Aims

Obesity is associated with an increased risk of hip osteoarthritis, resulting in an increased number of total hip arthroplasties (THAs) performed annually. This study examines the peri- and postoperative outcomes of morbidly obese (MO) patients (BMI ≥ 40 kg/m²) compared to healthy weight (HW) patients (BMI 18.5 to < 25 kg/m²) who underwent a THA using the anterior-based muscle-sparing (ABMS) approach.

The Japan National Register (JAR) for total hip arthroplasty (THA) was launched in 2006. The JAR office accumulates and processes all the data and reports annually. The comparative studies among the annual data from 2013 to 2016 reveal the current trend of THA in Japan. Up to March 2016, 1,188 hospitals have participated in the JAR. Registration ratio of THA is supposed to be about 50% in 2016. From 2006 to 2016, 88.146 data collection forms were submitted for THA. More than 65% of the patients are diagnosed with Developmental Dysplasia of the Hip in Japan. Recently, the anterior approaches, direct Anterior approach and anterolateral modified Watson-Jones approach, have increased. About 80% of implants are cementless, while 8.7% are cement. The major reasons for revision THA are aseptic loosening, osteolysis, and infection, while periprosthetic fracture and implant dislocation/instability increase currently. A brief summary of the annual report of the JAR is available from The Japanese Society for Replacement Arthroplasty website at . http://jsra.info/.

Aims

The aim of this study was to compare the pattern of initial fixation and changes in periprosthetic bone mineral density (BMD) between patients who underwent total hip arthroplasty (THA) using a traditional fully hydroxyapatite (HA)-coated stem (T-HA group) and those with a newly introduced fully HA-coated stem (N-HA group).