How to Treat MSK Conditions Tutorial Flashcards
What is Greek for bone?
Osteo
What are the 4 types of bone cells?
Osteogenic cell = precursor, bone ‘stem cell’
Osteogenic cells give rise to:
Osteoblasts =
‘Bone forming’
Secretes ‘osteoid’
Catalyse mineralisation of osteoid
Osteocyte =
‘Mature’ bone cell
Formed when an osteoblast becomes imbedded in its secretions
Sense mechanical strain to direct osteoclast and osteoblast activity
Osteoclast =
‘Bone breaking’
Dissolve and resorb bone by phagocytosis
Derived from bone marrow
The balance between which 2 types of bone cells is responsible for the turnover of bone?
Osteoblast and osteoclast activity
What is the organisation of the cortical (compact) bone?
Cortical bone = outer shell of the bone
Made up of osteons and osteoblasts and osteoclasts which sit ont he lining of the bone on the outside (periosteum) or inside (endosteum)
Central canal = Haversian canal
And concentrically around the central canal are the osteocytes - sitting within the mineralised bone matrix
Volkmann’s canals = transverse system communicating between the osteocytes and the Haversian canal
What is an osteon?
Repeated structural units
Concentric ‘Lamellae’ (made up of osteocytes) around a central ‘Haversian Canal’
What is the structure of a cross section of long bones?
Periosteum – Connective tissue covering
Outer Cortex – compact (cortical) bone
Cancellous bone
Medullary cavity - central part of the bone, contains yellow bone marrow and cancellous bone
Nutrient Artery
Articular cartilage: on surface of bone at a joint only
How do bones grow in children?
What is the structure of the long bone?
Growth plate proximally AND distally in long bones - known as the physis
Above the physis (closest to the joint) is the epiphysis and below is the metaphysis
Main body of the bone = diaphysis
What are the 3 mechanisms of fracture?
- Trauma - low energy or high energy
- Stress - abnormal stresses on normal bone
- Pathological - normal stresses on abnormal bone
Why might the bone be abnormal pathologically?
Pathological causes of abnormal bone =
Osteoporosis - low bone mineral density
Low bone mineralisation e.g. Vit D deficiency, osteomalacia / rickets
Malignancy - primary bone cancer or bone metastases
Infection e.g. osteomyelitis
Osteogenesis imperfecta
Pagets - degenerative turnover of bone that leads to abnormal bone
What is the difference between pathological VS insufficiency fractures?
Pathological = all abnormal bone Insufficiency = subgroup of pathological, usually applies to abnormalities due to metabolic diseases e.g. age related osteoporosis, or abonrmal mineralisation due to vitamin d deficiency
How are fracture patterns described?
- Soft tissue integrity - open (breached) VS closed
- Bony fragments - greenstick, simple, or multifragmentary (comminuted)
- Movement - displaced or undisplaced
What are the 3 phases of fracture healing?
- Inflammation - bone bleeds, blood brings swelling but also cells and cytokines that eventually produce new blood vessels and osteoblasts gradually start producing collagen
- Repair - soft callus formation (type II collagen - cartilage) initially, that then turns into type I collagen forming a hard callus (bone)
- Remodelling - overtime, osteoclasts and osteoblasts remodel bone according to the stresses placed on it
What is Wolff’s law?
Bone grows and remodels in response to the forces that are placed on it
What are the clinical signs of a fracture?
Pain
Swelling
Crepitus - abnormal popping or cracking of a joint
Deformity
Adjacent structural injury e.g. nerves, vessels, ligaments, tendons
What are the investigations of fracture?
X-ray = first line investigation for suspected fractured bone
CT scan = used to assess exact architecture of a fracture as they only tell you about bones
MRI = mainly for soft tissue information
Bone scan = rarely used, but used for multiple fragments OR spread of infection so they are not performed without very good reason due to dye injection, exposure of radiation etc.
How are fractures described on radiographs?
Location - which bone and which part of the bone? (use thirds or diaphysis/metaphysis/epiphysis) Pieces - simple or multifragmentary? Pattern - transverse, oblique or spiral? Displacement - displaced or undisplaced? Translated or angulated? Plane - X, Y or Z plane?
What are the 2 types of displacement?
- Translation - lateral (along a straight line)
2. Angulation - fracture is angled (no longer in a straight line)
What are the different types of translation?
Up or down = proximal / distal
Side to side = medial or lateral
Forward or backward = anterior / posterior
What are the different types of angulation?
Distal fragment moving away from the midline = valgus
Distal fragment moving towards the midline = varus
Backwards = volar
Front = Dorsal
Look at patient feet up - Internal (towards midline) / External (away from midline) rotation
What are the general principles of fracture management?
Reduce - open or closed
Hold - metal or no metal
Rehabilitate - move, physiotherapy, use
How can fractures be reduced?
Closed:
Manipulation
OR
Traction - pulling the skin or place pins in the bone (skeletal)
Open:
Mini-incision
OR
Full exposure
How can fractures be held?
Closed:
Plaster
OR
Traction (skin or skeletal)
Open:
Fixation (using metal)