Subtrochanteric Fractures

Demographics

Bimodal Age Distribution:

• Young adults: High-energy trauma (MVA, motorcycle, falls from height)
• Elderly: Low-energy falls, pathological, or atypical fractures

Incidence:

• 10-15% of proximal femur fractures
• Increasing incidence of atypical fractures (bisphosphonate awareness)
• Male predominance in young, female in elderly

Understanding epidemiology guides clinical suspicion for different fracture etiologies.

Injury Mechanisms

High-Energy (Young):

• Motor vehicle accidents
• Motorcycle crashes
• Falls from height
• Sporting injuries
• Associated polytrauma common

Low-Energy (Elderly):

• Standing height falls
• Minimal trauma or spontaneous
• Pathological through metastasis
• Atypical bisphosphonate-associated

Atypical Fractures:

• Prodromal thigh pain (weeks to months before)
• Associated with over 5 years bisphosphonate use
• May occur with minimal or no trauma

Mechanism helps distinguish standard traumatic from atypical fractures.

Risk Factor Assessment

For Standard Fractures:

• High-energy trauma
• Osteoporosis
• Metastatic bone disease
• Primary bone tumors
• Metabolic bone disease

For Atypical Fractures:

• Bisphosphonate use over 5 years
• Glucocorticoid use
• Proton pump inhibitors
• Diabetes mellitus
• Rheumatoid arthritis
• Asian ethnicity (slightly higher risk)

Risk factor assessment guides investigation and treatment planning.

Subtrochanteric Region

Anatomical Boundaries:

• Superior: Lesser trochanter
• Inferior: 5cm below lesser trochanter (or to isthmus)
• Bone type: Transitional - cancellous to cortical

Muscular Attachments (Key for Deformity):

• Iliopsoas: Lesser trochanter - FLEXES proximal fragment
• Gluteus medius/minimus: Greater trochanter - ABDUCTS proximal fragment
• Short external rotators: Intertrochanteric - EXTERNALLY ROTATES proximal fragment
• Adductors: Linea aspera - ADDUCTS distal fragment

Vascular Anatomy

Periosteal Supply:

• Perforating branches of profunda femoris
• Supplies outer third of cortex
• Preserved with minimal soft tissue stripping

Endosteal Supply:

• Nutrient artery (from profunda femoris)
• Enters posterior cortex
• Supplies inner two-thirds of cortex
• Disrupted by reaming

Clinical Implication:

• Balance between biology and mechanics
• Avoid excessive periosteal stripping
• Reaming disrupts endosteal supply but promotes healing response

Understanding blood supply informs surgical technique decisions.

Mechanical Environment

Stress Distribution:

• Highest stress zone in entire femur
• Medial cortex: Compressive stress
• Lateral cortex: Tensile stress
• Maximum bending moment at this level

Implant Considerations:

• Must resist high bending forces
• Intramedullary nail = load-sharing = better
• Plate = load-bearing = higher failure rate
• Short nail creates stress riser distally

Why Nails Work Better:

• Shorter lever arm to fracture
• Load-sharing device
• Allows early weight-bearing
• Resists bending moment effectively

Biomechanics dictates why CMN is superior to plating in this region.

Russell-Taylor Classification

The Russell-Taylor classification determines nail entry point based on fracture extension:

Seinsheimer Classification

Describes fracture pattern complexity and stability:

ASBMR Atypical Fracture Criteria

Major Features (at least 4 of 5 required):

1. Minimal or no trauma (fall from standing height or less)
2. Fracture line originates at lateral cortex, is substantially transverse
3. Complete fractures extend through both cortices; incomplete involve lateral only
4. Non-comminuted or minimally comminuted
5. Localized periosteal or endosteal thickening of lateral cortex (beaking)

Minor Features (not required but supportive):

• Bilateral fractures or symptoms
• Delayed fracture healing
• Prodromal pain or symptoms
• Comorbid conditions (vitamin D deficiency, RA, hypophosphatasia)
• Bisphosphonate, glucocorticoid, or PPI use

These criteria help identify atypical fractures requiring modified management.

Physical Examination

General Findings:

• Shortened limb
• External rotation deformity
• Thigh swelling (significant blood loss)
• Unable to weight bear
• Ecchymosis (may be delayed)

Specific Assessment:

• Proximal fragment position assessment difficult clinically
• Note rotational deformity
• Check for angular deformity
• Assess soft tissue condition (open vs closed)

Neurovascular:

• Distal pulses (dorsalis pedis, posterior tibial)
• Sciatic nerve function
• Compartment assessment
• Motor/sensory exam of foot

Trauma Survey:

• ATLS for high-energy
• Ipsilateral injuries (floating knee)
• Spine clearance
• Chest/abdomen in polytrauma

Complete assessment identifies associated injuries requiring attention.

Warning Signs

Atypical Fracture Flags:

• Bisphosphonate use over 5 years
• Prodromal thigh pain before fracture
• Transverse pattern with lateral beaking on X-ray
• Contralateral thigh pain (check other side)

Pathological Flags:

• Known malignancy
• Minimal trauma mechanism
• Lytic lesion on X-ray
• Consider biopsy before definitive fixation

Red flags warrant urgent action or modified treatment approach.

Radiographic Assessment

Essential X-rays:

• Full-length femur (AP and lateral) - MUST see hip and knee
• AP pelvis - for comparison and proximal extent
• Contralateral femur - if atypical suspected

Key Assessment Points:

• Fracture pattern and comminution
• Proximal and distal extent
• Piriformis fossa involvement (Russell-Taylor)
• Canal diameter for nail sizing
• Evidence of atypical features (lateral beaking)

CT Scan Indications:

• Complex fracture patterns
• Surgical planning for difficult cases
• Proximal extension assessment
• Pathological fracture evaluation

MRI/Bone Scan:

• Stress fracture evaluation
• Incomplete contralateral fracture assessment
• Pathological lesion characterization
• If metastatic disease suspected

Imaging selection depends on clinical suspicion and surgical planning needs.

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Atypical Fracture Investigation

Mandatory:

• Contralateral femur X-ray (bilateral in 28%)
• Consider MRI if incomplete fracture suspected

Metabolic Workup:

• Vitamin D level
• Calcium
• PTH
• Bone turnover markers (P1NP, CTX)
• Phosphate

Endocrinology Referral:

• Bone health optimization
• Alternative osteoporosis treatment
• Monitoring during healing

Comprehensive workup is essential for atypical fracture management.

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Surgical Planning

Essential Measurements:

• Canal diameter at isthmus (for nail sizing)
• Length of femur (for nail length)
• Neck-shaft angle
• Entry point assessment

Classification Review:

• Russell-Taylor for entry point
• Seinsheimer for pattern complexity
• Plan reduction strategy based on pattern

Equipment Planning:

• Long cephalomedullary nail
• Reduction aids (clamps, K-wires, cerclage)
• Blocking screw set
• Fracture table vs radiolucent table
• Fluoroscopy C-arm

Thorough preoperative planning improves surgical outcomes.

Core Management Principles

Goals of Treatment:

• Anatomic alignment (length, rotation, axis)
• Stable fixation allowing early mobilization
• Preserve biology where possible
• Address underlying cause (if pathological or atypical)

Reduction Strategy:

• Match leg position to proximal fragment (flex, abduct, slight ER)
• Hip flexion 30-60 degrees on fracture table
• Abduct leg to match abducted proximal fragment
• Use blocking screws for coronal plane control
• Accept slight valgus, NEVER varus

Core principles guide all management decisions for subtrochanteric fractures.

Implant Options

Cephalomedullary Nail (Gold Standard):

• Load-sharing device
• Resists bending moments effectively
• Short lever arm to fracture
• Allows early weight-bearing
• Long nail preferred (spans entire femur)

Entry Point Selection:

• Piriformis entry: Russell-Taylor Type I only
• Trochanteric entry: Type II (required) or any type
• Most modern nails designed for trochanteric entry
• Entry point is nail-specific

Nail Selection:

• Long nail preferred - protects entire femur, prevents distal stress riser
• Short nail only if truly isolated subtrochanteric (rare)
• Appropriate diameter for canal
• Static locking for comminuted patterns

Plate Fixation (NOT First-Line):

• Reserved for salvage/revision
• Higher failure rates historically
• Blade plate or proximal femoral locking plate
• Load-bearing = more complications

Implant selection is critical for successful fixation of subtrochanteric fractures.

Operative Steps

Positioning:

• Fracture table (supine) - most common
• Lateral decubitus - better reduction control
• Radiolucent table with manual traction

Reduction Technique (THE KEY):

1. Traction for length
2. Flex hip 30-60 degrees (neutralize iliopsoas)
3. Abduct leg (align with proximal fragment)
4. Slight external rotation if needed
5. Confirm reduction on AP and lateral BEFORE reaming
6. Use blocking screws if coronal plane unstable

Nail Insertion:

1. Entry point (trochanteric or piriformis per nail design)
2. Guidewire placement - confirm across fracture with reduction
3. Sequential reaming (2mm increments)
4. Nail insertion maintaining reduction
5. Proximal locking (lag screw or blade)
6. Distal locking (static for comminuted, dynamic if simple)

Systematic technique with reduction confirmation ensures optimal outcomes.

Blocking (Poller) Screws

Principle:

• Narrow the medullary canal
• Force nail/wire into correct trajectory
• Essential for coronal and sagittal plane control

Placement Rules:

• Place in the short fragment
• Place on the concave side of deformity
• Anterolateral for procurvatum (flexion deformity)
• Medial for varus tendency

When to Use:

• Wide medullary canal
• Difficult closed reduction
• Coronal plane instability
• Oblique fracture patterns
• Prevention of varus malunion

Blocking screws are an essential tool for achieving accurate alignment.

Atypical Fracture Specifics

Preoperative:

• Stop bisphosphonates immediately
• Image contralateral femur
• Vitamin D and calcium optimization
• Endocrinology referral

Surgical Considerations:

• Often require open reduction (cortices don't slide)
• Healing may be delayed
• Consider bone graft (local or RIA)
• Ensure secure proximal and distal fixation

Adjuncts:

• Bone graft (iliac crest or reamer-irrigator-aspirator)
• Teriparatide (PTH analog) postoperatively
• Vitamin D supplementation
• Calcium supplementation

Contralateral Incomplete Fracture:

• Prophylactic nailing if stress fracture present
• Protected weight-bearing if prodrome only
• Close monitoring with serial imaging

Atypical fractures require comprehensive management addressing underlying bone health.

Postoperative Care

Weight-Bearing:

• WBAT for simple patterns with good fixation
• Toe-touch for comminuted/complex patterns
• Progress based on healing

DVT Prophylaxis:

• LMWH for 4-6 weeks (high-risk injury)
• Mechanical prophylaxis
• Early mobilization

Follow-Up Schedule:

• 2 weeks: Wound check, suture removal
• 6 weeks: X-ray, progress weight-bearing
• 3 months: Assess union
• 6 months: Confirm union

Atypical Fracture Follow-Up:

• Endocrinology involvement
• Consider teriparatide for healing
• Longer healing expected (counsel patient)
• Bone health optimization long-term

Structured postoperative care ensures optimal healing and early complication detection.

Cephalomedullary Nailing - Gold Standard

Patient Positioning:

• Fracture table (supine) preferred
• Alternative: Lateral decubitus for better reduction control
• Radiolucent table with manual traction acceptable

Entry Point Selection:

• Trochanteric entry: Most common, suitable for all patterns
• Piriformis entry: Only for Russell-Taylor Type I
• Entry point determines nail trajectory

Step-by-Step Technique:

1. Position patient with hip flexed 30-60 degrees
2. Abduct leg to match proximal fragment position
3. Reduce fracture under fluoroscopy
4. CONFIRM REDUCTION ON AP AND LATERAL BEFORE REAMING
5. Make incision over entry point
6. Open cortex with awl
7. Pass guidewire across fracture with reduction held
8. Ream in 2mm increments to 1-1.5mm above nail diameter
9. Insert nail maintaining reduction
10. Lock proximally (lag screw to femoral head)
11. Lock distally (static for comminuted, dynamic if simple)

The reduce-before-reaming principle is paramount for successful outcomes.

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Reduction Techniques and Adjuncts

Fracture Table Positioning:

• Hip flexion matches iliopsoas flexion of proximal fragment
• Abduction matches gluteal abduction
• External rotation as needed
• Traction provides length

Blocking (Poller) Screws:

• Place in short fragment
• Place in concavity of deformity
• Medial for varus tendency (most common)
• Anterolateral for procurvatum

Other Reduction Aids:

• Ball-spike pusher for percutaneous manipulation
• Schanz pins as joysticks for fragment control
• Cerclage wires for provisional or permanent holding
• Reduction clamps through limited open approach

Open Reduction Indications:

• Failed closed reduction
• Soft tissue interposition
• Atypical fractures (cortices don't slide)

Multiple tools and techniques available to achieve anatomic reduction.

Avoiding Common Errors

Varus Malunion Prevention:

• NEVER accept varus alignment
• Accept slight valgus if needed
• Use blocking screws proactively
• Re-reduce rather than accept malposition

Rotation Assessment:

• Compare cortical diameters
• Lesser trochanter profile
• Patella-tubercle alignment at completion
• Intraoperative CT if uncertain

Entry Point Errors:

• Too medial: Varus start
• Too lateral: Risk of iatrogenic fracture
• Wrong nail for entry point: Malalignment

Length Assessment:

• Compare to contralateral femur
• Templating preoperatively
• Accept 1cm shortening in elderly if necessary

Technical errors are preventable with systematic approach and attention to detail.

Intraoperative Complications

Malreduction (Most Common and Preventable):

• Varus alignment (NEVER accept)
• Procurvatum (flexion deformity)
• Rotational malreduction
• Prevention: Reduce BEFORE reaming

Iatrogenic Fracture:

• Entry point fracture
• Distal fracture during nail insertion
• Prevention: Adequate reaming, correct entry point
• May need additional fixation

Hardware Malposition:

• Lag screw malpositioning
• Short nail creating stress riser
• Inadequate distal locking

Intraoperative complications are largely preventable with careful technique.

Early Complications

Nonunion (10-20% historically):

• Improved with modern cephalomedullary nails
• Risk factors: Comminution, infection, varus, atypical
• Treatment: Exchange nailing with bone graft

Malunion:

• Varus most common
• Mechanical axis deviation
• May require corrective osteotomy

Implant Failure:

• Nail breakage at fracture site
• Lag screw cutout (less common than IT fractures)
• Usually related to nonunion

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Infection:

• Under 1% for closed fractures
• Higher for open fractures
• Treatment: Debridement, antibiotics, possible implant exchange

Early recognition and intervention prevents progression of complications.

Late Complications

Chronic Pain:

• Thigh pain from nail
• May require nail removal after union
• Heterotopic ossification around entry point

Limb Length Discrepancy:

• From malreduction or bone loss
• Shoe lift if under 2cm
• Lengthening if severe

Refracture:

• After implant removal
• Stress riser at screw holes
• Delay removal 18-24 months post-union

Functional Limitation:

• Hip stiffness
• Knee stiffness (if associated injury)
• Abductor weakness from approach

Late complications impact long-term quality of life and may require intervention.

Immediate Postoperative (Days 0-14)

Wound Management:

• Check surgical wounds at 48 hours
• Remove drains at 24-48 hours when output is below 50mL
• Wound inspection at 2 weeks for suture removal

DVT Prophylaxis:

• Chemical prophylaxis for minimum 4-6 weeks
• LMWH preferred (enoxaparin 40mg daily)
• Mechanical prophylaxis with TED stockings and intermittent pneumatic compression

Mobilization:

• Physiotherapy commencing day 1 postoperatively
• Weight-bearing status dependent on fracture pattern and fixation stability
• Most CMN fixation allows touch weight-bearing or weight-bearing as tolerated
• Comminuted or unstable patterns may require protected weight-bearing for 6-8 weeks

Analgesia:

• Multimodal analgesia regimen
• Wean opioids as tolerated
• Consider regional blocks for enhanced recovery

Early mobilization reduces complications and improves outcomes in elderly patients.

Weeks 2-12

Clinical Review:

• 2-week wound check and X-ray
• 6-week clinical and radiological review
• 12-week assessment for progression to full weight-bearing

Radiological Monitoring:

• Serial X-rays at 6 and 12 weeks
• Assess for callus formation and implant position
• Look for signs of varus collapse or implant failure

Rehabilitation:

• Progressive strengthening exercises
• Range of motion exercises for hip and knee
• Gait training with progression of weight-bearing status
• Hydrotherapy when wound healed

Red Flags:

• Increasing pain (suggests nonunion or hardware failure)
• Wound complications
• Progressive shortening (varus collapse)
• New onset thigh pain (implant irritation or failure)

Regular follow-up allows early detection of complications and timely intervention.

3-12 Months and Beyond

Union Assessment:

• Clinical: Ability to bear full weight without pain
• Radiological: Bridging callus on 3 cortices
• Average union time 4-6 months

Return to Activities:

• Light activities at 3 months
• Full unrestricted activities once united
• High-impact activities may be limited long-term
• Driving typically permitted at 6-8 weeks if right-sided and automatic

Long-term Follow-up:

• Annual review until considering implant removal
• Assess for leg length discrepancy
• Monitor for late complications

Implant Removal:

• Not routinely recommended
• Consider if symptomatic (thigh pain, prominent hardware)
• Delay minimum 18-24 months post-union
• Warn of refracture risk through screw holes

Long-term outcomes depend on achieving anatomical reduction and stable fixation.