Subtrochanteric Femoral Fracture Fixation

Surgical Indications

Absolute Indications

• Displaced subtrochanteric femoral fracture (within 5 cm distal to the lesser trochanter) in an adult — virtually all displaced fractures in this region require surgical fixation due to the powerful deforming forces and poor outcomes with non-operative treatment
• Open subtrochanteric fracture — surgical fixation after wound debridement and antibiotic therapy
• Polytrauma with femoral shaft or subtrochanteric fracture — early fixation for damage control and mobilisation
• Pathological subtrochanteric fracture (metastatic disease) — stabilisation for pain relief and mobilisation
• Impending pathological fracture (cortical breach greater than 50 percent with pain) — prophylactic fixation before completion

Relative Indications

• Atypical bisphosphonate-related subtrochanteric fracture with prodromal pain and radiographic cortical changes — prophylactic cephalomedullary nailing to prevent completion
• Non-united subtrochanteric fracture after previous failed fixation — revision with exchange nailing or plate augmentation
• Periprosthetic fracture around a well-fixed femoral stem with subtrochanteric extension — requires specific implant strategies

Contraindications

Absolute:

• Patient unfit for anaesthesia due to severe medical comorbidity or terminal illness where the burden of surgery exceeds the benefit
• Active deep infection at the surgical site (not an open fracture with contamination — that is a different scenario requiring staged treatment)

Relative:

• Very poor bone stock with no restorable medial cortex — consider plate-based construct with medial augmentation or megaprosthesis in elderly patients
• Ipsilateral femoral neck fracture plus subtrochanteric extension — may require separate cervical fixation or a reconstruction-type nail with separate neck screw capability

Russell-Taylor Classification

The Russell-Taylor classification (1986) guides implant selection based on whether the piriformis fossa and the lesser trochanter/medial cortex are involved:

Clinical significance: Type I fractures allow a standard piriformis entry antegrade nail, which provides the best biomechanical axis. Type II fractures destroy the piriformis fossa and require either a trochanteric entry nail (entered at the tip of the greater trochanter, slightly medial) or a plate-based construct. The sub-classification by lesser trochanter involvement (A vs B) reflects the integrity of the medial cortex — Type IB and IIB fractures have medial disruption and higher nonunion rates.

Evidence for Implant Selection

Cephalomedullary (Intramedullary) Nail vs Plate Fixation

Cephalomedullary nail (implant of choice):

• Load-sharing device that exploits the femoral canal biomechanics
• Minimally invasive insertion with percutaneous technique
• Allows immediate distal interlocking for rotational and axial stability
• Long reconstruction nails (up to 480 mm) reach the distal femoral isthmus
• Proximal cephalomedullary locking screws at 130 degrees enter the femoral head/neck
• Biomechanically superior in cyclic loading compared to plate constructs
• Lower blood loss, shorter operative time, and lower infection rate than plate fixation in most series

95-degree blade plate (alternative):

• Provides fixed-angle fixation with a blade seated in the femoral neck
• Requires more extensive lateral soft-tissue dissection
• Better suited when the piriformis fossa is destroyed (Russell-Taylor Type II)
• Can be combined with cerclage wires for medial fragment control
• Direct visualisation of the fracture site for anatomical reduction
• Higher blood loss and infection risk compared to IM nailing
• Slower rehabilitation due to plate reliance on cortical contact

Dynamic condylar screw (DCS, 95 degrees):

• Similar indications to the blade plate but with a barrel/screw mechanism
• Allows compression across the fracture site after seating
• Bulkier and requires more lateral exposure than a blade plate
• Useful in distal subtrochanteric fractures extending towards the supracondylar region

Key Evidence

Deforming Forces in Subtrochanteric Fractures

The subtrochanteric region is one of the most mechanically demanding zones in the skeleton. The powerful muscular attachments to the proximal femur create characteristic displacements that must be understood and deliberately corrected before fixation.

Net deformity: The proximal fragment is flexed, abducted and externally rotated. The distal fragment is adducted and relatively extended. The fracture line angulates with its apex pointing anterolaterally — hence the term "apex-anterolateral angulation."

Anatomical Landmarks for Surgical Approach

Greater Trochanter (Entry Point for Trochanteric Nails)

• The tip of the greater trochanter is the entry point for trochanteric entry cephalomedullary nails
• Palpable as the most proximal lateral prominence of the proximal femur
• The correct entry point is at the very tip, slightly medial on the slope (the "medial tip" of the trochanter)
• On AP fluoroscopy, the guidewire starting point should be colinear with the femoral shaft axis
• A starting point too far lateral creates varus; too far anterior creates procurvatum

Piriformis Fossa (Entry Point for Standard Antegrade Nails)

• Located at the base of the greater trochanter, medial to its tip, in the medial cortex just above the lesser trochanter
• Intact only in Russell-Taylor Type I fractures — check preoperative radiographs
• Entry here provides the most biomechanically aligned nail path along the femoral shaft axis
• Destroyed in Type II fractures, which necessitates an alternative approach

Lesser Trochanter and Medial Calcar

• The lesser trochanter is the insertion of the iliopsoas tendon
• Detachment or comminution of the lesser trochanter (Russell-Taylor Type IB, IIB) indicates loss of the medial cortical buttress
• The calcar femorale is the vertical dense bone of the posteromedial femoral neck extending into the medial subtrochanteric cortex — it is the primary load-bearing surface in the proximal femur
• Loss of calcar support dramatically increases the bending moment on any lateral plate or the nail itself at the fracture site

Vascular Anatomy

Medial Femoral Circumflex Artery (MFCA)

• The dominant blood supply to the femoral head in most individuals
• Runs along the inferior border of the obturator externus, then posterior to the femoral neck
• At risk during open reduction approaches that expose the medial femoral neck — avoid excessive dissection in this region when reducing subtrochanteric fractures

Lateral Femoral Circumflex Artery (LFCA)

• Ascending branch runs along the intertrochanteric line anteriorly
• Lateral approach to the subtrochanteric region (for plate fixation) dissects through the vastus lateralis and is relatively safe from major vascular injury
• The deep branch of the LFCA is encountered along the lateral femoral shaft and requires cautery during exposure

Profunda Femoris Artery

• Runs deep to the femoral sheath and gives off the medial and lateral femoral circumflex branches
• Large perforating branches cross the medial femoral shaft — at risk during open medial approaches or during excessive cerclage wire passage

Biomechanics of the Subtrochanteric Region

• The subtrochanteric femur is subjected to compressive loads estimated at 3-4 times body weight during normal gait and significantly higher during stair climbing
• The medial cortex (calcar) bears approximately 60-70 percent of the compressive load; the lateral cortex bears tensile stress
• Loss of medial cortical support shifts the load to the implant — plates in this scenario act as tension-band devices but are vulnerable to cyclical bending failure
• Intramedullary nails are load-sharing: the nail and the femoral cortex share the bending load, reducing the stress on the implant itself
• The lever arm from the femoral head to the fracture site creates enormous bending moments — the further proximal the fracture, the higher the bending stress at the fracture-implant interface

Positioning and Preparation

Patient position: Supine on a radiolucent fracture table or a radiolucent flat-top table with a femoral distractor. A well-padded perineal post on the fracture table provides counter-traction.

Fracture table (standard choice):

• The leg is placed in traction through a boot or skeletal pin (distal femoral or proximal tibial Steinmann pin)
• The perineal post is positioned carefully to avoid pudendal nerve compression and scrotal/labial injury
• The contralateral leg is flexed at the hip and knee, abducted on a well-leg holder, or flexed and positioned in a scissors position to allow lateral fluoroscopy

Radiolucent table with femoral distractor (alternative):

• Allows greater manoeuvrability for open reduction if required
• The femoral distractor is applied percutaneously via Schanz pins in the proximal and distal fragments
• Particularly useful for Russell-Taylor Type IIB fractures where open reduction of the medial cortex may be needed
• Does not provide the same longitudinal traction control as a fracture table

Fluoroscopy: A C-arm positioned from the contralateral side (in supine position) provides AP and lateral imaging of the proximal femur. Ensure the C-arm can rotate freely without hitting the fracture table or perineal post.

Anaesthesia: General or regional (spinal). Regional anaesthesia reduces pulmonary complication risk in elderly patients with chest trauma or comorbidity.

Antibiotic prophylaxis: Single dose of IV cefazolin 2 g at induction (or appropriate alternative based on local protocol and allergy status). Redose if operative time exceeds 4 hours.

Consent: Counsel regarding: infection (1-3 percent), malreduction (5-10 percent), nonunion (5-15 percent), implant failure (2-8 percent), iatrogenic fracture during surgery (1-3 percent), need for revision surgery, blood transfusion requirement, and the possibility of hardware removal in the future.

Step-by-Step Cephalomedullary Nailing Technique

Step 1: Preoperative Planning and Classification

Obtain AP pelvis and full-length femoral radiographs including the knee. Classify using the Russell-Taylor system. Measure the contralateral femoral neck-shaft angle for comparison postoperatively. Determine nail length and diameter using preoperative templates or calibrated radiographs.

Select the entry point based on classification: piriformis fossa for Type I fractures, greater trochanteric tip for Type II fractures. Check the canal diameter — distal reaming may be required if the isthmus is narrow relative to the nail.

Step 2: Positioning and Traction Application

Position the patient supine on the fracture table. Apply skeletal traction through a proximal tibial or distal femoral Steinmann pin. Apply longitudinal traction with the limb in slight adduction (to bring the greater trochanter forward for easier trochanteric entry). Internally rotate the limb to neutralise the natural femoral anteversion and align the distal fragment.

Adjust traction until the fracture fragments are brought out to length. Avoid over-traction, which widens the fracture gap and makes reduction harder.

Step 3: Entry Point Preparation

Make a 3-5 cm longitudinal incision centred on the tip of the greater trochanter (for trochanteric entry) or over the lateral aspect of the proximal thigh at the piriformis level (for piriformis entry).

For trochanteric entry: Split the gluteus maximus fibres in line with the incision. Identify the trochanteric bursa and excise it. Palpate the tip of the greater trochanter. Insert a guidewire (or a threaded Steinmann pin) at the very tip, slightly medial on the slope. Confirm on AP fluoroscopy that the wire is colinear with the femoral shaft axis.

For piriformis entry: Use a similar lateral approach but aim the wire into the piriformis fossa (confirmed on AP and lateral fluoroscopy as the centre of the medullary canal on both views).

Step 4: Fracture Reduction

With the guidewire in position (but before reaming), reduce the fracture. In most Type I fractures, closed reduction on the fracture table with traction and internal rotation is sufficient. Check reduction on AP and lateral fluoroscopy.

If closed reduction fails:

• Insert a Schanz pin percutaneously into the proximal fragment (via a stab incision over the lateral cortex of the greater trochanteric region). Use this pin as a joystick to control flexion, abduction and rotation of the proximal fragment.
• Apply a ball-spike pusher through a separate stab incision at the fracture site to lever the fragments into alignment.
• Use percutually placed pointed reduction clamps (e.g., Verbrugge clamps) to hold the reduction.
• For long oblique or butterfly fragments, place cerclage wires before reaming to hold the reduction.

Step 5: Guidewire Passage and Reaming

Pass the ball-tipped guidewire across the fracture site and down the femoral canal to the distal femur. Confirm central position on both AP and lateral fluoroscopy throughout its length.

Ream the canal progressively to 1-2 mm greater than the planned nail diameter. Use sharp reamers. Ream slowly to minimise thermal necrosis, particularly in the distal isthmus where the cortical contact is tightest. Irrigate during reaming if available. Check the guidewire position frequently to ensure it has not migrated or bent during reaming.

Step 6: Nail Insertion

Select a cephalomedullary nail of appropriate length (must extend past the fracture to the distal isthmus with room for at least two distal locking bolts) and diameter (1-2 mm less than the final reamer diameter). Mount the nail on the insertion jig.

Insert the nail over the guidewire using gentle mallet blows or a manual push. Do not use excessive force — resistance suggests a blockage at the fracture site (malreduction, residual fragment, or cortical breach). If resistance is met, stop, withdraw the nail, re-check the fracture reduction and guidewire position on fluoroscopy, and re-attempt.

Drive the nail to the correct depth: the proximal targeting jig should align the cephalomedullary locking screw trajectory towards the femoral head on AP fluoroscopy.

Step 7: Proximal Cephalomedullary Locking

Through the targeting jig, drill and insert the proximal cephalomedullary locking screws (typically 6.5 mm partially threaded lag screws at 130 degrees) into the femoral head and neck. Place at least one screw, and consider two in unstable patterns.

Confirm screw position on both AP and lateral fluoroscopy:

• AP view: the screw should be in the centre of the femoral head (zone 3 on the TAD method), with its tip within 5-10 mm of subchondral bone
• Lateral view: the screw should be in the centre of the femoral head (central quadrant), not anterior or posterior
• Tip-apex distance: less than 25 mm (ideally less than 20 mm) from the screw tip to the femoral head apex on both views combined

Step 8: Distal Interlocking

Using the freehand technique (if the distal targeting jig is unreliable at this length) or the targeting jig, place two distal interlocking bolts through the pre-drilled holes in the nail. Confirm position on AP and lateral fluoroscopy. A third distal bolt may be added in highly unstable fracture patterns or when there is significant comminution between the fracture and the distal lock.

Distal locking controls rotation and prevents axial shortening. It also reduces the bending stress on the nail at the fracture site by distributing load to the distal cortex.

Step 9: Final Assessment and Closure

Remove the traction and check the final reduction on AP and lateral fluoroscopy. Compare the neck-shaft angle with the contralateral side to detect varus or valgus. Check for any residual fracture gap, rotational malalignment (compare the cortical thickness pattern on AP view), and implant position.

Irrigate the wound. Close the fascia (if opened), subcutaneous tissue and skin in layers. Apply a sterile dressing.

Alternative Technique: 95-Degree Blade Plate

When to Use a Blade Plate

• Russell-Taylor Type II fractures where the piriformis fossa is destroyed and trochanteric entry nailing is not preferred
• When the medullary canal is obstructed by prior implants or deformity that prevents nail passage
• When open reduction and anatomical fixation of the medial cortex is required (Type IIB with extensive medial comminution)

Key Steps

1. Direct lateral approach to the proximal femur (Watson-Jones or modified Hardinge interval)
2. Split the vastus lateralis and retract anteriorly to expose the lateral femoral cortex
3. Reduce the fracture anatomically under direct vision — this is the key advantage of a plate approach
4. Place cerclage wires around comminuted medial or posterior fragments
5. Insert the 95-degree blade plate guide pin into the femoral neck at 130 degrees to the lateral cortex (parallel to the femoral neck axis on AP fluoroscopy)
6. Confirm guide pin position on AP and lateral views — tip should be within the subchondral bone of the femoral head, not penetrating the articular surface
7. Seat the blade (or screw for DCS) over the guide pin into the femoral neck
8. Apply the plate to the lateral cortex and secure with cortical screws distally
9. Apply compression across the fracture if the pattern allows (transverse or short oblique)
10. Confirm final reduction and fixation on fluoroscopy

Post-operative Protocol

Immediate Post-operative Period (Day 0-3)

• Analgesia: Multimodal — paracetamol, NSAIDs (if not contraindicated), short-course opioids, nerve block (femoral nerve block or adductor canal block for pain control)
• Thromboprophylaxis: Chemical VTE prophylaxis (low-molecular-weight heparin or factor Xa inhibitor) for a minimum of 2-6 weeks, extended to 4-6 weeks in patients with additional risk factors (previous VTE, obesity, malignancy)
• Mobilisation: Begin passive and active-assisted hip and knee range-of-motion exercises from day 1. Gentle seated exercises and bedside mobilisation as pain allows
• Wound care: Inspect at 48 hours. Suture or staple removal at 10-14 days

Weight-Bearing Progression

Weight-bearing after subtrochanteric fracture fixation depends on fracture pattern, bone quality, implant construct and reduction quality:

General principle: Earlier weight-bearing is encouraged when the fixation construct is stable and the bone quality is good. Prolonged non-weight-bearing is reserved for unstable patterns, osteoporotic bone with comminution, or revision surgery for nonunion.

Follow-up Schedule

• 2 weeks: Wound check, suture removal, confirm AP and lateral radiographs
• 6 weeks: Clinical and radiographic review — check for early callus, alignment maintenance, implant position
• 3 months: Clinical and radiographic review — assess progression of union; adjust weight-bearing as appropriate
• 6 months: Clinical and radiographic review — confirm union or identify delayed union/nonunion early
• 12 months: Final clinical and radiographic review — confirm union; discuss hardware removal if symptomatic

Special Case: Atypical Bisphosphonate-Related Fractures

Recognition

The American Society for Bone and Mineral Research (ASBMR) defined criteria for atypical femoral fractures (Shane et al., 2010):

Major features (all required for the designation):

• Fracture location in the subtrochanteric region or femoral diaphysis
• Prodromal deep thigh or groin pain (days to weeks before fracture)
• Minimal or no trauma (fracture occurs spontaneously or with low-energy fall)
• Transverse or short oblique fracture pattern
• Medial cortical spiking
• Non-comminuted or minimally comminuted

Minor features (support the diagnosis):

• Lateral cortical thickening (periosteal reaction or beaking) at the fracture site
• Bilateral involvement (check the contralateral femur in every case)
• Delayed healing (common — these fractures are biologically different from typical fractures)

Management

Drug management:

• Stop bisphosphonate therapy immediately upon recognition of an atypical fracture or prodrome
• Consider teriparatide (PTH analogue) — there is some evidence that teriparatide promotes fracture healing in this setting
• Calcium and vitamin D supplementation
• Endocrinology input for bone health optimisation

Surgical fixation:

• Cephalomedullary nailing is the fixation of choice — load-sharing, biological, and provides distal interlocking
• Plate fixation has a substantially higher failure rate in atypical fractures due to the poor bone quality and transverse fracture pattern (minimal area for plate-bone contact)
• Expect slower healing than a typical subtrochanteric fracture — protected weight-bearing for longer (often 3-6 months before full weight-bearing)

Prophylactic Fixation

When prodromal pain persists and radiographs show cortical thickening with a cortical breach of 50 percent or greater, prophylactic cephalomedullary nailing is indicated:

• Prevents a completed fracture and the associated morbidity (potential for displacement, need for emergency surgery, and prolonged recovery)
• The surgery is straightforward (prophylactic nail in intact bone) with lower complication rates than fixation of a completed fracture
• Intramedullary approach provides protection of the entire femoral shaft from further propagation

Cortical breach less than 50 percent without pain: monitor with serial radiographs, consider drug holiday, and review in 6-8 weeks. Do not operate in the absence of symptoms or significant cortical breach.

Cortical breach greater than 50 percent with pain: prophylactic cephalomedullary nailing recommended.

Special Case: Pathological Subtrochanteric Fractures

Metastatic Disease

The proximal femur is a common site for skeletal metastases (particularly breast, prostate, lung, renal and thyroid primaries). A pathological fracture in the subtrochanteric region requires stabilisation for pain control and mobilisation.

Management Principles

• Full-strength cemented cephalomedullary nailing when the canal is intact and sufficient proximal bone stock remains for screw fixation
• Consider endoprosthetic reconstruction when the proximal bone is destroyed beyond salvage
• Postoperative radiotherapy to the fracture site (typically 20-30 Gy in 5-10 fractions) to prevent tumour progression
• Multidisciplinary involvement: oncology, radiation oncology, and palliative care