Reviewing Pertinent Principles With Plantar Plate Injuries And Emerging Repair Options

We have all seen patients in the office with a crossover toe. Most patients just say they have “ugly feet” and don’t think much of it. This deformity, however, is more complicated than just ugly feet. Plantar plate injuries are treatable and with some of the stronger new surgical systems that have developed, repair of this ligament has become easier.

It is important to understand the anatomy of the plantar plate and its surrounding structures. The plantar plate is the distal most major insertion of the plantar fascia and is continuous with the metatarsophalangeal joint (MPJ) capsule. The plantar plate inserts on the base of the proximal phalanx. The flexor tendons are directly plantar to the plantar plate. Injuries to the plantar plate can arise idiopathically from trauma and biomechanical abnormalities. It is also important to note that the crossover deformity of the second digit is often concomitant with a hallux abductovalgus (HAV) deformity, which one must addess in order to effectively perform the plantar plate repair and correct the second digit deformity.

Yu and colleagues described the term “pre-dislocation syndrome” to illustrate the symptomatology that patients experience early with plantar plate injuries.¹ Patients will complain of pain to the area just distal to the affected MPJ along with a feeling of fullness of the joint. There may also be swelling, which can obstruct the view of the extensor tendons. This pain can mimic capsulitis of the MPJ but plantarflexion of the digit may provide some pain relief in patients with a plantar plate injury.

Aside from pain of palpation of the joint, perform a Lachman test to assess for a plantar plate tear. With this test, pull the proximal phalanx dorsally with a stabilized metatarsal. More than 2 mm of displacement of the phalanx indicates a plantar plate rupture or insufficiency.

One typically obtains magnetic resonance imaging (MRI) for plantar plate injuries. Radiographs in the office are adequate for assessing any displacement of the digit. The digit will typically be dorsally dislocated and associated with a digital deformity as well. The MRI enables one to visualize the plantar plate tear and any other soft tissue injury in this area. When ordering this study, it can be helpful to make sure the facility knows you are assessing a plantar plate tear. Some MRI slices are 5 mm, which is large enough to completely miss the area of interest. Specific instructions as to what you are looking for may help the imaging team ensure adequate imaging of this area. However, keep in mind that a thorough clinical exam with a positive correlation to a plantar plate injury can save the patient an expensive test.

Conservative treatment can depend on the stage of injury. Early on before the toe begins to drift dorsally, splinting the toe in plantarflexion with tape is often the easiest and most effective treatment. Educate the patient on how to properly tape the foot into plantarflexion in order to help maintain this position between appointments. One can prescribe oral non-steroidal anti-inflammatory drugs (NSAIDs) or steroids to help control pain and inflammation.

Patients who present to the office with a dorsally dislocated digit or even one that is crossed over will not benefit from a splinting regimen. Provided these patients are not surgical candidates, extra wide toe box shoes with a mesh or Lycra top cover are necessary to allow for the deformity to safely fit into the shoes. Offloading orthotics may be necessary if there are hyperkeratoses due to abnormal biomechanics to compensate for the chronic subluxation.

Surgery is often indicated for those patients with persistent pain despite conservative care as well as those whose condition has developed to a loss of toe purchase or complete subluxation. The surgical approaches for plantar plate repair vary depending on surgeon preference and other deformities to be corrected. I have also been able to use and assist in cases with some of the newer plantar plate repair systems put out by various companies. Again, if an HAV deformity is present, one should appropriately treat the injury.

The plantar approach to plantar plate repair has its advantages and disadvantages. This approach allows for direct visualization of the plantar plate without the need for a metatarsal osteotomy or disruption of the joint capsule. It also enables surgeons to perform primary repair without the need for any special instrument or equipment systems. With this approach, the surgeon may not need to resect the plantar plate from the proximal phalanx if the tear is not in the proximal phalanx. However, as we are always cautioned, any incision on the plantar aspect of the foot can result in painful scar formation. This is a particularly concerning issue considering the length of incision that may be necessary to adequately visualize and repair the plantar plate.

Often a metatarsal osteotomy is necessary to adequately treat all of the pathology present and the dorsal approach offers the ability to correct all deformities and perform all osteotomies through the same incision. In my experience, this is the most common approach. Most plantar plate repairs also require a hammertoe correction and the surgeon can do this through the same incision. The lack of a large operative field between the metatarsal head and the phalanx can make visualization and re-approximation difficult. I have found this approach requires an adequate Weil osteotomy in order to provide enough working room to visualize and repair the plantar plate. If one does not perform the Weil osteotomy parallel to the weightbearing surface, then the metatarsal head will not distract proximally enough to allow for adequate visualization and repair.

The various repair systems focus on the ease of repairing the plantar plate as well as fixating the distal aspect of the plantar plate to the proximal phalanx base. The most commonly used systems in my area are the Mini-Scorpion (Arthrex), the Complete Plantar Plate Repair (CPR) Viper (Arthrex), and the Gravity Plantar Plate Repair System (Wright Medical). All of these systems are generally all inclusive for repair of the plantar plate and fixation of any metatarsal osteotomy.

Every practitioner has a preference as to what system they prefer, if any, as these systems often have a learning curve to them. When one performs these techniques correctly, they provide great repair and fixation to the proximal phalanx, which brings the digit back to a rectus position. In my experience, these systems are the key to an adequate reduction in the crossover toe and plantar plate repair. They simplify the repair and reinforce the digital correction at the MPJ. In addition to repairing the plantar plate itself, these systems also incorporate fixation of the plantar plate to the base of the proximal phalanx for added stability.

Plantar plate injuries are difficult to treat regardless of the stage. Even if one catches the injury early, it may still progress to a dorsally dislocated digit and a crossover deformity. The surgical options vary but a good understanding of the anatomy of the plantar plate, surrounding structures and the etiology of pathology can ensure the practitioner chooses the most appropriate course of treatment.

References

1. Yu GV, Judge MS, Hudson JR, Seidelmann FE. Predislocation syndrome – progressive subluxation/dislocation of the lesser metatarsophalangeal joint. J Am Podiatr Med Assoc. 2002; 92(4):182-99.

2. Brosky TA, McGlamry MC, Powell DR. Revisiting predislocation syndrome with direct repair of the plantar plate. Podiatry Institute Update, Chapter 10, 2010, pp. 45–48.

3. Camasta CA. Plantar plate repair of the second metatarsophalangeal joint. In McGlamry’s Comprehensive Textbook of Foot and Ankle Surgery, Fourth Edition, Lippincott Williams & Wilkins, Philadelphia, 2012, pp. 187-201.