Etiology of Osteo-Arthritis
The chronic pain associated with osteoarthritis arises from pain sensors in the subchondral bone rather than from the articular cartilage itself, which has no pain sensors [ACE-AHFS, pg 380].
Damage to the articular cartilage causes chemical synovitis, which arises when chemicals inside the damaged articular cartilage are released into the synovial fluid and irritate the type A synovial cells in the inner lining of the joint capsule, which in turn increase production of synovial fluid, leading to swelling of the joint capsule over the subsequent 12 hours and further pain due to the edema [ACE-AHFS, pg 381].
Specific factors leading to increased risk of osteoarthritis include [ACE-AHFS, pg 383] weak quadriceps [Bennell2005], [Mikesky2006], valgus or varus knee alignment, weak hip abductors, and obesity [Issa2006].
Dr. Starr has suggested a correlation between osteoarthritis and type-II hypothyroidism.
Diagnosis of Osteo-Arthritis
According to the Agency for Healthcare Research and Quality, Osteoarthritis of the knee can be diagnosed when joint pain is present plus five or more of the following criteria are met [Samson2007]:
- The patient is over 50 years of age
- Joint stiffness in the morning lasts less than 30 minutes (as opposed to Reumatoid Arthritis, where stiffness lasts longer).
- Crepitus is observed in the joint (due to absence or damage to articular cartilge).
- Bony tenderness is observed in the joint.
- Bony enlargement is observed in the joint.
- Signs of inflammatory disease (e.g. Rheumatoid Arthritis) are absent:
- No palpable warmth of synovium.
- Erythrocyte sedimentation rate (ESR) < 40 mm/hr.
- Rheumatoid factor < 1:40.
- Non-inflammatory synovial fluid.
Treatment of Osteo-Arthritis
For patients with chronic osteoarthitis pain, low-impact exercises (such as aqua-therapy and tai chi) may be useful [ACE-AHFS, pg 383], [Ettinger1997], [ Fransen2007], [Hinman2007], [ Lund2008], [Wang2007].
For patients who are relatively pain free, light- to moderate-intensity walking (up to 60 minutes 3 times a week) and light- to moderate-intensity resistance training (up to two sets of 12 repetitions of nine exercises) training three days per week can lower pain scores and increase functional ability [Ettinger1997], [Mikesky2006]. The American Council on Exercise gives specific exercise recommendations [ACE-AHFS, pp 383-389].
Although exercise can slow the progression of osteoarthritis, it is not a cure for osteoarthritis. However, there is no evidence that properly programmed and managed exercise will increase the rate of joint degeneration [ACE-AHFS, pg 383], as measured by joint-space narrowing [Mikesky2006] or pain scores [Ettinger1997], [vanBaar1999].
Exercise recommendations may be modified to include "the use of wrist straps or ankle or wrist weights and the performance of lower intensity and higher-duration activities" [ACE-AHFS, pg 377].
Dr. Hertogue notes that when treating osteoarthritis due to hypothyroidism, joint pains "improve very slowly and are the last symptoms to disappear" [Hertogue1914].
Evidence suggests that CosaminDS ® (glucosamine sulfate with a low-molecular chondroitin) 2-3 tabs TID provides better relieve of pain due to osteoarthritis and chemical synovitis than nonsteroidal anti-inflammatories such as Celebrex ® 200mg/day [Clegg et al., 2006].
Prevention of Osteo-Arthritis
It is important to correct any joint misalignment caused by spinal misalignment, antalgic posture or gait, ligamentous laxity, or muscle weakness (e.g. weak quadriceps [Bennell2005], [Mikesky2006], valgus or varus knee alignment, or weak hip abductors [Issa2006]) in order to prevent damage and minimize further damage to affected joints.
As discussed above, osteoarthritis is a sequel of repetitive microtrauma and instability of the affected joint, so it follows that avoidance of these insults to the joint by proper exercise aimed at strengthening the stabilizing muscles and ligaments is both preventative and therapeutic [ACE-AHFS, pg 379].
Sequelae of Osteo-Arthritis
Untreated osteoarthritis can reduce the physical activity of a patient, leading to secondary comorbitities due to a sedentary lifestyle, including: coronary artery disease, diabetes, and hypertension.