Hallux rigidus is a common condition encountered by foot and ankle surgeons. It was originally described in 1887 as condition affecting the great toe causing stiffness and pain.¹ The first metatarsophalangeal (MTP) joint is one of the most common joints affected by degenerative changes with almost 8% of adults reporting symptomatic hallux rigidus in their lifetime and radiographic evidence of arthritis present in at least 27% of adults over 50 years.²,³,⁴

Drs. Coughlin and Shurnas described their classification system of hallux rigidus and recommended that, when nonoperative treatment fails, mild grade 1 and 2 cases can be treated with cheilectomy and arthrodesis considered for higher grades.⁵ However, recently, there has been realization that the radiographic imaging and classification grades do not necessarily correlate with patient’s symptoms and treatment options.⁶,⁷

In general, patients with severe arthritis of the joint with limited motion and pain in the mid arc of motion typically correlate to grades 3 and 4 on the Coughlin classification.⁵ Open arthrodesis has been the traditional gold standard treatment for these patients with excellent longterm reported outcomes and function.⁸,⁹,¹⁰ Minimally invasive (MIS) surgical techniques offer a new approach to treat forefoot pathologies with the potential to limit postoperative wound complications and pain.¹¹ The first reported minimal incision first MTP joint fusion was in 1999 as case report of a successful arthroscopic-assisted MTP joint fusion.¹² Since then, the role of arthroscopy in foot and ankle conditions as well as the authors’ understanding of the anatomy, safe zone, and portal placement has expanded, and the first MTP joint arthroscopy and minimally invasive forefoot surgery have become much more common.¹²,¹³,¹⁴,¹⁵,¹⁶,¹⁷,¹⁸,¹⁹,²⁰,²¹,²²,²³

As foot and ankle surgeons gain MIS experience with bunion correction, cheilectomy, and metatarsal osteotomies, these skills are readily applicable to joint fusions. Hallux rigidus, one the most commonly treated degenerative foot and ankle conditions, coupled with the relatively simple anatomy of the first MTP joint allow the benefits of MIS to be applied to one of the most commonly performed foot surgeries. This chapter will describe the technique of MIS fusion of the hallux MTP joint. Results from early case series demonstrate 93% to 97% fusion rates with low complications, indicating that this is a promising surgery that could benefit many pati ents.¹²,¹⁴,¹⁶,²²,²⁴,²⁵,²⁶

Patients often present with pain and stiffness at the first MTP joint with or without deformity. There may be a history of trauma, but typically, there is no inciting event that the patient recalls. Usually, the pain is worse with actions involving toe dorsiflexion and loading across the MTP joint, such as the push-off phase of gait. Similarly, stairs, running, and plank position during activities such as yoga or push-ups may cause discomfort.⁸,¹⁰,²⁹

When there is a large dorsal osteophyte, there may be tenderness due to impingement in shoes. The dorsal medial cutaneous nerve will course over the spur and may be a source of additional pain if stretched over the spur with plantarflexion of the toe, and there is often evidence of neuritis with a positive Tinel sign at the site.³⁰ The patient may also report lateral foot discomfort due to abnormal gait patterns in an effort to off-load the painful hallux MTP joint. Finally, evaluating the pain with range of motion is one of the most important deciding factors. If the patient has pain at the mid arc of motion or with axial loading of the joint in the mid position, this likely indicates a loss of cartilage in the central joint, and in those cases, a fusion as opposed to a cheilectomy will be more beneficial as discussed above.