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Purpose: To investigate the effect of technology-assisted Anterior Cruciate Ligament Reconstruction (ACLR) on post-operative clinical outcomes and tunnel placement compared to conventional arthroscopic ACLR. Methods: CENTRAL, MEDLINE, and Embase were searched from January 2000 to November 17, 2022. Articles were included if there was intraoperative use of computer-assisted navigation, robotics, diagnostic imaging, computer simulations, or 3D printing (3DP). Two reviewers searched, screened, and evaluated the included studies for data quality. Data were abstracted using descriptive statistics and pooled using relative risk ratios (RR) or mean differences (MD), both with 95% confidence intervals (CI), where appropriate. Results: Eleven studies were included with total 775 patients and majority male participants (70.7%). Ages ranged from 14 to 54 years (391 patients) and follow-up ranged from 12 to 60 months (775 patients). Subjective International Knee Documentation Committee (IKDC) scores increased in the technology-assisted surgery group (473 patients; P = 0.02; MD 1.97, 95% CI 0.27 to 3.66). There was no difference in objective IKDC scores (447 patients; RR 1.02, 95% CI 0.98 to 1.06), Lysholm scores (199 patients; MD 1.14, 95% CI − 1.03 to 3.30) or negative pivot-shift tests (278 patients; RR 1.07, 95% CI 0.97 to 1.18) between the two groups. When using technology-assisted surgery, 6 (351 patients) of 8 (451 patients) studies reported more accurate femoral tunnel placement and 6 (321 patients) of 10 (561 patients) studies reported more accurate tibial tunnel placement in at least one measure. One study (209 patients) demonstrated a significant increase in cost associated with use of computer-assisted navigation (mean 1158€) versus conventional surgery (mean 704€). Of the two studies using 3DP templates, production costs ranging from $10 to $42 USD were cited. There was no difference in adverse events between the two groups. Conclusion: Clinical outcomes do not differ between technology-assisted surgery and conventional surgery. Computer-assisted navigation is more expensive and time consuming while 3DP is inexpensive and does not lead to greater operating times. ACLR tunnels can be more accurately located in radiologically ideal places by using technology, but anatomic placement is still undetermined because of variability and inaccuracy of the evaluation systems utilized. Level of evidence: Level III. [ABSTRACT FROM AUTHOR]

Purpose: Patellar maltracking caused by a rupture of the medial patellofemoral ligament (MPFL) can be improved by MPFL reconstruction (MPFL-R) with a tendon graft. Nonresorbable suture tape (FiberTape®, FT) is possibly becoming an option to tendon grafts for MPFL-R. Patella-side fixation of FT can be performed with suture anchors or via soft-tissue fixation. The aim of this study was to investigate patellar tracking considering soft-tissue-based and anchor-based patella-side fixation techniques. Methods: In eight fresh-frozen human knee joint specimens (m/f 4/4; age 75 ± 10 years), the MPFL was identified, and a rupture was placed near the femoral insertion site. In the study group (SG; 4 knees), soft-tissue fixation of the FT was performed at the medial patellar retinaculum; in the control group (CG; 4 knees), FT was fixed at the patella via suture anchors. For native MPFL (nMPFL), ruptured ("injured") MPFL (iMPFL) and reconstructed MPFL (FT-MPFL-SG, respectively, FT-MPFL-CG) cone beam CT scans were performed in 15°, 30°, and 45° of knee joint flexion. Patellar tracking was assessed using the radiological parameters patellar tilt (PT), congruence angle (CA) and posterior patellar edge-trochlear groove ratio (PTR). Results: All recorded radiological parameters increased, respectively, decreased in the CG and SG from the nMPFL to the iMPFL state. After MPFL-R, all parameters normalized when compared to the intact state (nMPFL), regardless of patella-side fixation technique. All investigated parameters of patellotrochlear alignment were positively, respectively, negatively significantly (p < 0.05) correlated throughout all evaluated conditions (nMPFL, iMPFL, FT-MPFL-SG, FT-MPFL-CG). Conclusion: MPFL-R with a nonresorbable suture tape can normalize patellar maltracking in fresh-frozen human knee joint specimens in earlier degrees of knee joint flexion independent of patella-side fixation technique. The investigated parameters of patellotrochlear alignment correlate with each other. [ABSTRACT FROM AUTHOR]

Purpose: Isolated MPFL reconstruction (iMPFLR) is increasingly used for the surgical treatment of treatment for recurrent patella dislocation. The purpose of this study was to evaluate the influence of tunnel widening and migration on clinical outcomes after iMPFL using a CT-scannographic analysis at 6 months postoperatively. Methods: One hundred and sixty patients (91 females for 69 males) with an average age of 23 years [14–54] who underwent iMPFLR and had an evaluation scan at 6 months postoperatively were evaluated with a mean follow-up of 97 ± 89 months [12 to 166]. Functional International Knee Documentation Committee (IKDC) Score, Kujala score, and joint mobility were assessed preoperatively, at 6 months and at the latest follow-up. The IKDC and Kujala scores were expressed as the difference between pre- and postoperative scores (dIKDC and dKujala). The position of the femoral tunnel was assessed according to the Schöttle criteria on post-operative radiographic profiles. Tunnel widening (at three levels of measurement) and the migration of the center of the tunnel were studied on a CT-scan analysis at 6 months. Any correlation and regression between the evolution of the clinical scores and the measured scannographic parameters were investigated. The relationships between tunnel position and tunnel changes were also studied. Results: Between pre- and post-op, the IKDC (45 ± 13 to 80 ± 15, p < 0.001) and Kujala (55 ± 11 to 87 ± 12, p < 0.001) scores were significantly improved. Patients with tunnel changes had decreased clinical and functional results at 6 months post-op of an iMPFLR (p < 0.001). These changes in the femoral tunnel, evidenced by a tunnel entrance widening and migration of the tunnel center, were related to an initial malposition of the tunnel (p < 0.001). Conclusion: In iMPFLR, changes in the femoral tunnel, corresponding to dilatation and migration of the tunnel center, may occur. These changes are increased by the initial malpositioning of the femoral tunnel and are correlated with less good clinical and functional outcomes. Level of evidence: Level IV. [ABSTRACT FROM AUTHOR]

Purpose: This study aimed to investigate the bony surface characteristic of the femoral attachment of the medial patellofemoral ligament (MPFL) and the correlation between the relevant layered structures, including muscular aponeurosis and the joint capsule, which contribute to patellofemoral joint (PFJ) stability. Methods: The morphology of the medial aspect of the medial condyle using micro-computed tomography and analysed cortical bone thickening in 24 knees was observed. For the macroscopic and histological analyses, 21 and 3 knees were allocated, respectively. The Kruskal–Wallis one-way analysis of variance test with Dunn post hoc testing was performed for statistical analysis. Results: At the level of the adductor tubercle, there were no significant differences in cortical bone thickness. At the level of the medial epicondyle (MEC), cortical bone thickness was considerably greater than that in other areas of the medial condyle (mean ± standard deviation, 0.60 ± 0.20 mm; p < 0.0001). Macroscopic analysis revealed that the deep aponeurosis of the vastus medialis obliquus and the tendinous arch of the vastus intermedius distally formed the composite membrane and adjoined to the joint capsule to firmly attach to MEC, which was located at 41.3 ± 5.7 mm posterior and 14.2 ± 3.1 mm superior to the joint cartilage. Histological analysis showed a composite membrane and adjoining capsule attached to MEC via fibrocartilage. Conclusion: MPFL could be interpreted as part of the deep aponeurosis of the vastus medialis obliquus (VMO) and the tendinous arch of the vastus intermedius, which combined with the joint capsule to attach to MEC. The cortical bone thickening indicated that the tensile stresses were loaded on MEC in aged cadavers. Involvement of VMO and vastus intermedius aponeuroses in restored graft of MPFL could utilise the dynamic stability of surrounding muscles to mimic a native structure. [ABSTRACT FROM AUTHOR]

Purpose: The goal is to evaluate contralateral knee joint laxity and ascertain whether or not contralateral symmetry is observable. Secondary, a validation of a knee laxity testing rig is provided. Methods: Seven pairs of cadaveric knee specimens have been tested under passive conditions with and without external loads, involving a varus/valgus and an external/internal rotational torque and an anteroposterior shear force. Results: Through the range of motion, the width of the varus/valgus laxity, internal/external laxity and anterior/posterior laxity for the medial and lateral compartment show no significant differences between left and right leg. These findings allow us to validate the setup, especially for relative values of laxity based on anatomical measures and knee joint biomechanics. Conclusion: A multidirectional laxity symmetry has been demonstrated for the intact knee and its contralateral knee in passive conditions as in an anesthetized patient. The passive laxity evaluation setup has been validated. Our work furthermore demonstrated a pronounced difference in anteroposterior mobility between the medial and lateral compartment of the knee, with a more stable medial side and more mobile lateral side. Clinical relevance: The contralateral knee can be used as reference for determining optimal knee laxity peri-operatively in total knee replacement and ligament reconstruction. Level of evidence: Level IV, Case series [ABSTRACT FROM AUTHOR]

Purpose: Arthroscopic lateral retinacular release (LRR) has long been considered the gold standard for the treatment for anterior knee pain caused by lateral retinacular tightness (LRT). However, one-third of patients experience continuous pain postoperatively, which is thought to be related to persistent maltracking of the patella and altered femoro-tibial kinematics. Therefore, the aim of the present study was to simultaneously assess femoro-tibial and patello-femoral kinematics and identify the influence of arthroscopic LRR. Methods: Sixteen healthy volunteers and 12 patients with unilateral, isolated LRT were prospectively included. Open MRI scans with and without isometric quadriceps contraction were performed in 0°, 30° and 90° of knee flexion preoperatively and at 12 months after surgery. Patellar shift, tilt angle, patello-femoral contact area and magnitude of femoro-tibial rotation were calculated by digital image processing. Results: Postoperatively, patellar shift was significantly reduced at 90° of knee flexion compared to preoperative values. The postoperative patellar tilt angle was found to be significantly smaller at 30° of knee flexion compared to that preoperatively. Isometric muscle contractions did not considerably influence patellar shift or tilt in either group. The patello-femoral contact area increased after LRR over the full range of motion (ROM), with significant changes at 0° and 90°. Regarding femoro-tibial kinematics, significantly increased femoral internal rotation at 0° was observed in the patient group preoperatively, whereas the magnitude of rotation at 90° of knee flexion was comparable to that of healthy individuals. The pathologically increased femoral internal rotation at 30° without muscular activity could be significantly decreased by LRR. With isometric quadriceps contraction no considerable improvement of femoral internal rotation could be achieved by LRR at 30° of knee flexion. Conclusions: Patello-femoral and femoro-tibial joint kinematics could be improved, making LRR a viable surgical option in carefully selected patients with isolated LRT. However, pathologically increased femoral internal rotation during early knee flexion remained unaffected by LRR and thus potentially accounts for persistent pain. Level of evidence: II. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study is two-fold: (1) to describe the femoral reference point of the medial patellofemoral ligament (MPFL) on a virtual true lateral radiograph reconstructed from a three-dimensional computed tomography (3D-CT) image and (2) to compare this point with that of patients without patellofemoral instability and with Schöttle's point. Methods: A total of 26 consecutive patients (29 affected knees) with recurrent patellar dislocation (RPD), who underwent MPFL reconstruction were included in this study (4 males; 22 females; mean age, 24.0 years old). Using a true lateral 3DCT image, the MPFL femoral insertion was identified and marked with a 2-mm circle, and this image was reconstructed as a virtual true lateral radiograph. Following Schöttle's method, the point of intersection was described by their anterior–posterior and proximal–distal positions. As a control population, 29 age- and gender-matched patients with anterior cruciate ligament (ACL) injuries were also analysed. Results: The points in RPD patients were located significantly posterior (-2.5 ± 2.3 mm, p < 0.01) to the line representing an extension of the posterior cortex of the femur and distal (− 6.9 ± 2.4 mm, p < 0.01) to the posterior origin of the medial femoral condyle compared with those in the control population. The mean reference point of RPD patients was located in a 3.8-mm posterior and 4.4-mm distal position compared with Schöttle's point. Conclusions: An anatomical and radiographic femoral reference point of the MPFL on a true lateral virtual radiograph was described with our method. In patients with RPD, this reference point was identified to be more posterior and distal to Schöttle's point. More anatomical and individualized MPFL reconstruction will be secured using our method. Level of evidence: Level IV. [ABSTRACT FROM AUTHOR]

Purpose: In patients with open growth plates, the direction of tunneling that avoids distal femoral physis (DFP) damage in anatomic reconstructions of the medial patellofemoral ligament (MPFL) has been a topic of discussion. The objective of this study was to determine the ideal orientation for anatomic reconstructions of MPFL tunneling that minimized DFP damage while avoiding breaching the intercondylar notch. Methods: Eighty magnetic resonance images of patients aged 10 through 17 were obtained, randomly sampled from the institutional database. A de novo software was developed to obtain 3D models of the distal femur and DFP. In each model, the anatomical insertion point of the MPFL was determined as defined by Stephen. A 20-mm-depth drilling was simulated, starting from the insertion point at every possible angle within a 90° cone using 5-, 6- and 7-mm drills. Physeal damage for each pair of angles and each drill size was determined. Damage was expressed as a percentage of total physis volume. Statistical analysis was conducted using Student's t test and one-way ANOVA. Results: Maximum physeal damage (5.35% [4.47–6.24]) was obtained with the 7-mm drill when drilling 3° cephalic and 15° posterior from insertion without differences between sexes (n.s.). Minimal physeal damage (0.22% [0.07–0.37]) was obtained using the 5-mm drill aimed 45° distal and 0° anteroposterior, not affected by sex (n.s.). Considering intra-articular drilling avoidance, the safest zone was obtained when aiming 30°–40° distal and 5°–35° anterior, regardless of sex. Conclusion: Ideal femoral tunnel orientation, avoiding physeal damage and breaching of the intercondylar notch, was obtained when aiming 30°–40° distal and 5°–35° anterior, regardless of sex. This area is a safe zone that allows anatomic MPFL reconstruction of patients with an open physis. [ABSTRACT FROM AUTHOR]

Purpose: To biomechanically evaluate MPTL reconstruction and compare it with two techniques for MPFL reconstruction in regard to changes in patellofemoral contact pressures and restoration of patellar stability. Methods: This is an experimental laboratory study in eight human cadaveric knees. None had patellofemoral cartilage lesions or trochlear dysplasia as evaluated by conventional radiographs and MRI examinations. The specimens were secured in a testing apparatus, and the quadriceps was tensioned in line with the femoral shaft. Contact pressures were measured using the TekScan sensor at 30°, 60° and 90°. The sensor was placed in the patellofemoral joint through a proximal approach between femoral shaft and quadriceps tendon to not violate the medial and lateral patellofemoral complex. TekScan data were analysed to determine mean contact pressures on the medial and lateral patellar facets. Patellar lateral displacement was evaluated with the knee positioned at 30° of flexion and 9 N of quadriceps load, then a lateral force of 22 N was applied. The same protocol was used for each condition: native, medial patellofemoral complex lesion, medial patellofemoral ligament reconstruction (MPFL-R) using gracilis tendon, MPFL-R using quadriceps tendon transfer, and medial patellotibial ligament reconstruction (MPTL-R) using patellar tendon transfer. Results: No statistical differences were found for mean and peak contact pressures, medial or lateral, among all three techniques. However, while both techniques of MPFL-R were able to restore the medial restraint, MPTL-R failed to restore resistance to lateral patellar translation to the native state (mean lateralization of the patella [mm]: native: 9.4; lesion: 22; gracilis MPFL-R: 8.1; quadriceps MPFL-R: 11.3; MPTL-R: 23.4 (p < 0.001). Conclusion: MPTL-R and both techniques for MPFL-R did not increase patellofemoral contact pressures; however, MPTL-R failed to provide a sufficient restraint against lateral patellar translation lateral translation in 30° of flexion. It, therefore, cannot be recommended as an isolated procedure for the treatment of patellar instability. [ABSTRACT FROM AUTHOR]

Purpose: A comprehensive understanding of the biomechanical properties of the medial patellofemoral complex (MPFC) is necessary when performing an MPFC reconstruction. How components of the MPFC change over the course of flexion can influence the surgeon's choice of location for graft fixation along the extensor mechanism. The purpose of this study was to (1) determine native MPFC length changes throughout a 90° arc using an anatomically based attachment and using Schöttle's point, and (2) compare native MPFC length changes with different MPFC attachment sites along the extensor mechanism. Methods: Eight fresh-frozen (n = 8), cadaveric knees were dissected of all soft tissue structures except the MPFC. The distance between the femoral footprint (identified through anatomical landmarks and Schottle's point) and the MPFC was calculated at four attachment sites along the extensor mechanism [midpoint of the patella [MP], the center of the osseous footprint of the MPFC (FC), the superomedial corner of the patella at the quadriceps insertion (SM), and the proximal extent of the MPFC along the quadriceps tendon (QT)] at 0°, 20°, 40°, 60°, and 90° of flexion. Results: Length changes were investigated between the MPFL femoral attachment site and the radiographic surrogate of the MPFL attachment site, Schottle's Point (SP). Paired t tests at each of the four components showed no differences in length change from 0° to 90° when comparing SP to the anatomic MPFC insertion. MPFL length changes from 0° to 90° were greatest at the QT point (13.9 ± 3.0 mm) and smallest at the MP point (2.7 ± 4.4 mm). The FC and SM points had a length change of 6.6 ± 4.2 and 9.0 ± 3.8, respectively. Finally, when examining how the length of the MPFC components changed through flexion, the greatest differences were seen at QT where all comparisons were significant (p < 0.01) except when comparing 0° vs 20° (n.s.). Conclusion: The MPFC demonstrates the most significant length changes between 0° and 20° of flexion, while more isometric behavior was seen during 20°–90°. The attachment points along the extensor mechanism demonstrate different length behaviors, where the more proximal components of the MPFC display greater anisometry through the arc of motion. When performing a proximal MPFC reconstruction, surgeons should expect increased length changes compared to reconstructions utilizing distal attachment sites. [ABSTRACT FROM AUTHOR]

Purpose: Biceps tenodesis is widely used as a primary treatment for long head of the biceps brachii pathology and superior labral anterior and posterior (SLAP) lesions. However, rates and timing of full return to sports (RTSs)/duty have not been systematically analysed. This systematic review examines the literature to ascertain the rate and timing of return to athletic activity, and the availability of specific criteria for safe return to atheletic activity following the biceps tenodesis. Methods: Based on PRISMA guidelines, this systematic review utilised the EMBASE, MEDLINE, and The Cochrane Library Databases. Eligible for inclusion were clinical studies reporting on return to athletic activity following biceps tenodesis. Statistical analysis was performed using SPSS. Results: This review identified 17 studies including 374 cases meeting the inclusion criteria. The majority of patients were men 260 (69.7%), with an median age of 42.2 years (range 16–88) and a mean follow-up of 37.4 months. The overall rate of RTS was 217/269 (80.7%), with 43/59 (72.9%) returning to the same level. In overhead athletes, the overall rate of return to play was 39/49 (79.6%). Among military personnel, the overall rate of return to duty was 61/74 (82.4%). The average time to RTS was 5.4 (range 3–11) months. 10 (58.8%) Studies reported a recommended time window within which patients were allowed to return to full activity. Specific criteria for return to play were not reported in any of the identified studies. Conclusion: While overall rate of return to athletic activity was reportedly high following biceps tenodesis, one in four patients were not able to resume athletic activity at the same level. At present, there is no objective assessment of when patients can return to full activity reported in the literature. Level of evidence: IV. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of the present study was to assess the kinematical behavior of a multi-radius posterior-stabilized (PS) mobile-bearing (MB) total knee arthroplasty (TKA) during an activity of daily living (Sit-To-Stand—STS) and a high demanding motor task (Deep-Knee-Lunge—DKL) using model-based dynamic RSA. We hypothesized the achievement of medial pivoting movement in both motor tasks due to the congruent geometry of the inlay with the femoral component, which should allow good stability of the medial compartment, and to the high magnitude of rotations guaranteed by the MB on the tibial side. Methods: Twenty-two randomly selected patients were recruited and prospectively evaluated. The PS MB cemented TKA was implanted with the standard technique (medial parapatellar approach, adjusted mechanical alignment). At minimum 9-month follow-up, patients were examined with model based Dynamic RSA developed in our Institute (BI-STAND DRX 2) during the execution of two motor tasks: STS and DKL. The motion parameters were evaluated using the Grood and Suntay decomposition and the low-point kinematics methods. Results: In the extension phase of DKL femur performed a greater antero posterior translation of 3.8 mm compared to STS between 0° and 20° of knee flexion (p < 0.05). Low-point analysis showed a medial pivoting movement in both motor tasks: in 62% of patients during STS and 48% during DKL. Varus-valgus rotations were lower than 1° during all the range-of-motion in both motor tasks without differences. Conclusions: Medial pivot was partially produced by this multi-radius PS MB TKA with some differences during activity of daily living (STS) and high demanding motor task (DKL). Level of evidence: IV. [ABSTRACT FROM AUTHOR]

Purpose: Accurate assessment of the locations of patellar avulsion fractures in acute patellar dislocations is clinically relevant for decision making for treatment. The study aim was to classify the locations of patellar avulsion fractures with a focus on the ligament attachments of medial stabilizing structures. Methods: Out of 131 first-time acute traumatic patellar dislocations, 61 patients had patellar fractures. Subsequently, 10 patients with isolated osteochondral fractures of the articular surface in the patella were excluded. Finally, 51 patients (34 females and 17 males, average age: 18.5 years, 95% CI 16.1–20.9) were included in the study cohort. Based on the locations of the patellar attachment, the patients were divided into three groups: the superior group [medial patellofemoral ligament (MPFL) attachment], inferior group [medial patellotibial ligament (MPTL)/medial patellomeniscal ligament (MPML) attachment], and mixed group. Results: In the patellar avulsion group (51 patients), the superior group, mixed group, and inferior group contained 8/51 (16%), 12/51 (24%), and 31/51 (61%) patients, respectively. Conclusions: This study showed that 84% of the patellar avulsion fractures were located in the inferomedial patellar border, which consisted of MPTL/MPML attachments that were clearly different from the true "MPFL" attachment at the superomedial patellar border. In terms of the clinical relevance, the acute surgical repair of MPTL/MPML attachments in the inferomedial patellar border may not sufficiently control the patella if optimal management of the MPFL is not performed. Level of evidence: IV. [ABSTRACT FROM AUTHOR]

Purpose: It remains unclear if morphologic patterns of the patella itself predispose to patellar instability. This study examined established patellar landmarks in relation to the femoral condyle width to clarify differences of patellar morphologies in patellofemoral stable and unstable patients.Methods: Magnetic Resonance Imaging of 50 subjects (20.7 ± 4.4 years; 17 males, 33 females) with patellofemoral instability (study group, SG) and 50 subjects (25.3 ± 5.8 years; 31 males, 19 females) with anterior cruciate ligament rupture (control group, CG) were analyzed. Corresponding patellar value indices (PW-I; LPF-I 1; LPF-I 2) in relation to the femoral condyle width (FCW) were evaluated after the measurement of absolute patellar dimension [patellar width (PW); direct length of the lateral patellar facet (LPF-1); projected length of the lateral patellar facet (LPF-2)]. The patellar shape according to Wiberg, trochlear dysplasia, patellar height, and tibial tubercle-trochlear groove (TT-TG) distance were determined.Results: The SG showed a significantly longer absolute (LPF 2) (P = 0.041) and relative (LPF-I 1, LPF-I 2) (P < 0.001) lateral facet of the patella. No significant differences were evaluable for the relative patellar width (PW-I) (ns). A patellar shape type 3 (P = 0.001) as well as a higher position of the patella and TT-TG-distance (P < 0.001) were significantly more often present in the SG.Conclusion: There are several bony alterations associated with patellofemoral instability, but our data did not show a significantly smaller lateral patellar facet or relative patellar width that could facilitate a patellar dislocation. This helps surgeons, that are considering to surgically address the patella in cases of patellofemoral instability, to better understand its morphologic pattern.Level Of Evidence: III. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study was to evaluate and compare the clinical outcomes of two different fixation techniques for anatomic medial patellofemoral ligament (MPFL) reconstruction.Methods: A retrospective study was undertaken between 2012 and 2018 of 60 cases of patellar dislocation who underwent surgical reconstruction between 2007 and 2010: 30 patients were treated with modified semi-tunnel bone bridge fixation (group A) and 30 patients with suture anchor fixation (group B). All patients had computed tomography scans available to review the patellar tilt angle and lateral patellar angle (LPA). In addition, a physical examination was performed, and the patellar apprehension sign and patellar stability were evaluated. Knee function was also evaluated using the Kujala score and Lysholm score.Results: At a minimum 5-year follow-up, the patellar tilt angle and LPA were restored to the normal range, and a significant difference was observed between the groups. There was a significant improvement in knee function in the Kujala and Lysholm scores after surgery in both groups. At the final follow-up, the mean Kujala and Lysholm scores in groups A and B were significantly different.Conclusion: Both the semi-tunnel bone bridge and suture anchor fixation for double-bundle anatomic reconstruction of the MPFL can effectively restore patellar stability and improve knee function. The semi-tunnel bone bridge technique achieved statistically better knee function than the suture anchor technique at a minimum 5-year follow-up.Level Of Evidence: III. [ABSTRACT FROM AUTHOR]

Purpose: To compare suture tape-augmented MPFL repair with allograft MPFL reconstruction using patellofemoral contact pressure and joint kinematics to assess the risk of patellofemoral over-constrainment at point zero.Methods: A total of ten fresh frozen cadaveric knee specimens were tested in four different conditions of the MPFL: (1) native, (2) cut, (3) reconstructed with tendon graft, and (4) augmented with suture tape. The patellofemoral mean pressure (MP), peak pressure (PP) and contact area (CA) were measured independently for the medial and lateral compartments using pressure-sensitive films. Patellar tilt (PT) and shift (PS) were measured using an optical 3D motion tracking system. Measurements were recorded at 0°, 10°, 20°, 30°, 60° and 90° of flexion. Both the tendon graft and the internal brace were preloaded with 2 N, 5 N, and 10 N.Results: There was no significant differences found between surgical methods for medial MP, medial PP, medial CA, lateral MP and PS at any preload or flexion angle. Significant differences were seen for lateral PP at 20° knee flexion and 10 N preload (suture tape vs. reconstruction: 1045.9 ± 168.7 kPa vs. 1003.0 ± 151.9 kPa; p = 0.016), for lateral CA at 10° knee flexion and 10 N preload (101.4 ± 39.5 mm2 vs. 108.7 ± 36.6 mm2; p = 0.040), for PT at 10° knee flexion and 2 N preload (- 1.9 ± 2.5° vs. - 2.5 ± 2.3°; p = 0.033) and for PT at 0° knee flexion and 10 N preload (- 0.8 ± 2.5° vs. - 1.8 ± 3.1°; p = 0.040). A preload of 2 N on the suture tape was the closest in restoring the native joint kinematics.Conclusions: Suture tape augmentation of the MPFL resulted in similar primary contact pressures and joint kinematics in comparison with MPFL reconstruction using a tendon graft. A pretension of 2 N was found to restore the knee joint closest to normal patellofemoral kinematics. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the clinical outcome of the combined reconstruction of the medial patellofemoral ligament (MPFL) and medial patellotibial ligament (MPTL) for patellar instability with patella alta.Methods: A total of 108 patients underwent a combined reconstruction of the MPFL and MPTL, and 58 patients were included in this study. The clinical results were evaluated and compared using the International Knee Documentation Committee (IKDC) scores, Kujala scores, and visual analogue scale (VAS) scores. The tibial tuberosity-trochlear groove (TT-TG) distance, three indices of patellar height (Insall-Salvati ratio, modified Insall-Salvati ratio, and Caton-Deschamps index), and patellar shift and tilt were defined preoperatively and at the 12- and 24-month follow-up visits.Results: At the 12- and 24-month follow-up visits, 86.2% (50/58) and 87.9% (51/58) of the subjective outcomes were excellent, 5/58 (8.6%) and 4/58 (6.9%) were good, 1/58 (1.7%) and 2/58 (3.4%) were fair, and 2/58 (3.4%) and 1/58 (1.7%) were poor. There were significant improvements in the IKDC scores, from 51.9 ± 13.8 preoperatively to 80 ± 19.2 (P < 0.05) at 12 months and 85 ± 13.9 (P < 0.05) at 24 months; Kujala scores, from 55.1 ± 15.2 preoperatively to 82.6 ± 14.9 (P < 0.05) at 12 months and 89.5 ± 10.2 (P < 0.05) at 24 months; and VAS scores, from 58 ± 11 preoperatively to 12 ± 5 (P < 0.05) at 12 months and 11 ± 4 (P < 0.05) at 24 months. The patellar tilt, patellar shift, Insall-Salvati ratio, modified Insall-Salvati ratio, Caton-Deschamps index, and TT-TG distance all decreased significantly compared with the preoperative values, and there were no significant differences between the values at the 12- and 24-month follow-ups.Conclusion: The results of this study show that a combined reconstruction of the MPFL and MPTL is an effective treatment for patellar instability with patella alta. This article emphasizes the combined effect of MPFL and MPTL instead of MPFL alone and provides an effective option for the treatment of recurrent patellar dislocation with patella alta.Level Of Evidence: Case series, Level IV. [ABSTRACT FROM AUTHOR]

Purpose: The scientific literature concerning the anatomy of medial soft-tissue stabilizers of the patella is growing exponentially. Much of the surgical literature has focused on the role of the medial patellofemoral ligament (MPFL) and techniques to reconstruct it, yet our understanding of its anatomy has evolved during the past several years. Given this, we report on the current understanding of medial patellofemoral anatomy and implications for reconstruction.Methods: Current and historical studies of medial patellar anatomy were reviewed, which include the MPFL and medial quadriceps tendon femoral ligament (MQTFL), as well as that of the distal medial patellar restraints, the medial patellotibial ligament (MPTL) and medial patellomeniscal ligament (MPML). In addition to the reported findings, the authors' anatomic descriptions of each ligament during their dissections were identified and recorded.Results: Despite the name of the MPFL, which implies that the ligament courses between the femur and patella, recent studies have highlighted the proximal MPFL fibers that attach to the quadriceps tendon, known as the MQTFL. The MPFL and MQTFL have also been referred to as the medial patellofemoral complex, reflecting the variability in anatomical attachment sites. The MPFL accounts for only half of the total restraint to lateral patellar displacement, and the remaining contributions to patellar stability are derived from the combination of the MPTL and MPML, which function primarily in greater degrees of knee flexion.Conclusion: The understanding of the complexity of the medial patellar stabilizers continues to evolve. Although MPFL reconstruction is gaining wide acceptance as a procedure to treat patellar instability, it is important to recognize the complex and changing understanding of the anatomy of the medial soft-tissue stabilizers and the implications for reconstruction.Level Of Evidence: V. [ABSTRACT FROM AUTHOR]

Purpose: A medial patellofemoral ligament reconstruction (MPFL) with an additional derotational femoral osteotomy is suggested for patients suffering from patellar instability and an increased internal femoral torsion (IT). This biomechanical study investigated whether an isolated MPFL reconstruction could restore patellofemoral biomechanics for 10° and 20° relatively increased internal femoral torsion.Methods: Eight fresh-frozen cadaver knees were tested on a specially designed knee simulator, which bend the knee from 0° to 90° flexion. Patellar motion (tilt and shift) and patellofemoral pressure (pressure shift, mean and peak pressure) were evaluated for 0°, 10° and 20° of IT with a native and reconstructed MPFL.Results: An isolated MPFL reconstruction, compared to a native MPFL with the same femoral torsion showed a significant medial shift of the center of force (10° IT p < 0.001; 20° IT p = 0.02) and patella shift (10° and 20° IT p < 0.001) but no significant change in patella tilt (10° IT n.s.; 20° IT n.s.) for 10° and 20° IT. There was a significant medial shift in the center of force for 10° IT (10° IT p = 0.04) and a non-significant lateral shift for 20° IT (20° IT n.s.) in comparison to the native MPFL with 0° of femoral torsion. Patella shift was directed medially for 10° IT (10° IT p = 0.002). In knee flexion angles up to 30°, the patella remained more lateral for 20° IT and showed a different motion pattern (20° IT n.s.). Patella tilt showed a significant lateral tilt for 10° and 20° IT (10° IT p = 0.01; 20° IT p = 0.002).Conclusion: MPFL reconstruction as an isolated therapy only appears to be reasonable for 10° increased IT. While for an increased IT of 20°, a lateralizing force vector remains and an additional femoral derotational osteotomy is recommendable. These findings may assist surgeons in the decision making of surgical procedures in patients suffering from patella instability. [ABSTRACT FROM AUTHOR]

Purpose: Concomitant anterolateral ligament (ALL) injury is often observed in patients with an anterior cruciate ligament injury leading some to recommend concurrent ALL reconstruction. In ligament reconstruction, it is imperative to restore desirable ligament length changes to prevent stress on the graft. The purpose of this investigation is to identify the optimal femoral and tibial locations for fixation in ALL reconstruction.Methods: 3D computerized tomography (CT) knee models were obtained from six fresh-frozen, unpaired, cadaveric human knees at 0°, 10°, 20°, 30°, 40°, 90°, 110°, and 125°of knee flexion. Planar grids were projected onto the lateral knee. Isometry between each tibial and femoral grid point was calculated at each angle of flexion by the length change in reference to the length at 0° of knee flexion. The mean normalized length change over the range of motion was calculated for each combination of points at all angles of flexion were calculated.Results: Fixation of the ALL to the lateral femoral epicondyle or 5 mm anterior to the epicondyle with tibial fixation on the posteroinferior aspect of the tibial condyle (14-21 mm posterior to Gerdy's tubercle and 13-20 mm below the joint line) provided the lowest average length change for all possible ALL tibial insertion points. Minimal length change for all femoral fixation locations occurred from 20° to 40° of flexion, which identifies the angle of flexion where graft tensioning should occur intraoperatively.Conclusion: With the use of 3D reconstructed models of knee-CT scans, we observed that there was no ALL fixation point that was truly isometric throughout range of motion. Fixation of the anterolateral ligament on the lateral femoral epicondyle or anterior to the lateral femoral epicondyle and on the inferoposterior aspect of the tibial condyle restores isometry. Additionally, minimal length change was observed between 20° and 40° of flexion, which is the most appropriate range of knee flexion to tension the graft. Reproducing isometry reduces stress on the graft, which minimizes the risk of graft failure. [ABSTRACT FROM AUTHOR]

Purpose: The hypotheses were that medial patellofemoral ligament reconstruction (MPFLr) would improve the long-term symptoms of patellofemoral Instability (PFI) and control patellar tilt, based on computed tomography (CT), and that the addition of a TT transfer, when it is necessary, would not deteriorate the outcome. The purpose of this study was to evaluate the long-term clinical and radiographic outcomes of a large series of MPFLr, either isolated or associated with a TT transfer.Methods: From 133 MPFLr with a minimum of 4 years postoperatively, three groups were defined: isolated MPFLr, MPFLr with tibial tubercle (TT) medialisation or MPFLr with TT medialisation and distalisation. IKDC and Kujala scores were evaluated. Patellar tilt was evaluated on the patient's preoperative and the last available radiograph, and on CT scan measurements performed preoperatively and at 6-month postoperatively.Results: The mean follow-up was 6.3 ± 1.7 years [4.1-10.3] and four patients reported recurrent patellar dislocation. Between pre and postoperative at last follow-up a significant improvement in IKDC and Kujala functional scores was observed (P < 0.01), with no difference between the three groups. Regarding patellar tilt, there were significant decreases in Laurin and Merchant angles and an improvement of the Maldague stage (P < 0.01). The CT analysis of patellar tilt also demonstrates a significant improvement of the patella tilt (P < 0.01). The control of the patella tilt was correlated with a good functional result (P < 0.01).Conclusion: The MPFLr, whether isolated or associated with a TT transfer, provides good long-term clinical and radiological outcomes with a low rate of recurrence. The addition of a TT transfer, when necessary, results in the same good outcomes. This article provides a guide for surgeons evaluating PFI to choose the most appropriate procedure.Level Of Evidence: IV. [ABSTRACT FROM AUTHOR]

Purpose: To report outcomes after combined medial patellofemoral ligament (MPFL) and medial patellotibial ligament (MPTL) reconstruction and test associations between prognostic factors and clinical outcomes. It was hypothesised that combined MPFL and MPTL reconstruction would result in significant improvement in function, and that outcomes would be associated with age, sex, Beighton score, concomitant articular lesions, and preoperative function.Methods: All combined reconstructions of MPFL and MPTL were reviewed. Inclusion criterion was minimum 2-year follow-up. Exclusion criteria were age at surgery ≥ 35 years and concomitant osteotomies. Kujala, Tegner and Marx scores were completed prospectively. Patients were evaluated at a minimum 2-year follow-up. Associations between potential prognostic factors and Kujala and Tegner scores were tested using bivariate analyses followed by multivariate regression models.Results: Of 22 patients (26 knees), 19 (23 knees) met inclusion criteria, and 16 (20 knees) were available for follow-up. Mean age at surgery was 18 years (range 14.5-23). Mean follow-up was 43 months (range 24-73). Postoperative Kujala score significantly improved compared to before surgery (86.4 ± 12.5 vs. 54.9 ± 15.2, p < 0.01). Postoperative Tegner score was nonsignificantly higher compared to before surgery (4.8 ± 2.4 vs. 4 ± 3, p = ns) and lower compared to before first patella dislocation (4.8 ± 2.4 vs. 5.9 ± 1.2, p < 0.01). Postoperative Kujala score was associated with male sex (p = 0.02), with medial patellofemoral chondral lesions (p = 0.01) and with preoperative Kujala score (p = 0.05). Postoperative Tegner score was associated with male sex (p < 0.01), with preoperative Tegner level (p < 0.01), and with Beighton score (p < 0.01). Patella apprehension was recorded in two knees (10%) in two patients.Conclusion: Combined MPFL and MPTL reconstruction in young adults results in significant improvement in subjective knee function with minimal risks, although preinjury activity levels are not consistently restored. Associated factors of improved outcome include higher preoperative knee scores and activity levels, medial patellofemoral chondral lesions, decreased Beighton scores, and male sex. This supports the advisability of the procedure and can also assist in setting realistic goals for specific groups of patients.Level Of Evidence: Case series, Level IV. [ABSTRACT FROM AUTHOR]

Purpose: To examine the predictors of the second-time lateral patellar dislocation (LPD) in patients after acute first-time LPD in a 5-year follow-up.Methods: Data were collected prospectively from patients after acute first-time LPD with conservative treatment. Factors included sex, age at the first-time LPD, anatomical variants [trochlear dysplasia, patellar height, tibial tuberosity-trochlear groove (TT-TG) distance], and injury patterns of medial patellofemoral ligament (MPFL) in acute first-time LPD. Logistic regression was carried out to identify the independent risk factors for the incidence of the second-time LPD.Results: The incidence rate of a second-time LPD was 35.5% (59 of 166) in the 5-year follow-up. Univariate analysis revealed significant differences in the incidence rate of the second-time LPD among age at the first-time LPD (P = 0.04), trochlear dysplasia (P = 0.003), patella height (P = 0.017) and the TT-TG distance (P = 0.027). Risk factors for the second-time LPD were age < 18 years at the first-time LPD [odds ratio (OR) 4.088], low-grade trochlear dysplasia (OR 7.214), high-grade trochlear dysplasia (OR 18.945), patella alta (OR 8.416), elevated TT-TG distance (OR 12.742), complete MPFL tear at its isolated femoral-side (OR 6.04) and complete combined MPFL tear (OR 5.851).Conclusions: Trochlear dysplasia, elevated TT-TG distance, patella alta, age < 18 years at the first-time LPD, complete MPFL tear at its isolated femoral-side and complete combined MPFL tear in the first-time LPD are independently associated with a higher incidence rate of the second-time LPD.Level Of Evidence: III. [ABSTRACT FROM AUTHOR]

Purpose: To describe the unclarified characteristics of medial patellofemoral ligament and its relation to neighboring structures.Methods: Sixteen fresh-frozen human knees were dissected in using outside-in and inside-out combined technique. The patellar side attachment was observed from the inside view and femoral side from outside view.Results: The medial patellofemoral ligament was described a complex and multiconnected structure. The femoral side included the upper and lower portion, of which the upper portion attached on the femur with mean width 7.5 ± 1.1 mm and its superficial fibers extended to the adductor magnus tendon and the medial gastrocnemius tendon, and of which the lower portion appeared a right-triangle connected to the MCL without bony attachment. From inside view, the patellar attachment consisted of the bony and non-bony parts. The width of bony attachment was measured mean 16.3 ± 3.8 mm, and the non-bony attachment was found attached on the vastus intermedius tendon with mean width 21.7 ± 4.8 mm. The average thickness was 0.4 ± 0.1 mm and the length were inside assessed mean 67.9 ± 6.1 mm.Conclusion: The medial patellofemoral ligament which dissected a complicated structure with bony and non-bony attachment and multi-connected to neighboring structures on both patella and femur side appears as a polygon-shaped complex structure. [ABSTRACT FROM AUTHOR]

Purpose: Reconstruction of the medial patellofemoral ligament (MPFL) has been established as standard of care for patellofemoral instability. An anatomic femoral tunnel position has been shown to be a prerequisite for restoration of patellofemoral stability and biomechanics. However, the incidence of malpositioning of the femoral tunnel during MPFL reconstruction continues to be notable. Palpation of anatomic landmarks and intraoperative fluoroscopy are the two primary techniques for tunnel placement. The aim of this study was to compare the accuracy of these two methods for femoral tunnel placement.Methods: From 2016 to 2017, 64 consecutive patients undergoing MPFL reconstruction for patelllofemoral instability were prospectively enrolled. During surgery, the presumed femoral MPFL insertion was identified by both palpation of anatomic landmarks and using fluoroscopy, both of these points were separately documented on true lateral radiographs. They were then analysed and deviations from the Schoettle's Point were measured as anterior-posterior and proximal-distal deviations. A tunnel position within a radius of 7 mm around the Schoettle's Point was designated as an "accurate tunnel position".Results: Compared to the method of palpation, fluoroscopy led to significantly more anatomic femoral tunnel positoning (p < 0.0001). The mean proximal-distal and anterior-posterior distances between the femoral insertion site identified by palpation and the Schoettle's Point were 5.7 ± 4.5 mm (0.3-20.3 mm) and 4.1 ± 3.7 mm (0.1-20.3 mm), respectively, versus 1.7 ± 0.9 mm (0.1-3.6 mm) and 1.8 ± 1.3 mm (0.1-4.8 mm) for fluoroscopy, respectively. Using fluoroscopy, all femoral insertion sites were identified within a 7 mm radius around the centre of the Schoettle's Point. In contrast, only 52% (33) of femoral insertion sites identified by palpation were within this radius. These data were independent of patients' age, gender and BMI. No improvement in accuracy of femoral tunnel positions was detected over time.Conclusions: The main finding of this study was that, compared to the method of palpation of anatomic landmarks, the use of intraoperative fluoroscopy in MPFL reconstruction leads to more accurate femoral tunnel positioning. Based on these results, the use of intraoperative fluoroscopy has to be recommended for femoral tunnel placement in daily surgical practice to minimize the incidence of malpositioning and to restore native patellofemoral biomechanics.Study Design: Level III Case-control study. [ABSTRACT FROM AUTHOR]

Purpose: The medial patellotibial ligament (MPTL), the medial patellofemoral ligament (MPFL), and the medial patellomeniscal ligament (MPML) support the stability of the patellofemoral joint. The purpose of this systematic review was to report the surgical techniques and clinical outcomes of the repair or reconstruction of the MPTL in isolation or concomitant with the MPFL and/or other procedures.Methods: A systematic review of the literature was conducted. Inclusion criteria were articles in the English language that reported clinical outcomes of the reconstruction of the MPTL in isolation or in combination with the MPFL and/or other procedures. Included articles were then cross-referenced to find additional journal articles not found in the initial search. The methodological quality of the articles was determined using the Coleman Methodology Score.Results: Nineteen articles were included detailing the clinical outcomes of 403 knees. The surgical procedures described included hamstrings tenodesis with or without other major procedures, medial transfer of the medial patellar tendon with or without other major procedures and the reconstruction of the MPTL in association with the MPFL. Overall, good and excellent outcomes were achieved in > 75% of cohorts in most studies and redislocations were < 10%, with or without the association of the MPFL. An exception was one study that reported a high failure rate of 82%. Results were consistent across different techniques. The median CMS for the articles was 66 out of 100 (range 30-85).Conclusion: Across different techniques, the outcomes are good with low rates of recurrence, with one article reporting a high rate of recurrence. Quality of the articles is variable, from low to high. Randomized control trials are needed for a better understanding of the indications, surgical techniques, and clinical outcomes. This systematic review suggests that the reconstruction of the MPTL leads to favorable clinical outcomes and supports the role of the procedure as a valid surgical patellar stabilization procedure.Level Of Evidence: IV: systematic review of level I-IV studies. [ABSTRACT FROM AUTHOR]

Purpose: Graft tensioning during medial patellofemoral ligament (MPFL) reconstruction typically allows for lateral patellar translation within the trochlear groove. Computational simulation was performed to relate the allowed patellar translation to patellofemoral kinematics and contact pressures.Methods: Multibody dynamic simulation models were developed to represent nine knees with patellar instability. Dual limb squatting was simulated representing the pre-operative condition and simulated MPFL reconstruction. The graft was tensioned to allow 10, 5, and 0 mm of patellar lateral translation at 30° of knee flexion. The patellofemoral contact pressure distribution was quantified using discrete element analysis.Results: For the 5 and 10 mm conditions, patellar lateral shift decreased significantly at 0° and 20°. The 0 mm condition significantly decreased lateral shift for nearly all flexion angles. All graft conditions significantly decreased lateral tilt at 0°, with additional significant decreases for the 5 and 0 mm conditions. The 0 mm condition significantly increased the maximum medial pressure at multiple flexion angles, increasing by 57% at 30°, but did not alter the maximum lateral pressure.Conclusions: Allowing 5 to 10 mm of patellar lateral translation limits lateral maltracking, thereby decreasing the risk of post-operative recurrent instability. Allowing no patellar translation during graft tensioning reduces maltracking further, but can overconstrain the patella, increasing the pressure applied to medial patellar cartilage already fibrillated or eroded from an instability episode. [ABSTRACT FROM AUTHOR]

Purpose: This study quantified the error in anterior cruciate ligament (ACL) insertion site location and area estimated from three-dimensional (3D) isotropic magnetic resonance imaging (MRI) by comparing to native insertion sites determined via 3D laser scanning.Methods: Isotropic 3D DESS MRI was acquired from twelve fresh-frozen, ACL-intact cadaver knees. ACL insertion sites were manually outlined in each MRI slice, and the resulting contours combined to determine the 3D insertion site shape. Specimens were then disarticulated, and the boundaries of the ACL insertion sites were digitized using a high-accuracy laser scanner. MRI and laser scan insertion sites were co-registered to determine the percent overlapping area and difference in insertion centroid location.Results: Femoral ACL insertion site area averaged 112.7 ± 17.9 mm2 from MRI and 109.7 ± 10.9 mm2 from laser scan (p = 0.345). Tibial insertion area was 134.7 ± 22.9 mm2 from MRI and 135.2 ± 15.1 mm2 from laser scan (p = 0.881). Percentages of overlapping area between modalities were 82.2 ± 10.2% for femurs and 81.0 ± 9.0% for tibias. The root-mean-square differences for ACL insertion site centroids were 1.87 mm for femurs and 2.49 mm for tibias. The MRI-estimated ACL insertion site centroids were biased on average 0.6 ± 1.6 mm proximally and 0.3 ± 1.9 mm posteriorly for femurs, and 0.3 ± 1.1 mm laterally and 0.5 ± 1.5 mm anteriorly for tibias.Conclusion: Errors in ACL insertion site location and area estimated from 3D-MRI were determined via comparison with a high-accuracy 3D laser scanning. Results indicate that MRI can provide estimates of ACL insertion site area and centroid location with clinically applicable accuracy. MRI-based assessment can provide a reliable estimate of the native ACL anatomy, which can be helpful for surgical planning as well as assessment of graft tunnel placement. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this article is to review anatomical, biomechanical, and clinical data of the medial patellotibial ligament (MPTL) and medial patellomeniscal ligament (MPML), as well as studies focusing on the medial patellofemoral ligament (MPFL) but with relevant data about the MPTL and MPML.Methods: A literature search of articles specifically addressing the MPTL and/or MPML was included along with studies focusing on the MPFL but with relevant data about the MPTL and MPML.Results: The medial patellar ligaments responsible for maintaining the stability of the patellofemoral (PF) joint include the MPFL, the MPTL, and the MPML. The MPFL is considered the primary restraint to lateral patellar translation, while the latter two are considered secondary restraints. There is robust literature on the anatomical, imaging, and biomechanical characteristics of the MPFL, and also the clinical outcome of its injury and surgical reconstruction; much less is known about the MPTL and MPML. Isolated MPFL reconstruction has good clinical and functional outcomes, with a low failure rate when defined as frank re-dislocation. Complications, including continued episodes of patellar apprehension and subluxation, remain present in most series. In addition, the current literature primarily includes a homogeneous population with few excessive anatomic dysplastic factors. There is lack of knowledge on the role of MPTL and MPML in (potentially) aiding patella stabilization and improving clinical outcomes. Understanding the role of the medial-sided patellar ligaments, in particular the role of the secondary stabilizers, in PF function and injury will aid in this goal.Conclusion: MPTL and MPML have consistent basic science literature, as well as favorable clinical outcomes of surgical patellar stabilization with reconstruction of the MPTL. However, there is much heterogeneity among clinical case series and lack of comparative studies to allow clear indication for the role of isolated or combined surgical reconstruction in patellar stabilization. Therefore, this comprehensive review helps understand the current knowledge and the possible applications in the orthopedic clinical practice.Level Of Evidence: V. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the correlation between injury patterns of the medial patellofemoral ligament (MPFL) and vastus medialis obliquus (VMO) after acute first-time lateral patellar dislocation (LPD) in adults.Methods: Magnetic resonance imaging (MRI) was prospectively performed in 132 consecutive adults with acute first-time LPD. Images were acquired and evaluated using standardized protocols. Injury patterns of MPFL were grouped by location and severity for analysis of the prevalence of VMO injury.Results: MRI demonstrated VMO injury in 63 (47.7%) patients. Twenty (38.5%) and 43 cases (56.6%) were present in partial and complete MPFL tear subgroups, respectively. Compared with partial MPFL tears, complete tears showed a higher prevalence of VMO injury (P = 0.044). The mean coronal (28.5 mm) and mean sagittal VMO elevations (20.7 mm) were higher in the complete MPFL tear subgroup than in the partial tear subgroup (19.8 mm, P = 0.005; 11.9 mm, P < 0.001). No correlations were identified between the prevalence of VMO injury and location subgroups of MPFL injury (n.s.). Mean VMO elevations were higher in isolated femoral-side (FEM) and combined MPFL tear (COM) subgroups (mean coronal VMO elevation of 29 mm and mean sagittal VMO elevation of 20.8 mm in the FEM subgroup; mean coronal VMO elevation of 29.6 mm and mean sagittal VMO elevation of 23.1 mm in the COM subgroup) than in the isolated patellar-side MPFL tear (PAT) subgroup (P = 0.022, P < 0.001) (mean coronal VMO elevation of 20.7 mm and mean sagittal VMO elevation of 10.6 mm).Conclusions: Complete MPFL tear predisposes to VMO injury and has a higher elevation of torn VMO after acute first-time LPD in adults. Isolated femoral-side and combined MPFL tears predispose to higher elevation of torn VMO.Level Of Evidence: IV. [ABSTRACT FROM AUTHOR]

Purpose: Recently, ultra-congruent (UC) inserts have shown successful outcomes following total knee arthroplasty (TKA). It was hypothesized that patients in the UC group would not show significantly different in vivo stability or functional outcomes from those in the cruciate-retaining (CR) group.Methods: The prospective study enrolled patients who had been treated with either CR or UC TKAs (38 cases in each group), after a minimum 3-year follow-up. The same surgical technique was used with the same femoral components in both groups except for the polyethylene inserts (CR or UC). The clinical outcome measures were knee range of motion (ROM), Hospital for Special Surgery (HSS) score, Knee Society (KS) score, and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) subscale score. The mediolateral laxity at full extension and anteroposterior laxity at 90° flexion were measured in stress radiographs and compared between the two groups.Results: Both the CR and UC groups showed significant improvements in post-operative ROM, HSS, KS, and WOMAC scores without inter-group differences between two groups. Moreover, there were no differences in mediolateral or anteroposterior laxity between the two groups (p > 0.05).Conclusion: TKA with posterior cruciate ligament (PCL) resection using the UC design showed comparable functional outcomes with those of CR TKA and provided similar in vivo stability. Therefore, UC inserts can be a good option in TKA without bony box cut when the PCL is damaged during an operation.Level Of Evidence: II. [ABSTRACT FROM AUTHOR]

Purpose: Medial patellofemoral ligament (MPFL) reconstruction offers good clinical results with a very low rate of instability recurrence. However, its in vivo effect on patellar tracking is not clearly known. The aim of this study is to investigate the effects of MPFL reconstruction on patellar tracking using dynamic 320-detector-row CT.Methods: Ten patients with patellofemoral instability referred to isolated MPFL reconstruction surgery were selected and subjected to dynamic CT before and ≥6 months after surgery. Patellar tilt angles and shift distance were analysed using computer software specifically designed for this purpose. Kujala and Tegner scores were applied, and the radiation of the CTs was recorded. Two protocols for imaging acquisition were compared: a tube potential of 80 kV and 50 mA versus a tube potential of 120 kV and 100 mA, both with a slice thickness of 0.5 mm and an acquisition duration of 10 s.Results: There were no changes in patellar tracking after MPFL reconstruction. There was no instability relapse. Clinical scores improved from a mean of 51.9 (±15.6)-74.2 (±20.9) on the Kujala scale (p = 0.011) and from a median of 2 (range 0-4) to 4 (range 1-6) on the Tegner scale (p = 0.017). The imaging protocols produced a dose-length product (DLP) of 254 versus 1617 mGycm and a radiation effective estimated dose of 0.2 versus 1.3 mSv, respectively. Both protocols allowed the analysis of the studied parameters without loss of precision.Conclusions: Reconstruction of the MPFL produced no improvement in patellar tilt or shift in the population studied. The low-radiation protocol was equally effective in measuring changes in patellar tracking and is recommended. Although the procedure successfully stabilized the patella, knee surgeons should not expect patellar shift and tilt correction when performing isolated patellofemoral ligament reconstruction in patients with recurrent patellar instability.Level Of Evidence: IV. [ABSTRACT FROM AUTHOR]

Purpose: To describe the anatomy of the medial patellofemoral ligament (MPFL) and its relationship to the Adductor Magnus (AM) tendon as well as the behaviour exhibited in length changes during knee flexion.Methods: Ten cadaveric knees were dissected. The length from the superior and inferior patellar origin of the MPFL to its femoral insertion was measured at different degrees of knee flexion (0°, 30°, 60°, 90° and 120°). The same measures were made from both patellar origins of the MPFL up to the femoral insertion of the AM. The distance between the insertion of the AM and the Hunter canal was also measured.Results: In general, isometry up to 90° was seen in all measures of the MPFL and those of the AM. The most isometric behaviour was seen in 2 measures: the length of the AM femoral insertion up to the inferior origin of the MPFL on the patella and the length of the femoral insertion of the MPFL up to the inferior origin of the MPFL on the patella. Similar behaviour was seen regardless of the anatomical or quasi-anatomical femoral point of attachment (n.s.). The distance from the AM tendon to the Hunter canal had a mean value of 78.6 mm (SD 9.4 mm).Conclusion: The behaviour exhibited during the changes in the length of the anatomical femoral footprint of the MPFL and the AM is similar. Neurovascular structures were not seen at risk. This is relevant in the daily clinical practice since the AM tendon might be a suitable point of insertion for MPFL reconstruction. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study was to clarify the insertion sites on the patellar side of the medial patellofemoral ligament (MPFL).Methods: A total of 35 nonpaired human cadaveric knees were used in this study. After identification of the MPFL, the insertion sites on the patellar side of the MPFL were marked. Three-dimensional images were created, and the location and morphology of these insertion sites were analysed.Results: The morphology of the insertion sites on the patellar side of the MPFL was consistent. The proximal fibres of the MPFL were inserted to the deep fascia of the vastus medialis obliquus (VMO) and medial margin of the vastus intermedius (VI). The distal fibres of the MPFL were inserted to the medial margin of the patella directly. The insertion lengths of the VMO, VI, and patella were 26.7 ± 5.0, 28.5 ± 4.4, and 18.5 ± 4.4 mm, respectively. The rate of the vertical distance from the superior pole of the patella to the superior edge of the MPFL in relation to the total patellar height was 12 ± 4.4 %. At the distal edge, the rate was 58 ± 9.6 %.Conclusion: The insertion sites on the patellar side of the MPFL were consistent. The MPFL inserted into the VMO and VI was significantly longer than into the patella. The clinical relevance of this study is to improve understanding of the anatomy of the insertion sites on the patellar side of the MPFL and the pathophysiology of patellar dislocation. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the knee kinematics of the intact, MPFL-ruptured and MPFL-reconstructed knee and, moreover, to compare dynamic patellofemoral contact pressure of the gracilis tendon and the fascia lata as an alternative graft option for reconstruction of the MPFL.Methods: Eight paired human cadaveric knees were fixed in a custom-made fixation device. Patellofemoral contact pressure was assessed during a dynamic flexion movement at 15°-30°-45°-60°-75° and 90° using a pressure-sensitive film (Tekscan). The medial patellofemoral ligament was cut, and measurements were repeated. Finally, reconstruction of the MPFL was performed using the gracilis tendon (group I) or a fascia lata graft (group II). Tunnel localization was performed under fluoroscopic control. Grafts were fixed at 30° of flexion, and pressure measurements were repeated.Results: Incision of the medial patellofemoral ligament significantly reduced patellofemoral contact pressure at 15°, 30° and 45° of knee flexion compared to the intact knee (p < 0.05), whereas reconstruction of the MPFL using either gracilis tendon of the fascia lata was able to restore pressure distributions at 15° and 30° of knee flexion. However, in the hamstring group, reconstruction of the MPFL revealed a significantly reduced contact pressure at 45° of flexion (p = 0.038) compared to the intact knee. In the fascia lata group, a significant reduction in patellofemoral contact pressure was observed after MPFL reconstruction at 45°, 60°, 75° and 90° of knee flexion (p < 0.05).Conclusions: Anatomic reconstruction of the MPFL with either a gracilis or a fascia lata graft showed comparable patellofemoral pressure distributions which were closely restored compared to the native knee. Therefore, the fascia lata has shown to be a viable alternative to the gracilis tendon for reconstruction of the MPFL. However, anatomic reconstruction of the MPFL may lead to persistently altered patellofemoral contact pressure during knee flexion compared to the native knee independent of the tested graft. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of the current study was to investigate the potential effect of intraoperative fluoroscopy on the accuracy of femoral tunnel placement in anatomic ACL reconstruction, using an ideal anatomic point as reference and evaluating postoperative tunnel placement based on 3D CT.Methods: An experienced ACL surgeon, using the anatomic approach for femoral tunnel placement, relying on intraarticular landmarks and remnants of the torn ACL-and novel to the fluoroscopic assist-was introduced to its use. A prospective series of patients was included where group 1 (without fluoroscopy) and group 2 (with fluoroscopy) both had postoperative CT scans so that femoral tunnel position could be evaluated and compared to an ideal tunnel centre based on anatomic studies by using the Bernard and Hertel grid.Results: Group 2, where fluoroscopy was used, had a mean femoral tunnel that was closer to the ideal anatomic centre than group 1. In the Bernard and Hertel grid, the distance in the high-low axis (y-axis) was found significantly closer (P = 0.001), whilst the deep-shallow axis (x-axis) and a total absolute distance were not significantly closer to the ideal described anatomic centre.Conclusions: Intraoperative fluoroscopy was found effective as an aid for placing the femoral tunnel in a more accurate position, as compared to a desired anatomic centre. Although the concept of the "one-size-fits-all" approach for tunnel placement is debatable, the avoidance of grossly misplaced tunnels is the benefit of using fluoroscopy during ACL reconstruction. The authors hold that fluoroscopy is readily available, safe and easy to use and therefore a good aid in the anatomic approach for graft tunnel placement, for example, in a learning situation, in revision cases and when performing low volumes of such surgery.Level Of Evidence: III. [ABSTRACT FROM AUTHOR]

Purpose: To inventory the examination methods available to assess antero-medial rotational laxity (AMRL) of the knee following medial collateral ligament injury.Methods: Searches were conducted in accordance with the PRISMA guidelines and using four online databases: WEB OF SCIENCE, MEDLINE, EMBASE, and AMED. The Critical Appraisal Skills Programme guidelines for Diagnostic Test Studies were used for the quality assessment of the articles.Results: A total of 2241 articles were identified from the database searches. From this, four articles were included in the final review. All were case-control studies, considered a combined ACL/MCL injury and had small study populations. Specialised equipment was required in all studies, and one needed additional imaging support before measurements could be taken. Two employed commercially available measuring equipment as part of the assessment process.Conclusion: Clinical assessment of AMRL in relation to a MCL injury remains challenging. Although methods have been developed to support clinical examination, they are limited by a number of factors, including the need for additional time in the clinical environment when setting up equipment, the need for specific equipment to produce and measure rotational movement and imaging support. In addition, there are patient safety concerns from the repeated imaging. A reliable and valid clinical examination remains to be found to truly assess antero-medial rotational laxity of the knee.Level Of Evidence: IV. [ABSTRACT FROM AUTHOR]

Purpose: The present review aims to analyse the available literature regarding the use of navigation systems in ACL reconstructive surgery underling the evolution during the years.Methods: A research of indexed scientific papers was performed on PubMed and Cochrane Library database. The research was performed in December 2015 with no publication year restriction. Only English-written papers and related to the terms ACL, NAVIGATION, CAOS and CAS were considered. Two reviewers independently selected only those manuscripts that presented at least the application of navigation system for ACL reconstructive surgery.Results: One hundred and forty-six of 394 articles were finally selected. In this analysis, it was possible to review the main uses of navigation system in ACL surgery including tunnel positioning for primary and revision surgery and kinematic assessment of knee laxity before and after different surgical procedures. In the early years, until 2006, navigation system was mainly used to improve tunnel positioning, but since the last decade, this tool has been principally used for kinematics evaluation. Increased accuracy of tunnel placement was observed using navigation surgery, especially, regarding femoral, 42 of 146 articles used navigation to guide tunnel positioning. During the following years, 82 of 146 articles have used navigation system to evaluate intraoperative knee kinematic. In particular, the importance of controlling rotatory laxity to achieve better surgical outcomes has been underlined.Conlusions: Several applications have been described and despite the contribution of navigation systems, its potential uses and theoretical advantages, there are still controversies about its clinical benefit. The present papers summarize the most relevant studies that have used navigation system in ACL reconstruction. In particular, the analysis identified four main applications of the navigation systems during ACL reconstructive surgery have been identified: (1) technical assistance for tunnel placement; (2) improvement in knowledge of the kinematic behaviour of ACL and other structures; (3) comparison of effectiveness of different surgical techniques in controlling laxities; (4) navigation system performance to improve the outcomes of ACL reconstruction and cost-effectiveness.Level Of Evidence: IV. [ABSTRACT FROM AUTHOR]

Purpose: The purpose was to measure the effect of flexion and additional rotation of the femur relative to the tibia on the tuberosity-trochlear groove distance (TT-TG) in the same subject in 20 cadaveric knees joint.Methods: In 20 human adult cadavers, formal fixed knees (age: 81.9 years, SD 12.3; 10 female) CT scans were performed in extension and 30° of flexion as well as in neutral, maximal possible internal (IR), and external rotation (ER). On superimposed CT scan images, TT-TG was measured in each position. TT-TG measurements were correlated in all knee positions.Results: TT-TG in full extension/neutral rotation was 7.8 mm (SD 3.4, range, 2.4-15.3). TT-TG in full extension and IR was significantly lower, and TT-TG in full extension and ER was significantly higher than in neutral rotation (5.4 ± 2.3 vs. 10.9 ± 4.8 mm; P < 0.001). IR and ER varied between 1.0°-7.6° and 0.2°-9.2°, respectively. TT-TG in 30° flexion/neutral rotation was 3.9 mm (SD 1.8, range, 1.3-7.8), which was significantly lower than in full extension and neutral rotation (P < 0.001). TT-TG in 30° flexion and IR was significantly lower, and TT-TG in 30° flexion and ER was significantly higher than values obtained in neutral rotation (2.7 ± 1.2 vs. 6.5 ± 3.4 mm; P < 0.001). IR and ER in 30° flexion varied between 0.6°-10.7° and 1.9°-13.0°, respectively.Conclusion: Flexion as well as rotation of the knee joint significantly alters the TT-TG. These results may have wider clinical relevance in assessing TT-TG and further decisions based on it. [ABSTRACT FROM AUTHOR]

Gait pattern alterations were previously reported in association with objective patellar instability (OPI). Gait pattern comparison between a series of patients having undergone medial patellofemoral ligament (MPFL) reconstruction and a sample of control subjects. Thirty patients at 6 months postoperatively after MPFL reconstruction and thirty control subjects were enrolled in the study for a clinical and biomechanical assessment including gait analysis at three selected walking rates using the GAITRite(®) system. The mean raw IKDC score was 73 (± 19), and the mean Kujala knee function was 84 (± 17.5). The study of gait did not demonstrate any significant difference between the two groups at a normal and fast walking rate. At a 10 km/h running speed, the single-support phase was significantly shortened by a mean 2.33% (p < 0.05), the swing phase by a mean 2.64% (p < 0.05) and the double-support phase by a mean 3.49% (p < 0.05) on the operated side. MPFL reconstruction reported good midterm functional and clinical results in the management of OPI. At 6 months postoperatively, the patient gait pattern was similar to that observed in healthy subjects at a normal and fast walking speed. However, our study revealed persistent gait abnormalities at a 10 km/h running speed. These gait alterations seemed to be related to the ligament reconstruction in itself due to the higher strain applied on the reconstructed MPFL during running cycle (10 km/h). Level of evidence IV. [ABSTRACT FROM AUTHOR]

An introduction to articles published within the issue related to anterior coruscate ligament (ACL) is presented including a study on joint kinematics during a vertical-hop test in patients more than 20 years after ACL rupture and a study which evaluated patients 16 months after ACL reconstruction.

Purpose: To investigate the effect of different loads of knee extensor open kinetic chain resistance training on anterior knee laxity and function in the ACL-injured (ACLI) knee.Methods: Fifty-eight ACLI subjects were randomised to one of three (12-week duration) training groups. The STAND group trained according to a standardised rehabilitation protocol. Subjects in the LOW and HIGH group trained as did the STAND group but with the addition of seated knee extensor open kinetic chain resistance training at loads of 2 sets of 20 repetition maximum (RM) and 20 sets of 2RM, respectively. Anterior knee laxity and measurements of physical and subjective function were performed at baseline, 6 and 12 weeks. Thirty-six subjects were tested at both baseline and 12 weeks (STAND n = 13, LOW n = 11, HIGH n = 12).Results: The LOW group demonstrated a reduction in 133 N anterior knee laxity between baseline and 12 weeks testing when compared to the HIGH and the STAND groups (p = 0.009). Specifically, the trained-untrained knee laxity decreased an average of approximately 5 mm in the LOW group while remaining the same in the other two groups.Conclusion: Twelve weeks of knee extensor open kinetic chain resistance training at loads of 2 sets of 20RM led to a reduction in anterior knee laxity in the ACLI knee. This reduction in laxity does not appear to offer any significant short-term functional advantages when compared to a standard rehabilitation protocol. These results indicate that knee laxity can be decreased with resistance training of the thigh muscles.Level Of Evidence: Randomised controlled trial, Level II. [ABSTRACT FROM AUTHOR]

Purpose: Intraoperative fluoroscopy has been proposed as a feasible method to improve the accuracy of anatomical tunnel positioning. However, it has so far not been determined, whether this technique reduces the variability of tunnel positioning in a clinical set-up. Therefore, the purpose of this study was to determine the variability of tunnel positions applying intraoperative fluoroscopy. Methods: Femoral and tibial tunnel positions of 112 fluoroscopic ACL reconstruction cases were determined according to validated radiological measurement methods. Mean positions, standard deviations and ranges were calculated to determine the variability of the tunnel positions. Subgroup variability analysis was performed to analyse cases in which tunnel positions were corrected. Results: Applying intraoperative fluoroscopy, the variability of tunnel positions was found to be 3 % at the femur (range 15.4 %) and 2.3 % at the tibia (9.7 %). In 34 cases (30.0 %), non-satisfactory tunnel positions were identified and could be corrected achieving more accurate positions regarding to radiological parameters (14× femur, 16× tibia, 4× femur and tibia). Conclusions: The results of the presented study indicate that intraoperative fluoroscopy allows to identify non-accurate tunnel positions regarding to radiological criteria. The determined low variability indicates that fluoroscopic-based ACL reconstruction can be recommended as a feasible, easy and effective adjunct that enables surgeons to create more consistent and reliable tunnel positions in ACL reconstruction. Level of evidence: IV. [ABSTRACT FROM AUTHOR]

Purpose: It is hypothesized that mobile polyethylene bearings in total knee arthroplasty (TKA) may confer benefits with regard to range of motion and have improved clinical outcome scores in comparison with an arthroplasty with a fixed-bearing design. Our study compares clinical outcomes between patients who undergo TKA with either a rotating platform or fixed bearing using a posterior cruciate-retaining design. Methods: Three hundred and thirty-one patients were randomized to receive either a rotating-platform (161 patients) or a fixed-bearing (170 patients) implant. All patients were assessed pre-operatively and at 1 and 2 years post-operatively using standard tools (range of movement, Oxford Knee Score, American Knee Society Score, SF12 and Patella Score). Results: There was no difference in pre- to 2-year post-operative outcomes between the groups with regard to improvement in range of motion (10° ± 16 vs. 9° ± 15), improvement in Oxford Knee Score (−17.6 ± 9.9 vs. −19.1 ± 8.4), improvement in American Knee Society Score (49.5 ± 24.7 vs. 50.7 ± 21.0), function (23.6 ± 19.6 vs. 25.0 ± 22.5) and pain (34.9 ± 16.2 vs. 35.8 ± 14.1) subscores, improvement in SF12 Score (10.0 ± 16.3 vs. 12.3 ± 15.8) or improvement in Patella Score (9.7 ± 7.4 vs. 10.6 ± 7.1). Conclusion: No difference was demonstrated in clinical outcome between patients with a rotating-platform and fixed-bearing posterior cruciate-retaining TKA at 2-year follow-up. Level of evidence: I. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study was to identify the femoral insertion of the medial patellofemoral ligament (MPFL) and related osseous landmarks. Methods: A total of 31 unpaired human cadaveric knees were studied. The MPFL was identified, and the site of its femoral insertion was marked. Three-dimensional images were created, and the location and morphology of the femoral insertion of the MPFL and related osseous structures were analyzed. Results: The MPFL was identified in all knees. The femoral insertion of the MPFL was elliptical in shape, and the mean surface area was 56.5 ± 16.9 mm. The characteristic features of the femoral insertion of the MPFL could not be identified, but the adductor tubercle was clearly identified in all knees. The centre of the femoral insertion of the MPFL was 10.6 ± 2.5 mm distal to the apex of the adductor tubercle on the long axis of the femur, and the position of the insertion site was consistent in all knees. Conclusion: The adductor tubercle was clearly identified as an osseous landmark. The femoral insertion of the MPFL was approximately 10 mm distal to the adductor tubercle. These findings may improve understanding of the anatomy of the femoral insertion of the MPFL and may assist surgeons in performing anatomical reconstruction. [ABSTRACT FROM AUTHOR]

The present paper describes a new minimally invasive anatomic medial patellofemoral ligament reconstruction, using a fascia lata allograft as graft source and arthroscopy to obtain balanced fixation throughout the range of motion. [ABSTRACT FROM AUTHOR]