Gait asymmetry in patients with limb length discrepancy

The Effect of Knee Height Asymmetry on Gait Biomechanics

BACKGROUND

Though the primary goal for limb length discrepancy (LLD) management is to equalize the leg lengths, symmetry between corresponding long bones is usually not achieved, leading to knee height asymmetry (KHA). To date, there is minimal information on what effect KHA has on gait biomechanics and joint loading. Thus, the purpose of this study is to determine the impact of KHA on gait biomechanics.

METHODS

Seventeen subjects with KHA after limb equalizing surgery and 10 healthy controls were enrolled. Subjects participated in 3D gait analysis collected using self-selected speed. Lower extremity kinematics, kinetics, work generated/absorbed, and total work were calculated. Standing lower limb x-rays and scanograms were used to measure LLD and calculate the tibia-to-femur (TF) ratio for each limb. Two sample t tests were used to compare differences in standing LLD, TF ratio, and work between groups. Bivariate correlation using Pearson correlation coefficients was conducted between TF ratio and total mechanical work, as well as between knee height asymmetry indices and total work asymmetry (α=0.05).

RESULTS

Among participants, there were no differences between LLD; however, there were differences between TF ratio and knee height asymmetry. We found a nonsignificant relationship between TF ratio and total mechanical work for individual lower extremities. Therefore, the length of individual bones (TF ratio) relative to each other within the individual lower extremity was not associated with the amount of work produced. However, when a difference exists between sides (asymmetry, ie, TF ratio asymmetry), there were associated differences in work (work asymmetry) produced between sides (r=0.54, P=0.003). In other words, greater knee height asymmetry between limbs resulted in more asymmetrical mechanical work during walking.

CONCLUSIONS

These findings may have implications for the management of LLD. Asymmetrical total mechanical work could lead to atypical joint loading during gait. Surgeons may want to consider prioritizing achieving knee height symmetry as a postoperative goal when correcting limb length discrepancy.

LEVEL OF EVIDENCE

Level III, Case Control Study.

Characterizing the Magnitude and Risk Factors of Functional and Anatomic Limb Lengthening in Patients Undergoing Revision Total Knee Arthroplasty

BACKGROUND

In revision total knee arthroplasty (TKA), there is little information on the magnitude of potential limb lengthening, risk factors for lengthening, or its impact on patient-reported outcome measures. We aimed to quantify limb length alteration during revision TKA and assess risk factors for lengthening.

METHODS

We identified 150 patients over a 3-year period who underwent revision TKA and had preoperative and postoperative EOS hip-to-ankle standing radiographs. The average patient age was 64 years, 51% were women; 68% had a preoperative varus deformity and 21% had a preoperative valgus deformity. Outcomes assessed included change in functional and anatomic limb length, risk factors for lengthening, and clinical outcome scores, including the Knee Osteoarthritis Outcome Score Joint Replacement, and the Veterans RAND 12-item Physical and Mental Scores.

RESULTS

There were 124 patients (83%) who had functional limb lengthening, and 108 patients (72%) had anatomic limb lengthening. Patients had an average functional limb lengthening of 7 mm (range, -22 to 35) and an average anatomic limb lengthening of 5 mm (range, -16 to 31). Patients undergoing revision for instability experienced significantly greater anatomic lengthening (7.6 versus 4.6, P = .047). Patients who had ≥ 10° of deformity were more likely to be functionally lengthened (91 versus 79%) and had significantly greater average functional lengthening (12 versus 6 mm; P = .003). There was no significant change in clinical outcome scores at 6 weeks and 1 year for patients lengthened ≥ 5 or 10 mm compared to those not lengthened as substantially.

CONCLUSIONS

There is major potential for functional and anatomic limb lengthening following revision TKA, with greater preoperative deformity and revision for instability being risk factors for lengthening.

Gait asymmetry in spatiotemporal and kinetic variables does not increase running-related injury risk in lower limbs: a secondary analysis of a randomised trial including 800+ recreational runners

Objective

To investigate asymmetry in spatiotemporal and kinetic variables in 800+ recreational runners, identify determinants of asymmetry, investigate if asymmetry is related to greater running injury risk and compare spatiotemporal and kinetic variables between the involved and uninvolved limb at baseline in runners having sustained an injury during follow-up.

Methods

836 healthy recreational runners (38.6% women) were tested on an instrumented treadmill at their preferred running speed at baseline and followed up for 6 months. From ground reaction force recordings, spatiotemporal and kinetic variables were derived for each lower limb. The Symmetry Index was computed for each variable. Correlations and multiple regression analyses were performed to identify potential determinants of asymmetry. Cox regression analyses investigated the association between asymmetry and injury risk. Analysis of variance for repeated measures was used to compare the involved and uninvolved limbs in runners who had sustained injuries during follow-up.

Results

107 participants reported at least one running-related injury. Leg length discrepancy and fat mass were the most common determinants of asymmetry, but all correlation coefficients were negligible (0.01-0.13) and explained variance was very low (multivariable-adjusted R2<0.01-0.03). Greater asymmetry for flight time and peak breaking force was associated with lower injury risk (HR (95% CI): 0.80 (0.64 to 0.99) and 0.96 (0.93 to 0.98), respectively). No between-limb differences were observed in runners having sustained an injury.

Conclusion

Gait asymmetry was not associated with higher injury risk for investigated spatiotemporal and kinetic variables.

Trial registration number

NCT03115437.

Acute effects of muscle mechanical properties after 2000-m rowing in young male rowers

Background

The mechanical properties of muscles, such as changes in muscle tone and stiffness, are related to sports performance and injuries. Rowers are at increased risk of muscle fatigue and injury during high-repetition and heavy-load cyclic muscle actions. In view of this, the aim of the present study was to investigate the acute effect on muscle tone and stiffness, as well as bilateral muscle asymmetry, in high school rowers after a 2000-meter rowing ergometer test.

Methods

Twelve young male rowers (age = 17.1 ± 0.9 years, body weight = 73.5 ± 9.7 kg) were included in the study. The data of muscle tone (frequency) and stiffness of the posterior deltoids (PD), latissimus dorsi (LD), and rectus femoris (RF) (dominant and non-dominant side) before and after a 2000-m rowing ergometer test were collected using a handheld MyotonPRO device.

Results

After the rowing ergometer test, the muscle tone of dominant side PD, LD, and RF were significantly increased (p < 0.05). On the other hand, the muscle stiffness of the non-dominant side LD and RF, as well as the dominant side PD, LD, and RF were significantly increased after the rowing ergometer test (p < 0.05). The muscle tone and stiffness results showed that the dominant side PD, LD, and RF were all significantly higher than the non-dominant side after the rowing ergometer test (p < 0.05), where bilateral PD and RF exhibits moderate asymmetry (5% < symmetry index < 10%).

Conclusions

After a high-intensity and high-load 2000-m rowing ergometer test, PD, LD, and RF showed increases in muscle tone and stiffness, as well as changes in the symmetry of bilateral muscle mechanical properties.

Effects of Artificially Induced Leg Length Discrepancy on Treadmill-Based Walking and Running Symmetry in Healthy College Students: A Lab-Based Experimental Study

Leg length discrepancy (LLD) is a common postural deviation of musculoskeletal origin, which causes compensatory reactions and often leads to injury. The aim of the study was to investigate the effect of artificially induced LLD on gait symmetry by means of the spatiotemporal gait parameters and ground reaction forces (GRFs) using a treadmill equipped with capacitive sensors (instrumented) as well as the EMG activity of trunk and hip muscles during walking and running. Twenty-six healthy male and female college students were required to perform two sets of four 2.5-min walking and running trials on an instrumented treadmill at 5.6 and 8.1 km·h-1, respectively, without (0) and with 1, 2, and 3 cm LLD implemented by wearing a special rubber shoe. Statistical analysis was performed using one-way repeated measures or a mixed-design ANOVA. Most spatiotemporal gait parameters and GRFs demonstrated an increase or decrease as LLD increased either on the short-limb or the long-limb side, with changes becoming more apparent at ≥1 cm LLD during walking and ≥2 cm LLD during running. The EMG activity of trunk and hip muscles was not affected by LLD. Our findings showed that gait symmetry in terms of treadmill-based spatiotemporal parameters of gait and GRFs is affected by LLD, the magnitude of which depends on the speed of locomotion.

Characteristics and Future Direction of Tibialis Posterior Tendinopathy Research: A Scoping Review

Background and Objectives: Tibialis posterior tendon pathologies have been traditionally categorized into different stages of posterior tibial tendon dysfunction (PTTD), or adult acquired flatfoot deformity (AAFD), and more recently to progressive collapsing foot deformity (PCFD). The purpose of this scoping review is to synthesize and characterize literature on early stages of PTTD (previously known as Stage I and II), which we will describe as tibialis posterior tendinopathy (TPT). We aim to identify what is known about TPT, identify gaps in knowledge on the topics of TPT, and propose future research direction. Materials and Methods: We included 44 studies and categorized them into epidemiology, diagnosis, evaluation, biomechanics outcome measure, imaging, and nonsurgical treatment. Results: A majority of studies (86.4%, 38 of 44 studies) recruited patients with mean or median ages greater than 40. For studies that reported body mass index (BMI) of the patients, 81.5% had mean or median BMI meeting criteria for being overweight. All but two papers described study populations as predominantly or entirely female gender. Biomechanical studies characterized findings associated with TPT to include increased forefoot abduction and rearfoot eversion during gait cycle, weak hip and ankle performance, and poor balance. Research on non-surgical treatment focused on orthotics with evidence mostly limited to observational studies. The optimal exercise regimen for the management of TPT remains unclear due to the limited number of high-quality studies. Conclusions: More epidemiological studies from diverse patient populations are necessary to better understand prevalence, incidence, and risk factors for TPT. The lack of high-quality studies investigating nonsurgical treatment options is concerning because, regardless of coexisting foot deformity, the initial treatment for TPT is typically conservative. Additional studies comparing various exercise programs may help identify optimal exercise therapy, and investigation into further nonsurgical treatments is needed to optimize the management for TPT.

Biomechanical evaluation and comparison of clinically relevant versus non-relevant leg length inequalities

BACKGROUND

Leg length inequalities are a frequent condition in every population. It is common clinical practice to consider LLIs of 2 cm and more as relevant and to treat those. However, the amount of LLIs that need treatment is not clearly defined in literature and the effect of real LLIs on the musculoskeletal system above and below 2 cm have not been studied biomechanically before.

METHODS

By using surface topography, we evaluated 32 patients (10 females, 22 male) with real LLIs of ≥ 2 cm (mean: 2.72 cm; n = 10) and compared their pelvic position and spinal posture to patients with LLIs < 2 cm (mean: 1.24 cm; n = 22) while standing and walking. All patients were measured with a surface topography system during standing and while walking on a treadmill. To compare patient groups, we used Student t-tests for independent samples.

RESULTS

Pelvic obliquity was significantly higher in patients with LLI ≥ 2 cm during the standing trial (p = 0.045) and during the midstance phase of the longer leg (p = 0.023) while walking. Further measurements did not reveal any significant differences (p = 0.06-0.706).

CONCLUSIONS

The results of our study suggest that relevant LLIs of ≥ 2 cm mostly affect pelvic obliquity and do not lead to significant alterations in the spinal posture during a standing trial. Additionally, we demonstrated that LLIs are better compensated when walking, showing almost no significant differences in pelvic and spinal posture between patients with LLIs smaller and greater than 2 cm. This study shows that LLIs ≥ 2 cm can still be compensated; however, we do not know if the compensation mechanisms may lead to long-term clinical pathologies.

Leg Length Discrepancy and Nonspecific Low Back Pain: 3-D Stereophotogrammetric Quantitative Posture Evaluation Confirms Positive Effects of Customized Heel-Lift Orthotics

Background: The literature reports evidence of leg length discrepancy (LLD) associated with musculoskeletal disorders, alterations in spinopelvic alignment, and body posture, leading to low back pain and lumbar scoliosis. The most common conservative treatment for LLD is the use of internal or external shoe lifts although no treatment guidelines have been established.

Aim: The study aimed to contribute to low back pain–LLD relationship comprehension, highlighting the benefits of LLD correction in the nonspecific low back pain (NSLBP) population.

Methods: A cross-sectional observational study recruited a cohort of 80 NSLBP patients (48 females, 32 males) with LLD, age (μ = 35 ± 17.2). Entire body posture, including 3-D spine shape reconstruction, was measured using a nonionizing 3-D optoelectronic stereophotogrammetric approach. After the first 3-D posture evaluation, patients were provided with customized orthotics, including 100% LLD heel lift correction. No other therapeutic interventions were considered. Pain level was assessed using the numerical pain rating scale (NPRS). The gender, age-related, and time-dependent effects of LLD equalization treatment in NSLBP patients was investigated during 2 years of follow-up. The statistical analysis was performed at the global level using multivariate methods by Hotelling T² tests and intrasubject-level using t-test.

Results and Discussion: An initial average NPRS = 7.8 was determined. In the medium-term follow-up group (4 months), the NPRS dramatically decreased (NPRS = 1.1). The pain disappeared in the long-term (2 years) follow-up group (NPRS = 0). The study results highlight that LLD equalization treatment led to clear statistically significant improvements in all the postural parameters of the frontal plane, including the underfoot load asymmetry. No worsening has been detected. An adaptation period long enough is needed to obtain progressive pain relief improvements and structural posture changes. Younger NSLBP patients showed slightly better improvements than older ones. Minimal differences between healthy young adults’ and NSLBP patients’ postures were found either in natural erect standing posture or when LLD equalization is applied.

Conclusion: Heel-lift customized orthotics with 100% LLD correction are an effective short- and long-term treatment in patients with nonspecific LBP, inducing pain symptom recession and stimulating the improvement of postural parameters without contraindications.

Effect of osteopathic manipulation on gait asymmetry

CONTEXT

Movement and loading asymmetry are associated with an increased risk of musculoskeletal injury, disease progression, and suboptimal recovery. Osteopathic structural screening can be utilized to determine areas of somatic dysfunction that could contribute to movement and loading asymmetry. Osteopathic manipulation treatments (OMTs) targeting identified somatic dysfunctions can correct structural asymmetries and malalignment, restoring the ability for proper compensation of stresses throughout the body. Little is currently known about the ability for OMTs to reduce gait asymmetries, thereby reducing the risk of injury, accelerated disease progression, and suboptimal recovery.

OBJECTIVES

To demonstrate whether osteopathic screening and treatment could alter movement and loading asymmetry during treadmill walking.

METHODS

Forty-two healthy adults (20 males, 22 females) between the ages of 18 and 35 were recruited for this prospective intervention. Standardized osteopathic screening exams were completed by a single physician for each participant, and osteopathic manipulation was performed targeting somatic dysfunctions identified in the screening exam. Three-dimensional (3-D) biomechanical assessments, including the collection of motion capture and force plate data, were performed prior to and following osteopathic manipulation to quantify gait mechanics. Motion capture and loading data were processed utilizing Qualisys Track Manager and Visual 3D software, respectively. Asymmetry in the following temporal, kinetic, and kinematic measures was quantified utilizing a limb symmetry index (LSI): peak vertical ground reaction force, the impulse of the vertical ground reaction force, peak knee flexion angle, step length, stride length, and stance time. A 2-way repeated-measures analysis of variance model was utilized to evaluate the effects of time (pre/post manipulation) and sex (male/female) on each measure of gait asymmetry.

RESULTS

Gait asymmetry in the peak vertical ground reaction force (-0.6%, p=0.025) and the impulse of the vertical ground reaction force (-0.3%, p=0.026) was reduced in males following osteopathic manipulation. There was no difference in gait asymmetry between time points in females. Osteopathic manipulation did not impact asymmetry in peak knee flexion angle, step length, stride length, or stance time. Among the participants, 59.5% (25) followed the common compensatory pattern, whereas 40.5% (17) followed the uncommon compensatory pattern. One third (33.3%, 14) of the participants showed decompensation at the occipitoatlantal (OA) junction, whereas 26.2% (11), one third (33.3%, 14), and 26.2% (11) showed decompensation at the cervicothoracic (CT), thoracolumbar (TL), and lumbosacral (LS) junctions, respectively. Somatic dysfunction at the sacrum, L5, right innominate, and left innominate occurred in 88.1% (37), 69.0% (29), 97.6% (41), and 97.6% (41) of the participants, respectively.

CONCLUSIONS

Correcting somatic dysfunction can influence gait asymmetry in males; the sex-specificity of the observed effects of osteopathic manipulation on gait asymmetry is worthy of further investigation. Osteopathic structural examinations and treatment of somatic dysfunctions may improve gait symmetry even in asymptomatic individuals. These findings encourage larger-scale investigations on the use of OMT to optimize gait, prevent injury and the progression of disease, and aid in recovery after surgery.

Intra and intersession repeatability and reliability of dynamic parameters in pressure platform assessments on subjects with simulated leg length discrepancy. A cross-sectional research

BACKGROUND

Leg length discrepancy (LLD) may play a key role in exercise biomechanics. Although the Podoprint platform has been used in dynamic pressure studies, there are no data regarding the reliability and repeatability of dynamic measurements under simulated LLD conditions.

OBJECTIVES

To determine the intra and intersession repeatability and reliability of dynamic parameters of the Podoprint pressure platform under simulated LLD conditions.

DESIGN AND SETTING

Observational cross-sectional study at a public university.

METHODS

Thirty-seven healthy volunteers participated in this study. LLD was simulated using ethyl vinyl acetate plantar lifts with heights of 5 mm, 10 mm, 15 mm and 20 mm located under the right shoe of each volunteer. The procedure was performed to capture the dynamic parameters of each participant under five different simulated LLD conditions. Stance time, mean pressure and peak pressure measurements were registered in three trials for each foot and each LLD level. Data were collected during two separate testing sessions, in order to establish intrasession and intersession reliability.

RESULTS

The intraclass correlation coefficients (ICCs) for intrasession reliability ranged from 0.775 to 0.983 in the first session and from 0.860 to 0.985 in the second session. The ICCs for intersession reliability ranged from 0.909 to 0.990. Bland-Altman plots showed absence of systematic measurement errors.

CONCLUSIONS

The results from this study indicate that the Podoprint platform is a reliable system for assessing dynamic parameters under simulated LLD conditions. Future studies should evaluate plantar pressures under LLD conditions, in association with exercise, biomechanics and musculoskeletal disorders.

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.

Increase in foot arch asymmetry after full marathon completion

Long-distance running results in lowering of the foot medial longitudinal arch, but it is unknown whether the left and right arches decrease equally. This study aimed to determine whether foot arch asymmetry increases upon completion of a full marathon and to identify factors capable of explaining the degree of asymmetry of navicular height and navicular height displacement. The three-dimensional foot posture data of 74 collegiate runners were obtained using an optical foot scanner system before (PRE) and immediately after (POST) a full marathon. The navicular height and arch height ratio (normalised navicular height by foot length) of both feet significantly decreased from PRE to POST full marathon completion (44.3 ± 6.3 mm versus 40.8 ± 6.5 mm, 17.8 ± 2.5 versus 16.6 ± 2.7, respectively; p < 0.001, both). The asymmetry of the arch height ratio was significantly greater POST than PRE marathon. Multiple linear regression analysis indicated that the POST-race Asymmetry Index (AI) of navicular height was significantly predicted by the PRE-race AI of navicular height; navicular height displacement was predicted by PRE-race navicular height and the marathon time. Full marathon running induced increasing asymmetry and lowering of the medial longitudinal arch in runners.

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.

The effect of asymmetrical gait induced by unilateral knee brace on the knee flexor and extensor muscles

Asymmetrical stiff knee gait is a mechanical pathology that can disrupt lower extremity muscle coordination. A better understanding of this condition can help identify potential complications. This study proposes the use of dynamic musculoskeletal modelling simulation to investigate the effect of induced mechanical perturbation on the kneeand to examine the muscle behaviour without invasive technique. Thirty-eight healthy participants were recruited. Asymmetrical gait was simulated using knee brace. Knee joint angle, joint moment and knee flexor and extensor muscle forces were computed using OpenSim. Differences inmuscle force between normal and abnormal conditions were investigated using ANOVA and Tukey-Kramer multiple comparison test.The results revealed that braced knee experienced limited range of motion with smaller flexion moment occuring at late swing phase. Significant differences were found in all flexormuscle forces and in several extensor muscle forces (p<0.05). Normal knee produced larger flexor muscle force than braced knee. Braced knee generated the largest extensor muscle force at early swing phase. In summary, musculoskeletal modelling simulation can be a computational tool to map and detect the differences between normal and asymmetrical gaits.

Limb Lengthening after Primary Total Knee Arthroplasty: Customized Patient-Specific Instrumentation Does Not Affect Expected Limb Lengthening

Introduction

Expectations for limb length differences after TKA are important for patient perception and outcomes. Limb length discrepancies may occur due to postoperative leg length increases, which can lead to decreased patient functionality and satisfaction and even possible litigation. The purpose of this study is to examine the frequency and extent of limb lengthening among various preoperative deformities and between two different implant systems.

Methods

Preoperative and postoperative full-length standing radiographs were obtained between August 2018 and August 2019 to measure mechanical axis and limb length of operative limbs. Demographic information such as age, sex, and BMI was also collected. Patients were grouped into categories for pre- and postoperative subgroup analysis: valgus, varus, customized implant, and conventional implant. Regression analysis was performed to evaluate significant relationships.

Results

Of the 121 primary TKAs analyzed, 62% of the knees showed an increase in limb length after TKA, with an average lengthening of 5.32 mm. Preoperative varus alignment was associated with a mean lengthening of 3.14 mm, while preoperative valgus alignment was associated with a mean lengthening of 16.2 mm. Overall, there were no statistically significant differences in limb lengths pre- and postoperatively (p = 0.23) and no significant changes in limb length for any subgroup. Further, no variables were associated with limb length changes (p = 0.49), including the use of customized implants (p = 0.2).

Conclusions

Limb lengthening after TKA is common and, on average, occurs more significantly in valgus knees. No significant difference in limb lengthening could be demonstrated using customized over conventional implants. Preoperative counseling is important to manage patient expectations.

Inter-limb difference of mechanical work in limb length discrepancy

BACKGROUND

Limb length discrepancy (LLD) is common and is associated with musculoskeletal disorders. Selection of adaptation strategies, the side more susceptible to complications, and the relationships between LLD magnitude and musculoskeletal complications are unclear. To elucidate these ambiguities, studies on gait parameters in LLD have been conducted. However, studies on inter-limb difference of mechanical work in LLD are rare.

RESEARCH QUESTION

To investigate whether inter-limb differences in mechanical work in LLD and the relationship between LLD magnitude and mechanical work performed by each lower limb are significant.

METHODS

Thirty-seven participants with LLD and without neuromuscular disorders disturbing normal gait were included. Three-dimensional motion analysis was conducted to obtain data on mechanical work, including joint work and the individual limb method (ILM) work. Mechanical work performed by the longer and shorter limbs was compared using paired t-test. Relationships between LLD and mechanical work were investigated using correlation and multiple regression analyses in both limbs. Eighteen participants had LLD > 20 mm, large group (LG), and 19 had LLD < 20 mm, small group (SG). Data exploration was conducted for the effect of LLD severity (LG vs. SG) on mechanical work.

RESULTS

LLD showed significant inter-limb difference of mechanical work and negative correlations with positive and negative ILM work performed by the shorter limb. The shorter limb in SG performed significantly larger positive ILM work than the longer limb, whereas the longer limb in LG performed significantly larger negative ILM work than the shorter limb.

SIGNIFICANCE

LLD showed inter-limb difference of ILM work and different adaptation strategies between LG and SG. These differences attribute to the decrease in ILM work performed by the shorter limb with the increase in LLD. Mechanical work including ILM work should be included in future studies to prevent complications and development of treatment methods for LLD.

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.

Leg dominance as a determinant in laterality of lower extremity amputation in diabetic patients: retrospective study and literature review

Background/Aims

Diabetic patients with peripheral vascular manifestations often develop foot ulcers and sometimes have to undergo lower extremity amputation. This retrospective study investigated leg dominance and laterality of lower extremity amputation in diabetic, dysvascular amputees.

Methods

All patients who met the inclusion criteria had their medical records reviewed for their dominant side and a correlation with a side of amputation was analysed. This information is routinely obtained as part of the admission history. For the literature review, PubMed, Google Scholar, ScienceDirect and Cochrane Library were searched with no date restriction until February 2018. Relevant studies were included and analysed.

Results

Of all the patients (n=27), 16 had diabetes and of these, 12 (75%) had their dominant leg amputated.

Conclusions

The data and literature analysis suggest that diabetic, dysvascular patients' dominant legs may be at higher risk for amputation than the non-dominant side. Larger studies are needed to clarify the relationship between leg dominance and laterality of lower extremity amputation.

Limb length discrepancy after total knee arthroplasty: Unilateral versus bilateral, a comparative study at tertiary centre

INTRODUCTION

We conducted a prospective study to find out change in limb length (lengthening/shortening) after total knee arthroplsty in unilateral and bilateral total knee arthroplasty (TKA) because few literature is available regarding limb length discrepancy in TKA in comparison to total hip arthroplasty. Limb length discrepancy (LLD) may lead to low back pain and gait abnormalities.

MATERIAL AND METHODS

We divided 58 patients into two groups: Group A (28 patients) includes patients who underwent unilateral TKA and Group B (30 patients) includes patients who underwent bilateral TKA. We assessed the patients clinico-radiologically in terms of limb length (supine position), deformity, Sagital-flexion deformity/extensor lag, coronal - varus/valgus, range of motion, knee stability, patellar tracking and Hip-knee-ankle angle preoperatively and postoperatively.

RESULTS

In group A, mean limb length difference (operated limb gained length as compared to unoperated limb) was 1.11 cm. Out of 22 patients (78%) in whom limb length discrepancy was present, only 7 patients (31%) having limb length discrepancy perceived it. In group B, mean limb length difference was 1.03 cm. Fourteen patients (47%) in group B had LLD but none of them perceived it. Clinically 22 patients (78%) in group A and 14 patients (47%) in group B had LLD. Radiologically 25 patients (89%) in group A and 22 patients (73%) in group B had LLD. Out of the 7 patients who perceived LLD, all had LLD radiologically too.

CONCLUSION

We reckoned that limb length discrepancy is more common in unilateral TKA. Limb length discrepancy of 2 cm or more is perceived by the patients operated for unilateral TKA. But in bilateral TKA, none of the patient perceived LLD because in this group LLD was less than 2 cm. Limb length discrepancy may leads to dissatisfaction of the patients and poor functional outcome.

Vertical ground reaction force and knee muscle activation asymmetries in patients with ACL reconstruction compared to healthy individuals

PURPOSE

Gait analysis is an important index in the clinical treatment of people with anterior cruciate ligament (ACL) injury. Following unilateral ACL reconstruction (ACLR), the knee kinetic asymmetries are likely to affect the gait cycle. Therefore, the aim of this study was to examine the symmetries of vertical ground reaction force (vGRF) and select the knee muscle activity in gait cycles in participants with and without unilateral ACLR.

METHODS

In this cross-sectional study, vGRF and muscle activity data in difference gait cycles were collected from 56 male subjects (28 with unilateral ACLR and 28 healthy subjects) using force plate and electromyography (EMG), respectively. MATLAB software was used for data analysis and independent t test was employed to compare the two groups.

RESULTS

No significant difference was seen between the two groups in the variable of first peak force symmetry (n.s). However, there was a significant difference in the second-peak force symmetry index between the two groups (p ≤ 0.001). Regarding muscle activity symmetry in the braking phase of gait, a significant difference was observed in rectus femoris between the two groups (p ≤ 0.001), while no difference was seen in medial gastrocnemius and biceps femoris activity (n.s). In the propulsive phase of gait, there was a significant difference in medial gastrocnemius and biceps femoris muscles activity between the two groups (p ≤ 0.001), while no difference was found in rectus femoris muscle activity (n.s).

CONCLUSIONS

The results revealed that unilateral ACLR creates asymmetry in vGRF and muscle activities in different phases of the gait cycle. So, more attention should be paid to this problem in clinical settings, and also to the use of therapeutic interventions to reduce the amount of kinetic asymmetries.

LEVEL OF EVIDENCE

III.

Wearer-Prosthesis Interaction for Symmetrical Gait: A Study Enabled by Reinforcement Learning Prosthesis Control

With advances in robotic prostheses, rese-archers attempt to improve amputee's gait performance (e.g., gait symmetry) beyond restoring normative knee kinematics/kinetics. Yet, little is known about how the prosthesis mechanics/control influence wearer-prosthesis' gait performance, such as gait symmetry, stability, etc. This study aimed to investigate the influence of robotic transfemoral prosthesis mechanics on human wearers' gait symmetry. The investigation was enabled by our previously designed reinforcement learning (RL) supplementary control, which simultaneously tuned 12 control parameters that determined the prosthesis mechanics throughout a gait cycle. The RL control design facilitated safe explorations of prosthesis mechanics with the human in the loop. Subjects were recruited and walked with a robotic transfemoral prosthesis on a treadmill while the RL controller tuned the control parameters. Stance time symmetry, step length symmetry, and bilateral anteroposterior (AP) impulses were measured. The data analysis showed that changes in robotic knee mechanics led to movement variations in both lower limbs and therefore gait temporal-spatial symmetry measures. Consistent across all the subjects, inter-limb AP impulse measurements explained gait symmetry: the stance time symmetry was significantly correlated with the net inter-limb AP impulse, and the step length symmetry was significantly correlated with braking and propulsive impulse symmetry. The results suggest that it is possible to personalize transfemoral prosthesis control for improved temporal-spatial gait symmetry. However, adjusting prosthesis mechanics alone was insufficient to maximize the gait symmetry. Rather, achieving gait symmetry may require coordination between the wearer's motor control of the intact limb and adaptive control of the prosthetic joints. The results also indicated that the RL-based prosthesis tuning system was a potential tool for studying wearer-prosthesis interactions.

Effect of induced hindlimb length difference on body-mounted inertial sensor measures used to evaluate hindlimb lameness in horses

This study has investigated the immediate effect of induced hindlimb length difference on hindlimb lameness measured as differences in minimum (Pmin) and maximum (Pmax) pelvic heights in 16 horses trotting in a straight line and lungeing on both hard and soft surfaces with body-mounted inertial sensors. Hindlimb length differences were induced by applying an Easyboot Glue-on shoe to one hindlimb. Changes in Pmin and Pmax with induced hindlimb length difference were assessed with a two-way repeated-measures ANOVA with trial (straight, lunge with inside limb elevation, lunge with outside limb elevation) and surface (hard, soft) as within-subject factors. Change in Pmin, indicating an impact-type lameness, in the hind limb with the elevation, was significant in both the straight line and while lunging on both hard and soft surfaces. Change in Pmax, indicating pushoff-type lameness, in the opposite, non-elevated hind limb, was significant when trotting in a straight line but not while lunging.

Ground reaction force adaptation during cross-slope walking on railroad ballast

BACKGROUND

Walking on railroad ballast is a unique challenge for railroad workers and contributes to a large number of falls and slips. However, the characteristics of ground reaction force (GRF) when walking on ballast combined with a cross-slope condition are poorly understood.

RESEARCH QUESTION

How does the magnitude and temporal distribution of GRF change during walking on railroad ballast combined with a cross-slope condition?

METHODS

Eight experienced railroad workers walked with their self-selected speed on three surfaces (mainline ballast, walking ballast and no ballast) in both a level and cross-slope (7°) condition. The magnitude and time of occurrence of selected key features of the GRF were extracted from the force plate. A two-factor repeated measures ANOVA was used to determine the effect of surface and cross-slope condition.

RESULTS

The minimum anteroposterior GRF and the first peak of the normal GRF occurred earlier on mainline ballast and walking ballast than no ballast. The maximum anteroposterior GRF was smaller, but the first peak of the normal GRF was larger on walking ballast compared with no ballast. Additionally, the asymmetrically mediolateral GRFs were observed between upslope limb and downslope limb in the cross-slope condition, which were also significantly different from the level condition.

SIGNIFICANCE

Ballast combined with a cross-slope condition posed a higher requirement for dynamic control to prevent downslope slippage and body instability, which could increase the fall risk for railroad workers. Future studies should investigate interventions to improve dynamic balance and reduce foot slippage on ballast.

Effects of a corrective heel lift with an orthopaedic walking boot on joint mechanics and symmetry during gait

BACKGROUND

Orthopaedic walking boots are commonly prescribed following injury and surgery. The boot creates a leg length discrepancy which is thought to affect limb symmetry and gait mechanics. This study aimed to examine the effects of a corrective heel lift for the contralateral limb on the mechanics and symmetry of walking with an orthopaedic walking boot.

RESEARCH QUESTION

Does a corrective heel lift reduce biomechanical alterations and asymmetries caused by an orthopaedic boot during gait?

METHODS

Healthy males (n=17) walked with normal shoes (Shod), an orthopaedic boot (Boot), and a corrective heel lift on the contralateral limb to the boot (Lift). A 10-camera motion capture system (Vicon, 100Hz) and four force platforms (AMTI, 1000 Hz) recorded lower extremity biomechanics. Pairwise statistics tested for differences in hip and knee kinematics and kinetics, and a symmetry index quantified limb symmetry.

FINDINGS

The Boot affected the sagittal and frontal plane hip mechanics and transverse plane knee mechanics (p<0.05), and increased the asymmetry compared to the Shod condition. The Lift improved the symmetry of some measures but increased the frontal plane hip asymmetry compared to the Boot. However, introducing the Lift did not change all kinematic variables affected by the boot.

SIGNIFICANCE

The Lift reduced some of the asymmetries introduced by the Boot, but also introduced new asymmetry in the hip frontal plane motion. The leg length discrepancy caused by the boot is probably not the only cause of altered gait mechanics. Prescribing a heel lift to a patient with an orthopaedic walking boot should be based on the individual patient's needs.

Application of dynamic time warping algorithm for pattern similarity of gait

The purpose of this study was to investigate the effectiveness of dynamic time warping (DTW) in gait research. Participants in this study were consist of 10 males and 10 females. Equipment used for collecting the gait data of participants in this study was three-dimensional (3D) motion analysis system consisted of 8 infrared CCD cameras operated with a sampling frequency of 120 frames/sec. DTW program used in this study was made using the MATLAB and the normal operation of the DTW program was verified by comparison of result manually calculated and output by the DTW program. Flexion angle of the knee joint of both feet obtained by 3D motion analysis system was analyzed by the DTW program and symmetry index (SI) equation. Statistical analysis of the values obtained by DTW was performed by one-sample t-test in confidence interval (CI) 99%, 95%, 90%, 85%, and 80% each using the SPSS. The subjects’ left and right legs were compared 20 times, and other steps of the same foot were compared 20 times. In this study, DTW showed different results from SI which is generally used to test the similarity of gait. Compared to that of DTW, the threshold figure for similarity evaluation in SI, 10%, is considered too large/high. When the CI threshold figure of 95% was adopted in statistical analysis, DTW demonstrated a lower rate of judging two sequences as similar even in the case of normal gait. This study suggests that DTW can be used for the similarity test of gait research.

There are two sides to every story: implications of asymmetry on breast support requirements for sports bra manufacturers

This study aimed to investigate: (1) the prevalence and magnitude of breast movement asymmetry, (2) the interaction between static and dynamic breast asymmetry and (3) the influence of sports bras on breast asymmetry during running. Position data were collected from 167 females whilst treadmill running and then a sub-group of 12 participants in different bra conditions. Breast movement asymmetry existed in 89% of participants, with resultant static breast position asymmetry larger in participants displaying dynamic asymmetry. Asymmetry was most commonly caused (60% to 75%) by greater movement of the left breast. No significant relationships were found between asymmetry and bra size or breast pain. Sports bras reduced asymmetry prevalence from 75% to 33% of participants in the antero-posterior direction but only from 75% to 67% of participants in the infero-superior direction. The magnitude of range-of-motion asymmetry reduced from 67 mm with no bra to between 6 and 64 mm in-bra in the infero-superior direction, with the best performing bra incorporating encapsulating cups and adjustable straps and underband. It is recommended that sports bras allow underband and strap adjustment to facilitate individual breast support and that asymmetry is considered when designing and fitting bras, which could utilise resultant asymmetry measured statically.

Sensor-based equine gait analysis: more than meets the eye?

Quantitative gait analysis in the lame horse has gained in popularity, likely related to the potential to remove bias from the clinical decision-making process. Its implementation into clinical practice is, however, not without challenges. This review visits some of the challenges related to the use of thresholds and guideline values in the context of clinical decision making, as well as when applied to scientific studies based on relevant published studies: issues such as ‘normal day-to-day variation’, conformational asymmetry and the often limited number of parameters that are being quantified. Emphasis is put on outlining the basic underlying principles relating to head nod and hip hike, which are explained in the context of Newtonian mechanics associating reduced vertical acceleration of the upper body to reduced force production with the limb that is in contact with the ground during that time period. Further to quantifying what can be seen ‘by eye’, the review also visits phenomena such as asymmetries in weight bearing or pushoff and compensatory mechanisms, with emphasis on measurement of withers movement and thoughts about multilimb lameness. The review concludes with thoughts about additional parameters such as limb movement and movement of the thoraco-lumbo-sacral area, which may provide additional insights into lameness and poor performance but are at current less frequently included into clinical gait analysis in the horse.

The risk factors of early acetabular failure after bipolar hemiarthroplasty because of fracture of the femoral neck

BACKGROUND

The aim of this study was to evaluate the influence of leg length discrepancy in geriatric patients with early failure of bipolar hemiarthroplasty and to identify related failure patterns and risk factors.

METHODS

In this retrospective study, the risk factors of early acetabulum failure within 5 years of hemiarthroplasty for displaced femoral neck fracture were compared with a control group of patients who had implant survival for at least 5 years after hemiarthroplasty. The basic data, leg length discrepancy, femoral offset, and the shell size were evaluated.

RESULTS

Of all risk factors, there was a significant difference in increased leg length between the two groups. The mean difference in leg length was 7.8 ± 5.9 mm in the early acetabular failure group and -1.7 ± 6.2 mm in the control group. For an increase in leg length of >6 mm, the odds ratio of early acetabular failure was 25-fold greater when compared with the control group.

CONCLUSION

Increased leg length was significantly associated with early acetabular failure after bipolar hemiarthroplasty for femoral neck fracture among geriatric patients. It is critical to avoid increase in leg length after bipolar hemiarthroplasty.

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.

Effect of inherent tibial asymmetry on leg length discrepancy measurements after intramedullary nailing of comminuted femoral shaft fractures

Introduction: Locked intramedullary nailing (IMN) is the standard treatment for femoral shaft fractures in adults with high rates of union and relatively low rates of complications. Leg length discrepancy (LLD) after IMN of femoral shaft fractures is common, and is reported in 20–43% of cases. A known surgical challenge when trying to obtain equal leg lengths is comminuted fracture, which results in a loss of bony landmarks that guide reduction. The purpose of this study was to assess the effect of inherent tibial asymmetry on LLD measurements after IMN.

Methods: Postoperative CT scanograms were performed on 79 consecutive patients after locked IMN for comminuted femoral shaft fracture. Leg lengths were determined by measurements taken from the scout view of a CT scanogram. Calculations of discrepancy were made for both femurs, tibias, and total leg length. Assessment was also made on the frequency wherein the tibial discrepancy compounded the femoral discrepancy. In situations where a limb segment was exactly symmetric to the contralateral side, the total leg was not regarded as a having compounded asymmetry.

Results: Notable discrepancies were found in tibial length that significantly departed from the null of symmetry (p < 0.0001). Forty-two patients (53.2%) were found to have a tibial asymmetry of 3 mm or more, and 20 patients (25.3%) were found to exhibit a difference of 6.3 mm or more. Median femoral discrepancy was 5.3 mm and median tibial discrepancy was 3.0 mm. Seven patients were found to be asymmetric in total leg length as a consequence of underlying tibial asymmetry. Conversely, 11 patients benefited from their tibial asymmetry, which compensated for femoral asymmetry after IMN.

Conclusion: Tibial symmetry cannot be assumed. If not accounted for, inherent tibial asymmetry may influence LLD after IMN of femur fractures.

Gain of length-loss of strength? Alteration in muscle strength after femoral leg lengthening in young patients: a prospective longitudinal observational study

This study aimed to determine the alteration in maximum isokinetic torque in patients after intramedullary femoral leg lengthening. Thirty patients with a median leg-length discrepancy of 3.0 cm underwent femoral limb lengthening with an intramedullary motorized device. Maximum isokinetic, concentric torque of the extensors, and flexors of the knee was measured before (n=30) and 2 years after surgery (n=21). Postoperatively, a significant difference remained for the maximum isokinetic torque of the extensors (22%) between the lengthened and the normal leg, which might have been caused by muscle response to the distraction procedure itself in the form of higher stiffness, less immediate displacement, and inconsistent force relaxation properties. However, we provide evidence that physiotherapy after limb lengthening should focus on extensors to prevent loss of strength.

Decreasing an Offloading Device's Size and Offsetting Its Imposed Limb-Length Discrepancy Lead to Improved Comfort and Gait

OBJECTIVE

Patient adherence is a challenge in offloading diabetic foot ulcers (DFUs) with removable cast walkers (RCWs). The size and weight of an RCW, changes to gait, and imposed limb-length discrepancies may all discourage adherence. This study sought to determine whether RCW size and provision of a contralateral limb lift affected users' comfort and gait.

RESEARCH DESIGN AND METHODS

Twenty-five individuals at risk for DFUs completed several 20-m walking trials under five footwear conditions: bilateral standardized shoes, a knee-high RCW with shoe with or without an external shoe lift contralaterally, and an ankle-high RCW with shoe with or without an external shoe lift contralaterally. Perceived comfort ratings were assessed through the use of visual analog scales. Spatial and temporal parameters of gait were captured by an instrumented walkway, and plantar pressure was measured and recorded using pedobarographic insoles.

RESULTS

The bilateral shoes condition was reported to be most comfortable; both RCW conditions without the lift were significantly less comfortable (P < 0.01). In contrast to the ankle-high RCW, the knee-high RCW resulted in significantly slower walking (5.6%; P < 0.01) but greater offloading in multiple forefoot regions of the offloaded foot (6.8-8.1%; P < 0.01). Use of the contralateral shoe lift resulted in significantly less variability in walking velocity (52.8%; P < 0.01) and reduced stance time for the offloaded foot (2.6%; P = 0.01), but it also reduced offloading in multiple forefoot regions of the offloaded foot (3.7-6.0%; P < 0.01).

CONCLUSIONS

Improved comfort and gait were associated with the ankle-high RCW and contralateral limb lift. Providing this combination to patients with active DFUs may increase offloading adherence and subsequently improve healing.

Effect of a unilateral hind limb orthotic lift on upper body movement symmetry in the trotting horse

In trotting horses, movement asymmetry is associated with ground reaction force asymmetry. In humans, limb length differences influence contralateral force production. Here we investigate whether horses, in immediate reaction to limb length changes, show movement asymmetry adaptations consistent with reported force differences. Aim of this study was to quantify pelvic and compensatory head and withers movement asymmetry as a function of limb length changes after application of orthotic lifts. In this experimental study movement asymmetry of eleven trotting horses was calculated from vertical displacement of poll, withers, sacrum and left and right tuber coxae with inertial sensors. Horses were assessed in-hand under 5 conditions (all with hind limb boots): without orthotic lifts, and with a 15mm or 30mm orthotic lift applied to the left hind or right hind. A linear mixed model investigated the influence of orthotic lift condition (P<0.05, pairwise posthoc Bonferroni correction). Pelvic movement asymmetry showed increased pelvic downward movement during stance of the shorter limb and increased pelvic upward movement during and after stance of the longer limb (P<0.001) with asymmetry changes of 3-7mm (4-10mm) for 15mm (30mm) lifts. Hip hike (tuber coxae movement asymmetry) was unaffected (P = 0.348). Head and withers movement asymmetry were affected less consistently (2 of 3 respectively 1 of 3 head or withers parameters). The small sample size of the study reduced generalizability, no direct force measurements were conducted and only immediate effects of orthotic lifts were assessed with no re-assessments days or weeks after. Conclusions about mechanical consequences (weight bearing, pushoff) are based on published movement-force associations. Pelvic movement asymmetry with an artificial change in limb length through application of an orthotic lift indicates increased weight support with the shorter limb and increased pushoff with the longer limb. This may be of relevance for the management of horses with different hoof shapes between contralateral limbs, for example some chronically lame horse.

A study on the characteristics of standing posture of elderly women with sarcopenia in Korea

This study intended to analyze the characteristics of standing posture and factors related to sarcopenia of elderly women in Korea to provide basic data for the development of rehabilitation programs designed to prevent and control of the sarcopenia of elderly women. A total of 194 elderly women, aged over 65 years old, living in Gyeonggi-do, were selected to diagnose the presence of sarcopenia through bioelectrical impedance analysis (BIA) and muscle function test (gait speed and grip strength). The subjects were then distinguished into normal group (NG=92), presarcopenia group (PG=86), and sarcopenia group (SG=16); the standing posture of elderly women was captured with the three-dimensional (3D) imaging technique (PA200), and an analysis of variance (ANOVA) was carried out for the collected data through IBM SPSS Statistics ver. 23.0. The frontal measurements of standing posture, the pelvic level, R-patella center, and L-patella center, appeared with significant differences from each other whereas, the side measurements of standing posture, the R-earhole position, L-earhole position, R-shoulder position, L-shoulder position, R-pelvic angle, L-pelvic angle, R-knee position, and L-knee position, were also found with significant differences from each other. As a consequence, an intervention to be focusing on obese control was found necessary to prevent or to delay the presence of sarcopenia of elderly women. The positional displacement found from head, knee, and pelvis also necessitates the introduction of rehabilitation program customized for elderly women suffering the sarcopenia.

Comparing Gait with Multiple Physical Asymmetries Using Consolidated Metrics

Physical changes such as leg length discrepancy, the addition of a mass at the distal end of the leg, the use of a prosthetic, and stroke frequently result in an asymmetric gait. This paper presents a metric that can potentially serve as a benchmark to categorize and differentiate between multiple asymmetric bipedal gaits. The combined gait asymmetry metric (CGAM) is based on modified Mahalanobis distances, and it utilizes the asymmetries of gait parameters obtained from motion capture and force data recorded during human walking. The gait parameters that were used in this analysis represent spatio-temporal, kinematic, and kinetic parameters. This form of a consolidated metric will help researchers identify overall gait asymmetry by showing them if the overall gait symmetry is improving and avoid the case where one parameter's symmetry is improving while another is getting worse. The CGAM metric successfully served as a measure for overall symmetry with eleven different gait parameters and successfully showed differences among gait with multiple physical asymmetries. The results showed that mass at the distal end had a larger magnitude on overall gait asymmetry compared to leg length discrepancy. It also showed that the combined effects are varied based on the cancelation effect between gait parameters. The metric was also successful in delineating the differences of prosthetic gait and able-bodied gait at three different walking velocities.

Three-dimensional limb lengthening after total knee arthroplasty in a simulation study

OBJECTIVES

Limb lengthening after total knee arthroplasty (TKA) has been reported in some cases, all of which were evaluated using two-dimensional images. To our knowledge, no case has been evaluated using three-dimensional (3D) images. We investigated 3D limb lengthening after TKA.

METHODS

We simulated 100 varus knees using 3D templating software. Virtual TKA was performed to maintain the original joint line by conducting a measured-resection technique. We examined the relationships of 3D distance between the femoral head center and ankle center before and after TKA, degree of hip-knee-ankle angle (HKA) improvement, and degree of flexion contracture angle improvement.

RESULTS

All cases showed limb lengthening (average, 9.4 ± 6.0 mm). The coefficients of correlation with limb lengthening and the degree of HKA improvement and the degree of flexion contracture angle improvement were good (0.730 and 0.751, respectively). The correlation between the degree of total improvement (the degree of HKA improvement + the degree of flexion contracture angle improvement) and limb lengthening was strong (r = 0.896).

CONCLUSION

The expected limb lengthening when performing measured-resection TKA is expressed as 0.58 × (the degree of HKA improvement + the degree of flexion contracture angle improvement) mm and is a useful index.

Heat-Induced Limb Length Asymmetry Has Functional Impact on Weight Bearing in Mouse Hindlimbs

Limb length inequality results from many types of musculoskeletal disorders. Asymmetric weight bearing from a limb length discrepancy of less than 2% can have debilitating consequences such as back problems and early-onset osteoarthritis. Existing treatments include invasive surgeries and/or drug regimens that are often only partially effective. As a noninvasive alternative, we previously developed a once daily limb-heating model using targeted heat on one side of the body for 2 weeks to unilaterally increase bone length by up to 1.5% in growing mice. In this study, we applied heat for 1 week to determine whether these small differences in limb length are functionally significant, assessed by changes in hindlimb weight bearing. We tested the hypothesis that heat-induced limb length asymmetry has a functional impact on weight bearing in mouse hindlimbs. Female 3-week-old C57BL/6 mice (N = 12 total) were treated with targeted intermittent heat for 7 days (40 C for 40 min/day). High-resolution x-ray (N = 6) and hindlimb weight bearing data (N = 8) were acquired at the start and end of the experiments. There were no significant left-right differences in starting tibial length or hindlimb weight bearing. After 1-week heat exposure, tibiae (t = 7.7, p < 0.001) and femora (t = 11.5, p < 0.001) were ~1 and 1.4% longer, respectively, on the heat-treated sides (40 C) compared to the non-treated contralateral sides (30 C). Tibial elongation rate was over 6% greater (t = 5.19, p < 0.001). Hindlimb weight bearing was nearly 20% greater (t = 11.9, p < 0.001) and significantly correlated with the increase in tibial elongation rate on the heat-treated side (R² = 0.82, p < 0.01). These results support the hypothesis that even a small limb length discrepancy can cause imbalanced weight distribution in healthy mice. The increase in bone elongation rate generated by localized heat could be a way to equalize limb length and weight bearing asymmetry caused by disease or trauma, leading to new approaches with better outcomes by using heat to lengthen limbs and reduce costly side effects of more invasive interventions.

Combined capillary-venous-lymphatic malformations without overgrowth in patients with Klippel-Trénaunay syndrome

OBJECTIVE

Klippel-Trénaunay syndrome (KTS) is described in the literature as a complex syndrome characterized by various combinations of capillary, venous, and lymphatic malformations associated with limb overgrowth. In the first description by Maurice Klippel and Paul Trénaunay, tridimensional bone hypertrophy was believed to be the cause of limb enlargement. The purpose of this study was primarily to assess the presence of real bone hypertrophy as a cause of enlargement of the limb and to underline the rare presence of undergrowth of the affected limb in patients with KTS.

METHODS

A two-center retrospective review including 17 KTS patients with various combinations of capillary, venous, and lymphatic malformation affecting the lower limb was performed. Differences in limb dimension were evaluated clinically. Width and length discrepancy of the affected limb was measured with radiologic imaging.

RESULTS

We found an increase of length in the affected limb in 80% of the patients. The leg length discrepancy varied from 0.2 to 2.6 cm. The median leg length discrepancy was found to be 1.4 cm. Three patients had a reduced length of the affected limb. Girth enlargement of the affected extremity was noticed in 60% of the patients, and 2 of 17 patients had hypotrophy of the involved limb. Hypertrophy (an increase in both length and width) of the bone was found in none of our cases, and the circumferential enlargement of the affected extremity was related only to soft tissue enlargement.

CONCLUSIONS

In the literature, KTS is considered the prototype of overgrowth syndromes associated with complex vascular malformations. The majority of our patients showed limb length increase associated with soft tissue enlargement without an increase of bone width; there were also two patients with limb undergrowth. A real bone overgrowth (an increase in both length and width) was not present in our patients. Therefore, we could consider the absence of real bone hypertrophy as probably a new aspect of such confusing and controversial definitions of KTS. In addition, it would be more accurate to classify KTS patients on the basis of their phenotypic features (type of vascular malformation, types of overgrown tissue) rather than by use of an outdated eponym.

Do different methods for measuring joint moment asymmetry give the same results?

Gait asymmetry is defined as a loss of perfect agreement between the dominant and non-dominant lower limbs. Conflicting results from gait asymmetry studies may be due to different definitions of asymmetry, different research methods, and/or different variables and formulas used for asymmetry calculation. As a result, this makes it difficult to compare joint asymmetry values between studies. An accurate and precise understanding of asymmetry during human walking is an important step towards developing enhanced rehabilitation protocols for pathological gait. This study examined bilateral lower extremity joint moment asymmetry during the stance phase of walking using three different methods. Fourteen male children (with flat feet) aged 8-14 years participated in this study. The three-dimensional lower limb kinetics was evaluated during a comfortable gait. Then, right and left lower limb joint moments were used to calculate the joint moment asymmetry via three different methods (Lathrop-Lambach method: equation used by Lathrop-Lambach et al. (2014); Su method: equation used by Su et al. (2015); Nigg method: equation used by Nigg et al. (2013)). Repeated-measures ANOVAs (α = 0.05) were used to compare the values of net joint moment asymmetry calculated by the three methods. The results of the statistical analyses found that the amounts of moment symmetry between limbs calculated by the first two methods were significantly greater than that of using the Nigg method (except for the values of the frontal ankle moment computed by the Lathrop-Lambach method). Furthermore, in comparison of the first two methods, using the Su method showed a reduction in moment asymmetry for all joints and for all moments (p < 0.05). We conclude that, although all of three common methods for determining asymmetry between limbs have documented merit, they sometimes differ dramatically in results.

Combined effects of leg length discrepancy and the addition of distal mass on gait asymmetry

Asymmetries in gait often arise due to some form of physical impairment. For example, a leg length discrepancy (LLD) or the change of limb mass can result in asymmetric gait patterns. Although adding mass and LLD have been studied separately, this research studies how gait patterns change as a result of asymmetrically altering both leg length and mass at a leg's distal end. Spatio-temporal and kinetic gait measures are used to study the combined asymmetric effects of placing LLD and mass on the opposite and same side. There were statistically significant differences for the amount of mass and leg length added for all five parameters. Contrary to our hypothesis, there was no significant interaction between the amount of mass and leg length added. There were cases in all perturbations where a combination of mass and LLD make a gait parameter more symmetric than a single effect. These cases exhibit the potential for configurations with lower overall asymmetries even though each parameter has a slight asymmetry as opposed to driving one parameter to symmetry and other parameters to a larger asymmetry.

Kinematic gait pattern in children with cerebral palsy and leg length discrepancy: Effects of an extra sole

The gait pattern in children with cerebral palsy (CP) often differs from normal, with slow velocity, problem with foot clearance and increased stress on joints. Several factors, such as muscle tone, impaired motor control, muscle contractures, skeletal deformities and leg length discrepancy affect gait. Leg length discrepancy can be treated surgically or with elevation of the shoe on the short leg. The purpose of this study was to examine whether compensating for leg length discrepancy, with elevation of the sole, leads to a change in movement pattern during walking in children with spastic CP.

RESULTS

Ten children with spastic CP, able to walk without aids, and 10 typically developing (TD) children aged between seven and 14 years were assessed with 3D gait analysis: 1) barefoot, 2) with shoes and 3) with an extra sole beneath the shoe for the shorter leg. All children with CP had a leg length discrepancy of more than or equal to 1.0cm. In the barefoot condition, the velocity was slower and the stride length was shorter, in children with CP compared with TD. The stride length and gait velocity increased in children with CP with shoes and shoe+sole and the stance time became more symmetrical. Among children with CP, there was more flexion in the longer leg relative to the short leg during barefoot walking. Differences in the kinematic pattern between the long and the short leg decreased with the extra sole.

The effect of foot orthoses on joint moment asymmetry in male children with flexible flat feet

INTRODUCTION

It has been widely postulated that structural and functional misalignments of the foot, such as flat foot, may cause mechanical deviations of the lower limb during walking. The aim of this study was to investigate the effect of foot orthoses on lower extremity joint moment asymmetry during the stance phase of walking in children with asymptomatic flexible flat feet.

METHODS

Fourteen volunteer male children, clinically diagnosed with flexible flat feet, participated in this study. Subjects completed 12 walking trials at a self-selected walking speed while 3-dimensional kinematic and kinetic data were collected for two conditions: shod with no orthoses, and shod with orthoses. The gait asymmetry index for each variable for each subject was defined as: (1-(lesser moment/greater moment)) × 100.

RESULTS

Results reveal no significant differences in ankle or knee joint moment asymmetry. However, the use of foot orthoses decreased asymmetry for the hip abduction moment (P = 0.04) compared to walking without orthoses and also resulted in subtle, non-significant increases in frontal plane subtalar and sagittal plane knee and hip joints moment asymmetry.

CONCLUSION

We conclude that foot orthoses decrease frontal plane hip joint moment asymmetry, but have little effect on ankle and knee joint asymmetry.

Association of spinal deformity and pelvic tilt with gait asymmetry in adolescent idiopathic scoliosis patients: Investigation of ground reaction force

BACKGROUND

Adolescent idiopathic scoliosis is a prevalent orthopedic problem in children ages 10 to 16years. Although genetic, physiological and biomechanical factors are considered to contribute to the onset and progression of adolescent idiopathic scoliosis, the underlying mechanisms are not yet clear. The purpose of this study was to investigate the association between spinal deformity and inter-leg ground reaction force asymmetry during walking in adolescent idiopathic scoliosis patients.

METHODS

Fourteen patients (3 males and 11 females) participated in this study. Maximum Cobb's angle, adjusted Cobb's angle, and pelvic tilt were calculated from X-ray images. Asymmetry indices between legs were also calculated from ground reaction force magnitude and time variables from their preferred speed walking. Pearson coefficients of correlation were used to investigate associations of asymmetry indices with angle variables.

FINDINGS

Asymmetry indices of ground reaction force magnitudes positively correlated with adjusted Cobb's angle and maximum Cobb's angle mainly during the peak of braking phase, average of braking phase, while asymmetry indices of ground reaction force time variables showed no significant correlation with adjusted or maximum Cobb's angle. In contrast, asymmetry indices of ground reaction force time variables positively correlated with pelvic tilt during stance phase.

INTERPRETATION

We concluded that the spinal deformity of adolescent idiopathic scoliosis patients estimated using the maximum and adjusted Cobb's angles is generally associated with greater asymmetry of ground reaction force magnitudes in walking, while the pelvic tilt is associated with the greater asymmetry of ground reaction force time variables.

Biomechanical response to ankle-foot orthosis stiffness during running

BACKGROUND

The Intrepid Dynamic Exoskeletal Orthosis (IDEO) is an ankle-foot orthosis developed to address the high rates of delayed amputation in the military. Its use has enabled many wounded Service Members to run again. During running, stiffness is thought to influence an orthosis' energy storage and return mechanical properties. This study examined the effect of orthosis stiffness on running biomechanics in patients with lower limb impairments who had undergone unilateral limb salvage.

METHODS

Ten patients with lower limb impairments underwent gait analysis at a self-selected running velocity. 1. Nominal (clinically-prescribed), 2. Stiff (20% stiffer than nominal), and 3. Compliant (20% less stiff than nominal) ankle-foot orthosis stiffnesses were tested.

FINDINGS

Ankle joint stiffness was greatest in the stiffest strut and lowest in the compliant strut, however ankle mechanical work remained unchanged. Speed, stride length, cycle time, joint angles, moments, powers, and ground reaction forces were not significantly different among stiffness conditions. Ankle joint kinematics and ankle, knee and hip kinetics were different between limbs. Ankle power, in particular, was lower in the injured limb.

INTERPRETATION

Ankle-foot orthosis stiffness affected ankle joint stiffness but did not influence other biomechanical parameters of running in individuals with unilateral limb salvage. Foot strike asymmetries may have influenced the kinetics of running. Therefore, a range of stiffness may be clinically appropriate when prescribing ankle-foot orthoses for active individuals with limb salvage.

Change in Limb Length After Total Knee Arthroplasty

The clinical outcome of total knee arthroplasty (TKA) remains suboptimal in some patients. One of the factors that might hinder improved functionality may be postoperative limb length discrepancy due to increase in limb length of the operative limb. The objective of this cross-sectional prospective study was to examine the extent to which limb length change occurs after TKA and to compare the change in limb length to the degree of valgus or varus joint position preoperatively. The role of body mass index and Kellgren-Lawrence grade in limb length change was also assessed. The data of 137 TKAs were analyzed and separated into categories to compare change in limb length pre- versus postoperatively. In all, 59.1% of patients experienced an increase in limb length with an average increase of 0.438 cm, but overall, there was no statistically significant difference in limb length pre- versus postoperatively (P value 0.598). Similar trends were seen within all other groups. It is the conclusion of this study that limb lengthening after TKA does not frequently occur to a statistically significant extent, regardless of preoperative joint state.