Can a Midtarsal (MTP) fusion help stabilize a nonunion at the midfoot?

From the Guidelines

Yes, an MTP fusion can help stabilize a nonunion at the midfoot in certain clinical scenarios, particularly when there is instability of foot and ankle joints, and/or deformity with a high-risk of developing ulcer in the offloading device, or pain that cannot be sufficiently stabilised in a Total Contact Cast or a non-removable knee-high device, as suggested by the guidelines on the diagnosis and treatment of active charcot neuro-osteoarthropathy in persons with diabetes mellitus (iwgdf 2023) 1.

Key Considerations

• The procedure involves surgically fusing the joint between the metatarsal bone and the proximal phalanx, which can provide additional stability to the midfoot region by reducing motion and redistributing weight-bearing forces.
• The fusion creates a rigid lever that can offload stress from the nonunion site, potentially allowing it to heal.
• Proper patient selection is crucial, as this approach is more appropriate for older, less active patients or those with significant midfoot instability rather than younger, highly active individuals.

Surgical Approach

• The surgical approach typically involves removing the remaining cartilage from the joint surfaces, preparing the bone ends, and securing them with hardware such as screws, plates, or staples.
• Postoperatively, patients usually require 6-8 weeks of non-weight bearing followed by a gradual return to protected weight bearing in a walking boot for another 4-6 weeks.

Success Rates

• Success rates are generally good, with fusion rates of 85-95% reported in the literature, though patients should understand that the procedure permanently eliminates motion at the fused joint, which may alter gait mechanics.

Recommendation

• The decision to perform an MTP fusion should be made on a case-by-case basis, taking into account the individual patient's needs and circumstances, and considering the potential benefits and risks of the procedure, as well as the availability of alternative treatment options 1.

From the Research

MTP Fusion and Nonunion Stabilization

• The provided studies do not directly address the use of MTP fusion to stabilize a nonunion at the midfoot.
• However, studies 2 and 3 discuss the treatment of nonunion after first metatarsophalangeal joint arthrodesis, which may be relevant to understanding nonunion treatment in general.
• Study 2 suggests that removal of hardware and debridement alone can be an alternative treatment option for nonunion after hallux metatarsophalangeal joint fusion.
• Study 3 identifies risk factors for nonunion after first MTP joint arthrodesis, including male gender, comorbidity, higher grade of osteoarthritis, and increased postoperative great toe dorsiflexion.

Alternative Treatment Options for Nonunion

• Studies 4, 5, and 6 discuss the use of implantable bone stimulators and combined magnetic field bone growth stimulation as treatment options for nonunion.
• These studies suggest that these methods can be effective in promoting bone healing and achieving union in patients with nonunion.
• For example, study 5 reports an overall success rate of 84% with a mean time to union of 6.62 months using combined magnetic field bone growth stimulators.
• Study 6 reports a healing rate of 75% with a weighted mean time to heal of 4.9 months using combined magnetic field bone growth stimulation.