Can a Metatarsal Phalangeal (MTP) fusion catalyze bone growth at a mid-foot nonunion?

From the Guidelines

MTP fusion is not a recommended procedure to catalyze bone growth at a mid-foot nonunion, as it targets a different anatomical area and does not directly address the nonunion site. When considering the treatment of mid-foot nonunions, the primary goal is to achieve osseous union and restore structural integrity to the affected area. According to the provided evidence, surgical reconstruction for active Charcot neuro-osteoarthropathy (CNO) includes realignment arthrodesis, tendon lengthening, tendon transfer, or partial ostectomy of a prominent bone (exostectomy) 1. However, these procedures are specific to CNO and may not be directly applicable to mid-foot nonunions.

Key Considerations for Mid-foot Nonunions

• The standard approach for treating mid-foot nonunions involves debridement of the nonunion site, bone grafting, and internal fixation with plates, screws, or staples.
• Biological adjuncts like bone morphogenetic proteins (BMPs) or bone marrow aspirate concentrate may be used to enhance healing potential.
• A period of non-weight bearing for 6-12 weeks is often recommended, depending on radiographic evidence of healing.

Limitations and Risks

• Surgical intervention in CNO is associated with high complication rates, including amputation, hardware removal, wound dehiscence, acute kidney injury, pneumonia, and surgical site infection 1.
• The decision to use external or internal fixation is highly dependent on the surgeon's preference and experience.

Recommendation

In the context of mid-foot nonunions, a procedure that directly targets the nonunion site, such as debridement, bone grafting, and internal fixation, is recommended over MTP fusion. It is essential to weigh the potential benefits of surgical intervention against the risks and consider a shared decision-making process with the patient, taking into account their individual circumstances and the expertise of the surgeon 1.

From the Research

MTP Fusion and Bone Growth

• The use of teriparatide, a parathyroid hormone (PTH) analogue, has been shown to induce union in cases of delayed union and nonunion, including in the foot and ankle region 2, 3.
• A study on the effects of teriparatide on fusion rates in patients undergoing complex foot and ankle arthrodesis found that the fusion rate was significantly greater in the teriparatide treatment group than in the control group (100% vs 50%) 2.
• Another study found that daily subcutaneous injection of teriparatide 20 μg is a potential new safe treatment for delayed union and nonunion, with 95.3% of subjects developing complete union 3.

Nonunion After MTP Joint Arthrodesis

• A retrospective study on the risk analysis of nonunion after first metatarsophalangeal joint arthrodesis found that the nonunion rate was 9.2%, and that negative influencing factors included the presence of preexisting diseases, higher grades of osteoarthritis, and a relative increased dorsiflexion position of the great toe after surgery 4.
• Another study found that the difference in fusion rates between males (17.5%) and females (3.8%) was significant, suggesting that gender may be a factor in nonunion rates after MTP joint arthrodesis 5.

Teriparatide Treatment

• Teriparatide treatment has been shown to be effective in promoting bone growth and union in cases of delayed union and nonunion, including in the foot and ankle region 6, 2, 3.
• The use of teriparatide may help avoid repetitive surgeries, especially in atrophic delayed and nonunions, as well as in patients with impaired fracture healing undergoing bisphosphonate therapy 6.