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Premature Partial Closure and Other Deformities of the Growth Plate: MR Imaging and Three-dimensional Modeling

¹ Departments of Radiology (J.G.C., D.D.C., D.O.H., R.Y.C., M.T.v.H., W.R.E.)
² Orthopaedic Surgery (K.E.C.), Henry Ford Hospital, 2799 W Grand Blvd, Detroit, MI 48202.

	Abstract

TOP Abstract Introduction MATERIALS AND METHODS RESULTS DISCUSSION References

 
PURPOSE: To examine growth plates of the distal femur and tibia with magnetic resonance (MR) imaging to detect bone bridges and other deformities in children.

MATERIALS AND METHODS: Thirteen children (nine boys and four girls, aged 5–13 years; mean age, 9.8 years) were referred because of suspected or known bone bridging of the growth plate. Among the 13 patients, 10 had Salter-Harris fractures of the knee or ankle, two had Blount disease, and one had neonatal sepsis. Fat-saturated spoiled gradient-recalled images enabled reconstruction of a three-dimensional model of the growth plate. Patients underwent one to four MR examinations.

RESULTS: Nine patients had bone bridging of less than 1% to 39% of the area of the growth plate. On MR images obtained in the growth plate of five patients, a stripe of low signal intensity indicated fracture. On MR images obtained in three patients, intrusions of growth plate cartilage into the metaphysis were seen to increase in depth over time. MR images obtained in four patients showed no bridges. In the two patients who underwent surgery, excellent correspondence was found between MR findings and surgical observations.

CONCLUSION: Marked undulation or splitting of the growth plate may occur with fixation of some cartilage in the metaphysis or epiphysis while growth continues. The configuration of the growth plate and bone bridges can be accurately mapped with MR imaging. Treatment planning is facilitated.

Index terms: Bones, injuries 451.414, 454.414, 461.414 • Bones, growth and development 451.433, 454.433, 461.433 • Bones, MR, 451.121415, 451.121419, 454.121415, 454.121419, 461.121415, 461.121419 • Children, injuries 451.414, 454.414, 461.414 • Children, skeletal system 451.433, 454.433, 461.433

	Introduction

TOP Abstract Introduction MATERIALS AND METHODS RESULTS DISCUSSION References

 
Growth arrest followed physeal injury at the knee and ankle in 1.4% of the large series of patients studied by Mizuto et al (1). The occurrence of arrest following Salter-Harris fractures at the knee and ankle is related to many factors, including the type of physeal fracture, the age of the patient, the physis involved, and the amount of energy applied to the bone (2,3). The knee is the most common site of growth arrest (4,5), with the ankle second (4). The development of bone bridges at these sites results in interference with longitudinal growth (4,5).

Physeal fracture is the most common cause of bone bridging across the growth plate, but growth arrest may also be due to other insults, as reported by Ogden (5,6). Such insults include infection, therapeutic irradiation, metabolic or hematologic abnormality, tumor, burn, frostbite, electrical injury, sensory neuropathy, microvascular ischemia, or insertion of metal. Pease (7) reports premature fusion of the growth plate in patients with hypervitaminosis A. Caffey (8) describes cupping of metaphyses following trauma, osteomyelitis, poliomyelitis, vitamin A toxicity, sickle cell anemia, achondroplasia, or osteopetrosis.

If the growth plate is affected eccentrically, tethering will cause angular deformity. If the growth plate is affected centrally, growth at the periphery causes cupping of the metaphysis with shortening of the bone (5). The younger the child, the more severe the complications.

Plain radiography remains the initial imaging approach. Interpretation problems arise if part of the physis is not parallel to the x-ray beam. The presence of growth arrest lines is helpful; if a growth arrest line extends across the entire metaphysis and is parallel to the physis, physeal bridge formation is unlikely (9). As needed, results can be compared with the normal appearance of the growth plate (10,11).

If surgical excision of a physeal bridge is considered, accurate knowledge of its size and position is necessary. Conventional tomography with grid mapping (12), bone scintigraphy (13), and computed tomography with reformatting (14–16) have been used for this purpose. MR has been used to image the growth plate (3,17) and has now become the imaging method of choice (18).

We present our findings in children at high risk for bone bridging in whom we obtained one or more MR studies and 3D models of the growth plate to determine the need for intervention.

	MATERIALS AND METHODS

TOP Abstract Introduction MATERIALS AND METHODS RESULTS DISCUSSION References

 
Patients and Imaging
From late 1995 through late 1997, 13 children (nine boys and four girls, aged 5–13 years; mean age, 9.8 years) were referred because of developing leg length discrepancy, angular deformity, or both, or because findings at conventional radiography were equivocal for or suggestive of physeal bridge formation. Ten of the patients had recent Salter-Harris fractures, two had Blount disease, and one had neonatal sepsis.

In the 13 patients, 10 knees and three ankles were examined with one of two 1.5-T MR systems or a mobile 1.0-T system (GE Medical Systems, Milwaukee, Wis). Patients underwent one to four MR examinations, for a total of 26 examinations. The number of MR examinations and the time from injury varied among the patients (Table). In 22 of the 26 examinations, we added a three-dimensional (3D) fat-saturated spoiled gradient-recalled (SPGR) sequence to our routine knee or ankle MR series.

Two patients underwent surgical intervention with resection of the bone bridges. After the surgery, the ankle was imaged at 2 months and the knee at 4 months. Imaging was performed with the following sequences: sagittal T1-weighted spin-echo, fat-saturated fast T2-weighted, 3D fat-saturated SPGR, and fat-saturated gadolinium-enhanced (Magnevist; Berlex Laboratories, Wayne, NJ) T1-weighted (1.5-mm-thick sections).

Among the 26 examinations in which SPGR imaging was performed, 23 were in the sagittal plane; one, coronal; one, sagittal and coronal; and one, sagittal and axial. All SPGR sequences were fat saturated. The effective echo time was 5–13 msec with repetition time of 60 msec in all but two patients, in whom it was 57 and 40 msec. The flip angle was 40° in all but three patients, in whom it was 45°. The field of view was 12–16 cm. Sixty images were acquired in all but one patient (ankle), in whom there were 28. Section thickness was 1.0–2.0 mm, and matrix size was either 256 x 256 or 256 x 192.

Three-dimensional Modeling of the Epiphyseal Plate
Three-dimensional models were created by using a workstation (ADVANTAGE, version 2.0; GE Medical Systems). The growth plate was mapped on each sagittal or coronal image by manually highlighting the cartilage with the paintbrush utility (Fig 1b). As all but one study comprised 60 images, 45–50 of which contained the growth plate, this was the most time-consuming portion of the method. A trained operator could usually complete this step in less than 30 minutes. Identification of the growth plate on each sagittal or coronal image for each patient was reviewed and revised by a radiologist (J.G.C., M.T.v.H.).

View larger version (138K): [in this window] [in a new window]   Figure 1a. Patient 10. Images in a 12-year-old boy with a Salter-Harris 2 fracture through the proximal tibia treated with open reduction. (a) Sagittal SPGR (60/6 with 40° flip angle) image at 10 months after injury. The tibial growth plate shows a peripheral area of bone bridging (small arrows). The growth plate (large arrows) of the distal femur is normal. (b) Magnified view of a with "painting" of the tibial growth plate cartilage indicated in red. Arrows indicate bridges. (c) A 3D model of the tibial growth plate from the left anterolateral aspect. The bone bridge (o) lies just lateral to the tibial tuberosity (T). (d) Superoinferior projection of 3D model of the growth plate shows a peripheral bone bridge (large arrow) extending medially and an adjacent smaller bridge (small arrow). There is a very small bridge (arrowhead) posterolaterally. (e) Axial display of MIP image of the growth plate shows the same areas of bone bridging as seen in d. The bone bridges constitute 3.2% of the total area of the growth plate.

View larger version (108K): [in this window] [in a new window]   Figure 1b. Patient 10. Images in a 12-year-old boy with a Salter-Harris 2 fracture through the proximal tibia treated with open reduction. (a) Sagittal SPGR (60/6 with 40° flip angle) image at 10 months after injury. The tibial growth plate shows a peripheral area of bone bridging (small arrows). The growth plate (large arrows) of the distal femur is normal. (b) Magnified view of a with "painting" of the tibial growth plate cartilage indicated in red. Arrows indicate bridges. (c) A 3D model of the tibial growth plate from the left anterolateral aspect. The bone bridge (o) lies just lateral to the tibial tuberosity (T). (d) Superoinferior projection of 3D model of the growth plate shows a peripheral bone bridge (large arrow) extending medially and an adjacent smaller bridge (small arrow). There is a very small bridge (arrowhead) posterolaterally. (e) Axial display of MIP image of the growth plate shows the same areas of bone bridging as seen in d. The bone bridges constitute 3.2% of the total area of the growth plate.

View larger version (46K): [in this window] [in a new window]   Figure 1c. Patient 10. Images in a 12-year-old boy with a Salter-Harris 2 fracture through the proximal tibia treated with open reduction. (a) Sagittal SPGR (60/6 with 40° flip angle) image at 10 months after injury. The tibial growth plate shows a peripheral area of bone bridging (small arrows). The growth plate (large arrows) of the distal femur is normal. (b) Magnified view of a with "painting" of the tibial growth plate cartilage indicated in red. Arrows indicate bridges. (c) A 3D model of the tibial growth plate from the left anterolateral aspect. The bone bridge (o) lies just lateral to the tibial tuberosity (T). (d) Superoinferior projection of 3D model of the growth plate shows a peripheral bone bridge (large arrow) extending medially and an adjacent smaller bridge (small arrow). There is a very small bridge (arrowhead) posterolaterally. (e) Axial display of MIP image of the growth plate shows the same areas of bone bridging as seen in d. The bone bridges constitute 3.2% of the total area of the growth plate.

View larger version (113K): [in this window] [in a new window]   Figure 1d. Patient 10. Images in a 12-year-old boy with a Salter-Harris 2 fracture through the proximal tibia treated with open reduction. (a) Sagittal SPGR (60/6 with 40° flip angle) image at 10 months after injury. The tibial growth plate shows a peripheral area of bone bridging (small arrows). The growth plate (large arrows) of the distal femur is normal. (b) Magnified view of a with "painting" of the tibial growth plate cartilage indicated in red. Arrows indicate bridges. (c) A 3D model of the tibial growth plate from the left anterolateral aspect. The bone bridge (o) lies just lateral to the tibial tuberosity (T). (d) Superoinferior projection of 3D model of the growth plate shows a peripheral bone bridge (large arrow) extending medially and an adjacent smaller bridge (small arrow). There is a very small bridge (arrowhead) posterolaterally. (e) Axial display of MIP image of the growth plate shows the same areas of bone bridging as seen in d. The bone bridges constitute 3.2% of the total area of the growth plate.

View larger version (125K): [in this window] [in a new window]   Figure 1e. Patient 10. Images in a 12-year-old boy with a Salter-Harris 2 fracture through the proximal tibia treated with open reduction. (a) Sagittal SPGR (60/6 with 40° flip angle) image at 10 months after injury. The tibial growth plate shows a peripheral area of bone bridging (small arrows). The growth plate (large arrows) of the distal femur is normal. (b) Magnified view of a with "painting" of the tibial growth plate cartilage indicated in red. Arrows indicate bridges. (c) A 3D model of the tibial growth plate from the left anterolateral aspect. The bone bridge (o) lies just lateral to the tibial tuberosity (T). (d) Superoinferior projection of 3D model of the growth plate shows a peripheral bone bridge (large arrow) extending medially and an adjacent smaller bridge (small arrow). There is a very small bridge (arrowhead) posterolaterally. (e) Axial display of MIP image of the growth plate shows the same areas of bone bridging as seen in d. The bone bridges constitute 3.2% of the total area of the growth plate.

This technique yields a reasonable approximation of the area of the bridging bone. The growth plate and, thus, the bone bridges have a very undulating shape in three dimensions, and the MIP view essentially collapses the 3D data onto a two-dimensional plane. Thus, the areas that were measured with this method, while related to the true volume, do not incorporate the true 3D configuration of the anatomy and should be considered a surrogate for the true volume of growth plate tissue. Whereas it is possible to compute the true volume of the growth plate, the volume of the bone bridge tissue is represented by a complete lack of data in the model. It is not currently feasible to compute the volume of a hole in the growth plate model; therefore, the bridge was outlined and the area computed. The orientation of the 3D model may also have affected the MIP view by diminishing the bone bridges that were not perpendicular to the MIP plane while more accurately portraying those that were.

	RESULTS

TOP Abstract Introduction MATERIALS AND METHODS RESULTS DISCUSSION References

 
The results are summarized in the Table.
Two patients who sustained Salter-Harris 2 fractures, one of the knee and one of the ankle, showed no evidence of bridging 7 months after injury. The two patients with Blount disease had no evidence of bridging. The other nine patients were found to have bridging of less than 1% to 39% of the growth plate. When the bridge extended to the periphery of the growth plate, it was categorized as peripheral (in three patients); otherwise, it was designated as central (in four patients). Bridging in the remaining two patients was both central and peripheral. In five of the patients with central bridging and in one of the patients with peripheral bridging, the major area of bridging was surrounded by smaller bone bridges. Representative bone bridging patterns are illustrated in Figures 1 (peripheral bridging) and 2–4 (central bridging). In five patients, SPGR images demonstrated a band of low signal intensity, consistent with fracture, crossing within the normally high-signal-intensity growth plate. The low-signal-intensity band crossed most or all of the growth plate in two patients (Fig 5) but only a short segment in three (Fig 6).

View larger version (125K): [in this window] [in a new window]   Figure 2a. Patient 1. Representative pattern of central bone bridging. (a) Sagittal SPGR (60/5 with 40° flip angle) image of the left knee demonstrates two areas of bone bridging (arrows). (b) Superoinferior view of the 3D model of the growth plate shows a large central bridge with scattered smaller bridges (area between arrows). The bone bridges constitute 11.5% of the area of the lateral condylar growth plate.

View larger version (112K): [in this window] [in a new window]   Figure 2b. Patient 1. Representative pattern of central bone bridging. (a) Sagittal SPGR (60/5 with 40° flip angle) image of the left knee demonstrates two areas of bone bridging (arrows). (b) Superoinferior view of the 3D model of the growth plate shows a large central bridge with scattered smaller bridges (area between arrows). The bone bridges constitute 11.5% of the area of the lateral condylar growth plate.

View larger version (112K): [in this window] [in a new window]   Figure 4a. Patient 11. Representative pattern of central bone bridging. (a) Sagittal SPGR (60/6 with 40° flip angle) image through the area of tenting of the growth plate shows a large zone of growth plate (long arrows) tethered in the metaphysis. Anteriorly, the growth plate (short arrow) is irregular. (b) Inferosuperior projection of 3D model of the growth plate shows large and small central bridges to the lateral condyle following neonatal sepsis. The arrows indicate three of the smaller bridges.

View larger version (112K): [in this window] [in a new window]   Figure 4b. Patient 11. Representative pattern of central bone bridging. (a) Sagittal SPGR (60/6 with 40° flip angle) image through the area of tenting of the growth plate shows a large zone of growth plate (long arrows) tethered in the metaphysis. Anteriorly, the growth plate (short arrow) is irregular. (b) Inferosuperior projection of 3D model of the growth plate shows large and small central bridges to the lateral condyle following neonatal sepsis. The arrows indicate three of the smaller bridges.

View larger version (129K): [in this window] [in a new window]   Figure 5. Patient 4. Image in an 11-year-old boy with a Salter-Harris 4 fracture through the distal tibia. Sagittal SPGR (60/5 with 40° flip angle) image obtained 1 month after injury, through the medial aspect of the ankle, shows posterior displacement of the epiphysis (e). The anterior growth plate demonstrates a stripe of low signal intensity (arrow) that makes a cleft in the thick growth plate. This stripe is consistent with fracture of the growth plate.

View larger version (137K): [in this window] [in a new window]   Figure 6a. Patient 7. Images in a 10-year-old boy with a Salter-Harris 1 fracture of the proximal tibia treated with closed reduction. Minimal bridging developed. (a) Anteroposterior radiograph of the right knee at presentation. The fracture of the proximal tibia results in widening of the growth plate (short arrows). There is an associated fracture of the proximal fibula (long arrow). (b) Sagittal SPGR (60/8 with 40° flip angle) image obtained 5 months after injury shows thinning of the middle third of the growth plate (arrows) and an additional thick laminated band of cartilage, apparently derived from the growth plate. Within this thick band, there is a narrow stripe of low signal intensity (arrowhead). (c) Sagittal SPGR (60/9 with 40° flip angle) image obtained 11 months after injury shows longitudinal growth of the tibial metaphysis between the growth plate and the fixed band of cartilage (arrow). The middle third of the growth plate remains thin and shows a narrow stripe of low signal intensity (arrowhead).

View larger version (136K): [in this window] [in a new window]   Figure 6b. Patient 7. Images in a 10-year-old boy with a Salter-Harris 1 fracture of the proximal tibia treated with closed reduction. Minimal bridging developed. (a) Anteroposterior radiograph of the right knee at presentation. The fracture of the proximal tibia results in widening of the growth plate (short arrows). There is an associated fracture of the proximal fibula (long arrow). (b) Sagittal SPGR (60/8 with 40° flip angle) image obtained 5 months after injury shows thinning of the middle third of the growth plate (arrows) and an additional thick laminated band of cartilage, apparently derived from the growth plate. Within this thick band, there is a narrow stripe of low signal intensity (arrowhead). (c) Sagittal SPGR (60/9 with 40° flip angle) image obtained 11 months after injury shows longitudinal growth of the tibial metaphysis between the growth plate and the fixed band of cartilage (arrow). The middle third of the growth plate remains thin and shows a narrow stripe of low signal intensity (arrowhead).

View larger version (106K): [in this window] [in a new window]   Figure 6c. Patient 7. Images in a 10-year-old boy with a Salter-Harris 1 fracture of the proximal tibia treated with closed reduction. Minimal bridging developed. (a) Anteroposterior radiograph of the right knee at presentation. The fracture of the proximal tibia results in widening of the growth plate (short arrows). There is an associated fracture of the proximal fibula (long arrow). (b) Sagittal SPGR (60/8 with 40° flip angle) image obtained 5 months after injury shows thinning of the middle third of the growth plate (arrows) and an additional thick laminated band of cartilage, apparently derived from the growth plate. Within this thick band, there is a narrow stripe of low signal intensity (arrowhead). (c) Sagittal SPGR (60/9 with 40° flip angle) image obtained 11 months after injury shows longitudinal growth of the tibial metaphysis between the growth plate and the fixed band of cartilage (arrow). The middle third of the growth plate remains thin and shows a narrow stripe of low signal intensity (arrowhead).

View larger version (126K): [in this window] [in a new window]   Figure 7a. Patient 8. Images in a 12-year-old boy with an open Salter-Harris 2 fracture of the proximal tibia treated with open reduction and pinning. (a) Anteroposterior radiograph of the left knee at presentation shows a fracture through the growth plate (straight arrow) with medial displacement of the metaphysis (curved arrow). There is a fracture of the fibula (arrowhead). (b) Sagittal SPGR (60/6 with 40° flip angle) image of the lateral portion of the knee at 3 months after injury shows no bridge or fracture. There are small intrusions of growth plate cartilage (arrows) into the tibial metaphysis. (c) Sagittal SPGR (60/6 with 45° flip angle) image (same level as b) at 14 months after injury shows progressive growth plate deformity with deeper intrusions (arrows) as the metaphysis has grown. (d) Sagittal SPGR (60/6 with 40° flip angle) image through the midline at 3 months after injury shows a block of cartilage (arrow) displaced into the epiphysis. There are small intrusions (arrowheads) anteriorly. (e) Sagittal SPGR (60/6 with 45° flip angle) image (same level as d) at 11 months after injury shows a deeper intrusion (arrowhead) into the growth plate anteriorly and a large area of widened and depressed growth plate (arrow) posteriorly. The block of cartilage in the epiphysis has been largely resorbed.

View larger version (124K): [in this window] [in a new window]   Figure 7b. Patient 8. Images in a 12-year-old boy with an open Salter-Harris 2 fracture of the proximal tibia treated with open reduction and pinning. (a) Anteroposterior radiograph of the left knee at presentation shows a fracture through the growth plate (straight arrow) with medial displacement of the metaphysis (curved arrow). There is a fracture of the fibula (arrowhead). (b) Sagittal SPGR (60/6 with 40° flip angle) image of the lateral portion of the knee at 3 months after injury shows no bridge or fracture. There are small intrusions of growth plate cartilage (arrows) into the tibial metaphysis. (c) Sagittal SPGR (60/6 with 45° flip angle) image (same level as b) at 14 months after injury shows progressive growth plate deformity with deeper intrusions (arrows) as the metaphysis has grown. (d) Sagittal SPGR (60/6 with 40° flip angle) image through the midline at 3 months after injury shows a block of cartilage (arrow) displaced into the epiphysis. There are small intrusions (arrowheads) anteriorly. (e) Sagittal SPGR (60/6 with 45° flip angle) image (same level as d) at 11 months after injury shows a deeper intrusion (arrowhead) into the growth plate anteriorly and a large area of widened and depressed growth plate (arrow) posteriorly. The block of cartilage in the epiphysis has been largely resorbed.

View larger version (147K): [in this window] [in a new window]   Figure 7c. Patient 8. Images in a 12-year-old boy with an open Salter-Harris 2 fracture of the proximal tibia treated with open reduction and pinning. (a) Anteroposterior radiograph of the left knee at presentation shows a fracture through the growth plate (straight arrow) with medial displacement of the metaphysis (curved arrow). There is a fracture of the fibula (arrowhead). (b) Sagittal SPGR (60/6 with 40° flip angle) image of the lateral portion of the knee at 3 months after injury shows no bridge or fracture. There are small intrusions of growth plate cartilage (arrows) into the tibial metaphysis. (c) Sagittal SPGR (60/6 with 45° flip angle) image (same level as b) at 14 months after injury shows progressive growth plate deformity with deeper intrusions (arrows) as the metaphysis has grown. (d) Sagittal SPGR (60/6 with 40° flip angle) image through the midline at 3 months after injury shows a block of cartilage (arrow) displaced into the epiphysis. There are small intrusions (arrowheads) anteriorly. (e) Sagittal SPGR (60/6 with 45° flip angle) image (same level as d) at 11 months after injury shows a deeper intrusion (arrowhead) into the growth plate anteriorly and a large area of widened and depressed growth plate (arrow) posteriorly. The block of cartilage in the epiphysis has been largely resorbed.

View larger version (139K): [in this window] [in a new window]   Figure 7d. Patient 8. Images in a 12-year-old boy with an open Salter-Harris 2 fracture of the proximal tibia treated with open reduction and pinning. (a) Anteroposterior radiograph of the left knee at presentation shows a fracture through the growth plate (straight arrow) with medial displacement of the metaphysis (curved arrow). There is a fracture of the fibula (arrowhead). (b) Sagittal SPGR (60/6 with 40° flip angle) image of the lateral portion of the knee at 3 months after injury shows no bridge or fracture. There are small intrusions of growth plate cartilage (arrows) into the tibial metaphysis. (c) Sagittal SPGR (60/6 with 45° flip angle) image (same level as b) at 14 months after injury shows progressive growth plate deformity with deeper intrusions (arrows) as the metaphysis has grown. (d) Sagittal SPGR (60/6 with 40° flip angle) image through the midline at 3 months after injury shows a block of cartilage (arrow) displaced into the epiphysis. There are small intrusions (arrowheads) anteriorly. (e) Sagittal SPGR (60/6 with 45° flip angle) image (same level as d) at 11 months after injury shows a deeper intrusion (arrowhead) into the growth plate anteriorly and a large area of widened and depressed growth plate (arrow) posteriorly. The block of cartilage in the epiphysis has been largely resorbed.

View larger version (150K): [in this window] [in a new window]   Figure 7e. Patient 8. Images in a 12-year-old boy with an open Salter-Harris 2 fracture of the proximal tibia treated with open reduction and pinning. (a) Anteroposterior radiograph of the left knee at presentation shows a fracture through the growth plate (straight arrow) with medial displacement of the metaphysis (curved arrow). There is a fracture of the fibula (arrowhead). (b) Sagittal SPGR (60/6 with 40° flip angle) image of the lateral portion of the knee at 3 months after injury shows no bridge or fracture. There are small intrusions of growth plate cartilage (arrows) into the tibial metaphysis. (c) Sagittal SPGR (60/6 with 45° flip angle) image (same level as b) at 14 months after injury shows progressive growth plate deformity with deeper intrusions (arrows) as the metaphysis has grown. (d) Sagittal SPGR (60/6 with 40° flip angle) image through the midline at 3 months after injury shows a block of cartilage (arrow) displaced into the epiphysis. There are small intrusions (arrowheads) anteriorly. (e) Sagittal SPGR (60/6 with 45° flip angle) image (same level as d) at 11 months after injury shows a deeper intrusion (arrowhead) into the growth plate anteriorly and a large area of widened and depressed growth plate (arrow) posteriorly. The block of cartilage in the epiphysis has been largely resorbed.

View larger version (114K): [in this window] [in a new window]   Figure 8a. Patient 13. Images in an 8-year-old girl with known Blount disease who was examined for growth plate deformity. Radiographs (not shown) showed typical findings of Blount disease without apparent bridging. (a) Sagittal SPGR (60/6 with 40° flip angle) image of left knee through the medial femoral condyle. Anteriorly, the tibial growth plate is unremarkable, but posteriorly there is marked thickening and irregularity (arrows) with one deep intrusion into the metaphysis (arrowhead). (b) Reformatted coronal image of the anterior portion of the joint shows thickened cartilage and corresponding underdevelopment of the epiphysis medially (large arrow). The adjacent growth plate is thickened and there are small intrusions into the metaphysis (small arrows). (c) A 3D model, inferior view. The growth plate shows no bridging. Posteromedially, the intrusions (between arrows) are displayed. Anterolaterally, the normal cartilage (arrowheads) of the tibial tuberosity is demonstrated.

View larger version (114K): [in this window] [in a new window]   Figure 8c. Patient 13. Images in an 8-year-old girl with known Blount disease who was examined for growth plate deformity. Radiographs (not shown) showed typical findings of Blount disease without apparent bridging. (a) Sagittal SPGR (60/6 with 40° flip angle) image of left knee through the medial femoral condyle. Anteriorly, the tibial growth plate is unremarkable, but posteriorly there is marked thickening and irregularity (arrows) with one deep intrusion into the metaphysis (arrowhead). (b) Reformatted coronal image of the anterior portion of the joint shows thickened cartilage and corresponding underdevelopment of the epiphysis medially (large arrow). The adjacent growth plate is thickened and there are small intrusions into the metaphysis (small arrows). (c) A 3D model, inferior view. The growth plate shows no bridging. Posteromedially, the intrusions (between arrows) are displayed. Anterolaterally, the normal cartilage (arrowheads) of the tibial tuberosity is demonstrated.

View larger version (140K): [in this window] [in a new window]   Figure 8b. Patient 13. Images in an 8-year-old girl with known Blount disease who was examined for growth plate deformity. Radiographs (not shown) showed typical findings of Blount disease without apparent bridging. (a) Sagittal SPGR (60/6 with 40° flip angle) image of left knee through the medial femoral condyle. Anteriorly, the tibial growth plate is unremarkable, but posteriorly there is marked thickening and irregularity (arrows) with one deep intrusion into the metaphysis (arrowhead). (b) Reformatted coronal image of the anterior portion of the joint shows thickened cartilage and corresponding underdevelopment of the epiphysis medially (large arrow). The adjacent growth plate is thickened and there are small intrusions into the metaphysis (small arrows). (c) A 3D model, inferior view. The growth plate shows no bridging. Posteromedially, the intrusions (between arrows) are displayed. Anterolaterally, the normal cartilage (arrowheads) of the tibial tuberosity is demonstrated.

	DISCUSSION

TOP Abstract Introduction MATERIALS AND METHODS RESULTS DISCUSSION References

 
MR is now the imaging method of choice for evaluation of premature closure of the epiphyseal plate. Definition of bone bridges across the physis can be obtained with 3D modeling.

Disler (19) described the use of a 3D fat-saturated SPGR sequences for reformatted 3D imaging of the growth plate. Advantages of such sequences include excellent contrast between cartilage and bone marrow, thin sections, and increased signal-to-noise ratio. The major disadvantage is the relatively long acquisition time, 16 minutes 27 seconds for 60 sections. Previously, scanning with conventional tomography lasted longer and exposed the patient to radiation. Currently, a routine MR examination of the knee or ankle that includes the SPGR sequence requires 45 minutes and spares the patient from radiation.

The optimal technique to visualize the physis in 3D is to make a model by outlining the physeal cartilage on multiple sagittal or coronal images. This information is then used for the reconstruction by the computer. The model can be displayed by using either the MIP or 3D rendering. Once the model of the growth plate is produced, it can be readily alternated between MIP and 3D displays. The area of bone bridging can be measured on both the MIP and 3D models, yielding similar values with the two methods, but we found the process to be easier with the MIP model. Each method will underestimate the areas of both the bridge and the growth plate owing to the display of an undulating 3D structure in two dimensions.

Modeling of the physis is not a perfect technique. Although we did not determine the precision of this method of measurement directly, an indication of slight variation was seen in the results for patient 10 (Table). With little or no change in the appearance of the bone bridge, the percentage bridging was consistently about 1% for this patient. Partial volume averaging of the growth plate with adjacent bone marrow where the plate was thin and with adjacent bone marrow edema may have interfered with the process. When cartilage was present but had low signal intensity on the SPGR images because of fracture (Fig 5), distinction from bridging had to be made with care. Supervision by a radiologist is required during modeling, and strict correlation with the SPGR images is essential. Although it is not of great consequence, the anterior and posterior margins of the growth plate on coronal images and the lateral margins on sagittal images may be less well defined than are other margins.

Bone bridging occurred in a variety of patterns (Figs 1–4). Bright (20) and Ogden (6) comment on the various patterns of bridging. Six of our patients in whom bone bridging was present had more than one discrete area of bridging (Figs 1, 2). No findings were identified that enabled prediction of premature closure of the growth plate. Indications for resection of bridges include bridging of less than 50% with more than 2 years of growth remaining. If there are central or multiple bridges, surgery may be contraindicated because of the amount of plate that would have to be removed to gain access.

Trueta and Amato (21) studied changes in the growth cartilage caused by experimentally induced ischemia in rabbits. By using rabbits, Jaramillo et al (22) also studied the growth plate after trauma. Kleinman et al (23) and Kleinman and Marks (24) studied the growth plates of abused infants. All groups found intrusion of the growth plate into the metaphysis during posttraumatic growth. The three groups of investigators attributed the phenomenon to injury to the metaphyseal vessels with failure of endochondral ossification. As a result, portions of cartilage from the growth plate become fixed in the metaphysis while growth of bone continues. This results in several patterns: deep intrusions of the growth plate into the metaphysis (Fig 7c), persistence of a band of cartilage in the metaphysis (Fig 6b, 6c), or widening and irregularity of the growth plate (Fig 7d, 7e). Small islands of cartilage may also be trapped in the epiphysis (Fig 7e).

A low-signal-intensity stripe in the growth plate may be seen with and without bridging. It has been attributed to fracture by Jaramillo and Hoffer (25) and Rogers and Poznanski (9). Whereas fracture explains many of the MR findings, there are some inconsistencies in the appearance of the stripe: It was not seen in all patients, it was shown in only a part of the growth plate, and it did not always correspond to the extent of the fracture shown at radiography.

Jaramillo et al (26) found gadolinium enhancement useful in imaging of posttraumatic bone bridges. We found enhancement with gadopentetate dimeglumine useful in imaging of the postsurgical growth plate. If the surgery involved the placement of fat in the area from which the bridge was resected, the fat was of low signal intensity on SPGR images. With gadopentetate dimeglumine, we found no linear enhancement between the epiphysis and metaphysis to suggest recurrent bridging; instead, we saw enhancement around the periphery of the fat graft. In our limited experience with two patients, the most useful sequence in the postoperative period was the thin-section (1.5 mm) fat-saturated gadolinium-enhanced T1-weighted spin-echo sequence.

Our data suggest that bridges start to form between 1 and 2 months after injury (Table). Optimal imaging time is still open to discussion.

In conclusion, fat-saturated SPGR imaging and 3D modeling of the growth plate depict areas of bone bridging or deformity following trauma, sepsis, or Blount disease and can show fixation of parts of the plate, which causes marked distortion. Surgical therapy is facilitated.

View larger version (113K): [in this window] [in a new window]   Figure 3a. Patient 2. Representative pattern of central bone bridging. (a) Sagittal SPGR (60/8 with 40° flip angle) image of the left knee shows both peripheral (short arrow) and central (long arrow) bone bridges with cartilage of the growth plate disrupted by small bridges (between arrowheads). The plane of this section is indicated in b. (b) Superoinferior 3D model shows two areas of central bone bridging (black arrows) and a peripheral bridge anteriorly (white arrow). The red line indicates the sagittal plane of projection for a.

View larger version (99K): [in this window] [in a new window]   Figure 3b. Patient 2. Representative pattern of central bone bridging. (a) Sagittal SPGR (60/8 with 40° flip angle) image of the left knee shows both peripheral (short arrow) and central (long arrow) bone bridges with cartilage of the growth plate disrupted by small bridges (between arrowheads). The plane of this section is indicated in b. (b) Superoinferior 3D model shows two areas of central bone bridging (black arrows) and a peripheral bridge anteriorly (white arrow). The red line indicates the sagittal plane of projection for a.

	Acknowledgments

 
The authors thank Chandan Mehta, Linda Coulter, RT, Antonio La-Barera, BS, and Jacqueline Kralik, RT, for processing the 3D images required for this study.

	Footnotes

 
Address reprint requests to J.G.C.

Abbreviations: MIP = maximum intensity projection SPGR = spoiled gradient-recalled 3D = three-dimensional

Author contributions: Guarantors of integrity of entire study, J.G.C., K.E.C.; study concepts, J.G.C., K.E.C.; study design, J.G.C., K.E.C., D.D.C., D.O.H.; definition of intellectual content, J.G.C., W.R.E.; literature research, J.G.C., R.Y.C., W.R.E.; clinical studies, K.E.C., J.G.C.; data acquisition, J.G.C., K.E.C., D.D.C., D.O.H.; data analysis, J.G.C., D.D.C., D.O.H., W.R.E.; manuscript preparation, J.G.C., R.Y.C., D.D.C., W.R.E.; manuscript editing, J.G.C., W.R.E., D.D.C.; manuscript review, all authors.

Received February 6, 1998; revision requested March 25, 1998; revision received July 31, 1998; accepted October 13, 1998.

	References

TOP Abstract Introduction MATERIALS AND METHODS RESULTS DISCUSSION References

 

1. Mizuto T, Benson WM, Foster BK, Paterson DC, Morris LL. Statistical analysis of the incidence of physeal injuries. J Pediatr Orthop 1987; 7:518-523.[Medline]
2. Smith BG, Rand F, Jaramillo D, et al. Early MR imaging of lower-extremity physeal fracture-separations: a preliminary report. J Pediatr Orthop 1994; 14:526-533.[Medline]
3. Riseborough E, Barrett I, Shapiro F. Growth disturbances following distal femoral physeal fracture-separations. J Bone Joint Surg [Am] 1983; 65:885-893.[Free Full Text]
4. Bright RW. Physeal injuries. In: Rockwood CA, Jr, Wilkins KE, King RE, eds. Fractures in children. Vol 3. Philadelphia, Pa: Lippincott, 1984; 87-172.
5. Ogden JA. The evaluation and treatment of partial physeal arrest. J Bone Joint Surg [Am] 1987; 69:1297-1302.[Free Full Text]
6. Ogden JA. Injury to the growth mechanisms. In: Ogden JA, eds. Skeletal injury in the child. 2nd ed. Philadelphia, Pa: Saunders, 1990; 97-173.
7. Pease CN. Focal retardation and arrestment of growth of bones due to vitamin A intoxication. JAMA 1962; 182:980-985.
8. Caffey J. Traumatic cupping of the metaphyses of growing bones. AJR 1970; 108:451-460.[Abstract]
9. Rogers LF, Poznanski AK. Imaging of epiphyseal injuries. Radiology 1994; 191:297-308.[Abstract/Free Full Text]
10. Harcke HT, Snyder M, Caro PA, Bowen JR. Growth plate of the normal knee: evaluation with MR imaging. Radiology 1992; 183:119-123.[Abstract/Free Full Text]
11. Chung T, Jaramillo D. Normal maturing distal tibia and fibula: changes with age at MR imaging. Radiology 1995; 194:227-232.[Abstract/Free Full Text]
12. Carlson WO, Wenger DR. A mapping method to prepare for surgical excision of a partial physeal arrest. J Pediatr Orthop 1984; 4:232-238.[Medline]
13. Harcke HT, Macy NJ, Mandell GA, et al. Quantitative assessment of growth plate activity (abstr). J Nucl Med 1984; 25:115.
14. Decampo JF, Boldt DW. Computed tomography of partial growth plate arrest: initial experience. Skeletal Radiol 1986; 15:526-529.[Medline]
15. Young JWR, Bright RW, Whitley NO. Computed tomography in the evaluation of partial growth plate arrest in children. Skeletal Radiol 1986; 15:530-535.[Medline]
16. Murray K, Nixon GW. Epiphyseal growth plate: evaluation with modified coronal CT. Radiology 1988; 166:263-265.[Abstract/Free Full Text]
17. Gabel GT, Peterson HA, Berquist TH. Premature partial physeal arrest. Clin Orthop 1991; 272:242-247.
18. Borsa JJ, Peterson HA, Ehman RL. MR imaging of physeal bars. Radiology 1996; 199:683-687.[Abstract/Free Full Text]
19. Disler DG. Fat-suppressed three-dimensional spoiled gradient recalled MR imaging: assessment of articular and physeal hyaline cartilage. AJR 1997; 169:1117-1123.[Abstract/Free Full Text]
20. Bright RW. Partial growth arrest: identification, classification and results of treatment. Orthop Trans 1982; 6:65-66.
21. Trueta J, Amato VP. The vascular contribution to osteogenesis. III. Changes in the growth cartilage caused by experimentally induced ischaemia. J Bone Joint Surg [Br] 1960; 42:571-587.
22. Jaramillo D, Laor T, Zaleske DJ. Indirect trauma to the growth plate: results of MR imaging after epiphyseal and metaphyseal injury in rabbits. Radiology 1993; 187:171-178.[Abstract/Free Full Text]
23. Kleinman PK, Marks SC, Jr, Spevak MR, et al. Extension of growth-plate cartilage into the metaphysis: a sign of healing fracture in abused infants. AJR 1991; 156:775-779.[Abstract/Free Full Text]
24. Kleinman PK, Marks SC, Jr. A regional approach to the classic metaphyseal lesion in abused infants: the distal femur. AJR 1998; 170:43-47.[Abstract/Free Full Text]
25. Jaramillo D, Hoffer FA. Cartilaginous epiphysis and growth plate: normal and abnormal MR imaging findings. AJR 1992; 158:1105-1110.[Abstract/Free Full Text]
26. Jaramillo D, Shapiro F, Hoffer FA, et al. Posttraumatic growth-plate abnormalities: MR imaging of bony-bridge formation in rabbits. Radiology 1990; 175:767-773.[Abstract/Free Full Text]

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