BONY GROWTH AND COMPLICATIONS IN SCREW-FIXED SLIPPED CAPITAL FEMORAL EPIPHYSIS

Abstract

A slipped capital femoral epiphysis (SCFE) can be fixed in-situ with K-wires or screws. For the latter is said that one disadvantage is the lack of femoral neck growth. Assumed reasons for this is despite an injury of the physis by the often too long thread the missing lubrication of the screw in the bone.

The following study evaluates the amount of remaining bony growth and method-depending complications in screw fixation of SCFE.

Method: All children with titanium screw fixed SCFE and completed growth were evaluated retrospectively. For percutaneously fixation a cannulated titanium screw (Fa. Firma Königsee) was used. With help of the postoperative X-ray follow-up in two dimensions the remaining bony growth was assessed. Further parameters were possible complications like AVN, misplaced screws, problems in removal of the screws and duration of surgery.

Result: 40 patients with 49 SCFEs were treated bilaterally with cannulated screws in the time period 1999 to 2005, 4 got an additional closed reduction. In 6 cases a correction osteotomy was performed. The contralateral hips off these patients were enclosed in the study. The average growth of the femoral neck was 6 mm both at the healthy and SCFE-hip (Range 0–19mm) and depended not on the degree of dislocation. None had a premature closure of physis. In 2 cases screws were changed due to excessive growth despite a growth reserve in screw length of 1 cm. 1 acute and 4 of 7 acute-on-chronic slips developed a clinically relevant AVN.

In 20 patients we tried to remove the screws after completed growth. This was possible in 30% minimal invasively and in 30% with open surgery. In 40% parts of the screws or even the whole screw remained in situ. Time of surgery for bilateral screw pinning was 51 minutes, for removal 91 minutes in average (34–278).

Discussion: The percutaneously fixation of SCFE with cannulated screws is a save and easy procedure that allows further bony growth of the femoral neck and remodelling but is more than difficult to remove the titanium screws due to bony integration. One screw is sufficient for fixation, secondary dislocation does not happen. We recommend the use of cannulated steal-screws with a backward incisive thread. Titanium screws should be used only in cases of a high risk of AVN to allow the early control of femoral head blood flow with MRI.