Week 11 - MSK Flashcards
Define compartment syndrome. What are common sites?
Elevated interstitial pressure within a closed fascial compartment resulting in microvascular compromise.
Leg, forearm, thigh.
What causes compartment syndrome?
Internal pressure: Trauma (bleeding), muscle oedema, intracompartmental administartion of fluids/drugs, vascular surgery
or
External compression e.g. casts/bandages, full thickness burns, positioning in theature i.e. lithotomy.
Describe the pathophysiology of compartment syndrome.
Pressure within compartment exceeds pressure within the capillaries. Loss of perfusion and muscles become ischaemic and oedematous due to increased endothelial permeability. Necrosis begins in ischaemic muscles after 4 hours and ischaemic nerves become neuropraxic.
What are the clinical features of compartment syndrome?
Pain (out of proportion to that expected from the injury)
Pain on passive stretching of the compartment.
Pallor
Parasthesia (later stage)
Paralysis (later stage)
Pulselessness (later stage)
Limb may be swollen and the skin shiny.
Autonomic responses i.e. sweating, tachycardia may be present.
What compartment pressure indicates compartment syndrome and a need for fasciotomy?
> 30 mmHg
What is the treatment for compartment syndrome?
Open any constricting dressings and bandages, Reassess Surgical release - fasciotomy Later wound closure Possible skin grafting
What is the structure and function of tendons?
Parallel collagen fibrils with tenocytes, surrounded by sheath, largely avascular.
Function: transmits force from muscle to bone.
Describe the pathology of tendonopathy.
Chronic tendon injury of over use, degeneration and disorganisation of collagen fibres, increased cellularity, not a lot of inflammation, increased vascularity around tendon, IL-1, NO and PG release MMPs.
What are the risk factors for tendonopathy?
Age, chronic disease, diabetes, rheumatoid arthritis, adverse biomechanics, repetitive exercise, recent increase in exercise, quinolone antibiotics.
What are the clinical features of tendinopathy?
Pain, swelling, thickening, tenderness, provocative tests.
What imaging techniques are best for seeing tendinopathy?
Ultrasound, T1 MRI
What are some of the non-operative measures for tendinopathy?
NSAID’s, activity modification, physiotherapy, GTN patches, PRP injections, extracorporeal shock wave therapy, steroid injection.
What is the operative treatment for tendinopathy?
Debridement (excision of diseased tissue).
What are the functions of bone?
Structural: support, protection, movement.
Mineral storage: calcium, phosphate.
Describe 2 different types of bone tissue?
Outer cortical bone which is 80% of the skeleton, slow turnover rate, resistant to torsion and bending, small air spaces.
Inner cancellous bone, undergoes greater remodelling, more elastic, contains larger spaces with marrow and blood vessels.
Describe the composition of bone.
Cells - osteoclasts, osteoblasts, osteocytes, osteoprogenitor cells.
Matrix - inorganic - calcium, phosphorus. Organic - collagen type 1, mucopolysaccharides, non-collagenous proteins.
What are the different sections of a long bone?
Diaphysis (shaft)
Epiphysis (end)
Metaphysis (transitional flared area between diaphysis and epiphysis)
What are the steps of indirect fracture healing and the timescale of these steps?
- Fracture haematoma and inflammation.
- 6-8 hours after injury - Fibrocartilage (SOFT) callus formation.
- lasts about 3 weeks - Bony (HARD) callus formation.
- after 3 weeks, lasts about 3-4 months. - Bone remodelling - up to 2 years.
What is direct fracture healing?
Direct formation of bone WITHOUT the process of callus formation.
What different factors can compromise blood supply to bone?
Surgical factors (iatrogenous) Anatomical factors (certain fracture are just more prone to problems with blood supply) i.e. proximal pole of scaphoid, talar neck fractures, intracapsular hip fractures, surgical neck of humerus fractures.
What patient factors inhibit bone healing?
Increasing age, smoking, alcohol intake, diabetes, anaemia, malnutrition, peripheral vascular disease, hypothyroidism.
Name 3 types of medication that can affect bone healing.
NSAIDs (reduce local vascularity at fracture site) steroids, bisphosphonates.(inhibit osteoclast activity)
Secondary tumours in the bone are very common. Which primary cancers commonly lead to bone metastases?
Bronchus, breast, prostate, kidney, thyroid.
Which childhood cancers often lead to metastases of the bone?
Neuroblastoma, rhabdomyosarcoma.
Which bones are often affected by metastases?
Those with good blood supply i.e. long bones, vertebrae.
How can bone metastases present?
Often asymptomatic
Bone pain (typically unremitting and worse at night)
Swelling
Systemic symptoms i.e. weight loss, malaise
Pathological fractures
Hypercalcaemia
Spinal metastases: vertebral collapse, spinal cord compression, nerve root compression, back pain.
What investigations could be performed for suspected bone tumours?
Skeletal isotope scan, x-rays, MRI, PET-CT.
Serum alkaline phosphatase, hypercalcaemia.
Name 3 benign primary bone tumours and 3 malignant.
Benign:
Osteoid osteoma
Chondroma
Giant cell tumour
Malignant:
Osterosarcoma
Chondrosarcoma
Ewing’s tumour
What age group, sex and part of the skeleton is most commonly affected by osteoid osteoma?
Adolescents
Males
Any bone, especially spine and long bones.
What age group, sex and part of the skeleton is most affected by osteosarcoma?
Age 10-25
Males
Metaphysis of long bones, especially knee.
Where does osteosarcoma commonly metastsize to? Which variant has a worse prognosis?
The lung.
Paget’s osteosarcoma.
What is an enchondroma? Which bones does it commonly affect?
A lobulated mass of cartilage within in the medulla.
Hands and feet, long bones.
What is Osteocartilaginous Exostosis? Which age group does it normally affect? Where in the bone is it normally found?
Benign outgrowth of cartilage with endo-chondral ossification.
Adolescence
Metaphysis of long bones.
What age group, sex and part of the skeleton is commonly affected by chondrosarcoma?
Middle aged and elderly
Males
Axial skeleton i.e. ribs, pelvis, shoulder.
Which age group is normally affected by a Ewing’s sarcoma? Where does it often metastasize to? Which bones does it normally affect? Which sex does it normally affect?
5-15 year old
Lung, bone, bone marrow.
Flat bones of limb girdles.
Females
How are bone tumours managed?
- analgesics and anti-inflammatory drugs
- local radiotherapy
- chemotherapy
- bisphosphonates for symptoms.
Describe the aetiology of rheumatoid arthritis.
HLA-DR4 and other genetic factors.
Smoking
Infection i.e. EBV, TB
Pregnancy? (female preponderance)
Describe the epidemiology of rheumatoid arthritis.
Female:male ration 3:1
Affects 1% of caucasians
30-50 years old at presentation.
Describe the pathophysiology of rheumatoid arthritis.
Synovitis - infiltration of inflammatory cells to synovium.
Pannus, a layer of chronically inflamed tissue extends across the cartilage, destroying it.
This results in bone destruction and joint deformities.
What are the clinical features of rheumatoid arthritis?
Synovitis - any synovial joint
Symmetrical
Small joints of hands and feet early on, shoulder and hip at onset rare.
MCPs/PIP/wrists
Inflammatory - pain, erythema, swelling,
Tenosynovitis, bursitis, CTS
Constitutional symptoms i.e. fatigue, weakness, low grade fever, weight loss, anorexia.
Name 3 extra-articular signs of RA.
pleural effusion, lung fibrosis, peripheral neuropathy.
How would RA be investigated?
Bloods: FBC, U&Es, LFTs, ESR/CRP, RF (rheumatoid factor), ACPA (anti-citrillunated peptide antibody), ANA (anti-nuclear antibody). X-ray USS MRI
What are the potential differentials for a diagnosis of rheumatoid arthritis?
OA SLE/other connective tissue disease PMR (polymyalgia rheumatica) Psoriatic arthropathy Sponyloarthropathies Reactive arthritis Sarcoid CPPD (calcium pyrophosphate) Lyme’s
What are the different treatments for RA?
Non-pharmacological:
OT/PT
Pharmacological:
Symptomatic - NSAIDs, analgesia
Disease modifying - DMARDS - i.e. methotrexate, sulfasalazine
Glucocorticoids
Biologics i.e. anti-TNF - etanercept, infliximab. Anti-CD20 i.e. rituximab
What does biological therapies in RA increase your risk of? What precautions should be made?
Infection i.e. TB, varicella zoster.
Determine vaccine status and vaccinate against influenza and pneumococcal annually.
What are the indications for immunosuppressant drugs?
Abnormal inflammation - inflammatory arthropathies, ilcerative colitis/crohn’s, psoriasis.
or
Unwanted normal inflammation -
Solid organ transplants, bone marrow grafts
Name some side effects of steroids.
Weight gain + fluid retention Glaucoma Osteoporosis Infection Hypertension + hypokalaemia Peptic ulceration and GI bleed Psychiatric symptoms
Name 3 non-steroid immunosuppressant drugs.
Methotrexate
Azathioprine
Cyclosporin
What is the mechanism of action of methotrexate?
Stops the action of the enzyme dihydrofolate needed for production of DNA.