Measurement of Patient's Perception on Limb-Length Discrepancy Compared With Weight-Bearing Orthoroentgenography in Total Hip Arthroplasty: A Prospective Study.

BACKGROUND: Aims of this study included providing a comparison of the measurement of limb-length discrepancy after primary total hip arthroplasty between patient's perception and weight-bearing orthoroentgenographic measurement. A comparison between patient's perception and pelvic radiographic measurement was examined as well.

METHODS: This prospective study comprised patients who had already undergone total hip arthroplasty and were receiving postoperative outpatient care between April 2017 and July 2017. Block test was used to assess patient's perception on limb-length discrepancy. Weight-bearing orthoroentgenography and pelvic radiography were used for radiographic measurement. These 3 measurements were compared to find the difference, correlation, and reliability.

RESULTS: Evaluations were carried out on 68 patients subsequent to primary total hip arthroplasty. The prevalence of limb-length discrepancy by orthoroentgenographic, patient's perception, and pelvic radiographic measurements was 60%, 57.35%, and 52.94%, respectively. Mean difference of limb-length discrepancy between the 3 measurements were not statistically significant. When compared with orthoroentgenography, sensitivity and specificity of patient's perception measurement were 60.98% and 48.15%, respectively. Likewise, sensitivity and specificity of pelvic radiographic measurement were 78.05% and 85.19%, respectively. Poor correlation and reliability were found between orthoroentgenographic and patient's perception measurement (concordance correlation coefficient = 0.21, intraclass correlation coefficient = 0.22). However, good correlation and reliability were found between orthoroentgenographic and pelvic radiographic measurement (concordance correlation coefficient = 0.85, intraclass correlation coefficient = 0.85).

CONCLUSION: Patient's perception on limb-length discrepancy had poor correlation and reliability, low sensitivity and specificity when compared with orthoroentgenographic measurement. A physician should additionally perform measurement by orthoroentgenography or pelvic radiography.