Joints

Fibrous

• Strong
• Stable
• Little movement

Primary cartilaginous

• Bones connected by hyaline cartilage
• Temporary joints - growth plates
• Permanent joints with little movement

Secondary cartilaginous

• Bones connected by fibrocartilage
• Slight movement

Synovial

• Consider replacement if required
• Hinge, saddle, plane, pivot, ball and socket
• Smooth surface on bone - hyaline cartilage
• Lubricated environment - synovial fluid
• Something to produce lubrication and feed smooth bone - synovial membrane
• Supporting structures to allow movement - joint capsule, strong ligaments

Damage

• Interfere with any properties needed to create it
• Smooth
• Lubricated
• Capsule and ligaments
• Nutrition - hyaline cartilage

Wear and repair cycle

• Hyaline cartilage
  • Chondrocytes and 80% water content and ECM (type 2 collagen and proteoglycans)
• Constant creation and degradation of articular cartilage
• Injuries above tidemark cannot heal - blood supply is below the tidemark
• Injuries below the tidemark heal with fibrocartilage

Joint replacement

• Don't have to replace the whole joint
• Suggests a more radical procedure - resurface
• Human made materials to restore function

Why replace

• Joint damage beyond repair - can be due to arthritis
• Intrusive pain
• Significant loss of function and stability
• Consequent impairment to activities of daily life
• Trauma - loss of blood supply, unreconstructable joint
• Symptoms unbearable
• Nothing works
• Losing independence - reliant on others
• Cannot leave home - fear of falling

Knee joint

Symptoms

• Knee pain
• Start-up stiffness
• Unstable
• Worse pain going up or down stairs
• Reduced distance that can be walked
• Increased dependence on walking aids and pain killers
• Knee changes shape and swollen
• Gait
• Can't keep up/ride/kneel

Signs

• Look
  • Quads wasting
  • Varus or valgus
• Feel
  • Knee swelling/effusion
  • Global/lateral or medial pain
  • Knee crepitus
• Move
  • Fixed flexion deformity
  • Reduced range of movement
  • Posterior cruciate ligament deficient knee

Hip joint

Symptoms

• Ache in groin
• Sleeping with pillow between legs to help with pain
• Cannot get into a comfortable position at night
• Referred pain to the knee
• Back pain due to gait
• Painful walking - antalgic gait
• Walking stick
• Reliance on pain killers

Signs

• Look
  • Fixed flexion arising from hip
  • Leg length discrepancy
  • Leg in external rotation
• Feel
  • Pain on groin palpation
  • Tender over the greater trochanter
• Move
  • Hip flexion cause grown pain
  • External rotation preserved
  • Internal rotation ab/adduction reduced

Shoulder joint

Symptoms

• Pain
• Stiffness
• Inability to participate in upper limb sports

Signs

• Look
  • Swelling
  • Deltoid wasting
  • Shoulder girdle wasting
• Feel
  • Marked crepitus
• Move
  • Reduced abduction, forward flexion, internal rotation

Intra-articular injections

• Diagnostic or therapeutic
• More therapeutic earlier on in disease progression
• Can be definitive treatment in the very comorbid
• Associated with joint infection risk
• Primary care/surgeon/radiologist

Surgical risks

• Bleeding
• Infection
• Scar
• Nerve, vessel or tendon injury
• Fractures
• Dislocations
• Revision
• Ongoing pain
• Death
• No change in symptoms

Complications

• Infection
• 1% risk for any arthroplasty
• Increase in arthroplasty = increased burden on resources when complications occur
• Infected joint has an 80% chance of eradication
• Long inpatient stay
• Protracted treatment
• Impact on patient mental health
• Mortality similar to colorectal cancer
• Sepsis
• Aseptic loosening - implants loosen over time

Reducing infection

• Optimising patients pre-op
• Laminar flow theatres
• Sterilised implants
• Hand washing
• Antibiotic prophylaxis
• Timely surgical procedure
• Cannot account for haematogenous/dental/cardiac/traumatic causes

Modes of failure

• Dislocation
• Clinical presentation
• Limb short and externally/internally rotated
• Painful/painless
• Present with sciatic nerve palsy
• Deep vein thrombosis/pulmonary embolism - increased incidence in hip and knee replacements
• Early mobilisation post-op
• Prolonged wound ooze
• Patient compliance
• Expensive