Outcome of medial open wedge high tibial osteotomy and conversion knee arthroplasty in a local joint replacement centre

The primary purpose of this study is to evaluate the long-term survivorship of medial open wedge high tibial osteotomy. The secondary purpose is to review the clinical outcome and surgical challenges during conversion knee arthroplasty. The patients with medial open wedge high tibial osteotomy performed from 1995 to 2019 were reviewed. The survivorship, surgical particulars and clinical outcomes of the conversion arthroplasty were reviewed. There were 61 medial open wedge high tibial osteotomy performed from 1995 to 2019. The overall 10-year survival rate of medial open wedge high tibial osteotomy is 83.7%. In total, 22 medial open wedge high tibial osteotomy required conversion arthroplasty and none of them required revision in the study period. The patients who required conversion arthroplasty had higher mean posterior tibial slope than those who did not require it (14.5° vs 11.6°; p = 0.047). In total, 52.3% required quadriceps snip for exposure, 14.3% need a tibial stemmed component and 9.5% need a constrained total knee replacement. There was statistically significant improvement in Knee Society knee score, functional score, and range of motion after the conversion arthroplasty. The 10-year survival rate of medial open wedge high tibial osteotomy is satisfactory. The patients who required conversion arthroplasty had higher mean posterior tibial slope. In conversion cases, with careful pre-operative planning, most of them can be converted to conventional total knee replacement. The range of movement and functional scores significantly improved after conversion arthroplasty. Also, patellar baja or not does not predict the need for quadriceps snip during conversion arthroplasty.