Ipsilateral Healthy-segment Response to Leg Length Discrepancy.

BACKGROUND

Few studies address frequency or magnitude of healthy lower-extremity segment response to ipsilateral companion segment shortening. We sought to document and quantify this occurrence in a variety of pediatric etiologies.

METHODS

We reviewed the medical record and radiographs of patients undergoing epiphysiodesis to manage leg length discrepancy. Inclusion criteria for this study were leg length discrepancy of a single lower-extremity segment by identifiable cause and adequate scanograms to allow accurate measurement of all 4 lower-extremity segments before any surgical treatment for the discrepancy. We recorded the etiology of shortening, age of onset of disorder, the length of the lower-extremity segments on scanograms, and age at the time of radiographs. We considered ipsilateral healthy-segment difference from the contralateral ≥ 0.5 cm. as clinically significant.

RESULTS

Two hundred nine patients met inclusion criteria (126 boys, 83 girls). The average age was 12.5 years. 16/60 patients with avascular necrosis of the hip demonstrated ipsilateral tibial shortening averaging 1.2 cm whereas 6/60 demonstrated ipsilateral tibial overgrowth averaging 0.6 cm. 11/30 Legg-Perthés patients demonstrated ipsilateral tibial shortening averaging 0.7 cm; none had ipsilateral tibial overgrowth. 10/42 posteromedial bow patients had ipsilateral femoral shortening averaging 0.8 cm, whereas 6/42 had ipsilateral overgrowth averaging 0.8 cm. 13/48 with distal femoral physeal injury demonstrated ipsilateral tibial shortening averaging 1.2 cm, whereas 6/48 demonstrated ipsilateral tibial overgrowth averaging 0.8 cm. 8/29 tibial physeal injuries (proximal or distal) demonstrated ipsilateral femoral shortening averaging 1.1 cm. whereas 7/29 demonstrated ipsilateral femoral overgrowth averaging 0.7 cm.

CONCLUSIONS

Although there are individual exceptions, the ipsilateral healthy segment does not grow appreciably more than the contralateral in patients with avascular necrosis of the hip, Legg-Perthés disease, or physeal trauma. The femur is not a significant component of shortening in patients with posteromedial bow.

LEVEL OF EVIDENCE: Level III, retrospective review.