WEEK 5 - MINI LECTURES - OSTEOARTHRITIS Flashcards
What is OA
- progressive disease
- failed repair of joing damage that has been triggered by abnormal intra-articular stress
- synovial inflammation in OA may be secondary to breakdown of cartilage and bone
- all tissues of joint are involved
OA disease vs OA illness
- disease: radiographic OA: 30% of adult population
- Illness: pain: 10% of adults
Criteria for hand diagnosis of OA
- hand pain, aching, stiffness
3 or more of
- hard tissue enlargement of 2 or more of 10 selected joints
- hard tissue enlargement of 2 or more DIP joint
- fewer than 3 swollen MCP joint
- deformity of at least 1/10 joints
ACR criteria for diagnosis of knee OA: clinical and laboratory
- knee pain plus at least 5 of the following
1) >50 yo
2) stiffness for less than 30 min
3) crepitus
4) bony tenderness
5) bony elargement
6) no palpable warmth
7) ESR
ACR criteria for diagnosis of knee OA: clinical and radiographic
Knee pain + 1+ of the following:
- age 50+
- stiffness
ACR criteria for the diagnosis of knee OA: Clinical
- knee pain + at least 3 of the following
1) age 50+
2) stiffness
Criteria for hip OA diagnosis
- hip pain + 2+ of these features
1) ESR
Knee joint
- largest, most complex joint in the body
- synovial, modified hinge joint
- articular surfaces: patellar surface of femur to patella, and femoral condyles to tibial plateau
KNEE JOINT collateral ligaments
- fibular collateral ligament: round, cord like, separate from capsule, limits adduction
- Tibial collateral ligament: broad and flat, blends with joint capsule, attaches to medial meniscus and limits movement, limits abduction movement, more commonly damaged
Knee joint also stabilised by
- biceps femoris and ITT on lateral side
- sartorius, gracillis, semitendenosis, semimembranosus on medial side
Knee joint menisci
- fibrocarilage
- lateral meniscus more mobile
- medial mniscus more commonly injured
- thicker laterally
- outer part more supplied
Knee joint - synovial joint
- synovial joint caviry is the largest in the body -> communicates with suprapatellar bursae
- cruciate ligaments are outside the synovial joint cavity
- Bursae: 11 in knee joint: reduce friction between adjacent structures
- bursae in the anterior of the knee may become inflammed
Ligaments of the hip joint
- 3 major stabilising ligaments: iliofemoral, pubofemoral, ischiofemoral
- are thickenings of capsule
- taut on extension -> more stable
Synovial joints: normal morphology and function
- different tissues functioning together to enable movement, provide frictionless bearing and transmit load
- have proprioceptive function
- are able to adapt to different physiological requirements/loads
Bone morphology and function
- continuum from diaphysis to metaphysis to subchondral plate
- absorb and translate load
- rapidly adaptable - remodelling
- really about load bearing capacity
- 1st affected in OA
Cartilage normal morphology and function
- calcified and non calcified
- different morphology, biochemistry, metabolism and function deep to superficial and topographially
- compression resistant, frictionless
- surface: parallelly oriented
- deeper: more vertically oriented
Joint capsule, synoviu, synovial fluid: morphology and function
- filtration barrier: protein, cells: reduce cell influx
- immune privileged
- lubrication
- nutrition
Meniscus: morphology and function
- load translation, lubrication, proprioception
Ligaments and capsule: morphology and function
- ligaments (and capsule)
- constrain and regulate range of motion
- proprioception
OA - a disease of the joint organ - BONE
- increased bone formation: subchondral thickening, osteophytes, enthesophyte
- lower bone mineral density, increased turnover
- increased vascularity
- BML - necrosis, microfractute
OA - a disease of the joint organ - CARTILAGE
- loss of aggrecan early on (reversible)
- Collagen breakdown in late stages (irreparable)
- cartilage loss is an autplytic process: the cells taht lay down cartilage also produce proteins that break it down (ADAMTS)
- hypertrophic differentiation and apoptosis
- recapitulates grown plate
OA: a disease of the joint organ: JOINT CAPSULE, MENISCUS, LIGAMENT
- capsule fibrosis, loss of SF HA and lubricin
- inflammation - innate and adaptive
- altered biochemistry , loss of biomechanics
OA is NOT just a wear and tear - its an active disease
- respond to external signals
- drive the pathology and pain pathwyas
- interactions between structures
- extrinc factors
Study if you target one system
- different OA models compared in same GM strain
- 70% had same outcome
- 30% have a different outcome
- molecular pathophysiology differs with OA phenotype
- makes it difficult to find a treatment
4 general pathways of OA
- cartilage matrix degradation
- chondrocyte hypertrophic differentiation and apoptosis
- inflammation/synovitis
- bone turnover
Pain sensitive structures in the normal knee
- joint capsule
- ligaments
- outer third of meniscus, especially near capsule
- periosteal and subchondral bone
- synovium
- soft tissues including fat around and deep to patellar tendon
(LAST 3 MOST IMPORTANT)
Other reasons for pain
- pain behavior, distress, disability
- SES
- psychosocial comorbidity
- altered cortical processing, spinal cord gating, PNS…
Prevalence of kneee pain and OA in persons age 55+
- 25% of adults above 55 have had more than 4 weeks of knee pain, half of them had radiographic evidence of OA
Characteristic symptoms of OA
- pain is mechanical in nature - occurs with activity and is relieved with rest
- insiduous onset of pain
- morning stiffness absent or lasts
Other symptoms of OA
- limited function or disability
- joint swelling
- feeling of giving way
- reduced ROM
Physical examination of OA
- tenderness over joint line
- crepitus
- bony enlargement
- reduced ROM
- joint swelling/deformity
- instability/laxity of joint
Other types of arthritis that may involve hip, knee or hand
- RA
- Psoriatic arthritis
- otehr seronegative spondyloarthripathies
- crystal arthropathy
- sarcoidosis
Diseases that can predispose to OA
- metabolic diseases
- endocrine diseases
- hypermobility
- crystal arthropathy (gout)
- neuropathic joint
- chondrodysplasia
Other common causes of hip pain
- trochaneric bursitis
- iliopsoas tendonitis
- referred pain from lumbosacral spine
- avascular necrosis
- inguinal hernia
- hip fracture
Radiographic patterns of OA
1) patellofemoral: most common
2) medial tibiofemoral (50% cooccur with patellofemoral)
3) lateral tibiofemoral: less common
Other common causes of knee pain
- pes anserine bursitis
- ITT friction sundrome
- patella tendonitis
- PFPS
- prepatellar bursitis
- semimembranosous bursitis
HEberden’s and bouchard’s nodes
- most commonly affected by OA
- Heberden’s node: distal IP of third finfer
- Bouchard node: middle IP of second finger
- base of thumb also prevalent: squaring deformithy
Other common causes of hand pain
- De Quervain’s tenosynovitis
- Carpal tunnel syndrome
- flexor tenosynovitis
- Ulnar nerve compression
Lab test and OA
- non contributory as OA is a non-inflammatory arthritis
- aspiration if another diagnosis is feared
- synovial fluid in OA should be clear and viscous with a WCC
Role of radiography in OA
- confirm clinical suspicion and exclude other conditions
- can see osteophyte formation, joing space narrowing, subchondral sclerosis, sunchondral cyst
X ray of hand and wrist principles
- bone more than soft tissue
- centred on important part, close to film
- joint surgace in multiple projections
- often useful to include both hands to compare
- need good spatial detail
Osteoarthritis X ray changes - general changes
- cartilage loss
- non uniform joint space thinning
- subchondral bone sclerosis, cyst formation, intraarticular lose bodies
- reactive proliferative changes; sclerosis, osteophytes
- weakening: isntabilities, malalignment, capsular tears ganglia
- absence of erosive changes
OA specific changes on XRAY
- symmetrical
- DIP 2 and 3
- IP thumb
- MC thumb
- deformities: heberden, bouchard
Geodes
- subchondral cysts
- lucent space in subchondral bone formation
Ganglia and mucous cysts
- common at the back of the wrist
- localised collection of joint fluid
OA: aims of management
- patient education about both the disease and its management
- pain control
- improvement of function
- alteration of the disease process and its consequence: disease modification
Algorhythm for OA management
1) Non pharmacological management (education, exercise, weight loss, appropriate footwear)
2) physiotherapy, braces, simple analgesic
3) pharmacological management: NSAIDS, opioids
4) Surgery: osteotomy, total joint replacement
Concomitant morbidities
- 90% overweight/obese
- 60% have hypertension
- 20% have depression
- 20% have diabedeteied
Knee osteoarthritis
- prevention
- progression
- palliation
1) Prevention: obesity, joint injury
2) progression: reduce load, disease modification
3) palliation: analgesia, joint replacement
What is the most important intervention for OA
- weight loss
- those that lost 10% of their body weight improved by 50% in their symptoms
EWxercise
- generally ineffective at home because exercise trechnique not appropriate
- exercise leads to improvement in strength, proprioception, pain and function
- combination of strength training and aerobic conditioning - low impact exercises
ConclusionOA management
- adequate pain control still unmet need
- dichotomy between guidelines and clinical practice
- focus management on risk factors
- reduce compressive load
- recognize those at risk and encourage them to lose weight
OA epidemiology and prevention
1: 8 australians are affected by OA
2: 1 F:M
- disease of old age, but 2/3 are still in working age
Risk factors for OA
- Susceptible joint: injury, alignment, limp length inequality, structural abnormality, muscle eweakness…
- susceptible individual: obesity, age, gender, race, genetic predisposition, dietary
Surgical options for OA
- arthroscopic surgery
- chondrocyte implantation
- relaignment osteotomy
- joint replacement
Arthroscopic surgery
- no direct benefit for OA -> not indicated if symptoms are mostly related to OA
- possible role in significant displaced meniscus tears or early OA
Joint replacement
- commonly performed
- mostly for old patients
- for advanced OA clinically and radiologically
- failure of non operative treatment
- severe pain and disability
Total knee replcement especially for
- more than one compartment affected
- fixed deformity
- stiffness
- all joint surfaces replaces with metal and plastic components
- computer navigation
- postoperatively
Contraindications to joint replacement
- active infection
- knee: absent extensor mechanism
- hip: absent abductor mechanism
- medically unfit
Outcomes of joint replacement
- reduced pain
- increase activity level
- improved fitness and longevity
- improved quality of life
- not normal but not much improved
- hips surgery slightly more successful than knees
- approximately 5% revision surgery over 10 years
