MUSCOSKELETAL Flashcards
What are the 2 types of bone at a macro level?
Cortical:
* Compact
* Dense, solid
* Only spaces are for cells and blood vessels
Trabecular:
* Cancellous (spongy)
* Network of bony struts (TRABECULAE)
* Looks like sponge, many holes filled with bone marrow
* Cells reside in trabeculae and blood vessels in holes
What do the minerals and collagen provide to bone respectively?
Minerals - Stiffness
Collagen - Elasticity
Define Osteoarthritis
A non-inflammatory degenerative joint disorder characterised by joint pain and functional limitation.
It commonly affects the synovial joints
Disease of bone and joint cartilage
“wear and tear of the joints”
What is the epidemiology of OA?
One of the leading causes of disability world wide.
Affects 8.5 million people in the UK
More common in women
MOST COMMON type of arthritis
What are some risk factors for Osteoarthritis?
Genetics
Increasing Age - strongest RF
Female - Hip OA 2x more common
High bone density - protective against osteoporosis but RF for OA
Excessive stress for exercise or certain occupations
What gene is related to an increased risk of osteoarthritis?
COL2A1- collagen type 2 gene
What is the pathophysiology of OA?
It appears inflammatory cytokines interrupt normal repair of cartilage damage.
(IL-1) (TNF-alpha) stimulate metalloproteinase production which degrade the collagen and proteoglycans, and inhibits collagen production
As cartilage is lost, the joint space narrows. Bone on bone interaction may occur, leads to stress and over time subchondral sclerosis (via a process called eburnation) seen on x-ray.
Essentially, cartilage is lost and chondroblasts are unable to replace and repair the lost cartilage, this leads to abnormal bone repair.
What happens in a joint affected by osteoarthritis?
Chondrocytes switch from making type 2 collagen to type 1 collagen - leading to Decreased Elasticity
Cartilage flakes into synovial space - joint mice which attracts macrophages and lymphocytes
Subsequent inflammation of articular structures at joint margins called osteophytes - leading to nodes
What are the symptoms of OA?
Joint pain - exacerbated by movement and relieved by rest
Worse as the day goes on
Joint Stiffness
Swelling
OFTEN ASSYMETIRCAL
Joint Locking - inability to straighten joints
What are the clinical signs of OA?
Hands:
Bouchard’s Nodes
Heberden’s Nodes
Thenar Muscle wasting
First CMC Joint affected most
Weak grip
Knees:
Crepitus
Hips:
Antalgic gait
Restricted internal rotation
All affected Joints:
Joint tenderness
What is Heberden’s and Bouchard’s Nodes?
Bouchard’s - Bony swelling at PIP - (tom has this on his deformed finger)
Heberden’s Bony swelling at the DIP
Remember B before H and proximal before distal
What joints are the most commonly affected in OA?
Knees
Hips
Sacro-ileac joints
Cervical spine
Wrist
base of thumb (carpometacarpal)
finger joints (interphalangeal)
What is Crepitus?
Crackling or grating sensation when moving a joint
What is a common differential diagnosis to OA?
Rheumatoid arthritis
This differs from RA due to the absence of systemic features and the pattern of joint involvement.
What are the primary investigations to diagnose OA?
Joint X rays show OA hallmarks: LOSS:
Loss of Joint space
Osteophytes
Subarticular Sclerosis
Subchondral Cysts
What other investigations may be done in OA? (ruling out other diseases)
Bloods - normal in OA
ESR/CRP - inflammatory markers to distinguish between RA or Gout
Negative anti-nuclear antibodies
How can a diagnosis of osteoarthritis be made?
If someone is over 45 and has typical activity related pain with no morning stiffness or stiffness lasting less than 30 minuets
What is the non pharmological management of OA?
Weight loss if overweight to reduce the load on the joint
Physiotherapy to improve strength and function
Occupational therapy to support activities and function
improved diet
anti-inflammatory foods (basically less processed foods: fewer ingredients = less
processed),
Orthotics to support activities and function (e.g., knee braces)
What medical treatments can be used in OA?
Analgesics to control pain and Sx:
1st. Oral paracetamol / topical NSAIDs
2nd. Add oral NSAIDs
3rd . Consider Opiates - Codeine
If these fail:
Inter-articular steroid injections
Joint replacement
When should oral NSAIDs be used with caution for OA?
In an older patient who may be on anticoagulants such as aspirin/DOACs
There may be some drug interactions/side effects using both Tx
Outline what ESR is.
ESR (erythrocyte sedimentation rate)
Rises with inflammation/infection
Increased fibrinogen makes RBCs “stick together” and therefore fall faster
Therefore, if ESR rises, the rate of fall is faster
ESR rises and falls slowly (days to weeks)
Outline what makes up a synovial joint
Bones are covered by articular cartilage. Synovial joints also have a fibrous joint capsule that links them, continuous with the periosteum of the bone
this is lined by synovial membrane which produces synovial fluid. This lubricates the joint as well as clearing debris.
There are also blood vessels and lymphatics attached to the synovial membrane.
Define what rheumatoid arthritis is
Chronic systemic inflammatory disease due to deposition of immune complexes in synovial joints which causes symmetrical, deforming polyarthritis
Can progress to involve larger joint and other organs such as the skin and lungs
Explain why CRP levels are raised in someone with inflammatory joint pain.
Inflammation leads to increased levels of IL-6. CRP is produced by the liver in response to IL-6 and therefore is raised.