Abstract
Introduction
Heterotopic Ossification(HO) is a recognized complication following Total Hip Arthroplasty(THA) that can compromise patient outcomes. Our objectives were to report its incidence and risk factors in a modern arthroplasty unit(MAU).
Methods
2305 consecutive primary THAs in 2150 patients(887♂;1263♀) undertaken at a single centre and followed-up for at least one year constituted the study cohort. A retrospective review of patient demographics (age, side, body mass index[BMI], type of anaesthesia, surgical approach, method of fixation, estimated blood loss[EBL] and operative time), serial radiographs and outcome measure (The Oxford hip score[OHS]) were undertaken. All HO were further followed for additional four years to determine the incidence of Revision THA at five years. Descriptive statistics and logistic regression was undertaken to identify the risk factors for HO using Statistical Package(SPSS) version16.
Results
The mean age and BMI were 67.9±SD9.9years and 29.7±SD5.5 respectively. The mean operative time and blood loss was 72±SD18minutes. 148 hips in 146 patients(83♂;63♀) had established HO in 6.79% patients(146/2150). The first year incidence of HO was 6.42%(148/2305) and the incidence of severe HO (Brooker's Grade III+IV) was 1.47%(34/2305). We did not find any difference in the incidence of HO for choice of fixation (Cemented[6.9%]; Uncemented[6.7%]; Hybrid[5.6%]). The mean OHS was 42±SD7 and overall satisfaction at one year was 97.5%. There was no difference in OHS between the two groups(p=0.39). Statistically significant risk factors (p=0.0001) on logistical regression were male gender (Odds Ratio[OR]=1.97;95%CI:1.40–2.76) and anterolateral (OR=2.05;95%CI:1.42–2.95) approach. Excision of HO mass and Revision THA was undertaken in two instances by five years.
Discussion
Incidence of HO in MAU is lower than previous published literature (10–47%). Uncemented THA. EBL and epidural anaesthetic were not found to be associated with higher incidence of HO as previously reported in the literature. The incidence of Revision THA in HO patients was 1.35% at 5 years.
