In many papers, the diagnosis of pincer-type femoroacetabular impingement (FAI) is attributed to the presence of coxa profunda. However, little is known about the prevalence of coxa profunda in the general population and its clinical relevance. In order to ascertain its prevalence in asymptomatic subjects and whether it is a reliable indicator of pincer-type FAI, we undertook a cross-sectional study between July and December 2013. A total of 226 subjects (452 hips) were initially screened. According to strict inclusion criteria, 129 asymptomatic patients (257 hips) were included in the study. The coxa profunda sign, the crossover sign, the acetabular index (AI) and lateral centre-edge (LCE) angle were measured on the radiographs. The median age of the patients was 36.5 years (28 to 50) and 138 (53.7%) were women. Coxa profunda was present in 199 hips (77.4%). There was a significantly increased prevalence of coxa profunda in women (p < 0.05) and a significant association between coxa profunda and female gender (p < 0.001) (92% vs 60.5%). The crossover sign was seen in 36 hips (14%), an LCE > 40° in 28 hips (10.9%) and an AI < 0º in 79 hips (30.7%). A total of 221 normal hips (79.2%) (normal considering the crossover) had coxa profunda, a total of 229 normal hips (75.5%) (normal considering the LCE) had coxa profunda and a total of 178 normal hips (75.3%) (normal considering AI) had coxa profunda. When the presence of all radiological signs in the same subject was considered, pincer-type FAI was found in only two hips (one subject). We therefore consider that the coxa profunda sign should not be used as a radiological indicator of pincer-type FAI. We consider profunda to be a benign alteration in the morphology of the hip with low prevalence and a lack of association with other radiological markers of FAI. We suggest that the diagnosis of pincer-type FAI should be based on objective measures, in association with clinical findings.

The reconstruction of an acetabular bone defect is one of the most important aspects of revision total hip arthroplasty surgery. It can be done by the use of grafts. Therefore, many kinds of grafts may be used and lyophilized xenograft is an alternative example. The purpose of the study was to evaluate the histological findings of lyophilized bovine xenografts used in previous total hip arthroplasty revision surgery. A case series was carried out from July 2000 to April 2013 with the approval of the Hospital Ethics Committee. Fourteen subjects were analyzed. Of these, 64.3 % were female. The average age of the patients was 52.36 ± 18.55. Neoformed bone was present in 85.7 % of subjects, and constituted 61.79 % of the total bone matrix area. The diagnosis of xenograft absorption was present in 12 subjects. A strong inverse correlation between the percentage of neoformed bone and the percentage of xenograft in the total bone matrix by analysis of biopsies was found by the Pearson test (p = 0.001). No inflammatory response was found in the clinical status of the patients or in the histological analysis. Lyophilized bovine xenograft shown to be safe until the present moment, with acceptable results. Most of the cases presented new bone formation as expected (considered values greater than 30 %) and for this reason the xenograft has proven to be an osteoconductive compatible scaffold/trellis for the bone ingrowth. Therefore, it can be considered an alternative to other bone grafts in the treatment of bone loss.