Hip Fracture
Hip fracture usually refers to a fracture of the proximal femur and is most common in older adults after a fall. The key classification is intracapsular vs extracapsular, as this determines the risk of complications and the preferred surgical approach.
This updated UKMLA guide to hip fracture is based on NICE CG124, which covers intracapsular vs extracapsular hip fracture, causes, risk factors, symptoms, diagnosis, and management.
Anatomy and Classification
Illustration created by Guideline Genius
Intracapsular vs extracapsular hip fracture is the most important classification, as it determines both management and risk of complications.
- The anterior capsular attachment is along the intertrochanteric line, which runs from the greater trochanter to the lesser trochanter
- Intracapsular fracture = fracture line proximal to the intertrochanteric line
- Extracapsular fracture = fracture line distal to the intertrochanteric line
For the clinical significance, see the complications and management sections below.
Blood supply to the femoral head (relevant for complications):
| Artery | Importance |
|---|---|
| Medial femoral circumflex artery (retinacular branches) | Main blood supply to the femoral head in adults |
| Lateral femoral circumflex artery | Smaller contribution to femoral head |
| Artery of the ligamentum teres | Minor contribution in adults; more important in children |
The medial and lateral circumflex femoral artery branch off the profunda femoris artery (a branch of the femoral artery).
Intracapsular fractures are clinically important because the retinacular vessels (of the medial femoral circumflex artery) supplying the femoral head run along the intracapsular femoral neck. These vessels may be disrupted, especially in displaced fractures, increasing the risk of avascular necrosis of the femoral head.
Causes and Risk Factors
Common causes / mechanisms of hip fractures: [Ref]
- Falls (more common in the elderly population)
- High-energy trauma (more common in younger adults)
- Causes of pathological hip fracture
- Malignancy (e.g. primary bone tumour, bone metastasis, multiple myeloma)
- Use of bisphosphonates (increases risk of atypical femoral fracture)
A hip fracture may occur after high-energy trauma in any patient.
However, in older adults, most hip fractures are fragility fractures, meaning they occur after low-energy trauma, usually a fall from standing height, due to underlying bone fragility such as osteoporosis.
There are 2 main groups of risk factors:
| Risk factors for falls | Frailty and reduced mobility
Alertness / cognitive impairment
Dizziness-related
Sensory or environmental factors
|
| Risk factors for osteoporosis / fragility fracture | Typical risk factors (as per FRAX score)
|
Clinical Features
Hip fracture typically presents after a fall or trauma with: [Ref]
- Hip pain (often worse on palpation of the groin / greater trochanter)
- Inability to walk or weight-bear
- Reduced mobility / immobility
A displaced hip fracture classically presents with a shortened + externally rotated lower limb [Ref]
- Shortening occurs due to the unopposed upward pull of the iliopsoas muscle
- External rotation occurs due to the unopposed action of the external rotator muscles
- The degree of visible deformity depends on the fracture pattern and the extent of displacement
Undisplaced fractures may have minimal or no visible deformity.
Important differentials:
- Posterior hip dislocation = shortened + internally rotated + adducted lower limb
- Anterior hip dislocation = externally rotated + abducted lower limb (with no obvious shortening or even lengthening)
Investigation and Diagnosis
1st line investigation: X-ray pelvis (AP view and lateral view)
If X-ray is normal and clinical suspicion of a hip fracture remains (i.e. suspected occult fractures) → offer MRI
- If not available → consider CT
Classifying the fracture:
- Intracapsular fracture = fracture line proximal to the intertrochanteric line
- Extracapsular fracture = fracture line distal to the intertrochanteric line
Standard bloods to be performed on admission:
- FBC, U&Es
- Clotting profile
- Cross-match
Management
Analgesia
Offer immediate analgesia:
- 1st line: paracetamol
- If ineffective: add opioids
- If still ineffective: consider nerve blocks (e.g. femoral nerve block, fascia iliaca compartment block)
NSAIDs are not recommended
Definitive Management
Definitive management involves surgery and should be performed within 48 hours of admission
The choice of surgery depends on the type of hip fracture:
| Fracture type | Subtype | Surgical approach |
|---|---|---|
| Intracapsular fracture | Displaced | Hip replacement (arthroplasty) with cemented implants
|
| Undisplaced | Consider any of the following: [Ref]
|
|
| Extracapsular fracture | Intertrochanteric | Sliding hip screw / dynamic hip screw (extramedullary implants) |
| Subtrochanteric | Intramedullary nail |
Post-operatively, patients should be encouraged to fully weight bear as soon as possible without restriction
Disclaimer:
NICE did not provide a specific recommendation for the surgical approach for undisplaced intracapsular fracture due to paucity of evidence
Similarly, the AAOS guideline notes that the evidence for stable / impacted / non-displaced femoral neck fractures is limited and conflicting. As a result, it recommends that a range of options may be considered (see above).
Secondary Prevention
After a hip fracture, the patient should be assessed for:
- Osteoporosis and future fracture risk, thus the need for bone-protective treatment (see the Osteoporosis article for more information)
- Risk of fall
Complications
Fracture-Related Complications
The primary complication of intracapsular hip fracture is avascular necrosis of the femoral head [Ref]
- The main arterial supply to the femoral head relies on retinacular branches from the medial circumflex femoral artery (and to a lesser extent the lateral circumflex femoral artery)
- Intracapsular fractures often damage these vessels → femoral head ischaemia → avascular necrosis
Risk factors for avascular necrosis:
- Displaced intracapsular fracture – most important
- Delayed reduction of the fracture
- Patient factors affecting healing and bone quality (e.g. smoking, corticosteroid use, alcohol excess, immunocompromised, osteoporosis / osteopaenia)
The primary complication of extracapsular hip fracture is mechanical instability, fixation failure and risk of non-union [Ref]
- Extracapsular hip fractures have a much lower risk of avascular necrosis because the femoral head blood supply is usually preserved
Surgery-Related Complications
Internal fixation (e.g. dynamic hip screw, intramedullary nail) may be complicated with: [Ref]
- Fixation failure
- Screw cut-out
- Implant failure
Hip replacements (arthroplasty) may be complicated with: [Ref]
- Prosthetic joint infection
- Dislocation
- Aseptic loosening
- Periprosthetic fractures