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Prediction of Midfoot Instability in the Subtle Lisfranc InjuryComparison of Magnetic Resonance Imaging with Intraoperative Findings
Steven M. Raikin, MD1; Ilan Elias, MD1; Sachin Dheer, MD2; Marcus P. Besser, PhD3; William B. Morrison, MD2; Adam C. Zoga, MD2
1 Rothman Institute, Thomas Jefferson University Hospital, 925 Chestnut Street, Philadelphia, PA 19107. E-mail address for S.M. Raikin: Steven.raikin@rothmaninstitute.com
2 Department of Radiology, Thomas Jefferson University Hospital, 111 South 11th Street, Philadelphia, PA 19107
3 Human Performance and Gait Laboratory, Thomas Jefferson University, 130 South 9th Street, Suite 830, Philadelphia, PA 19107
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Disclosure: 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. 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 Thomas Jefferson University Hospital, Philadelphia, Pennsylvania

The Journal of Bone and Joint Surgery, Inc.
J Bone Joint Surg Am, 2009 Apr 01;91(4):892-899. doi: 10.2106/JBJS.H.01075
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Abstract

Background: The objective of the present study was to assess the utility of magnetic resonance imaging for the diagnosis of an injury to the Lisfranc and adjacent ligaments and to determine whether conventional magnetic resonance imaging is a reliable diagnostic tool, with manual stress radiographic evaluation with the patient under anesthesia and surgical findings being used as a reference standard.

Methods: Magnetic resonance images of twenty-one feet in twenty patients (ten women and ten men with a mean age of 33.6 years [range, twenty to fifty-six years]) were evaluated with regard to the integrity of the dorsal and plantar bundles of the Lisfranc ligament, the plantar tarsal-metatarsal ligaments, and the medial-middle cuneiform ligament. Furthermore, the presence of fluid along the first metatarsal base and the presence of fractures also were evaluated. Radiographic observations were compared with intraoperative findings with respect to the stability of the Lisfranc joint, and logistic regression was used to find the best predictors of Lisfranc joint instability.

Results: Intraoperatively, seventeen unstable and four stable Lisfranc joints were identified. The strongest predictor of instability was disruption of the plantar ligament between the first cuneiform and the bases of the second and third metatarsals (the pC1-M2M3 ligament), with a sensitivity, specificity, and positive predictive value of 94%, 75%, and 94%, respectively. Nineteen (90%) of the twenty-one Lisfranc joint complexes were correctly classified on magnetic resonance imaging; in one case an intraoperatively stable Lisfranc joint complex was interpreted as unstable on magnetic resonance imaging, and in another case an intraoperatively unstable Lisfranc joint complex was interpreted as stable on magnetic resonance imaging. The majority (eighteen) of the twenty-one feet demonstrated disruption of the second plantar tarsal-metatarsal ligament, which had little clinical correlation with instability.

Conclusions: Magnetic resonance imaging is accurate for detecting traumatic injury of the Lisfranc ligament and for predicting Lisfranc joint complex instability when the plantar Lisfranc ligament bundle is used as a predictor. Rupture or grade-2 sprain of the plantar ligament between the first cuneiform and the bases of the second and third metatarsals is highly suggestive of an unstable midfoot, for which surgical stabilization has been recommended. The appearance of a normal ligament is suggestive of a stable midfoot, and documentation of its integrity may obviate the need for a manual stress radiographic evaluation under anesthesia for a patient with equivocal clinical and radiographic examinations.

Level of Evidence: Diagnostic Level II. See Instructions to Authors for a complete description of levels of evidence.

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    References

    Accreditation Statement
    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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    Steven M. Raikin, MD
    Posted on September 02, 2010
    Dr. Raikin responds to Dr. Poeze
    Rothman Institute/Thomas Jefferson University, Philadelphia, Pennsylvania

    Thank you for your well thought out letter to the editor regarding our study, "Prediction of Midfoot Instability in the Subtle Lisfranc Injury. Comparison of Magnetic Resonance Imaging with Intraoperative Findings.”

    Many of the points which you raise are valid and the study does have limitations which are acknowledged within the manuscript, particularly related to the limited number of patients in the study.

    The main issue of your letter questions “is a reduction of 14% stress tests equal against performing 21 MRI scans?”

    In our opinion, the answer in unquestionable: yes!

    1. An MRI study in a non-invasive, non-radiation emitting study without known risk to the patient.

    2. A stress test in usually performed in the operating room (OR) under some form on anesthesia, with the patient frequently prepared to undergo a concomitant surgical procedure if found to be positive. The risk of anesthesia, however small, looms large over that of an MRI study. Additionally the emotional stress of a visit to the OR is significantly greater than that of undergoing an MRI evaluation.

    3. While MRI studies remain costly, the financial burden of a stress test in the operating room is significantly greater to the system, particularly when surgery is not going to be needed.

    Continued data collection since publication and experience with the MRI technique has successfully predicted the stability/instability of numerous patients. An MRI demonstrating an intact pC1-M2M3 ligament has obviated intra-operative stress testing in these patients, with radiographic follow-up confirming the absence of development of Lisfranc diastasis or midfoot instability. We still believe that patients with MRI evidence of midfoot instability on whom surgical fixation is planned should undergo a pre-incision stress test once under anesthesia to confirm diastasis. Thus far all our cases have demonstrated instability corresponding to the MRI findings.

    Finally many of these patients, including those who do not have midfoot instability, do have other subtle injuries (such as undisplaced metatarsal fractures) which are demonstrated on the MRI study and can help guide subsequent treatment.

    Martijn Poeze
    Posted on August 10, 2010
    MRI for Determining Midfoot Instability: Too Soon to Pass the Test
    Department of Surgery, Maastricht University Medical Center, Maastricht, The Netherlands

    To the Editor:

    We read the article, "Prediction of midfoot instability in the subtle Lisfranc injury. Comparison of magnetic resonance imaging with intraoperative findings" by Raikin et al. (2009;91:892-9) determining midfoot instability in the Lisfranc joint complex comparing MRI and the ‘golden standard’ intra-operative stress testing with great interest. The authors stated, as recently summarized by Marx et al. in their specialty update (1), that MRI is an accurate predictor of Lisfranc ligament instability. We would like to argue that, in contrast to the authors' conclusion, not the positive predictive value of the MRI, but the negative predictive value in this diagnostic study seems to be valid (2). The authors report a sensitivity of 94% in predicting Lisfranc ligament instability based upon a stepwise logistic regression model with use of the plantar Lisfranc ligament as a predictor. The limited number of patients (n = 21), however, has important implications for the validity of this study. For example, although the 95 % confidence interval (CI) was not reported, the sensitivity of the MRI has a wide variation from 69% to 99%. In addition, the sensitivity in itself does not provide information about the power of a test to include or exclude a target condition. Therefore, general consensus is that in (especially smaller) diagnostic studies it is better to report the likelihood ratio with the 95% confidence interval (3). Interestingly, in this study the likelihood ratio of finding instability (LR+) is 3.8 with a 95% CI of 0.69-20.6. This means that finding a rupture of the plantar Lisfranc ligament complex on MRI scanning in this study does not provide additional diagnostic value over the standard regime. In addition, the high pre-test probability (chance of finding instability prior to MRI) of 81% (17 out of the 21 patients included) necessitates a high positive likelihood ratio (>10) in order to be clinically relevant. Although the authors do not report the negative predictive value, this is clinically relevant. The negative LR was 0.08 (95% CI: 0.01 to 0.57), indicating that the absence of a rupture on MRI convincingly rules out subsequent instability. The authors report a diagnostic algorithm indicating that with a positive MRI result patients could undergo surgery without further testing. Although this conclusion seems to be formulated prematurely, a negative diagnostic test on the MRI indeed seems to indicate that conservative treatment is warranted. However, one may wonder whether MRI scanning with these data is warranted. The use of MRI scanning would prevent a stress test in 4 out of 21 patients, with one false-negative result. Put it another way, is a reduction in 14% stress tests equal against performing 21 MRI scans? In our opinion, more data are necessary before the algorithm can be used in clinical practice.

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

    References

    1. Marx RC, Mizel MS. What's new in foot and ankle surgery. J Bone Joint Surg Am. 2010;92:512-23.

    2. Knottnerus JA, Buntinx F, editors. The evidence base of clinical diagnosis: theory and methods of diagnostic research. 2nd ed. West Sussex: John Wiley & Sons Ltd; 2008.

    3. Steinberg DM, Fine J, Chappell R. Sample size for positive and negative predictive value in diagnostic research using case-control designs. Biostatistics. 2009;10:94-105.

    Steven M. Raikin, MD
    Posted on May 24, 2009
    Dr. Raikin and colleagues respond to Dr. Summerhays and colleagues
    Thomas Jefferson University Hospital, Philadelphia, PA

    We thank Dr. Summerhays and colleagues for their letter regarding our study on “Prediction of Midfoot Instability in Subtle Lisfranc Injury” (1).

    With regard to the bundles, we did not find isolated ligamentous bands between the medial cuneiform and the second metatarsal base. Instead, we consistently observed two intimate but distinct ligamentous bundles running between the planatar central cuneiform and the second/third metatarsal bases. These bundles are morphologically analagous to the two bundles of an anterior cruciate ligament (ACL) and may very well be contained within one synovial sheath. With recently improved MRI technology and gradient strength, we routinely observe both of these bundles on all high-quality examinations. In this study, we grouped the two bundles together (which may represent the “Lisfranc” and pC1-M2M3 ligaments) describing a rupture as incompetence of both bundles, which may in fact occur as a single entity (as with the ACL) during the injury mechanism.

    With regard to the question about the existence of the pC2-M2 ligament, Sarrafian does describe a variant of a ligament band running between the plantar lateral aspect of the second metatarsal and the middle cuneiform. Additionally MRI evaluation of uninjured feet demonstrate a clear capsular band plantarly in this region, akin to a plantar plate like structure. Whether one calls it a thickened joint capsule or a ligament may be a matter of semantics, but the connective tissue at the plantar aspect of the cuneiform-metatarsal articulations was clearly injured in many of our patients, based upon the review of two experienced musculoskeletal radiologists, and was not a reproducible sign of midfoot instability.

    Reference

    1. Raikin SM, Elias I, Dheer S, Besser MP, Morrison WB, Zoga AC. Prediction of midfoot instability in the subtle Lisfranc injury. Comparison of magnetic resonance imaging with intraoperative findings. J Bone Joint Surg Am. 2009;91:892-9.

    Ben J. Summerhays, DPM
    Posted on May 15, 2009
    Prediction of Midfoot Instability in Subtle Lisfranc Injury
    Wheaton Franciscan Healthcare-St. Joseph's Milwaukee, WI

    To the Editor:

    In their recent article (1), Raiken et al. conclude that MRI is accurate for detecting traumatic injury of the Lisfranc ligament and for predicting Lisfranc joint complex instability when there is rupture of the plantar ligament bundle between the medial cuneiform and bases of metatarsals 2 and 3 (pC1-M2M3). The authors also looked to see if injury to other ligamentous structures of the Lisfranc joint could be used to determine instability. We have a few observations regarding this study.

    Sarrafian (2) states that the Lisfranc ligament is the first interosseous cuneo1-metatarsal2 ligament arising from the lateral surface of the first cuneiform in front of the intercuneiform ligament, and under the particular surface corresponding to the second metatarsal. The ligament is directed obliquely outward and slightly downward and inserts on the lower half of the medial surface of the second metatarsal base. Sarrafian also states that the ligament is distinct from the dorsal and plantar ligaments (2). In their article (1), Raikin et al. do not make reference to this interosseous ligament.

    Kaar et al. (3) found that both the pC1-M2M3 ligament and Lisfranc ligament must be ruptured for transverse instability to occur. Perhaps evaluating the MR images for possible rupture or tear of the interosseous Lisfranc ligament would provide better correlation with Lisfranc joint complex stability. Preidler et al. (4) in their study on the tarsometatarsal joint MR imaging pointed out the effectiveness and ability to view the Lisfranc ligament in all planes of MR imaging.

    Raikin et al. (1) state several times that rupture of the plantar cuneiform 2-metatarsal 2 ligament was identified in the majority (18) of the 21 feet, but this was not useful in predicting stability. However, Sarrafian (2), Kaar et al. (3) , and Kura et al. (5) all have found that there is no plantar ligament between the second cuneiform and second metatarsal; thus its absence, or apparent rupture is likely normal anatomy.

    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. 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.

    References

    1. Raikin SM, Elias I, Dheer S, Besser MP, Morrison WB, Zoga AC. Prediction of midfoot instability in the subtle Lisfranc Injury. Comparison of magnetic resonance imaging with intraoperative findings. J Bone Joint Surg Am. 2009;91:892-9.

    2. Sarrafian SK. Anatomy of the foot and ankle: descriptive, topographic, functional. 2nd ed. Philadelphia: Lippincott Williams and Wilkins; 1993. p 205-6.

    3. Kaar S, Femino J, Morag Y. Lisfranc joint displacement following sequential ligament sectioning. J Bone Joint Surg Am. 2007;89:2225-32.

    4. Preidler KW, Wang YC, Brossmann J, Trudell D, Daenen B, Resnick D. Tarsometatarsal joint: anatomic details on MR images. Radiology. 1996;199:733-6.

    5. Kura H, Luo ZP, Kitaoka HB, Smutz WP, An KN. Mechanical behavior of the Lisfranc and dorsal cuneometatarsal ligaments: in vitro biomechanical study. J Orthop Trauma. 2001;15:107-10.

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