Infrapatellar contracture syndrome. An unrecognized cause of knee stiffness with patella entrapment and patella infera.

Infrapatellar Contracture Syndrome (IPCS) is an infrequently recognized cause of posttraumatic knee morbidity. Unique to this group of patients is the combination of restricted knee extension and flexion associated with patella entrapment. IPCS can occur primarily as an exaggerated pathologic fibrous hyperplasia of the anterior soft tissues of the knee beyond that associated with normal healing. It can also occur secondarily to prolonged immobility and lack of extension associated with knee surgery, particularly intraarticular ACL reconstruction. IPCS follows a predictable natural history which is divided into three stages. Symptoms, diagnostic findings, and recommended treatment are determined by the stage at presentation. Once beyond its early presentation, IPCS is best treated by an anterior intraarticular and extraarticular capsular debridement and release, followed by extensive rehabilitation. The authors review 28 consecutive cases of IPCS. At followup 3 months to 4 years postoperation, the patients had averaged 2.3 additional surgical procedures following their index procedure or injury. The average increase in extension at followup was 12 degrees with the average increase flexion 35 degrees. Eighty percent of patients demonstrated signs and symptoms consistent with patellofemoral arthrosis; 16% of the patients demonstrated patella infera. The authors conclude that prevention or early detection and aggressive treatment are the only ways of avoiding complication in these problem cases.