Post-traumatic knee osteoarthritis treated by osteotomy only.

BACKGROUND: Osteotomies to address lower extremity post-traumatic deformities are more complex than standard osteotomies performed for congenital deformities, standard osteotomies and their outcomes are not well known. We performed a multicentric retrospective study of these cases. We hypothesized that osteotomy without total knee replacement to correct fracture malunion deformities can provide long-term relief from athritic pain.

PATIENTS AND METHODS: Twenty-eight patients, mean age 46.4 years old, underwent, between 2000 and 2008, osteotomy for post traumatic osteoarthritis which had resulted in intraarticular malunion in six patients and extraarticular malunion in 22 cases. The initial trauma had occurred a mean 17.3 years before. There were 11 valgus and 17 varus deformities. Two osteotomies were performed in the callus to correct intraarticular malunion. The other osteotomies were performed outside the callus: in 25 cases to correct coronal plane deformities (nine tibial, 11 femoral and five tibial and femoral), including nine cases with associated derotation. Osteotomies were performed on the distal femoral metaphysis and the proximal tibia. There was also one case of supramalleolar derotation osteotomy of the tibia. All 28 patients were contacted again for a consultation. There was a postoperative clinical and radiographic follow-up of at least 2years for all patients despite four lost to follow-up patients. There were 18 patients with Ahlback grade 2 arthritis, nine grade 3 and one grade 4.

RESULTS: Two patients with an intraarticular malunion finally underwent revision surgery to receive total knee replacement because of persistent pain. These patients had grade 3 and 4 arthritis respectively and undercorrection persisted in the coronal plane. Four patients underwent repeated surgery for stiffness, early infection treated with debridement and antibiotics as well as femoral pseudarthrosis (two cases). After a mean follow-up of 3.8 years, the pain score had improved significantly with more marked improvement in extraarticular malunions (P=0.03). Functional improvement was moderate (equivalent in patients with Ahlback grades 2 and 3 arthritis) and articular range of motion did not change. Osteotomy corrected valgus and varus deformities with a mean realignment effect of 9° and 10° respectively.

DISCUSSION: Osteotomy should correct the three components of the traumatic deformity at the distal femoral metaphysic level to allow mechanical axis and rotation anomalies correction, and at the proximal tibia level for realignment purposes. Supramalleolar tibial osteotomy should be performed for tibial derotation. Pain relief with osteotomy had better outcomes when dealing with extraarticular malunions. In unicompartmental grade 2 and 3 arthritis, the indications can be fairly broad in young patients. Besides providing temporary relief, osteotomy facilitates future total knee replacement surgery in these cases.

LEVEL OF EVIDENCE: Level 4; non controlled, retrospective study.