[Total knee arthroplasty in post-traumatic osteoarthritis]

This study aims to analyse the outcome and the complications after total knee arthroplasty in post-traumatic osteoarthritis in comparison to TKA in patients with degenerative osteoarthritis.

In a period of six years 43 patients with a post-traumatic osteoarthritis were treated with a total knee arthroplasty (group PT). 38 (88 %) patients (age median 55 years, 22 female, 16 male) were investigated clinically and radiologically after an average follow-up time of 2.7 years. The OKS (Oxford Knee Score, max. 48 points), the Knee Society Scores "function" (max. 100 points) and "knee" (max. 100 points) as well as the visual analogue scale (VAS, 0 to 10 points) were recorded preoperatively and at follow-up. For comparison we chose a matched-pair selection of patients with degenerative osteoarthritis and TKA (group DO, age median 63 years, 22 female, 16 male). For statistical analysis we used common parametric tests (Wilcoxon and U test) and a level of significance of 0.05.

In 19 patients (50 %) of the group PT the osteoarthritis was caused by a bone injury. Furthermore in 19 patients a meniscal and/or ligamentous injury led to osteoarthritis. Out of all patients of group PT, 10 patients showed a preoperative valgus malalignment higher than 10°. KSS knee and KSS function added up to 76.9 and 84.9 points. So they are significantly less than in the matched group (DO, knee: 86.1; function: 94.4). Similarly, the OKS is significantly less in group PT after follow-up (PT: 32.3; DO: 38.4, p ≤ 0.05) although the preoperative values are equal in both groups. The VAS value decreased significantly in both groups. Initial level of pain was significantly higher in the group DO compared to the group PT. Patients with osteoarthritis after trauma showed complications in 17 cases (^ = 44.7 %) that led to 28 revision operations (^ = 0.7 operations per knee). The group with valgus malalignment had a revision rate of 1.4 operations per knee. In the group DO 8 complications occurred (^ = 21,1 %) that led to 11 revision operations (^=0.3 per knee). The deviation from the "ideal" leg axis could be reduced from 3.8° varus to 1.7° varus in the group DO and from 1.3° valgus auf 1.2° valgus in the group PT. Patients with a preoperative valgus deviation > 10° were reduced from 13.6° (± 3.9°) valgus to 0.5° (± 9.2°) varus.

Patients after TKA because of post-traumatic osteoarthritis show worse results concerning function and condition compared to patients with degenerative osteoarthritis. Heterogeneous pathogenesis and high rates of revision operations underline the complexity of this group of patients. The treatment has to be adjusted to the patient's requirements as well to the pathoanatomy.