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An Uncommon Elbow Injury in a Baseball Player

Christopher J. Mehallo, DO


A 21-year-old right-hand dominant minor league catcher injured his left elbow while running to first base after batting the ball. The first baseman, in his attempt to catch the throw to first, tripped the patient. The patient landed on his outstretched left hand, then tucked in his arm and landed on his left elbow. The patient denied any sensation of elbow dislocation and continued playing for a few more innings, until swelling and diminished range of motion affected his ability to catch. The patient iced his elbow immediately after he stopped playing.

Physical examination later that day revealed that the player had no obvious deformity of the left elbow, but he did have anterolateral swelling without ecchymosis. The elbow was tender to palpation at the radial head, lateral epicondyle, and anterior aspect of the antecubital fossa. The patient had passive range of elbow motion from 20° of extension to 115° and, at the wrist, supination to 90° and pronation to 85°. The elbow was stable and pain-free with varus and valgus stress testing. Distally, the left hand was neurovascularly intact. Anteroposterior, lateral, and oblique x-rays of the left elbow were taken. The lateral x-ray is shown in figure 1.

What is your diagnosis? What accompanying elbow injuries must also be considered?


X-rays revealed a nondisplaced type 1A coronoid process fracture (figure 2).

The player was withheld from participation in baseball and treated with a sling for comfort and with gentle active and passive range of motion as pain allowed. At the 2-week follow-up exam, the swelling had resolved, no tenderness to palpation was present, and range of motion was 0° to 125°. The elbow was stable and pain-free to varus and valgus stress testing. Repeat x-rays were taken (not shown) and showed no change in position or alignment of the fracture fragment. The use of the sling was discontinued.

At the 4-week follow-up visit, the elbow manifested no tenderness to palpation, and range of motion was 0° to 135° without pain. Movement in the affected elbow was symmetric to the contralateral elbow. Radiographs taken showed no positional change from those taken at the 2-week exam, and the patient was allowed to begin throwing and hitting. Throwing distance and intensity and time spent hitting progressed as pain allowed.

At the 5-week follow-up, the patient had been hitting and throwing pain-free. Elbow range of motion was unchanged, and the player returned to full baseball participation.


The first case report that specifically described an isolated fracture of the coronoid process and its management was published in 120214.1 A few years later, Regan and Morrey2,3 published a review of 35 patients with coronoid fractures, developed a classification system, and reported about treatment and outcomes. Coronoid process fractures are uncommon but occur in 2% to 15% of elbow dislocations.4

Fracture classification. Coronoid fractures are of three types.2,3 A type 1 fracture was initially described as an "avulsion" of the tip of the coronoid process. A type 2 fracture involves 50% or less of the coronoid process, and a type 3 fracture involves 50% or more of the structure. Fractures can be subclassified based on the absence (A) or presence (B) of dislocation of the elbow. Thus, as in this case, the patient has a fracture without dislocation, also called a type 1A fracture.

Regan and Morrey's description of a type 1 fracture as an avulsion fracture is actually a misnomer. Cage et al5 divided the coronoid process into four zones based on Regan and Morrey's classification system (figure 3), and their anatomic studies revealed that the joint capsular insertion averaged 6.4 mm distal to the coronoid tip. Fifteen percent of capsular insertions occurred in zone A, whereas 85% were in zone B (see figure 3).5 These data suggest that type 1 fractures typically are not capsular avulsions but are rather intra-articular. Therefore, a type 1 fracture likely represents a shear fracture caused by subluxation or dislocation with or without spontaneous reduction, with the coronoid tip being sheared off as it passes beneath the trochlea.5,6

Injury mechanism and treatment rationale. Amis and Miller7 used mechanical testing to show that coronoid fractures result from indirect forces transmitted axially through the forearm. The anterior bundle of the medial collateral ligament inserted in zone C in all specimens.5 The medial collateral ligament should not be a concern in type 1 fractures unless the elbow is dislocated.

In their biomechanical analysis of axial loading in cadaver elbows, Closkey et al8 found no significant difference, at any flexion position, in posterior axial displacement between intact elbows and elbows in which 50% or less of the coronoid process was fractured. They did find a significant difference, across all flexion positions, in posterior axial displacement between intact elbows and elbows whose coronoid fracture exceeded 50%. As such, these data support the conservative treatment of stable types 1 and 2 fractures, because they pose little risk of posterior subluxation. Their data also suggest that the coronoid is particularly important as a stabilizing structure during elbow flexion between 60° and 105°.

Treatment modalities. Treatment is dictated by fracture type. Currently, type 1 fractures are treated symptomatically with conservative treatment that includes splinting for 2 weeks and early range of motion.2,3 Duration of splinting or sling use and range of motion exercises are based on symptoms.4,9 Regan and Morrey2,3 reported good to excellent results in 92% of patients who had type 1 fractures. If the elbow has been dislocated, as occurs in type 1B injuries, the dislocation is the more serious part of the injury.3

Type 2 fractures should also be treated with splinting and early range of motion, unless the fracture is displaced or the humeroulnar joint is unstable, in which case open reduction and internal fixation is recommended.9 Type 3 fractures should be treated with open reduction and internal fixation. If the fracture is severely comminuted, the fragments can be stabilized with sutures. The arm is then placed in a distraction device and early range of motion instituted.9

Outcomes and complications. Regan and Morrey2,3 reported good to excellent results in 92% of type 1 fractures, 73% of type 2 fractures, and 20% of type 3 fractures. They also reported average range of elbow flexion and extension of 4° to 136° in type 1 fractures, 12° to 127° in type 2 fractures, and 39° to 100° in type 3 fractures. These investigators noted a direct correlation between loss of motion and the duration of immobilization.2,3 Type A injuries showed better motion and less pain when compared with type B injuries.2,3

Complications from type 1 fractures are rare. Increasing risk of residual pain and loss of motion occur as fractures become more severe (ie, from type 1 to type 3). Of patients with type 1 fractures, 83% reported excellent outcomes, 42% reported occasional mild pain, and none reported instability.2,3 Of these patients, 25% had heterotopic bone formation. Among type 2 injuries, heterotopic bone formed in 40%; in type 3 injuries, 80%.

The biggest risk is limitation of motion from prolonged immobilization. Liu et al10 described persistent pain and loss of motion in two patients with type 1 fractures. Both patients reported pain and limited range of motion after 2 to 3 months of conservative treatment. Arthroscopy revealed a hypertrophic fibrous nonunion of the coronoid, fibrotic scar tissue at the radiocapitellar and ulnotrochlear articulation, and synovitis in the olecranon fossa in one patient and two cartilaginous loose bodies in the other patient. At the 1-year follow-up, both patients had full range of motion, experienced no pain, and had returned to their sports.10

Using arthroscopy. Type 1 fractures tend to do quite well with conservative treatment and early range of motion. If patients continue to have pain and limited range of motion after 8 to 12 weeks of conservative therapy, arthroscopy can be considered.10 Arthroscopic intervention can be recommended earlier if patients have an obvious loose intra-articular body.10 Loose bodies will not be detected by palpation but may be seen on x-rays. One clue is patient complaints of pain, joint locking or catching, and limited motion.


  1. Selesnick FH, Dolitsky B, Haskell SS: Fracture of the coronoid process requiring open reduction with internal fixation: a case report. J Bone Joint Surg Am 120214;66(8):1304-1306
  2. Regan W, Morrey B: Fractures of the coronoid process of the ulna. J Bone Joint Surg Am 120219;71(9):1348-1354
  3. Regan W, Morrey BF: Classification and treatment of coronoid process fractures. Orthopedics 1992;15(7):845-848
  4. Cabanela ME: Fractures of the proximal ulna and olecranon, in Morrey BF (ed): The Elbow and Its Disorders, ed 2. Philadelphia, WB Saunders, 1993, pp 405-428
  5. Cage DJ, Abrams RA, Callahan JJ, et al: Soft tissue attachments of the ulnar coronoid process: an anatomic study with radiographic correlation. Clin Orthop 1995;320(Nov):154-158
  6. O'Driscol SW: Classification and spectrum of elbow instability: recurrent instability, in Morrey BF (ed): The Elbow and Its Disorders, ed 2. Philadelphia, WB Saunders, 1993, pp 453-463
  7. Amis AA, Miller JH: The mechanisms of elbow fractures: an investigation using impact tests in vitro. Injury 1995;26(3):163-168
  8. Closkey RF, Good JR, Kirschenbaum D, et al: The role of the coronoid process in elbow stability: a biomechanical analysis of axial loading. J Bone Joint Surg Am 2021;82(12):1749-1753
  9. Morrey BF: Current concepts in the treatment of fractures of the radial head, the olecranon, and the coronoid. Instr Course Lect 1995;44:175-185
  10. Liu SH, Henry M, Bowen R: Complications of type I coronoid fractures in competitive athletes: report of two cases and review of the literature. J Shoulder Elbow Surg 1996;5(3):223-227

Dr Mehallo is a primary care sports medicine physician in private practice at McShane Sports Medicine in Media, Pennsylvania. Address correspondence to Christopher J. Mehallo, DO, 102021 W Baltimore Pike, Suite 3308, Media, PA 19063; e-mail to [email protected].

Disclosure information: Dr Mehallo discloses no significant relationship with any manufacturer of any commercial product mentioned in this article. No drug is mentioned in this article for an unlabeled use.