Medical Rationale
Total hip arthroplasty (THA) and significant hip injuries that alter joint architecture frequently produce iatrogenic or injury-related leg length discrepancy (LLD). Prosthetic component sizing, femoral offset changes, and acetabular cup positioning during THA commonly result in discrepancies of 5–20 mm, which may be intentional (to achieve soft-tissue tension) or inadvertent. Even small LLD (<10 mm) alters gait mechanics — the longer limb pronates excessively and absorbs increased ground reaction force, while the shorter limb develops a compensatory equinus posture. Biomechanical consequences of persistent LLD include ipsilateral lateral knee compartment overloading, contralateral hip abductor overload, lumbar scoliotic posturing with facet arthrosis, sacroiliac joint dysfunction, and trochanteric bursitis. Functional LLD from hip abductor weakness post-THA produces similar mechanical consequences.
Key Studies
White TO & Dougall TW (2002) J Bone Joint Surg Br (LLD after THA); Ranawat CS et al. (2001) Clin Orthop Relat Res (LLD and gait after THA); Konyves A & Bannister GC (2005) J Bone Joint Surg Br (functional outcomes and LLD); Gurney B (2002) Gait Posture (LLD biomechanical effects).
Filing Tips
Standing full-length radiograph (orthoroentgenogram or EOS scanogram) documenting actual limb lengths and the degree of discrepancy. Gait analysis or physical therapy documentation of compensatory ambulation strategies. Orthopedic or physiatrist nexus letter explicitly linking the THA or hip injury service connection to resulting LLD. File secondary conditions arising from LLD (knee pain, back pain, sacroiliac dysfunction) as additional secondary conditions under 38 CFR § 3.310.