Slipped Capital Femoral Epiphysis: Relevant Pathophysiological Findings With Open Surgery

Abstract

Background Traditionally arthrotomy has rarely been performed during surgery for slipped capital femoral epiphysis (SCFE). As a result, most pathophysiological information about the articular surfaces was derived clinically and radiographically. Novel insights regarding deformity-induced damage and epiphyseal perfusion became available with surgical hip dislocation. Questions/purposes We (1) determined the influence of chronicity of prodromal symptoms and severity of SCFE deformity on severity of cartilage damage. (2) In surgically confirmed disconnected epiphyses, we determined the influence of injury and time to surgery on epiphyseal perfusion; and (3) the frequency of new bone at the posterior neck potentially reducing perfusion during epimetaphyseal reduction. Methods We reviewed 116 patients with 119 SCFE and available records treated between 1996 and 2011. Acetabular cartilage damage was graded as +/++/+++ in 109 of the 119 hips. Epiphyseal perfusion was determined with laser-Doppler flowmetry at capsulotomy and after reduction. Information about bone at the posterior neck was retrieved from operative reports.

Is Assessment of Femoral Head Perfusion During Modified Dunn for Unstable Slipped Capital Femoral Epiphysis an Accurate Indicator of Osteonecrosis?

“…It is unclear, however, whether revascularization was related to the integrity of the retinacular vessels or if it may have happened through a transphyseal mechanism. Contrary to previous studies [9,18,30], we found three patients with an ICP waveform before dissection and after fixation who later developed osteonecrosis. These represent examples of a false-negative test result.…”

“…All three patients developed osteonecrosis. However, in accordance with Ziebarth et al [30], we observed two patients with an intact retinacular flap in whom there was no intraoperative ICP waveform and who did not development of osteonecrosis. These represent examples of a false-positive test result.…”

“…This may be related to the fact that we did not perform any surgery within 8 hours after presentation. In contrast, Ziebarth et al [30] showed that patients undergoing a modified Dunn procedure less than 8 hours from injury were less likely to develop osteonecrosis when compared with patients undergoing surgery after 8 hours. Early surgery may have the benefit of decompression of the hematoma, which has been associated with increased intraarticular pressure, a potential risk factor for osteonecrosis [8].…”

“…One of the advantages of the modified Dunn procedure is the ability to perform an intraoperative assessment of epiphyseal perfusion and controlled reduction of the epiphysis preserving its blood supply. However, there is limited evidence [18,30] about the performance of epiphyseal perfusion assessment in screening for osteonecrosis. In this study, we investigated the accuracy of intraoperative assessment of femoral head vascularity by examining the presence of active bleeding and using an ICP monitor as an indicator for osteonecrosis development in patients undergoing a modified Dunn procedure for the treatment of unstable SCFE while assessing clinical features as possible prognostic factors.…”

“…One of the benefits of the subcapital realignment through the surgical dislocation approach (modified Dunn procedure) is visualization and protection of the vascular retinaculum and direct assessment of perfusion of the femoral head during surgery. Femoral head perfusion may be assessed by evaluating bleeding after creating a 2-mm drill hole [9,24,30,31], by laser-Doppler flowmetry [9,30], and/or by intracranial pressure probe monitoring [24]. Assessment of perfusion during surgery may allow for adjustments of positioning the femoral head if blood flow decreases after the femoral head is reduced.…”