TOTAL KNEE ARTHROPLASTY FOR IDIOPATHIC JUVENILE OSTEOARTHRITIS: 31 CASES

Abstract

Purpose: From 1985 to 2001, 31 total knee arthroplasties were performed for 17 adolescents or young adults with idiopathic juvenile osteoarthritis. The purpose of this work was to evaluate functional and radiological outcome.

Material and methods: Overall functional outcome was assessed with the Steinbrocker classification. Knee function was evaluated with the IKS score. Several types of prostheses were implanted: constrained GSB (n=14), cemented semi-constrained tri-CCC tri-compartment with a rotatory platform (n=10), non-cemented semi-constrained ROCC (n=1), LCS (n=2) including non-cemented, and FINN (n=2) (two custom-made rotation hinge prostheses implanted in the same patient). Fourteen prostheses involved bilateral implants, including three dual implantation procedures.

Results: Mean age at implantation was 20 years five months (14–29). There were fourteen girls and three boys. Eight had systemic idiopathic juvenile osteoarthritis and nine a polyarticular form. The Steinbrocker staging was: II (n=5,) III (n=6), IV or bedridden (n=4). Ten patients had two hip prostheses before bilateral knee arthroplasty. Mean follow-up was 4.5 years (1–12). Among the 31 operated knees, 16 were pain free, 14 minimally painful, and one painful due to loosening. The joint score was very good (n=18), good (n=4), and poor (n=5). Radiographically, normal alignment was found for 29 knees. Lucent lines were observed for 10 of the 14 GSB constrained prostheses. We did not observe any evidence of lucent lines for the non-cemented tri-compartment prostheses. Complications were: limited skin necrosis (n=1), bilateral supracondylar fracture one year after implantation (n=1).

Discussion: Outcome has been encouraging for total knee prostheses in patients with idiopathic juvenile osteoarthritis. These arthroplasties allow spectacular functional improvement. The few series reported have also reported very good results. Cemented tri-compartment semi-constrained implants appear to provide better stability at five years. Biologically sealed tri-compartment prostheses would be a very satisfactory solution due to the preservation of bone stock.