Numerous studies have investigated kinematic alterations in patients with an isolated anterior cruciate ligament (ACL) injury. However, a substantial proportion of patients with injured ACLs also have concomitant meniscal tears. To evaluate the in vivo alteration of knee kinematics after an ACL tear, with or without a combined medial or lateral meniscal tear, during level walking activity. Controlled laboratory study. Fifty-six patients with unilateral ACL-deficient (ACLD) knees were studied. Among these patients, 15 had isolated ACL injuries (group 1), 15 had combined ACL and medial meniscal injuries (group 2), 15 had combined ACL and lateral meniscal injuries (group 3), and 11 had combined ACL and medial/lateral meniscal injuries (group 4). The kinematics of each knee was determined using an optical tracking system during treadmill gait. Range of motion (ROM) and kinematic alterations were compared between the contralateral ACL-intact (ACLI) and ACLD knees. All ACLD knees, with or without meniscal deficiency, had significantly less flexion than the ACLI knees (~3°-8°; P < .05). In groups 1, 3, and 4, the injured knees exhibited more femoral external rotation by approximately 1° to 2° (P < .05). Group 4 showed posterior femoral translation (anterior tibial translation) in the swing phase (~13 mm), while groups 2 and 3 showed increased anterior femoral translation (~2-3 mm). During medial-lateral translation, patients in group 2 had a more medial femoral shift (~4 mm) relative to the tibia initially, while those in group 4 exhibited a lateral femoral shift. The results indicate that meniscal injuries alter the kinematics of the ACLD knee when compared with knees with an isolated ACL injury. The location of the meniscal tear also affects knee kinematics. Considering the varying effects of meniscal injuries on knee joint kinematics, these data provide insight into the pathological function of the ACL-injured knee joint during walking.

Recurrent patellar dislocation is common clinically, primarily in adolescents. However, the biomechanical properties of single- and double-bundle medial patellofemoral ligament (MPFL) reconstruction remain poorly understood. Six fresh frozen adult cadaveric knee specimens were obtained for this study. Each specimen was fixed at 0° to test the force needed when the patella was laterally shifted 10 mm at a speed of 0.5 mm/s, and the test was repeated three times. This test was repeated when knee flexion was at 0°, 15°, 30°, 45°, 60°, and 90°. All six specimens were tested in four statuses, including MPFL intact, MPFL torn, single-bundle MPFL reconstruction, and double-bundle MPFL reconstruction. Similar force is required in these MPFL statuses at 0° of flexion, except for the MPFL torn group with a smaller force (45.5 ± 9.6 N, p < 0.05). The force required in the MPFL torn group reduced from 12.8 to 38.8% compared to other groups, at 0°, 15°, 30°, and 45° of flexion angles. At the flexion of 15°, the double-bundle reconstruction group required a statistically greater force (85.9 ± 10.1 N) compared to the single-bundle reconstruction group (74.0 ± 7.9 N). Interestingly, no statistical difference was found at flexions of 60° and 90° in these four groups. Both single-bundle and double-bundle MPFL reconstruction can restore the stability of the patella. The double-bundle reconstruction has an angular synergy effect that simulates the MPFL wide footprint in the patella, which enables it to have greater capacity to resist patellar dislocation before the patella entering the femoral trochlea at a smaller flexion angle.

Knee osteoarthritis (KOA) is reported to have characteristic kinematics during walking. However, the relationship between Kellgren-Lawrence (K/L) score and the 3D kinematic gait of patients with medial KOA remains unclear. Here, ninety-seven patients with medial KOA and thirty-eight asymptomatic participants were involved. Patients with medial KOA were divided into early, moderate, and severe KOA based on the K/L score. Through kinematic gait analysis, we found a relationship between K/L score and 3D kinematic gait for patients. All KOA knees had a significantly reduced range of motion. As the K/L score was increasing, the knee flexion at the heel strike and 50% of the stance phase increased while the peak knee flexion in the swing phase decreased. In addition, the adduction and femoral rotation increased internally at the heel strike, 50% of the stance phase, and maximum angle of the swing phase. Femoral translation increased anteriorly and distally at the heel strike and 50% of the stance phase. The severe group had more medial translation than the asymptomatic groups. Significant alterations of three-dimensional joint kinematics were identified in subjects suffering various severities in Chinese patients. This study provides an important reference for the treatment options, therapy assessment, and rehabilitation of KOA.

Objective: The purpose of this study was to evaluate the sensitivity and specificity of 3 tests for assessing anterior cruciate ligament (ACL) ruptures. Methods: MEDLINE, EMBASE, Cochrane Library, and CBM (Chinese Biomedical Literature Database) searches were performed. Studies selected for data extraction were those that addressed the accuracy of at least 1 physical diagnostic test for ACL rupture in comparison with a clinical reference standard such as arthroscopy, arthrotomy, or magnetic resonance imaging (MRI). The references of the included studies were also reviewed. Searches were limited to English and Chinese languages. Results: Sixteen studies that assessed the accuracy of the 3 tests for diagnosing ACL ruptures met the inclusion criteria. Study results were, however, heterogeneous. The Lachman test is the most sensitive test to determine ACL tears, showing a pooled sensitivity of 87.1% (95% confidence interval [CI] 0.84–0.90). The pivot shift test is the most specific test, showing a pooled specificity of 97.5% (95% CI 0.95–0.99); additionally, it has the highest positive likelihood ratios (LR+) of 16.00 (95% CI 7.34– 34.87). The Lachman test has the lowest negative likelihood ratios (LR-) of 0.17 (95% CI 0.11–0.25). Conclusion: In cases of suspected ACL injury, it is recommended to perform the pivot shift test, as it is highly specific and has greater likelihood and discrimination of accurately diagnosing ACL rupture. The Lachman test has great efficacy in ruling out a diagnosis of ACL rupture because of the lowest negative likelihood ratios.