Rela%onship between Leg Length Discrepancy and Degenera%ve Spine, Hip and Knee Disease
Raymond W. Liu, M.D. Jonathan J. Streit, M.D. Jeremy D. Shaw, M.D.
Daniel R. Cooperman, M.D. Case Western Reserve University
Disclosure
• Orthopediatrics: Royal%es paid to my ins%tu%on – Direct research costs – Medical students to mee%ngs
Introduc%on • What amount of LLD is benign? – Gross (Orthopedics 1978): Pa%ents with <2cm LLD did not report clinical issues
– Goel et al (Am J Orthop 1997): Gait analysis showed no significant side-‐to-‐side differences with discrepancy up to 2cm
– Gurney et al (JBJS-‐A 2001): 2cm or higher LLD increased oxygen consump%on
– White et al (CORR 2004): LLD 1-‐3cm, shorter limb sustained greater propor%on of load
– Mahar et al (Arch Phys Med Rehabil 1985) Postural sway increase with discrepancy as low as 1cm
Methods
• Hamann Todd Osteological Collec%on • 600 (689) cadaveric skeletons • Ages 40-‐79 years • 83 female, 517 male • 187 black, 411 white • Exclusions – Obvious periar%cular trauma – Obvious metabolic disease – Incomplete skeletons
Methods
• Leg length discrepancy – Femoral length: superior aspect of femoral head to femoral condyles
– Tibial length: medial %bial plateau to medial %bial plafond
– Foot height not included
Methods
• Grading of degenera%ve disease – Spine: Grades 0 to 4 – Acetabulum, Proximal Femur, Distal Femur, Proximal Tibia: Grades 0 to 3 • Grouped into hip and knee joints • Grouped into long and short limbs
Spine Grading
0 4 3 2 1
Acetabulum Grading
0 3 2 1
Proximal Femur Grading
0 3 2 1
Distal Femur Grading
0 3 2 1
Proximal Tibia Grading
0 3 2 1
Results
• Kappa Inter-‐relator reliability: 20 specimens – Spine: 0.59 – Acet: 0.40 – Prox Fem: 0.22 – Dist Fem: 0.38 – Prox Tib: 0.23
Landis and Koch (Biometrics 1977) <0.00 Poor 0.00-‐0.20 Slight 0.21-‐0.40 Fair 0.41-‐0.60 Moderate 0.61-‐0.80 Substan%al 0.81-‐1.00 Almost Perfect
Results
• Average age: 56 ± 10 years • Average LLD: 5.0 ± 4.2 mm – Range 0 to 28.6 mm – 61 specimens between 10 and 20 mm
Results
Results
Results
• Mul%ple regression analysis – Analyzed by short and long limbs – Standardized Beta Age: 0.459 to 0.543 (significant) – Standardized Beta LLD: -‐0.020 to 0.001 • Nonstandardized Beta confidence intervals from -‐0.045 to 0.026 • No significance
– Males higher risk for spine arthri%s – African Americans at higher risk for knee arthri%s
Results
• 89 addi%onal specimens with LLD >1cm – Screened from 875 addi%onal specimens – S%ll no correla%on between LLD and degenera%ve joint disease
Valid and Powered?
• Validity of methodology – Strong correla%on with age – Reliability tests
• Power of study – Sensi%ve enough to detect effects of gender and race – Sta%s%cal confidence intervals
• Highest unstandardized beta was 0.026 for long knee • Corresponding unstandardized beta for age was 0.082 • 2cm LLD would equate to 6 years (drops to 5 years when adding 89 new specimens)
Conclusions
• A pure LLD of up to 2 cm does not appear to have any associa%on with degenera%ve disease of the spine, hips and knees
Thank You