fraturas da diáfise da tÍbia em crianças Tibial diaphyseal fracTures in children

As fraturas da diáfise da tíbia nas crianças e adolescentes são lesões relativamente comuns e geralmente têm boa evolução com os métodos clássicos de tratamento conservador. Sua elevada fre quência se deve ao alto grau de exposição da criança nas suas atividades físicas e também pela anatomia e topografia da tíbia, expondo-a ao trauma direto ou indireto. Algumas particularidades devem ser consideradas e respeitadas na sua abordagem, que compreendem aspectos atinentes à faixa etária, local de acometimento (se proximal ou distal), tipo de fratura e de terapêutica instituída. A vantagem anatômica do periósteo mais espesso e a relativa flexibilidade na acomodação de impactos angulares podem proporcionar na criança de menor idade, maior estabilidade e consequente tendência ao melhor prognóstico. Nas crianças maiores e nos adolescentes o grau de exposição a traumas de maior energia, a maior gravidade e complexidade das lesões têm tornado mais comum a estabilização cirúrgica. Complicações encontradas nessas fraturas nos adultos como infecção, retarde de consolidação e pseudartrose são muito menos frequentes nas crianças, mas o risco de instalação de síndromes compartimentais é uma eventualidade que requer atenção, principalmente nas condutas incruentas com imobilizações gessadas.

aBsTRaCT Tibial diaphyseal fractures in children and adolescents are relatively common injuries and often evolve with good results when treated through traditional methods of conservative treatment.Their elevated frequency is due to the high degree of exposure of children in physical activities and also to the topographic location, exposing them to direct or indirect trauma.The approach used should consider and respect some features regarding age, place of affection (whether proximal or distal), type of fracture and therapy.The anatomical advantage of a thicker periosteum and flexibility when submitted to angular impacts can provide younger children with greater stability and, consequently, increases their chances of a better prognosis than older children and adolescents.In the latter, the degree of exposure to highenergy trauma and the greater complexity and severity of injuries have caused the recent trend towards stabilization surgery to become more common.Frequent complications in the evolution of fractures in adults such as infection, delayed union and nonunion are much less common in children, although the risk of occurrence of compartment syndrome is an event that requires attention, especially with plaster.

GENERAL CONSIDERATIONS
Tibia fractures in children and adolescents constitute the most common lower-extremity fractures, representing 10 to 15% of all fractures in the pediatric population.][3][4][5][6] Fractures in this region are much more common in children that are still learning to walk.The fractures usually result from lowenergy trauma, causing fractures with smaller deviations than in adolescents, as bone resistance to direct impact trauma and to torsional trauma increases with age.[3][4][5][6] EPIDEMIOLOGY Tibia fractures are the third most common type and represent from 10 to 15% of pediatric fractures.][7][8] Twenty-six out of every one hundred (26%) children who are victims of abuse resulting in fractures present tibia fractures, making this segment the second most frequently fractured bone in beaten children. 1,6p to the age of seven years, the most common traumas reported originate from domestic and school accidents.From five to ten years, cases of children run over by vehicles are important causes of fractures, while from seven to fourteen years of age, accidents caused from falling off bicycles, sports (soccer, volleyball, basketball, etc.), skateboarding and the so-called radical sports are the most frequent causal factors of tibia fractures in this age bracket.Epiphyseal fractures and detachments occur as a consequence of forces applied indirectly at the site of the affected lower limb.Direct traumas produce transverse, simple oblique or comminuted fractures.The torsion mechanism with angulation usually results in a long oblique or spiral fracture. 4,6,7

ANATOMY
The anteromedial region of the tibia is subcutaneous and without underlying musculature for its protection. 1,6here are three ossification centers that form the tibia: 1 -Proximal epiphysis -The proximal secondary ossification center appears soon after birth with later closure at 16 years of age. 2 -Diaphyseal -It ossifies in the seventh week of gestation and expands proximally and distally.3 -Distal epiphysis -The distal secondary ossification center appears in the second year with later closure at 15 years of age.The malleolus and medial tubercle can appear as separate ossification centers and should not be confused with a fracture. 1he nutrient artery originates from the posterior tibial artery and penetrates in the posterolateral cortical bone, distally.In the intramedullary canal, it gives rise to three ascending and one descending branch, which in turn originate endosteal vascularization and anastomose with the periosteal vessels that protrude from the anterior tibial artery.This artery in turn is particularly vulnerable to lesions as it passes through the hiatus of the interosseous membrane. 1he common fibular describes its course around the fibular neck that is almost subcutaneous in this region and is particularly vulnerable to injuries by direct trauma or by indirect traction mechanism.

Fascial compartments
The leg has four fascial compartments. 6 -Anterior -Contains the extensor digitorum longus and extensor hallucis longus muscles and the tibialis anterior muscle; anterior tibial artery and the deep fibular nerve.Zionts and MacEwen 9 monitored seven children with deformity in progressive valgus of the tibia after metaphyseal fracture and concluded that the best attitude would be, "to wait and see".The highest percentage of the deformity occurred during the first year.The tibia continued to deform at a slower pace up to 17 months after the injury.
Totally spontaneous clinical correction occurred in six patients.After the average follow-up period of 39 months; all the children radiographically presented less than 10 degrees of residual deformity.
In angulated or deviated greenstick fractures, the performance of closed reduction is recommended whenever possible with the help of an image intensifier, under general anesthesia, followed by immobilization with plaster cruropodalic cast with the knee in total extension and a movement in varus applied on the knee to avoid valgus collapse.The immobilization is maintained for four to six weeks, depending on the age of the child.][7][8] Rare metaphyseal fractures become irreducible or unstable when treated by closed methods and this may occur due to the interposition of soft, ligamentary or tendinous (knee flexors) parts.In these cases the recommended treatment is surgical reduction and fixation by means of Kirschner wires, associated with plaster cast immobilization, for a period of 45-60 days.As these fractures are located in a strongly vascularized area, comprised of spongy bone, they consolidate very quickly.
In the post-plaster cast period, physiotherapy should be indicated for muscular strengthening of the affected limb, with particular attention to the quadriceps, as well as to gain and maintain the range of movement of the knee and ankle.Robert et al. 10 , in an analysis of 25 children, reported 12 children with greenstick or complete fracture and 11 with progressive valgus.There were no complications in the tubercle fractures, and in three fractures, there was compensation with distal growth of the shaft.Four children were submitted to corrective osteotomy, there were two recurrences of the deformity and two cases of compartment syndrome.Several authors affirm that the treatment of proximal metaphyseal fractures consolidated in valgus consists of observation and clinical follow-up due to the common occurrence of the spontaneous disappearance of the problem with the development of an "S" shaped tibia. 6,11,12Persistent deformity should only be corrected surgically in puberty. 4,10

Diaphyseal fractures
Fractures of the diaphysis of the tibia or fibula are responsible for approximately 4 to 5% of all pediatric fractures (2,4) .In general, these fractures fall into three categories: -Without deviation -Oblique or spiral -Transverse and comminuted with deviation Less than 4% of these fractures require surgical treatment, and in 70% of the cases they are isolated tibial fractures, which maintains leg length to a certain extent manner, yet predisposes to angular deformity in valgus. 5he tibia has limited remodeling potential.Rotational deformities do not undergo remodeling.Nevertheless, in clinical practice it is observed that the deformity in external rotation is tolerated better that that in internal rotation. 13uring growth, babies and infants can correct approximately 50% of post-fracture residual angulation.In children over 10 years of age, there will only be an improvement of the poor axial alignment in 25% of the cases.Hansen et al. 14 communicated that just 13.5% of their patients achieved correction of angular deformity with subsequent growth, while Shannak 13 observed that 1/3 of the children, with more than 10 degrees of angulation upon consolidation, persisted with some degree of defective consolidation until the final evaluation of the follow-up, which was from three to ten years.And he concluded that, in general, defective alignment in varus appears to remodel more efficiently than deformity in valgus.
][7][8] In cases in which fractures exhibit important edema, the recommended treatment is immobilization with plaster cruropodalic splint for seven to 10 days and subsequent conversion to a plaster cast, with light contact with ground allowed with the aid of two crutches when possible, after four weeks.Between the fourth and sixth weeks, the plaster cruropodalic cast can be converted into a plaster boot for gait in transverse and short oblique fractures and those located between the medial third and distal bones.Radiographic control is performed in the first and third weeks and physiotherapy should be recommended in children from pre-adolescence.The type of osteosynthesis to be used in children is still highly controversial today and not yet totally accepted consensually, with a great deal of respect shown for the experience and common sense of each surgeon.Plates produce good immobilization, yet require incisions that are somewhat extensive and additional procedures to remove them.Their use is not recommended in patients under 12 years of age due to the excessive growth potential that they can produce, due to the stimulus to the fracture union plates. 17s regards the use of rigid intramedullary nails after closed reduction, it is known that although they constitute a very safe method from the surgical point of view, they should only be used in adolescents, after the shaft closing age or very close to it.Nonetheless, in adolescence they can already be used with the same criteria as for adults.Srivastava et al. 18  Most of the fractures (68%) were located in the medial third.The consolidation time was ten weeks (ranging from 7 to 18 weeks) and the follow-up period 11 months (ranging from 8 to 17 months).As complications they observed residual angulation of the tibia, discrepancy of limb length, deep infection and fixation failures, and that in spite of this, the children all showed excellent functional result.Kubiak et al. 21conducted a retrospective review, evaluating the differences in the development of results of tibial fractures in children treated with external fixation versus flexible nails.They reviewed 31 patients that needed surgical treatment of the fractures, treating 16 tibias with flexible nails and 15 with external fixation.They evaluated the rates of complications and the need for further surgery clinically and radiographically.There was no statistical difference between the two groups.The main conclusions of the study included a significantly lower number in relation to the consolidation time for patients in the flexible nail group (7 versus 18 weeks), and a significant rate of bone complications related to the group treated with external fixator.Without any randomized prospective studies comparing flexible nails and external fixation, there is no established consensus on the best fixation of pediatric tibial fractures.However, there appears to be a tendency toward the treatment of these fractures with flexible nails whenever possible.El-adi et al. 22 prospectively evaluated 48 femoral fractures and 25 tibial fractures, treated with flexible intramedullary nails.In spite of complications like vicious consolidation, discrepancy of the lower limbs and irritation in the soft parts related to the entrance points of the nails, all the cases obtained good or satisfactory results."Flexible intramedullary fixation is an easy and effective method in the treatment of unstable exposed and/or closed tibial fractures in children". 20

Open fractures
Open fractures of the tibia in children are a result of high-energy trauma, and are associated with other injuries in 25 to 50% of the cases. 5,6,23,244][25][26] After adequate debridement, first-degree open and clean fractures can have the wound loosely sutured, and a drainage tube can be fixed, but in most cases, the wounds should be left open, as among other reasons, they might be submitted to further debridement. 25reder and Armstrong 24 noticed that a delay of more than six hours in surgical cleaning was correlated to 25% of infection in comparison with 12% for patients operated within a time limit of up to six hours.Other authors, Song et al. 26 and Blazier and Barnes, 27 observed that age is the most significant prognostic indicator.They propose that children under 12 years of age need less aggressive surgical treatment, as their injuries heal faster, they have lower percentages of infection and present fewer complications than children above this age. 26,27n open fractures the use of external fixators is a relatively simple procedure with the advantage of maintaining the reduction and stability of the fracture, besides favoring easy access for the cleaning of wounds.Some models allow patients to walk at an early stage and do not cause limitation of joint movement amplitude, both of the knee and of the ankle.They present low morbidity provided maximum care is taken with possible infections along the course of the pins, to avoid deep infection.Bartlett et al. 28 studied 23 exposed fractures in children aged between 3.5 and 14.5 years, with 18 boys and 5 girls.The types of fracture were: 6 second-degree fractures, 8 type IIIA fractures and 9 type IIIB fractures with 7 comminuting butterfly-wing fractures.The lesion mechanisms were: all the fractures caused by running over by motor vehicles except for two, one of which was the fall of a motor vehicle and the other a collision between a motorcycle and motor vehicle.Five children had other associated lesions (CET, fracture of the acetabulum, femur, humerus, mandible, maxilla, and severe disorders of knee ligaments).The Orthofix monolateral and AO fixators or even Wagner bone lengtheners are those of preferential use due to the ease of installation, and versatility when the correction of any secondary deviations is necessary.Above all, they make it possible to reduce and maintain the reduction as they are extremely resistant to longitudinal traction forces, compression and angulation.Circular fixators and rigid models are not intended for routine use and any indication of these devices in the treatment of traumatic lesions in children is exceptional and should be practiced with prudence.Buckley et al. 29  In a recent review, Gougolias et al. 30 suggest that flexible intramedullary nails are an alternative, yet further studies are necessary to determine their best indication in these cases.

Distal metaphyseal fractures
Treatment is conservative when no unacceptable deviation is observed.Isolated fractures of the tibia or associated with distal fracture of the fibula, can sometimes present deviation and are generally in recurvatum or with lateral angulations.
The vast majority of fractures with deviation require the performance of closed reduction under general anesthesia followed by immobilization for 30 to 45 days, depending on the age of the child, the plaster cast can be of the boot type or longer, reaching above the knee in the case of instability and consequent risk of loss of the reduction.Immobilization is mandatory if the recurvatum is accentuated and with a high possibility of secondary deviation inside the actual cast, including the foot in plantar flexion for a period of three weeks and after this in the anatomical position of 90° in relation to the leg axis. 1,5,6n unstable fractures or fractures with suspicion of interposition where reduction is impossible, the recommended treatment is open exploration; removal of the interposed tissue and after reduction fixation with smooth Kirschner wires with tapered edge or compression screws avoiding crossing the growth plate.

IMMEDIATE COMPLICATIONS Compartment syndrome
Compartment syndrome may sometimes occur in fractures of the proximal third, particularly in the presence of severe trauma affecting the soft parts, after prolonged traumatic compressions or those caused by very tight plaster casts, especially when they are donned in the presence of intense edema or when the child fails to keep the limb in an elevated position.Symptoms and clinical signs, when present, can be confirmed by measuring the compartment pressure and imply urgent measures, which can range from simple removal of the cast and elevation of the limb to decompressive fasciotomy and use of an external fixator to guarantee bone stabilization and to provide freedom to control and care for the soft parts.

Arterial lesion
Although not very frequent, this can occur in proximal epiphyseal detachments of the tibia, injuring the anterior tibial artery.Arterial lesion provoked by spasm can be immediate or of late onset.
It is extremely important for the physician assistant to watch out for the appearance of this severe lesion, as it can culminate in the amputation of the limb.

Neurological lesion
This can be observed in proximal and lateral lesions of the leg caused by injury of the fibular nerve in fibular neck fractures, in proximal tibiofibular dislocations and in exaggerated external compression in the production of the plaster cast.It is important for the physician assistant to search constantly for early signs of nerve compression with hallux extension and presence of paresthesias in the specific territories.

LATE-ONSET COMPLICATIONS Progressive Deformities
Varus or Valgus Knee These can occur in proximal epiphysometaphyseal fractures of the tibia by partial closing of the growth plate.It should become a routine in clinical practice to warn the family about the possible appearance of this kind of complication whenever these fractures are present.According to Koval et al. 1 progressive valgus angulation can result from a combination of factors such as tearing of the perichondrial ring of the lateral shaft at the time of the lesion or the medial exuberant perichondrial callus formation, which results in excessive growth of the fractured bone.Other hypotheses include periosteum incarceration in the medial site of the fracture or concomitant lesion of the pes anserinus ("goosefoot"), which results in loss of the inhibitory effect of pinching on the physis, allowing excessive growth.The deformity is more prominent in the first year after the fracture and younger patients can present spontaneous correction with remodeling.
In relation to the treatment it was recommended, for example, to use resection or addition wedges in the plaster, with inversion of the removed fragment to correct the deformity.
In patients over the age of 12 years professionals have used dome osteotomy, which should be fixed with two crossed Steimann wires, plus plaster cast immobilization for 45-60 days.
Another technique in use is partial epiphysiodesis (lateral or medial), which depending on the residual deviation can be permanent by means of curettage or transitory with Blount staples or transfixing screws.
In distal metaphyseal fractures of the tibia, inadequate reduction or collapse due to caving of the fracture can result in a recurvatum deformity.Younger patients tend to tolerate this better, since remodeling in general makes the deformity insignificant.Older patients might need supramaleolar osteotomy when the recurvatum deformity is so severe it compromises ankle function and gait.

HALT OF EPIPHYSEAL GROWTH
The premature closure of the proximal tibial shaft 1 can occur with unnoticed lesion by crushing (Salter-Harris V), resulting in growth suspension.It most usually affects the anterior shaft, which entails recurvatum deformity of the affected knee.The closing of the distal tibial shaft can also occur in undiagnosed "crushing" lesions (Salter Harris V) in the distal tibial physis, resulting in growth halt.Bone lengthening can be indicated in these cases, depending on the disparity in the residual length or on how much it will be predictable.

WARNING
Progressive varus and valgus deformities are likely to occur after proximal epiphysometaphyseal fractures.There can also be knee recurvatum due to the premature closure of the proximal tibial physis, resulting from an unnoticed lesion caused by crushing.Thus it should become a routine in clinical practice to warn the family of the possible appearance of post-traumatic deformities in the immature skeleton.

ACKNOWLEDGMENT
We are grateful to the Núcleo de Apoio à Publicação da Faculdade de Ciências Médicas da Santa Casa de São Paulo -NAP-SC for their technical and scientific support to the publication of this manuscript.
16ng and Letts16observed 95 children including 61 boys and 34 girls.The distal third of the leg was affected in 69 children, the medial third in 17 and proximal fractures in nine children.In relation to lines, 81 fractures were spiral or oblique, 11 transverse and three comminuted.After the follow-up time of 38.8 months they verified that the consolidation time was five weeks (ranging from 2 to 16 weeks).Of the 95 fractures, 19 were immobilized with plaster cruropodalic cast and 70 presented dislocated fractures with angular deformity having been submitted to closed reduction and immobilization with PTB (patellar tendon-bearing) type plaster.The six fractures resulting from traffic accidents had serious lesions and were submitted to open reduction followed by internal or external fixation.Indirect trauma was the most common mechanism, with 39 fractures resulting from skiing/skating accidents, 38 from falls, three from child abuse and 15 from other road accidents.
Unstable, extensive comminuted, multiple or contralateral leg fractures, polytraumatized fractures (cephalorachidian, thoracic and/ or abdominal trauma) and open fractures, benefit from surgical treatment with temporary or permanent stabilization, to facilitate the handling of the child.