Tibia-Fibula Shaft Fractures and Pilon (Tibial Plafond) Fractures

Introduction

The tibia is the most commonly fractured long bone and the principal weight-bearing bone of the leg, with a particularly thin subcutaneous anteromedial cortex that contributes to the disproportionately high rate of open fractures (the highest of any long bone, with approximately 25 percent of tibial shaft fractures being open). The fibula, although less essential to weight bearing (transmitting only approximately 6 to 16 percent of the load through the leg), provides important contributions to stability through its proximal articulation, its participation in the ankle mortise distally, and its function as a strut against varus collapse. The tibial shaft fracture, treated almost universally by intramedullary nailing in adults, is one of the most commonly performed orthopedic operations. The tibial pilon (plafond) fracture — the intra-articular fracture of the distal tibial weight-bearing surface — is a distinct entity with a substantially different management strategy reflecting the high-energy mechanism, soft-tissue compromise, and articular reconstruction challenge that characterize these injuries. 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 both entities.

Surgical Anatomy

The tibia is a triangular bone in cross-section with three cortices (anterior, posteromedial, and lateral) and three borders (medial, anterolateral, and interosseous). The anteromedial cortex is subcutaneous from just below the knee to the medial malleolus, with virtually no soft-tissue coverage — a feature that contributes to the high open fracture rate and to the slow healing of fracture site wounds and surgical incisions in this region. The isthmus of the tibial medullary canal is typically in the mid-third, with diameter 8 to 14 mm in adults, and is the site of greatest endosteal cortical contact for intramedullary nailing. The fibula is a slender bone running parallel to the tibia, articulating with it proximally at the proximal tibiofibular joint and connected through the interosseous membrane along its length. Distally, the fibula forms the lateral wall of the ankle mortise as the lateral malleolus. The leg compartments (anterior, lateral, posterior superficial, posterior deep — four total) are tightly bounded by fascia and contain the muscles, nerves, and vessels of the leg. The principal neurovascular structures include: The anterior tibial artery and deep peroneal nerve in the anterior compartment, descending along the interosseous membrane to terminate at the dorsum of the foot. The superficial peroneal nerve in the lateral compartment, becoming subcutaneous at the junction of the middle and distal thirds of the leg.

The tibial nerve and posterior tibial artery in the posterior deep compartment, descending along the posterior surface of the tibia. The common peroneal nerve around the neck of the fibula proximally, at greatest risk in fibular neck or proximal tibial injuries. The distal tibiofibular syndesmosis is a fibrous joint with the anterior inferior tibiofibular ligament (AITFL), the posterior inferior tibiofibular ligament (PITFL), the interosseous ligament, and the transverse tibiofibular ligament providing stability between the tibia and fibula at the ankle mortise. Syndesmotic injury is a recognized component of ankle fractures and certain tibial fractures and requires attention to maintain the integrity of the ankle mortise.

Tibial Shaft Fractures — Classification

The AO/OTA classification (region 42) is the standard: 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 with butterfly), C2 segmental, C3 irregular comminuted. The Gustilo-Anderson classification of open fractures (described in detail in Topic Trauma-5) is critical to tibial shaft fracture management because of the high open fracture rate. The types I (clean wound less than 1 cm), II (wound 1 to 10 cm with moderate soft- tissue injury), IIIA (severe but adequate periosteal coverage), IIIB (severe with inadequate periosteal coverage requiring flap), and IIIC (with arterial injury requiring repair) substantially direct management.

Clinical Assessment of Tibial Shaft Fractures

The clinical presentation depends on energy and pattern. Low-energy spiral fractures (sports injuries, falls) present with localized pain, swelling, and deformity. High-energy transverse or comminuted fractures (motor vehicle accidents, falls from height) present with greater deformity, more substantial soft-tissue injury, and frequent open wounds. The examination specifically assesses: Soft-tissue envelope and wound condition: The presence and grade of open wound, blistering, abrasions, and the condition of the surrounding skin and subcutaneous tissue. The subcutaneous anteromedial surface is particularly vulnerable to skin compromise and necrosis. Compartment syndrome: The leg compartments are the most common site of compartment syndrome in the body, and the tibial shaft fracture is the most common precipitant. The 5 P’s (pain, paresthesias, pallor, pulselessness, paralysis) are taught, but pain out of proportion to injury and pain with passive stretch of the affected muscles are the earliest and most reliable signs. Intra-compartmental pressure measurement

(Whitesides technique or slit catheter) is performed in equivocal cases; absolute pressure greater than 30 mmHg or perfusion pressure (diastolic blood pressure minus compartment pressure) less than 30 mmHg indicates compartment syndrome requiring fasciotomy. Neurovascular examination: Distal pulses (dorsalis pedis, posterior tibial), peroneal and tibial nerve function in the foot. Imaging is AP and lateral radiographs of the tibia and fibula including the knee and ankle joints. CT is reserved for intra-articular extension or for surgical planning in complex patterns; it is essential for pilon fractures.

Treatment of Tibial Shaft Fractures

Non-Operative Management Non-operative management with long-leg cast or Sarmiento patellar tendon-bearing cast was the historical standard for the majority of closed tibial shaft fractures. The technique involves closed reduction under appropriate anesthesia, application of a long-leg cast for 4 to 6 weeks, conversion to a patellar tendon-bearing functional brace (the Sarmiento brace adapted for the tibia) for an additional 6 to 12 weeks, and progressive weight bearing throughout. The technique remains appropriate for truly stable closed fractures with acceptable position: • Less than 5 mm shortening. • Less than 5 degrees varus or valgus angulation. • Less than 10 degrees of sagittal angulation. • Less than 10 degrees of rotational malalignment. Within these limits, non-operative management produces acceptable outcomes, with union rates of 90 to 95 percent and reasonable functional results. Outside these limits, secondary displacement, malunion, or nonunion become substantially more common, and operative management is preferred. Operative Management — Intramedullary Nailing Intramedullary nailing is the standard operative treatment for displaced tibial shaft fractures, including most closed fractures and the great majority of open fractures up through Gustilo-Anderson type IIIA (and selected IIIB after soft-tissue coverage). The technique: Patient positioning: Supine on a regular table with the affected leg over a bolster or on a radiolucent triangle, knee flexed for entry, or on a fracture table. Entry point: The standard entry point is on the anterior tibial surface, immediately above the tibial tuberosity, in line with the anatomic axis of the tibia. The classical approach is infrapatellar (through a small longitudinal incision split between or splitting the patellar tendon), with attention to the medial-lateral starting position to avoid valgus or varus malreduction. The suprapatellar approach with the knee in semi-extension has gained substantial popularity over the past decade because of easier reduction (especially for

proximal-third fractures), reduced anterior knee pain, and the ability to maintain reduction during nailing with the leg over the table without a bump. Reduction: Closed reduction by traction and manipulation is the goal. Adjunctive techniques include reduction with a small percutaneous “poke” tool, provisional K-wire fixation, blocking screws (Poller screws placed in the metaphysis at the apex of deformity to direct the nail into the correct trajectory), and femoral distractor application across the fracture. Open reduction is reserved for fractures where closed reduction fails or for cases with interposed soft tissue. Reaming: Standard reaming with progressive flexible reamers prepares the canal for a larger-diameter nail with greater fatigue strength. The reaming debris also contributes to fracture healing. The intramedullary pressure increase with reaming is less of a clinical concern than in the femur (where the marrow embolization risks fat embolism — see Topic Trauma-7), but the RIA system can be used if needed. Locking: Proximal (typically 2 to 3 screws) and distal (typically 2 to 3 screws) locking provides rotational and axial stability. Static locking is the standard; dynamic locking (removing screws at one end to permit fracture site compression) is occasionally used for delayed union. The SPRINT trial (Bhandari et al., 2008) — a large multicenter trial of reamed versus unreamed nailing in tibial shaft fractures — provided substantial evidence supporting reamed nailing as the standard in closed and selected open tibial shaft fractures, with reduced reoperation rates in the reamed cohort. Other Operative Techniques Plate fixation of the tibial shaft is reserved for specific indications: pediatric or skeletally immature patients (to avoid physeal injury), severely contaminated open fractures where intramedullary nailing risks deep infection, fractures with extensive comminution and bone loss where the working length of an IM nail is inadequate, peri-articular extension that compromises nailing, and selected metaphyseal fractures (proximal or distal). The MIPO (minimally invasive percutaneous osteosynthesis) technique uses submuscular plating without exposure of the fracture site, preserving the periosteal blood supply. External fixation is the standard for damage control in polytrauma patients, for severely contaminated open fractures (particularly IIIB and IIIC with extensive soft-tissue injury where intramedullary nailing carries infection risk), for fractures with severe soft-tissue compromise where definitive internal fixation is delayed, and for selected children. The Ilizarov circular fixator is used for both temporary stabilization and definitive treatment in selected complex injuries, including those with bone loss requiring bone transport (see Topic Trauma-8).

Complications of Tibial Shaft Fractures

The principal complications include:

Nonunion: Reported in 2 to 17 percent depending on the series, the fracture pattern, and patient factors (smoking, NSAIDs, diabetes). The tibia has a particularly high nonunion rate compared to other long bones because of the limited soft-tissue envelope and the tenuous vascular supply. Treatment of established nonunion is by exchange nailing (success rate approximately 70 to 90 percent for atrophic nonunion in the tibia), plate augmentation of an existing nail, or bone grafting with revision fixation. The Ilizarov technique is reserved for the most severe cases, particularly with segmental defects or with infection. Malunion: As discussed for acceptable parameters. The tibia tolerates less malunion than the femur because of the direct relationship between tibial alignment and ankle joint mechanics. Significant malunion (more than 5 degrees varus/valgus, more than 10 degrees sagittal, more than 10 degrees rotation, more than 1 to 2 cm shortening) produces ankle arthritis and gait disturbance and is treated by corrective osteotomy. Compartment syndrome: As discussed above. Decompressive four-compartment fasciotomy through medial and lateral incisions (Mubarak technique) is the standard. Infection: Approximately 1 to 2 percent in closed tibial nailing and 5 to 25 percent in open fractures depending on grade. Management follows the principles in Topic Trauma-9. Knee pain: Anterior knee pain after tibial nailing is reported in 30 to 50 percent of patients with infrapatellar approach, less common with suprapatellar approach. Hardware removal is sometimes performed for symptomatic patients after union is achieved.

Pilon (Tibial Plafond) Fractures

The tibial pilon is the weight-bearing articular surface of the distal tibia, articulating with the talus to form the ankle joint. The pilon fracture is the intra-articular fracture of this region, typically produced by high-energy axial load through the talus into the distal tibia (fall from height, motor vehicle dashboard injury), in contrast to the rotational mechanism of typical ankle fractures. Classification The Rüedi-Allgöwer classification (1969) is the historical standard: Type I: Non-displaced cleavage fracture without articular impaction. Type II: Displaced articular fracture with no comminution but with rotational and varus/valgus displacement. Type III: Severely comminuted articular fracture with significant impaction of the articular surface. The AO/OTA classification (region 43) provides more detail: 43-A is extra-articular distal tibia, 43-B is partial articular, 43-C is complete articular pilon. The pilon proper corresponds to AO 43-C patterns.

Mechanism and Soft-Tissue Considerations The high-energy axial mechanism produces both bony comminution and substantial soft- tissue injury, with blister formation within 24 to 48 hours of injury being characteristic. The blisters (and the underlying skin compromise) prevent immediate definitive operative fixation; the two-stage approach is now the standard for the great majority of pilon fractures. Two-Stage Management The two-stage management consists of: Stage 1 (within 24 to 48 hours): Spanning external fixation across the ankle, with restoration of length and rough alignment of the fracture; open reduction of the fibula if displaced, with plate or rod fixation (the fibular fixation provides a “third tube” that helps maintain length); and protection of the soft-tissue envelope with appropriate dressings. The patient is then maintained in the spanning fixator for 1 to 3 weeks while the soft tissues recover (resolution of blisters, return of skin pliability, decrease in swelling). Stage 2 (typically 7 to 21 days after injury): Definitive ORIF through approaches selected to avoid the at-risk skin. The classical anterolateral approach (between the deep peroneal nerve and the EHL/anterior tibial tendon) provides excellent visualization of the articular surface and is the most commonly used. The medial approach is reserved for fractures with medial-dominant components. Articular reduction is achieved with reduction tools and direct visualization, with structural autograft or allograft used to fill defects. Fixation is by medial buttress plate and/or anterolateral plate, with the choice depending on the pattern. The dual plating (medial and anterolateral) of severely comminuted pilon fractures has become increasingly common. Single-Stage Management Single-stage definitive fixation is reserved for low-energy pilon fractures with minimal soft-tissue injury, where definitive ORIF can be performed acutely without significant skin compromise. Outcomes The functional outcomes of pilon fractures are notoriously disappointing — even with optimal management, post-traumatic arthritis develops in 30 to 60 percent of patients within 5 years, and many require ankle arthrodesis or total ankle arthroplasty in the long term. The principal determinants of outcome are the quality of articular reduction (anatomical reduction is the single most important predictor of good outcome) and the management of the soft-tissue envelope (with infection in the inflamed pilon fracture surgical site being one of the most disastrous complications in orthopedics). The complications of pilon fractures include: Wound complications: Wound dehiscence, skin necrosis, infection — substantially higher than for typical fracture surgery, hence the two-stage approach.

Infection: Deep infection in 5 to 15 percent of series, with substantially worse outcomes than for tibial shaft fracture infection. Post-traumatic arthritis: 30 to 60 percent at 5 years. Stiffness: Common, particularly of the ankle in dorsiflexion. Nonunion: Occasional, requiring revision surgery or, in severe cases, ankle fusion.

Fibular Fractures

Isolated fibular shaft fractures (in the absence of tibial fracture) are uncommon and typically result from direct trauma. Treatment is generally non-operative with cast or boot immobilization for 4 to 6 weeks, as the fibula plays a minor role in weight bearing and even significant displacement is well tolerated. Operative fixation of isolated fibular shaft fractures is reserved for specific indications: severely displaced fractures with skin compromise, fractures associated with syndesmotic injury (which usually requires fibular fixation as part of syndesmotic reduction), and fractures associated with ankle instability. Proximal fibular fractures (fibular head or neck) require attention to the common peroneal nerve, which courses around the fibular neck and is at risk of injury both from the initial trauma and from operative exposure. Maisonneuve fracture — proximal fibular fracture with associated syndesmotic disruption and medial ankle injury — is a specific pattern produced by external rotation mechanism and requires recognition of the entire injury (the medial side and the syndesmosis) for appropriate treatment (addressed in Topic Trauma-28 on ankle fractures). Distal fibular fractures are addressed under ankle fractures (see Topic Trauma-28).

Tibial Shaft Stress Fractures and Tibial Stress Reactions

The tibial stress fracture is a fatigue fracture of the tibial cortex produced by repeated submaximal loading — typically in distance runners, military recruits, and dancers. The fracture occurs through accumulation of microdamage in the cortex without complete failure under any single load. The classification by location is critical: anterior cortex (“dreaded black line”) stress fractures of the mid-tibia are at high risk of progression to complete fracture and nonunion because of the tension side of the bone (the anterior cortex is in tension under loading because of the natural posterior bow of the tibia); posteromedial stress fractures of the proximal or mid-tibia heal more reliably with relative rest. The Stress fracture risk classification distinguishes high-risk sites (anterior tibial cortex, femoral neck tension side, patella, talus, navicular, fifth metatarsal proximal diaphysis, sesamoids) from low-risk sites; high-risk stress fractures require operative management or strict non-weight-bearing protocols, while low-risk fractures permit graduated relative rest with continued cross- training. Treatment of posteromedial tibial stress fracture: relative rest, modification of activity, treatment of underlying factors (training error, bone density issues, RED-S — relative

energy deficiency in sport with associated menstrual dysfunction in female athletes). Most heal with 6 to 12 weeks of relative rest and graduated return to activity. Treatment of anterior tibial cortex stress fracture: prolonged non-weight-bearing or operative intervention. Surgical options include intramedullary nailing (which provides immediate mechanical support and accelerates healing) and excision of the radiolucent line with bone grafting and plate fixation. The operative approach is increasingly favored for the dreaded black line in competitive athletes because of the prolonged time to recovery with conservative management.

Summary and Take-Home Points

The tibial shaft fracture is the most common adult long-bone fracture, with the high rate of open fractures reflecting the subcutaneous nature of the anteromedial cortex. The AO/OTA classification (42) and the Gustilo-Anderson classification for open fractures structure management. Intramedullary nailing has been the standard operative treatment since the 1980s, with the suprapatellar approach gaining popularity for its easier reduction (especially in proximal-third fractures) and reduced anterior knee pain compared with the traditional infrapatellar approach. Reamed nailing is the standard based on the SPRINT trial evidence. The acceptable parameters for non-operative cast treatment (less than 5 mm shortening, less than 5 degrees varus/valgus, less than 10 degrees sagittal, less than 10 degrees rotation) reflect the lesser tolerance of the tibia for malunion compared with the femur. Compartment syndrome of the leg is the most common compartment syndrome site, with the tibial shaft fracture being the most common precipitant; four-compartment fasciotomy is the treatment. The pilon fracture is the intra-articular fracture of the distal tibial weight-bearing surface, produced by high-energy axial mechanism with substantial soft-tissue injury. The two- stage management (initial spanning external fixation and fibular fixation, with delayed definitive ORIF after soft-tissue recovery) has become standard for the great majority of pilon fractures, replacing the historical approach of immediate definitive fixation that produced unacceptable rates of wound complications and infection. Anatomical articular reduction through anterolateral or medial approaches with buttress plating (often dual plating for severely comminuted patterns) is the surgical principle. The outcomes are notoriously disappointing, with high rates of post-traumatic arthritis (30 to 60 percent at 5 years) and frequent progression to ankle arthrodesis or total ankle arthroplasty in long- term follow-up. The fibular fracture is generally a benign injury when isolated (the fibula transmits only 6 to 16 percent of leg load), with operative management reserved for fractures associated with syndesmotic disruption or ankle instability. The Maisonneuve fracture of the proximal fibula with associated syndesmotic and medial ankle injury must be recognized as part of the complete injury complex. Tibial stress fractures, particularly the anterior cortex “dreaded black line,” are at high risk of progression and frequently require operative management in competitive athletes. The chapter that follows turns to the ankle fractures and ligamentous injuries, with the rotational mechanisms of the Weber and Lauge-Hansen classifications structuring the bulk of ankle trauma management.