Scanogram leg length measurement after total hip arthroplasty: not all landmarks are created equal
Brian T. N. Le, Yoan Bourgeault-Gagnon, Matthew C. Lyons, Samuel L. McCaffrey, Lucy J. Salmon, Michael D. O’Sullivan

TL;DR
This study shows that a common method for measuring leg length after hip replacement surgery overestimates discrepancies compared to an alternative technique.
Contribution
The study introduces an alternative measurement technique that avoids using the acetabular prosthesis as a landmark for leg length discrepancy.
Findings
The AA-TP method overestimated leg length discrepancy by 3.7 mm compared to the IT-TP method.
The odds of clinically significant LLD were 3.8 times higher with the AA-TP method.
Both methods showed excellent inter-rater and intra-rater reliability.
Abstract
To compare the magnitude of post-arthroplasty leg length discrepancy (LLD) and incidence of clinically significant LLD measured on CT scanogram using a commonly used measurement method (from the acetabular apex to tibial plafond) to an alternative technique avoiding the use of the acetabular prosthesis as a landmark and to assess inter-observer and intra-rater reliability of the new technique. In this retrospective study, post-arthroplasty LLD measurements were conducted in 100 hips by two interpreters on CT scanogram scout views from the acetabular apex to the tibial plafond (AA-TP) and the inter-teardrop line to the tibial plafond (IT-TP). Aggregate means and proportions of clinically relevant LLD (≥ 10 mm) were compared between methods. Inter-rater reliability was calculated, and both interpreters repeated measurements on ten randomly selected patients to calculate intra-rater…
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Taxonomy
TopicsOrthopaedic implants and arthroplasty · Total Knee Arthroplasty Outcomes · Orthopedic Infections and Treatments
