Patients with osteoarthritis may derive little benefit from hip arthroscopy because a high proportion go on to have total hip arthroplasty within a short time, according to Victorian orthopaedic surgeons.

While the minimally invasive procedure is increasingly being used in the belief that it can delay progression of OA, surgeons at the Epworth Hospital in Melbourne have shown that OA patients are five times more likely to have a THA within two years of arthroscopy compared to people without OA.

In a review of outcomes for 947 patients undergoing hip arthroscopy procedures at the hospital between 2004 and 2013, they found that 13% of patients progressed to THA within two years.

In their study, OA was present at arthroscopy in 31.5% of patients. Early progression to THA occurred in 29% of OA patients and in 6% of patients without OA.

On multivariate analysis, OA was a risk factor for progression to THA within two years (Odds Ratio 4.6). The only other independent risk factor for early progression to THA was previous arthroscopy of the ipsilateral hip (OR 2.6).

The likelihood of early THA increased with age, with 25% in 50-59 years age group having early THA, 37% at 60-69 years of age, and 50% of patients over 70.

Obesity was also identified as a risk factor for early THA but only in univariate analysis.

Writing in Australia and NZ Journal of Surgery, study author Dr Brendon McCarthy notes that rates of hip arthroscopy have increased 600% in recent years in Australia, so it is important to ensure that all patients having the procedure are likely to gain clinical benefit.

The 13% rate of progression to THA within two years is similar to that seen in other international studies, and likely represents a group of patients who might be better managed without surgery initially, but with future planning for THA, he writes.

Knowing that OA is a risk factor for progressing to early THA should help inform discussions between patients and their clinicians about  appropriate indications and expected outcomes from arthroscopy, Dr McCarthy and co-authors say.

“The success of arthroscopy in patients at higher risk of early progression to THA may be considered with reference the patient’s expectations and individual goals. Patients who identified short-term goals following their arthroscopy and were able to meet these goals before undergoing THA may consider their hip arthroscopy successful despite the early need for THA.”

“Those patients with goals or expectations following their arthroscopy that were unable to meet these because of their early THA may, however, consider their arthroscopy as unnecessary,” they conclude.