The oblique plane deformity in slipped capital femoral epiphysis

Anthony Philip Cooper,James A Fernandes,Sanjeev S Madan,Patrick Foster,Carolyn Geddis,Saif Salih

doi:10.1007/s11832-014-0559-2

Abstract

BackgroundSlipped capital femoral epiphysis (SCFE) is commonly treated with in situ pinning. However, a severe slip may not be suitable for in situ pinning because the required screw trajectory is such that it risks perforating the posterior cortex and damaging the remaining blood supply to the capital epiphysis. In such cases, an anteriorly placed screw may also cause impingement. It is also possible to underestimate the severity of the slip using conventional radiographs. The aim of this study was to describe and evaluate a novel method for calculating the true deformity in SCFE and to assess the interobserver and intraobserver reliability of this technique.MethodsWe selected 20 patients with varying severity of SCFE who presented to our institution. Cross-sectional imaging [either axial computed tomography (CT) scans or magnetic resonance imaging (MRI) scans] and anteroposterior (AP) pelvis radiographs were assessed by four reviewers with varying levels of experience on two occasions. The degree of slip on the axial image and on the AP pelvis radiographs were measured and, from this, the oblique plane deformity was calculated using the method as popularised by Paley. The intraclass correlation coefficient (ICC) was calculated to determine the interobserver and intraobserver reliabilities between and amongst the raters.ResultsThe interobserver reliability for the calculated oblique plane deformity in SCFE ICC was 0.947 [95 % confidence interval (CI) 0.90–0.98] and the intraobserver reliability for the calculated oblique plane deformity of individual raters ranged from 0.81 to 0.94. The deformity in the oblique plane was always greater than the deformity measured in the axial or the coronal plane alone.ConclusionThis method for calculating the true deformity in SCFE has excellent interobserver and intraobserver reliability and can be used to guide treatment options. This technique is a reliable and reproducible method for assessing the degree of deformity in SCFE. It may help orthopaedic surgeons with varying degrees of experience to identify which hips are suitable for in situ pinning and those which require surgical dislocation and anatomical reduction, given that plain radiographs in a single plane will underestimate the true deformity in the oblique plane.Level of evidenceLevel II diagnostic study.

Highlights

When assessing a patient with slipped capital femoral epiphysis (SCFE), several factors need to be addressed
A severe slip may not be suitable for in situ pinning because the required screw trajectory is such that it risks perforating the posterior cortex and damaging the remaining blood supply to the capital epiphysis
The reliability for our method of measuring the deformity in the coronal and axial planes can be classified as almost perfect agreement [10], with intraclass correlation coefficient (ICC) values of 0.964 and 0.914, respectively

Summary

Introduction

When assessing a patient with slipped capital femoral epiphysis (SCFE), several factors need to be addressed. It is important to identify a severe slip, as it may not be suitable for in situ pinning because the trajectory required of the screw is such that it risks perforating the posterior cortex and damaging the remaining blood supply to the capital epiphysis [5] In such cases, an anteriorly placed screw may cause impingement of the screw head on the pelvis [6]. A severe slip may not be suitable for in situ pinning because the required screw trajectory is such that it risks perforating the posterior cortex and damaging the remaining blood supply to the capital epiphysis In such cases, an anteriorly placed screw may cause impingement. The aim of this study was to describe and evaluate a novel method for calculating the true deformity

Objectives

Methods

Results

Conclusion