The role of knee alignment in disease progression and functional decline in knee osteoarthritis

Altered motor function during daily activities in patients eligible for high tibial osteotomy is primarily driven by knee varus deformity

Aims

Patients with knee osteoarthritis (OA) and varus deformity present altered gait parameters, especially a large knee adduction moment that is predictive of OA progression. The distinct role of each coexisting parameter, such as OA grade, varus deformity, and previous meniscectomy, in the setting of high tibial osteotomy is not clear. Therefore, the aim of this study was to analyze the motor function parameters in patients eligible for high tibial osteotomy during walking, stair ascending, and stair descending, and to evaluate the effect of OA grade, varus deformity, and meniscectomy.

Methods

A total of 52 patients with knee OA and varus deformity participated in this study, including 22 with previous partial meniscectomy, alongside 20 healthy controls. Imaging and motion-capture data during walking, stair ascending, and descending were acquired. Subject characteristics, joint kinematics, joint kinetics, and electromyography on-off activities were compared to evaluate statistically significant differences between the patients and healthy groups. Additionally, multiple linear regression evaluated the relationships between OA grade, varus deformity, and previous meniscectomy with motor function parameters.

Results

The patients group showed significantly higher knee adduction and rotation moments, lower hip adduction and ankle inversion, and higher knee adduction and trunk flexion compared with the healthy group, as well as significantly increased biceps femoris activity. In addition, larger varus deformity showed a more marked effect on the major motor function parameters compared with OA grade and previous meniscectomy, especially during walking.

Conclusion

Patients eligible for high tibial osteotomy move with altered motor function during daily activities, and the coexisting factors of OA grade, varus malalignment, and previous meniscectomy have different impacts, with varus deformity primarily affecting motor function. These findings help to detect the target that should be considered priority in the treatment of high tibial osteotomy, and highlight the importance of realigning the lower limb to possibly restore motor function.

Femoral bone growth predictions based on personalized multi-scale simulations: validation and sensitivity analysis of a mechanobiological model

Musculoskeletal function is pivotal to long-term health. However, various patient groups develop torsional deformities, leading to clinical, functional problems. Understanding the interplay between movement pattern, bone loading and growth is crucial for improving the functional mobility of these patients and preserving long-term health. Multi-scale simulations in combination with a mechanobiological bone growth model have been used to estimate bone loads and predict femoral growth trends based on cross-sectional data. The lack of longitudinal data in the previous studies hindered refinements of the mechanobiological model and validation of subject-specific growth predictions, thereby limiting clinical applications. This study aimed to validate the growth predictions using magnetic resonance images and motion capture data-collected longitudinally-from ten growing children. Additionally, a sensitivity analysis was conducted to refine model parameters. A linear regression model based on physical activity information, anthropometric data and predictions from the refined mechanobiological model explained 70% of femoral anteversion development. Notably, the direction of femoral development was accurately predicted in 18 out of 20 femurs, suggesting that growth predictions could help to revolutionize treatment strategies for torsional deformities.

Medial meniscus injury changed plantar pressure distributions and decreased posture stability especially in those with varus alignment: a cross-sectional study based on a wearable smart plantar pressure system

BACKGROUND

Medial meniscus (MM) injuries are common and often contribute to knee osteoarthritis (KOA). While studies focus on joint degeneration, the role of extrinsic factors such as postural control remains underexplored. This study investigated how MM injuries affected postural control, particularly plantar pressure distribution, with an emphasis on lower limb alignment.

METHODS

83 participants were recruited: 29 healthy subjects, 29 MM patients with neutral alignment (-3°< hip-knee-ankle angle (HKA) ≤ 3°), and 25 MM patients with varus alignment (HKA > 3°). Plantar pressure was measured using a shoe-integrated detection system. Normalized peak force, center-of-pressure (COP), and time-to-boundary (TTB) were measured during walking and single-leg stance (SLS).

RESULTS

During walking, compared to the healthy group, the varus alignment group showed lower peak force for the posterior heel (P = 0.012), lateral midfoot (P = 0.024) and hallux (P = 0.009). When the two sides were compared, the varus group exhibited a lower peak force in the anterior heel (P = 0.004) and hallux (P = 0.017) of the affected sides, the neutral (P = 0.043) and varus (P = 0.045) groups all showed higher medio-lateral COP of the unaffected sides, indicating the COP shifting laterally. In SLS test, the two MM groups demonstrated increased peak force of the third (P = 0.037) and fifth (P = 0.040) metatarsals compared to the healthy group, the peak force of the posterior heel were lower in the varus alignment group compared to the healthy group (P = 0.007) and the neutral alignment group (P = 0.008). And the TTB absolute value of medial-lateral direction of the two MM groups were lower than healthy controls (P = 0.029). The area under the receiver operating characteristic curve (AUC = 0.698, P = 0.016) suggested that peak force of posterior heel had good performance to discriminate varus alignment group from neutral alignment group.

CONCLUSION

MM injuries, especially with varus alignment, lead to significant changes in plantar pressure distribution and postural stability. These insights are clinically significant for designing early, biomechanically-informed rehabilitative strategies to optimize recovery and prevent further joint degeneration following MM injuries.

Coronal plane alignment changes do not affect outcome for total knee implant design with 3 degree varus joint line

BACKGROUND

Total knee arthroplasty (TKA) is a widely performed surgical intervention for symptomatic knee osteoarthritis (OA). However, the influence of coronal plane alignment on clinical outcomes remains unclear. This study evaluates whether alterations in the coronal plane alignment of the knee (CPAK) classification, using the same implant system, affect postoperative outcomes in patients undergoing robotic-assisted TKA.

METHODS

We conducted a retrospective review of 202 patients who underwent primary robotic-assisted TKA between 2019 and 2023 using NAVIO or CORI systems and Journey II implants. Patients were classified based on changes in CPAK classification and functional outcomes assessed using the Knee Society Score (KSS) and Knee Society Function Score (KSFS) at multiple postoperative time points. Statistical analyses compared outcomes between groups with changed and unchanged CPAK.

RESULTS

A total of 202 patients were included. Preoperative demographic characteristics were comparable between groups. Functional outcome scores at 6 weeks, 3 months, 6 months, and 12 months postoperatively showed no significant differences between the changed CPAK group and the unchanged CPAK group (p > 0.05 for all comparisons). Subgroup analyses further revealed no statistically significant disparities in functional outcomes based on the type or degree of CPAK changes.

CONCLUSION

Our findings suggest that changes in coronal plane alignment do not adversely affect functional outcomes following robotic-assisted TKA. This implies that alignment strategy may be less critical to patient satisfaction and functional recovery than previously assumed. Implant-induced alignment changes may contribute to comparable clinical outcomes and could be a key factor in patient recovery. Understanding the relationship between CPAK changes and clinical outcomes can inform best practices in knee arthroplasty, ultimately enhancing patient satisfaction and quality of life post-surgery.

Coronal Plane Alignment of the Knee (CPAK) distribution in a diverse Asian population: Influence of ethnicity, sex and bilaterality

Purpose

In total knee arthroplasty (TKA), it remains unclear which patients benefit from correction versus restoration of native knee alignment. The Coronal Plane Alignment of the Knee (CPAK) classification system was introduced in 2021 to describe native alignment, helping to characterise the effect of different TKA alignment techniques. This study aims to describe CPAK in an ethnically diverse population and characterise the relationship between CPAK and ethnicity, as well as the bilaterality of osteoarthritis and other patient factors.

Methods

503 primary TKAs were performed in a large tertiary institution in Singapore from 2014 to 2021. Pre-operative anteroposterior knee radiographs were collected for 441 procedures-all had ethnicity, age, sex and body mass index data. The medial proximal tibial angle (MPTA) and lateral distal femoral angle (LDFA) were measured with good inter-observer correlation. Knees were then classified into nine CPAK categories based on arithmetic hip-knee-ankle (aHKA) angle and joint line obliquity (JLO).

Results

77% of the cohort were apex-distal (CPAK 1, 2 and 3), and 59% were varus (CPAK 1, 4 and 7); 44% were CPAK 1 (varus + apex-distal). Chinese and Indian knees followed near-identical patterns: CPAK 1 (46%) > CPAK 2 (20%) > CPAK 4 (15%). Malay knees had significantly fewer CPAK 1 (p = 0.0183), with CPAK 1 (29%) ≈ CPAK 2 (29%) ≈ CPAK 4 (21%). Thirty-eight patients had bilateral TKA. Identical categories were recorded bilaterally in 45% of CPAK, 67% of JLO and 70% of aHKA. Bilateral TKA were more likely when knees were in valgus alignment than unilateral TKA (p = 0.00457).

Conclusion

Malay knees are less likely to be CPAK-1; this novel finding may explain ethnic differences in TKA outcomes described in the literature. Less than half of the bilateral knees had the same CPAK category bilaterally. The implications of this bilateral CPAK incongruence are unclear and require further study.

Level of Evidence

Level II, prospective cohort study.

Normative values of radiographic parameters in coronal plane lower limb alignment in a general Japanese population: A cross-sectional study in the Iwaki cohort

Purpose

The purpose of this study was to estimate normative values of radiographic parameters in lower limb alignment and investigate age-related changes in lower limb alignment in a general Japanese population.

Methods

A total of 1474 knees in 737 volunteers (307 men and 430 women) who participated in the Iwaki cohort study were enroled. Standing anterior-posterior radiographs were assessed using the Kellgren-Lawrence (KL) grading scale, with KL ≥Grade 2 defined as osteoarthritis (OA). Radiographic parameters measured included the hip-knee-ankle angle (HKAA), femorotibial angle (FTA), mechanical lateral distal femoral angle (mLDFA), medial proximal tibial angle (MPTA), joint line convergence angle (JLCA) and weight-bearing line ratio (WBLR). Normative values were estimated as the mean ± 2 standard deviations for all participants without knee OA (KOA) aged 18-39 years, and associations with age were analyzed.

Results

Normative values in overall young healthy participants were: HKAA, 1.8 ± 5.1°; FTA, 175.7 ± 6.5°; mLDFA, 86.4 ± 3.4°; MPTA, 85.8 ± 4.1°; JLCA, 1.2 ± 2.7° and WBLR, 39.7 ± 23.7%. The HKAA, FTA, MPTA and WBLR values differed significantly between sexes. In men without KOA, HKAA, FTA, MPTA and WBLR values correlated very weakly with age (r = -0.189 to 0.220). In contrast, only HKAA correlated very weakly with age in women without KOA (r = 0.096).

Conclusions

Estimated normative values of radiographic parameters in coronal plane lower limb alignment differed significantly between sexes. These data might be useful when considering the aetiology and therapeutic strategy for KOA.

Level of Evidence

Level II.

The relationship between spinopelvic alignment and knee osteoarthritis in female patients: A cross-sectional study

BackgroundThe spine, pelvis, and lower extremities move in the form of a kinematic chain.ObjectiveThis study aimed to evaluate the relationship between spinopelvic parameters and knee osteoarthritis.MethodsSixty-nine participants (50-70 years) were diagnosed with knee osteoarthritis: early-stage (n = 36) and late-stage (n = 33). Knee osteoarthritis severity was assessed using standing antero-posterior radiographs (Kellgren-Lawrence scores). A visual Analog Scale was used to evaluate knee and lumbar pain, the Western Ontario and McMaster Universities Osteoarthritis Index to evaluate knee joint function and disability, and the Oswestry Low Back Pain Disability Index to evaluate disability associated with lumbar pain. Lateral scoliosis radiographs were taken of all the study participants; pelvic incidence, pelvic tilt, sacral slope, lumbar lordosis, thoracic kyphosis, and sagittal vertical axis values were measured and recorded.ResultsMultivariate logistic regression analysis was performed to determine the independent risk factors associated with the clinical and radiological osteoarthritis severity as Body Mass Index, sagittal vertical axis and lumbopelvic mismatch increased. The sacral slope values were determined to be independently negatively correlated with the clinical osteoarthritis severity. However, no correlation was determined with the radiological severity.ConclusionIn this study, we determined that global sagittal imbalance and lumbopelvic mismatch are associated with advanced knee osteoarthritis. Although pelvic retroversion was not found to be correlated with the radiographic severity of osteoarthritis, it was found to be associated with poor functional results.

Knee alignment and patella shape are not associated with the persistence of patellofemoral pain

INTRODUCTION

Patellofemoral pain (PFP) is suggested as a precursor of patellofemoral osteoarthritis (PFOA) later in life. This hypothesis is based on shared risk factors for both diseases, such as deviating alignment parameters. In patients with PFOA, certain 2D alignment parameters and 3D shape variations are associated with the progression of PFOA. The relationship among alignment, shape, and PFP persistence remains unclear to date.

OBJECTIVE

To investigate the association between 2D alignment parameters, 3D bone shape variations, and PFP persistence.

METHODS

Questionnaire and magnetic resonance imaging (MRI) data from 64 patients between 14 and 40 years of age with PFP were selected from a case-control study. Participants who completed follow-up questionnaires at one or two years of follow-up were included. PFP persistence, measured using a 7-point Likert scale, was dichotomized. Structural abnormalities were scored using the MRI Osteoarthritis Knee Score (MOAKS), and alignment parameters were determined following standardized methods. The patellae were segmented from the MRI using a semi-automatic segmentation algorithm, and a 3D statistical shape model was created. Shape modes explaining at least 1% of total population variation were included. Regression analyses were performed to determine the association among baseline function (anterior knee pain scale (AKPS)), MOAKS features, alignment parameters, 3D patellar shape modes, and PFP persistence.

RESULTS

Fifty-five participants completed follow-up questionnaires and were included in the current analyses. Participants had a mean (standard deviation) age of 23.2 (6.8), and 58.2% were female. AKPS increased statistically significantly from 65.7 (10.6) at baseline to 75.9 (14.9) at follow-up. Nineteen patellar shape modes were included in the analyses, of which four showed a P-value <0.05; however, they were not statistically significant after applying Bonferroni correction. No associations were found among MOAKS, alignment parameters, shape modes, and PFP persistence in the adjusted models. Only AKPS at baseline was associated with pain severity at follow-up (β ​= ​-0.13, 95% confidence interval: -0.20; -0.07).

CONCLUSION

No statistically significant associations were found among structural abnormalities, 2D alignment, or 3D shape modes, and PFP persistence. Only worse AKPS at baseline was associated with persistent PFP, suggesting that baseline function might be a better predictor than structural abnormalities, alignment, or bone shape.

LEVEL OF EVIDENCE

III.

Measuring static and dynamic lower limb alignment in patients with advanced knee osteoarthritis using markerless motion capture

PURPOSE

Marked lower limb malalignment is associated with the progression of knee osteoarthritis (OA). Markerless motion capture is a computer-vision tool that can measure lower limb alignment throughout both static and dynamic tasks.

RESEARCH QUESTIONS

The primary objective of the study was to quantify static and dynamic lower limb alignment for patients diagnosed with advanced medial and lateral knee OA. This analysis also explored sex differences in alignment from the static and dynamic tasks. The secondary objective was to investigate if the mean knee adduction angle during quiet standing and the peak knee adduction angle during the first half of stance of gait were associated.

METHODS

Ninety-two patients (37 male, 55 female) diagnosed with advanced knee OA (83 with predominantly medial knee OA, and 9 with predominantly lateral knee OA) completed a quiet standing task and a gait task for markerless motion capture using Theia3D software. Two-way analysis of variance tests were used to investigate sex differences and unpaired t-tests were computed to compare knee OA groups.

RESULTS

Statistically significant differences in the knee adduction angle were found between medial and lateral knee OA groups during quiet standing (p < 0.001) and the first half of stance of gait (p < 0.0001). A strong correlation was found (Spearman's ρ = 0.86, p < 0.0001) in lower limb alignment between the static and gait tasks.

SIGNIFICANCE

These results show how markerless technology was able to quantify lower limb alignment and demonstrates potential for integration into clinic to assess musculoskeletal diseases.

Frontal plane mechanical leg alignment estimation from knee x-rays using deep learning

Objective

Lower limb malalignment can complicate symptoms and accelerate knee osteoarthritis (OA), necessitating consideration in study population selection. In this study, we develop and validate a deep learning model that classifies leg alignment as "normal" or "malaligned" from knee antero-posterior (AP)/postero-anterior (PA) radiographs alone, using an adjustable hip-knee-ankle (HKA) angle threshold.

Material and methods

We utilized 8878 digital radiographs, including 6181 AP/PA full-leg x-rays (LLRs) and 2697 AP/PA knee x-rays (2292 with positioning frame, 405 without). The model's evaluation involved two steps: In step 1, the model's predictions on knee images cropped from LLRs were compared against the ground truth from the original LLRs. In step 2, the model was tested on knee AP radiographs, using corresponding same-day LLRs as a proxy for ground truth.

Results

The model effectively classified alignment, with step one achieving sensitivity and specificity of 0.92 for a threshold of 7.5°, and 0.90 and 0.85 for 5°. For positioning frame images, step two showed a sensitivity of 0.85 and specificity of 0.81 for 7.5°, and 0.79 and 0.74 for 5°. For non-positioning frame images, sensitivity and specificity were 0.91 and 0.83 for 7.5°, and 0.9 and 0.86 for 5°.

Conclusion

The model developed in this study accurately classifies lower limb malalignment from AP/PA knee radiographs using adjustable thresholds, offering a practical alternative to LLRs. This can enhance the precision of study population selection and patient management.

Changes in spino-pelvis-lower extremity alignment in patients with knee osteoarthritis: a prospective radiographic study

PURPOSE

Osteoarthritis (OA) is a prevalent, debilitating ailment among the elderly. Humans need a correct sagittal spino-pelvis-lower extremity alignment to stand upright. Pathology in trunk or lower extremity section might disrupt this harmony, causing compensatory alterations in other segments. The aim of the present study was to evaluate spino-pelvis-lower extremity alignment and association among the various spino-pelvic, knee, and ankle radiological angles in patients with knee osteoarthritis (OA).

MATERIALS AND METHODS

This prospective study enrolled 70 adults over 50 years of age of either sex who complained of knee pain and met the American College of Rheumatology criteria for symptomatic OA of at least one knee. The radiological assessment comprised anteroposterior and lateral lower extremity full-length scans, as well as the Kellgren-Lawrence radiographic classification of OA. We measured hip, knee, ankle, and spino-pelvic angles using Horos software. We calculated descriptive statistics and linear correlation between continuous variables.

RESULTS

There was a significant association (p < 0.05) between age and the majority of the spino-pelvic, knee, and ankle angles and between age and severity of OA. Significant variables linked with 'SFA' include HKAA (p = 0.008), mLDFA (p < 0.001), TJLA, FS-TS, Cond-Plateau, and femoral bowing (p = 0.007). We found significant associations between 'PFA' and mMPTA (p = 0.005), Cond-Plateau (p = 0.005), Tibial Bowing (p = 0.003), and 'LL' with HKAA, mLDFA, FS-TS, and Cond-Plate. SSA was significantly associated with mLDFA, mMPTA, TJLA, Cond-Plateau, and HKAA; while, FI' was significantly associated with FS-TS, femoral bowing, and tibial bowing (p < 0.001). The variables 'SS' was substantially linked with TTA (p = 0.008), TT (p = 0.004), PP (< 0.001), GP (p < 0.001), and GT (p = 0.010). 'PI' was substantially linked to TT (p = 0.001), GP (p = 0.005), and GT (p = 0.042), and 'PT' to TT (p < 0.001) and GT (p = 0.012). 'SFA' and 'PFA' only correlated with TT (p = 0.012 and 0.010). Lower limb angles were significantly associated with TT, PP, GP, GT, mLDFA, and mMPTA (p = 0.031, p = 0.026, p = 0.009, p = 0.009, TT, GP, GT, p < 0.001). GP was the sole significant association for 'TJLA' (p = 0.016). 'FS-TS' substantially correlated with PP (p = 0.015), GP (p < 0.001), and GT (p < 0.001). "Femoral Bowing" was significantly linked to PP (p = 0.017), GP (p = 0.007), and GT (p < 0.001), and "Cond-Plateau" was significantly linked to GP (p = 0.002) and GT. "Tibial Bowing" was significantly linked to TTA (p < 0.001), TAS (p = 0.003), LDTA (p = 0.002), TC (p < 0.001), GP (p = 0.007), and GT (p < 0.001). Age, gender, BMI, and the severity of knee OA significantly influenced the association among these various angles.

CONCLUSION

Osteoarthritis of the knee disrupts the harmonious alignment of the spine and pelvis with the lower limbs, resulting in compensatory changes in the ankle and spine. The severity of knee osteoarthritis and the patient's gender, age, and BMI impact compensatory adaptations.

TRIAL REGISTRATION NUMBER AND DATE OF REGISTRATION

CTRI/2021/08/036088 [Registered on: 31/08/2021] - Trial Registered Prospectively.

Comparison of the clinical and radiological outcomes of Puddu and TomoFix plates for medial opening-wedge high tibial osteotomy: A two-year follow-up of a randomized controlled trial

PURPOSE

Opening-wedge high tibial osteotomy (OWHTO) requires fixation devices for stabilization of the osteotomy gap. The two most commonly used fixation devices are the Puddu and the TomoFix plates. Based on its design, each implant generates a characteristic stability profile. The aim of this randomized controlled trial (RCT) was to investigate the short-term clinical and radiological outcomes of OWHTO using the Puddu and TomoFix plating systems. We hypothesized that the TomoFix plate would achieve superior clinical and radiographic results compared to the Puddu plate.

METHODS

A total of 60 patients were randomly allocated to undergo OWHTO either using the Puddu plate or the TomoFix plate if conservative treatment failed with symptomatic medial compartment knee osteoarthritis (OA) stage I or II according to Ahlbäck classification, and varus malalignment. All patients underwent clinical and radiological assessment preoperatively, and at 3, 6, 12, and 24months postoperatively. Radiological measurement of the hip-knee-ankle (HKA) angle, and posterior tibial slope (PTS) was performed. Functional assessment was carried out using the Hospital for Special Surgery Knee-Rating Scale (HSS) and the Western Ontario McMaster Universities (WOMAC) Osteoarthritis Index. Patients were also evaluated for intraoperative and postoperative complications throughout the follow-up period.

RESULTS

The mean angular correction was 9.6±4°, and 10.5±4.8° in the Puddu and TomoFix groups, respectively (p=0.488). The mean PTS change was significantly higher in the Puddu group (3.4±1.1°) compared to the TomoFix group (0.8±0.7°) (p<0.001). There was a statistically significant improvement in the mean HSS and WOMAC in both groups until one year postoperatively. Neither HSS nor WOMAC showed a statistically significant difference between the Puddu and TomoFix groups at any time during the first two postoperative years. The overall complication rate was not significantly different between the Puddu and TomoFix groups. However, the TomoFix group demonstrated higher incidence of symptomatic hardware (23% vs. 3.3%) and removal of metalwork (17% vs. 0%) than the Puddu group (p=0.023 and 0.020, respectively).

CONCLUSION

This RCT suggests that the implant choice for OWHTO has no significant impact on functional outcomes during the first 2years postoperatively. While the Puddu plate was associated with an unintentional increase in the PTS during the surgery, both implants allowed coronal and sagittal plane corrections to be preserved postoperatively. The overall complication rates were similar, but the TomoFix required more material to be removed because it is more cumbersome. However, these results need to be confirmed on a larger scale.

LEVEL OF EVIDENCE

II; randomized controlled trial.

Coronal alignment does not enable to predict the degree of femoral and tibial torsion

Purpose

Malalignment of the lower extremity can affect one, two or all three anatomic planes. We hypothesized an influence between the malalignment of the coronal and axial planes.

Methods

A total of 356 lower extremities of 226 patients were included. Femoral and tibial torsion were assessed in computer tomographic scans while frontal plane alignment was measured in long-leg standing radiographs. The mechanical angles were for knee phenotyping according to the coronal plane alignment of the knee classification. The correlation between the coronal alignment and torsional profile was analyzed. The population was divided into three groups according to leg alignment (valgus, neutral, varus) and gender.

Results

As the coronal alignment changed from valgus to varus the tibial external torsion increased (r = 0.35; p < 0.001). Femoral internal torsion increased as well but only in the male subgroup (r = -0.34; p < 0.001). Both femoral internal torsion and tibial external torsion increased with higher mechanical lateral distal femoral angle (mLDFA) but were not related to mechanical medial proximal tibial angle. A distinct pattern of results concerning knee phenotypes in relation to femoral and tibial torsion was found.

Conclusion

Tibial torsion correlated with increasing varus alignment while both femoral and tibial torsion correlated with higher mLDFA, but the correlations were weak. Therefore, the coronal alignment does not enable to predict the degree of femoral and tibial torsion. This study demonstrates that an individual approach to each patient with lower limb malalignment is unavoidable.

Level of Evidence

Level III.

[Insoles in the treatment of pes planovalgus : A prospective, randomised, double-blind, placebo-controlled comparative trial of sensomotoric and supportive insoles]

BACKGROUND

In adults, flexible symptomatic flat foot is treated conservatively with supportive foot orthoses. Sensorimotor foot orthoses, however, are controversial due to insufficient data.

PURPOSE

Comparison of the effectiveness of sensorimotor and supportive foot orthoses in adults.

MATERIAL AND METHODS

In 73 patients, in addition to foot gymnastics, supportive, sensorimotor or placebo insoles were compared over 3 measurement points during 1 year as part of a double-blind, prospective, randomised placebo-controlled clinical trial using Numeric Rating-Scala, the Foot and Ankle Disability Index, as well as pedobarography and valgus index. The statistical analysis was performed using ANOVA with repeated measures.

RESULTS

The valgus index increased significantly with supportive foot orthoses. In the follow-up, the foot contact area was only significantly reduced with sensorimotor foot orthoses in static and dynamic measurements. Supportive foot orthoses led to a faster reduction in pain, but without reducing the contact area of the foot. There were no relevant differences in functionality.

CONCLUSIONS

The reduction of the contact surface in combination with sensorimotor foot orthoses shows the potential for muscular addressing of the flexible flat foot. There were no disadvantages compared to other treatments. Supportive foot orthoses led to a faster reduction in subjective complaints, but appear to weaken the muscles supporting the arch of the foot. In the longer term, consistent foot muscle training also appears to be effective, as wearing placebo foot orthoses also led to an improvement in subjective well-being without significant biomechanical changes.

Varus alignment of the hip and knee 2 years after anterior cruciate ligament injury is associated with medial tibiofemoral osteoarthritis 3 years later

Purpose

To investigate if hip and knee alignment assessed 2 years after anterior cruciate ligament (ACL) injury is associated with compartment-specific radiographic knee osteoarthritis (OA) 3 years later.

Methods

An exploratory analysis was conducted in the knee ACL, nonsurgical versus surgical treatment (KANON) trial (ISRCTN84752559); 115 subjects with acute ACL injury were assessed at the 2-year follow-up; full-limb images of the injured leg were acquired, and the neck-shaft angle (NSA) and hip-knee-ankle angle (HKA) were measured. At the 5-year follow-up, weight-bearing tibiofemoral and patellofemoral radiographs were obtained. Radiographs were graded according to the OA Research Society International Atlas and Radiographic OA was defined as approximating Kellgren & Lawrence grade 2 or worse. Analysis of covariance adjusting for sex, age, body mass index, randomization and partial meniscectomy recorded at the 2-year follow-up was performed.

Results

In patients who had developed medial tibiofemoral OA at the 5-year follow-up, the NSA and the HKA at the 2-year follow-up were smaller (NSA, mean difference = -4.6° [95% confidence interval {CI} -7.9° to -1.1°]; HKA, mean difference = -2.3° [95% CI -4.2° to -0.4°]). No association was observed between the NSA or HKA at the 2-year follow-up and lateral tibiofemoral OA, nor patellofemoral OA at the 5-year follow-up.

Conclusion

A smaller NSA and HKA angle of the ACL injured leg (i.e., more varus hip and varus knee alignment) 2 years after the injury was associated with medial tibiofemoral radiographic OA 3 years later.

Level of Evidence

Level II exploratory post hoc analysis of an RCT.

Machine learning for clustering and classification of early knee osteoarthritis using single-leg standing kinematics

Objective

Detection of early osteoarthritis (EOA) of the knee is crucial for effective management and improved outcomes. This study investigated the application of machine learning techniques to single-leg standing (SLS) kinematics to classify and predict EOA. (1) To identify distinct groups based on SLS kinematic patterns using unsupervised learning algorithms, (2) to develop supervised learning models to predict EOA status, and (3) to identify the most influential kinematic variables associated with EOA.

Methods

Total 43 manufacturing workers (86 legs) aged 40-70 years were evaluated. The participants were categorized using an Early Osteoarthritis Questionnaire. Single-leg standing kinematics was captured using 2D video analysis to assess the horizontal displacement of six key anatomical points (trunk, pelvis, femur, knee, lower leg, and ankle) in the frontal plane. K-means clustering was used for unsupervised learning, whereas six supervised machine learning algorithms were trained and validated for EOA classification.

Results

In our machine learning models, we used 258 data points derived from three repeated measurements per participant. K-means clustering revealed three distinct groups based on SLS kinematics and demographic characteristics. The random forest algorithm achieved the highest classification accuracy (area under the receiver operating characteristic curve = 1.000, accuracy = 1.000) in distinguishing between individuals with and without EOA. Pelvic and ankle horizontal displacements were identified as the most influential predictors of EOA classification.

Conclusions

Machine learning analysis of SLS kinematics shows significant potential for the early detection of knee osteoarthritis. Identification of key kinematic predictors, particularly pelvic and ankle movements, provides new insights into targeted interventions and screening protocols for rehabilitation.

Knee osteotomy combined with meniscal allograft transplantation versus knee osteotomy alone in patients with unicompartmental knee osteoarthritis: a prospective double-blind randomised controlled trial protocol

INTRODUCTION

Knee osteotomy combined with meniscal allograft transplantation (MAT) showed promising results to treat unicompartmental knee osteoarthritis (OA) secondary to meniscal deficiency and knee malalignment. However, there is still no high-level evidence to demonstrate whether the combination of these two treatments is superior to osteotomy alone.

METHODS AND ANALYSIS

52 patients with unicompartmental knee OA Kellgren-Lawrence grade ≤3 secondary to meniscal deficiency and knee malalignment (aged 20-60 years) are randomised to undergo knee osteotomy associated with MAT or knee osteotomy alone in a 1:1 ratio. The primary outcome is the International Knee Documentation Committee (IKDC) subjective score at 12 months. The secondary outcomes are the IKDC subjective score at 1, 3 and 6 months, the Western Ontario and McMaster Universities Osteoarthritis Index score, the Knee Injury and Osteoarthritis Outcome Score, the Visual Analogue Scale, the EuroQol Visual Analogue Scale, the Tegner Activity Level Scale, objective parameters (transpatellar circumference, suprapatellar circumference and range of motion), patient expectation on treatment efficacy and patient satisfaction at 1, 3, 6 and 12 months. Radiographs are performed at baseline and at 1-, 6- and 12-month follow-ups and magnetic resonance evaluations at baseline and at 12 months. Biomechanical assessment is performed through gait analysis before surgery and at 12 months, investigating motion data, biomechanical parameters and muscle activation through electromyography. In addition, to detect early joint environment changes and potential MAT effects in protecting the articular surface providing a better knee homeostasis, biological markers of cartilage turnover and inflammation obtained from synovial fluid, serum and urine are evaluated at baseline and at 24 hours, 1-, 3-, 6- and 12-month follow-ups.

ETHICS AND DISSEMINATION

The study protocol has been approved by Emilia Romagna's Ethics Committee (CE-AVEC), Bologna, Italy. Written informed consent is obtained from all participants. Findings of this study will be disseminated through peer-reviewed publications and conference presentations.

PROTOCOL VERSION

March 2023.

TRIAL REGISTRATION NUMBER

NCT05840887.

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.

EUROVISCO Consensus Guidelines for the Use of Hyaluronic Acid Viscosupplementation in Knee Osteoarthritis Based on Patient Characteristics

OBJECTIVES

Viscosupplementation with hyaluronic acid (HA) is a commonly used intra-articular treatment for osteoarthritis (OA). We performed a Delphi consensus process to formulate guidelines for the use of intra-articular hyaluronic acid (IAHA) knee injection according to the patient's characteristics.

METHODS

The EUROVISCO group consists of 12 members who had expertise in clinical and/or research in the field of OA and IAHA treatment. This group drafted issues through an iterative process and subsequently voted according to a Delphi process on their level of agreement (LoA) on these recommendations. The scores were pooled to generate a median agreement score for each recommendation. The strength of the recommendation (SOR) was classified as strong if the median agreement score was ≥8. The level of consensus (LOC) was also obtained. The level of evidence was given for each recommendation.

RESULTS

A total of 34 statements were evaluated by the expert group. A unanimous or high LoA was obtained in 16. IAHA can be considered irrespective of the age in patients with symptomatic knee OA. It can be used in patients with diabetes and/or moderate to severe obesity. It can also be used in knee OA patients with a history of gout, meniscocalcinosis and with mild-to-moderate varus/valgus malalignment. The group recommended against the use of VS in pregnant women and in OA flare.

CONCLUSION

In summary, the working group provided strong recommendations for the use of IAHA injection that will facilitate individualized treatment decision algorithms in the management of knee OA.

HKA-Net: clinically-adapted deep learning for automated measurement of hip-knee-ankle angle on lower limb radiography for knee osteoarthritis assessment

BACKGROUND

Accurate measurement of the hip-knee-ankle (HKA) angle is essential for informed clinical decision-making in the management of knee osteoarthritis (OA). Knee OA is commonly associated with varus deformity, where the alignment of the knee shifts medially, leading to increased stress and deterioration of the medial compartment. The HKA angle, which quantifies this alignment, is a critical indicator of the severity of varus deformity and helps guide treatment strategies, including corrective surgeries. Current manual methods are labor-intensive, time-consuming, and prone to inter-observer variability. Developing an automated model for HKA angle measurement is challenging due to the elaborate process of generating handcrafted anatomical landmarks, which is more labor-intensive than the actual measurement. This study aims to develop a ResNet-based deep learning model that predicts the HKA angle without requiring explicit anatomical landmark annotations and to assess its accuracy and efficiency compared to conventional manual methods.

METHODS

We developed a deep learning model based on the variants of the ResNet architecture to process lower limb radiographs and predict HKA angles without explicit landmark annotations. The classification performance for the four stages of varus deformity (stage I: 0°-10°, stage II: 10°-20°, stage III: > 20°, others: genu valgum or normal alignment) was also evaluated. The model was trained and validated using a retrospective cohort of 300 knee OA patients (Kellgren-Lawrence grade 3 or higher), with horizontal flip augmentation applied to double the dataset to 600 samples, followed by fivefold cross-validation. An extended temporal validation was conducted on a separate cohort of 50 knee OA patients. The model's accuracy was assessed by calculating the mean absolute error between predicted and actual HKA angles. Additionally, the classification of varus deformity stages was conducted to evaluate the model's ability to provide clinically relevant categorizations. Time efficiency was compared between the automated model and manual measurements performed by an experienced orthopedic surgeon.

RESULTS

The ResNet-50 model achieved a bias of - 0.025° with a standard deviation of 1.422° in the retrospective cohort and a bias of - 0.008° with a standard deviation of 1.677° in the temporal validation cohort. Using the ResNet-152 model, it accurately classified the four stages of varus deformity with weighted F1-score of 0.878 and 0.859 in the retrospective and temporal validation cohorts, respectively. The automated model was 126.7 times faster than manual measurements, reducing the total time from 49.8 min to 23.6 sec for the temporal validation cohort.

CONCLUSIONS

The proposed ResNet-based model provides an efficient and accurate method for measuring HKA angles and classifying varus deformity stages without the need for extensive landmark annotations. Its high accuracy and significant improvement in time efficiency make it a valuable tool for clinical practice, potentially enhancing decision-making and workflow efficiency in the management of knee OA.

Comparison of the asymmetries in foot posture, gait and plantar pressure between patients with unilateral and bilateral knee osteoarthritis based on a cross-sectional study

This study aimed to observe the characteristics of foot posture asymmetry and abnormal gait in patients with unilateral and bilateral knee osteoarthritis (KOA) and to explore the association between foot posture asymmetry, abnormal gait and the clinical symptoms and severity of KOA. Sixty patients with KOA were allocated as follows: unilateral group (UG; n = 30) and bilateral group (BG; n = 30). We accessed foot posture, foot posture asymmetry, gait and plantar pressure parameters and symmetry index, clinical symptom-related scores and disease severity, and investigated the relationship between these variables. The results showed that the overall percentage of asymmetry and severe asymmetry in foot posture were lower in BG than in UG. There was substantial asymmetry in many gait indicators within the two groups, but no significant differences were observed between the two groups. Moreover, foot posture asymmetry, multiple gait and plantar pressure parameters and symmetry indices were closely related to clinical symptoms and disease severity. In conclusion, both unilateral and bilateral KOA patients have foot posture asymmetry and gait asymmetry, but the foot posture asymmetry of the former is more severe than that of the latter. Intervention for this population should treat simultaneously both knee joints. The evaluation and monitoring of foot posture asymmetry, gait and plantar pressure parameters and symmetry indices can provide a more comprehensive and scientific basis for the prevention and treatment of KOA.

Estimating elbow loading conditions through the motion behaviors of subchondral bone density during joint movements

Evaluating complicated stress across the elbow under joint motion remains difficult. Here, we aimed to evaluate the distribution of the subchondral bone density in the normal elbow bones and further characterize their spatial relationships during elbow motion to estimate the loading stress across the articular surface using three-dimensional computed tomography bone models. The normal elbow joint exhibited a consistent distribution pattern of subchondral bone density. High-density regions were distributed in the capitellum and posterior humeral trochlea, sagittal ridge of the ulnar trochlear notch and ulnar-volar side of the radial head. Motion analyses revealed that the high-density regions proximate with elbow flexion with forearm pronation in the radiocapitellar joint and in the fully extended position in the ulnohumeral joint. This reasonably reflects the stress acting on the joint surface under actual loading conditions. These findings suggest that daily activities involving lifting or carrying objects in these positions are stress-prone activities.

Relationship between preoperative and discharge evaluations in patients receiving around-the-knee osteotomy

[Purpose] This study aimed to determine the relationship between preoperative and discharge assessments in patients undergoing around-the-knee osteotomy. [Participants and Methods] We enrolled patients admitted to our hospital who underwent around-the-knee osteotomy. We measured knee joint range of motion, pain numeric rating scale, pain catastrophizing scale, hospital anxiety and depression scale, and 10-m walk time were measured preoperatively and before discharge. Pre-post comparisons and correlation testing were performed. [Results] A total of 18 patients were analyzed. Resting and exercise pain numeric rating scale, knee flexion and extension range of motion, and pain catastrophizing scale were significantly better during discharge. A significant correlation was observed between the preoperative pain catastrophizing scale total score and 10-m walking time, knee flexion and extension range of motion, pain catastrophizing scale total score, and hospital anxiety and depression scale-depression subscale preoperatively. [Conclusion] Appropriate postoperative rehabilitation after around-the-knee osteotomy improved physical function and cognitive/psychological evaluation at discharge. The correlation between the preoperative pain catastrophizing scale total score and 10-m walking time at discharge suggests that the prolonged walking pain that occurred preoperatively may have affected the cognitive and psychological evaluation of pain.

Population-based in silico modeling of anatomical shape variation of the knee and its impact on joint loading in knee osteoarthritis

Anatomical knee joint features and osteoarthritis (OA) severity are associated, however confirming causals link to altered knee loading is challenging. This study leverages statistical shape models (SSM) to investigate the relationship between joint shape/alignment and knee loading during gait in knee OA (KOA) patients to understand their contribution to elevated medial knee loading in OA. Musculoskeletal (MSK) models were created for the mean as well as the first eight SSM principal modes of variation (-3,-2,-1, +1, +2, +3 standard deviations for each mode) and used as input to a MSK modeling framework. Using an identical KOA gait pattern (i.e., joint kinematics and ground reaction forces), we ran simulations for each MSK model and evaluated medial compartment loading magnitude and contact distribution at the instant of first and second peak of knee joint loading. An increase in external rotation, posterior tibia translation and a decrease in medial joint space and medial femoral condylar size predisposed the medial compartment knee joint to overloading during gait. This was coupled with an anterior and medial shift in contact location with increasing external rotated tibial position and increasing posterior tibial translation with respect to the femur. Next, results also highlighted a posterior shift of the medial compartment loading location with decreasing medial joint space. This study provides important population-based insights on how knee shape and alignment predispose individuals with KOA to elevated medial compartmental knee loading. This information can be crucial in assessing the risk for medial KOA development and progression.

Fixed-bearing medial unicompartmental knee arthroplasty restores pre-arthritic coronal alignment and achieves satisfactory functional outcomes: a retrospective study

PURPOSE

This study aimed to (1) analyze the Coronal Plane Alignment of the Knee (CPAK) classification in patients undergoing unicompartmental knee arthroplasty (UKA), (2) assess whether UKA can restore pre-arthritic coronal alignment by utilizing the arithmetic hip-knee-ankle angle (aHKA), and (3) evaluate the relationship between patient-reported outcome measures (PROMs) and postoperative alignment following UKA.

METHODS

We retrospectively analyzed 152 consecutive patients who underwent fixed-bearing medial UKA. A radiological analysis was conducted using an EOS imaging system. Postoperative alignment was classified as neutral (varus ≤ 3°), mild varus (3° < varus ≤ 7°), or marked varus (varus > 7°) based on the mechanical hip-knee-ankle angle (mHKA). The aHKA was calculated and the CPAK classification was used to categorize knee phenotypes. The PROMs were obtained both before and after the surgery.

RESULTS

A total of 152 knees from 113 patients were included with a mean two-year follow-up. The mean difference between the postoperative mHKA and the estimated aHKA was 0.80° (90% CI 0.35 to 1.24; P = 0.003). Postoperatively, 63 (41.45%) of the 152 knees were in neutral group, 54 (35.53%) mild varus, and 35 (23.03%) marked varus. The neutrally aligned cohort did not exhibit significantly higher scores in range of motion, VAS, HSS, WOMAC, or FJS-12 scores compared to the mild or marked varus cohort (P = 0.205, 0.118, 0.076, 0.140, and 0.788, respectively) during the short-term follow-up.

CONCLUSION

Non-robotically assisted, fixed-bearing medial UKA can restore pre-arthritic coronal alignment and achieve satisfactory PROMs. Fixed-bearing medial UKA aims to restore the pre-arthritic alignment rather than achieving neutral mechanical alignment.

Windswept deformity of the knee: prevalence and predictive factors in osteoarthritic and healthy populations

Aims

This study examined windswept deformity (WSD) of the knee, comparing prevalence and contributing factors in healthy and osteoarthritic (OA) cohorts.

Methods

A case-control radiological study was undertaken comparing 500 healthy knees (250 adults) with a consecutive sample of 710 OA knees (355 adults) undergoing bilateral total knee arthroplasty. The mechanical hip-knee-ankle angle (mHKA), medial proximal tibial angle (MPTA), and lateral distal femoral angle (LDFA) were determined for each knee, and the arithmetic hip-knee-ankle angle (aHKA), joint line obliquity, and Coronal Plane Alignment of the Knee (CPAK) types were calculated. WSD was defined as a varus mHKA of < -2° in one limb and a valgus mHKA of > 2° in the contralateral limb. The primary outcome was the proportional difference in WSD prevalence between healthy and OA groups. Secondary outcomes were the proportional difference in WSD prevalence between constitutional varus and valgus CPAK types, and to explore associations between predefined variables and WSD within the OA group.

Results

WSD was more prevalent in the OA group compared to the healthy group (7.9% vs 0.4%; p < 0.001, relative risk (RR) 19.8). There was a significant difference in means and variance between the mHKA of the healthy and OA groups (mean -1.3° (SD 2.3°) vs mean -3.8°(SD 6.6°) respectively; p < 0.001). No significant differences existed in MPTA and LDFA between the groups, with a minimal difference in aHKA (mean -0.9° healthy vs -0.5° OA; p < 0.001). Backwards logistic regression identified meniscectomy, rheumatoid arthritis, and osteotomy as predictors of WSD (odds ratio (OR) 4.1 (95% CI 1.7 to 10.0), p = 0.002; OR 11.9 (95% CI 1.3 to 89.3); p = 0.016; OR 41.6 (95% CI 5.4 to 432.9), p ≤ 0.001, respectively).

Conclusion

This study found a 20-fold greater prevalence of WSD in OA populations. The development of WSD is associated with meniscectomy, rheumatoid arthritis, and osteotomy. These findings support WSD being mostly an acquired condition following skeletal maturity.

Unraveling the genetic association between knee osteoarthritis and hallux deformities

OBJECTIVE

Knee osteoarthritis (KOA), hallux valgus (HV) and hallux rigidus (HR) are common musculoskeletal problems of the lower extremities. However, their underlying causal relationships are unclear. This study attempts to clarify the cause-and-effect relationship between KOA and the two common hallux deformities (HV and HR).

DESIGN

The summary-level statistics for KOA, HV, and HR were collected from genome-wide association studies (GWAS). The causal analysis of KOA on HV or HR was carried out using two-sample Mendelian randomization (MR). In order to assess the robustness of the MR results, sensitivity analyses were performed. In addition, multivariable MR (MVMR) was implemented to assess the influence of KOA in causation as well as calibrate the effect of anthropometric characteristics. Supplementary backward MR analysis was conducted to determine the causal effect of hallux diseases on KOA.

RESULTS

The univariable analysis indicated that KOA has a causative influence on HR (odds ratio [OR] = 1.29, 95% confidence interval [CI] = 1.18-1.41, P = 2.25E-8) and HV (OR = 1.43, 95% CI = 1.21-1.68, P = 2.76E-5). In the backward MR analyses, hallux deformities did not appear to be the cause of KOA. In the MVMR analysis, after jointly adjusting for the effects of waist-to-hip ratio (WHR), waist circumference (WC), hip circumference (HC) and BMI, the causal impact of KOA on HV and HR remained robust.

CONCLUSION

In this study, the genetic causality between KOA and increased risk of hallux deformities (HV and HR) is established, which can provide evidence-based recommendations for reducing the incidence of hallux deformities in KOA patients. Further high-level studies are warranted to validate the associations and explore its broader implications.

A Novel Minimally Invasive Surgical Technique for Eight-Plate Hemiepiphysiodesis: Description and Evaluation

Background: Temporary hemiepiphysiodesis with tension band plates or eight-plates is a common surgical procedure to treat malalignment of the lower limb axis in skeletally immature patients. The objective of this study was to compare a new minimally invasive surgical procedure with the conventional procedure and evaluate its safety and effectiveness in order to reduce the risk of hypertrophic scarring, which may cause functional impairment as well as cosmetic issues. Methods: Sixty-five growth plates of either the femur or the tibia were evaluated in 33 patients treated for genu valgum or varum between 2010 and 2017. Each growth plate was considered an individual case. The modified procedure was used in 17 cases and the conventional procedure in 48 cases. The modified surgical procedure is characterized by an 8 mm incision and preparation of the epi-periosteal layer, in which the eight-plate is positioned via a guide-wire. Positioning and implantation are controlled via fluoroscopy. Skin incision length, duration of surgery, revision rate, achievement of a defined correction goal, and correction rate were analyzed. Results: Using the minimally invasive procedure, the mean skin incision length (23.94 ± 10.18 mm vs. 8.75 ± 2.14 mm, p < 0.001) could be significantly reduced. No significant difference was found in regard to the duration of surgery, revision rate, achievement of the correction goal or correction rate. Conclusions: The minimally invasive procedure results in a reduction in incision length without significant impact on the duration of surgery, revision rate, achievement of correction goal or correction rate. Consequently, the modified procedure can be regarded as equally as effective and safe as the conventional procedure.

Dual Femoral and Tibial Osteotomies for Large Varus and Valgus Deformities

Aim and background

The aim of this study is to evaluate the outcomes of acute correction of large varus and valgus deformities with simultaneous distal femoral and tibial osteotomies. Acute correction of large coronal plane deformities is complex and if done incorrectly, can lead to problems like non-union, soft tissue problems, and joint line obliquity.

Materials and methods

Radiographic, clinical, and patient-reported outcomes are analysed through a retrospective series of 21 extremities in 18 consecutive patients with coexisting femoral and tibial deformities who underwent concurrent distal femoral and proximal tibial osteotomies with acute coronal plane correction and internal fixation.

Results

The mean mechanical axis deviation (MAD) correction was 56 mm for varus deformities (n = 13) and 45 mm for valgus deformities (n = 8) with an overall mean correction of the femoral tibial angle of 15° per extremity. The accuracy of correction was 92.9% compared to the goal MAD. Two patients had peri-incisional cellulitis that resolved with antibiotics. There was no incidence of non-union, deep vein thrombosis, compartment syndrome, deep infection, or peripheral nerve palsy. Patient-reported outcome scores had clinically meaningful improvements in pain, function, and mental health.

Conclusion

Acute correction of large coronal plane deformities can be accurately and safely performed with simultaneous distal femoral and proximal tibial osteotomies with internal fixation.

Clinical significance

This study highlights a safe method to accurately correct large coronal plane deformities in the lower extremity.

How to cite this article

Wallace SJ, Jaime MK, Fragomen AT, et al. Dual Femoral and Tibial Osteotomies for Large Varus and Valgus Deformities. Strategies Trauma Limb Reconstr 2024;19(3):135-140.

Knee Osteoarthritis

Knee osteoarthritis (OA) typically presents with joint pain that is exacerbated by use and alleviated with rest. There is relatively brief, self-limited morning stiffness and absence of constitutional symptoms. Overweight and obesity are the most important modifiable risk factors. Although pharmacologic and nonpharmacologic interventions are generally effective at alleviating pain and improving physical function, they do not fundamentally reverse the pathologic and radiographic process of knee OA. As the severity of disease increases, the magnitude of pain and functional impairment intensifies. Surgical intervention should be pursued to relieve pain and restore functionality only when nonpharmacologic approaches and pharmacologic agents fail to control pain.

Mid-Term Clinical and Radiological Changes in the Ankle Joint in Varus Knee Osteoarthritis Following Total Knee Arthroplasty

Background/Objectives: In patients with varus knee osteoarthritis, compensatory changes occur in the foot and ankle joints to compensate for the varus deformity of the knee. The aim of the study was to investigate the changes in the ankle of patients whose knee alignment was corrected with total knee arthroplasty (TKA) and to explore the clinical implications of these findings. Methods: In this retrospective observational study, we analyzed 204 knees of 179 patients who had regular follow-ups out of 431 patients who underwent TKA for varus knee osteoarthritis between January 2019 and July 2021. Patient demographics, body mass index, follow-up time, and radiographs were studied. The hip-knee-ankle (HKA) angle, joint line convergence angle (JLCA), talar tilt (TT) angle, ground talar dome (GT) angle, ground tibia plafond (GP) angle, and the American Orthopaedic Foot & Ankle Society (AOFAS) score were assessed preoperatively and at the last follow-up. Results: A total of 204 knees of 179 patients with a mean follow-up time of 32.50 ± 6.68 months were evaluated. It was found that the change in the HKA had a positive effect on the AOFAS score and a negative effect on the TT, GT, and GP angles. While the clinical score improved in 82 patients, it worsened in 8 patients. The age difference between the groups whose AOFAS score improved and worsened was statistically significant. Conclusions: The correction of the varus malalignment in the knee was shown to also improve the compensatory valgus in the foot and ankle over the mid-term, with a statistically significant improvement in the patients' clinical ankle scores.

Outcomes of Medial Closing-Wedge Distal Femoral Osteotomy for Femoral- and Tibial-Based Valgus Deformity

BACKGROUND

In carefully selected patients with an arthritic valgus knee, distal femoral osteotomy (DFO) can improve symptoms at medium- to long-term follow-up, reducing osteoarthritis progression. To date, there is no clear evidence in the current literature regarding the role of postoperative joint line obliquity (JLO) in valgus deformity correction.

PURPOSE

To assess the clinical and radiological outcomes of medial closing-wedge DFO (MCW-DFO) for the treatment of valgus knees, considering both tibial- and femoral-based deformities, as well as to verify the efficacy and safety of MCW-DFO according to JLO boundaries (≤4°).

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

A retrospective analysis was conducted on a cohort of patients with valgus knees. Patients were divided into 2 groups: femoral-based valgus (FB-V) and tibial-based valgus (TB-V). Knee radiographs were collected before surgery and at the last follow-up. The clinical outcome was evaluated through several validated scores (International Knee Documentation Committee, Knee Society Score, Knee injury and Osteoarthritis Outcome Score, Tegner, Numeric Rating Scale, Crosby-Insall).

RESULTS

A total of 30 patients (34 knees) with a mean age of 49.3 ± 9.1 years were included in the study. The overall mean follow-up was 9.4 ± 5.9 years. The mean preoperative hip-knee-ankle angle was 187.6°± 3.3° (range, 181.5°-191°) and the postoperative angle was 180°± 3.1° (range, 176°-185°). Most postoperative JLOs were within the safe zone of ≤4° in both groups (the postoperative JLO was >4° in 4 patients in the TB-V group and 1 patient in the FB-V group), although FB-V knees exhibited significant superior JLO correction (postoperative JLO in the TB-V group: mean, 4.0°± 2.5° [P = .1]; postoperative JLO in the FB-V group: mean, 2.4°± 1.4° [P = .5]). Significant improvements in all clinical scores were observed in both groups (P < .01). Additionally, the severity of the osteoarthritis did not worsen at the last follow-up.

CONCLUSION

MCW-DFO is an effective procedure for treating pathological valgus knees, regardless of the site of the deformity. Both FB-V and TB-V groups showed comparable improvements in the clinical scores, development of osteoarthritis, and the restoration of a neutral mechanical axis. Notably, FB-V knees achieved more JLO correction compared with the TB-V ones.

Assessment of lower limb alignment: supine weight-bearing CT scanograms compared with a standing full-length radiograph

PURPOSE

We identified limb misalignment by applying personalized axial force while the limb was in a supine position to mimic a standing posture. This study aimed to confirm the accuracy of evaluating lower limb alignment using supine weight-bearing CT scanograms.

METHODS

We prospectively compared measurements of the weight-bearing line ratio (WBL), hip-knee-ankle (HKA) angle, and joint convergence angle (JLCA) in 46 sets of supine weight-bearing CT scanograms with those obtained from full-length standing anteroposterior lower extremity radiographs. We achieved the weight-bearing CT scanograms by applying six different levels of axial force: zero, 1/5 of body weight, 2/5 of body weight, 3/5 of body weight, 4/5 of body weight, and full body weight. We assessed the impact of age, body mass index, HKA, and JLCA on the observed mechanical axis deviation differences between the two methods.

RESULT

The average absolute difference between standing radiographs and supine CT scanograms was 4.32% for the WBL ratio (p < 0.05), 1.25° for HKA (p < 0.05), and 0.46 for JLCA (p < 0.05). The mean absolute difference was minimal when applying full body weight axial pressure during CT scanograms (p > 0.05). Age, body mass index, HKA, and JLCA had no effect on the deviation in the mechanical axis measurements obtained through supine weight-bearing CT scanograms with full body weight.

CONCLUSION

No significant differences were found in assessing lower limb alignment between standing radiographs and supine weight-bearing CT scanograms with full body weight. Weight-bearing CT scanograms prove to be a valuable method for assessing lower limb alignment while in a supine position.

A Simple Surgical Technique for Correction of Varus Deformity in Advanced Osteoarthritis of Knees by Medial Femoral Condylar Sliding Osteotomy-Description of Procedure and short term Outcome-A Prospective Study

Background

Advanced osteoarthritis of knees with varus deformity consists of attenuation of lateral structures with contracture of the posteromedial structures and formation of medial osteophytes. The conventional step-wise medial and posteromedial release with measured resection may sometimes hinder achievement of perfectly balanced flexion and extension gaps with maintenance of flexion stability, without the use of a constrained prosthesis. Medial femoral epicondylar sliding osteotomy tailors the balancing to the need of the kinematics of the native knee and precludes the use of a constrained implant.

Methods

15 patients with Ahlbäck Grades III through V osteoarthritic changes at Howrah Orthopaedic Hospital were included in a prospective cohort case series with a minimum period of follow-up being 12 months. Physical examination, clinical questionnaire and radiographic evaluation were done post-operatively for objectification by functional Knee Society and Oxford Knee Scores respectively.

Results and Analysis

The mean post-operative femorotibial angulation ameliorated to a value of 3.73 ± 1.58° from 18.67 ± 4.2° in the pre-operative stage. The mean overall Range of Motion of operated knee was 109.87 ± 6.86° with no residual frontal laxity and/or laxity in the coronal plane. The mean amount of resection of tibial plateau in patients with severe varus deformity was kept to a minimum, 6.56 mm from the least deficient portion of the lateral condyle. There were no complications as regards component loosening and/or surgical-site infection.

Conclusion

The main objective of balancing a severely varus-afflicted knee is to preserve as much of the Medial Collateral Ligament as possible, to retain its check rein function and not jeopardise the stability. This is ensured by distalisation and posteriorizing the medial epicondyle by an incomplete osteotomy in addition to modest tibial resection fetching a non-isometric point of knee flexion. All osteotomies united by bony union and restoration of kinematic alignment. The limitation of this study however includes the lack of long-term results, such as late instability and polyethylene wear.

Cartilage thickness in the medial compartment of the knee joint evaluated by MRI three-dimensional analysis correlates with weight-bearing line ratio and joint line convergence angle

PURPOSE

The correlation between cartilage thickness evaluated by 3D MRI and knee alignment has not been elucidated. The study's purpose was to retrospectively verify whether average cartilage thickness calculated by the automatic MRI 3D analysis system for each subregion was correlated with knee alignment.

METHODS

A total of 53 patients underwent medial meniscus repair or high tibial osteotomy for medial knee osteoarthritis. Cartilage thickness was automatically calculated using 3D MRI software. Knee alignment, weight-bearing line ratio (WBLR), joint line convergence angle (JLCA), medial proximal tibial angle (MPTA), and lateral distal femoral angle (LDFA) were calculated on a weight-bearing long-leg radiograph using digital planning software. The association between knee alignment and the average cartilage thickness at 18 subregions in the medial femoral condyle (MFC) and medial tibial plateau (MTP) was evaluated using Spearman's rank correlation coefficient.

RESULTS

Cartilage thickness of the MFC had moderately positive correlations with WBLR at four subregions and weak correlations at two subregions. Cartilage thickness of the MTP had moderately positive correlations with WBLR at four subregions. Cartilage thickness of the MFC had moderately negative correlations with JLCA at six subregions. Cartilage thickness of the MTP had moderately negative correlations with JLCA at four subregions and a weak correlation at one subregion. Conversely, cartilage thickness had weak correlations with MPTA or LDFA.

CONCLUSIONS

In knees with pathological conditions in the medial compartment, cartilage thicknesses by 3D MRI had positive correlations with WBLR and JLCA at almost all subregions of the MFC and at the anterior-middle and central-external of the MTP. Treatment strategies should be considered in light of these regions.

LEVEL OF EVIDENCE

Cross-sectional study (diagnosis); Level of evidence, 2.

A synoptic literature review of animal models for investigating the biomechanics of knee osteoarthritis

Osteoarthritis (OA) is a common chronic disease largely driven by mechanical factors, causing significant health and economic burdens worldwide. Early detection is challenging, making animal models a key tool for studying its onset and mechanically-relevant pathogenesis. This review evaluate current use of preclinical in vivo models and progressive measurement techniques for analysing biomechanical factors in the specific context of the clinical OA phenotypes. It categorizes preclinical in vivo models into naturally occurring, genetically modified, chemically-induced, surgically-induced, and non-invasive types, linking each to clinical phenotypes like chronic pain, inflammation, and mechanical overload. Specifically, we discriminate between mechanical and biological factors, give a new explanation of the mechanical overload OA phenotype and propose that it should be further subcategorized into two subtypes, post-traumatic and chronic overloading OA. This review then summarises the representative models and tools in biomechanical studies of OA. We highlight and identify how to develop a mechanical model without inflammatory sequelae and how to induce OA without significant experimental trauma and so enable the detection of changes indicative of early-stage OA in the absence of such sequelae. We propose that the most popular post-traumatic OA biomechanical models are not representative of all types of mechanical overloading OA and, in particular, identify a deficiency of current rodent models to represent the chronic overloading OA phenotype without requiring intraarticular surgery. We therefore pinpoint well standardized and reproducible chronic overloading models that are being developed to enable the study of early OA changes in non-trauma related, slowly-progressive OA. In particular, non-invasive models (repetitive small compression loading model and exercise model) and an extra-articular surgical model (osteotomy) are attractive ways to present the chronic natural course of primary OA. Use of these models and quantitative mechanical behaviour tools such as gait analysis and non-invasive imaging techniques show great promise in understanding the mechanical aspects of the onset and progression of OA in the context of chronic knee joint overloading. Further development of these models and the advanced characterisation tools will enable better replication of the human chronic overloading OA phenotype and thus facilitate mechanically-driven clinical questions to be answered.

Radiological Assessment of Coronal Plane Alignment of the Knee Phenotypes in the Romanian Population

Background: The Coronal Plane Alignment of the Knee (CPAK) classification system has been developed as a comprehensive framework delineating nine coronal plane phenotypes, based on arithmetic hip-knee angle (aHKA) and joint line obliquity (JLO). Our study aimed to assess the prevalence of knee phenotypes in the Romanian population using the CPAK classification, encompassing both osteoarthritic and healthy cohorts. Methods: We conducted an observational cross-sectional study, analyzing data from 500 knees with osteoarthritis and 500 healthy knees that met the inclusion criteria. Demographic data were collected, and radiological parameters including lateral distal femoral angle (LDFA), medial proximal tibial angle (MPTA), aHKA, and JLO were measured. Knee phenotypes were categorized using the CPAK classification. Results: In the osteoarthritic cohort, the most prevalent CPAK phenotype was type I (42.4%), characterized by varus alignment and an apex distal joint. Conversely, in the healthy population, CPAK type II, indicating neutral alignment and an apex distal joint, was the most prevalent phenotype (39.0%). CPAK types VII, VIII, and IX were rare. Conclusions: Our findings demonstrate similarities in knee phenotypes compared to other populations, with some minor differences and particularities. The CPAK classification proves to be a valuable tool in assessing knee tyalignment.

Severity of knee osteoarthritis does not affect clinical outcomes following proximal fibular osteotomy - A systematic review and pooled analysis

Background & aims

Knee osteoarthritis (KOA) is a progressive degenerative disease of chronic nature. The mainstay of surgical management for KOA would be total knee arthroplasty. Joint preserving options like High Tibial Osteotomy (HTO) and Proximal Fibular Osteotomy (PFO) have been offered as an inexpensive option by knee preservation surgeons. Current literature on PFO outcomes lack of clarity for specific indications for offering PFO based on degree of severity of KOA. Therefore, this systematic review aims to critically evaluate clinical and radiological outcomes of PFO stratified by severity of KOA.

Methods

PubMed, Scopus, CINAHL and Google Scholar databases were searched. Eligible studies included those published up till August 2023, with 271 studies obtained. After duplicate removal, title-abstract screening, and a full text screen based on inclusion and exclusion criteria, 11 papers were included. 46 papers were further identified from snowballing of 7 existing systematic reviews, with 2 additional papers subsequently included.

Results

13 included articles analysed 788 knees. Our study found that indications based on KL grading of KOA do not seem to differ in terms of post-operative clinical outcomes (VAS score) and radiological measures also found that hip knee alignment was improved regardless of KL grading of KOA. Additionally, the most common post-operative complication reported was deep peroneal nerve palsy.

Conclusion

PFO is a viable knee joint preserving surgery for medial compartment KOA, however given the high risk for complications reported in the literature, surgeons should pay close attention to the neuroanatomical landmarks and techniques to avoid neurovascular injury.

The significance of frontal plane static alignment in anticipating dynamic knee moment among transtibial prosthesis users: A cross-sectional study

BACKGROUND

In the process of transtibial prosthetic fitting, alignment is the process of positioning the prosthetic foot relative to the residual limb. Changes in frontal plane alignment can impact knee moments during walking, which can either cause or, when aligned properly, prevent injuries. However, clinical evaluation of dynamic knee moments is challenging, limiting prosthetists' insights into dynamic joint loading. Typically, knee joint loading is assessed in static stance using the knee moment arm as a proxy for subsequent dynamic alignment. It remains uncertain if static alignment accurately represents actual dynamics during walking.

RESEARCH QUESTION

Is the frontal knee moment arm in stance predictive for the knee moment arm and external knee adduction moment during gait in transtibial bone-anchored prosthesis users?

METHODS

In this cross-sectional study, twenty-seven unilateral transtibial bone-anchored prosthesis users underwent data acquisition on the M-Gait instrumented treadmill. Static and dynamic measurements were conducted, and knee moment arm and external knee adduction moment were calculated. Pearson's correlation and linear regression analyses were performed to examine relationships between static and dynamic knee moment arms and external knee adduction moments.

RESULTS

The static knee moment arm showed significant associations with dynamic knee moment arm at the ground reaction force peaks (First: r=0.60, r2=35%, p<0.001; Second: r=0.62, r2=38%, p=0.001) and knee adduction moment (First: r=0.42, r2=17%, p=0.030; Second: r=0.59, r2=35%, p=0.001). A 1 mm between-subject difference in static knee moment arm corresponded, on average, with a 0.9% difference in knee adduction moment at the first peak and a 1.5% difference at the second peak of the ground reaction force.

SIGNIFICANCE

While static alignment is important to optimize adduction moments during stance it may only partly mitigate excessive moments during gait. The fair correlation and limited percentage of explained variance underscores the importance of dynamic alignment in optimizing the body's dynamic load during walking.

Intraoperative radiographic analysis and adjustment of the optimal position of plate in high tibial osteotomy

BACKGROUND

When high tibial osteotomy is performed for genu varus deformity, it is not easy to determine the accurate placement of the plate.

PURPOSE

To determine a simple way to assess the position of the plate, to provide more effective mechanical support and to reduce the risk of implant rupture and vascular injury.

MATERIAL AND METHODS

Two human anatomical marks, the patellar ligament and semimembranosus, were connected and divided into four parts to identify points Ⅰ, Ⅱ, and Ⅲ. These points determined the areas for Tomofix placement: anterior, anterolateral, and lateral. Simulated internal fixation placed hole B of Tomofix at points Ⅰ (anterior), Ⅱ (anterolateral), and Ⅲ (lateral). We analyzed the pointing direction of the locking screws in Tomofix holes on MRI to assess potential injury risk to the popliteal neurovascular bundle.

RESULTS

In the X-ray: holes B and C appeared as the plate in the anterior, only hole C appeared as the plate in the anterolateral, and none of the holes appeared as the plate in the lateral. In the general view of the sawbones, the screw pointed towards the popliteal neurovascular bundle when the plate was in the anterior.

CONCLUSION

If a small number of holes on the plate is visible under fluoroscopy, then several lateral positions of the plate can be obtained; the direction of the screw tunnel tends to deviate from the popliteal neurovascular bundle with the posterior position of the plate.

Modulation of early osteoarthritis by tibiofemoral re-alignment in sheep

OBJECTIVE

To investigate whether tibiofemoral alignment influences early knee osteoarthritis (OA). We hypothesized that varus overload exacerbates early degenerative osteochondral changes, and that valgus underload diminishes early OA.

METHOD

Normal, over- and underload were induced by altering alignment via high tibial osteotomy in adult sheep (n = 8 each). Simultaneously, OA was induced by partial medial anterior meniscectomy. At 6 weeks postoperatively, OA was examined in five individual subregions of the medial tibial plateau using Kellgren-Lawrence grading, quantification of macroscopic OA, semiquantitative histopathological OA and immunohistochemical type-II collagen, ADAMTS-5, and MMP-13 scoring, biochemical determination of DNA and proteoglycan contents, and micro-computed tomographic evaluation of the subchondral bone.

RESULTS

Multivariate analyses revealed that OA cartilaginous changes had a temporal priority over subchondral bone changes. Underload inhibited early cartilage degeneration in a characteristic topographic pattern (P ≥ 0.0983 vs. normal), in particular below the meniscal damage, avoided alterations of the subarticular spongiosa (P ≥ 0.162 vs. normal), and prevented the disturbance of otherwise normal osteochondral correlations. Overload induced early alterations of the subchondral bone plate microstructure towards osteopenia, including significantly decreased percent bone volume and increased bone surface-to-volume ratio (all P ≤ 0.0359 vs. normal).

CONCLUSION

The data provide high-resolution evidence that tibiofemoral alignment modulates early OA induced by a medial meniscus injury in adult sheep. Since underload inhibits early OA, these data also support the clinical value of strategies to reduce the load in an affected knee compartment to possibly decelerate structural OA progression.

Knees with isolated lateral compartment osteoarthritis show a substantial variability in functional knee phenotypes with demographic-specific variations: Phenotypic analysis of 305 knees

BACKGROUND

The primary aim of this study was to assess and describe the phenotypic variation in the coronal plane of knees affected by isolated lateral compartment osteoarthritis (OA). The secondary aim was to investigate the potential gender-specific and age-related differences in functional knee phenotypes among knees with isolated lateral compartment OA.

METHODS

A comprehensive classification system was used to categorize 305 knees with isolated lateral compartment OA based on their mechanical hip-knee-ankle angle (HKA), femoral mechanical angle (FMA), and tibial mechanical angle (TMA). The phenotypic variation of functional knee phenotypes was assessed for the entire cohort and stratified by gender and age category.

RESULTS

Among knees with isolated lateral compartment OA, a total of 60 distinct functional knee phenotypes were identified, with phenotype VALHKA6°NEUFMA0°VALTMA3° being the most prevalent (10.8 %). Gender-specific differences were evident, with females exhibiting significantly greater valgus alignment in both mean HKA and TMA values compared with males (HKA: -6.4° vs. -5.4°, respectively; P = 0.02 and TMA 94.4° vs. 89.0°, respectively; P = 0.005). Age-related variations included younger patients predominantly displaying femoral deformities, while older patients primarily exhibited isolated tibial- or combined femoral and tibial deformities.

CONCLUSIONS

There is a broad variation of functional knee phenotypes among knees affected by isolated lateral compartment OA, with gender-specific and age-related differences. Recognizing this inherent phenotypic diversity during preoperative planning may facilitate the implementation of tailored approaches that account for the unique characteristics and bony deformities of the individual knee.

The Effect of Lower Limb Alignment on Tibiofemoral Joint Contact Biomechanics after Medial Meniscus Posterior Root Repair: A Finite-Element Analysis

INTRODUCTION

The purpose of this study was to determine how variations in lower limb alignment affect tibiofemoral joint contact biomechanics in the setting of medial meniscus posterior root tear (MMPRT) and associated root repair.

METHODS

A finite-element model of an intact knee joint was developed. Limb alignments ranging from 4° valgus to 8° varus were simulated under a 1,000 N compression load applied to the femoral head. For the intact, MMPRT, and root repair conditions, the peak contact pressure (PCP), total contact area, mean and maximum local contact pressure (LCP) elevation, and total area of LCP elevation of the medial tibiofemoral compartment were quantified.

RESULTS

The PCP and total contact area of the medial compartment in the intact knee increased from 2.43 MPa and 361 mm 2 at 4° valgus to 9.09 MPa and 508 mm 2 at 8° of varus. Compared with the intact state, in the MMPRT condition, medial compartment PCP was greater and the total contact area smaller for all alignment conditions. Root repair roughly restored PCPs in the medial compartment; however, this ability was compromised in knees with increasing varus alignment. Specifically, elevations in PCP relative to the intact state increased with increasing varus, as did the total contact area with LCP elevation. After root repair, medial compartment PCP remained elevated above the intact state at all degrees tested, ranging from 0.05 MPa at 4° valgus to 0.27 MPa at 8° of varus, with overall PCP values increasing from 2.48 to 9.09 MPa. For varus alignment greater than 4°, root repair failed to reduce the total contact area with LCP elevation relative to the MMPRT state.

DISCUSSION

Greater PCPs and areas of LCP elevation in varus knees may reduce the clinical effectiveness of root repair in delaying or preventing the development of tibiofemoral osteoarthritis.

Unicompartmental knee arthroplasty vs high tibial osteotomy for knee osteoarthritis: A comparison of clinical and radiological outcomes

BACKGROUND

Unicompartmental knee arthroplasty (UKA) and high tibial osteotomy (HTO) are well-established operative interventions in the treatment of knee osteoarthritis. However, which intervention is more beneficial to patients with knee osteoarthritis remains unknown and a topic of much debate. Simultaneously, there is a paucity of research assessing the relationship between radiographic parameters of knee joint alignment and patient-reported clinical outcomes, preoperatively and following HTO or UKA.

AIM

To compare UKAs and HTOs as interventions for medial-compartment knee osteoarthritis: Examining differences in clinical outcome and investigating the relationship of joint alignment with respect to this.

METHODS

This longitudinal observational study assessed a total of 42 patients that had undergone UKA (n = 23) and HTO (n = 19) to treat medial compartment knee osteoarthritis. Patient-reported outcome measures (PROMs) were collected to evaluate clinical outcome. These included two disease-specific (Knee Injury and Osteoarthritis Outcome Score, Oxford Knee Score) and two generic (EQ-5D-5L, Short Form-12) PROMs. The radiographic parameters of knee alignment assessed were the: Hip-knee-ankle angle, mechanical axis deviation and angle of Mikulicz line.

RESULTS

Statistical analyses demonstrated significant (P < 0.001), preoperative to postoperative, improvements in the PROM scores of both groups. There were, however, no significant inter-group differences in the postoperative PROM scores of the UKA and HTO group. Several significant correlations associated a more distolaterally angled Mikulicz line with worse knee function and overall health preoperatively (P < 0.05). Postoperatively, two clusters of significant correlations were observed between the disease-specific PROM scores and knee joint alignment parameters (hip-knee-ankle angle, mechanical axis deviation) within the HTO group; yet no such associations were observed within the UKA group.

CONCLUSION

UKAs and HTOs are both efficacious operations that provide a comparable degree of clinical benefit to patients with medial compartment knee osteoarthritis. Clinical outcome has a limited association with radiographic parameters of knee joint alignment postoperatively; however, a more distolaterally angled Mikulicz line appears associated with worse knee function/health-related quality of life preoperatively.

Preoperative Hindfoot Alignment and Outcomes After High Tibial Osteotomy for Varus Knee Osteoarthritis: We Walk on Our Heel, Not Our Ankle

UPDATE

This article was updated on May 15, 2024 because of previous errors, which were discovered after the preliminary version of the article was posted online. On page 898, in the section entitled "Materials and Methods," the sentence that had read "The WBL ratio of the knee joint was defined as the point where the GA or MA passed through the width of the tibia and intersected a line from the center of the femoral head to the center of the calcaneus (for the GA) or talus (for the MA), with the medial edge defined as 0% and the lateral edge as 100%." now reads "The WBL ratio of the knee joint was defined as the point where the GA or MA passed through the width of the tibia and intersected a line from the center of the femoral head to the lowest point of the calcaneus (for the GA) or the center of the talus (for the MA), with the medial edge defined as 0% and the lateral edge as 100%." Likewise, in the legend for Figure 3 on page 899, the sentence that had read "Depiction of the ground mechanical axis (GA), defined as the line (represented by the solid red line) from the center of the femoral head to the ground reaction point at the center of the calcaneus, passing lateral to the traditional mechanical axis (MA; represented by the dashed red line)." now reads "Depiction of the ground mechanical axis (GA), defined as the line (represented by the solid red line) from the center of the femoral head to the ground reaction point at the lowest point of the calcaneus, passing lateral to the traditional mechanical axis (MA; represented by the dashed red line)." Finally, on page 903, "HKA" was changed to "HKA angle" in Table III.

BACKGROUND

The hip-to-calcaneus axis, previously known as the ground mechanical axis (GA), ideally passes through the center of the knee joint in the native knee. The aim of this study was to elucidate, with use of hip-to-calcaneus radiographs, changes in knee and hindfoot alignment and changes in outcomes following high tibial osteotomy (HTO).

METHODS

We reviewed the records for 128 patients who underwent HTO between 2018 and 2020. Patients were stratified into 2 groups, a hindfoot valgus group (n = 94) and a hindfoot varus group (n = 34), on the basis of their preoperative hindfoot alignment. The hindfoot alignment was evaluated with use of the hindfoot alignment angle (HAA). To evaluate lower-limb alignment, full-length standing posteroanterior hip-to-calcaneus radiographs were utilized to measure 4 radiographic parameters preoperatively and 2 years postoperatively: the hip-knee-ankle (HKA) angle, hip-knee-calcaneus (HKC) angle, and the weight-bearing line (WBL) ratios of the mechanical axis (MA) and GA.

RESULTS

The mean HAA improved significantly from 5.1° valgus preoperatively to 1.9° valgus postoperatively in the hindfoot valgus group (p < 0.001). In contrast, in the hindfoot varus group, the HAA showed no meaningful improvement in the coronal alignment of the hindfoot following HTO (p = 0.236). The postoperative mean HKC angle in the hindfoot varus group was 2° more varus than that in the hindfoot valgus group (1.0° versus 3.0°; p = 0.001), and the GA in the hindfoot varus group passed across the knee 8.0% more medially than that in the hindfoot valgus group (55% versus 63% from the most medial to the most lateral part of the tibial plateau). The hindfoot varus group had worse postoperative clinical outcomes than the hindfoot valgus group in terms of the mean Knee injury and Osteoarthritis Outcome Score for pain and American Orthopaedic Foot & Ankle Society Ankle-Hindfoot Score.

CONCLUSIONS

Although our findings did not provide sufficient evidence to establish clinically relevant differences between the groups, they indicated that the group with a preoperative fixed hindfoot varus deformity had a higher rate of undercorrection and worse clinical outcomes, especially pain, following HTO. Therefore, modification of the procedure to shift the GA more laterally may be required for these patients.

LEVEL OF EVIDENCE

Prognostic Level III . See Instructions for Authors for a complete description of levels of evidence.

Analysis of cartilage loading and injury correlation in knee varus deformity

Knee varus (KV) deformity leads to abnormal forces in the different compartments of the joint cavity and abnormal mechanical loading thus leading to knee osteoarthritis (KOA). This study used computer-aided design to create 3-dimensional simulation models of KOA with varying varus angles to analyze stress distribution within the knee joint cavity using finite element analysis for different varus KOA models and to compare intra-articular loads among these models. Additionally, we developed a cartilage loading model of static KV deformity to correlate with dynamic clinical cases of cartilage injury. Different KV angle models were accurately simulated with computer-aided design, and the KV angles were divided into (0°, 3°, 6°, 9°, 12°, 15°, and 18°) 7 knee models, and then processed with finite element software, and the Von-Mises stress distribution and peak values of the cartilage of the femoral condyles, medial tibial plateau, and lateral plateau were obtained by simulating the human body weight in axial loading while performing the static extension position. Finally, intraoperative endoscopy visualization of cartilage injuries in clinical cases corresponding to KV deformity subgroups was combined to find cartilage loading and injury correlations. With increasing varus angle, there was a significant increase in lower limb mechanical axial inward excursion and peak Von-Mises stress in the medial interstitial compartment. Analysis of patients' clinical data demonstrated a significant correlation between varus deformity angle and cartilage damage in the knee, medial plateau, and patellofemoral intercompartment. Larger varus deformity angles could be associated with higher medial cartilage stress loads and increased cartilage damage in the corresponding peak stress area. When the varus angle exceeds 6°, there is an increased risk of cartilage damage, emphasizing the importance of early surgical correction to prevent further deformity and restore knee function.

The association of folate deficiency with clinical and radiological severity of knee osteoarthritis

CONTEXT

Folate deficiency is often observed in patients with inflammatory diseases, raising questions about its role in knee osteoarthritis (OA) progression.

OBJECTIVES

This study aimed to assess the association of folate deficiency with the clinical and radiological severity of knee OA.

METHODS

A prospective cross-sectional study was conducted from January 1, 2019 to January 1, 2020. Primary knee OA patients referred to orthopedic clinics in Zabol, Iran were included. Radiographic severity was gauged utilizing the Kellgren-Lawrence (KL) classification. For clinical severity, patients completed the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) questionnaire. IBM SPSS v.27 facilitated the statistical analysis.

RESULTS

Forty-nine knee OA patients, averaging 67.45±13.44 years in age, were analyzed. Spearman correlation analysis revealed a negative correlation between folate levels and both WOMAC and KL scores. The correlation was stronger between folate and KL score (Spearman correlation coefficient: -0.75) than between folate and WOMAC total score (Spearman correlation coefficient: -0.46). Additionally, a significantly higher KL score was observed in patients with folate deficiency (p=0.004).

CONCLUSIONS

Our study highlights a significant correlation between folate deficiency and increased severity of OA, which is evident in radiological and clinical assessments. These findings suggest that folate plays a key role in OA pathogenesis and could be a modifiable factor in its management.