Prediction of Plantar Plate Injury using MRI


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Prediction of Plantar Plate Injury using MRI

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