Loco PBL 3: Osteoarthritis and Perthes Disease Flashcards
What is Perthes disease?
Where blood supply the head of the femur (epiphysis) because inadequate leading to avascular necrosis of the femoral head (usually due to insufficiency of the acetabular branch of the obturator artery)
What are the signs/symptoms of Perthes disease?
Hip/groin/knee pain, muscle wasting of upper thigh and shortening of the leg with hip stiffness
What are the four stages of Perthes disease?
> Necrosis
Fragmentation (resorption of bone)
Re-ossification (deposition of bone)
Remodelling
What is the pathophysiology of Perthes disease?
Avascular necrosis of the femoral head and over several months the blood vessels re-grow and revascularise the dead bone tissue leading to new bone growth and the moral head regrows and remodels over years
How is Perthes disease diagnosed from x-ray?
Flattened femoral head
How is Perthes disease treated?
Promote the healing process and provide good positioning for healing
What is the prognosis for Perthes disease?
Children <5 = good chance of full recovery
Children/adults >5 = less chance of full recovery without complications
What is osteoarthritis?
Degeneration of joint cartilage and the underlying bone, most common from middle age onward. It causes pain and stiffness, especially in the hip, knee, and thumb joints.
What are the signs and symptoms of osteoarthritis?
Joint pain with use, less than 30 minutes of morning stiffness, loss of function, crepitus, bony enlargements, joint deformity and muscle atrophy
What are the risk factors for osteoarthritis?
Use (obesity, exertion and labour), increasing age, being female, nutrition and previous joint damage alongside genetic factors (HMGB2)
What gene conveys an increased risk of developing osteoarthritis?
HMGB2 - this gene is expressed in the superficial zone of the cartilage and is used to support the chondrocytes and allow differentiation of osteoprogenitor cells. Therefore dysfunction of this one causes superficial zone death and a loss of progenitor cells (which can’t replace damaged tissue)
How may HMGB2 mutations lead to osteoarthritis?
This gene is expressed in the superficial zone of the cartilage and is used to support the chondrocytes and allow differentiation of osteoprogenitor cells. Therefore dysfunction of this one causes superficial zone death and a loss of progenitor cells (which can’t replace damaged tissue)
What are the two main types of cell that are found in articular cartilage synovium?
Type A (macrophage) and Type B (fibroblast)
Explain the pathophysiology of osteoarthritis
A factor leads to increased expression of degradative enzymes by chondrocytes, leading to necrosis of the cartilage and release of inflammatory mediators such as IL-1, IL-6 and TNF. The chondrocytes detect this damage and increase type II collagen production and decrease proteoglycan production leading to swelling and thickening of cartilage. Eventually the chondrocytes become ‘stressed out’ and change type II to type I collagen production leading to softer articular cartilage. Cartilage begins to crack and break off (fibrillation) into the joint space (joint mice) which are engulfed by Type A synoviocytes which attracts lymphocytes and neutrophils until eventually no articular cartilage will remain (eburnation) and the ends will rub which can cause microfractures of the subchondral bone.
Why is a second tidemark formed in osteoarthritis?
When the chondrocytes become exhausted and begin to produce type I instead of type II collagen
What are the three main phases of cartilage loss in osteoarthritis?
Fibrillation, erosion/cracking and eburnation
What are the common forms/affected sites of osteoarthritis?
Hip, hands, foot, knee and spine
What is spondylosis?
Osteoarthritis of the vertebra/spine
What are the findings for osteoarthritis on clinical examination?
Swelling, cracking, reduced range of movement, tenderness and fluid
What are the diagnostic features of osteoarthritis on x-ray?
Subchondral cysts, microfractures of the trabecular bone, joint-space narrowing, osteophytes and subchondral sclerosis
How may osteoarthritis be treated?
Conservative management (exercise, weight loss, TENS, orthopaedic insoles), pain relief, NSAIDs, intra-articular steroid injections or surgery
Outline how osteoarthritis may be managed conservatively
With non-weight bearing exercise, weight loss, TENS, orthopaedic insoles and walking sticks
How may topical capsaicin be used in the treatment of osteoarthritis?
It’s a chilli-pepper derivative which binds to TRPV1 receptors on nociceptors to stimulate C-fibres, and acts to counteract other pain
When is surgery considered for the treatment of osteoarthritis?
When the pain, stiffness or range of movement have a large impact on the patient’s quality of life and may be waking during the night due to the pain
How may osteoarthritis be treated surgically?
Arthroscopic lavage (plus debridement), microfracture, mosaicplasty, chondrocyte graft, joint replacement or viscosupplementation
Outline arthroscopic lavage in the treatment of osteoarthritis
Remove all of the loose bits in the joint capsule and smooth the surfaces
Outline micro fracture in the treatment of osteoarthritis
Involves drilling into the subchondral bone to stimulate the repair of the articular cartilage; this leads to the formation of fibrocartilage, which is weaker than hyaline cartilage
Outline mosaicplasty in the treatment of osteoarthritis
Involves an osteochondral transplant
Outline chondrocyte grafting in the treatment of osteoarthritis
Transplantation of chondrocytes from the rib costochondral process or a non damaged part of the joint
How long does a joint replacement usually last?
15-20 years
Outline viscosupplementation in the treatment of osteoarthritis
Hyaluronic acid is given to re-establish the lost elastic properties of the synovial fluid due to loss
What is pseudogout?
Where chalky deposits of calcium form in the cartilage (chondrocalcinosis). These deposits can shake loose from the cartilage and irritate the synovium causing the joint to become red, hot and swollen
How is pseudogout related to osteoarthritis?
It’s a common complication of OA.
How is the synovial fluid affected in osteoarthritis?
There is a lower concentration and a lower molecular weight of hyaluronic acid
What is nodal osteoarthritis?
Arthritis of the hands which effects middle-aged women predominantly
What is oxycodone?
Opioid medication
