How does Midtarsal (MTP) fusion improve foot function?

From the Guidelines

MTP fusion significantly improves foot function by stabilizing the first metatarsophalangeal joint, thereby providing pain relief and enhancing weight-bearing capability. This is based on the most recent and highest quality study available, which discusses various surgical interventions for foot ulcers in persons with diabetes 1. The study highlights the importance of stabilizing the foot to promote healing and prevent further complications.

Key Benefits of MTP Fusion

• Provides significant pain relief by eliminating painful motion at the joint
• Improves weight-bearing capability, allowing for more normal walking patterns
• Creates a rigid lever for push-off during gait, restoring normal walking mechanics
• High satisfaction rates among patients due to reliable pain relief and functional improvement

Considerations for MTP Fusion

• Typically recommended for conditions like severe hallux rigidus (arthritis), hallux valgus (bunion deformity), or joint instability
• Requires 6-12 weeks of protected weight-bearing with a post-operative shoe or boot, followed by gradual return to regular footwear
• Sacrifices motion at the MTP joint, but this loss is often compensated by increased motion at nearby joints
• May not be suitable for activities requiring significant toe flexion, such as running

Comparison with Other Interventions

• The study 1 also discusses other surgical interventions, such as Achilles tendon lengthening and metatarsal head resection, which may be considered for foot ulcers in persons with diabetes
• However, MTP fusion is a viable option for stabilizing the first metatarsophalangeal joint and improving foot function, particularly in cases where non-surgical offloading interventions have failed.

From the Research

MTP Fusion and Foot Function

• MTP fusion aims to eliminate pain resulting from end-stage arthritis and obtain a stable, plantigrade first toe, which can lead to improved foot function 2.
• The procedure can correct associated deformities and fill greater defects with interposition autograft or allograft, resulting in better foot function 2.
• Studies have shown that MTP fusion can improve foot function, with success rates of approximately 90% in medium-term results 2.
• Normal walking and running are possible after MTP1 fusion, with the first ray mobility being essentially in the interphalangeal (IP) joint with a compensatory hypermobility in dorsal flexion 3.

Improvement in Foot Function

• Foot function improved for 23 (79%) patients after MTP joint arthrodesis, as measured by the Foot Health Status Questionnaire (FHSQ) 4.
• The FHSQ foot function scores improved for 93% of patients, and 72% of patients reported improved physical activity after arthrodesis of the first MTP joint 4.
• A study using the Dutch Foot Function Index (FFI) found that the median FFI score improved from 38 to 8 after MTP joint fusion, indicating improved foot function 5.
• Another study found that 75.88% of patients reported being able to wear any type of shoe most or all the time after the operation, suggesting improved foot function 6.

Correlation between Foot Function and Hallux Position

• There was no correlation between postoperative foot function, dorsiflexion angles, and hallux valgus angles, suggesting that foot function is not directly related to hallux position 5.
• The desired position of the hallux was most often achieved, which could be a reason for the lack of correlation between foot function and hallux position 5.