Surgical technique guide for Retrograde Femoral Nailing - FRCS exam preparation
Reviewed by OrthoVellum Editorial Team
Orthopaedic clinicians and medical editors • Published by OrthoVellum Medical Education Team
Infrapatellar approach (medial parapatellar or transpatellar tendon) | intermediate
PCL. Location: Inserts posterior intercondylar roof. Risk: Entry too posterior damages PCL, creates apex anterior deformity. Protection: Entry 1cm ANTERIOR to PCL, confirm with lateral fluoro anterior to Blumensaat's line.
ACL. Location: Anterolateral intercondylar notch. Risk: Eccentric entry or reaming can damage ACL. Protection: Central coronal plane entry, direct visualization of notch, avoid notch impingement with buried nail tip.
Popliteal Artery. Location: Posterior to distal femur, tethered at adductor hiatus and popliteal fossa. Risk: Posterior cortex perforation during reaming, retractor placement, or fracture displacement. Protection: Maintain knee flexion 30-40°, ball-tipped guidewire, AP/lateral fluoro monitoring.
Common Peroneal Nerve. Location: Wraps around fibular neck, vulnerable with lateral approaches/positioning. Risk: Compression from positioning, lateral retractor placement. Protection: Padding around knee, avoid valgus stress on knee, careful lateral screw placement.
Infrapatellar Branch of Saphenous Nerve. Location: Crosses medially 1-2cm below patella, variable course. Risk: Medial parapatellar approach cuts nerve branches. Protection: Longitudinal incision in line with tibial tuberosity, minimize medial dissection, patient counseled re: infrapatellar numbness.
| Feature | Retrograde | Antegrade |
|---|---|---|
| Entry Point | Intercondylar notch | Piriformis/greater trochanter |
| Position | Supine, knee flexed 30-40° | Lateral or supine with extension table |
| Best For | Distal 1/3 fractures | Proximal/middle 1/3 fractures |
| Polytrauma | Preferred (supine access) | Requires lateral positioning |
| Obesity | Easier entry | Entry can be very difficult |
| Bilateral Femurs | Efficient (no repositioning) | Requires repositioning |
| Knee Complications | Anterior knee pain 20-40% | Minimal |
| Hip Complications | Minimal | Abductor weakness, heterotopic bone |
| Distal Fragment | Requires 4-5cm minimum | Not as critical |
| Proximal Locking | Freehand (harder) | Jig-guided (easier) |
Patient Position: Supine, knee flexed 30-40° over radiolucent triangle/bolster
Surgical Approach: Infrapatellar approach (medial parapatellar or transpatellar tendon)
Incision: 3-4cm vertical infrapatellar incision, medial parapatellar or midline transpatellar
Preoperative Planning and Setup: Review AP/lateral XR and CT if available to assess fracture pattern, comminution, canal diameter. Measure contralateral femur for nail length (subtract 2-3cm). Plan nail diameter (ream 1-1.5mm larger). Setup radiolucent table with image intensifier opposite side. Confirm AP and lateral views obtainable BEFORE prep/drape.
Exam Pearl
Technical Tip: EXAM KEY: Templating on contralateral side gives accurate nail length. Entry point location is MOST CRITICAL technical point - wrong entry causes malreduction, implant failure, knee pain. CT useful for distal extension fractures.
Patient Positioning: Supine position. Knee flexed 30-40° over radiolucent bolster/triangle under distal thigh. This allows nail insertion trajectory and opens posterior cortex distally. Hip neutral position. Image intensifier on opposite side of fracture. CONFIRM: AP and lateral femur views including hip and knee achievable.
Exam Pearl
Technical Tip: EXAM KEY: 30-40° flexion is optimal - less than 30° makes entry difficult, more than 45° risks posterior cortex breach. Bolster position affects reduction - place at fracture level to assist reduction maneuvers.
Surgical Approach to Knee: Midline or medial parapatellar 3-4cm longitudinal incision over inferior pole patella. CHOICE: (1) Transpatellar tendon (longitudinal split in midline) OR (2) Medial parapatellar (retract tendon laterally). Deepen to expose fat pad. Excise triangular portion of fat pad to visualize intercondylar notch entrance.
Exam Pearl
Technical Tip: EXAM KEY: Medial parapatellar PRESERVES tendon integrity (preferred by many) but gives slightly off-centre entry. Transpatellar gives central entry but requires meticulous tendon repair. If split tendon, tag with stay sutures for later repair.
Identify Anatomic Entry Point: Direct visualization of intercondylar notch. ENTRY POINT: anteroposterior - centre of notch (equal distance from lateral/medial walls), 1cm ANTERIOR to PCL insertion. Lateral view: ANTERIOR to Blumensaat's line (roof of notch). Use awl to mark/create starting point in subchondral bone.
Exam Pearl
Technical Tip: EXAM KEY: Entry TOO POSTERIOR damages PCL, nail driven anterior (apex anterior angulation). Entry TOO ANTERIOR creates difficulty insertion, notch impingement, patellofemoral symptoms. Blumensaat's line is KEY lateral landmark.
Guidewire Insertion: Insert ball-tipped guidewire through entry point under LIVE fluoroscopy (AP and lateral simultaneously if possible). Direct wire down femoral canal with gentle manipulation. GOAL: central in canal on AP and lateral views, passing fracture site without eccentric positioning. If fracture displaced, may need manipulation or small incision for reduction aids.
Exam Pearl
Technical Tip: EXAM KEY: Ball-tip prevents guidewire getting lost in soft tissues. Watch tip CONTINUOUSLY on fluoro - if eccentric, withdraw and redirect. Difficulty passing fracture = need closed reduction maneuvers or limited open reduction.
Fracture Reduction (if needed): Assess reduction on AP/lateral. ACCEPTABLE: less than 5° angulation, less than 1cm shortening, rotation matched to contralateral. If unacceptable: (1) Closed manipulation with traction/rotation, (2) Percutaneous clamps, (3) Mini-open at fracture site. Provisional reduction with K-wires or clamps. THEN pass guidewire.
Exam Pearl
Technical Tip: EXAM KEY: Reduction BEFORE reaming is critical - reaming displaced fracture risks eccentric canal, cortical perforation, malreduction. Rotation assessed by comparing lesser trochanter profile to contralateral femur on AP view.
Opening the Medullary Canal: Over guidewire, use cannulated awl or entry reamer to open distal femur entry portal. Start small, enlarge gradually. FEEL: penetration through subchondral bone into medullary canal. Confirm position with fluoro - should be INTRAMEDULLARY, not in soft tissue or articular.
Exam Pearl
Technical Tip: EXAM KEY: Gentle controlled force - excessive force risks fracture displacement, condyle fracture, or guidewire advancement. Opening adequately prevents difficulty with reamer passage.
Sequential Reaming: Ream over BALL-TIPPED guidewire in 0.5-1mm increments starting 1-1.5mm smaller than anticipated nail size. Ream to measured diameter (templated) plus 1-1.5mm. Feel for chatter (cortical contact), watch fluoro for eccentric reaming. GOAL: uniform reaming without eccentricity or fracture displacement.
Exam Pearl
Technical Tip: EXAM KEY: Ball-tipped wire essential - prevents wire advancement or exit through fracture. Reamings have osteogenic potential. Ream 1-1.5mm LARGER than nail for ease of passage. Stop if excessive resistance (risk perforation).
Nail Insertion: Attach selected nail (length from template, diameter 1-1.5mm smaller than final reaming) to jig. Insert over guidewire with gentle rotatory movements. Monitor passage on fluoro - should remain central, pass fracture smoothly. If resistance: stop, assess with fluoro, may need additional reaming or wire repositioning. Advance until nail tip 5-10mm ABOVE lesser trochanter.
Exam Pearl
Technical Tip: EXAM KEY: Nail length critical - TOO SHORT: inadequate proximal fixation, TOO LONG: greater trochanter pain, difficulty with proximal locking. Tip position 5-10mm ABOVE lesser trochanter optimal. Rotatory insertion prevents incarceration.
Confirm Reduction and Nail Position: Full AP and lateral fluoroscopy: (1) Fracture reduction acceptable, (2) Nail central in medullary canal throughout, (3) No cortical perforation, (4) Distal nail position in notch acceptable, (5) Proximal nail tip position appropriate. Address any issues NOW before locking.
Exam Pearl
Technical Tip: EXAM KEY: Final reduction check BEFORE locking - once locked, difficult to adjust. Varus/valgus malreduction common - check mechanical axis on AP. Flexion/extension malreduction - check lateral. Rotation hardest to assess - compare to contralateral.
Distal Locking (Static): Using jig-guidance (attached to nail), insert 2-3 distal interlocking screws. TECHNIQUE: stab incision, tissue protector, drill through near cortex-nail-far cortex, measure, insert screw 5mm longer than measurement. Bicortical purchase essential. Most distal screw as close to joint as possible (maximum fragment control).
Exam Pearl
Technical Tip: EXAM KEY: DISTAL LOCKING FIRST for retrograde nails (opposite of antegrade). Jig-guided distal locking very accurate. Ensure screws don't penetrate joint - confirm with fluoro. Minimum TWO screws, THREE if short distal fragment. Locking provides rotational/length control.
Proximal Locking (Static or Dynamic): FREEHAND technique (jig doesn't reach proximal femur): (1) Perfect circles technique - rotate C-arm until screw hole appears as PERFECT CIRCLE, (2) Stab incision centered on circle, (3) Drill centered in circle on both orthogonal views, (4) Measure and insert screw. Insert 1-2 proximal screws. STATIC (no sliding) for comminuted/unstable fractures, DYNAMIC (allow sliding) for simple transverse fractures.
Exam Pearl
Technical Tip: EXAM KEY: Freehand locking technically demanding - requires perfect circle technique mastery. Radiation exposure higher (protect thyroid, eyes). STATIC vs DYNAMIC: simple fractures can be dynamic (allows compression), comminuted MUST be static (prevent shortening).
Final Imaging and Assessment: Complete AP/lateral fluoroscopy: (1) ALL screws fully inserted, bicortical, correct length, (2) Reduction maintained (alignment, length, rotation), (3) No intra-articular screw penetration (distal screws, change knee flexion/rotation during check), (4) No hardware complications visible. Document images.
Exam Pearl
Technical Tip: EXAM KEY: INTRA-ARTICULAR SCREW penetration most common error - MUST check with knee in flexion/extension and rotation (changes condyle profile). Screw length: aim 5mm past far cortex. If unicortical purchase only = inadequate.
Wound Closure: If tendon split: repair with #2 non-absorbable suture (Krackow or similar locking technique), ensure solid repair to prevent rupture. Irrigate thoroughly. Close retinaculum, subcutaneous with absorbable suture, skin. Bulky compressive dressing. NO DRAIN typically needed.
Exam Pearl
Technical Tip: EXAM KEY: Patellar tendon repair CRITICAL if split approach used - rupture is devastating complication. Krackow suture technique gives strongest repair. Early protected ROM improves outcomes if fixation stable.
Postoperative Protocol: Weight-bearing status depends on fracture pattern and fixation stability. STABLE simple fracture with good fixation: early protected weight-bearing (TDWB advancing to PWB then FWB over 6-12 weeks as clinical/radiographic healing progresses). UNSTABLE comminuted fracture: NWB 6-8 weeks minimum. Early ROM exercises (prevent stiffness). DVT prophylaxis per protocol. Serial XR at 2, 6, 12 weeks.
Exam Pearl
Technical Tip: EXAM KEY: Retrograde nails allow EARLIER mobilization than plates (load-sharing vs load-bearing). Knee stiffness is common complication - early ROM critical. Full weight-bearing when radiographic/clinical healing (typically 8-12 weeks simple, 12-16 weeks comminuted).
| Complication | Recognition | Prevention | Management |
|---|---|---|---|
| Anterior Knee Pain (20-40%) | Pain with kneeling, stairs, prolonged sitting; examination shows patellofemoral tenderness, may have crepitus | Precise entry point anterior to Blumensaat's, bury nail tip flush/recessed, meticulous tendon repair, minimize fat pad trauma | Physiotherapy, activity modification, NSAIDs initially; nail removal after union improves 60-80% of cases; MRI if considering revision |
| Malunion (5-15%) | Clinical deformity, abnormal gait, adjacent joint symptoms; radiographic angulation or rotation exceeds acceptable limits | Correct entry point (prevents apex anterior), adequate reduction before nailing, check alignment all planes before locking, compare rotation to contralateral | Acceptable limits: less than 5° varus/valgus, less than 10° flexion/extension, less than 10° rotation; symptomatic malunion requires corrective osteotomy after union |
| Nonunion (3-7%) | Persistent pain at fracture site beyond 6 months, hardware loosening, motion at fracture site on stress views | Static locking for unstable fractures, avoid excessive distraction, optimize biology (smoking cessation), appropriate weight-bearing progression | Exchange nailing with larger diameter, add autograft iliac crest or BMP, address infection if present, dynamization if hypertrophic |
| Hardware Failure (2-5%) | Sudden pain after event, loss of reduction, visible screw or nail breakage on radiograph | Adequate nail diameter (fill 80% canal), static locking for unstable patterns, appropriate weight-bearing restrictions | Usually indicates nonunion; requires revision: exchange nailing with larger diameter, add bone graft, address biological factors |
| ACL/PCL Injury (less than 2%) | Post-op instability, positive Lachman or posterior drawer, MRI confirmation if suspected | Precise entry point (fluoro confirmation anterior to Blumensaat's, 10mm anterior to PCL), direct notch visualization, avoid eccentric entry | PCL: most tolerated non-operatively; ACL: consider reconstruction after fracture healed if symptomatic instability |
| Deep Infection (1-3%) | Wound erythema, drainage, fever, elevated CRP/ESR beyond expected timeframe, positive cultures | Preoperative IV cephazolin 2g, minimize soft tissue trauma, limit surgical time, meticulous hemostasis | Early (less than 3 weeks): debridement, retain hardware, IV antibiotics 6 weeks; Late: staged removal, debridement, antibiotic spacer, definitive fixation after eradication |
Weight-bearing: STABLE simple fractures - touch-down weight-bearing advancing to partial then full over 6-12 weeks as clinical/radiographic healing progresses. UNSTABLE comminuted fractures - non-weight bearing 6-8 weeks minimum. ROM: immediate knee ROM exercises to prevent stiffness - flexion/extension in brace if needed initially. DVT prophylaxis per protocol (LMWH or DOACs). Follow-up: 2, 6, 12 weeks with AP/lateral XR to assess union, alignment, hardware position. Union expected 8-12 weeks simple fractures, 12-16 weeks comminuted. Full activity when clinical/radiographic union confirmed, typically 3-6 months.
Practice these scenarios to excel in your viva examination
"A 45-year-old polytrauma patient has bilateral femoral shaft fractures with associated chest and abdominal injuries. How would you manage the femoral fractures and what approach would you use?"
"During retrograde nailing of a distal femoral shaft fracture, you're having difficulty achieving reduction and the guidewire keeps exiting posteriorly at the fracture site. What is your approach?"
"You've completed retrograde femoral nailing and the patient develops anterior knee pain 3 months postoperatively that limits their rehabilitation. The fracture is healing well. What is your assessment and management?"
High-Yield Exam Summary
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Papadokostakis G, Papakostidis C, Dimitriou R, Giannoudis PV. The role and efficacy of retrograding nailing for the treatment of diaphyseal and distal femoral fractures: a systematic review of the literature. Injury. 2005;36(7):813-822.
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