Introduction: Intra-articular steroid injection has been widely used for relief of pain in osteoarthritis. Recent studies show an increasing rate of infection in these patients following hip arthroplasty. We have reviewed our cohort of patients to see if they are susceptible to higher infection rate.

Methods: We reviewed a cohort of 167 consecutive hips that had at least one injection with a 40mg triamcinolone acetonide and 4ml 0.5% bupivacaine mixture to relieve the symptoms of hip osteoarthritis or to clarify a diagnosis of hip arthritis between January 1997 and November 2004 were reviewed. A total of 37 hips (36 patients) that subsequently proceeded to have a total hip arthroplasty were selected as our study group. There was a minimum of a one-year follow up.

Results: The rate of infection in our initial cohort of patients following a hip injection was 0.60% (1 hip) which resulted in repeated washouts and a subsequent total hip arthroplasty with a good outcome. On review of the 37 hips, one was revised due to a deep infection secondary to staphylococcus epidermidis. Four were revised for continued instability and pain with no evidence of infection either prior to or during revision. When deep infection is taken as an endpoint, cumulative survival at 7.5 years is 0.968 (95% confidence interval of 1 to 0.905). The total survivorship of this cohort if all revisions are included is 0.852 at 7.5 years (95% confidence interval of 0.730 to 0.974). The revision rate due to a deep infection in our study is 2.7%.

Discussion: We conclude that patients who have a total hip arthroplasty after a hip injection do not have an adversely high rate of deep infection.

This study was designed to identify the radiological changes of the knee that correlated with an unfavorable outcome when treated with an intra-articular knee viscoelastic supplementation. A prospective cohort of 60 patients receiving a standard course of intra-articular knee viscoelastic supplementation with a commercial uncrosslinked hyaluronic acid derivative of an intermediate molecular weight were studied.

Follow-up was for 12 weeks post treatment with clinical improvement measured using the Western Ontario and McMasters Universities Osteoarthritis Index. Radiographs of the relevant knee were viewed and graded for the severity of joint space, osteophyte, tibial spine, sclerosis, cyst formation, alignment and general severity by an observer blinded to the outcome of the treatment.

There were no appreciable differences noted in the age, sex, length of follow up, prior treatment, the severity of symptoms before treatment and number of intra-articular injections given per course in each radiographic category identified. There was a significant amount of improvement in patients with a minor loss of medial and lateral joint space in all outcome measures. Minimal changes in tibial spine and global appearance also indicated a positive outcome in stiffness, pain and overall improvement. Thus, patients with moderate to severe osteoarthritic changes in joint space on radiographic examination would not significantly benefit from intra-articular knee viscoelastic supplementation. In addition, we feel that changes in the tibial spine and global appearance are not reviewed consistently enough to be included as part of our recommendation. As such, we conclude that only patients with a minimal to mild loss in joint space on radiological examination should form part of the target group who are likely to benefit from intra-articular knee viscoelastic supplementation.