CT scanogram for limb length discrepancy in comminuted femoral shaft fractures following IM nailing

IntroductionLeg length discrepancy (LLD) following intramedullary nailing of femoral fractures is not uncommon. We designed a prospective study to evaluate the efficacy of routine postoperative computed tomography (CT) scanograms for evaluation of limb length discrepancy in patients with comminuted Winquist III or IV femoral shaft fractures treated with intramedullary nailing.MethodsThe study consisted of 15 patients with Winquist III and 13 with a Winquist IV femoral shaft fracture pattern with an average age of 37 years. The mechanisms of injury were motor vehicle collision (13), gunshot wound (12) and falls (three). All patients were treated with a statically locked intramedullary femoral nail (18 antegrade and 10 retrograde). A CT scanogram evaluated limb length in all patients. A discrepancy of greater than 20 mm was considered for correction during the same admission. An LLD of 15-20 mm was discussed with the patient extensively for correction.ResultsIn the 28 patients included in our study, the average limb length discrepancy was 9.1 mm with a range of −43.5 mm short to 10.3 mm long. The LLD was less than 10 mm in 18 patients (64%), 10-15 mm in four patients (14%), 15-20 mm in three patients (11%) and more than 20 mm in three patients (11%). Measurement of discrepancy as small as 0.5 mm showed that 18 patients were fixed with shortening and in 10 patients the operated femur was longer. Tibia lengths were also evaluated separately. Though none of the tibiae had a previous fracture, only three patients (10%) had tibiae of equal length. In 13 patients, an unequal tibia partially corrected the LLD whilst in 12 it added to the discrepancy. Five patients with LLD of greater than 15 mm underwent correction.ConclusionsA postoperative scanogram in patients with comminuted femoral shaft fractures treated with intramedullary nailing is useful to evaluate LLD and allows for early intervention. The ideal length where correction is necessary remains unclear.