Varus Morphology And Its Surgical Implication In Osteoarthritic Knee And Total Knee Arthroplasty

Background Knee varus alignment represents a notorious cause of knee osteoarthritis. It can be caused by tibial deformity, combined tibial-femoral deformity and/or ligament imbalance. Understanding malalignment is crucial in total knee arthroplasty (TKA) to restore frontal plane neutral mechanical axis. The aim of this study was to determine which factor contributes the most to varus osteoarthritic knee and its related surgical implications in performing a TKA. Methods We retrospectively evaluated 140 patients operated for TKA due to a varus knee. Full-leg hip to ankle preoperative X-rays were taken. Radiological parameters recorded were: mechanical axis deviation (MAD), hip-knee-ankle (HKA), anatomical-mechanical Angle (AMA), medial neck-shaft angle (MNSA), mechanical lateral distal femoral angle (mLDFA), medial proximal tibial angle (MPTA), joint line convergence angle (JLCA), lateral proximal femoral angle (LPFA), lateral distal tibial angle (LDTA), femoral bowing and length of tibia and femur. We also determined ideals tibial and femoral cuts in mm according to mechanical alignment technique. A R2 was calculated based on the linear regression between the predicted values and the observed data. Results The greatest contributor to arthritic varus (R=0,444) was MPTA. Minor contributors were mLDFA (R= 0.076), JLCA (R = 0,1554), LDTA (R = 0.065), Femoral Bowing (R= 0,049). We recorded an average of 7,6 mm in lateral tibial cut thickness to restore neutral alignment. Conclusions The radiological major contributor to osteoarthritic varus knee alignment is related to proximal tibia deformity. As a surgical consequence, during performing TKA, the majority of the correction should therefore be made on tibial cut.

Relationship between the Height of Fibular Head and the Incidence and Severity of Knee Osteoarthritis

Objective: To investigate the correlation between fibular head height and the incidence and severity of varus knee osteoarthritis based on three-dimensional reconstruction of the knee joint.Methods: The data of knee joint imaging in our hospital from June 2018 to June 2020 were collected. The degree of varus deformity of the knee was assessed at the superior hip-knee-ankle angle of the X-rays. Three-dimensional reconstruction of patient computed tomography(CT)data was performed by mimics software. The fibular head height, joint line convergence angle (JLCA) and medial proximal tibial angle (MPTA) were measured in a three-dimensional model. The patients were divided according to the Kellgren-Lawrence grade: group A: grade 0, group B: grade I, group C: grade II, group D: grade III, and group E: grade IV. The differences in age, gender, height, weight, body mass index(BMI), fibular head height, and degree of varus deformity (JLCA, MPTA, and coxa-knee-ankle angle) were compared. Ordinal multivariate logistic regression was used to analyze the correlation between fibular head height and Kellgren-Lawrence grade.Pearson correlation was used to analyze the correlation between fibular head height and Kellgren-Lawrence grade.Results: 232 patients (232 knees) were finally included in the study, with Kellgren-Lawrence grades of 28 in group A, 31 in group B, 49 in group C, 53 in group D, and 71 in group E. The differences in age, gender, height, body mass index, fibular head height, JLCA, MPTA, and hip-knee-ankle angle among the five groups were statistically significant (P < 0.05), and the differences in body weight were not statistically significant (P > 0.05). There were significant differences in fibular head height, JLCA, JLCA and hip-knee-ankle angle between different groups (P < 0.05). Furthermore, there were significant differences in JLCA and hip-knee-ankle angle (P < 0.05), and both JLCA and hip-knee-ankle angle increased with severe aggravation of Kellgren-Lawrence grade. Furthermore, both fibular head height and MPTA decreased as the Kellgren-Lawrence grade was severely aggravated. There was a significant negative correlation between Kellgren-Lawrence grade and fibular head height (r = -0.812, P < 0.001). Furthermore, there was a significant negative correlation between fibular head height and hip-knee-ankle angle (r = -0.7905, P < 0.001). When Kellgren-Lawrence grade III and IV knees were considered as disease, ROC curve analysis showed a cut-off value of 10.63 for fibular head height and an AUC of 0.872.Conclusion: The height of fibular head in patients with varus knee osteoarthritis is smaller than that in non-osteoarthritis patients. In addition to body mass index, fibular head height is a risk factor for the pathogenesis of varus knee osteoarthritis,the smaller the fibular head height, the more severe the severity of osteoarthritis and the more severe the degree of varus deformity.

Early Failure of Total Ankle Arthroplasty in a Patient with Ipsilateral Varus Knee Deformity

Multiple risk factors such as age, body mass index (BMI), preoperative diagnosis, smoking, diabetes mellitus, malalignment of an implant, and presence of ipsilateral hindfoot fusion have been shown to contribute to failure of total ankle arthroplasty (TAA). However, the exact causes of TAA failure remain uncertain, and various causes can lead to a need for revision surgery. We report a case of early aseptic loosening of the implant following TAA in a patient with severe varus deformity of the ipsilateral knee.

Novel ideas for the comprehensive evaluation of varus knee osteoarthritis: radiological measurements of the morphology of the lateral knee joint

BackgroundThe lateral anatomical and morphological characteristics of knees with varus knee osteoarthritis (OA) have not received sufficient attention. This study used several radiological parameters to describe the morphological characteristics of the lateral knee with OA to determine whether there are relationships between varus knee OA and parameters such as lateral plateau widening (LPW), proximal fibula curvature (PFC), and fibula height (FH).MethodsThe study retrospectively analyzed 1072 subjects [376 males, 696 females; mean age 66.84 ± 7.04 (range 46–83) years; mean body mass index (BMI) 26.98 ± 3.22 kg/m²] who underwent standard radiography for diagnosing or evaluating symptomatic knee joint disease. The 163 Kellgren and Lawrence (K-L) grades 0 and I knees were categorized into the no-knee-OA group, and the 909 K-L grades II–IV knees were classified into the knee-OA group. The medial proximal tibial angle (MPTA), joint line convergence angle (JLCA), and hip-knee-ankle angle (HKAA) were measured to investigate varus knee deformity. The LPW, PFC, and FH were measured. T-tests and chi-square tests were used to compare each index between the two groups. Binary logistic regression was performed to examine the correlation between indexes and knee OA occurrence. Principal component analysis was used to calculate the comprehensive principal component score of varus deformity, which was used to comprehensively evaluate the knee varus deformity degree by reducing the original data's dimension. Multiple logistic and linear regression analyses were performed to examine the correlations between the three parameters and K-L grades and the comprehensive principal component score of varus deformit.ResultsLPW and PFC were significantly greater and FH was significantly smaller in the knee-OA group than in the no-knee-OA group. LPW, PFC, and FH were correlated with knee OA occurrence. One principal component, named the comprehensive principal component score of varus deformity, was extracted from the three indexes, and the total variance of the principal component interpretation was 76.60%. Multivariate logistics and linear regression analysis showed that after adjusting for age and BMI, LPW and PFC were positively correlated with K-L grading and varus deformity. FH was significantly and negatively associatedwith K-L grading and varus deformity (all P < 0.05).ConclusionsRegular morphological changes take place in the lateral knee with varus OA, including lateral dislocation of the tibial plateau, proximal fibula bending, and upward movement of the fibular head. Changes in LPW, PFC, and FH could enable a more comprehensive assessment of varus knee OA occurrence, severity, and deformity.Level of EvidenceRetrospective Study Level III

Association between changes in hip-knee-ankle angle and hindfoot alignment after total knee arthroplasty for varus knee osteoarthritis

Background The change in hip-knee-ankle (HKA) angle after total knee arthroplasty (TKA) may cause an adjustment in hindfoot alignment (HFA). However, the relationship between the changes in HKA angle and HFA is still not well studied. This study aimed to investigate the association between HKA angle and hindfoot alignment changes after TKA for varus knee osteoarthritis. Methods A prospective study was carried out in which 108 patients with varus knee deformities were radiographically and clinically evaluated before and 3 months after TKA. The relationship of change in HFA with correction in HKA angle was investigated. Results The results showed that the HFA was adjusted significantly by 3 months after TKA (p < 0.001), along with improved American Orthopaedic Foot and Ankle Society (AOFAS) ankle hindfoot score (p < 0.001). Next, a univariate correlation and linear regression analysis showed that the change in HFA was weakly correlated with the change in HKA angle (r=-0.262, β=-0.14, 95 % CI: -0.23 to -0.04, P = 0.006). Further stratified analysis and interaction tests revealed that age has a distinct effect on the correlation between the changes in HFA and HKA angle. The correlation was dramatically greater in the group under 65 years (r=-0.474, β=-0.26, 95 % CI: -0.41 to -0.12, P = 0.001), whilst, no correlation was observed in those above 65 years old (r=-0.036, β=-0.02, 95 % CI: -0.14 to 0.11, P = 0.779). Conclusions Our findings indicated that correction of HKA after TKA tend to promote adjustment in the hindfoot alignment toward re-balance of the whole lower limb weight-bearing axis. However, this mechanism obviously weakens in elderly patients. Therefore, if apparent hindfoot deformity exists in these patients before TKA, more perioperative intervention is required for hindfoot adjustment, and even HKA undercorrection may be considered.