Early development of patella infera after knee fractures.

The condition referred to as patella infera is characterized by a permanent shortening of the patellar ligament and is associated with a severely limited range of motion of the knee joint. Patella infera is a common complication of injury or surgery to the knee joint, and it is generally considered a condition that presents after a variable, albeit considerable time after injury. A review of the knee roentgenograms of patients with arthrofibrosis and patella infera showed this condition to be an immediate complication of knee fractures. Therefore, in order to better define the development of patella infera, the patellar height was studied during treatment of 146 knee joint fractures (46 supracondylar fractures, 50 patellar fractures and 50 tibial plateau fractures). Using the Caton-Deschamps method patella infera was detected in eight cases (17.39%) immediately after supracondylar fractures, in six cases (12%) after patellar fractures, and only in two cases (4%) after tibial plateau fractures. The patellar ratio remained unchanged or worsened further after treatment, and its incidence was unaffected by the type of treatment. These observations rule out etiologies such as inflammatory or algodystrophic phenomena and quadriceps inhibition, because the reduction of patellar height was evident immediately and persisted at follow-up examinations.