Joint disease

INTRODUCTION

CLINICAL AND RADIOLOGICAL FINDINGS IN JOINT DISEASE

Condition	Site of involvement	Discriminatory findings
*Primary osteoarthritis (F>M > 45 years)*	Hands Large joints (e.g. hip, knee) Spine	PIP and DIP joint involvement (Heberden’s and Bouchard’s nodes) no osteopenia Joint space narrowing subchondral sclerosis subchondral cysts marginal osteophytes Degenerative disc disease spondylosis deformans apophyseal joint involvement spinal stenosis foraminal stenosis
*Erosive osteoarthritis (affects middle-aged females)*	Hands	PIP and DIP joint involvement joint ankylosis ‘gull-wing’ deformities (central erosions and marginal osteophytes)
*Rheumatoid arthritis (F>M Rh factor positive)*	Hand and wrist Large joints Spine	Symmetrical arthritis MCP and PIP joint involvement periarticular (early) and diffuse (late) osteopenia marginal erosions subluxation (swan neck and boutonnière deformities) periostitis is uncommon Joint space narrowing marginal erosions synovial cysts protrusio acetabulae Atlantoaxial subluxation
*Juvenile idiopathic arthritis (M = F affects children)*	Hands Large joints (e.g. knee) Cervical spine	Joint ankylosis florid periosteal reaction osteopenia Abnormalities of growth and maturation epiphyseal overgrowth and premature closure of the physis widened intercondylar notch Apophyseal joint fusion atlantoaxial subluxation
*Psoriatic arthritis (M>F nail changes HLA-B27 +ve)*	Upper extremities (e.g. hands and feet) SI joints Spine	‘Sausage’ digit DIP joint involvement terminal tuft erosion pencil-in-cup deformity joint ankylosis arthritis mutilans periosteal reaction no osteopenia Asymmetric or unilateral sacroiliitis Coarse syndesmophytes
*Reiter’s syndrome (affects young male adults)*	Lower extremities (e.g. foot) Spine SI joints	Hallux involvement periosteal reaction calcaneal erosions osteopenia not prominent Coarse syndesmophytes Asymmetric or unilateral sacroiliitis
*Ankylosing spondylitis (M>F affects young adults HLA-B27 +ve in 95%)*	SI joints Spine Pelvis	Bilateral symmetrical sacroiliitis ankylosis Anterior vertebral body squaring syndesmophytes paravertebral ossification bamboo spine ‘Whiskering’ of the iliac crests and ischial tuberosities
*Enteropathic arthropathies*	SI joints	Symmetrical sacroiliitis
*Gout (M>F)*	Hands and feet (especially the great toe)	MTP joint of the great toe juxta-articular erosions punched-out lesions with an overhanging margin no periarticular osteopenia tophi
*CPPD crystal deposition disease (M = F)*	Any peripheral joint predilection for the knee	Degenerative changes chondrocalcinosis paucity of subchondral sclerosis
*HA crystal deposition disease (M = F)*	Predilection for the shoulder (supraspinatus tendon)	Periarticular calcification
*Haemochromatosis (M>F)*	Hands	2^nd and 3^rd MCP joint involvement (‘squared’ metacarpal heads) joint space narrowing ‘hook-like’ osteophytes numerous subchondral cysts
*Alkaptonuria (ochronosis) (M = F)*	Intervertebral discs SI joints large joints	Degenerative changes: disc calcification joint space narrowing periarticular sclerosis
*Systemic lupus erythematosus (F>M affects young adults)*	Hands	Reversible MCP joint subluxation
*Scleroderma (F>M affects adults)*	Hands	IP joint arthritis acro-osteolysis soft tissue calcifications
*Mixed connective tissue disease (overlap syndrome)*	Hands	PIP joint, MCP joint, mid-carpal involvement soft tissue swelling, calcifications or atrophy
*Multicentric reticulohistiocytosis (F>M)*	Hands and feet	DIP joint and carpal involvement soft tissue swelling articular erosions no osteopenia
*Polymyositis / dermatomyositis*	Proximal extremities Hands	Soft tissue calcification DIP joint erosions
*Sarcoidosis*	Distal and middle phalanges of the hands and feet	Punched-out cyst-like lesions ‘lace-like’ appearance
*Haemophilic arthropathy (affecting males – but with female carriers)*	Predilection for large joints (e.g. knee)	Epiphyseal overgrowth juxta-articular osteopenia erosion and cartilage destruction widened intercondylar and trochlear notches squared patella
*Neuropathic arthropathy*	Any joint	5 ‘D’s’: normal bone Density joint Distension bony Debris joint Disorganization Dislocation
*Hypertrophic osteoarthropathy*	Tubular bones (radius and ulna > tibia and fibula)	Diaphyseal and metaphyseal painful periostitis

OSTEOARTHRITIS

DEFINITION

• This is the most common joint disorder – it is a balance between degenerative joint destruction (stressed bone) and repair (non-stressed bone)

• Primary OA: there is no underlying cause it occurs in the context of normal biomechanical forces

The joints most at risk: thumb base DIP joints acromioclavicular joints knees hips 1^st MTP joints spinal apophyseal joints

• Secondary OA: joints are damaged by previous disease

Causes: trauma systemic, metabolic or endocrine disorders (e.g. rheumatoid arthritis, ochronosis, haemochromatosis) crystal deposition disease neuropathic disorders congenital hip dislocation bone dysplasias

CLINICAL PRESENTATION

• Pain reduced movement joint crepitus (± effusion) early morning stiffness

RADIOLOGICAL FEATURES

PEARLS

Erosive OA

This characteristically affects middle-aged women destructive changes outstrip productive changes and can mimic an erosive arthritis (such as psoriatic arthropathy)

XR

Central erosions and marginal osteophytes (a ‘gull wing’ pattern) affecting the DIP joints

• Differential: psoriasis and rheumatoid arthritis – however these will have no 1^st CMC joint involvement and will have marginal (as opposed to central) erosions with no true osteophyte formation

Plain radiographic findings in primary osteoarthritis and corresponding underlying pathophysiological causes*

Radiological finding	Pathological cause
Localized joint space narrowing	Articular cartilage fibrillation, ulceration and erosion lead to changes in collagen and protein polysaccharide structure of cartilage. This results in reduced turgor
Subchondral bony sclerosis	Increased osteoblastic activity resulting in new bone formation and increased cellularity of the subchondral bone
Osteophyte formation (most commonly marginal)	Cartilage and bone proliferation and revascularization of remaining cartilage
Bone cysts and bone collapse	Subchondral micro-fractures and passage of synovial fluid under pressure through the damaged cartilage to excavate a subchondral cyst
Gross deformity with subluxation	Ligamentous laxity resulting from mechanical force applied after the distortion of capsular structures
Loose bodies	Fragments of bone and cartilage become separated and, if not resorbed, become loose in the joint. They may reattach to the membrane, become vascularized and undergo endochondral ossification
Fibrocartilage or hyaline cartilage calcification	This is usually due to calcium pyrophosphate deposition disease (CPPD). The reparative response is usually quite florid

HAEMOPHILIC AND NEUROPATHIC ARTHROPATHIES

HAEMOPHILIC ARTHROPATHY

DEFINITION

• There is recurrent bleeding into a joint due to a deficiency of blood clotting factors the repeated intra-articular bleeding leads to villous synovial hypertrophy with the accumulation of haemosiderin within macrophages

Classic haemophilia (haemophilia A): X-linked recessive factor VIII deficiency

Christmas disease (haemophilia B): X-linked recessive factor IX deficiency

CLINICAL PRESENTATION

• Painful and swollen joints joint deformities

• It is only expressed in males (females can be carriers)

RADIOLOGICAL FEATURES

Location

It particularly affects the knee, elbow, ankle and shoulder small peripheral joints are rarely involved

XR

Hyperaemia causes epiphyseal overgrowth and accelerated maturation in the immature skeleton there is neither uniform nor symmetrical joint involvement

• Acute: joint effusion and oedema

• Chronic: juxta-articular osteoporosis resulting from haemorrhage and periarticular hyperaemia increased radio-opacity of the periarticular soft tissues and synovium (due to haemosiderin deposition) articular erosion and cartilage destruction (due to a thickened synovium) secondary osteoarthritis (subchondral cysts are common)

Knee: a widened intercondylar notch a squared patella it demonstrates similar appearances to juvenile rheumatoid arthritis

Elbow: an enlarged radial head and trochlear notch

• 5 stages:

Stage I: soft tissue swelling (± joint effusion) normal joint surfaces

Stage II: stage I + periarticular osteoporosis epiphyseal overgrowth

Stage III: erosions, sclerosis and subchondral cysts the joint space is preserved

Stage IV: stage III + focal or diffuse joint space narrowing

Stage V: a stiff contracted joint with significant degenerative change

MRI

This can detect early synovial and cartilaginous changes it can differentiate between acute and chronic soft tissue bleeding

• T1WI/T2WI: a thickened and irregular synovium with fibrosis and haemosiderin deposition

Haemosiderin: this generates low SI foci, with a blooming artefact on gradient-echo (GE) sequences

PEARLS

• Septic arthritis is a rare complication of haemophilia

Intraosseous subperiosteal or soft tissue pseudotumours

These can develop following the encapsulation of episodes of repeated haemorrhage it occurs particularly within the femur and around the pelvis it presents as a painless expanding mass, with soft tissue and bone destruction

MRI

T1WI: a low SI thick fibrous capsule T2WI: central high SI (due to blood breakdown products)

NEUROPATHIC ARTHROPATHY (CHARCOT JOINT)

DEFINITION

• A destructive and productive articular abnormality following a loss of pain sensation and/or proprioception

CLINICAL PRESENTATION

• Painless joint deformity and destruction on a background of neurological disease

RADIOLOGICAL FEATURES

Location

The distribution helps determine the cause (see table)

Atrophic form

This occurs early and is more acute resorption of the ends of affected bones results in sharp pointed ends there is an absence of osteoporosis, sclerosis, fragmentation or soft tissue debris it may lead to joint dislocation

Hypertrophic form

This occurs later with a slow progression it begins with a joint effusion the joint spaces are initially widened but then narrowed there is marked bony sclerosis (and no osteoporosis) fragmentation of the articular surfaces results in bony debris, which may later fuse into a large dense and well-organized corticated bony mass (± fusion with the underlying bone or dissection into the muscle planes) there is periosteal new bone formation subluxation and dislocation preceeds total joint disorganization pathological fractures can occur

• 5 ‘D’s’: normal bone Density joint Distension bony Debris joint Disorganization Dislocation

PEARL

• Differential: the pseudoneuropathic form of CPPD

Conditions associated with neuropathic arthropathy*

Condition	Prevalence of arthropathy	Joints most commonly affected
Congenital insensitivity to pain	100%	Ankle, tarsal, knee, hip
Syringomyelia	20–50%	Shoulder, elbow, wrist, cervical spine
Neurosyphilis	5–10%	Knee, hip
Diabetes mellitus	1%	Midfoot, forefoot
Alcohol related	Rare	Foot