Arthritis of the second and third tarsometatarsal joints can be a challenging condition to manage. Clinically, patients present with pain, stiffness and swelling located at the dorsal midfoot. Many patients also have a painful lump on the top of the foot, which makes it difficult to wear a closed shoe.
Younger patients who present with this condition tend to have had a traumatic event. Older folks are the most common demographic with this diagnosis, which is typically due to wear and tear.
The reasons why this condition is hard to manage are threefold.
• The condition is often associated with a high arch/curved foot type (pes cavus with metatatarsus adductus).
• It typically affects geriatric patients.
• It can be a challenge to get these patients to wear supportive lace-up shoes because of the pain caused by the dorsal bony prominence.
I am sure our treatment protocols are similar. I may recommend using doughnut pads and/or alternating the lacing pattern on the shoe to avoid the bump, using non-steroidal anti-inflammatory drugs (NSAIDs) or occasional cortisone injections. I may suggest orthotic devices to reduce arch sag and strain on the tarsometatarsal joints and may recommend surgery as a last resort.
Orthotics are a tough sell. Patients are already reluctant to wear a closed-in shoe because of pressure on the dorsal lump. Orthotics are going to raise the foot in the shoe and result in a tighter fit.
Many of the geriatric patients cannot tolerate NSAIDs or are already taking them for other arthritic conditions. Cortisone injections can reduce inflammation for a period of time but certainly cannot resolve the problem. Moreover, we can only give a limited number of injections.
From a surgical standpoint, the knee-jerk response is to remove the exostosis and perform a fusion of the joint or joints. In older patient, it is tricky for them to be non-weightbearing for six weeks. Arthroplasty is ideal for older patients with low activity demand. I liken it to a Keller bunionectomy of the great toe joint. I do not like the Keller procedure in active people but it is perfect for a sedentary patient.
We know the fourth and fifth tarsometatarsal joints do not fare well with fusion and that arthroplasties have been advocated for many years. In the right patient, an arthroplasty in the second and third tarsometatarsal joints may be very effective in resolving arthritis pain. The simplest thing to do is to resect just enough of the base of the metatarsal to decompress the joint. You can test this with intraoperative sagittal plane motion of the metatarsal. Once there is no rubbing of the two bones, you have resected enough bone.
The most difficult part of the joint resection is making sure you do not leave a plantar ledge, which is hard to see. If you leave a ledge, then the arthritis pain will not resolve. The use of a mini-joint distractor can be helpful to visualize the plantar aspect of the joint. You can also consider implant arthroplasty using a ceramic sphere as we do in the fourth and fifth tarsometatarsal joints. Others have tried using soft tissue xenografts and allografts to act as a spacer. The grafts can oftentimes extrude from the joint or cause a loose body reaction. I tend to avoid that technique. Keeping it simple whenever possible is best.
I have seen a fair amount of non-unions of the second and third tarsometatarsal joint fusions. Technically, this fusion seems pretty simple but these are small joints and there is very little room for error in preparation of the fusion site. We often forget about the dowel fusion. The calcaneus is a great source for autogenous bone. By performing a dowel fusion, there is inherent stability of the fusion site due to intact ligamentous tissue. Aggressive dissection is not necessary. Assuming that the alignment of the joint is acceptable, the dowel fusion can be a way to reduce your non-union rate. You can use a compression staple for fixation, which simplifies matters.
Typically, one is working in tight quarters with the neurovascular bundle in the neighborhood. Using a plate and screws in this area seems to be more complicated. With a plate and screws, there is added potential to violate intercuneiform joints and there is need for added dissection to provide more exposure.
This is yet another example of a seemingly simple clinical problem that challenges us on a daily basis.