Osteoarthritis (OA) of the knee is one of the most common problems seen by both rheumatologists as well as orthopedists in the office. The standard forms of therapy include maintenance of proper weight, exercise, application of cold, bracing, analgesics (pain killers), anti-inflammatory medicines, steroid injections, and viscosupplementation. This latter type of treatment involves the injection of a lubricant directly into the knee.

These lubricants consist of a purified form of a protein called hyaluronic acid (HA). These preparations are effective in relieving pain. pain relief from OA of the knee starts between the 5th and 13th week follwoing injection. While HA is felt to be effective for pain relief, it has been unclear as to whether there are any other benefits.

Two recent studies have demonstrated that viscosupplementation may actually forestall the need for eventual knee replacement surgery and also may represent a long term cost savings.

The first study from Louisiana State University surveyed patients from a large orthopedic practice. A total of 863 patients (1187 knees) were evaluated. All patients had grade 4 changes, meaning they had "bone on bone" and were candidates for total knee replacement.

Using survival analysis of the data, it was estimated that total knee replacement was delayed approximately 3.8 years in 75 percent of the knees receiving viscosupplementation (Waddell DD, et al. J. Managed Care Pharm. 2007; 2:113-121.)

In another study, investigators in Thailand studied one hundred and eighty three patients with knee OA (208 knees) who failed conservative treatments and did not have contraindications for surgery were enrolled. All patients were treated with one course of three hyaluoronic acid injections at weekly intervals and followed up for a minimum 2-year period. In case of successful treatment (response group), repeated doses were recommended. If the patients did not improve within one month after completion of the injections, they would be classified as a non-response group and total knee replacement surgery was considered. Cost of direct medical costs (drugs), hospitalization, and resource utilization were recorded and analyzed.

They concluded that IA-HA (joint injection with HA) should be considered as a medical intervention before surgical procedures in knee OA patients who failed conservative treatments. Even though the cost of IA-HA treatment would increase the total costs of treatment and some patients might fail, it was only 6.44% of the total costs. On the other hand, if patients responded to IA-HA treatment, then the surgical procedures were not required. This treatment would represent a savings of 63.26% of total costs. (Turajane T, et al. J Med Assoc Thailand. 2007; 90;1839).

While, the exact analyses and conclusions of these two studies are different, they do suggest that HA may be cost effectve in delaying the need for total knee replacement.

There are five HA preparations available. They are Hyalgan, Synvisc, Supartz, Orthovisc, and Euflexxa. Only Euflexxa is not derived from a chicken source.

The number of injections required varies from 3-5 depending on the preparation used. Hyalgan and Supartz generally are given as weekly injections for 5 weeks while Synvisc, Orthovisc, and Euflexxa are given as weekly injections for 3 weeks.

Thes injections should be administered using either fluoroscopic or ultrasound needle guidance to ensure accuracy.

Side-effects are minimal when administered by trained specialists.

HA injections are worth a try even with grade 4 knees if patients wish to delay surgery.