Biomechanical strategies implemented to compensate for mild leg length discrepancy during gait

Impact of mild leg length discrepancy on pelvic alignment and gait compensation in children

BACKGROUND

Leg length discrepancy (LLD) is common in children and often leads to pelvic lateral tilt as a primary gait deviation. While children rarely report low back pain, prolonged LLD can induce lasting changes in lumbar spine biomechanics, potentially resulting in future back issues. To mitigate the effects of LLD, children often employ various compensatory mechanisms. However, the degree of LLD that significantly impacts gait remains unclear.

RESEARCH QUESTION

This study aims to identify gait deviations in children and adolescents with mild LLD and examine the relationship between LLD severity and lower limb compensatory strategies.

METHODS

Fifty-one children and adolescents (mean age 12.6 years, SD = 2.5) with mild LLD ranging from 0.0 to 3.0 cm were enrolled. Exclusion criteria included neurological involvement, scoliosis, syndromes, and lower extremity joint contractures. Pelvic motion and gait compensations were evaluated across three groups: LLD 0-1 cm, LLD 1-2 cm, LLD 2-3 cm Correlations between gait parameters and LLD were assessed.

RESULTS

Pelvic lateral tilt showed significant correlations with LLD severity. Kinematic analyses revealed significant joint adaptations on the long leg side, leading to functional shortening, particularly in the 2-3 cm group, which displayed multiple and clear compensations. Notably, only ankle dorsiflexion on the long side significantly correlated with LLD.

SIGNIFICANCE

In cases of mild LLD, pelvic adaptations include lateral tilt, counterbalanced by lowering the longer leg. In absence of ankle contractures, individuals tend to avoid lengthening the shorter leg through toe walking, as it requires greater muscular effort. These adaptive strategies correlate with LLD severity, suggesting that even mild discrepancies may contribute to overuse injuries affecting the spine and longer limb. This study highlights the importance of recognizing and addressing mild LLD in relation to symptoms associated with pelvic tilt and ankle issues on the long leg.

Radiographic severity of knee osteoarthritis in adult spinal deformity: the effect on rod fracture after long spinal fusion in deformity correction

BACKGROUND CONTEXT

Instrumentation failure, notably rod fracture (RF), may occur even after ideal spinal deformity correction in adult spinal deformity (ASD). As RF is the major reason behind a revision surgery, various risk factors of RF are reported in literature, including pedicle subtraction osteotomy (PSO) technique itself. However, whether hip and knee joint diseases serve as another risk factor for RF remains unexplored.

PURPOSE

To investigate the effects of lower-extremity joint diseases on RF in ASD patients who underwent deformity correction through long-segment fixation with PSO.

STUDY DESIGN

Retrospective study.

PATIENT SAMPLE

About 96 consecutive ASD patients (mean age, 71.2 years) who underwent deformity correction through PSO and long-segment fixation from T10 to S1 between 2008 and 2019 were included. Those with radiographic data less than 2 years were excluded.

OUTCOME MEASURES

RF was confirmed on radiograph, computed tomography (CT) and bone scan or SPECT images. Coronal and sagittal spinopelvic parameters, lower-extremity osteoarthritis (OA) parameters and clinical outcomes (Oswestry Disability Index [ODI] and Visual Analog Scale [VAS]) were analyzed.

METHODS

Radiographic measurements were performed at preoperative, postoperative, and last follow-up visits. Patients were divided into 2 groups: non-RF (n=60) and RF (n=36). Radiographic factors were assessed, correlations between parameters were examined, and multivariate logistic regression analysis was performed to evaluate risk factors for RF.

RESULTS

Structural and functional leg length discrepancies (LLDs), pelvic obliquity (PO), and the differences of mechanical axis (MAD) between both extremities had significantly differed between the groups (p<.05). The between-knee differences in the extent of OA, clinically significant MAD and PO, and the incidences of both structural and functional LLD were significantly greater in the RF group than in the non-RF group (p<.05). On correlation analysis, PO was not correlated with coronal radiographic parameters but was correlated with structural and functional LLDs and MAD (p<.05). Logistic analysis revealed that the difference in OA grade between the knee joints, functional LLD, and preoperative lower extremity surgery were significantly associated with RF (p<.05).

CONCLUSION

ASD in the elderly often presents alongside degenerative changes in the lower-extremities, and even with ideal spinal deformity correction, RF may still occur if preexisting joint pathologies are not resolved. In the deformity correction of ASD, it is essential that we not only pursue the restoration of spinopelvic harmony, but also apply perioperative measures for lower-extremity degenerative joint diseases.

Floating Knee Arthrodesis After Periprosthetic Knee Infection: A Multi-Center Study

BACKGROUND

Knee arthrodesis is a means of avoiding above-knee amputation after a periprosthetic joint infection (PJI). The objective of this study was to analyze the results of floating knee arthrodesis in patients who had a history of a periprosthetic knee infection and to perform an external validation of the Baeza-Ortega scale. The analysis consisted of determining reinfection rates, functional results, and the survival of arthrodesis.

METHODS

There were 86 patients who had undergone floating knee arthrodesis in cases of PJI who were retrospectively included in the study. The operations were performed between 2012 and 2022 at three different referral centers for complex bone and joint infections in Spain. In addition to being evaluated clinically, analytically, and radiographically, the patients were assessed functionally with the Baeza-Ortega scale, which had been previously validated. At a mean follow-up of 4 years (range, 1 to 9), 13 patients suffered reinfection (15%) and 29% of patients experienced complications with an average of 42 months until a complication appeared.

RESULTS

The recurrence of infection was not observed to be significantly affected by sex (P = 0.13), age (P = 0.1), or the type of surgery previously undergone (P = 0.17), nor was the McPherson Host Grade (P = 0.4) observed to have a significant effect. Patients who had a McPherson Limb Grade 3 were more likely to suffer reinfection than those with a McPherson Limb Grade 2 (P = 0.036). There were 45 patients (53%) who were fully evaluated and scored. For 16 patients (35%), the results were evaluated as excellent, for 22 (48%) acceptable, for six (14%) low, and for one (3%) poor. There was a significant correlation between patient satisfaction and functional outcomes (P = 0.0006).

CONCLUSIONS

The arthrodesis nail without bone-bone fusion is an effective and safe procedure for patients who have a recurrent PJI, providing satisfactory functional results when a knee prosthesis revision cannot be performed.

Updates in the Management of Leg Length Discrepancy: A Systematic Review

The aim of this study is to comprehensively investigate the recent literature on the management of leg length discrepancy (LLD). A thorough search of pertinent databases was done in order to find studies that satisfied the requirements for inclusion. A thorough search of PubMed, Web of Science, Scopus, and Science Direct was conducted to find pertinent literature. Rayyan Qatar Computing Research Institute (QRCI, Ar Rayyan, Qatar) was utilized during the whole operation. Eight studies, including a total of 345 patients, were included in our data, and 206 (59.7%) of them were males. Percutaneous epiphysiodesis was the surgical intervention of choice in four studies. LLD can be effectively corrected by temporary and permanent epiphysiodesis. One study reported the incidence of angular deformities following temporary epiphysiodesis. Circumferential periosteal and dual tension-band plating significantly reduced LLD, but reported the incidence of an "over-shoot" in some patients. Bilateral motion control shoes and orthotic insole both were found to improve the patient's gait and trunk symmetry, evidenced by longer and faster steps, reduced ground impact at heel strike, and lower peak plantar pressure in both limbs. Our findings confirm that no inferences about the superiority of a particular management approach for the treatment of LLD can be made. The poor quality of the studies shows that more randomized control trials and prospective studies on the subject are required.

The Effect of Leg Length Discrepancy on Paraspinal Muscles Activation Using Surface Electromyography

OBJECTIVE

The aim of the study is to assess the effects of leg length discrepancy on paraspinal muscle activity and kinematic variables during gait.

DESIGN

Thirty-nine healthy participants aged 5-12 yrs performed the 10-m walk test using the surface electromyography and G-walk sensor for the following conditions: (1) non-leg length discrepancy condition (leg length discrepancy 0 cm) and (2) leg length discrepancy condition with an insole on the right leg at three different heights (leg length discrepancy 0.5 cm, 1.0 cm, and 1.5 cm). The root mean square was normalized using maximal voluntary contraction and reference voluntary contraction methods (RMS_MVC and RMS_ref) and compared between the sides.

RESULTS

The mean RMS_MVC of the 12th thoracic erector spinae on the right side was significantly higher at a leg length discrepancy 0.5 cm and 1 cm. Regarding the 3rd lumbar multifidus, the mean RMS_MVC on the right side was significantly higher at a leg length discrepancy 1.5 cm. The mean RMS_ref exhibited similar patterns. Pelvic obliquity and rotation showed asymmetry at a leg length discrepancy 1.5 cm compared with a leg length discrepancy 0 cm.

CONCLUSIONS

A small leg length discrepancy significantly affected the asymmetric hyperactivation of the 3rd lumbar multifidus and 12th thoracic erector spinae muscles during gait. Considering the action of these muscles, asymmetric hyperactivation might result in rotation and bending of the lumbar spine and the bending of the thoracolumbar spine.

Impact of prior spinal fusion surgery on complications and functional outcomes following total hip arthroplasty: an updated systematic review and meta-analysis

PURPOSE

This study aimed to compare the complication rates and functional outcomes between patients with and without a history of spinal fusion undergoing THA.

METHODS

A systematic search was conducted across PubMed, EMBASE, Scopus, and Cochrane databases. Studies that compared adults with and without a history of spinal fusion after primary THA were included. The methodological quality of the studies was evaluated using MINORS criteria. Meta-analyses were performed utilizing mean differences (MD), standardized mean differences (SMD), and odds ratios (OR), along with 95% confidence intervals (CI).

RESULTS

Seventeen studies involving 1,789,356 patients (31,786 in the SF group and 1,757,570 in the Non-SF group) were analyzed. The spinal fusion group exhibited significantly higher rates of dislocation (OR 2.50, 95% CI 1.78-3.52), periprosthetic fracture (OR 1.96, 95% CI 1.39-2.77), overall complications (OR 1.73, 95% CI 1.10-2.71), and revision rates (OR 1.86, 95% CI 1.74-1.99). Furthermore, within the first three months, there was an increased risk of dislocation (OR 4.38, 95% CI 1.36-14.14) and revisions (OR 3.87, 95% CI 1.63-9.18). Longer spinal fusions were significantly associated with a higher risk of dislocations (OR 0.62, 95% CI 0.53-0.71). Additionally, prior spinal fusion was linked to higher levels of pain (SMD 0.11, 95% CI 0.02-0.19) and poorer functional outcomes (MD - 0.09, 95% CI - 0.18 to - 0.00).

CONCLUSIONS

Patients with a history of spinal fusion undergoing THA exhibit increased complication rates, higher levels of pain, and greater functional limitations than those without prior fusion. These findings have significant clinical implications for optimizing perioperative care in high-risk patient populations.

Influence of reduced passive ankle dorsiflexion range of motion on lower limb kinetics and stiffness during gait

BACKGROUND

The ankle dorsiflexion range of motion (ADF-ROM) during single support phase allows elastic energy storage in the calcaneal tendon, contributing to advance the body forward. Reduced ADF-ROM may influence lower limb kinetics and stiffness.

RESEARCH QUESTION

What is the influence of reduced passive ADF-ROM on lower limb internal moments and stiffness during gait?

METHODS

Thirty-two participants, classified into two groups according to passive ADF-ROM (smaller than 10° and greater than 15°), were submitted to gait assessment at self-selected speed with a force platform and a three-dimensional motion analysis system. Statistical parametrical mapping (SPM) analyses were used to compare the lower limbs' internal moments between groups. Independent t-tests analyzed the differences between groups on lower limb stiffness during gait.

RESULTS

The lower ADF-ROM group had greater knee flexor moment (terminal stance and push-off), greater ankle abductor (i.e., shank internal rotator) moment in terminal stance and greater knee internal rotator moment in mid to terminal stance. The lower ADF-ROM group also had higher lower limb stiffness during gait.

SIGNIFICANCE

Individuals with reduced passive ADF-ROM had greater lower limb stiffness and adopted a gait pattern with increased knee and ankle moments, suggesting increased loading at these joints.

Floating Knee Arthrodesis After Prosthetic Knee Infection: A Report of 48 Cases

BACKGROUND

Knee arthrodesis is a means of avoiding above-knee amputation after a prosthetic joint infection (PJI). The objective of this study was to analyze the results of floating knee arthrodesis in patients who had a history of aprosthetic knee infection. The analysis consisted of determining reinfection rates, functional results, and the survival of arthrodesis.

METHODS

There were 48 patients who underwent a cemented floating knee arthrodesis in cases of PJI retrospectively included in the study, having been operated on between 2012 and 2020. In addition to being evaluated clinically, analytically, and radiographically, the patients were assessed functionally by means of a newly-created scale.

RESULTS

At a mean follow-up of 4 years (1 year to 9 years), 7 patients suffered reinfection (14.6%). The recurrence of infection was not observed to be significantly affected by sex (P = .16), age(P = .09), or the type of surgery previously undergone (P = .18), nor was the McPherson Host Grade (P = .4) observed to have a significant effect. Patients who had a McPherson Limb Grade 3 were more likely to suffer reinfection than those with a McPherson Limb Grade 2 (P = .034). There were 26 patients (54%)fully evaluated and scored on the Knee Arthrodesis Functional Scale(BAOR). For 11 patients (42%), the results were evaluated as excellent, for 11 (42%) acceptable, for 3 (12%) low, and for 1(4%) poor.

CONCLUSION

The arthrodesis nail is an effective and safe procedure for patients who have a recurrent PJI, providing an effective alternative when the criteria for a new revision total knee arthroplasty are not met.

Leg length discrepancy before total knee arthroplasty is associated with increased complications and earlier time to revision

INTRODUCTION

Leg length discrepancy (LLD) following total knee arthroplasty (TKA) is a common complaint, leading to decreased patient satisfaction. However, the effect of LLD diagnosis prior to TKA on outcomes and complications is not well defined. Thus, this study aimed to assess the effects that LLD has on rates of falls and implant complications, length of stay and readmissions, and implant survivorship following TKA.

METHODS

A retrospective review of a private insurance claims database was conducted from 2010 to 2021. All cases of TKA and those with a diagnosis of leg length discrepancy were identified. Patients undergoing TKA with a diagnosis of LLD were matched to control patients 1:5 based on demographic and comorbidity profiles. Two-year fall rates and implant complications, lengths of stay, 90-day readmissions, and time to revision were compared between cohorts.

RESULTS

A total of 1,378 LLD patients were matched to 6,889 control patients. The LLD group had significantly higher rates of falls, dislocation, mechanical loosening, periprosthetic fracture, and fibrosis when compared to the control group (all P < 0.01). Additionally, mean length of stay was significantly greater in the LLD group (4.9 days vs. 3.0 days, P < 0.001). There was no significant difference in 90-day readmission rates between groups (P = 0.178). Time to revision was significantly shorter in the LLD group (392 days vs. 928 days, P < 0.001).

CONCLUSIONS

Leg length discrepancy in patients undergoing TKA was associated with significantly increased fall risk, rates of implant complications, length of stay, and faster time to revision. The findings of this study may allow orthopedic surgeons to identify those patients at risk and allow for more educated patient counseling and operative planning.

LEVEL OF EVIDENCE

III, retrospective case-control study.

The immediate effect of simulating leg-length discrepancy on spinal posture and pelvic position: a cross-over designed study

Leg-length discrepancy (LLD) is a common condition that may cause posture changes and clinical consequences. Rasterstereography is a valid and reliable method that analyzes posture without radiation exposure and invasive procedures. This study aimed to assess the immediate effect of artificial LLD on pelvic position and spinal posture in athletes. Twenty-four elite karate athletes (14 men, 10 women) were included in the study. Sagittal imbalance, coronal imbalance, pelvic obliquity, pelvic torsion angle, thoracic kyphosis angle and lumbar lordosis angle were measured at different artificial LLD heights (5 -10 -15 -20 mm). Statistical analysis was performed with One-Way ANOVA with repeated measures or Friedman test. In cases where there were significant differences, pairwise comparisons were performed with least significant differences (LSD) test or Wilcoxon signed rank test. There were statistically significant differences in pelvic obliquity (p = 0.001), pelvic torsion (p = 0.001) and lumbar lordosis (p = 0.001) with varying LLD. However, there was no significant difference in sagittal imbalance, coronal imbalance and thoracic kyphosis angle. It has been observed that even a 5-mm LLD causes pelvic position and spinal posture changes. Future studies detecting these changes in populations with LLD via rastersterography may prevent possible musculoskeletal disorders.

A novel measurement approach to dynamic change of limb length discrepancy using deep learning and wearable sensors

The accurate identification of dynamic change of limb length discrepancy (LLD) in non-clinical settings is of great significance for monitoring gait function change in people's everyday lives. How to search for advanced techniques to measure LLD changes in non-clinical settings has always been a challenging endeavor in recent related research. In this study, we have proposed a novel approach to accurately measure the dynamic change of LLD outdoors by using deep learning and wearable sensors. The basic idea is that the measurement of dynamic change of LLD was considered as a multiple gait classification task based on LLD change that is clearly associated with its gait pattern. A hybrid deep learning model of convolutional neural network and long short-term memory (CNN-LSTM) was developed to precisely classify LLD gait patterns by discovering the most representative spatial-temporal LLD dynamic change features. Twenty-three healthy subjects were recruited to simulate four levels of LLD by wearing a shoe lift with different heights. The Delsys TrignoTM system was implemented to simultaneously acquire gait data from six sensors positioned on the hip, knee and ankle joint of two lower limbs respectively. The experimental results showed that the developed CNN-LSTM model could reach a higher accuracy of 93.24% and F1-score of 93.48% to classify four different LLD gait patterns when compared with CNN, LSTM, and CNN-gated recurrent unit(CNN-GRU), and gain better recall and precision (more than 92%) to detect each LLD gait pattern accurately. Our model could achieve excellent learning ability to discover the most representative LLD dynamic change features for classifying LLD gait patterns accurately. Our technical solution would help not only to accurately measure LLD dynamic change in non-clinical settings, but also to potentially find out lower limb joints with more abnormal compensatory change caused by LLD.

The Immediate Effects of Muscle Energy Technique in Chronic Low Back Pain Patients with Functional Leg Length Discrepancy: A Randomized and Placebo-Controlled Trial

This study was conducted to determine the effect of muscle energy technique (MET) on pelvic alignment, leg length, pain, and fatigue in chronic low back pain (CLBP) patients with leg length discrepancy (LLD). Forty-two CLBP patients with LLD volunteered to participate and were randomly assigned to the MET group (n = 21) and placebo group (n = 21). The intervention group performed three METs with 5 s of isometric contraction and 30 s of rest once, and the placebo group performed three times the placebo-MET, maintaining the same posture as the MET group without muscle isometric contraction. X-ray equipment, tape measure, and visual analog scale were used to evaluate pelvic alignment, leg length, pain, and fatigue before and after each intervention. In comparison pre- and postintervention, only the MET group showed significant changes in pelvic alignment, leg length, pain, and fatigue (p < 0.05). In comparison between groups, there were significant differences in all variables (pelvic alignment, leg length, pain, fatigue) (p < 0.05). The results of this study confirmed the therapeutic effect of MET for improving pelvic alignment, functional LLD, pain, and fatigue in CLBP patients with functional LLD. Future research is needed to evaluate the long-term effect on more chronic low back pain patients.

Impact of bilateral motion control shoes with outsole adjustment on gait asymmetry in individuals with mild leg length discrepancy

BACKGROUND

Footwear adjustment is recommended in the management plan of leg length discrepancy. However, it is not clear how the outsole of motion control shoe adjustment influences trunk symmetry and walking performance.

RESEARCH QUESTION

Does bilateral adjustment of the outsole affect trunk and pelvis symmetry and ground reaction force during walking in individuals with leg length discrepancy?

METHODS

20 mild leg length discrepancy participants were recruited into a cross-sectional study. All subjects performed a walking trial with their habitual shoes to determine the outsole adjustment. Four trials of walking were carried out in the order of unadjusted and bilateral adjusted motion control air-cushion shoes. Shoulder level differences and trunk and pelvic motion were assessed, while the ground reaction force at the heel strike was reported. A paired t-test was performed to compare the differences between the conditions with a significance level at p < 0.05.

RESULTS

During walking trials, mild leg length discrepancy participants with the adjusted shoe displayed lower variations in the maximum shoulder height differences (p = 0.001) and trunk rotation angle (p = 0.002) than those with the unadjusted shoe. Also, there was a significant reduction in the vertical ground reaction force (p = 0.030), but not in the anteroposterior or mediolateral directions, during walking in the adjusted shoe condition compared to the unadjusted shoe condition.

SIGNIFICANCE

The outsole adjustment of the bilateral motion control shoes can improve trunk symmetry while decreasing the ground impact at the heel strike. The study provides additional information to prescribe or recommend footwear adjustment to improve walking symmetry in leg length discrepancy participants.

Induced leg length inequality affects pelvis orientation during upright standing immediately following a sit-to-stand transfer: a pre-post measurement study

BACKGROUND

Leg length inequality (LLI) greater than 20 mm has been associated with low back pain (LBP) and its correction is clinically recommended. Much less is known about the biomechanical effects that LLI below 15 mm has on pelvis orientation.

METHODS

Twenty-two adult participants (8 female) aged between 18 and 30 years without LBP were enrolled in the study and completed a series of sit-to-stand trials with no heel-lift (0 mm baseline) and heel-lifts of varying heights (5, 9 and 12 mm) placed in their right shoe. Three-dimensional kinematic data were obtained from the lower extremities, pelvis and thorax. Additional kinematic data were obtained from the left and right sides of the pelvis. The global orientation of the whole pelvis and relative orientation between the left and right sides of the pelvis were obtained in upright standing immediately upon completion of the sit-to-stand movement. Repeated measures ANOVAs were used to detect differences in sample means across the different levels of heel-lift (0, 5, 9, and 12 mm). The tests for within-subject effects determined overall significant differences between the means at the different levels of heel-lift induced LLI. Partial Eta-Squared was used to express the size for the main effect of heel-lift height. For each level of heel-lift, the estimated marginal mean and 95% confidence interval (95%CI) values of pelvis angles were illustrated graphically.

RESULTS

Left frontal plane rotation of the pelvis increased (p = 0.001), that is, the left side of the pelvis was lower than the right side of the pelvis, and anterior tilt of the pelvis decreased (p = 0.020) with a heel-lift height (applied on the right) as low as 5 mm. A significant main effect of heel-lift was only observed for the norm of rotations about all three axes for relative-pelvis orientation (p = 0.034). Post-hoc analyses did not reveal any statistically significant differences between the heel-lifts and the 0 mm baseline (p≥0.072).

CONCLUSION

These findings suggest that correcting leg length inequality below the recommended threshold of 20 mm may influence pelvic orientation. Future work can investigate the effects of the altered orientations on spine loading and the clinical effects of corrections to minor leg length inequality.

Risk factors for femoral overgrowth after femoral shortening osteotomy in children with developmental dysplasia of the hip

Objective

Developmental dysplasia of the hip (DDH) refers to a series of deformity of acetabulum and proximal femur and abnormal relationship between them, it represents the most common hip disease in children. Overgrowth and limb length discrepancy (LLD) was common complication in children undergoing femoral shortening osteotomy. Therefore, the purpose of this study was to explore the risk factors of overgrowth after femoral shortening osteotomy in children with DDH.

Methods

We included 52 children with unilateral DDH who underwent pelvic osteotomy combined with femoral shortening osteotomy between January 2016 and April 2018, including seven males (six left and one right hip) and 45 females (33 left and 12 right hips) with an average age of 5.00 ± 2.48 years, and an average follow-up time of 45.85 ± 6.22 months. The amount of overgrowth and limb length discrepancies (LLDs) were calculated. The risk factors of femoral overgrowth ≥1 cm and LLD ≥ 1 cm were analyzed.

Results

There were statistical differences in age (p < 0.001) and operation duration (p = 0.010) between the two groups with femoral overgrowth <1 cm and ≥1 cm. There was a statistical difference in operation duration (p < 0.001) between the two groups. Age (p < 0.001) was an independent influencing factor of femoral overgrowth in children with unilateral DDH after pelvic osteotomy and femoral shortening osteotomy, and a risk factor (p = 0.008) of LLD in these children.

Conclusion

The overgrowth and LLD of children with developmental dislocation of hip after pelvic osteotomy and femoral shortening osteotomy are significantly related to age. There was no significant difference between different pelvic osteotomies for femoral overgrowth in children. Therefore, surgeons should consider the possibility of LLD after femoral shortening osteotomy in children of a young age.

Effect of the Inverted V-Shaped Osteotomy on Patellofemoral Joint and Tibial Morphometry as Compared With the Medial Opening Wedge High Tibial Osteotomy

BACKGROUND

Recent studies have reported that medial opening wedge (OW) high tibial osteotomy (HTO) induces patella baja, resulting in degenerative changes in the patellofemoral joint. We have developed an inverted V-shaped (iV) HTO, which is classified as a neutral wedge osteotomy.

HYPOTHESES

The study hypotheses were as follows: (1) patellar height, posterior tibial slope, and tibial length will not change between pre- and postoperative evaluations after iV-HTO; (2) the lateral shift ratio of the patella and the distance between the tibial tubercle and the trochlear groove may be significantly decreased after iV-HTO.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

A total of 191 patients (220 knees) who underwent HTO for medial osteoarthritis were enrolled retrospectively in this study: 107 knees underwent OW-HTO and 113 knees underwent iV-HTO. Clinical and radiological evaluations were performed before and at least 3 years after surgery.

RESULTS

Postoperatively, the mean Caton-Deschamps ratio was significantly decreased (P < .0001) from 0.95 to 0.79 in the OW group, while there were no significant changes in the iV group. The mean posterior tibial slope was significantly increased (P < .0001) from 8.5° to 10.5° in the OW group, while there were no significant differences in the iV group. Although the entire leg length was significantly increased (P < .0003) in both groups after HTO, there were no significant differences in tibial length between the pre- and postoperative periods in the iV group. Regarding the congruity of the patellofemoral joint, the mean lateral shift ratio did not significantly change in the OW group, whereas it was significantly decreased (P = .0012) from 11.5% to 8.8% in the iV group. The mean tibial tubercle-trochlear groove distance was significantly decreased (P < .0001) from 12.8 to 9.7 mm in the iV group, while it was significantly increased in the OW group (P < .0001). Concerning the clinical outcome, the Japanese Orthopaedic Association (JOA) and Lysholm knee scores at final follow-up (OW vs iV: JOA, 91.2 vs 90.1; Lysholm, 92.5 vs 89.0) were significantly increased (P < .0001) as compared with the preoperative values (OW vs iV: JOA, 68.3 vs 66.8; Lysholm, 67.9 vs 61.0).

CONCLUSION

Patellar height, posterior tibial slope, and tibial length did not change after the iV-HTO, while they were significantly changed after the OW-HTO. Although the preoperative degrees of varus knee and patellofemoral osteoarthritis were more severe in the iV group than the OW group, the iV-HTO led to altered patellofemoral joint congruity.

Effect of limited range of motion of the hip joint and leg-length discrepancy on gait trajectory: an experiment to reproduce the asymmetric gait that occurs in patients with osteoarthritis of the hip joint

PURPOSE

Although some symptoms that often occur with hip joint osteoarthritis (OA) may be involved in the appearance of gait disturbance, the main cause has not been identified. We hypothesised that the abnormalities in gait trajectory of patients with hip joint OA are mainly caused by limited range of motion of the hip joint or the presence of leg-length discrepancy, or both. To investigate this hypothesis, we examined whether the abnormal gait trajectory in patients with hip joint OA can be reproduced in healthy individuals by asking them to wear a hip orthosis and shoe orthotic (insole).

METHODS

We recruited 2 groups of participants: patients with hip joint OA (OA group, 38 patients) and healthy individuals who imitated patients with OA of the hip joint by wearing a hip orthosis or shoe orthotic (10-mm or 20-mm insole) or both (simulated OA group, 6 individuals). For gait analysis, we used a portable, wearable gait analyser with inertial sensors to evaluate 3-dimensional (3D) changes in gait trajectory.

RESULTS

In the OA group, the patterns of gait trajectories that were drawn on the 3 planes (coronal, sagittal, and horizontal planes) could be roughly divided into 3 types. The gait trajectories that were drawn when wearing a hip orthosis in the simulated OA group were very similar to 1 of the 3 patterns of gait trajectory that occurs in the OA group.

CONCLUSIONS

We were able to reproduce the abnormal gait trajectory that is observed in ⅓ of patients with hip OA in healthy individuals, so we propose that an extreme reduction in hip joint ROM is 1 of the causes of abnormal gait pattern in patients with OA of the hip joint. A difference in leg length of 20 mm alone has little effect on gait trajectory.

Effect of correction of leg length discrepancy on the biomechanical characteristics of the pelvis and hip joints among standing workers

BACKGROUND: Few studies have reported the contribution of correction of leg length discrepancy (LLD) on the kinematic and kinetic characteristics of the pelvis and hip joints among those who must stand while working using shoe insoles and a three-dimensional (3D) motion analysis system. OBJECTIVE: To investigate dynamic pelvic and hip joint angles and hip moments using a 3D motion analysis system with and without insoles in standing workers with LLD. METHODS: Kinematic and kinetic data of 31 participants with LLD were collected using a motion analysis system and force platforms. Participants were asked to walk wearing standard shoes or shoes with LLD-corrected insoles. Repeated-measures analysis of variance (ANOVA) was used to compare the kinematic and kinetic data of the hip joints and pelvic orientation according to leg side and corrective interventions for LLD. RESULTS: There were significant differences in maximal ROM of hip adduction and abduction with vs. without LLD insoles in the longer and shorter legs (p < 0.05). There were significant differences in maximal elevation (p = 0.004) and total coronal motion (p = 0.006) of the pelvic segment with and without insole corrections in the longer leg during gait. CONCLUSIONS: LLD correction using a customized insole is a recommended therapeutic intervention to improve the musculoskeletal imbalances of hip and pelvic segments in workers with LLD.

Effects of orthotic insole on gait patterns in children with mild leg length discrepancy

BACKGROUND

Leg length discrepancy (LLD) is commonly associated with compensatory gait strategies leading to musculoskeletal disorders of the lower extremity and lumbar spine. Orthotic insole (OI) is considered as a conservative treatment for patients with mild LLD, especially for children. However, the restoration of normal gait when wearing OI with foot lift are still poorly understood.

RESEARCH QUESTION

What are the immediate effects of OI on the gait patterns in children with mild LLD?

METHODS

Gait data and plantar pressure data were collected for 12 children with mild anatomical LLD in barefoot and OI conditions. Paired t-test was performed to determine the changes in gait between these two conditions, and also the symmetry between limbs in the same condition for spatiotemporal, kinematic, and kinetic variables.

RESULTS

Children with mild LLD showed an immediate gait improvement confirmed by increased step length and velocity, decreased peak plantar pressure in both limbs with OI. Additionally, the significant between-limb differences disappeared for peak ankle dorsiflexion, hip adduction, pelvis upward obliquity and also second peak plantar pressure with OI, which improved gait symmetry.

SIGNIFICANCE

This study provides a better understanding of the immediate effect of OI with foot lift on biomechanical changes in gait, which identify that OI with foot lift could be a potential therapeutic option for children with mild structural LLD to improve gait metrics.

Lumbar Spine Fusion and Symptoms of Leg Length Discrepancy After Hip Arthroplasty

BACKGROUND

Hip length discrepancy (HLD) is common after total hip arthroplasty (THA); however, the effect of spinal fusion on perceived leg length discrepancy (LLD) symptoms after THA has not been examined. This study tested the hypothesis that LLD symptoms are increased in patients who underwent lumbar spinal fusion and THA, compared with patients with THA only.

METHODS

This retrospective cohort study included 67 patients who underwent lumbar spinal fusion and THA, along with 78 matched control patients who underwent THA only. Hip and spine measurements were taken on postoperative, standing anterior-posterior pelvic, lateral lumbar, and anterior-posterior lumbar spinal radiographs. Perceived LLD symptoms were assessed via telephone survey.

RESULTS

Between the spinal fusion and control groups, there was no significant difference in HLD (M = 7.10 mm, SE = 0.70 and M = 5.60 mm, SE = 0.49) (P = .403). The spinal fusion patients reported more frequently noticing a difference in the length of their legs than the control group (P = .046) and reported limping "all the time" compared with the control group (P = .001). Among all patients with an HLD ≤10 mm, those in the spinal fusion group reported limping at a higher frequency than patients in the control group (P = .008). Patients in the spinal fusion group were also more likely to report worsened back pain after THA (P = .011) than the control group.

CONCLUSION

Frequencies of a perceived LLD, limping, and worsened back pain after THA were increased in patients with THA and a spinal fusion compared with patients who had THA only, even in a population with HLD traditionally considered to be subclinical. The results indicate that in patients with prior spinal fusion, precautions should be taken to avoid even minor LLD in the setting of THA.

Research and development of 3D printing orthotic insoles and preliminary treatment of leg length discrepancy patients

BACKGROUND:

Leg length discrepancy (LLD) can cause abnormal posture, muscle and/or joint pains, which leads to walking difficulties. The common treatment is to use a shoe lift on the shorter leg side, but this has unsatisfying results.

OBJECTIVE:

Through research and development, we created 3D printing orthotic insoles for LLD patients and aimed to improve their symptoms.

METHODS:

1. Research and development of 3D printing orthotic insole: (1) foot scan and data acquisition; (2) insole software modeling; (3) 3D printing insole using TPU materials, and (4) post-processing. 2. Clinical observation: we customized insoles for LLD patients and required them to wear them while walking. We conducted general inquiries and a functional evaluation before and after 12 weeks of wearing insoles.

RESULTS:

There are seven complete cases. The joint and lower back pains were alleviated. The stride frequency, stride and pace were improved in all seven cases. Patients’ overall health condition improved significantly.

CONCLUSIONS:

The 3D printing orthotic insoles are made with clear procedures and practical operability. By wearing insoles, patients’ muscle and/or joint pains were relieved and their gaits were improved.

The effects of incremental changes in rucksack load on lower extremity joint Kinetic patterns during ruck marching

Injuries are often attributed to ruck marching. Therefore, it is important to examine how load carriage influences gait mechanics. The purpose of this study was to examine how subtle changes in rucksack load influence joint torque patterns during marching. Fourteen Army ROTC cadets marched with light, moderate, and heavy rucksack loads. Kinetic and kinematic data were recorded via an instrumented treadmill and motion capture system and principal component analysis was used to analyse the joint torque waveforms. Cadets exhibited moderate-large increases in knee extension torques during early stance (effect sizes ≥0.45) and small-moderate increases in ankle plantarflexion torques during push off (effect sizes ≥0.23) with each incremental increase in rucksack load. The lighter load also resulted in lower hip extension torques during early stance and flexion torques during late stance, vs. the moderate and heavier loads (effect sizes ≥0.23). It appears that subtle changes in rucksack load influence marching mechanics. Practitioner Summary: The purpose of this study was to examine how relatively subtle changes in rucksack load influence marching mechanics. Army ROTC cadets marched with relatively light, moderate, and heavy rucksack loads. Our results indicate that even subtle changes in rucksack load influence joint torque patterns of the hip, knee, and ankle. Abbreviations: ROTC: reserve officer training corps; RoF: rating-of-fatigue; PC: principal component; ICC: intraclass correlation coefficient; ES: effect size.

Effects of Orthotic Insoles on Gait Kinematics and Low-Back Pain in Patients with Mild Leg Length Discrepancy

BACKGROUND

Mild leg length discrepancy increases biomechanical asymmetry during gait, which leads to low-back pain. Orthotic insoles with a directly integrated heel lift were used to reduce this asymmetry and thus the associated low-back pain. The aim of this study was to analyze the biomechanical adaptations of the locomotor apparatus during gait and the subjective pain ratings before and after the establishment of orthotic insole use.

METHODS

Eight patients with mild leg length discrepancy (≤2.0 cm) underwent three-dimensional biomechanical analysis while walking before and after 3 weeks of orthotic insole use. Low-back pain was assessed separately before both measurement sessions using a visual analog scale.

RESULTS

Analysis of the kinematic parameters highlighted individual adaptations. The symmetry index of Dingwell indicated that orthotic insoles had no significant effect on the kinematic gait parameters and an unpredictable effect across patients. Orthotic insole use significantly and systematically (in all of the patients) reduced low-back pain (P < .05), which was correlated with changes in ankle kinematics (P = .02, r = 0.80).

CONCLUSIONS

The effects of orthotic insoles on gait symmetry are unpredictable and specific to each patient's individual manner of biomechanical compensation. The reduction in low-back pain seems to be associated with the improved ankle kinematics during gait.

Changes in muscle activities and kinematics due to simulated leg length inequalities

Muscle imbalances are a leading cause of musculoskeletal problems. One example are leg length inequalities (LLIs). This study aimed to analyze the effect of different (simulated) LLIs on back and leg muscles in combination with kinematic compensation mechanics. Therefore, 20 healthy volunteers were analyzed during walking with artificial LLIs (0-4 cm). The effect of different amounts of LLIs and significant differences to the reference condition without LLI were calculated of maximal joint angles, mean muscle activity, and its symmetry index. While walking, LLIs led to higher muscle activity and asymmetry of back muscles, by increased lumbar lateral flexion and pelvic obliquity. The rectus femoris showed higher values, independent of the amount of LLI, whereas the activity of the gastrocnemius on the shorter leg increased. The hip and knee flexion of the long leg increased significantly with increasing LLIs, like the knee extension and the ankle plantarflexion of the shorter leg. The described compensation mechanisms are explained by a dynamic lengthening of the short and shortening of the longer leg, which is associated with increased and asymmetrical muscle activity. Presenting this overview is important for a better understanding of the effects of LLIs to improve diagnostic and therapy in the future.

Predictor index of functional limb length discrepancy

INTRODUCTION

Limb length discrepancy (LLD) of lower extremities is underdiagnosed due to compensatory mechanisms during locomotion. The natural course of compensation leads to biomechanical alteration in human musculoskeletal system leading to adverse effects. General consensus accepts LLD more than 2 cm as significant to cause biomechanical alteration. No studies were conducted correlating height and lower extremities true length (TL) to signify LLD. Examining significant LLD in relation to height and TL using dynamic gait analysis with primary focus on kinematics and secondary focus on kinetics would provide an objective evaluation method.

METHODOLOGY

Forty participants with no evidence of LLD were recruited. Height and TL were measured. Reflective markers were attached at specific points in lower extremity and subjects walked in gait lab at a self-selected normal walking pace with artificial LLDs of 0, 1, 2, 3, and 4 cm simulated using shoe raise. Accommodation period of 30 min was given. Infrared cameras were used to capture the motion. Primary kinematic (knee flexion and pelvic obliquity (PO)) and secondary kinetic (ground reaction force (GRF)) were measured at right heel strike and left heel strike. Functional adaptation was analyzed and the postulated predictor indices (PIs) were used as a screening tool using height, LLD, and TL to notify significance.

RESULTS

There was a significant knee flexion component seen in height category of less than 170 cm. There was significant difference between LLD 3 cm and 4 cm. No significant changes were seen in PO and GRF. PIs of LLD/height and LLD/TL were analyzed using receiver operating characteristic curve. LLD/height as a PI with value of 1.75 was determined with specificity of 80% and sensitivity of 76%.

CONCLUSION

A height of less than 170 cm has significant changes in relation to LLD. PI using LLD/height appears to be a promising tool to identify patients at risk.

Reconstruction of acetabular defects greater than Paprosky type 3B: the importance of functional imaging

BACKGROUND

3D Surgical planning has become a key tool in complex hip revision surgery. The restoration of centre of rotation (CoR) of the hips and leg length (LL) are key factors in achieving good clinical outcome. Pelvic imaging is the gold standard for planning and assessment of LL. We aimed to better understand if 3D planning is effective at equalising LL when large acetabular defects are present.

MATERIALS AND METHODS

This was a prospective case study of 25 patients. We report the analysis of pre-operative LL status and planned LL restoration measured on CT, in relation to the achieved LL measured post-operatively in functional, weight bearing position. Our primary objective was the assessment of restoration of CoR as well as the anatomical and functional LL using biplanar full-length standing low-dose radiographs; our secondary objective was to evaluate the clinical outcome.

RESULTS

Pre-operative intra-pelvic discrepancy between right and left leg was a mean of 28 mm (SD 17.99, min = 3, max = 60 mm). Post-operatively, the difference between right and left vertical femoral offset (VFO), or CoR discrepancy, was of 7.4 mm on average, significantly different from the functional LL discrepancy (median = 15 mm), p = 0.0024. Anatomical LLD was a median of 15 mm. In one case there was transient foot drop, one dislocation occurred 6 months post-operatively and was treated by closed reduction, none of the patients had had revision surgery at the time of writing. Mean oxford hip score at latest follow up was 32.1/48.

DISCUSSION

This is the first study to investigate limb length discrepancy in functional position after reconstruction of large acetabular defects. We observed that VFO is not an optimal surrogate for LL when there is significant bone loss leading to length inequality, fixed flexion of the knee and abduction deformity.

CONCLUSIONS

Although challenging, LLD and gait abnormalities can be greatly improved with the aid of an accurate surgical planning. Surgeons and engineers should consider the integration of EOS imaging in surgical planning of reconstruction of large acetabular defects.

Inertial measurement units for the detection of the effects of simulated leg length inequalities

Background

Leg length inequalities (LLI) are a common condition that can be associated with detrimental effects like low back pain and osteoarthritis. Inertial measurement units (IMUs) offer the chance to analyze daily activities outside a laboratory. Analyzing the kinematic effects of (simulated) LLI on the musculoskeletal apparatus using IMUs will show their potentiality to improve the comprehension of LLI.

Methods

Twenty healthy participants with simulated LLI of 0-4 cm were analyzed while walking with an inertial sensor system (MyoMotion). Statistical evaluation of the peak anatomical angles of the spine and legs were performed using repeated measurement (RM) ANOVA or their non-parametric test versions (Friedman test).

Results

Lumbar lateral flexion and pelvic obliquity increased during the stance phase of the elongated leg and decreased during its swing phase. The longer limb was functionally shortened by higher hip and knee flexion, higher hip adduction, dorsiflexion, and lower ankle adduction. Finally, the shorter leg was lengthened by higher hip and knee extension, hip abduction, ankle plantarflexion, and decreased hip adduction.

Conclusion

We found differing compensation strategies between the different joints, movement planes, gait phases, and amounts of inequality. Overall the shorter leg is lengthened and the longer leg is shortened during walking, to retain the upright posture of the trunk. IMUs were helpful and precise in the detection of anatomical joint angles and for the analysis of the effects of LLI.

Symptomatic leg length discrepancy after total hip arthroplasty is associated with new onset of lower back pain

BACKGROUND

Leg length discrepancy (LLD) is common after total hip arthroplasty (THA) with a plethora of clinical consequences. The associations between symptomatic (sLLD; disturbing perception of anatomical leg length discrepancy), anatomical (aLLD; side difference in leg length between the center of rotation of the hip and the center of the ankle joint) and intraarticular (iLLD; side difference between the tear drop figure and the most prominent point of the trochanter minor) LLD and lower back have not yet been reported in the literature. We performed a retrospective study to answer if postoperative (1) symptomatic LLD, (2) anatomic LLD, and (3) a change in intraarticular leg length are associated with lower back pain in patients undergoing THA. Further, we aimed to answer (4) whether symptomatic LLD is associated with the magnitude of anatomical LLD and the change in intraarticular leg length.

HYPOTHESIS

LLD after THA is associated with lower back pain.

MATERIALS AND METHODS

Seventy-nine consecutive patients were retrospectively analyzed for the presence of aLLD and iLLD using EOS™ and X-rays, and were interviewed for the presence of sLLD and lower back pain using a questionnaire 5 years after primary THA.

RESULTS

Postoperative new onset of lower back pain was reported by 9 (11%) patients. Twenty (25%) patients reported sLLD. Anatomical LLD>5mm was present in 44 (56%) (median 8.0 (IQR -3.0 to 12.0; range -22 to 22) mm) and>10mm in 17 (22%) (median 12.0 (IQR 11.0 to 16.5; range -22 to 22) mm) patients. iLLD changed>5mm in 44 (56%) (median 8.5 (IQR 7.0 to 10.0; range -8 to 18) mm) and>10mm in 10 (13%) (median 14.0 (IQR 12.5 to 14.5; range 11 to 18) mm). New onset lower back pain was associated with sLLD (p=0.002) but not with aLLD or iLLD. Patients without preoperative lower back pain had a statistically significant association between presence of sLLD and an aLLD of >10mm (p=0.01).

CONCLUSIONS

Symptomatic LLD after primary THA is associated with postoperative new onset of lower back pain irrespective of the magnitude of LLD. In patients without lower back pain prior to THA, symptomatic LLD is associated with anatomical LLD of more than 10mm.

LEVEL OF EVIDENCE

IV.

Orthotic Insoles Improve Gait Symmetry and Reduce Immediate Pain in Subjects With Mild Leg Length Discrepancy

Background: Mild leg length discrepancy can lead to musculoskeletal disorders; however, the magnitude starting from which leg length discrepancy alters the biomechanics of gait or benefits from treatment interventions is not clear.

Research question: The aim of the current study was to examine the immediate effects of orthotic insoles on gait symmetry and pain on mild leg length discrepancy according to two groups of the leg length discrepancy (i.e., LLD ≤ 1 cm vs. LLD > 1 cm).

Methods: Forty-six adults with mild leg length discrepancy were retrospectively included and classified into two groups (G_LLD≤1cm or G_LLD>1cm). All subjects underwent routine 3D gait analysis with and without orthotic insoles. The symmetry index was calculated to assess changes in gait symmetry between the right and left limbs. Pain was rated without (in standing) and with the orthotic insoles (after 30 min of use) on a visual analog scale.

Results: There was a significant improvement in the symmetry index of the pelvis in the frontal plane (p = 0.001) and the ankle in the sagittal plane (p = 0.010) in the stance with the orthotic insoles independent from the group. Pain reduced significantly with the orthotic insoles independently from the group (p < 0.001).

Significance: Orthotic insoles significantly improved gait symmetry in the pelvis in the frontal plane and the ankle in the sagittal plane, as well as pain in all subjects (both LLD ≤ 1 cm and LLD > 1 cm) suggesting that it may be appropriate to treat even mild leg length discrepancy.

Dynamic leg length measurement is a valid method for detecting anatomic leg length discrepancy

BACKGROUND

Even though the importance of leg length discrepancy (LLD), with its potential of causing several pathological conditions or gait deviations, is well known, measuring LLD is still challenging with limited reliability and validity.

OBJECTIVE

To assess the capability of the dynamic leg length (DLL) measurement in detecting the presence of anatomic LLD.

METHODS

A lower limb x-ray was performed on 15 participants with suspected LLD in addition to a gait analysis study using a motion analysis system to measure DLL (the absolute distance from the hip joint centre to the heel, to the ankle joint centre and to the forefoot). Average DLLs were compared between sides for symmetry by the paired t-test at 51 sample points during the gait cycle in conjunction with the differences between the sides based on the maximal stance phase and minimal swing phase DLLs. Differences were correlated with anatomic LLD by Pearson correlation.

RESULTS

No significant differences in DLLs between sides throughout the gait cycle were found. Significant differences between sides were found between the maximal stance and minimal swing phase DLLs.

CONCLUSIONS

DLL measurement is capable of detecting an anatomic leg length difference based on functional changes in leg length and functional discrepancy.

Do hip strength, flexibility and running biomechanics predict dynamic valgus in female recreational runners?

BACKGOUND

Dynamic valgus has been the focus of many studies to identify its association to an increased risk of running-related injuries. However, it is not known which physical and biomechanical variables are associated with this movement dysfunction.

RESEARCH QUESTION

This study aimed to test the correlation between strength, flexibility and biomechanical variables and dynamic valgus in female runners.

METHODS

Twenty-nine healthy females ran on a treadmill at 2.92 m/s and performed strength, range of motion and endurance tests. Pelvic, hip and ankle kinematics were measured with a 3D motion analysis system. Six multiple linear regression models were used to identify the ability of physical and biomechanical variables to predict excursion and peak of contralateral pelvic drop, hip adduction and internal rotation.

RESULTS

Contralateral pelvic drop and hip adduction were positively correlated to ankle eversion and step cadence. Hip internal rotation had a negative correlation with ankle eversion. Despite significance, predictor variables explained less than 30% of dynamic valgus variance during running. No interest variable had significant correlation with the hip strength and hip and ankle passive range of motion.

SIGNIFICANCE

The results showed that distal joint kinematics and spatiotemporal variables should be considered during biomechanical running analysis to identify their possible relationship with joint overload caused by dynamic valgus. Caution should be taken when linking hip disorders during running to posterolateral hip strength and stiffness, core endurance, and ankle dorsiflexion range of motion since no correlation occurred amongstthese variables in this sample of female runners.

Unilateral and bilateral patellofemoral pain in young female dancers: Associated factors

Aiming to evaluate the prevalence of unilateral/bilateral patellofemoral pain (PFP) among young dancers, and to investigate whether different factors are associated with PFP in young dancers, 132 dancers aged 12-14 years were assessed for PFP. Anthropometric parameters, proprioception ability, dynamic postural balance (DPB), and muscle strength were measured. PFP was found in 64.1% of the dancers. No significant differences in the prevalence of dancers with no, unilateral, or bilateral PFP at different ages were found. Significant age effects were found for anthropometric and developmental measurements, and for intensity of training. PFP effect was found for DPB asymmetry, ankle proprioception, and leg-length %height. A higher hip abductor/adductor ratio was associated with PFP in 14-year-old dancers. Binomial logistic regression showed that increased number of hours per day (h/day) and decreased number of hours per week (h/week), low proprioception scores, greater leg length as %height, and more anterior DPB asymmetry were significant predictors of PFP. In conclusion: unilateral/bilateral PFP is common among young dancers. Body morphology, reduced ankle proprioception ability, DPB asymmetry, and increased h/day of practice are associated with PFP. Dance teachers should start monitoring the impact of training and implement injury modification/prevention strategies when their students are at a young age.

MRI-biochemical follow up measurements of lumbar intervertebral disc in patients with leg length discrepancy: Is it possible to alter cartilage damage with conservative therapy?

Objective

Effect of conservative therapy on intervertebral discs (IVD) in patients with leg-length-discrepancy (LLD).

M&M

Seventy lumbar IVDs of 14 participants (five with LLD 10-20 mm) were examined using a 3T-MRI-scanner. Morphological (Pfirrmann) and molecular (glycosaminoglycan-chemical-exchange-saturation-transfer, gagCEST) grading was assessed before and after a four-month therapy (physiotherapy and shoe inlays).

Results

Significantly lower GAG values in patients with LLD were found (L5/S1, p = 0.02). After therapy, a trend towards higher gagCEST values in patients with LLD was observed (2.48 ± 1.77% vs. 1.79 ± 0.79%; p > 0.05).

Conclusion

LLD represents a risk factor for molecular alterations of lumbar IVDs. Only minor effects of conservative therapy on these alterations could be found.

Effects of medially wedged insoles on the biomechanics of the lower limbs of runners with excessive foot pronation and foot varus alignment

BACKGROUND

Excessive foot pronation during running in individuals with foot varus alignment may be reduced by medially wedged insoles.

RESEARCH QUESTION

This study investigated the effects of a medially wedged insole at the forefoot and at the rearfoot on the lower limbs angles and internal moments of runners with excessive foot pronation and foot varus alignment.

METHODS

Kinematic and kinetic data of 19 runners (11 females and 8 males) were collected while they ran wearing flat (control condition) and medially wedged insoles (insole condition). Both insoles had arch support. We used principal component analysis for data reduction and dependent t-test to compare differences between conditions.

RESULTS

The insole condition reduced ankle eversion (p = 0.003; effect size = 0.63); reduced knee range of motion in the transverse plane (p = 0.012; effect size = 0.55); increased knee range of motion in the frontal plane in early stance and had earlier knee adduction peak (p = 0.018; effect size = 0.52); reduced hip range of motion in the transverse plane (p = 0.031; effect size = 0.48); reduced hip adduction (p = 0.024; effect size = 0.50); reduced ankle inversion moment (p = 0.012; effect size = 0.55); and increased the difference between the knee internal rotation moment in early stance and midstance (p = 0.012; effect size = 0.55).

SIGNIFICANCE

Insoles with 7˚ medial wedges at the forefoot and rearfoot are able to modify motion and moments patterns that are related to lower limb injuries in runners with increased foot pronation and foot varus alignment with some non-desired effects on the knee motion in the frontal plane.

Assessment of glycosaminoglycan content in intervertebral discs of patients with leg length discrepancy: A pilot study

OBJECTIVE

Leg length discrepancy (LLD) could be a predisposing factor for early degeneration of lumbar intervertebral discs (IVD). The purpose of this study was to elucidate the molecular effect of LLD on IVDs.

METHODS

IVDs of Eleven patients (25.6 ± 4.3years) with LLD (>10 mm) and 14 control subjects (23.9 ± 3.5years) were compared using a 3T-MR scanner. Morphological T2-weighted and glycosaminoglycan-chemical-exchange-saturation-transfer (gagCEST) sequences were performed.

RESULTS

No differences in morphological Pfirrmann grading were found (p > 0.05). In contrast, nucleus-pulposus-gagCEST-values of L5/S1 were significantly lower (p = 0.0008).

CONCLUSION

Our results suggest that LLD is a predisposing factor for molecular IVD alterations, which are detectable even before morphological pathologies could be found.

INFLUENCE OF CUSTOMIZED FOOT ORTHOTICS ON GAIT BALANCE FOR PELVIC ASYMMETRY PATIENTS

Gait is one of the most common and important factor of human movements in daily life. Pelvis is closely connected with the gait due to it allows maintain stable posture by supporting the spine and lower extremities against the gravity. Therefore, pelvic asymmetry, which is caused by biomechanical stress and muscle imbalance, has been associated with postural imbalance and abnormal walking pattern. The purpose of this study was to manufacture customized foot orthotics for improving gait balance and evaluate the effectiveness of customized foot orthotics during walking by measuring lower extremity muscle activity and plantar pressure distribution. All subjects with pelvic asymmetry were asked to walk on a treadmill under three conditions: walking without foot orthotics, walking with customized foot orthotics and walking with non-customized foot orthotics. Root mean square (RMS) value of the electromyography signals, force and peak pressure of the plantar pressure distribution was analyzed based on the gait cycle. The results showed that excessive tension of the muscles and high pressure of the foot that was induced by pelvic asymmetry were more reduced when walking with custom-made foot orthotics than walking without foot orthotics and walking with non-customized foot orthotics. This paper suggest that custom-made orthotics for patients with pelvic asymmetry could be helpful to relieve the excessive loading of the foot and maintain balanced gait pattern.

Leg Length Discrepancy: The Natural History (And What Do We Really Know)

BACKGROUND

The long-term effects of small limb length discrepancies have been poorly documented in the literature. References to low back pain, hip pathology, knee pathology, and foot problems abound in the popular literature. Health care providers frequently recommend the use of lifts for structural and functional limb length discrepancies, yet the natural history of limb length inequality as well as the effectiveness of treatments that may be recommended are obscure. The purpose of this paper is to document and evaluate the literature associated with small limb length discrepancies.

METHODS

A search of the English literature was carried out using PubMed to identify papers dealing with the effects of limb length discrepancies. Papers reporting only expert opinion or case reports were excluded.

RESULTS

Papers dealing with the natural history of limb length discrepancy as well as studies in which gait analysis was performed in patients with limb length discrepancy were identified. Only 10% of the population has exactly equal lower limb lengths. Approximately 90% of the population has a limb length discrepancy <1.0 cm. Hip and knee pathology is present in an increased number of patients with limb length discrepancies over 5 mm. Hip pathology is more often present in the long leg, knee pathology has been reported in various studies to be more common in either the long or short leg. Low back problems seem to be more common on the short side in patients with limb length discrepancies. A number of different compensatory mechanisms for limb length discrepancy have been identified during gait analysis.

CONCLUSIONS

There seems to be a consensus that limb length discrepancies >2.0 cm are frequently a problem. There is some evidence that limb length discrepancies as little as 5 mm can lead to long-term pathology.

Understanding Skeletal Growth and Predicting Limb-Length Inequality in Pediatric Patients

Limb-length inequality in a child can be a complex condition for patients, parents, and medical providers. Managing these patients and explaining the treatment options to families requires knowledge of the potential risks associated with leaving a discrepancy untreated and a thorough understanding of skeletal growth. The provider must also be familiar with the available growth prediction methods as treatment is influenced by the anticipated discrepancy at skeletal maturity. This article provides an overview to skeletal growth, assessing skeletal maturity and growth prediction to help providers develop an organized and thoughtful approach to treating pediatric patients with limb-length inequalities.

What are the biomechanical consequences of a structural leg length discrepancy on the adolescent spine during walking?

BACKGROUND

Structural leg length discrepancy (LLD) is a common phenomenon. However, its effect on spinal gait kinematics remains unclear.

RESEARCH QUESTION

How does LLD affect spinal gait kinematics in patients with structural LLD and what is the immediate effect of a shoe lift?.

METHODS

10 adolescents with structural LLD (20-60 mm) and 14 healthy controls were included. All of whom were fitted with a trunk marker set and requested to walk barefoot as well as with an orthotic shoe lift (only patients). Data were collected using a 12-camera motion capture system. Group comparisons were conducted using one-dimensional Statistical Parametric Mapping (SPM).

RESULTS

Patients with LLD showed statistically significant increased frontal plane lumbar bending angles to the longer side (p = 0.007), increased pelvic drop on the shorter side (p < 0.001) and increased hip adduction angles on the longer leg (p < 0.001) compared to the healthy controls. In the sagittal plane, patients demonstrated changed knee (shorter leg) and ankle joint (longer leg) motion. All gait deviations observed in patients with LLD could immediately be altered by correcting the LLD using a shoe lift.

SIGNIFICANCE

Due to the LLD, patients showed a lateral pelvic drop on the shorter side, which appeared to be compensated for by a contralateral bending in the lumbar spine and a lateral shift of the pelvis towards the longer side. In addition, the use of an orthotic correction seems to be a suitable option to instantly normalize gait kinematics in patients with mild to moderate LLD.

Effects of foot pronation on the lower limb sagittal plane biomechanics during gait

BACKGROUND

Increased foot pronation may compromise ankle plantarflexion moment during the stance phase of gait, which may overload knee and hip.

RESEARCH QUESTION

This study investigated the influence of increased foot pronation on lower limbs angular displacement, internal moments and power in the sagittal plane and ground reaction force and center of pressure displacement during the stance phase of gait.

METHODS

Kinematic and kinetic data of 22 participants (10 women and 12 men) were collected while they walked wearing flat (control condition) and laterally wedged sandals to induce foot pronation (inclined condition). We used principal component analysis for data reduction and dependent t-test to compare differences between conditions with α = 0.05.

RESULTS

The inclined condition increased forefoot range of motion (p < 0.001; effect size = 0.73); increased ankle plantarflexion angle (p < 0.001; effect size = 0.96); reduced ankle plantarflexion moment in mid and terminal stance phases and delayed and increased ankle plantarflexion moment in late stance (p < 0.001; effect size = 0.72); increased range of ankle power during late stance (p = 0.006; effect size = 0.56); reduced knee range of moment (p < 0.001; effect size = 0.76); increased range of knee power in early stance and reduced knee power generation in late stance (p = 0.005; effect size = 0.56); reduced the anterior displacement of the center of pressure (p < 0.001; effect size = 0.82) and increased the ground reaction force in the anterior direction (p = 0.003; effect size = 0.60).

SIGNIFICANCE

Increased foot pronation compromises lower limb mechanics in the sagittal plane during the stance phase of gait. These findings are explained by the fact that foot pronation increases foot segments flexibility and compromises foot lever arm function during the stance of gait.

Measuring Dynamic Leg Length during Normal Gait

Dynamic leg length [DLL] is a resultant factor of anatomic leg length and lower limb movement that is measured by the distance from the hip to the heel, ankle, and forefoot during the gait cycle. The aim of this study was to present DLL measurement during normal gait. Forty healthy participants underwent a gait evaluation using a motion analysis system. The average DLLs were compared between sides during the gait cycle using the paired t-test at 51 sample points. Time of maximal and minimal DLLs and the ratio between maximal and minimal DLLs during the gait cycle were calculated. DLLs were found to be consistent, indicated by a within standard deviation of <6.65 mm and by being symmetrical with no significant differences between sides [p > 0.103]. DLL patterns and time of maximal and minimal DLLs were established. The ratio between maximal DLLs during the stance phase and minimal DLLs during the swing phase was also defined and found to be symmetrical. Normative data of DLL measures were set with respect to magnitude and pattern during the gait cycle. These data might serve as a reference for abnormal gait deviation reflected by abnormal DLLs, thus promoting a new perspective in gait analysis.

Patellar height influences knee function in patients with aggressive bone tumors of the proximal tibia after endoprosthetic reconstruction

BACKGROUND

The proximal tibia is the second most common site of aggressive bone tumors. In proximal tibia resection, the patellar tendon is sectioned one to two centimeters from its insertion on the tibial tubercle, which makes it technically challenging to achieve an appropriate patellar height and firm fixation of the patellar tendon. The purpose of this study was to determine whether the patellar height influences knee function after proximal tibia endoprosthetic reconstruction (EPR).

METHODS

Twenty-nine patients with pathologically confirmed aggressive bone tumors in the proximal tibia were retrospectively analyzed. We used the Insall-Salvati ratio (ISR) and the Blackburne-Peel index (BPI) to radiographically analyze the patellar height. Functional outcomes were retrospectively assessed using the Musculoskeletal Tumor Society (MSTS) score, the Oxford Knee Score (OKS) and the range of motion (ROM) which was evaluated through extensor lag and active flexion. Univariate analysis with Pearson's correlation and a multivariate linear regression of patient characteristics and surgery-related changes were performed.

RESULTS

The postoperative ISRs were negatively correlated with the functionality domain of the MSTS score (function, gait, walking) and the OKS. Pearson's correlation analysis showed a significant correlation between the postoperative ISR and extensor lag. The change in patellar height had no impact on the active flexion of the knee.

CONCLUSIONS

Patellar height is an independent factor contributing to knee function after proximal tibia EPR. The quality of patellar tendon reconstruction is a key point in proximal tibia EPR after tumor resection.

No relationship between mild limb length discrepancy and spine, hip or knee degenerative disease in a large cadaveric collection

BACKGROUND

Although asymptomatic mild limb length discrepancy (LLD) in children is generally treated non-operatively, there is limited high quality follow up data to support this recommendation.

HYPOTHESIS

We hypothesized that there would be no association between LLD and arthritic changes with mild limb length discrepancy.

MATERIALS AND METHODS

We studied 576 well-preserved cadaveric skeletons ranging from 40 to 79 years of age. Limb length discrepancy was based on combined femoral and tibial lengths measured using digital calipers. Degenerative disease was hand graded in the spine, hips and knees using a previously described classification system. Power was set at 90%.

RESULTS

Average age was 56±10 years and average LLD was 4.8±4.0mm. Multiple regression analysis did not demonstrate any correlation between LLD and degenerative disease. After screening to find 26 additional specimens with LLD 10mm or greater, and assessing a potentially quadratic relationship, we still did not find any detrimental effects of LLD.

DISCUSSION

Our data support the general clinical recommendation of observation for mild asymptomatic LLD. These results do not apply to larger LLD nor LLD associated with other deformities or clinical symptoms.

LEVEL OF EVIDENCE

Not applicable, anatomic basic science study.

The Effects of Leg Length Discrepancy on Stability and Kinematics-Kinetics Deviations: A Systematic Review

Various studies have examined body posture stability, including postural sway and associated biomechanical parameters, to assess the severity effects of leg length discrepancy (LLD). However, various viewpoints have been articulated on the results of these studies because of certain drawbacks in the comprehensive analysis of the effect of variations in LLD magnitude. Therefore, this systematic review was performed to help focus on the current findings to help identify which biomechanical parameters are most relevant, commonly used, and able to distinguish and/or have specific clinical relevance to the effect of variations in LLD magnitude during static (standing) and dynamic (walking) conditions. Several electronic databases containing studies from the year 1983 to 2016 (Scopus, ScienceDirect, PubMed, PMC, and ProQuest) were obtained in our literature search. The search process yielded 22 published articles that fulfilled our criteria. We found most of the published data that we analyzed to be inconsistent, and very little data was obtained on the correlation between LLD severity and changes in body posture stability during standing and walking. However, the results of the present review study are in line with previous observational studies, which describe asymmetry in the lower limbs corresponding to biomechanical parameters such as gait kinematics, kinetics, and other parameters described during static (standing) postural balance. In future investigations, we believe that it might be useful to use and exploit other balance-related factors that may potentially influence body posture stability.

Leg Length Discrepancy: Dynamic Balance Response during Gait

Balance in the human body's movement is generally associated with different synergistic pathologies. The trunk is supported by one's leg most of the time when walking. A person with poor balance may face limitation when performing their physical activities on a daily basis, and they may be more prone to having risk of fall. The ground reaction forces (GRFs), centre of pressure (COP), and centre of mass (COM) in quite standing posture were often measured for the evaluation of balance. Currently, there is still no experimental evidence or study on leg length discrepancy (LLD) during walking. Analysis of the stability parameters is more representative of the functional activity undergone by the person who has a LLD. Therefore, this study hopes to shed new light on the effects of LLD on the dynamic stability associated with VGRF, COP, and COM during walking. Eighteen healthy subjects were selected among the university population with normal BMIs. Each subject was asked to walk with 1.0 to 2.0 ms-1 of walking speed for three to five trials each. Insoles of 0.5 cm thickness were added, and the thickness of the insoles was subsequently raised until 4 cm and placed under the right foot as we simulated LLD. The captured data obtained from a force plate and motion analysis present Peak VGRF (single-leg stance) and WD (double-leg stance) that showed more forces exerted on the short leg rather than long leg. Obviously, changes occurred on the displacement of COM trajectories in the ML and vertical directions as LLD increased at the whole gait cycle. Displacement of COP trajectories demonstrated that more distribution was on the short leg rather than on the long leg. The root mean square (RMS) of COP-COM distance showed, obviously, changes only in ML direction with the value at 3 cm and 3.5 cm. The cutoff value via receiver operating characteristic (ROC) indicates the significant differences starting at the level 2.5 cm up to 4 cm in long and short legs for both AP and ML directions. The present study performed included all the proposed parameters on the effect of dynamic stability on LLD during walking and thus helps to determine and evaluate the balance pattern.

The effect of simulated leg length discrepancy on lower limb biomechanics during gait

Understanding the effects of leg length discrepancy (LLD) on the biomechanics of gait and determining as to what extent of LLD alters gait is essential. A total of 91 biomechanical data were assessed from 14 lower limbs of healthy individuals walking under random conditions: shod only and with a 5, 10, 15, 20, 30 and 40 mm sole lift. Lower limb kinematics and dynamic leg length (DLL) were measured by a motion capture system. Hotelling's T-Square test was used to evaluate the differences in DLLs throughout the gait cycle in conjunction with differences between the sides based on the maximal stance phase and minimal swing phase DLLs. Kinematics were compared using the one-way blocked analysis of variance and Post-hoc analysis by the paired t-test. Significant dynamic shortening of the longer limb, mainly during the swing phase, and significant change in maximal stance and minimal swing phase DLL relationship started at a 10 mm lift condition (p < 0.05). Thirteen kinematic variables produced a significant angular main effect (p < 0.05), with a more flexed position of the longer limb and extended shorter limb beginning at a 5 mm lift. An increase in hip abduction and external foot rotation during the swing phase was also found. This study demonstrates that simulated LLD, as low as 5 mm, causes biomechanical changes in the lower limbs during gait revealed in both kinematics and dynamic leg length, suggesting that LLD, as small as 5-10 mm, should not be ignored.

Gait symmetry and hip strength in women with developmental dysplasia following hip arthroplasty compared to healthy subjects: A cross-sectional study

Introduction

Untreated unilateral developmental dysplasia of the hip (DDH) results in asymmetry of gait and hip strength and may lead to early osteoarthritis, which is commonly treated with a total hip arthroplasty (THA). There is limited knowledge about the obtained symmetry of gait and hip strength after the THA. The objectives of this cross-sectional study were to: a) identify asymmetries between the operated and non-operated side in kinematics, kinetics and hip strength, b) analyze if increased walking speed changed the level of asymmetry in patients c) compare these results with those of healthy subjects.

Methods

Women (18–70 year) with unilateral DDH who had undergone unilateral THA were eligible for inclusion. Vicon gait analysis system was used to collect frontal and sagittal plane kinematic and kinetic parameters of the hip joint, pelvis and trunk during walking at comfortable walking speed and increased walking speed. Furthermore, hip abductor and extensor muscle strength was measured.

Results

Six patients and eight healthy subjects were included. In the patients, modest asymmetries in lower limb kinematics and kinetics were present during gait, but trunk lateral flexion asymmetry was evident. Patients’ trunk lateral flexion also differed compared to healthy subjects. Walking speed did not significantly influence the level of asymmetry. The hip abduction strength asymmetry of 23% was not statistically significant, but the muscle strength of both sides were significantly weaker than those of healthy subjects.

Conclusions

In patients with a DDH treated with an IBG THA modest asymmetries in gait kinematics and kinetics were present, with the exception of a substantial asymmetry of the trunk lateral flexion. Increased walking speed did not result in increased asymmetries in gait kinematics and kinetics. Hip muscle strength was symmetrical in patients, but significantly weaker than in healthy subjects. Trunk kinematics should be included as an outcome measure to assess the biomechanical benefits of the THA surgery after DDH.