Ectopic ossification following total hip arthroplasty: is diffuse idiopathic skeletal hyperostosis a risk factor?

Area of Science:

• Orthopedic Surgery
• Rheumatology
• Bone Metabolism

Background:

• Ectopic bone formation can occur after total hip arthroplasty.
• An increased incidence of this complication is suspected in patients with diffuse idiopathic skeletal hyperostosis (DISH).

Purpose of the Study:

• To investigate the frequency of postoperative ectopic bone formation in patients with and without DISH undergoing total hip arthroplasty.
• To evaluate the clinical significance of ectopic bone formation after total hip arthroplasty.

Main Methods:

• Retrospective analysis of 204 patients undergoing total hip arthroplasty, comparing ectopic bone formation rates between those with and without pre-existing DISH.
• Correlation analysis between the severity of postoperative ectopic bone and clinical outcomes (pain, hip flexion) in a separate cohort of 1325 patients.

Main Results:

• Patients with DISH had a significantly higher rate of postoperative ossification (29%) compared to those without DISH (10%) (p < 0.01).
• In a larger cohort, even severe grades of ectopic bone formation were associated with only 10% reporting serious pain and 26% experiencing reduced hip flexion (<70 degrees).

Conclusions:

• Diffuse idiopathic skeletal hyperostosis (DISH) is a significant risk factor for ectopic bone formation following total hip arthroplasty.
• The clinical impact of periprosthetic ectopic bone is generally minor, not warranting routine prophylactic bisphosphonate use in DISH patients undergoing total hip replacement.