MSK - week 1 Flashcards
What are the three joint types?
Fibrous
Cartilainous
Synovial
What are the examples of fibrous joints
Cranial sutures
Interossous membranes
Peridontal ligaments (teeth)
What are the types of cartiliganous joints?
Give an example of both
Primary - only hyaline
– Synchondrosis (growth plates)
Secondary - hyaline and fibrocartilage
–Symphysis - intervertebral discs
What are the common features of a synovial joint?
Synovial cavity
Fibrous capsule
Synovial membrane
Articular cartilage
May contain:
Articular discs
Ligaments
Bursea (fluid filled sacs)
What are the types of synovial joints?
Plane Hinge Pivot Condylar Saddle Ball and socket
What contributes to joint stability?
Shape of articulating surfaces
Capsule + ligaments
Muscles
What is the arrangement of articular cartilage?
Made of two levels, superficial and transitional.
Superficial - made up of flattened chondrocytes that produce collagen and glycoproteins
Transitional - round glycoproteins producing protoglycans
Made up of at least 75% water so uncompressible
What are glycoproteins?
proteins to which oligosaccharide chains are attached, i.e. more a protein than a carbohydrate!
IE lubricin
What are proteoglycans?
proteins that are heavily glycosylated (= a protein core to which one or more GAGs attach), i.e. tend to be more carb than protein!
IE aggrecan
What are Glycosaminoglycans (GAGs)?
long unbranched polysaccharides, which are highly polar and thus attract water
IE hyaluronic acid
How does cartilage get its nutrients?
Gets it from the synovial fluid (in the synovial membrane)
Not from blood supply as it’s avascular
Describe the synovium.
Contains synoviocytes which produce the synovial fluid
Has no epithelial lining and a rich capillary network
This facilitates direct exchange of oxygen + other nutrients
What are the differences between the types of synoviocytes?
Type A - look similar to macrophages
Remove debris
Contribute to synovial fluid production
Type B - fibroblast like
Main producer of synovial fluid
What is synovial fluid + functions?
A viscous fluid present in small volumes with rapid turnover
Lubricates joints + exchanges nutrients for cartilage
What are bursae?
Sacks around joints filled with liquid to reduce friction
Can lead to bursitis if inflammed
How does aging affect joints?
Viscosity of the synovial fluid increases
Leads to slower joint movements and reduced lubrication
Water content of cartilage decreases, reducing shock absorption
How does osteoarthritis affect the bones?
Narrowing vertebral disks
Bone spurs
What is sarcoma?
A malignant tissue from connective tissues
Spreads along fascial planes
Haematogenous spread to lungs
Describe bone tumours
Benign tumours common, although malignant is rare
Tend to be more secondary tumours
What are the bone forming tumours? (malignant and benign)
Benign - osteoid osteoma
Osteoblastoma
Malignant - osteosarcoma
What are the cartilage forming tumours?
Benign - enchondroma
Osteochondroma
Malignant - chondrosarcoma
What are fibrous tissue tumours?
Benign - firoma
Malignant - fibrosarcoma
Malignant fibrous histiocytoma (MFH)
What are the vascular tissue tumours?
Benign - haemangioma
Aneursmal bone cyst
Malignant - angiosarcoma
Examples of adipose tissue tumours
Benign- lipoma
Malignant - liposarcoma
Examples of marrow tissue tumours
Malignant
Ewings sarcoma
Lymphoma
Myeloma
What invesitgations are pertinent with suspected bone lesions?
Plain X-rays
What are the differences in x-rays for aggressive and non-aggresive bone tumours?
Aggressive have less well defined transition zones
Cortical destruction is a sign of malignancy
What are isotop bone scans?
Used for staging of skeletal mets
Frequently negative in myeloma
Not great at distinguishing malignant from benign as benign also demonstrate increased uptake
What are the cardinal features of a primary bone tumour?
Pain either unexplained, at night or increasing in severity
With a deep seated boring nature
Difficulty weight bearing
Deep swelling
Name 3 examples of primary bone tumours
Osteosarcoma
Ewings sarcoma
Chondrosarcoma
What are the clinical features of osteosarcoma?
Pain
Loss of function
Swelling Pathological fracture Joint effusion Deformity Neurovascular effects Systemic effects of neoplasia
What is the pain like in osteosarcoma?
Pain increasing in nature, not related to exercise
Deep boring character worse at night
Analgesics eventually inneffective
What characterises loss of function in osteosarcoma?
Limp
Reduced joint movement
Stiff back - especially in a child
What are the clinical features of swelling in osteosarcoma?
Generally difuse in malignancy
Near end of long bone
Enlargement can be rapid
Warmth over swelling + venous congestion = active
Why is MRI the investigtion of choice for suspected osteosarcoma?
Very sensitive Very good for showing: Intraosseous AND extraosseous (soft tissue) extent of tumour Can show joint involvement Skip metastesis Epiphyseal extension
Good for determining resection margins
Treatment for osteosarcoma?
Chemo
Surgery
Radiotherapy
Goal is to make free of disease
What are the suspicous signs of a soft tissue tumour?
Deep (deeper than deep fascia)
Subcutaneous tumours greater than 5cm
Rapid growth, hard, craggy or non-tender
If any of these refer to specialist tumour centre
What are the common sites causing bone metastases?
Breast Melanoma Lung Prostate Kidney Thyroid GI tract
Most common site after lung and liver for secondary tumours
What are the common bones to develop a secondary tumour?
Order: Vertebrae Proximal femur Pelvis Ribs Sternum Skull
How can you prevent pathological fractures?
Early chemotherpay
Prophylactic internal fixation based on Mirel’s scoring system. 8+ indicates fixation
What is Mirel’s scoring system?
Picture needed
What is osteoarthritis?
Most common form of joint problem Consists of "Tear, flare and repair" -Trauma and mechanical imbalance -Causes inflammation and pain -Repair processes around joint
What are the biomechanical factors of osteoarthritis?
Abnormal anatomy Intra-articular fracture Ligament rupture Meniscal injury Occupation (farmers/football players Persistent heavy physical activity Elite running Obesity
What events happen due to inflammation in the joints?
Synovial hypertophy
Subocondral changes
Joint effusion
What is the pathogensis of primary OA?
Wear + tear - joint use over the years causes degeneration in cartilage
What is the pathogensis of secondary OA?
Due to increased load that causes joint microtrauma
Increased load can be due to weight gain (obesity) or instability / misalignment of joint
This can arise from either muscle weakness, ligament injury or abnormal anatomy
How do you diagnose OA?
A patient who is 45+ with activity related joint pain
With morning joint related stiffness being absent or lasting less than 30 minutes
What are the differentials of OA?
Gout
Other inflammatory arthritides
Septic arthritis
Malignancy
What are the non-pharmacological treatments for OA?
Thermotheraphy
Electrotherarpy
Aids/devices
Manual therapy
What are the pharmological treatments of OA?
Oral analgesia - paracetamol, NSAIDs
Topical - NSAIDs, capsaicin
When do you refer a patient with OA for surgery?
Substantial impact on QOL
What are the differentials for a knee injury?
Fracture Acute/chornic degnerative joint disease Meniscal injury Ligament injury Tendon injury
What are the important questions in a knee history?
Sport/recreation? Or whilst resting/at work?
Activity at the time - jumping? Sports tackle
Energy at time of impact - how fast/heavy?
Chronology - was it quick or slow onset
For swelling, quick onset means blood
Any previous injuries in same spot?
Pop/crack heard?
What are the characteristics of a meniscal injury?
Often caused by a twisting movement on a loaded fixed knee
Results in painful squelch
Slow to swell (quicker in young though)
Painful to bear weight
Can result in locked knee - unable for even physician to move
What are the characteristics of an ACL tear?
Caused by forward momentum against a fixed leg with or without rotation
Loud pop heard at time
Quick to swell
Able to bear weight
What are the characteristics of collateral tears?
Lateralised pain
Feel of crack with sharp pain
No or minimal effusion
Bruising localised to one side
What are the important things to look for in a knee examination?
scars, brusing, swelling
Joint line irregularities
What are the important things to feel for in a knee examination
Effusion Crepitus Heat Tenderness Tissue lumps/defects
What are the important movements in a knee examination?
Passive/active
Straight leg raise
Range of movement
Ligament + dyanmic testing
What are the indications for knee surgery?
Failure of conservative treatment Demands of work/sport Problems with daily activities Prevention of further joint injury Prevention of falls
What are the non-surgical managements for acute knee injuries?
Restoration of function
Physio
Analgesia
Swelling reduction
What are the surgeries available for a meniscal tear?
Meniscal repair
Partial menisectomy
Meniscal transplant
What are the zones in a meniscus, what is their significance?
Red to white, with red/white inbetween
Indicates the vascularity of the meniscus (more vascular on lateral side)
Indicates how well it will heal
And thus how successful surgery would be
Who is eligible for meniscal surgery?
Young or sporty
Fresh tears - less than 3 months
Health meniscus with damage in red or red/white zone, NOT in white zone
What is the treatment for anterior cruciate ligament issues?
Rehab or reconstruction
When is reconstruction indicated?
Prevention of further injury
Helping to get back to work/sport
To prevent osteoarthritis
What is osteomyelitis?
Infection in the bone
What is septic arthritis?
Infection in the joint
Who is most likely to get acute osteomyelitis?
Children, boys more than girls
Often with history of minor trauma
Associated with diabetes, immunocompromised/steroids, rheumatic arthritis, sickle cell
What are the types of osteomyelitis?
Acute
Chronic
Can be specific or non-specific causation
Who is affected by acute osteomyelitis?
Mostly children, favouring boys with history of trauma (minor trauma)
Assocaited with diabetes,
Rheumatic arthritis,
steroid/immune compromised,
sickle cell
How is acute osteomyelitis spread?
Haematogenous spread in children/elderly
Local spread from contiguous site of infection (open fracture, joint replacement etc)
Secondary to vascular insufficiency
What are the sources of infection in acute osteomyeltits?
Infants - infected umbilical cord
Children - boils, tonsilitis, skin abraisons
Adults - UTI, arterial line
What are the most likely organisms in an infant for acute osteomyelitis?
Staph A
Group B streptococci
E coli
What are the most likely organisms to cause acute osteomyelitis in older children?
Staph A
Strep pyogenes
Haemophilus influenzae
What are the most likely organisms to cause acute osteomyelitis in adults?
Staph A
Coagulase-negative staphylococci (prostheses)
Propionibacterium (prostheses)
Streptococcus pyogenes (infective arthritis)
Mycobacterium tuberculosis
Pseudomonas aerginosa (especially in penetrating foot injury)
What other organisms can sometimes cause acute osteomyeltits?
Brucella in butchers Mycobacterium marinum in fishermen/filliters Proteus mirabilis Candida in immunocompromised Diabettic foot - mixed anaerobes Vertebral osteomyelitis - S. Aureus, TB Sickle cell - salmonella STD - gonococcus
What bones are likely to be affected?
Distal femur Proximal tibia Proximal humerus Hip Elbow (radial head)
What are the clinical features in an infant with acute osteomyeltits?
Minimal signs or may be very ill Fail to thrive Possible drowsiness /irritation Metaphyseal tenderness/swelling Positional change Decreased range of movement
Most common around knee
What is the pathology of acute osteomyelitis?
Trauma causes acute inflammation and vascular stasis
Pus forms and bone reformation occurs
If infection gets into bone whilst reforming granulation tissue walls off diseased bone tissue
Bacterial proliferation resultsin further destruction + potential abscess formation
What are the clinical features of acute osteomyeltis in a child?
Severe pain Reluctant to move (non weight bearing, neighboring joints flexed) May be tender fever + tachycardia Malaise Toxaemia
What are the clinical features of osteomyelitis in an adult? (primary)
Backache (most primary OM seen in thoracolumbar spine) History of UTI/urological procedure Elderly Diabetic Immunocompromised
What are the clinical features of osteomyelitis in an adult (secondary)?
More common
Often after open fracture
Mixed organisms
How do you blood tests are used to diagnose acute osteomeylitis?
History + clinical exam (pulse+temp) FBC + diffuse WBC ESR +CRP (inflamm markers) 3 blood cultures U&Es
What are the differentials for acute osteomyelitis?
Acute septic arthritis Trauma (fracture, dislocation etc) Acute inflammatory arthritis Transient synovitis Soft tissue infection (cellulitis, necrotising fasciitis, gas gangrene, txic shock syndrome)
What are the rare differentials for acute osteomyelitis?
Sickle cell crisis
Gaunchers disease
Rheumatic fever
Haemophillia
What investigations are used to diagnose acute osteomyelitis?
X-Ray US Aspiration Isotope bone scan Labelled white cell scan MRI
What is shown on an x-ray in acute osteomyelitis?
Normal for first 10-14 days
Then shows late metaphysial destruction
Latermedullay changes
Later, osteoneceosis and ner periosteal bone
What is the process for microbial identification in acute osteomyleitis?
Blood cultures in haemataogenous OM and septic arthritis
Bone biopsy
Tissue/swabs from 5 sites around implant in prosthetic infection
How do you treat acute osteomyelitis?
Rest + splintage Supportive for pain + dehydration Antibiotics IV for first week, oral thereafter 4-6wks - treat before results empirically
What are the indications for surgery in acute osteomyeltis ?
Aspiration of pus
Abscess drainage
Debridement of dead/infected tissue
Infected joint replacements
What are the complications of acute osteomyelitis?
Sepitcemia
Death
Metastatic infection Pathological fracture Septic arthritis Altered boine growth Chronic osteomyelitis
What is subacute osteomyelitis?
osteomyelitis where the host has resistance
Bacteria has lower virulance
Or use of antibiotics
Prolonged by lessened symptoms
What are the clinical features of subacute osteomyelitis?
long history (weeks-months) Variable symptoms Pain, limp Local swelling/warmth Tenderness
What are the differentials of subacute osteomyelitis?
Ewings sarcoma
Osteoid oseoma
TB
What is brodie’s abscess?
An abcess that forms in Subacute osteomyelitis
Painful limb with no systemic features
Older children
What is seen in X-ray of brodie’s abcess?
Luency in long bone metaphysis
What are the differntials of brodie’s abscess?
Ewings sarcoma
What is the treatment of brodie’s abcess?
Curettage surgery
What are the investigations in subacute osteomyelitis?
X-ray
Bone scan
Biopsy
How do you treat subacute osteomyelitis?
Prolonged course of antibiotics
Surgery - curettage
What leads to chornic osteomyelitis
May follow acute osteomyelitis
May start de novo
Either after operation or open fracture
Or in immunocomprmised patients - immunosuppressed, diabetics, elderly, drug abusers
Repeated breakdown of healed wounds can contribute
What are teh causative organisms of chronic osteomyelitis?
Often mixed Normally same organism for each flareup Staph A E coli Strep pyogenes Proteus
What is chronic osteomyelitis?
Chrnoically discharging sinus attached to underlying bone
Contains dead bone tissue due to infection (sequestrum)
Surrounded by granulation tissue and layer of new bone growth
What is the pathology of chronic osteomyelitis?
Due to insult cavity occurs which becomes infected
Dead bone leads to abcess + forming of new bone
Picture of chornic inflammation
How do you treat chronic osteomyelitis?
Long term antibiotics Erradicate bone infection (multiple surgeries) Treat soft tissue problems Correct deformity if present Reconstruction? Amputation?
What are the complications of chronic osteomyelitis?
Chronically discharging sinus + flare ups Ongoing infection Patolgical fractures Growth distubrance Squamous cell carcinoma (0/07%)
What is the route of infection in acute septic arthritis?
Direct invasion (pentrating wound, intra-articular injury)
Eruption of bone abscess
Haematogenous
What are the common caustative agents of acute septic arthritis?
Staph A
H. influenzae
Strep pyogenes
Ecoli
What is the pathology of acute septic arthritis?
Acute synovitis with purulent joint effusion
Articular cartilage attacked by bacterial toxin/cellular enzyme
Complete destruction of articular cartilage
What are the possible outcomes (sqeulae) of acute septic arthritis?
Complete recover
Partial loss of articular cartilage –> OA
Fibrous or bony ankylosis
What is the clinical picture in a neonate with acute septic arthritis?
Irritability
Resitant to movement
Ill
What is the clinical picture in a child with acute septic arthritis?
Acute pain in single large joint
Reluctant to move joint (any movment)
Increased temp + pulse
Increased tenderness
What is the clinical picture of an adult with acute septic arthritis?
Often superficial joint
Rare in healthy adult
Most common after joint replacement
How do you investigate acute septic arthritis?
FBC, WBC, ESR, CRP, blood culture
X-ray
US
Aspiration
How rare is an infected joint replacement?
1.1-5% However deadly (staph A)
What are the differential diagnoses of acute septic arthritis?
Acute osteomyelitis Trauma Irritabile joint Haemophilia Rheumatic fever Gout Gauchers disease
How do you treat acute septic arthritis?
General supportive measures
Antibiotics for 3-4 weeks
Surgical drainage in ermgency (ie pus)
What are the three types of TB joint infections?
Extra-articular (epipihyseal/haemodynamic marrow)
Intra-articular (large joints)
Vertebral body
How many patients have multiple TB bone infection lesions?
1/3
What are the clinical features of TB bone/joint infections?
Insidious onset History of TB contact Pain (night!) swelling, weight loss Joint swelling Decreased range of movenet Ankylosis Deformity
What is the pathology of TB bone/joint infections?
Primarily in lung
This spreads, sometimes to bones
Forms tuberculos granuloma - early (vascular ) and chronic (avascular)
Chronic develops obliterative endarteritis so difficult to treat with antibiotics
How do you diagnose TB joint/bone infection?
Long history with single joint involvement
Marked thickening of synovium
Marked muscle wastage
Periarticular osteoporosis
How do you investigate TB joint/bone infection?
FBC, ESR Mantoux test Sputum/urine culture Xray Joint aspiration and biopsy
What does the bone x-ray show in joint/bone TB infection?
Soft tissue swelling
Periarticular ostepaenia
Articular space narrowing
What tests are done on aspirated fluid in a TB joint/bone infection?
AAFB (10-20% ID rate)
Culture (50% positive)
What are the differentials of TB joint infection?
Transient synovitis
Monoarticular RA
Haemorrhagic arthritis
Pyogenic arthritis
What is the treatment regime in TB joint/bone infection? (note, differs from usual)
8 weeks
Rifampicin
Isoniazid
Ethambutol
Then 6-12 months
Rifampicin
Isoniazid
Rest + splintage
