Synvisc-OneTM for the treatment of knee osteoarthritis

Osteoarthritis (OA) is a chronic, progressive, degenerative disease that affects many joints and is the most common type of arthritis. OA is classified as idiopathic, or as secondary, owing to traumatic, congenital or medical causes. It is characterized by the progressive loss of hyaline cartilage leading to joint space narrowing, osteophyte formation and bony changes. Patients with OA typically present in their later years with pain, swelling, stiffness and varying functional limitations [201]. Osteoarthritis affects approximately 27 million Americans with nearly a third of individuals over the age of 65 years having some form of OA [1]. The knee is considered one of the more common sites of developing OA, with a symptomatic prevalence ranging between 10–16% of individuals over the age of 45 years [2–4]. The overall radiographic incidence of knee OA is 2% per year, with a symptomatic incidence of 1% per year [5]. This incidence rate increases with age until the age of 80 years at which time the incidence rate plateaus. In addition, there seems to be an increased prevalence of knee OA in females, especially after the age of 50 years [6,7]. The diagnostic criteria set forward by the American College of Rheumatology (GA, USA) for knee OA are based on individuals over the age of 50 years and permutations of clinical, radiographic and laboratory evaluations, which include knee pain for most days over the previous month and osteophyte formation at the joint margin [8]. The pain associated with knee OA has profound effects on quality of life and general functional ability. In fact, knee OA is one of the top five leading causes of disability in non institutionalized adults [9]. Therefore, it is easy to see how the treatment of knee OA affects the general wellbeing of a large number of individuals as well as the associated medical costs inherent in such a debilitating disease. The exact mechanism by which certain individuals develop OA while others do not is poorly understood. However, there are modifiable and non-modifiable risk factors associated with the development of knee OA (Table 1). Treatment options for knee OA focus on addressing modifiable risk factors. Medical therapies are not considered curative for knee OA; they are adjuncts in the treatment of the symptoms associated with the disease. The goals for treatment include controlling pain, improving function and return to normal life activities. These are accomplished by a combination of pharmaco logical and nonpharmacological means. For example, treatments include exercise, weight control, physical modalities, alternative treatments and medications. Medication treatment for OA typically begins with acetaminophen and/or NSAIDS. NSAIDs are widely accepted as a treatment option; however, they are associated with an increased risk of gastrointestinal and cardiovascular side effects [10,11]. Estimates Knee osteoarthritis is a chronic, progressive, degenerative disease that most commonly presents in individuals over the age of 50 years with symptoms of pain, swelling, stiffness, crepitus and functional limitations. It is characterized by the progressive loss of hyaline cartilage resulting in joint space narrowing and bony changes. Furthermore, the synovial fluid contained within osteoarthritic joints, of which hyaluronan is a major protective constituent, undergoes a degenerative process. This has led to a treatment modality to replace hyaluronan, which is known as viscosupplementation. Viscosupplementation use has been supported by numerous studies and several meta-analyses to be safe and effective in ameliorating the pain and functional limitations associated with knee osteoarthritis. However, up until fairly recently, viscosupplementation was provided through weekly intra-articular injections over a course of 3–5 weeks. Synvisc-OneTM (Genzyme Biosurgery Corporation, MA, USA) is one example of a newly released and promising group of single-dose intra-articular injections that is proving to be effective, safe and convenient for the treatment of knee osteoarthritis.