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