Why Gel Injections Are Not Recommended for Hip Arthritis
The American College of Rheumatology/Arthritis Foundation strongly recommends against hyaluronic acid (gel) injections for hip osteoarthritis because high-quality, low-bias trials demonstrate that the effect size compared to saline injections approaches zero, meaning they provide no meaningful benefit beyond placebo. 1
The Evidence Quality Problem
The apparent benefits of hyaluronic acid injections reported in earlier systematic reviews were driven by methodological flaws. 1 When the analysis is restricted to only high-quality trials with low risk of bias, the treatment effect essentially disappears—the benefit approaches zero compared to saline placebo injections. 1
The key distinction: Studies showing benefit were those with higher risk of bias, while rigorous studies failed to demonstrate efficacy. 1 This pattern strongly suggests that positive results in lower-quality studies reflected placebo effects, publication bias, or methodological weaknesses rather than true therapeutic benefit.
Hip vs. Knee: A Critical Difference
The evidence against hyaluronic acid is stronger for hip OA than knee OA. 1
- For knee OA, the ACR/AF provides only a conditional recommendation against use, acknowledging that some clinicians may still consider it after other treatments fail. 1
- For hip OA, the recommendation is strong (not conditional), reflecting higher-quality evidence of lack of benefit. 1
This stronger stance for hip OA is based on more definitive evidence showing no efficacy. 1
What the Research Actually Shows
Recent meta-analyses and systematic reviews confirm the guideline position:
- A 2021 systematic review of high molecular weight HA for hip OA found a standardized mean difference of only -0.056 for pain (VAS) and -0.114 for function (Lequesne index), with results that "do not favor treatment with HMWHA over other treatment methods." 2
- A 2015 meta-analysis found that while the overall mean VAS decrease was -1.97, when limited to the six randomized trials, the decrease was only -0.27—clinically insignificant. 3
- Most studies had follow-up durations of less than six months, providing no evidence of sustained benefit. 3
Potential Harms
Beyond lack of efficacy, there are concerns about harm associated with these injections. 1 While severe complications are rare, the risk-benefit ratio is unfavorable when the benefit is essentially zero.
What to Use Instead
For hip OA, corticosteroid injections are the evidence-based choice for intra-articular therapy when injection is warranted. 4
- Corticosteroids are supported by 19 high-quality and 6 moderate-quality studies. 4
- They provide effective short-term benefit (typically 3 months duration). 4
- They offer immediate symptom relief within 7 days (effect size 1.27). 4
- They require only a single injection versus 3-5 weekly injections for HA. 4
Treatment Algorithm for Hip OA
First-line treatments should include: 5
- Non-pharmacologic therapies (exercise, weight loss, physical therapy)
- Topical NSAIDs
- Oral NSAIDs
- Intra-articular corticosteroids (when injection is indicated)
Only after failure of these evidence-based treatments might one consider discussing HA injections in the context of shared decision-making that explicitly acknowledges the limited to absent evidence of benefit. 1, 5 However, given the strong recommendation against HA for hip OA specifically, proceeding to surgical consultation for hip replacement would be more appropriate than pursuing ineffective injections.
Common Pitfall to Avoid
Do not extrapolate the (weak) evidence for HA in knee OA to hip OA. 1 The hip joint has distinct biomechanics, different accessibility for injection, and most importantly, higher-quality evidence specifically showing lack of benefit. 1 The strong recommendation against HA for hip OA is intentionally more definitive than the conditional recommendation for knee OA. 1