Periarticular infiltration in total hip replacement: effect on heterotopic ossification, analgesic requirements and outcome.

Background: Up to 80% of patients develop heterotopic ossification (HO) following total hip replacement (THR) and high grades may adversely affect outcome. This study investigated the influence of local infiltration of a NSAID (Ketorolac) and local anaesthetic on the incidence and grade of HO following THR, the effect on post-operative opiate analgesic requirement and on patient reported outcome score.

Methods: A retrospective study was performed on 118 THRs performed without periarticular infiltration from 2003 to 2005, and on 211 performed with infiltration from 2005 to 2008. Pre-operative and 12-month radiographs were examined and HO graded according to the Brooker classification. Peri-operative analgesic requirements and NSAID use were noted and outcome was measured at 1 year with the Oxford Hip Score.

Results: Univariate and multivariate analysis indicated that single-dose periarticular NSAID infiltration did not reduce the incidence or grade of HO. Preoperative HO (p = 0.005) and enthesopathy (p = 0.027) were significant predictors of post-operative HO. The use of post-operative oral NSAID (except aspirin) significantly reduced HO (p = 0.001). Periarticular infiltration significantly reduced opiate analgesia use in the first 24 h (p < 0.001) and length of inpatient stay (p < 0.001). There was no difference in Oxford Hip Score at 1 year.

Conclusion: Preoperative enthesopathies are a risk factor for postoperative HO. Periarticular infiltration of NSAID and local anaesthetic does not reduce HO incidence or grade in THR, but does reduce perioperative opiate requirements and length of hospital stay.