prediction of plantar plate injury using mri
DESCRIPTION
My e-poster won BEST in Category and BEST in Show at the AOFAS 2011 Summer MeetingTRANSCRIPT
Twitter: @jaysung#foot2011
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.
Twitter: @jaysung#foot2011
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).
Twitter: @jaysung#foot2011
PurposeBackground
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.
Twitter: @jaysung#foot2011
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)
Twitter: @jaysung#foot2011
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).
Twitter: @jaysung#foot2011
MethodsInclusion 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
Twitter: @jaysung#foot2011
Methods
MRI to be performed at 0.31 T (O-Scan Extremity MRI, Biosound Esaote 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.
Twitter: @jaysung#foot2011
ResultsDemographics
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
All 41 patients (45 feet) elected to have surgery to the case foot
Twitter: @jaysung#foot2011
ResultsMRI 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”
Twitter: @jaysung#foot2011
ResultsTable 1 - Tear Diagnosed on MRI vs Tear Actually Present
Cross-tabulation—Positive and Negative Predictive Values
Tear Actually Present
TotalNo YesTear Diagnosed on MRI
Yes Count 0 39 39% within Tear Diagnosed on MRI
0.00% 100.00% 100.00%
No Count 4 2 6
% within Tear Diagnosed on MRI
66.67% 33.33% 100.00%
Total Count 4 41 45% within Tear Diagnosed on MRI
8.89% 91.11% 100.00%
Twitter: @jaysung#foot2011
Results Sensitivity = 95%
Specificity = 100%
Positive Predictive Value = 100%
Negative Predictive Value = 67%
Twitter: @jaysung#foot2011
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.
Twitter: @jaysung#foot2011
DiscussionStrength
Prospective, diagnostic
Power analysis to determine needed sample size
Statistical analysis
Simple, reproducible study
Weakness
Assessor bias
No blinding
Twitter: @jaysung#foot2011
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
Twitter: @jaysung#foot2011
References
1. Yao L, Cracchiolo A, Farahani K, et al. Magnetic resonance imaging of plantar plate rupture. Foot Ankle Int. 1996;17:33-36.
2. 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.
3. 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.
4. 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.
5. 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.
6. Karpman RR, MacCollum MS, 3rd. Arthrography of the metatarsophalangeal joint. Foot Ankle. 1988;9:125-129.
7. Weil Jr L, Sung W, Weil Sr LS, et al. Anatomic Plantar Plate Repair. Tech Foot Ankl Surg. 10(1):33-39, March 2011.