High Yield Overview

PROXIMAL FEMORAL NAIL (CEPHALOMEDULLARY NAIL) FOR INTERTROCHANTERIC FRACTURE

Percutaneous greater trochanter entry with minimal incision | intermediate

Critical Danger Structures

Superior Gluteal Nerve & Vessels

Location: Exit sciatic notch 3-5cm proximal to greater trochanter tip, run between gluteus medius and minimus

Protection: Keep entry point at or below tip of greater trochanter. Avoid proximal dissection beyond 3cm above GT. Split gluteal muscles in line with fibers only.

Sciatic Nerve

Location: Exits pelvis through greater sciatic notch, ~5cm posterior to greater trochanter at level of hip joint

Protection: Avoid excessive posterior dissection. No retractors placed posteriorly. Careful with fracture manipulation in external rotation. Monitor sciatic nerve function post-operatively.

Medial Femoral Circumflex Artery

Location: Medial aspect of femoral neck, gives retinacular vessels supplying femoral head (posterior-superior branch most important)

Protection: Minimize soft tissue stripping around fracture. Careful guidewire and cephalic screw placement - stay intraosseous. Avoid multiple screw attempts.

Lateral Femoral Cutaneous Nerve

Location: Crosses ASIS, runs lateral to sartorius, highly variable course anterior to hip

Protection: Percutaneous technique with minimal anterior dissection. Small skin incision. Blunt dissection only when necessary. Incision centered over GT avoids LFCN.

Abductor Mechanism (Gluteus Medius/Minimus)

Location: Insert onto greater trochanter (medius - lateral facet, minimus - anterior facet)

Protection: Split muscles in line with fibers. Avoid excessive lateral dissection. Entry point at tip or just medial prevents splitting GT and disrupting insertion. Repair any significant tears.

Mnemonic

TAD PLUSTAD PLUS - Essential Cephalic Screw Checks

Mnemonic

SHORT vs LONGSHORT vs LONG - Nail Selection Decision

Positioning and Preparation

Patient Position: Supine on fracture table with traction. Affected leg in boot with traction apparatus. Unaffected leg abducted in hemilithotomy position or leg holder, or extended and abducted on leg support. Perineal post well-padded with gel pad to prevent pudendal nerve injury. C-arm positioned between legs for optimal AP and lateral views without repositioning.

Surgical Approach: Percutaneous greater trochanter entry with minimal incision

Incision: 5cm longitudinal incision over greater trochanter tip, centered and extending proximally

Indications

Absolute Indications

Unstable intertrochanteric fractures (AO 31-A2.2, A2.3, A3)
Reverse obliquity fractures (medial cortex proximal)
Intertrochanteric fractures with subtrochanteric extension
Pathological intertrochanteric fractures
Ipsilateral femoral neck and shaft fractures

Relative Indications

Stable intertrochanteric fractures (AO 31-A1, A2.1) in young patients
Failed Dynamic Hip Screw requiring conversion
Lateral wall thickness less than 20mm
Severely osteoporotic bone requiring better load sharing

Contraindications

Absolute:

Active infection at surgical site
Inadequate bone stock precluding screw fixation (consider arthroplasty)
Severe medical comorbidities precluding surgery

Relative:

Previous ipsilateral femoral instrumentation
Severe deformity preventing nail passage
Very narrow femoral canal (less than 8mm)

Pre-operative Planning

Imaging Assessment

AP pelvis: Assess fracture pattern, measure lateral wall thickness, check for pelvic ring injury
AP and lateral hip: Classify fracture (AO classification), assess comminution, measure neck-shaft angle
Contralateral hip: Template nail size, assess normal anatomy for comparison
Full-length femur: Rule out shaft extension, plan nail length

Critical Measurements

Lateral wall thickness: Measure perpendicular distance from lateral cortex to fracture line at level of lesser trochanter. Less than 20mm indicates unstable pattern requiring long nail
Neck-shaft angle: Normal 125-135°. Pre-operative varus indicates need for careful reduction
Femoral canal diameter: Measure at isthmus on contralateral side to select nail diameter
Femoral length: Compare to contralateral for length assessment

Nail Selection

Short nail: 170-240mm for isolated intertrochanteric fractures with intact lateral wall
Long nail: 340-420mm for subtrochanteric extension, lateral wall comminution, reverse obliquity
Diameter: Typically 10-11mm based on isthmus diameter
Screw vs Blade: Helical blade for osteoporotic bone (better purchase), screw for better bone

Operative Technique - Detailed Steps

Step 1: Setup & Closed Reduction

Setup & Closed Reduction: Position patient supine on fracture table. Apply gel padding to perineal post. Place affected limb in boot with traction apparatus. Unaffected leg in hemilithotomy or extended position. Prepare and drape in standard fashion. Apply gentle longitudinal traction (typically 10-20kg). Internally rotate leg 10-15° to correct typical external rotation deformity of distal fragment. Use fluoroscopy to assess reduction on AP and lateral views.

Acceptable Reduction:

Anatomic or slight valgus alignment (5-10° valgus acceptable, varus NOT acceptable)
Restoration of medial cortical continuity (medial support critical)
No posterior sag on lateral view (apex posterior deformity increases malunion risk)
Rotation corrected (internally rotate 10-15° typically)

If closed reduction fails: Consider percutaneous joystick with Schanz pin in greater trochanter for manipulation. Alternatively, small incision for pointed reduction clamp on medial cortex. Accept imperfect reduction if medial support achieved - anatomic reduction not always possible in comminuted fractures.

Exam Pearl

Technical Tip: EXAM KEY: 'I position patient on fracture table with well-padded perineal post. I apply longitudinal traction and internally rotate the leg 10-15° to correct the typical external rotation deformity. On fluoroscopy, I accept anatomic or slight valgus alignment - varus is NOT acceptable as it increases cut-out risk. Restoration of medial cortical support is CRITICAL for stability. No posterior sag on lateral view. If closed reduction fails, I use percutaneous Schanz pin joystick in GT for manipulation.'

Dangers at this step

Over-distraction causing difficulty with nail passage and increased non-union risk
Persistent varus malreduction - MAJOR risk factor for cut-out
Posterior sag causing apex posterior deformity and malunion
Pudendal nerve compression from poorly padded perineal post (numbness, pain)
Femoral neck fracture from excessive or forceful manipulation
Sciatic nerve injury from external rotation force

Step 2: Incision & Entry Point

Incision & Entry Point: Palpate greater trochanter (GT) tip - most prominent lateral point. Make 5cm longitudinal skin incision centered over tip of GT, extending proximally along femur. Incise subcutaneous tissue with electrocautery. Incise fascia lata (iliotibial band) in line with skin incision. Split gluteus medius and minimus fibers bluntly in line with muscle fibers - avoid excessive splitting.

ENTRY POINT CRITICAL:

Trochanteric entry nail (most modern nails): At tip of GT or just medial (2-3mm medial to tip)
Piriformis entry nail: Piriformis fossa, approximately 1cm medial to GT tip

Fluoroscopic Confirmation:

AP view: Entry point at tip of GT or just medial. NOT lateral to GT (causes varus). NOT too medial (risks medial cortex perforation or valgus)
Lateral view: Entry point MUST be in line with center of femoral canal. Too anterior causes anterior cortex perforation. Too posterior causes posterior perforation or difficulty passing nail

Exam Pearl

Technical Tip: EXAM KEY: 'I make 5cm longitudinal incision over the tip of the greater trochanter. Entry point is CRITICAL for preventing malalignment. For trochanteric entry nails, I aim for the tip of GT or 2-3mm medial on AP view. On LATERAL view, the entry point MUST be aligned with the center of the femoral canal - this is equally important. Too lateral an entry causes varus malalignment. Too medial risks medial cortex perforation. I confirm entry point on BOTH AP and lateral fluoroscopy before creating the portal.'

Dangers at this step

Entry too lateral = varus malalignment (common error)
Entry too medial = valgus or medial cortex perforation
Entry too anterior = anterior cortex perforation, nail prominence
Entry too posterior = posterior perforation, difficulty seating nail
Superior gluteal nerve injury if dissection extends more than 3cm proximal to GT
Iatrogenic femoral neck fracture from improper entry point or technique
Splitting of greater trochanter damaging abductor insertion

Step 3: Entry Portal Creation

Entry Portal Creation: Use T-handle awl or powered entry reamer to create entry portal. For trochanteric entry, open cancellous bone of GT tip. For piriformis entry, find piriformis fossa medial to GT. Hold awl/reamer perpendicular to lateral cortex, advance with controlled force through lateral cortex into medullary canal. Confirm on fluoroscopy - tool should advance toward center of femoral canal on lateral view. Feel for cortical breakthrough distally indicating entry into medullary canal. Do not force - use gentle rotational movements.

Exam Pearl

Technical Tip: EXAM KEY: 'I use T-handle awl or powered entry reamer to create the entry portal. I hold the instrument perpendicular to the lateral cortex and advance with controlled force. On lateral fluoroscopy, I confirm the trajectory is toward the center of the femoral canal, not anterior or posterior. I feel for cortical breakthrough indicating entry into the medullary canal. Proper entry portal prevents malalignment and cortical perforation.'

Dangers at this step

Anterior or posterior cortex perforation if trajectory wrong
Creating false passage outside medullary canal
Splitting or fracturing the greater trochanter
Damage to abductor insertion on GT
Femoral neck fracture from excessive force
Propagation of fracture pattern

Step 4: Guidewire Passage & Reduction Confirmation

Guidewire Passage & Reduction Confirmation: Select ball-tipped guidewire (typically 3mm diameter). Insert guidewire through entry portal into medullary canal. Advance with gentle rotational movements to help cross fracture site into distal fragment. Guide wire trajectory using fluoroscopy - aim for CENTER of canal on both AP and lateral views. At fracture site, wire should be central - eccentric wire leads to eccentric nail placement.

Guidewire Position Check:

At entry: Central in proximal fragment
At fracture site: Central position maintained
Distally: Central in medullary canal, parallel to cortices
Final position: Terminate 3-4cm above knee joint

Confirm fracture reduction maintained after wire passage. If reduction lost during wire passage, remove wire, re-reduce, and pass wire again. Do not proceed with poor reduction.

Exam Pearl

Technical Tip: EXAM KEY: 'I pass a ball-tipped guidewire across the fracture using gentle rotational movements. The wire MUST be central on both AP and lateral views - eccentric wire placement leads to eccentric nail position and malalignment. I check wire position at entry, at fracture site, and distally. I confirm the fracture reduction is maintained after wire passage. The wire terminates 3-4cm above the knee joint to allow nail length measurement.'

Dangers at this step

Guidewire takes false passage outside medullary canal
Eccentric wire placement causing eccentric nail and malalignment
Loss of fracture reduction during wire passage
Distal anterior cortex perforation (common if wire too anterior)
Wire advancement into knee joint causing pain and cartilage damage
Wire advancement too far preventing subsequent steps
Fracture distraction from wire passage

Step 5: Nail Length Measurement & Selection

Nail Length Measurement & Selection: With guidewire in final position, measure nail length from entry point to distal extent. Use measuring device or ruler on fluoroscopy with magnification correction.

Nail Length:

Short nail: 170-240mm, terminating in metaphyseal region. Typical length 220-240mm
Long nail: 340-420mm, terminating 3-4cm above knee joint. Typical length 360-380mm

Short vs Long Decision:

SHORT nail: Stable patterns (AO 31-A1, A2.1), intact lateral wall more than 20mm, no subtrochanteric extension
LONG nail: Unstable patterns, lateral wall comminution less than 20mm, subtrochanteric extension, reverse obliquity, pathological fractures

Nail Diameter: Based on canal diameter at isthmus. Typical 10-11mm. Ream 1-1.5mm over nail diameter.

Mark nail insertion depth on guidewire with depth gauge or marker.

Exam Pearl

Technical Tip: EXAM KEY: 'I measure nail length to terminate appropriately - for short nail in metaphyseal region, for long nail 3-4cm above knee joint line. My decision for SHORT vs LONG nail is based on: lateral wall thickness (less than 20mm requires long nail), subtrochanteric extension (requires long nail), fracture pattern stability (reverse obliquity requires long). SHORT nail for stable intertrochanteric fractures with intact lateral wall. Nail diameter selected based on isthmus diameter, typically 10-11mm. I will ream 1-1.5mm over nail diameter.'

Dangers at this step

Nail too short = stress riser at nail tip, risk of distal femur fracture
Nail too long = impingement on knee joint, anterior knee pain
Wrong nail type for fracture pattern (short for unstable = high failure risk)
Nail diameter too large = intraoperative fracture during insertion
Nail diameter too small = inadequate stability, increased risk of implant failure

Step 6: Reaming (if indicated)

Reaming Decision: REAMED vs UNREAMED. Most intertrochanteric fractures are REAMED for better cortical contact and rotational stability.

REAMED technique:

Sequential flexible reamers over guidewire
Start 1mm larger than canal diameter at isthmus
Increase in 0.5mm increments
Final reamer diameter 1-1.5mm larger than nail diameter
Ream to cortical chatter (feel vibration indicating cortical contact)
Copious irrigation during reaming to prevent heat necrosis
Monitor guidewire position continuously - prevent advancement

UNREAMED: Reserved for severe chest injury (fat embolism concern), very comminuted fractures, or bleeding disorders

Exam Pearl

Technical Tip: EXAM KEY: 'For intertrochanteric fractures, I typically REAM the femoral canal as this provides better cortical contact and rotational stability compared to unreamed technique. I use sequential flexible reamers over the guidewire in 0.5mm increments. I ream to 1-1.5mm over the final nail diameter. I ream to cortical chatter which I can feel as vibration through the reamer. Critical steps: copious irrigation to prevent heat necrosis, continuously monitor guidewire position to prevent advancement. I would only use UNREAMED technique in specific circumstances like severe pulmonary injury where fat embolism is a major concern.'

Dangers at this step

Fat embolism syndrome from reaming (more common with long nails, bilateral procedures)
Heat necrosis of bone without adequate irrigation
Guidewire advancement or loss of position during reaming
Cortical perforation with overly aggressive reaming
Fracture propagation distally from reaming forces
Intraoperative fracture if reaming too large

Step 7: Nail Insertion

Nail Insertion: Mount nail on insertion jig/handle according to manufacturer instructions. Ensure nail orientation is CORRECT - anteroposterior curvature should match femoral bow (apex anterior). Check nail is fully seated on jig. Insert nail over guidewire with gentle rotational movements (clockwise/counterclockwise) and controlled mallet blows to advance. Do not use excessive force.

Insertion Depth:

Nail should be flush with GT tip or 5-10mm proud (above tip)
NEVER bury nail below GT tip - makes removal extremely difficult
Confirm depth on lateral fluoroscopy

Position Check:

AP view: Nail centered in medullary canal, appropriate rotation
Lateral view: Nail centered, no anterior or posterior perforation, correct depth at entry
At fracture site: Nail crosses fracture centrally, reduction maintained
Distally: Nail centered in canal

Exam Pearl

Technical Tip: EXAM KEY: 'I mount the nail on the insertion jig ensuring correct orientation - the anteroposterior curvature must match the femoral bow with apex anterior. I insert the nail over the guidewire using gentle rotational movements and controlled mallet blows. I advance to predetermined depth - the nail should be flush with or 5-10mm proud of the GT tip. I specifically do NOT bury the nail below the GT tip as this makes future removal extremely difficult if needed. I confirm position on AP and lateral fluoroscopy - the nail should be centered in the canal on both views with no cortical perforation.'

Dangers at this step

Nail inserted backwards (wrong orientation) causing malalignment
Nail buried too deep below GT = extremely difficult removal
Nail left too proud = prominent hardware, abductor irritation
Anterior cortex perforation if nail curvature doesn't match femoral bow
Posterior perforation if entry too posterior
Fracture distraction if nail too long proximally or impacting at fracture
Loss of reduction during nail insertion
Splitting of proximal fragment

Step 8: Cephalic Screw/Blade Insertion - CRITICAL STEP

Cephalic Screw/Blade Insertion: This is the MOST CRITICAL step for preventing cut-out.

Guidewire Placement:

Using targeting jig attached to nail, insert guidewire for cephalic screw
Angle typically 130-135° from femoral shaft (CCD angle)
TARGET POSITION: Center-center or inferior-center in femoral head on BOTH AP and lateral
Think 3x3 grid: on AP (superior/center/inferior), on lateral (anterior/center/posterior)
CENTER-CENTER is optimal
INFERIOR-CENTER is acceptable
AVOID superior position - highest cut-out risk

Depth:

Aim for DEEP placement: 5-10mm from subchondral bone on ALL views
Measure on both AP and lateral fluoroscopy
Too shallow = inadequate purchase, cut-out risk
Too deep or penetration = joint damage

Tip-Apex Distance (TAD) - CRITICAL:

Measure distance from tip of screw to apex of femoral head on AP radiograph
Measure same distance on lateral radiograph
SUM these distances (after correcting for magnification)
TAD MUST BE LESS THAN 25mm
TAD greater than 25mm = exponentially increased cut-out risk

Screw Insertion:

Ream over guidewire to measured depth
For helical blade: insert to predetermined depth, compress if system allows
For lag screw: insert to depth, typically 85-95mm length depending on head size
Confirm final position on AP and lateral
Recheck TAD calculation
Confirm no joint penetration

Exam Pearl

Technical Tip: EXAM KEY: 'Cephalic screw position is THE MOST CRITICAL factor for preventing cut-out. I aim for CENTER-CENTER or INFERIOR-CENTER position in the femoral head on BOTH AP and lateral views. I specifically AVOID superior placement which has the highest cut-out risk. Deep placement is essential - I aim for 5-10mm from subchondral bone on all views. The TIP-APEX DISTANCE is the single most important measurement - I calculate this by summing the distance from screw tip to apex of head on AP and lateral radiographs. TAD MUST be less than 25mm. Studies show TAD less than 25mm has 6% cut-out rate, while TAD greater than 25mm increases cut-out exponentially. I use calibrated ruler or measurement tool to ensure accuracy.'

Dangers at this step

Superior-posterior placement = HIGHEST cut-out risk (avoid at all costs)
TAD greater than 25mm = exponentially increased cut-out rate
Joint penetration causing cartilage damage and early arthritis
Anterior perforation of femoral neck (check lateral view)
Posterior perforation of neck (check lateral view)
Screw too short = poor purchase, cut-out risk
Screw too long = joint penetration
Iatrogenic femoral neck fracture from screw insertion or multiple attempts
Z-effect or reverse Z-effect (screw backs out with loading)

Step 9: Distal Locking

Distal Locking: Purpose is to control rotation and length. Decision: static vs dynamic locking.

Short Nail:

Typically ONE or TWO static distal locking screws through targeting jig
Insert through stab incisions
Confirm position with fluoroscopy - screws must pass through nail
Bicortical purchase essential

Long Nail:

STATIC locking (2 screws - distal and middle holes): For subtrochanteric involvement, unstable patterns, need for rigid fixation
DYNAMIC locking (1 screw - distal hole only): For pure intertrochanteric fractures, allows axial compression at fracture site

Technique:

Confirm screw trajectory through targeting jig or freehand with fluoroscopy
Drill through both cortices
Measure screw length with depth gauge
Insert screws to engage both cortices
Confirm on fluoroscopy: screws through nail, bicortical engagement

Exam Pearl

Technical Tip: EXAM KEY: 'For distal locking, my decision is between static and dynamic. For SHORT nail, I use one or two static distal screws through the targeting jig. For LONG nail, I use STATIC locking with two screws (distal and middle holes) if there is subtrochanteric extension or unstable pattern requiring rigid fixation. I use DYNAMIC locking with one distal screw only for pure intertrochanteric fractures to allow axial compression at the fracture site which promotes healing. I confirm bicortical engagement and screws passing through nail on fluoroscopy.'

Dangers at this step

Screws miss nail holes (not engaging nail) = no rotational control
Unicortical purchase = inadequate stability and fixation
Screws too long = far cortex prominence, soft tissue irritation, possible vascular injury
Screws too short = loss of fixation
Wrong locking mode for fracture pattern (dynamic for unstable = loss of fixation)
Thermal necrosis if drilling without irrigation
Fracture at distal screw sites

Step 10: Final Assessment & Closure

Final Assessment & Closure: Remove guidewire. If helical blade system with compression capability, apply compression using set screw mechanism.

COMPREHENSIVE FINAL FLUOROSCOPY CHECK (Critical for exam):

Fracture reduction: Anatomic or slight valgus, medial cortical support restored, no posterior sag
Nail position: Centered in canal on AP and lateral, appropriate depth (flush or 5-10mm proud)
Cephalic screw: Center-center or inferior-center position, TAD less than 25mm, 5-10mm from subchondral bone, no joint penetration
Distal locking: Screws through nail, bicortical engagement
No cortical perforation: Check entire nail length on both views
Leg length: Compare to contralateral - should be within 1cm
Rotation: Compare to contralateral - patella should face forward with leg neutral

Release traction gradually and recheck fracture stability and alignment on fluoroscopy. Some settling is acceptable.

Copious saline irrigation. Close fascia lata with absorbable sutures. Close subcutaneous layer with absorbable sutures. Skin closure with staples or sutures. Sterile dressing.

Document final images for medical record - save AP and lateral showing all implants.

Exam Pearl

Technical Tip: EXAM KEY: 'My final assessment is comprehensive and systematic. I check: (1) Fracture reduction maintained with valgus acceptable and medial support, (2) Nail position centered and appropriate depth, (3) Cephalic screw position with TAD less than 25mm - this is critical, (4) Distal locking screws through nail, (5) No cortical perforation anywhere, (6) Leg length and rotation compared to contralateral. I release traction gradually to allow controlled settling and recheck alignment. I document final images for the medical record including views showing TAD measurement which is important medicolegally.'

Dangers at this step

Unrecognized joint penetration by cephalic screw
Malrotation (compare to contralateral limb carefully)
Leg length discrepancy (typically shortening with comminuted fractures)
Loss of reduction on traction release indicating instability
Persistent varus alignment (unacceptable - increases cut-out)
Unrecognized cortical perforation
Inadequate documentation

Exam Viva Scenarios

Practice these scenarios to excel in your viva examination

VIVA SCENARIOStandard

EXAMINER

"You're in the trauma meeting and presented with a 78-year-old female with an intertrochanteric hip fracture. The registrar suggests a dynamic hip screw. Walk me through your decision-making for fixation choice and specifically when you would use a cephalomedullary nail instead."

EXCEPTIONAL ANSWER

I would make my decision based on careful assessment of the fracture pattern and patient factors. First, I would classify the fracture using the AO/OTA system - A1 are stable two-part fractures, A2 are unstable with multiple fragments, and A3 are reverse obliquity patterns. The KEY factors favoring cephalomedullary nail over DHS are: (1) LATERAL WALL THICKNESS - if less than 20mm measured perpendicular from lateral cortex to fracture line at level of lesser trochanter, this indicates unstable pattern with high DHS failure risk requiring CMN. (2) REVERSE OBLIQUITY pattern where medial cortex is proximal - DHS will fail, CMN mandatory. (3) SUBTROCHANTERIC EXTENSION - any fracture line extending below lesser trochanter requires CMN. (4) Severe comminution of posteromedial cortex - loss of medial support favors CMN. For this patient, I would obtain AP pelvis and lateral hip X-rays, measure lateral wall thickness, assess fracture pattern, and if any of these high-risk features are present, I would proceed with cephalomedullary nail. A stable two-part fracture with intact lateral wall greater than 20mm could be treated with either, but CMN has shown lower revision rates in unstable patterns.

VIVA SCENARIOStandard

EXAMINER

"What is tip-apex distance, how do you measure it, and why is it the most important technical factor in cephalomedullary nailing?"

EXCEPTIONAL ANSWER

Tip-apex distance, or TAD, is the sum of the distances from the tip of the cephalic screw to the apex of the femoral head measured on BOTH the AP and lateral radiographs, after correcting for magnification. It was described by Baumgaertner in 1995 in a landmark study. To measure it: On the AP radiograph, I measure the distance from the screw tip to the apex of the femoral head - the apex being the most superior and medial point. I then measure the same distance on the lateral radiograph from screw tip to apex - the most superior and posterior point. I correct for magnification using the known diameter of the screw or nail, then SUM these two distances. The critical threshold is 25mm. TAD LESS than 25mm has a cut-out rate of approximately 6%, while TAD GREATER than 25mm increases cut-out risk exponentially. In Baumgaertner's study, there were NO cut-outs with TAD less than 25mm. This is the SINGLE MOST IMPORTANT technical factor because cut-out is the most common mechanical failure of cephalomedullary nails, occurring in 2-6% of cases. To achieve TAD less than 25mm, I need: (1) Center-center or inferior-center screw position on both views, (2) Deep placement 5-10mm from subchondral bone, (3) Adequate screw length, (4) Avoiding superior placement.

VIVA SCENARIOStandard

EXAMINER

"Your registrar calls you from theatre - they've inserted the cephalomedullary nail for an intertrochanteric fracture but on final imaging you see the cephalic screw tip-apex distance is 30mm with the screw positioned in the superior third of the femoral head on both views. What do you do and why is this a problem?"

EXCEPTIONAL ANSWER

This is a SIGNIFICANT problem that requires correction intraoperatively. TAD of 30mm is GREATER than the critical 25mm threshold, and superior positioning in both views places this in the highest risk quadrant for cut-out. I would NOT accept this and would revise it now. My approach: (1) I would thank the registrar for checking and explain this needs revision as TAD greater than 25mm increases cut-out risk exponentially and superior position has the highest failure rate in published studies. (2) I would remove the cephalic screw. (3) I would reassess the guidewire position and redirect to achieve CENTER-CENTER or INFERIOR-CENTER position on both AP and lateral views. (4) I would re-insert the screw aiming for deeper placement, 5-10mm from subchondral bone. (5) I would recalculate TAD aiming for less than 25mm - ideally 20-22mm. (6) I would confirm no joint penetration. Why is this problem: Superior positioning has the HIGHEST cut-out risk because (1) the subchondral bone is thinnest in the superior quadrant, (2) the loading forces are highest superiorly with weight bearing creating shear stress, (3) osteoporotic bone quality is worst superiorly. Combined with TAD greater than 25mm, this patient has extremely high cut-out risk - potentially 20-30% or higher. The clinical consequence would be progressive superior migration of the screw through the femoral head over 6-12 weeks, requiring revision to total hip arthroplasty. Prevention now is far better than revision later.

Proximal Femoral Nail - Exam Day Rapid Review

High-Yield Exam Summary

References

Baumgaertner MR, Curtin SL, Lindskog DM, Keggi JM. The value of the tip-apex distance in predicting failure of fixation of peritrochanteric fractures of the hip. J Bone Joint Surg Am. 1995;77(7):1058-1064. [Landmark study establishing TAD <25mm as critical predictor of cut-out]
FAITH Investigators. Fracture fixation in the operative management of hip fractures (FAITH): an international, multicentre, randomised controlled trial. Lancet. 2017;389(10078):1519-1527. [Level I RCT comparing sliding hip screw vs CMN for intertrochanteric fractures]
Parker MJ, Handoll HH. Gamma and other cephalocondylic intramedullary nails versus extramedullary implants for extracapsular hip fractures in adults. Cochrane Database Syst Rev. 2010;(9):CD000093. [Level I meta-analysis of CMN vs SHS]
Hsu CE, Shih CM, Wang CC, Huang KC. Lateral femoral wall thickness. A reliable predictor of post-operative lateral wall fracture in intertrochanteric fractures. Bone Joint J. 2013;95-B(8):1134-1138. [Level III study establishing lateral wall <20mm threshold]
Palm H, Jacobsen S, Sonne-Holm S, Gebuhr P; Hip Fracture Study Group. Integrity of the lateral femoral wall in intertrochanteric hip fractures: an important predictor of a reoperation. J Bone Joint Surg Am. 2007;89(3):470-475. [Level III prognostic study on lateral wall significance]
Kaufer H. Mechanics of the treatment of hip injuries. Clin Orthop Relat Res. 1980;(146):53-61. [Classic biomechanical analysis of hip fracture fixation]
Streubel PN, Moustoukas MJ, Obremskey WT. Mechanical failure after intramedullary screw fixation of unstable intertrochanteric femur fractures. J Orthop Trauma. 2013;27(1):e1-e6. [Level IV case series analyzing mechanical failures and TAD]
Australian and New Zealand Hip Fracture Registry (ANZHFR) Steering Group. Australian and New Zealand Guideline for Hip Fracture Care: Improving Outcomes in Hip Fracture Management of Adults. Sydney: Australian and New Zealand Hip Fracture Registry Steering Group; 2014. [Australian clinical practice guideline]
Mereddy P, Kamath S, Ramakrishnan M, Malik H, Donnachie N. The AO/ASIF proximal femoral nail antirotation (PFNA): a new design for the treatment of unstable proximal femoral fractures. Injury. 2009;40(4):428-432. [Level IV case series on helical blade design]
National Institute for Health and Care Excellence (NICE). Hip fracture: management. Clinical guideline [CG124]. London: NICE; 2011 (updated 2017). [Clinical practice guideline on hip fracture management including orthogeriatric care]

Proximal Femoral Nail (Cephalomedullary Nail) for Intertrochanteric Fracture