Positive Drawer Test Combined With Radiographic Deviation of the Third Metatarsophalangeal Joint Suggests High Grade Tear of the Second Metatarsophalangeal Joint Plantar Plate

Abstract

There is uncertainty regarding the most accurate and cost-effective method for diagnosing plantar plate injuries within the foot. The purpose of this study was to examine the combined value of using clinical and radiographic findings to diagnose high grade tears (> 50% disruption) within the second metatarsophalangeal (MTP) joint. Ninety-eight consecutive patients (117 feet) who underwent corrective surgery for plantar forefoot pain at a single foot and ankle specialty clinic were included in this retrospective analysis. All patients received a structured intraoperative assessment of the second MTP joint plantar plate by a single trained observer. Twenty-five clinical and plain film radiographic variables obtained prior to surgery were tested for their association with a high grade plantar plate tear using multiple logistic regression techniques. A positive drawer sign was the most informative individual test for differentiating high from low grade tears (odds ratio [OR] = 2.9; 95% confidence interval [CI], 0.92-9.5; sensitivity 91.5%; specificity 22%). Patients with longstanding forefoot symptoms (> 2 years) tended to be more likely to have low grade tears only (OR = 2.1; 95% CI, 0.98-4.5; sensitivity 61.7%; specificity 58.1%). Most radiographic measurements did little to distinguish high from low grade tears; however, the addition of ipsilateral third MTP joint transverse deviation angle showed a trend toward improving upon the diagnostic accuracy of strategies that used clinical findings alone (area under the curve [AUC] improved from 0.63 to 0.67; P = .11). A third MTP joint deviation angle greater than 15° in either direction combined with drawer testing and duration of symptoms achieved the highest specificities of any combination of variables examined in the study (specificities 82.4% [95% CI, 73.7%-91.1%] and 89.1 [95% CI, 82.1-96.3], respectively). The combination of a positive drawer test coupled with transverse deviation of the third MTP joint (> 15°) on plain films strongly suggests an underlying high grade plantar plate tear of the second MTP joint. However, this study highlights the need for using advanced imaging to distinguish between high and low grade tears in many instances (eg, positive drawer test and normal or near-normal alignment of the third MTP joint). Level of Evidence: Diagnostic, Level II