How do I treat a metatarsal transfer lesion?
The forefoot is designed to work as a unit. With each step, the multiple bones of the forefoot are intended to distribute load bearing in an equal distribution. In theory, each metatarsal head should carry an equal amount of load. A metatarsal transfer lesion occurs when one metatarsal head carries more than its fair share of load. As a result of this increase in focal load bearing, a number of conditions can occur:
There are a number of reasons that metatarsal transfer lesions occur, but the most common reason is foot surgery. Surgery on the first metatarsal, such as bunion surgery, hallux limitus or hallux rigidus surgery, can result in disproportionate load bearing of the forefoot. If the outcome of these surgeries results in elevation or shortening of the first metatarsal, a transfer lesion beneath the second metatarsal head is a common outcome.
In cases of a transfer lesion sub 2, what I find interesting is how the second metatarsal responds. The increased load to the second metatarsal can result in two outcomes.
In cases where the transfer lesion results in an abrupt, increased load to the second metatarsal, we'll often see the body self-correct this eccentric load by creating a stress fracture of the second metatarsal. This secondary stress fracture often results in resolution of the transfer lesion. In other cases, the second metatarsal will 'step up to the plate' and increase in size to accommodate this new load. Unfortunately, this often results in a chronic problem with load bearing in the forefoot. The most common problem is chronic capsulitis beneath the second metatarsal head.
How can a transfer lesion be treated? First and foremost, the surgeon who performs the 1st metatarsal surgery should be keenly aware of the potential for transfer lesions and perform a surgery that does not result in shortening or elevation of the first metatarsal. But even in cases with the best surgeons, transfer lesions still happen. Treatment options for transfer lesions include:
- Metatarsal pads
- Rx orthotics with metatarsal pads, metatarsal bars or a pocket sub 2
- Metatarsal osteotomy
If you experience pain beneath the second metatarsal head following bunion or hallux limitus surgery, be sure to speak with your surgeon about treatment options. Although an unfortunate outcome of some forefoot surgeries, transfer lesions are usually a problem that can be treated and corrected.