02.16.2015
- Action Points
- Note that this randomized trial of hyaluronic acid versus betamethasone, injections for knee osteoarthritis demonstrated that effects at 1 year were superior in the hyaluronic acid arm.
- Be aware that significant differences in BMI between the groups leads to some concern about randomization quality.
Intra-articular injections of both hyaluronic acid and steroids were associated with symptom improvement in knee osteoarthritis (OA), but the pattern of response differed between the two treatments, a prospective, randomized study found.
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At 3 months, patients who had injections of betamethasone had a 66.3% reduction in pain (95% CI 63.3-69.3) compared with a 48.5% reduction (95% CI 45.8-51.3) for those given hyaluronic acid injections (P<0.0001), according to Cesareo Angel Trueba Davalillo, MD, of the School of Medicine, Universidad Nacional Autonoma de Mexico in Mexico City, and colleagues.
However, by 12 months, the mean decrease in pain in the hyaluronic acid group was 33.6% (95% CI 31.1-36.1) compared with only 8.2% (95% CI 5.2-11.1) among those receiving betamethasone (P<0.0001), the researchers reported online in Open Access Rheumatology: Research and Reviews.
Injections of corticosteroids have been used for 6 decades in knee OA, and various treatment guidelines, including those of the American College of Rheumatology and the Osteoarthritis Research Society International, recommend them.
Injections of hyaluronic acid, first described more than 20 years ago, also are widely used today as a nonsurgical therapy for knee OA.
“Hyaluronic acid is a key molecule in joint biomechanics because of the fact that treatment with exogenous hyaluronic acid contributes to the restoration of the elastic and viscous properties of the synovial fluid, resulting in pain reduction and functional improvement,” the researchers explained.
“Moreover, different studies have confirmed that hyaluronic acid interacts with inflammation mediators and matrix turnover in joint cells, reduces the apoptosis of chondrocytes, and exerts a biosynthetic-chondroprotective effect,” they added.
Previous studies comparing the two have been hampered by small numbers and short duration and have had conflicting results, so Davalillo and colleagues enrolled 200 patients with grades II and III radiographic OA for a yearlong study.
The treatment consisted of five weekly intra-articular injections of hyaluronic acid (2.5 mL of 1% hyaluronic acid) or two injections one month apart of betamethasone dipropionate, 5 mg plus 2 mg in 1 mL betamethasone sodium phosphate.
Before each injection, arthrocentesis was done to clear any effusion. For the first month, all participants also received glucosamine (1,500 mg) plus meloxicam (15 mg) followed by a month of glucosamine (1,500 mg) plus chondroitin (1,200 mg).
The majority of patients were women and mean age was 63.
Body mass index was significantly higher in the hyaluronic acid group (28.3 versus 26.3 kg/m2, P=0.002) and more were obese (40.2% versus 24.5%).
At baseline, global pain scores were higher in the betamethasone group (6.6 versus 6.1, P=0.004), while functional status as rated on the Western Ontario McMaster University Osteoarthritis (WOMAC) was worse in the hyaluronic acid group (53.2 versus 48.4, P=0.001).
WOMAC function scores favored hyaluronic acid at months 3, 6, 9, and 12, with mean improvements of 47.5% (95% CI 45.6-49.3) at the end of follow-up compared with 13.2% (95% CI 11.4-14.9) in the betamethasone group (P<0.0001).
The percentage of patients achieving a minimal clinically important absolute improvement of 15 out of 100 points was almost 100% in both groups at 6 months. However, by 9 months the percentage in the hyaluronic acid group was 81.4% but only 9.2% in the betamethasone group (P<0.0001).
And the minimal clinically important relative improvement of 20% was seen in 87.6% of the hyaluronic acid group at 9 months compared with 10.2% of the betamethasone group (P<0.0001).
Similar numbers of patients (67%) in the two groups reported using acetaminophen as a rescue medication during the study.
The only adverse events reported were pain from the injection in four patients receiving hyaluronic acid and two given betamethasone, and one case of erythema in the hyaluronic acid group.
As to the changes in response over time, with more rapid pain relief being seen with betamethasone and better function throughout with hyaluronic acid, Davalillo and colleagues wrote, “It has been reported that corticosteroids have a short-term effect on pain but have no effect on function, whereas hyaluronic acid products can provide a more durable response with relief of pain and improvement in function, although the onset of these effects is slower.”
A limitation of the study was baseline differences between the two groups, especially in body mass index and obesity.
The authors reported no conflicts of interest.