Background: Intra-articular knee injections with hylan GF-20 (Synvisc) have been shown to provide temporary relief of osteoarthritic symptoms. Several studies have suggested that repeated courses of treatment with this product may be administered without an increase in the likelihood of an adverse reaction. The present study was performed to test the hypothesis that the likelihood of a painful reaction to hylan GF-20 does not increase in patients who receive more than one course of treatment.
Methods: The records of all patients who had received more than one course of treatment with hylan GF-20 were compared with a group of patients who had received only one course of treatment during the same fifteen-month period at a single center. The single-course group was prospectively enrolled and followed, as part of an ongoing randomized trial. The two groups were compared with respect to several demographic and clinical parameters as well as with respect to the frequency of painful acute local reactions following injections of hylan GF-20.
Results: Local reactions to hylan GF-20 occurred significantly more often in patients who had received more than one course of treatment than they did in patients who had received only a single course of treatment; the reactions occurred in four (21%) of nineteen patients in the former group and in one (2%) of the forty-two patients in the latter (p = 0.029). All of the reactions were severe enough to cause the patient to seek unscheduled care. Following corticosteroid injection, the reactions abated without apparent sequelae. With the numbers available, no significant differences were detected between the multiple-course and single-course groups in terms of age, gender, body-mass index, or severity or bilaterality of the disease.
Conclusions: The present study suggests that it may be reasonable to counsel patients who have been treated with a course of hylan GF-20 and who desire an additional course that the likelihood of a painful acute local reaction to the medication appears to be increased. Additional study of the frequency of acute local reactions following repeated courses of hylan GF-20 and investigation of the mechanisms of those reactions are warranted.