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Purpose: There have been numerous studies of the anterior cruciate ligament (ACL) anatomy, but few have focused on the long axis angle of the femoral ACL footprint. This study investigated the angle between the long axis of the femoral ACL footprint and the bony morphology of the knee. Methods: This study is a cadaveric descriptive study. Thirty non-paired formalin-fixed knees of Japanese cadavers were used. Anteromedial (AM) and posterolateral (PL) bundles were identified according to the tension pattern differences during the complete range of motion of the knee. In the ACL femoral footprint, there is a fold between the mid-substance insertion site and fan-like extension fibers. After identifying AM and PL bundles of mid-substance fibers, the mid-substance and fan-like extension fibers were divided into those bundles and stained. We defined the line passing through the center of the AM and PL bundles as the long axis of the ACL. The center points of each of the four areas and the angle between the long axis of the ACL and the bony morphology of the knee were calculated using Image J software. Results: The mean angle between the axis of the femoral shaft and the long axis of the ACL mid-substance insertion was 28.8 ± 12.2 degrees. The mean angle between the Blumensaat line and the long axis of the mid-substance was 54.2 ± 13.5 degrees. Conclusion: The mean angle between the axis of the femoral shaft and the long axis of the femoral ACL footprint was approximately 29 degrees. There is a wide variation in the long axis of the femoral ACL footprint. To achieve better clinical results through a more anatomically accurate reconstruction, it can be beneficial to replicate the ACL femoral footprint along its native long axis. [ABSTRACT FROM AUTHOR]

Context: Excessive knee valgus on landing can cause anterior cruciate ligament injury. Therefore, knee valgus alignment may show characteristic energy absorption patterns during landings with lateral movement that impose greater impact forces on the knee joint compared with landings in other alignments. Objective: To investigate the energy absorption strategy in lower-extremities during side steps in females with knee valgus alignment. Design: Controlled laboratory study. Setting: University research laboratory. Participants: A total of 34 female college students participated in this experiment. Interventions: Participants performed single-leg drop vertical jump and side steps. All participants were divided into valgus (n = 13), neutral (n = 9), and varus (n = 12) groups according to knee position during landing in single-leg drop vertical jumps. Main Outcome Measures: Lower-extremity joint angles, moments, and negative works were calculated during landing in side steps, and 1-way analysis of variance and post hoc tests were used to determine between-group differences. Results: Negative works of hip extensors, knee abductors, and ankle plantar flexors during landing in side steps were significantly smaller in the valgus than in the varus group; however, negative work of the knee extensors was significantly greater in the valgus group than in varus group. Conclusions: The findings of this study indicated that landing with knee valgus induced the characteristic energy absorption strategy in the lower-extremity. Knee extensors contributed more to energy absorption when landing in knee valgus than in knee varus alignment. Learning to land in knee varus alignment might reduce the impact on the knee joint by increasing the energy absorption capacities of hip extensors, knee abductors, and ankle plantar flexors. [ABSTRACT FROM AUTHOR]

Background: Poor postoperative quadriceps muscle strength recovery after anterior cruciate ligament reconstruction (ACLR) leads to delayed return to sports and lower patient satisfaction. Purpose/Hypothesis: The purpose of this study was to examine factors that affect quadriceps muscle strength 1 year after ACLR. It was hypothesized that older age, poor preoperative quadriceps muscle strength, and residual pain would be risk factors for poor quadriceps muscle strength recovery. Study Design: Case-control study; Level of evidence, 3. Methods: Included were patients from multiple institutions who underwent primary ACLR using autologous hamstring tendon grafts between August 1, 2013, and March 31, 2018, and who had at least 1 year of follow-up data. Patients with past ligamentous injuries in the affected knee, previous injuries or operations in the contralateral knee, accompanying ligament injuries of grade 2 or 3, or inflammatory or other types of osteoarthritis were excluded. Patients were categorized as having muscle strength ≥80% (good strength recovery) or <80% (poor strength recovery) compared with the contralateral leg at 1 year postoperatively. Multivariate logistic regression analysis was performed to investigate the factors influencing postoperative quadriceps muscle strength. In addition, a categorical analysis was conducted based on factors extracted by the multivariate logistic regression analysis. Results: A total of 402 patients were included. Multivariate logistic regression analysis revealed that age at surgery (P =.020), preoperative quadriceps muscle strength (P =.006), and postoperative Knee injury and Osteoarthritis Outcome Score (KOOS)-Pain score (P =.002) were significantly associated with quadriceps muscle strength at 1 year postoperatively. The odds of poor muscle strength recovery according to categorical analysis were 5.0-fold higher for patients aged >40 versus ≤20 years, 4.2-fold higher for those with preoperative quadriceps muscle index <60% versus ≥80%, and 7.7-fold higher for those with a postoperative KOOS-Pain score of <85 versus 100. Conclusion: Older age, poor preoperative quadriceps muscle strength, and low postoperative KOOS-Pain score were risk factors for poor quadriceps muscle strength 1 year after primary ACLR. Surgical indications, including age, preoperative active rehabilitation, and pain control, should be considered for optimization of postoperative quadriceps muscle strength recovery. [ABSTRACT FROM AUTHOR]

Background: The advantages of remnant tissue preservation in anterior cruciate ligament (ACL) reconstruction (ACLR) remain controversial. Hypothesis: It was hypothesized that a large amount of remnant tissue, especially if anatomically positioned, would improve patient-reported outcomes and second-look graft appearance after preserved double-bundle ACLR (DB-ACLR). Study Design: Cohort study; Level of evidence, 3. Methods: This retrospective study included 89 consecutive patients who underwent unilateral remnant-preserving DB-ACLR using 2 hamstring tendon autografts. The authors categorized the arthroscopic findings into 3 groups according to the location and volume of the ACL remnant tissue in the femoral notch: (1) anatomical attachment (group AA; n = 34); (2) nonanatomical attachment (group NA; n = 33); and (3) no remnant (group NR; n = 22). Based on second-look arthroscopy, the reconstructed graft was graded as excellent, fair, or poor. Patient-reported outcomes were evaluated at 2 years after surgery using the Knee injury and Osteoarthritis Outcome Score (KOOS) and the Japanese Anterior Cruciate Ligament Questionnaire–25 (JACL-25). Results: The AA and NA groups had a significantly shorter time from injury to surgery compared with the NR group (P =.0165). Considering the second-look arthroscopic findings, the authors found a significant difference in synovial coverage of the grafts between the 3 groups (P =.0018). There were no significant differences in the overall KOOS and JACL-25 score among the 3 groups; however, the KOOS–Sport and Recreation and KOOS–Quality of Life subscale scores were significantly higher in the AA group compared with the NA and NR groups (P =.0014 and.0039, respectively). The JACL-25 score for middle- to high-speed flexion and extension was significantly better in the AA group versus the NR group (P =.0261). Conclusion: This study showed that preserving anatomically positioned and adequate remnant tissue during DB-ACLR improved second-look graft appearance and KOOS–Sport and Recreation and KOOS–Quality of Life scores. [ABSTRACT FROM AUTHOR]

Background: Investigations on the biomechanical characteristics of the anterior horn of the lateral meniscus (AHLM) related to anterior cruciate ligament (ACL) tibial tunnel reaming have revealed increased contact pressure between the femur and tibia, decreased attachment area, and decreased ultimate failure strength. Purpose/Hypothesis: The purpose of this study was to investigate the influence of a complete radial tear of the AHLM on force distribution in response to applied anterior and posterior drawer forces and internal and external rotation torques. We hypothesized that the AHLM plays an important role in knee stability, primarily at lower knee flexion angles. Study Design: Controlled laboratory study. Methods: A total of 9 fresh-frozen cadaveric knee specimens and a robotic testing system were used. Anterior and posterior drawer forces up to 89 N and internal and external rotation torques up to 4 N·m were applied at 0°, 30°, 60°, and 90° of knee flexion. A complete AHLM tear was then made 10 mm from the lateral border of the tibial attachment of the ACL, and the same tests performed in the intact state were repeated. Next, the recorded intact knee motion was reproduced in the AHLM-torn knee, and the change in the resultant force after an AHLM tear was determined by calculating the difference between the 2 states. Results: In the torn AHLM, the reduction in the resultant force at 0° for external rotation torque (34.8 N) was larger than that at 60° (5.2 N; P <.01) and 90° (6.7 N; P <.01). Conclusion: The AHLM played a role in facilitating knee stability against an applied posterior drawer force of 89 N and external rotation torque of 4 N·m, especially at lower knee flexion angles. Clinical Relevance: This study provides information about the effects of AHLM injuries that may occur during single-bundle ACL reconstruction using a round tunnel. [ABSTRACT FROM AUTHOR]

Background: Deep venous thrombosis (DVT) and pulmonary embolism are serious potential complications after anterior cruciate ligament reconstruction (ACLR). Little is known about the influence of tourniquet use on the incidence of DVT after ACLR. Purpose: To compare the incidence of DVT after ACLR with and without the use of a tourniquet. Study Design: Cohort study; Level of evidence, 3. Methods: Between November 2018 and May 2020, a total of 60 consecutive ACLRs in 60 patients, including 7 revision surgeries, were performed without tourniquet use at our hospital and were enrolled in this study (T– group). In addition, 55 consecutive ACLRs in 55 patients, including 10 revision surgeries, were performed with tourniquet use between April 2017 and September 2018 and were enrolled as the control group (T+ group). DVT was diagnosed using ultrasonography of both legs performed preoperatively and at postoperative week 1. The incidence of postoperative DVT was compared between the T– and T+ groups. Logistic regression analysis was performed to evaluate the effect of older age (≥40 vs <40 years) and tourniquet use on the occurrence of DVT. Results: No DVTs were detected preoperatively. The incidence of postoperative DVT was significantly lower in the T– group compared with the T+ group (1 patient [1.7%] vs 9 patients [16.4%]; P =.005). All patients with DVT were asymptomatic. Although the mean operative time was not significantly different (80.8 minutes in the T+ group vs 78.5 minutes in the T– group; P =.461), the mean blood loss from the drain was significantly lower in the T– group than in the T+ group (149.9 vs 201.9 mL; P <.001). Age ≥40 years and tourniquet use were significantly related to the occurrence of DVT (odds ratio, 8.3 [95% CI, 1.9-36.8]; P =.005; and odds ratio, 8.8 [95% CI, 1.0-75.3]; P =.047, respectively). Conclusion: ACLRs performed without tourniquet resulted in a significantly lower incidence of DVT after ACLR and significantly less bleeding from drains. If adequate visibility of the surgical field is obtained, ACLR without tourniquet use may reduce the incidence of DVT. [ABSTRACT FROM AUTHOR]

Background: Although various reconstruction techniques are available for anterior cruciate ligament (ACL) injuries, a long recovery time is required before patients return to sports activities, as the reconstructed ACL requires time to regain strength. To date, several studies have reported use of mesenchymal stem cells in orthopaedic surgery; however, no studies have used adipose-derived stem cell (ADSC) sheets in ACL reconstruction (ACLR). Hypothesis: ADSC sheet transplantation can improve biomechanical strength of the autograft used in ACLR. Study Design: Controlled laboratory study. Methods: A total of 68 healthy Japanese white rabbits underwent unilateral ACLR with a semitendinosus tendon autograft after random enrollment into a control group (no sheet; n = 34) and a sheet group (ADSC sheet; n = 34). At 2, 4, 8, 16, and 24 weeks after surgery, rabbits in each group were sacrificed to evaluate tendon-bone healing using histological staining, micro–computed tomography, and biomechanical testing. At 24 weeks, scanning transmission electron microscopy of the graft midsubstance was performed. Results: The ultimate failure load for the control and sheet groups, respectively, was as follows: 17.2 ± 5.5 versus 37.3 ± 10.3 (P =.01) at 2 weeks, 28.6 ± 1.9 versus 47.4 ± 10.4 (P =.003) at 4 weeks, 53.0 ± 14.3 versus 48.1 ± 9.3 (P =.59) at 8 weeks, 66.2 ± 9.3 versus 95.2 ± 43.1 (P =.24) at 16 weeks, and 66.7 ± 27.3 versus 85.3 ± 29.5 (P =.39) at 24 weeks. The histological score was also significantly higher in the sheet group compared with the control group at early stages up to 8 weeks. On micro–computed tomography, relative to the control group, the bone tunnel area was significantly narrower in the sheet group at 4 weeks, and the bone volume/tissue volume of the tendon-bone interface was significantly greater at 24 weeks. Scanning transmission electron microscopy at 24 weeks indicated that the mean collagen fiber diameter in the midsubstance was significantly greater, as was the occupation ratio of collagen fibers per field of view, in the sheet group. Conclusion: ADSC sheets improved biomechanical strength, prevented bone tunnel enlargement, and promoted tendon-bone interface healing and graft midsubstance healing in an in vivo rabbit model. Clinical Relevance: ADSC sheets may be useful for early tendon-bone healing and graft maturation in ACLR. [ABSTRACT FROM AUTHOR]

Introduction: One of the final goals of anatomical anterior cruciate ligament (ACL) reconstruction is the restoration of native anatomy. It is essential to obtain more accurate predictors of mid-substance ACL size before surgery. However, to the best of our knowledge, no study has reported correlation between the mid-substance cross-sectional ACL size and the knee osseous morphology. The purpose of this study was to reveal correlation between the mid-substance cross-sectional ACL size and the knee osseous morphology. Materials and methods: We used 39 non-paired formalin fixed Japanese cadaveric knees. All surrounding muscles, ligaments and soft tissues in the knee were resected. After soft tissue resection, the knee was flexed at 90°, and a tangential plane of the femoral posterior condyles was marked and cut the ACL. Femoral ACL footprint size, Blumensaat's line length, lateral wall of the femoral intercondylar notch size, lateral wall of the femoral intercondylar notch height, tibial ACL footprint size, tibia plateau size, the whole anterior–posterior (AP) length, the medial and the lateral AP length of the tibia plateau, and the medial–lateral (ML) length of the tibia plateau were measured. The Pearson's product movement correlation was calculated to reveal correlation between the mid-substance cross-sectional ACL size and the measured parameters of the knee osseous morphology. Results: The measured mid-substance cross-sectional ACL size was 49.9 ± 16.3 mm2. The tibial ACL footprint size, the tibia plateau size, the whole AP length of the tibia plateau, the lateral AP length of the tibia plateau and the ML length of the tibia plateau were significantly correlated with the mid-substance cross-sectional ACL size. Conclusions: For clinical relevance, some tibial sides of the knee osseous morphology were significantly correlated with the mid-substance cross-sectional ACL size. It might be possible to predict the mid-substance ACL size measuring these parameters. [ABSTRACT FROM AUTHOR]

Background: This clinical guideline presents recommendations for the management of patients with anterior cruciate ligament (ACL) injury, endorsed by the Japanese Orthopaedic Association (JOA) and Japanese Orthopaedic Society of Knee, Arthroscopy and Sports Medicine (JOSKAS).Methods: The JOA ACL guideline committee revised the previous guideline based on "Medical Information Network Distribution Service Handbook for Clinical Practice Guideline Development 2014", which proposed a desirable method for preparing clinical guidelines in Japan. Furthermore, the importance of "the balance of benefit and harm" was also emphasized. This guideline consists of 21 clinical questions (CQ) and 23 background questions (BQ). For each CQ, outcomes from the literature were collected and evaluated systematically according to the adopted study design.Results: We evaluated the objectives and results of each study in order to make a decision on the level of evidence so as to integrate the results with our recommendations for each CQ. For BQ, the guideline committee proposed recommendations based on the literature.Conclusions: This guideline is intended to be used by physicians, orthopedic surgeons, physical therapists, and athletic trainers managing ACL injuries. We hope that this guideline is useful for appropriate decision-making and improved management of ACL injuries. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study was to measure the detailed morphology of the femoral anterior cruciate ligament (ACL) footprint. The correlation and the comparison between the measured area and the area which mathematically calculated as elliptical were also evaluated. Materials and Methods: Thirty nine nonpaired human cadaver knees were used. The ACL was cut in the middle, and the femoral bone was cut at the most proximal point of the femoral notch. The ACL was carefully dissected, and the periphery of the ACL insertion site was outlined on both the whole footprint and the midsubstance insertion. Lateral view of the femoral condyle was photographed with a digital camera, and the images were downloaded to a personal computer. The area, length, and width of the femoral ACL footprint were measured with Image J software (National Institution of Health). Using the length and width of the femoral ACL footprint, the elliptical area was calculated as 0.25 π (length × width). Statistical analysis was performed to reveal the correlation and the comparison of the measured and elliptically calculated area. Results: The sizes of the whole and midsubstance femoral ACL footprints were 127.6 ± 41.7 mm[2] and 61 ± 20.2 mm[2], respectively. The sizes of the elliptically calculated whole and midsubstance femoral ACL footprints were 113.9 ± 4.5 mm[2] and 58.4 ± 3 mm[2], respectively. Significant difference was observed between the measured and the elliptically calculated area. In the midsubstance insertion, significant correlation was observed between the measured and the elliptically calculated area (Pearson's correlation coefficient = 0.603, P= 0.001). However, no correlation was observed in the whole ACL insertion area. Conclusion: The morphology of the femoral ACL insertion resembles an elliptical shape. However, due to the wide variation in morphology, the femoral ACL insertion cannot be considered mathematically elliptical. [ABSTRACT FROM AUTHOR]

Purpose: Although various risk factors for surgical site infection after anterior cruciate ligament reconstruction (ACLR) have been reported, the number of studies with large sample sizes on this topic is limited. The aim of the present study was to clarify the risk factors for early surgical site infection after ACLR in a large cohort using a national database in Japan.Methods: The data of patients who underwent ACLR from 2010 to 2015 were obtained from the Diagnosis Procedure Combination database, which covers approximately half of all hospital admissions in Japan. The outcome measures were the prevalences of surgical site infection and deep surgical site infection after ACLR during hospitalization. The association between the occurrence of surgical site infection and patients' demographic data, including sex, age, body mass index (BMI), smoking status, preoperative steroid use, and comorbidities such as diabetes, hepatic dysfunction, renal dysfunction, and atopic dermatitis, were examined using a multivariable logistic regression model.Results: Among 30,536 patients who underwent ACLR, 288 patients with surgical site infection (0.94%) and 86 with deep surgical site infection (0.28%) were identified. The univariate analysis showed that higher prevalences of surgical site infection and deep surgical site infection were associated with male sex, a higher BMI, atopic dermatitis, and preoperative steroid use. Patients with diabetes or hepatic dysfunction had a significantly higher prevalence of surgical site infection. The multivariable analysis showed that surgical site infection was significantly associated with male sex vs. female sex; odds ratio (OR), 2.90; 95% confidence interval (CI), 2.17-3.89, age of ≤ 19 vs. 20-29 years; OR, 1.56; 95% CI 1.13-2.15, BMI of ≥ 30.0 vs. 18.5-22.9 kg/m2; OR, 1.72; 95% CI 1.16-2.54, diabetes (OR, 2.70; 95% CI 1.28-5.71), atopic dermatitis (OR, 7.19; 95% CI 2.94-17.57), and preoperative steroid use (OR, 6.18; 95% CI 2.32-16.52).Conclusion: Atopic dermatitis, preoperative steroid use, young age (≤ 19 years), obesity (BMI of ≥ 30.0 kg/m2), male sex, and diabetes were independent demographic risk factors for surgical site infection after ACLR. The present study will be useful when surgeons evaluate the risk of SSI after ACLR in terms of demographic aspects.Level Of Evidence: III. [ABSTRACT FROM AUTHOR]

Background: Remnant tissue preservation may be important in improving graft healing after anterior cruciate ligament (ACL) reconstruction, but it has yet to be established whether remnant tissue preservation improves the control of pivot-shift laxity. Hypothesis: The amount of ACL graft coverage with preserved remnant tissue improves the control of pivot-shift laxity, as qualitatively determined with an electromagnetic device. Study Design: Cohort study; Level of evidence, 3. Methods: The 3-dimensional kinematics were evaluated intraoperatively using an electromagnetic sensor system in 38 patients at the time of anatomic double-bundle ACL reconstruction with remnant tissue preservation and again at a minimum of 12 months postoperatively. The magnitude of the peak coupled anterior tibial translation (pCAT) and the maximal acceleration of posterior translation (APT) during the pivot-shift test were evaluated. The degree of graft coverage by remnant tissue was determined arthroscopically at the end of surgery, which was evaluated quantitatively using a scoring system (0-9 points). The relationship between the values during the pivot-shift test and preoperative and intraoperative factors were assessed. Results: The mean (±SD) side-to-side difference of the pCAT (ΔpCAT) was significantly (P < .0001) improved from 14.0 ± 5.0 mm to 2.6 ± 1.1 mm. Also, the mean side-to-side difference of the APT (ΔAPT) was significantly (P < .0001) improved from 525.6 ± 99.7 mm/s2 to 32.9 ± 23.6 mm/s2. The mean initial graft coverage score was 5.3 ± 2.6. The correlation analysis demonstrated that the degree of initial graft coverage was significantly correlated with the ΔpCAT (r = −0.517, P = .0007) and ΔAPT (r = −0.532, P = .0005). The status of the reconstructed graft at second-look arthroscopic surgery showed no significant correlations with the degree of initial graft coverage or the results of the pivot-shift test. Conclusion: The present study demonstrated that the preservation of ACL remnant tissue in anatomic double-bundle ACL reconstruction appears to improve the control of pivot-shift laxity at a minimum of 12 months postoperatively, as measured by an electromagnetic device. This improvement was significantly affected by the degree of intraoperative graft coverage with preserved remnant tissue. [ABSTRACT FROM AUTHOR]

We investigated the incidence of anterior cruciate ligament (ACL) injuries among athletes in junior high school and high school by retrospectively reviewing Japan Sports Council notification data registered over a period of 10 years. The total number of ACL injuries during the 10-year period was 30,458, with an incidence of 0.81 per 1000 athlete-years. Among those with ACL injuries, the ratio of girls to boys was 2.8, and incidence of injury was significantly greater among girls than boys (1.36 as against 0.48). Athletes in the 11th grade demonstrated the highest incidence of ACL injuries. We also found that the greatest incidence of ACL injuries was among female high school basketball players; the second highest being among female high school Judo athletes. For sports with a greater number of ACL injuries and a higher injury rate, it is necessary to obtain more detailed data and analysis to determine an effective prevention programme. [ABSTRACT FROM AUTHOR]

Background: Vascular CD34+ cells in anterior cruciate ligament (ACL) tissue have the potential for high proliferation and multilineage differentiation that can accelerate tendon-bone healing. While patient characteristics, such as age, can affect tendon-bone healing, the influence of elapsed time after injury on the healing process is unclear. Hypothesis: Cells obtained during the early phase after injury will exhibit a greater tendon-bone healing potential compared with chronic phase counterparts when applied to an immunodeficient rat model of ACL reconstruction. Study Design: Controlled laboratory study. Methods: Adult human ACL-ruptured tissue was harvested from patients undergoing arthroscopic primary ACL reconstruction and classified into 2 groups based on the time elapsed between injury and surgery: (1) early group (≤3 months from injury) and (2) chronic group (>3 months from injury). In addition, 76 ten-week-old female immunodeficient rats underwent ACL reconstruction, followed by intracapsular administration of one of the following: (1) ACL-derived cells from the early group (n = 5), (2) ACL-derived cells from the chronic group (n = 5), or (3) phosphate-buffered saline (PBS) only (n = 5). During the 8 weeks after surgery, histological (weeks 2, 4, 8), immunohistochemical (week 2), radiographic (weeks 0, 2, 4, 8), and biomechanical (week 8) analyses were performed to evaluate tendon-bone healing. Results: In the early group, the histological evaluation showed early healing, induction of endochondral ossification–like integration, and mature bone ingrowth. Micro–computed tomography showed that the tibial bone tunnels at week 4 and week 8 were significantly reduced in the early group compared with those in the chronic group and PBS group (P < .05). Moreover, biomechanical tensile strength was significantly greater in the early group than in the other groups (P < .05). An accelerated healing potential in the early group was further demonstrated by the enhancement of intrinsic angiogenesis/osteogenesis and human-derived vasculogenesis/osteogenesis. Conclusion: Compared with human ACL-derived cells obtained during the chronic phase, cells obtained during the early phase after injury have a greater tendon-bone healing potential when used in an immunodeficient rat model of ACL reconstruction. Clinical Relevance: During ACL reconstruction surgery, transplanting ACL remnant tissue in the early phase after injury could accelerate and enhance tendon-bone healing. [ABSTRACT FROM AUTHOR]

Background: Remnant-preserved anterior cruciate ligament (ACL) reconstruction was introduced to improve clinical outcomes and biological healing. However, the effects of remnant preservation and the influence of the delay from injury until reconstruction on the outcomes of this technique are still uncertain. Purpose/Hypothesis: The purposes of this study were to evaluate whether remnant preservation improved the clinical outcomes and graft incorporation of ACL reconstruction and to examine the influence of the delay between ACL injury and reconstruction on the usefulness of remnant preservation. We hypothesized that remnant preservation improves clinical results and accelerates graft incorporation and that its effect is dependent on the delay between ACL injury and reconstruction. Study Design: Cohort study; Level of evidence, 2. Methods: A total of 151 consecutive patients who underwent double-bundle ACL reconstruction using a semitendinosus graft were enrolled in this study: 74 knees underwent ACL reconstruction without a remnant (or the remnant was <25% of the intra-articular portion of the graft; NR group), while 77 knees underwent ACL reconstruction with remnant preservation (RP group). These were divided into 4 subgroups based on the time from injury to surgery: phase 1 was <3 weeks (n = 24), phase 2 was 3 to less than 8 weeks (n = 70), phase 3 was 8 to 20 weeks (n = 32), and phase 4 was >20 weeks (n = 25). Clinical measurements, including KT-1000 arthrometer side-to-side anterior tibial translation measurements, were assessed at 3, 6, 12, and 24 months after reconstruction. Magnetic resonance imaging evaluations of graft maturation and graft-tunnel integration of the anteromedial and posterolateral bundles were assessed at 3, 6, and 12 months after reconstruction. Results: There was no difference in side-to-side anterior tibial translation between the NR and RP groups. There was also no difference in graft maturation between the 2 groups. Furthermore, the time from ACL injury until reconstruction did not affect graft maturation, except in the case of very long delays before reconstruction (phase 4). Graft-tunnel integration was significantly increased in both groups in a time-dependent manner. However, there was no difference between the NR and RP groups. Conclusion: Remnant preservation did not improve knee stability at 2 years after ACL reconstruction. Furthermore, remnant preservation did not accelerate graft incorporation, especially during the acute and subacute injury phases. [ABSTRACT FROM AUTHOR]

Background: The anterior cruciate ligament (ACL) does not heal spontaneously after injury, and ACL patients of different ages respond differently to treatment. Although ACL-derived CD34-positive cells contribute to bone-tendon healing after ACL reconstruction, the relationship between the healing potential of ACL-derived cells and a patient's age is unknown. Hypothesis: ACL-derived cells from young patients will have a greater effect on the maturation of bone-tendon integration in an immunodeficient rat model of ACL reconstruction compared with cells derived from older patients. Study Design: Controlled laboratory study. Methods: Sixty 10-week-old female immunodeficient rats underwent ACL reconstruction (using the autologous flexor digitorum longus tendon as a graft) followed by intracapsular administration of ACL-derived cells from patients aged 10 to 19 years (younger group) or patients aged 30 to 39 years (older group), or they were given phosphate-buffered saline (PBS; PBS group). Histologic, radiographic, and biomechanical examinations were performed 2 to 8 weeks after surgery. In addition, intrinsic and human cell– derived angiogenesis and osteogenesis were examined by immunohistochemistry. Results: In the younger group, histologic assessment demonstrated early bone-tendon healing, which induced endochondral ossification-like integration. Micro–computed tomography showed a statistically significant reduction in the area of tibial bone tunnel in the younger group (week 4, 20.0% ± 11.2% reduction; week 8, 25.7% ± 5.6% reduction) compared with the older group (week 4, 1.8% ± 3.0% reduction; week 8, 4.0% ± 5.9% reduction) and the PBS group (week 4, -0.5% ± 3.2% reduction; week 8, 3.3% ± 5.2% reduction) (week 4, P<.05; week 8, P<.01). Failure loads during tensile testing demonstrated a significantly higher ultimate load to failure in the younger group (17.52 ± 4.01 N) compared with the older (8.05 ± 2.91 N) and PBS (7.01 ± 3.16 N) groups (P<.05), and isolectin B4 and rat osteocalcin immunostaining indicated enhanced intrinsic angiogenesis and osteogenesis in the younger group. There was no statistically significant difference in the results of radiographic and biomechanical examinations between the older and PBS groups. Double immunohistochemistry for human-specific endothelial cell and osteoblast markers demonstrated a greater ability of differentiation into endothelial cells and osteoblasts in the younger group. Conclusion: ACL-derived cells from younger patients enhanced early bone-tendon healing in an immunodeficient rat model of ACL reconstruction. Clinical Relevance: Surgeons should consider a patient's age when performing ACL reconstruction with remnant preservation or ruptured tissue incorporation, as this can predict healing ability. [ABSTRACT FROM AUTHOR]

The article presents research which examined the age-related differences in cells derived from the anterior cruciate ligament (ACL). Topics covered include the description of ACL tissues in adolescent and younger patients as well as collection of ACL remnants from 28 patients. Also mentioned is the need for surgeons to consider the age of patients when assessing healing potential of those with ACL injuries.

The article presents research which focused on the anatomy of the anterior cruciate ligament (ACL). Topics covered include the importance of ACL tibial footprint to bone near the ligament as well as the significance of tibial tunnel position to attain ACL stability after surgery. Also mentioned is the effectiveness of computed tomography imaging to assess ACL injuries.

The article presents a study that evaluates the incidence of roof impingement by the native anterior cruciate ligament (ACL) in hyperextensible knees. The study examines the risk of roof impingement by anatomic placement of the ACL graft in hyperextensible knees. It urges surgeons to consider roof impingement after anatomic double-bundle ACLreconstruction in patients with a hyperextensible knee.

Objective To investigate the expression and function of Mohawk (MKX) in human adult anterior cruciate ligament (ACL) tissue and ligament cells from normal and osteoarthritis (OA)-affected knees. Methods Knee joints were obtained at autopsy (within 24-48 hours postmortem) from 13 donors with normal knees (mean ± SD age 36.9 ± 11.0 years), 16 donors with knee OA (age 79.7 ± 11.4 years), and 8 aging donors without knee OA (age 76.9 ± 12.9 years). All cartilage surfaces were graded macroscopically. MKX expression was analyzed by immunohistochemistry and quantitative polymerase chain reaction. ACL-derived cells were used to study regulation of MKX expression by interleukin-1β (IL-1β). MKX was knocked down with small interfering RNA (siRNA) to analyze the function of MKX in extracellular matrix (ECM) production and differentiation in ACL-derived cells. Results The expression of MKX was significantly decreased in ACL-derived cells from OA knees compared with normal knees. Consistent with this finding, immunohistochemistry analysis showed that MKX-positive cells were significantly reduced in ACL tissue from OA donors, in particular in cells located in disorientated fibers. In ACL-derived cells, IL-1β strongly suppressed MKX expression and reduced expression of the ligament ECM genes COL1A1 and TNXB. In contrast, SOX9, a chondrocyte master transcription factor, was up-regulated by IL-1β treatment. Importantly, knockdown of MKX expression with siRNA up-regulated SOX9 expression in ACL-derived cells, whereas the expression of COL1A1 and TNXB was reduced. Conclusion Reduced expression of MKX is a feature of degenerated ACL in OA-affected joints, and this may be mediated in part by IL-1β. MKX appears necessary to maintain the tissue-specific cellular differentiation status and ECM production in adult human tendons and ligaments. [ABSTRACT FROM AUTHOR]

The article discusses the effect of intra-articular injection of MicroRNA-210 (miRNA miR-210) on ligament healing in a rat model. It examines the effect of intra-articular injection of miRNA miR-210 on acceleration of anterior cruciate ligament (ACL) healing. It states that the injection of double-stranded miR-210 promoted the healing of partially torn ACLs by the enhancement of angiogenesis through the upregulation of vascular endothelial growth factor and fibroblast growth factor 2.

Background: A sheep or goat anterior cruciate ligament (ACL) reconstruction model with the semitendinosus tendon autograft has not as of yet been established.Hypothesis: The semitendinosus tendon graft may be necrotized after ACL reconstruction until 12 weeks. Structural properties of the femur-graft-tibia complex may not be restored to the normal ACL level even at 12 months after surgery.Study Design: Controlled laboratory study.Methods: Thirty-eight mature sheep were used. In each animal, the right knee underwent ACL reconstruction using the semitendinosus tendon autograft. Two of them were not tested because of pneumonia. Twenty of 36 sheep were used for biomechanical evaluations. Five randomly selected animals were sacrificed at 0, 12, 24, or 52 weeks after surgery. In each animal, both the knees were harvested, and the left knee was used to obtain the control data. The remaining 16 sheep were used for histological evaluation. Two or 3 randomly selected animals were sacrificed at 0, 2, 6, 12, 24, or 52 weeks after surgery.Results: The tendon graft was predominantly acellular at 2 weeks. Although cell infiltration increased at 6 weeks, the core portion remained necrotic even at 12 weeks. At 24 and 52 weeks, the necrotic lesion disappeared in the core portion. In each period, the anteroposterior translation of the reconstructed knee remained significantly greater than that of the control (P < .0001). At 52 weeks, the maximum load of the femur-graft-tibia complex was significantly lower than that of the femur-ACL-tibia complex (P < .0001), although there was no significant difference in the cell density, the tissue dimensions, the stiffness, and the elongation at failure between the 2 complexes.Conclusion: The sheep ACL reconstruction model showed predominant intrinsic fibroblast necrosis in the tendon autograft until 12 weeks. Although the structural properties of the femur-graft-tibia complex gradually improved, they were not completely restored to the femur-ACL-tibia complex level even at 52 weeks.Clinical Relevance: Remodeling of the semitendinosus tendon autograft after ACL reconstruction is not different from that of the bone-tendon-bone graft. This study has suggested that vigorous activity should not be permitted for patients in the early periods after ACL reconstruction using semitendinosus tendon autografts, which are necrotized and weakened after surgery. [ABSTRACT FROM PUBLISHER]

Background: Repair of complete radial meniscal tears is a key to restoring the mechanical integrity necessary to maintain hoop tension in the meniscus. The primary stability of the meniscal repair is one of the most important factors for meniscal healing, but the biomechanical structural properties of different repair techniques for complete radial meniscal tears remain unknown.Hypothesis: Our novel cross-suture technique with suturing oblique to the collagen fibrils of the meniscus will yield better fixation than the standard double horizontal suture technique with suturing parallel to the collagen fibrils in the meniscus.Study Design: Controlled laboratory study.Methods: Biomechanical investigation was performed on 40 fresh human menisci (2 groups of 20 menisci each) from patients who underwent total knee arthroplasty. In the cross-suture technique group (group A), the sutures crossed over 5 mm from the tear and 5 mm and 10 mm from the rim. In the double horizontal suture technique group (group B), the sutures were parallel and had the same attachment points as group A. The specimens were cyclically loaded 500 times between 5 and 30 N and then loaded to failure after completion of the cyclic load testing.Results: Compared with the double horizontal suture group, the cross-suture group had a significantly higher ultimate failure load (78.96 ± 19.27 N vs 68.16 ± 12.92 N; P < .05), significantly greater stiffness (8.01 ± 1.54 N/mm vs 6.46 ± 1.12 N/mm; P < .05), and significantly lower displacement (5.74 ± 1.84 mm vs 8.56 ± 2.39 mm; P < .05) after a 500–cycle loading protocol.Conclusion: Our cross-suture technique significantly improved the structural properties of the repaired complete radial meniscal tears.Clinical Relevance: The cross-suture technique for repair of radial meniscal tears provides high stability and could be a promising solution in young and in active patients. [ABSTRACT FROM PUBLISHER]

Background: Controversy persists as to whether double-bundle reconstruction of the anterior cruciate ligament (ACL) has any clinical advantage over single-bundle reconstruction. Several studies have used subjective and nonquantitative manual tests to evaluate the rotatory stability of the knee. The authors have developed a method to quantitate the rotatory stability of the ACL-deficient knee using open magnetic resonance imaging (MRI).Hypothesis: Anatomic double-bundle reconstruction restores rotatory stability significantly better than does single-bundle reconstruction.Study Design: Cohort study; Level of evidence, 3.Methods: Twenty-three consecutive patients treated with the single-bundle reconstruction (group S) and 25 consecutive patients treated with the anatomic double-bundle reconstruction (group D) were evaluated. Both reconstruction procedures were performed using hamstring tendon autografts. The Slocum anterolateral rotatory instability (ALRI) test was performed 1 year after surgery using open MRI. To assess rotatory stability, we measured the difference in anterior tibial translation between medial and lateral compartments in the sagittal plane and defined this difference as the ALRI value. In addition, clinical examinations consisting of the Lysholm knee score, Tegner activity score, KT-2000 arthrometer anterior translation examination, and the pivot-shift test were carried out.Results: The mean side-to-side difference in ALRI values was significantly less (P < .001) in double-bundle reconstruction (mean, 1.2 mm) than in single-bundle reconstruction (mean, 4.1 mm). The mean side-to-side difference in KT-2000 arthrometer measurements was significantly less (P = .014) in double-bundle reconstruction (mean, 1.2 mm) than in single-bundle reconstruction (mean, 2.6 mm). The difference in the incidence of positive pivot-shift tests between group S (43%) and group D (16%) did not reach the level of statistical significance (P = .058). No significant differences in Lysholm score or Tegner score between the groups were observed.Conclusion: The rotatory stability of anatomic double-bundle reconstruction was significantly better than the rotatory stability of single-bundle reconstruction. [ABSTRACT FROM AUTHOR]

Background: Knee hyperextension and tibial posterior slope are related to sagittal alignment of the knee. The relationship of sagittal alignment to noncontact anterior cruciate ligament (ACL) injuries has been reported with conflicting results.Purpose: To determine whether there is a difference in sagittal alignment of the knee between an ACL-deficient group and a negative control group and to find risk factors contributing to noncontact ACL injuries.Study Design: Cross-sectional study; Level of evidence, 3.Methods: Magnetic resonance images of the knee in full extension were acquired in the patient group, which consisted of 33 male and 40 female patients with noncontact ACL injuries, and in the negative control group, which consisted of 28 male and 30 female participants. Three angles were measured: the angle between the femoral axis and the tibial axis, designated as the extension angle; the femoral plateau angle, between the femoral axis and a line tangent to the concave profile of the medial tibial plateau (P line); and the tibial posterior slope angle, 90° minus the angle made by the intersection of the tibial axis and the P line.Results: In the female group, the femoral plateau angle and the tibial posterior slope angle were significantly larger in the ACL-deficient patients than in the negative control group, although these differences were not seen in the male group. In the female subjects, a negative correlation between the extension angle and the tibial posterior slope angle was seen in the ACL-deficient group, suggesting that knees with hyperextension had a small tibial posterior slope, whereas knees without hyperextension had a large tibial posterior slope.Conclusion: There were 2 types of large femoral plateau angles: one had its origin in an increasing tibial posterior slope; the other resulted from hyperextension of the knee. Large posterior tibial slope and hyperextension are both correlated with noncontact ACL injury in women. [ABSTRACT FROM AUTHOR]

Background: The structural properties of a tendon autograft deteriorate during the remodeling phase after anterior cruciate ligament (ACL) reconstruction.Hypothesis: A local application of autologous synovium-derived cells cultured in medium supplemented with transforming growth factor β (TGFβ) may inhibit the deterioration of structural properties of the tendon graft after ACL reconstruction.Study Design: Controlled laboratory study.Methods: Fifty-two mature sheep were used. In each animal, the right knee underwent ACL reconstruction using the semitendinosus tendon autograft; then, the animals were divided into 5 groups of 10. No additional treatments were applied in group 1, whereas fibrin sealant was applied around the graft in group 2. In group 3, autologous synovium-derived cells cultured in standard medium were applied around the graft with fibrin sealant, whereas autologous synovium-derived cells cultured in TGFβ-supplemented medium were applied with fibrin sealant in group 4. In group 5, fibrin sealant containing 20 ng of TGFβ was applied around the graft. Each animal was sacrificed at 12 weeks after the surgery. In each group, 7 and 3 sheep were used for biomechanical and histologic evaluations, respectively. The remaining 2 sheep were used to confirm whether the applied cells infiltrated the graft at 1 week after surgery.Results: Confocal microscope observations showed that the applied cells that were labeled before implantation infiltrated into the superficial portion of the graft at 1 week. Biomechanically, the maximum load and the stiffness of groups 4 and 5 were significantly greater than those of groups 1, 2, and 3. Histologically, necrotic lesions were observed in the core portion of the midsubstance in groups 1 and 2. In groups 3, 4, and 5, no necrotic lesions were found in the midsubstance.Conclusion: A local application of autologous synovium-derived cells cultured in TGFβ-supplemented medium or a fibrin sealant containing TGFβ significantly inhibits the natural deterioration of the structural properties of the tendon graft after ACL reconstruction.Clinical Relevance: Administration of autologous synovium-derived cells cultured in TGFβ-supplemented medium or TGFβ and fibrin glue alone can be a potential cell-based therapy to prevent graft deterioration after transplantation or accelerate mechanical restoration of the deteriorated graft. [ABSTRACT FROM AUTHOR]

Our study aimed to investigate the effect of an anterior cruciate ligament injuries prevention program. Fifty-one female basketball players from high school participated in our study. Measurement was conducted before and after a 10-week prevention program. In alignment measurement, the distance between the hips, knees was measured during a drop-jump test, and the ratio of knee distance to hip distance (K/H ratio) was calculated. An isometric knee flexion test was also conducted by a hand-held dynamometer. After 10 weeks, this prevention program was continued for a further 12-month period. In the group of knee-in alignment, the K/H ratio was improved, and knee flexion muscular strength also improved. The incidence of ACL injuries was not significant, but non-contact ACL injuries decreased compared to the three years prior to conducting this prevention program. By conducting this prevention program, the possibility of decreasing non-contact ACL injuries and improvement of alignment is suggested. [ABSTRACT FROM AUTHOR]

The article presents abstracts on medical topics which include one on the effects of new knee braces on the knee osteoarthritis (OA) patients of Japan, one on electromyographic analysis of the supraspinatus and infraspinatus muscles during activities of daily living (ADL) under abduction orthosis and on the virtual anthroscopy by using multi-detector-row CT and air-arthrography.

Background: An intact anterior cruciate ligament (ACL) is thought to be prerequisite for successful unicompartmental knee arthroplasty (UKA), but recent studies reported successful midterm results of UKA in ACL-deficient (ACLD) knees. We hypothesized that ACLD is not always a contraindication for medial UKA when preoperative radiographs showed typical anteromedial knee patterns., Methods: From April 2012 to March 2016, 401 Oxford mobile-bearing UKAs in 282 patients were retrospectively identified from our database. Patients whose ACL was severely damaged, but preoperative X-rays showed typical anteromedial osteoarthritis patterns, were categorized into the ACLD group. From intraoperative data, those whose ACL was intact were categorized into the ACL functional (ACLF) group. There were 32 and 369 knees in the ACLD and ACLF groups, respectively, and mean follow-up periods were 66.1 and 63.8 months for the ACLD and ACLF groups, respectively. We compared the postoperative clinical outcome and component survivorship, with an endpoint of component revision, between ACLD groups and ACLF groups., Results: In both groups, the Oxford knee score, Knee Society score, Tegner activity score, and knee range of motion in extension were improved after surgery. The UKA component survival rate at five years was 100% in the ACLD group and 98.9% in the ACLF group. There were no significant differences between the groups., Conclusion: Mid-term clinical outcomes of Oxford mobile-bearing UKA in ACLD knees were similar to those in ACLF knees. ACL deficiency is not always a contraindication for medial unicompartmental knee arthroplasty in patients with typical anteromedial osteoarthritis radiographs., (Copyright © 2020 Elsevier Inc. All rights reserved.)