When Second MPJ Overload Occurs Without Hammertoe Deformity
It is not uncommon to see one patient every day on my practice schedule who has pain and inflammation of the second metatarsophalangeal joint (MPJ). While there are cases that involve a hammertoe associated with metatarsophalangeal joint pain, what are the options for treating patients who have pain in the second metatarsophalangeal joint but do not have a hammertoe deformity? When it comes to cases of so-called “capsulitis of the second MPJ,” we try all kinds of different therapy with little consideration of a proper diagnosis and diagnostic testing. Furthermore, we never develop a true treatment plan for such a problem. With this in mind, let us take a closer look at this condition. The patient who commonly presents to my practice is between the ages of 35 and 50 and has either acute or more chronic onset of pain in the second MPJ. The pain tends to be subtle and increasing with mild fullness of the ball of the foot and mild tenderness to pressure on the second MPJ plantar aspect. There is often pain with high heels and hard-soled shoes but these patients may also experience pain with flat shoes. Patients commonly note that the pain has gradually increased with time and they often have a limp when they present to my office. While there is no history of trauma, these patients tend to experience pain with every step and it is not associated with a specific time of day or event during the day. The pain does seem to get worse with increased activity. One may also note some mild swelling of the plantar surface of the ball of the foot with mild erythema. While there is no gross hammertoe deformity, one may note some mild laxity of the joint with dorsal drawer testing. There is no varus or valgus deviation of the second toe but there is often a very mild dorsal contracture of the toe with an extensor contracture to the second digit. Clinicians may often note an underlying hallux valgus deformity with a mild to moderate deformity that is not a severe cause of pain. The patient may have mild to moderate laxity of the first ray and a slight equinus deformity that is more associated with a tight gastrocnemius muscle than the actual Achilles tendon itself. There is also no callus in the plantar aspect of the second metatarsal head.
Emphasizing Key Diagnostic Steps
When evaluating these patients, our first step is obtaining radiographs of the feet. If there is any question of ankle deformity or possible impingement of the ankle contributing to the equinus problems, we also take radiographs of the ankle. We take all films with the patient in full weightbearing in order to achieve a proper foot and ankle position and base of gait. We review the films to ensure there is no stress fracture or metatarsal overload fracture, bone tumor, signs of avascular necrosis or cartilage defect of the metatarsal head. Radiographs are particularly useful for checking the alignment of the foot, the length of the first through third metatarsals and the parabola of the forefoot. I often add a plantar axial image if there is gross hypermobility of the first ray and have the X-ray shot in such a way to see if there is a first ray elevatus versus a generalized forefoot varus. This is an essential part of the general biomechanical workup. I often pursue an ultrasound examination of the foot in my diagnostic examination of these patients. This enables me to check the plantar plates of the metatarsal heads for laxity and drawer, gross tear and also for the laxity of the joint. I also check the interspaces for any signs of a soft tissue mass or neuroma formation in the region. If I identify a neuroma, I treat it accordingly. However, for the purposes of this article, let us assume there is no neuroma. It is very easy to check the plantar plate and one must treat a tear or partial tear accordingly. However, in most cases, one will not see a tear and the only finding is laxity of the joint with easy dorsal motion of the digit to 80 or 90 degrees dorsiflexion.