Evaluation of unicondylar knee arthroplasty and fibulectomy from a biomechanical viewpoint / 医用生物力学

Varus deformation in knee joint is one of the common symptoms caused by unicompartment knee osteoarthritis. Currently, several operations can be used for correcting such deformation, including high tibial osteotomy, unicondylar knee arthroplasty (UKA) and fibulectomy. UKA has been developed for over 60 years, with the advantage of normal knee kinematics restored, less incision, more bony tissue preserved and larger range of motion than total knee arthroplasty (TKA). Therefore, UKA has become a reliable method for treating unicompartment knee osteoarthritis. Fibulectomy is a new kind of surgical technique for treating varus deformation in knee joint, with the advantage of simple operation, low cost and fast recovery. At present, fibulectomy has been widely applied, but its treatment mechanism is still not clear. In this review, two clinical operations UKA and fibulectomy were summarized, and the possible mechanism of fibulectomy for treating unicompartment knee osteoarthritis was proposed from the viewpoint of biomechanics. The author hypothesized that reduction in lateral muscle force after fibulectomy would cause rebalance of the resultant joint moment, therefore, the change of joint contact position and the decrease in joint contact force might be the cause of fibulectomy to release the pain for knee osteoarthritis patients.

Biomechanical comparisons between a new avascular necrosis of femaral head stem based on Chinese patients with avascular necrosis and two other designs / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>There is a relatively high failure rate of the femoral component in patients with avascular necrosis at the intermediate-term follow-up. Improving the geometrical fit of the femoral stem against the medullary canal may help to provide long-term survivorship of the hip replacement for patients with avascular necrosis.</p><p><b>METHODS</b>We designed a specific stem, based on morphometric studies of proximal femoral canals in Chinese avascular necrosis patients and evaluated the stem by finite element analyses, comparing the novel stem with two commercially available and commonly used stems.</p><p><b>RESULTS</b>The morphometric data from avascular necrosis patients showed specific geometric differences in the proximal femoral canal, including profile curves in both the sagittal and coronary planes than the patients with femoral neck fracture. The shorter stemmed prostheses (Fitmore(®) and our stem) performed better than the longer stemmed prosthesis (VerSys(®)).</p><p><b>CONCLUSIONS</b>This is the first study to investigate the femoral geometries of Chinese avascular necrosis patients. Our stem provides better stability and is theoretically beneficial to bone ingrowth, which may increase the long-term stability and fixation of the implant.</p>