A SUCCINCT REVIEW OF OSTEOARTHRITIS



OSTEOARTHRITIS

Osteoarthritis affects approximately 10% of 40-year-olds and 50% of 60-year-olds. Approximately 80% of us will develop some degree of degenerative change in our joints. Degenerative change in the joints appears to be the result of a normal aging process of cartilage. This can be exacerbated by abnormal stresses on the joints due to activity or body habitus.

PATHOGENESIS

In the early stage of osteoarthritis, there is increased water content in the cartilage with an altered proteoglycan matrix. Mild fibrillation of the cartilage develops. In the intermediate stages, there is progressive fibrillation and abrasion of the cartilage resulting in shearing and thinning. There is necrosis of chondrocytes and the gradual development of osteophytes and the buttressing of the subchondral bone. Eventually, calcified cartilage is exposed and the cartilage is repaired and replaced with fibrocartilage which is not as elastic. Subchondral bony cysts and sclerosis develop with eventual bony necrosis and collapse. There is evidence of a variety of inflammatory mediators in the process.

DIAGNOSIS

The key to diagnosing OA lies in the joint distribution. The following joint patterns should be committed to memory:

1. The hand – DIPs (Heberden’s nodes) and PIPs (Bouchard’s nodes) are commonly involved. The MCPs and wrists are not involved unless there is a specific history of trauma. The 1st carpal-metacarpal joint is commonly involved and often overlooked by practitioners. In contrast, in rheumatoid arthritis the DIPs are spared and the PIPs, MCPs and wrists are commonly involved.

2. The arms – The elbows and shoulders are rarely involved in osteoarthritis since they are not weight bearing. Pain in these areas is usually due to tendinitis.

3. The spine – The cervical and lumbar spine are commonly involved in OA.

4. The legs – The hips and knees are commonly involved. Knee involvement is usually in the medial compartment but can involve the lateral compartment and the patellofemoral joint.

5. The feet – The ankles are rarely involved in OA. The tarsal bones and MTPs are commonly involved in OA. However, there are a myriad of other painful conditions of the feet which can mimic the pain of OA.

X-rays are useful for diagnosing early 1st CMC osteoarthritis. X-rays of the cervical and lumbar spine are not particularly useful since they do not change management. X-rays of the hips and knees are useful in determining the severity of OA and subsequent management. Surgical therapy should be considered for severe involvement of the hips and knees.

Joint aspiration and analysis of synovial fluid is useful only when there is a clinical suspicion of other conditions.

RISK FACTORS

It is clear that certain occupations lead to a higher incidence of osteoarthritis. It has been shown that pneumatic drillers develop more elbow and wrist OA. Eloquent studies have demonstrated that workers using particular fingers in their task will develop an increased amount of OA in the overused digits. Miners, truckers, and nurses develop more back OA. Obesity has been shown to be a risk factor for development of OA of the knees and lumbar spine but not of the hips. Females with a family history of OA involving the fingers are more likely to develop this condition.

TREATMENT

It has been shown that exercise in general is beneficial for joint stability. Walking programs have led to an improvement in symptoms in patients with knee OA. It has also been shown that weight loss reduces the risk of developing OA. Patients should be encouraged to exercise regularly, consider the initial assistance of physical therapy in setting up a program. Patients should engage in activities such as swimming or walking and avoid impact on the joints such as running. Canes, walkers and other adaptive equipment unload damaged lower extremity joints. Patients who are functionally limited due to OA should see an occupational therapist for assistance in activities of daily living and adaptive equipment.

Patients can try physical modalities such as hot and cold packs, massage and ultrasound. Many patients subjectively benefit from arthritic balms including OTCs and Voltaren gel. Capsaicin cream is useful for pain relief if patients can tolerate the local burning sensation associated with its use.

The mainstays of medical therapy are analgesics and nonsteroidal anti-inflammatory medications. Analgesics such as Acetaminophen are as efficacious as low dose NSAIDs (Bradley NEJM 325, 87, 1991). NSAIDs are useful if patients are not at high risk of gastric and renal complications of NSAIDS. In these patients, analgesic or mild narcotic use is indicated.

Intra-articular corticosteroid injections have been shown to be useful in several controlled trials. Pain relief from injections tend to last 2-3 months. A recent NIH study has demonstrated no significant joint deterioration on MRI scans of knees randomized to 2 years of quarterly injections. We will inject knees every 3-4 months as needed.

If patients fail steroid injections and NSAIDs and are not surgical candidates, they may benefit from a Synvisc-1 injection. This gel will act as a joint lubricant and provide 6-9 months of pain relief. However, it is expensive and some studies have shown no benefit over steroids. A prior authorization from insurance should be obtained prior to injection due to its expense.

The final therapy is arthroplasty or total joint replacement. This is 90% successful in the hip with a low complication rate. The success rate in the knee is a bit less. Candidates should have moderate to severe arthritis on xray, and should have significant functional limitations due to their arthritis that should be improved by the procedure. Though individualized, the ideal candidates would be 60 – 70 years old – replacing younger patients routinely would lead to more “re-dos” after the 15 -20 year life expectancy of the prosthesis. Patients older than 70 will accumulate more medical risk factors for surgical complications. The surgery is less successful in obese patients – hence you may consider discussing weight loss options to obese patients with moderate hip or knee arthritis in their early 50s in anticipation of eventual surgery.

TB 2016

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