Radiology of postnatal skeletal development

Initially the distal tibial physis is a relatively transverse structure. As the epiphysis matures, undulations develop within the physis and lappet formation occurs peripherally. Within the first two years a significant physeal undulation develops anteriorly above the medial malleolus. This undulation must not be misinterpreted as premature epiphyseodesis following distal tibial fracture. Secondary ossification in the distal tibia begins centrally and initially expands to fill the area over the tibial plafond. At the lateral side of the tibial epiphysis the ossification center may be wedgeshaped. The medial margin adjacent to the medial malleolus is often irregular and may show small peripheral foci of ossification. By seven to eight vears, the secondary center extends into the medial malleolus, with complete distal extension often not occurring until adolescence (although usually complete by ten to eleven years). The malleolar tip may exhibit an accessory ossification center. However, this center also may be a traumatic avulsion in the symptomatic patient. Physiologic epiphyseodesis begins over the medial malleolus and subsequently extends laterally. This pattern of closure appears to predispose to fracture of the lateral portion of the distal tibial epiphysis (fracture of Tillaux), as well as to triplane fractures. The articular surface curves onto the lateral side of the distal tibia to form an articulation with the lateral malleolus (distal tibiofibular joint). A similar extension occurs along the medial side of the fibula. These surfaces extend proximally as a recess to the level of the distal tibial physis, at which point the syndesmosis begins. The initially transverse distal fibular physis becomes a convoluted structure, with extensive peripheral lappet formation. Within these regions of physeal overlap there may be small areas of accessory ossification (both medially and laterally) that should not be misinterpreted as fractures. This overlapping also minimizes specific physeal separation and displacement (especially when compared to the incidence of distal tibial physeal injuries). Stress views may be necessary to show such an undisplaced fracture. The fibular physis normally is level with the tibial articular surface or distal extent of the tibial ossification center, especially after the second year of life (however, it may be more proximal in infants). As in the medial malleolus, there may be accessory ossification at the tip of the fibula. While this usually is a normal variant of secondary ossification, occasionally it also may result from trauma. Extensive porosity of the distal fibular metaphysis predisposes to buckling or torus injuries that may have severe, multiangular deformation.     

Radiology of postnatal skeletal development

The patella initially ossifies at between three and five years, commencing as multiple foci that rapidly coalesce. As the patellar ossification center enlarges the expanding margins may be irregular and associated with accessory ossification centers. These are most common superolaterally and may lead to the development of a bipartite patella. The bipartite patella has cartilaginous continuity despite the appearance of osseous discontinuity. The patella expands to all cartilaginous contours during late adolescence when the epiphyseal ossification centers around the knee are also in the final stages of maturation. The only cartilage not replaced is that occupying the superior twothirds of the articular surface (the lower one-third is covered by the fat pad). The subchondral plate does not assume the actual articular contours until the late stages of osseous maturation (after ten to twelve years). Accordingly, typical measurements such as medial and lateral angulation cannot be accurately done prior to the final stages of patellar ossification expansion and maturation.The tibial tuberosity begins ossification at between seven and nine years as a distal focus. This progressively enlarges proximally and anteriorly, while the main tibial ossification center concomitantly expands downward into the tuberosity. A section of epiphyseal cartilage usually remains between these two ossification centers until close to physeal maturity. The anterior chondro-osseous region at the site of patellar tendon attachment is a biomechanically susceptible region that may be acutely or chronically traumatized to create an Osgood-Schlatter lesion. The physis associated with the tibial tuberosity is histologically modified in a proximal to distal gradation of columnar adaptation to specific biomechanical demands in this region. Closure of the tuberosity physis occurs in a proximal to distal direction.     

Correlative roentgenography and morphology of the longitudinal epiphyseal bracket

Detailed examination of a complete chondro-osseous specimen from a patient with duplication of the first ray of the foot revealed the involved metatarsal had a trapezoid-shaped, diaphyseal-metaphyseal osseous unit that was longitudinally bracketed along the lateral side by a functioning physis, epiphysis, and secondary (epiphyseal) ossification center. The physis extended as an arc from the medial proximal side toward and along the lateral side and then back to the medial side distally. The medial side of the diaphysis had a normal periosteum. The longitudinal epiphyseal ossification bracket was a composite of initially separate proximal and distal secondary ossification centers that had progressively extended toward each other and finally coalesced along the laterally placed epiphyseal cartilage. We have termed this deformity the longitudinal epiphyseal bracket (LEB). The macroscopic and microscopic anatomy relevant to initial diagnosis and evaluation of sequential roentgenographic changes will be considered.     

Injuries of the medial epicondylar ossification center of the humerus.

The complex nature of the ossification centers makes elbow injuries in a child or adolescent difficult to evaluate. The medial epicondylar ossification center is involved in a significant proportion. Injuries vary from simple avulsions to wide displacement with entrapment in the elbow. When entrapment occurs, it may be mistaken for the trochlear ossification center and the true nature of the injury overlooked. Radiographic findings are presented. The anteroposterior view was found to be diagnostic in minimal or marked avulsions of the medial epicondyle because of the characteristic inferior displacement. The anteroposterior view may not always be diagnostic in cases of entrapment of the medial epicondyle; the lateral view is usually diagnostic. In elbow dislocation, the presence and position of the medial epicondyle must be ascertained. Comparison and oblique views are often of value.     

Radiology of postnatal skeletal development

Thirty-one pairs of distal radioulnar units were obtained from human cadavers ranging in age from full-term neonates to fourteen years. These were studied morphologically and radiographically. Specimen roentgenography using air/cartilage interfacing demonstrated the osseous and cartilaginous portions of the epiphyses. These roentgenographic aspects of development are discussed and illustrated to provide a reference index.The radial and ulnar physeal/metaphyseal contours initially are transverse. Progressively the distal radius develops a proximally directed curve adjacent to the radioulnar joint. Both physes subsequently develop a convex contour with mild undulations, and a central concavity associated with the secondary ossification center. Longitudinal ossification striations were observed crossing the distal ulnar physis. These appear to be normal.At no time during postnatal development did the distal ulna ever articulate directly with the carpus. It was always separated by a segment of triangular fibrocartilage connecting the ulnar styloid to the distal radial epiphysis. This was never perforated. this discoid cartilaginous structure is the anatomic cause of the concomitancy of ulnar styloid fractures with distal radial epiphyseal injuries, an injury pattern which may occur prior to ossification in the ulnar styloid, and which may lead to non-union of the styloid when ossification eventually occurs. In none of the specimens was an accessory ossification center present in either the radial or ulnar styloid process.     

Ossification and pseudoepiphysis formation in the “nonepiphyseal” end of bones of the hands and feet

Metacarpals, metatarsals, and phalanges were studied to assess the developmental morphology of secondary ossification in the nonepiphyseal ends of these bones as well as the formation of the pseudoepiphysis as an epiphyseal ossification variant. Both direct ossification extension from the metaphysis into the epiphysis and pseudoepiphysis formation preceded, and continued to be more mature than, formation and expansion of the classic epiphyseal (secondary) ossification center at the opposite end of each specific bone. Direct metaphyseal to epiphyseal ossification usually started centrally and expanded hemispherically, replacing both physeal and epiphyseal cartilage simultaneously. In contrast, when remnants of physis were retained, while juxtaposed epiphyseal cartilage was replaced, a pseudoepiphysis formed. There were three basic patterns of pseudoepiphysis formation. First, a central osseous bridge extended from the metaphysis across the physis into the epiphysis and subsequently expanded to create a mushroom-like osseous structure. In the second pattern a peripheral osseous bridge formed, creating either an osseous ring or an eccentric bridge between the metaphysis and the epiphysis. In the third pattern, multiple bridging occurred. In each situation the associated remnant physis lacked typical cell columns and was incapable of significantly contributing to the postnatal longitudinal growth of the involved bone. Pseudoepiphyses were well formed by 4–5 years and coalesced with the rest of the bone months of years before skeletal maturation was attained at the opposite epiphyseal end, which ossified in the typical pattern (i.e., formation of a secondary center de novo completely within the cartilaginous epiphysis). This process may also affect the development and appearance of ossification within the longitudinal epiphyseal bracket (delta phalanx).     

Enhanced possibilities to make statements on the ossification status of the medial clavicular epiphysis using an amplified staging scheme in evaluating thin-slice CT scans

Thin-slice computed tomography provides the imaging modality of choice in analysing the ossification process of the medial clavicular epiphysis for the purpose of forensic age diagnostics in the living in the course of criminal proceedings. The classification of the ossification stages by Schmeling et al. compass the emergence of an epiphyseal ossification centre (stage 2), the partial fusion of the epiphysis with the metaphysis (stage 3), the complete fusion of these osseous elements including a visible epiphyseal scar (stage 4), and the complete fusion without a visible epiphyseal scar (stage 5). In the present study, each of the ossification stages 2 and 3 was divided into an early, intermediate and late phase. The authors evaluated the thin-slice CT scans of 185 patients aged between 13 and 26 years. In all these cases, a stage 2 or 3 had been determined in a previous study. The late stage 3, which is characterized by a fusion between metaphysis and epiphysis completing more than two thirds of the former epiphyseal gap, first appeared at age 19 in both sexes. If a late stage 3 is found, it is therefore possible to substantiate that an individual has already reached the legally important age threshold of 18 years.     

Magnetic resonance imaging in acute physeal injuries

Magnetic resonance imaging (MRI) permits noninvasive evaluation of the cartilage of the growth plate and epiphysis. This paper reports three cases where MRI was used to supplement conventional radiography in the assessment of acute physeal injuries. In the first patient, MRI was used for postoperative assessment of a radial neck fracture, avoiding further surgical exploration. In the second case, MRI was compared with ultrasonography in the diagnosis of proximal humeral epiphyseal separation in a neonate. In the third case, MRI and computed tomography were compared in evaluation of a Salter-Harris type 4 distal femur fracture. In all cases MRI was diagnostic. MRI is the investigation of choice in acute complex physeal injuries, and is particularly appropriate for use prior to the appearance of the secondary ossification center.     

Radiology of postnatal skeletal development

The development of the second cervical vertebra is complex. The dens (odontoid process) develops two primary ossification centers that usually coalesce within three months following birth. These centers are separated from the primary ossification center of the vertebral centrum by a cartilaginous region—the dentocentral synchondrosis. This synchondrosis is a slow growing, bipolar physis similar to the triradiate catilage of the acetabulum. It contributes to the overall heights of both the dens as well as the vertebral body. Anatomically the dentocentral synchondrosis is below the level of the C1–C2 articulations. This cartilaginous structure is continuous throughout the vertebral body with similar cartilage in both the facet regions as well as the neurocentral synchondroses. These various carulaginous continuities progressively close—first, the connections to the facet regions, next the neurocentral synchondroses, and finally the dentocentral synchondrosis. Remnants of the incompletely closed dentocentral synchondrosis must be distinguished from a fracture, which usually propagates along this structure as a physeal injury in infants and children. The cartilaginous epiphysis at the tip of the dens may be transverse or may form a cleft (V) shape. At eight to ten years, a secondary ossification center—the ossiculum terminale—develops in this proximal dens epiphysis. Fusion of the ossiculum terminale with the rest of the dens occurs between ten and thirteen years.     

Beurteilung des Ossifikationsstadiums der medialen Klavikulaepiphysenfuge

In forensic age estimation of the living in criminal proceedings the radiological examination of the ossification status of the medial clavicular epiphysis permits an assessment with regard to the completion of 21 years of age. In the present study the authors prospectively comparatively analyzed 8 prepared samples of the sternoclavicular region of individuals aged 15–17 years obtained during autopsy by means of projectional radiography, thin-slice computed tomography and magnetic resonance imaging. In 6 out of 15 examined sternoclavicular joints the ossification stage of the medial clavicular epiphysis was in agreement in each of the three imaging methods used. In the remaining cases the ossification stage was assessed as either one stage higher or lower in one of the imaging methods than in the other two techniques. In five cases compared to CT, and seven cases compared to MR, projectional radiography showed a higher ossification stage than CT and MR imaging. In two cases projectional radiography resulted in the determination of a lower stage than in CT and MR imaging. MR scans showed a less advanced ossification stage than CT-based images in two cases. In the practice of age estimation modality-specific reference studies based on projectional radiography and computed tomography are to be applied in order to guarantee an adequate assessment of the ossification stage of the medial clavicular epiphysis.     

Case report 280

A fracture involving the trochlear ossification center as well as the medial epicondyle is a more serious injury than simple avulsion of the medial epicondyle. This diagnosis may be difficult in young children before the secondary centers are ossified. Radiographic clues to this injury in a young child are localized soft tissue swelling over the medial aspect of the elbow accompanied by a metaphyseal flake and/or a positive fat pad sign. In the older child, separation of the ossified medial epicondyle with a positive fat pad sign suggests a more complex injury.     

Epiphyseal extension of a unicameral bone cyst

 Epiphyseal extension of a unicameral bone cyst is rare. We report a case of a 13-year-old boy with three pathological fractures through a unicameral bone cyst with epiphyseal involvement in the proximal humerus. These lesions initially tends to expand the humeral epiphysis laterally and progress medially. They also commonly cause a slip of the epiphysis in a medial direction. They also have a greater association with growth retardation and lesser degree of recurrence than their metaphyseal counterpart.     

The utility of MR in assessing Blount disease

OBJECTIVE: To review the MR appearances of Blount disease. DESIGN AND PATIENTS: The MR examinations of six knees in four patients (ages 6-7 years) with Blount disease were reviewed. RESULTS: All patients showed delay in ossification of the medial tibial epiphysis. A spectrum of changes was seen in and around the tibial growth plate including: widening and depression of the medial growth plate; small and deep intrusions of cartilage into the metaphysis; edema of the medial tibial epiphysis and medial and lateral metaphysis; varus deformity of the lower leg; widening of the lateral growth plate; osteochondral injury to the medial femoral condyle; hypertrophy of the medial meniscus; focal bone bridging. CONCLUSION: MR appearances are consistent with the primary abnormality in Blount disease, which is failure of endochondral ossification of the medial growth plate. MR examination is useful in surgical planning.     

Radiology of postnatal skeletal development

Thirty-six pairs of proximal radioulnar and elbow units from cadavers and prepared skeletons ranging in age from full-term neonates to fourteen years, were studied morphologically and roentgenographically. Air/cartilage interfacing was used to demonstrate the osseous and cartilaginous portions of the developing epiphyses. These roentgenographic aspects are discussed and illustrated to provide a reference index.The articular interrelationships and basic contours of the distal humerus, proximal ulna, and proximal radius are the same throughout postnatal development. The major changes are proportional volume increase and the progressive development of the secondary ossification centers. Because of overlap of the developing secondary ossification centers, roentgenographic interpretation may be difficult. Awareness of the developmental stages and variations should assist in the diagnosis of trauma to the immature elbow.During the first few years the proximal ulnar metaphysis is usually at the midpoint of the ulnohumeral joint in a lateral roentgenogram with the elbow flexed at 90°. With further growth and maturation this region of the metaphysis extends proximally. However, such extension is quite variable. The secondary ossification center, which will form most of the olecranon at skeletal maturity, initially forms adjacent to the dorsal side of the metaphysis. Multifocal ossification, while a relatively common clinical observation, was not seen in any of the specimens.The radial head is intra-articular, as is part of the neck (metaphysis). However, attachments of the capsule are such that none of the ulnar metaphysis is intra-articular. The proximal radius has the same contours and relative proportions of head and neck throughout postnatal development. The head is always larger than the neck. However, the contours of the sides of the radial head are of variable obliquity, allowing different degrees of excursion of the annular ligament during rotation (supination-pronation), a factor that anatomically predisposes young children to nursemaid's elbow.The secondary ossification center of the proximal radius initially appears as a linear focus centrally located adjacent to the metaphysis. This progressively expands, but not always symmetrically. The concavity of the articular cartilage may be reflected in a central identation of the ossification center, but this is not usually evident until ten to eleven years. The plane of the articular surface is not at a right angle relative to the longitudinal axis of the radius; instead, there is an increased angulation toward the bicipital tuberosity. This also is a factor predisposing to nursemaid's elbow in the young child.     

Congenital synchondroses in the ischial bones

In this paper, a 39-year-old woman is presented with congenital, symmetrically bilateral synchondroses in the bodies of the ischial bones, which presumably occurred due to extension of two separate primary ossification centers which failed to fuse, instead of a usual single primary ossification center. To the best of the author's knowledge, such an anomaly has not been reported previously in the ischial bones. The apparent clinical significance of these synchondroses was development of degenerative changes about them, which was associated with moderate hip pain in the absence of degenerative hip-joint disease. Received 28 September 1995; Revision received 29 April 1996; Accepted 2 May 1996     

Age-related vascular changes in the epiphysis, physis, and metaphysis: normal findings on gadolinium-enhanced MRI of piglets

OBJECTIVE: We sought to study the normal enhancement patterns seen on MRIs of the epiphysis, physis, and metaphysis and age-related vascular changes in piglets using gadoteridol, a nonionic gadolinium chelate. MATERIALS AND METHODS: We quantitatively and qualitatively analyzed the normal changes on sequential T1-weighted images after the IV administration of gadoteridol. In an investigation approved by the research animal care committee at our hospital, we studied the proximal and distal femurs of 26 piglets 1-6 weeks old and correlated the enhanced images with findings on intermediate-weighted, T2-weighted, and gradient-recalled echo images and at histologic examination. RESULTS: We observed early enhancement of the epiphyseal vascular canals, the main physis, the physis of the secondary ossification center, and a metaphyseal band adjacent to the physis. Enhancement of the epiphyseal and metaphyseal marrow and of the epiphyseal cartilage was slower. In the epiphyseal cartilage, we saw three phases of enhancement: vascular, canalicular, and cartilaginous. As the piglets matured, enhancement of the epiphyseal cartilage decreased, and the epiphyseal vascular canals were less conspicuous. Physeal enhancement was greatest during the first week of life, declined at 3 weeks, and subsequently increased again as the physis came to lie adjacent to a larger segment of the epiphyseal ossification center. CONCLUSION: Gadoteridol-enhanced MRIs showed multiple cartilaginous and vascular structures of the growing skeleton. With maturity and progressive epiphyseal ossification, epiphyseal cartilage enhancement decreased, and physeal cartilage enhancement increased.     

Biomechanics of a previously unknown thyroid cartilage fracture in fatal strangulation

After the death of a 63-year-old woman following pressure against the neck, the injury was assessed forensically and a radiological-preparatory examination of the osseous structure of the larynx was conducted. We used fine preparation and, for further characterization of the fracture, radiological imaging in spiral CT, 3D reconstruction and fine-focus technique (mammography). While a skeletal injury with the basal fractures of the upper horns of the thyroid cartilage was clearly visible in the CT and 3D reconstruction, the radiological visualization of a 3-4mm wide wall-penetrating dehiscence in the upper part of the thyroid cartilage commissure required a higher sensitivity. Using fine-focus technology, we were able to diagnose this fracture as an avulsion of the cartilage from the medial primary ossification center of the thyroid cartilage. Not only has this type of fracture of an insertion avulsion of the median thyrohyoid ligament never been described before, but it must also be considered as the main fracture in dorsocranial traction. In this specific case, it enabled the expert to state in court that strangulation had occurred from behind.     

Comparison of imaging planes during CT-based evaluation of clavicular ossification: a multi-center study

Determining the ossification stage of the medial clavicular epiphysis by computed tomography represents the currently recommended methodology for the question of whether a living individual has completed the 18th or 21st year of life. In the present study, thin-slice CT scans of 1078 sternoclavicular joints were reconstructed in axial and coronal image series and evaluated according to the two classification systems established for age diagnostics using the clavicle. Both image series (axial and coronal) were analyzed separately. When comparing the results of axial and coronal view, a different ossification stage was found in 35.6% of the clavicles. The results suggest an influence of the imaging plane on the process of stage determination. In order to further approximate the three-dimensional and asymmetrical structure of the epiphyseal ossification center, the usage of at least two different reformation types may be recommended. In practice, only those reference studies should be applied which exactly employed the same number and orientations of the reformation types that are going to be used in the respective routine case.

     

Ultrasound studies on the time course of clavicular ossification

When preparing forensic age estimates for living subjects over 18 years of age, it is crucial to evaluate the stage of ossification of the medial clavicular epiphysis. The establishment of radiation-free imaging techniques for assessment of clavicular ossification would be desirable in order to reduce the radiation exposure associated with forensic age estimations. In the present study, 84 right clavicles of test subjects 12–30 years of age were prospectively evaluated by means of ultrasound. Ossification stage classification was possible in 80 of the 84 medial clavicular epiphyses studied. In the remaining cases, stage classification was not possible due to the presence of developmental anomalies. The earliest ages at which the respective ossification stages were observed were 17.1 years for stage 2, 16.7 years for stage 3, and 22.5 years for stage 4. The age intervals observed for the ossification stages are consistent with the known data from radiological and computed tomography assessments. The present study results should be confirmed in a larger number of cases and with analysis of observer variability. Evaluation of medial clavicular epiphyseal ossification by ultrasound could ultimately be a rapid and economic non-ionizing diagnostic imaging procedure for forensic age estimation.     

Medial collateral ligament tear entrapped within a proximal tibial physeal separation: imaging findings and operative reduction

Entrapped soft tissues such as periosteum and tendons have been described within joints and physeal fractures in the literature and frequently result in irreducible fractures and posttraumatic growth disturbances. We believe this case represents a novel presentation of acute, preoperative, magnetic resonance (MR) imaging diagnosis of a torn medial collateral ligament entrapped within a proximal tibial physeal separation. This case is presented with MR imaging and operative correlation of the findings.