Approach to Joint Pain Flashcards
What are the 3 broad categories of joint disorders?
Disorders of cartilage
Disorders of the synovial membrane
Disorders of the synovial fluid
(Also important to consider disorders of surrounding structures)
Example of a disorder of cartilage
OA
Example of a disorder of synovial membrane
RA
Examples of disorders of synovial fluid
Gout
Septic arthritis
What are the 6 characteristics of mechanical joint pain?
Chronic pain (months to years) Slowly worsening Worse on movement Improved with rest Not much swelling Little stiffness (lasts <30 minutes)
What are the 6 characteristics of inflammatory joint pain?
Acute or subacute pain (days to weeks) May change quickly Better with movement Worse with rest Swelling may be prominent Stiffness prolonged (lasts hours, worse in morning or after prolonged immobility)
What are the 4 main findings of OA on XR?
Osteophytes
Reduced joint space
Sclerosis of subchondral bone
??
Is arthritis more common in males or females?
Females
What are the 3 most important investigations for joint disorders?
XRs
Blood tests for Abs, markers of inflammation, etc
Synovial fluid analysis
Give 2 examples of Abs involved in joint pathology
Rheumatoid factor (RA) Antinuclear Ab (SLE)
What kind of joint pathology can RA predispose to?
OA
Knee joint infection
What joint pathology never affects distal interphalangeal joints?
RA
What conditions may cause an increase in ESR and CRP?
RA
SLE
Gout
Pseudo-gout
When can OA develop?
As a result of primarily mechanical degeneration OR due to long-standing joint disease (e.g. RA)
What are some non-specific markers of joint pathology which can be assessed in a blood test?
Urate
Calcium
What is the most useful form of imaging for diagnosis of joint pathology?
Plain XR
MRI (>CT)
What is CT useful for in the context of musculoskeletal disorder?
Picking up suspected fractures not seen on XR
What is US useful for in the context of musculoskeletal disorder?
Joint effusions
What is the most common presentation of joint pathology in the setting of SLE?
Small joint inflammation that comes and goes
What type of joint pathology is classically symmetrical?
RA
What type of joint pathology is classically non-symmetrical and oligoarthritic?
Psoriatic arthritis
Distinguish between mono-, oligo- and polyarthritis
Mono: 1 affected joint
Oligo: 2-5
Poly: >5
Give an example of a joint pathology that affects axial joints
Ankylosing spondylitis
Pain in the upper lateral thigh is suggestive of what conditions?
Gluteal tendonopathy
Intertrochanteric bursitis
What does “clicking” and “locking” of the knee usually indicate?
Meniscal damage
What does “giving way” of the knee usually indicate?
Ligamentous injury
What does a full joint examination in the lower limb involve?
Posture (looking for varus or valgus deformity) Gait Muscle atrophy Scarring Erythema, warmth Joint effusion Active and passive movement of the joint Examination of joints above and below Full back examination
If active movement of a joint is more limited than passive, what does this suggest?
Problem with surrounding structures, not the joint itself (a problem with the joint cannot be overcome with passive movement)
What is the most sensitive part of the hip examination?
Internal rotation (if this can be done without bother there is probably no true hip pathology)
What are some common findings on examination in the setting of OA of the knee?
Quadriceps (especially vastus medialis) atrophy on the affected side
Genu varus of affected side
Tender joint line +/- joint effusion
Limited ROM
What is important to note about the relationship between XR findings and the symptoms of OA? What is the clinical relevance of this?
XR findings do not necessarily correlate with pain and functional limitation
When deciding which joint to replace, the decision should be made based on the pt’s level of pain and discomfort (not the imaging)
What is the main predisposing factor for pseudogout?
Age
List some predisposing factors for knee joint infection
Penetrating injury Surgery/prosthesis Systemic sepsis Immunosuppression Damaged joint (e.g. in the setting of RA)
List some predisposing factors for gout
Age
European ancestry
Alcohol
Thiazide diuretics
Anything causing high metabolic turnover (e.g. post-surgery, psoriasis)
CKD (due to impaired uric acid excretion)
What is another name for pseudogout?
Calcium pyrophosphate disease (CPPD)
What is the relationship between PTH levels and pseudogout?
Pseudogout may be precipitated by hypercalcaemia
Hypercalcaemia can be caused by elevated PTH
What is the differential diagnosis for a presentation of acute joint pain and swelling?
Knee joint infection
Gout/pseudogout
Haemarthrosis
Inflammatory arthritis
List 3 predisposing factors for haemarthrosis
Trauma
Blood-thinning medications
Some rare tumours
What diagnosis should not be missed in the setting of acute onset joint pain?
Septic arthritis (this is a medical emergency)
When is joint aspiration contraindicated?
With a prosthetic joint
What synovial fluid WCC would be expected in the setting of inflammatory arthritis?
> 50,000 cells/mL
What WCC would be suggestive of septic arthritis?
Elevated where 75-80% were neutrophils
How can gout be diagnosed?
Negatively birefringent crystals on polarising light microscopy of the joint aspirate
What are some features of SLE?
Fever Alopecia Raynaud's syndrome Mouth ulcers Secondary Sjrogen's syndrome Photosensitivity
What is Raynaud’s syndrome?
Excessively reduced blood flow in response to cold or emotional stress, causing discolouration of the fingers, toes, and occasionally other areas
What is Sjogren’s syndrome?
AI disease causing dryness of the eyes and mouth
What joint pathology can result following diarrhoeal illness?
Reactive arthritis
What joints tend to be affected by seronegative arthritis?
Larger joints
What is the relationship between smoking and RA?
Causative factor
Impacts treatment
Associated with poorer prognosis
What does soft tissue swelling indicate?
Synovitis
Why is it important to perform a CXR in someone diagnosed with RA who has respiratory symptoms?
Methotrexate can cause pulmonary fibrosis; important to assess respiratory function before commencing
Which is the more specific test for RA: RF or CCP Abs?
CCP Abs (90%)
Which is the more sensitive test for RA: RF or CCP Abs?
Equally sensitive (70%)
What are the ACR 1987 classification criteria for RA?
Patients must have 4 of 7: Morning stiffness >1 hour* Swelling in ≥3 joints* Swelling in hand joints* Symmetric joint swelling* Erosions or decalcification on XR Rheumatoid nodules Abnormal serum RF *Must be present ≥6 weeks
What have the ACR criteria for RA largely been replaced by diagnostically?
CCP
What is gonococcal arthritis?
Form of septic arthritis caused by disseminated gonoccocal infection
