Addressing Hallux Rigidus In The Presence Of Metatarsus Primus Elevatus

Author(s): 
Boyd J. Andrews, DPM, and Lawrence M. Fallat, DPM, FACFAS

Given the common nature of hallux rigidus and the challenges of concomitant metatarsus primus elevatus, these authors share key diagnostic insights, explore possible surgical options and discuss two illuminating case studies. 

Hallux rigidus is degenerative arthritis of the first metatarsophalangeal joint (MPJ) and is the most common form of osteoarthritis of the foot.1 Hallux rigidus is characterized as a progressive condition that causes a severely painful and rigid great toe joint, leading to debilitating pain.2    

There is debate as to the exact etiology of hallux rigidus. Some state that inadequate shoe gear and a tight Achilles tendon are to blame.3,4 Authors have also suggested that hallux rigidus can occur due to hypermobility of the first ray, immobilization of the first ray, an excessively long first metatarsal, an elevated first ray, degenerative joint disease or trauma.5,6    

McMaster postulated that a subchondral defect develops on the articular surface of the first metatarsal head, causing a subchondral lesion. This lesion is also located beneath the dorsal lip of the proximal phalanx of the hallux. If jamming continues, degenerative changes will lead to joint narrowing, flattening of the first metatarsal head and the development of osteophytes.7 The hallux needs to dorsiflex 65 to 70 degrees for normal locomotion.5,7,8 The patient’s gait may become antalgic as the MPJ stiffens and there is a transfer of weight to the lateral border of the foot.9    

Lambrinudi originally described the theory of an elevated first metatarsal as a variation in the sagittal plane of the first ray being elevated in relation to the lesser metatarsals.6 The etiology of metatarsus primus elevatus is either structural or functional. Structural etiology occurs from a congenital malformation or first metatarsal fracture, usually toward the base of the metatarsal. Functional elevatus is due to some form of muscle or biomechanical imbalance, or a combination of both. The peroneus longus is the prime stabilizer of the first ray and any interference with the peroneus longus resulting in paralysis or weakness will lead to the onset of functional elevatus.10

Essential Diagnostic Insights

Initially, patients complain of pain localized to the first MPJ, often with a history of an arthritic condition secondary to injury.9,11 Patients with a complaint of acute onset of symptoms need evaluation for gout, calcium pyrophosphate dihydrate crystal deposition disease, septic arthritis, stress fracture of the sesamoids and soft tissue masses. Early hallux rigidus consists of pain only at the end range of motion while patients with end-stage hallux rigidus may be pain-free due to ankylosis of the first MPJ. The most common finding on physical examination is a dorsal bunion.9,11    

Radiographic evaluation of hallux rigidus should include dorsoplantar, lateral and oblique views of the foot.9 X-rays usually show dorsal osteophytes at the head of the metatarsal, joint space narrowing, subchondral cyst formation and sclerosis. During early stages, these findings are confined to the dorsal aspect of the joint but extend as the disease continues to spread. It is necessary to evaluate the parabola of the metatarsal and specifically the length of the first metatarsal. Lateral views show dorsal osteophytic spurring but this view tends to underestimate the size.9,11 Radiographic findings are characteristic of arthritic changes of the joint.12    

The radiographic relationship between hallux rigidus and elevatus is a subject of debate due to a lack of agreement on the appropriate measurement between the first and second metatarsal. Some authors have evaluated elevatus by measuring the distance from the dorsal distal metaphyseal flare of the first metatarsal to the dorsal aspect of the second metatarsal perpendicular to the ground.2,13-15    

Comments

I am surprised by your emphasis on surgical correction of metatarsus primus elevates (MPE). Both Coughlin and Horton, referenced in your article, clearly show that MPE is a result of, not a cause of hallux rigidus. Futhermore, there is no evidence that so-called "plantarflexion osteotomies" actually end up positioning the head of the first metatarsal in a more plantarflexed alignment relative to the 2nd metatarsal in the post-operative weightbearing lateral radiograph. The goal and benefit of these osteotomies is to decompress the 1st MTP, which indirectly reduces MPE. Otherwise, kudos to you for writing a very good overview of the challenges of treating this enigmatic condition.

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