Varus morphology and its surgical implication in osteoarthritic knee and total knee arthroplasty

Do knee alignment patterns differ between Middle Eastern and East Asian populations? A propensity-matched analysis using artificial intelligence

INTRODUCTION

Population-based differences in knee alignment patterns may impact osteoarthritis (OA) progression. This study compares lower extremity alignment in knee OA between Middle Eastern (UAE) and East Asian (South Korean) populations using artificial intelligence (AI)-assisted analysis.

METHODS

A retrospective review included patients with knee symptoms from South Korea (2009-2019) and the United Arab Emirates (UAE) (2015-2024). Exclusion criteria comprised prior knee surgeries, significant bony attrition, and low-quality radiographs. Propensity score matching controlled for age and sex differences between populations. Alignment parameters (hip-knee-ankle angle (HKA), medial proximal tibial angle (MPTA), lateral distal femoral angle (LDFA), and joint line convergence angle (JLCA)) and OA severity (Kellgren-Lawrence (KL) grade) were measured using artificial intelligence (AI) software, along with the analysis of coronal plane alignment of the knee (CPAK) classification. Subanalyses by sex and age group (under 40, 40-60, and over 60 years) were also conducted.

RESULTS

A total of 1098 UAE and 7138 South Korean patients (2196 and 14,276 knees, respectively) were evaluated in this study. Post-matching (1:2), body mass index was significantly higher in UAE patients (p < 0.001). CPAK type 1 was predominant in UAE male patients (42.4%), whereas type 2 was more common in South Korean male patients (30.6%). Female patients in both populations predominantly exhibited CPAK type 2 (UAE 30.6%; South Korea 35.3%). UAE patients showed a lower MPTA with increasing age, indicating a trend toward more varus alignment in older individuals.

CONCLUSIONS

A propensity score-matched analysis revealed significant alignment differences between Middle Eastern and East Asian populations, underscoring the importance of population-specific considerations in OA management.

Hypoplasia of the Lateral Femoral Condyle Is Not Associated With Valgus Knee Alignment

BACKGROUND

Valgus lower limb alignment has anecdotally been associated with lateral femoral condyle (LFC) hypoplasia. However, limited scientific evidence exists to substantiate this doctrine. This study aimed to investigate the association between coronal plane alignment (CPA) and bony distal femoral geometry.

METHODS

Routine preoperative computed tomography scans and full-length weight-bearing radiographs were analyzed for patients undergoing primary total knee arthroplasty, and standardized measurements of bony distal femoral geometry were recorded. Ratios between lateral to medial structure measurements were used to adjust for size differences between patients. Patients were grouped by CPA and sex with statistical analysis performed to determine any significant groupwise differences for each measurement/ratio.

RESULTS

There were 156 patients included, with 83 women (53.2%) and 73 men (46.8%). There were 100 patients (64.1%) who demonstrated varus (women n = 49; men n = 51) and 56 patients (35.9%) who had valgus alignment. No significant differences were observed between groups in age, body mass index, race, or laterality of the imaged knee. Linear regression modeling demonstrated no significant groupwise differences in lateral/medial condyle anteroposterior (AP) distance or lateral/medial posterior condyle offset ratios in relation to CPA and sex, or in lateral/medial condyle diameter ratio in relation to CPA alone. Valgus alignment was associated with significantly reduced lateral/medial epicondyle to posterior condyle distance ratio, lateral/medial femoral column length ratios, and increased lateral femoral AP condyle distance to transcondylar width.

CONCLUSIONS

No statistically significant differences exist across most standardized measurements of lateral distal femoral geometry in relation to CPA. Contrary to conventional thought, patients who had valgus alignment did not demonstrate reduced bony AP diameter of the LFC. Perceived LFC hypoplasia in patients who have valgus alignment may be attributable to differences in cartilage wear of the LFC, relative shortening of the lateral femoral column, or a relative posterior position of the lateral epicondyle resulting in an internally rotated appearance of the distal femur in the axial plane relative to the transepicondylar axis.

Association Between Preoperative Radiological Findings and Outcomes After Total Knee Arthroplasty

Introduction Total knee arthroplasty (TKA) is a widely accepted surgical intervention for patients with advanced knee osteoarthritis, aimed at reducing pain and improving functional mobility. Preoperative radiological evaluations, including assessments of joint space narrowing, osteophytes, varus/valgus deformities, and subchondral sclerosis, are essential for planning the surgery and predicting postoperative outcomes. Although extensive research has been conducted internationally, data focusing on populations in Saudi Arabia remain limited. This study investigates the association between preoperative radiological findings and postoperative outcomes, including pain, range of motion (ROM), and functional status, in a Saudi retrospective cross-sectional study.  Methods This retrospective cross-sectional study was conducted at King Abdulaziz Medical City in Jeddah, Saudi Arabia. A total of 523 patients who underwent TKA were included. Data were collected from medical records through the BESTCare system, focusing on patient demographics, preoperative and postoperative radiological findings, and surgical outcomes. Statistical analyses were performed using IBM SPSS Statistics software (IBM Corp., Armonk, NY), and the significance was determined at p < 0.05.  Results The study population had a median age of 64 years, and 72% were female. Preoperative radiological findings included varus deformity (65.39%), joint space narrowing (47.61%), and osteophytes (31.17%). Postoperative outcomes showed 19% of patients reported pain, 85% regained normal ROM, and 74% returned to normal functional status. Significant associations were found between postoperative limited ROM and preoperative osteophytes (p = 0.021), subchondral sclerosis (p = 0.033), and osteopenia (p = 0.017). Subchondral sclerosis was also linked to postoperative functional impairment (p = 0.009). No significant association was observed between preoperative radiological findings and postoperative pain or thromboembolism.  Conclusion Preoperative radiological markers, particularly osteophytes and subchondral sclerosis, were significant predictors of postoperative ROM and functional status in TKA patients. Identifying these markers can enhance preoperative planning, enable targeted rehabilitation strategies, and improve patient outcomes in the Saudi population. Further studies are warranted to confirm these findings and explore additional predictive factors.

Considerations of morphometry and phenotypes in modern knee arthroplasty

As advancements in total knee arthroplasty progress at an exciting pace, two areas are of special interest, as they directly impact implant design and surgical decision making. Knee morphometry considers the three-dimensional shape of the articulating surfaces within the knee joint, and knee phenotyping provides the ability to categorize alignment into practical groupings that can be used in both clinical and research settings. This annotation discusses the details of these concepts, and the ways in which they are helping us better understand the individual subtleties of each patient's knee.

In-silico study of the biomechanical effects of proximal-fibular osteotomy on knee joint contact pressure in varus-valgus misalignment

The aim of this work is to investigate in-silico the biomechanical effects of a proximal fibular osteotomy (PFO) on a knee joint with different varus/valgus deformities on the progression of knee osteoarthritis (KOA). A finite element analysis (FEA) of a human lower extremity consisting of the femoral, tibial and fibular bones and the cartilage connecting them was designed. The FEA was performed in a static standing primitive position to determine the contact pressure (CP) distribution and the location of the center of pressure (CoP). The analysis examined the relationship between these factors and the degree of deformation of the hip-knee angle in the baseline condition. The results suggested that PFO could be a simple and effective surgical treatment for patients with associated genu varum. This work also reported that a possible CP homogenization and a CoP correction can be achieved for medial varus deformities after PFO. However, it reduced its effectiveness for tibial origin valgus misalignment and worsened in cases of femoral valgus misalignment.

How effective is proximal fibular osteotomy in redistributing joint pressures? Insights from an HTO comparative in-silico study

BACKGROUND

Knee osteoarthritis (KOA) represents a widespread degenerative condition among adults that significantly affects quality of life. This study aims to elucidate the biomechanical implications of proximal fibular osteotomy (PFO), a proposed cost-effective and straightforward intervention for KOA, comparing its effects against traditional high tibial osteotomy (HTO) through in-silico analysis.

METHODS

Using medical imaging and finite element analysis (FEA), this research quantitatively evaluates the biomechanical outcomes of a simulated PFO procedure in patients with severe medial compartment genu-varum, who have undergone surgical correction with HTO. The study focused on evaluating changes in knee joint contact pressures, stress distribution, and anatomical positioning of the center of pressure (CoP). Three models are generated for each of the five patients investigated in this study, a preoperative original condition model, an in-silico PFO based on the same original condition data, and a reversed-engineered HTO in-silico model.

RESULTS

The novel contribution of this investigation is the quantitative analysis of the impact of PFO on the biomechanics of the knee joint. The results provide mechanical evidence that PFO can effectively redistribute and homogenize joint stresses, while also repositioning the CoP towards the center of the knee, similar to what is observed post HTO. The findings propose PFO as a potentially viable and simpler alternative to conventional surgical methods for managing severe KOA, specifically in patients with medial compartment genu-varum.

CONCLUSION

This research also marks the first application of FEA that may support one of the underlying biomechanical theories of PFO, providing a foundation for future clinical and in-silico studies.

How Do the Morphological Abnormalities of Femoral Head and Neck, Femoral Shaft and Femoral Condyle Affect the Occurrence and Development of Medial Knee Osteoarthritis

OBJECTIVE

At present, the main viewpoint is that tibial varus is the main reason of medial knee osteoarthritis (OA), and high tibial osteotomy (HTO) is also the main alignment correction method to correct medial knee OA. In contrast, the impact of the anatomical alignment of the femur on medial knee OA is often overlooked. We evaluated the increased risk for medial knee OA because a varus alignment could be attributed to the anatomical reasons that include hip anatomy, femoral shaft bowing (FSB) and femoral condylar dysplasia.

METHODS

The present research adopted a cross-sectional study method. We selected 62 patients with HTO in the Third Hospital of Hebei Medical University from June 2021 to March 2022 as the HTO group and 55 healthy volunteers as the control group. Femoral neck-shaft angle (NSA), lateral FSB, mechanical lateral distal femoral angle (mLDFA) and hip-knee-ankle (HKA) was radiographically examined within the two groups. The femoral neck length and offset were also measured, and the ratio is represented by the ratio of the femoral neck length to off-set (N/O). The 2-tailed Student t-test was used to compare the differences between groups when the data were in accordance with a normal distribution. Otherwise, the Mann-Whitney U tests was used to compare the differences between groups.

RESULT

Compared to the control group, the HTO group had a higher offset (p < 0.05), greater femoral neck length (p < 0.05), and decreased (more varus) NSA (p < 0.05). The HKA in the HTO group was 172.20 ° (3.50°), which was significantly lower than that of the control group 177.00° (3.05°), (p < 0.001), while the medial OA was associated with more varus HKA. The mean mLDFA was 89.10 ° (2.35°) and 87.50° (2.85°) in the HTO and control groups (p < 0.005), respectively. The mean lateral FSB values of the full-length radiographs were larger (p < 0.001) in the HTO group (4.24° ± 3.25°) than that in control group (1.16° ± 2.32°).

CONCLUSION

The reduction of NSA (coxa vara) and the increase of the mLDFA can lead to medial knee OA, while the lateral FSB also affects medial OA. We believe that femoral deformity is also one of the cause of the medial knee OA. Therefore, it is necessary to evaluate the joint deformity of the femur and tibia before surgery in order to determine whether to use HTO alone to correct the lower limb alignment.