Background: Previous literature has suggested both MRI and ultrasound can accurately diagnose plantar plate tears. There is a significant cost difference between these two modalities, sparking interest for which should be the preferred method for diagnosis.
Purpose: The purpose of this study was to examine the diagnostic accuracy of MRI and dynamic, musculoskeletal ultrasound for lesser metatarsal plantar plate injuries using a systematic review and meta-analysis.
Methods: MEDLINE, CINAHL, and Clinicaltrials.gov were searched thru May 2020. We included studies evaluating the diagnostic accuracy of MRI or ultrasound for detecting plantar plate tears, using intraoperative confirmation as the gold standard comparison. Sensitivity and specificity were obtained and pooled from included studies. Summary receiver operating curves were formed for each diagnostic test to compare accuracy. Study quality was assessed using the QUADAS-2 scoring system.
Results: Eleven studies met our inclusion criteria, representing 227 plantar plates for MRI and 238 plantar plates for ultrasound. MRI displayed a pooled sensitivity of 89% (95% CI 0.84, 0.93) and specificity of 83% (95% CI 0.64, 0.94). Ultrasound displayed a sensitivity and specificity of 95% (95% CI 0.91, 0.98) and 52% (95% CI 0.37, 0.68), respectively.
Conclusion: MRI was superior to ultrasound in diagnosing plantar plate injuries overall, however, ultrasound was more sensitive than MRI, suggesting a negative ultrasound would likely rule out a plantar plate injury in the presence of an equivocal physical exam. Determining the grade of the injury is best served with MRI which can provide added insight into the joint's supporting structures (e.g. collateral ligaments) and integrity.
Keywords: Diagnostic; MRI; Meta-analysis; Plantar plate; Systematic review; Ultrasound.
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