Cắt cầu Physeal ppsx

Physeal Bridge Resection Khalid I. Khoshhal, FRCS Edin, ABOS, and Gerhard N. Kiefer, MD, FRCSC Abstract The physes, located near each end of the long bones, are responsible for bone lengthening during growth. The physis is composed of cartilage, bone, and a fibrous component that sur- rounds the periphery of the growth plate. The cartilage has three main lay- ers: resting and germinal cells, pro- liferating cells, and hypertrophying cells. The matrix of the physis is composed of collagen, proteoglycans, and glycoproteins. Collagen provides strength and stability to the cartilage, particularly in response to shear forc- es. Proteoglycans give cartilage its compressive strength and the ability to resist deformation. Glycoproteins organize the collagen and proteoglycans into a mesh. The layer of hypertrophying cells in the cartilage is struc- turally weak because the matrix is scanty. Most physeal fracture separations occur at the layer of hypertrophying cells or at the chondro-osseous junction. 1 However, depending on the mechanism of injury, Salter-Harris type I and II physeal fractures sometimes involve the germinal cell layer. 2,3 In experimental studies on im- mature bovine bones, Moen and Pelker 4 suggested that the rate of load- ing, the maturity of the physis, the spe- cific type of joint, and sex may influ- ence the pattern of the fracture and the layer involved. Growth arrest after trauma is most likely during early adolescence,when the physis isthickest and the cartilage is weakest. The groove of Ranvier, which contains osteoblastic, prechon- drogenic, and fibrous cells, is an area of intense cellular division that con- tributes to the horizontal growth of the physis. 5 The perichondrial ring of LaCroix, 6 which consists ofa thin ring of intramembranous bone andan out- er fibrous layer, supports the weak chondro-osseous junction. Injuries to these peripheral portions of the physis also cause growth disturbances. Fifteen percent to 30% of injuries to long bones during childhood involve the physis. 7,8 Significant growth disturbances occur with approximately 10% of physeal injuries; mi- nor disturbances are seen in a higher percentage of patients. 8 The location and size of the physeal bridge determine the clinical deformity. When the physis is affected peripherally, teth- ering can cause angular deformity. When the physis is affected centrally, growth at the periphery causes metaphyseal tenting (Fig. 1). This tenting is associated with bone growth defi- ciency and potential alteration of the articular surface. Fortunately, not all patients who develop a physeal bridge requir e treatment. These physeal injuries occur most commonly in adolescents, who have limited gr owth remaining. Some physeal bridges re- solve spontaneously. 9,10 Although physeal bridges start to form between 1 and 2 months after injury, they may not become clini- cally evident until years later, particularly if the injury occurs when Dr. Khoshhal is Assistant Professor and Consul- tant Pediatric Orthopedic Surgeon, Department of Orthopedics, King Khalid University Hospital, Riyadh, Saudi Arabia. Dr. Kiefer is Clinical As- sociate Professor, University of Calgary, and Di- rector, Division of Pediatric Orthopedics, Alberta Children’s Hospital, Calgary, Alberta, Canada. None of the following authors or the departments with which they are affiliated has r eceived anything of value from or owns stock in a commercial com- pany or institution related directly or indirectly to the subject of this article: Dr. Khoshhal and Dr. Kiefer. Reprint requests: Dr. Khoshhal, King Khalid Uni- versity Hospital, PO Box 7805, Riyadh 11472, Saudi Arabia. Copyright 2005 by the American Academy of Orthopaedic Surgeons. Growth arrest secondary to physeal bridge formation is an uncommon but well- recognized complication of physeal fractures and other injuries. Regardless of the underlying etiology, physeal bridges may cause angular and/or longitudinal growth disturbances, with progression dependent on the remaining physeal growth potential. Physeal bridge resection and insertion of interposition material releases the teth- ering effect of the bridge. Physeal bridge resection has become an accepted treatment option for patients with existing or developing deformity and for those with at least 2 years or 2 cm of growth remaining. Current experimental research is focused on the use of gene therapy and other factors that enhance chondrocyte proliferation to improve the management of growth arrest. The use of cartilage and cultured chondrocytes as interposition material after physeal bridge resection is an area of active research. J Am Acad Orthop Surg 2005;13:47-58 Vol 13, No 1, January/February 2005 47 the epiphyseal ossification center is small. Because many bridges do not manifest until the adolescent growth spurt, young patients should be followed until skeletal maturity to be sure that a bridge does not occur. 8,11,12 Johnson and Southwick 9 reported that gr owth can continue normally after physeal bridging when the lesion is small. In such instances, continued growth can disrupt an im- mature bony bridge, thereby permit- ting longitudinal growth to be rees- tablished. Also, some physeal bridges spontaneously lengthen with growth, similar to bone regeneration during distraction osteogenesis. However, this happens only when the bridge is small and well localized. Physeal bridges vary by location and patient age. A size threshold seems to exist that can be overcome by intrinsic physeal recovery capac- ity. Animal studies suggest that damage to <7% of the cross-sectional area of the physis does not usually cause a permanent physeal bridge. 13,14 Österman 15 induced physeal defects in rabbits and filled them with free fat graft. The defects became smaller with time, and the originally induced defects were almost totally corrected. Österman concluded that complete regeneration of the physis is not important to normal growth when physeal bridge formation can be pre- vented. The two separate parts of the same physis can grow normally and independently. 15 When a traumatic physeal bridge is identified early, treatment can be directed solely toward resolving the bridge rather than toward managing both the area of the bridge and the acquired growth deformity. Treatment is indicated only in patients with existing or developing deformities who have significant growth remaining. Treatment options include corrective osteotomy, comple- tion of the epiphysiodesis (with or without the contralateral extremity in the forearm or leg), and lengthening of the involved segment. Epiphysiod- esis and/or shortening of the oppo- site extremity may be indicated in some patients. Combinations of these procedures can be used with or without surgical excision of the physeal bridge. 16 The results of physeal distraction r emain controversial because premature complete epiphysiodesis frequently occurs after distraction of the physis. 17 Autogenous physeal transplantation has had limited suc- cess in the treatment of physeal bridges, as have allografts, which fail because of immune response. 11 Surgical resection of the physeal bridge and insertion of an interposition material was introduced by Langenskiöld 18 in the late 1960s with the objective of relieving the tether- ing effect. Longitudinal growth after resection of a distal tibial physeal bridge was first documented by Peterson, 19 who reported growth of 16.7 cm inthe tibia of a 5-year-old boy. Peterson 16 noted the growth in theop- erated bone to be an average of 94% (range, 0 to 200%) compared with the normal extremity. Williamson and Staheli 20 reported mean growth of 83% in 22 resections at 2 years. Al- though resection of physeal bridges is beneficial, it remains unpredictable. Excellent and good results in most se- ries range from 62% to 90%. 16,20-22 Poor r esults are fr equent, usually secondary to osteomyelitis or congeni- tal deformities (eg, Madelung’s deformity). 23 Etiology Physeal bridging occurs when there is contact between the epiphysis and the metaphysis, resulting in osseous consolidation in that region. Contact may occur when part of the physis is completely destroyed or when a fracture becomes displaced. Contact also can occur when the physis is dis- rupted, resulting in a liquid mixture of blood and crushed tissue lying in continuity between the epiphysis and the metaphysis. 24 Physeal bridges commonly occur after trauma 25 (Fig. 2). Although physeal injuries repre- sent 15% to 30% of all fractures, only 1% to 10% of those injuries result in physeal bridges. 26,27 All five Salter -Harris types of physeal fracture, as well as Rang’s sixth type (ie, injury to the perichondrial ring),havebeenr eportedtocausephys- eal bridges. In these groups, growth arrest occurs more frequently than was originally suggested by the Salter- Harris classification scheme. 3,11 Low- er extremity bars occur more frequently than do upper extremity bars because the injuries often are more violent. High-energy injuries, especially with physeal comminution, usually are associated with physeal bridg- Figure 1 Anteroposterior radiograph demonstrating a central physeal bridge in the proximal phalanx of the middle finger of the left hand that caused tenting of the physis, deformity of the articular surface, and shortening of the phalanx. Physeal Bridge Resection 48 Journal of the American Academy of Orthopaedic Surgeons es regardless of the type of fractur e. 11,24 Most Salter-Harris type I fractures have an excellent prognosis. A physeal bridge may occur if the fracture is severely displaced and if reduction is difficult.Approximately 75% of all physeal fractures are type II fractures. Although the prognosis typically is good, growth disturbances occur in 10% to 30% of patients, depending on the location of the fracture. Growth disturbances are especially frequent in distal femoral fractur es. In their re- view of 151 injuries of the distal femoral physis, Eid and Hafez 28 reported an even higher complication rate (46.2% shortening, 63% angular deformity) in type II fractures compared with type IV (40.9% shortening, 63.6% angular deformity). The outcome of type III fractures depends on the vas- cularity of the physis and the involvement of the germinal layer.Fortunate- ly, such fractures usually occur near the end of growth, when bridge formation does not cause significant deformity. 26 Because Salter-Harris type IV physeal fractures cross the metaphysis, epiphysis, and physis, a displaced, unreduced type IV physeal fracture has the greatest potential to form a physeal bridge. A bridge may form even with anatomic reduction. 16 In type V Salter-Harris injuries, no fracture is evident radiographically, but these injuries can cause growth abnormalities. Thus, the diagnosis often is made in retrospect from clinical and radiographic evidence, usually after deformity has occurred. The existence of this type of physeal injury has been questioned. 25-27 Type VI physeal injuries usually ar e the r esult of direct trauma or ligamentous avul- sion. Peripheral physeal bridging may occur in these cases. In fractures involving physeal comminution, or in a fracture exiting at the groove of Ran- vier,placement of prophylactic fat graft in the physeal defect may be considered. This may prevent future physeal bridge formation. 11,29 Foster et al 29 hypothesized that the free fat pr events bridge formation. The graft is pushed aside, thus allowing the physis to re- gain some or all of the original width by regeneration from the inner part toward the periphery during continued growth. Partial regeneration of the physis also has been noted. 15 Physeal fractures of the distal femur, proximal tibia, and distal tibia have the greatest propensity for complications. Barmada et al 30 reported that physeal bridge formation occurs in 32% of distal tibia physeal fractures. The highest percentage (38%) was after type III and IV Salter-Harris fractures. The incidence increased to 60% when a residual gap was evident on postreduction radiographs. In proximal tibia physeal fractures, the risk of growth abnormality varies with the type of injury. The risk after injury is 50% in patients with Salter-Harris type I fractures, 25% after type II, 6% after type III, and 55% after type IV. Patients with Salter-Harris type III fractures have a lower risk of growth abnormalities because these fractures usually occur near skeletal maturity. 31-33 The incidence of physeal bridge formation is higher after injuries to the distal femoral and proximal tibial physes than to other physes, regardless of the type of injury. Al- though <3% of all physeal injuries occur at the distal end of the femur and the proximal end of the tibia, >50% of all physeal bridge resections Figure 2 Physeal bridge of the distal tibial physis in a 5-year-old girl after an abduction injury. A, Mortise view demonstrating fracture of the medial malleolus extending to the physis. B, Anteroposterior radiograph of the ankle 15 months after injury, demonstrating a medial physeal bridge. C, Mortise view 4 years postexcision. Interposition material can be seen medially. D, Mortise view 8 years postexcision demonstrating good general alignment. Khalid I. Khoshhal, FRCS Edin, ABOS, and Gerhard N. Kiefer, MD, FRCSC Vol 13, No 1, January/February 2005 49 occur at these locations. 11,26,34 The distal femoral and proximal tibial physes contribute to the greatest propor- tion of limb growth and are more susceptible to bridge formation because they are more frequently sub- jected to relatively violent injury mechanisms. As a result, physeal bridges in these areas are most likely to produce noticeable angular deformity and marked limb-length discrepancy. Each of these physes has a large surface area with marked un- dulations that increase physeal stability and protect the physes from shearing injuries. Conversely, with high-energy trauma, the same undu- lations predispose the physis to damage. The metaphyseal surfaces are sheared against the physeal surface, producing direct injury to the undu- lations, with subsequent increased likelihood of physeal bridge formation. In contrast, physeal fractures of the distal radius andulna have a more benign outcome. Cannata et al 35 reported on the long-term prognosis (average follow-up, 25.5 years) of 157 patients with physeal fractures at the distal radius and ulna. Only 10 patients were symptomatic; none of those with either radioulnar length discrepancy <1 cm or with styloid nonunion reported symptoms. Other insults that can cause physeal bridge formation are infection (osteomyelitis, systemic infection [eg, meningococcemia]), tumors, irra- diation, thermal and electrical burns (eg, laser beam damage, 27 lightning strike 36 ), vascular insufficiency, met- abolic disorders (eg, vitaminAintox- ication 16 ), disuse, 27 and hematologic abnormalities. Iatrogenic injury, such as insertion of metal or drilling across the physis as well as subperiosteal dissection extending to the perichondrial ring, also can cause physeal bridges. 34 Physeal bridge formation secondary to iatrogenic placement of metal pins andscrews across the physis depends on factors such as pin location, size, obliquity to the physis, duration of use, and, most important, whether the pin is smooth or thread- ed. A smooth pin of small diameter placed perpendicularly across the center of a large physis for 2 to 3 weeks rarely results in physeal bridge formation. However, a large, thread- ed pin placed obliquely across a physis and left in place for a few weeks has a greater risk of forming a physeal bridge. 16 The presence of a traction pin acr oss or even close to a physis sometimes is associated with subsequent physeal bridging, especially in the proximal tibia. 27 Congen- ital or developmental physeal bridges can occur with Blount’s disease, Madelung’s deformity (Fig. 3), or longitudinal bracketed epiphysis (ie, delta phalanx), or from no obvious cause. Repeated minor trauma may play a role in physeal bridge resection. 16,24,37 A benign tumor in the vi- cinity of the physis may result in physeal disruption and bridging that can be demonstrated on magnetic resonance imaging (MRI) scans; ex- amples include a bone cyst, en- chondroma, aneurysmal bone cyst, chondroblastoma, chondromyxoid fibroma, fibrous dysplasia, or osteo- chondroma. 5,27 In some cases, particularly when the abnormality is caused by injury to the blood supply, the physis remains open but is thin and irregular. The rate of longitudinal growth slows because ofimpair ed cell formation. In such cases, the physis may close prematurely, although there may be a delay of several years between the insult andpr emature closure. 17 Once formed, physeal bridges can increase in size as the child grows, resulting in a greater propensity for a growth problem. 13 Classification Peterson 16 has classified physealbridg- es into thr ee descriptive types: peripheral, elongated, and central (Fig. 4). Peterson’s classification describes not only the pattern of injury but also indicates the ease of surgical repair. Pe- ripheral bridges causeconsiderable angular deformity and are relatively easy to correct surgically. However, satis- factory long-term outcome is unlike- ly with large bridges because there is insufficient surrounding physis to re- establish growth. Elongated physeal bridges are linear or longitudinal and involve the middle of the physis from one edge to the other, with healthy physis on either side. Elongated bridges are unusual and most commonly occur as a consequence of Salter-Harris type III or IV fractures (ie, malunion of a medial malleolus fracture). 25 Cen- tral bridges have a perimeter of healthy physis. The bridge acts as a central tether, resulting in tenting of the p hysis with eventual distortion of the articular surface (Fig. 1). Histopathology The mechanism of injury is likely a combination of cellular disruption and ischemia. Destruction of the epiphyseal vascular supply leads to the development of a central physeal bridge that may be followed by par- Figure 3 Anteroposterior radiograph of the right wrist showing a physeal bridge in the medial part of the distal radial physis in a 9-year-old girl with Madelung’s deformity. Physeal Bridge Resection 50 Journal of the American Academy of Orthopaedic Surgeons tial or complete epiphysiodesis. In contrast, destruction of the metaphyseal vascular supply may tempo- rarily interfere with ossification but usually does not result in physeal bridge formation. 38 The initial chang- es that occur in a segment of disrupt- ed physis involve the formation of fibrous tissue, which may vascularize. The cartilage along these transphys- eal vessels undergoes calcification, a necessary prelude to the eventual chondro-osseous transformation that leads to early bony physeal bridging. 11 The bridge usually is composed of very dense, sclerotic bone. At surgery, the abnormal physeal tissue has a grayish, translucent appearance, whereas the normal physis is usually opaque white with a blue tinge. 25 A fracture is likely to limit physeal damage to the actual cleavage plane, but more diffuse damage may occur when the fracture transects a significant intraepiphyseal vessel. The extent of microscopic physeal damage after infection is much greater than what is visible on radiographs. This explains the limited recovery potential after resection of theobviousbony physeal bridge. 11 Radiologic Evaluation Standard radiography usually con- firms the site and extent of the bony bridge in patients with obvious deformity. Asymmetry of growth recovery lines (ie, Harris lines) may be the earliest sign of physeal bridge formation. 31 A sclerotic bridge of bone or blurring and narrowing of the physis is often seen on plain radiographs when the x-ray beam is tangential to the physis. Problems of interpretation arise when part of the physis is oriented obliquely to the x-ray beam. An elongated physeal bridge extending from anterior to posterior has a radiologic appearance similar to that of a central bridge in the anteroposterior projection. The distinguishing feature is the absence of tenting of the physis resulting from peripheral growth seen in central bridges (Fig. 4). The presence of growth recovery lines is useful. These lines form at the location of the physis at the time of injury, presumably as a result of tem- porary slowing or cessation of growth secondary to trauma or illness. The distance between the physis and the growth recovery lines indicates the amount of growth that has taken place since the injury. When growth is normal, the growth recovery lines are parallel to the physis. When growth is arrested peripherally, the lines tend to converge toward the ar ea of abnormal physis. With slowing of growth rather than complete arrest, the line is oriented obliquely but is not converging. 2 In a total physeal arrest, there is no growth recovery line. Harris lines can be seen best on MRI scans, often 6 to 7 weeks earlier than their appearance on normal radiographs 13 (Fig. 5). Skeletal age estima- tion is essential, especially in the older child, because future growth potential dictates the therapeutic alternatives. The length of both the involved and uninvolved extremity should be documented radiographically. 16 Computed Tomography Scans Axial computed tomography (CT) scans are sometimes difficult to inter- pret because of the normal undula- tions of the physis (Fig. 6). However, multiplanar reconstructions in the coronal or sagittal plane may show the physeal bridge. CT may provide additional information on the config- uration of a central bridge with tenting. The cr oss-sectional area of the teth- ering physeal bridge can be obtained from the most superior CT slice through the abnormal region. This view can easily define the extent of the physeal bridge and enable mea- surement of the area of affected physis. 10 Helical CT has improved imaging quality; also, positioning of the leg and physis in the gantry is not as crit- Figure 4 Anteroposterior (top) and cross section (bottom) views of the Peterson classification of physeal bridges (shaded areas). A, Peripheral bridge. B, Elongated bridge. C, Central bridge. Note the tenting of the physis (top) caused by peripheral growth. Khalid I. Khoshhal, FRCS Edin, ABOS, and Gerhard N. Kiefer, MD, FRCSC Vol 13, No 1, January/February 2005 51 ical as with conventional CT. Because the scanning time is reduced to approximately 20 seconds, it often can be done without sedation and with lower radiation exposur e. 39 Helical CT imaging is accurate for mapping because the physeal cartilage is easily differentiated from the adjacent bone on the reformatted images 39 (Fig. 7). Scintigraphy Single-photon emission computed tomography can map the distribution of osteoblastic activity in the physis. 40 One limitation of this technique is that, in the absence of an atlas of normal tomoscintigraphic slices of different physes, only one-sided involvement can be established with certainty. The lesion should be >1 cm to be detectable. Single-photon emission computed tomography is the only radiographic method that can distinguish between generalized slowdowns of growth (eg, injuries to the blood supply without actual bridge formation) and complete epiphysiodesis. 40 Magnetic Resonance Imaging MRI, which provides images of excellent quality without radiation, is the imaging method of choice for evaluation of physeal bridges. 13,27,41-44 MRI scans help to map the bridge (the physical dimension and distance fr om known landmarks) while demonstrating the injured and uninjured areas of the gr owth cartilage (Fig. 5).At least two sequences are necessary for comparison to differentiate cartilage, cortical bone, and bone marrow: fat- suppressed three-dimensional spoiled gradient echo imaging and a three- dimensional T1-weighted gradient with water excitation. Fat-suppressed three-dimensional spoiled gradient echo–weighted images clearly dem- onstrate the bridge and the associated abnormalities that might follow the physeal injury. It is now thought to be the best sequence for physeal bridge imaging. 43 The images ar e made in two planes perpendicular to the physis to localize the exact size, shape, and location of the physeal bridge and the status of the remaining physeal area. 44 Definition of physeal bridges across the physis can be obtained using thr ee- dimensional projection with software for MRI angiography. 12 The area of involvement is best measured using a three-dimensional T1-weighted gradient with water excitation. The result is a true anatomic image based on volume data, depicting only the physis and the physeal bridge. 27 Figure 5 Posttraumatic physeal bridge in a 10-year -old girl. A, Sagittal gradient echo–weighted image of the distal femoral physis demonstrating the posttraumatic physeal bridge. There was involvement of the middle and posterior thirds of the physis 9 months after the girl suffered a Salter-Harris type II fracture. B, Coronal short tau inversion recovery image demonstrating physeal bridge involvement in the middle third of the posterior physis. In both images, a Harris line is visible distal and parallel to the proximal tibial physis. Figure 6 Axial computed tomography scan of the right distal femoral physis demonstrating a posttraumatic posterior physeal bridge in a 13-year-old boy. Figure 7 Coronal helical CT scan demonstrating a clear central physeal bridge of the distal physis. (Courtesy of J. A. Herring, MD, Dallas, TX.) Physeal Bridge Resection 52 Journal of the American Academy of Orthopaedic Surgeons Physeal widening on gradient echo– weighted and T2-weighted images im- plies physeal dysfunction without bridge formation. 42 The disadvantage of MRI is the considerable amount of time r equired for the child to lie still in the scanner. Younger children often require sedation or general anesthesia. Hasler and Foster 23 recommend preoperative MRI to map the bridge; early postoperative MRI to detect incomplete resection; and MRI 6 months after surgery to detect bridge recurrence, migration, and necrosis of the interposition material (if fat graft is used) and to evaluate the remnant physis and its repair potential. Mapping the Bridge Before physeal bridge resection is considered, it is critical to carefully and precisely delineate the physeal bridge in three dimensions toplan the best approach. The physical dimensions of the physeal bridge should be defined schematically with precise dimensions of easilyidentified anatomic borders. Most MRI and CTsoftwar e can now do the mapping (Fig. 8). Patient Selection The mere presence of a premature partial physeal bridge is not an indication for surgery. Patients with documented existing or developing deformities ar e candidates for resection. At least 2 years or 2 cm of growth should remain, and the physeal bridge should be ≤50% of the physeal area. The younger the patient, the greater the benefit of a successful resection. In very young children, re- secting physeal bridges of >50% of the physeal area could be considered because the alternatives (eg, repeated corrective osteotomies) are unde- sirable. Additionally, if the procedure is unsuccessful, other treatment options remain. 27 The smaller the bridge, the better the likely outcome because less resection is needed. Excellent results have been reported for bridges of <25%. 20 Also, the shorter the time interval between the insult and surgery, the better the likely outcome. In such cases, the deformity is smaller and the bridge is easier to treat. The deformity might even correct spontaneously. Central physeal bridges generally have a better long-term outcome than do peripheral bridges, although they are more difficult to remove. The surrounding physis should be healthy to resume growth after bridge resection. Determining the health of the growth plate is difficult and is especially important in physeal bridges secondary to infection, vascular insult, and crushing Salter-Harris type V injuries. Physes injured by infection or vascular insults often do not heal as suc- cessfully as do physeal bridges secondary to fracture. The patient should be free of drainage for at least 1 year if previously infected. 21 Surgical Technique The surgical approach varies depending on the type of bridge and its location. Generally, posterior peripheral physeal bridges are more difficult to approach in the lowerlimb because of the neurovascular structures and soft tissues encountered. Peripher- al and elongated bridges are approached directly after localization with an image intensifier (Fig. 9). First, the overlying periosteum is excised from the junction of the bridge with the intact perichondrial ring and across the extent of the bridge. It is important to excise, not suture, the periosteum to prevent bridge reformation when the surgical approach necessitates periosteal violation. The bridge usually is hard sclerotic bone that should be removed with a high- speed burr until healthy physis is seen surrounding the resection cavity. After complete removal of the bridge, 2 to 3 mm more bone is removed along the metaphyseal and epiphyseal margins of the physis. This ensures good contact between the physis and the interposition material, while avoiding contact between the epiphysis and the metaphysis. Constant irrigation should be used to prevent heat injury to the remaining physis and to remove all osseous debris. Periodic imaging is helpful to accurately delineate the bridge and Figure 8 Physeal bridge of the distant tibial physis in a 5-year-old child 1 year after a Salter- Harris type IV fractur e. A, Coronal CT scan of the ankle showing the peripheral physeal bridge (arrow). B, Axial CT scan showing the anteromedial physeal bridge (arrow). Khalid I. Khoshhal, FRCS Edin, ABOS, and Gerhard N. Kiefer, MD, FRCSC Vol 13, No 1, January/February 2005 53 to define the depth and extent of the cavity. Loupe magnification and a co- axial light source will facilitate visu- alization of the physis. Care must be taken not to elevate the periosteum when defining thelimits of the bridge unless elevation is needed for the approach, because damage to the perichondrial ring can cause a new physeal bridge. When an osteotomy is needed to correct the angular deformity, physeal bridge resection can be done simultaneously using the cut surface of the osteotomy to approach the bridge. Central physeal bridges can be approached either through a metaphyseal window or, more directly, through access created by a metaphyseal osteotomy adjacent to the bridge. With either approach, a curette should be used tor emove cancellous bone down to the area of the bridge. This bone should be saved and used at the end of the procedure to fill the surgical defect. Once the bridge is located, a high-speed burr can be used to completely remove the physeal bridge from the inside out. Using a small dental mirror, the normal physis must be visualized thor- oughly thr oughout the circumference of the resection cavity. The following may aid evaluation: the physeal bridge usually is composed of dense bone similar to cortical bone; the surrounding bone is more cancellous; the physeal cartilage is usually straight- er and wider, often with a blue tinge; and the epiphyseal bone feels spongy and, when pressed on, feelsas though it were floating. 24 Approaching central bridges through a metaphyseal window may be difficult even with adequate suc- tion, illumination, magnification, dental mirrors, and cutting instru- ments. In some cases, Jackson’s modification of cutting a predrilled and tapped wedge of metaphysis as a window is helpful 45 (Fig. 10). With help from the image intensifier, the horizontal cut is made parallel to the physis and 5 t o 1 0 m m f r om it. Screw- ing the bone wedge back on top of the fat graft fixes the graft and pre- vents the hematoma from displacing it, thus reducing the risk of recurrence.Thescrewactsasausefulmark- er for follow up. Stricker 46 used an arthroscope to better visualize the excision of central physeal bridges through small metaphyseal windows. Insertion of metallic markers on either side of the physis after resection of the physeal bridge is essential for measuring subsequent growth. The markers alsocan be used to differentiate growth of the affected physis from overgrowth of the physis at t he other end of thesame bone. The markers are best inserted in the cancellous bone parallel to the physis in the plane of deformity (eg, in the sagittal plane in sagittal plane deformity) and in the ossified center of the epiphysis to avoid extrusion with growth and metaphyseal re- modeling 23,27 (Fig. 11). The markers should not be in contact with the cavity. Transverse small Kirschner wires cut flush with the bone, small vascular clips, and small bone anchors without sutures all have been used. Titanium Kirschner wires are prefer- able because they do not interfere with future MRI evaluation. 23 It is very instructive to draw a postoperative “map” immediately after the surgical treatment based on the surgical findings. The map is useful for future refer ence should bridge formation recur and for comparison with the preoperative map. 47 Interposition Material Animal studies have shown that bridge reformation occurs consistent- ly when interposition material is not used. 20,48 Fat, polymethylmethacry- late (PMMA), bone wax, cartilage, muscle, and silicone have all been used as interposition materials. Fat and PMMA are the two most commonly used materials. Because cartilage is the damaged tissue, it is the ideal interposition material. 49 Autog- enous chondrocytes, which are cultured in vitro and transplanted into the defect created by the resection of the physeal bridge, appear to be promising in animal models. 50,51 Ev- idence suggests that the defects are filled with cartilage; histologic examination showed the chondrocytes lin- ing up in a columnar arrangement, as in anormal physis. 50 Based on their rabbit study, Tobita et al 51 reported that autogenous chondrocyte trans- Figure 9 Cross-section (top) and anteroposterior (bottom) views of a peripheral physeal bridge. A, The shaded area inthe cross-section diagram represents mapping of a peripheral physeal bridge. B, The bridge is excised via a direct approach. Figure 10 Jackson’s modification of the metaphyseal window approach. Physeal Bridge Resection 54 Journal of the American Academy of Orthopaedic Surgeons plantation is better than fat graft for cases in which the damaged area is larger than two thirds of the physis. Cultured chondrocytes or other bio- logic tissue (eg, cartilage) may be useful in the near future. 48 Lee et al 52 investigated the feasi- bility of using gene therapy and tissue engineering to treat tibial physeal defects in rabbits. Their studies were based on autologous muscle- and adenoviral-mediated gene transfer of insulin-like growth factor-1 (IGF-1) and bone morphogenetic protein-2 (BMP-2). IGF-1 appeared to have a supportive effect on physeal chondrocytes; BMP-2 caused increased osteogenic activity in the injured physis. 52 Johnstone et al 53 reported that osteogenic protein-1 had a localized effect of promoting outgrowth of the adjacent physeal cartilage. Regardless of the type of interposition material used, the material should remain at the original site of the physeal bridge and the adjacent metaphysis-epiphysis. The likelihood of physeal bridge reformation occur- ring acr oss the physis increases when the epiphysis grows away from the interposition material (Fig. 12). Fat has the advantage of being autogenous and can potentially enlarge in size with the patient. Langenskiöld 18 used buttock fat because of its firmer and globular consistency. The disadvantage of using fat is that it is associated with poor hemostasis in the cavity. It tends to float out of the cavity when the tourniquet is released. Clo- sure of the periosteum over the cavity to contain the fat predisposes to peripheral bridging. Fat grafts do not provide structural support to the weakened bone, which predisposes the bone to fracture, thereby requir- ing postoperative immobilization. Tachdjian 54 recommends suturing the fat graft through drill holes made in the epiphysis and metaphysis surrounding the cavity; doing so may avoid fat migration caused by bleeding from the raw bony surfaces. To decrease bleeding and hematoma for - mation, bone wax can be used on osseous surfaces. Shrinking of the graft may induce recurr ence of the physeal bridge, 23 and partial necrosis of fat grafts has been reported. PMMA without barium is an in- ert material with minimalthermogen- ic properties. Its radiolucency allows assessment of bridge recurrence. It provides hemostasis because it occu- pies the entire portion of the cavity and is strong enough to provide some structural support, thereby permit- ting potentially less postoperativeim- mobilization. PMMA can be poured into a dependent cavity in a liquid state, or it may be allowed to set par- tially and then be pushed into the defect like putty so that it molds well to the cavity. 16 When PMMA is used as an interposition material, the epiphyseal walls should be undermined with a right-angled cur ette to ensure that the PMMA plug stays in the epiphysis and adjacent physis and does not dis- place toward the metaphysis. It also can be kept in the epiphysis by cre- ating drill holes (pods) in the epiphysis to anchor it. 16 A minimal amount of PMMA should be used in the metaphysis (Fig. 12). After the PMMA sets completely, the remaining metaphyseal cavity is packed with the cancellous bone har- vested during the exposure. Allograft bone can be usedas a supplement. Sil- icone, which has many properties similar to PMMA, has been used ex- perimentally in both humans and an- imals, but it is currently unavailable for use. Corrective Osteotomy With Bridge Resection Absolute indications for corrective osteotomy at the time of bridge resection have not been firmly established. Although spontaneous correction of up to 35° has been reported, the degree of correction is variable and in- consistent. 20 A current indication for Figure 11 Posttraumatic posterior physeal bridge of the distal femoral physis in a 13-year- old boy. A, Intraoperative lateral radiograph after excision of the bridge and insertion of fat graft. Note the orientation of the metal markers. B, Lateral radiograph of the distal femur of the same patient 4.5 years later demonstrating the spread and nearly parallel orientation of the metal markers. Khalid I. Khoshhal, FRCS Edin, ABOS, and Gerhard N. Kiefer, MD, FRCSC Vol 13, No 1, January/February 2005 55 osteotomy is correction of angular deformities >20° because theylikely will not correct spontaneously after bridge resection. 16,24,25,27 Williamson and Staheli 20 recommended corrective osteotomy at the time of bridge resection for all knee and ankle deformities >10°, especially when the area of growth arrest is >25% of the physis. Initial spontaneous improvement in angular deformity was noted in the first year after bridge resection and was attributed to surgical stimulation of the physis. Recurrence of the deformity by the time of skeletal maturity was attributed to early closure of the injured side of the physis. 20 The decision to perform an osteotomy at the time of bridge resection must be guided by the degree and location of the deformity as well as the area of the physeal bridge. A one-stage procedure can be done when corrective osteotomy can be performed without compromising either the physeal bridge resection or the level of the osteotomy. Postoperative Care Postoperative immobilization is not necessary after excision of small peripheral bridges when PMMA is used as an interposition material or when osteotomy is not performed. Patients should be advised that, although it is not routinely necessary, the PMMA plug may need to be removed. Re- moval can be difficult and may be destructive. There is a theoretical dan- ger of fracture if the PMMA is displaced by growth of the metaphysis and creates an area of stress concen- tration within the bone. 31 Removal could cause recurrence of the bridge if done before longitudinal growth is completed. 27 All patients should be followed to skeletal maturity with scanograms to accurately determine the outcome. Peterson 47 reported unexpect- ed growth in the nonoperated physis of the operated bone compared with the nonoperated contralateral bone. It isnot uncommon that growth slows or even ceases completely on the operated side before the contralateral side. This could be either secondary to reformation of the physeal bridge or because of premature closure of the physis. 21 Complications Early or late physeal bridge reformation may occur, especially with bridges ≥50%. Early bridge recurrence can be repeatedly resected if the indications for resection are met (2 cm of growth remaining and <50% of the area of the physis). When insufficient growth remains and the deformity is unacceptable, osteotomy is the procedure of choice. 34 There is a small risk of fractur e i f excessive bone is removed during resection. Infection is a risk, especially when the physeal bridge is secondary to osteomyelitis. Premature closure of the involved physis, which is reported frequently, may not be a complication but rather a normal physiologic response to physeal injury. 21 In a r eview of 98 patients followed to maturity, Peterson 27 reported that the average growth was 84% of that of the unoperated side. Thirteen percent of the patients did not need fur- ther surgery. Eighty-five patients (87%) required adjunctive surgery, usually for preexisting length discrepancy and angular deformity, which did not correct fully even with successful bridge resection. The recurrence rate was 18%, and the infection rate, 3%. Osteomyelitis was the cause of the bridge in all of the infected cases. Two patients (2%) had fractures postoperatively. 27 Summary Physeal bridge r esection can prevent, correct, or improve deformity and limb-length discrepancy by restoring growth potential. It also may help avoid r epetitive complex lengthening surgeries. 24,31 Surgery is not indicated in every patient with a physeal bridge unless a deformity is shown to be present or developing.The over- all results for this procedure indicate an efficacy of growth restoration in most patients, with correction of angular deformity up to 20°. Even with successful bridge resection, a patient might need surgery to correct residual limb-length discr epancy or angular deformity. Figure 12 Shape and position of the PMMAinterposition material. A, The PMMA is mainly in the epiphysis, leaving as little PMMA as possible in the metaphysis. B, With the growth of the epiphysis away from the physis, the physis grows inward over the PMMA, prevent- ing bridge reformation. The arrows indicate directions of growth. C, The PMMA is mostly in the metaphysis. When the physis grows away from the interposition material, the material becomes completely metaphyseal, which predisposes it to bridge reformation once the epiphysis comes into contact with the metaphysis. D, Bridge reformation with tenting of the physis and distortion of the articular surface. Physeal Bridge Resection 56 Journal of the American Academy of Orthopaedic Surgeons [...]... recommended once the physeal bridge is defined The best outcomes are associated with younger age at the time of surgery, shorter time interval from injury to resection, traumatic etiology, and smaller central bridges Physeal closure seems to occur prematurely despite physeal bridge resection Thus, continued follow-up examination to the end of the growth period is mandatory after physeal bridge resection... Foster BK, John B, Hasler C: Free fat interpositional graft in acute physeal injuries: The anticipatory Langenskiold procedure J Pediatr Orthop 2000;20:282-285 Barmada A, Gaynor MA, Mubarak SJ: Premature physeal closure following distal tibial physeal fractures: A new radiographic predictor J Pediatr Orthop 2003;23:733-739 Kasser J: Physeal bar resection after growth arrest about the knee Clin Orthop... distal tibial physeal fractures Foot Ankle Int 2000;21:54-58 Hasler CC, Foster BK: Secondary tethers after physeal bar resection: A common source of failure? Clin Orthop 2002; 405:242-249 Vickers DW: Premature incomplete fusion of the growth plate: Causes and treatment by resection (physolysis) in fifteen cases Aust N Z J Surg 1980;50:393-401 Ogden JA: The evaluation and treatment of partial physeal arrest... the tibia through the proximal tibial epiphyseal cartilage J Bone Joint Surg Am 1979;61:167-173 Burkhart SS, Peterson HA: Fracture of the proximal tibial epiphysis J Bone Joint Surg Am 1979;61:996-1002 Guille JT, Yamazaki A, Bowen JR: Physeal surgery: Indications and operative treatment Am J Orthop 1997;26:323-332 Cannata G, DeMaio F, Mancini F, Ippolito E: Physeal fractures of the distal radius and... Swinford AE, Kuhns LR: The use of helical computed tomographic scan to assess bony physeal bridges J Pediatr Orthop 1997;17:356-359 Wioland M, Bonnerot V: Diagnosis of partial and total physeal arrest by bone single-photon emission computed tomography J Nucl Med 1993;34:14101415 Gabel GT, Peterson HA, Berquist TH: Premature partial physeal arrest: Diagnosis by magnetic resonance imaging in two cases Clin Orthop... WM, Foster BK, Paterson DC, Morris LL: Statistical analysis of the incidence of physeal injuries J Pediatr Orthop 1987;7:518-523 Salter RB: Epiphyseal plate injuries, in Letts RM (ed): Management of Paediatric Fractures New York, NY: Churchill Livingstone, 1994, pp 11-26 Johnson JTH, Southwick WO: Growth following transepiphyseal bone graft: An experimental study to explain continued growth following... imaging of lower-extremity physeal fracture-separations: A preliminary report J Pediatr Orthop 1994; 14:526-533 Makela EA, Vainionpaa S, Vihtonen K, Mero M, Rokkanen P: The effect of trauma to the lower femoral epiphyseal plate: An experimental study in rabbits Vol 13, No 1, January/February 2005 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 57 Physeal Bridge Resection... 2001;39:823-841 43 Ecklund K, Jaramillo D: Patterns of premature physeal arrest: MR imaging of 111 children AJR Am J Roentgenol 2002; 178:967-972 44 Havránek P, Lízler J: Magnetic resonance imaging in the evaluation of partial growth arrest after physeal injuries in children J Bone Joint Surg Am 1991; 73:1234-1241 45 Jackson AM: Excision of the central physeal bar: A modification of Langenskiöld’s procedure J... evaluation and treatment of partial physeal arrest J Bone Joint Surg Am 1987;69:1297-1302 Peterson HA, Madhok R, Benson JT, Ilstrup DM, Melton LJ: Physeal fractures: I Epidemiology in Olmsted County, Minnesota, 1979-1988 J Pediatr Orthop 1994;14:423-430 Peterson HA: Physeal injuries and growth arrest, in Beaty JH, Kasser JR (eds): Rockwood and Wilkins’ Fractures in Children, ed 5 Philadelphia, PA: Lippincott... Imaging of References 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Salter RB: Injuries of the epiphyseal plate Instr Course Lect 1992;41:351-359 Ogden JA, Ganey T, Light TR, Southwick WO: The pathology of acute chondro-osseous injury in the child Yale J Biol Med 1993;66:219-233 Salter RB, Harris WR: Injuries involving the epiphyseal plate J Bone Joint Surg Am 1963;45:587-603 Moen CT, Pelker RR: Biomechanical and . arrest secondary to physeal bridge formation is an uncommon but well- recognized complication of physeal fractures and other injuries. Regardless of the underlying etiology, physeal bridges may. dependent on the remaining physeal growth potential. Physeal bridge resection and insertion of interposition material releases the teth- ering effect of the bridge. Physeal bridge resection has. the physeal bridge. 16 The results of physeal distraction r emain controversial because premature complete epiphysiodesis frequently occurs after distraction of the physis. 17 Autogenous physeal transplantation

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