Therapeutic Challenges for Knee Osteoarthritis

One of the most common degenerative joint diseases among the elderly who refer to pain clinics is knee osteoarthritis, the characteristics of which are progressive cartilage loss in the knee joint, synovial membrane changes, and reduced viscosity of the synovial fluid. It causes pain, joint mobility limitations, disability, and poor quality of life. There is no specific, definite treatment, as yet, to reverse the destructive process involving joint inflammation for knee osteoarthritis, so the treatment is mostly symptomatic. Current consensus suggests that the knee osteoarthritis management should take a multidisciplinary approach involving conservative, surgical, as well as complementary therapies. Physical therapy, oral medications, and intra-articular injections are considered as conservative treatment employed as the first step to treat mild to moderate osteoarthritis of the knee joint. The main goal of these modalities is to attenuate joint pain, improve joint function and quality of life, and slow down the progression of the disease. Several drugs, particularly nonsteroidal anti-inflammatory drugs (NSAIDs), corticosteroid, glucosamine, and hyaluronic acid, have been considered as nonsurgical pain management for osteoarthritis of the knee. Hyaluronic acid is basically a natural glycosaminoglycan and a component of synovial fluid, which serves as a lubricant during joint movements. Intra-articular hyaluronic acid can restore the function of synovial fluid, protect against cartilage erosion, and alleviate synovial inflammation. It may also have some analgesic effect on the joints (1). Injection of intra-articular corticosteroids has shown significant anti-inflammatory effect, and can boost the relative viscosity and concentration of hyaluronic acid in the arthritic knee. The duration of action of intra-articular corticosteroid injections has yet remained controversial, lying somewhere between 1 to 24 weeks, as suggested by different studies. However, there is an agreement that steroids start to relieve pain approximately one week after intra-articular injection. In addition, there are controversies concerning the intra-articular corticosteroid administration owing to the chondrolytic effects on cartilage and synovium (2). Prolotherapy, also called “proliferation therapy,” refers to an injection of hypertonic dextrose, a treatment option for a variety of painful chronic musculoskeletal pain conditions, particularly knee osteoarthritis. The main practical principle of prolotherapy is based on the injection of relatively small volumes of an irritant solution, generally hypertonic dextrose, at painful ligament and tendon attachments, as well as in adjacent joint spaces. In recent years, prolotherapy has been used for the treatment of knee osteoarthritis obstinate to other conservative options. Reports from articles have documented positive effects in knee osteoarthritis; the findings have not been synthesized, however (3). An autologous concentration of human platelets by simple centrifugation of the patient’s blood, which contains many components, including growth factors, cytokines, etc., is referred to as platelet-rich plasma (PRP) (4). It serves as a carrier for a large amount of growth factors, with the function of increasing tissue repair, which is progressively being used in the treatment of knee osteoarthritis (5). Compared to the physiologic plasma, PRP maintains four to six times the platelet concentration. According to some reports, platelet-rich plasma may cause precursor cells to migrate, proliferate, and differentiate in the synovial fat pad or cartilage. As a result, platelet-rich plasma could augment the repair of damaged cartilage, while reducing the pain and inflammation. Several studies have compared platelet-rich plasma