Limb Length Inequality: Clinical Implications for Assessment and Intervention

Abstract

The purpose of this paper is to review relevant literature concerning limb length inequalities in adults and to make recommendations for assessment and intervention based on the literature and our own clinical experience. Literature searches were conducted in the MEDLINE, PubMed, and CINAHL databases. Limb length inequality and common classification criteria are defined and etiological factors are presented. Common methods of detecting limb length inequality include direct (tape measure methods), indirect (pelvic leveling), and radiological techniques. Interventions include shoe inserts or external shoe lift therapy for mild cases. Surgery may be appropriate in severe cases. Little agreement exists regarding the prevalence of limb length inequality, the degree of limb length inequality that is considered clinically significant, and the reliability and validity of assessment methods. Based on correlational studies, the relationship between limb length inequality and orthopaedic pathologies is questionable. Stronger support for the link between low back pain (LBP) and limb length inequality is provided by intervention studies. Methods involving palpation of pelvic landmarks with block correction have the most support for clinical assessment of limb length inequality. Standing radiographs are suggested when clinical assessment methods are unsatisfactory. Clinicians should exercise caution when undertaking intervention strategies for limb length inequality of less than 5 mm when limb length inequality has been identified with clinical techniques. Recommendations are provided regarding intervention strategies. J Orthop Sports Phys Ther. 2003;33:221-234.

Changes in Pain and Disability Secondary to Shoe Lift Intervention in Subjects With Limb Length Inequality and Chronic Low Back Pain: A Preliminary Report

“…The tester palpated the greater trochanters and as many pelvic landmarks as possible (ie, iliac crests, anterior superior iliac spines, posterior superior iliac spines, and ischial tuberosities) to determine the existence of an LLI. 6 If an LLI was suggested by the asymmetry of at least 2 sets of landmarks (eg, greater trochanters and iliac crests), the masonite boards were placed under the foot of the suspected shorter limb until the examiner determined that the greater trochanters and other pelvic landmarks were level. Subjects with a suspected LLI equal to or greater than 6.4 mm (0.25 in), based on the indirect assessment method, were then scheduled for a radiograph to be performed on a separate day.…”

“…Several authors have recommended increments of 3.2 to 6.4 mm every 1 to 2 weeks. 5,6 The overall height of the full-length insert and/or heel lift did not exceed 9.54 mm (0.375 in) inside the shoe. A full-length lift was added to the plantar surface of the shoe of the shorter limb for subjects who required a lift greater than 9.54 mm (0.375 in).…”

“…Clinicians, therefore, should be cautious when determining interventions based on a clinically determined LLI of 5 mm or less. 6 Clinicians, however, should not rule out the possibility of an LLI in the absence of an LLI on clinical examination, especially if patients present with LBP associated with standing and reduced with sitting. Subjects in our study also did not report any significant limitation in walking.…”

“…30 Radiographic methods are the gold standard for measuring LLI, as compared to clinical methods. 6 Twenty-four subjects appeared to have an LLI of at least 6.4 mm (0.25 in), based on the clinical assessment of LLI. Only 15 (63%) subjects, however, demonstrated an LLI of at least 6.4 mm, based on radiographic assessment.…”

“…Shoe wear and orthotics have the potential to influence foot posture and, consequently, functional limb length. 6 The radiograph procedure for measuring LLI was modeled after procedures used by Brady et al 6 A carpenter's level was used to determine the levelness of the floor on which subjects stood during acquisition of the radiographs. Subjects were asked to stand with equal weight bearing on each limb, and with their knees fully extended, but not hyperextended.…”