Dispelling The Myths And Misconceptions About Hallux Rigidus

I recently read a flurry of postings on another podiatric Web site giving advice on a complication from implant arthroplasty of the first metatarsophalangeal joint (MPJ) in a patient with hallux rigidus. I was amazed by the propagation of myths regarding hallux rigidus, metatarsus primus elevatus and the selection of surgical procedures to treat this disorder.

There appears to be no direct causal relationship among first ray “hypermobility,” metatarsus primus elavatus and hallux rigidus. Yet it is common for podiatric physicians to recommend surgical procedures that theoretically plantarflex the first ray to improve range of motion of the first MPJ.

Two excellent studies have suggested that metatarsus primus elevatus is not a predisposing factor for hallux rigidus.1,2 Furthermore, metatarsus primus elevatus appears to develop and worsen as the severity or grade of hallux rigidus increases. In other words, metatarsus primus elevatus appears to be the result, not the cause of hallux rigidus.

Another important study by Cornwall, McPoil and my fellow Podiatry Today blogger William Fishco, DPM, sheds light on further misconceptions about first ray “hypermobility.”3 Contrary to popular belief, patients in this study with a hypermobile first ray did not show increased rearfoot pronation or increased pressure under the second metatarsal.

Roukis understood the clinical significance of these studies and conducted a comprehensive literature review of the subject of hallux rigidus.4 He found no evidence that distal first metatarsal plantarflexion osteotomies actually reduce metatarsus primus elevatus. Studies consistently show that the first ray will maintain alignment to the pre-surgical measurement even after the surgeon plantarflexes first metatarsal via osteotomy. This suggests that forces that we do not fully understand position the first ray.

To the credulous reader who firmly believes that first ray hypermobility is the source of all evil in foot pathologies, let me offer a few insights:

1. Almost all studies of metatarsus primus elevatus are based upon static radiographic measures of the foot. The lateral weightbearing X-ray has no ability to assess first ray function during dynamic gait.
2. We do not have reliable measures of first ray stiffness in the clinical setting. The off-weightbearing exam technique most of us learn was based upon Root’s recommendations, which measured range of motion of the first ray in a static, off-weightbearing position of the foot.
3. We do not have reliable surgical procedures that improve range of motion of the first MPJ. Implant arthroplasty appears to be one of the worst options if one takes a critical look at the literature.

At the same time, I am convinced that the first ray is the most important segment of the human foot. Efforts to improve stability of the first ray almost always result in improvement of function and reduction of symptoms throughout the foot. What remains a mystery is how we can reliably improve stability of the first ray using surgical procedures and foot orthotic therapy.

References
1. Horton G, Park Y, Myerson M. Role of metatarsus primus elevatus in the pathogenesis of hallux rigidus. Foot Ankle Int. 1999; 20(12):777–780.
2. Coughlin MJ, Shurnas PS. Hallux rigidus: demographics, etiology, and radiographic assessment. Foot Ankle Int. 2003; 24(10):731-43.
3. Cornwall MW, McPoil TG, Fishco WD, et al. The influence of first ray mobility on forefoot plantar pressure and hindfoot kinematics during walking. Foot Ankle Int. 2006; 27(7):539-547.
4. Roukis TS. Metatarsus primus elevatus in hallux rigidus: Fact or fiction? JAPMA. 2005; 95(3):221-8.