Analysis of Knee Joint Line Obliquity after High Tibial Osteotomy

Abstract

The aim of this study was to evaluate which lower extremity alignment (knee and ankle joint) parameters affect knee joint line obliquity (KJLO) in the coronal plane after open wedge high tibial osteotomy (OWHTO). Overall, 69 knees of patients that underwent OWHTO were evaluated using radiographs obtained preoperatively and from 6 weeks to 3 months postoperatively. We measured multiple parameters of knee and ankle joint alignment (hip-knee-ankle angle [HKA], joint line height [JLH], posterior tibial slope [PS], femoral condyle-tibial plateau angle [FCTP], medial proximal tibial angle [MPTA], mechanical lateral distal femoral angle [mLDFA], KJLO, talar tilt angle [TTA], ankle joint obliquity [AJO], and the lateral distal tibial ground surface angle [LDTGA]; preoperative [-pre], postoperative [-post], and the difference between -pre and -post values [-Δ]). We categorized patients into two groups according to the KJLO-post value (the normal group [within ± 4 degrees, 56 knees] and the abnormal group [greater than ± 4 degrees, 13 knees]), and compared their -pre parameters. Multiple logistic regression analysis was used to examine the contribution of the -pre parameters to abnormal KJLO-post. The mean HKA-Δ (-9.4 ± 4.7 degrees) was larger than the mean KJLO-Δ (-2.1 ± 3.2 degrees). The knee joint alignment parameters (the HKA-pre, FCTP-pre) differed significantly between the two groups ( < 0.05). In addition, the HKA-pre (odds ratio [OR] = 1.27, = 0.006) and FCTP-pre (OR = 2.13, = 0.006) were significant predictors of abnormal KJLO-post. However, -pre ankle joint parameters (TTA, AJO, and LDTGA) did not differ significantly between the two groups and were not significantly associated with the abnormal KJLO-post. The -pre knee joint alignment and knee joint convergence angle evaluated by HKA-pre and FCTP-pre angle, respectively, were significant predictors of abnormal KJLO after OWHTO. However, -pre ankle joint parameters were not significantly associated with abnormal KJLO after OWHTO.

Knee ankle joint line angle: a critical value at 10。 for decompensated knee joint line obliquity in medial opening wedge osteotomy.

“…In accordance with previous studies, higher preoperative mHKA and MPTA were also predictors of higher postoperative KJLO [9,14]. It was reasonable that higher mHKA might require a larger correction, which was supposed to result in greater obliquity.…”

“…This phenomenon can be explained by the compensation of the ankle joint [8,18]. However, the capacity of compensation differs among individuals [9,15,25], and currently there is no information about the maximum of the capacity for most of the patients undergoing MOWHTO. Understanding when the knee obliquity will be "decompensated" is essential to ensure a satisfactory outcome.…”

“…In order to relieve the stress at medial compartment, MOWHTO shifts the mechanical axis of the lower extremity laterally. However, this procedure inevitably changes the joint inclination in the coronal plane since the medial tibia is elevated [5][6][7][8][9]. In cases of severe varus deformity of the knee joint due to proximal tibial deformity or combined deformity of both the distal femur and proximal tibia, single-level osteotomy can result in high-degree joint obliquity because a large amount of correction is required [5][6][7], which can induce excessive shear force on the articular cartilage [10].…”

“…There have been several studies discussing preoperative parameters associated with greater postoperative knee joint line obliquity [9,14]. Preoperative mechanical hip-knee-ankle angle (mHKA), medial proximal tibial angle (MPTA) and joint line convergence angle (JCLA) are well-established predictors of postoperative abnormal joint obliquity.…”

Development and validation of a prediction model for knee joint line orientation after high tibial osteotomy

“…A previous study have noted that correcting only the proximal tibia with the aim of achieving a normal mechanical axis(MA) with HTO may result in overcorrection of the tibia [5]. An overcorrection in the proximal tibia may induce abnormal knee joint line orientation (KJLO), which has been raised as a concern in previous studies for the negative effect on joint biomechanics [6–9]. KJLO plays a crucial role in analysing the balance of forces across the knee joint.…”