Orthopaedics Flashcards
Embryological development of the musculoskeletal system begins at what week of gestation?
Approx. the 4th week
Activations of mesenchymal cells in what embryological structure is responsible for the development of the musculoskeletal system?
Somatic lateral mesoderm
What genes are responsible for regulating the musculoskeletal system?
Homeobox genes
At what days gestation do the upper and lower limb buds develop?
Upper limb buds - day 24
Lower limb buds - day 25-26
What are limb buds?
Elongated proliferations of mesenchyme
What structure forms at the apex of each limb bud? What is their function?
Ectoderm thickens to form the apical ectodermal ridge (AER) which exerts an inductive influence on the limb mesenchyme causing the growth of blood vessels/cartilage/bone etc.
Outline the process of the embryological formation of hands and feet
Distal ends of the limb buds flatten into paddle-like plates which condense into digital rays for hands and feet by six and seven weeks gestation respectively.
What process causes separation of digital rays to make individual fingers and toes?
Programmed cell death (apoptosis) mediated by morphogenetic proteins
What defect may arise from the incorrect separation of digits in utero?
Syndactyly (simple cutaneous or complicated osseous)
Cartilaginous precursors to the bones of the limbs develop from what embryological structure?
Mesoderm
What areas of proto-bone develop between 8 and 12 weeks gestation? What causes their development?
Primary centres of ossification appear in response to growth factors
What type of calcification occurs for all limb bones? What is the one exception?
Endochondral ossification for all limb bones except the clavicle (membranous ossification instead)
Both limbs rotate in utero during the development of the musculoskeletal system.
Outline rotation of both upper and lower limbs respectively
Upper limbs - rotate laterally - extensors are on lateral/posterior surface (remember the thumb is lateral)
Lower limbs - rotate medially - rotate medially so extensors are on anterior surfaces (remember big toe is medial)
Birth defects of the limbs can be either hereditary or teratogenic in nature. What is the word used to describe a total lack of limbs?
Amelia
What is meant by the term meromelia?
Partial lack of limbs
What is meant by the term phocomelia?
Partial loss of long bones
What is meant by the term micromelia?
All parts of limbs present but small
What teratogen is associated with meromelia?
Thalidomide
What is the medical term of a congenital club-foot?
Talipes equinovarus
Describe congenital clubfoot
Soles of feet are turned medially and the foot is inverted
List different types of bone-forming tumours
Benign - osteoid osteoma, osteoblastoma
Malignancy - osteosarcoma
List different types of cartilage-forming tumours
Benign - enchondroma, osteochondroma
Malignant - Chondrosarcoma
List different types of fibrous tissue tumours
Benign - fibroma
Malignant - fibrosarcoma, malignant fibrous histiocytoma (MFH)
List different types of vascular tissue tumours
Benign - haemangioma, aneurysmal bone cyst
Malignant - angiosarcoma
List different types of fatty tissue tumours
Benign - lipoma
Malignant - liposarcoma
List different types of bone marrow tissue tumours
Malignant - Ewing’s sarcoma, lymphoma, myeloma
What is the commonest primary malignant bone tumour in younger patients?
Osteosarcoma
What is the commonest primary malignant bone tumour in older patients?
Myeloma (not strictly a bone malignancy but it is a major diagnostic aspect of the disease)
List some investigation which may be useful in the diagnosis and monitoring of bone tumours
Plain X-Rays CT Scan Isotope bone scan MRI PET Scan
Outline the clinical features of a bone tumour
Pain (worse at night) Loss of function (limp/reduced movement/stiff back) Swelling Pathological fracture Joint effusion Deformity Neurovascular effects
What is the triad of pathophysiology of osteoarthritis?
Tear, flare and repair
A lifetime of wear (and injuries) cause inflammation and subchondral changes lead to activation of the repair process - constant cycles of repair lead to destruction of cartilage
What are the diagnostic criteria for osteoarthritis?
Typically aged +45
Activity related joint pain
No related morning stiffness/stiffness that lasts <30 mins
Pay attention to a history of trauma, prolonged morning stiffness, rapid deterioration or systemic symptoms as this may point to a more serious underlying diagnosis
What are some differential diagnoses for osteoarthritis?
Gout
Inflammatory arthritides (rheumatoid, psoriatic etc.)
Septic arthritis
Malignancy
What is the treatment escalation plan for osteoarthritis?
First-line - non-pharmacological treatments
Second line - pharmacological
Third line - surgical intervention
What non-pharmacological treatments are available or osteoarthritis?
Thermotherapy, electrotherapy, aids and devices, manual therapy
What pharmacological treatments are available or osteoarthritis?
Oral analgesia (paracetamol, NSAIDs) Topical treatments (NSAIDs, capsaicin cream)
What age demographic is most likely to develop osteomyelitis?
Mostly children with boys being more affected than girls
What routes of infection may lead to osteomyelitis?
Hematogenous spread
Local spread - from a contiguous site of infection e.g. trauma (open fracture), surgery (ORIF) or joint replacement
What are the most likely causes of osteomyelitis in infants, children and adults respectively?
Infants - infected umbilical cord
Children - boils, tonsilitis, skin abrasions
Adults - UTI, arterial lines
What organisms are most likely to be the cause of osteomyelitis in infants?
Staph aureus
Group B strep
E. Coli
What organisms are most likely to be the cause of osteomyelitis in older children?
Staph aureus
Strep pyogenes
H influenzae
What organisms are most likely to be the cause of osteomyelitis in adults?
Staph aureus
Coagulase -ve staph
Mycobacterium
Pseudomonas aeroginosa
What organism(s) are most likely the cause of osteomyelitis in diabetic foot/pressure sore patients?
Mixed infection (including anaerobes)
What organism(s) are most likely the cause of osteomyelitis in sickle cell disease patients?
Salmonella spp.
What organism(s) are most likely the cause of osteomyelitis in fishermen or filleters?
Mycobacterium manrium
What organism(s) are most likely the cause of osteomyelitis in HIV/AIDS patients?
Candida
What anatomical sites are most commonly affected by osteomyelitis?
Long bones (particularly distal femur, proximal tibia or proximal humerus)
Joints with intra-articular metaphysis (hip, elbow (radial head)
Outline the pathophysiology of osteomyelitis
Acute inflammation at the metaphysis/suppuration causing vascular stasis.
Release of pressure
