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Vol 10, No 5, September/October 2002 345 The knee is a common site of injury in children and adolescents, especially those who engage in competitive sports. The physician who evaluates and treats fractures in the pediatric age group must be familiar with the types of injuries and complications that are unique to these patients. Fractures of the immature knee, such as those that involve the distal femoral and proximal tibial epiphyses, tibial tubercle apophysis, tibial spine, patella, articular cartilage, and proximal tibial metaphysis, are particularly challenging in terms of establishing the diagnosis and predicting long-term sequelae. An understanding of the classification, clinical and radiographic evaluation, treatment, and potential complications of each type of injury can lead to more effective treatment as well as to clear com- munication with the child’s parents. Distal Femoral Epiphyseal Fractures Classification The most commonly used system to classify fractures involving the distal femoral epiphysis is that of Salter and Harris 1 (Fig. 1). In type I fractures, there is a separation through the physis with no involve- ment of the adjacent metaphysis or epiphysis. Type II fractures are the most common. In these injuries, the fracture line traverses the physis before exiting obliquely across one corner of the metaphysis. Displace- ment is usually toward the side of the metaphyseal fragment. A type III injury consists of a fracture through the physis that exits through the epiphysis into the joint. A type IV fracture consists of a vertical, intra- articular fracture that traverses the metaphysis, physis, and epiphysis. Most type III and IV injuries require accurate reduction, usually supplemented by internal fixation, to align the physis and achieve a congruous joint surface. Type V fractures are crush injuries to the physeal cartilage. These rare injuries are usually diag- nosed in retrospect or by association with the mechanism of injury. Signs and Symptoms The patient with a distal femoral epiphyseal fracture usually presents with effusion of the knee joint, local soft-tissue swelling, and tenderness over the physis. In displaced injuries, deformity may be evident, and soft or muffled crepitus with motion often can be felt. In the anteriorly displaced, or hyperextension, injury, the patella becomes prominent and the anterior skin is often dimpled. With posterior displacement of the epiphysis, the distal metaphyseal fragment becomes prominent just above the patella. Although arterial injury is less common than with a proximal tibial physeal injury, a careful neurovascular examination is Dr. Zionts is Professor, Department of Orthopaedics and Pediatrics, Keck School of Medicine, University of Southern California, and Director, Pediatric Orthopaedics, Women’s and Children’s Hospital, University of Southern California Medical Center, Los Angeles, CA. Reprint requests: Dr. Zionts, Room 3L-31, 1240 North Mission Road, Los Angeles, CA 90033. Copyright 2002 by the American Academy of Orthopaedic Surgeons. Abstract Traumatic forces applied to the immature knee result in fracture patterns differ- ent from those in adults. The relative abundance of cartilage in the knee of the growing child may make the diagnosis of certain injuries more challenging. If plain radiographs fail to reveal a fracture, a stress radiograph, computed tomography scan, or magnetic resonance imaging study may help to establish the diagnosis. Certain fractures, such as hyperextension injuries to the distal femoral or proximal tibial epiphysis, or displaced tibial tuberosity fractures, may be especially susceptible to neurovascular problems. Although the use of appropriate treatment techniques may minimize the occurrence of late complications such as malunion and physeal bridging, not all problems are preventable. A careful discussion of the injury with both patient and parents should stress the importance of follow-up so that any problems that do occur can be promptly addressed. J Am Acad Orthop Surg 2002;10:345-355 Fractures Around the Knee in Children Lewis E. Zionts, MD warranted to rule out damage to the popliteal vessels or peroneal nerve. Imaging Studies Anteroposterior and lateral radiographs should routinely be obtained to evaluate the displacement of the fractures. Oblique radiographs may help reveal minimally displaced fractures. Gentle-stress radiographs can help differentiate a physeal separation from a ligamentous injury in a patient who has pain and apparent laxity of the knee and whose plain radiographs fail to reveal a fracture. Adequate analgesia can alleviate muscle spasm and protect the physis from further damage during the examination. Magnetic resonance imaging (MRI) or computed tomography (CT) also may help to identify fracture lines in nondisplaced injuries. 2,3 Naranja et al 3 found MRI useful for diagnosing fractures when an injury was not apparent on plain radiographs, especially in children with a preceding traumatic event, effusion or swelling, and refusal to bear weight on the extremity (Fig. 2). Treatment The goals of treatment are to obtain and maintain an anatomic reduction and avoid further damage to the physis. The form of treatment is determined by both the fracture type and the degree of displacement. For Salter-Harris type I and II injuries, nondisplaced fractures are immobilized for 4 to 6 weeks in either a long leg cast or hip spica cast. The duration of immobilization will vary with the age of the patient. Short, obese children, or patients who may be unreliable, are better managed in a spica cast. 4 Displaced fractures should be reduced under general anesthesia. Longitudinal traction can be used during the reduction maneuver to avoid further damage to the physis. Internal fixation makes subsequent displacement less likely, allows the use of a long leg cast with a greater margin of safety, and avoids the need to immobilize the knee in an extreme position of flexion or extension to maintain the reduction. 4,5 Smooth transphyseal pins are used for type I injuries and for type II injuries with small metaphyseal fragments. Bending and burying the pins just beneath the skin can minimize the risk of bacterial contamination of the knee joint. Type II fractures with an adequately sized metaphyseal fragment may be stabilized using pins or AO cannulated screws across the metaphyseal portion of the fracture fragment (Fig. 3). Open reduction is indicated for any type I or II fracture that is irreducible by closed means. For Salter-Harris type III and IV injuries, nondisplaced and stable fractures may be managed by cast immobilization alone. Careful follow- up of these patients at weekly intervals is needed so that any displacement may be promptly addressed. Alternatively, these injuries may be stabilized using percutaneous pins or screws to minimize the risk of late displacement. Open reduction and internal fixation is indicated for all displaced type III and IV fractures to restore congruity of the joint surface and to align the physis. Because these are intra-articular fractures, full weight bearing is not begun until radiographs demonstrate adequate fracture healing. Outcome At most anatomic locations, a growth disturbance after a type I or II injury is rarely seen. However, when these fractures involve the distal femoral epiphysis, problems with shortening and angular deformity are more common. 4,6 Presumably this is because greater forces are required to disrupt the distal femoral physis, and the undulating shape of this growth plate renders it more susceptible to damage by shearing and compressive stresses. Growth distur- Fractures Around the Knee in Children Journal of the American Academy of Orthopaedic Surgeons 346 Type I Type II Type III Type IV Type V Figure 1 The Salter-Harris classification 1 for fractures of the distal femoral epiphysis. The dashed line indicates the fracture line. (Reproduced with permission from Edwards PH Jr, Grana WA: Physeal fractures about the knee. J Am Acad Orthop Surg 1995;3:63-69.) bances are more likely to occur with fractures in younger patients and after fractures that are initially displaced more than one half the diame- ter of the shaft. 5,6 Riseborough et al 4 observed that fractures of the distal femoral epiphysis in patients 2 to 11 years of age were caused by more severe trauma and were more likely to lead to growth problems than similar fractures in adolescents. Careful clinical evaluation is recommended at 6 months after the injury to detect physeal irregulari- ties that may suggest an impending growth disturbance. 7 Comparative radiographs of both lower extremi- ties are helpful for detecting these changes early. The patients should be followed at regular intervals until skeletal maturity because both growth deceleration 4 and growth stimulation 5 can occur after distal femoral physeal injuries. The precise amount of leg-length discrepancy that requires treatment remains controversial. Generally, leg-length inequalities estimated to be <2 cm at skeletal maturity can be managed nonsurgically. If the estimated discrepancy at maturity is 2 to 5 cm, an appropriately timed epiphysiodesis of the contralateral extremity may be indicated. For inequalities estimated to be >5 cm at maturity, leg lengthening should be considered. Significant angular deformity resulting from malunion or a partial growth arrest may be managed by osteotomy or by hemiepiphysiode- sis. When an osseous bridge is present, resection may be considered in children who have at least 2 years of growth remaining and whose lesions occupy <50% of the growth plate. MRI is now the imaging modality of choice to evaluate these lesions. Three-dimensional modeling can be used to produce physeal maps that show the site and extent of the abnormality, which are useful for preoperative planning. 8,9 Oste- otomy combined with concomitant epiphysiodesis may be indicated in children who have larger physeal bridges or who are approaching skeletal maturity. Proximal Tibial Epiphyseal Fractures Classification The most commonly used classification system for fractures of the proximal epiphysis of the tibia is that of Salter and Harris 1 (Fig. 4). It corre- sponds to the system used for the distal femur. Type I is a separation through the physis without involve- ment of the adjacent metaphyseal or epiphyseal bone. Type II traverses the physis before exiting obliquely across one corner of the metaphysis. These fractures are usually the result of a Lewis E. Zionts, MD Vol 10, No 5, September/October 2002 347 A D B C Figure 2 A 13-year-old boy sustained an injury to his right knee. Anteroposterior (A) and lateral (B) radiographs did not show a fracture. Sagittal T2-weighted (C) and axial fast spin echo (D) MRIs revealed a nondisplaced Salter-Harris type IV fracture of the proximal tibia (arrows). (Panels A–C reproduced with permission from Zionts LE: Fractures and dislocations around the knee, in Green NE, Swiontkowski MF: Skeletal Trauma in Children, ed 3. Philadelphia, PA: WB Saunders, in press.) Fractures Around the Knee in Children Journal of the American Academy of Orthopaedic Surgeons valgus stress with the metaphyseal fragment on the lateral side. Type III is a fracture through the physis that exits through the epiphysis into the joint. Type IV is a vertical, intra-articular fracture through the metaphysis, physis, and epiphysis. These fractures may involve either the medial or lateral tibial plateau. Signs and Symptoms The patient with a fracture of the proximal tibial epiphysis presents with an effusion of the knee joint, local soft-tissue swelling, and tenderness over the physis. Deformity is present in displaced injuries. Because of its close proximity to the proximal tibial epiphysis, the popliteal artery is potentially at risk in these injuries. Posterior displacement of the tibial shaft in relation to the epiphysis, as may occur after a hyperextension injury, can produce a laceration or thrombosis of the popliteal artery (Fig. 5). Because the fracture may partially or completely reduce before the patient is evaluated, arterial injury must be considered in every patient with this injury. 10 The guidelines for evaluating children who sustain this injury are similar to those used for adults after a traumatic knee dislocation. A careful neurovascular examination must be done, documenting the presence of the dorsalis pedis and posterior tibial arterial pulses, the status of the distal perfusion of the limb, and the function of the posterior tibial and peroneal nerves. In an obviously ischemic extremity, the displacement should be reduced as soon as possible. If the vascular deficit persists, an arterial explo- 348 A DB C Figure 3 Anteroposterior (A) and lateral (B) radiographs of a Salter-Harris type II fracture (arrows) of the distal femur in a 9-year-old boy. Anteroposterior (C) and lateral (D) posttreatment radiographs. The fracture was stabilized using two AO cannulated screws across the metaphyseal portion of the fragment, supplemented by immobilization in a long leg cast for 4 weeks. Figure 4 The Salter-Harris classification 1 for fractures of the proximal tibial epiphysis. (Adapted with permission from Hensinger RN [ed]: Operative Management of Lower Extremity Fractures in Children. Park Ridge, IL: American Academy of Orthopaedic Surgeons, 1992, p 49.) Type I Anteroposterior view Lateral view Type II Type III Type IV ration should be performed imme- diately. In the absence of an obviously ischemic limb, patients who have a diminished or absent pulse, or those who recover pulses and perfusion after reduction of the fracture, should undergo arteriogra- phy. 11,12 Ongoing evaluation of the lower extremity is important during the first few days after the fracture so that a developing compartment syndrome or intimal tear with thrombosis may be detected promptly. Imaging Studies Anteroposterior and lateral radiographs usually reveal the fracture. When the plain radiographs appear to be normal, gentle-stress radiogra- phy or MRI may be used to detect a nondisplaced or otherwise obscure injury, as described for the distal femur. When stress radiographs are considered, hyperextension should probably be avoided. On occasion, CT may be used to evaluate and classify injuries more fully, especially in Salter-Harris type III and IV fractures that involve the articular surface 13 (Fig. 6). Treatment The goals of treatment are to obtain and maintain an anatomic reduction and to avoid further damage to the growth plate. For Salter- Harris type I and II injuries, nondisplaced fractures are immobilized in a long leg cast for 4 to 6 weeks, de- pending on the age of the patient. Displaced fractures are gently reduced under general anesthesia to avoid further damage to the growth plate. Because many of these fractures are the result of hyperextension injuries, flexion usually achieves reduction. Immobilization of the knee in marked flexion may increase the risk of vascular compromise and thus should be avoided. The use of internal fixation allows the knee to be immobilized in 20° to 30° of flexion, a position that poses less risk to the circulation and makes subsequent displacement not as likely. Smooth, crossed transphyseal pins are used for type I and II fractures with small metaphyseal fragments. Type II fractures with an adequately sized metaphyseal fragment may be stabi- Lewis E. Zionts, MD Vol 10, No 5, September/October 2002 349 Figure 5 Lateral view of the knee showing the potential for popliteal artery laceration or thrombosis (arrow) after a hyperextension injury to the proximal tibial physis. (Adapted with permission from Tolo VT: Fractures and dislocations around the knee, in Green NE, Swiontkowski MF [eds]: Skeletal Trauma in Children. Philadelphia, PA: WB Saunders, 1994, vol 3, pp 369-395.) Popliteal artery A D B C Figure 6 Salter-Harris type IV fracture of the proximal tibia in a 12-year-old boy. A, Anteroposterior radiograph does not demonstrate the fracture well (arrows). B, Coronal reconstruction CT scan shows the fracture line (arrows) more clearly. C, Axial CT view of the joint surface shows minimal displacement at the articular surface (arrows). D, The fracture was stabilized with two AO screws inserted percutaneously. lized using pins or AO cannulated screws across the metaphyseal portion of the fracture. Open reduction is indicated for irreducible type I and II fractures. Nondisplaced Salter-Harris type III and IV injuries may be placed in a long leg cast for 6 weeks. Careful follow-up of these patients at weekly intervals is necessary to address any displacement promptly. Alternatively, cannulated screws may be inserted percutaneously to stabilize these fractures (Fig. 6). Displaced fractures are treated by open reduction and internal fixation to restore congruity of the joint surface and to align the physis. After reduction, smooth pins or screws are inserted horizontally to avoid crossing the physis. Because these fractures are intra-articular, full weight bearing should not be allowed until radiographs show complete healing. Outcome In general, the prognosis for a closed fracture of the proximal tibial epiphysis is good. Shortening and angular deformity are uncommon because these fractures tend to occur in older children and adolescents and because the proximal tibial epiphysis contributes less to the overall growth of the limb than does the distal femur. Open injuries to the proximal tibial epiphysis have a much poorer prognosis. These fractures are often caused by lawnmower mishaps 10 that result in damage to the perichondral ring. Angular deformities, either alone or in combination with limb shortening, are commonly seen after these open injuries. Tibial Tubercle Fractures Classification Watson-Jones 14 classified fractures of the tibial tubercle into three types. Ogden et al 15 modified this classification to include two subtypes, A and B, according to the severity of displacement and comminution (Fig. 7). In type IA, the fracture is distal to the normal junction of the ossification centers of the proximal end of the tibia and tuberosity. In type IB, the fragment is displaced (hinged). In type IIA, the fracture is at the junction of the ossification centers of the proximal end of the tibia and tuberosity. In type IIB, the fragment is comminut- ed and the more distal fragment is usually proximally displaced. Type III fractures extend into the joint. Type IIIA is not comminut- ed; type IIIB is. Signs and Symptoms Fractures of the tibial tubercle most often occur in males between 12 and 17 years of age. These injuries are most frequently associated with sports activities, particularly basket- ball and competitive jumping events. Injury is caused by either violent con- traction of the quadriceps muscle, as occurs with jumping, or acute passive flexion of the knee against a con- tracted quadriceps muscle, as occurs when a football player is tackled. The patient with a fracture of the tibial tubercle presents with local soft-tissue swelling and tenderness directly over the tubercle. Patients with a type I injury usually are able to extend the knee against gravity, whereas those with a type II or III injury are unable to do so. Most of the patients with type II and III fractures have a hemarthrosis of the knee joint. Imaging Studies Accurate lateral radiographs of the tubercle are essential to evaluate this injury. Because the tubercle is just lateral to the midline of the tibia, the best profile is obtained with the leg in slight internal rota- tion. Oblique radiographs of the proximal end of the tibia are helpful to visualize fully the extension of the fracture into the knee joint. 15 Treatment Nondisplaced type I fractures (IA) can be treated successfully by immobilization in a cylinder cast or long leg cast with the knee in full extension for 4 to 6 weeks, followed by progressive rehabilitation of the quadriceps muscle. Displaced type I injuries, as well as nearly all type II and III injuries, are best treated by open reduction and internal fixation through a midline vertical incision. Any interposed soft tissue, such as a flap of periosteum, is removed to facilitate an accurate reduction. In all type III injuries, the menisci should be inspected for tears or peripheral detachments. Fractures Around the Knee in Children Journal of the American Academy of Orthopaedic Surgeons 350 Type IA Type IIA Type IIIA Figure 7 The Watson-Jones 14 classification of fractures of the tibial tubercle as modified by Ogden et al. 15 (Reproduced with permission from Edwards PH Jr, Grana WA: Physeal fractures about the knee. J Am Acad Orthop Surg 1995;3:63-69.) Type IB Type IIB Type IIIA Osseous fixation may be achieved with pins or screws. Cancellous screws placed horizontally through the tubercle into the metaphysis afford stable fixation. Wiss et al 16 recommended the use of 4.0-mm cancellous screws rather than larger implants, such as 6.5-mm screws, to lessen the incidence of bursitis that may develop over prominent screw heads. Washers may be helpful to prevent the screw head from sinking below the cortical surface. The con- tinuity of the patellar ligament and avulsed periosteum is also repaired. If severe comminution is present, a tension-holding suture may be necessary to secure the repair. Postoperatively, the patient wears a cylinder or long leg cast for 4 to 6 weeks, followed by progressive rehabilitation of the quadriceps muscle. Return to regular activities is permitted after the quadriceps has regained normal strength and a full range of motion of the knee joint has been achieved. Mirbey et al 17 permitted their patients to resume sports activities at an average of 3 months after injury; however, after type II and III injuries, patients may require 16 to 18 weeks after cast removal to return to their preinjury activity levels. 15 Outcome The prognosis for a fracture of the tibial tubercle is very good. Compli- cations are uncommon. The theoretic complication of genu recurvatum has not been reported because most of these injuries occur when the physis is nearing normal physiologic closure. Compartment syndrome, presumably caused by tearing of nearby branches of the anterior tibial recurrent artery, has been reported after tibial tubercle fractures. 16,18 Patients should be carefully monitored and those treated surgically considered for prophylactic anterior compartment fasciotomy. Bursitis over prominent screw heads that necessitates removal of the implant has been reported. 16 Tibial Spine Fractures Classification The anterior tibial spine, or eminence, is the distal site of attachment of the anterior cruciate ligament. Before ossification of the proximal tibia is complete, the surface of the spine is cartilaginous. When exces- sive stresses are applied to the anterior cruciate ligament, the incom- pletely ossified tibial spine offers less resistance than does the ligament, resulting in a fracture through the cancellous bone beneath the tibial spine. Traumatic forces that would cause a tear of the anterior cruciate ligament in an adult commonly lead to a tibial spine fracture in a child. Meyers and McKeever 19 classified tibial spine fractures into three main types (Fig. 8). In type I fractures, the fragment is minimally displaced, with only slight elevation of the anterior margin. In type II fractures, the anterior portion of the avulsed fragment has a posterior hinge and the anterior portion is ele- vated. In type III fractures, the avulsed fragment is completely displaced and may be rotated. Signs and Symptoms Fractures of the tibial spine usually occur in children 8 to 14 years of age and are often the result of a fall from a bicycle. The patient with a fracture of the tibial spine typically presents with pain, a hemarthrosis, and a reluctance to bear weight. The knee may be held in a slightly flexed position because of hamstring spasm. Imaging Studies Anteroposterior and lateral radiographs will demonstrate a tibial spine fracture, with the degree of displacement best evaluated on the lateral view. Radiographs often un- derestimate the size of the avulsed fragment, which is largely cartilaginous. When routine radiographs show only small flecks of bone in the intercondylar notch, MRI may be useful to further assess the injury. Treatment Type I fractures and minimally displaced type II fractures may be treated by closed means. If a tense hemarthrosis is present, an aspira- tion of the knee joint should be performed under sterile conditions and a long leg cast applied. Although the Lewis E. Zionts, MD Vol 10, No 5, September/October 2002 351 Figure 8 The Meyers and McKeever 19 classification for tibial spine fractures. (Adapted with permission from Tolo VT: Fractures and dislocations around the knee, in Green NE, Swiontkowski MF [eds]: Skeletal Trauma in Children. Philadelphia, PA: WB Saunders, 1994, vol 3, pp 369-395.) Type I Type II Type III ideal position of immobilization is still the subject of some controversy, 10° of flexion seems to be an opti- mal position to immobilize the knee joint. Some authors have suggested immobilizing the knee in greater flexion to relax the anterior cruciate ligament. 19,20 Hyperextension probably should be avoided so as not to compromise the distal circulation. Radiographs should be done to confirm the reduction of the tibial spine fragment and repeated in 1 to 2 weeks to ensure that displacement has not occurred. The cast usually can be removed in 6 weeks and rehabilitation of the knee initiated. Surgical reduction, either arthroscopically assisted 21,22 or through an anteromedial arthrotomy, is indicated for irreducible type II fractures and all type III fractures. The anterior horn of the medial meniscus, if interposed, is removed from the fracture site to facilitate an accurate reduction. When reduction is performed through an arthrotomy, the fragment can be secured using an absorbable suture passed through the cartilaginous portion of the fracture fragment and the anterior tibial epiphysis. After arthroscopic reduction, either an absorbable suture or cancellous screw can be used to fix the fragment. In an adolescent patient with a small fragment, fixation may be achieved by weaving a non- absorbable pullout suture through the anterior cruciate ligament with the ends passed through drill holes in the anterior tibia. Postopera- tively, the knee is immobilized in 10° to 20° of flexion in a long leg cast. The cast is removed in 6 weeks and rehabilitation is begun. Outcome A good outcome may be expected for fractures of the tibial spine, at least in the short term. Nonunion of properly treated fractures is rare. Several authors have documented anterior cruciate laxity and some loss of full knee extension despite healing of the fracture in an anatomic position. 23-25 This laxity has been attributed to interstitial tearing of the anterior cruciate ligament that presumably occurs before the fragment is avulsed. Late laxity varies according to the severity of the ini- tial injury. Compared with type I injuries, greater laxity has been noted after type II and III fractures. 24 Despite the laxity, few patients complain of pain or instability. Few long-term studies of this injury have been published. For an average of 16 years, Janarv et al 26 followed 61 children who had anterior tibial spine fractures. Although most of their patients had a good clinical result at long-term follow-up, these authors found no evidence to suggest that the anterior knee laxity resulting from the injury diminished over time. Because of the persistent laxity of the anterior cruciate ligament, which has been documented in several studies, 23-26 the long-term prognosis for this injury remains unclear, and parents of children with this injury should be appropriately counseled. Patellar Fractures Classification Patellar fractures rarely occur in children because the patella is largely cartilaginous and has greater mobil- ity than in adults. Ossification of this sesamoid bone does not begin until 3 to 5 years of age. 27 Most patellar fractures occur in adolescents when ossification is nearly complete. 28 Fractures of the patella are generally classified according to the location, pattern, and degree of displacement. Houghton and Ackroyd 29 described the so-called sleeve fracture that occurs through the cartilage on the inferior pole of the patella (Fig. 9). This fracture occurs most commonly in children 8 to 12 years of age. A large sleeve of cartilage is pulled off the main body of the patella along with a small piece of bone from the distal pole. The diagnosis of this injury may be missed because the distal bony fragment is not readily discernible on radiographs. Grogan et al 30 observed that avulsion fractures can involve any segment of the patellar periphery. They described four patterns of injury: superior, inferior, medial (which often accompanies an acute lateral dislocation of the patella), and lateral (which they attributed to chronic stress from repetitive pull from the vastus lateralis muscle). Signs and Symptoms The patient with a fracture of the patella usually demonstrates local tenderness, soft-tissue swelling, and hemarthrosis of the knee joint. Active extension of the knee is difficult, especially against resistance. A palpable gap at the lower end of the patella suggests the presence of a Fractures Around the Knee in Children Journal of the American Academy of Orthopaedic Surgeons 352 Articular cartilage Figure 9 Lateral view of a sleeve fracture of the patella. (Adapted with permission from Tolo VT: Fractures and dislocations around the knee, in Green NE, Swiontkow- ski MF [eds]: Skeletal Trauma in Children. Philadelphia, PA: WB Saunders, 1994, vol 3, pp 369-395.) sleeve fracture. A high-riding patella implies that the extensor mechanism has been disrupted. With marginal fractures, local tenderness and swelling are present over the medial or lateral margin of the patella, and straight-leg raising may still be possible. The presence of an avulsion fracture of the medial margin suggests an acute patellar dislocation that may have reduced spontaneously. When an acute patellar dislocation is suspected, other findings, such as tenderness over the medial retinaculum and a positive apprehension sign, also might be noted on physical examination. Imaging Studies Anteroposterior and lateral radiographs are necessary to evaluate fractures of the main body of the patella. Transverse fractures are best seen on the lateral view. A lateral radiograph taken with the knee in 30° of flexion may better ascertain the soft-tissue stability and true extent of displacement. 30,31 Small flecks of bone adjacent to the inferior pole in a patient who has sustained an acute injury may indi- cate that a sleeve fracture is present. MRI may be useful for diagnosing a sleeve fracture when the diagnosis is not clear from the clinical and plain radiographic findings. 32 Marginal fractures that are oriented longitudinally may be best seen on a skyline-view radiograph. Treatment Treatment guidelines for patellar fractures in children are generally the same as those for adults. Closed treatment in a cylinder cast with the knee in extension is recommended for nondisplaced fractures, particularly if active extension of the knee is present. Surgical treatment is indicated for transverse fractures that show more than 3 mm of dias- tasis or step-off at the articular surface. 31,33 Fixation may be achieved using the AO tension band tech- nique, a circumferential wire loop, or interfragmentary screws. The retinaculum should be repaired at the time of osseous fixation. Partial or total patellectomy should be reserved for injuries with wide- spread comminution. Sleeve fractures should be accurately reduced and stabilized using modified tension band wiring around two longitudinally placed Kirschner wires. Small marginal fractures are probably best excised. If a large portion of the articular surface is involved, screw fixation of the fragment may be preferable to excision. Outcome The outcome after a fracture of the patella is generally good. Re- sults are poorer with fractures that show greater displacement and comminution. 28 If displaced fractures are not accurately reduced, complications can include patella alta, extensor lag, and quadriceps muscle atrophy. 31 Osteochondral Fractures Classification Osteochondral fractures of the knee are most often the result of a direct blow on a flexed knee or shearing forces associated with an acute dislocation of the patella. Rorabeck and Bobechko 34 described three fracture patterns following acute patellar dislocations in children: inferomedial fracture of the patella, fracture of the lateral femoral condyle, and a combination of the two. They estimated that osteochondral fractures occur in approxi- mately 5% of all acute patellar dislocations in children. Others have demonstrated a much higher rate of osteochondral fracture after acute dislocation of the patella in the pediatric age group. Nietosvaara et al 35 found associated osteochondral fractures, either capsular avulsions or intra-articular loose bodies, in 28 of 72 children (39%) after an acute dislocation of the patella. Stanitski and Paletta 36 reported arthroscopically documented articular injuries in 34 of 48 older children and adolescents (71%) after acute patellar dislocation. Signs and Symptoms The patient with an osteochondral fracture of the knee presents with a painful, swollen joint. The patient is reluctant to bear weight, and any attempt to flex or extend the knee is resisted. Tenderness may be elicited over the injured portion of the articular surface. A sterile aspi- ration of the knee joint is likely to yield a hemarthrosis and fat glob- ules, a finding that may suggest the presence of an osteochondral fracture somewhere in the knee. After an acute patellar dislocation, the patient also may exhibit tenderness or a palpable gap along the medial patellar retinaculum and a positive apprehension sign. Imaging Studies Osteochondral fractures may be difficult to see on plain anteroposterior and lateral radiographs, especially if the ossified portion of the fragment is small. Oblique, skyline, and notch views should be obtained when an osteochondral fracture is suspected. Stanitski and Paletta 36 found that only 8 of 28 osteochondral loose bodies retrieved at arthroscopic examination (29%) could be identi- fied on a complete four-view radiographic series. Arthrography, CT, and MRI 37 may better visualize fragments that are largely cartilaginous. Treatment Most authorities recommend surgical management of acute osteochondral fractures of the knee. 31,34 Whether the fragment is excised or reattached depends on its size and origin. There is no agreement as to the size of the fragment that man- dates reattachment. In general, if the fragment is small and from a Lewis E. Zionts, MD Vol 10, No 5, September/October 2002 353 non–weight-bearing surface, it may be removed arthroscopically. Larger fragments from weight-bearing areas should be replaced. Numerous fixation techniques have been used with comparable results, including small, threaded Steinmann pins inserted in a retrograde fashion, coun- tersunk AO minifragment screws, Herbert screws, fibrin sealant or other adhesives, and biodegradable pins. After reattachment, weight bearing should be avoided until radiographs confirm that healing of the fragment is complete. Outcome A good result may be expected after removal of small fragments that do not involve the weight-bearing surface of the joint. The outcome is less certain for large fracture fragments from a weight-bearing area. Complications include stiffness because of adhesions and quadriceps muscle atrophy. Patients whose osteochondral fractures occurred as a result of an acute patellar dislocation may experience recurrent sub- luxation or dislocation. This complication is most prevalent in patients whose first dislocation occurred in their early teenage years and in those with predisposing anatomic factors in the unaffected knee, such as passive lateral hypermobility of the patella, a dysplastic distal third of the vastus medialis obliquus muscle, and a high and/or lateral position of the patella. 38 Proximal Tibial Metaphyseal Fractures Classification Fractures involving the proximal metaphysis of the tibia are unusual injuries in children. The most common type of fracture in this region is a minimally displaced, valgus green- stick injury. The fracture line usually extends two thirds of the way across the proximal metaphysis of the tibia although, in some instances, the fracture may extend completely across. Despite their innocuous appearance, these fractures often develop a progressive valgus angulation during fracture healing as well as after union of the fracture. Signs and Symptoms These injuries are seen most often in children younger than 10 years of age and are usually the result of low-energy trauma. The patient with a minimally displaced fracture of the proximal metaphysis of the tibia presents with pain, swelling, and tenderness at the fracture site. Imaging Studies Anteroposterior and lateral radiographs usually reveal the fracture, which is most apparent on the anteroposterior view. Treatment Minimally displaced fractures of the proximal tibial metaphysis may be treated by closed methods. Treat- ment is directed toward correcting the valgus angulation and closing the medial gap at the fracture site. The lower limb is immobilized in a long leg cast with the knee in extension, and varus molding is applied to the fracture site. Healing is usually complete by 4 to 6 weeks. Outcome The most common problem associated with a minimally displaced fracture of the proximal tibial metaphysis is progressive valgus angulation. The angulation occurs most rapidly during the first 12 months after the injury and continues at a slower rate for as long as 18 to 24 months. 39,40 It is important to emphasize to parents the possibility of subsequent deformity despite adequate and appropriate treatment of the fracture. Although the exact cause of the deformity is not known, relative overgrowth of the medial portion of the proximal tibial physis, presumably because of fracture-induced hyperemia, probably plays a role. 41 In a series of children with posttraumatic tibia valga, Ogden et al 39 found a generalized increase in longitudinal growth of the injured tibia both proximally and distally, and an eccentric proximal medial overgrowth in every patient. Early corrective osteotomy generally is not indicated in the treatment of this problem because of the high rate of recurrence after osteotomy and the trend toward spontaneous improvement of the angulation as the child grows. 40 McCarthy et al 42 compared the results of surgical ver- sus nonsurgical treatment in a series of children with posttraumatic tibia valga. They found no significant difference in lower-extremity align- ment between the groups at the time of injury, at maximal deformity, or at latest follow-up. For an average of 15 years, Tuten et al 43 followed seven patients with posttraumatic tibia valga and found in all patients that spontaneous improvement of the angulation had occurred, resulting in a clinically well-aligned, asymptomatic limb in most. They concluded that patients with this deformity should be followed through skeletal maturity and that surgical intervention should be reserved for patients who have symptoms caused by malalignment. Summary Awareness of the unique types of fractures that occur around the knee of the growing child will allow the physician to make a prompt and accurate diagnosis, apply appropriate treatment techniques, and antici- pate potential problems. An adequate discussion with both patient and parents should emphasize the importance of follow-up care to allow early detection and management of any complications. Fractures Around the Knee in Children Journal of the American Academy of Orthopaedic Surgeons 354 [...]... Riseborough EJ, Barrett IR, Shapiro F: Growth disturbances following distal femoral physeal fracture-separations J Bone Joint Surg Am 1983;65:885-893 5 Thomson JD, Stricker SJ, Williams MM: Fractures of the distal femoral epiphyseal plate J Pediatr Orthop 1995;15: 474-478 6 Lombardo SJ, Harvey JP Jr: Fractures of the distal femoral epiphyses: Factors influencing prognosis: A review of thirty-four cases... Ogden JA, Ogden DA, Pugh L, Raney EM, Guidera KJ: Tibia valga after proximal metaphyseal fractures in childhood: A normal biologic response J Pediatr Orthop 1995;15:489-494 40 Zionts LE, MacEwen GD: Spontaneous improvement of post-traumatic tibia valga J Bone Joint Surg Am 1986;68: 680-687 41 Zionts L, Harcke HT, Brooks KM, MacEwen GD: Posttraumatic tibia valga: A case demonstrating asymmetric activity... Smith JB: Knee instability after fractures of the intercondylar eminence of the tibia J Pediatr Orthop 1984;4:462-464 Baxter MP, Wiley JJ: Fractures of the tibial spine in children: An evaluation of knee stability J Bone Joint Surg Br 1988;70:228-230 Willis RB, Blokker C, Stoll TM, Paterson DC, Galpin RD: Long-term follow-up of anterior tibial eminence fractures J Pediatr Orthop 1993;13:361-364 Janarv PM,... McKeever FM: Fracture of the intercondylar eminence of the tibia J Bone Joint Surg Am 1970;52:1677-1684 Fyfe IS, Jackson JP: Tibial intercondylar fractures in children: A review of the classification and the treatment of malunion Injury 1981;13:165-169 Mah JY, Adili A, Otsuka NY, Ogilvie R: Follow-up study of arthroscopic reduction and fixation of type III tibial-eminence fractures J Pediatr Orthop 1998;18:475-477... Watson-Jones R (ed): Fractures and Joint Injuries, ed 4 Baltimore, MD: Williams & Wilkins, 1955, vol 2, pp 751-800 15 Ogden JA, Tross RB, Murphy MJ: Fractures of the tibial tuberosity in Vol 10, No 5, September/October 2002 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 adolescents J Bone Joint Surg Am 1980;62:205-215 Wiss DA, Schilz JL, Zionts L: Type III fractures of the tibial tubercle in adolescents J... Ogden JA: Avulsion fractures of the patella J Pediatr Orthop 1990;10:721-730 31 Beaty JH, Kumar A: Fractures about the knee in children J Bone Joint Surg Am 1994;76:1870-1880 32 Shands PA, McQueen DA: Demonstration of avulsion fracture of the inferior pole of the patella by magnetic resonance imaging: A case report J Bone Joint Surg Am 1995;77:1721-1723 33 Ray JM, Hendrix J: Incidence, mechanism of injury,... JA: Growth slowdown and arrest lines J Pediatr Orthop 1984;4: 409-415 8 Borsa JJ, Peterson HA, Ehman RL: MR imaging of physeal bars Radiology 1996;199:683-687 9 Craig JG, Cramer KE, Cody DD, et al: Premature partial closure and other deformities of the growth plate: MR imaging and three-dimensional modeling Radiology 1999;210:835-843 10 Burkhart SS, Peterson HA: Fractures of the proximal tibial epiphysis . com- munication with the child’s parents. Distal Femoral Epiphyseal Fractures Classification The most commonly used system to classify fractures involving the distal femoral epiphysis is that of Salter and. classification system for fractures of the proximal epiphysis of the tibia is that of Salter and Harris 1 (Fig. 4). It corre- sponds to the system used for the distal femur. Type I is a separation through. and the function of the posterior tibial and peroneal nerves. In an obviously ischemic extremity, the displacement should be reduced as soon as possible. If the vascular deficit persists, an

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