Trash Lesions Around the Elbow: A Review of Approach to Diagnosis and Management

Abstract

TRASH lesions are a group of special injuries around the elbow resulting from high energy trauma that are routinely missed at initial presentation because of seemingly normal X-rays. These are a group of osteochondral injuries having a high propensity for surgical intervention and usually have poor outcomes if not treated adequately. Prompt diagnosis warrants a high index of suspicion even when a radiograph appears to be normal with a disproportionately swollen elbow in a child. TRASH lesions include radial head osteochondral fractures, medial condylar fractures in unossified elbow, transphyseal separations of the distal humerus, monteggia lesions, entrapped incarcerated medial epicondylar fractures, capitellar shear fractures, lateral condylar fractures extending to the cartilage. This article attempts to review in brief, the approach to early diagnosis and management with literature review and case examples.

Introduction

The elbow of a child is made predominantly of cartilage. Secondary ossification centers appear around the ages as depicted in the image below (Fig. 1). Fractures around the elbow constitute 12% of all paediatric fractures [1]. Most common fractures around elbow in a child less than 10 years are supracondylar fractures followed by fractures of the lateral condyle of humerus [2]. A few uncommon injuries that occur through the unossified part of the elbow prior to the appearance of secondary ossification centers, are relatively difficult to diagnose and are not routinely appreciated on a radiograph. These lesions if undetected or detected late may lead to serious long-term complications.

Fig. 1.

Typical age of appearance of secondary ossification centers around elbow

Waters et al. described these frequently missed injuries around the elbow as TRASH (The Radiographic Appearance Seemed Harmless) lesions in 2010 [3]. They present with a painful swollen elbow with an otherwise normal-looking radiograph. A high index of suspicion, early further imaging like ultrasound, arthrogram, MRI helps give us a prompt diagnosis and a chance for early surgical intervention.

TRASH lesions include the following osteochondral fractures.

• Radial head osteochondral fractures with progressive radiocapitellar dislocation.

• Unossified medial condylar fractures.

• Transphyseal separations of the distal humerus.

• Monteggia lesions.

• Entrapped incarcerated medial epicondylar fractures following dislocation of elbow.

• Capitellar shear fractures.

• Lateral condylar osteochondral shear fractures.

In this article, a brief overview of the individual TRASH lesions, with tips and potential pitfalls in diagnosis and management protocol are addressed.

History, Examination and Management of Individual Lesions

Radial Head Osteochondral Fractures with Progressive Radiocapitellar Dislocation

Fractures of the radial head in a child are infrequent due to its cartilaginous nature and resiliency. Intra-articular radial head fractures are seldom noticed in comparison to radial neck fractures and are associated with a poor prognosis [4, 5]. Most of the intra-articular fractures can be managed successfully conservatively. A subset of intraarticular fractures tends to subluxate posteriorly leading to progressive radiocapitellar dislocation if not detected early (Fig. 2) [6]. This can be graded using the Bell et al. criteria [7]. Type I lesion is a posterior radiocapitellar subluxation, and a type II lesion is a posterior dislocation of the radial head with minimal displacement. A type III lesion is a posterior dislocation of the radial head which is proximally migrated crossing the midline of the humerus. Delay in diagnosis poses a risk of complications such as delayed radial head subluxation, radiocapitellar arthritis, osteochondral defect, fibrous non-union, full-thickness chondral defect, radial head enlargement, and premature physeal arrest leading to relative shortening of the radius [5]. If presented acutely with subluxation or dislocation, it may warrant open reduction and internal fixation with annular ligament repair, if required. If the patient presents late with complications, salvage procedures like radial head excision, cheilectomy, anterior capsular release might be needed to improve elbow function.

Fig. 2.

9-year-old boy, aspiring boxer with a history of fall presented at 8 weeks following injury with stiffness and swollen elbow. a Radiograph showing Mclaughlins line passing posterior to capitellum suggestive of radiocapitellar subluxation. b CT scan shows osteochondral fracture of radial head with posterior subluxation. c Intraoperative picture showing intraarticluar radial head fracture following fixation with Herbert screw. d 12 week postoperative radiograph showing good union

Unossified Medial Condylar Fractures

Medial humeral condylar fractures are uncommon injuries, comprising 1–2% of all pediatric elbow fractures [8, 9]. Medial condylar secondary ossification center appears around 8 to 9 years. Medial humeral condylar fractures prior to this age may be mistaken for medial epicondylar avulsion fractures if a metaphyseal wafer of bone attached to fractured medial condyle is confused with the epicondyle. The distinction between fractures limited to the epicondyle and other more extensive fractures involving the medial condyle is critical as the latter are unstable and must be treated promptly with surgical intervention to prevent instability, deformity and restriction of range of movements.

Owing to the location of medial epicondyle outside the joint capsule, fractures limited to this center usually do not produce joint capsular distention and consequently will not produce a positive fat pad sign [10]. Pain, swelling, ecchymosis over the medial side of the elbow, and radiographic clues like soft tissue shadow confined to the medial aspect of the elbow with a metaphyseal wafer of bone and a positive fat pad sign should arise suspicion of medial condylar fracture and should be evaluated with further imaging techniques like an ultrasound, arthrogram or an MRI. If C-sign (sickle-shaped malrotated small metaphyseal fragment) (Fig. 3a) appears on the medial side of the elbow in a child younger than 8 years, a medial condyle fracture must be ruled out [11].

Fig. 3.

6-year-old child presented with swollen elbow following fall on outstretched hand. a, b Radiograph reveals a small flake of bone with C- sign (arrow mark) medially suggestive of medial condyle fracture. He was managed conservatively initially. c 6 months later child presented with cubitus varus deformity with nonunion. d Intraoperative image following open reduction and fixation with cancellous screw and a k wire

The development of non-union, cubitus varus deformity occurs as a result of failure in identifying these fractures [8, 11]. Patients in whom diagnosis was made early and received prompt surgical intervention had better functional outcomes. Risk of avascular necrosis of trochlea and fish tail deformity has been described following open reduction and posterior dissection of the medial condyle which may compromise the blood supply of the trochlea [11].

Transphyseal Separation of Distal Humerus

Transphyseal fractures of the lower end humerus are rare injuries. They occur typically in children under 3 years of age and are often mistaken for elbow dislocations. However, elbow dislocations are rarely seen in children younger than 3 years, because the cartilaginous physis is weaker compared to bone ligament junction in young, which makes them susceptible to transphyseal separations [12]. The most common mode of injury in a newborn is during obstetrical maneuvers used to deliver the baby especially with shoulder dystocia or with excessive traction during the caesarian section [13, 14]. In toddlers, common mechanisms are fall on an outstretched hand and non-accidental trauma due to child abuse. An injured child will have diminished spontaneous movements of the affected extremity, swelling, and ecchymosis around the elbow. Many of these injuries are missed by primary care physician discounting them as normal or elbow dislocations.

The key to the diagnosis of transphyseal fractures on plain radiography is recognizing that a line drawn along the shaft of ulna is not aligned with the shaft of humerus on an AP view. The forearm is displaced posteromedially, whereas in most elbow dislocations, it is displaced posterolaterally (Fig. 4). If the secondary ossification center of capitellum has appeared, the radiocapitellar alignment is maintained (as opposed to elbow dislocation) and is displaced posteromedially with the entire forearm. A positive posterior fat-pad sign is noted in these cases which is suggestive of an occult fracture.

Fig. 4.

a Neonate presented with swelling over elbow and decreased movements in the upperlimb following delivery. b Radiograph shows posteromedial displacement of entire forearm suggestive of transphyseal fracture. c Arthrogram delineates the fracture well. d Intraoperative c-arm picture showing fixation with k wires

Children older than 3 years typically have Salter-Harris type II injuries with a metaphyseal Thurston-Holland fragment attached to the distal fragment, and younger children have Salter-Harris type I injuries with pure transphyseal fractures [15]. When in the dilemma of the diagnosis, Ultrasound, MRI or arthrogram can be done. The majority of the transphyseal fractures of the distal humerus can be treated successfully with closed reduction and percutaneous k-wire fixation, with the aid of an arthrogram. Acceptable criteria following closed reduction are similar to those of the supracondylar fractures- the anterior humeral line should pass through the middle third of the capitellum; varus alignment, and malrotation should be avoided. The most common complication of the transphyseal separations is cubitus varus deformity [16]. Other known complications are osteonecrosis, growth disturbance, compartment syndrome, decreased range of movements, and neurovascular injuries. It is recommended to avoid late manipulation (after 5–7 days) due to the danger of avascular necrosis, physeal injuries, and growth disturbances, and deal with residual deformity if any, at a later date.

Hence, particular attention has to be paid in children younger than 3 years with elbow trauma for prompt recognition and appropriate treatment, often with closed reduction and percutaneous k wire fixation with the aid of an arthrogram results in excellent outcome.

Missed Monteggia fractures

Radial head dislocation in combination with the plastic deformity of the ulna is a subgroup of Monteggia fractures [17]. All isolated traumatic radial head dislocations noted in children are Letts type A Monteggia variants [18, 19]. Variation in radiocapitellar line and a positive ulnar bow sign on a lateral radiograph are diagnostic of monteggia fracture with plastic deformation of the ulna and radial head dislocation. The radiocapitellar line helps demonstrate radial head dislocation, where in a line drawn along the long axis of the radial shaft fails to pass through the middle third of the capitellum in any degree of elbow flexion (Fig. 5a, b, c). The ulnar bow line normally is a straight line from the level of the olecranon to the distal ulnar metaphysis when drawn on the true lateral view of plain radiograph along the dorsal border of the ulna. This shows concavity with > 1 mm displacement from the ulnar shaft at the maximal ulnar bow in cases with plastic deformity of the ulna and radial head dislocation (Fig. 5a, b) [18]. Proper lateral view of elbow is needed to interpret these lines accurately.

Fig. 5.

a, b 7-year-old girl with injury to wrist and forearm following a fall. Distal radius and ulna with proximal ulna fracture were treated with closed reduction and above elbow cast. But Monteggia lesion was missed during the initial treatment. Note Mc Lauglins line (solid line) passing anterior to capitellum and Ulnar bow sign (dotted line) is positive. c Child presented 5 months following injury with block in flexion, elbow pain and restricted prono-supination. d Ulnar dorsal open wedge osteotomy along with open radial head relocation was performed. e Radiograph shows good healing of osteotomy site and well reduced radial head (restored Radiocapitellar line)

When diagnosed early, closed reduction by manipulation of the radial head and correction of ulna bow is a viable option. If radial head reduction is not stable, it may lead to a painful deformed elbow with restricted movements. When there is no ulnar bowing, closed reduction of the radial head alone is sufficient. However, if ulnar bowing deformity is left uncorrected, congruent radial head reduction is likely to fail with disappointing functional results. A dorsal open wedge (flexion) osteotomy of the ulna, and fixation with a contoured plate, combined with open reduction of radial head and a short period of immobilisation is a safe and dependable method of treating the delayed presenting monteggia lesions (Fig. 5d, e). Annular ligament reconstruction is not always mandatory. The annular ligament is frequently flipped over the radial head, with the formation of meniscoid scar tissue thereby preventing reduction, which ultimately demands resection.

Good radiographs, ability to recognize the ulnar bow sign, and altered radiocapitellar line in all children presenting with a painful swollen elbow and restricted movements will minimize the chances of a missed diagnosis. Prompt treatment to reduce the plastic deformation of ulna and dislocated radial head will give the best possible outcome. In late cases, corrective osteotomy of the ulna with radial head open reduction with reconstruction of annular ligament when required gives functionally acceptable results.

Entrapped Incarcerated Medial Epicondyle Fractures Following Elbow Dislocation

Medial epicondyle ossification center appears around 5–7 years and is last to fuse to the distal humerus, at around 15–17 years [20]. The peak age of incidence of medial epicondylar fractures is around 11–12 years [21]. It occurs in about 30 to 55% of elbow dislocations in children and adolescents [21]. Medial epicondyle fracture has been classified into 4 types by Papavasiliou (Fig. 6) [22]. Entrapped medial epicondyle fractures present with pain and swelling accompanied by loss in motion especially extension of the elbow. Elbow stability has to be assessed in all cases of medial epicondyle fractures, which is best seen by gravity-assisted valgus stress test. This is done with the patient lying supine, abducting and externally rotating the shoulder to 90°, flexing the elbow to 15°, and checking for medial opening at the elbow under gravity. The ulnar nerve may be involved in displaced medial epicondyle fractures given its proximity to the epicondyle. Internal oblique and axial views of the elbow are preferred as they better delineate the fracture displacement.

Fig. 6.

Papavasiliou classification of medial epicondyle fractures. Type I is minimally displaced avulsion, type II is avulsed, non-entrapped at the level of joint, type III with an avulsed fragment incarcerated in the joint, type IV with a fragment in the joint with dislocated elbow

Medial epicondyle incarceration within the joint, marked elbow instability, ulnar nerve symptoms, and compound fractures are absolute indications for surgery. It is approached through the medial incision, entrapped epicondyle is released, freshened and fixed with one or two 3.5 mm or 4 mm screws. Kirschner wires are preferred in very young patients (Fig. 7). The ulnar nerve is delineated and protected in all cases and anterior transposition is done in cases with ulnar nerve affection. Screws are positioned above the olecranon fossa and are preferably unicortical to prevent radial nerve injury and stress riser effect that may occur if a bicortical purchase is achieved [23]. High index of suspicion is needed in very young in whom the apophysis is not ossified. Clinical features such as swelling or tenderness on the medial side of the elbow and palpation of the fragment must arise suspicion of this injury. An incarcerated medial epicondylar fragment has to be considered when there is a restriction in elbow extension following an elbow reduction with radiographs showing a small fragment at the level of joint. These injuries warrant additional investigations such as arthrography, sonography, or MRI, and prompt surgical intervention is needed to avoid future complications.

Fig. 7.

a, b 5-Year-old child presented with pain, restricted elbow movements and parasthesias in ulnar nerve distibution following elbow dislocation reduced at other centre, the radiograph shows Papavasiliou type 3 medial epicondylar fracture fragment at joint level indicating incarceration following elbow dislocation. c MRI shows medial epicondylar fragment entrapped with ulnar nerve in the joint. d Exploration revealed ulnar nerve entrapment; e Neurolysis, anterior transposition of ulnar nerve and medial epicondylar fracture fixation were performed. f, g Postoperative radiograph with screw insitu

Capitellar Shear Fractures

Capitellar shear fractures are often seen in adolescents beyond 12 years of age as trauma in younger children usually leads to supracondylar fracture of humerus owing to the cartilaginous composition of capitellum [24]. Radiological diagnosis of capitellar fractures is challenging in children below 10 years of age as it is not completely ossified and fused [25]. These injuries occur following a fall on an outstretched hand, where the radial head exerts a shearing force on the capitellum.

Four types of fractures are described by Bryan- Morrey and McKee (Fig. 8) [26, 27]. Type I or Hahn- Steinthal fragment is where the entire articular part of capitellum is fractured which occasionally includes lateral crista of trochlea. Type II or Kocher-Lorenz fragment is a superficial osteochondral fracture involving only cartilaginous part of the capitellum with a part of subchondral bone attached to it. This type is difficult to diagnose on radiographs and needs advanced imaging like MRI. Type III or Broberg-Morrey/ Grantham fracture is a comminuted/ compression fracture of the capitellum. Type IV fracture, McKee’s modification of type I, is a shear fracture across the capitellum extending medially to include the lateral half of the trochlea. Another type of fracture unique to children called “sleeve fracture”, includes a large fragment of capitellar articular cartilage with subchondral bone, which separates in continuation with metaphysis and physis resembling a sleeve [28, 29]. Treatment includes fixation with headless compression/ bioabsorbable screws aiming at restoring the articular congruity or excising the fragments if they are too small (Fig. 9).

Fig. 8.

Bryan-Morrey classification type I—Large osseous fragment of capitellum, type II—shear fracture of articular cartilage with little/no bone, type III—comminuted fracture of the capitellum, type IV—Mc Kee’s modification—coronal shear involving capitellum and trochlea

Fig. 9.

11-year-old child presented 1 month following injury with persistent pain and restriction of motion in the elbow. a, b Radiograph of the elbow shows shear fracture of the capitellum. c, d CT scan shows displaced type 1 Hahn Steinthal fragment. e Intraoperative picture showing capitellum fracture. f, g Intraoperative X-ray picture after fixation with Herbert screws

Missed capitellar fractures present with loss of flexion–extension movements, crepitation on movement, preserved supination and pronation movements. Diagnosis is made by radiographs in AP, lateral and oblique views. The capitellar subchondral bone and lateral part of trochlea forms a characteristic ‘double arc sign’ on an elbow lateral radiograph, which is typical of Mc Kee’s type IV fracture [30]. Presence of concomitant radial head fractures should be screened for on the radiograph.

When there is a suspicion of capitellum fracture, MRI or arthrogram aids in confirming the diagnosis which if missed and left untreated, may lead to substantial disability in elbow motion and may result in early radio-humeral arthritis.

Lateral Condyle Avulsion Shear Fractures

Fractures of the lateral condyle are the second most common fractures around the elbow in children [31]. As the articular portion of lateral condyle ossifies in late adolescence, fractures extending through this cartilaginous part are not readily visible on radiographs. Hence, complete delineation of lateral humeral condyle fractures cannot be made on a plain radiograph. Minimally displaced fractures pose a problem because of inaccurate diagnosis and subsequent complications. Song’s classification helps define management protocol. Stable fractures are those with intact articular cartilage hinge and unstable ones lack cartilaginous articular continuity. Unstable fractures warrant reduction and fixation with smooth wires to prevent nonunion and subsequent complications. Differentiation of stable from unstable fractures can be done with various studies such as MRI, stress radiography, arthrography, ultrasonography, etc., Most important distinction between stable and unstable fractures can be made by measuring and comparing the fracture gap in anteroposterior and internal oblique views. Proper internal oblique view is obtained with the patient seated, arm extended comfortably, forearm pronated and elbow rotated medially until the anterior surface of the elbow is at a 45° angle to the X-ray beam. If the fracture displacement is more than 2 mm in either anteroposterior or internal oblique view, they are deemed unstable and need closed reduction and k wire fixation [32]. Additionally, arthrogram helps differentiate Song’s stage 1 and 2 from others when the presence of radiopaque contrast within the fracture line indicates disruption of the cartilage hinge (Fig. 10). MRI is also valuable in determining the integrity of the cartilaginous articular hinge, but the need for sedation in children makes it an unattractive option. When conservative management is chosen, it is recommended to procure fresh AP and internal oblique views of the elbow out of cast during the initial weekly follow-ups to look for the late displacement of the fracture and intervene if necessary [33]. Stable fractures (stage 1, 2) need conservative management with a cast. Unstable fractures (stage 3, 4) need traction and varus force followed by direct compression of the distal fragment in anteromedial direction and valgus force in extension to stabilize and k wire fixation. For unstable (stage 5) fractures K-wire assisted joystick reduction may be attempted to reduce the rotated fragment followed by fixation as mentioned above or it can be converted to open reduction if it is unsuccessful [32]. Failure to distinguish between stable and unstable fractures may lead to inadequate treatment and subsequently present with late complications like nonunion, cubitus valgus, tardy ulnar nerve palsy, elbow stiffness, etc.

Fig. 10.

a 4 year old child with lateral condyle fracture AP, lateral and internal oblique views showing fracture gap > 2 mm. b Integrity of articular hinge was examined with an arthrogram which has shown dye leaking through the fracture site indicating disrupted articular hinge and an unstable fracture. c This was managed with closed reduction and percutaneous K wire fixation

Summary

TRASH lesions around the elbow are a collection of osteochondral injuries which if left untreated or inadequately treated result in long-term consequences. Prompt diagnosis needs a high index of suspicion in an elbow swollen out of proportion to a radiograph appearing normal. This group of injuries are displaced and unstable but is seldom seen on a radiograph owing to their cartilaginous nature. These lesions almost always warrant further imaging like Ultrasound or MRI or Arthrogram or CT scan for an accurate diagnosis. The aim should be to achieve anatomical reduction following internal fixation with or without soft tissue repair to have a fully functional elbow and prevent subsequent complications.

Compliance with ethical standards

Conflict of interest

On behalf of all authors, the corresponding author states that there is no conflict of interest.

Ethical Standard Statement

This article does not contain any studies with human or animal subjects performed by the any of the authors.

Informed Consent

For this type of study informed consent is not required.