Basicervical Fractures

Basicervical fractures occur at the base of the femoral neck, just proximal to the intertrochanteric line (AO/OTA 31-B2.1). The fracture line lies largely outside the capsular reflection, so the injury is effectively extracapsular and behaves biomechanically far more like an intertrochanteric fracture than a true intracapsular neck fracture. The hallmark problem is rotational and collapse instability: a single lag implant can allow the proximal fragment to rotate, producing collapse, cut-out and a need for reoperation.

There is no universally agreed radiographic definition, which is the main reason reported failure rates vary so widely in the literature.

Mechanism of Injury

Similar to femoral neck fractures:

• Low-energy fall: Elderly patients (osteoporosis)
• High-energy trauma: Young patients (motor vehicle accident, fall from height)
• Torsion: Rotational force
• Direct trauma: Less common

The basicervical region is a transition zone between the femoral neck and intertrochanteric region. Because the line sits at the base of the neck, the fragment is short and the rotational lever arm is small, which is exactly why a single lag screw or blade is prone to allowing rotation and collapse.

Epidemiology

• Incidence: uncommon - 1.8% of all proximal femoral fractures in pooled review data; up to ~4% in single-centre series (the older "5-10%" figure is not supported)
• Age: predominantly elderly with osteoporotic bone; a minority result from high-energy trauma in younger patients (e.g. concurrent ipsilateral hip-and-shaft injuries, where basicervical was the commonest hip-fracture subtype)
• Gender: female predominance (osteoporosis)
• Laterality: usually unilateral
• Associated injuries: consider ipsilateral femoral shaft fracture in high-energy cases

Basicervical Region Anatomy

The basicervical region:

• Location: base of the femoral neck, immediately proximal to the intertrochanteric line
• Boundaries: distal to the true femoral neck, proximal to the lesser trochanter
• Capsule: the fracture line lies at or distal to the capsular reflection - functionally extracapsular
• Blood supply: the medial femoral circumflex artery and its retinacular branches enter more distally than the subcapital region, so the head fragment usually retains its blood supply
• Biomechanics: short proximal fragment with a small rotational lever arm

Pathophysiology

History

Mechanism: Similar to femoral neck fractures

• Low-energy fall: Elderly patients (osteoporosis)
• High-energy trauma: Young patients (motor vehicle accident, fall from height)
• Torsion: Rotational force

Symptoms:

• Immediate pain in hip/groin
• Inability to bear weight
• Leg shortening and external rotation (if displaced)
• Pain with movement

Physical Examination

Inspection:

• Leg shortening (if displaced)
• External rotation (if displaced)
• Swelling (minimal - deep location)

Palpation:

• Tenderness over hip/groin
• Crepitus (rare)
• Greater trochanter tenderness

Range of Motion:

• Limited hip ROM (pain)
• Pain with passive motion
• Inability to perform straight leg raise (if displaced)

Neurovascular Status:

• Usually intact
• Assess distal pulses and sensation

Associated Injuries

• Other fractures: 10-15% (wrist, spine, other hip)
• Head injury: 5-10% (high-energy trauma)
• Soft tissue injuries: Less common

Differential Diagnosis (Where Is The Fracture Line?)

The whole management decision turns on correctly distinguishing a basicervical fracture from its neighbours on the AP and lateral films.

Every construct in this topic is judged against one number - the tip-apex distance (TAD) - yet the metric deserves defining in its own right, because a low TAD is the single most reproducible way to reduce lag-screw cut-out in a rotationally unstable base-of-neck fracture.

Definition (Baumgaertner). TAD is the sum of two distances: the gap from the tip of the lag screw to the apex (subchondral surface) of the femoral head measured on the AP radiograph, plus the same distance measured on the lateral radiograph. Each distance is corrected for radiographic magnification, using the known diameter of the lag screw as the on-screen scale.

Why 25 mm. In the original 198-fracture series, none of the 120 screws with a TAD of 25 mm or less cut out; mean TAD was 24 mm in fractures that healed versus 38 mm in those that failed, with a strong dose-response - every additional millimetre raised the cut-out risk regardless of fracture pattern, reduction or implant.

How to hit it: aim the guide wire centre-centre or slightly inferior-central, deep to within 5-10 mm of subchondral bone, on both views before reaming. A calcar-referenced TAD (CalTAD), which measures the AP component from an inferiorly placed screw to the calcar rather than to the centre, has been proposed as a refinement, reflecting evidence that an inferior (rather than superior) AP screw position resists cut-out; the practical message is the same - deep, central-to-inferior, and never superior or short.

Fracture-Site Collapse and Fixation Failure

Collapse ~25%, conversion to arthroplasty ~8-9%:

• Cause: rotational instability and comminution of the short proximal fragment; an extramedullary plate (vs IM helical blade) independently raised failure (OR 12.2 in cohort data)
• Prevention: rotational control (derotation screw or helical blade), central lag screw, tip-apex distance under 25mm
• Management: revision fixation, or conversion to arthroplasty for established failure

AVN

Uncommon:

• Cause: the fracture is largely extracapsular and distal to the main retinacular entry, so the head usually keeps its blood supply - AVN is far less common than after a displaced intracapsular neck fracture
• Management: arthroplasty if symptomatic AVN does develop

Nonunion

Uncommon (lower than intracapsular neck fractures):

• Cause: inadequate fixation, poor reduction, poor bone quality
• Prevention: stable construct with good cortical apposition
• Management: revision fixation or conversion to arthroplasty

Weight Bearing and Mobilisation

• Early mobilisation is the goal in this elderly population - prolonged restricted weight bearing is poorly tolerated and increases medical complications
• With a stable cephalomedullary nail or sliding hip screw, weight bear as tolerated under physiotherapy supervision; reserve protected weight bearing for very comminuted or tenuous constructs
• Arthroplasty: weight bear as tolerated
• Begin hip and knee range of motion and quadriceps work from day one

Recovery Trajectory

• Inpatient: orthogeriatric review, VTE prophylaxis, analgesia, delirium screening
• Weeks 0-6: supervised gait re-education, progressive loading, falls prevention
• Weeks 6-12: most patients consolidating; check radiographs for collapse and screw position
• Ongoing: bone-protection therapy, continued strength and balance work

Functional recovery to pre-injury mobility is the realistic endpoint; the priority is preventing collapse and a second fall, not return to sport.

Pooled Outcomes by Implant

Pooled systematic-review data (Dekhne 2021; Yoon 2022) give revision rates of approximately:

• Sliding hip screw: ~7%
• Cephalomedullary nail: ~8% (slightly faster union than SHS)
• Cannulated screws: 23% (unacceptable - avoid)
• Hemiarthroplasty: ~8%; total hip arthroplasty: ~0% (very small numbers)

Cohort data show fracture-site collapse in ~25% and conversion to arthroplasty in ~8-9% of fixed cases (Lee 2018).

Prognostic Factors

Because the fracture is largely extracapsular, AVN and nonunion are uncommon - the dominant late problem is mechanical collapse, not vascular failure.

This is predominantly a fragility fracture, so management does not end with the operation.

• Treat the osteoporosis: assess fracture risk and start bone-protective therapy (e.g. bisphosphonate or denosumab) with calcium/vitamin D as indicated
• Falls prevention: multifactorial assessment, gait and balance training, medication review, home-hazard modification
• Orthogeriatric co-management and early mobilisation reduce medical complications and mortality after hip fracture
• In the rare high-energy young patient, exclude an ipsilateral femoral shaft fracture and other injuries

The topic repeatedly flags the need to exclude an ipsilateral femoral shaft fracture in high-energy cases, and notes that the basicervical pattern was the commonest hip-fracture subtype among concurrent ipsilateral hip-and-shaft injuries - a combination that deserves its own plan, because it changes both the work-up and the implant strategy.

Recognise it. Ipsilateral neck-and-shaft fractures are a recognised association of high-energy femoral shaft fractures in younger patients. The neck component is notoriously easy to miss - it is often minimally displaced, vertical or basicervical, and overshadowed by the dramatic shaft injury, so a substantial minority are diagnosed late. Every high-energy femoral shaft fracture therefore warrants dedicated hip imaging: a true AP internal-rotation hip view, fine-cut CT of the femoral neck, and a deliberate fluoroscopic check of the neck before, during and after shaft fixation.

The neck fracture takes priority. Its risk of avascular necrosis and nonunion dominates the long-term prognosis, so it must be anatomically reduced and stabilised - do not let neck reduction be lost while passing an antegrade nail.

Two construct strategies:

• Single-implant reconstruction (cephalomedullary) nail - one device spans both fractures, but neck reduction and proximal-screw placement are constrained by the nail, and the neck can be left under-reduced.
• Dual-implant "separate" fixation - the neck is fixed independently (cannulated screws or a sliding hip screw) and the shaft with a retrograde nail or plate. This is increasingly favoured because it lets the higher-stakes neck fracture be reduced and fixed anatomically and independently of the shaft implant.

Whichever is chosen, the guiding principle is the same: treat the neck fracture as the priority injury and confirm its reduction is maintained after the shaft is stabilised.

Global Epidemiology

• Basicervical fractures are uncommon: ~1.8% of all proximal femoral fractures in pooled review data, up to ~4% in single-centre series
• Predominantly a fragility fracture of older adults with osteoporotic bone; female predominance
• In high-energy young patients, basicervical was the commonest hip-fracture subtype in concurrent ipsilateral hip-and-shaft injuries

Guidelines Side by Side

Registry and Practice Variation

• Hip-fracture registries (e.g. UK National Hip Fracture Database, and national registries elsewhere) track time-to-surgery, orthogeriatric input and 30-day mortality; basicervical fractures are usually pooled within neck or trochanteric categories
• High-resource settings: routine cephalomedullary nails/helical blades, orthogeriatric pathways, systematic bone-protection
• Limited-resource settings: sliding hip screw remains a cost-effective, widely available workhorse with equivalent revision rates; implant choice is often driven by availability rather than marginal biomechanical advantage