Introduction to Orthopaedics

Orthopaedic injuries are some of the most commonly missed in the ED

Why?

• Failure to take a history
• Failure to examine properly
• Must MOVE the joint (especially if normal X-rays)
• Examine both sides and compare
• Not treated like other specialties (see above)

Do not be SCAREDOF normal X-rays

• Septic
• Compartment syndrome
• Abuse
• RE – Radiology error, REferred pain
• Dislocation/subluxation that has reduced
• Operative soft tissue injury
• Fracture (occult)

Fracture healing

• Three phases:
  • Inflammatory
    • Bone ends gradually necrose due to damage to blood supply, triggering classic inflammatory response with neutrophils, macrophages and lymphocytes to site
    • Cytokines released promote revascularisation
  • Reparative
    • Granulation tissue infiltrates area with callus formation (collagen, cartilage, bone)
    • Callus gradually mineralised
    • Necrotic edges resorbed by osteoclasts
  • Remodelling
    • Longest, years sometimes, resorption of superfluous callus, new bone laid down along lines of stress forming trabeculae

Fracture healing

• Anticipated degree of remodelling higher if:
  • Young
  • Proximity to end of bone (but not involving epiphyseal plate)
  • Lesser degree of angulation
  • Extent to which degree of angulation coincides with plane of natural joint motion
    • i.e. in wrist, dorsal or volar angulation is more acceptable than radial or ulnar angulation as dorsal/volar flexion/extension is the naturally plane of wrist motion

Mechanisms

Neurological assessment

• Based on peripheral nerves vs. dermatomes/myotomes with limb injury
• Upper limb
  • Axillary nerve – Sensation over deltoid patch and deltoid muscle activity
  • Musculocutaneous – Sensation over extensor aspect of forearm and elbow flexion
  • Radial nerve – Sensation over anatomical snuff box and wrist extension
  • Ulnar nerve – Sensation over ulnar aspect of palm and finger adduction
  • Median nerve – Sensation over lateral aspect of palm and thumb abduction

Neurological assessment

• Upper limb
  • C5 – Shoulder abduction + deltoid patch
  • C6 – Elbow flexion + thumb
  • C7 – Wrist extension + middle finger
  • C8 – Finger extension/flexion + pinky finger
  • T1 – Finger abduction/adduction + axillae

Neurological assessment

• Lower limb
  • Femoral nerve – Knee extension and anterior thigh + saphenous nerve
  • Sciatic nerve – Knee flexion + all below knee except saphenous nerve
  • Obturator nerve – Hip adduction
  • Tibial – Foot plantarflexion + heel sensation
  • Deep fibular – Foot dorsiflexion + 1^st web space
  • Saphenous nerve – Medial ankle and calf (branch of femoral nerve)
  • Superficial fibular – Rest of dorsum of foot
  • Sural nerve  – Lateral ankle and calf
  • Medial plantar and lateral plantars

Neurological assessment

• Lower limb
  • L1 – Underpants
  • L2 – Hip flexion + Anterior thigh
  • L3 – Knee extension + Knee dermatome
  • L4 – Foot inversion/dorsiflexion – Medial calf
  • L5 – Hallux dorsiflexion + Lateral calf
  • S1 – Ankle plantarflexion + Lateral aspect of foot
  • S2 – Behind knee
  • S3 – Buttock
  • S4/5 – Perianal region

Open fracture

• Antibiotics
  • Cefazolin 2g IV q6h +- gentamicin if >10cm with severe soft tissue loss
  • Consider adding metronidazole if contaminated with soil/organic matter or amputation
• ADT
• Debridement and decontamination
• Irrigation

POP

• At least 12 layers for adults and more for children (as do not protect dressings/plaster)

Crutches

• Ideal height is one hand width below axilla
• Grip bar should be adjusted where elbows are mildly flexed while supporting body weight
• Bear pressure of pads against sides of thorax rather than in the axillae (for risk of crutch palsy in brachial plexus)
• Three-point gait
  • Injured extremity kept off ground with swing-to or swing-through gait of good leg
• To ascend stairs
  • Well extremity up to next step, then crutches and then injured extremity
• To descend stairs
  • Crutches lowered first

Cane

• Instinctively held on same side as injury but SHOULD BE held on the well side and advanced forward with injured limb, followed by good leg

Osteomyelitis

• Mostly long bones in children and axial in adults
• Haematogenous spread in children mostly
• Contiguous in adults mostly (80%)
• Classification
  • Acute <2 weeks
  • Subacute 2-6 weeks
  • Chronic >6 weeks
• CT best for peripheral and/or chronic osteomyelitis
• MRI best for spinal and acute osteomyelitis (>90% sensitive)
• Bone scan 80-90% sensitive but lacks specificity
• BC positive in 50%

Osteomyelitis

• Treatment
  • Children <5yo
    • Fluclox 50mg/kg q6h + Cefotaxime/Ceftriaxone 50mg/kg q8h
    • 4 weeks all IV
  • Children >5yo
    • Flucloxacillin 50mg/kg q6h
    • 3 days IV and 4 weeks minimum total
  • Adults
    • Flucloxacillin 2g q6h +- Vancomycin 30mg/kg load then 15mg/kg BD +- Ceftriaxone 2g daily if suspected Gram negatives
    • 4 weeks IV and 6 weeks total

Prosthetic joint infections

• <1% hip/shoulder
• <2% knee
• Coag-neg Staph (35%)
• S. aureus (20%)
• Streptococci 10%
• Gram-neg Bacilli 5%

Prosthetic joint infection

• Early <3 months
  • Acute fever usually from surgical infection
• 3-24 months
  • Subtle pain, malaise
• >24 months
  • Infection usually haematogenous
• Investigations
  • WCC/CRP/ESR not sensitive or specific enough
  • Aspiration by Ortho
    • WCC >1700/mm3 or >65% neutrophils (95% sensitive; 90% specific)
    • Gram stain (25% sensitive; 95% specific)
  • Imaging not really useful as not specific or sensitive enough

Osteoporosis

• 30% of women and 15% of men sustain osteoporotic fracture in lifetime
• DEXA highly accurate and best predictor of fracture risk
  • 1-2.5 SD from mean = osteopaenia
  • >2.5 SD from mean = osteoporosis
  • >2.5 SD from mean with fragility fracture = severe osteoporosis
• Bisphosphonates
  • Increase BMN 4-8% over 3 years
  • Decrease vertebral fracture rate by 50%

Paget’s disease

• 2-4% of Australians over 55
• Usually incidental Xray or raised ALP
• Complications
  • Pathological chalk stick #
  • Osteosarcoma (<1%)
  • High output cardiac failure (rare)
  • CN palsy from skull thickening (sensorineural deafness)
• Mixed lytic/sclerotic on X-ray

Complex regional pain syndrome

• Pain, swelling and vasomotor dysfunction of extremity
• Sympathetic response continues post-injury unabated
• Prolonged ischaemia from subsequent vasoconstriction leads to viscious circle
• 5% of patients with upper limb trauma
• 15-20% of stroke patients that do not receive active physical therapy

Complex regional pain syndrome

• Acute phase
  • 3 months
  • Swelling, redness, burning pain, hyperhydrosis
  • Reversible oedema
• Subacute
  • 3-9 month period
  • Persistent severe pain, fixed oedema, pallor/dry skin
• Chronic
  • >9 months
  • Variable pain, oedema subsides but fibrotic joints
  • Dry, cool, shiny skin
• Pronounced demineralisation
• Prevention with active early ROM is key

Bone tumor systematic approach

• Age of patient
• Lytic well defined / Lytic ill-defined / Sclerotic
• Periosteal reaction: Benign vs. aggressive
• Location within skeleton
• Epiphysis/metaphysis/diaphysis

Bone tumor systematic approach

• Age
  • Infections in any age group
  • If <30yo, a narrow transition zone indicates benign
  • Metastases and plasmacytoma/multiple myeloma should be included in the differential of all patients >40 and those with known primary cancer

Bone tumor systematic approach

• <30yo
  • Simple bone cyst
  • Ewing sarcoma
  • Chrondroblastoma
  • Non-ossifying fibroma
  • Osteochondroma
  • Fibrous dysplasia
  • Osteosarcoma
  • Osteoid osteoma
  • Aneurysmal bone cyst
  • Eosinophilic granuloma
  • Giant cell tumor
  • Enchondroma

Bone tumor systematic approach

• >30yo
  • Enchondroma
  • Fibrosarcoma
  • Osteoma
  • Chondrosarcoma
  • Myeloma
  • Metastases
  • Chordoma

Bone tumor systematic approach

• DDx of wide zone of transition
  • Malignant
  • Infection
  • Eosinophilic granuloma

Bone tumor systematic approach

• Aggressive periosteal reactions
  • Seen in infectious and malignant aetiologies
  • Fibrous dysplasia, enchondroma, non-ossifying fibromas and simple bone cysts do not show aggressive periosteal reactions unless fractured

Location at end of bone

Bone tumours

• Metastatic tumors
  • Mostly osteolytic
  • Pain absent in 70%
  • Common primary
    • Adult – Lung, kidney, breast, prostate, thyroid, colon
    • Children – Neuroblastoma, leukaemia
  • Common bones
    • Spine, ribs, pelvis, skull, proximal femur/humerus
    • Rare below knee/elbow

Bone tumors

• Osteolytic DDx
  • Metastases: Renal cell, small cell, thyroid, melanoma, lymphoma
  • OA (Schmorl’s nodes, subchondral cysts)
  • Metabolic bone disease
  • Cystic angiomatosis
• Osteosclerotic DDx
  • Metastases: Prostate, carcinoid, small cell, Hodgkin’s, medulloblastoma
  • Bone islands
  • Tuberous sclerosis

Bone tumors

• Management
  • Decompression if compression symptoms
  • Analgesia
  • Glucocorticoids 7.5-10mg prednisone daily
  • Bone cement vertebroplasty
  • Radiotherapy
    • Partial pain relief in 80%; complete relief in 30%
    • Repeat radiotherapy provides only partial in 30%
  • Bisphosphonates if breast Ca
  • +- Chemo/hormonal therapy

Malignant primary tumors

• Aneurysmal bone cysts
  • 10-30yo, eccentric in long bones
• Osteosarcoma
• Chondrosarcoma
• Giant cell sarcoma
• Ewing’s tumor
• Paget’s sarcoma
• Irradiation sarcoma

Malignant primary tumors

• Radiological features of malignancy
  • Poorly defined margins
  • Absence of surrounding sclerosis
  • Break in the cortex
  • Periosteal reaction (sail sign; onion-skinned)

Benign tumors

• Fibroxanthoma
• Simple bony cyst
• Chondroma
• Osteochondroma
• Osteoid osteoma
• Osteoblastoma
• Fibrous dysplasia
• Chondroblastoma

Fibrous cortical defect/Fibroxanthoma

• Fibrous cortical defect (non-ossifying fibroma)
  • 30% prevalence in children
  • Knee/distal tibia
  • Peaks 10-15yo
  • Rare in those >30yo
  • <2cm in size
  • Cortex of metaphysis, eccentric, thin sclerotic border
• Fibroxanthoma
  • Peaks adolescence
  • Rare in patients >40yo
  • >3cm in size
  • Intramedullary adjacent to cortex

Simple bone cyst

• Under 30 yo
• Common cause of pathological fracture
• Mostly proximal humerus, proximal tibia, femur
• Arises in physeal growth plate and extends into diaphysis
• Solitary, central

Chondroma

• Seen on tubular bones of hands
• Asymptomatic unless pathological fracture

Osteochondroma

• Cortical + cancellous bone with cartilage cap
• Metaphysis of long bones
• Larger clinically than radiologically (cartilage component)

Osteoid osteoma

• Femur or tibia in young adults
• Rarely vertebral column (15%)
• Aching pain, worse at night, responds rapidly to NSAId’s
• No malignant potential
• Resolve spontaneously

Osteoblastomas

• Larger more aggressive osteoid osteomas
• Can spread to cause compressive symptoms

Fibrous dysplasia

• Lytic large lesions in long bones
• Ground glass appearance
• Asymptomatic unless pathological fracture

Chondroblastoma

• Epiphysis of long bone
• Mostly humerus in second decade of life

Soft tissue sarcomas

• Benign soft tissue tumours are 100x more common (e.g. lipomas)
• 1% of all cancer
• 50% mortality rate
• EBV and HIV associated with leiomyosarcoma
• Irradiation associated with sarcoma
• Surgical resection with wide margins +- amputation+- Radiotherapy

Periprosthetic fractures

• A – Apophyseal
  • E.g. trochanters of femur
  • Conservative unless soft tissue attachments important or grossly displaced
• B – Bed of implant
  • Management depends on how loose and quality of bone in bed
• C – Clear of implant
  • Management as if implant not there
• D – Dividing one bone which supports two joint replacements
  • Management of fracture and specific replaced joint separately
• E – Each of two bones supporting one joint replacement
  • Management of fractures and specific replaced joint separately
• F – Facing or articulating with replacement
  • Conservative if undisplaced or operative for displaced

Dual energy CT

• Distinguishes between monosodium urate crystals (gout) and other soft tissue/mineralization
• Studies seem to be on chronic cases of gout
• Joint aspirates can be negative in up to 25% of acute gout cases
• 100% sensitive and specific for tophaceous gout

Last Updated on April 14, 2021 by Andrew Crofton