Morphological and Morphometric Study of the Adult Human Acetabulum in South-Western Nigeria: Clinical Relevance in Hip Arthroplasty Surgery

BACKGROUND: The acetabulum is the structure that the head of femur articulates with to form the hip joint. Knowledge of its structure and dimensions is helpful in clinical and forensics settings. Data on its dimensions are sparse in Southwestern Nigeria. In hip joint arthroplasty, metal backed acetabular cup implant is inserted into this structure. The implants used are designed based on the anatomic findings of countries where these implants were made. AIMS: The study aimed to provide data from Southwestern Nigeria and to correlate the distances between bony prominences in the hemipelvis that will be useful to implant manufacturers. MATERIALS AND METHODS: This was a prospective, descriptive and observational study that involved the measurements of parts of the acetabulum and distances between some bony points of 78 cadaveric hemipelvic bones. Parameters documented included 'Vertical diameters' (VDs), 'Transverse diameters' (TDs), 'Total diameters' (VD + TD)/2, acetabular depth and morphology of the anterior acetabular ridge. The acetabular rim thickness was also estimated. The distance between the anterior superior iliac spine (ASIS) and pubic tubercle (PT) was measured and documented. Data obtained from the study were transferred into Microsoft Excel 2010 (by Microsoft Corporation, Redmond. Washington) and analysed with Stata 13 (StataCorp, Texas, USA). RESULTS: The mean VD, TD and total diameters measured were 57.6 mm, 56.2 mm and 56.9 mm and 51.0 mm, 49.5 mm and 50.3 mm for outer and inner diameters of the acetabulum, respectively. The mean acetabular rim thickness estimated was 3.3 mm for each acetabular rim along the vertical and transverse axes for both left and right sides. Mean acetabular depth was 27.2 mm. The curved pattern was the most common anterior acetabular ridge observed. There was no statistically significant relationship between the acetabular diameters and the distance between ASIS and PT. CONCLUSION: This study has contributed data that would be useful to orthopaedic surgeons, implant manufacturers and forensic pathologists. These data should be used when population specific acetabular cup implants are being considered. This study documented no significant statistical relationship between the acetabular diameter and the distances between any of the bony prominences around the hemipelvis. Therefore, no equation could be generated for pre-operative estimation of acetabular diameter. The use of plain radiograph remains the reliable method for pre-operative estimation of the acetabular diameter.