Open vs Arthroscopic First Metatarsophalangeal (MTP) Joint Fusion
Authors: Viner Gean C. , Abyar Eildar , Moraes Leonardo , McKissack Haley , Pinto Martim , He Jun Kit , Naranje Sameer M. , Shah Ashish 
Published: October 2019

Category:

Arthroscopy, Basic Sciences/Biologics, Midfoot/Forefoot

Introduction/Purpose:

First metatarsophalangeal (MTP) joint fusion has been proven to be an effective treatment for a variety of conditions such as osteoarthritis, rheumatoid arthritis, hallux rigidus/valgus, and failed first MTP arthroplasties. Multiple surgical techniques have been described in the literature with regards to bone preparation and different fixation with varying degrees of success. Studies have demonstrated that one of the complications of MTP fusion is first ray shortening, which can lead to symptomatic forefoot disorders such as transfer metatarsalgia of the lesser toes. Patients can develop altered gait mechanics that manifest as decreased ankle plantarflexion at toe-off and decreased step gait. The purpose of this study was to compare the amount of first ray shortening that occurs during MTP fusions with open versus arthroscopic technique.

Methods:

Ten specimens were divided into two groups. Group one was arthroscopic and group two was open technique. For arthroscopy, the long extensor (EHL) tendon and first MTP joint were identified. Dorsomedial and dorsolateral ports were created at the level of the MTP joint. A small curette was used to prepare the joint. For open technique, an incision was made on the dorsum of the first MTP joint and carried down to the subcutaneous tissue. The EHL tendon was dissected and a capsulotomy was performed. The head of the first metatarsal and the base of the proximal phalanx were exposed. Dome-shaped reamers were used to prepare the joint. A lag screw was used for fixation. AP and lateral radiographs were obtained. The length of the first ray was measured from the base of the first metatarsal to the distal end of the proximal phalanx. Pre and post fixation lengths were compared.

Results:

A comparison of pre and post fixation first ray length demonstrated that there was an average decrease of 2.2 mm in the arthroscopic group and 2.1 mm in the open technique group. Even though both techniques shortened the average length of the first ray, there was no statistically significant difference between the groups (p = 0.934). Comparison of the average percentage of surface area prepared of the head of the first metatarsal showed a statistically significant difference (p = 0.035) between both techniques. In contrast, comparison of the average percentage of surface area prepared of the base of the proximal phalanx and total surface area prepared did not show a statistically significant difference (p = 0.159 and p = 0.051) between the groups.

Conclusion:

First metatarsophalangeal (MTP) joint fusion has been proven to be an effective treatment for a variety of conditions that affect the first ray. First ray shortening can lead to symptomatic forefoot disorders and altered gait patterns. The results of our study indicate that there is no statistically significant difference in first ray length after MTP fusion performed by either arthroscopic or open technique. Our study also showed that even though the average percentage of surface area prepared of the head of the first metatarsal was statistically different between both groups the average percentage of total surface area prepared was not.