Common conditions Flashcards
OA, RA, Gout, Osteoporosis and other metabolic conditions
X ray presentation of OA
LOSS
- Loss of joint space
- Osteophytes (marginal)
- Subchondral cyst
- Subchondral sclerosis
Grading of OA chondral damage
Outerbridge classification
0: normal cartilage
1: cartilage softening and swelling
2: partial thickness defects with fissures on surface
3: fissuring to level of subchondral bone
4: exposed subchondral bone
Causes of OA
Primary - idiopathic - senile (degen) - post meno Secondary (VITAMINCD) - Vascular - Infective: syphillis - Trauma - Autoimmune: RA - Metabolic: hyperPTH, crystal - Inflammatory, iatrogenic' - Neoplastic - Congenital - Degenerative
What causes pain in OA
vascular congestion of subarticular bone
capsular fibrosis
muscular fatigue
(cartilage and synovium have no nerve supply)
DVT prevention
1) pre-operative: thromboembolic deterrent (TED) stockings
2) peri-operative: TED stockings, compression boots and foot pumps (eg. pneumatic intermittent compression devices), minimize length of surgery
3) post-operative: low dose LMW heparin, early mobilization (physio)
Conservative mgx of OA
Non pharm
- lifestyle: weight loss, exercise, avoid kneeling/ squatting
- physio: strengthen muscles
- occupational therapy: load reduction with walking stick, soft soled shoes
Pharm
- analgesia: paracetamol, NSAIDs w PPI
- Glucosamine
- Intraarticular H&L or hyaluronic acid viscosupplmentation
Sx indications and options for OA
Indications
- v symptomatic (instability, pain, deformity, disability)
- failure of conserv tx
- can tolerate sx
Types
- arthroscopic debridement and wash out with cartilage regeneration procedures
- realignment osteotomy (younger)
- arthrodesis
- arthroplasty (lasts 15yrs): unicompartmental vs total
Post sx: physio + continuous passive movement (CPM)
Complications of joint replacement surgery (arthroplasty)
Intraop:
- # e.g. acetabulum in THR
- neuromuscular injuries: peroneal in TKR, sciatic n in HR
- GA cx: AMI, stroke
- blood loss
within 24h: dislocation
Early (within 30d)
- infection
- fat embolism
- DVT/ PE
Late (after 30d) - infection - heterotopic ossification - disuse osteoporosis - tissue atrophy - limb length discrepancy (THR) implant failure - periprosthetic fractures - loosening of joint - disruption of extensor mechanism - wearing of articular surfaces
RF of OA knees
- > 50yo
- overweight
- hereditary
- competitive contact sports, meniscal injuries
- deformities (genu valgus/ varum)
- previous injuries
Types of OA knees
Medial tibiofemoral compartment OA (TFOA): joint line tenderness and Patellofemoral OA (PFOA): patella medial or lateral facet tenderness
4 x ray views of knee
- weight bearing AP view
- skyline view
- lateral
- long film
Mechanical vs anatomical axis of knee
Mechanical: centre of hip to centre of ankle
Anatomical: line of femur to line of tibia
Mgx of infected implant
Removal of implant, plus 6 weeks IV antibiotics
Reimplantation after Abx completed
what is Kienbock disease
AVN of lunate
OA hand changes
Herbeden nodes (DIPJ) Bouchard nodes (PIPJ) ulnar dev of fingers CMCJ (trapezio-MC jt) of thumb: bony thickening and adduction > squaring (+ve grind test) Mallet deformity (DIPJ)
Definition of osteoporosis
- what is T score
- what is Z score
Normal mineralisation (quality normal) but quantity deficient (decr bone mass per unit volume)
Bone mineral density > 2.5 SD below the mean seen in peak bone mass of young (25-30) normal subjects
(T-score ≤ -2.5SD)
T score: Number of sds below means of peak bone mass of young healthy adults (based on BMD of 25yo Caucasian females)
Z score: Number of standard deviations below average person of the same age
What is Wolff’s law
Bone is deposited and resorbed in accordance with the stresses placed upon it.
Interpretation of BMD T score
Normal: >-1
Osteopenia: -1 to -2.5
Osteoporosis:
RF of osteoporosis
Non modifiable
- family hx
- hx of anorexia, amenorrhea
- low peak bone mass in early adulthood
- early menopause/ oophorectomy
- previous # history
Modifiable
- dietary insufficiency
- alcohol, cigarette
- chronic lack of exercise
- drugs: steroids, thyroxine
- low calcium
- comorbids: hyperthyroid, hyperPTH, cushing, liver dz, CRF
- lean people
Screening guidelines for osteoporosis
- when to screen?
- frequency?
- investigations
- action
BMD for women > 65
or <65 with RF
osteoporosis self assessment tool for asians (OSTA): age-weight x>20: measure BMD x 0-20: measure if with RF x+1: recheck BMD in 5 years 1 to -1: recheck in 2y -1 to -2.5: osteopenia - prevention
method: dual energy x ray absorptiometry (DEXA)
- hip for diagnosis
- spine for monitoring of tx
Tx for osteoporosis
Life style
- good nutrition
- exercise
- stop smoking, alcohol
- prevent falls
Pharm
- calcium and vit D supplements
- bisphosphonates
- HRT
- calcitonin
- strontium ranelate
- intermittent PTH
- SERM
- tibolone
Bisphosphonates
- examples
- MOA
- SE
- advice
e.g. alendronate (fosamax), residronate
MOA: Potent inhibitors of osteoclasts, osteoclasts undergo apoptosis when they ingest it
SE: GIT (gastritis, ulceration, stricture, diarrhea, vomiting), esophageal rxn (eg. heartburn)
osteonecrosis of jaw (rare), dizziness, hypersensitivity.
Overuse will result in SSBT (severe suppression of bone turnover): bone would hence be brittle
advice:
Take medication sitting up, keep upright for 30min after swallowing, weekly dosing.
consider drug holiday in low risk pt after 3-5yrs
Strontium ranelate
- MOA
- SE
MOA: Decreases bone resorption and stimulates bone formation
SE: Venous thromboembolism, contraindicated in patients with severe renal impairment
X ray features of gout
Asymmetric polyarthropathy Periarticular erosions Sclerotic margins soft tissue calcifications (tophi) overhanding bony edges
X ray features of psoriatic arthritis
bilateral involvement
pencil in cup deformity
Types of gout
Primary: idiopathic disorder of nucleic acid metabolism that leads to hyperuricemia and deposition of monosodium rate crystals in joint
Sec: dz with high metabolic turnover (psoriasis, haemolytic anemia, leukemia, chemotherapy)
Tx of gout
Acute - indomethacin (NSAID) - colchicine - glucocorticoid Chronic - allopurinol (xanthine oxidase inhibitor) - colchicine
Pseudogout
- what kind of crystals
- radiographic findings
- calcium pyrophosphate dehydrate (CPPD) crystals
- weakly positively birefringent rhomboid shaped crystals
x ray:
- calcification of fibrocartilage structures
(TFCC in wrist, meniscus in knee)
Associations of pseudogout
hemochromatosis wilson hyperparathyroidism SLE gout RA hemophilia long term hemodialysis
Mgx of pseudogout
Acute - nsaids - splint - intraarticular steroids Chronic - intraarticular y90 injections - colchicine
Rickets and osteomalacia
- causes
- features
Causes:
- calcium deficiency
- hypophosphatemia
- defect along vit D metabolism pathway (nutritional lack, lack of sunlight, intestinal malabsorption)
Features: ADULT
- acetabuli protrusio
- depressed bone density
- under mineralization of osteoid
- looser zone (pseudo#)
- triradiate pelvis
Causes of hyperPTH
Primary: solitary adenoma Secondary: PTH over secretion in response to chronic hypocalcemia - kidney failure (phos high) - calcium deficiency - impaired phosphate breakdown - vit D disorders - absorption problems (phosphate low)
Tertiary: secondary hyperplasia leading to autonomous activity
bone changes from hyperPTH
- osteoporosis
- osteitis fibrosa cystica: replacement of marrow spaces by vascular granulation and fibrous tissue
- brown tumour: from excessive osteoclast activity (fibrous tissue, woven bone, vasculature)
pathognomonic feature of Pri hyperPTH on x ray
subperiosteal cortical resorption of middle phalange
