Orthopaedics
Fracture Healing and Complications
Fracture healing and complications for MBBS and NEET-PG: stages of union, non-union, malunion, compartment syndrome, avascular necrosis and fat embolism, mapped to NMC codes OR2.15 and OR2.16.
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Fracture Healing and Complications
Fracture healing and complications for MBBS and NEET-PG: stages of union, non-union, malunion, compartment syndrome, avascular necrosis and fat embolism, mapped to NMC codes OR2.15 and OR2.16.
This chapter covers how fractures heal and what can go wrong. It works through the stages of bone healing, the difference between primary and secondary union, and the local and systemic complications, from compartment syndrome and avascular necrosis to non-union, malunion and fat embolism, that examiners and clinicians must recognise early.
High-yield: Fracture Healing and Complications
- Secondary bone healing passes through haematoma, inflammation, soft callus, hard callus and remodelling.
- Primary bone healing occurs under rigid fixation with compression and heals without visible callus.
- Delayed union is a fracture that takes longer than expected to unite, while non-union is a failure of union with no prospect of healing without intervention.
- An atrophic non-union has poor blood supply and needs bone grafting, whereas a hypertrophic non-union has abundant callus and reflects inadequate fixation.
- Malunion is healing in an unacceptable position, causing deformity, shortening or later osteoarthritis.
- Avascular necrosis commonly follows fractures of the femoral head, scaphoid and talus because of their tenuous blood supply.
- Compartment syndrome presents with pain out of proportion and pain on passive stretch, and it is treated by urgent fasciotomy.
- Volkmann ischaemic contracture is the late result of an untreated forearm compartment syndrome.
- Fat embolism syndrome follows long bone fractures with respiratory distress, cerebral signs and a petechial rash.
- Venous thromboembolism is an important risk after lower limb and pelvic fractures and after immobilisation.
- Complex regional pain syndrome causes persistent pain, swelling and trophic changes out of proportion to the injury.
- Myositis ossificans is heterotopic bone formation in muscle, classically around the elbow after injury or forceful manipulation.
- Growth arrest and limb length discrepancy can follow physeal injuries in children.
- Infection is the dominant late complication of open fractures and of internal fixation.
Complications to recognise early
- **Compartment syndrome:** Pain out of proportion and on passive stretch. Urgent fasciotomy. Pulselessness is late.
- **Non-union:** Atrophic (poor blood supply, needs graft) or hypertrophic (inadequate fixation).
- **Avascular necrosis:** Femoral head, scaphoid and talus, where the blood supply is precarious.
- **Fat embolism:** 24 to 72 hours after long bone fracture: breathlessness, confusion, petechiae.
NMC competencies in this chapter
- **OR2.15:** Complications of fractures: local and systemic
- **OR2.16:** Fracture healing, delayed union, non-union and malunion
Frequently Asked Questions
What is the difference between delayed union and non-union?
Delayed union is a fracture that is healing but is slower than expected. Non-union is a fracture that has stopped healing and will not unite without further intervention such as grafting or revision fixation.
How do atrophic and hypertrophic non-unions differ?
An atrophic non-union has poor blood supply and little callus and usually needs bone grafting. A hypertrophic non-union has abundant callus but inadequate stability, so it needs better fixation.
Why is compartment syndrome an emergency?
Rising pressure in a closed compartment cuts off perfusion and can cause irreversible muscle and nerve death within hours, so it needs urgent fasciotomy rather than observation.
Which fractures classically cause avascular necrosis?
Fractures of the femoral head, the scaphoid and the talus, because in each the blood supply enters in a way that a fracture can easily interrupt.
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