Outcome Assessment of Cementless Total Hip Arthroplasty in Patients with Late-stage Avascular Necrosis of the Femoral Head in Vietnam, 2011 - 2021.

Background: The progression of avascular necrosis to the point of femoral head collapse necessitates total hip arthroplasty surgery as a treatment intevention. Despite its widespread use, this surgical procedure is often associated with a notable incidence of failure and various postoperative complications. This study aimed to evaluate the outcomes of cementless total hip arthroplasty (CTHA) in Vietnamese patients diagnosed with late-stage avascular necrosis of the femoral head (AVNFH). Methods: From Sep 2011 to Dec 2021, 150 patients were diagnosed with unilateral AVNFH at stages IV, V, and VI at the 108 Military Central Hospital. These patients underwent laboratory tests, CTHA, and assessments of hip function at three intervals: before surgical procedure, 12 months after surgery, and 48 months post-surgery. Results: Among the 150 patients with AVNFH, the femurs were classified as type B (80.7%), type A (10%), and type C (9.3%). Of these patients, 62.0% had articular head diameters of 32mm, while 38.0% had diameters of 36mm. The bearing surface pairings used in hip arthroplasty included 63.3% metal-polyethylene and 36.7% ceramic-ceramic. Regarding implant size, 86.7% used size 10-13 femoral stems, 6.0% used size 9, and 7.4% used size 14-15. In-hospital following surgery, there were no reports of thrombosis, deep infection, femoral fracture, or acetabular fracture. Meanwhile, 80% of cases had the acetabulum positioned in an intermediate alignment, whereas 4.0% and 16.0% were in varus and valgus positions, respectively. Patients with AVNFH in stages IV, V, and VI showed significant improvement in mobility, with pain levels decreasing to 0.0% and Harriss Hip scores increasing to approximately 85 points. At 12 months postoperatively, 16.0%, 52.0%, 21.2%, and 16.7% of patients exhibited bone platforms, bone welds, radiolucent lines, and calcar osteolysis, respectively. These figures increased to 23.0%, 89.3%, 27.3%, and 30.7%, respectively, after 48 months. Complications at 12 months included 2.0% superficial infection, 0.7% deep infection, and prosthetic joint loosening. At 48 months, patients experienced deep infection, hip dislocation, and prosthetic joint loosening, each occurring in 1.3% of cases. Conclusion: With the posterior approach, CTHA for Vietnamese patients with AVNFH stages IV, V, and VI demonstrated favorable and promising outcomes. Intraoperative complications were minor, and no significant issues were observed during the 12- and 48-month postoperative follow-up periods.