Quasi-stiffness of the knee joint is influenced by walking on a destabilising terrain.

BACKGROUND: Predictive models have been devised to estimate the necessary quasi-stiffness that a transfemoral prosthesis should be set to aligning the body and gait parameters of the user. Current recommendations exist only for walking over level ground. This study aimed to ascertain whether walking across destabilising terrain influences the quasi-stiffness of the knee joint thus influencing prosthetic engineering. METHODS: Ten healthy males (age: 25.1 ± 2.5 years; mean ± sd, height: 1.78 ± 0.05 m, weight: 84.40 ± 11.02 kg) performed 14 gait trials. Seven trials were conducted over even ground and seven over 20 mm ballast. Three-dimensional motion capture and ground reaction force were collected. Paired samples t-tests and Wilcoxon signed ranked test compared variables including; quasi-stiffness, gait speed, stride length and stride width. RESULTS: Quasi-stiffness (d = 0.562, P = 0.001) and stride width (d = 0.909, P < 0.001) were significantly greater in the destabilising terrain condition. Gait speed (r = -0.731, P = 0.001) was significantly greater in the control condition. No significant difference was seen in stride length (d = 0.583, P = 0.016). CONCLUSIONS: An increase in quasi-stiffness when walking across destabilising terrain was attributed to a magnified shock absorption mechanism, facilitating an increased flexion angle during the stance phase. This causes a lower centre of mass resulting in the musculoskeletal system having to produce a greater knee extensor moment to prevent the knee collapsing. Therefore, transfemoral prostheses should be tuned to apply increased extension moments if ambulation is to occur on a destabilising terrain.

Correction to: Paediatric proximal ACL tears managed with direct ACL repair is safe, effective and has excellent short-term outcomes.

Authors would like to update the full author names.

Paediatric proximal ACL tears managed with direct ACL repair is safe, effective and has excellent short-term outcomes.

PURPOSE: Anterior cruciate ligament (ACL) surgery in the paediatric population has long been a challenge. Non-operative treatment will result in persistent instability which can lead to chondral and meniscal injuries. The results of primary open ACL repair are poor. Concerns of growth plate disturbance with transphyseal techniques and issues with relatively small-diameter grafts in Tanner 1 and 2 patients, which are inadequate, have contributed to these challenges. With advancing instrumentation, there is renewed interest in ACL repair. The minimally invasive approach of arthroscopic primary ACL repair retains the native ligament. The objective and subjective outcomes at 2 years are presented. METHODS: Paediatric patients, less than 16 years of age, presenting acutely with complete proximal ACL ruptures underwent direct arthroscopic ACL repair, reinforced by a temporary internal brace, which was subsequently removed after 3 months. Patient-reported outcome measures including the Lysholm, Tegner and KOOS scores were collected at 6 months, 1 year and 2 years post-operatively. RESULTS: Twenty patients (age 6-16) completed data at 2 years post-operatively. There were no failures, no complications and no growth disturbance out to 2 years. The 2-year postoperative outcomes; Lysholm 95 (90-100), Tegner 7 (6-10), KOOS-Child 96.5 (88.9-100) demonstrated statistically significant improvements following surgery (p < 0.001). Objective measurements with an accelerometer did not demonstrate any significant side-to-side difference. CONCLUSION: ACL repair for proximal ACL tears in the paediatric population demonstrates the potential for excellent outcomes at short-term follow-up. This presents an attractive alternative to ACL reconstruction when an adequate ACL remnant permits direct repair. Our results demonstrate that paediatric ACL repair is safe and effective.

Non-Identical Bilateral Rupture of the Extensor Mechanism of the Knee in a Patient with Hyperlipidemia: A Case Study.

INTRODUCTION: Rupture of the extensor mechanism is a relatively common injury, most frequently occurring as a result of patella fracture, while ruptures of the quadriceps tendon and patellar ligament are less common. Extensor mechanisms of healthy knees are able to tolerate large forces before rupturing; therefore, complete ruptures without significant trauma are due to minor injury to an already degenerate or attenuated tendon. Hyperlipidemia has been linked as a cause of tendon degeneration due to the systemic biological effect that it has on tenocytes. Non-identical bilateral ruptures are rare. To the best of our knowledge, this is the only case report of bilateral ruptures involving the quadriceps tendon of one knee and patellar ligament of the contralateral knee simultaneously. CASE REPORT: A 42-year-old man presented to our department with bilateral traumatic rupture of the extensor mechanism of the knee. He had no medical history, was not taking any regular medications, and had no significant family history but a 15-year history of anterior knee pain. Both of his legs gave way on landing from a jump. Radiographs demonstrated a knee effusion with normal patella height on the left and a knee effusion with an elevated patella on the right. A diagnosis of quadriceps tendon rupture on the left and patellar ligament rupture on the right was made. CONCLUSION: Hyperlipidemia has been associated with ruptures of the Achilles tendon but has not been reported in association with failure of the extensor mechanism of the knee. We suggest that all patients presenting with bilateral tendon ruptures, especially in the absence of systemic disease or corticosteroid therapy, are investigated for hyperlipidemia and treated accordingly.