Effect of Congenital Versus Acquired Varus on Patient-Reported Outcomes After High Tibial Osteotomy

ABSTRACT Objectives: 1) To determine the inter-rater reliability of tibial bone varus angle (TBVA) measurements. 2) To compare patient-reported outcomes after medial opening wedge high tibial osteotomy (HTO) in patients with congenital versus acquired varus. Methods: Two raters measured TBVA from preoperative whole-limb standing anteroposterior radiographs (n=74). Patients completed Knee Osteoarthritis Outcome Scores (KOOS) before and 5 years after surgery. The sample was first divided into two groups based on preoperative congenital (TBVA\u3e5°) or acquired (TBVA≤5°) varus, then three groups based on tertiles for TBVA. Results: Intraclass correlation coefficients (ICC) suggested excellent inter-rater reliability (ICC2,1=0.78; ICC2,2=0.88). Repeated measures analysis of variance suggested no significant difference in the increase in KOOS scores between groups. Although patients in the highest TBVA tertile had higher KOOS scores before and after surgery, increases were similar among groups. Conclusions: Improvements in patient-reported outcomes after medial opening wedge HTO are similar for patients with congenital and acquired varus. Key terms: tibial bone varus angle; tbva; knee; osteoarthritis; high tibial osteotomy; inter-rater reliability; patient reported outcome