Incidence of knee height asymmetry in a paediatric population of corrected leg length discrepancy: a retrospective chart review study.

PURPOSE

The purpose of the study is to provide a methodology to quantify knee height asymmetry (KHA) and to establish the incidence of knee height asymmetry in a patient population visiting the limb length discrepancy clinic in a paediatric-orthopaedic hospital centre.

METHOD

A retrospective chart review was performed on all patients who attended the limb length discrepancy clinic and underwent corrective surgery at the Shriners Hospital for Children-Canada from December 2009 to December 2015. Full-standing anteroposterior radiographs were used to measure pre- and post-surgery limb length discrepancy and knee height asymmetry for 52 individuals included in the study.

RESULTS

Sixty-seven percent of the studied population had a KHA of 20 mm or less, 25% had a KHA between 20 and 40 mm, and 8% had a KHA of over 40 mm. The average KHA preoperatively for all 52 individuals was 17 ± 14 mm (range 0-59 mm), which represents roughly 2.5% of total limb length. There was a 3-mm non-significant reduction in KHA size between pre-and post-operative states (p = 0.22).

CONCLUSION

The current study provides a method to quantify knee height asymmetry. Using this method, it was shown that knee height asymmetry is frequent in youth with limb length discrepancy in both pre- and post-corrective surgery states. The relatively high incidence of knee height asymmetry highlights the importance to investigate the impact of knee height asymmetry in youth living with a limb length discrepancy.