The predictors of outcome in total knee arthroplasty for post-traumatic arthritis.

BACKGROUND: The outcomes of total knee arthroplasty (TKA) for post-traumatic arthritis are less reliable than for idiopathic osteoarthritis. These patients tend to be younger, present with varying degrees of deformity, and often have a history of prior surgery, resulting in a wide spectrum of pathology. We hypothesized that preoperative variables, in particular the location of deformity, would predict pain and functional outcomes.

METHODS: The outcomes of total knee arthroplasty for post-traumatic arthrosis were studied in 47 knees treated at our institution. All patients were administered the Knee Society Score (KSS) preoperatively and at follow-up (mean 52months, range 16 to 124). We classified the defects into four categories: intra-articular, metaphyseal, diaphyseal, and combined femoral and tibial deformities.

RESULTS: There was a significant improvement in KSS scores for pain (p<0.0001) and a trend toward higher function (p=0.06) comparing preoperative scores to final follow-up. The largest improvements in pain and functional scores were in patients with isolated articular deformities, while patients with combined tibial and femoral deformities did not have significant improvements in pain or function. Soft-tissue defects requiring flap coverage were associated with worsening in the pain score (p=0.027).

CONCLUSIONS: The location of post-traumatic deformity and compromise of the soft-tissue envelope influence the pain and functional outcomes of total knee arthroplasty for post-traumatic arthritis. Specifically, isolated articular deformities have the largest improvement in pain and function while patients with combined tibial and femoral deformities as well as patients with soft-tissue compromise experience poor outcomes.

LEVEL OF EVIDENCE: IV-Retrospective Case Series.