Osteoarthritis

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

• 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)

  

• 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

• NOTE: Radiographic severity ≠ severity of symptoms
• Image Source: http://www.physio-pedia.com/

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)

  

  • 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