Published: May 20, 2013 | Updated: May 20, 2013

By Nancy Walsh , Staff Writer, MedPage Today

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In this study, adults with at least 3 months of painful knee osteoarthritis were randomized to blinded injection (dextrose prolotherapy or saline) or at-home exercise.
Dextrose prolotherapy resulted in clinically meaningful sustained improvement of pain, function, and stiffness scores for knee osteoarthritis compared with blinded saline injections and at-home exercises.

Injection of a sugar solution into the joint significantly improved quality of life among patients with osteoarthritis in the knee, a randomized study showed.

In patients who underwent the dextrose injections — a treatment known as prolotherapy — scores on a knee-specific quality of life scale at 1 year had risen by 15.32 points, which represented a 24% improvement, according to David Rabago, MD, of the University of Wisconsin in Madison, and colleagues.

In contrast, participants who were given saline injections had increases of 7.59 points (P=0.022 versus dextrose) and those who followed an exercise program showed increases of 8.24 points (P=0.34), the researchers reported in the May/June issue of Annals of Family Medicine.

Prolotherapy has been used for 75 years to alleviate chronic articular pain, although most reports and studies have been of questionable methodology.

“Contemporary hypotheses suggest that prolotherapy stimulates local healing of chronically injured extra- and intra-articular tissue, though definitive evidence is lacking,” Rabago and colleagues wrote.

To address that gap, they enrolled 90 adults with an average of 5 years of pain in one or both knees.

Two-thirds were women, mean age was 57, and three-quarters were overweight or obese.

In the two injection groups, the procedure was done at weeks 1, 5, and 9, and then again at weeks 13 and 17 if the investigators felt this was warranted.

Multiple punctures were first made around the knee at various tendon and ligament sites and 22.5 mL of the hypertonic dextrose or saline placebo injected. This was followed by an intra-articular injection of 6 mL additional fluid.

Patients randomized to the exercise group were given a booklet about osteoarthritis and taught a series of home exercises that they were advised to perform regularly, increasing the frequency as tolerated.

The primary outcome measure was the change from baseline on the Western Ontario McMaster University Osteoarthritis Index (WOMAC), which combines scores for pain, function, and stiffness on a 100-point scale.

In the dextrose group, 17 patients had injections in only one knee, while 13 had treatment in both knees.

In the saline group, 15 had a single knee treated, while 13 had both.

In both groups, the average number of treatment sessions was four.

In the exercise group, 77% said they were adhering to the program.

On the WOMAC, the “minimal clinically important difference” has been established at 12 points. A total of 50% of the dextrose group achieved that, compared with 30% and 24% of the saline and exercise patients, respectively.

By week 9, significant differences were already seen for the dextrose group, with an increase of 13.91 points compared with 6.75 points (P=0.20) in the saline group and 2.51 points (P=0.001) in the exercise group.

On the WOMAC function subscale, significantly better scores were seen at 6 months among patients receiving the dextrose injections, with an increase of 17.19 points, compared with 7.62 points (P=0.005) in the saline group and 9.30 points (P=0.018) in the exercise group.

Frequency of knee pain showed greater reductions at 1 year in the dextrose group (-1.20,P<0.05) compared with the saline (-0.60) or exercise (-0.40) groups.

A similar pattern was seen for the severity of knee pain, with a change of -0.92 (P<0.05) at 1 year for patients receiving the dextrose injections compared with changes of -o.32 and -0.11 in the saline and exercise groups, respectively.

During the study, 14 patients in both injection groups used nonsteroidal anti-inflammatory drugs, as did 15 in the exercise group.

All patients receiving injections reported mild-to-moderate pain after the procedure, and one-half to two-thirds used oxycodone before or after the injections.

A total of 91% of the dextrose group said they would recommend the treatment to others, as did 82% of the saline group and 89% of the exercise group.

Several possible mechanisms have been proposed as being responsible for the effects of prolotherapy, including stimulatory effects of dextrose on damaged tissue and induction of growth factors, as well as direct effects of the needles on articular and peri-articular tissues.

Further studies will be needed to establish doses, to provide radiologic evidence of change, and to explore the mechanisms of effect.

“Determination of clinical utility of prolotherapy will require confirmation in a larger effectiveness trial that includes biomechanical and imaging outcome measures to assess potential disease modification,” Rabago and colleagues stated.