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Purpose: To compare the difference of angle of the lower portion of the posterior cruciate ligament (PCL) measured via magnetic resonance imaging (MRI) in patients with and without partial anterior cruciate ligament (ACL) tears and to investigate the effectiveness of the angle of the lower portion of the PCL in diagnosing partial ACL tears. Methods: From January 2022 to December 2022, a cohort of consecutive patients presenting with ACL tears who underwent ACL reconstruction and patients with isolated meniscus tears undergoing arthroscopic surgery were enroled for this study. The angle of the inferior portion of the PCL comprises α and β angles, and the posterior offset of the lateral condyle were measured on the MRI and compared between the partial ACL tear and control groups. Receiver operating characteristic curves, the areas under the curve (AUCs) and the 95% confidence intervals (CIs) were calculated to identify cutoff values for diagnosing partial ACL injuries. Results: Following an assessment of cohort eligibility and matching for age and sex, 100 patients were included in this study. The mean age of the cohort was 46.1 ± 10.3 years. The AUC for the α angle was 0.88 (95% CI, 0.82–0.94), with a sensitivity of 0.74 and specificity of 0.84 for predicting partial ACL ruptures; the α angle cutoff value was 73.6° (diagnostic odds ratio (OR), 14.10; 95% CI, 5.33–37.28). The AUC for the β angle was 0.86 (95% CI, 0.79–0.93), with a sensitivity of 0.64 and a specificity of 0.92 for predicting partial ACL ruptures; the β angle cutoff value was 73.3° (diagnostic OR, 14.54; 95% CI, 5.76–36.68). Conclusions: A small α angle and a large β angle were associated with partial ACL tears. The angle of the distal portion of the PCL was simple to measure and reproducible, enhancing the diagnosis of partial ACL tears. Level of Evidence: Level III. [ABSTRACT FROM AUTHOR]

Purpose: The medial synovial fold of the posterior cruciate ligament is one of the synovial plicae of the knee joint. The objective of this study was to assess the necessity of reporting the appearance of the medial synovial fold of the posterior cruciate ligament on magnetic resonance imaging of the knee joint and its correlation with side and sex. Methods: Patients with normal knee structure on magnetic resonance imaging (MRI) scans between 2018 and 2023 were included in this retrospective study. MRI scans of the knee joints were retrospectively reviewed by two musculoskeletal radiologists independently. The medial synovial fold of the posterior cruciate ligament was divided into three types according to the imaginary line drawn between the lateral border of the medial femoral condyle and the medial tibial intercondylar tubercle. Results: The study included 1147 patients, of whom 478 (41.7%) were female and 669 (58.3%) were male. Among these patients, 580 (50.6%) had a right knee scan, and 567 (49.4%) had a left knee scan. The age range was 15–35 years for both sexes. The frequency of the medial synovial fold types in all patients was as follows: Type A (30.1%), Type B (55.4%) and Type C (14.5%). There was a high level of agreement between the observers. There was a statistically significant difference in the frequency of medial synovial fold types between sexes, with men exhibiting a greater prevalence. Conclusion: Magnetic resonance imaging (MRI) of the knee joint revealed the medial synovial folds of the posterior cruciate ligament (PCL). The most common was Type B (55.4%), followed by Type A (30.1%) and Type C (14.5%) among the MSF types. No statistically significant difference was found between the right and left knees for any of the MSF types. [ABSTRACT FROM AUTHOR]

Objectives: To evaluate the type and prevalence of associated injuries by using magnetic resonance imaging (MRI) in patients with anterior cruciate ligament (ACL) tears. Methods: Data from the Natural Corollaries and Recovery after ACL injury multicenter longitudinal cohort study were analyzed. Between May 2016 and October 2018, patients aged between 15 and 40 years, who had experienced an ACL tear within the last 6 weeks and sought medical attention at one of seven healthcare clinics in Sweden, were invited to participate. The mean time from injury to MRI was 19.6 ± 15.2 days. An orthopedic knee surgeon and a musculoskeletal radiologist reviewed all the MRI scans. The following structures were assessed: posterior cruciate ligament (PCL), medial collateral ligament (MCL) complex, lateral collateral ligament (LCL), popliteus tendon, medial meniscus (MM), lateral meniscus (LM), and cartilage. In addition, the presence of bone bruising, impaction fractures in the lateral femoral condyle (LFC) or posterolateral tibia (PLT), and Segond fractures were also assessed. Results: A total of 254 patients (48.4% males) with a mean age of 25.4 ± 7.1 years were included. The prevalence of associated injuries was as follows: PCL (0.4%), MCL {41.3% [superficial MCL and deep MCL (dMCL) 16.5%; isolated dMCL 24.8%]}, LCL (2.4%), MM (57.4%), LM (25.2%), cartilage (15.0%), bone bruising (92.9%), impaction fracture in the LFC (45.7%) and PLT (4.7%), and Segond fracture (7.5%). Conclusions: The prevalence of associated injuries in patients with ACL tears was high. The findings reported in this study may serve as a reference tool for orthopedic surgeons and radiologists in the diagnosis of associated injuries using MRI in patients with ACL tears. [ABSTRACT FROM AUTHOR]

ABSTRACT Estimation of the knee joint strength by maximum voluntary isometric contraction (MVIC) is a common practice to assess strength, coordination, safety to return to work or engage in sports after an injury, and to evaluate the efficacy of treatment modalities and rehabilitation strategies. In this study, we utilize a previously validated coupled finite element‐musculoskeletal model of the lower extremity to explore the sensitivity of output measures (posterior cruciate ligament [PCL]/muscle/contact forces and passive moments) in knee MVIC flexion exercises at seated position. To do so, at three knee flexion angles (KFA), input measures (resistance moment and contribution moments of quadriceps and gastrocnemii) were varied at four levels each using the Taguchi design of experiment. Our findings reveal significant increases in PCL forces with KFA (p < 0.01), net MVIC moment (p < 0.01), and resistance moment of quadriceps (p < 0.01). In contrast, they drop at larger activity in gastrocnemii (p < 0.01). Tibiofemoral (TF) contact forces increase with the net MVIC moment (p < 0.01). The passive knee flexion moment, while highly dependent on the location at which computed, also increases with the net MVIC moment (p < 0.01). Changes in KFA, MVIC moment, and proportions thereof carried by quadriceps and/or gastrocnemii substantially affect biomechanics of the joint. Compared with level walking and stair ascent, slightly larger contact forces/stresses and much greater PCL forces are computed. This study improves our understanding of the knee joint behavior during MVIC in effective evaluation and rehabilitation interventions. Besides, it emphasizes the importance of positioning the joint center in model studies. [ABSTRACT FROM AUTHOR]

Background: Our study aims to examine stress–strain data of the four major knee ligaments—the anterior cruciate ligament (ACL), the posterior cruciate ligament (PCL), the medial collateral ligament (MCL), and the lateral collateral ligament (LCL)—under transient impacts in various knee joint regions and directions within the static standing position of the human body. Subsequently, we will analyze the varying biomechanical properties of knee ligaments under distinct loading conditions. Methods: A 3D simulation model of the human knee joint including bone, meniscus, articular cartilage, ligaments, and other tissues, was reconstructed from MRI images. A vertical load of 300 N was applied to the femur model's top surface to mimic the static standing position, and a 134 N load was applied to the impacted area of the knee joint. Nine scenarios were created to examine the effects of anterior, posterior, and lateral external forces on the upper, middle, and lower regions of the knee joint. Results: The PCL exhibited the highest stress levels among the four ligaments when anterior loads were applied to the upper, middle, and lower parts of the knee, with maximum stresses at the PCL-fibula junction measuring 59.895 MPa, 27.481 MPa, and 28.607 MPa, respectively. Highest stresses on the PCL were observed under posterior loads on the upper, middle, and lower knee areas, with peak stresses of 57.421 MPa, 38.147 MPa, and 26.904 MPa, focusing notably on the PCL-tibia junction. When a lateral load was placed on the upper knee joint, the ACL showed the highest stress 32.102 MPa. Likewise, in a lateral impact on the middle knee joint, the ACL also had the highest stress of 29.544 MPa, with peak force at the ACL-tibia junction each time. In a lateral impact on the lower knee area, the LCL had the highest stress of 22.279 MPa, with the highest force at the LCL-fibula junction. Furthermore, the maximum stress data table indicates that stresses in the ligaments are typically higher when the upper portion of the knee is affected compared to when the middle and lower parts are impacted. Conclusions: This study recommends people avoid impacting the upper knee and use the middle and lower parts of the knee effectively against external forces to minimize ligament damage and safeguard the knee. [ABSTRACT FROM AUTHOR]

Introduction: The posterior meniscofemoral ligament (pMFL) of knee joint is a ligament that runs posterior to the posterior cruciate ligament and it is known that the height of the pMFL attachment site causes meniscus avulsion. Therefore, understanding the three-dimensional (3D) structure of the pMFL attachment site is essential to better understand the pathogenesis of meniscus disorders. However, the developmental process of pMFL has not been well investigated. The purpose of this study was to analyze pMFL development in rat knee joints using 3D reconstructed images produced from episcopic fluorescence image capture (EFIC) images and examine its relationship with other knee joint components. Methods: Knee joints of Wistar rat embryos between embryonic day (E) 16 and E21 were observed with HE-stained tissues. Serial EFIC images of the hind limbs of E17–E21 were, respectively, captured from which 3D images were reconstructed and the features of pMFL structure: length and angle were measured. Besides, the chronological volume changes and the volume ratio of the knee joint components compared to E17 were calculated to identify the differences in growth by components. Results: pMFL was observed from E17 and was attached to the medial femoral condyle and lateral meniscus at all developmental stages, as in mature rats. The lack of marked variation in the attachment site and angle of the pMFL with the developmental stage indicates that the pMFL and surrounding knee joint components developed while maintaining their positional relationship from the onset of development. Conclusion: Current results may support to congenital etiology of meniscus disorder. [ABSTRACT FROM AUTHOR]

Background: This study aimed to investigate the expression of vascular endothelial growth factor (VEGF) in cruciate ligaments from patients with osteoarthritis (OA). It was hypothesized that the expression level of VEGF is associated with the extent of degeneration of the cruciate ligaments. Methods: Remnants of anterior cruciate ligaments (ACLs) from patients with acute ACL injury due to trauma, and ACLs and posterior cruciate ligaments (PCLs) from patients with primary OA were assessed histologically. Samples were immunohistochemically stained with VEGF and tenomodulin, and immunopositive cells were quantitatively assessed by the histological grades of ligament degeneration. Results: Histological analysis showed significant degeneration of the ACLs from OA patients compared with trauma patients, with increased expression of VEGF correlating with higher grades of degeneration. Conversely, tenomodulin expression was lower in more degenerated cruciate ligaments. The percentage of VEGF-positive cells was correlated inversely with that of tenomodulin-positive cells. Conclusions: Increased VEGF expression is associated with degeneration of cruciate ligaments in patients with osteoarthritis of the knee. [ABSTRACT FROM AUTHOR]

Purpose Methods Results Conclusion Level of Evidence Similar to the anterior cruciate ligament, the femoral footprint of the posterior cruciate ligament (PCL) is composed of different fibre areas, possibly having distinct biomechanical functions. The aim of this study was to determine the role of different fibre areas of the femoral footprint of the PCL in restraining posterior tibial translation (PTT).A sequential cutting study was performed on eight fresh‐frozen human knee specimens, utilizing a six‐degrees‐of‐freedom robotic test setup. The femoral attachment of the PCL was divided into 15 areas, which were sequentially cut from the bone in a randomized sequence. After determining the native knee kinematics, a displacement‐controlled protocol was performed replaying the native motion, while constantly measuring the force. The reduction of the restraining force presented the percentage contribution of each cut, according to the principle of superposition.The PCL was found to contribute 29 ± 16% in 0°, 51 ± 24% in 30°, 60 ± 22% in 60° and 55 ± 18% in 90°, to restricting a PTT. The fibre areas contributing the most were located at the proximal border of the PCL footprint, away from the cartilage, and directly adjacent to the medial intercondylar ridge (p < 0.05). Of these, one fibre area showed the highest contribution at all flexion angles. This area was located at the posterior half of the medial intercondylar ridge. No clear assignment of the areas to either the anterolateral or posteromedial bundle was possible.An area towards the proximal and posterior part of the femoral PCL footprint was found to significantly restrain a posterior tibial force. Based on the data of this testing setup, a PCL graft positioned at the identified area may best mimic the part of the native PCL, which bears the most load in resisting a PTT force.No evidence level (laboratory study). [ABSTRACT FROM AUTHOR]

Purpose Methods Results Conclusion Level of Evidence Posterior stress radiography is recommended to identify isolated or combined posterior cruciate ligament (PCL) deficiencies. The posterior drawer in internal (IR) or external rotation (ER) helps to differentiate between these combined instabilities. The purpose of this study was to evaluate posterior stress radiography (PSR) in isolated and combined PCL deficiency with IR and ER compared to PSR in neutral rotation (NR) for diagnosing combined PCL instabilities.Six paired fresh‐frozen human cadaveric legs (n = 12) were mounted in a Telos device for PSR. The tibia was rotated using an attached foot apparatus capable of rotating the foot 30° internally and externally. A posterior tibial load of 15 kp (147.1 N) was applied to the tibial tubercle at 90° knee flexion, and a lateral radiograph was obtained. This was repeated with the foot in 30° IR and ER. The PCL, posterolateral complex (PLC), and posteromedial complex (PMC) were sectioned in six knees, while the PMC was sectioned before the PLC in the other six knees. Posterior tibial displacement (PTD) was measured radiographically. Statistical analysis was performed using a two‐way ANOVA and a mixed model with Bonferroni correction, and the significance was set at p < 0.05. Furthermore, intra‐ and interobserver reliability was determined.Cutting the PCL significantly increased the radiographic PTD by 9.8 ± 1.8 mm (side‐to‐side difference compared to the intact state of the knee, n = 12; p < 0.001). This further increased to 12.2 ± 2.3 mm (n = 6; p < 0.01) with an additional PLC deficiency and to 15.4 ± 3.4 mm (n = 6; p < 0.05) with an additional PMC deficiency. A combined PLC and PMC deficiency resulted in an increase of the PTD to 15.9 ± 4.5 mm (n = 12; p < 0.01). In the PCL/PLC deficient state, ER did not demonstrate a higher PTD, compared to the NR and IR posterior drawer. In the PCL/PMC deficient state in IR, PTD was 1.6 ± 0.7 mm (p < 0.01) higher compared to NR and 3.2 ± 1.9 mm (p < 0.05) higher compared to ER. We showed excellent intra‐ and interobserver reliability (0.987–0.997).Combined PCL instabilities resulted in a significant increase in posterior tibial displacement in posterior stress radiographs. However, PSR in IR or ER was unable to differentiate between these combined instabilities. Based on our data, additional stress radiographs in rotation are unlikely to provide any diagnostic benefit in the clinical setting.There is no level of evidence as this study was an experimental laboratory study. [ABSTRACT FROM AUTHOR]

The objective of this study was to assess radiolucent lines (RLLs) and to determine their effect on clinical outcomes of the newly introduced cementless mobile-bearing total knee arthroplasty (TKA) system. This was prospective, multicentre study. Seventy-eight patients with knee osteoarthritis who underwent primary TKA were enrolled. Patient-reported outcome measures (PROMs) and radiographic assessments were evaluated at preoperative baseline and at 6 weeks, 1 year, and 2 years after surgery. KOOS, PKIP, 2011KSS, EQ-5D-3L and SKO improved from preoperative baseline to all postoperative timepoints, with no loosening of components. No RLLs were detected at 6 weeks after surgery. However, RLLs ≥ 1 mm developed in 2.8% of the patients for the femur and 9.7% for the tibia at 1 year after surgery, and values were 5.7% and 10.9%, respectively, at 2 years after surgery. RLL incidence was not correlated with PROMs. Age, sex, body mass index, range of motion knee flexion, posterior cruciate ligament treatment and β angle did not impact the occurrence of RLLs. There were no intraoperative complications, revisions or reoperations. This TKA system improved PROMs and showed less incidence of RLLs compared to the previous reported TKA without implant-related complications. [ABSTRACT FROM AUTHOR]

Current surgical practices in total knee arthroplasty (TKA) have advanced and include significant changes and improvements in alignment philosophies, femorotibial implant conformities, and ligament management to replicate in vivo knee kinematics. While corrective measures have emphasized sagittal plane alignment to restore normal flexion–extension (F–E) motion and coronal plane ligament balance, internal–external (I–E) rotation kinematics in the axial plane have been largely neglected. Recent in vivo evidence indicates that the combination of factors necessary to closely restore native tibial rotation as the knee flexes and extends is kinematic alignment (KA), which resurfaces the patient's pre-arthritic knee without releasing ligaments, an insert with medial 1:1 ball-in-socket conformity and a lateral flat surface, and posterior cruciate ligament (PCL) retention. However, the inherent anterior–posterior (A–P) stability provided by the medial 1:1 ball-in-socket limits the surgeon's ability to select the correct insert thickness using manual laxity testing. Accordingly, this review presents the design and validation of an instrument called an insert goniometer that measures I–E tibial rotation for inserts that differ in thickness by 1 mm and uses rotation limits at extension and 90° flexion to select the optimal insert thickness. The optimal thickness is the one that provides the greatest external tibial orientation in extension and internal tibial orientation at 90° flexion without lift-off of the insert. [ABSTRACT FROM AUTHOR]

BACKGROUND: A gradually reducing radius (GRADIUS) design implant can facilitate a smooth transition from stability through full range of motion in total knee arthroplasty (TKA). Nonetheless, patient-specific factors associated with good knee flexion remain unclear. OBJECTIVE: This study aimed to determine the factors associated with good knee flexion after cruciate-retaining TKA with a GRADIUS prosthesis in an Asian population. METHODS: This retrospective study included 135 patients that were stratified according to postoperative knee flexion angle (KFA) into Group F (⩾ 120∘; 85 patients [63.2%]) and Group NF (< 120∘; 50 patients [36.8%]). RESULTS: Patients in Group F were taller and had a lower body mass index (BMI) smaller preoperative hipkneeankle angle and better preoperative extension and flexion angle than Group NF patients. The multivariable analysis revealed that patients' height (odds ratio [OR]: 1.07, P = 0.0150), BMI (OR: 0.85, P = 0.0049), and preoperative flexion angle (OR: 1.06, P = 0.0008) predicted good KFA. The ROC curve analysis showed that the cutoff values of a good KFA were height 155.1 cm, BMI 22.1 kg/m2, and preoperative KFA 120∘. CONCLUSIONS: Patient height, BMI, and preoperative KFA were independent factors affecting good postoperative KFA in patients of Asian descent who underwent cruciate-retaining TKA with a GRADIUS design. [ABSTRACT FROM AUTHOR]

Purpose: Resecting the posterior cruciate ligament (PCL) increases posterior laxity and increases the flexion gap more than the extension gap in the native (i.e. healthy) knee. These two effects could lead to significant anterior displacement of the medial femoral condyle in kneeling following total knee arthroplasty even when using a tibial insert with a high degree of medial conformity. Using an insert with ball-in-socket medial conformity and a flat lateral articular surface, the primary purpose was to determine whether the medial femoral condyle remained stable with and without PCL retention during kneeling. Methods: Two groups of patients were studied, one with PCL retention (22 patients) and the other with PCL resection (25 patients), while kneeling at 90º flexion. Following 3D model-to-2D image registration, A-P displacements of both femoral condyles were determined relative to the dwell point of the medial socket. Results: With PCL resection versus PCL retention, the medial femoral condyle was 5.1 ± 3.7 mm versus 0.8 ± 2.1 mm anterior of the dwell point (p < 0.0001). Patient-reported function scores were comparable (p ≥ 0.1610) despite a significantly shorter follow-up of 7.8 ± 0.9 months with PCL retention than 19.6 ± 4.9 months with PCL resection (p < 0.0001). Range of motion was 126 ± 8° versus 122 ± 6° with and without PCL retention, respectively (p = 0.057). Conclusion: Surgeons that use a highly conforming tibial insert design can stabilize the medial femoral condyle during kneeling by retaining the PCL. In patients with PCL resection, the 9 mm high anterior lip of the insert with ball-in-socket medial conformity was insufficient to prevent significant anterior displacement of the medial femoral condyle when weight-bearing on the anterior tibia. [ABSTRACT FROM AUTHOR]

Introduction: Multi-ligament knee injuries (MLKIs) are rare and complex knee lesions and are potentially associated with intra-articular injuries, especially meniscal tears. Understanding the meniscal tear patterns involved in MLKI can help the orthopedic surgeon treat these complex injuries. Objective: The purpose of this study was to describe the incidence, classification, and treatment of meniscal injuries in a cohort of patients with MLKIs and carry out an updated review of the evidence available. Materials and methods: Descriptive retrospective study. Patients with a history of reconstructive surgery for MLKI performed between 2013 and 2023 were included. Informed consent was obtained from all patients included in the study. Patient demographics, magnetic resonance imaging (MRI) study, and operative reports were reviewed. Groups were then formed based on ligament injury patterns. Meniscal tears were identified by MRI and through diagnostic arthroscopy for each patient. The association between meniscal lesions and injury patterns was calculated through Fisher's exact test. Agreement between the presence of meniscal tear on MRI and in diagnostic arthroscopy was measured using the kappa test. The sensitivity and specificity of MRI were calculated. We inferred the presence of a meniscal tear by injury pattern using the Agresti-Coull confidence interval. For the statistical analysis, a significance of 5% and a confidence interval of 95% were considered. Results: Seventy patients with MLKIs were included, with a mean age of 30.69 years (SD 10.65). Forty-seven patients had meniscal lesions (67.1%). Of them, 6 had only medial meniscus tears, 31 had only lateral meniscus tears, and 10 had lesions of both menisci, comprising 57 meniscal lesions in total. An anterior cruciate ligament (ACL) + medial collateral ligament/posteromedial corner (MCL/PMC) was the most common injury pattern (52.86% of all patients). Of these 37 patients, 78.38% had meniscal injuries, and most of them (68.97%) were only lateral meniscus injuries. The odds ratio (OR) of having a meniscal tear when having an ACL + medial-side injury was 4.83 (95% CI; 0.89–26.17). Patients with ACL + lateral-side injury pattern had meniscal tears in 42.86%. The lateral meniscus was involved in 100% of these patients. 62.5% of medial meniscus injuries were treated by meniscal repair, and 37.5% by partial meniscectomy. 58.54% of lateral meniscus injuries were treated by meniscal repair, and 39.02% by partial meniscectomy. Agreement calculated using the kappa test between MRI and diagnostic arthroscopy for medial meniscal lesions was 78.57%, and for lateral meniscal lesions was 84.29%. Conclusion: The ligament injury pattern and the side of the injured collateral ligament influenced the incidence and laterality of meniscal damage. ACL + medial-side injuries were shown to have significantly greater meniscal damage compared to other injury patterns. It is crucial to have a high index of suspicion, obtain a high-quality MRI, and arthroscopically evaluate any possible meniscal lesions in MLKIs. [ABSTRACT FROM AUTHOR]

Background and Purpose: The comprehensive treatment for an athlete who sustains a complete posterior cruciate ligament (PCL) injury remains unclear. The purpose of this case report is to describe the effects of an isokinetic exercise program on muscle performance and physical function in a professional soccer player with a PCL injury. Study Design: Case Report Case Description: A 23-year-old male professional soccer player injured his right knee (non-dominant) during a soccer match, with magnetic resonance imaging confirming a complete PCL rupture. The athlete completed 23 sessions of isokinetic treatment over nine weeks to improve physical function and muscle performance. The concentric mode was used to evaluate quadriceps and hamstrings performance isokinetically at angular velocities of 60 °/s, 120 °/s, and 300 °/s. The LEFS questionnaire was used to evaluate physical function. The assessment occurred before starting the treatment and at the end of nine weeks. An athlete with similar anthropometric characteristics was invited to participate and serve as a control, in order to better understand the athlete's assessment results. Outcomes: After nine weeks, peak torque normalized to body mass (PT/BM) improved to 4.0 N.m/kg for knee extensors (control: 3.6 Nm/kg) and 2.3 N.m/kg for knee flexors (control: 1.9 Nm/kg) at 60 °/s. This increase in PT was reflected in the hamstrings-to-quadriceps (H:Q) ratio post-treatment (57 %). At the end of treatment, the athlete returned to sports activities with 98.7 % restored physical function as measured by the LEFS (Score: 79 points). Discussion: The results demonstrated that the isokinetic treatment improved knee functional capacity, with increased PT/BM for knee extensors and flexors and enhanced torque-holding capacity, indicating improved muscle performance. Level of evidence: 5 [ABSTRACT FROM AUTHOR]

Abstract Background We report a rare case of posterior cruciate ligament (PCL) calcification, which has only been reported in two case studies on PubMed. Case presentation A 71-year-old man developed left popliteal pain in the morning without any history of trauma and the pain became severe that night. On the following day, he presented to our department. The patient could not flex his left knee at all due to pain and swelling. CT and MRI scans showed calcification behind the PCL with mild osteoarthritic changes and accumulation of synovial fluid in the joint. Synovial fluid analysis did not reveal any crystals. Blood tests at first admission showed inflammation, hyperglycemia, and low blood uric acid levels. Although the patient’s knee joint was injected with steroids, his symptoms did not improve. Thus, we performed arthroscopic surgery two days after symptoms had appeared. Intraoperatively, we observed a white, soft tissue in the synovial membrane behind the PCL. Part of this tissue was collected for histological analysis, which revealed sparse fibers with calcium deposits. Immediately after surgery, the patient’s symptoms were completely gone. Afterward, the patient remained asymptomatic one month after surgery. Conclusion This is the first reported case of debridement of PCL calcification and ossification that was performed soon after symptoms appeared. In addition, we demonstrated that early debridement led to complete recovery.

Abstract Purpose The posterior cruciate ligament (PCL) is a vital knee stabilizer. While PCL injuries are rare, high-energy traumas can lead to total ruptures, with accompanying injuries requiring surgery. This study aims to investigate the demographics, concomitant injuries, and postoperative complications of patients who underwent PCL reconstruction due to high-energy trauma in a large patient sample. Methods Patients who underwent PCL reconstruction from 2016 to 2022 were retrospectively evaluated using data from a nationwide personal health recording system. Patient demographics, injury mechanisms, associated fractures, soft tissue injuries, and postoperative complications were collected from patient notes, clinical visits, and surgical notes. Individuals with a PCL injury following high-energy trauma (car accident, falls from height, motorcycle accident) with a minimum follow-up of 1 year were included in the study. Results The study included 416 patients with a mean age of 32.4 years. Isolated PCL injuries (n = 97, 23.3%) were observed less frequently than multiple-ligament injuries (n = 319, 76.7%). Most cases were treated with single-stage surgery (86.8%), while staged surgeries were performed in a minority of cases (13.2%). There was no relationship between trauma mechanisms and multiple-ligament involvement, accompanying injuries, or postoperative complications. Surgeries following car accidents were more likely to occur as staged surgeries (p = 0.014). Additionally, the complication rates for staged surgeries and younger patients (≤ 18 years) were significantly higher (p = 0.009). Conclusion High-energy trauma-induced PCL injuries are often associated with severe concurrent knee injuries with multiple ligament involvement. PCL reconstructions following car accidents are more likely to be staged. These findings highlight the importance of careful consideration in managing these cases to minimize complications, particularly in younger age groups. Level of evidence Level III.

Objective Retention or sacrifice of the posterior cruciate ligament (PCL) is one of the most controversial issues while performing total knee arthroplasty (TKA). This study aimed to evaluate the impact of PCL resection on flexion–extension gaps, femoral component rotation, and bone resection amounts during robot‐assisted TKA. Methods This prospective study included 40 patients with knee osteoarthritis who underwent robot‐assisted posterior‐stabilized (PS) TKA between September 2021 and February 2022. Of the patients, 75% were women (30/40) with a mean age and BMI of 72.6 years and 27.4 kg/m2, respectively. The guidance module and camera stand assembly were used to capture gaps before and after PCL resection. Measurements of femoral component rotation and bone resection amounts were made in cruciate‐retaining (CR) TKA mode and PS‐TKA mode. Results After PCL resection, the mean change in the medial and lateral compartments of flexion gaps increased by 2.0 and 0.6 mm, respectively (p

Introduction Total knee arthroplasty (TKA) is the most effective treatment of late osteoarthritis (OA) and is considered among the most successful surgical procedures in general. However, about 20% of patients remain dissatisfied. An important aspect of TKA is the proper choice of implant type – posterior stabilized (PS) or cruciate retaining (CR). Both have their indications for use based on intraoperative functional examination, but no objective radiological criteria have yet been developed. The aim of this study was to investigate the relationship between the posterior subluxation of the tibia on preoperative radiograms and implant type used. Material and methods A series of 52 patients undergoing TKA were included in the study. All patients were over 50 years old, had clinically and radiologically confirmed primary OA of grade IV on the Kellgren-Lawrence scale and were undergoing a primary total knee replacement (TKR) with a PS or CR design. Preoperative lateral radiographs were analysed retrospectively. The tibial translation ratio was calculated as a percentage of subluxation in the length of the tibial plateau. Results There were no significant differences between implant types in regard to investigated parameters. However, there was a significant difference between the groups CR and PS in regard to age (68.5 [60.0–72.0] vs. 72.5 [68.0–75.0], p = 0.006). Conclusions This study revealed that preoperative tibial translation does not significantly correlate with the choice of implant type and so probably not with posterior cruciate ligament (PCL) function and efficiency either. Additionally, this study showed that PCL insufficiency is related to the age of the patients, because of the more frequent choice of the PS implant type for the surgery in older patients than in the case of the CR implant type.

Abstract Purpose To assess the clinical efficacy of arthroscopic treatment for posterior cruciate ligament (PCL) tibial avulsion fractures using high-intensity suture binding combined with button plate suspension fixation. Methods We retrospectively analyzed clinical data from 32 patients with PCL tibial avulsion fractures treated at our hospital from July 2020 to August 2023. We recorded operation time, intraoperative and postoperative complications, and used imaging to assess fracture reduction and healing. Pain and knee function were evaluated using the Visual Analogue Scale (VAS), range of knee motion, Lysholm score, and International Knee Documentation Committee (IKDC) score. Study Design Case series; Level of evidence, 4. Results All patients were followed for 6 to 18 months, averaging 13.6 months. All incisions healed successfully without postoperative complications. X-rays taken on the first postoperative day showed satisfactory fracture reduction. Three-month post-surgery imaging confirmed healed fractures and no internal fixation failures. At the final follow-up, knee function was well recovered, with only one patient exhibiting a positive posterior drawer test of degree I. Furthermore, the mean VAS score was 0. 5 (range 0.0 to 1.0), active knee extension was 2. 2° (range 0.0 to 5.0), and active knee flexion was 137.7° (range 130.0 to 145.0). The mean Lysholm score was 91.5(range 89.3 to 94.0), and the IKDC score averaged 83.8 ± 3.7, and these outcomes showed statistically significant improvement from preoperative levels (P

Objective Predicting whether the posterior cruciate ligament (PCL) should be preserved during total knee arthroplasty (TKA) procedures is a complex task in the preoperative phase. The choice to either retain or excise the PCL has a substantial effect on the surgical outcomes and biomechanical integrity of the knee joint after the operation. To enhance surgeons' ability to predict the removal and retention of the PCL in patients before TKA, we developed machine learning models. We also identified significant feature factors that contribute to accurate predictions during this process. Methods Patients' data on TKA continuously performed by a single surgeon who had intended initially to undergo implantation of cruciate‐retaining (CR) prostheses was collected. During the sacrifice of PCL, we utilized anterior‐stabilized (AS) tibial bearings. The dataset was split into CR and AS categories to form distinct groups. Relevant information regarding age, gender, body mass index (BMI), the affected side, and preoperative diagnosis was extracted by reviewing the medical records of the patients. To ensure the authenticity of the research, an initial step involved capturing X‐ray images before the surgery. These images were then analyzed to determine the height of the medial condyle (MMH) and lateral condyle (LMH), as well as the ratios between MLW and MMH and MLW and LMH. Additionally, the insall‐salvati index (ISI) was calculated, and the severity of any varus or valgus deformities was assessed. Eight machine‐learning methods were developed to predict the retention of PCL in TKA. Risk factor analysis was performed using the SHApley Additive exPlanations method. Results A total of 307 knee joints from 266 patients were included, among which there were 254 females and 53 males. A stratified random sampling technique was used to split patients in a 70:30 ratio into a training dataset and a testing dataset. Eight machine‐learning models were trained using data feeding. Except for the AUC of the LGBM Classifier, which is 0.70, the AUCs of other machine learning models are all lower than 0.70. In importance‐based analysis, ISI, MMH, LMH, deformity, and age were confirmed as important predictive factors for PCL retention in operations. Conclusion The LGBM Classifier model achieved the best performance in predicting PCL retention in TKA. Among the potential risk factors, ISI, MMH, LMH, and deformity played essential roles in the prediction of PCL retention.

Background: We report a rare case of posterior cruciate ligament (PCL) calcification, which has only been reported in two case studies on PubMed. Case presentation: A 71-year-old man developed left popliteal pain in the morning without any history of trauma and the pain became severe that night. On the following day, he presented to our department. The patient could not flex his left knee at all due to pain and swelling. CT and MRI scans showed calcification behind the PCL with mild osteoarthritic changes and accumulation of synovial fluid in the joint. Synovial fluid analysis did not reveal any crystals. Blood tests at first admission showed inflammation, hyperglycemia, and low blood uric acid levels. Although the patient's knee joint was injected with steroids, his symptoms did not improve. Thus, we performed arthroscopic surgery two days after symptoms had appeared. Intraoperatively, we observed a white, soft tissue in the synovial membrane behind the PCL. Part of this tissue was collected for histological analysis, which revealed sparse fibers with calcium deposits. Immediately after surgery, the patient's symptoms were completely gone. Afterward, the patient remained asymptomatic one month after surgery. Conclusion: This is the first reported case of debridement of PCL calcification and ossification that was performed soon after symptoms appeared. In addition, we demonstrated that early debridement led to complete recovery. [ABSTRACT FROM AUTHOR]

Purpose Methods Results Conclusion Study Design Level of Evidence The aberrant anterior tibial artery (ATA) runs along the posterior surface of the tibial cortex making it, particularly, at risk during high tibial osteotomy (HTO). This study aimed to analyze the prevalence of the ATA according to global morphotype and its anatomical features in consideration of knee surgery.This retrospective study included 1589 knees on magnetic resonance imaging (MRI) studies with long‐leg radiographs. The anatomical characteristics of the ATA, its distance in surgical areas at risk and its lumen were defined on MRI. Its presence according to the patient's morphotype (varus, valgus or neutral) was assessed using a χ2 test.The ATA was present in 33 of 1589 knees, resulting in a prevalence of 2.1%. The anteroposterior distance of the ATA to the tibial head was 6.6 ± 2.5 mm at the height of the tibial plateau, 2.7 ± 1.6 mm at the footprint of the posterior cruciate ligament and 1.0 ± 0.6 mm under the top of the fibula (p < 0.01). For these three levels, the ratio between the distance from the ATA to the lateral tibial border and the total tibial width decreases progressively (p < 0.001). The mean lumen area of the ATA was 4.2 ± 2.5 mm2, and the lumen of the popliteal artery was 9.2 ± 3.6 mm2, representing a ratio of 49.4 ± 27.0%. The prevalence of ATA was similar between varus and valgus patients (n.s).The presence of an ATA is rare, found in one out of 50 cases, but can be easily identified on MRI in patients before knee surgery, especially before HTO. The patient's morphotype did not influence its presence, the lumen diameter is highly variable and its clinical impact has yet to be determined.Cross‐sectional study.Level 3. [ABSTRACT FROM AUTHOR]

Background: Knee instability in midflexion may contribute to patient dissatisfaction following total knee arthroplasty (TKA). Midflexion instability involves abnormal motions and tissue loading in multiple planes. Therefore, we quantified and compared the tensions carried by the medial and lateral collateral ligaments (MCL and LCL) following posterior-stabilized (PS) TKA through knee flexion, and then compared these tensions with those carried by the native knee. Finally, we examined the relationships between collateral ligament tensions and anterior tibial translation (ATT). Methods: Eight cadaveric knees (from 5 male and 3 female donors with a mean age of 62.6 years and standard deviation of 10.9 years) underwent PS TKA. Each specimen was mounted to a robotic manipulator and flexed to 90°. ATT was quantified by applying 30 N of anterior force to the tibia. Tensions carried by the collateral ligaments were determined via serial sectioning. Robotic testing was also conducted on a cohort of 15 healthy native cadaveric knees (from 9 male and 6 female donors with a mean age of 36 years and standard deviation of 11 years). Relationships between collateral ligament tensions during passive flexion and ATT were assessed via linear and nonlinear regressions. Results: MCL tensions were greater following PS TKA than in the native knee at 15° and 30° of passive flexion, by a median of ≥27 N (p = 0.002), while the LCL tensions did not differ. Median tensions following PS TKA were greater in the MCL than in the LCL at 15°, 30°, and 90° of flexion, by ≥4 N (p ≤ 0.02). Median tensions in the MCL of the native knee were small (≤11 N) and did not exceed those in the LCL (p ≥ 0.25). A logarithmic relationship was identified between MCL tension and ATT following TKA. Conclusions: MCL tensions were greater following PS TKA with this typical nonconforming PS implant than in the native knee. Anterior laxity at 30° of flexion was highly sensitive to MCL tension during passive flexion following PS TKA but not in the native knee. Clinical Relevance: Surgeons face competing objectives when performing PS TKA: they can either impart supraphysiological MCL tension to reduce anterior-posterior laxity or maintain native MCL tensions that lead to heightened anteriorposterior laxity, as shown in this study. [ABSTRACT FROM AUTHOR]

Purpose: The posterior cruciate ligament (PCL) is a vital knee stabilizer. While PCL injuries are rare, high-energy traumas can lead to total ruptures, with accompanying injuries requiring surgery. This study aims to investigate the demographics, concomitant injuries, and postoperative complications of patients who underwent PCL reconstruction due to high-energy trauma in a large patient sample. Methods: Patients who underwent PCL reconstruction from 2016 to 2022 were retrospectively evaluated using data from a nationwide personal health recording system. Patient demographics, injury mechanisms, associated fractures, soft tissue injuries, and postoperative complications were collected from patient notes, clinical visits, and surgical notes. Individuals with a PCL injury following high-energy trauma (car accident, falls from height, motorcycle accident) with a minimum follow-up of 1 year were included in the study. Results: The study included 416 patients with a mean age of 32.4 years. Isolated PCL injuries (n = 97, 23.3%) were observed less frequently than multiple-ligament injuries (n = 319, 76.7%). Most cases were treated with single-stage surgery (86.8%), while staged surgeries were performed in a minority of cases (13.2%). There was no relationship between trauma mechanisms and multiple-ligament involvement, accompanying injuries, or postoperative complications. Surgeries following car accidents were more likely to occur as staged surgeries (p = 0.014). Additionally, the complication rates for staged surgeries and younger patients (≤ 18 years) were significantly higher (p = 0.009). Conclusion: High-energy trauma-induced PCL injuries are often associated with severe concurrent knee injuries with multiple ligament involvement. PCL reconstructions following car accidents are more likely to be staged. These findings highlight the importance of careful consideration in managing these cases to minimize complications, particularly in younger age groups. Level of evidence: Level III. [ABSTRACT FROM AUTHOR]

Background: The diagnosis of anterior cruciate ligament (ACL) tear relies on clinical evaluation and magnetic resonance imaging (MRI). Direct and indirect signs of ACL tear have been described with MRI evaluation. Posterior cruciate ligament (PCL) buckling has been described as an indirect radiographic sign of an ACL tear. Purpose: The aim of the present study was to assess the variations in PCL buckling angles in patients with ACL tears and in patients with isolated lesions in the posterior horn of the medial meniscus. In addition, the influence of different patterns of medial meniscus tears in ACL-deficient knees was investigated. Finally, the influences of risk factors such as tibial slope, delay from injury to surgery, absence of medial meniscus tear, degree of Lachman and pivot shift testing were also assessed. Study design: This was a cohort study. Methods: A total of 154 patients (78 in the group with ACL tear and 76 in the control group) were assessed with MRI and lateral weight-bearing X-ray to assess PCL buckling angle and tibial slope by two independent observers. The presence of a medial meniscus bucket handle or ramp lesion of the medial meniscus was assessed and recorded at the time of surgery. Results: PCL buckling angle measurement was highly reliable, with an ICC of 0.866 and 0.894, respectively, in the study group and the control group for interobserver reliability. The intrarater reliability was found to be high in PCL buckling angle for the study group [ICC = 0.955] and the control group [ICC = 0.943]. The mean angle in patients with ACL tear was 110.7 ± 15.2° and 115.3 ± 16.2° (for the two examiners) and 111.4 ± 12° and 114 ± 14.5° (for the two examiners) in patients with an intact, healthy ACL. An association emerged between bucket handle tears of the medial meniscus (p = 0.010) and a decreased PCL buckling angle and between ramp lesions of the medial meniscus and increased PCL buckling angle both (p = 0.024). Conclusions: Good inter- and intraobserver reliability for the measurement of the PCL buckling angle was observed. Increased PCL buckling angle values were observed in patients with concomitant ACL and bucket handle tears of the medial meniscus, while decreased angle values were observed in those who had ACL tear and ramp lesion of the medial meniscus. No statistically significant difference in the PCL buckling angle emerged between patients with ACL tears and those who had a healthy, intact ACL. [ABSTRACT FROM AUTHOR]

A variety of total knee arthroplasty (TKA) designs offer increased congruency bearing options, primarily to compensate for a loss of posterior cruciate ligament (PCL) function. However, their efficacy in providing sufficient stability under different circumstances requires further investigation. The preclinical testing of prosthesis components on joint motion simulators is useful for quantifying how design changes affect joint stability. However, this type of testing may not be clinically relevant because surrounding ligaments are either ignored or greatly simplified. This study aimed to assess the kinematics and stability of TKA joints during various motions using condylar-stabilized (CS) bearings without a PCL versus cruciate-retaining (CR) bearings with an intact PCL. TKA prosthetic components were tested on a joint motion simulator while being stabilized with five different sets of specimen-specific virtual ligament envelopes. In comparison to CR knees, CS knees without a PCL exhibited a greater amount of posterior tibial displacement laxity, with a mean increase of 2.7±2.1 mm (p = 0.03). Additionally, significant differences were observed in the anterior–posterior kinematics of the knee joint during activities of daily living (ADL) between the two designs. These results were consistent with previous cadaveric investigations, which indicated that CS knees without a PCL are less resistant to posterior tibial displacement than CR knees with one. This study employing virtual ligaments confirms previous findings that the raised anterior lip of some CS bearings may not completely compensate for the absence of the PCL; however, as both studies used reduced joint contact forces, the contributions of this design feature may be attenuated. [ABSTRACT FROM AUTHOR]

Objective: Retention or sacrifice of the posterior cruciate ligament (PCL) is one of the most controversial issues while performing total knee arthroplasty (TKA). This study aimed to evaluate the impact of PCL resection on flexion–extension gaps, femoral component rotation, and bone resection amounts during robot‐assisted TKA. Methods: This prospective study included 40 patients with knee osteoarthritis who underwent robot‐assisted posterior‐stabilized (PS) TKA between September 2021 and February 2022. Of the patients, 75% were women (30/40) with a mean age and BMI of 72.6 years and 27.4 kg/m2, respectively. The guidance module and camera stand assembly were used to capture gaps before and after PCL resection. Measurements of femoral component rotation and bone resection amounts were made in cruciate‐retaining (CR) TKA mode and PS‐TKA mode. Results: After PCL resection, the mean change in the medial and lateral compartments of flexion gaps increased by 2.0 and 0.6 mm, respectively (p < 0.001). Compared with the CR‐TKA mode group, the bone resection amounts of the medial posterior condyle and the lateral posterior condyle in the PS‐TKA mode group decreased by 2.0 ± 1.1 and 1.1 ± 1.1 mm, respectively, and the external rotation of the femoral prosthesis relative to the posterior condylar axis and trans‐epicondylar line was reduced by 1.0° ± 1.3° and 1.2° ± 1.6°, respectively (p < 0.001). Conclusion: The release of the PCL did not affect the extension gap, but significantly increased the flexion gap. Moreover, the increases in the medial flexion gap were greater than those of the lateral flexion gap. After PCL resection, less external rotation of the femoral prosthesis and fewer bone cuts of the posterior femur were needed in PS‐TKA. [ABSTRACT FROM AUTHOR]

Polycaprolactone (PCL) implants in large animals show great promise for tracheal transplantation. However, the longest survival time achieved to date is only about three weeks. To meet clinical application standards, it is essential to extend the survival time and ensure the complete integration and functionality of the implant. Our study investigates the use of three-dimensional (3D)-printed, biodegradable, PCL-based tracheal grafts for large-scale porcine tracheal transplantation, assessing the feasibility and early structural integrity crucial for long-term survival experiments. A biodegradable PCL tracheal graft was fabricated using a BIOX bioprinter and transplanted into large-scale porcine models. The grafts, measuring 20 × 20 × 1.5 mm, were implanted following a 2 cm circumferential resection of the porcine trachea. The experiment design was traditionally implanted in eight porcines to replace four-ring tracheal segments, only two of which survived more than three months. Data were collected on the graft construction and clinical outcomes. The 3D-printed biosynthetic grafts replicated the native organ with high fidelity. The implantations were successful, without immediate complications. At two weeks, bronchoscopy revealed significant granulation tissue around the anastomosis, which was managed with laser ablation. The presence of neocartilage, neoglands, and partial epithelialization near the anastomosis was verified in the final pathology findings. Our study demonstrates in situ regenerative tissue growth with intact cartilage following transplantation, marked by neotissue formation on the graft's exterior. The 90-day survival milestone was achieved due to innovative surgical strategies, reinforced with strap muscle attached to the distal trachea. Further improvements in graft design and granulation tissue management are essential to optimize outcomes. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study was to study the relationship between the presence of a deep lateral femoral notch sign (DLFNS) in anterior cruciate ligament (ACL)‐injured patients and a higher posterior lateral tibial slope (LPTS), a reduced meniscal bone angle (MBA), a higher LPTS/MBA ratio and a higher incidence of concomitant injuries in primary ACL tears. Methods: A retrospective case‐control study was performed in patients submitted to primary ACL reconstruction with an available preoperative magnetic resonance imaging (MRI) scan. Patients with ACL tears and a femoral impactation with a depth ≥2 mm were assorted to the DLFNS group and patients with ACL tear and without a DLFNS to the control group. LPTS and MBA were measured in MRI. The presence of concomitant injuries (meniscal, posterior cruciate ligament, medial collateral ligament, lateral collateral ligament and bone injuries) was assessed in MRI. Quantitative data are presented in the median ± interquartile range (IQR). Results: There were 206 patients included in the study, with 46 patients assorted to the DLFNS group and 160 patients to the control group. In the DLFNS group, the median LPTS was 6.7° (IQR: 4.0–8.2) versus 4.0° in the control group (IQR: 2.2–6.5) (p = 0.003). The LPTS/MBA ratio was significantly higher in the DLFNS group, with a median of 0.32 (IQR: 0.19–0.44), in comparison to the control group, with a median of 0.19 (IQR: 0.11–0.31) (p < 0.001). The multivariable logistic regression analysis showed that the LPTS is an independent risk factor to having a DLFNS (odds ratio [OR] = 1.161; 95% confidence interval [CI]: 1.042–1.293, p = 0.007). There was a higher incidence of concomitant lateral meniscal injuries in the DLFNS group (67% vs. 48%, p = 0.017). Conclusions: In patients with ACL tears, the presence of a DLFNS is associated with a steeper lateral posterior tibial slope, as well as a higher incidence of concomitant lateral meniscal injuries. Level of Evidence: Level III. [ABSTRACT FROM AUTHOR]

Tissue engineering integrating cell-based approaches is promising for urinary tract injury treatments. Exploring the Impact of Nanostructured Heparin Conjugated-Polycaprolactone (HPCL) on the differentiation of Adipose Mesenchymal Stem Cells (ADMSCs) into Smooth Muscle Cells (SMCs). PCL nanofibers were produced by electrospinning and conjugated with heparin. The surface properties of the scaffolds were analyzed using FE-SEM for imaging, FTIR for investigation of chemical structure, assessments of surface roughness, thermomechanical characteristics, and the contact angle to evaluate wettability. The study included six groups; Group I: ADMSCs cells, Group II: ADMSCs seeded on PCL, Group III: ADMSCs seeded on HPCL, Group IV: SMCs cells, Group V: SMCs seeded on PCL, and Group VI: MSCs seeded on HPCL. SMCs differentiation was evaluated using specific genes and proteins. Immobilization of heparin was confirmed by amide I (3427 cm−1) and it was significantly raised on HPCL scaffolds. SMCs + HPCL group revealed the highest cell viability and the most significant increase in differentiation-related genes and proteins at 7 days (p < 0.05). HPCL nanofibers have an effect on SMCs differentiation, which are the functional units of the ureter. Therefore, they could represent a valuable tool for tissue engineering applications in ureter repair. [Display omitted] • Electrospinning technology provides a wide range of interesting and different alternatives for ureteral engineering. • The SMCs seeded onto HPCL scaffolds in particular could be employed as seed cells to generate a tissue-engineered ureter. • HPCL coatings could interact with the body to remodel artificial blood vessels similar to native veins. • The artificial medical devices could induce tissue regeneration on device surfaces while controlling the immune response. [ABSTRACT FROM AUTHOR]

Background: There is limited understanding of differences in the composition and structure of ligaments between healthy males and females, and individuals of different ages. Females present higher risk for ligament injuries than males and there are conflicting reports on its cause. This study looks into T1ρ parameters for an explanation as it relates to proteoglycan, collagen, and water content in these tissues. Purpose: To investigate gender‐related and age‐related differences in T1ρ parameters in knee joint ligaments in healthy volunteers using a T1ρ‐prepared zero echo‐time (ZTE)‐based pointwise‐encoding time‐reduction with radial acquisition (T1ρ‐PETRA) sequence. Study Type: Prospective. Population: The study group consisted of 22 healthy subjects (11 females, ages: 41 ± 18 years, and 11 males, ages: 41 ± 14 years) with no known inflammation, trauma, or pain in the knee joint. Field Strength/Sequence: A T1ρ‐prepared 3D‐PETRA sequence was used to acquire fat‐suppressed images with varying spin‐lock lengths (TSLs) of the knee joint at 3T. Assessment: Monoexponential, biexponential, and stretched‐exponential 3D‐PETRA‐T1ρ parameters were measured in the anterior cruciate ligament (ACL), posterior cruciate ligament (PCL), and patellar tendon (PT) by manually drawing ROIs over the entirety of the tissues. Statistical Tests: Mann–Whitney U‐tests were used to compare 3D‐PETRA‐T1ρ parameters in the ACL, PCL, and PT between males and females. Spearman correlation coefficients were used to determine the association between age and T1ρ parameters. Statistical significance was defined as P < 0.05. Results: Significant correlations with age were found the three ligaments with most of the measured T1ρ parameters (rs = 0.28–0.74) with the exception of the short fraction in the PCL (P = 0.18), and the short relaxation time in the ACL (P = 0.58) and in the PCL (P = 0.14). Data Conclusion: 3D‐PETRA‐T1ρ can detect age‐related differences in monoexponential, biexponential, and stretched‐exponential T1ρ parameters in three ligaments of healthy volunteers, which are thought to be related to changes in tissue composition and structure during the aging process. Level of Evidence: 2 Technical Efficacy: Stage 1 [ABSTRACT FROM AUTHOR]

Purpose: To assess the clinical efficacy of arthroscopic treatment for posterior cruciate ligament (PCL) tibial avulsion fractures using high-intensity suture binding combined with button plate suspension fixation. Methods: We retrospectively analyzed clinical data from 32 patients with PCL tibial avulsion fractures treated at our hospital from July 2020 to August 2023. We recorded operation time, intraoperative and postoperative complications, and used imaging to assess fracture reduction and healing. Pain and knee function were evaluated using the Visual Analogue Scale (VAS), range of knee motion, Lysholm score, and International Knee Documentation Committee (IKDC) score. Study Design: Case series; Level of evidence, 4. Results: All patients were followed for 6 to 18 months, averaging 13.6 months. All incisions healed successfully without postoperative complications. X-rays taken on the first postoperative day showed satisfactory fracture reduction. Three-month post-surgery imaging confirmed healed fractures and no internal fixation failures. At the final follow-up, knee function was well recovered, with only one patient exhibiting a positive posterior drawer test of degree I. Furthermore, the mean VAS score was 0. 5 (range 0.0 to 1.0), active knee extension was 2. 2° (range 0.0 to 5.0), and active knee flexion was 137.7° (range 130.0 to 145.0). The mean Lysholm score was 91.5(range 89.3 to 94.0), and the IKDC score averaged 83.8 ± 3.7, and these outcomes showed statistically significant improvement from preoperative levels (P < 0.001). Conclusions: Arthroscopic high-intensity suture binding combined with button plate suspension fixation for PCL tibial avulsion fractures offers several benefits: it is minimally invasive, results in less postoperative pain, enables earlier functional exercise, and provides satisfactory clinical outcomes with fewer complications. [ABSTRACT FROM AUTHOR]

Introduction: The posterior cruciate ligament (PCL) is the largest and strongest intra‐articular ligament of the knee joint and the primary posterior stabilizer. PCL injuries are less frequent than other knee ligament injuries and are typically combined with meniscal and chondral injuries or in the context of multiligamentous injuries. It is critical to properly diagnose and treat these lesions in order to avoid the risk of PCL insufficiency, subsequent knee instability, and early osteoarthritis. Surgical management can vary, and the ideal fixation device is still debated. Suture anchors are an unusual mean of fixation of PCL tibial bony avulsion. We report on two patients treated with open anchor fixation for PCL tibial bony avulsion with a follow‐up of 3 years. Case Presentation: A 15‐year‐old male and a 65‐year‐old male were treated with open anchor fixation for bony tibial avulsion of the PCL. Surgical treatment was performed at 5 weeks and 3 weeks after the trauma, respectively. Diagnosis was made with an X‐ray followed by CT and MR scans. Repair was achieved by reinserting the PCL bony fragment to its posterior tibial eminence with suture anchors through an open posterior approach. Both patients recovered full knee stability and a pain‐free full range of motion (ROM) within 4 months and returned to their previous activities with a high satisfaction. The patient has been followed up for 3 years, and no complications were observed. Conclusion: PCL bony avulsions are rare, and their optimal treatment remains a significant subject of debate, particularly in the skeletally immature patient. We believe that open repair with metal anchors could be a good choice to repair PCL bony tibial avulsion in patients without concomitant intra‐articular lesions and immature growth plates or severe fragmentation. [ABSTRACT FROM AUTHOR]

Introduction: Total knee arthroplasty (TKA) is the most effective treatment of late osteoarthritis (OA) and is considered among the most successful surgical procedures in general. However, about 20% of patients remain dissatisfied. An important aspect of TKA is the proper choice of implant type - posterior stabilized (PS) or cruciate retaining (CR). Both have their indications for use based on intraoperative functional examination, but no objective radiological criteria have yet been developed. The aim of this study was to investigate the relationship between the posterior subluxation of the tibia on preoperative radiograms and implant type used. Material and methods: A series of 52 patients undergoing TKA were included in the study. All patients were over 50 years old, had clinically and radiologically confirmed primary OA of grade IV on the Kellgren-Lawrence scale and were undergoing a primary total knee replacement (TKR) with a PS or CR design. Preoperative lateral radiographs were analysed retrospectively. The tibial translation ratio was calculated as a percentage of subluxation in the length of the tibial plateau. Results: There were no significant differences between implant types in regard to investigated parameters. However, there was a significant difference between the groups CR and PS in regard to age (68.5 [60.0-72.0] vs. 72.5 [68.0-75.0], p = 0.006). Conclusions: This study revealed that preoperative tibial translation does not significantly correlate with the choice of implant type and so probably not with posterior cruciate ligament (PCL) function and efficiency either. Additionally, this study showed that PCL insufficiency is related to the age of the patients, because of the more frequent choice of the PS implant type for the surgery in older patients than in the case of the CR implant type. [ABSTRACT FROM AUTHOR]

Background: Animal models that use open surgical transection of the anterior cruciate ligament (ACL) do not accurately simulate the clinical condition regarding the pivot-shift mechanism and the associated inflammatory response that occurs before reconstruction. Purpose/Hypothesis: The purpose was to characterize a reproducible manual, nonsurgical method to mimic an isolated ACL tear in a clinically relevant model and to evaluate the development of progressive posttraumatic osteoarthritis due to ACL injury. It was hypothesized that the ACL could be reproducibly torn with minimal damage to other ligaments and that there would be progressive development of degenerative joint disease after ACL injury. Study Design: Controlled laboratory study. Methods: A total of 37 mice (strain C57BL/6) were used to compare the manual procedure with sham surgery (sham group; n = 10) and with the established surgical ACL transection (ACLT) procedure (surgical group; n = 27). In the sham group, a closed manual procedure was performed on the right knee and sham surgery on the left knee. In the surgical group, the closed manual procedure was performed on the right knee and surgical ACLT on the left knee. Dissection using India ink, histological assessment with safranin O and hematoxylin-eosin staining, radiological evaluation through radiographs and microfocus computed tomography scans, and gait analyses were performed to assess cartilage/ligament status. Osteoarthritis Research Society International (OARSI) and synovitis scores, anterior tibial translation, range of motion, bone microstructure, osteophyte volume, and pain were assessed at 2, 4, and 8 weeks postoperatively. Results: The manual procedure successfully resulted in an ACL rupture and associated meniscal injury. The posterior cruciate, lateral collateral, and medial collateral ligaments were intact in all dissected knees. Two weeks after ACL tear, the surgical group showed a significantly higher synovitis score, whereas 8 weeks after ACL tear, the manual group showed a significantly higher volume of osteophytes. No significant differences were found between the groups in terms of OARSI score, anterior tibial translation, range of motion, bone microstructure computed tomography values, and stride distance/irregularity. Conclusion: This procedure can be used to create an ACL tear model without causing grossly evident injuries to other ligaments and avoiding the risk of cartilage damage from surgical instruments. Clinical Relevance: This procedure offers a more clinically relevant ACL tear model and facilitates simple, inexpensive, and reproducible development of posttraumatic osteoarthritis. [ABSTRACT FROM AUTHOR]

Anterior cruciate ligament and meniscus tears are common among sports injuries. There are different techniques for addressing anterior cruciate ligament and meniscus tears, with distinct indications, advantages, and disadvantages. We present the case of a 23-year-old male who underwent right anterior cruciate ligament reconstruction and posterior horn medial meniscus repair using an all-inside technique via superficial medial collateral ligament (sMCL) pie-crusting. Clinical examination and radiological investigations a few months later identified calcifications on the medial side of the right knee. We diagnosed the patient with heterotopic ossification post-sMCL pie-crusting; no apparent causal factors were present. To our knowledge, there have been no documented instances of heterotopic ossification following sMCL pie-crusting. In conclusion, heterotopic ossification may occur after sMCL pie-crusting; further studies are needed on this subject. [ABSTRACT FROM AUTHOR]

Purpose: To investigate the validity of using tibial capsular reflection and septum in the posterior compartment as landmark during posterior cruciate ligament (PCL) reconstruction (PCLR). Methods: Anatomic measurements were obtained for 12 fresh human cadaveric knee specimens to observe the spatial position of the tibial insertion of the PCL in relation to the posterior septum and the capsular reflection in the posterior compartment. Sixty patients who underwent reconstruction of the PCL between 2020 and 2023 were also retrospectively investigated. The tibial tunnel was replaced in all patients using the same method (with reference to the tibial capsular reflection and the posterior septum). The placement of the tibial tunnel was assessed using X‐ray fluoroscopy intraoperatively and computed tomography and three‐dimensional reconstruction postoperatively. Results: All fibres in the tibial insertion of the PCL in the 12 cadaveric specimens were located in the posteromedial compartment, adjacent to the posterior septum. The inferior border of the PCL insertion is adjacent to the tibial capsular reflection, which is attached at the champagne glass drop‐off of the posterior tibia. In our previous cases, none of the patients experienced postoperative or intraoperative complications such as neurovascular injury, and the angle between the pin and the PCL facet was 93.1 ± 3.9° as measured on intraoperative radiographs. The mean distance from the centre of the tibial tunnel outlet to the inferior border of the PCL insertion was 5.6 ± 1.1 mm, and the distance from the centre of the tibial tunnel outlet to the outer border of the PCL insertion as a percentage of the length of the inferior border of PCL insertion was 42.2 ± 6.3%. Conclusion: The tibial capsular reflection and septum in the posterior compartment are safe and reliable soft‐tissue landmark for tibial tunnel drilling in PCLR. Level of Evidence: Level Ⅳ. [ABSTRACT FROM AUTHOR]

Purpose: Mid-flexion instability has been identified as a cause for dissatisfaction following total knee arthroplasty (TKA). Robotic-assisted surgery using the Mako robot only allows for assessment of stability at 10° and 90°. This study aimed to investigate any evidence of mid-flexion instability in Mako-assisted TKA. Methods: Data from 72 TKA in 59 patients from 2018 to 2022 were collected. All patients underwent an RA (Mako, Stryker, Fort Lauderdale, FL, USA), single-radius design, cruciate-retaining TKA. Intraoperatively, medial, and lateral pressures were measured at 10°, 45° and 90° of flexion using a pressure sensor (Verasense, OrthoSensor, 59 Inc., Dania Beach, FL, USA). The knee was considered balanced if the difference in pressures between compartments was less than 15 pounds-force (lbf). Results: There was no significant difference between the pressures measured in the medial compartment at 10°, 45° and 90° of flexion (P = 0.696). A statistically significant difference was found between the pressures measured in the lateral compartment at 10°, 45° and 90° of flexion, with the 10° value being significantly higher (P < 0.001), but this did not exceed the threshold of 15 lbf. None of the patients had a pressure difference of more than 15 lbf when pressures at 45° were compared to that at 10° and 90°, medially or laterally. Conclusion: This study showed no evidence of mid-flexion instability in Mako-assisted TKA, using a single radius, cruciate-retaining prosthesis whilst maintaining the joint height. Level of evidence: Level III retrospective cohort study. [ABSTRACT FROM AUTHOR]

Purpose: This original case series aims to describe an uncommon triad of clinical signs in patients presenting with persistent pain and inability to resume physical activities after knee hyperextension trauma. Methods: Patient history, clinical examination, arthroscopic findings and investigations of 12 patients who consulted with the senior author are presented. Results: Twelve patients (seven males/five females) presented with persistent pain after knee hyperextension trauma either in sport or a traffic accident. They had a median age of 18.5 and a median body mass index of 23 kg/m2. All had medical visits and at least one magnetic resonance imaging (MRI) before visiting the senior author's institution but the cause of their problems could not be explained. The clinical examination of the injured knee appeared normal except for an uncommon triad of clinical signs with the knee close to extension: (1) a grade 1+ anterior–posterior laxity around 10–20° of knee flexion with a firm end‐point (pseudo‐Lachman sign), (2) a grade 1+ tibiofemoral step‐off sign with a posterior drawer at 10–20° of knee flexion and (3) an increased knee hyperextension compared to the contralateral side. Arthroscopy of eight patients confirmed the pseudo‐Lachman sign with a grade I posterior drawer close to knee extension, normal posterior laxity at 90° of knee flexion and an intact anterior cruciate ligament. Conclusion: Patients displayed an increased hyperextension and posterior laxity close to knee extension which normalised at 90° of knee flexion. In patients with a history of knee hyperextension trauma associated with persistent pain, inability to resume physical activities, inconclusive MRIs and a standard clinical examination, clinicians should consider extending their investigations with the knee close to extension to identify this clinical triad consistent with a lesion to the posteromedial bundle of the posterior cruciate ligament. Level of evidence: Level IV. [ABSTRACT FROM AUTHOR]

Background: During the transtibial posterior cruciate ligament (PCL) reconstruction, drilling depth excessively longer than the tibial tunnel length (TTL) is an important reason to cause popliteal neurovascular bundle injury when preparing the tibial tunnel. This study aims to develop an in-vitro three-dimensional surgical simulation technique to determine the TTL in anteromedial (AM) and anterolateral (AL) approaches. Methods: A total of 63 knees' 3-dimensional (3D) computed tomography models were included in this study. The SuperImage system was used to reconstruct the 3D knee model and locate the tibial PCL site. The established 3D knee model and the coordinates of the tibial PCL site were imported into Rhinoceros 3D modeling software to simulate AM and AL tibial tunnel approaches with different tibial tunnel angles (TTA). The TTL and the tibial tunnel height (TTH) were measured in this study. Results: In AM and AL tibial tunnel approaches, the TTL showed a strong correlation with the TTA (for AM: r = 0.758, p < 0.001; for AL: r = 0.727, p < 0.001). The best fit equation to calculate the TTL based on the TTA was Y = 1.04X + 14.96 for males in AM approach, Y = 0.93X + 17.76 for males in AL approach, Y = 0.92X + 14.4 for females in AM approach, and Y = 0.94X + 10.5 for females in AL approach. Conclusion: Marking the TTL on the guide pin or reamer could help to avoid the drill bit over-penetrated into the popliteal space to damage the neurovascular structure. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study was to analyse the difference between arthroscopic fixation and open reduction internal fixation (ORIF) of posterior cruciate ligament (PCL) tibial avulsion fractures. Methods: This retrospective study analysed patients with an acute PCL tibial avulsion fracture who underwent surgical treatment at our hospital and follow-up for at least 24 months. Variables based on sex, age, Meyers–McKeever type, surgical method, meniscus tear, external fixation, labour or sports, Lysholm knee score, IKDC score, and KT-1000 value were also recorded. Multifactor unconditional logistic regression and Student's t test with 1:1 propensity score matching (PSM) to remove confounding factors were used for analysis. Results: Sixty-five cases achieved knee function graded as "good" or better, and 9 cases not. Single-factor analysis indicated that Meyers–McKeever type (χ2 = 4.669, P = 0.031) and surgical approach (χ2 = 9.428, P = 0.002) are related to functional outcomes. Multifactorial logistic regression analysis further confirmed that Meyers–McKeever typing (OR = 10.763, P = 0.036, [95% CI 1.174–98.693]) and surgical approach (OR = 9.274, P = 0.008, [95% CI 1.794–47.934]) are independent risk factors affecting prognosis. In addition, PSM verified significant differences in the Lysholm score (t = 3.195, P = 0.006), IKDC score (t = 4.703, P = 0.000) and A-KT/H-KT (t = 2.859, P = 0.012). However, the affected-side KT-1000 value (A-KT, mm, t = 1.225, P = 0.239) and healthy-side KT-1000 value (H-KT, mm, t = 1.436, P = 0.172) did not significantly differ between the two groups. The proportions of cases in which the Lysholm score, IKDC and A-KT/H-KT exceeded the minimal clinically important difference (MCID) were 62.5% (20/32), 62.5% (20/32) and 93.75% (30/32), respectively. Conclusion: Compared with ORIF, an arthroscopic approach for PCL tibial avulsion fractures achieves better results. Level of evidence: Retrospective cohort study; Level II. [ABSTRACT FROM AUTHOR]

This document is an editorial from the journal International Orthopaedics, discussing a special issue dedicated to current concepts and recent progress in pediatric orthopaedics and trauma surgery. The field of pediatric orthopaedics has seen significant changes in recent years, with increasing specialization in various areas. The special issue includes high-quality scientific papers from authors in 35 different countries, covering a wide range of topics and clinical innovations. The editorial highlights key papers in the issue, expressing gratitude to the authors and the journal for their contributions. This report, authored by Federico Canavese, Patricia Maria de Moraes Barros Fucs, and Ashok N. Johari, provides an in-depth analysis of a specific topic, written in a culturally sensitive manner. Library patrons conducting research on this topic will find this report to be a valuable resource. [Extracted from the article]

Purpose: The posterior cruciate ligament (PCL) rupture rarely occurs, especially in skeletally immature adolescents, and poses a dilemma in appropriately managing the open physis with its vast growth potential. However, although many epiphyseal-protecting techniques for anterior cruciate ligament (ACL) reconstruction have been reported, a similar problem in PCL reconstruction has received scant attention and needs more relevant research. So, this study aims to evaluate the short-term clinical and imaging results of the arthroscopic physeal-sparing reconstruction program. Method: All the 13 patients we reviewed in this study have accepted the arthroscopic physeal-sparing PCL reconstruction from January 2019 to December 2022 in our Department of Orthopedics. Primary demographic data collected include gender (8 males and 5 females), age (11–15 years, average 13.3 years), follow-up period (15–35 months, average 25.2 months), injury mechanism (nine non-contact injuries and four contact injuries), and days following injury (1–10 days, average 5.3 days). The assessment of clinical outcomes included pre- and postoperative physical examination, knee functional scores, and imaging data. Result: All patients in this study were followed up with an average 25.2-month (range 15–35 months) follow-up period. All the cases preoperatively had a positive posterior drawer test and turned negative at the final follow-up. The average ROM improved from 103.6° ± 11.4° to 132.6° ± 3.6° at the last follow-up (p < 0.05). The VAS score decreased from 5.8 ± 1.6 to 0.9 ± 0.5 (p < 0.05); the average KT-1000 healthy-side to affected-side difference decreased from 11.3 ± 1.6 to1.8 ± 0.5 mm. The comparison of all the knee functional scores (IKDC, Tegner scores, and Lysholm) at preoperative and last follow-up showed a significant difference (p < 0.05). None of the cases had operation-related complications, and all recovered to sports well. Conclusion: The arthroscopic physeal-sparing posterior cruciate ligament reconstruction is a dependable and recommended treatment for posterior cruciate ligament rupture in adolescents with open physis, showing a striking improvement in knee function without growth arrest and angular deformity of the affected limb in the short-term follow-up. [ABSTRACT FROM AUTHOR]

Introduction: Anterior cruciate ligament (ACL) reconstruction remains associated with the risk of re-rupture and persisting rotational instability. Additional extraarticular anterolateral stabilization procedures stabilize the tibial internal rotation and lead to lower ACL failure rate and improved knee stability. However, data for additional stabilization of tibial external rotation is lacking and the importance of an anteromedial stabilization procedure is less well evaluated. Aim of this study is to investigate the influence of an extraarticular anteromedial stabilization procedure for the stabilization of the tibial external rotation and protection of the ACL from these rotational forces. Methods: Internal and external rotations of the tibia were applied to a finite element (FE) model with anatomical ACL, posterior cruciate ligament (PCL), lateral collateral ligament (LCL), medial collateral ligament (MCL) and intact medial and lateral meniscus. Five additional anatomic structures (Anteromedial stabilization/anteromedial ligament, AML, augmented superficial medial collateral ligament, sMCL, posterior oblique ligament, POL, anterolateral ligament, ALL, and popliteal tendon, PLT) were added to the FE model separately and then combined. The force histories within all structures were measured and determined for each case. Results: The anteromedial stabilization or imaginary AML was the main secondary stabilizer of tibial external rotation (90% of overall ACL force reduction). The AML reduced the load on the ACL by 9% in tibial external rotation which could not be achieved by an augmented sMCL (-1%). The AML had no influence in tibial internal rotation (-1%). In the combined measurements with all additional structures (AML, ALL, PLT, POL) the load on the ACL was reduced by 10% in tibial external rotation. Conclusion: This study showed that an additional anteromedial stabilization procedure secures the tibial external rotation and has the most protective effect on the ACL during these external rotational forces. [ABSTRACT FROM AUTHOR]

Purpose: Arthroscopic reconstruction techniques for higher-grade posterolateral corner (PLC) injuries (Fanelli Type B, PoLIS LI-B) have not yet been validated in clinical studies. The open reconstruction technique described by Arciero is well-established and showed good restoration of joint stability in previous studies. This study aimed to compare clinical outcomes of this established open surgery technique to a newly developed arthroscopic technique in a prospective randomized clinical trial. Methods: Between 2019 and 2021, this study focused on chronic high-grade PLC injuries (Fanelli Type B, PoLIS LI-B). Group A consisted of patients treated with conventional open surgery following Arciero's technique, while Group B included patients treated with Arciero's arthroscopic technique. All cases underwent additional PCL reconstruction. After a minimum 12-month follow-up, clinical scores and objective stability assessments were compared between the groups. Results: In total, 26 (group A 12, group B 14) eligible patients with a mean follow-up of 14.9 ± 7.2 months were evaluated in the present study. Knee stability and patient-reported outcome scores (PROMS) were significantly improved when comparing pre- and post-operative values (p < 0.0001). No clinically relevant differences in PROMS (Lysholm: A 83.9 ± 11.4 vs. B 85.3 ± 13.8; IKDC: A 76.91 ± 12.6 vs. B 76.8 ± 15.7) were shown in both groups. Additionally, no statistically significant differences were detected between groups with respect to external rotation, range of motion and instrumental stability testing. Arthroscopic reconstruction showed significantly shorter operation time (p = 0.0109). There were no clinical failures or neurovascular complications of the surgical procedures. Conclusion: Both surgical techniques for isolated chronic PLC Fanelli Type B injuries significantly improved the knee stability, were equivalent with respect to PROMs and led to good clinical results. However, arthroscopic PLC reconstruction was associated with a shorter surgery time compared to open PLC reconstruction. Therefore, arthroscopic PLC reconstruction may be a viable option in the hands of an experienced surgeon. Level of evidence: Prospective cohort study, II. [ABSTRACT FROM AUTHOR]

An objective of a total knee arthroplasty (TKA) is to restore native (i.e. healthy) function, and a crucial step is determining the correct insert thickness for each patient. If the insert is too thick, then stiffness results, and if too thin, then instability results. Two methods to determine the insert thickness are by manually assessing the joint laxity and by using a trial insert with goniometric markings that measures the internal-external rotation of the trial with respect to a mark on the femoral component. The former is qualitative and depends on the surgeon's experience and 'feel' and while the latter is quantitative, it can be used only with an insert with medial ball-in-socket conformity. An unexplored method is to measure the force required to push a trial insert into position. To determine whether this method has merit, the push force was measured in 30 patients undergoing unrestricted kinematically aligned TKA using an insert with ball-in-socket medial conformity, a flat lateral surface, and retention of the posterior cruciate ligament. During surgery, the surgeon determined three appropriate thicknesses to test from a selection ranging from 10 mm to 14 mm in 1 mm increments. The peak push forces going from an insert 1 mm thinner than the correct thickness as determined by an insert goniometer and from the correct thickness to 1 mm thicker were measured. Mean peak forces for the different insert thicknesses were 127 ± 104 N, 127 ± 95 N, and 144 ± 96 N for 1 mm thinner, correct, and 1 mm thicker, respectively, and did not differ (p = 0.3210). As a result, measurement of peak force during trial positioning of a tibial insert cannot be used to identify the correct thickness for all insert designs. [ABSTRACT FROM AUTHOR]

Objective: Predicting whether the posterior cruciate ligament (PCL) should be preserved during total knee arthroplasty (TKA) procedures is a complex task in the preoperative phase. The choice to either retain or excise the PCL has a substantial effect on the surgical outcomes and biomechanical integrity of the knee joint after the operation. To enhance surgeons' ability to predict the removal and retention of the PCL in patients before TKA, we developed machine learning models. We also identified significant feature factors that contribute to accurate predictions during this process. Methods: Patients' data on TKA continuously performed by a single surgeon who had intended initially to undergo implantation of cruciate‐retaining (CR) prostheses was collected. During the sacrifice of PCL, we utilized anterior‐stabilized (AS) tibial bearings. The dataset was split into CR and AS categories to form distinct groups. Relevant information regarding age, gender, body mass index (BMI), the affected side, and preoperative diagnosis was extracted by reviewing the medical records of the patients. To ensure the authenticity of the research, an initial step involved capturing X‐ray images before the surgery. These images were then analyzed to determine the height of the medial condyle (MMH) and lateral condyle (LMH), as well as the ratios between MLW and MMH and MLW and LMH. Additionally, the insall‐salvati index (ISI) was calculated, and the severity of any varus or valgus deformities was assessed. Eight machine‐learning methods were developed to predict the retention of PCL in TKA. Risk factor analysis was performed using the SHApley Additive exPlanations method. Results: A total of 307 knee joints from 266 patients were included, among which there were 254 females and 53 males. A stratified random sampling technique was used to split patients in a 70:30 ratio into a training dataset and a testing dataset. Eight machine‐learning models were trained using data feeding. Except for the AUC of the LGBM Classifier, which is 0.70, the AUCs of other machine learning models are all lower than 0.70. In importance‐based analysis, ISI, MMH, LMH, deformity, and age were confirmed as important predictive factors for PCL retention in operations. Conclusion: The LGBM Classifier model achieved the best performance in predicting PCL retention in TKA. Among the potential risk factors, ISI, MMH, LMH, and deformity played essential roles in the prediction of PCL retention. [ABSTRACT FROM AUTHOR]

Background: After posterior cruciate ligament reconstruction (PCLR), functional deficits at the knee can persist. It remains unclear if neighboring joints compensate for the knee during demanding activities of daily living. Purpose: To assess long-term alterations in lower limb mechanics in patients after PCLR. Study Design: Descriptive laboratory study. Methods: A total of 28 patients who had undergone single-bundle unilateral isolated or combined PCLR performed stair navigation, squat, sit-to-stand, and stand-to-sit tasks at 8.2 ± 2.2 years after surgery. Motion capture and force plates were used to collect kinematic and kinetic data. Then, 3-dimensional hip, knee, and ankle kinematic data of the reconstructed limb were compared with those of the contralateral limb using statistical parametric mapping. Results: Side-to-side differences at the knee were primarily found during upward-driven movements at 8 years after surgery. The reconstructed knee exhibited lower internal rotation during the initial loading phase of stair ascent versus the contralateral knee (P =.005). During the sit-to-stand task, higher flexion angles during the midcycle (P =.017) and lower external rotation angles (P =.049) were found in the reconstructed knee; sagittal knee (P =.001) and hip (P =.016) moments were lower in the reconstructed limb than the contralateral limb. In downward-driven movements, side-to-side differences were minimal at the knee but prominent at the ankle and hip: during stair descent, the reconstructed ankle exhibited lower dorsiflexion and lower external rotation during the midcycle versus the contralateral ankle (P =.006 and P =.040, respectively). Frontal hip moments in the reconstructed limb were higher than those in the contralateral limb during the stand-to-sit task (P =.010); during squats, sagittal hip angles in the reconstructed limb were higher than those in the contralateral limb (P <.001). Conclusion: Patients after PCLR exhibited compensations at the hip and ankle during downward-driven movements, such as stair descent, squats, and stand-to-sit. Conversely, residual long-term side-to-side differences at the knee were detected during upward-driven movements such as stair ascent and sit-to-stand. Clinical Relevance: After PCLR, side-to-side differences in biomechanical function were activity-dependent and occurred either at the knee or neighboring joints. When referring to the contralateral limb to assess knee function in the reconstructed limb, concentric, upward-driven movements should be prioritized. Compensations at the hip and ankle during downward-driven movements lead to biases in long-term functional assessments. [ABSTRACT FROM AUTHOR]

Purpose: The aim of this study was to investigate whether malrotation of lateral knee radiographs influences posterior tibial slope (PTS) measurements. Methods: Lateral knee radiographs of all patients who underwent knee surgery at a single institution between June 2022 and January 2023 and received multiple lateral knee radiographs were included. Radiographs were categorised as malrotated lateral knee radiographs or lateral knee radiographs based on the radiographic distance between the medial and lateral posterior femoral condyles. Medial PTS (MPTS) and lateral PTS (LPTS) were evaluated on malrotated lateral knee radiographs and lateral knee radiographs and compared using the paired t test. Intra‐ and interrater reliability between four raters were assessed for MPTS and LPTS measurements. Results: A total of 92 lateral knee radiographs (46 pairs of malrotated lateral knee radiographs and lateral knee radiographs; 50.0% right side) from 46 patients (33.2 ± 12.4 years, 69.6% male) were included. Mean posterior femoral condyle distance in malrotated lateral knee radiographs was 8.1 ± 4.4 mm. Overall, MPTS and LPTS were significantly higher on malrotated lateral knee radiographs versus lateral knee radiographs (medial: 10.5 ± 3.2° vs. 9.7 ± 3.5°, p < 0.05; lateral: 10.6 ± 3.4° vs. 9.7 ± 3.3°, p < 0.05). Mean absolute difference between MPTS and LPTS on malrotated lateral knee radiographs versus lateral knee radiographs were |1.9| ± |1.5|° and |2.0| ± |1.8|°, respectively. Intrarater reliability was 'moderate' and interrater reliability was 'good' for both MPTS and LPTS. Conclusion: Malrotation of lateral knee radiographs led to a significant distortion of both the MPTS and LPTS. In clinical practice, attention should be placed on the (mal)rotation of lateral knee radiographs, especially in patients for whom a slope‐correcting osteotomy is being discussed. Level of Evidence: Level IV. [ABSTRACT FROM AUTHOR]