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Leg Length Inequality. Implications for running injury prevention

Authors:
  • McCaw Biomechanics Consulting

Abstract and Figures

Leg length inequality is a relatively common musculoskeletal malalignment related to structural, postural and environmental factors. The inequality is a plausible aetiological factor in the development of a variety of overuse injuries because it alters the magnitude and distribution of mechanical stress within the body. Leg length inequality has been linked with lower extremity stress fractures, low back pain, hip pain and vertebral disk problems of runners. The appropriateness of using inshoe lifts to reduce or eliminate the inequality has not been rigorously evaluated. Further research is needed to quantify the biomechanical effects of leg length inequality as it interacts with other factors related to running injury.
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... In various studies, it was shown that LLIs can have a significant impact on the musculoskeletal apparatus. For example, LLIs can lead to hip pain in the longer leg [1,23,24]. This can be explained by an increase in pressure between the femoral head and the acetabulum caused by pelvic obliquity [23,25,26]. ...
... For example, LLIs can lead to hip pain in the longer leg [1,23,24]. This can be explained by an increase in pressure between the femoral head and the acetabulum caused by pelvic obliquity [23,25,26]. A further effect of LLIs is a decrease in the center edge angle of the hip joint, which can increase the risk for a femoro-acetabular impingement [25,27]. ...
... A further effect of LLIs is a decrease in the center edge angle of the hip joint, which can increase the risk for a femoro-acetabular impingement [25,27]. LLIs can also cause low back pain, which has been shown in multiple studies [2,23,24]. LLIs negatively affect the spine by causing a lumbar scoliosis, which is directed towards the shorter leg [1,2,23,28,29]. ...
Article
Background: Leg length inequalities (LLI) are a common problem in medicine. So far, the diagnosis and treatment are performed under static conditions. Surface Topography (ST) is an optical, non-invasive technique that uses the principle of triangulation to measure spinal posture and pelvic position. This technique offers the opportunity to detect and treat LLIs and their effects under dynamic conditions. Research: question The aim of the study is to show that ST can detect simulated LLIs under dynamic conditions and to prove if there are differences between the effects on the human body under static and dynamic conditions. Methods: In the clinical study a total of 30 test subjects were examined with a ST measuring device. LLIs (1 to 4 cm) were simulated using a custom- built sandal and insoles of various thickness. The pelvic obliquity, the surface rotation and lateral deviation of the spine were detected on a treadmill under static and dynamic conditions (3 km/h). Results: Under static and dynamic conditions LLIs lead to a significant increase of all measured parameters. The pelvic obliquity reaches a significant level of p < 0.0001 under static and p = 0.0001-0.0421 under dynamic conditions. However, for all examined parameters the magnitudes of the parameters under dynamic conditions were smaller than under static conditions. Significance: The study showed that simulated LLIs also have a significant effect on the human pelvis and spine under dynamic conditions, but with a smaller magnitude than under static conditions. The human individuum is a dynamic one. Because of that, for the future it should be of great interest to use dynamic measurements to detect and treat LLIs to provide an over correction of LLIs.
... Despite the reported disagreement regarding the prevalence of LLD [3,4], mild structural discrepancy has been reported to affect 90% of the adult population [5,6]. LLD causes changes in spino-pelvic alignment [5,7,8], body posture [1,9,10] and balance [11] by altering the distribution and magnitude of mechanical stresses and strains within the body [12]. ...
... Regarding its effect on pelvic posture, LLD induces pelvic motion in the sagittal and/or frontal plane with forward innominate bone rotation on the short limb and backward rotation on the long limb [7,12]. Differences in forward/backward rotation and leveling of both innominate bones may change the rotation and inclination of the sacrum that is located between them, producing alteration in the dynamics of the lumbar vertebrae and possibly developing low back pain and lumbar scoliosis with a convexity towards the short limb [8,10,13]. ...
... Discrepancies as small as 5 to 15 mm have been associated with osteoarthritis, low back pain, and knee injuries. [20][21][22][23][24][25] Pelvic obliquity associated with LLD can cause the spine to create compensatory curves and reduce hip coverage of the longer leg. The foot of the short leg can assume an equinus position, or the knee of the long leg can flex to equalize the pelvis. ...
Article
Introduction: Limb length discrepancy (LLD) is common in both the pediatric and adult population. Length inequalities can be due to a multitude of etiologies including congenital, developmental, and acquired causes. There has been little consensus on the morbidity of LLD and, as a result, the threshold necessary for treatment of LLD to prevent morbidity. Advances in magnetically controlled lengthening devices achieve greater accuracy and patient satisfaction and create an opportunity to lower the threshold for limb lengthening. Discussion: Asymptomatic LLD is relatively common in both pediatric and adult populations. Only ~10% of the population has equal leg length. LLD of <5 cm may lead to long-term morbidities such as scoliosis, lower back pain, gait abnormalities, stress on hip or knee joint, and lower extremity symptomatic versus asymptomatic osteoarthritis. The teaching in most orthopaedic textbooks is to adjust the shoe if symptomatic for discrepancies up to 2 cm; consider an orthotic, epiphysiodesis, or skeletal shortening for 2.5 to 5 cm; and possible limb reconstruction for >5 cm. The assumption is that there are no long-term consequences of mild LLD. However, data in recent literature show that small discrepancies may contribute to pathologic changes such as pain, gait abnormalities, and osteoarthritis. Major advances have been made in limb lengthening over the past 40 years. The increased accuracy and superior patient satisfaction of the magnetically controlled lengthening nail versus external fixation methods argue for including lengthening for LLD of <5 cm. Conclusion: If mild LLD can cause long-term pathology, it is important to counsel families on the full range of options for limb equalization no matter the size of the discrepancy. The evolution in technology and understanding of limb lengthening has provided additional safe surgical options. Therefore, the historic treatment protocol for addressing limb differences may need to include lengthening for smaller discrepancies even <2 cm.
... 16 Results of the present study 10 showed that individuals with an LLD had more knee and hip symptoms compared with those without an LLD, even when controlling for variables such as radiographic osteoarthritis and history of knee and hip problems. Other studies have also reported increased knee and hip symptoms in patients with an LLD, 5,9,20 and a study conducted by Giles and Taylor 8 observed back pain to be more common in those with an LLD of more than 10 mm. In this context, we hypothesized that patients using the limb length-evening orthotic might have decreased large joint and spine pain compared with patients who did not use the orthotic. ...
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Article
Background Patients are often made weightbearing as tolerated (WBAT) in a controlled ankle motion (CAM) boot for the management of various foot and ankle conditions. The CAM boot causes a leg length discrepancy (LLD) between the booted (longer) and contralateral (shorter) lower extremities. This discrepancy can potentially cause balance problems, undue strain on joints, and discomfort in patients. We hypothesized that a leg length–evening orthotic placed on the plantar aspect of the contralateral shoe improves balance among patients who are WBAT in a CAM boot. Methods Patients made WBAT in a CAM boot were randomized to either the leg length–evening orthotic intervention group or to a control group in which patients wore a normal shoe of their choice. Patients were followed for 2 weeks and asked a series of questions pertaining to balance and pain experienced at their knees, hips, and back. Balance was the primary outcome and was scored from 0 (no difficulty with balance) to 10 (great difficulty with balance). Of 107 subjects enrolled and randomized, 95 (88.8%) completed the study, satisfying the a priori sample size requirement of 94 patients. There were no differences in baseline characteristics between groups ( P > .05 for each). Results Intervention patients reported less difficulty with balance than control patients (intention-to-treat analysis: 2.0±1.5 vs 3.2±1.8, P = .001; as-treated analysis: 2.1±1.7 vs 3.0±1.7, P = .009). Intervention and control patients did not differ with respect to pain experienced at their knees, hips, or back, or in a composite total pain score ( P > .05 for each). Conclusion This multicenter randomized controlled trial found that adding a limb length–evening orthotic to the plantar aspect of the contralateral shoe in a patient that is WBAT in a CAM boot improved patient-reported self-assessment of balance. The trial was powered to identify a difference in the primary outcome measure of balance and may have been insufficiently powered to identify differences in knee, hip, back, or total pain. Level of Evidence Level II, prospective comparative study.
... 4 Among the results of asymmetry, McCaw describes stress fractures, back pain and knee joint pain. 5 Other studies have shown leg length discrepancy to be frequently associated with hip pain, sciatica, muscle fatigue. 6 The data in our study shows the presence of asymmetry (44%) between the right and the left tibial bone lengths. ...
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Article
Introduction: A wide variability of bilateral asymmetry in human has been observed within the population. However sufficient attention has not been given to the difference present in the limbs especially the tibial bones. It is generally assumed that the both limbs of the individual are with insignificant differences. The objective of the study is to find the prevalence of bilateral asymmetry of the tibial bone length of the same individual and distribution in between the two genders. Methods: This descriptive cross-sectional study was conducted on 150 students of Kathmandu Medical College and Teaching Hospital after obtaining ethical approval. Simple Random Sampling technique was used. The right and the left tibial length were recorded for different genders Results: Bilateral asymmetry in the tibial bone length was observed in 66 (44%) [41.58%- 46.42% at 95% CI] of the subjects which was recorded more in males 98 (65.15%) than in females. The minimum and maximum differences between the tibial length present was 0.1mm and 0.8 mm respectively with a mean of 0.2136 mm. Among the three age groups, tibial length asymmetry was observed highest 67 (45.56%) in Group B (20-22 years). Asymmetry in length was seen more in the right tibia with male preponderance over female. Conclusions: Asymmetry in the tibial bones length should be given proper attention and proper diagnosis and treatment of leg discrepancies should be done.
... The discrepancy is an aetiological factor in the development of a variety of overuse injuries as it alters the magnitude and distribution of mechanical stress within the body. LLD has been linked with lower extremity stress fractures, low back pain, hip pain and vertebral disk problems 8 It was noted that the majority of literatures main concern was about anatomical type of LLD while some other literatures gave more attention to functional abnormalities associated or isolated from LLD of real type, with recommendations for proper clinical assessment to distinguish between both types for accurate management [9][10][11] . The often functional abnormalities associated with LLD are over-pronation of one foot or imbalances within the pelvis itself with a high correlation with injury on the short leg side. ...
... 12 Rotation of the longer limb has also been implicated in progressive scoliotic curvature, which may lead to development of lower back pain. [21][22][23][24][25][26][27][28] Betsch et al 9 illustrated that an artificial leg-length inequality of just 15 mm can lead to changes in pelvic tilt, torsion, and spinal posture. Long-term effects of limb-length inequality include the development of arthritis of the hip and lower back pain. ...
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Article
Background Controlled ankle movement (CAM) walker boots may cause gait alterations and leg-length discrepancy. This study evaluates secondary site pain relating to immobilization in a CAM walker boot. Methods Patients wearing a CAM walker boot were prospectively enrolled and evaluated for new or worsened secondary site pain. Surveys at four time points were completed to evaluate secondary site pain severity and its effect on function. Results The study included 46 patients (mean age, 49 years). At transition out of the boot (mean, 4.2 weeks), 31 patients (67%) reported pain which was new or worse than at baseline. The sites most susceptible to pain were lower back, contralateral hip, and ipsilateral knee. Most pains (84%) began within the first 2 weeks of boot wear. Secondary site pain was less common after transition out of the boot: 18 patients (39%) at 1 month and 15 patients (33%) at 3 months. Conclusion Secondary site pain after CAM walker boot wear is common. The frequency and severity of pain lessened after transition out of the boot. Yet, one-third of patients still had new or worsened secondary site pain 3 months after cessation of boot wear.
Chapter
Auffälligkeiten im Kleinkind-, Kindes und Jugendalter können wie bei Säuglingen strukturelle aber auch funktionelle Ursachen haben. Entsprechend ist das therapeutische Vorgehen. Bei vielen Erkrankungen kann die Manualmedizin nur begleitend wirksam sein, wie viele Erkrankungen im Kopf-, Gesichts-, Wirbelsäulenbereich sowie zentralnervöse Krankheiten zeigen. An über 50 Beispielen wird die Vorgehensweise beschrieben.
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Background: Leg length discrepancy (LLD) can cause abnormal posture, muscle and/or joint pains, which leads to walking difficulties. The common treatment is to use a shoe lift on the shorter leg side, but this has unsatisfying results. Objective: Through research and development, we created 3D printing orthotic insoles for LLD patients and aimed to improve their symptoms. Methods: 1. Research and development of 3D printing orthotic insole: (1) foot scan and data acquisition; (2) insole software modeling; (3) 3D printing insole using TPU materials, and (4) post-processing. 2. Clinical observation: we customized insoles for LLD patients and required them to wear them while walking. We conducted general inquiries and a functional evaluation before and after 12 weeks of wearing insoles. Results: There are seven complete cases. The joint and lower back pains were alleviated. The stride frequency, stride and pace were improved in all seven cases. Patients' overall health condition improved significantly. Conclusions: The 3D printing orthotic insoles are made with clear procedures and practical operability. By wearing insoles, patients' muscle and/or joint pains were relieved and their gaits were improved.
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Five clinical methods of leg length discrepancy assessment were tested against one another for their relative accuracy and precision compared to exact anatomical standards as determined by radiograph. Five normal subjects, one with a known discrepancy of 1.3 cm, were evaluated by twenty physical therapists each using every method of assessment. T-tests and F-tests (a = 0.05) were used to determine statistical accuracy and precision among methods. Absolute values of mean differences, standard deviations, and ranges were used to determine clinical significance. The indirect method, which employed lift blocks under a foot with a subject in the standing position, proved to be the most accurate and precise method of any tested. Of the direct methods tested, which employ a tape measure between various anatomical landmarks, the technique shown to be the most accurate and precise utilized the landmarks of the anterior superior iliac spine and the lateral malleolus of the fibula.J Orthop Sports Phys 1984;5(5):230-239.
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This review article discusses the role of the hip abductor muscles in the generation of forces at the hip joint. The biomechanical rationale behind selected clinical principles of hip joint protection for the patient with hip osteoarthritis is discussed. These principles are based primarily on the benefit of reducing the magnitude of hip abductor muscle forces during walking. The specific hip joint protection principles that are analyzed are loss of body weight, walking with an antalgic limp, the use of a cane, proper methods of load carriage, and the reasons for certain orthopedic surgeries. The reduction of these myogenic hip joint forces for the patient with a painful hip and/or hip with arthritis should be considered an important component of the clinical management of the hip.
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In brief: This retrospective survey of the clinical records of 1,650 patients seen from 1978 to 1980 identified 1,819 injuries. Almost 60% of the patients were men, but women under age 30 had the greatest risk of overuse running injuries. The knee was the most commonly injured site, and patellofemoral pain syndrome was the most common injury. Most patients had moderate to severe degrees of varus alignment and subsequent overpronation. Because certain injuries were more frequent in one sex or the other, the authors say future studies should differentiate injuries by sex.
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The purpose of this paper is to discuss the classifications of leg length discrepancy (mild, moderate, and severe), to point out some of the clinical implications, and to outline the present concepts of treatment. While each of the causes of leg length discrepancy is relatively uncommon, as a group they represent a large block of orthopaedic problems which ultimately face the physiotherapist. An accurate clinical assessment of anisomelia, or leg length inequality, although difficult, is important, because many functional problems are, in fact, related to only minor discrepancies. These mild discrepancies, of up to 3 cm, have not been convincingly linked to specific pathology but when they are associated with pain syndromes, a therapeutic trial of correction may be fruitful. Moderate discrepancies, of between 3 and 6 cm, are associated with significant functional disturbances and, while orthotics may be expedient, in many cases will require surgical correction. For severe leg length discrepancies of more than 6 cm, a surgical correction of some form is indicated. In such cases the physiotherapist plays an important role in restoring function. In addition to traditional orthotic and surgical treatments, there is currently some exciting work being done on methods of stimulating the growth-plate, a technique which would be an ideal method of correcting leg length discrepancies.
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In brief: Most information about running injuries comes from case reports. Although useful, the case series does not take into consideration the population from which the injuries arose and is therefore an inappropriate method on which to base causal inference. The epidemiological method is a more powerful approach because, by definition, it takes into account the population from which the injuries arose. A review of three epidemiological studies shows that the only reasonably well-established cause of running injuries is the number of miles run per week. More information is needed to establish the relationship between injury and characteristics of the runner, characteristics of running, and characteristics of the running environment. More research on the causes of running injuries is needed and should be directed to those factors over which the runner has control.
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The effect of leg length inequality (LLI) on the mechanics of posture and gait is not clearly understood. The purpose of this study was to assess the concordance between LLI and bilateral asymmetry in the vertical impact ground reaction force during running. Three male runners (training more than 20 km/week and injury-free for more than 2 months) volunteered as subjects. 25 trials of ground reaction force data (500Hz) were collected for each foot in two sessions one week apart. The results suggest a concordance between LLI and impact loading asymmetry in runners.
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The purpose of this study was to extend our knowledge of running related injuries by determining whether relationships exist between selected anthropometric, biomechanical, muscular strength and endurance, and training variables and runners afflicted with patellofemoral pain (PFP). Specifically, the objectives of this study were to examine differences in selected measures between a non-injured control group (C) of runners (N = 20) and a group of injured runners (INJ) diagnosed by an orthopedic surgeon as having PFP (N = 16). High speed photography, a force platform, and isokinetic dynamometry were used to determine rearfoot motion, ground reaction forces, and knee muscular strength and endurance. Stepwise discriminant function analyses were performed on the anthropometric, biomechanical, and muscular strength and endurance variables. Q angle was a significant discriminator (P less than 0.01) between the INJ and C groups. The muscular endurance data revealed several significant discriminators with the INJ subjects being weaker in knee extension endurance. Kinetic analysis revealed several significant discriminators whereas rearfoot movement variables were not good discriminators between the groups. The training data revealed that the INJ group ran significantly less (P less than 0.01) miles.wk-1 than the C group. Our results suggest that Q angle is a strong discriminator between runners afflicted with PFP and non-injured runners. In addition, several muscular endurance and kinetic variables may also be important components of the etiology of PFP.
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A review of the clinical records of two sports physicians identified 1,819 injuries in 1,650 running patients during a two-year period. Men comprised 59.8% of the total patients, and women under age 30 appeared to have the greatest risk of overuse running injuries. The knee was the most common site of complaint, accounting for 41.7% of all injuries. The least frequently involved areas were the lower back (3.7%) and upper leg (3.6% of total injuries). All anatomical regions were equally susceptible to injury in both sexes. Patellofemoral pain syndrome was the most frequent disorder, accounting for 25.8% of all injuries. Most patients had moderate to severe varus alignment and subsequent functional overpronation. Certain injuries were more frequent in one sex or the other, so we believe that our results should prompt other authors to differentiate incidence of injuries by sex in the future.