Intraoperative Monitoring of Epiphyseal Perfusion in Slipped Capital Femoral Epiphysis.

Background: The purposes of this study were to validate an innovative, percutaneous method of monitoring femoral head (epiphyseal) perfusion intraoperatively in patients with slipped capital femoral epiphysis (SCFE) and to investigate an association between intraoperative perfusion and the subsequent development of osteonecrosis.
Methods: A percutaneous screw fixation technique for SCFE was utilized. A fully threaded, cannulated, stainless-steel 7.0-mm screw was inserted into the epiphysis. The guidewire was removed, and a sterile intracranial pressure (ICP) probe was placed through the screw such that the tip was in the epiphyseal bone past the end of the screw. Intraoperative epiphyseal pressure and waveform were recorded. A prospective analysis of patients undergoing percutaneous screw fixation for unstable or stable SCFE or for prophylactic treatment with the use of this technique to evaluate femoral head perfusion was performed.
Results: This technique was used in 23 patients (29 hips, including 15 hips with unstable SCFE, 11 with stable SCFE, and 3 treated prophylactically). Three hips (2 with unstable SCFE and 1 treated prophylactically) in 2 patients were eliminated from the analysis because of technical problems with the ICP monitor. All hips with stable SCFE and the prophylactically treated hips had measurable pulsatile flow that was synchronous with the patient's heart rate at the initial time of probe insertion. Seven patients (7 hips) with unstable SCFE had measurable, pulsatile flow with initial insertion of the probe, and 6 patients (6 hips) with unstable SCFE had no measurable flow. We were able to demonstrate perfusion following a percutaneous capsular decompression in the patients with no initial flow. All patients left the operating room with measurable femoral head blood flow. At a mean follow-up of 1.6 years for hips with stable SCFE and 2.0 years for those with unstable SCFE, no hip subsequently developed radiographic evidence of osteonecrosis of the femoral head. No complications from the use of the ICP monitor occurred.
Conclusions: Femoral head perfusion in patients with SCFE can be measured intraoperatively using this technique. Demonstrating femoral head perfusion before leaving the operating room was associated with the absence of osteonecrosis postoperatively.
Level of Evidence: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.
(Copyright © 2016 by The Journal of Bone and Joint Surgery, Incorporated.)