Reliability of assessing proximal femur geometry with Rutz classification schema in patients with cerebral palsy

Abstract

Our investigation aimed to assess the reliability of the femoral head shape classification system devised by Rutz et al. and observe its application in patients with cerebral palsy (CP) at different skeletal maturity levels. Four independent observers assessed anteroposterior radiographs of the hips of 60 patients with hip dysplasia associated with non-ambulatory CP (Gross Motor Function Classification System levels IV and V) and recorded the femoral head shape radiological grading system as described by Rutz et al. Radiographs were obtained from 20 patients in each of three age groups: under 8 years, between 8 and 12 years and above 12 years old, respectively. Inter-observer reliability was assessed by comparing the measurements of four different observers. To determine the intra-observer reliability, radiographs were reassessed after a 4-week interval. Accuracy was checked by comparing these measurements with the assessment of expert consensus. Validity was checked indirectly by observing the relationship between the Rutz grade and the migration percentage. The Rutz classification system's evaluation of femoral head shape showed moderate to substantial intra-and inter-observer reliability (mean κ = 0.64 for intraobserver and mean κ = 0.5 for interobserver). Specialist assessors had slightly higher intra-observer reliability than trainee assessors. The grade of femoral head shape was significantly associated with increasing migration percentage. Rutz's classification was shown to be reliable. Once the clinical utility of this classification can be established, it has the potential for broad application for prognostication and surgical decision-making and as an essential radiographic variable in studies involving the outcomes of hip displacement in CP. Level of evidence: III.

Hip reconstruction in cerebral palsy: Lessons from a single center and 137 hips

“…Of note, Rutz et al 30 found that femoral head shape was not an independent predictor of outcome of reconstruction. Recent papers Kasprzyk et al 43 and Ulusaloglu et al 44 report that the grade of femoral head shape was significantly associated with increasing MP.…”

“…The Rutz et al 30 classification can be used to classify the shape of the femoral head. Kasprzyk et al 43 reported that while it is reliable (showing moderate-to-substantial intra- and interobserver reliability (mean κ = 0.64 and mean κ = 0.5, respectively)), clinical utility of this classification system is yet to be established in the literature. This radiological classification system was therefore not used in our study.…”

Long-term outcomes of reconstructive treatment for painful dislocations in patients with cerebral palsy

“…It is worth knowing that the femoral head shape classification system devised by Rutz was recently assessed with moderate to substantial intra-observer reliability and moderate inter-observer reliability. 15 Pain complaints in patients with CP are common with studies suggesting a prevalence of pain up to 74%. [16][17][18] Children with GMFCS level III-V experience hip pain more often than those at level I-II, which is also correlated with hip migration.…”

“…It is worth knowing that the femoral head shape classification system devised by Rutz was recently assessed with moderate to substantial intra-observer reliability and moderate inter-observer reliability. 15 …”