Hallux Rigidus
Mark M. Casillas, MD and Margaret Jacobs, PT

Clinical Background
The term hallux rigidus describes a limited arthrosis of the first MTP joint. The first MTP joint and the great toe (hallux) provide significant weight transfer from the foot to the ground as well as active push-off. An intact first MTP joint implies a complete and pain-free ROM, and full intrinsic and extrinsic motor strength.

The first MTP joint ROM is variable. The neutral position is described by 0 (or 180) degrees angulation between a line through the first metatarsal and a line through the hallux (Fig. 5–61). Dorsiflexion, the ROM above the neutral position, varies between 60 and 100 degrees (Fig. 5–62A). Plantar flexion, the ROM below the neutral position, varies between 10 and 40 degrees (see Fig. 5–62B). The ROM is noncrepitant and painfree in the uninjured joint.

Two sesamoid bones (the medial, or tibial, sesamoid and the lateral, or fibular, sesamoid) provide mechanical advantage to the intrinsic plantar flexors by increasing the distance between the empirical center of the joint and the respective tendons.

Hallux rigidus is an arthritic condition limited to the dorsal aspect of the first MTP joint. Also known as a dorsal bunion or hallux limitus, the condition is most commonly idiopathic (but may be associated with posttraumatic OCD of the metatarsal head) and is characterized by an extensive dorsal osteophyte and dorsal third cartilage damage and loss. An associated synovitis may further aggravate the limited and painful ROM.

A foot with increased first ray ROM and increased pronation may be predisposed to the condition. Excessive flexibility of the shoe forefoot increases the potential for hyperdorsiflexion of the hallux MTP joint (Fig. 5–63). For this reason, this type of shoewear should be avoided.

Classification of Hallux Rigidus
A useful classification system grades clinical and radiographic findings from mild to end stage (Table 5–6).

Diagnosis
Clinical Examination
Patients with hallux rigidus complain of dorsal pain, swelling, and stiffness localized to the hallux MTP joint. The sitting examination may reveal decreased ROM in dorsiflexion and, to a lesser degree, in plantar flexion. The ROM becomes more and more painful as the condition advances. Forced dorsiflexion reveals an abrupt dorsal bony block associated with pain. Also, forced plantar flexion produces pain as the dorsal capsule and the extensor hallucis longus tendon are stretched across the dorsal osteophyte. The dorsal osteophyte is easily palpable and typically exquisitely tender.

Radiographic Evaluation
Standard radiographic evaluation includes AP and lateral views of the weight-bearing foot (Fig. 5–64). Bone scanning, CT, and MRI are capable of demonstrating the condition, but these are not part of a routine work-up.
The differential diagnosis of hallux rigidius is shown in Table 5–7.

Treatment
The treatment of hallux rigidus is symptom-based. Acute exacerbations are treated with the RICE (rest, ice, compression, and elevation) method followed by a gentle ROM program and protected weight-bearing. The chronic condition is treated with a ROM program and protected weight-bearing. The hallux MTP joint is supported by shoe modifications (e.g., rocker bottom sole), a rigid shoe insert (Fig. 5–65), a stiff-soled shoe, or various taping methods that resist forced dorsiflexion (Fig. 5–66). A soft upper and deep toe box reduce pressure over the dorsal osteophyte. The joint is also protected by reducing activity levels, increasing rest intervals and duration, and avoiding excessively firm play surfaces. Occasionally, a patient with excessive pronation will benefit from an antipronation orthotic. NSAIDs and cold therapy are used to reduce swelling and inflammation. Occasionally, corticosteroid injection to the MTP joint is used as an adjunctive therapy.

Operative treatment is indicated for symptoms that fail to respond to a reasonable period of well-supervised conservative management (Fig. 5–67). Hallux MTP débridement and exostectomy are standard treatment for hallux rigidus. Ideally, the intraoperative and postoperative passive ROM approaches 90 degrees of dorsiflexion. If the arthrosis is extensive and this ROM not obtainable, a dorsiflexion osteotomy may be added to the surgical repair. The osteotomy is designed to place the functional ROM of the hallux within the newly established pain-free arc of motion. Patients with severe findings must be warned that outcomes become less predictable with advanced stages. CT images are useful in discriminating between severe hallux rigidus and frank degenerative joint disease. A hallux arthrodesis (fusion) is a more predictable reconstruction method for the most advanced cases of hallux rigidus. Pain relief is provided at the expense of permanent loss of joint motion.

Authors’ Recommended Treatment (Figure 5–68)
The acutely swollen and painful hallux rigidus is treated with the RICE method for several days. For chronic conditions, a stiff-soled shoe with a soft upper is prescribed along with a rigid low-profile carbon insert. We often rocker-bottom the shoe. NSAIDs and ice are used as adjunct to reduce inflammation. Adequate rest and recovery are scheduled with increasing frequency and duration. If symptoms persist, or if the patient presents with moderate to severe findings, a hallux rigidus repair is considered. Adequate débridement and soft tissue release are done to achieve 90 degrees of intraoperative dorsiflexion. If the joint is globally affected (hallux arthrosis), a hallux arthrodesis is performed.

Nonoperative Rehabilitative Treatment of Hallux Rigidus
Occasionally, hallus rigidus is associated with a synovitis that is improved with nonoperative treatment. Fundamental to the protocol is the prevention of recurrent injury by limiting dorsiflexion of the hallux MTP with appropriate shoewear, rigid shoe inserts, or taping. Taping (by the trainer) is useful in athletic events, but is limited by time-related failure and the poor results with self-application. Off-the-shelf devices are readily available, and custom devices can be used for difficult sizes or specialty shoewear. The phases of rehabilitation are variable in length and depend completely on the reestablishment of ROM and resolution of pain. Flexibility is emphasized throughout the protocol.