Define Pathological Fracture. Describe its causes and management.
Definition
A pathological fracture is a fracture through abnormal, weakened bone, occurring after trivial or no trauma that would not fracture normal bone. Recognising it matters because the underlying disease must be diagnosed and treated, and because management differs from that of an ordinary fracture.
Causes
Causes are local or generalised. Local: a bone tumour (benign cyst/enchondroma, or malignant — especially metastasis, myeloma or primary sarcoma) or infection. Generalised: osteoporosis (much the commonest overall, e.g. Vertebral and hip fragility fractures), osteomalacia, Paget’s disease, and metabolic/genetic disorders such as osteogenesis imperfecta.
DANGER / REMEMBER
A fracture after trivial injury, or bone pain preceding a fracture, should prompt a search for the underlying cause. In an adult over 40, always exclude metastasis and myeloma before assuming a simple fracture, and biopsy a suspicious lesion (ideally before fixation) so as not to miss a primary sarcoma.
Management
Management addresses both the fracture and its cause. Investigate to establish the diagnosis (radiographs, blood tests, bone scan/MRI, biopsy). Stabilise the fracture appropriately — often by internal fixation or prosthetic replacement, since pathological bone heals poorly — and treat the underlying disease (e.g. Radiotherapy and systemic therapy for a metastasis, anti-resorptive treatment for osteoporosis). Impending fractures (e.g. Mirels-positive metastases) are best fixed prophylactically.
Clinical Assessment
The clue is a mismatch between the force and the fracture, or bone pain preceding the injury. A careful history (previous cancer, weight loss, constitutional symptoms), examination and targeted investigations (calcium, alkaline phosphatase, renal function, protein electrophoresis, prostate-specific antigen, and imaging of the whole bone) establish the cause. The radiograph is inspected for the tell-tale lesion at the fracture site rather than being read simply as a fracture, since the lesion is easy to overlook once attention fixes on the break.
Never fix without establishing the underlying diagnosis.
KEY POINT
Key points TO remember
- Fracture through weakened bone after trivial/no trauma.
- Causes: local (tumour — esp. Metastasis/myeloma, infection) or generalised (osteoporosis commonest).
- In adults >40, exclude metastasis/myeloma; biopsy suspicious lesions before fixation.
- Treat fracture (often fixation/replacement) and the underlying cause; fix impending fractures prophylactically.
EXAM TIP
Sources: Maheshwari's Essential Orthopaedics; Apley & Solomon's System of Orthopaedics and Trauma; AO Principles of Fracture Management.
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