What are Plantar Plate Injuries?
Plantar plate injuries refer to damage sustained by one of the strong ligaments located on the bottom of the foot called the plantar plate.
The plantar plate is a thick ligament that runs along the ball of the foot, attaching to the joints. It is a fibrocartilaginous structure designed to safeguard the metatarsal head (the long bones of the foot) from excess pressure and stabilize the metatarsophalangeal joints (MTPJ). An MTP joint connects one of the toes (a phalanx or a phalangeal bone) to a long bone in the foot (a metatarsal bone). There are 5 MTP joints on each foot, one for each toe. The plantar plate also acts as an attachment site for the plantar fascia. It plays a key role in keeping the toes in place, stopping them from drifting or over-extending, and stabilizing them, especially toes two, three, four, and five.
Causes of Plantar Plate Injuries
The most common cause of a plantar plate injury is an overload of pressure on the MTP joint. This leads to significant strain which eventually causes attenuation and a rupture in the plantar plate region. It is this rupture that leads to instability and pain which characterizes the injury. Even though plantar plate ruptures can happen suddenly, they commonly develop gradually over time from progressive degeneration of the ligament from repetitive overuse or abnormalities, such as:
- Having a hammertoe or bunion
- Activities that place increased pressure on the ball of the foot, such as running, climbing stairs, and dancing
- The tendency to over-pronate (roll the feet inwards)
- Having a long second metatarsal bone
Signs and Symptoms of Plantar Plate Injuries
Persistent swelling and pain underneath the ball of the foot that extends toward the toes is the first common sign of a plantar plate injury or rupture. This pain may be reproduced by bending the toe upwards. Some swelling may be visible on the top of the foot, along with redness. Most often a sensation of “walking on the bones of the foot” will be reported, and a “V” sign between the toes may be seen, where 2 toes have moved apart further from one another than what is usual as a result of a plantar plate rupture.
Diagnosis of Plantar Plate Injuries
To diagnose plantar plate injuries, your physician will conduct a thorough physical examination of the foot where your physician will move and manipulate the troubled toe joint into several different angles to assess the location of the pain and the level of deformity. Usually, there is pain and inflammation at the plantar aspect of the metatarsal head and pain at the base of the proximal phalanx.
Weight-bearing X-rays will also be ordered to assess plantar plate injuries. X-rays show the angles and degree of the toe deformity, as well as any arthritis in the joint.
Additional imaging such as magnetic resonance imaging (MRI) may also be ordered to assess the quality of the plantar plate, which X-rays cannot reveal. MRI can reveal further details of the plantar plate ligament such as if there is any thickening, joint effusion, and partial to complete plantar plate ruptures. Ultrasound may be ordered as well.
Treatment for Plantar Plate Injuries
The first line of treatment for plantar plate injuries is usually conservative methods and consists of rest, icing, non-steroidal anti-inflammatory drugs (NSAIDs), plantar flexion strapping of the digit, and accommodative padding to decrease stress or loads under the affected MTP joint.
In severe cases, your physician may recommend a boot to take the weight off the ball of the foot. Tape may be wrapped around the toe to hold it at a downward angle for several weeks. If there is any deformity from side to side, the tape can hold the toe in the opposite direction, which enables the healing of the ligament without continued strain.
Custom-molded orthotics may also be recommended. Orthotics with support under the ball of the foot mitigates pressure off the overstretched region and keeps the deformity from returning. Anti-inflammatories may be prescribed to decrease pain and inflammation.
In cases where the toe has drifted significantly due to overstretching of the ligament, conservative treatments may only ease the pain, but surgical treatments are required to put the toe back into a normal position. Surgery is very occasionally needed as often wearing a customized soft full-length orthotic and proper footwear can prevent the progression of the deformity. Surgery is usually recommended as a last resort and will involve repairing the plantar plate, or in chronic cases, performing a resection osteotomy under anesthesia. The surgery may take about 30 minutes. Restoring the plantar plate can take time, with most patients pain-free within 3 to 4 months.
