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CASE REPORTS

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Humeral Plate Augmentation of an Elbow Internal Joint StabilizerKendrick Khoo, MD, Kamran Movassaghi, MD, MS, and Nathan Hoekzema, MD

Summary: We describe a unique case of a distal humerusfracture involving the capitellum with associated elbow disloca-tion. Preoperative computed tomography demonstrated avulsionfractures of the medial collateral ligament, triceps insertion, andlateral epicondyle indicative of significant elbow instability. Thepatient underwent capitellar fixation and internal joint stabilizer.Because of the osseous compromise of the lateral distal humerus,the internal joint stabilizer was augmented with a precontouredlateral distal humeral plate to maintain the axis pin position.

Key Words: capitellum fracture, complex elbow dislocation,elbow instability, internal joint stabilizer, hinged elbow fixator

INTRODUCTIONComplex elbow dislocations are challenging to manage. The

combination of osseous injury with soft tissue disruption oftenrenders the joint unstable. This issue is further complicated in thepresence of significant fracture comminution or poor bone quality.A stable fixation construct that allows for early range of motion isthe preferred to other treatment modalities.1

Postoperative stiffness after complex elbow injuries is asignificant complication often requiring secondary proceduresand may lead to worse functional outcomes.2 Hinged elbow fixa-tors, static external fixation, and crossed pinning have demon-strated success in the treatment of a variety of complex elbow

injuries. Hinged elbow fixators provide satisfactory stability toallow early range of motion in the setting of elbow instability.3 Inthe setting of complex articular fractures, hinged elbow fixation hasalso proven to be a useful adjunct in protecting articular fracturefixation while allowing for early range of motion.4 The notion ofoffloading the articular fixation by augmenting the construct with ahinged external fixator has been shown to increase stability.4

The internal joint stabilizer (IJS) of the elbow is a novel fixationdevice for treatment of elbow instability. Previous studies of the IJShave demonstrated equivalent functional outcomes and range ofmotion to hinged external fixators in the treatment of acute orchronic elbow instability.5,6 The internalized hinged mechanismminimizes the risks associated with traditional external fixators,such as pin tract infections, pin breakage, and nerve injury.2 Therehas been increased adoption of the IJS in management of persistentelbow instability after osseous and ligamentous repair.5,7

In our report we describe a fixation modification of supplement-ing the IJS system with a lateral axis plate in the treatment ofcapitellum fracture dislocation.

PATIENT INFORMATION

OTA/AO Classification: 13B3.1 [5a]A48-year-old woman sustained a left elbow injury after a fall from

standing height while working in her garden. Radiographs demon-strated a left capitellar shear fracture of the distal humerus withanterolateral dislocation of the elbow (Figs. 1A, B). She underwenttemporizingbedside reduction and splinting.Apreoperative computedtomography (CT) scan revealed significant comminution of the cap-itellum with avulsion fractures of the triceps insertion, sublime tuber-cle, and lateral epicondyle (Figs. 2A, B). The origin of the lateral ulnarcollateral ligament was avulsed taking a thin cortical shell fragment.

Surgical TechniqueThe patient was positioned supine with the arm placed in a

McConnell arm positioner (McConnel Orthopedic ManufacturingCompany, Greenville, TX). A posterior curvilinear skin incision wasmade over the elbow. Full-thickness flaps were developed down to the

Accepted for publication June 29, 2020.

From the Department of Orthopedic Surgery, UCSF Fresno, Fresno, CA.

The authors report no conflict of interest.

Reprints: Kendrick Khoo, MD, Department of Orthopedic Surgery,UCSF Fresno, 2823 Fresno St. Fresno, CA 93721 (e-mail: kkhoo@fresno.ucsf.edu).

The views and opinions expressed in this case report are those of theauthors and do not necessarily reflect the views of the editors of Journalof Orthopaedic Trauma or Skeletal Dynamics.

Copyright © 2020 Wolters Kluwer Health, Inc. All rights reserved.

DOI: 10.1097/BOT.0000000000001887

J Orthop Trauma � 2020 www.jorthotrauma.com e1

fascia. There was a traumatic avulsion of the lateral collateral ligamentcomplex from the distal humeral epicondylewith concomitant fracture.The lateral traumatic interval was developed into an arthrotomy to gainaccess to the elbow joint. The capitellar shear fragment was identifiedalong with significant injury to the lateral trochlea. The capitellar andtrochlear fragments were reduced and fixed with guidewires forheadless compression screws (Skeletal Dynamics, Miami, FL).

Once the fracture was provisionally reduced, the guidewire for theIJS axis pin (Skeletal Dynamics) was placed to recreate the distalhumerus rotational axis (Fig. 3A). Once the axis pin was placed, theheadless compression screwguidewireswere replacedby screws.After-ward, a lateral distal humeral plate (Zimmer Biomet, Warsaw, IN) wasapplied. Care was taken to center the most distal hole of the plate overthe capitellum center to allow the IJS axis pin to be placed through theplate into thedistal humerus (Figs. 3B,C).Cancellous allograftwas thenplaced tofill the voidbehind the capitellum.The elbowwas reducedandlateral collateral ligament was repaired. The IJS hinge mechanism wasassembled. The elbow was stable and well aligned.

Postoperative CourseThe patient was placed into a posterior long arm splint and their

weightlifting restricted to 5 pounds. Ten days after her surgery, the

splint was removed, postoperative radiographs were obtained, andthe patient started elbow range of motion exercises with formalphysical therapy (Figs. 4A, B).

Six months after her initial procedure, the patient underwentremoval of her IJS (Figs. 5A, B). The elbow was stable with smoothrange of motion after removal of the implant. At her 15-month post-operative visit, the patient had a flexion arc of 140 degrees (10–150degrees) and a pronosupinatory arc of 150 degrees (Fig. 6).

DISCUSSIONIn our case, this patient had articular fractures of the capitellum

extending into the trochlea in the setting of global ligamentousinstability (avulsion fractures of the triceps, lateral collateral, andmedial collateral ligament complexes). Despite the ability to treatthe capitellum fracture with direct fixation, the patient had aglobally unstable elbow.

The IJS has proven to be effective in treating acute elbowinstability.5,6 The axis pin for the IJS is inserted laterally through thecapitellar center. Given the extensive comminution of the capitelluminvolving the axis pin insertion site, a precontoured lateral distalhumeral locking plate was used to maintain the ideal lateral positionof the mechanical axis. The goal of the plate was to act as an addi-

FIGURE 1. Anteroposterior (A) and lateral (B)injury radiographs demonstrating complex elbowdislocation.

FIGURE 2. Computed tomography (CT) scan 3Dreconstruction of the preoperative left elbowrevealing capitellar shear fracture with avulsionfractures of the triceps insertion, sublime tubercle,and lateral epicondyle.

Khoo et al

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tional stabilizing point of fixation for the IJS axis pin to allow theelbow to maintain its proper axis of rotation. It is our practice to usethe IJS system in the treatment of complex elbow injuries when thereis persistent instability after osseous fixation and ligamentous repair.

Identification of the elbow axis of rotation has been shown to becritical in minimizing motion resistance. It has been described asrunning from the center of the trochlea, then exiting laterally at thecapitellum center.8,9 Proper placement of the pin determines the

FIGURE 3. Intraoperative fluoroscopic images illustrating initial IJS guidewire placement (A) and anteroposterior (B) and lateral (C)views with an IJS axis pin through a humerus plate centered at the most distal hole.

FIGURE 4. Initial postoperative anteroposterior(A) and lateral (B) radiographs of the left elbow.

FIGURE 5. Anteroposterior (A) and lateral (B)radiographs of the left elbow after removal of IJS.

Humeral Plate Augmentation of an Elbow

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functional motion of the construct. A cadaveric study by Madeyet al10 demonstrated that misplacement of the axis pin by 5 degreesoff the ideal trajectory increases energy expenditure 3.7-fold whenused in a hinged external fixator system. Misplacement jeopardizesconcentric elbow motion but can also increase stress at the capitel-lar fracture fixation site. Correct axis pin placement is also criticallyimportant in the IJS system. It is our preference to place the guide-wire for the axis pin at the beginning of the case. There is only onecorrect trajectory for the axis pin, and in this case it was possible toadjust the distal humerus fixation around the pin such that bothwere well positioned.

The short segment of fixation in the capitellum fragment pairedwith the significant lateral comminution diminished the rigidity ofthe construct. In addition, the patient in our case sustained nearglobal ligamentous instability after the dislocation. Taking thesefactors into account, the additional support of a hinged elbowfixator allowed for stable, early range of motion. Duell et alperformed a cadaveric biomechanical study on the effect ofsupplementing distal humerus plate fixation with a hinged externalelbow fixator. In their study, they found that construct stiffness wasincreased approximately 40% when a hinged elbow fixator wasadded to the fixation construct.4

Our technique of supplemental lateral axis plate is a viablesolution to the management of complex elbow injuries withconcomitant lateral comminution at the axis pin insertion site.Utilization of other points of fixation provides additional supportfor the IJS axis pin. This may also be useful in the setting ofcompromised bone quality, such as with osteoporotic bone. Similarto standard implantation of the IJS, it is recommended to have asecondary surgery for removal of the implant.

CONCLUSIONSThe IJS remains an effective tool in the treatment of complex

elbow injuries. In the presence of significant lateral distal humeruscomminution at the axis pin insertion site, stability of the axis pinshould be evaluated. If there is any increased motion laterally, the

use of a precontoured lateral distal humeral plate can provideanother point of support. The authors have also used this plateaugmentation technique in patients with significant osteoporosis tocontrol possible axis pin migration.

REFERENCES1. Lopiz Y, Rodríguez-González A, García-Fernández C, et al. Open reduc-tion and internal fixation of coronal fractures of the capitellum in patientsolder than 65 years. J Shoulder Elbow Surg. 2016;25:369–375.

2. Zhang D, Nazarian A, Rodriguez EK. Post-traumatic elbow stiffness:pathogenesis and current treatments. Shoulder Elb. 2020;12:38–45.

3. Sakai K, Shirahama M, Shiba N, et al. Primary hinged external fixation ofterrible triad injuries and olecranon fracture-dislocations of the elbow.Kurume Med J. 2017;63:7–14.

4. Deuel CR, Wolinsky P, Shepherd E, et al. The use of hinged externalfixation to provide additional stabilization for fractures of the distalhumerus. J Orthop Trauma. 2007;21:323–329.

5. Sochol KM, Andelman SM, Koehler SM, et al. Treatment of traumaticelbow instability with an internal joint stabilizer. J Hand Surg Am. 2019;44:161.e1–161.e7.

6. Orbay JL, Mijares MR. The management of elbow instability using aninternal joint stabilizer: preliminary results. Clin Orthop Relat Res. 2014;472:2049–2060.

7. Pasternack JB, Ciminero ML, Choueka J, et al. Patient outcomes for theinternal joint stabilizer of the elbow (IJS-E). J Shoulder Elbow Surg. 2020;29:e238–e244.

8. Deland JT, Garg A, Walker PS. Biomechanical basis for elbow hinge-distractor design. Clin Orthop Relat Res. 1987;215:303–312.

9. Morrey BF. Distraction arthroplasty. Clinical applications. Clin OrthopRelat Res. 1993;293:46–54.

10. Madey SM, Bottlang M, Steyers CM, et al. Hinged external fixation of theelbow: optimal axis alignment to minimize motion resistance. J OrthopTrauma. 2000;14:41–47.

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FIGURE 6. Functional outcome extension (A)and flexion (B) at 15 months after surgery.

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