Lucan · Conditions

Neck of femur fracture

Australian guidance: ANZHFR Australian and New Zealand Guideline for Hip Fracture Care + ACSQHC Hip Fracture Care Clinical Care Standard + HealthPathways WA

1. Definition and epidemiology

A neck of femur (NOF) fracture is a break through the proximal femur between the femoral head and the intertrochanteric line, and is one of the most common serious injuries of older age. In Australia the typical patient is a woman in her eighties with osteoporosis who sustains the fracture in a low-energy fall from standing height, most often onto the greater trochanter; the female-to-male ratio is roughly 2:1, reflecting the disproportionate burden of postmenopausal bone loss. A NOF fracture in a young patient is a different disease altogether, usually the result of high-energy trauma (motor vehicle crash, fall from height) in bone of normal density, and carries a much higher risk of disrupting the femoral head blood supply because the force required is far greater. Hip fracture is tracked nationally through the Australian and New Zealand Hip Fracture Registry (ANZHFR), reflecting its status as a sentinel event: it marks the point at which frailty, falls risk, and osteoporosis converge, and it carries a mortality and loss-of-independence burden that rivals many cancers, which is why its management is protocolised end-to-end from emergency department to secondary prevention.

Strictly, "neck of femur fracture" refers only to a fracture of the femoral neck itself (an intracapsular fracture, either subcapital or transcervical); intertrochanteric and subtrochanteric fractures are extracapsular and, on a strict anatomical reading, are "hip fractures" rather than NOF fractures proper. In AU clinical shorthand, however, "NOF#" is used loosely as an umbrella term for any fracture of the proximal femur, intracapsular or extracapsular, and this note follows that common usage while covering both categories explicitly in Section 2. A student asked to define a NOF fracture strictly should answer with the femoral neck (intracapsular) fracture alone.

2. Pathophysiology

The single organising concept for this topic is blood supply. The femoral head and the proximal neck are supplied predominantly by the medial circumflex femoral artery, which gives rise to the retinacular (ascending cervical) vessels that run proximally along the posterosuperior surface of the femoral neck, tethered beneath the hip capsule, before piercing the head near the head-neck junction. The lateral circumflex femoral artery contributes a smaller anteroinferior supply, and the artery of the ligamentum teres (a branch of the obturator artery) supplies only a small medial portion of the head and is frequently attenuated or obliterated with age, so in most older adults it cannot sustain the head alone.

This anatomy is why the intracapsular versus extracapsular distinction matters more than almost any other classification in orthopaedics. Intracapsular fractures (subcapital and transcervical, occurring within the hip joint capsule) shear through or strip the retinacular vessels running along the neck, cutting off the femoral head's retrograde blood supply; the more displaced the fracture, the more complete the disruption, and the higher the risk of avascular necrosis (AVN) and nonunion, because a devascularised head cannot generate the biological response needed for fracture healing or fixation to succeed. Extracapsular fractures (intertrochanteric, between the greater and lesser trochanters, and subtrochanteric, below the lesser trochanter) occur outside the capsule in cancellous, richly vascularised metaphyseal bone supplied directly by perforating branches of the profunda femoris; the femoral head's blood supply is preserved, healing potential is good, and the fracture can be fixed rather than replaced. This single mechanistic difference drives essentially every downstream decision about implant choice.

Intracapsular fracture displacement is described using the Garden classification: Garden I is an incomplete or valgus-impacted fracture, Garden II is complete but undisplaced, Garden III is complete with partial displacement (trabeculae not fully disrupted), and Garden IV is complete with full displacement. Interobserver agreement on the four-point scale is poor, so in practice clinicians collapse it to a two-way split, undisplaced (Garden I-II) versus displaced (Garden III-IV), which is what actually drives management.

3. Clinical presentation and diagnostic criteria

The classic presentation is an older patient who cannot weight-bear after a fall, with groin or hip pain and, on inspection, a leg that is shortened and externally rotated. Shortening occurs because the unopposed pull of the short external rotators and the iliopsoas draws the distal fragment proximally once the fracture disrupts the bony strut; external rotation occurs because the same short external rotators (piriformis, obturator internus and externus, gemelli, quadratus femoris) rotate the distal fragment laterally once its normal attachment to a stable femoral neck is lost. Pain is worsened by any attempt at hip movement, and there is often bruising and tenderness over the greater trochanter.

This limb position is a useful discriminator against the other classic cause of an acutely deformed hip, posterior hip dislocation, which instead shortens the limb with the hip held flexed, adducted, and internally rotated (the opposite rotation), typically in a younger patient after a high-energy dashboard-type injury. A minority of NOF fracture patients, particularly those with an impacted or undisplaced fracture, remain able to weight-bear with only mild groin pain, which is the clinical scenario most likely to mask an occult fracture and delay diagnosis if imaging is not pursued.

Gentle axial loading of the leg (a light heel-tap or heel-percussion test) and pain on passive log-rolling of the hip into internal and external rotation both reproduce the patient's pain in a true NOF fracture and are useful bedside adjuncts when the deformity is subtle, though neither is sensitive or specific enough to substitute for imaging. Distal neurovascular status (dorsalis pedis and posterior tibial pulses, sensation over the foot) is checked and documented on presentation, both as a baseline before surgery and because a cold, pulseless limb raises concern for a separate vascular injury rather than the fracture itself.

4. Investigations and AU-specific cutoffs

An AP pelvis radiograph and a lateral view of the affected hip are the first-line investigation for any older patient presenting with hip pain or an inability to weight-bear after a fall, and are usually diagnostic. Where the plain film is normal or equivocal but clinical suspicion remains high (persistent groin pain, inability to straight-leg raise or weight-bear despite a normal radiograph), the fracture is treated as an occult NOF fracture until proven otherwise, and MRI of the hip is the investigation of choice: it is the most sensitive modality for detecting the fracture line and the surrounding bone marrow oedema of a trabecular microfracture that plain film cannot resolve. Where MRI is unavailable or contraindicated (for example, a pacemaker without MRI compatibility), CT of the hip is an acceptable second-line alternative, with a radionuclide bone scan reserved as a further fallback once a few days have elapsed for tracer uptake to become positive. AU practice generally favours early MRI in this scenario, within 24 hours, per the ANZHFR guideline's own consensus-based recommendation, rather than immobilising and reassessing empirically, because missing an occult fracture and allowing the patient to continue weight-bearing risks converting an undisplaced, easily fixed fracture into a displaced one with a much worse prognosis; where MRI is not available within 24 hours, CT is the guideline's stated fallback.

5. Management

Once confirmed, hip fracture triggers a protocolised, time-critical pathway. The ACSQHC Hip Fracture Care Clinical Care Standard (revised September 2023) and the ANZHFR guideline set surgery within 36 hours of first presentation as the national quality benchmark (tightened from a prior 48-hour standard), with the ANZHFR guideline itself framing this as operating on the day of, or the day after, presentation once the patient is medically optimised, because delay independently increases 30-day mortality, pressure injury, hospital-acquired pneumonia, and venous thromboembolism. Delay is justified only to correct a reversible medical issue that would materially raise anaesthetic risk, such as reversing anticoagulation, correcting severe anaemia or electrolyte derangement, or urgently treating decompensated heart failure; it is not justified simply to await a more convenient theatre slot.

Operative choice is dictated by the intracapsular/extracapsular split, fracture displacement, and the patient's baseline function. An undisplaced intracapsular fracture (Garden I-II) is treated with internal fixation, most commonly cannulated screws, because the retinacular blood supply is largely intact and the native head has a good chance of healing; this avoids the added morbidity of arthroplasty in a fracture pattern that does not need it. A displaced intracapsular fracture (Garden III-IV) has disrupted the femoral head's blood supply and carries a high risk of AVN and fixation failure, so the head is replaced rather than fixed: patients who were previously fit, cognitively intact, and independently mobile with a reasonable life expectancy are offered total hip replacement (THR), which gives better functional outcomes and lower revision rates in this group than hemiarthroplasty; frailer patients, those with cognitive impairment, or those with lower baseline functional demand are offered hemiarthroplasty (replacement of the femoral head only, against the native acetabulum), which is a shorter, lower-risk procedure appropriate to lower functional demand.

Extracapsular fractures are fixed rather than replaced in essentially all patients, since the blood supply to the head is preserved: a stable two-part intertrochanteric fracture is managed with a dynamic (sliding) hip screw, while an unstable, reverse-obliquity, or subtrochanteric fracture is managed with a cephalomedullary (intramedullary) nail, which better resists the higher shear forces these fracture patterns generate.

Orthogeriatric co-management, in which a geriatrician or general/internal medicine physician runs a parallel, proactive comprehensive assessment alongside the surgical team, is a core recommendation of both the ANZHFR guideline and the ACSQHC Standard, and is associated with reduced mortality, shorter length of stay, and better functional recovery in registry and trial data. This shared-care model covers perioperative medical optimisation, delirium screening and prevention (avoiding precipitants such as dehydration, polypharmacy, and unnecessary catheterisation), early mobilisation within 24 hours of surgery wherever possible, nutrition, pressure injury prevention, and discharge and rehabilitation planning from day one.

Anaesthetic choice (spinal/regional versus general anaesthesia) is made jointly by the anaesthetic and surgical teams based on the patient's comorbidities, anticoagulation status, and cognitive baseline; neither technique has shown a clear, consistent mortality advantage over the other in this population, so the choice is individualised rather than protocolised in the way that surgical timing is.

6. Pharmacology and AU PBS notes

Multimodal analgesia is started immediately on presentation: regular paracetamol, a fascia iliaca compartment block (or femoral nerve block) as an opioid-sparing regional technique with a good AU evidence base for pain control at rest and with movement, and cautious, low-dose opioids titrated for breakthrough pain, since older patients are disproportionately sensitive to opioid-related delirium and respiratory depression. NSAIDs are generally avoided given the high prevalence of renal impairment and the perioperative bleeding and renal risk in this population. Pharmacological VTE prophylaxis, typically subcutaneous enoxaparin, is commenced per local protocol and continued into the postoperative period unless contraindicated by active bleeding or imminent surgery.

Every patient with a NOF fracture has, by definition, sustained a minimal trauma (fragility) fracture and should be assessed and treated for osteoporosis before discharge, ideally through a fracture liaison service model as promoted by Healthy Bones Australia and reflected in the ANZHFR guideline. This includes correcting vitamin D and calcium deficiency, and starting antiresorptive therapy: oral bisphosphonates (alendronate) are first-line where adherence and renal function allow, but IV zoledronic acid given annually is frequently preferred after hip fracture specifically, both because adherence is more assured with an annual infusion in a population prone to polypharmacy and cognitive impairment, and because zoledronic acid has trial evidence of a mortality benefit in this exact post-hip-fracture population. Denosumab is a subcutaneous alternative where bisphosphonates are contraindicated, particularly in significant renal impairment. Under the PBS, bisphosphonates and denosumab attract streamlined authority for patients who have sustained a minimal trauma fracture, removing the requirement for a formal T-score threshold that applies to primary prevention.

7. Complications and monitoring

Mortality is the headline complication: registry data consistently show roughly 5 to 10% mortality at 30 days and 20 to 30% at one year following hip fracture, reflecting both the injury itself and the burden of comorbidity in the population it affects. Avascular necrosis and nonunion are specific risks of displaced intracapsular fractures managed with fixation rather than arthroplasty, which is precisely why displaced intracapsular fractures are replaced rather than fixed in most patients; AVN typically manifests months to a few years after injury as recurrent groin pain and progressive collapse of the femoral head on imaging. Dislocation is a specific risk of arthroplasty and is more common after THR than hemiarthroplasty in this population, particularly via the posterior surgical approach; surgical site infection and periprosthetic fracture are recognised longer-term risks of any operative fixation. Beyond the implant itself, a substantial proportion of previously independent patients do not return to their pre-fracture level of mobility or living arrangement, which is the functional rationale underpinning the emphasis on early surgery, early mobilisation, and orthogeriatric co-management. Without secondary prevention, the risk of a further fragility fracture, including a contralateral NOF fracture, is markedly elevated, which is why osteoporosis treatment and falls-risk reduction are treated as part of the acute admission rather than deferred to outpatient follow-up.

Postoperative monitoring in the acute admission focuses on the same complications the pathway is designed to prevent: regular observation for delirium (using a validated screening tool), pressure injury checks given prolonged immobility and reduced sensation in frail skin, and clinical surveillance for VTE despite pharmacological prophylaxis, since hip fracture surgery itself remains a strong independent risk factor. Mobility and function are formally reassessed by physiotherapy at intervals through the admission to guide discharge and rehabilitation planning, and patients started on osteoporosis therapy are flagged, ideally through a fracture liaison service, for structured follow-up (repeat DEXA and adherence review) after discharge rather than being left to self-manage a chronic condition identified during an acute admission.

Written for Australian practice and grounded in the guidance named above. Study material only — not medical advice. Always check against current guidelines.