Ottawa classification for symptomatic acetabular dysplasia assessment of interobserver and intraobserver reliability

Abstract

Aims The aim of the current study was to assess the reliability of the Ottawa classification for symptomatic acetabular dysplasia. Methods In all, 134 consecutive hips that underwent periacetabular osteotomy were categorized using a validated software (Hip2Norm) into four categories of normal, lateral/global, anterior, or posterior. A total of 74 cases were selected for reliability analysis, and these included 44 dysplastic and 30 normal hips. A group of six blinded fellowship-trained raters, provided with the classification system, looked at these radiographs at two separate timepoints to classify the hips using standard radiological measurements. Thereafter, a consensus meeting was held where a modified flow diagram was devised, before a third reading by four raters using a separate set of 74 radiographs took place. Results Intrarater results per surgeon between Time 1 and Time 2 showed substantial to almost perfect agreement among the raters (κappa = 0.416 to 0.873). With respect to inter-rater reliability, at Time 1 and Time 2 there was substantial agreement overall between all surgeons (Time 1 κappa = 0.619; Time 2 κappa = 0.623). Posterior and anterior rating categories had moderate and fair agreement at Time 1 (posterior κappa = 0.557; anterior κappa = 0.438) and Time 2 (posterior κappa = 0.506; anterior κappa = 0.250), respectively. At Time 3, overall reliability (κappa = 0.687) and posterior and anterior reliability (posterior κappa = 0.579; anterior κappa = 0.521) improved from Time 1 and Time 2. Conclusion The Ottawa classification system provides a reliable way to identify three categories of acetabular dysplasia that are well-aligned with surgical management. The term ‘borderline dysplasia’ should no longer be used. Cite this article: Bone Joint Res. 2020;9(5):242–249.

Correlation of Patient-Reported Outcomes After Periacetabular Osteotomy With Femoral Head Coverage and Acetabular Orientation: A Single-Center Cohort Study

“…More importantly, when comparing before and after correction, the largest percentage in change was seen in the direction of initial deficiency, with all hips having a significant improvement in TFC and posteriorly deficient hips having a negative change in AC. 2,22,53 These findings of including class P within the spectrum of dysplasia are consistent with the recent work of McClincy et al, 34 which showed excellent outcomes at 2 years, as well as the work from Zurmuhle et al 58 in regard to PAO being superior to rim trimming in hips with retroversion. In other words, posterior undercoverage is the driving force in the patient's symptoms.…”

“…40,50 The hips were classified according to the Ottawa classification for acetabular dysplasia, which has been shown to have substantial reliability: 54 hips (68.4%) were class G (global deficiency), 15 hips (18.9%) were class P (posterior deficiency), and 10 hips (12.7%) were class A (anterior deficiency). 2,22,53…”

“…37,52 However, recent work by the Bern group as well as others has helped us to better understand that acetabular dysplasia is a deformity that exists in multiple planes, 21,22 which can be classified into 3 broad categories: anterior deficiency (A), posterior deficiency (P), and global deficiency (G). 2,22,30,46,53 Consequently, gaining a better understanding of the underlying pattern of acetabular dysplasia beyond the coronal plane can help better guide treatment and our understanding of the causes of poor outcomes. 5,7,8,45,53 The aim of this study was to examine the relationship between preoperative and postoperative femoral head coverage and PROM scores in patients undergoing PAO for acetabular dysplasia.…”

Radiographic Measures Predicting Failure of Arthroscopy in Borderline Hip Dysplasia: Letter to the Editor

“…6 Additionally, femoral head under-coverage can exist even in the presence of a normal LCEA. 2 Siebenrock et al 6 described the anterior (AWI) and posterior (PWI) wall indexes as a versatile method to assess the anterior and posterior wall coverage of the femoral head. These tools are particularly valuable in cases of so-called borderline dysplasia, in which sometimes there is an underdiagnosed deficient anterior and/or posterior wall coverage.…”

“…The concept of “mild” dysplasia based purely on an almost normal LCEA sounds minimalistic, as these hips can likely exhibit deficient anterior or posterior wall coverage with normal lateral coverage. 2,3 Also, understanding that hip dysplasia is a structural (ie, 3-dimensional [3-D]) problem of the hip should make orthopaedic providers further characterize acetabular anatomy with 3-D computed axial tomography (CT) or 3-D magnetic resonance imaging (MRI) to help reach an accurate diagnosis. 7…”