Loss of a condyle of the femur or tibia following septic arthritis in infancy: problems of management and testing of a hypothesis of pathogenesis

Purpose: The study was undertaken to: (1) describe the characteristic radiological features and problems of management of the loss of one condyle of the femur or tibia following septic arthritis of the knee in infancy and (2) test a hypothesis of the cause of the loss of a single condyle.

Methods: Radiographs of eight children with the loss of one condyle of the femur or the tibia following septic arthritis in infancy were reviewed. The course and outcome in two of these children who underwent reconstructive operations were studied. The knees of 35 stillborn foetuses were dissected to determine if the presence of synovial septae could account for the isolated loss of one condyle following infection.

Results: All eight cases showed characteristic features of loss of half the epiphysis, the underlying physis and part of the adjacent metaphysis; the other condyle was totally spared. The two children who underwent elaborate reconstructive procedures had poor outcomes at skeletal maturity, despite a series of additional operations. The foetal cadaveric study showed that complete infrapatellar synovial septae are present in some foetuses approaching 40 weeks of gestation.

Conclusions: The pattern of loss of a femoral or tibial condyle following septic arthritis is consistent with total preservation of the other condyle. The outcome of surgical reconstruction of the missing condyle is poor. The presence of a complete synovial septum could result in the localisation of infection to one half of the joint, with the destruction of one condyle.