Anatomic Leg Length Discrepancy Research Articles

Anatomical leg length discrepancy in children: Can it be accurately determined using 3-D motion capturing?

BackgroundLeg length discrepancy (LLD) is common in youth and is cause by several conditions. Long leg X-rays is the gold standard technique of measuring LLD. It is highly accurate and reliable compared to clinical method, but expose the subject to radiation. Instrumented Gait Analysis (IGA) serves not only as a means to measure joint kinematics during gait but also as a valuable tool for assessing Leg Length Discrepancy (LLD) while standing.Research Question.The purpose of this study was to compare different methods of determining the LLD in paediatric population. We hypothesize that IGA using joint centres is more accurate and precise than the tape measurement. MethodsThirty-one patients with mean age 12.3 (SD=2.4) years were retrospectively included in the study. Their LLD varied between 0 and 36 mm. Three methods for determining LLD were compared to radiography using Bland-Altman analysis: 1. Tape measurement, 2. IGA, summarizing the distance from the spina iliaca anterior superior to the medial malleolus marker via the medial knee condyle marker. 3. IGA, summarizing distances between ankle, knee, and hip joints centres where the latter is calculated with different equations. ResultsThe IGA joints method performed better than the tape measurement or IGA markers method. The equations of Davis calculating the hip joint centre had the highest accuracy with mean difference to radiography of 0.7 mm (SD=6.3). The simple Harrington method resulted in a slightly reduced accuracy but higher precision 0.9 mm (SD=6.2). The Harrington method with leg length as input was less accurate 1.0 mm (SD=6.7), but was still considerably better than the tape measurement 1.8 mm (SD=7.0) or IGA markers method 1.1 mm (SD=11.5).Significance.Determining LLD with IGA using the distances between ankle, knee and hip joints centres is a feasible method that can be applied in clinical practice to calculate LLD.

Predictor index for anatomic leg length discrepancy as a screening tool for referral to tertiary care center of India

Predictor index for anatomic leg length discrepancy as a screening tool for referral to tertiary care center of India

Leg length discrepancy: A systematic review on the validity and reliability of clinical assessments and imaging diagnostics used in clinical practice.

BackgroundA variety of assessments to determine leg length discrepancy (LLD) is used in clinical practice and evidence about validity and reliability may differ.ObjectiveThe objective of this systematic review was to identify and describe the validity and reliability of different assessments and imaging diagnostics for the determination of LLD.Materials and methodsThe review was conducted following the recommendations of Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA). The databases Medline (PubMed) and Index to Chiropractic Literature were systematically searched. Studies regarding clinical assessments and imaging diagnostics for the diagnosis of LLD, which reported the clinimetric properties for assessment of LLD, were included and screened for methodological quality using the Quality Assessment of Studies of Diagnostic Accuracy (QUADAS-2) tool for validity studies and the Quality Appraisal of Diagnostic Reliability (QAREL) tool for reliability studies.ResultsThirty-seven articles on clinical assessments and 15 studies on imaging diagnostics met the eligibility criteria. Thirteen studies on the validity of clinical assessments and six studies on the validity of imaging diagnostics had a low risk of bias and low concerns regarding applicability for all domains. One study on the reliability of clinical assessments and one study on the reliability of imaging diagnostics had a low risk of bias. Main limitations were, that an analysis of sensitivity and specificity was only performed in a few studies and that a valid reference standard was lacking in numerous studies on clinical assessments.ConclusionsFor the clinical assessment of LLD, the block test appears to be the most useful method. Full-length standing anteroposterior radiography seems to be the most valid and reliable method and may be used as global reference standard to measure the anatomic LLD when comparing clinical methods and imaging diagnostics.

Une inégalité de longueur symptomatique après une arthroplastie totale de la hanche est-elle associée à l’apparition de douleurs lombaires ?

BackgroundLeg 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. HypothesisLLD after THA is associated with lower back pain. Materials and methodsSeventy-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. ResultsPostoperative 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). ConclusionsSymptomatic 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 evidenceIV.

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

BackgroundLeg 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. HypothesisLLD after THA is associated with lower back pain. Materials and methodsSeventy-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. ResultsPostoperative 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). ConclusionsSymptomatic 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 evidenceIV.

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

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. To assess the capability of the dynamic leg length (DLL) measurement in detecting the presence of anatomic LLD. 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. 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. DLL measurement is capable of detecting an anatomic leg length difference based on functional changes in leg length and functional discrepancy.

Preoperative Planning for Total Hip Arthroplasty for Neglected Developmental Dysplasia of the Hip.

Developmental dysplasia of the hip (DDH) is accompanied by morphological alterations on both the acetabular and the femoral side. Total hip arthroplasty (THA) provides effective treatment in cases of neglected DDH but requires elaborate preoperative planning. To determine the morphological changes resulting from the dysplasia, the anatomic acetabular position, the height of the femur head dislocation, the height of the femur head dislocation, and the combined anteversion must all be established. In addition, a vital and complicated process of strategizing leg length balance must be conducted in cases of severe DDH. Each type of leg length discrepancy (LLD), including bony and functional and anatomical LLD, should be evaluated in the context of the presence or absence of a fixed pelvic tilt. Moreover, with severe unilateral dislocated hips, a more inferior change in the original rotational center of the hip must be accounted for. Due to these multiple morphological changes, the accurate size of the prosthesis and the cup position are difficult to predict. In comparison with other methods, CT scan‐based 3‐dimensional templating provides the best accuracy. Despite the presence of anatomic alterations, various types of acetabular and femoral prostheses have been developed to treat hip dysplasia. Both cemented and cementless cups are used in DDH cases. In DDH accompanied by insufficient acetabular bone stock, a cemented cup combined with bone graft provides a reliable treatment. Monoblock stems can be used when the combined anteversion is less than 55°, and a modular stem system when this parameter is greater than 55°. Customized stems can be designed for DDH coupled with severe proximal femoral distortion. A ceramic‐on‐ceramic bearing is considered optimal for young DDH patients.

Correlation between Gait Asymmetry and Leg Length Discrepancy—What Is the Role of Clinical Abnormalities?

Reducing the effect of leg length discrepancy (LLD) on gait abnormalities while other abnormal conditions such as spasticity, joint contractures or weak muscle strength are exhibited is challenging. This study aimed to evaluate the impact of mild LLD on lower limb biomechanics, on participants with anatomic LLD with and without other clinical abnormalities. A motion capture system was utilized on 32 participants to measure lower limb kinematics and dynamic leg length (DLL) throughout the gait cycle, calculated as the absolute distance from the hip joint center, either to the heel, ankle joint center, or forefoot. The Pearson correlation coefficient found that LLD was associated with 5 kinematic variables only when LLD appeared with no other clinical abnormalities present (r = 0.574 – 0.846, p < 0.05). When clinical abnormalities were present, the random forest classification accuracy was lower (64% versus 80%), implying that the used kinematics are low predictors for anatomic LLD, revealing a higher asymmetrical clearance index (the difference between the maximal stance phase and the minimal contra-lateral swing phase DLL) and a different kinematic variable importance index. Clinical abnormalities in pathological gait will in all probability significantly affect gait deviations, affirming mild anatomic LLD as inconsequential. A functional measurement can offer a better estimate as to the side and extent of the functional discrepancy.

Prediction of mild anatomical leg length discrepancy based on gait kinematics and linear regression model

BackgoundLeg length discrepancy (LLD) can be related to different pathologies, due to an inadequate distribution of mechanical loads, as well as gait kinematics asymmetries resulted from LLD. Research questionTo validate a model to predict anatomical LLD (ALLD) based on gait kinematics. MethodsGait of 39 participants with different lower limb pathologies and mild discrepancy were collected. Pelvic, hip, knee and ankle kinematics were measured with a 3D motion analysis system and ALLD, femur discrepancy (FD) and tibia discrepancy (TD) were measured by a computerized digital radiograph. Three multiple linear regression models were used to identify the ability of kinematic variables to predict ALLD (model 1), FD (model 2) and TD (model 3). ResultsDifference between peak knee and hip flexion of the long and short lower limb was selected by models 1 (p < 0.001) and 2 (p < 0.001). Hip adduction was selected as a predictor only by model 1 (p = 0.05). Peak pelvic obliquity and ankle dorsiflexion were not selected by any model and model 3 did not retain any dependent variable (p > 0.05). Regression models predicted mild ALLD with moderate accuracy based on hip and knee kinematics during gait, but not ankle strategies. Excessive hip flexion of the longer limb possibly occurs to reduce the limb to equalize the LLD, and discrepancies of the femur and tibia affects gait cycle in a different way. SignificanceThis study showed that kinematic variables during gait could be used as a screening tool to identify patients with ALLD, reducing unnecessary x-ray exposure and assisting rehabilitation programs.

P 020 - Is gait asymmetry correlated to anatomic leg length discrepancy when abnormal clinical findings are also present?

Background: Plantarflexor structure is an important predictor of function in healthy, athletic, and some patient populations. Computational simulations are powerful tools capable of testing the isolated effects of muscle-tendon structure on gait function.Research Question: The purpose of this study was to characterize the sensitivity of plantarflexor muscle function based on muscle-tendon unit (MTU) parameters. We hypothesized that plantarflexor metabolics and shortening dynamics would be sensitive to MTU parameters.Methods: Stance phase of gait was simulated using a musculoskeletal model and computed muscle control algorithm. Optimal muscle fiber length, resting ankle angle, and tendon stiffness parameters were systematically changed to test these effects on plantarflexor metabolics, activation, and power. Dorsiflexor metabolics were also measured to determine the impact of the action of the antagonist muscle group.Results and Significance: Plantarflexor metabolic demands were 1.5 and 2.7 times more sensitive to optimal fiber length and resting ankle angle, respectively, compared to the effect of tendon stiffness. Increased resting ankle plantarflexion induced a large passive plantarflexion moment during early stance, which required non-physiologic dorsiflexor contractions. Conversely, longer optimal fiber and more neutral resting ankle angles increased the shortening demands of the plantarflexors. These findings highlight the importance of carefully selecting MTU parameters when modeling gait with musculoskeletal models, especially in pathologic or high-performance athlete populations.

Dynamic leg length asymmetry during gait is not a valid method for estimating mild anatomic leg length discrepancy

The purpose of this study was to test the validity of dynamic leg length discrepancy (DLLD) during gait as a radiation-free screening method for measuring anatomic leg length discrepancy (ALLD). Thirty-three subjects with mild leg length discrepancy walked along a walkway and the dynamic leg length discrepancy (DLLD) was calculated using a motion analysis system. Pearson correlation and paired Student t-tests were applied to calculate the correlation and compare the differences between DLLD and ALLD (α = 0.05). The results of our study showed DLLD is not a valid method to predict ALLD in subjects with mild limb discrepancy.

Detecting Anatomical Leg Length Discrepancy Using the Plug-in-Gait Model

Leg length discrepancy (LLD) is a significant factor influencing several pathological conditions. Gait analysis is based on biomechanical gait models calculating joint kinematics; however, no previous study has validated its ability to detect anatomical LLD. The aim of the present study was to compare the validity of the Vicon® Plug-in-Gait-model (PGM) in measuring femur and tibia segmental length discrepancy with measurements attained by X-ray. Fifteen participants with suspected leg length discrepancies underwent a lower limb X-ray and a standing calibration trial using a motion analysis system (Vicon®, Oxford Metrics, UK). Femur and tibia segment lengths were deducted from both measurements. No differences were found when measuring the discrepancies between sides for the femur (p = 0.3) and tibia (p = 0.45) segmental length. A high correlation was found between methods (r = 0.808–0.962, p &lt; 0.001), however, a significant difference was observed when measuring the femur and tibia length (p &lt; 0.0001). PGM was found to be a valid model in detecting segmental length discrepancy when based on the location of the joint centers compared to X-ray. A variance was noted in the femur and tibial segmental length. The impact of this inconsistency in segmental length on kinematics and kinetics should be further evaluated.

Equalisation of leg lengths in total hip arthroplasty for patients with Crowe type-IV developmental dysplasia of the hip: classification and management.

There is no consensus about the best method of achieving equal leg lengths at total hip arthroplasty (THA) in patients with Crowe type-IV developmental dysplasia of the hip (DDH). We reviewed our experience of a consecutive series of patients who underwent THA for this indication. We retrospectively reviewed 78 patients (86 THAs) with Crowe type-IV DDH, including 64 women and 14 men, with a minimum follow-up of two years. The mean age at the time of surgery was 52.2 years (34 to 82). We subdivided Crowe type-IV DDH into two major types according to the number of dislocated hips, and further categorised them into three groups according to the occurrence of pelvic obliquity or spinal curvature. Leg length discrepancy (LLD) and functional scores were analysed. Type-I included 53 patients with unilateral dislocation, in which 25 (category A) had no pelvic obliquity or spinal deformity, 19 (category B) had pelvic obliquity with a compensated spinal curvature and nine (category C) had pelvic obliquity and decompensated spinal degenerative changes. Type-II included 25 patients with one dislocated and one dysplastic hip, in which there were eight of category A, 15 of category B and two of category C. Pre-operatively, there were significant differences between the anatomical and functional LLD in type-IB (p = 0.005) and -IC (p < 0.001), but not in type-IA, -IIA or -IIB. Post-operatively, bony LLD increased significantly in types-IB, -IC and -IIB, whereas functional LLD decreased significantly in each type except for IIA. The mean functional LLD decreased from 30.7 mm (standard deviation (sd) 18.5) pre-operatively to 6.2 mm (sd 4.4) post-operatively and the mean anatomical LLD improved from 35.8 mm (sd 19.7) pre-operatively to 12.4 mm (sd 8.3) post-operatively. Pelvic and spinal changes are common in patients with Crowe type-IV DDH and need to be taken into consideration when planning THA, in order to obtain equal leg lengths post-operatively. The principal subdivisions of Crowe type-IV DDH which we describe proved effective in achieving equal leg lengths and satisfactory outcomes. Cite this article: Bone Joint J 2017;99-B:872-9.

Differences in leg length discrepancy and weight distribution between the healthy and unhealthy sides of hemiplegic stroke patients

Weight distribution is often measured for the evaluation of balance. The present study was designed to evaluate the correlation between leg length discrepancy (LLD) and balance as measured by weight distribution after stroke. Twenty-two patients who were hemiplegic after stroke (twelve men and ten women) participated in this weight-distribution measurement and the LLD measurement study. A tape measure was used to measure LLD between the unhealthy and healthy sides. The balance was measured in three different positions (weight distribution while standing quietly, while sit to standing, and while in a maximal weight-shifting position) using the Messen Tairuieren Dokumentieren system. The degree of weight distribution on the unhealthy side was less than on the healthy side in all the positions. The functional and anatomical leg length discrepancy in the lower limb of the unhealthy side was longer than that of the healthy side. In all positions, these LLDs were significantly correlated with balance on the unhealthy side compared with that on healthy side. The present study in part found that after stroke, hemiplegic patients could become more unbalanced because of asymmetry in weight distribution and decreased limits of stability caused by leg length discrepancy.

Compensatory mechanisms of upper and lower body movements for anatomic leg length discrepancy

Compensatory mechanisms of upper and lower body movements for anatomic leg length discrepancy

Prevalence and functional impact of patient-perceived leg length discrepancy after hip replacement

The aim of this postal survey was to determine the prevalence and impact of patient-perceived leg length discrepancy (LLD) at 5-8 years after primary total hip replacement (THR). A postal audit survey was undertaken of all consecutive patients who had a primary unilateral THR at one elective orthopaedic centre between April 1993 and April 1996. The questionnaire included the Oxford hip score (OHS) and questions about LLD. Questionnaires were received from 1,114 patients. In total, 329 THR patients (30%) reported an LLD, although radiographic analysis revealed that only 36% of these patients had anatomical LLD. Patients with a perceived LLD had a significantly poorer OHS (p < 0.001) and reported more limping than those patients without a perceived LLD. This study found that a third of patients perceived an LLD after THR and that perceived LLD was associated with a significantly poorer midterm functional outcome.

Asymmetric limb loading with true or simulated leg-length differences.

Unequal leg lengths result in asymmetric limb loading but opinions vary on the size of the difference inducing abnormal loading, and which limb sustains the greater load. Our study compared limb-loading asymmetries during walking for subjects with anatomic leg-length discrepancies between 1.0 and 3 cm, subjects without length discrepancies, and for subjects with a simulated a 1.31-cm leg-length discrepancy. Symmetry indices were calculated for peak ground reaction force during weight acceptance, rate of change of weight acceptance force, peak push-off force, and rate of change of push-off force. All symmetry measures were significantly different from normal for the simulated leg-length discrepancy. The shorter limb sustained a greater proportion of the load and loading rate. The anatomic leg-length discrepancy group showed the same trend with the exception of the push-off force rate. There were equivalent size-effect differences for both leg-length discrepancy conditions; however, for the anatomic leg-length discrepancy group, only the weight acceptance force symmetry value was statistically different from normal. The shorter limb sustains a greater proportion of load and loading rates; therefore, equalizing leg lengths should be considered even with bilateral differences less than 3 cm.

The reliability and validity of the ‘Tape’ and ‘Block’ methods for assessing anatomical leg-length discrepancy

This study, following on from previous review papers, determined test reliability and validity within a clinical context. The chosen topic was the assessment of intra and inter-tester reliability as well as criterion validity (X-ray) for ‘Tape’ (TP) and ‘Block’ (BK) methods of leg length discrepancy (LLD) estimation. Four different testers using both TP and BK methods on two occasions within the same working day assessed 25 subjects. Two testers were designated as experienced (EX) and two as non-experienced (NEX). Intra-tester reliability was perfect for the BK method but demonstrated a range of variability, as assessed by typical error, for the TP method (range 0·17–0·32cm). One EX tester was more reliable than the other EX and both NEX testers. Inter-tester variability was assessed on the ability of different pairs of testers to categorize any left or right LLD as > or <0·5cm. Kappa coefficients were only moderate throughout but were generally larger for the BK method. Criterion validity for the most reliable tester (EX1) was assessed for both TP and BK methods on a sub-sample of subjects using regression analysis and suggested a closer match between TP and X-ray than between BK and X-ray measures. Whilst the intra-tester reliability data for the BK method is better than the TP method both approaches may be sensitive enough to differentiate ‘large’ clinically significant LLD with some confidence. Inter-tester reliability data suggests that the same tester should perform serial LLD estimations. Data for criterion validity must be viewed cautiously because of the sample size but suggests that the BK estimation produced a greater degree of error. The experience of the tester may impinge on the reliability of the estimation of LLD thus careful attention must be paid to training staff appropriately.