Bone + Joint Disorders PT2 Flashcards
Osteomalacia and Rickett's, Avascular Necrosis, Prosthetic Joint Infection
What is osteomalacia?
Defect of bone characterised by abnormal softening due to deficient mineralisation of osteoid, caused by inadequate calcium and phosphorus
What is the pediatric equivalent of osteomalacia?
Rickets
What are the principal causes of osteomalacia and rickets?
- Vitamin D deficiency
- Hypophosphatemia
- Impaired calcium absorption
- Phosphate deficiency
What is the clinical presentation of osteomalacia?
Symptoms
(1) Bone pain (pelvis, spine, femora)
(2) Hypocalcemia symptoms
(eg) cramps, irritability
(3) Easy fractures.
Signs
(1) Proximal myopathy
(2) Dental defects
What is the clinical presentation of rickets?
- Delayed fontanel closure
- Gen varum (bowing of the legs)
What are the typical lab findings in osteomalacia?
(1) Low calcium
(2) Low serum phosphate
(3) Raised serum alkaline phosphatase (ALP)
(4) Raised PTH
What is the first-line treatment for osteomalacia?
Vitamin D therapy + Calcium and phosphate supplementation.
D3 tablets (400-800 IU per day) after a loading dose of 3200 IU per day for 12 weeks are commonly used
How would you manage severe osteomalacia?
A vitamin D level of less than 25 nmol/L reflects deficiency and requires high-dose treatment initially followed by maintenance treatment
Vitamin D deficiency leads to inadequate stores of [Blank] and [Blank] in the bone matrix
Calcium and Phosphate
In osteomalacia, bones have a greater proportion of [Blank] bone matrix
Unmineralised
What are the symptoms and signs of rickets?
Bowed legs
Bone pain
Stunted growth
Darker skin tones [Blank] your risk of rickets
Increase
Rickets is a skeletal disorder caused by a prolonged lack of [Blank]
Vitamin D
A 6-year-old patient presents with bone pain, weakness and constipation. A diagnosis of rickets is suspected
What findings would be seen on X-ray?
bowed femurs and widened epiphyseal plates
A four-year-old boy presents to his GP with his mother after concerns he is not growing as he should. On examination, the boy has a patent anterior fontanelle, and a prominent forehead. He has enlarged wrists and ankles, and he is bow-legged. He does not yet have all his teeth. He was predominantly breastfed until he was two years old
What is the most likely cause of his condition?
Poor nutrition
What is avascular necrosis (AVN)?
Failure of blood supply to a bone’s end, causing ischaemic necrosis
Typical demographic for AVN?
Males, ages 35-50
Most commonly affected bone in AVN?
The femoral head, but can also affect the wrist, humerus head
What is the “hanging rope sign” in AVN?
Later MRI sign of femoral head AVN with patchy sclerosis and a lytic zone from granulation tissue
Typical presentation of femoral head AVN?
(1) Insidious groin pain → worsened by stairs or impact; often bilateral
First-line imaging for AVN diagnosis?
MRI
Key management options if AVN is reversible?
- Bisphosphonates,
- Core decompression
- Bone grafting
- Vascularised fibular graft
Which region of bone is usually affected by avascular necrosis?
The epiphysis of long bones
What is typically required for irreversible AVN?
Joint replacement (e.g., total hip replacement)
Rotational osteotomy (rare)
Fusion (in wrist/foot)
What is the Steinberg classification used for?
It categorises stages of AVN, aiding in treatment decisions based on progression
What part of the scaphoid is most prone to avascular necrosis?
The proximal pole
A 21-year-old falls onto his outstretched hand while playing rugby
On examination, there is bruising around the wrist and pain in the anatomical snuffbox. Imaging shows no obvious fracture and he is sent home with pain relief.
On a follow-up appointment three weeks later in the orthopaedic clinic, he complained of ongoing pain and stiffness in the wrist. What is the diagnosis?
Avascular necrosis
What are risk factors for fat necrosis of the breast?
Trauma or surgery
A 38-year-old female presents to her GP with a two-week history of increasing pain in both of her hips. She denies any recent falls and does not recall any trauma. She has a medical history of systemic lupus erythematosus for 15 years and is taking prednisolone and hydroxychloroquine for it.
She can weight-bear with pain. She is apyrexic with normal observations. Hip examination shows tenderness and a restricted range of movement of the hip bilaterally
What is the most likely diagnosis and why?
Avascular necrosis of the femoral heads
= Steroid use is one of the common nontraumatic cause of avascular necrosis
Long-term corticosteroid use is a risk factor for what disease?
Avascular necrosis
Which organisms most commonly cause periprosthetic infections?
Staph. aureus and Staph. epidermidis
What is Prosthetic Joint Infection?
Periprosthetic infection involving the joint prosthesis and adjacent tissue
Describe the mechanism of periprosthetic joint infection
Infection can occur from direct inoculation during surgery, joint manipulation, or later through bacteraemia
Differentiate between early, chronic, and haematogenous periprosthetic infections
Early: Within 2-3 weeks, from surgery;
Chronic: After 3+ weeks
Haematogenous: Abrupt onset, systemically unwell
What causative organisms are found in chronic periprosthetic infections?
S. epidermis
cutibacterium
corynebacterium
S. aureus
What causative organisms are found in haematogenous periprosthetic infections?
S. aureus
GNB
What causative organisms are found in early periprosthetic infections?
(1) Staph. aureus
(2) S. epidermis
What are the common symptoms of periprosthetic infection?
(1) Fever
(2) Joint pain
(3) Minimal swelling
(4) Sometimes sinuses
What does Planktonic bacteria mean?
Is responsible for most symptoms, bacteraemia
What does sessile bacteria mean?
phenotypic transformation of planktonic bacteria to form a biofilm encased in an extracellular matrix
General advice for those with prosthetic Joint Infection
If there is pus, let it out!
What is the primary treatment approach for early or haematogenous infection?
- DAIR - Debridement
= Antibiotics (for 12 weeks) - Implant retention
Frail patients with chronic infection - Stage 1 exchange management
(1) Removal of joint and antibiotics
Chronic infection - Stage 2 exchange management
(1) Removal of joint and 6 weeks of aggressive antibiotic therapy
(2) Patient left without a joint for 6 weeks
(3) Once the infection is under control a revision joint replacement is performed with more complex joint replacement components
A 60-year-old man describes difficulty in standing from the seated position and diffuse joint and bone pain. Other than a recent fracture sustained from a mechanical fall he has no other past medical history and denies any systemic signs of illness. On examination, he has a waddling gait.
What is the most likely diagnosis?
Osteomalacia
What is a significant risk factor for avascular necrosis?
Previous chemotherapy
Steroid use
alcohol excess + trauma
A 67-year-old woman who is taking long-term prednisolone for polymyalgia rheumatica presents with progressive pain in her right hip joint. On examination, movement is painful in all directions but there is no evidence of limb shortening or external rotation.
An x-ray of the hip shows osteopenia and microfractures.
What is the most likely diagnosis?
Avascular necrosis of the femoral head
What are the plain X-ray findings seen in avascular necrosis of the hip?
- osteopenia and microfractures may be seen early on
- collapse of the articular surface may result in the crescent sign
Bone pain, tenderness and proximal myopathy (→ waddling gait) = ?
osteomalacia
