The goal of this clinical trial is to investigate the relationship between Hallux Abductus Valgus (HAV) and the hyperextension of the Extensor Hallucis Longus (EHL) tendon. The study aims to understand the efficacy of MIS surgery in treating foot deformities like HAV and to evaluate the impact of EHL tendon hyperextension on this condition.

The main questions this study aims to answer are:

• How does the hyperextension of the EHL tendon correlate with the presence and severity of HAV?
• What is the effectiveness of MIS surgery in correcting HAV deformities and addressing issues related to EHL tendon hyperextension? Participants in this study will undergo pre-surgical evaluation to assess the severity of HAV and measure the extent of EHL tendon hyperextension using pressure platform analysis and other relevant clinical measures. During the MIS surgery, participants will receive treatment targeted at correcting HAV, possibly involving partial tenotomy.

If there is a comparison group: Researchers will compare individuals who undergo MIS surgery for HAV correction with a control group not receiving this intervention. The comparison aims to assess the effects of MIS surgery on both HAV correction and the relationship between EHL tendon hyperextension and the deformity.

This study endeavors to shed light on the relationship between HAV and EHL tendon hyperextension, the effectiveness of MIS surgery in addressing these issues, and potentially pave the way for improved surgical techniques in treating foot pathologies.

Main Objective: To analyze the effectiveness of incomplete zig-zag tenotomy of the EHL combined with minimally invasive foot surgery for the correction of moderate and severe hallux abducts valgus (HAV).

Secondary Objectives:

Compare pre-surgical and post-surgical plantar pressure changes. Determine American Orthopaedic Foot & Ankle Society Scale (AOFAS scale) values pre-surgery and post-surgery.

Compare the improvement in post-surgical results of angles: HAV, Intermetatarsal Angle (AIM),Proximal Articular Set Angle (PASA),Distal Articular Set Angle(DASA), and the metatarsophalangeal angle of the first ray (lateral projection).

Materials and Methods: The chosen study design is an experimental, controlled, non-randomized, longitudinal, analytical, and prospective study. Subjects meeting the selection criteria will be non-randomly assigned to two different groups: the "Minimally Invasive Surgery Group with Zig-zag EHL Tenotomy" and the "Minimally Invasive Surgery Group without Zig-zag EHL Tenotomy." After surgery, a follow-up with radiological control will be performed, where post-surgical angles will be measured and plantar pressures will be evaluated.

Results: The investigators expect to achieve effective and safe lengthening of the long hallux extensor in all patients with HAV and hyperextension of the first toe.

Conclusions: The study results will indicate that zig-zag tenotomy of the long hallux extensor is a safe, effective, and rapid technique.

Inclusion Criteria:

• Pain in the metatarsophalangeal joint of the big toe caused by HAV.
• Moderate and severe Hallux Abductus Valgus.
• Incorrect metatarsal shape of the 2nd, 3rd and 4th rays due to HAV.
• Be between 20 and 90 years old.
• Patients with no osteoarthritis.

Exclusion Criteria:

• Patients who have previously undergone surgery for Hallux Abductus Valgus.
• Pregnant patients.
• Patients with coagulopathies, diabetes or risk disease (ASA lll, ASA lV).
• Patients with high-risk pharmacological treatments.

The target population for this project is men and women between 20 and 90 years old with hallux abductus valgus and the first toe in hyperextension on one or both feet. The subjects in the sample will be patients undergoing surgery in private clinics who come for consultation at the time of the study. The method to select the sample is non-probabilistic due to the inclusion of volunteers.