INTEROBSERVER VARIABILITY IN LIMB LENGTH DISCREPANCY IN THR ON RADIOGRAPH - A MULTICENTRIC STUDY.

Abstract

Introduction: Restoration of limb length is one of the most important aims after total hip replacement . The measurement is often done by various radiological methods ,but its measurement is often difcult and variable. We studied to check if measurements of limb length discrepancy has interobserver variability using standard anteroposterior radiograph. Material and methods: Forty patients (40 hips) underwent measurement of limb length discrepancy on standard AP radiographs. The measurement was done by two observers from two different institutions (On digital X-ray AP view of hip, a line is drawn at the level of & parallel to inter teardrop area and intersecting the lesser trochanter on each side. Compare 2 points of intersection & measure difference to determine the amount of limb discrepancy). Results:There was excellent inter-observer agreement for radiological measurments kappa=0.867 (good aggrement) for pre-operative radiographic measurements and kappa=0.811(good aggrement) for post-operative radiographic measurements. Conclusions: Our data show use of radiological measurement of Limb Length Discrepancy (using intertear drop as pelvic reference and lesser trochanter as femoral reference) has excellent interobserver agreement and hence is more reliable than manual measurement of Limb Length Discrepancy