MSK Flashcards
What are the 5 adult cancers that commonly metastases to bone?
Bronchus/lung Breast Prostate Kidney Thyroid (follicular thyroid)
What are the two paediatric cancers that commonly metastases to bone?
Rhabdomyosarcoma
Neuroblastoma
What bones are most commonly the site of metastases?
Long bones
Vertebrae
(good blood supply)
What is the most common primary bone tumour?
Myeloma
Describe some of the effects of bone metastases
Bone pain/destruction
Pathological fractures of long bones
Hypercalcaemia
Spinal metastases:
Vertebral collapse –> spinal cord compression –> nerve root compression –> back pain/paralysis (oncological emergency –> emergency radiotherapy)
What are the majority of bone mets? (Lytic/sclerotic?
Lytic
Describe lytic bone mets
Destroys the bone
Release of cytokines from tumour cells which activate osteoclasts to resorb bone
Can be inhibited by bisphosphonates
Describe sclerotic bone mets
Production of new woven bone
What types of cancer are sclerotic bone mets most commonly seen?
Prostate
Breast
Carcinoid tumours
What cancers most commonly cause a solitary bone met?
Renal and thyroid cancer
What are the orthopaedic consequences of a myeloma?
Punched out lytic foci
Generalised osteopenia - bone pain, tendency to fracture
What are the medical consequences of a myeloma?
Pancytopenia
Anaemia, thrombocytopenia, infections due to leucopenia
What are the immunological signs associated with a myeloma?
ESR >100
Serum electrophoresis: monoclonal bands
Bence Jones Protein in urine (immunological light chains)
What are the renal impairments associated with myeloma?
Myeloma kidneys (precipitated light chains in renal tubules) Hypercalcaemia Amyloidosis
Give three benign primary bone tumours
Osteoid osteoma
Chondroma
Giant Cell Tumour
Give three malignant primary bone tumours
Osteosarcoma
Chondrosarcoma
Ewing’s tumour
Describe osteoid osteoma
Small benign osteoblastic proliferation
(osteoblasts –> osteoid - woven bone)
Esp. common in adolescents
M:F 2:!
Can occur in any bone esp long bones, spine
What is the classical history of an osteoid osteoma?
Pain - worse at night
Relieved by NSAIDs
(+ scoliosis)
What is the management of osteoid osteoma?
Radiofrequency ablation
Describe osteosarcoma
A malignant tumour who’s cells form osteoid/bone
What is the peak incidence of osteosarcoma?
10-25y
What is the typical site of an osteosarcoma?
Metaphysis of long bones (50% around knee)
What clinical features are associated with osteosarcoma?
Pain, swelling, inability to move the joint
What is the natural history of osteosarcoma?
Highly malignant
Aggressive
Early lung metastases
5y survival 50-60%
What is Codman triangle in relation to osteosarcoma?
Tumour spreads very quickly through the cortex of a bone, so forms a new cortex
Describe the management of osteosarcoma
8/52 chemo
Surgery - endoprosthetic replacement
Further chemo
Describe Paget’s disease
Disorder of excessive bone turnover
Infection of osteoclasts - resorb too much bone
Activation of osteoblasts - structurally weak bone
What are the clinical signs of Paget’s disease?
Bone pain
Deformity
Pathological fracture
Osteoarthritis
Deafness (compression of CNVIII due to thickened skull)
High cardiac output failure (very vascular bone –> takes blood away from heart)
Paget’s sarcoma
Describe Paget’s sarcoma
Second osteosarcoma peak in elderly Usually lytic Long bones>spine Very poor prognosis Metastases to lung early
Describe enchondroma
Lobulated mass of cartilage within medulla
>50% hands, feet, long bones
Often asymptomatic in long bones
Hands - swelling, pathological fracture
Low cellularity - often surrounded by plates of lamellar bone
Describe osteocartilaginous exostosis
Benign outgrowth of cartilage with endo-chondral ossification
Describe chondrosarcoma
Most commonly occurs in middle-aged/elderly
Low grade tumours, less aggressive
Requires surgery
Describe Ewing’s sarcoma
Peak 5-15y Long bones Flat bones of limb girdles Early metastases to lung, bone marrow and bone Aggressive - 5y survival 50-60%
Define compartment syndrome
Elevated interstitial pressure within a closed fascial compartment resulting in microvascular compromise
Give some potential causes of compartment syndrome
Increased internal pressure:
Trauma - fracture, bleeding, entrapment
Muscle oedema/myositis
Intracompartment administration of fluids/drugs
Increased external pressure: Full thickness circumference burns Impaired consciousness Positioning in theatre - lithotomy Bandages/casts
Describe the pathophysiology of compartment syndrome
Pressure within the compartment > pressure within the capillaries
Microcirculatory collapse –> muscle becomes ischaemic
Oedema develops through increased endothelial perrmeability
Necrosis begins in the ischaemic tissue after 4 hours
Release of myoglobin –> kidney damage
Ischaemic nerves –> neurophraxic (irreversible after 4 hours)
Compromise of arterial supply –> absent pulse (late sign)
What are the signs of end-stage of compartment syndrome?
Stiff fibrotic muscle compartments
Impaired nerve function
Clawing of limbs (forearms flexed wrist and fingers; equine contracture in legs)
Loss of function
Describe the clinical signs attributed to compartment syndrome
Autonomic response - sweating, tachycardia
Swelling, shiny skin
6 P’s:
Pain out of proportion to be expected for level of injury
Pain on passive stretching of the compartment
Pallor
Parathesia
Paralysis
Pulseless (late sign)
What is the normal intracompartment pressure?
0-4mmHg (10mmHg with exercise)
What Compartment Pressures are diagnostic of ICP?
DBP-CP <30mmHg
CP >30mmHg
Describe the management of compartment syndrome
Open any constricting bandages/dressings down to skin –> reassess
Surgical release: full length decomposition of all compartments, excise any dead tissue
Later wound closure (48hr) - repeat debridement until pressure is down and all dead muscle has been excised
Skin grafts/plastic surgery
What are the compartments of the forearm?
Flexor
Extensor
Mobile Wad of Three
What are the compartments of the leg?
Anterior
Lateral
Deep Posterior
Superficial Posterior
What are the compartments of the thigh?
Anterior
Adductor
Posterior
Describe aspects of the preoperative management of compartment syndrome
Adequate fluid manage Measure fluid losses Monitor and regulate electrolytes - esp K Correct acidosis Monitor renal function/mygobulinuria
Describe the management of late presentation of compartment syndrome
Debride/amputate
Consider conservative management - splint in position of function
What are the clinical features of tendinopathy?
Loss of function Pain Swelling Thickening Tenderness
Describe the pathogenesis of tendinopathy
Chronic tendon injury due to overuse
Deranged collagen fibres in tendon
Invasion of blood vessels to aid healing
Increased cellularity (myofibroblasts) but not much of an inflammatory response
Release of inflammatory mediators (IL-1, NO, PG) –> apoptosis, pain, provokes degeneration through release of matrix metalloproteinases
What are the risk factors for developing tendinopathy?
Age Chronic disease (DM, RA) Adverse biomechanics (tight calf muscle --> achilles tendon under higher tension --> more likely to be damaged) Repetitive exercise Recent increase in activity Quinolone Abx
What are some of the common tendinopathies?
Achilles tendinopathy Rotator cuff tendonitis Tennis elbow (lateral epicondylitis) Golfers elbow (medial epicondylitis)
How are tendinopathies diagnosed?
XR - calcification in tendon, bone deposits around tendon
US - doppler to assess for neovascularisation
MRI - T1 (thickening of tendon); T2 (accumulation of fluid)
Describe non-operative management of tendinopathies
NSAIDs
Activity modification
Physio - eccentric exercises
GTN patches - increase local perfusion –> increase blood flow to tendon –> aids healing (takes 12/52 therefore compliance, headaches)
Platelet rich plasma - contains GF –> aids healing
Describe operative management of tendinopathies
Debridement - remove up to 50% of tendon before strength is affected
Tendon transfers
Define reactive arthritis
Sterile synovitis which occurs after a distal mucosal infection
What HLA gene is associated with reactive arthritis?
HLA-B27
What organisms can cause reactive arthritis?
Chlamydia trochomatis
Yersinia
Salmonella
Shigella
What are the clinical feature features of reactive arthritis?
Acute asymmetrical arthritis affecting the lower limb
More common in males
Occurs days-weeks post infection
Can cause dactylitis - entire digit is swollen
What is Reuter’s syndrome?
Post-infective arthritis
Non-gonorrhoeal urethritis
Conjunctivitis
How is reactive arthritis managed?
Treat underlying infection
NSAIDs
Intra-articular steroids
What is the prognosis of reactive arthritis like?
Usually self-limiting but can take up to 6/12
May be chronic
May have cardiac complications (aortic regurgitation, aortitis, amyloidosis)
What is enteropathic arthritis?
Reactive arthritis seen in association with Crohn’s disease/ulcerative colitis
How is enteropathic arthritis managed?
Treat underlying inflammatory bowel disease
NSAIDs
What are the clinical features of septic arthritis?
Pain
Fever
Swollen joint
Loss of function
What are the most common causative organisms of septic arthritis?
S.aureus
S.pyogenes
What organism most commonly causes septic arthritis in people who are sexually active?
N.gonnorhoea
What organism is most likely to cause septic arthritis in children?
H.influenzae
What is the most commonly used Abx regimen for the management of septic arthritis?
Flucloxacillin + gentamicin
IV for 2/52 then oral for 4/52
Define gout
Inflammatory arthritis that results due to the deposition of urate crystals in and around joints
What is the clinical presentation of gout?
Podagra (very painful monoarthritis of 1st MTJ)
Pain
Describe the pathogenesis of acute gout
Deposition of urate crystals in joint –> acute inflammatory process –> joint destruction (increased CVA risk)
Describe the pathogenesis of chronic gout
Deposition of urate –> tophi formation (may develop renal disease)
What investigations are needed for suspected gout?
Aspirate - negatively birefringent needle shaped crystals on polarised microscopy
Serum urate levels
U&Es
What is a primary cause of gout?
Lesch-Nyhan Syndrome
Rare inherited disorder
Gout + poor muscle control + self-mutilating behaviours
What are some secondary causes of gout?
High uric acid due to myeloproliferative disorders
Leukaemia treated with chemotherapy
Thiazide diuretics
Chronic renal disease
What are risk factors for developing high urate levels?
Older people
Metabolic syndrome
Alcohol excess
Red meat, shellfish, anchovies
Describe the management of gout
NSAIDs - high dose needed to reduce pain/swelling
Colchicine
Corticosteroids
What can Colchicine interact with?
Statins, cyclosporin, clarithromycin
What medications can be used to prevent repeated attacks of gout?
Allopurinol (inhibits xanthine oxidase) Uricosuric agent (probenecid) - increase secretion of uric acid into urine
Define pseudo-gout
Calcium pyrophosphate crystals deposition in the synovium
Define Chrondrocalcinosis
Calcium pyrophosphate crystals deposited into cartilage and extra-articular tissue
What are potential secondary causes of pseudo-gout?
Haemochromatosis
Hyperparathyroidism
What is the classic feature of joint aspirate in pseudo-gout?
Positively birefringent rhomboid shaped crystals
How is pseudo-gout managed?
Aspiration - reduces pain and swelling
NSAIDs
Colchocine
