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Leg Length Discrepancy

From WikiSM

Other Names

  • Leg Length Discrepancy
  • Limb Length Discrepancy
  • Acquired Leg Length Discrepancy
  • Congenital Leg Length Discrepancy
  • Idiopathic Leg Length Discrepancy
  • Anisomelia
  • Functional Leg Length Discrepancy

Background

  • This page refers to leg length discrepancy (LLD)

History

  • Needs to be updated

Epidemiology: Prevalence

  • Prevalence ≥ 1 cm
    • US/Swedish study found LLD present in over over third of the population[1]
    • Systematic review found 90% of the normal population had some type of variance in bony leg length, 20% with a difference > 9 mm[2]
  • Prevalence ≥ 1.5 cm
    • Among military recruits, leg length discrepancy of >1.5 cm was measured in 4% of cases[3]
  • Prevalence ≥ 2 cm
    • Not well established

Epidemiology: Incidence

  • Incidence ≥ 2 cm
    • French study found one per 1000 population had orthopedic treatment for LLD 2 cm[4]

Introduction

Left: Double-leg stance with equal weight distribution in the presence of leg length discrepancy. Right: Single-leg stance with balancing of the pelvis by the gluteal muscles.[5]
Changes by joint between the long leg and the short leg[6]
Structural (Anatomical) and Functional Causes of Leg Length Discrepancy[7]
Measuring the apparent and true length of the lower limb

General

  • Condition in which paired lower extremity limbs have a noticeably unequal length
  • Almost always the result of the shortening of one leg
  • Extraordinarily common however clinical significance is a matter of debate
  • Diagnosis is clinical and confirmed with radiographs
  • Widely accepted as a clinical condition, however little consensus in treatment
  • Controversial among researchers and clinicians includes extent to clinical significance, prevalence, accuracy of measurement, effect of LLD on function, role in numerous MSK conditions

Etiology: Acquired

  • Primary
    • As a result of loss of bone
  • Secondary
    • Traumatic or infectious epiphyseal injury in growing patients
    • Paralytic such as cerebral palsy, polio

Etiology: Congenital

  • Often termed idiopathic, meaning no other clear cause can be attributed
  • Affected leg is growing continuously slower than the normal leg[8]
  • Examples

Leg Elongation

  • Very rare, not the focus of this page
  • Associated with: hemihyperplasia (formerly hemihypertrophy), partial gigantism, Klippel-Trénaunay-Weber syndrome

Abnormal Growth, Hip Dysplasia and Scoliosis

  • Position of attention: weight equally distributed on both legs
  • LLD tilt to the side of the shortened leg
  • Consequences
    • Deterioration of femoral head containment
    • Lateral flexion of the spine
  • No data on how much of the day people are in double leg stance
  • Notion that "improper loading" has significant effects has been debated

Function, Limping and Athletic Ability

  • Gait analysis: LLD >1 cm can result in gait asymmetry[9]
    • As discrepancy increases, asymmetry and limping increase
  • In German sports
    • Permanent leg length discrepancy of ≥4 cm or ≥7 cm, depending on the type of sports, are considered a disability
  • Some experts suggest if LLD < 5 cm, practice sport without equalization of LLD with conservative measures
    • Shoe lift can change performance of sports shoes, making it impossible to engage in activity

Back Pain and Osteoarthritis

  • Unclear relationship between chronic back pain and LLD
  • Multiple studies have not identified LLD as a factor promoting the development of back pain[10]
  • Some patients have experienced improvement in back pain after prescribed shoe lifts
  • Knee Osteoarthritis
    • Cohort of 3000 patients showed association between LLD and Knee OA[11]
    • This was true for both the shorter and longer leg
  • Knee and Hip Osteoarthritis
    • Study looked at participants with LLD ≥ 2 cm[12]
    • Only association was found with knee osteoarthritis

Functional Leg Length Discrepancy

  • Unilateral asymmetry of the LE without any shortening of the osseous components
  • Causes
    • Shortening of soft tissues
    • Joint contractures
    • Ligamentous laxity
    • Axial malalignments
    • Foot biomechanics (such as excessive ankle pronation)
  • Can only be detected clinically, radiographs are normal
  • Can develop as abnormal motion of the hip, knee, ankle, foot in any plane of motion

Compensatory Structural Changes

  • Passive structural changes can compensate for LLD up to 2 cm
  • Examples
    • Pelvic torsion
    • Mild lumbar scoliosis
    • Facet angulation
    • Changes in muscle length

Associated Conditions

Risk Factors

  • Generally includes any risk to injuries of the
    • Spine
    • Hip Joint
    • Knee joint

Differential Diagnosis

  • Needs to be updated

Clinical Features

History

  • The vast majority of patients are asymptomatic
  • Patients may initially present with pain in the hip, knee or spin
  • Pain and fatigue
  • Sensation of instability as a result of component orientation and peri-articular muscle fatigue

Physical Exam

  • Block Testing/ Method
    • The Patient is standing
    • Place blocks under shorter limb until the pelvis is level
    • Total height of blocks can infer the LLD
    • Probably the best initial screening method
  • Tape Measurement
    • Considered controversial, accuracy has been questioned
    • Typically measure from ASIS to the medial malleolus
    • Recommend measuring 2 or 3 times and averaging
    • Have more than one person measure
  • Palpation of Bony Landmarks
    • Detect at the horizontal level, see if length inequality is present
    • Most commonly iliac crest or ASIS when standing

Special Tests

  • Needs to be updated

Evaluation

Measuring leg length discrepancy using the block method: Level pelvis is achieved by equalization with blocks of 4 cm in total height.[5]
Illustration of the tape measurement method measuring from ASIS to medial malleolus[13]
This was a patient presenting with an abnormal gait. The right femur measures approximately 41 cm, while the left femur is about 47 cm, resulting in a limb length discrepancy of roughly 6 cm. Internal fixation with an intramedullary metallic long rod and screws has been applied to the right femur. There is mild right coxa vara and slight internal bowing of the right femur.[14]

Clinical Diagnosis

  • LLD can be determined with an accuracy of ± 1 cm[15]
  • See: Block method, tape measurement above

Radiographs

  • Standing Full Leg Radiograph
    • aka Teleroentgenogram
    • Performed using the blocks method
    • Only necessary when surgical correction is being planned

Classification

Potential Classification

  • Mild (0-30 mm)
  • Moderate (30-60mm)
  • Severe (>60mm)

Pediatric

  • Static
    • Malunion of femur or tibia
  • Progressive
    • physeal growth arrest
    • congenital: absolute discrepancy increases, proportion stats the same

Management

Guide to the treatment of leg length discrepancy[5]

Decision to Treat

  • There are no clear, evidence guidelines to determine when to initiate treatment
  • The presence of a LLD does not automatically constitute an indication for treatment
  • The decision to treat should be decided on an individual basis, balancing potential risks and benefits
  • In growing children, measuring LLD only provides a snapshot
    • Treatment decisions should be primarily based on LLD after skeletal maturity

Nonoperative

  • Indications
    • Reserved for patients with LLD between 2 and 5 cm[16]
    • Do not need to achieve full equalization
    • Growing children: correct to 1 cm
    • Skeletally mature: correct to 2 cm
  • Insoles
    • Limited by shoe volume
  • Heel Wedge
    • Can correct by up to 2 cm
  • Sole Lift
    • Can correct up to 5 cm
  • Orthosis
    • Indicated for lift of ≥ 5 cm due instability with sole lift this big
    • Always lead to relative equinus, loss of function of the ankle

Operative

  • Indications
    • >2 cm and failure of conservative measures
  • Technique
    • Shortening osteotomy
    • Epiphysiodesis
    • Lengthening
    • Growth Arrest

Rehab and Return to Play

Rehabilitation

  • Needs to be updated

Return to Play/ Work

  • Needs to be updated

Prognosis and Complications

Prognosis

  • Needs to be updated

Complications

  • Incomplete arrest/ angular deformity
  • Pin site infections
  • Fracture
  • Delayed union
  • Premature cessation of lengthening
  • Persistent limb length discrepancy due to error in timing of surgery
  • Joint subluxation/dislocation
  • Mechanical axis deviation

See Also

References

  1. ↑ Brady, Rebecca J., et al. "Limb length inequality: clinical implications for assessment and intervention." Journal of Orthopaedic & Sports Physical Therapy 33.5 (2003): 221-234.
  2. ↑ Khamis, Sam, and Eli Carmeli. "A new concept for measuring leg length discrepancy." Journal of orthopaedics 14.2 (2017): 276-280.
  3. ↑ Hellsing, Anna-Lisa. "Leg length inequality: a prospective study of young men during their military service." Upsala journal of medical sciences 93.3 (1988): 245-253.
  4. ↑ Guichet, Jean-Marc, et al. "Lower Limb-Length Discrepancy: An Epidemiologic Study." Clinical Orthopaedics and Related Research (1976-2007) 272 (1991): 235-241.
  5. ↑ 5.0 5.1 5.2 Vogt, Björn, et al. "Leg length discrepancy—treatment indications and strategies." Deutsches Ärzteblatt International 117.24 (2020): 405.
  6. ↑ Image courtesy of physio-pedia.com
  7. ↑ Applebaum, Ariella, Adam Nessim, and Woojin Cho. "Overview and spinal implications of leg length discrepancy: narrative review." Clinics in Orthopedic Surgery 13.2 (2021): 127.
  8. ↑ Grill, F., M. Chochole, and A. Schultz. "Pelvic tilt and leg length discrepancy." Der Orthopade 19.5 (1990): 244-262.
  9. ↑ Khamis, Sam, and Eli Carmeli. "Relationship and significance of gait deviations associated with limb length discrepancy: A systematic review." Gait & posture 57 (2017): 115-123.
  10. ↑ Back pain and osteoarthritis
  11. ↑ Harvey, William F., et al. "Association of leg-length inequality with knee osteoarthritis: a cohort study." Annals of internal medicine 152.5 (2010): 287-295.
  12. ↑ Golightly, Yvonne M., et al. "Hazard of incident and progressive knee and hip radiographic osteoarthritis and chronic joint symptoms in individuals with and without limb length inequality." The Journal of rheumatology 37.10 (2010): 2133-2140.
  13. ↑ Beattie, Paul, et al. "Validity of derived measurements of leg-length differences obtained by use of a tape measure." Physical therapy 70.3 (1990): 150-157.
  14. ↑ Case courtesy of Mohammad walid Ahmad Amin, Radiopaedia.org, rID: 96654
  15. ↑ Woerman, Allyn L., and Stuart A. Binder-Macleod. "Leg length discrepancy assessment: accuracy and precision in five clinical methods of evaluation." Journal of Orthopaedic & Sports Physical Therapy 5.5 (1984): 230-239.
  16. ↑ Hefti, Fritz, et al. "Achsen und Längen." Kinderorthopädie in der Praxis (2014): 633-660.
Created by:
John Kiel on 29 August 2024 18:49:55
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Last edited:
24 May 2025 12:49:04
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