RESUMEN
PURPOSE: Clinical studies regarding medial open-wedge high tibial osteotomy (MOWHTO) often analyse a large group of mechanical varus knees rather than differentiating for its primary varus-inducing component. This study aims to compare the radiological and clinical outcomes of the most prevalent varus malalignment phenotypes using the coronal plane alignment of the knee (CPAK) classification. METHODS: MOWHTO cases with minimal 2-year clinical follow-up were retrospectively selected from a knee osteotomy database (2016-2020). Based on the medial proximal tibial angle (MPTA) and lateral distal femoral angle (LDFA), subjects were allocated to the correct CPAK phenotype pre- and postoperatively. Clinical outcomes were the numeric rating scale (NRS), the knee injury and osteoarthritis outcome score (KOOS) and the therapeutic response rate (TRR) at 2-year follow-up. Inter-observer correlation coefficient (ICC) and unpaired student t test were performed for cross-phenotype comparison. RESULTS: One hundred thirty-five (135) subjects were found eligible (53.0 years old ±9.6 [19-77], 72% male, 53% left-sided). The most prevalent preoperative phenotype was CPAK 1 (n = 70 (52%)) and the postoperative phenotype was CPAK 6 (n = 66 (49%)). All CPAK phenotypes improved significantly relative to baseline but cross-phenotype comparison yielded no significant differences in clinical outcome. The TRR at 2 years was 67% for CPAK 1, 69% for CPAK 2 and 87% for CPAK 4. The TRR for CPAK 6 was 64% compared with 80% for CPAK 9, which was not significantly different. CONCLUSION: At 2-year follow-up, no clinically significant differences are observed between different CPAK phenotypes. Accurate MOWHTO corrections provide significant clinical improvement even in the femoral-driven varus knee and the constitutional varus knee dominated by intra-articular wear. The clinical indication for MOWHTO performance should not be reduced to the medial arthritic varus knee with underlying tibial varus alone. LEVEL OF EVIDENCE: Level IV, retrospective comparative study.
Asunto(s)
Osteoartritis de la Rodilla , Humanos , Masculino , Persona de Mediana Edad , Femenino , Osteoartritis de la Rodilla/cirugía , Estudios Retrospectivos , Estudios de Seguimiento , Articulación de la Rodilla/cirugía , Tibia/cirugía , OsteotomíaRESUMEN
The lateral tibial spine (LTS) is frequently proposed as a correction target in high tibial osteotomy (HTO), although little is known about its exact radiographic position. This study primarily aims to define the position and variance of the LTS. Secondly, this study wants to investigate the relevance of the LTS position on the mechanical tibiofemoral angle (mTFA°) while planning and postoperatively landing the weight-bearing line (WBL) on this landmark. The LTS position was studied on preoperative full-leg standing radiographs (FLSR) and computed tomography (CT) scans in 70 cases. 3D models of the tibia were created in Mimics 23.0 and measurements were conducted in 3-matic 15.0 (Materialise, Leuven®). Next, 100 HTO cases were retrospectively planned with the WBL through the LTS according to Dugdale's method on FLSR. Finally, 55 postoperative FLSR which had the WBL on the LTS (±2%) were assessed for mTFA° outcome. Statistics were conducted in GraphPad 8.0. The LTS was located at 58.3%±1.9 [55-63%] in 2D and 57.3%±2.2 [53-63%] in 3D showing a high correlation (r=0.77 [0.65 to 0.85]). The planned mTFA on the LTS was 181.8°±0.3 (181.3°-182.5°). On postoperative FLSR, the mTFA was 182.2°±0.6 (180.9°-183.1°). The lateral tibial spine is located at 57-58% on the tibial plateau with a 10% maximal variation range. Good agreement was found between 2D and 3D imaging modalities while evaluating its position in the coronal plane. When aiming the WBL through the LTS during valgus-producing HTO, a consistent realignment of 181-183° mTFA can be expected when performing accurate surgery.