Association of the joint line orientation angle of the contralateral limb with the alignment change of the unilateral and bilateral opening-wedge high tibial osteotomy

Achieving Sufficient Valgus Alignment is Essential to Ensure Low Residual Pain in Short- to Midterm Follow-up After High Tibial Osteotomy in KL Grade 4 Osteoarthritis Patients

Background

Severe osteoarthritis (OA) has been identified as a risk factor for inferior outcomes following high tibial osteotomy (HTO).

Purpose

To investigate the effectiveness of HTO in patients with advanced OA, particularly those with Kellgren-Lawrence (KL) grade 4 (KL4), and to compare clinical outcomes based on OA severity and the effect of postoperative alignment in each group.

Study Design

Cohort study; Level of evidence, 3.

Methods

A retrospective review was conducted on patients who underwent biplanar medial opening-wedge HTO from 2010 to 2022, with a follow-up period of 2 to 5 years. Patients were divided into 2 groups based on preoperative KL grades: non-KL4 and KL4. Clinical outcomes were compared using patient-reported outcome (PRO) measures: pain visual analog scale (VAS), Lysholm Knee Score, and Knee injury and Osteoarthritis Outcome Score (KOOS) between the groups. Subgroup analyses were conducted to ascertain whether outcomes differed based on postoperative weightbearing line (WBL) ratio within each group.

Results

Out of 324 patients, 141 were eligible: 110 in the non-KL4 group and 31 in the KL4 group, with a mean follow-up of 37.5 months (overall mean age, 56.9 years; mean body mass index, 26.9 kg/m2). Baseline demographics were similar between the groups. The KL4 group had more severe preoperative conditions (larger defect size and more varus). However, both groups showed significant improvements in PROs (P < .001), with no significant differences between them. In the KL4 group, patients with a postoperative WBL ratio ≥62.5% showed better scores in certain PRO measures, while other PRO data showed no significant differences (VAS: 17.1 ± 19.1 vs 33.9 ± 18.3, P = .03; KOOS Activities of Daily Living subscale: 78.7 ± 9.9 vs 69.3 ± 13.8, P = .04). In contrast, the non-KL4 group showed no difference in PROs based on WBL ratio. In the KL4 group, the final VAS was most correlated with the WBL ratio (r = -0.545; P = .002). A WBL ratio of 62.2% to 67.3% was the cutoff value to predict the achievement of low residual pain (VAS < 18; median of KL4 group) in KL4 patients.

Conclusion

HTO can yield comparable clinical outcomes in KL4 OA patients to those with lower-grade OA. However, achieving sufficient valgus alignment (WBL ratio > 62.2%-67.3%) correlates with less residual pain in the short- to midterm follow-up in high-grade OA patients.

Prediction of the Serial Alignment Change after Opening-Wedge High Tibial Osteotomy Based on Coronal Plane Alignment of the Knee Using Machine Learning Algorithm

Categorization of alignment into phenotypes can be useful for predicting and analyzing postoperative alignment changes after opening-wedge high tibial osteotomy (OWHTO). The purposes of this study were to (1) develop a machine learning model for the predicting the Coronal Plane Alignment of the Knee (CPAK) phenotypes of final alignment after OWHTO, and (2) analyze predictive factors for final alignment phenotypes. Data were retrospectively collected from 163 knees that underwent OWHTO between March 2014 and December 2019. Each data were assessed at three time points: preoperatively, at 3 months postoperatively, and the final follow-up. Constitutional alignment was also evaluated. Machine learning models were developed using two independent feature sets consisting of serial radiologic parameters and CPAK phenotypes. The area under the receiver-operating characteristic curve (AUC) was used as a primary metric to determine the best model. To evaluate the feature importance, Shapley additive explanation (SHAP) analysis was also performed on the best model. Multilayer perceptron (MLP) was the best prediction model, with the highest AUC of 0.867 based on radiologic parameters and 0.783 based on CPAK phenotypes. Joint line obliquity (JLO) at 3 months postoperatively was the most important factor among the radiologic parameters for predicting the final CPAK phenotypes. The features of constitutional and preoperative alignments also contributed, although the features of alignments at 3 months postoperatively were the highest contributing predictors. In conclusion, the developed machine learning models of the MLP showed excellent performance in predicting the final CPAK phenotypes after OWHTO. Postoperative JLO was the most important radiologic parameter for predicting the final alignment. The combination of features of the constitutional, preoperative, and postoperative periods enabled high accuracy and performance in predicting the final alignment.A retrospective cohort study with the level of evidence as level III.

Alignment rod and gap measurement methods achieve comparable alignment correction in opening wedge high tibial osteotomy for varus osteoarthritic knees

Purpose

To compare clinical and radiological outcomes of medial opening wedge high tibial osteotomy (MOWHTO) using two different alignment methods: the alignment rod (AR) versus the gap measurement (GM) method. The primary outcome was to report the surgical accuracy of coronal plane corrections in each method.

Methods

Patients who underwent MOWHTO with either AR or GM method between 2014 and 2022 at a single institution, with a minimum of 2 years of follow-up, were included. The opening gap was gradually spread with an AR under fluoroscopic control in the AR group, whereas the osteotomy site was opened to the value of the measured gap distance in addition to the thickness of the bone saw in the GM group. Radiological assessment of geometric characteristics included hip-knee-ankle angle (HKA), medial proximal tibial angle (MPTA), mechanical lateral distal femoral angle and joint line convergence angle. Surgical accuracy, which is the deviation (Δ) between the intended and achieved correction, was compared between both methods. Clinical outcomes were assessed using the Knee Injury and Osteoarthritis Outcome Scores.

Results

A total of 110 patients (n = 110 knees) with a mean age of 54.1 ± 8.4 years were included in the study. Radiological parameters were significantly improved as reflected by HKA correction from 171.6° ± 2.0° to 181.1° ± 2.6° in the AR group and from 171.0° ± 2.3° to 181.1° ± 2.8° in the GM group at 2 years (Intergroup n.s). There was no significant intergroup difference for all radiological parameters and clinical outcomes. There was no intergroup difference in the surgical accuracy as evaluated by Δvalues and absolute Δvalues of both HKA and MPTA (n.s).

Conclusions

Comparable correction accuracy was achieved in MOWHTO using either the AR or GM method. The GM method is simple and reliable in achieving the intended correction in MOWHTO.

Level of Evidence

Ⅲ retrospective comparative study.

Around-the-knee osteotomies part 1: definitions, rationale and planning-state of the art

Knee osteotomies are essential orthopedic procedures with the ability to preserve the joint and correct ligament instabilities. Literature supports the correlation between lower limb malalignment and outcomes after knee ligament reconstruction and cartilage procedures. Concepts such as joint line obliquity, posterior tibial slope angle, and intra-articular deformity correction are integral components of both preoperative planning and postoperative evaluations. The concept of preserving and/or restoring joint line congruence during simultaneous correction of varus or valgus deformity can be achieved through several different approaches. With advancements in osteotomy research and surgical planning technology, the surgical decision-making has increased in complexity. Based upon a patient's specific deformity, decisions need to be made whether to perform a single-level (proximal tibia or distal femur) versus double-level (both proximal tibia and distal femur) osteotomy, and whether to correct deformity in a single plane (coronal or sagittal) or perform a biplanar osteotomy, correcting two of the malalignments in either coronal, sagittal, or axial planes. Osteotomy procedures prioritize safety, reproducibility, precision, and meticulous planning. Equally important is the proactive management of possible complications and the implementation of preventive strategies for complications such as hinge fractures and unintentional changes to alignment in other planes. This review navigates the intricate landscape of lower limb alignment, commencing with foundational definitions and rationale for performing osteotomies, progressing through the planning phase, and addressing the critical aspect of complication prevention, all while looking ahead to anticipate future advancements in this field. However, rotational osteotomies and tibial tubercle osteotomies in isolation or as an adjunct procedure are beyond the scope of this review.

Coronal and sagittal alignment of ankle joint is significantly affected by high tibial osteotomy

PURPOSE

Changes in coronal and sagittal alignment of the knee joint after HTO have been reported in several previous studies. However, only few of them investigated the changes only on coronal alignment of the ankle joint. The purpose of this study was to investigate changes in both coronal and sagittal alignment of the ankle joint after HTO.

METHODS

46 patients (49 cases) who underwent HTO were retrospectively analyzed. Preoperative and postoperative lower extremity scanogram and EOS imaging system were investigated. The hip-knee-ankle (HKA) angle, medial proximal tibial angle (MPTA), and knee tibia plafond angle (KTPA) were measured by scanogram to evaluate coronal alignment of the knee. Tibial anterior surface angle (TAS), talar tilt (TT), tibial plafond inclination (TPI), and ankle joint axis point on the weight-bearing-line (AAWBL) ratio were measured by scanogram to investigate coronal alignment of the ankle. Knee lateral ankle surface angle (KLAS) and tibial lateral surface angle (TLS) were measured by EOS to evaluate sagittal alignment of the ankle.

RESULTS

Varus alignment of the knee was corrected by significant change of the HKA angle (5.8 ± 3.1° vs. - 2.1 ± 2.8°, p < 0.001), MPTA (85.7 ± 2.9° vs. 91.7 ± 3.3°, p < 0.001), and KTPA (5.0 ± 3.5° vs. - 2.1 ± 4.2°, p < 0.001) after HTO. Regarding the ankle coronal alignment, there was significant change in TPI (3.9 ± 3.4° vs. - 0.9 ± 3.8°, p < 0.001) and AAWBL ratio (45.5 ± 14.7% vs. 61.6 ± 13.3%, p < 0.001). In sagittal alignment of the ankle, KLAS (4.5 ± 3.1° vs. 7.7 ± 3.7°, p < 0.001) significantly increased. Among the variables, the amount of correction in AAWBL ratio (R = 0.608, p < 0.01) showed strongest relationship with tibial correction angle.

CONCLUSION

Based on the present study, coronal and sagittal alignment of ankle joint was significantly affected by HTO. After HTO, AAWBL ratio increased due to lateralization of the ankle joint axis, and KLAS increased due to increased posterior tibial slope.

LEVEL OF EVIDENCE

III.