2nd MTP Joint Capsulitis
What is 2nd MTP Joint Capsulitis?
Capsulitis is inflammation of a joint capsule. The second MTP joint is one of the capsules that most commonly experiences inflammation. Each foot possesses five MTP joints that connect your toe bones, or phalanges, with your metatarsal bones—long, thin bones located in your mid-foot.
In our practice we typically see this condition more commonly in women who wear high heel shoes which places increased force on the 2nd MTP. We also see this condition in our runner's who may injury this area of the foot from overuse. Many of the problems and the feet are mechanical. From a mechanical standpoint approximately 50% of the forefoot weight bearing load is carried by the great toe and the bones behind it including the first metatarsal. The remaining 50% is distributed amongst the second third fourth and fifth metatarsals and the corresponding metatarsophalangeal joints (where the toes meet the forefoot) this entire area (MTP joints #1-#5) is also described as "the ball of the foot". A common scenario would be someone who may have a bunion. In the case of a bunion more pressure is taken off the bunion and placed on the ball of the foot which can be a central cause biomechanically of this condition.
Typically the second metatarsal is next in line and receives the brunt of this "stress overload". Over time this increased stress can cause problems including inflammation and pain and eventually damaging the second MTP joint capsule itself. When this damage occurs, often there is resultant misalignment of the second toe whether it starts to drift toward the great toe or starts to contract into what is described as a hammertoe. It is even possible over time for this capsule to completely breakdown and for the second toe to dislocate from the metatarsal head.
Another common cause of capsulitis is a hammertoe contracture which can cause a retrograde buckling of the joint and abnormal pressure on the capsule and related structures.
Pain associated with capsulitis of the second metatarsal phalangeal joint, or the second MTP joint, is felt in the ball of the foot especially near the base of the second and sometimes third or fourth toes. Sometimes there is even swelling in the knuckle behind the second toe. Pain in the second MTP joint is often misdiagnosed as 2nd interspace neuroma. A neuroma is an inflammation of a nerve on the bal of the foot with radiating pain into the lesser digits. Second MTP capsulitis is an inflammation of the ligaments around this joint because of a stress overload and increase weight bearing and a disproportionate manner to this joint.
After the initial physical examination we typically will need an x-ray to evaluate the foot structure. We evaluate potential causes of pain in the second MTP joint area and rule out other potential differential diagnosis considerations such as a stress fracture or arthritis. Diagnostic ultrasound imaging can provide an excellent image of the associated structures including the capsule. But in some of the more difficult cases, we will need MRI evaluation to get a definitive picture and/or assessment of a tear of the capsule. A further sub-category of the capsule is the plantar plate. This can be torn and is also well visualized MRI evaluation.
Because this is a mechanical problem, change in the mechanics of foot function via offloading with pads and prescription orthotics as well as shoe recommendations is an essential first step in treatment. Prescription orthotics can have specific modifications unique to the particular foot and the related pathology. The whole goal is to get the first metatarsal to bear more weight and the second metatarsal less weight. Ice, NSAIDS, topical NSAIDS, cross over taping of the digit, and immoblization with a cam walker boot are other conservative treatment modalities that we can offer our patients.
It is essential that if you have ball of the foot pain to come into either our West Ashley or Mt. Pleasant location to be evaluated and treated. The correct diagnosis is essential in this often overlooked foot condition. In addition if not treated promptly this can lead to a rupture of an important structural component of your foot called the "plantar plate" which often leads to surgical intervention.
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