Anatomical features of Vietnamese hip joints and assessment of the efficacy of short-stem hip arthroplasty in patients with avascular necrosis of the femoral head, 2011–2022

Spiron short-stem hip arthroplasty for the treatment of avascular necrosis of the femoral head (AVNFH) in young patients preserves the bones of the neck and upper femoral head, resulting in favorable and easy conditions when the hip is replaced again. The purpose of this study is to describe several anatomical features of the hip joint in adult Vietnamese people and to assess the efficacy of Spiron short-shaft hip arthroplasty. 129 healthy hips and 64 hips of 46 AVNFH patients underwent Spiron short-stem arthroplasty and were followed up from Jan-2012 – Dec-2022. Patients were performed digital X-rays to determine anatomical parameters in order to select the proper joint size. Patients' clinical outcomes and complications were evaluated at 12, 36, and 48 months after arthroplasty. Among the 46 patients, only 4.4% were women. The patients had an average age of 40.6 years and a mean preoperative Harris score of 45.9. The AVNFH patients had a mean acetabular diameter of 48.2 mm, acetabular tilt angle of 43.1 o , superior femoral neck length of 15.3 mm, inferior femoral neck length of 21.6 mm, superior-inferior, mid-femoral neck distance of 32.9 mm, distance from the base of the head to the medial border of the lateral femoral wall of 50.1 mm, femoral neck-shaft angle of 131.6 o , and distance from the center of the head to the femoral shaft of 36.4 mm. These indices were all lower than those of healthy people. After 48 months of joint replacement surgery, severe pain symptoms decreased from 71.9% to 3.1%, walking limitation and severe range of motion decreased from 59.4% and 56.2% to 4.7% and 6.3%, and Harris score good and excellent (80-100 points) increased from 0.0% to 78.2% respectively. Complications recorded included 1.6% wound infection after 12 months and 3.1% acetabular displacement after 48 months. Other complications, such as lateral popliteal nerve injury, decreased from 6.3% (after 12 months) to 1.6% after 48 months, while bone loss and periarticular lumina increased from 3.1% (after 12 months) to 18.8-21.9 percent (after 48 months). After 48 months of follow-up, 12.5% of patients underwent re-arthroplasty. Although Spiron short-stem hip arthroplasty for young Vietnamese patients has significantly improved clinical symptoms and bone preservation, the rate of complications and re-arthroplasty remains relatively high due to the skill of surgeons. Therefore, surgeons need to receive careful and closely monitored training in the Spiron hip arthroplasty technique.