Incidence of heterotopic ossification after hip replacement – preliminary study

Abstract

Introduction: Heterotopic ossification represents bone formation in ectopic locations. Their importance in patients with hip arthroplasty due to repercussions that may have on: joint biomechanics, mobility and the quality of life. Unobserving and their corresponding untreatment can cause severe damage to affected hip up to ankylosis. Material and methods: We have evaluated clinically and radiographically in the Department of Orthopedics and Traumatology of Brasov County Hospital, a group of 57 patients with heterotopic ossification occurred at an interval of 1-3 years after hip arthroplasty, 18 men and 39 women. 46 patients were treated with unilateral arthroplasty and 11 patients with bilateral arthroplasty. Etiological diagnosis was in 49 patients artrosis, 6 femoral neck fracture and one patient with acetabulum inflammation. Type of approach that was used to 47 patients was a lateral approach and 10 patients Watson-Jones approach. Examined patient age was between 40 and 80 years. HO appearance was analyzed according to the type of hip replacement used and radiological classified as Brooker grade on anterior-posterior hip radiograph. Results: HO incidence was higher in age group 50-59 years, predominantly in womankind - 39 women, in patients with unilateral hip arthroplasty. The main etiologic diagnosis, before the prosthesis and the aparrence of OH, was artrosis. HO occurred more frequently approached laterally and HO were predominantly classified as Brooker grade I and II - 52 patients. Conclusion: Appearance of heterotopic ossification assessment should be required by the collaboration of clinical and radiological appearance of their pursuit to make medium and long term. 50-69 years age group is most represented in terms of appearance of HO. Most common etiological diagnosis was artrosis (primary and secondary), followed by upper extremity fracture of the femur (head and neck). Comparison of radiological results depending on the type of approach has shown a rate of occurrence higher to the patients operated with lateral approach then Watson - Jones approach. Comparison of radiological results depending on the type of implant showed that the cemented and cementedless arthroplasty have a total rate of appearance of OH, higher than Austin- Moore arthroplasty. Most heterotopic ossification occurred were classified as Brooker grade I and II.