Prediction of Plantar Plate Injury using MRI

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My e-poster won BEST in Category and BEST in Show at the AOFAS 2011 Summer Meeting

My e-poster won BEST in Category and BEST in Show at the AOFAS 2011 Summer Meeting

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  • 1. Prediction of Plantar Plate Tear by Magnetic Resonance Imaging with Correlation to Intra-Operative Findings
    • Authors: Wenjay Sung, DPM,Lowell Weil, Jr., DPM, Lowell Scott Weil, Sr., DPM, and Richard Rofles, MD.
  • Disclosures
    My disclosure is in the Final AOFAS Program Book.
    My co-authors have their disclosures in the Final AOFAS Program Booklet.
    Our presentation was funded by a research grant from the American College of Foot and Ankle Surgeon’s Clinical and Scientific Research Committee (2010).
  • 2. Purpose
    Background
    Diagnostic studies have developed enhanced protocols to detect specific injury to the plantar plate2,5,6.
    Principle stabilizer of the MTP joint
    The integrity is essential to stabilize the proximal phalanx of the lesser toes4.
    Descriptions of plantar plate ruptures on MRI have been well documented by Yao et al1,2
    Gregg et al3 found that MRI was high in sensitivity but low in specificity in cadavers.
  • 3. Purpose
    To assess the utility of magnetic resonance imaging (MRI) in diagnosing injury of the plantar plate ligament to the second metatarsophalangeal (MTP) joint
    To determine the reliability of MRI as a diagnostic tool with correlation to intra-operative observations as a reference standard.
    Prospective, diagnostic study
    EBM Level of evidence: II (prospective diagnostic)
  • 4. Methods
    IRB approved
    Prospectively enrolled consecutive adult subjects after clinical suspicion of plantar plate pathology
    Power analysis for this research has determined the need for at least 45 subjects
    Alpha level = 0.05, Observed R2 = 0.15, Observed Power = 0.80).
    Sensitivity, specificity, positive predictive values and negative predictive values were calculated using this model.
    All statistical analysis were performed by an outside consultant statistician using SPSS version 14.0 (SPSS Science Inc, Chicago, Ill).
  • 5. Methods
    Inclusion Criteria
    Clinical diagnosis
    Healthy male or female, ages 18-75
    Failed at non-operative treatments for a period of at least three months
    Elected for surgical correction
    Exclusion Criteria
    Previous surgery to 2nd MTP joint region
    Known allergy to contrast dye
    Chronic kidney disease
    Women who are pregnant
    Any contraindications to MRI, including history of implanted pacemaker, loose shrapnel, ocular implants, or ventricular stents
  • 6. Methods
    MRI to be performed at 0.31 T (O-Scan Extremity MRI, BiosoundEsaote Inc, Indianapolis, IN).
    Evaluation included
    coronal T1-weighted images
    coronal T2-weighted images
    coronal fast-spin-echo short tau inversion recovery images
    sagittal T1-weighted images
    sagittal T2-weighted images
    sagittal fast-spin-echo short tau inversion recovery images
    One fellowship-trained musculoskeletal radiologist created the protocol and evaluated the MRI data
    Two different attending surgeons performed the surgeries.
    One foot & ankle fellow was present to observe all intra-operative findings.
  • 7. Results
    Demographics
    All 41 patients (45 feet) elected to have surgery to the case foot
    From August 2010 until May 2011, 41 patients (45 feet) underwent MRI scan for suspected plantar plate pathology.
    Thirty eight were female and three male with an average age of 52.4
  • 8. Results
    MRI Reading
    39 cases were read as “tear”
    6 cases were read as “no tear”
    Visual inspection
    All 39 were confirmed “tear”
    4 of 6 were confirmed “no tear”
    2 of 6 were in fact “tears”
  • 9. Results
  • 10. Results
    Sensitivity = 95%
    Specificity = 100%
    Positive Predictive Value = 100%
    Negative Predictive Value = 67%
  • 11. Discussion
    MRI appears to be good a “ruling-in” test for a tear
    MRI does not appear to give false positives.
    However, MRI may not be as accurate for “ruling-out” a tear.
    Accurate predictive values from MRI results may be meaningful for those who:
    Wish to repair the plantar plate ligament
    May not recognize the prevalence of this pathology in lesser MTP joint deformities.
  • 12. Discussion
    Strength
    Prospective, diagnostic
    Power analysis to determine needed sample size
    Statistical analysis
    Simple, reproducible study
    Weakness
    Assessor bias
    No blinding
  • 13. Conclusions
    We hope with these protocols more clinicians can assess the utility of magnetic resonance imaging in the diagnosis of injury to the plantar plate ligament
    We are planning to evaluate the utility of diagnostic ultrasound vs MRI in assessing plantar plate tears
  • 14. References
    Yao L, Cracchiolo A, Farahani K, et al. Magnetic resonance imaging of plantar plate rupture. Foot Ankle Int. 1996;17:33-36.
    Yao L, Do HM, Cracchiolo A, et al. Plantar plate of the foot: findings on conventional arthrography and MR imaging. AJR Am J Roentgenol. 1994;163:641-644.
    Gregg JM, Silberstein M, Schneider T, et al. Sonography of plantar plates in cadavers: correlation with MRI and histology. AJR Am J Roentgenol. 2006;186:948-955.
    Yu GV, Judge MS, Hudson JR, et al. Predislocation syndrome. Progressive subluxation/dislocation of the lesser metatarsophalangeal joint. J Am Podiatr Med Assoc. 2002;92:182-199.
    Powless SH, Elze ME. Metatarsophalangeal joint capsule tears: an analysis by arthrography, a new classification system and surgical management. J Foot Ankle Surg. 2001;40:374-389.
    Karpman RR, MacCollum MS, 3rd. Arthrography of the metatarsophalangeal joint. Foot Ankle. 1988;9:125-129.
    Weil Jr L, Sung W, Weil Sr LS, et al. Anatomic Plantar Plate Repair. Tech Foot Ankl Surg. 10(1):33-39, March 2011.