Managing Fractures of the Humeral Trochlea

The Problem

The humeral trochlea is an important articular surface of the elbow that is injured frequently in falls onto the upper extremity. Isolated trochlea fractures are rare but are frequently encountered in complete articular fractures of the distal humerus involving both the trochlea and capitellum. The trochlea forms the articular surface of the medial column of the elbow and is responsible for allowing ulnohumeral flexion and extension. Fractures of the humeral trochlea can result in elbow stiffness, instability, and post-traumatic arthritis. In general, partial articular fractures of the humeral trochlea are more easily managed than complete articular fractures involving the capitellum. In either case, restoration of the normal trochlea anatomy is paramount in obtaining the best functional result.

Clinical Presentation

Patients with humeral trochlea fractures usually present with acute onset elbow pain after a fall onto the affected elbow. Given the subcutaneous nature of the distal humerus, open fractures are not uncommon and are usually a result of the proximal humeral shaft fracture spike exiting through the posterior elbow. Partial articular fractures involving only the humeral trochlea can present with isolated medial-sided elbow pain, however complete articular fractures present with diffuse elbow pain. Elbow swelling secondary to hemarthrosis is common. Patients will be unable to range the elbow through the flexion-extension arc of motion secondary to involvement of the ulnohumeral articulation. Paresthesias in the ulnar nerve distribution may be present if the trochlea is displaced medially and/or posteriorly and compressing the cubital tunnel.

Diagnostic Workup

Classic physical exam findings

Diffuse elbow joint swelling secondary to hemarthrosis.
Painful elbow range-of-motion through the flexion-extension arc.
Varus elbow instability in extension.
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Posterior wound if open fracture.

Diagnostic tests

Standard trauma views of the elbow include plain X-ray of the elbow including anteroposterior (AP), lateral, and oblique views.
If fracture is present, obtain traction AP view. Ligamentotaxis will align the fracture fragments and allow for easier interpretation of articular fragments.
Computed tomography (CT) is indicated if there is difficulty in interpreting the extent of articular involvement on standard plain X-rays.

Imaging findings

Extra articular fracture with simple fracture pattern: the trochlea is fractured and is a single piece.
Partial articular fracture with complex fracture pattern: the trochlea is fractured and is multifragmentary; the capitellum is fractured and may be displaced.
Complete articular fracture with simple or complex fracture pattern of the trochlea: The trochlea and capitellum are fractured and both are dissociated from the humeral shaft.

Non–Operative Management

Indications

<2 mm articular surface displacement.
Patients in whom surgery is contraindicated (too sick, i.e. risks of surgery outweigh the benefits).

Treatment

Long arm cast for 12 weeks to ensure there is no displacement of the articular surface.
Elbow stiffness is expected after this type of treatment, therefore, most fractures involving the trochlea should undergo operative fixation to allow early range of motion.

Indications for Surgery

≥ 2 mm articular surface displacement.
Contra-indications to casting (sensory nerve deficit involving the arm such that the cast can cause skin irritation that the patient cannot feel).

Surgical Technique

Necessary Equipment/Instrumentation

Large or mini C-arm (fluoroscopic imaging)
Small fragment set
Mini fragment set
Elbow specific plates: precontoured medial column plate
Drill
Pointed bone reduction clamps
1.6 mm K-wires
18-gauge stainless steel wire
18” sterile tourniquet
Narrow blade microsagittal saw
1/2” osteotome

Patient Set–up

Lateral decubitus position with injured arm over bolster. Arm bolster should rest on distal 1/3 of humeral shaft so as to not get in the way of C-arm imaging.
Beanbag to maintain lateral decubitus position.
Axillary roll (rolled sheets).
Large or mini C-arm positioned at head of bed and parallel to bed. C-arm can swing from AP to lateral of elbow without moving elbow.
Entire arm draped free to allow for placement of sterile tourniquet around proximal 1/3 of humerus.

Step–by–Step Description of Procedure

Posterior midline skin incision extending proximally ~10 cm from the trochlea articular surface and extending distally ~3 cm from the olecranon tip. If an olecranon osteotomy is performed, the distal limb of this incision can be extended as needed.
Elevate medial and lateral subcutaneous skin flaps. This will expose the underlying triceps.
Dissect and free the ulnar nerve from the cubital tunnel medially (distal extent of ulnar nerve exposure is to the motor branch of the flexor carpi ulnaris muscle).
See below for medial paratricipital approach versus olecranon osteotomy.
After final fixation, ulnar nerve transposition is not performed and the nerve is allowed to rest in-situ in the cubital tunnel.

Partial Articular Fracture with a Simple Fracture of the Trochlea or Complete Articular Fractures with a Simple Fracture of the Trochlea

A medial paratricipital approach is sufficient to expose, reduce, and fix the trochlea. (a lateral paratricipital approach is used to expose the capitellum in the case of complete articular fractures).
Exposure of the medial aspect of the distal humerus involves exposure of the medial column of the humerus using the interval between the medial head of the triceps and the flexor-pronator mass originating from the medial aspect of the distal humerus. Exposure of the medial epicondyle is necessary if a precontoured medial elbow plate is used to secure the fractured trochlea to the intact humeral shaft.
Dissection around the medial condyle involves partial elevation of the origin of the flexor pronator mass from the medial epicondyle (complete detachment is not necessary; only elevate enough flexor-pronator mass to allow the plate to sit on bone).
Care should be taken to avoid dissection of the anterior band of the medial collateral ligament of the elbow as this is an important stabilizer of the elbow. Therefore, keep dissection anterior to this structure.
Independent screw fixation with 2.7 mm cortical screws can be used to secure the trochlea to the capitellum using either a lag by technique method or using partially threaded screws.
If additional fixation is necessary, a precontoured plate can be used to secure the trochlea to the humeral shaft.

Partial Articular Fractures and Complete Articular Fractures with a Complex Fracture of the Trochlea

An olecranon osteotomy is performed to allow for complete visualization of the trochlea in the setting of complex fracture patterns.
Dissection is carried between the extensor carpi ulnaris/anconeus laterally and the flexor carpi ulnaris medially to expose the olecranon.
Two small Hohmann retractors are placed into the ulno-humeral joint at the level of the articular surface “bare area” (area of olecranon void of articular cartilage) to protect the underlying trochlear cartilage.
A chevron osteotomy (apex pointing distal) is performed using a narrow-blade sagittal saw aimed towards the bare area and only to the level of the subchondral bone of the olecranon. Completion of the osteotomy is performed with a 1/2” flat osteotome. The olecranon and attached triceps is then flipped proximally to expose the underlying trochlea fracture.
Identify all fracture fragments and clear any interposed clot with irrigation to fully visualize the fracture edges.
Provisional reduction of the trochlea to the intact capitellum (partial articular fractures) and/or intact humeral shaft (complete articular fractures) is performed with small pointed bone reduction clamps and 1.6 mm K-wires
Independent screw fixation with a 2.7 mm or 2.0 mm cortical screw can be used to fix trochlea fragments. If coronal fragments are present, screws that are placed from posterior to anterior through the articular surface should be buried beneath the articular surface. Lateral fluoroscopic views should be obtained to ensure the screws do not penetrate the joint anteriorly.
If additional fixation is necessary, a precontoured plate can be used to secure the trochlea to the humeral shaft.
Olecranon osteotomy is fixed using a figure-of-eight tension band construct using 2 1.6 mm K-wires and 18-gauge wire.

Pearls and Pitfalls of Technique

Patient set–up

Prior to prepping and draping the arm, ensure that adequate fluoroscopic images can be obtained (i.e. the arm bolster is not precluding adequate visualization of the articular surface).
Ideally, the elbow does not have to be manipulated or moved to obtain AP or lateral X-rays (other than extending the flexed forearm to obtain the AP X-ray).
Prep the entire arm to allow for sterile tourniquet placement in the event that intra-operative bleeding is obscuring adequate visualization of the articular surface.

Procedure

Apex distal chevron osteotomy will allow for increased visualization of the trochlea articular surface.
Avoid dissection of the anterior band of the medial collateral ligament. If the anterior band of the medial collateral ligament is cut, then it should be repaired by either tying it down through drill-holes through the medial epicondyle or tying it down with suture anchors placed in the medial epicondyle.
Continued elbow instability after final fixation of the trochlea fracture indicates that there is compromise of other dynamic and/or static stabilizers of the elbow. Possible sources of continued instability include: coranoid fracture, medial collateral ligament incompetency (rupture or iatrogenic injury), and lateral collateral ligament rupture. Primary repair of the coranoid fracture or ligaments can be performed through the posterior approach. If there is continued elbow instability, then a hinged elbow fixator should be applied to maintain congruency of the ulnohumeral joint through the flexion-extension arc of motion.

Potential Complications

Complications of operative fixation of humeral trochlea fractures include:

Ulnar nerve neuropraxia (from prolonged intra-operative retraction of the nerve).
Post-traumatic arthritis (from damage to articular surface at the time of injury or from malreduction of the articular surface).
Elbow instability (resulting from failure to recognize and repair injuries to other dynamic or static stabilizers of the elbow).
Infection (deep or superficial).
Elbow stiffness.
Malunion.
Nonunion.

Post–operative Rehabilitation

Post-operative rehabilitation after operative fixation of humeral trochlea fracture is required to achieve maximum elbow range-of-motion given the predilection for periarticular fractures about the elbow to cause elbow stiffness. The following guidelines will optimize fracture healing while achieving early, active elbow range-of-motion.

Weight–bearing Status

Non-weight-bearing (no impact loading, no lifting objects >2 lbs) for 12 weeks.

Immobilization

Long-arm splint in 60-70 flexion immediately post-operatively for 2-3 days for patient comfort. Then remove splint and place into sling for comfort.
In cases in which there is tenuous fixation of the trochlea fragment and high concern for fracture displacement, an unlocked hinged elbow brace can be used to prevent varus forces across the elbow. Continue elbow brace for 6-8 weeks.

Timepoints for advancement of activities

0-6 weeks: Active and active-assist range elbow range-of-motion (flexion/extension) as tolerated. Active and active-assist forearm pronation/supination. Active and passive finger/wrist/shoulder range-of-motion. Start gentle passive range-of-motion as tolerated at the elbow (flexion/extension) and forearm (pronation/supination).
6-12 weeks: Continue elbow range-of-motion exercises. Start muscle strengthening against resistance including biceps/triceps and forearm pronators/supinators.
12 weeks – onwards: Continue elbow range-of-motion, continue muscle strengthening against resistance, start weight-bearing as tolerated (including elbow loading and lifting heavy objects).

Outcomes/Evidence in the Literature

Sen, RK, Tripahty, SK, Goyal, T, Aggarwal, S. “Coronal shear fracture of the humeral trochlea”. J Orthop Surg (Hong Kong). vol. 21. 2013. pp. 82-6. (Case series of 5 patients with coronal shear fractures of the trochlea treated with open reduction and screw fixation or Kirschner wire fixation only. At a mean follow-up of 2.7 years, the mean arc of flexion-extension was 101 degrees and the mean arc of pronation-supination was 130 degrees. Small fractures of the trochlea not amenable to screw fixation can be fixed with Kirschner wires.)

Bilsel, K, Atalar, AC, Erdil, M. “Coronal plane fractures of the distal humerus involving the capitellum and trochlea treated with open reduction internal fixation”. Arch Orthop Trauma Surg. vol. 133. 2013. pp. 797-804. (Case series of 18 patients with coronal plane fractures of either the capitellum and/or trochlea treated with cannulated screw fixation. Mean follow-up was 43.6 months. The mean elbow extension-flexion was 8.9 degrees to 132.8 degrees. Open reduction and internal fixation with cannulated screws provides adequate fixation of coronal plate fractures involving the capitellum and/or trochlea and results in acceptable intermediate-term elbow range-of-motion.)

Wiggers, JK, Brouwer, KM, Helmerhorst, GT, Ring, D. “Predictors of diagnosis of ulnar neuropathy after surgically treated distal humerus fractures”. J Hand Surg Am. vol. 37. 2012. pp. 1168-72. (The authors evaluated for predictors of ulnar nerve neuropathy after operative fixation of distal humerus fractures. Of 107 patients who underwent operative fixation, 17 (16%) developed ulnar nerve neuropathy. Isolated trochlea or capitellar fractures were not predictive of ulnar nerve neuropathy. The only risk factor for ulnar nerve neuropathy was columnar fracture.)

Brouwer, KM, Jupiter, JB, Rind, D. “Nonunion of operatively treated capitelum and trochlear fractures”. J Hand Surg Am. vol. 36. 2011. pp. 804-7. (The authors evaluated 30 patients treated for fracture of the capitellum and trochlea and had a mean follow-up of 34 months. They divided their patients into 2 cohorts: 18 fractures with comminution of the capitellum and trochlea and posterior comminution (Dubberley type 3B) vs. 12 fractures without comminution (single large anterior fracture fragments). Forty-four percent (8/18) of fractures with comminution resulted in nonunion compared to 0.0% (0/12) of patients without comminution. Fractures of the trochlea and capitellum with articular comminution and posterior Dubberley type 3B comminution are an increased risk for developing nonunion after operative treatment.)

Guitton, TG, Zurakowski, D, Van Dijk, NC, Ring, D. “Incidence and risk factors for the development of radiographic arthrosis after traumatic elbow injuries”. J Hand Surg Am. vol. 35. 2010. pp. 1976-80. (The authors reported on predictors of radiographic arthrosis in 139 patients with elbow fractures with a minimum of 10-year follow-up (median 19.5 years). They found that bicolumnar distal humerus fractures, fractures of the capitellum/trochlea, and elbow-fracture dislocations were 8.0, 7.2, and 5.2 times more likely to develop moderate or severe arthrosis compared to patients who had elbow fracture without these injury patterns.)

Giannicola, G, Sacchetti, FM, Greco, A. “Open reduction and internal fixation combined with hinged elbow fixator in capitellum and trochlea fractures”. Acta Orthop. vol. 81. 2010. pp. 228-33. (The authors reported on 15 patients who underwent open reduction and internal fixation of displaced capitellum and trochlea fracture followed by hinged external fixation to allow early active and passive range of motion. The authors noted 87% (13/15) of patients had functional range-of-motion within 6 weeks of surgery. At a mean final follow-up of 29 months, 93% (14/15) of patients had a stable, pain-free range of motion of 13 degrees to 140 degrees. The authors concluded that hinged elbow fixator allows early motion while preserving joint stability.)

Sabo, MT, Fay, K, McDonald, CP. “Effect of coronal shear fractures of the distal humerus on elbow kinematics and stability”. J Shoulder Elbow Surg. vol. 19. 2010. pp. 670-80. (The authors performed a cadaveric study on eight human cadaveric elbows and removed sequential pieces of the capitellum and trochlea to replicate coronal shear fractures and examined elbow stability. Excision of the trochlea resulted in multidirectional instability of both the ulnohumeral and radiocapitellar joints. Therefore, the trochlea should not be excised.)

Ruchelsman, DE, Tejwani, NC, Kwon, YW, Egol, KA. “Coronal plane partial articular fractures of the distal humerus: current concepts in management”. J Am Acad Orthop Surg. vol. 16. 2008. pp. 716-28. (Partial articular fractures of the capitellum are often more complex than can be visualized on plain radiographs of the elbow. Extension of the capitellar fracture into the trochlea is common. As understanding of the kinematics of the elbow has evolved; the recommendation for closed treatment or fragment excision has shifted to open reduction and internal fixation of these fragments. Involvement of the trochlea significantly increased the risk for elbow instability without operative fixation.)

Summary

Isolated fractures of the humeral trochlea are rare. They are more commonly seen in the setting of complete articular fractures involving the distal humerus or as extension of the coronal shear fractures of the capitellum. Non-operative management is rarely indicated given the importance to ulnohumeral stability provided by the trochlea and the difficulty associated with managing this fracture by closed means. Operative fixation of trochlea fractures through a direct posterior approach affords the ability to evaluate the lateral side of the elbow through the same incision. Additionally, olecranon osteotomy can be performed through this incision to better visualize the entire distal humeral articular surface. Elbow stiffness is common after intra-articular distal humerus fractures, therefore, post-operative rehabilitation is key to optimizing functional outcome. Restoration of the trochlea anatomy is important to maintaining elbow stability as well as a functional range of motion.

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