Total knee arthroplasty following proximal tibial osteotomy: risk factors for failure.

BACKGROUND

The results of proximal tibial osteotomy are known to deteriorate over time, with the majority of patients eventually requiring total knee arthroplasty. The outcome of total knee arthroplasty in patients who have had a proximal tibial osteotomy, compared with that of routine primary total knee arthroplasty, remains controversial. The purpose of the present study was to evaluate the long-term clinical and radiographic outcome of total knee arthroplasty in patients who had undergone a previous proximal tibial osteotomy and to identify the risk factors that may result in an inferior outcome.

METHODS

Between 1980 and 1990, 166 cemented condylar total knee prostheses were implanted in 118 patients who had had a previous proximal tibial osteotomy for the treatment of osteoarthritis. The study group included seventy-seven men and forty-one women who had a mean age of 69.1 years at the time of knee arthroplasty. The average interval between the osteotomy and the total knee arthroplasty was 8.6 years. The average duration of clinical follow-up was 15.1 years, and the average duration of radiographic follow-up was 9.2 years.

RESULTS

The mean Knee Society pain score improved from 34.5 to 82.9 points, and the mean function score improved from 44.6 to 88.1 points. There was also a substantial improvement in the mean arc of motion. Thirteen knees (8%) were revised at a mean of 5.9 years. At the time of the final follow-up, progressive complete radiolucent lines indicating a loose prosthesis were present around seventeen tibial components and seven femoral components.

CONCLUSIONS

There was a very high rate of radiographic evidence of loosening. Male gender, increased weight, young age at the time of total knee arthroplasty, coronal laxity, and preoperative limb malalignment were identified as risk factors for early failure. Despite these findings, total knee arthroplasty can provide reliable and durable pain relief and improvement in function for patients who have had a previous proximal tibial osteotomy.

LEVEL OF EVIDENCE

Prognostic study. Level II-1 (retrospective study). See Instructions to Authors for a complete description of levels of evidence.