Knee-ankle joint line angle: a significant contributor to high-degree knee joint line obliquity in medial opening wedge high tibial osteotomy

Purpose This study aimed to measure the change in knee joint line obliquity (KJLO) and the changes in radiologic parameters of the ankle and hip joints after medial opening-wedge high tibial osteotomy (MOWHTO), and to evaluate the correlation and causal relationship between these parameters. Methods This study evaluated 109 patients who underwent MOWHTO between April 2015 and December 2021. Radiologic parameters, including KJLO, medial proximal tibial angle (MPTA), ankle joint line obliquity (AJLO), and hip abduction angle (HAA), were analysed before and 1 year after MOWHTO. Multiple linear regression analysis was used to identify independent variables that significantly affected the change in KJLO after MOWHTO. Receiver operating characteristic (ROC) analysis was used to evaluate the cutoff value for a change in KJLO that exceeded 5° postoperatively, and the predicting values of radiologic parameters. Results Multiple linear regression analysis showed that changes in MPTA, AJLO, and HAA (β = 0.440, P < 0.001; β = − 0.310, P < 0.001; β = 0.164, P = 0.035, respectively) were predictors of the change in KJLO after MOWHTO. ROC analysis showed that the threshold value for a change in KJLO which exceeded 5° postoperatively was 4.6° (66.7% sensitivity, 63.8% specificity, P = 0.025). Moreover, ROC curves for predicting a change in KJLO of > 4.6° showed that the AUC was significantly higher for the change in MPTA than that of the other two parameters (P = 0.011 for AJLO and P < 0.001 for HAA). Conclusion MOWHTO increases the KJLO by valgization of the proximal tibia and causes hip adduction and ankle valgization. The postoperative ankle valgization after MOWHTO could reduce the increase in KJLO, counteracting the effects of proximal tibial valgization and hip adduction. Therefore, the effects of the hip and ankle joints should be considered to achieve an optimal KJLO and satisfactory clinical outcomes after MOWHTO. Level of studyCohort study, IV. Keywords Knee • Medial opening-wedge high tibial osteotomy • Knee joint line obliquity • Hip abduction angle • Ankle joint line obliquity Sang-Gyun Kim and June-Bum Jun contributed equally to this work and should be considered as co-first authors.

Section: Discussionmentioning

confidence: 99%

Changes in ankle and hip joints following medial opening‐wedge high tibial osteotomy affect knee joint line obliquity

Kim,

Jun,

Bae

et al. 2023

“…And difference of offset of each X-ray was defined as offset change. Hip-knee-ankle angle (HKA) was measured in both preoperative and postoperative lower limb Scanogram [18,19]. Measurement of the PTS used the proximal tibial anterior cortical line.…”

Section: Radiologic Evaluationmentioning

confidence: 99%

Controlled posterior condylar milling technique for unicompartmental knee arthroplasty minimises tibia resection during gap balancing: Short‐term clinical results

Koh,

Lim,

Park

et al. 2024

PurposeThe purpose of this study was to demonstrate the clinical utility of controlled posterior condylar milling (CPCM) in gap balancing while minimally resecting the tibia during fixed‐bearing unicompartmental knee arthroplasty (UKA).MethodsThis study is a retrospective cohort study. Patients who underwent medial UKA for isolated medial compartment osteoarthritis with a minimum follow‐up of 2 years were included. The patients were divided into two groups: the conventional group (n = 56) and the CPCM group (n = 66). In the CPCM group, the proximal tibia was resected at the level of the distal end of the subchondral bone. If the flexion gap was tighter than extension, the posterior condyle was additionally milled to adjust gap tightness. Standing knee X‐ray and scanogram were used to evaluate alignment and tibia resection amount. Range of motion (ROM) and Western Ontario McMaster Universities Osteoarthritis Index (WOMAC) scores were used to evaluate clinical outcomes.ResultsThe CPCM group showed significantly smaller tibia resection (3.6 ± 1.9 mm) compared to the conventional group (5.2 ± 2.7 mm) (p < 0.001). Postoperative ROM (133.0 ± 8.3°, 135.2 ± 7.2°, n.s.) and WOMAC (19.3 ± 13.6, 23.6 ± 17.7, n.s.) were not significantly different between the two groups. Postoperative periprosthetic fractures occurred in two patients in conventional group, while the CPCM group had no periprosthetic fractures.ConclusionThe CPCM technique may be a simple and useful intraoperative technique that can achieve minimal tibia resection and promising clinical outcomes while easily adjusting gap tightness between flexion and extension during medial fixed‐bearing UKA.Level of EvidenceLevel III.

“…The radiographic measurements were completed by two fellowship-trained orthopaedic specialists. Measurements were carried out twice with an interval of 8 weeks in between; the following parameters were measured: hip knee ankle (HKA) [15], weightbearing line ratio (WBR) [8], medial proximal tibial angle (MPTA) [22], mLDFA [22], KJLO [22], joint line convergence angle (JLCA) [12], knee-ankle joint angle (KAJA) [28,30], and distal tibial ground surface angle (DTGSA) [22]. (Figures 1-3, respectively).…”

Section: Radiological Analysismentioning

confidence: 99%

“…Currently, various measurement techniques have been described regarding the inclination of the knee joint line [30]. However, there are few studies that have evaluated the long-term clinical implications of these techniques [16,28,30]. The knee joint line orientation angle (KJLOA), also known as knee joint line obliquity (KJLO), demonstrates the position of the proximal tibial plateau relative to the ground.…”

Section: Introductionmentioning

confidence: 99%

“…In total knee arthroplasty, KJLO has a prominent role in assessing both the mechanical and kinematic alignment [3,5,9]. Similarly, it stands as a fundamental alignment target in surgeries such as unicompartmental knee arthroplasty (UKA) and high tibial osteotomy (HTO) [2,13,25,28]. In the current literature, the impact of KJLO on clinical outcomes has been well-established [7,14,23].…”

Section: Introductionmentioning

confidence: 99%

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CPAK classification detect the real knee joint apex position in less than half of the knees

Şahbat,

Chou,

et al. 2024

PurposeAccurate assessment of the knee joint line is essential for surgeries involving the knee. The knee joint line obliquity (KJLO) is a radiological measurement that evaluates the position of the knee joint relative to the ground and is frequently used in preoperative planning and clinical follow‐up. On the other hand, coronal plane alignment of the knee (CPAK) classifications assesses the joint line as the summation of the medial proximal tibial angle (MPTA) and mechanical lateral distal femoral angle (mLDFA). The purpose of this study is to determine the concordance of these two measurement techniques.MethodsThis cross‐sectional study evaluated the long‐leg standing radiographs (LSRs) of 164 healthy knees. The extremity KJLO and CPAK classification JLO were measured twice by two observers at 8‐week intervals. The knee joint line apex positions (proximal, neutral and distal) of the two measurement techniques are compared (concordance or discordant). The intraobserver and interobserver reliability were examined using the intraclass correlation coefficient (ICC). Possible causes of the discordant were evaluated with univariate and multivariate logistic regression analysis.ResultsCPAK classification detected the KJLO apex position in 70 extremities (42.7%) only. Subgroups CPAK JLO detected 13.6% of the proximal apex, 20.4% of the neutral, and 90.7% of the distal apex (p < 0.01). Upon multivariate logistic regression analysis, the variable KJLO apex position (proximal, neutral vs. distal, odds ratio (OR) = 10.291, 95% confidence interval [CI] = 2.225–25.656, and (p < 0.01) was determined as a risk factor for discordant.ConclusionThe CPAK JLO measurement technique can be misleading in defining the KJLO apex position and the concordance between them is less than 50%. It has a high tendency to misleadingly predict proximal and neutral apex positions, which can potentially have negative implications for assessing the joint line.Level of EvidenceLevel I.