Congenital Synostosis of the Knee: Long-term Outcomes of Limb Reconstruction Surgery

Background:Congenital synostosis of the knee is a rare condition with limited data on treatment options and outcomes. This study reports clinical findings, treatment approach, and surgical/clinical outcomes for congenital synostosis of the knee. Methods:An institutional review board-approved retrospective review of patients with congenital synostosis of the knee presenting to 2 institutions between 1997 and 2021 was performed. Results:Eight patients (13 knees) with a median follow-up of 11.3 years (3.3 to 17 y) were included. Seven patients had associated syndromes. Patients presented with an average knee flexion deformity of 100 degrees (range 60 to 130 degrees) and delayed walking ability. Seven patients had associated upper extremity hypoplasia/phocomelia. The average age at the index surgery was 4.3 years (range 1.2 to 9.2 y). Synostosis resection with gradual deformity correction was performed in most patients. An attempt was made at a mobile knee in some patients, but all went on to knee fusion. Mean flexion deformity at final follow-up was 11.6 degrees (range: 0 to 40 degrees) and 5 limbs were fused in full extension. Mean limb length discrepancy at final follow-up was 6.8 cm (range: 0 to 8 cm). All patients maintained their improved ambulation status at final follow-up. Twenty-two complications were identified. Conclusions:Reliable correction of the deformity associated with congenital knee synostosis was achieved at a median follow-up of 11 years. Importantly, all patients maintained their improved ambulation at final follow-up. This is the largest study on patients with congenital knee synostosis and outlines a reconstructive approach to improve ambulatory status.