Pain in Primary Care

Hip OA: What's the Best First Option?

Charles P. Vega, MD


August 10, 2021

My Take

I want this patient to feel better and gain function, but I am also worried about her chronic medical conditions and potential drug interactions. I'm going to choose the first option: acetaminophen up to 3g daily.

I can see the comments now: "Acetaminophen doesn't work!" "Acetaminophen won't improve physical function!" "You are a monster! Die! Die!"

Allow me to explain.

Acetaminophen is certainly not highly effective in the management of OA. A meta-analysis of 10 randomized, placebo-controlled trials of acetaminophen found that it improved pain and physical function scores for hip and knee OA by just 5% vs placebo. This difference may not be clinically meaningful, and subgroup analysis based on the daily dose of acetaminophen failed to alter the main conclusion.

This study also demonstrated that serious adverse events were rare with both placebo and acetaminophen, although the incidence of abnormal liver function testing was higher in the acetaminophen vs placebo group. The clinical significance of that finding is also debatable. Overall, the balance of modest efficacy but relative drug safety associated with acetaminophen is reflected in OA management guidelines from the American College of Rheumatology (ACR) and Arthritis Foundation (AF).

These guidelines provide a conditional recommendation for acetaminophen for OA of the hand, hip, and knee. They cite a weak record of efficacy vs placebo. However, they also note that acetaminophen may be appropriate for patients with "limited pharmacologic options." This patient certainly has limited options, particularly due to multiple comorbid illnesses plus potential drug-drug interactions.

Oral nonsteroidal anti-inflammatory drugs (NSAIDs) are recommended as a first-line intervention of OA in the ACR/AF guidelines, but NSAIDs are risky among patients receiving antiplatelet therapy to treat existing cardiovascular disease. In a retrospective analysis of adults with a first myocardial infarction treated with aspirin, clopidogrel, or oral anticoagulants, the use of NSAIDs was associated with a twofold increase in the risk of bleeding requiring hospitalization compared with no NSAID use. Moreover, the use of NSAIDs in these patients was associated with a 40% increase in the risk for another cardiovascular event. Subgroup analyses based on the type of antithrombotic therapy or type of NSAID failed to alter the main conclusions of the study.

Oral NSAIDs should be used with extreme caution in this patient. What about topical NSAIDs? These are a good option for OA of the knee, but the ACR/AF guidelines state that they are unlikely to penetrate to the deeper hip joint. The guidelines do not recommend topical NSAIDs for OA of the hip.

Finally, why not try an IASI for this patient's hip OA? That is a reasonable option. A systematic review of five small randomized controlled trials of IASI found that it was associated with improvements in hip pain for at least 3 or 4 weeks compared with placebo. The number of patients needed to treat with hip IASI to achieve treatment response at 8 weeks was 2.4, and IASI was well tolerated.

However, substantial hyperglycemia has been reported after IASI. Ultrasound guidance is recommended for IASI for the hip joint to both ensure therapeutic value as well as prevent systemic absorption of the corticosteroid.

A hip IASI would be a reasonable approach for this patient now, but I choose a short trial of acetaminophen for the following reasons:

  • The patient has taken acetaminophen occasionally with moderate relief. She might experience more relief with regular use. Most trials have used acetaminophen at dosages between 2 and 3 g/day, and I would recommend at least 3 g/day if her baseline liver function is normal.

  • This is a good time to emphasize nonpharmacologic treatment for hip OA. Weight loss, exercise, and even tai chi and the use of a cane can promote better outcomes for OA in terms of pain and physical function. She can get started on some of these interventions now, and they can supplement the efficacy of acetaminophen as primary pharmacotherapy.

The patient should be followed in about 4 weeks to recheck her symptoms and progress. If she is feeling better, she can continue to advance the nonpharmacologic treatment while using acetaminophen to manage her hip pain. If she is not improving, it is time to consider the IASI.

Overall, there is little to lose with a trial of acetaminophen plus exercise. It is not only a good plan with respect to patient safety, but it's very cost-conscious as well.

What do you think? I look forward to your comments! I'll post a follow-up in a few weeks to reveal the crowdsourced opinion on my management of this case.


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