Complications at screw removal in slipped capital femoral epiphysis treated by cannulated titanium screws.

INTRODUCTION

Various modes of fixation are proposed for the treatment of slips of the capital femoral epiphysis (SCFE). We describe our experience with the use and removal of a new, cannulated titanium screw (Asnis III, Stryker, Howmedica).

PATIENTS AND

METHODS

Single cannulated titanium screws had been inserted in 101 hips of 65 patients in the 3-year period from 2001 to 2003. These pins were used for in situ fixation of minor chronic slips in 41 patients and for prophylactic fixation on the contralateral side in patients with open physis in 60 patients.

RESULTS

The insertion of these screws was achieved without any real problem. The mean surgical time was 25 min (13-46 min). Problems came up when we started to remove the pins. Hardware retrieval was attempted in 27 patients with 43 pins. The mean surgical time for removal was double the average time of insertion with 51 min (26-107 min). The hexagonal Allen sockets proved to be too weak to overcome the necessary torque for loosening the pin from bone and applying the reverse-cutting-force, necessary to extract the pin. Eleven patients needed extensive chiselling. Two adolescents sustained a subtrochanteric fracture 5 and 7 weeks after hardware removal. Seven pins could not be totally removed.

CONCLUSION

Due to the considerable disadvantages encountered in our series we conclude that Asnis III cannulated screws should be suspended from further use in SCFE.