Challenging A Myth About The Cause Of Hallux Rigidus
Last month, Podiatry Today featured an excellent article written by Boyd Andrews, DPM, and Lawrence Fallat, DPM, focusing on surgical correction of metatarsus primus elevatus and hallux rigidus.1 (See https://www.podiatrytoday.com/addressing-hallux-rigidus-presence-metatarsus-primus-elevatus .) While this article provides a good comprehensive review of hallux rigidus, I was surprised by the emphasis on metatarsus primus elevatus as a causative factor in this condition. I had written a reply to the authors right before the article moved off the home page so I thought I would restate my observations and opinion about the role of metatarsus primus elevatus and hallux rigidus.
When I was a podiatric medical student in the late 1970s, we universally accepted that metatarsus primus varus caused hallux valgus deformities and metatarsus primus elevatus caused hallux rigidus. While many studies have dispelled both notions, I am surprised how many colleagues continue to teach, write and lecture on the subject of hallux rigidus and focus on the importance of reducing metatarsus primus elevatus.
While clinically we can push up on the first metatarsal head and observe immediate reduction of dorsiflexion of the first metatarsophalangeal joint (MPJ), we assume this same process has occurred in the pathogenesis of hallux rigidus, resulting in jamming and subsequent osteoarthritis of this joint. Yet excellent studies of patients with various stages of hallux rigidus have shown there is no cause-effect relationship among hypermobility of the first ray, metatarsus primus elevatus and hallux rigidus.2-4
Coughlin and Sharma studied 110 patients with hallux rigidus and found no association among hallux rigidus, first ray hypermobility and metatarsus primus elevatus.2 In addition, studies by Horton, Bouaicha and their respective colleagues showed that metatarsus primus elevatus increases as the severity of hallux rigidus increases but both authors stated that metatarsus primus elevatus was the result of rather than the cause of hallux rigidus.3,4
While these studies may be a bit confounding, it is even more interesting to look at the results of surgery intended to correct or reduce metatarsus primus elevatus when treating hallux rigidus. Distal metaphyseal osteotomies such as the Green-Waterman and the modified Youngswick procedures do not end up reducing metatarsus primus elevatus even though they purposely plantarflex the first metatarsal head.5-7 Clearly other factors are in play that not only cause metatarsus primus elevatus but also cause hallux rigidus.
Elevation of the first ray can be the result of hindfoot positioning, which distal osteotomies of the first metatarsal head do not affect. Pronation of the subtalar joint will increase ground reaction forces on the first ray, causing dorsiflexion at either the first metatarsal-medial cuneiform joint or the navicular-cuneiform joint. Another observed phenomenon is that painful jamming of the first MPJ causes a compensatory hallux equinus (plantarflexion), which then leads to a reciprocal elevation of the first metatarsal.8
Finally, it is almost universally agreed that soft tissue constraints around the first MPJ, including the plantar aponeurosis and the flexor hallucis longus tendon, are primary contributors to both hallux limitus and hallux rigidus.9 Osteotomies intending to treat hallux rigidus by plantarflexing the first metatarsal actually achieve their success by decompressing the first MPJ and relieving the soft tissue constraints around the joint.10
For the clinician evaluating and treating hallux rigidus, simply relying on a lateral weightbearing radiograph will not give accurate information about the true etiology or give a solution to the condition. While the distal metaphyseal first metatarsal osteotomy continues to be a preferred treatment for early stages of hallux rigidus, these procedures are well known to have potential complications that can be irreversible.7 Since we cannot reduce metatarsus primus elevatus with plantarflexion osteotomies alone, perhaps we need to look at other solutions to decompress the first MPJ to relieve symptoms of hallux rigidus.
Thus, despite recent research and insights into hallux rigidus, we are still seeking the perfect surgical solution for this enigmatic condition.
References
1. Andrews BJ, Fallat LM. Addressing hallux rigidus in the presence of metatarsus primus elevatus. Podiatry Today. 2014; 27(9):46-54.
2. Coughlin MJ, Shurnas PS. Hallux rigidus: demographics, etiology, and radiographic assessment. Foot Ankle Int. 2003; 24(10):731–743.
3. Horton GA, Park YW, Myerson MS. Role of metatarsus primus elevatus in the pathogenesis of hallux rigidus. Foot Ankle Int. 1999; 20(12):777-80.
4. Bouaicha S, Ehrmann C, Moor BK, et al. Radiographic analysis of metatarsus primus elevatus and hallux rigidus. Foot Ankle Int. 2010; 31(9):807-814.
5. Laakmann G, Green RM, Green DR. The modified Waterman procedure: A preliminary retrospective study. In Camasta C (ed.): Reconstructive Surgery of the Foot and Leg: Update ’95, The Podiatry Institute, Tucker, GA, 1995, p. 128.
6. Dickerson JB, Green R, Gren DR. Long-term follow-up of the Green-Waterman osteotomy for hallux limitus. J Am Podiatr Med Assoc. 2002; 92(10):543-54.
7. Roukis TS, Jacobs PM, Dawson DM, et al. A prospective comparison of clinical, radiographic, and intraoperative features of hallux rigidus: short-term follow-up and analysis. J Foot Ankle Surg. 2002; 41(3):158-65.
8. Roukis TS. Metatarsus primus elevatus in hallux rigidus: fact or fiction? J Am Podiatr Med Assoc. 2005; 95(3):221-228.
9. Kriane YM, Michelson JD, Sharkey NA. Contribution of the flexor hallucis longus to loading of the first metatarsal and first metatarsophangeal joint. Foot Ankle Int. 2008; 29(4):367-77.
10. Malerba F, Milani R, Sartorelli E, Haddo O. Distal oblique first metatarsal osteotomy in grade 3 hallux rigidus: a long-term followup. Foot Ankle Int. 2008; 29(7):677-682.
