Surgical Biomechanics of the Patellofemoral Joint

This review presents objective data, as far as possible, about the current understanding of the biomechanics of the patellofemoral joint as it pertains to the management of patellofemoral problems. When faced with a patellofemoral malfunction, it is important to check all the soft-tissue and articular geometry factors relating to the patella locally and not to neglect the overall lower limb alignment and function. It is important to remember that small alterations in alignment can result in significant alterations in patellofemoral joint stresses and that changes in the mechanics of the patellofemoral joint can also result in changes in the tibiofemoral compartments. Surgical intervention for patellofemoral problems needs to be planned carefully and take into account an individual’s anatomy.     

Arthroscopic Chondral Cyst Excision in a Stiff Perthes’ Hip

Persistent hip stiffness in Perthes’ disease indicates a poor prognosis and is a therapeutic challenge. We report a case of a 13-year-old boy with a stiff Perthes’ hip that was nonresponsive to prolonged nonsurgical treatment. Imaging revealed Catterall group IV Perthes’ disease in an advanced reossification stage, with a focal defect in the weight-bearing area of the capital femoral epiphysis. A focal, compressible chondral elevation was detected on hip arthroscopy; on incision, flocculent fluid was released. After the cyst was excised, microfracture revascularization of the chondral defect was undertaken. Postoperatively, the patient had immediate pain relief, correction of deformity, and restoration of painless range of motion; this has continued for 4 years since surgery was performed. Persistence of an unhealed necrotic segment in Perthes’ disease has traditionally been associated with osteochondritis dissecans; however, in this case, the unhealed and nonossified segment produced an elevated painful chondral cyst that caused spasm and stiffness of the hip. Although 2 distinct types of chondral lesions have been described in Perthes’ disease, stiffness arising because of these lesions has not been reported. Patients with this unusual third type of chondral lesion of the capital femoral epiphysis, which causes persistent stiffness in Perthes’ hip, may be identified and successfully treated with the use of arthroscopic techniques.