Osteoarthritis

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    Osteoarthritis

    • The most common MSK problem. (80% age >55yo, and 90% >65yo)
    • Biomechanical process where joints respond pathologically to mechanical stress
      • Causes cartilage degradation and changes in subchondral bone. 
    • F>M (2:1) 

     

    Risk Fact ors

    • Typically any overuse, trauma, genetics, or increased load (obesity) are risk factors
    • Example:
      • Age, Female, Obesity
      • Occupation, Sports Activities, Previous Joint Injury
      • Muscle Weakness, Proprioceptive deficits
      • Genetic Elements
      • Acromegaly
      • CPPD Disease
    • Often depends on joint involved
      • Knees: Obesity is biggest risk factor
      • Hands: Genetics is biggest risk factor
    • Obesity is a modifiable risk factor

     

    Joints Involved

     

    joints OA.png

    • Usually load-bearing joints
    • Any joint that has previous trauma/injury/inflammation
    • Hand: PIP and DIP involvement (+bone spurs cause Bouchard's and Heberden's nodes)
    • Thumb: CMC joint 1st digit... squaring of contour of joint.
    • Knees: Usually on weight bearing - asymmetric joint space narrowing (medial usually), causes valgus/varus deformity
    • Hip: Groin Pain

     

    Clinical Features

    • Presentation:
      • Peripheral Joints
        • Pain, loss of function
        • Although "non-inflammatory", but inflammation can occur in flares.
          • Inflammatory episodes correlate with progression
        • Worse with activity (unlike RA)
        • Morning stiffness can occur, lasts < 30min
        • Sx depend on joints:
          • Hip --> Groin Pain (not lateral)
          • Knee --> On weight bearing
        • Patello-femoral Joint --> climbing/descending stairs, or sitting in chair for long time
      • Axial Involvement
        • Back pain!
        • Pain not due to joint disease, but due to nerve root foraminal narrowing or spinal compression inside canal --> radiculopathy, sciatica, pseudoclaudication, myelopathy
    • Physical Exam
      • Inspection
        • Valgus Deformity (lateral joint space narrowing)
        • Varus Deformity (medial joint space narrowing) [more common]
        • Bony Enlargement
      • Palpation: Temperature, Pulses, 
      • Hand
        • Ulnar Deviation
        • Ulnar styloid prominence
        • MCP, PIP swelling or wrist swelling, r/o dactylitis
        • Subluxation particularly of the MCP joints
        • Swan neck or boutonniere's deformity
        • Z deformity
        • Nodules and ganglion cysts
      • Special tests
        • CMC arthritis vs. DeQuervain's Synovitis (Finklestein's test)
        • Joint line tenderness (esp medial compartment)
      • etc

    Imaging Findings

    • 1. Asymmetric Joints Space Narrowing (load bearing)

      Xray Knee OA.jpg

    • 2. Osteophytes
    • 3. Subchondral Sclerosis (joint compensating for cartilage damage).
    • 4. Bone Cyst Formation
    • 5. Eburnation
    • Spine:
      • Cystic Changes
      • Disc Narrowing + collapse
      • Facet osteophytes
      • Spondylolisthesis (Spine misalignment)
      • Scoliosis/Kyphosis
    • Knee: Medial compartment joint space narrowing

     

    Classification

    • Erosive OA
      • OA with lots of inflammation and erosions.  On X-Ray looks like psoriatic arthritis. 
      • Usually DIP and PIP.
      • Joints usually red/warm, but will have OA bony enlargement. 
    • Primary OA
      • Axial skeleton, weight-bearing joints (hip/knee joints), hand (IP and CMC joins).
    • Secondary OA
      • Due to joint injury or metabolic diseases (i.e. prev damaged by inflammatory conditions)
      • Usually, OA features in "wrong joints" for OA
      • Most common:
        • Chondrocalcinosis
        • Hemochromatosis
    • Diffuse Idiopathic Skeletal Hyperostosis (DISH)

      dishXray.jpg

      • Calcification of spinal ligaments --> large flowing osteophytes.
        • Discs are spared 
        • Thoracic involvement is earliest (most common)
        • Enthesis calcification (where tendons/ligaments insert) can occur
      • Occurs in Obese men > 50yo
      • Can be asymptomatic, or have stiffness and decreased ROM of spine (mostly thoracic)
      • Diagnosis
        • In Imaging: flowing osteophytes across 4 contiguous vertebrae
      • Difference Ankylosing Spondylitis
        • Feature DISH Ank Spond
          Osteophytes/Syndesmophytes Horizontal ("Flowing") curve out/in Vertical
          Location Thoracic Spine & patchy distribution SI joints and Lumbar Spine
      •  
    • Disease Severity
      • WOMAC
        • Western Ontario Mcmaster University OA Index
        • Functional assessment

    Treatment

    • Non-Pharmacological
      • ADAPT Trial - Arthritis Diet Activity Promotion Trial 
        • Impact of weight loss, exercise combo therapy vs. healthy lifestyle for OA
        • Found diet and exercise groups had less pain and more function at 6mo. 
        • Weight loss and exercise (combined) had the best outcomes. 
      • Exercise - none is bad, high impact competitive sports can predispose to OA
        • Walking (Activities such as walking are good activities)
        • Water Therapy (well tolerated (warm water pool)
        • Weight Reduction (Risk factor, and increases symptoms.  Even 10lb helps substantially)
      • Biomechanics (Unloading joint)
        • Unloading Knee/Hip Braces
          • Braces for hip/knee (biomechanics)
          • Brace unloads affected joint, and distributes load to the other extremity. 
          • Works only with asymmetric arthritis obviously.
          • (NOTE: Wedge shoe inserts = no benefit)
        • Using Caine
          • Unloads affected joint
        • Hand
          • Large grip utensils, keyholders, 
      • Diet
        • Weight loss!
        • AVOID high saturated fat diet (avoid fructose!!)
        • More fatty acids (Tumeric has some evidence)
      • Patient Education
        • Arthritis Foundation Foundation Self-Mgmt Program (participation = less disability)
    • Pharmacological
      • Topical (some relief)
        • Topical diclofenac: Pennsaid lotion 1.5% (40 drops to knee)
        • Voltaren emugel is OTC: is also diclofenac but in ointment form
        • Lidocaine patches (super expensive), Lidocaine cream (cheaper)
        • Topical Arnica, ice, heat
        • Capsaicin topicals (hot peppers alter nerve endings)
      • Analgesics
        • Tylenol (safest)
        • NSAIDs (have evidence if don't respond to acetaminophen)
        • Cox2 Inhibitors (high risk of GI s/e, avoid in high CV risk)
      • Articular Injection
        • Only when single joint or few joints (worse than other joints) + limits function
        • Cortisone Injection
          • Must do every 3-4mo (stops working after 2-3 times)
          • Drawbacks:
            • Soft Tissue Atrophy
            • Stops working after 2-3 times
            • Infection/bleeding complications are rare
        • Hyaluronic acid injections:
          • most beneficial in mild-to-mod OA (EXPENSIVE - $450/needle), lasts 6mo
          • Unclear how it works (lubrication?), substance cleared from joint in 24-48hrs
          • Clinical Trials: modest effect, but statistically significant
        • Platelet rich plasma injections: likely beneficial
      • Opioids
        • Only role for acute severe pain. NOT chronic pain.
        • Nerve blocks, steroid injection first
      • Surgery (Joint Replacement)
        • Joint Replacement is HIGHLY EFFECTIVE, but due to morbidity it is last line.
          • Arthroscopy NOT INDICATED. (RCT = no effect)
        • 90% significant functional improvement
        • Knee replacement longer recovery than hip
        • Back to driving in 6w, fully recover by 6mo, many patients say takes 12mo to get full benefit. 
        • PT post-surgery is CRITICAL
        • MUST be motivated to participate in PT, and have good social support!
    • NOTE:
      • Glucosamine: no benefit in large studies (advise to try it for few months, if no help can stop)
      • Hyaluronate injection: Only indicated for mild-to-moderate arthritis.
      • Knee Arthroscopic Lavage/debridement: RCT shows no benefit. (unless meniscal tear (catching/locking).
      • Osteotomy (removes wedge of bone to realign axial load on joint)  --> studies show improvement in pain in young patients, but likely similar benefit as maximal medical therpay. 
      • Accupuncture - no benefit
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