Current Concepts In Plantar Plate Repair
How Common Is Plantar Plate Pathology?
In the experience of our institution, plantar plate pathology is responsible for much of the lesser MPJ pain/metatarsalgia in our patients. As many as 50 percent of our patients with metatarsalgia present to our clinic seeking a second opinion as they had previously seen physicians who diagnosed another pathology (generally capsulitis or a second interspace neuroma) that was resistant to treatment.
Interestingly, while conducting a cadaveric study earlier this year aimed at elucidating the cross-sectional anatomy of the metatarsal neck and the proximal attachment of the plantar plate, researchers found 80 percent (16 of 20) of these randomly selected specimens had one of four types of plantar plate tears (see the table “What A Cadaveric Study Reveals About Plantar Plate Pathology” below).12
How To Determine Plantar Plate Pathology
A thorough clinical examination can isolate the possibility of plantar plate pathology. Patients will typically present with pain to the ball of the foot that is progressive in nature. They may complain of some numbness in the area, which is likely due to swelling putting pressure on the nerves in the area. The toe may be changing position over time by becoming more dorsally aligned or with lateral or, more commonly, medial deviation. There can be concomitant first ray pathology (hallux valgus or hallux rigidus), but this is not always present.
In the most severe cases, there may be a crossover toe deformity or MPJ dislocation. Hammertoe deformities may or may not be present. In early manifestations of disease, swelling at the plantar aspect of the MPJ may be present. However, in the situation of complete tear, this may be absent. There will be pain at the plantar aspect of the MPJ or distal aspect of the metatarsal head. A modified drawer test may yield instability in comparison to the contralateral foot or in comparison to the “expected normal” when bilateral disease is present. A drawer test will be painful in the patient with an incomplete tear but is often painless with complete tear. There may be weakness of plantarflexion of the affected toe.
X-ray findings of bilateral weightbearing films will often show an altered metatarsal pattern with the second metatarsal being slightly longer in comparison to the contralateral foot, transverse plane deviation of the digits, splaying of the digits and a subtly increased metatarsus adductus angle. Interestingly, 60 percent of our patients had splaying of the second and third digits, and did not have an interdigital neuroma. In the past, advanced diagnostics were inconsistent at best. Magnetic resonance images (MRI) of a MPJ would rarely provide more than one or two slices through the joint and visualization of the plantar plate was inadequate. More recently, MRI techniques have allowed a much higher level of appreciation of the MPJ.
Our previous Fellow, Wenjay Sung, DPM, led our ACFAS Research Grant Award to determine MRI correlation to intraoperative findings of plantar plate pathology. The overall accuracy of MRI in determining if plantar plate pathology was present was 96 percent. This study also revealed a sensitivity of 95 percent, a specificity of 100 percent, a positive predictive value of 100 percent and a negative predictive value of 67 percent. This MRI study occurred without IV contrast and without intra-articular contrast, as had been done previously in the literature.13,14 Sung’s MRI study was the 2011 poster award winner at the American Orthopedic Foot and Ankle Surgeons Annual Summer Meeting, and will be published in the Journal of Foot and Ankle Surgery in 2012.15