Leg length discrepancy in total hip arthroplasty: comparison of two methods of measurement

Abstract

Measurement of leg length discrepancy is an important part in planning a successful total hip arthroplasty (THA). Many clinical and radiological methods with variable degrees of accuracy have been advocated to carry out this measurement. We studied the accuracy of a commonly used clinical method by comparing it to a well-known and reliable radiological method. A total of 139 patients aged 44-89 (mean: 67.5 years) scheduled to undergo THA were examined for clinical and radiological leg length discrepancy measurements before and after the operation by the same observers. There was a poor correlation between the clinical and radiological methods preoperatively [r =0.21, intra-class correlation coefficient (ICC)=0.33]. The correlation was better postoperatively (r =0.45, ICC=0.62). The clinical method used is not recommended for leg length discrepancy measurement preoperatively. Caution should even be taken when using this method postoperatively. The authors recommend using the radiological method when measuring leg length discrepancy as a part of planning for THA.Résumé Objectif: La mesure de l'inégalité de longueur est une part importante de la planification des prothèses totales de hanche. De nombreuses méthodes cliniques et radiologiques ont été utilisées pour permettre de telles mesures. Nous avons voulu étudier une méthode clinique habituelle comparée à une méthode radiologique fiable. Patients et méthode: 139 patients âgés de 44 à 89 ans (en moyenne 67,5 ans) devant bénéficier d'une prothèse totale de hanche ont été examinés sur le plan clinique et radiologique avec mesure de l'inégalité de longueur avant et après l'intervention chirurgicale par les mêmes observateurs. Résultats: il y a peu de corrélations entre les méthodes cliniques et radiologiques pré-opératoires (r =0.21, ICC=0.33). La corrélation est bien meilleure en post-opératoire (r =0.45, ICC=0.62). En conclusion, la méthode clinique n'est pas recommandée en pré-opératoire, elle doit être utilisée avec méfiance. En post-opératoire il est recommandé d'utiliser une méthode radiologique afin de mesurer l'inégalité de longueur des membres inférieurs. Celle-ci doit faire partie du planning d'une prothèse totale de hanche.

Clinimetric properties of observer‐assessed impairment tests used to evaluate hip and groin impairments: A systematic review

“…Nine studies investigated ROM (27)(28)(29)(30)(31)(32)(33)(34)(35), 6 studies measured muscle strength (12,29,31,36 -38), and 3 studies measured tenderness (11,29,36). Two studies each measured LLD (29,39), balance testing (33,37), and muscle length/flexibility (12,36).…”

“…Eleven studies investigated reliability (11,12,28 -34,36,37), 3 studies investigated validity (27,34,35,39), 1 study investigated internal consistency (38), and 1 study investigated both reliability and validity (34).…”

“…Complementary reviews evaluating patient-reported outcome questionnaires for measuring hip and/or groin dysfunction were recently published (14,15). In the current review, we identified 15 eligible studies from which 7 measurement properties were rated as good quality (11,30,31,33,35,37,39), 2 were rated as fair quality (34,38), and the remaining 6 were rated as poor quality (12,(27)(28)(29)32,36). The measurement properties assessed in these studies included internal consistency, intrarater reliability, interrater reliability, measurement error, construct validity, and criterion validity.…”

“…One good-quality study examined criterion validity of LLD measurements by comparing tape measure scores with radiologic measures in people with hip OA (39). The correlation was Ͻ0.50, both preoperatively (r ϭ 0.21) and after arthroplasty (r ϭ 0.45).…”

“…Measurement of LLD with a tape measure is not recommended as a valid measure in people with hip OA prior to hip arthroplasty, and caution should be exercised with this test postoperatively (39). Tape measures have routinely been used to assess LLD in clinical practice (44 -47).…”