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The Effect of Anteromedial Facet Fractures of the Coronoid and Lateral Collateral Ligament Injury on Elbow Stability and Kinematics
J Whitcomb Pollock, MD, MSc, FRCSC1; Jamie Brownhill, PhD2; Louis Ferreira, BESc2; Colin P. McDonald, BESc2; James Johnson, PhD2; Graham King, MD, MSc, FRCSC2
1 The Ottawa Hospital, 501 Smyth Road, Ottawa, ON K1H 8L6, Canada. E-mail address: jwpollock@gmail.com
2 Hand and Upper Limb Clinic, University of Western Ontario, 268 Grosvenor Street, Rooms B2-226 (J.B., L.F., and C.P.M.), E2-153 (J.J.), and D0-202 (G.K.), London, ON N6A 4V2, Canada
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Disclosure: In support of their research for or preparation of this work, one or more of the authors received, in any one year, outside funding or grants of less than $10,000 from the Canadian Institute of Health Research. Neither they nor a member of their immediate families received payments or other benefits or a commitment or agreement to provide such benefits from a commercial entity. No commercial entity paid or directed, or agreed to pay or direct, any benefits to any research fund, foundation, division, center, clinical practice, or other charitable or nonprofit organization with which the authors, or a member of their immediate families, are affiliated or associated.
Investigation performed at The Ottawa Hospital, Ottawa, and the Hand and Upper Limb Clinic, University of Western Ontario, London, Ontario, Canada

The Journal of Bone and Joint Surgery, Inc.
J Bone Joint Surg Am, 2009 Jun 01;91(6):1448-1458. doi: 10.2106/JBJS.H.00222
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Abstract

Background: It is postulated that fractures of the anteromedial facet of the coronoid process and avulsion of the lateral collateral ligament lead to posteromedial subluxation and arthritis of the elbow. It is not clear which injuries require internal fixation and whether repair of the lateral collateral ligament is sufficient. We hypothesized that increasing sizes and subtypes of anteromedial facet fractures cause increasing instability and that isolated lateral collateral ligament repair without fracture fixation would restore elbow stability in the presence of small subtype-I fractures.

Methods: Ten fresh-frozen cadaveric arms from donors with a mean age of 66.3 years at the time of death were used in this biomechanical study. Passive elbow flexion was performed with the plane of flexion oriented horizontally to achieve varus and valgus gravitational loading. An in vitro unconstrained elbow-motion simulator was used to simulate active elbow flexion in the vertical position. Varus-valgus angle and internal-external rotational kinematics were recorded with use of an electromagnetic tracking system. Testing was repeated with the coronoid intact and with subtype-I, subtype-II, and subtype-III fractures. Instability was defined as an alteration in varus-valgus angle and/or in internal-external rotation of the elbow. All six coronoid states were tested with the lateral collateral ligament detached and after repair.

Results: In the vertical position, the kinematics of subtype-I and subtype-II anteromedial coronoid fractures with the lateral collateral ligament repaired were similar to those of the intact elbow. In the varus position, the kinematics of 2.5-mm subtype-I fractures with the lateral collateral ligament repaired were similar to those of the intact elbow. However, 5-mm fractures demonstrated a mean (and standard deviation) of 6.2° ± 4.5° of internal rotation compared with a mean of 3.3° ± 3.1° of external rotation in the intact elbow (p < 0.05). In the varus position, subtype-II 2.5-mm fractures with the lateral collateral ligament repaired demonstrated increased internal rotation (mean, 7.0° ± 4.5°; p < 0.005). Subtype-II 5-mm fractures demonstrated instability in both the varus and valgus positions (p < 0.05). Subtype-III fractures with the lateral collateral ligament repaired were unstable in all three testing positions (p < 0.05).

Conclusions: This study suggests that the size of the anteromedial coronoid fracture fragment affects elbow kinematics, particularly in varus stress. The size of an anteromedial coronoid fracture and the presence of concomitant ligament injuries may be important determinants of the need for open reduction and internal fixation.

Clinical Relevance: This biomechanical study suggests that small subtype-I anteromedial coronoid fractures may be managed with isolated repair of the lateral collateral ligament while larger fragments probably should be treated with internal fixation in addition to lateral collateral ligament repair. Additional clinical studies are needed to determine the outcomes of operative and nonoperative treatment of anteromedial coronoid fractures.

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    References

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    These activities have been planned and implemented in accordance with the Essential Areas and policies of the Accreditation Council for Continuing Medical Education (ACCME) through the joint sponsorship of the American Academy of Orthopaedic Surgeons and The Journal of Bone and Joint Surgery, Inc. The American Academy of Orthopaedic Surgeons is accredited by the ACCME to provide continuing medical education for physicians.
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    Xin Wang
    Posted on July 23, 2010
    Treatment of Anteromedial Coronoid Facet Fracture
    Department of Orthopaedic Surgery, Tongji Hospital, Shanghai, China

    To the Editor:

    We read the article by Pollock et al. entitled, "The effect of anteromedial facet fractures of the coronoid and lateral collateral ligament injury on elbow stability and kinematics" with interest (1). They concluded that the size of the anteromedial coronoid facet fracture fragment affects elbow kinematics, particularly in varus stress, suggesting that small subtype-I anteromedial coronoid fractures may be managed with isolated repair of the lateral collateral ligament while larger fragments probably should be treated with internal fixation in addition to lateral collateral ligament repair. But there were no clinical studies to validate their conclusions.

    Because the anteromedial coronoid facet fractures were uncommon and recently recognized as a distinct type of coronoid fracture resulting from a varus posteromedial rotational injury force, very little literature was available to identify these injuries and help guide management (2-5).

    We have treated patients with these injuries and would like to present two representative cases.

    The first young man fell and sustained an isolated fracture of the anteromedial facet of the coronoid process associated with complete dislocation of the elbow. The shape of the fragment was triangular. According to the classification system of O'Driscoll, the fracture was classified as Subtype I. After the fragment of the coronoid facet was reduced and stabilized with a mini-T plate, the elbow was still subluxated. Through a lateral incision ,the avulsion of the LCL from the lateral epicondyle was identified and was repaired to the lateral epicondyle with one metal suture anchor with 2-0 Ethibond suture, leading to satisfactory reduction and stability. The Mayo Elbow Performance Score for the patient was 100 points and DASH(Disability of Arm, Shoulder and Hand) was 0.8 points after 2 years. The man returned to his labor job.

    In the second case, a middle-aged woman sustained an elbow injury with an isolated small fragment of the anteromedial coronoid facet associated with subluxation of the elbow. The fracture was also classified as Subtype I according to the classification system of O'Driscoll et al. The fragment was much smaller than the first patient's. This small fragment was stabilized with one screw. During the following period, the small fragment of coronoid was absorbed in four months after operation and the function and stability of elbow was good without osteoarthritis. From the patient, we can see that if the coronoid process bone defect is small that the elbow will remain stable.

    We were excited by the article, because the study gived us the information from biomechanics that the size of fragment is too small to affect the kinematics and stability of elbow if the lateral collateral ligament(LCL)was intact.

    Congratulations to the authors for their good biomechanical studies which provide some theoretical bases for us. We agree completely with their suggestions that small subtype-I anteromedial coronoid facet fractures may be managed with isolated repair of the lateral collateral ligament while larger fragments should be treated with internal fixation in addition to lateral collateral ligament repair. If the small fracture fragment is not stabilized, will this produce later such as heterotopic ossification, loose body, and so on? Could the small fragment be removed? So we suggest that the biomechanical study could be performed to evaluate the effect of anteromedial coronoid facet fragment removal on elbow stability and kinematics.

    The authors did not receive any outside funding or grants in support of their research for or preparation of this work. Neither they nor a member of their immediate families received payments or other benefits or a commitment or agreement to provide such benefits from a commercial entity.

    References

    1. Pollock JW, Brownhill J, Ferreira L, McDonald CP, Johnson J, King G. The effect of anteromedial facet fractures of the coronoid and lateral collateral ligament injury on elbow stability and kinematics. J Bone Joint Surg Am. 2009;91:1448-58.

    2. Doornberg JN, Ring DC. Fracture of the anteromedial facet of the coronoid process. J Bone Joint Surg Am. 2006;88:2216-24.

    3. Doornberg JN, de Jong IM, Lindenhovius AL, Ring D. The anteromedial facet of the coronoid process of the ulna. J Shoulder Elbow Surg. 2007;16:667-70.

    4. Weber MF, Barbosa DM, Belentani C, Ramos PM, Trudell D, Resnick D. Coronoid process of the ulna: paleopathologic and anatomic study with imaging correlation. Emphasis on the anteromedial "facet". Skeletal Radiol. 2009;38:61-7.

    5. O'Driscoll SW, Jupiter JB, Cohen MS, Ring D, McKee MD. Difficult elbow fractures: pearls and pitfalls. Instr Course Lect. 2003;52:113-34.

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