Outcomes of total knee arthroplasty following high tibial osteotomy

Total knee arthroplasty (TKA) following high tibial osteotomy (HTO) is a technically demanding procedure with varying results. The purpose of our study was to analyze the clinicoradiological results of TKA following HTO and to identify the factors that may influence the final outcome.

55 patients (58 knees) who had undergone a previous HTO were treated with a TKA from 1991 to 2009. There were 34 female and 21 male patients. The average age was 61.9 years (range 52-82 years) and the average weight was 79.5 kg (range 54-106 kg), with an average body mass index of 29.6 (range 21.8-34.6) at the time of TKA. The knee society scores (KSSs) and knee society functional scores were evaluated for every patient pre and postoperatively and the results evaluated.

The mean period of followup was 11.2 years (range 3-18 years) and the patients were followed up every year. The average KSS score at final followup improved from 38.5 (range 0-80 points) preoperatively to 88.5 postoperatively (range 35-95 points) (P < 0.05). The mean femorotibial angle corrected from 6.8 degrees (range 5-12°) varus preoperatively to a valgus of 4.4 (2-8°) degrees postoperatively. The average joint line height improved to an average of 9.6 mm (range 4.4-22 mm) (P < 0.01) at the last followup. The average Insall Salvatti Ratio also improved (average 1.11 preoperative - 1.21 average postoperative) (P < 0.05). The average range of motion improved to 108° (range 85°-125°) from 76° preoperative (range 55°-100°) (P < 0.01).

Although TKA postHTO is a demanding surgery however, with newer component designs, results are comparable to primary TKA. Technical difficulties in exposure can sometimes lead to component malpositioning, which can affect the final outcome. Inadequate soft tissue balancing and limb malalignment should always be kept in mind. Regular followup to look for evidences of loosening is advised in such patients].