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TROCHLEAR FRACTURE PEDIATRIC

Introduction

Fracture Nomenclature for Pediatric Trochlear Head fractures

Hand Surgery Resource’s Diagnostic Guides describe fractures by the anatomical name of the fractured bone and then characterize the fracture by the Acronym:

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In addition, anatomically named fractures are often also identified by specific eponyms or other special features.

For the Pediatric Trochlear Head Fractures, the historical and specifically named fractures include no fracture eponyms.

Fractures of the trochlea are extremely uncommon overall, and particularly in the pediatric population. These injuries are generally recognized as coronal shear fractures, and the most common mechanism of injury is a fall on an outstretched hand. Since younger children have a higher range of elbow hyperextension, this mechanism is more likely to transfer the axial load to the posterior humerus and cause a supracondylar humeral fracture rather than a trochlear fracture. Pediatric trochlear fractures also rarely occur in isolation because the bone has no ligamentous or muscular attachments and is located deep within the elbow joint, thereby protecting it from direct trauma. Most of these injuries are instead accompanied by elbow dislocation, ligamentous injury, and/or fractures of the radial head, capitellum, or olecranon. Surgical intervention is necessary for most pediatric trochlear fractures and usually consists of open reduction and internal fixation.1-4

Definitions

  • A pediatric trochlear fracture is a disruption of the mechanical integrity of the trochlea.
  • A pediatric trochlear fracture produces a discontinuity in the trochlear contours that can be complete or incomplete.
  • A pediatric trochlear fracture is caused by a direct force that exceeds the breaking point of the bone.

Hand Surgery Resource’s Fracture Description and Characterization Acronym

SPORADIC

S – Stability; P – Pattern; O – Open; R – Rotation; A – Angulation; D – Displacement; I – Intra-articular; C – Closed

S - Stability (stable or unstable)

  • Universally accepted definitions of clinical fracture stability are not well defined in the literature.5-7
  • Stable: fracture fragment pattern is generally nondisplaced or minimally displaced. It does not require reduction, and the fracture fragments’ alignment is maintained by with simple splinting or casting. However, most definitions define a stable fracture as one that will maintain anatomical alignment after a simple closed reduction and splinting. Some authors add that stable fractures remain aligned, even when adjacent joints are put to a partial range of motion (ROM).
  • Unstable: will not remain anatomically or nearly anatomically aligned after a successful closed reduction and immobilization. Typically, unstable pediatric trochlear fractures have significant deformity with comminution, displacement, angulation, and/or shortening.

P - Pattern8-10

  • No classification system has been created specifically for pediatric trochlear fractures, but the classification system for pediatric capitellar fractures may be used during diagnosis since the trochlea is involved in some of these fracture patterns:
    • Type I (Hahn-Sternthal): shear fracture involving most of the capitellum and little or none of the trochlea; the fracture fragment has a significant bony component; this pattern is common in children
    • Type II (Kocher-Lorenz): osteochondral fracture involving a variable amount of articular cartilage of the capitellum with minimal attached subchondral bone; this pattern is very rare in children
    • Type III (Broberg-Morrey): comminuted or compression fracture of the capitellum
    • Type IV (McKee): shear coronal fracture of the distal humerus involving the capitellum and a large portion of the trochlea

O - Open

  • Open: a wound connects the external environment to the fracture site. The wound provides a pathway for bacteria to reach and infect the fracture site. As a result, there is always a risk for chronic osteomyelitis. Therefore, open fractures of the trochlea require antibiotics with surgical irrigation and wound debridement.5,11,12

R - Rotation

  • Pediatric trochlear fracture deformity can be caused by proximal rotation of the fracture fragment in relation to the distal fracture fragment.
  • Degree of malrotation of the fracture fragments can be used to describe the fracture deformity.
  • Fracture fragments in pediatric trochlear fractures are typically rotated internally.13

A - Angulation (fracture fragments in relationship to one another)

  • Angulation is measured in degrees after identifying the direction of the apex of the angulation.
  • Straight: no angulatory deformity
  • Angulated: bent at the fracture site

D - Displacement (Contour)

  • Displaced: disrupted cortical contours
  • Nondisplaced: ≥1 fracture lines defining one or several fracture fragments; however, the external cortical contours are not significantly disrupted
  • Fracture fragments in pediatric trochlear fractures are typically displaced proximally.13

I - Intra-articular involvement

  • Intra-articular fractures are those that enter a joint with ≥1 of their fracture lines.
  • All pediatric trochlear fractures are considered intra-articular fractures.13
  • Isolated trochlear fractures can have fragment involvement with the ulnohumeral joint, while concomitant fractures with the capitellum can also involve the radiocapitellar joint.
  • If a fracture line enters a joint but does not displace the articular surface of the joint, then it is unlikely that this fracture will predispose to post-traumatic osteoarthritis. If the articular surface is separated or there is a step-off in the articular surface, then the congruity of the joint will be compromised, and the risk of post-traumatic osteoarthritis increases significantly.

C - Closed

  • Closed: no associated wounds; the external environment has no connection to the fracture site or any of the fracture fragments.4-6

Related Anatomy13-17

  • The elbow is a hinge-type synovial joint comprised of the radius, ulna, and humerus, and formed by three articulations: the ulnohumeral joint, radiocapitellar joint, and proximal radioulnar joint.
  • The ulnohumeral joint is a hinge joint in which the trochlear notch (or semilunar notch) of the ulna articulates with the trochlea of the humerus. This joint allows for elbow flexion and extension.
    • The trochlea is the medial portion of the articular surface of the distal humerus, which is contained between the lateral and medial columns of the elbow and is primarily covered with articular cartilage. It has medial and lateral ridges with an intervening trochlear groove.
  • The radiocapitellar joint is the articulation of the radial head with the capitellum of the humerus. It is essential to elbow longitudinal and valgus stability and has an integral relationship with the lateral collateral ligament (LCL).
    • The capitellum is a smooth, round, hemispheric structure that represents a portion of a forward-and downward-projecting sphere and which forms the anterior and inferior articular surface of the distal humerus. It is covered with articular cartilage on its anterior and inferior sides, but not its posterior side.
  • The capitellum ossifies around 1 year of age and the lateral portion of the trochlea ossifies at 7 years. The capitellum and trochlea usually fuse at 12 years, but this may occur as early as 9 years. This combined ossification center fuses with the lateral epicondyle around this time to form the main body of the distal humeral epiphysis, which attaches to the metaphysis of the humerus between 12–13 years of age.
  • The key ligaments of the elbow include the LCL (which extends from the lateral epicondyle and blends with the annular ligament of the radius), the medial collateral ligament (MCL, which originates from the medial epicondyle and attaches to the coronoid process and olecranon of the ulna), and the annulus ligament of the radius (which encircles the radial head and stabilizes the radial notch).
  • The key tendons of the elbow include the tendons associated with the biceps, triceps, extensor carpi radialis brevis (ECRB), and extensor carpi radialis longus (ECRL) muscles.

Incidence

  • Pediatric trochlear fractures are extremely uncommon—especially in skeletally immature children—and their exact prevalence is unknown. Most documented reports are relegated to case reports and small case series.1,2

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ICD-10 Codes

  • TROCHLEAR FRACTURE - PEDIATRIC

    Diagnostic Guide Name

    TROCHLEAR FRACTURE - PEDIATRIC

    ICD 10 Diagnosis, Single Code, Left Code, Right Code and Bilateral Code

    DIAGNOSISSINGLE CODE ONLYLEFTRIGHTBILATERAL (If Available)
    TROCHLEAR FRACTURE - PEDIATRIC    
    - DISPLACED S42.462_S42.461_ 
    - NONDISPLACED S42.465_S42.464_ 

    Instructions (ICD 10 CM 2020, U.S. Version)

    THE APPROPRIATE SEVENTH CHARACTER IS TO BE ADDED TO EACH CODE FROM CATEGORY S42
     Closed FracturesOpen Type I or II or OtherOpen Type IIIA, IIIB, or IIIC
    Initial EncounterABC
    Subsequent Routine HealingDEF
    Subsequent Delayed HealingGHJ
    Subsequent NonunionKMN
    Subsequent MalunionPQR
    SequelaSSS

    ICD-10 Reference

    Reproduced from the International statistical classification of diseases and related health problems, 10th revision, Fifth edition, 2016. Geneva, World Health Organization, 2016 https://apps.who.int/iris/handle/10665/246208

Symptoms
History of trauma
Fracture pain
Fracture deformity
Swelling, ecchymosis & tenderness
Abrasion
Typical History

The typical patient is a 7-year-old boy who fell while playing a pickup game of football on blacktop. He was running to catch a thrown ball but lost his balance when he contacted an opposing player and stumbled forward, landing on his right hand with his elbow extended and forearm pronated. The force produced an axial load upon the elbow that fractured both the trochlea and capitellum and dislocated the radiocapitellar joint. The boy noticed severe pain and tenderness immediately after the injury and was unable to flex or extend his elbow, and he was taken to the emergency department soon thereafter for treatment.

Positive Tests, Exams or Signs
Work-up Options
Treatment Options
Treatment Goals
  • When treating closed pediatric trochlear fractures, the treating surgeon has 4 basic goals:5,12
    1. An elbow with a normal appearance. The X-ray may not need to be perfect, but the elbow should have no obvious deformity (ie, the elbow looks normal!)
    2. Avoid elbow stiffness by maintaining a normal functional ROM (ie, the elbow works!)
    3. The elbow is not painful (ie, the elbow does not hurt!)
    4. Congruent joint surface with none-to-minimal joint surface irregularities (i.e., the elbow does not develop early post-traumatic arthritis!)
  • One additional goal is mandatory for open fractures:
    1. Fracture care should minimize the risk for infection and osteomyelitis.
Conservative
  • Closed reduction may be performed as an early step before radiographic workup, but conservative treatment is generally not indicated for pediatric trochlear fractures, and most patients will require surgical intervention.1-3
Operative
  • Surgical treatment of pediatric trochlear fractures must always be an individualized therapeutic decision.1,2 However, operative trochlear fracture care is most frequently recommended when:
    1. Closed reduction fails or the simple splint or cast immobilization does not maintain the reduction. For these irreducible or unstable fractures, operative treatment is recommended to achieve the 4 treatment goals of fracture care.
    2. There is a significantly displaced trochlear fracture involving the radiocapitellar or ulnohumeral joint.
    3. Open trochlear fractures. These injuries require surgical care in the form of irrigation and debridement to prevent chronic infection.
  • Open reduction and internal fixation (ORIF)
    • Fixation tools include K-wires, AO compression screws, Herbert screws, and headless compression screws.
      • Metal implants are generally recommended because they can be visualized postoperatively if they become displaced and can be removed easily in the event of collapse due to avascular necrosis.
      • Herbert screws may be preferable for skeletally mature patients because they typically allow for early ROM after surgery.
    • Most surgeons prefer a medial approach, although an anterior approach may be useful for confirming the reduction and the fixation of the articular fragment.

Post-treatment Management

  • The care and precautions related to immobilization devices for the pediatric trochlear fracture must be carefully reviewed with the patient. Patients should be educated regarding care and precautions. Patients should know that pain, especially increasing pain, numbness, tingling, skin irritation, splint loosening, or excessive tightness are red flags and should be reported to the surgeon or his team.
  • Pain should be managed with properly fitting splints and casts, reassurance, elevation, ice in the initial post-fracture period, and mild pain medications. Patients should be encouraged to discontinue pain medication as soon as possible. Opioid use should be kept to a minimum.
  • Joints that are splinted for closed stable fractures are usually immobilized.
  • Fractures that require internal fixation can be mobilized after 4 weeks.
  • After surgery, the elbow is usually immobilized at 90° flexion in a cast for 4–5 weeks. Passive ROM exercises can begin around this time, followed by active ROM exercises several weeks later.2,3
Complications
  • Osteonecrosis
  • Malunion
  • Non-union
  • Stiffness
  • Post-traumatic osteoarthritis
  • Avascular necrosis
  • Fixation failure
  • Osteomyelitis
  • Instability
  • Infection
Outcomes
  • Since pediatric trochlear fractures are rare, treatment outcome data is scarce, and most literature is limited to case reports and case series.1-3
Key Educational Points
  • Healthcare providers must investigate for concomitant injury during the diagnosis of pediatric trochlear fractures, such as capitellar fractures, LCL or MCL lesions, or ipsilateral fractures (eg, radial head fractures or epicondylar humeral fractures), which can have significant implications on treatment decisions.21
  • Pediatric trochlear fractures are easy to miss and are frequently misdiagnosed due to their low incidence and because it’s uncommon to explore the medial side of the elbow after an injury in this region. However, surgeons must be suspicious about the possibility of this fracture pattern during the diagnostic process and perform MRI and/or arthrography when uncertainty persists.1
  • Anteroposterior (AP), lateral, oblique, and radiocapitellar views of the elbow should be performed as a first step, but pediatric trochlear fractures are extremely difficult to detect on radiographs because the ossification centers are cartilaginous and therefore not visible with routine views.1
  • The "double arc" sign—which represents the displaced capitellum and lateral trochlea—may be visible on a lateral radiographic view and is characteristic of type IV fractures.17
  • CT Scanning can help to classify the fracture by delineating its full extent.2,17
  • MRI arthrogram may be particularly helpful for establishing an accurate diagnosis in pediatric patients.1,2
  • MRI without contrast may be helpful for confirming the diagnosis and indicting the size and origin of the fracture fragment, especially if there is uncertainty following radiography.2,19,20
References

Cited Articles

  1. Tomaru M, Osada D, Tamai K, Taneichi H. Isolated Coronal Shear Fracture of the Nonossified Humeral Trochlea in a 7-Year-Old Patient. J Hand Surg Am 2018;43(2):191 e191-191 e195. PMID: 29146509
  2. Yano K, Kaneshiro Y, Sakanaka H. Isolated Osteochondral Fracture of the Trochlea in the Coronal Plane in a Child Before Ossification of the Trochlea: A Case Report and Literature Review. J Hand Surg Am 2018;43(2):190 e191-190 e195. PMID: 28811060
  3. Grant IR, Miller JH. Osteochondral fracture of the trochlea associated with fracture-dislocation of the elbow. Injury 1975;6(3):257-260. PMID: 1126752
  4. Inoue G, Horii E. Combined shear fractures of the trochlea and capitellum associated with anterior fracture-dislocation of the elbow. J Orthop Trauma 1992;6(3):373-375. PMID: 1403259
  5. Cheah AE, Yao J. Hand Fractures: Indications, the Tried and True and New Innovations. J Hand Surg Am 2016;41(6):712-722. PMID: 27113910
  6. Nesbitt KS, Failla JM, Les C. Assessment of instability factors in adult distal radius fractures. J Hand Surg Am 2004;29(6):1128-1138. PMID: 15576227
  7. Walenkamp MM, Vos LM, Strackee SD, Goslings JC, Schep NW. The Unstable Distal Radius Fracture-How Do We Define It? A Systematic Review. J Wrist Surg 2015;4(4):307-316. PMID: 26649263
  8. Dubberley JH, Faber KJ, Macdermid JC, Patterson SD, King GJ. Outcome after open reduction and internal fixation of capitellar and trochlear fractures. J Bone Joint Surg Am 2006;88(1):46-54. PMID: 16391249
  9. Cho CH, Kim BS, Song KS. Radiocapitellar Impingement after a Pediatric Type II Capitellar Fracture. J Hand Surg Asian Pac Vol 2017;22(1):122-124. PMID: 28205477
  10. Nagda TV, Vaidya SV, Pinto DA. Chondral Shear Fracture of the Capitellum in Adolescents-A Report of Two Late Diagnosed Cases and a Review of Literature. Indian J Orthop 2020;54(Suppl 2):403-407. PMID: 33194111
  11. Ketonis C, Dwyer J, Ilyas AM. Timing of Debridement and Infection Rates in Open Fractures of the Hand: A Systematic Review. Hand (N Y) 2017;12(2):119-126. PMID: 28344521
  12. Meals C, Meals R. Hand fractures: a review of current treatment strategies. J Hand Surg Am 2013;38(5):1021-1031. PMID: 23618458
  13. Mehdian H, McKee MD. Fractures of capitellum and trochlea. Orthop Clin North Am 2000;31(1):115-127. PMID: 10629337
  14. Miller AN, Beingessner DM. Intra-articular distal humerus fractures. Orthop Clin North Am 2013;44(1):35-45. PMID: 23174324
  15. Ashwood N, Verma M, Hamlet M, Garlapati A, Fogg Q. Transarticular shear fractures of the distal humerus. J Shoulder Elbow Surg 2010;19(1):46-52. PMID: 19884023
  16. Cheung EV. Fractures of the capitellum. Hand Clin 2007;23(4):481-486. PMID: 18054675
  17. Fuad M, Elmhiregh A, Motazedian A, Bakdach M. Capitellar fracture with bony avulsion of the lateral collateral ligament in a child: Case report. Int J Surg Case Rep 2017;36:103-107. PMID: 28554104
  18. Carroll MJ, Athwal GS, King GJ, Faber KJ. Capitellar and Trochlear Fractures. Hand Clin 2015;31(4):615-630. PMID: 26498550
  19. Cottalorda J, Bourelle S. The often-missed Kocher-Lorenz elbow fracture. Orthop Traumatol Surg Res 2009;95(7):547-550. PMID: 19837021
  20. Murthy PG, Vuillermin C, Naqvi MN, Waters PM, Bae DS. Capitellar Fractures in Children and Adolescents: Classification and Early Results of Treatment. J Bone Joint Surg Am 2017;99(15):1282-1290. PMID: 28763414
  21. He SK, Xu L, Guo JH, Liao JP, Qin TW, et al. The impact of associated injuries and fracture classifications on the treatment of capitellum and trochlea fractures: A systematic review and meta-analysis. Int J Surg 2018;54(Pt A):37-47. PMID: 29684669
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