📖 Rheumatology Orthopaedics
& Pathophysiology
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This study guide covers all conditions from the Rheumatology textbook, organised into Rheumatology & Orthopaedics (pages 1–32), Pathophysiology (pages 33–56), and Letter Writing (pages 69–96). Each condition includes: definition, epidemiology, aetiology, pathology, symptoms, signs, investigations, treatment, prognosis, and exam tips. Use the sidebar to navigate, take the quiz to test yourself, and use search to find any term instantly.
🏛️ Rheumatology Study Resource
Exam revision companion for osteopathic students.
📑 Table of Contents
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🦴 Rheumatology & Orthopaedics
🦴 Arthritis & Osteoarthritis
| Def | Degenerative joint disease — progressive "wearing out" of articular cartilage |
| Incidence | Common — present to some degree in every elderly person |
| Age | Increases with age. Secondary OA can develop at any age |
| Sex | F > M |
| Genetics | Primary OA has genetic link; family history is a strong risk factor |
| Aetiology | Primary OA: No apparent cause, family history. Affects large joints (knee, elbow) + IP joints. Secondary OA: Uneven load bearing from trauma, malalignment, unequal leg lengths, occupational wear |
| Symptoms | Pain worsened by use, eased by rest. Stiffness. Functional impairment. |
| Signs | Swelling, muscle wasting, tenderness, reduced movement, crepitus, deformity. Heberden's nodes at DIPJ · Bouchard's nodes at PIPJ Common sites: hips, knees, spine, 1st MTPJ, PIPJ, DIPJ |
| X-ray | Reduced joint space · Osteophytes · Periarticular sclerosis · Subchondral cysts · Irregular margins |
| Treatment | Education · NSAIDs & analgesics · OT & appliances · Physiotherapy/mobilisation · Steroid injections · Joint replacement, osteotomy, fusion · Treat exacerbating factors |
| Prognosis | Progressive but symptoms can be relieved — quality of life improved by maintaining mobility |
| Level | Nerve Root | Power Loss | Movement Weak | Reflex ↓ | Sensory Loss |
|---|---|---|---|---|---|
| L3/L4 | L4 | Tibialis Anterior | Ankle Inversion | Knee | Medial foot & leg |
| L4/L5 | L5 | Extensor Hallucis Longus | Big toe dorsiflexion | None | Dorsum of foot |
| L5/S1 | S1 | Peroneus Longus & Brevis | Ankle dorsiflexion & eversion | Ankle | Lateral foot |
| Conservative | Education · NSAIDs & analgesics · OT & appliances · Physiotherapy & mobilisation |
| Injections | Steroid injections into affected joints |
| Surgical | Joint replacement (hip/knee) · Osteotomy · Fusion (arthrodesis) |
| Other | Treat exacerbating factors (obesity, alignment, leg length discrepancy) |
🔥 Rheumatoid Arthritis — The Full Picture
| Def | Progressive chronic inflammatory disorder of unknown aetiology — primarily affects synovium, but can affect many tissues |
| Prevalence | 1% of population |
| Age | Peak 35–55 |
| Sex | F > M |
| Genetics | HLA DR4 & DR3 linked |
| Theory 1 | Hormonal: Symptoms reduced in pregnancy |
| Theory 2 | Infective: Reaction to viral infection |
| Theory 3 | Genetic: HLA links as above |
| Theory 4 | Immunological: Possibly in reaction to infective agent. Evidence: rheumatoid factor in blood/synovium correlates with severity; synovial membranes show immunological mediated damage |
RA synovial fluid contains immune complexes + WBCs → reduce Tsuppressor activity, increase macrophage activity. Tissue damage is via inflammatory response.
| Early | Blood vessels dilate + thrombase · Synovium swells & thickens (hyperplasia) · WBCs infiltrate → inflammation, oedema, fibrosis |
| Later | Articular cartilage invaded by synovium (Pannus formation) · Cartilage destroyed by proteolytic enzymes · Pain + swelling from prostaglandins & lymphokines · Immunoglobulins produced |
| Severe | Intra-articular pressure ↑ · Ligaments weaken & become lax · Capsule weakens · Joint subluxes due to abnormal muscle/tendon pull · Eroded bone + malalignment + fibrosis + destruction |
| Joint pattern | Polyarticular · Symmetrical · Small joints of hands & feet primarily · PIPJ, DIPJ, MTPJ, wrist in 80% |
| Onset | Insidious in most cases |
Hand Deformities:
- MCP subluxation
- Ulnar deviation (especially at MCPJ)
- Swan neck deformity
- Z deformity of thumb
- Extensor tendon rupture
- Ulnar styloid prominence
Foot Deformities:
- MTPJ subluxation with callus formation
- Prominent metatarsal heads ("walking on marbles")
- Hallux valgus
- Valgus mid-foot deformity
Symptoms:
- Pain, tenderness & swelling of joints
- Functional impairment
- Constitutional symptoms (fatigue, fever, malaise)
- Carpal tunnel syndrome — 50% of patients
- Stiffness after inactivity, especially mornings — at least 20–30 mins
Signs:
Early: Swelling, effusion, tenderness, reduced movement, warmth, muscle wasting, oedema
Late: Symmetrical joint involvement, deformity, swelling, wasting, extra-articular manifestations
Investigations:
- Rheumatoid factor latex agglutination test (80% positive)
- FBC — anaemia + raised WBCs
- ESR raised in inflammation
- Synovial fluid shows WBCs
- Biopsy — characteristic histology
- Arthroscopy & arthrograms
X-ray Changes:
Early: Soft tissue swelling · Periarticular osteoporosis · Marginal bone erosions
Late: REDUCED joint space · Erosive changes & bone destruction · Subluxed/dislocated joints · Ankylosis · Secondary degeneration
| Medications | NSAIDs · Disease-modifying drugs (Gold, Penicillamine) · Immunosuppressants (Azathioprine) · Steroids |
| Physical | Education · Physical therapies · OT & special appliances |
| Injections | Steroid injections into affected joints |
| Surgery | Joint replacements · Synovectomy · Plastic surgery |
Prognosis — Worse if:
- Insidious onset
- Young patient
- Rheumatoid factor positive
- Early erosions
- Marked systemic disease
3 Disease Patterns:
- Persistent (75%): If lasts >3 years, remission is rare
- Intermittent (25%): Episodes 6–12 months with remissions months to years
- Monoarticular: Progresses to polyarticular within 10 years in 40%
50% have little disability · 40% moderate to severe · 10% severe. Some die directly from disease.
🦋 Systemic Lupus Erythematosus (SLE)
| Def | Multisystem disorder with widespread organ involvement |
| Incidence | Common — one of major causes of inflammatory arthritis |
| Age | Peak early 20s, onset 10–35 |
| Sex | F:M = 9:1 |
| Genetics | HLA A1, B8, DR3, C4. Familial tendency |
Aetiology Theories:
- Hormonal: Women more affected; worse in pregnancy & before menstruation
- Genetic: Familial tendency, twin studies show increased risk
- Infective: Acute stage resembles viral illness (fever, lymphadenopathy)
- UV light: Disease flares up in UV exposure
- Drugs: Some drugs can cause similar reaction
- Immunological: Major role — Tsuppressor cells impaired, B cells produce more antibodies, direct immune damage to RBCs, indirect damage via immune complexes (e.g. kidney)
- Fibrinoid necrosis — mostly in small blood vessels, surrounded by inflammation (vasculitis)
- Haematoxylin bodies — altered DNA
- Immune complex deposition — Type 3 reaction in kidney & skin especially
| Organ System | % | Manifestation |
|---|---|---|
| Musculo-articular | 95% | Arthralgia, myositis, avascular necrosis (steroid-induced) |
| Cutaneous (skin) | 81% | Butterfly rash on face |
| Fever | 77% | Swinging pyrexia |
| Neuro (CNS) | 59% | Infarcts & thrombosis |
| Renal (kidneys) | 53% | Glomerulonephritis — leading cause of death |
| Pulmonary (lungs) | 48% | Pleural effusion, infections |
| Cardiac (heart) | 38% | Pericarditis, endocarditis |
| NSAIDs | For joint symptoms |
| Hydroxychloroquin | Antimalarial — disease-modifying for SLE |
| Steroids | For acute flares & organ involvement |
| Immunosuppressives | For severe/refractory disease |
| Plasmapheresis | In severe cases |
Prognosis: 10-year survival now >90%. Death occurs from renal disease & vasculitis. Some patients have only one severe flare then are virtually symptom-free forever.
🦴 Seronegative Arthropathies
Group of inflammatory arthritides with similar histology to RA but Rheumatoid Factor ABSENT. Includes: Ankylosing Spondylitis, Reiter's Syndrome, Psoriatic Arthritis, Enteropathic Arthritis, Juvenile Chronic Arthritis.
| Def | Chronic inflammatory arthritis principally affecting the axial skeleton |
| Incidence | 0.5–2% of Caucasians. Incomplete forms more common |
| Age | 20–40, peak at 17–25 |
| Sex | M > F 5:1 |
| Genetics | HLA B27 in >90% of cases. 7% of 1° relatives affected |
| Aetiology | Genetic (HLA B27) + environmental (Klebsiella bacteria in gut linked in some studies) |
Pathology — 2 Processes:
- Synovitis: Identical to RA
- Enthesopathy: Inflammatory reaction at ligamentous attachment → calcification
Sites: Sacroiliac joints, spinal apophyseal, costovertebral. Enthesopathy at annulus fibrosus insertion → syndesmophytes (bony bridges) → bamboo spine. Symphysis pubis & manubriosternal joints also involved. Peripheral joints may show synovitis with rapid ankylosis.
Extra-articular: Iritis (25%), cardiac (2–8% — arrhythmia/valve disease), pulmonary fibrosis, cauda equina lesions. Complications: Spinal fractures, amyloidosis, reduced vital capacity.
Symptoms:
Low back pain (thoraco-lumbar junction), radiates to buttocks, at night. Not relieved by rest, relieved by moderate activity. Stiffness & poor posture.
Signs:
- Loss of lumbar lordosis
- SI tenderness
- Restricted movement in all 3 planes
- Later: Kyphosis + rigidity
- Chest expansion <5cm at 4th intercostal space
- Schober's test — reduced lumbar flexion
- Tragus test — distance from earlobe to wall increases as posture deteriorates
Investigations & Treatment:
X-ray: SI sclerosis → ankylosis → bamboo spine. ESR raised. RF ABSENT.
Tx: Indomethacin (NSAIDs) · Sulphasalazine (peripheral) · Physiotherapy · Exercises · Surgery for positioning. Radiotherapy as last resort.
Prognosis: Wide range. Many get severe kyphosis. Hip involvement = poor prognosis.
| Triad | 1. Non-specific urethritis · 2. Conjunctivitis · 3. Arthritis |
| Type | Reactive arthritis |
| Age | Peak 16–35 |
| Sex | Venereal M:F 20:1 · Post-dysenteric 10:1 · Childhood 5:1 |
| Genetics | HLA B27 in 60–80% |
| Triggers | Sexually acquired urethritis (Chlamydia, Ureaplasma) OR Enteric infections (Shigella, Yersinia, Salmonella) |
| Pathology | Synovitis with lymphocyte & leukocyte infiltration (like RA). Periostitis on sole of foot. Sacroiliitis & spondylitis. |
| Joints | Asymmetrical, mainly lower limb. Sausage digits (swollen toes). Achilles tendonitis & plantar fasciitis. |
Prognosis: Exacerbations 2–4 months with remissions up to years. 50% have recurrences. 30% permanent disability (usually feet). 20–40% go on to sacroiliitis, 20% develop full AS.
Uncommon. Characterised by:
- Oral & genital ulcers
- Uveitis
- Skin lesions
- Vascular lesions including thrombophlebitis
- Arthritis
- CNS or gut involvement
🦴 Osteoporosis, Osteomyelitis & More
| Def | Reduced bone mass per unit volume vs normal for age, sex & race. No change in bone volume! |
| Age | Mostly women >60, men >70 |
| Sex | F > M |
3 Types:
- Primary: Ageing + post-menopause
- Secondary: Endocrine (Cushing's), chronic disease (alcoholism, malabsorption), malignancy, myeloma, RA, steroids, heparin, immobilisation
- Juvenile: Spine & long bone ends. Self-limiting.
Key Physiology:
Oestrogen stimulates osteoblasts & reduces osteoclasts. Weight-bearing also stimulates bone laying. Bone mass peaks at 35–49 (some say late 20s). After menopause: 5% loss/year for 5 years, then 1%/year. Early menopause = higher risk.
3 Main Fractures:
- Fractured Neck of Femur — 10–20% mortality at 3 years (treated), untreated few survive a year
- Vertebral fracture — Crush/wedge → loss of height + kyphosis. Often first sign is painless thoracic kyphosis
- Colles' fracture of wrist — Fall on outstretched arm → "dinner fork deformity" (radial dorsal angulation, impaction, radial deviation)
X-ray:
Reduced bone density — >30% of bone must be lost before visible on X-ray
Treatment:
- Prevention is key: Exercise (jumping!), Vitamin D + Calcium
- HRT — delays post-menopause 5% loss until stopped
- Bisphosphonates (e.g. Etridonate) — increase bone mass
- Calcitonin injections · Prophylactic Etridonate with steroids · Surgery
Prognosis: Once a fracture occurs, another is likely. Directly or indirectly, osteoporosis is life-threatening.
Bone infection — usually chronic except immediately post-op or post-trauma. Can be due to haematogenous spread.
| Presentation | Pain, redness, discharging sinus (to outside). Systemic unwell. |
| Pathology | Cavities within bone (involucrum) + dead bone pieces (sequestra) act as infection focus |
| X-ray | Involucrum + sequestra visible |
| Treatment | Conservative — antibiotics. Surgery to remove sequestra if needed |
NB: Bone abscess = small abscess at end of long bone. May lie dormant for years.
💥 Spine: Disc, Stenosis, Scoliosis & More
Disc herniation is a common cause of back pain & sciatica. Often precipitated by injury on a background of age-related degeneration. Common sites: L5/S1 and L4/L5.
Mechanism:
Rent in annulus fibrosus → nucleus protrudes → impinges nerve root (postero-lateral) or cauda equina/spinal cord (posterior). Small bulge → stretches longitudinal ligament → back pain. Larger → pressure on nerve root → sciatica. Severe → extrusion into canal → loose fragment (sequestration). Healing by shrinkage & fibrosis.
Clinical Picture:
Sudden severe back pain → dies down over days → sciatic pain in buttock, down back of leg to foot. May have sciatic scoliosis. Restricted forward flexion. SLR positive.
Treatment:
Conservative (most cases): Analgesia, gentle mobilisation, physiotherapy/osteopathy. Surgery (rarely warranted): decompression, laminectomy, fusion — variable success. Chemonucleolysis in some centres.
Diagnosis:
- Bladder or bowel loss of control (incontinence or retention)
- Loss of saddle sensation (perineum)
- Loss of anal tone
Action: Patient needs to go to Casualty IMMEDIATELY for urgent spinal decompression and/or laminectomy.
Scoliosis = lateral angulation >5°. Can be accompanied by vertebral rotation.
Idiopathic Structural Scoliosis (3 subgroups):
- Infantile (0–3 yrs): Left curve, M>F. Two types — resolving & progressive. Most resolve. Brace/fusion if needed.
- Juvenile (4–9 yrs): Before 6 M>F, after 6 F>M. Mostly thoracic right curves. Most progressive.
- Adolescent (puberty): Thoracic curve to right with rotation. Surgery for curves >40°.
Secondary Structural Scoliosis:
Congenital (hemivertebra, OI, Marfan's), Polio, Neurofibromatosis
Other Types:
- Compensatory: Lumbar, compensates for pelvic tilt (short limb, hip deformity)
- Postural: Adolescent girls, mild left curve, resolves on bending. Spontaneous recovery
- Sciatic: Temporary, muscle pull protecting spine (e.g. disc prolapse)
| Spondylolysis | Neural arch defect in L5 (or L4) — loss of bone between facets, replaced by fibrous tissue. Congenital or post-trauma. Usually asymptomatic. Makes spondylolisthesis more likely. Treatment: surgical. |
| Spondylosis | Disc degeneration → no disc space reduction + facet joint displacement. Recurrent backache, hard work/sitting aggravates, lying relieves. Pain referred to buttocks/greater trochanter. Acute locking/giving way. |
| Spondylolisthesis | Spontaneous forward displacement of lumbar vertebra upon vertebra below. Causes: congenital, spondylolysis, OA of facet joints. Usually L4/L5 or L5/S1. Mostly symptom-free. |
| Spinal Stenosis | Congenital narrow spinal canal → pain in gluteal region & lower limb on standing/walking. Nerves & vessels compressed in narrow canal after minor disc prolapse or osteophytes. More common in middle-aged men. |
| Scheuermann's Disease | Cause of kyphosis. Intrusion of IV disc into vertebral end plate at multiple levels in thoracic spine. 13–16 year olds. Active stage → pain. |
🔌 Nerve Injuries & Cervical Conditions
Caused by severe traction with arm in abduction (motorcycle accident, forceps delivery, shoulder dislocation, stab/gunshot). Tethering from fibrosis adds to symptoms later.
Differentiating Brachial Plexus vs Nerve Root:
| Brachial Plexus | Nerve Root |
|---|---|
| ↑ by side bend away from affected side | ↑ by side bend toward affected side |
| Unaffected by compression/distraction | ↑ by compression, ↓ by distraction |
Differentiate from shoulder pain: shoulder pain only extends to elbow; brachial plexus extends to hand.
Severe Injuries — 3 Categories:
- Erb's Palsy (C5, C6): Shoulder abductors & external rotators paralysed → arm hangs close to body, inwardly rotated — "Waiter's Tip"
- Klumpke's Palsy (C8, T1): Intrinsic hand muscles paralysed → claw hand + ulnar sensory loss
- Entire plexus: Whole arm paralysed & numb
Axillary Nerve Palsy:
Injured by shoulder dislocation or fractured humeral neck. Supplies deltoid → abduction weak at shoulder + "regimental badge" numbness over lower deltoid.
| Cervical Spondylosis | Most common C-spine disorder. Degeneration & flattening of IV discs + bone spurs at vertebral margins → encroach on nerve foramina. Middle-old age. Neck pain & stiffness, worse on rising, may radiate to scapulae & occiput. X-ray: disc space narrowing + spurs. Later facet joints involved. Differentiate from cervical rib, carpal tunnel, cervical tumours. Tx: heat + massage + maintain mobility. |
| The Rheumatoid Neck | 30–40% of RA patients. 1) Erosion of atlanto-axial joints & transverse ligaments. 2) Erosion of atlanto-occipital articulation → odontoid rises into foramen magnum (danger of peg fracture). 3) Mid-cervical facet erosion. |
| Acute Brachial Neuritis | Neuralgic amyotrophy — thought to be viral. Severe shoulder pain from nerve root infection → may extend to hand. Wasting of deltoid & hand. Tx: Pain control. Recovery months to years. |
| Cervical Spondylolisthesis | Rare. Anterior displacement from: 1) Congenital failure of odontoid fusion. 2) Inflammatory pathology in transverse ligament of Axis. 3) Previous RA instability. |
| Cervical Rib | Congenital over-development of C7 transverse process (bony or fibrous). Can be asymptomatic or cause neurovascular complications. Diagnosis: Adson's test + X-ray. Also positive in Thoracic Outlet Syndrome / Scalenus Syndrome. |
🩻 Other Orthopaedic Conditions
"Simple back pain" — backache with no discernible pathology. Failure of spinal muscles to protect ligaments from overstretching. Associated with obesity, poor fitness, chronic illness. More common in females. Diagnosis of exclusion — all investigations normal. Chronic course regardless of treatment. Osteopathic treatment far better than most.
Pain in coccyx region. Usually chronic, after fall → strain at sacro-coccygeal joint or fracture. Pain when sitting, disappears on standing. Localised tenderness. Self-limiting — treatment usually not needed. Rare: excision or manipulation.
Congenital malformation — failure of folding of neural tube in developing embryo. 4 grades:
- Spina bifida occulta: Failure of fusion of vertebral arch. Most common. Usually asymptomatic. Faun's beard in some. Symptoms from dural tethering.
- Meningocele: Meninges expand beyond vertebrae
- Myelomeningocoele: Meninges + cauda equina expand beyond
- Rachischisis: Complete failure of fusion — opening posteriorly
Frequency decreases with severity — mainly due to antenatal screening & folic acid in pregnancy. Varying motor/sensory loss in lower limbs for aperta types.
🧬 Pathophysiology: Cancers
| Oesophageal | Gastric | |
|---|---|---|
| Incidence | Very rare | Rare |
| Age | Increases with age. 65+ main risk | Increases with age |
| Sex | F > M slightly (men >3x in US) | M > F |
| Geography | Highest Africa & USSR | Highest Japan |
| Aetiology | Hot foods, smoking, heavy drinking (>3/day), obesity, acid reflux, Barrett's oesophagus | H. pylori infection (main cause), diet, blood group A, chronic gastritis, polyps >2cm |
| Pathology | Polyp and/or wall invasion. Local spread. Adenocarcinoma (lower, US most common) vs Squamous cell (upper, worldwide most common) | 95% adenocarcinoma. Invades locally through stomach wall → early lymphatic spread. Late symptoms |
| Symptoms | Dysphagia, food stuck, pain on swallowing, chest/back pain, weight loss, hoarse voice/cough | Early satiety, vague abdominal pain (mimics PUD), weight loss, anaemia, haematemesis, melena |
| Treatment | Usually palliative. Radiotherapy, dilation ± stents. Surgery (mortality ~50%) | Usually palliative. Surgery ineffective for cure |
| Prognosis | 5% cure | 10% cure — spreads early, <15% survive >5 years |
| Def | Carcinoma of the colon/rectum. Most common GI cancer |
| Incidence | Common |
| Aetiology | Western diet, carcinogens + increased gut transit time (low fibre) → malignant change. Most are adenocarcinomas forming polyps → malignant transformation → invade wall → lymphatics → liver |
| Location | 80% within 30cm of anus |
Dukes Staging System — 5-Year Survival:
| Stage | Description | 5-Year Survival |
|---|---|---|
| Dukes A | Invasive no deeper than muscularis layer | 98% |
| Dukes B | Below muscularis but not through gut wall | 80% |
| Dukes C | Invaded through wall | 40% |
| Dukes D | Distant metastases | 5% |
Symptoms: Bleeding PR, mucous, tenesmus, dissatisfaction passing stool, weight loss, cachexia
Signs: Often none. Mass may be felt PR
Treatment: Surgery ± chemotherapy
| Incidence | One of commonest cancers (19% of all cancers) |
| Age | Increases with age |
| Sex | M > F (changing) |
| Aetiology | Smoking, asbestos, iron oxides → chronic inflammation → increased cell turnover → DNA damage → mutation in cell division regulation → cancer |
| Pathology | Tumour in large airways. Most common: Squamous cell carcinoma from bronchi. Mesothelioma from asbestos. Spread: local → metastases (brain, bone, liver, adrenals) |
Symptoms by Site:
- Tumour: Haemoptysis, cough, SOB, chest pain
- Local spread: SOB, hoarse voice (recurrent laryngeal n.), chest pain (pericarditis/rib mets), SVC obstruction, nerve palsies
- Metastases: Brain, bone, liver, adrenal symptoms
- Constitutional: Weight loss, fatigue. Endocrine effects e.g. SIADH
Signs: SOB, stridor, cyanosis, clubbing, nicotine stains, mediastinal shift, Horner's, SVC obstruction
Treatment: Surgery if small + no mets. Otherwise palliative radiotherapy/chemo.
Prognosis: Very poor.
| Type | Key Features |
|---|---|
| Ovarian | Women >50, often presents late. Multiple types. Usually asymptomatic except abdominal distension & ascites. Has often metastasised by presentation → poor prognosis. |
| Endometrial | Women 40–60. Post-menopausal bleeding or abnormal bleeding. Uncommon but early detection allows treatment. Spread: pelvic organs → liver. Unopposed oestrogen post-menopause is important cause. |
| Cervical | Young women. Uncommon. Risk factors: unprotected sex with multiple partners. Caused by HPV. Detected by cervical smears (CIN). Treatment: radical surgery + chemotherapy. |
| Incidence | ~1 in 35 women. 99% are women, 1% men |
| Age | More common with age |
| Aetiology | Unknown. Most common is invasive carcinoma (usually one breast; lobular form is bilateral) |
| Pathology | Develops in one breast. Spreads EARLY via lymphatics to axillary nodes and beyond |
| Symptoms | Breast lump, occasionally nipple discharge, blood, skin changes |
| Treatment | Elderly: Tamoxifen (oestrogen-dependent). Younger (= more aggressive): Lumpectomy/mastectomy + axillary node dissection ± adjuvant chemo |
| Prognosis | Elderly: often slow. Younger: can recur 10 years after treatment. Only 25–30% actually die of cancer. Many are young. |
🫁 Respiratory Pathophysiology
| Def | Reversible airways disease, often with inflammatory component |
| Incidence | Common — up to 20% of population |
| Age | Most common in children; second peak 50–60 |
| Sex | M = F |
Two Types:
- Extrinsic: Type 1 hypersensitivity (e.g. house dust mite). IgE on mast cells → allergen activates → histamine, bradykinin release → bronchoconstriction in large airways + mucosal inflammation
- Intrinsic: Hyper-reactive airways (e.g. winter asthma). Bronchoconstriction ± inflammation. May be due to beta blockers
Clinical:
Symptoms: SOB, chest tightness, nocturnal cough ± waking, wheeze
Signs: Tachypnoea, peripheral cyanosis, audible wheeze, use of accessory muscles, barrel chest
Investigations: Allergen testing, reversibility studies with bronchodilators
Treatment: β2 agonists (e.g. salbutamol) for smooth muscle relaxation. Inhaled steroids for inflammatory component
Prognosis: Childhood asthma — many grow out of it, may recur later. Maturity-onset tends to remain.
COPD = Emphysema + Chronic Bronchitis. Common. Elderly. M=F. More in Western societies.
Definitions:
- Emphysema: Permanent increase in alveolar air spaces due to destructive changes
- Chronic Bronchitis: Repeated sputum production on most days in 3 consecutive months over 2 years
Aetiology:
- Emphysema: Alveolar walls destroyed by smoking → chronic irritation + inflammation. α1-antitrypsin deficiency → unopposed proteolysis → severe early emphysema
- Chronic Bronchitis: Smoking destroys microvilli → retention of secretions → bacteria thrive → repeated infections → more lung damage
Key Pathology & Types:
| Pink Puffers (Emphysema dominant) | Blue Bloaters (Bronchitis dominant) | |
|---|---|---|
| Pathology | Alveoli destroyed → large air sacs (bullae) → ↓ surface area. Lung volume ↑ but vital capacity ↓. Elastic tissue destroyed → difficult to ventilate. | Chronic inflammation → ↑ secretions + ↓ clearance. Repeated infections. |
| CO₂ | Initially normal/low (puffing to keep CO₂ down) | CO₂ creeps up → loss of respiratory drive → cyanosis → respiratory failure |
| Appearance | Pink, thin, use accessory muscles | Blue (cyanosed), oedematous |
X-ray: Hyperexpanded "black" lungs ± signs of infection. LFTs: Reduced vital capacity, increased total lung volume.
Treatment: Bronchodilator + steroid inhalers · Antibiotics for exacerbations · Oral steroids · Nebulisers · Oxygen for respiratory failure.
Prognosis: It gets worse! Deterioration reduced by stopping smoking but destroyed lung can never be repaired.
Pneumonia
| Def | Lung infection → acute inflammation of alveolar tissue |
| Types | Bronchopneumonia: Spreading throughout lung. Risk of death → fibrosis on resolution. Lobar pneumonia: Confined to 1–2 lobes. Usually S. pneumoniae. Younger patients. |
| Aetiology | Bacterial infection in immunosuppressed host (elderly, infant, chronic disease, viral infection) |
| Symptoms | Temperature, SOB, productive cough, general unwell |
| Signs | ↑ RR + pyrexia, confusion, cyanosis, accessory muscles, asymmetrical chest expansion, dullness to percussion, ↑ breath sounds ± crackles |
| X-ray | Consolidation |
| Tx | Antibiotics |
| Prognosis | Often terminal for elderly/COPD → septicaemia. Younger: some permanent damage but usually no functional impact. |
Pulmonary Embolism
| Def | Clot from elsewhere lodged in pulmonary vasculature |
| Risk factors | Virchow's Triad: 1) Stasis (long flight, post-op, pregnancy) · 2) Vessel damage (surgery, orthopaedic) · 3) Hypercoagulability (familial, post-op, pregnancy, antithrombin 3 deficiency) |
| Small clot | Part of lung not perfused → eventually dies. Rest of lung works harder → ↑ RR + ↑ HR + cyanosis |
| Large clot | Blocks pulmonary trunk/major vessel → inadequate perfusion → right heart strain + ↓ O₂ + ↓ flow to left heart → coronary ischaemia → cardiac arrest |
| V/Q scan | Areas ventilated but NOT perfused |
| Tx | Warfarin |
| Prognosis | Always increased risk of recurrence |
🧠 Neurological Conditions
| Def | Acute episodes of neurological deficit from demyelination — sporadic in time & place, spontaneous but partial remission |
| Prevalence | 50–80/100,000 |
| Age | Young adulthood |
| Sex | F > M 3:2 |
| Genetics | Increased incidence in families |
| Aetiology | Unknown. Theories: slow virus (like CJD), genetic factor |
| Pathology | CNS white matter demyelinated in patches with inflammation. Spontaneous recovery occurs slowly. Demyelinated nerves conduct more slowly → severe functional impairment |
| Common 1st site | Optic nerve → sudden vision loss |
| Other sites | Brainstem, cerebellar peduncles, motor tracts — any part of brain |
Symptoms & Signs:
- UMN motor deficit (paraparesis, hemiparesis, monoparesis)
- Retrobulbar neuritis — vision loss
- Sensory deficit · Cerebellar signs · Diplopia (internuclear ophthalmoplegia)
- Vertigo · Urinary incontinence · Frontal lobe lesions · Dementia
NB. IQ & language skills often unaffected until late.
Diagnosis: 2 episodes distinct in time AND site. MRI, LP, VEP
Treatment: Steroids (acute) · Psychological support · Beta Interferon "Avonex, Betaferon" (neurologist-prescribed, ~£50,000/year)
Prognosis: Average duration 20 years. 80% have progressive disability. 5% die in 5 years. May have 30-year latent period after first attack of retrobulbar neuritis.
| Def | Progressive degeneration of: Anterior Horn Cells (spinal cord) · Lower Cranial Motor Nerves · Neurones of Motor Cortex |
| Incidence | 1.5/100,000 (rare) |
| Age | 50–70 |
| Sex | M > F 1.5:1 |
3 Forms:
- Progressive Muscle Atrophy: LMN weakness — wasting, reduced tone, fasciculation, absent reflexes. Starts in hands → limbs
- Progressive Bulbar Palsy: LMN of lower cranial motor nuclei → fasciculation & wasting of tongue, absent swallow
- Amyotrophic Lateral Sclerosis (ALS): UMN — spastic weakness starting in legs
Any combination. Some say all 3 must be present. No sensory/cognitive deficit. No real treatment. Death from aspiration within 2 years.
| Def | Disturbance of voluntary motor function: rest tremor + bradykinesia + rigidity |
| Prevalence | 1–1.5/1,000 (common). Over 70: 1/200 |
| Age | Increases with age (usually >60) |
| Sex | M > F |
| Aetiology | Idiopathic: Dopamine deficiency in Substantia Nigra + relative excess of Acetylcholine in Corpus Striatum Atherosclerotic: Damage to Substantia Nigra from atheroma/stroke (often less tremor) Drugs: Neuroleptics · Poisoning: Manganese, Copper · Postencephalitic · Boxing |
Increased Intracranial Pressure:
Causes: Bleed, tumour, abscess, hydrocephalus, oedema (CVA/infection).
Mechanism: Direct pressure → midline shift → optic nerve stretched → pupil dilates then fixed. Pressure pushes brainstem → ↑BP + ↓pulse. Eventually "coning" → respiratory arrest.
Chronic raised pressure: Headache worse in morning & sitting up, worsened by Valsalva. Optic disc cupping.
Epilepsy:
Often idiopathic. Grand Mal: aura (strange taste/smell) → generalised fit → loss of consciousness ~½ hour post-fit → headache. May have incontinence + tongue bitten.
Investigations: EEG, CT. Treatment: Carbamazepine, Phenytoin, Valproate. Surgery.
📊 Differential Diagnosis Charts
Clinical DD grids from the textbook — organised by body region. Perfect quick revision.
🤕 HEADACHE — DD by Category
TRAUMATIC
- CSF Shunts
- Blows to head
- CVA/TIA
- Epidurals/myelograms
- RTA (concussion, whiplash)
- Birth trauma
METABOLIC
- ↑BP
- Vit A toxicity
- Anorexia/Bulimia
- Paget's
- Acromegaly
- Excessive alcohol/drugs
FUNCTIONAL
- Visual impairment
- Postural (bad ergonomics)
- RSI
- Previous trauma/loss of motion
- Muscle spasm
- Somatic Dysfunction C.Sp/TMJ
- Dehydration
- Depression/PMT
- Tension/Stress
- Drugs
- Fatigue/lack of sleep
INFLAMMATORY
- RA
- PMR
- Vasculitis
DEGENERATIVE
- OA
- Degenerative disc disease
- Neurological disease
- ↑BP
VASCULAR
- CVA (subdural, subarachnoid, intracerebral, thrombo-embolic)
- Hypertension
- Anaemia
- Migraine
- Aneurysm
CONGENITAL
- Apical ligament instability (Downs)
- Abnormal Foramen Magnum
- Vertebral abnormalities
- Vascular anomalies
- ↑CSF production
- Sutural fusion
- Budd-Chiari malformation
INFECTIVE
- Viral/Bacterial toxic headache
- Trigeminal neuralgia
- Otitis externa/media
- Cholesteatoma
- Dental abscess
- TMJ discitis
NEOPLASTIC
- Space occupying lesions
- Pituitary tumours
- Cranial nerve tumours
- Meningeal tumours
- Metastatic
- Bone cancer
- Multiple Myeloma
🦵 KNEE PAIN — Full DD
TRAUMATIC
- Muscle strain
- # Patella/femur/tib/fib
- Dislocation
- Ligament rupture/sprain
- Meniscal tears (bucket handle, pedunculated)
- Recurrent dislocating patella
FUNCTIONAL
- RSI
- Osgood Schlatters
- LLI
- Bursitis
- Somatic dysfunction
REFERRED
- OA hip
- Shin splints
- Neurological
- Pelvis/foot/ankle
DEGENERATIVE
- OA/RA
- AS
- Retropatella wear
- Bucket handle tear
- Baker's cyst
- Discoid lateral meniscus
- Loose bodies (OA 1–10, chip # 1–3)
- Synovial chondromatosis
INFLAMMATORY
- RA/AS/Reiters
- Bursitis
- Arthritis with GIT disturbance
- SLE
- Gout
METABOLIC
- Vit C/D deficiency
- Rickets
- Hyperparathyroidism
NEUROLOGICAL
- Neurovascular bundle compression
- Compartment syndrome
- L234 somatic dysfunction
- Charcot joints (tabes dorsalis)
- Neuroma
CONGENITAL
- Flabella
- Genu Varum (bow legs)
- Genu Valgus (knock knee)
- Osteogenesis imperfecta
- Diaphysial aclasis
- Absent patella
INFECTIVE
- Rheumatic Fever
- Pyogenic Arthritis
- TB
- Osteomyelitis
- Herpes
NEOPLASTIC
- Primary bone (osteosarcoma)
- Soft tissue
- Metastatic
- Ewing's (onion peel)
- Giant cell tumour
🦶 ANKLE/FOOT PAIN — Full DD
TRAUMATIC
- Ligament tear/rupture/sprain
- Muscle tear/rupture/strain
- #/dislocation
- March # (2/3 neck of met)
- Pilot's #
- Laxity
- Haglund's Deformity
INFLAMMATORY
- RA/OA/Bursitis
- Gout
METABOLIC
- DM (Charcot's)
- Crystal Deposition
- Osteoporosis
DEGENERATIVE
- OADJ disease
- Psoriatic arthritis
- Reiters (fluffy heel spurs)
- AS (Achilles tendonitis, plantar fasciitis, sausage digits)
NEUROLOGICAL
- Tarsal Tunnel Syndrome
- Foot Drop
- Charcot Marie Tooth (Pes Cavus)
- Friedreich's ataxia
- Spastic Flat Foot
- Polio
- Morton's neuroma
🦿 HIP PAIN — Full DD
TRAUMATIC
- # Femur/acetabulum/head
- #/dislocation head of femur
- # pubic ramus
- Dislocated pubis symphysis
- Pelvic floor tears
- Slipped upper femoral epiphysis
INFLAMMATORY
- RA/OA
- Bursitis
- Irritable hip (synovitis)
METABOLIC
- Gout (uric acid)
- Pseudogout (calcium pyrophosphate)
- Rickets
DEGENERATIVE
- OA/RA
- Perthes disease
- Intermittent claudication
- Paget's
CONGENITAL
- Congenital dislocation of hip
- Coxa vara
- OI
INFECTIVE
- TB
- Bursitis
- GIT disturbance
- Pyogenic
- Osteomyelitis
NEOPLASTIC
- Primary bone
- Metastatic
- Soft tissue
💪 SHOULDER PAIN — Full DD
TRAUMATIC
- Biceps tendon rupture
- # clavicle/humerus/scapulae
- AC & CC ligaments
- Rotator cuff rupture
- Recurrent dislocation
- Long thoracic N. palsy
INFLAMMATORY
- RA
- Gout
- Tendonitis (biceps, rotator cuff)
- Brachial neuritis
- PMR
- Bursitis · SLE
DEGENERATIVE
- Tendonitis
- Cuff tears (partial/complete)
- OA
NEUROLOGICAL
- Peripheral nerve palsy
- Discus
- Foramina (spondylosis)
- Syringomyelia
- Pancoast (apical lung)
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