Biomechanics
May 2000

Sports Medicine:
Conservative approach benefits athletes with hallux valgus

By Joseph P. Laluya, DO, Terry Nicola, MD, and Sarah McDade, MD

As more people participate in sports and extend this interest into the later decades of life, we are seeing an increasing number of hallux-valgus-related injuries. Historically, hallux valgus has been treated with surgical intervention. However, as our experience with and knowledge about the condition increases, a noninvasive therapeutic approach warrants consideration.

Hallux valgus presents as lateral deviation of the great toe and medial deviation of the first metatarsal bone. Commonly, the deformity is characterized by progressive subluxation of the metatarsophalangeal joint.¹

Etiology

Although inappropriate or constricting footwear appears to be the primary extrinsic cause of hallux valgus, intrinsic factors play a role as well. Mann and Coughlin⁵ reported that pes planus has some influence on bunion formation, while Inman⁶ and Hohmann⁷ both suggested hindfoot pronation as a major cause of this process. An increased angle between the first and second metatarsals (metatarsus primus varus) is often associated with a hallux valgus deformity. Hardy and Clapham⁸ reported an association between the magnitude of the hallux valgus angle and the magnitude of the first/second intermetatarsal angle, and stated that metatarsus primus varus is secondary to an increased hallux valgus angle. Other intrinsic causes of hallux valgus include contracture of the Achilles tendon, generalized joint laxity, hypermobility of the first metatarsocuneiform joint, and neuromuscular disorders (including cerebral palsy and stroke).¹ Heredity is also thought to be a factor in the development of hallux valgus deformity. Hardy and Clapham⁸ noted that 57 (63%) of the 91 patients in their series had a parent with a hallux valgus, and Coughlin¹ reported that a bunion was identified in 29 (94%) of 31 mothers of children who had hallux valgus.

Anatomy

The abductor and adductor hallucis tendons are located on the medial-plantar and lateral-plantar aspects, respectively, of the metatarsophalangeal joint and insert into the base of the proximal phalanx and the adjacent sesamoids. The plantar part of the metatarsophalangeal joint capsule is reinforced by the tendons of the abductor hallucis and adductor hallucis, while the dorsal half of the metatarsophalangeal capsule is comparatively thin and has no tendinous constraints. With the development of hallux valgus, the abductor hallucis tendon is displaced plantarly, leaving only the center and the weaker, dorsal half of the capsule as the major restraining force on the medial aspect¹ (Figure 2).

With the development of hallux valgus, the adductor hallucis, with its insertion into the lateral plantar aspect of the base of the proximal phalanx and lateral sesamoid, becomes a deforming force. The adductor hallucis tends to tether the sesamoids and proximal phalanx as the first metatarsal deviates medially. Because it inserts on the plantar aspect of the proximal phalanx, the adductor hallucis also exerts a rotational force on the great toe, rotating it in a counterclockwise fashion as the phalanx deviates laterally (Figure 3). With further hallux valgus deformity, the extensor hallucis longus displaces into the first inner space and exerts an adduction force on the great toe.⁹

With continued rotation of the great toe, the medial and lateral sesamoids become displaced in relation to the plantar surface of the first metatarsal. With a severe hallux valgus deformity, the lateral sesamoid migrates to the lateral aspect of the first metatarsal head and lies vertically dorsal to the medial sesamoid.¹

Angular measurements are best obtained with standing radiographs, including anteroposterior, lateral, and axial (sesamoid) views. The hallux valgus angle is formed by the intersection of the longitudinal axes of the proximal phalanx and the first metatarsal. The average deviation in adults is up to 15° and is considered normal (Figure 4). The first/second intermetatarsal angle is formed by the intersection of the longitudinal axes of the first and second metatarsals, and an angle of less than 9° is considered normal (Figure 4). With the use of these measurements, a general classification scheme for hallux valgus was developed.

A mild hallux valgus deformity is characterized by a hallux valgus angle of more than 15° and less than 20° and a first/second intermetatarsal angle of more than 9° and less than 11° (Figure 5A). Subluxation of the lateral sesamoid, as measured on an axial radiograph, is less than 50%. A moderate deformity is characterized by a hallux valgus angle of 20° to 40°, a first/second intermetatarsal angle of 11° to 16°, and 50% to 75% subluxation of the lateral sesamoid (Figure 5B). A severe deformity is characterized by a hallux valgus angle of more than 40°, a first/second intermetatarsal angle of 16° or more, and more than 75% subluxation of the lateral sesamoid (Figure 5C).¹

History And Physical Examination

Physical evaluation of the athlete with hallux valgus is performed with the patient first sitting and then standing. Weight-bearing will often accentuate any deformity. It is important to note biomechanical abnormalities such as pes planus, pes cavus, or contracture of the Achilles tendon, as well as any neuromuscular abnormalities. Neurologic evaluation is also important for assessment of sensation, motor strength, and control. Evaluating the athlete while walking or running on a treadmill may reveal significant gait abnormalities. In my experience, a combination of posterior tibialis weakness, pes planus, pronation, and hallux valgus deformity is a common finding.

With hallux valgus, functional motion at the first metatarsophalangeal joint is often greatly reduced. The increased force generated in the forefoot can approach 250% of body weight while running compared to 80% while walking.⁴ As can be imagined, significant functional motion loss at the first metatarsophalangeal joint may significantly impair an athlete’s performance.

Lastly, the physical examination, including radiographs, should identify any other lesser toe abnormalities such as claw- and hammertoes. Dorsal subluxation and/or dislocation of the second toe are common findings in moderate to severe hallux valgus deformities.

Treatment

Initial treatment should address not only the hallux valgus deformity but other biomechanical and/or gait pattern alterations as well. A conservative approach must first address pain and joint function. Pain can be lessened with inflammation-reducing measures such as ultrasound, icing after exercise, heat, and the use of anti-inflammatory medications. Athletic activities should be modified to reduce the amount of forefoot propulsion; acceleration, hill running, cutting, kicking, and kneeling activities should be limited.¹¹ A transition to activities such as rowing, cycling, swimming, and deep water running should be encouraged.

As pain is reduced, the practitioner should focus on restoring normal biomechanics of the lower extremities. Mobilization to address soft tissue contracture, namely significant limitations in dorsiflexion and plantar flexion of the first metatarsophalangeal joint, should be initiated early. We suggest a great toe stretch (Figure 6), which involves long access distraction with slight lateral glide or varus deviation, to reduce the subluxation. If rotation has occurred at the phalanx, then counter-rotation should follow. This is accomplished by manually holding the great toe and applying counterforce to reduce the rotatory mechanics. The great toe is then placed into either dorsiflexion or plantar flexion with pressure applied over the flexor hallucis longus or extensor hallucis longus tendon, respectively. This stretch is held for approximately 30 seconds and should be repeated three to four times daily. A similar approach may be applied for second-toe dorsal subluxation. The toe or toes are manipulated into plantar flexion with pressure applied over the extensor tendon contracture to provide sufficient stretching.

Weakness, including intrinsic foot and leg muscle strength, should be addressed simultaneously. Resistance exercises for the ankle with an elastic band or tubing and barefoot calf raises off a step edge can be helpful. Progression of repetitions for each exercise depends on initial strength and the presence of next-day pain. Toe curl exercises may also prove beneficial.

Athletic shoes should provide ample room and motion control, particularly for pronation. Shoes may need to be modified so the toebox height can accommodate bony exostoses. As a temporary measure, this portion of the shoe may be cut away for pressure relief. Biomechanical foot orthoses may be useful for reducing excessive pronation, which causes oblique stresses across the first metatarsophalangeal joint. I use firm but pliable material such as cork and leather or PTB for orthoses. Pes cavus- or pes planus-type feet should be accommodated with prominent medial arching or posting, respectively. Metatarsal head relief should be considered along with a prominent premetatarsal arch support, which often reduces dorsal subluxation of the lesser toes. In cases of significant flexor hallucis longus and/or tibialis posterior tendinitis or ankle synovitis, plastic ankle foot orthoses may be prescribed. Lastly, splinting may reduce initial symptoms and (Figure 7) reduce progression. Night splints, such as moldable toe spacers are the most aggressive, whereas athletic taping is more practicable for daytime and athletic use.

Success in treating hallux valgus should be gauged not only by the ability to satisfactorily resolve the athlete’s complaint of pain and loss of function, but also to do so in a timely fashion. Conservative treatment within a supervised program should provide a significant response within two to five weeks. As the athlete returns to specific sports-related activity, we recommend that an exercise program that includes stretching and strengthening, two to three times per week, be maintained.

References

1. Coughlin MJ. Hallux valgus. In: American Academy of Orthopaedic Surgeons, eds. Instructional course lectures, vol. 78-A(6):932-966. Boise, ID: The American Academy of Orthopaedic Surgeons, 1996.
2. Coughlin MJ, Thompson FM. The high price of high-fashion footwear. In: The American Academy of Orthopaedic Surgeons, eds. Instructional course lectures, vol. 44:371-377. Rosemont, IL: The American Academy of Orthopaedic Surgeons, 1995.
3. Kato T, Watanabe S. The etiology of hallux valgus in Japan. Clin Orthop 1981;157:78-81.
4. Lam SF, Hodgson AR. A comparison of foot forms among the non-shoe and shoe wearing Chinese population. J Bone Joint Surg 1958;40A:1058-1062.
5. Mann RA, Coughlin MJ. Hallux valgusýetiology, anatomy, treatment and surgical considerations. Clin Orthop 1981;157:31-41.
6. Inman VT. Hallux valgus: a review of etiologic factors. Orthop Clin North Amer 1974;5:59-66.
7. Hohmann G. Fuss und Bein. 4th ed. Munich, Germany: J.F. Bergmann, 1948:167.
8. Hardy RH, Clapham JCR. Observations on hallux valgus. Based on a controlled series. J Bone Joint Surg 1951;33-B(3):376-391.
9. Coughlin MJ. Hallux valgus. Causes, evaluation, and treatment. Postgrad Med 1984;75:174-187.
10. Lutter LD. Forefoot abnormalities in runners. Presented at the 18th annual meeting of the American Orthopaedic Foot and Ankle Society, February 1988.