Friday, March 23, 2012

Predislocation Syndrome


Metatarsalgia is a general term that is used to refer to pain in the metatarsal heads of the foot. This is the area of the metatarsal that forms the proximal half of the metatarsal-phalangeal (MTP) joints, which are the joints that connect the toes to the rest of the foot.  Pain underneath the second metatarsal head is a common clinical presentation. 

Pain in the second metatarsal most commonly occurs in the presence of hallux limits.  Hallux limitus is a condition in which the first metatarsophalangeal joint (the joint that connects the big toe to the rest of the foot) does not have the appropriate amount of motion required for normal function.  When there is not enough motion available in the first MTP joint, the ground reactive forces are transferred to the lateral, smaller MTP joints.  Most often, it is the second MTP joint that takes the brunt of this force.

If the second toe has a hammer digit deformity, in which the joints of the small toe remain contracted, it can exacerbate the problem.  When a hammer toe is present, the metatarsal head is pointed down towards the ground, or plantarflexed.  This plantarflexed position of the metatarsal adds to the amount of force.  Equinus deformities, in which the ankle joint is tight, can also contribute to the problem by placing additional pressure on the forefoot.  The pain will be especially great when the patient walks down stairs, as they lead with their toes. 

When this second metatarsalgia is present for a long period of time, a condition known as predislocation syndrome may occur.  This is most commonly described in the second toe, though it may be seen in any of the lesser digits.  Predislocation syndrome occurs when the plantar plate, which is a portion of the joint capsule, becomes damaged.  This damage can attenuate, or thin out, the structure.  This attenutation can lead to joint instability, and can cause the second toe to end up pointing upwards and medially or laterally.  Thus, the condition is also sometimes referred to as a crossover toe deformity, as the second toe may overalp the first or third toes. 

The diagnosis of predislocation syndrome is largely made using clinical judgement, though x-rays are necessary to rule out any underlying pathology, such as fractures or complete dislocations.  An MRI may also be ordered, though it is not always necessary.  The MRI will show the ordering physician whether the plantar plate is torn, attenuated, or if there is any other potential pathology causing the deformity. 

Initial treatment typically involves icing the affected area, rest, and the use of non-steroidal anti-inflammatory medications.  Orthotics may be used to manipulate the position of the foot while walking or running, and various strapping and padding methods may alleviate some of the pain. 

Surgery becomes warranted if there is a failure of conservative therapy.  Typically surgery will address any bony deformities of the foot first, such as hammer digits, metatarsals that are functionally too long, or other problems.  In the case of concomitant hallux limitus, procedures of the first MTP joint may be required to restore normal function to that joint and to take pressure off of the second MTP joint. 

When the plantar plate is ruptured or damaged, that too can be repaired with a direct approach.  This has traditionally been done through an approach through the bottom of the foot, though it has recently been described as being repaired through the top of the foot.  


 Central Florida Foot & Ankle Center, LLC 
101 6th Street N.W. 
Winter Haven, FL 33881 
Phone: 863-299-4551