Overview
Femoral neck fractures represent >50% of all hip fractures and constitute approximately 20% of the operative orthopaedic trauma workload. They carry a ~10% 30,day mortality and ~25–30% one,year mortality in elderly patients, conferring a combined health and care cost exceeding that of stroke or myocardial infarction. The majority are intracapsular, occurring in osteoporotic elderly women following low,energy falls. Displacement is the single most important determinant of management, underpinning both the Garden and AO/OTA classification systems.
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Anatomy and Biomechanical Considerations
Blood Supply to the Femoral Head
The femoral head receives its dominant blood supply via the medial femoral circumflex artery (MFCA), whose retinacular branches ascend along the femoral neck within the synovial lining. The superior retinacular artery (lateral epiphyseal artery) is traditionally cited as the dominant contributor; the inferior retinacular artery has more recently been shown to also provide significant perfusion with a consistent anatomical course. Both are vulnerable to disruption with displacement or malreduction. The artery of the ligamentum teres (obturator artery) contributes minimally in adults. Intracapsular haematoma may elevate intra,articular pressure and compromise retinacular flow — the rationale for capsulotomy/decompression, though benefit remains unproven and controversial.
Biomechanical Relevance to Fixation
The femoral neck is predominantly cortical with limited cancellous bone — screws will settle until abutting intact cortex, so positioning is critical. Fixation failure occurs through: , Varus collapse (inadequate medial buttress) , Posterior comminution/retroversion , Screw cut,out (tip,apex distance >25 mm, poor positioning)
Higher Pauwels angles generate predominantly shear forces, increasing failure risk with standard cannulated screws.
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Classification Systems
Garden Classification (1961)
Based on the relationship of trabecular lines in the femoral head to those in the acetabulum on the AP radiograph alone.
| Grade | Description | Trabecular Pattern | |,,,|,,,|,,,| | I | Incomplete (valgus,impacted); intact medial calcar | Medial trabeculae angled relative to acetabular trabeculae (head tilted into valgus) | | II | Complete, non,displaced | Medial trabeculae align continuously with acetabular trabeculae | | III | Complete, partially displaced | Trabecular malalignment; head partially displaced retaining some continuity | | IV | Complete, fully displaced | Head trabeculae paradoxically re,align with acetabular trabeculae (head has rotated into apparent normal position despite full displacement) |
Practical grouping: , Stable: Grades I and II (non,displaced/impacted) → internal fixation , Unstable: Grades III and IV (displaced) → arthroplasty in elderly; ORIF in young
The four,grade system has poor inter,observer reliability. The binary collapse (non,displaced vs displaced) has superior reproducibility and greater clinical utility — some authors advocate abandoning the four,grade system in favour of this binary classification.
Examination pitfall: Garden IV fractures paradoxically show near,normal trabecular alignment on AP radiograph because the head has completely rotated. Grades III and IV are managed identically in clinical practice.
AO/OTA Classification
Proximal femoral fractures (segment 31):
| Code | Description | |,,,|,,,| | 31,A | Trochanteric fractures (extracapsular) | | 31,B | Femoral neck fractures (intracapsular) | | 31,C | Femoral head fractures |
Femoral neck (31,B) subgroups:
| Subtype | Description | |,,,|,,,| | 31,B1 | Subcapital, non,displaced (impacted in valgus) | | 31,B2 | Transcervical | | 31,B3 | Subcapital, displaced (non,impacted) |
The AO system additionally captures fracture location. Its inter,observer reliability is comparable to binary Garden grouping. Both systems are examinable; the Garden classification remains more widely used in clinical communication.
Pauwels Classification
Based on the angle of the fracture line relative to the horizontal on AP radiograph:
| Type | Pauwels Angle | Predominant Force | Clinical Significance | |,,,|,,,|,,,|,,,| | I | <30° | Compression | Low fixation failure risk | | II | 30–50° | Mixed | Intermediate risk | | III | >50° | Shear | High failure risk with cannulated screws; consider fixed,angle device |
Pauwels III ("vertical") fractures are most relevant in young patients where head preservation mandates internal fixation.
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Clinical Assessment
History
, Mechanism: low,energy fall (elderly/osteoporotic) vs high,energy trauma (young) , Premorbid mobility and walking aids , Cognitive function (influences arthroplasty type selection) , Comorbidities and anticoagulation status , Pre,injury ipsilateral hip symptoms or arthritis
Examination
, Displaced fracture: shortened, externally rotated limb , Garden I (impacted): near,normal posture; groin pain on axial load or log roll; may be walking , Neurovascular assessment of lower limb , Systematic medical evaluation for modifiable perioperative risk , Skin assessment (pressure area risk)
Occult Fractures
Approximately 4% of patients present with hip pain, normal plain radiographs, and an occult fracture. Investigate with MRI (gold standard; detects trabecular injury within 24 hours) or CT (more accessible but lower sensitivity). Bone scan sensitivity is delayed 48–72 hours post,injury.
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Investigations
| Investigation | Purpose | |,,,|,,,| | AP pelvis + lateral hip X,ray | First,line; Garden/AO classification; assess contralateral hip | | CT pelvis | Fracture characterisation, occult fractures, posterior comminution, basicervical vs intertrochanteric differentiation | | MRI hip | Gold standard for occult fractures; high sensitivity and specificity within 24 hours | | FBC, UEC, coagulation, group and hold | Perioperative work,up; renal dysfunction common post,hip fracture | | Bone profile | Screen for secondary osteoporosis | | ECG, CXR | Perioperative cardiac assessment | | DEXA | Post,acute; secondary fracture prevention planning |
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Non,operative Management
Reserved for approximately 5–8% of patients: , Terminal illness with prohibitive surgical risk , Non,ambulatory, minimal,pain patients , Prohibitive anaesthetic risk where surgical benefit cannot be justified
When non,operative: fascia iliaca or PENG block analgesia, pressure area nursing, early palliative input, family discussions. Touch,down weight bearing 6–8 weeks if managed without surgery.
Garden I fractures: historically managed non,operatively, but up to 30% of valgus,impacted fractures displace without fixation — operative fixation is now recommended for the majority of Garden I and II fractures.
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Operative Management
Decision Framework
$$\text{Non,displaced (Garden I/II)} \rightarrow \text{Internal fixation (all ages)}$$
$$\text{Displaced (Garden III/IV), elderly} \rightarrow \text{Arthroplasty (HA or THA)}$$
$$\text{Displaced (Garden III/IV), young} \rightarrow \text{Urgent ORIF (head preservation)}$$
Operative Management by Patient Profile
| Patient Profile | Fracture | Preferred Management | |,,,|,,,|,,,| | Any age, non,displaced | Garden I/II | Cannulated screw fixation (3 screws) | | Elderly, displaced, low demand or cognitive impairment | Garden III/IV | Cemented hemiarthroplasty | | Elderly, displaced, active and independent, no hip arthritis | Garden III/IV | THA | | Elderly, displaced, pre,existing ipsilateral OA or RA | Garden III/IV | THA | | Young (<55–60 years), displaced | Garden III/IV | Urgent ORIF | | Basicervical fracture | Any | Sliding hip screw or cephalomedullary nail |
Internal Fixation: Indications and Principles
Indications: Garden I and II (all patients); Garden III/IV in young patients where head preservation is the priority.
| Device | Notes | |,,,|,,,| | Three parallel cannulated cancellous screws (6.5–7.3 mm) | Standard for non,displaced fractures; inverted triangle or inferior,posterior configuration | | Dynamic Hip Screw (DHS) ± anti,rotation screw | Basicervical fractures; controlled collapse along screw axis | | Femoral Neck System (FNS) | Fixed,angle construct; increasing use for Pauwels III (vertical) fractures | | Cephalomedullary nail | Basicervical fractures, subtrochanteric extension, or ipsilateral shaft fracture |
Technical principles: , Tip,apex distance (TAD) should be $<25\ \text{mm}$ to minimise cut,out:
$$\text{TAD} = d_{AP} + d_{LAT}$$
where $d_{AP}$ and $d_{LAT}$ are the distances from the screw tip to the femoral head apex on AP and lateral views respectively.
, Inferior and posterior screw placement provides the best cortical buttress against displacement , Avoid starting point distal to the lesser trochanter (increased subtrochanteric peri,implant fracture risk) , Varus malreduction is strongly associated with fixation failure — anatomical or slight valgus reduction preferred , Internal fixation carries up to 30% failure rate in displaced fractures; higher with sagittal plane deformity (retroversion) , Decompression of intracapsular haematoma to reduce AVN risk: rationale exists but benefit is unproven and controversial
Hemiarthroplasty (HA): Indications and Principles
Indications: Displaced femoral neck fractures in elderly patients with lower functional demands or cognitive impairment (dementia, Parkinson disease — unable to comply with dislocation precautions).
| Factor | Recommendation | |,,,|,,,| | Cemented vs uncemented stem | Cemented preferred — lower periprosthetic fracture risk, superior pain outcomes, lower revision rate in osteoporotic bone (AAOS: moderate recommendation) | | Unipolar vs bipolar | Similar functional outcomes (AAOS: moderate recommendation); bipolar theoretical acetabular benefit unproven | | Surgical approach | Anterolateral reduces dislocation risk compared with posterolateral approach |
Total Hip Arthroplasty (THA): Indications and Principles
Indications: Active, independently mobile elderly patients with displaced femoral neck fractures; pre,existing ipsilateral hip OA or RA; patients likely to outlive a hemiarthroplasty.
HEALTH Trial (NEJM 2019): Among patients ≥50 years with displaced femoral neck fractures, THA did not result in significantly better functional outcomes (WOMAC) than HA at 24 months in an unselected elderly cohort. THA was associated with a higher rate of re,operation at 2 years (mainly dislocation). This supports selective rather than universal application of THA.
AAOS CPG: THA more beneficial than HA in properly selected patients with displaced femoral neck fractures (moderate recommendation strength).
| Consideration | Notes | |,,,|,,,| | Dislocation risk | Higher than HA, especially posterior approach | | Approach | Anterolateral or direct anterior preferred to reduce dislocation | | Dual,mobility or constrained liner | Consider for high dislocation risk | | Cemented femoral component | Preferred | | Contraindications | Dementia, severe cognitive impairment, inability to comply with dislocation precautions |
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Timing of Surgery
| Timeframe | Evidence and Recommendation | |,,,|,,,| | Within 24–48 hours | Reduces 30,day and 1,year mortality; reduces pressure injuries, delirium, and pain (AAOS: 48,hour target) | | Delay >48 hours | Multiple observational studies demonstrate increased mortality | | Medical optimisation | Appropriate for reversible, time,sensitive conditions (e.g. haemodynamically significant arrhythmia, acute decompensated heart failure, anticoagulation reversal) — target correction within 24–48 hours | | Young patient, displaced fracture | Surgical emergency — proceed as soon as safely possible, ideally within 6–12 hours, to maximise femoral head perfusion |
Key principle: The 48,hour threshold for mortality benefit is well,supported and should prompt expedited theatre access. ASA grade predicts operative risk — most modifiable factors can be optimised within 24 hours without unacceptable delay.
ANZ context: The ANZHFR tracks 48,hour surgical compliance as a key performance indicator, alongside 30,day mortality, early mobilisation, bone protection prescribing, and falls prevention.
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Complications
Fracture,Related Complications
| Complication | Risk Factors | Management | |,,,|,,,|,,,| | Avascular necrosis (AVN) | Displacement, delayed reduction, Garden III/IV | Analgesia → arthroplasty (stage,dependent) | | Non,union | Varus reduction, osteoporosis, displacement | Valgus osteotomy (young); salvage arthroplasty (elderly) | | Fixation failure / screw cut,out | TAD >25 mm, varus, Pauwels III, poor bone quality | Revision arthroplasty | | Femoral neck shortening | Collapse after fixation | Usually asymptomatic; arthroplasty if symptomatic |
Arthroplasty,Specific Complications
| Complication | Hemiarthroplasty | THA | |,,,|,,,|,,,| | Dislocation | Lower risk | Higher risk (especially posterior approach) | | Acetabular erosion | Long,term risk (HA → conversion to THA) | Not applicable | | Periprosthetic fracture | Uncemented > cemented | Uncemented > cemented | | Prosthetic loosening | Uncemented > cemented | Uncemented > cemented | | Infection | 1–3% | 1–3% |
General Complications
, Mortality: 30,day ~10%; 1,year ~25–30% , Delirium: 15–50%; predicted by pre,existing cognitive impairment, pain, and anaesthetic type , DVT/PE: DVT rates up to 50% without prophylaxis; LMWH or aspirin standard (CRISTAL trial: aspirin non,inferior to enoxaparin for symptomatic VTE in hip/knee arthroplasty) , Contralateral hip fracture: ~10% at 5 years — DEXA, falls prevention, and osteoporosis treatment essential , Pressure injuries, pneumonia, UTI: reduced by expedited surgery and early mobilisation
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Outcomes and Prognosis
| Metric | Data | |,,,|,,,| | 1,year mortality (elderly, displaced) | ~25–30% | | Return to pre,fracture functional level | ~50–60% | | Fixation failure rate (displaced fractures, cannulated screws) | Up to 30% | | HEALTH trial: THA vs HA functional difference at 24 months | No statistically significant difference in unselected elderly cohort | | Re,operation rate at 2 years (HEALTH) | Higher in THA group (primarily dislocation) |
Prognostic predictors: , Pre,fracture mobility and cognitive status are the strongest predictors of postoperative function , ASA grade and Charlson Comorbidity Index (CCI) predict perioperative mortality , Age alone should not preclude surgical intervention
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Paediatric Considerations
Femoral neck fractures in children are rare, high,energy injuries with distinctly different management.
| Feature | Notes | |,,,|,,,| | Classification | Delbet classification (4 types by location) — not Garden | | AVN risk | Very high (up to 40–50% in displaced fractures); reduced by urgent fixation | | Timing | Surgical emergency — urgent reduction and fixation within 6–12 hours | | Physeal considerations | Avoid routine physis,crossing screws in young children; urgency of anatomical reduction paramount | | Arthroplasty | Not applicable — head preservation mandatory |
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Examination Summary
| Key Point | Detail | |,,,|,,,| | Garden I/II | Internal fixation (all ages); urgent in young with displaced fractures | | Garden III/IV, elderly | Arthroplasty; cemented stem; THA for active patients without cognitive impairment; HA for lower demand or cognitively impaired | | Surgery timing | Within 48 hours reduces mortality; within 6–12 hours for young displaced fractures | | TAD | $<25\ \text{mm}$; avoid varus; inferior,posterior screw placement | | AO/OTA | 31,B = intracapsular neck; 31,A = intertrochanteric (extracapsular); 31,C = femoral head | | Pauwels III | Highest shear; highest fixation failure risk — consider fixed,angle device (DHS, FNS) | | HEALTH trial | THA vs HA — no significant overall functional benefit at 24 months in unselected elderly; supports selective THA use | | AAOS CPG | Arthroplasty for displaced = strong recommendation; cemented stems = moderate recommendation; THA over HA in selected patients = moderate recommendation | | ANZHFR | Tracks 48,hour surgery compliance, 30,day mortality, mobilisation, bone protection — key ANZ quality indicators | | Non,operative | Only 5–8% of patients; terminal illness or prohibitive surgical risk | | Garden IV paradox | Trabecular alignment appears normal on AP despite complete displacement | | Binary Garden grouping | Superior inter,observer reliability to 4,grade system; non,displaced vs displaced drives management |