The epipubic bones of the marsupials have been little studied and the meaning of their linear dimensions is poorly known. We therefore evaluated epipubic bone size of Virginia Opossum (Didelphis virginiana) from Mexico, and estimated their proportions relative to skull size of individuals. Results showed that males have larger skull and acetabulum size than females, epipubic bones of females are almost half the size of a female’s skull while that of the male is a little less than a third of the male cranial size. Therefore, epipubic bones are an important landmark of sexual dimorphism in D. virginiana, and our data may be useful to learn more about epipubic bones of other marsupials.

Developmental dysplasia of the hip (DDH) is a congenital condition characterized by abnormality in acetabulum size and/or shape. The incidence rate of DDH differs between different populations with risk factors including positive family history, breech presentation, sex, firstborn status, side of the hip, mode of delivery and oligohydramnios. It is recognized that DDH has a genetic component that exhibit autosomal dominant patterns. Many candidate genes have been studied and found to be associated with the disease; most of them are normally involved in cartilage development and joint metabolism. In this study, the association of four single-nucleotide polymorphisms (SNPs) (rs731236, rs1544410, rs7975232 and rs2228570) in the vitamin D receptor (VDR) gene was studied by a case-control analysis. The study sample involves 50 cases with confirmed DDH presentation and 50 nonDDH controls. SNPs were genotyped using conventional polymerase chain reaction (PCR) and restriction fragment-length polymorphism (RFLP) techniques. Genotype and allele frequencies were analysed using SPSS software. No significant associations were found between the VDR polymorphisms analysed and DDH. Further work need to be performed using genomewide analysis to elucidate the genetic basis of DDH.

The articular surface replacement (ASR) monoblock metal-on-metal acetabular component was recalled due to a higher than expected early failure rate. We evaluated the survivorship of the device and variables that may be predictive of failure at a minimum of 5-year follow-up. A single-center, single-surgeon retrospective review was conducted in patients who received the DePuy Synthes ASR™ XL Acetabular hip system from December 2005 to November 2009. Mean values and percentages were calculated and compared using the Fisher's exact test, simple logistic regression, and Student's t-test. The significance level was P ≤ .05. This study included 29 patients (24 males, 5 females) with 32 ASR™ XL acetabular hip systems. Mean age and body mass index (BMI) reached 55.2 years and 28.9 kg/m², respectively. Mean postoperative follow-up was 6.2 years. A total of 2 patients (6.9%) died of an unrelated cause and 1 patient was lost to follow-up (3.4%), leaving 26 patients with 28 hip replacements, all of whom were available for follow-up. The 5-year revision rate was 34.4% (10 patients with 11 hip replacements). Mean time to revision was 3.1 years. Age (P = .76), gender (P = .49), BMI (P = .29), acetabular component abduction angle (P = .12), and acetabulum size (P = .59) were not associated with the increased rate for hip failure. Blood cobalt (7.6 vs 6.8 µg/L, P = .58) and chromium (5.0 vs 2.2 µg/L, P = .31) levels were not significantly higher in the revised group when compared with those of the unrevised group. In the revised group, a 91% decrease in cobalt and 78% decrease in chromium levels were observed at a mean of 6 months following the revision. This study demonstrates a high rate of failure of ASR acetabular components used in total hip arthroplasty at a minimum of 5 years of follow-up. No variable that was predictive of failure could be identified in this series. Close clinical surveillance of these patients is required.

Femoral head size provides important information on body size in extinct species. Although it is well-known that femoral head size is correlated with acetabular size, the precision with which femoral head size can be estimated from acetabular size has not been quantified. The availability of accurate 3D surface models of fossil acetabular remains opens the possibility of obtaining accurate estimates of femoral head size from even fragmentary fossil remains [Hammond et al.,: Am J Phys Anthropol 150 (2013) 565-578]. Here we evaluate the relationship between spheres fit to surface models of the femoral head and acetabulum of a large sample of extant anthropoid primates. Sphere diameters are tightly correlated and scale isometrically. In spite of significant taxonomic and possibly functional differences in the relationship between femoral head size and acetabulum size, percent prediction errors of estimated femoral head size remain low regardless of the taxonomic composition of the reference sample. We provide estimates of femoral head size for a series of fossil hominins and monkeys.

The present study was designed to define the morphological dimensions of the acetabulum in normal Chinese adults and to statistically compare these data with the available data worldwide. This information is important for the diagnosis of dysplasia and treatment of total hip arthroplasty. In this study, the gender and bilateral differences were evaluated. One-hundred CT scans of patients were retrospectively studied. These individuals showed no signs of developmental disturbances in either of the hip joints. Thirty-five morphometric parameters of the acetabulum were measured. The size of acetabulum was evaluated by the acetabular perimeter, anteroposterior diameter, vertical diameter, the depth and width of fossa ovalis in both transaxial and coronal plane. The parameters of acetabular orientation were the acetabular angle, anterior center edge angle, neck shaft angle, acetabular anteversion, and abduction angle. The coverage of acetabulum was examined as the, acetabular head index, center edge angle, the distance between the femoral head, and acetabulum. Gender and bilateral differences were analyzed for each parameter, and compared with available worldwide data. The results showed statistically significant differences between the Chinese genders and also between the Chinese and other human races in some parameters. In conclusion, gender, bilateral and racial differences exist in the morphology of acetabulum. The data may be helpful for the design of total hip arthroplasty for the Chinese population.

Preoperative templating in Total Hip Replacement (THR) is a method to estimate the optimal size and position of the implant. Today, observational (manual) size recognition techniques are still used to find a suitable implant for the patient. Therefore, a digital and automated technique should be developed so that the implant size recognition process can be effectively implemented. For this purpose, we have introduced the new technique for acetabular implant size recognition in THR preoperative planning based on the diameter of acetabulum size. This technique enables the surgeon to recognise a digital acetabular implant size automatically. Ten randomly selected X-rays of unidentified patients were used to test the accuracy and utility of an automated implant size recognition technique. Based on the testing result, the new technique yielded very close results to those obtained by the observational method in nine studies (90%).

Manual templating using transparencies allows preoperative visualisation of anatomy and prosthesis size, as well as ease of exchange from prosthesis type to another. Most UK hospitals have converted X-ray provision to Picture Archiving and Communication Systems (PACS), necessitating the use of digital templating. We assessed the accuracy and speed of templating for hip replacement on 36 occasions in 12 patients listed for hip replacement, using final component choice as an indicator of accuracy. Each hip was templated using, “Orthoview,” templating programme without initial scaling and following scaling and then manually scaled images on a computer screen superimposing acetate templates in the traditional fashion. A two pence coin taped to the lateral aspect of the thigh at the level of the greater trochanter was used for scaling purposes. Our results showed acetate templating to be most accurate, correlating identically with the prosthesis stem size in 9/12 cases, and with the acetabulum reamed size on 10/12 occasions. Acetate templating was also the most accurate method when allowing for +/− one size difference, being within +/− one size in all 12/12 cases for both stem size and acetabulum size. In comparison, both scaled and non scaled Orthoview templating correlated with the correct femoral prosthesis size in 5/12 patients. The acetabulum ream size was correctly templated in 10/12 patients using unscaled Orthoview, and 8/12 patients using scaled Orthoview. Additionally, Orthoview templating took a mean of 6 minutes, whereas manual templating can be achieved in under 30 seconds. Manual templating of scaled PACS images using transparencies conferred considerable advantages in terms of accuracy and speed. Moreover, this method allows a hands-on assessment of the forthcoming surgical procedure immediately prior to the operation, as well as late changes in implant choice. We recommend the continuation of manual templating using modern scaled digital images.

Ann R Coll Surg Engl 2010; 92: 73–78 74 correlating identically with the prosthesis stem size in 9 out of 12 cases and, with the acetabulum size, on 10 of 12 occasions. In comparison, scaled Orthoview® templating correlated with the correct femoral prosthesis size in 5 of 12 patients, and 8 of 12 for the acetabulum. Additionally, Orthoview® templating took a mean of 6 min, whereas manual templating can be achieved in under 30 s. Manual templating of scaled PACS images using transparencies conferred considerable advantages in terms of accuracy and speed. Moreover, this method allows a hands-on assessment of the forthcoming surgical procedure immediately prior to the operation, as well as late changes in implant choice. We recommend the continuation of manual templating using modern, scaled, digital images.

Resurfacing arthroplasty of the hip is being performed more frequently in the United Kingdom. The majority of these patients are younger than 55 years of age, and in this group the key benefits include conservation of femoral bone stock and the potential reduction in the rate of dislocation afforded by the larger resurfacing head. Early aseptic loosening is well recognised in patients younger than 55 years of age, and proponents of resurfacing believe that the improved wear characteristics of the metal-on-metal bearing may improve the long-term survival of this implant. There has been some concern, however, that resurfacing may not be conservative of acetabular bone. We compared a series of 33 consecutive patients who had a hybrid total hip arthroplasty with an uncemented acetabular component and a cemented femoral implant, with 35 patients undergoing a Birmingham hip resurfacing arthroplasty. We compared the diameter of the implanted acetabulum in both groups and, because they were not directly comparable, we corrected for patient size by measuring the diameter of the contralateral femoral head. The data were analysed using unpaired t-tests and analysis of covariance. There was a significantly larger acetabulum in the Birmingham arthroplasty group (mean diameter 56.6 mm vs 52.0 mm; p < 0.001). However, this group had a significantly larger femoral head diameter on the contralateral side (p = 0.03). Analysis of covariance revealed a significant difference between the mean size of the acetabular component implanted in the two operations. The greatest difference in the size of acetabulum was in those patients with a larger diameter of the femoral head. This study shows that more bone is removed from the acetabulum in hip resurfacing than during hybrid total hip arthroplasty, a difference which is most marked in larger patients.

We reviewed the results of 545 consecutive total hip replacements using a cementless non-coated high-density polyethylene acetabular component combined with a cemented Müller stem at five to 10 years. In all, 421 patients (445 hips) were available for review, 118 by questionnaire and 303 by examination and radiography. Of these, 86% had a good or excellent result. We found a high rate of radiological loosening of the cup after the sixth year, and a high rate of clinical loosening after the eighth year. Loosening was commoner in women, in younger patients and where a smaller size of acetabulum had been used. Calcar resorption was significantly related to loosening of the acetabulum. Loosening appeared to be mainly due to polyethylene debris produced by micro-movement of the acetabulum against the bone, which had resulted in a giant cell foreign body reaction and subsequent bone erosion. We have abandoned the use of this prosthesis and suggest that direct contact between bone and polyethylene should be prevented by a coating of metal or some other material.