Acetabular fracture types vary with different acetabular version.

PURPOSE: Acetabular fractures typically occur in high energy trauma. Understanding of the various contributing biomechanical factors and trauma mechanisms is still limited. While several investigations figured out what role femoral position during impact plays in distinct fracture patterns, no data exists on the influence of acetabular version on the fracture type. Our study was carried out to clarify this issue. METHODS: Radiological data sets of 192 patients (145 male, 47 female, age 14-90 years) sustaining acetabular fractures were assessed retrospectively. The crossover ratio of the crossover sign and presence or absence of the posterior wall sign and ischial spine sign were used to determine acetabular retroversion on conventional radiographs. Acetabular version in the axial plane was measured on a computed tomography (CT) scan. Statistics were then performed to analyse the relationship between the acetabular fracture type according to the Letournel classification and acetabular version. RESULTS: A significant difference (p = 0.029) in acetabular version was found between fractures of the anterior [mean equatorial edge (EE) angle 19.93°] and posterior (mean EE angle 17.53°) acetabulum in the CT scan. No difference was shown on the measurements on conventional radiographs. CONCLUSIONS: Acetabular version in the axial plane has an influence on the acetabular fracture pattern. While more anteverted acetabula were frequently associated with anterior fracture types according to the Letournel classification, retroversion of the acetabulum was associated with posterior fracture types.

Normal values of Wiberg's lateral center-edge angle and Lequesne's acetabular index--a coxometric update.

BACKGROUND: The historical pathological cut-off values for Wiberg's lateral center-edge (LCE) angle and Lequesne's acetabular index (AI) are below 20° and above 12° for the LCE and AI, respectively. The aim of this study was to reassess these two angles more than 50 years after their introduction using a standardized conventional radiological measurement method, considering changing social habits and their associated physiological changes. METHODS: A total of 1,226 anteroposterior radiographs of the pelvis (2,452 hips) were obtained according to a strict standardized radiographic technique allowing reliable measurements of the LCE angle and the AI. RESULTS: Distributions of the LCE and AI were pronouncedly Gaussian, with mean values of 33.6° for the LCE and 4.4° for the AI. The 2.5th and 97.5th empirical percentiles were 18.1 and 48.0° for the LCE and -6.9 and 14.9° for the AI. These intervals contained 95 % of the data in our large sample. Small but statistically significant differences between the sexes and right and left hips have been demonstrated. Correlation between age and coxometric indices was low. CONCLUSION: The above findings do not conflict with the historical benchmarks. Statistical differences between sexes and between right and left hips were not clinically relevant. No conclusion can be drawn about coxometric indices and clinical manifestations of hip dysplasia.

Relationship between Wiberg's lateral center edge angle, Lequesne's acetabular index, and medial acetabular bone stock.

OBJECTIVE: Knowledge of acetabular anatomy is crucial for cup positioning in total hip replacement. Medial wall thickness of the acetabulum is known to correlate with the degree of developmental dysplasia of the hip (DDH). No data exist about the relationship of routinely used radiographic parameters such as Wiberg's lateral center edge angle (LCE-angle) or Lequesne's acetabular index (AI) with thickness of the medial acetabular wall in the general population. The aim of our study was to clarify the relationship between LCE, AI, and thickness of the medial acetabular wall. MATERIALS AND METHODS: Measurements on plain radiographs (LCE and AI) and axial CT scans (quadrilateral plate acetabular distance QPAD) of 1,201 individuals (2,402 hips) were obtained using a PACS imaging program and statistical analyses were performed. RESULTS: The mean thickness of the medial acetabulum bone stock (QPAD) was 1.08 mm (95% CI: 1.05-1.10) with a range of 0.1 to 8.8 mm. For pathological values of either the LCE (<20°) or the AI (>12°) the medial acetabular wall showed to be thicker than in radiological normal hips. The overall correlation between coxometric indices and medial acetabular was weak for LCE (r =-0.21. 95% CI [-0.25, -0.17]) and moderate for AI (r = 0.37, [0.33, 0.41]). CONCLUSIONS: We did not find a linear relationship between Wiberg's lateral center edge angle, Lequesne's acetabular index and medial acetabular bone stock in radiological normal hips but medial acetabular wall thickness increases with dysplastic indices.

Radiographic markers of acetabular retroversion: correlation of the cross-over sign, ischial spine sign and posterior wall sign.

Radiological diagnosis of acetabular retroversion is based on the presence of the cross-over sign (COS), the posterior wall sign (PWS), and prominence of the ischial spine (PRISS). The primary purpose of the study was to correlate the quantitative cross-over sign with the presence or absence of the PRISS and PWS signs. The hypothesis was that both, PRISS and PWS are associated with a higher cross-over sign ratio or higher amount of acetabular retroversion. A previous study identified 1417 patients with a positive acetabular cross-over sign. Among these, three radiological parameters were assessed: (1) the amount of acetabular retroversion, quantified as a cross-over sign ratio; (2) the presence of the PRISS sign; (3) the presence of the PWS sign. The relation of these three parameters was analysed using Fisher's exact test, ANOVA, and linear regression analysis. In hips with cross-over sign, the PRISS was present in 61.7%. A direct association between PRISS and the cross-over sign ratio (p < 0.001) was seen. The PWS was positive in 31% of the hips and was also significantly related with the cross-over sign ratio (p < 0.001). In hips with a PRISS, 39.7% had a PWS sign, which was a significant relation (p < 0.001). In patients with positive PWS, 78.8% of the cases also had a PRISS (p < 0.001). Both the PRISS and PWS signs were significantly associated with higher grade cross-over values. Both the PRISS and PWS signs as well as the coexistence of COS, PRISS, and PWS are significantly associated with higher grade of acetabular retroversion. In conjunction with the COS, the PRISS and PWS signs indicate severe acetabular retroversion. Presence and recognition of distinct radiological signs around the hip joint might raise the awareness of possible femoroacetabular impingement (FAI).

Correlation of the cross-over ratio of the cross-over sign on conventional pelvic radiographs with computed tomography retroversion measurements.

OBJECTIVE: To find a correlation between the cross-over ratio of the cross-over sign on conventional anteroposterior (AP) pelvic radiographs and retroversion measurements ('roof-edge angle' and 'equatorial-edge angle) on computed tomography (CT) scans. This would facilitate the interpretation of the cross-over sign regarding the amount of acetabular retroversion. MATERIALS AND METHODS: Correctly projected AP pelvic radiographs (2,925 hips) were examined for the presence of the cross-over sign (COS), and the overlap ratio of the COS was measured. On CT scans of the same patients the 'roof-edge angle' (RE angle) and the 'equatorial-edge angle' (EE angle) were also calculated. RESULTS: A statistically significant but only weak relationship could be found between the overlap ratio of the COS and the 'roof-edge angle' (P < 0.0001; correlation coefficient -0.486) and between this ratio and the 'equatorial-edge angle' (P < 0.0001; correlation coefficient -0.395). CONCLUSION: A relationship between the overlap ratio and orientation measurements on CT scans could be found, but it was less strong than expected.

Prevalence of acetabular dome retroversion in a mixed race adult trauma patient population.

The goals of the present investigation were to identify the prevalence of acetabular dome retroversion in a mixed race population, to quantify the average amount of cross-over ratio, and to determine normative values. The presence of the cross-over sign and its overlap ratio was assessed for 2,925 hips meeting strict radiographic criteria of the pelvic radiograph. Fifty-two percent of the hips had no cross-over sign whereas 48% had at least a minimal amount of overlap of the anterior and posterior acetabular wall. Analysis of only those hips with positive cross-over sign revealed a mean cross-over ratio of 26% +/- 11% (range: 3 to 93). Forty-two percent of the patients had no cross-over on either side, 18% on one side, and 40% on both sides. The presence of the cross-over sign is more common than previously expected. Further studies will be necessary to determine the risk of pathological abnormality and to correlate symptoms to crossover ratios. Surgery should not be based solely on the finding of a cross-over sign without clinical correlation.