Leg length discrepancies (LLD): An etiology to be considered in its proper measure. A critical and historical review

Abstract

Studies of leg-length discrepancies (LLD) have been the subject of debate for almost 200 years. A large number of studies have emerged, most frequently using assessment criteria based on painful symptoms or joint damage. While many authors argue for a threshold of 10-20mm to establish a link between pain and LLD, most publications based on radiography show lesion stigmata on lumbar, hip and knee joints as early as 6mm. This would be linked to comorbidities. Some studies argue forcefully that leg-length correction below 20mm is of no benefit. The authors of the present article, on the other hand, evoke the notion of lesion risks in the absence of correction, even for small deviations in the presence of certain associated factors and according to their importance. The authors argue for the need to define in the future a lesion significance score that would not be correlated to painful symptomatology, but rather to the presence of co-morbidities such as age, anatomical variability, sports practice and/or patients' professional activities. Other parameters, such as mobility, should also be taken into consideration, while gender, height and weight do not appear to be significantly related.