Low-cost surveillance for lower extremity fracture union after intramedullary nailing – experience on 80 SIGN patients by a Philippine trauma center

Background. There is need to come up with low-cost strategies for assessing fracture union following surgical treatment in developing countries. We aimed to develop one by determining the optimal surveillance schedule taking into account associated factors and diagnostic performance of S & S test.

Methods. A total of 80 patients with lower extremity fracture treated with the SIGN nail were followed for at least 8 months. Time to fracture union were calculated using the RUST, and variables analyzed for association with fracture union. Forty-eight patients performed additional S & S test, and sensitivity, specificity, positive and negative predictive values, and accuracy of S & S test were assessed.

Results. Ten (12.5%) of 80 patients developed nonunion, and presence of superficial infection (28.5 ± 5.6 weeks vs 17.2 ± 1.2 weeks, p=.01) and pain on weight-bearing (29.6 ± 2.2 weeks vs 16.8 ± 1.2 weeks, p<.001) were associated factors. Cumulative incidence at 16 weeks was 59% (58% to 60%), and S & S test had high Sn (90%) and Sp (100%) in diagnosing union with NPV and PPV of 67% and 100%, respectively, and accuracy of 92%.

Conclusions. S & S test may reliably detect fracture union by fourth month after surgery, while closer follow-up is likely needed for patients developing superficial infection or pain on weight-bearing.

Key words. RUST; Squat and smile test; SIGN; Trauma; Fracture