Femoral Shaft Fractures and Intramedullary Nailing Technique

Introduction

The femoral shaft (diaphyseal) fracture occupies a particular place in the history of orthopedic surgery as the injury for which intramedullary nailing was originally developed (Gerhard Küntscher in the 1930s and 1940s) and as the prototypical application of the technique. The femur is the largest, strongest, and most heavily loaded long bone in the body, and the femoral shaft fracture is therefore both a marker of significant trauma (typically high-energy mechanism in young patients, although a smaller proportion of fractures occur in elderly osteoporotic patients) and a substantial physiological insult. The fracture site can hold over a liter of blood in the closed compartment of the thigh, contributing to shock; the marrow contents released during fracture and reaming contribute to fat embolism risk; and the proximity to major neurovascular structures (femoral, superficial femoral, and popliteal vessels) demands careful consideration. The intramedullary nail provides the closed, load-sharing, biologically protective construct that has produced reliable union rates exceeding 95 percent and excellent functional outcomes in most patients. This chapter, drawing on Rockwood and Green’s Fractures in Adults, AO Principles of Fracture Management, Apley & Solomon’s, and Miller’s Review of Orthopaedics, addresses the contemporary management of femoral shaft fractures and the principles of intramedullary nailing.

Surgical Anatomy and Biomechanics

The femoral shaft extends from approximately 5 cm distal to the lesser trochanter to approximately 6 cm proximal to the adductor tubercle, a length of approximately 35 cm in the adult. The shaft has a characteristic anterior bow of approximately 12 to 15 degrees of apex-anterior curvature in the sagittal plane, which must be accommodated by the design of intramedullary nails (modern nails have appropriate radius of curvature to match this anatomy). The isthmus of the femoral medullary canal is typically located in the mid-third of the bone, with diameter 10 to 16 mm in adults, and is the site of greatest endosteal cortical contact for a non-curved cylindrical nail. The deforming forces on the femoral shaft fracture are complex and produce characteristic displacements: The proximal fragment is acted on by the abductors (gluteus medius and minimus) producing abduction, the iliopsoas producing flexion and external rotation, and the short external rotators producing external rotation. The classical proximal fragment displacement is therefore flexed, abducted, and externally rotated. The distal fragment is acted on by the adductors producing adduction, the hamstrings producing flexion of the knee with relative shortening, and the gastrocnemius producing flexion of the distal fragment.

The combined effect produces shortening, varus angulation (apex lateral), and external rotation of the distal fragment relative to the proximal — a deformity that must be corrected during reduction and maintained by the fixation construct. The vascular anatomy includes the superficial femoral artery and vein descending along the medial aspect of the thigh through the adductor canal, the profunda femoris artery with its perforating branches that supply the muscular envelope and the bone, and the popliteal vessels distally. Significant vascular injury is rare in closed femoral shaft fractures but should be specifically excluded in any patient with diminished pulses, signs of vascular compromise, or unusual displacement patterns. The neurological anatomy includes the sciatic nerve descending in the posterior thigh (dividing into common peroneal and tibial divisions in the popliteal fossa) and the femoral nerve descending anteriorly. The sciatic nerve is at greatest risk during retrograde nailing (where errors in entry point can damage the nerve directly) and during fracture displacement; the femoral nerve is at risk during anterior approaches.

Classification

The AO/OTA classification (region 32) is the standard system: Type A (simple): A1 spiral, A2 oblique (>30 degrees), A3 transverse (<30 degrees). Type B (wedge): B1 spiral wedge, B2 bending wedge, B3 fragmentary wedge. Type C (complex): C1 spiral complex (segmental fracture with intact butterfly), C2 segmental, C3 irregular comminuted. The Winquist and Hansen classification (1980) specifically describes comminution patterns and remains useful for treatment planning: Type I: Minimal or no comminution. Type II: Large butterfly with greater than 50 percent cortical contact maintained. Type III: Large butterfly with less than 50 percent cortical contact maintained. Type IV: Segmental fracture with no cortical contact (length cannot be maintained by cortical apposition alone). The clinical importance of the Winquist-Hansen classification is the prediction of construct loading: types I and II permit some load sharing between bone and implant after reduction; types III and IV transfer all axial load through the implant until callus forms, requiring constructs (statically locked nails) that can bear this load.

Clinical Assessment

The patient typically presents after high-energy trauma with gross deformity of the thigh, shortening, abnormal motion, and severe pain. The mechanism — motor vehicle

accident, motorcycle accident, fall from height, gunshot — typically implies polytrauma with concurrent injuries. Polytrauma evaluation by ATLS principles is essential, with the femoral shaft fracture often being one of several significant injuries. Blood loss into the thigh compartment can produce hypovolemic shock; a single femoral shaft fracture can lose 1 to 2 liters of blood, and bilateral femoral shaft fractures with associated injuries can lose 4 to 6 liters or more. The neurovascular examination is documented, with attention to the sciatic and femoral nerve functions distally and the dorsalis pedis and posterior tibial pulses. Compartment syndrome of the thigh is rare in closed femoral shaft fractures because of the large compartment volume but can occur, particularly in high-energy injuries with extensive soft-tissue involvement and in obtunded patients who cannot report symptoms. The classic clinical signs (pain out of proportion, pain with passive stretch, paresthesias, paralysis, pulselessness, and pallor) should be sought. Imaging includes AP and lateral radiographs of the entire femur with the joints above and below included. Imaging of the ipsilateral hip and knee is mandatory to detect occult ipsilateral femoral neck fracture (which can be missed in up to 30 percent of cases without specific imaging) and knee injuries. CT of the proximal femur has been advocated by some groups to detect occult neck fractures; the rate of missed femoral neck fractures in patients with shaft fractures justifies routine careful imaging.

Initial Management

Splinting for transport is typically with a Thomas splint or a Hare/Sager traction splint that provides axial traction and reduces fracture displacement. The traction relieves pain, reduces blood loss by limiting cancellous bleeding, and protects the soft-tissue envelope. Skeletal traction with a tibial or distal femoral pin may be used as temporary stabilization before definitive surgery, particularly when surgery is delayed by patient instability or operative resource availability. The traction force is typically 10 to 20 percent of body weight, applied with the hip and knee flexed. The timing of definitive fixation has been an active area of investigation. The classical principle has been early intramedullary nailing of the femoral shaft fracture (within 24 hours) in the stable polytrauma patient because of reduced ARDS rates, reduced ICU length of stay, and improved overall outcomes (this is the body of evidence underlying the early total care approach discussed in Topic Trauma-6). The principle was challenged in the late 1990s and early 2000s with evidence that in the unstable polytrauma patient, the additional surgical insult of femoral nailing — particularly with reaming — could worsen pulmonary inflammation and contribute to ARDS, leading to the damage control orthopedics approach with initial external fixation followed by delayed conversion to definitive intramedullary nailing. The current consensus is: stable polytrauma patient with normal physiology — early intramedullary nailing within 24 hours; unstable polytrauma patient — damage control external fixation followed by conversion to intramedullary nailing when

physiology is normalized; borderline patient — individualized decision incorporating fracture pattern, associated injuries, and patient response to resuscitation.

Intramedullary Nailing — Technique

Antegrade Nailing Antegrade nailing has been the historical standard for femoral shaft fractures. The technique requires: Patient positioning: Supine on a fracture table with traction, or lateral decubitus on a regular table. The fracture table provides reproducible traction but can be cumbersome and has been associated with complications (perineal nerve injury from the perineal post, compartment syndrome of the contralateral leg). Many surgeons now prefer the lateral decubitus position on a regular table with manual traction from an assistant. Entry point: Two principal options exist. The piriformis fossa entry uses the small fossa just medial to the greater trochanter at the base of the femoral neck; this entry produces a relatively straight nail trajectory along the anatomic axis of the femur but is technically demanding to identify intraoperatively, particularly in obese patients, and carries the risk of injury to the medial femoral circumflex artery (with consequent AVN of the femoral head — a small but recognized risk). The trochanteric entry uses the tip or just medial to the tip of the greater trochanter; this entry is easier to identify and is associated with lower risk of vascular injury but requires the nail to have an appropriate proximal bend to accommodate the more lateral starting point. Modern nails are designed for either entry, and trochanteric-entry nails have become the standard in many centers. Reaming versus unreamed nailing: The classical debate has been the relative merits of reaming the medullary canal (with progressive flexible reamers) before nail insertion versus inserting the nail without reaming. Reaming produces a larger canal that accepts a larger-diameter nail with greater fatigue strength, increases endosteal cortical contact for stability, generates intramedullary bone graft from the reaming debris that contributes to fracture healing, and is the standard technique in most centers. The disadvantages of reaming include the generation of intramedullary pressure (with consequent fat embolization and pulmonary insult — see Topic Trauma-7), and a longer operative time. Unreamed nailing uses a smaller nail without reaming and was proposed as an alternative in polytrauma patients with concerns about pulmonary insult, but the evidence has not consistently shown advantages, and reamed nailing remains the standard with appropriate considerations in the polytrauma context. The Reamer-Irrigator-Aspirator (RIA) system reduces intramedullary pressure during reaming and is the technique of choice when reaming is performed in the polytrauma patient. Nail size and length: The nail diameter is typically 10 to 14 mm depending on the canal size, with the principle being to use the largest nail that fills the canal at the isthmus. The nail length should span from the proximal entry point to within 1 to 2 cm of the distal femoral physis or just proximal to the adductor tubercle, providing the longest possible “working length” of the construct.

Reduction: Closed reduction by traction and manipulation is the goal. Indirect reduction techniques using a long bone reduction clamp, pointed reduction tool through a small percutaneous incision, or a “finger” tool can address residual angulation. Open reduction is reserved for cases where closed reduction is impossible or where there is interposed soft tissue. Locking screws: Proximal and distal locking screws prevent rotation and provide axial stability. Statically locked constructs (with all locking screws engaged) are used for unstable patterns (Winquist-Hansen III and IV); dynamically locked constructs (with only the proximal screws engaged at one end and only the distal at the other) permit axial loading at the fracture site and may be appropriate for stable patterns where bone-to-bone contact provides axial support. Conversion from static to dynamic locking (by removing screws from one end) may be considered in delayed union cases. Retrograde Nailing Retrograde nailing through the intercondylar notch of the distal femur has emerged as an important alternative. The entry point is just anterior to the PCL insertion in the intercondylar notch, accessed through a small parapatellar arthrotomy. The technique is advantageous in: Bilateral femoral shaft fractures (both can be nailed in the supine position without repositioning). Polytrauma patients with concurrent abdominal or chest injuries where supine positioning is needed. Obese patients where the trochanteric entry is difficult to identify. Ipsilateral pertrochanteric or acetabular fracture that precludes proximal entry. Distal-third shaft fractures where the antegrade nail does not provide adequate distal fixation. The disadvantages include the violation of the knee joint (with potential for septic arthritis if infection develops, and stiffness in selected patients), the technical challenge of distal entry, and the historical concern about knee pain. Contemporary outcomes are generally good in appropriate indications.

Plate Fixation Plate fixation of the femoral shaft is reserved for specific indications: periprosthetic fractures where the existing hip arthroplasty stem precludes nailing; fractures with vascular injury requiring open exposure for repair; fractures with extensive comminution and bone loss where the nail’s working length is inadequate; adolescents in whom the proximal femoral physis precludes piriformis or trochanteric entry; and selected highly proximal or distal fractures where the metaphyseal location makes nailing technically challenging. Submuscular plating with minimally invasive percutaneous osteosynthesis (MIPO) techniques has reduced the morbidity of plate fixation.

External Fixation External fixation is reserved for temporary stabilization in the damage control setting (as discussed in Topic Trauma-6), with conversion to intramedullary nailing within 5 to 14 days when the patient is physiologically stable. The conversion should not be delayed excessively because of the rising risk of pin tract infection that complicates subsequent nailing.

Specific Considerations

Ipsilateral Femoral Neck and Shaft Fractures The ipsilateral femoral neck and shaft fracture combination — sometimes called the “Tronzo fracture pattern” or simply the segmental femoral fracture — is reported in 1 to 9 percent of femoral shaft fractures and is frequently missed at initial evaluation. Specific careful imaging of the ipsilateral hip is essential in any patient with femoral shaft fracture. Treatment requires fixation of both fractures; the principal options are: Standard antegrade nailing with cephalic locking (using a long cephalomedullary-style construct or a “miss-a-nail” technique where cancellous screws bypass the nail to engage the femoral neck). Standard antegrade nail of the shaft plus separate cannulated screws across the femoral neck. Retrograde nailing of the shaft plus separate fixation of the neck. The femoral neck fracture is the priority because of AVN risk and is typically reduced and provisionally fixed first, with the shaft fracture subsequently addressed. Pediatric Femoral Shaft Fractures Pediatric femoral shaft fractures are managed by age-specific protocols. Children under 6 months: Pavlik harness or simple immobilization, given the remarkable remodeling potential. 6 months to 5 years: Early hip spica casting after closed reduction is the standard, with substantial residual deformity acceptable because of remodeling. 5 to 11 years: Flexible intramedullary nailing (Métaizeau / titanium elastic nailing, TENS) with two flexible nails inserted retrograde from the distal femoral metaphysis. Adolescents (11 to 18 years): Rigid intramedullary nailing with attention to the proximal femoral physis (using trochanteric entry to avoid the femoral neck) and to the distal femoral physis (which is the dominant growth contributor of the lower extremity). The lateral entry nailing technique developed for pediatric and adolescent patients avoids both the piriformis fossa (with AVN risk) and the trochanteric tip (with abductor disruption risk) by using an entry point on the lateral aspect of the trochanter; this technique has become widely adopted for the adolescent population.

Periprosthetic Femoral Shaft Fractures Periprosthetic femoral shaft fractures around an existing total hip arthroplasty are classified by the Vancouver classification discussed in Topic Trauma-8. The Vancouver C pattern, with the fracture distal to the implant, is addressed by standard plate or retrograde nail fixation of the femoral shaft with the existing implant left undisturbed. The Vancouver B patterns (around the implant) require the more complex management addressed in the periprosthetic fracture chapter. Bilateral Femoral Shaft Fractures Bilateral femoral shaft fractures are uncommon (5 to 10 percent of femoral shaft fracture series) but are associated with substantially increased mortality (25 percent compared with 5 to 10 percent for unilateral fractures), with the increased mortality reflecting both the doubled blood loss and the often more severe overall polytrauma. The classical management is bilateral intramedullary nailing in a single setting in the stable patient; the unstable polytrauma patient with bilateral femoral shaft fractures is typically managed with bilateral external fixation as part of damage control.

Complications

Nonunion and Delayed Union The nonunion rate after femoral shaft intramedullary nailing is approximately 1 to 5 percent, with risk factors including open fractures, segmental fractures, smoking, NSAIDs, and inadequate reduction with significant fracture gap. Treatment is by exchange nailing (removal of the existing nail, reaming to one or two mm larger, and insertion of a larger nail), which produces union in 70 to 90 percent of cases. Plate augmentation (addition of a compression plate to the existing nail) is an alternative for selected nonunions. Bone grafting may be added in atrophic nonunions. Malunion Malunion can occur in any plane. Rotational malalignment is the most common and is best assessed by CT (rotational profile of the entire femur compared with the contralateral side). Rotational malreduction greater than 15 degrees produces functional impairment and is treated by corrective osteotomy. Angular malalignment of more than 5 degrees varus or valgus or more than 10 degrees of sagittal angulation is poorly tolerated and may also require correction. Shortening of more than 2 cm requires lengthening or contralateral shortening procedures. Infection Deep infection after femoral nailing is uncommon (1 to 2 percent in closed fractures, 3 to 7 percent in open fractures) but is a serious complication. Treatment depends on the timing — early infection (within 4 to 6 weeks) may be managed with retention of hardware, debridement, and antibiotics (the “DAIR” approach discussed in Topic Trauma-9); late or

chronic infection requires removal of hardware, debridement, antibiotic spacer, prolonged antibiotic therapy, and definitive reconstruction. Other Complications Heterotopic ossification at the proximal entry site can occur, more commonly with piriformis entry; meticulous reaming debris removal and consideration of NSAIDs for prophylaxis can reduce incidence. Knee pain after retrograde nailing is reported in 10 to 30 percent of patients but is rarely severe enough to require hardware removal. Thigh pain from nail prominence is occasionally severe enough to require hardware removal after union. Refracture after hardware removal is uncommon but described, typically through screw holes.

Open Femoral Shaft Fractures

Open femoral shaft fractures are managed by the principles outlined in Topic Trauma-5 (open fractures): urgent broad-spectrum antibiotic administration (cefazolin plus aminoglycoside for higher-grade injuries), tetanus prophylaxis, surgical debridement of all devitalized tissue, and fracture stabilization. Definitive stabilization with intramedullary nailing is acceptable in most open femoral shaft fractures (Gustilo-Anderson types I, II, and most IIIA) and produces good outcomes with appropriate debridement. The most severe open injuries (IIIB and IIIC) may require initial external fixation with delayed conversion to intramedullary nailing after soft-tissue coverage and infection control are established.

Summary and Take-Home Points

The femoral shaft fracture is the prototype application of intramedullary nailing, with the technique providing reliable union, excellent functional outcomes, and load-sharing biological fixation that has been the standard for over half a century. The AO/OTA classification (32) and the Winquist-Hansen classification of comminution organize the heterogeneity of fracture patterns. The principles of intramedullary nailing include appropriate patient positioning (supine on fracture table or lateral decubitus with manual traction), entry point selection (trochanteric or piriformis for antegrade; intercondylar notch for retrograde), anatomical reduction (closed or with adjunctive indirect reduction techniques), appropriate nail sizing (largest diameter filling the canal at the isthmus), and appropriate locking (static for unstable patterns, dynamic for stable). The reaming versus unreamed debate has settled in favor of reamed nailing in most situations, with the RIA system reducing the pulmonary insult of reaming in polytrauma patients. Antegrade and retrograde approaches each have specific indications. The timing of definitive fixation in polytrauma incorporates the damage control principles — early nailing in stable patients, damage control external fixation in unstable patients with delayed conversion when physiology normalizes. The ipsilateral femoral neck fracture is missed in up to 30 percent of cases without specific imaging — careful imaging of the proximal femur in any shaft fracture is essential.

The complications of nonunion (managed by exchange nailing), malunion (managed by corrective osteotomy with attention to rotation), infection (managed by DAIR for early infections, by hardware removal and reconstruction for late infections), and the regional considerations (open fractures, ipsilateral neck fracture, bilateral fractures, periprosthetic fractures, pediatric fractures) round out the spectrum of management considerations. The chapters that follow turn to the distal femur and the knee, completing the lower extremity fracture sequence.