What is the histology of OA?
• Cartilage degradation /proteoglycan loss
• Surface fibrillation
• Chondrocyte clustering and apoptosis
• Hyperplasia of synovium
Why does articular cartilage have limited capacity for self-repair?
• Slow diffusion of nutrients from synovial fluid.
What is a focal cartilage lesion?
Damage to cartilage from trauma or repetitive strain.
They can either be Chondral or Osteochondral.
What is a focal chondral lesion?
A lesion that lies entirely within the cartilage, do not repair spontaneously.
What is a focal osteochondral lesion?
These are lesions that penetrate through some subchondral bone - some spontaneous healing as it is vascular, osteoprogenitor cells invade the lesion.
What are the different classifications of cartilage defects?
• Grade I - Some fissures extending into superficial cartilage.
• Grade II - Multiple fissures extending half-depth into the cartilage.
• Grade III - Fissures extending down to subchondral bone.
• Grade IV - Complete loss of cartilage and exposure of subchondral bone.
What are the current repair strategies for intermediate/small localised cartilage defects?
• Osteochondral grafting
• Cell-based therapies
Cartilage repair techniques: Debridement.
• This is a palliative procedure which envolves shaving off the frayed edges of cartilage.
• Aims to reduce friction and inflammation to improve pain and swelling.
Cartilage repair techniques: Microfracture.
A repairative technique, which drills small holes in the subchondrol bone with a arthroscope, this causes bleeding and initiates healing.
• Does not last long, and additional surgery will be required.
Cartilage repair techniques: Osteotomy.
• This involves removing a wedge shaped bone in order to restore load-distribution and gait.
• Edges of cut-bone are held together with nails.
• Long recovery process, does not repair.
Cartilage repair techniques: Osteochondral grafting.
• Regenerative procedure.
• Healthy cartilage is removed from a location either self or donor and is then drilled into the site, which then multiplies to repair.
Cartilage repair techniques: Autologous chondrocyte implantation. (ACI)
• This is a regenerative technique where healthy tissue is removed and sent to a lab where it undergoes processing for clonal expansion.
• These are then injecting into the site and covered with a peiosteal patch which is sealed with fibrinogen and thombin.
• This treatment is for injury from trauma or repetive action, it is not useful in OA.
Cartilage repair techniques: Matrix-induced autologous chondrocyte implantation (MACI).
• This is an adaptation of ACI, where the chondrocytes are attached to a membrane which is directly implanted into the defect. A periosteal patch is not needed.
• Surgery time is reduced.
What is septic arthritis?
This is acute inflammation of the joint due to direct infection.
Most frequently bacterial.
How does septic arthritis tend to present?
What are some of the predisposing factors for septic arthritis?
• Prosthetic joint
• Immunosupression / elderly / diabetes
• Rheumatoid arthritis
• Exisiting joint damage
• IV drug abuse
What is the outcome of septic arthritis if left untreated?
• Rapid destruction of joint
• Sinus/abcess formation
• Multiple organ failure
What is the morbidity of septic arthritis when treated?
What investigations should be performed for a suspected septic arthritis?
• Blood- FBC, U&Es, LFT, Culture, Urate etc..
• Aspirate joint fluid (NOT prosthetic joint)
How should antibiotics be given for septic arthritis?
2 weeks IV, 4 weeks oral.
What is gout?
A clinical syndrome caused by an inflammatory response to monosodium urate monohydrate crystals which may form in people with hyperuricaemia.
What is the type of crystal largely responsible for gout?
Monosodium urate monohydrate crystals.
What essentially causes gout?
Overproduction/ underexcretion of urate.
Overproduction: Due to a purine-rich diet or increased synthesis of purines.
Under-excretion: 90% of gout due to under-secretion, mainly sue to renal impairment.
What are the non-modifiable risk factors for gout?
• Age - 40-50 males, >60 females
• Gender: Male
• Genetic factors
• Impaired renal function
What are the modifiable risk factors for gout?
• High-purine diet
• Alcohol consumption
What is the clinical presentation of gout?
• Acute, relapsing, self-limiting, severe inflammatory arthritis.
• Exquisite pain, swelling and erythema.
• >50% of 1st attacks occur in the 1st MTP.
What % of acute attacks of gout occur mono-articularly?
What are tophi?
These are hard swellings of monosodium urate monohydrate crystals, responsible for the most disability during chronic gout.
What investigations should be performed for Gout?
• Joint fluid examination - presence of urate crystals.
• Bloods, urinanlysis.
What are the treatment aims for gout?
• To treat acute attacks early and effectively.
• Manage hyperuricaemia, to prevent build up of urate crystals.
What is the medical treatment for an acute attack of gout?
• Oral and intra-articular steroids.
What are some of the Urate-lowering drugs that can be used to treat chronic gout?
• Xathine oxidase inhibitors
- Reduces production of uric acid.
• Uricosuric agents
- Increases secretion of uric acid.
- Sulphinpyrazone - Used in normal renal function.
- Benbromarone - Can be used in renal impairment.
Explain the initiation of Urate-lowering therapy.
• Should not be started during an acute attack.
• It should be started at a low dose and titrated up.
• It may cause an acute attack as urate crystals are mobilised.
• Patients should recieve anti-inflammatory prophylaxis during the first few months of treatment.
What is psuedogout?
This is similar to gout but is due to Calcium pyrophosphate crystals instead.
Attacks can last much longer and there is no specific treatment.
What conditions are associated with pseudogout?
Hyperparathyroidism, osteoarthritis, haemochromatosis, diabetes, acromegaly.