Abstract
PURPOSE: High tibial osteotomy (HTO) is widely performed for treating compartmental knee osteoarthritis with varus alignment. We evaluated the influence of constitutional alignment on clinical outcomes following opening-wedge HTO (OWHTO) and assessed individual target points in reference to constitutional alignment for improving postoperative results. METHODS: OWHTO procedures for varus knee osteoarthritis (n = 109) were retrospectively studied. The arithmetic hip-knee-ankle angle (aHKAA) predicting constitutional alignment, which differs from the conventional HKAA, was calculated as the difference between the medial proximal tibial and lateral distal femoral angles and assessed before and after the procedure. Post-aHKAA was defined as the difference between postoperative HKAA and aHKAA. Clinical outcomes were evaluated using the Knee Injury and Osteoarthritis Outcome Score (KOOS). International Cartilage Repair Society (ICRS) grades of the medial femoral condyle and medial tibial plateau were evaluated during the initial and second-look arthroscopies. RESULTS: The mean arithmetic and post-aHKAAs were -3.7 ± 2.8° and 4.7 ± 3.3°, respectively. Post-aHKAA was significantly correlated with the KOOS subscales of symptoms (r = 0.223, p = 0.012), pain (r = 0.196, p = 0.029), and activities of daily living (r = 0.213, p = 0.017). Logistic regression analysis revealed that post-aHKAA (p = 0.013, OR = 1.185) and body mass index (p = 0.013, B = -0.836) were significantly associated with improved medial tibial plateau and medial femoral condyle ICRS scores. Receiver operating characteristic analysis revealed that the cutoff value of post-aHKAA for improvement in medial tibial plateau ICRS score was 5.6° (area under the curve: 0.652; p = 0.004). CONCLUSIONS: Postoperative alignment should be considered constitutional. Individualized correction strategies based on aHKAA may enhance clinical outcomes and help optimize joint preservation in OWHTO.