MSK Pathology Flashcards
(130 cards)
Fracture
Break in structural continuity of bone.
Aetiology:
- Energy transfer (high force in normal, low force in abnormal)
- Repetitive stress (stress fracture)
Fracture repair mechanism
- Inflammation
Haematoma and fibrin clot released into area.
Lysosomal enzymes break down by-products of cell death and bring in new cells for repair
- Fibroblasts: collagen
- Mesenchymal and osteoprogenitor cells
- Macrophages: angiogenesis (if hypoxic) - Soft callus (10-14 days) - pain subsides:
Collagen matrix -> cartilage/fibrous tissue
- Stability: prevents shortening only - Hard callus (cartilage -> woven bone)
- Endochondral and membranous bone formation
- Responds to load
- Increased rigidity -> obvious callus - Bone remodelling (woven bone -> lamellar bone)
- Wolff’s Law: thicken in large load
Fracture Management
Reduction (restore alignment)
Hold (immobilise)
Rehabilitate
Surgery: platelet concentrates (IGF, PDGF, TGF-B, VEGF), bone graft (autogenous) and substitutes
Pathological healing of fracture
Reduction of inflammation
- NSAIDs
- Lose haematoma (surgery, open fracture)
- Poor vasculature
Delayed healing -> other management
Delayed union (>6 months)
- High energy trauma
- Distraction (large gap)
- Instability
- Infection
- Smoking
- Drugs: Steroids, Immunosuppressants, Warfarin, NSAIDs, Ciprofloxacin
Non-union
- Abundant callus
- Pain/tenderness
- Persistent fracture lines or sclerosis (ends seal off) on x-ray
Tendon repair mechanism
- Haemostasis and inflammation
- Organogenesis: disorganised collagen and angiogenesis
- Remodelling: type I collagen
Tendinosis
DEGENERATION
Intrasubstance mucoid degeneration (collagen)
- Chronic overuse or underload
- Swollen, painful, nodules, asymptomatic
- Management: load progressively
Tendinitis
INFLAMMATION (intrasubstance)
- Abrupt overload
- Swollen, tender, hot
- Management: offload, pain relief
Enthesopathy
Inflammation at bone insertion
Traction apophysitis
Inflammation or stress injury to growth plate area
- e.g. Osgood Schlatter’s - patellar tendon
- Active adolescent with inflammation + pain
Avulsion +/- bone fragment
Failure at bone insertion
- Load > failure strength when contracted
- e.g. Mallet finger - torn extensor tendon (forced flexion of extended finger)
- Management: conservative (retraction), operative
Tendon rupture/tear
Intrasubstance:
- Load > failure strength
- E.g. Achilles (violent dorsiflexion of plantar flexed foot): +ve Simmond’s, palpable tender gap
Musculotendinous:
- Sudden force of contraction
Management
- If ends can be opposed (US) -> conservative (splint, cast)
- If not or high re-rupture risk -> operative
Tendon laceration
Sharp object, often younger individuals
- Surgery early
Other tendon injury
- Crush
- Ischaemia
- Attrition
- Nodules
Ligament injury
Force exceeds ligament strength and ligament separates from bone
- Abnormal position
- Strongly contracted muscle
- Chronic stress
- Complete vs incomplete
Ligament repair mechanism
- Haemorrhage and inflammation
- Proliferative: disorganised collagen laid down
- Remodelling: stress -> more ligament-like collagen structure
Ligament injury Management
Depends on extent and patient
Conservative:
- Partial, stability, poor surgical candidate
- Light (compression, brace, stability) vs supportive (walker, cast)
Operative:
- Instability, expectation, compulsory (multiple)
- Direct repair (tied)
- Augment (taped)
- Replacement
Peripheral nerve injuries
Neuropraxia (Sunderland grade 1): nerve in continuity
- Stretched/bruised
Axonotmesis (Sunderland grade 2): endoneurium intact, disruption of axons
- Stretched, compression, direct blow
Wallerian degeneration follows
Neurotmesis (Sunderland grade 3,4,5): complete nerve division
- Laceration, avulsion
- Must be repaired
Peripheral nerve injury clinical features
Dysaethesiae:
- Anaesthesia
- Hypo/hyper-anaesthesia
- Paraesthesia (pins and needles)
Motor:
- Paresis (weakness)
- Paralysis +/- wasting
- Dry skin (sweat glands not activated)
Reflexes:
- Increased (UMN)
- Diminished (LMN)
- Absent
Strength: decreased Tone: increased (UMN) or decreased (LMN) Clonus (UMN) Babinski's sign (UMN) Atrophy (LMN)
Peripheral nerve repair mechanism
Regenerate slowly
- Wallerian degeneration of distal axons
- Proximal axon budding (4 days)
- Regeneration (1mm/day)
Peripheral nerve injury management
- Direct (no tissue lost)
- Nerve graft
Rule of 3:
- Clean/sharp -> immediate (3 days)
- Blunt/contusion -> 3 weeks
- Closed -> 3 months
Shoulder (glenohumeral) dislocation
Anterior most common
Posterior: epileptic fits, electrocution
- Sporting injuries
- Accidents
- Falling on outstretched arm
Shoulder dislocation clinical features
- Humeral head and acromion prominent
- Shoulder flattened
- Arm in slight abduction
- Elbow flexed and forearm internally rotated
Shoulder dislocation investigations and management
X-ray, arthroscopy
- Manipulation under sedation (Hippocratic and Kocher methods)
- Immobilisation
- Physiotherapy
- Surgery
Subacromial impingement syndrome (SAIS)
Pain and dysfunction of shoulder joint due to any pathology decreasing subacromial space or increasing size of subacromial contents (bursa, rotator cuff muscles and tendons)