Physeal fractures about the ankle are the second most common physeal fracture, with only the distal radius being more common. Physeal fractures of the distal tibia and fibula are more common in boys than in girls and occur most frequently between 10 and 15 years of age.1 The unique anatomy of the skeletally immature ankle (strong ligamentous attachments distal to the physis and the horizontal orientation of the physis) make the ankle susceptible to injuries that require operative intervention. Thus, as a result of the injury and/or the intervention, distal tibia and fibula physeal fractures are more likely to have a subsequent premature physeal arrest as compared with distal radius fractures.
Ankle fractures typically are the result of a twisting injury. The patient will typically complain of immediate pain that is significantly worse with attempted weight bearing and persists when nonweight bearing. Noting the position of the foot and the deforming force at the time of injury will help you to interpret the radiographic findings and apply the classification scheme of Dias and Tachdjian.2
The physical exam of the injured ankle should include a thorough visual inspection and palpation around the entire ankle. Identifying lacerations or evidence of an open wound is paramount. If there is a delay in presentation from the time of injury, fracture blisters may be present and may alter the treatment plan. Localized areas of ecchymosis and swelling may be a clue to the injury. Palpation of the distal tibia and fibula physes is critical as Salter-Harris type I fractures may not be radiographically evident and diagnosis will be purely on the basis of physical exam. In the face of a distal fibula fracture with no radiographic evidence of a medial malleolar fracture, palpation of the medial soft tissues is the key to diagnosing ligamentous injury that may result in an unstable ankle mortise.
Vascular exam should include palpation of the dorsalis pedis and tibial arteries. If excessive swelling impedes palpation of the pulses, Doppler exam of the arteries should be performed. If a triphasic wave form is not heard, vascular compromise should be considered. Documenting normal capillary refill (<2 s) is helpful but may not rule out vascular compromise, as collateral circulation may allow the foot to remain viable in the face of vascular injury. This combined with careful sensory and motor exam of the nerves of the foot (superficial and deep peroneal, tibial and sural) is necessary for early diagnosis of neurovascular deficits.
Compartment syndrome of the leg or foot, although uncommon, can be associated with physeal fractures of the distal tibia and fibula. A high index of suspicion must be maintained in the face of severe swelling, pain out of proportion to the injury, and marked increased pain with passive range of motion of the toes. The extensor retinaculum syndrome has been described in patients with physeal fractures of the distal tibia.3 Anterior displacement of the distal tibia causes compression of the extensor tendons and anterior neurovascular structures under the superior extensor retinaculum (Fig. 1). These patients present similarly to those with a classic compartment syndrome: severe pain and swelling of the ankle, hypoesthesia or anesthesia of the web space of the great toe, weakness of the extensor hallucis longus and extensor digitorum communis, and pain with pain passive range of motion of the toes, particularly the great toe. Similar to the release of the compartments of the leg or foot for a compartment syndrome of the leg or foot, prompt release extensor retinaculum is the definitive treatment.3
Initial radiographic examination should include anteroposterior, lateral, and mortise views of the ankle. The mortise should be carefully evaluated for symmetry throughout the entire joint space. An external rotation stress radiograph, helpful to rule out ankle joint instability, will demonstrate joint space asymmetry if there is ligamentous instability. A computed tomography (CT) scan of the ankle is indicated to confirm and delineate the intra-articular displacement of an epiphyseal fracture. The CT scan will frequently demonstrate additional fracture lines, comminution, and fracture step-off or gapping previously unrecognized on the plain radiographs. The CT scan has been shown to be more sensitive than plain radiographs in detecting distal tibial epiphyseal fractures with >2 mm of displacement and is considered to be the preferred imaging modality of the distal tibial epiphyseal fractures.4
Accessory centers of ossification may be present at the medial malleolus in up to 20% of cases as compared with only about 1% at the distal fibula. Comparison radiographs of the contralateral ankle along with the clinical exam may be beneficial to identify true pathology versus normal variants.
SALTER-HARRIS TYPE I AND II DISTAL FIBULA FRACTURES
Salter-Harris type I and II distal fibula fractures are the most common pediatric ankle fractures and are most common between 10 and 12 years of age.5 Skeletally immature patients generally do not get isolated ankle sprains. The ligaments around the ankle are far stronger that the physis when placed under tension, resulting in physeal failure before ligament rupture. These physeal injuries are most commonly a supination-inversion injury and will typically present with swelling and ecchymosis around the lateral ankle. Always check for ecchymosis medially and pain with palpation of the medial ligaments, which may indicate a more severe injury pattern that may result in an unstable ankle mortise and the need for fixation of the fibula.
A nondisplaced Salter-Harris type I injury may not be evident on radiographs and thus will be a clinical diagnosis based on lateral swelling and tenderness directly over the distal fibular physis. A thorough and systematic review of the radiographs is critical as displaced Salter-Harris type I and II fractures are frequently associated with Salter-Harris type III and IV distal tibia fractures.
Nondisplaced distal fibular physeal fractures can safely be treated in a walking cast or boot for 4 weeks with activity modifications for 6 weeks total. Once the cast is removed, a self-guided range of motion and strengthening program is instituted until symmetric calf strength has returned. Displaced fractures requiring reduction should be treated in a non–weight-bearing short leg cast for 4 to 6 weeks followed by a self-guided range of motion and strengthening program.
SALTER-HARRIS TYPE I DISTAL TIBIA FRACTURES
Salter-Harris type I distal tibia fractures account for about 15% of all pediatric distal tibiofibular fractures and can occur with any mechanism of injury as described by Dias and Tachdjian.2,5 There is an associated fibula fracture in approximately 25% of cases, and the fibula fracture may offer a clue to the mechanism of injury.
Nondisplaced fractures can be safely treated in a short leg, non–weight-bearing cast for 4 to 6 weeks followed by a self-guided range of motion and strengthening program. Displaced fractures should be gently reduced by reversing the mechanism of injury and applying a long leg cast for 4 weeks followed by walking boot for 2 to 4 weeks while instituting a range of motion and strengthening program. If open reduction is necessary or an acceptable alignment cannot be maintained after closed reduction, smooth wire cross pinning of the distal tibia should be considered.
Although the exact amount of acceptable residual fracture displacement is not universally agreed upon, Barmada et al6 have demonstrated that 3 mm of residual physeal gapping (in a patient with ≥2 y of growth remaining) following a reduction of a Salter-Harris type I or type II distal tibia fracture may be the result of entrapped periosteum. In their series, 60% of patients with a residual gap of ≥3 mm went on to a premature physeal closure. All of the 5 patients who had residual gapping and who underwent open reduction of the distal tibia had entrapped periosteum blocking the reduction.6
SALTER-HARRIS TYPE II DISTAL TIBIA FRACTURES
This is the most common distal tibial physeal injury, accounting for up to 40% of all pediatric ankle fractures with the average age of the patient being 12.5 years.5 A fibular shaft fracture is associated with 20% of these injuries. The most common mechanisms are supination-external rotation and supination-plantar flexion, but any of the 4 mechanisms described by Dias and Tachdjian2 can cause this injury. The location of the metaphyseal fragment may be helpful in determining the mechanism of injury that will dictate the reduction technique (ie, a posterior metaphyseal fragment indicates a supination-plantar flexion injury).
Nondisplaced fractures can be safely treated in a long leg cast for 3 to 4 weeks and then changed to a short leg walking cast or walking boot for an additional 2 to 3 weeks. Displaced fractures should undergo a gentle closed reduction with long leg casting for 4 weeks followed by a short leg walking cast or walking boot for 2 to 3 weeks. It cannot be stressed enough that understanding the mechanism of injury is one of the keys to a successful closed reduction. In addition, complete relaxation of the patient during the reduction is paramount to a successful outcome. The choice of conscious sedation in the emergency department or general anesthesia in the operating room should be based on the surgeon’s judgment, taking into account the patient’s age, type of fracture, and severity of injury.7 Multiple attempts at closed reduction should be avoided so as to reduce the risk of premature growth arrest. Failure of a closed reduction should be followed by open reduction. As seen with the Salter-Harris type I fractures, a residual physeal gap of ≥3 mm in a patient with ≥2 years of growth after a closed reduction may indicate entrapped periosteum and increase the risk of a premature physeal closure.6 Open reduction is indicated for these fractures. Similarly, retrograde smooth wire cross pinning of the distal tibia should be considered in those patients undergoing open reduction.
SALTER-HARRIS TYPE III/IV DISTAL TIBIA FRACTURES (INCLUDING TILLAUX, TRIPLANE, AND MEDIAL MALLEOLUS FRACTURES)
Salter-Harris type III fractures account for about 20% of all distal tibia fractures, whereas Salter-Harris type IV (medial malleolus) fractures only account for approximately 1% distal tibia fractures. Twenty-five percent of Salter-Harris type III fractures are associated with fibular fracture and occur at an average age of 11 to 12 years.5
Salter-Harris type III fractures are the result of a supination-inversion injury. The inversion force causes a lateral ligament stress frequently resulting in an avulsion fracture of the fibula while the talus is driven into the medial distal tibia. The fracture line is medial to midline of epiphysis as compared with Tillaux or triplane fracture where the fracture line is at the midline or lateral to it. Similarly, a Salter-Harris type IV (medial malleolus) fracture is also the result of a supination-inversion injury resulting in the talus being driven into the medial distal tibia creating a fracture line that traverses the articular surface, epiphysis, and metaphysis.
Nondisplaced fractures can be treated in a long leg, non–weight-bearing cast for 4 weeks, followed by a boot for 4 weeks. The initial 2 weeks of boot wear is nonweight bearing, but the patient is allowed to remove the boot to begin ankle range of motion exercises. Weekly evaluation for the first 2 or 3 weeks is encouraged to confirm that the fracture does not displace.
Any fracture with ≥2 mm displacement should be reduced to minimize the risk of premature physeal closure, prevent joint incongruity, and minimize the risk of subsequent early degenerative arthritis.8 A Salter-Harris type III (including Tillaux and triplane) fracture is typically approached through a 3 to 4-cm anterior incision directly over the fracture. The fracture and joint line can be directly visualized. Reduction can typically be achieved indirectly with a large periarticular reduction clamp or directly with a dental pick. Percutaneous transepiphyseal fixation with 1 or 2 stainless steel cannulated screws can then be easily performed. Removal of epiphyseal metallic implants is recommended as the total force transmission, and peak contact pressures are significantly increased over baseline with the presence of the epiphyseal screws.9 Alternatively, bioabsorbable transepiphyseal screws have been shown to be safe and equally effective while negating the cost and potential risk of removal of the stainless steel screws10 (Fig. 2).
A displaced Salter-Harris type IV (medial malleolus) fracture can be approached by an anterior or traditional medial malleolar approach. Transepiphyseal fixation (stainless steel or bioabsorbable screws) is the preferred fixation. Small or comminuted fractures may necessitate a tension band construct (Fig. 3), and an unstable vertical shear fracture may necessitate a metaphyseal buttress plate. The tension band and buttress plate will span the physis and should be removed once healing of the fracture is confirmed. Postoperatively, the patient is nonweight bearing for 6 weeks, initially with a short leg cast for 4 weeks followed by a boot for 2 weeks. Serial ankle radiographs should be performed every 6 months for a minimum of 2 years to monitor for a distal tibial growth arrest.
PREMATURE PHYSEAL CLOSURE/GROWTH ARREST
The incidence of premature physeal closure, partial or complete, is the most common complication after a distal tibial physeal injury and varies depending on the fracture type (Salter-Harris type, I/II 2% to 39.6% and Salter-Harris type III/IV, 7.7% to 50%).4,8,11–14 The arrest is caused by injury to the germinal layer of the physis, creating vertical septa that allow open access for marrow cell, osteoclast, and osteoblast infiltration from the epiphyseal or metaphyseal marrow spaces.15 General risk factors include high-energy injuries, significant initial displacement, mechanism of injury, and multiple attempts at closed reduction.13,14
As mentioned in the discussion of Salter-Harris type I and II fractures, a residual physeal gap of ≥3 mm after closed reduction is associated with high rate of premature physeal closure resulting from entrapped periosteum.6 Gruber et al16 have demonstrated in an animal model that the histologic process of bar formation secondary to entrapped periosteum is similar to bar formation without entrapped periosteum. The physeal fracture is through the hypertrophic zone and spares the germinal zone, therefore anatomic reduction is not as critical. Recognition of the persistent gapping followed by open reduction and removal of the entrapped periosteum is the primary method of preventing premature closure in these types of fractures. Closed cast treatment is a significant risk factor for the development of a growth arrest in Salter-Harris type III and IV fractures in younger patients.8 Anatomic reduction of the physis, in particular the germinal layer, is the critical step in preventing premature closure in these fractures. Salter-Harris type III fractures in teenagers (Tillaux and triplane fractures) are much less like to cause a significant growth abnormality given the relative lack of remaining growth.
A physeal arrest can appear as long as 2 years postoperative; therefore, extended follow-up is important. If an arrest is suspected, the plain radiographs may show a bony bar. Asymmetric Park-Harris growth arrest lines may be visible. Comparison with the contralateral ankle may also be helpful. CT or magnetic resonance imaging (MRI) can be used to evaluate the extent of a bony bar, but all metallic implants should first be removed.
Treatment options are defined by the location and size of the bar and the amount of growth remaining. Bar resection can be considered if there is >2 years growth remaining and <50% of the width of physis is involved. If the patient has <2 years growth remaining or >50% of the width of physis is involved, one should consider completing the epiphyseodesis with or without contralateral epiphyseodesis. An opening wedge corrective osteotomy (Fig. 4) at the time of epiphyseodesis should be considered if significant varus deformity is present.7
- Knowledge of the mechanism of injury combined with a thorough clinical exam will aid in the interpretation of the radiographs and instituting a plan of care.
- Significant displacement (>3 mm) after a closed reduction attempt for Salter-Harris type II fractures and any displacement of Salter-Harris type III and IV fractures (Tillaux, triplane, medial malleolus) >2 mm is an indication for open reduction to minimize risk of physeal arrest.
- General risk factors for premature physeal closure include high-energy injuries, significant initial displacement, mechanism of injury, and multiple attempts at closed reduction.
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