Measurement Techniques for Leg Length Discrepancy in Total Hip Arthroplasty: A Systematic Review of Reliability and Validity

J Arthroplasty. 2022 Dec;37(12):2507-2516.e11. doi: 10.1016/j.arth.2022.05.029. Epub 2022 May 21.

Abstract

Background: Total hip arthroplasty (THA) carries a substantial litigative burden. THA may introduce leg length discrepancy (LLD), necessitating a valid and reliable technique for LLD measurement. This study investigates the reliability and validity of techniques quantitively measuring LLD in both pre- and post-THA.

Methods: Embase and MEDLINE databases were searched following Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines for articles assessing either the validity or reliability of LLD measurement techniques. Data was pooled using random effects meta-analysis to derive reliability estimates. Study quality was assessed using the Brink and Louw checklist.

Results: Forty-two articles with 2059 participants were included. Thirty-three investigated reliability and 25 validity. Reliability displayed high heterogeneity. Poor to excellent intra-rater reliability was reported for antero-posterior pelvis radiographs, moderate to excellent for computed tomography scanograms, and good to excellent for clinical methods and teleradiography, and excellent for bi-planar radiography (BPR). Poor to excellent inter-rater reliability was reported for antero-posterior pelvis radiographs and clinical methods, moderate to excellent for teleradiography, good to excellent for computed tomography scanogram and excellent for BPR. The tape measure method is a valid clinical measure of LLD whilst markerless motion analysis and the block method are not. Imaging techniques are appropriately cross-validated with the exception of BPR.

Conclusion: The reported intra- and inter-rater reliability for most measurement techniques vary widely. The tape measure method is a valid clinical measurement of LLD. Imaging techniques have been appropriately cross-validated, with the exception of BPR, although they lack validation against a common reference technique.

Keywords: leg length discrepancy; measurement techniques; reliability; total hip arthroplasty; validity.

Publication types

  • Systematic Review
  • Meta-Analysis

MeSH terms

  • Arthroplasty, Replacement, Hip* / methods
  • Humans
  • Leg
  • Leg Length Inequality / diagnostic imaging
  • Radiography
  • Reproducibility of Results