Joint line obliquity was maintained after double-level osteotomy, but was increased after open-wedge high tibial osteotomy.

PURPOSE: To compare the radiographic, clinical, and arthroscopic outcomes of varus osteoarthritic knees treated with an open-wedge high tibial osteotomy (OWHTO) alone or with a double-level osteotomy (DLO). It was hypothesized that treatment with DLO would maintain the joint line obliquity (JLO) and acquire better arthroscopic and clinical outcomes after surgery than OWHTO alone. METHODS: Knees with predicted medial proximal tibial angle (MPTA) > 95° were treated with OWHTO alone or with DLO. Preoperatively, age, body mass index, and hip-knee-ankle angle (HKA) differed between the two groups. Therefore, after adjustment for those factors, 34 knees with OWHTO alone and 34 knees with DLO were compared. On whole-leg radiographs for a single leg, HKA, weightbearing line (WBL) ratio, lateral distal femoral angle (LDFA), MPTA, and JLO were measured before and 2 years after surgery. Clinical outcomes were evaluated by the Knee Society Score (KSS) knee, KSS function, Lysholm, and Knee injury and Osteoarthritis Outcome Score (KOOS) scores before and 2 years after surgery. Arthroscopic findings were obtained before and 1 year after surgery. Various factors were compared between the two groups. RESULTS: JLO increased significantly from 1.4° to 6.3° in the OWHTO group (p < 0.001) and changed from 1.0° to 1.3° in the DLO group (n.s.). Postoperative MPTA and JLO in the OWHTO group were significantly higher than those in the DLO group (both p < 0.001). There were no significant differences in the KSS knee, KSS function, and KOOS scores between the two groups. Postoperative Lysholm score in the DLO group was higher than that in the OWHTO group (p < 0.025). Femoral and tibial cartilage regeneration in the medial condyles and deterioration in the lateral condyles did not differ between the two groups on second-look arthroscopy. CONCLUSIONS: JLO was not significantly changed after surgery in the DLO group. DLO enabled the acquisition of physiological JLO compared with OWHTO alone. LEVEL OF EVIDENCE: Retrospective comparative study, Level III.

Open-wedge high tibial osteotomy using intraoperative control of joint line convergence angle with reference to preoperative supine radiograph.

INTRODUCTION: Preoperative supine joint line convergence angle (JLCA) correlates with postoperative standing JLCA. Here, we compared the radiographic and clinical outcomes of knees with preoperative JLCAs of ≥ 4° and < 4° in open-wedge high tibial osteotomy (OWHTO). We hypothesized that the postoperative coronal alignment in both groups would not be affected by a change in JLCA if this change could predict before surgery. MATERIALS AND METHODS: Eighty-four patients with medial knee osteoarthritis who underwent OWHTO were enrolled retrospectively. A weight-bearing line (WBL) ratio of 62% and a JCLA equivalent to the preoperative supine JLCA were anticipated in preoperative planning. These were intraoperatively set using an alignment rod and a radiolucent protractor under fluoroscopy. Soft tissue correction was defined as correction angle minus bone correction. The participants with preoperative JLCAs of < 4° (low-JLCA group) and ≥ 4° (high-JLCA group) were compared. RESULTS: No significant difference in the coronal alignment was found between the groups after OWHTO. No significant differences in correction angle or bone correction were found between the groups, but the soft tissue correction in the high-JLCA group was higher than that in the low-JLCA group after OWHTO (p = 0.013). CONCLUSIONS: When we controlled intraoperative JLCA, the postoperative coronal alignment was not affected by the change in JLCA and the differences in soft tissue correction between the low-JLCA and high-JLCA groups. However, overcorrection compared with the target coronal alignment remained in both groups. LEVEL OF EVIDENCE: Level III, retrospective comparative study.

The surgical epicondylar axis is a consistent reference of the distal femur in the coronal and axial planes.

PURPOSE: Various rotational landmarks including the surgical epicondylar axis (SEA) are used for preoperative planning and intra-operative reference of total knee arthroplasty (TKA) in the axial plane. The aim of the study was to elucidate the relationships between the SEA and other femoral anatomical landmarks, including the mechanical axis, distal and posterior knee joints, the trochlear groove, and the anterior femoral condyle, in both the coronal and axial planes. METHODS: Angular and linear measurements were taken of sixty femora using Orthomap3D, which has a tool to analyse computed tomography image data that makes it possible to measure three-dimensional distances and angles precisely. The inter- and intra-observer reliabilities of these measurements were evaluated. Comparisons were made according to height, weight, body mass index, and gender. RESULTS: The angle between the mechanical axis and the SEA was 90.2° (95% CI 90.0°-90.4°). There was a significant correlation for each linear measurement between the SEA and the distal/posterior knee joint line and for each linear measurement between the SEA and the anterior medial/lateral femoral condyle. A significant difference was observed between genders in the linear measurements. Significant correlations were found between height and weight and linear parameters. CONCLUSION: Knowledge of the relationships between the SEA and other femoral anatomical landmarks is useful in preoperative planning, intra-operative landmark, and postoperative assessment of TKA. The SEA is a consistent parameter of femoral alignment in the coronal plane and a stable reference for femoral rotation in the axial plane. LEVEL OF EVIDENCE: III.

Lateral hinge fracture delays healing of the osteotomy gap in opening wedge high tibial osteotomy with a beta-tricalcium phosphate block.

BACKGROUND: The purpose of this study was to investigate the healing process of synthetic bone grafts in opening wedge high tibial osteotomy (OWHTO) and to identify the factors that affect bone healing in OWHTO. It was hypothesized that lateral hinge fracture (LHF) is associated with delayed bone healing after OWHTO with synthetic bone grafting. METHODS: The subjects included 350 knees of 283 patients who underwent OWHTO using two wedged blocks of beta-tricalcium phosphate (ß-TCP) with 60% porosity. The healing of the osteotomy gap using a radiologic rating system for OWHTO with synthetic bone grafts and the presence of an LHF were assessed up to postoperative 24 months. RESULTS: LHFs were found in 49 knees (14%). The osteotomy gap showed slower progression of radiographic healing with an LHF than without an LHF (P < .05). In the knees with LHFs, initial radiographic change in the osteotomy gap was observed almost at the same time as healing of the LHF. Multivariate logistic regression analysis identified LHF as the factor preventing the progression of bone healing (OR = 46.78, P < .05). CONCLUSIONS: LHF is associated with delayed bone healing after OWHTO with synthetic bone grafting.