Chondral Shear Fracture of the Capitellum in Adolescents—A Report of Two Late Diagnosed Cases and a Review of Literature

Abstract

The chondral shear fracture is a rare sub-type of pediatric capitellum fractures, in which the fractured fragment is almost entirely cartilaginous. Since the fractured fragment is not visible on plain radiographs, these injuries are often missed on initial presentation resulting in delayed diagnosis and poor outcomes. To our knowledge, only eight such cases have been reported in the past. We report the cases of two adolescents with chondral shear fractures of the capitellum, that were initially missed. They both presented to us several months following trauma, with pain and restricted elbow range of motion. They were treated by excision of the intra-articular loose fragment, and one child also required radial head excision due to advanced radio-capitellar arthritis. Both had good outcomes at 1 year follow-up. We provide a review of literature on this injury and emphasize the need for having a high index of suspicion when dealing with elbow trauma in adolescents, so as to avoid missing this rare, but distinct fracture pattern.

Introduction

Capitellum fractures account for < 1% of all pediatric elbow fractures [1]. The chondral shear fracture, called ‘Kocher-Lorenz fracture,’ is an extremely rare sub-type of pediatric capitellum fractures in which the fractured fragment is almost entirely cartilaginous. Since the fractured fragment is not visible on plain radiographs, these injuries are often missed in the acute phase and rapidly progress to radio-capitellar arthritis. To our knowledge, only eight such cases have been reported in the past in skeletally immature children [1–4].

We report the cases of two adolescents who presented 4 and 5 months post-trauma, with chondral shear fractures of the capitellum. Both were treated by excision of the intra-articular loose fragment. Parents of both children consented to have the details of the respective cases submitted for publication.

This report highlights the need for having a high index of suspicion when dealing with elbow trauma in adolescents, so as to avoid missing this rare, but distinct fracture pattern.

Case Report One

A 12-year-old, right-hand-dominant boy suffered left elbow trauma following a fall on the outstretched hand with partially flexed elbow. Plain radiographs did not reveal any fracture, and he was treated elsewhere with immobilization in an above elbow slab for two weeks. He presented to us four months after injury with persistent elbow pain and stiffness. On examination, there was swelling and tenderness over the lateral aspect of the elbow. He had a flexion deformity of 70° with 20° further flexion. Pronation was possible from zero to 30°, but no supination was possible (Fig. 1a). There was no appreciable elbow instability and no neurovascular deficit. Plain X-rays were normal (Fig. 1b). MRI revealed a chondral defect in the anterior capitellar articular surface, and a semilunar shaped fragment of cartilage corresponding to the defect was seen floating free posterior to the radial head (Fig. 1c). CT cuts revealed a faintly discernable outline of the chondral fragment (Fig. 1d).

Fig. 1.

Pre-operative findings in case 1. a Clinical photographs showing flexion deformity at left elbow of 70° with further flexion up to 90°, and restricted forearm rotation. b Antero-posterior and lateral view radiographs of the left elbow at presentation. c Sagittal T2-weighted MRI of the left elbow showing cartilaginous loose body (arrow) and defect in capitellar articular surface (arrowhead). d Sagittal and transverse CT cuts of the left elbow with arrow indicating the chondral fragment

At surgery, the anterior aspect of the capitellum was exposed through the lateral approach between the extensor carpi radialis brevis (ECRB) and extensor digitorum communis (EDC), anterior to the attachment of the lateral collateral ligament. A 10 × 8 mm chondral defect was noted on the antero-inferior surface of the capitellum (Fig. 2a). A friable cartilaginous loose body of 1 cm diameter was found in the joint space. There was considerable radio-capitellar arthritis, and the cartilage overlying the radial head was degenerated (Fig. 2b). The loose body was removed, radial head was excised and arthrolysis was performed for restoration of range of motion. Intra-operatively, elbow range of motion improved to a range of 10°–130° flexion and full prono-supination. Elbow mobilization was commenced on the second post-operative day. At a follow-up of 12 months, the child has remained pain free and has elbow range from 10° to 140°, with full prono-supination (Fig. 2c, d).

Fig. 2.

Intra- and post-operative findings in case 1. a Intra-operative photograph showing showing defect in capitellar articular surface (arrow). b Photograph of excised radial head showing damaged cartilage. c Clinical photographs demonstrating elbow range of motion at one year follow-up. d Lateral view radiograph of left elbow at one year follow-up

Case Report Two

A 15-year-old right-hand-dominant adolescent boy presented to us, 5 months after right elbow trauma due to fall on the out-stretched hand with partially flexed elbow. At presentation, he had a 40° flexion deformity of the elbow joint, with further flexion possible to 120°. Range of forearm rotation was from 80° supination to 80° pronation. There was no gross elbow instability, and neurovascular status was normal. Plain radiographs appeared to be normal (Fig. 3a), whereas MRI revealed a chondral defect in the capitellar articular surface and an intra-articular loose body (Fig. 3b). He underwent arthrotomy through a lateral approach between ECRB and EDC. A rounded chondral ulcer of 1 cm diameter was noted on the antero-inferior surface of capitellum (Fig. 3c). The loose body measuring 1.5 × 1.0 cm was removed (Fig. 3d) and micro-fracture was performed by drilling of the exposed sub-chondral bone with a 0.8-mm Kirschner wire. Following removal of the loose body, elbow range of motion was improved. At follow-up of 12 months, painless range of motion from 10° to 150° flexion and full prono-supination have been maintained.

Fig. 3.

Pre-, intra- and post-operative findings in case 2. a Antero-posterior and lateral view radiographs of the right elbow at presentation. b Sagittal T2 and T1 weighted MRI of the right elbow showing the chondral fragment (arrow) and capitellar cartilage defect (arrow head). c Intra-operative photograph showing defect in capitellar articular surface (arrow). d Photograph of the excised loose body. e Lateral view radiograph of right elbow at 1 year follow-up

Discussion

Capitellar injuries in children are a distinct entity and should be distinguished from the more commonly seen lateral condyle fractures. In the former, the fracture line lies in the coronal plane, producing a fracture entirely within the articular cartilage, whereas in the latter, the fracture line commences in the metaphysis and extends distally and medially toward the joint line. The age of occurrence of these injuries also varies, with lateral condyle fractures usually occurring below the age of 6 years, and capitellum fractures occurring almost exclusively in adolescents.

Capitellar fractures in adults have conventionally been classified as per Morrey [5]. Type I (Hahn-Steinthal) injuries are common; the fracture fragment having a significant bony component, these injuries are readily identified on plain X-rays. On the other hand, Type II (Kocher-Lorenz) are chondral injuries; the fracture fragment consists almost entirely of articular cartilage, with little or no subchondral bone. Hence, the fracture fragment is not visualized on plain radiographs. Type III (Broberg-Morrey) are comminuted capitellar fractures. Type IV (McKee) are shear fractures that involve a large part of the trochlea in addition to the capitellum.

Recently, a new classification system for pediatric and adolescent capitellar fractures was proposed by Murthy et al. [1]. Type I are anterior shear injuries, analogous to the Hahn-Steinthal fractures. Type II are posterolateral shear injuries, an entity that has not been described previously. Type III are chondral shear injuries, analogous to Kocher-Lorenz fractures.

Both the cases reported by us were type II (Kocher-Lorenz type) as per the adult classification or type III (Chondral shear type) as per the classification in children by Murthy et al. Diagnosis of this injury is challenging as the fracture fragment is almost entirely cartilaginous and can only be visualized on MRI. It is one of the injury patterns that constitute the ‘TRASH lesions’ of the elbow (the radiographic appearance seemed harmless) [6]. Capitellar chondral shear injuries are extremely rare with only eight such cases having been described in the past [1–4]. The first case was described by Sodl et al. [2]. In the Murthy et al. series, out of the 37 pediatric capitellar fractures studied over 10 years, only three fractures were of the chondral shear type [1]. As the fracture fragment is not visible in plain radiographs, these fractures are often missed at initial presentation. Out of the eight cases of pediatric chondral shear fracture of the capitellum previously described, all were detected after a delay ranging from 5 weeks to 3 years. Hence, a high index of suspicion and low threshold for obtaining advanced imaging in the form of MRI are essential for early detection and optimal management of these injuries.

The chondral shear fracture occurs due to the shearing force exerted by the radius on the capitellum, when the child sustains a fall on a partially flexed elbow. The radial head shears off the chondral fragment from the anterior capitellum. This fracture pattern is unlikely to occur in younger children, as the largely cartilaginous capitellum is very resistant to shearing stresses, in contrast to older children and adolescents, where the capitellum is more ossified.

Management depends on the duration of injury. If diagnosed early, the fractured fragment may be re-positioned and fixed in the fracture bed. Options for fixation of the fracture fragment include K-wires, headless screws and bio-absorbable screws. Sodl et al. reported a 12-year-old boy with a Kocher-Lorenz fracture following direct impact to a hyper-flexed elbow, diagnosed 5 weeks after trauma [2]. The fragment was fixed using a novel horizontal mattress suture cross-stitch technique. The authors reported good clinical and radiological outcomes at 14-month follow-up. In our two cases, reposition and fixation of the fragment was not feasible as the fracture fragment was hypertrophied and misshapen due to the delayed diagnosis. Treatment in such cases consists of excision of the osteochondral fragment, as previously described [1, 3, 4].

Delayed diagnosis may be complicated by rapid progression of radio-capitellar joint degenerative changes and loss of elbow range of motion. We noted advanced degenerative changes in the cartilage overlying the radial head in case one who presented to us 4 months post-trauma, due to which radial head excision was performed. Radio-capitellar arthritis and diminished elbow movements were also noted by Frank et al. in three adolescents who presented after a delay of 4–6 months, for which all underwent radial head excision in addition to removal of the loose body [4]. Undetected micro-instability of the radio-capitellar joint representing a greater injury to the capsulo-ligamentous complex with elbow subluxation at the time of injury, or occult associated injuries to the radial head may be factors in the causation of these rapid degenerative changes [4, 7]. In fact, in our first case, pre-operative MRI does reveal slight posterior translation of the radial head, suggestive of radio-capitellar instability, even though the joint was stable on examination. Under normal circumstances, excision of the radial head is not recommended till skeletal maturity; however, it is the only option available in the presence of such advanced degenerative changes. Excision of the radial head in adolescence has not been shown to be associated with late consequences in the form of proximal migration of the radius, arthrosis, cubitus valgus or wrist pain at follow-up ranging from 47 months to 8 years [8, 9]. Although both our cases had good short-term results in the form of restoration of elbow range of motion and absence of pain, long-term follow-up is needed to look for delayed consequences. Case one will need to be monitored for late consequences of radial head excision. Similarly, case two needs to be monitored for the development of radio-capitellar arthritis due to incongruity between the radial head and the capitellar surface which is now devoid of articular cartilage.

Conclusion

The chondral shear fracture of the capitellum is an extremely uncommon injury in skeletally immature children. Plain X-rays are normal, and MRI is needed for diagnosis. Due to this, the injury is often missed at initial presentation and is diagnosed late. In late presentation, fragment reposition and fixation are often not feasible and fragment excision may be needed. In addition, rapid progression to radio-capitellar arthritis may necessitate radial head excision as well. Short-term outcomes are satisfactory; however, long-term implications have not been sufficiently studied.

Author contributions

Taral V. Nagda contributed to concepts, design, definition of intellectual content, literature search, data acquisition, data analysis. Sandeep V. Vaidya helped in building concepts, design, defining intellectual content, literature search, data acquisition, data analysis, manuscript preparation, manuscript editing, manuscript review. Deepika A. Pinto was involved in design, literature search, data analysis, manuscript preparation, manuscript editing, manuscript review, and she is the guarantor of this case report.

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The authors declare that they have no conflict of interest.

Patient Declaration Statement

The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

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All procedures performed in this study were in accordance with the ethical standards of the institutional research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.

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This is a retrospective observational study (case report). This article does not contain any studies with human or animal participants performed by any of the authors.

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Informed consent was obtained from all individual participants included the study.