Hallux Valgus: Is Hypermobility A Cause Or Effect?

Cause.

While this author concedes there is no universal definition of hypermobility and a lack of evidence-based medicine to support hypermobility as a cause or effect of hallux valgus, he cites some research and clinical experience that suggest hypermobility as a possible factor in bunion formation.

By Gary M. Rothenberg, DPM, FACFAS

Does hypermobility cause bunions or did the bunion result in hypermobility? The question is admittedly difficult to answer, mostly because we cannot universally agree on a definition of hypermobility.

   Morton first introduced the concept of hypermobility of the first ray in 1928.1 He postulated that hypermobility of the first ray led to a multitude of foot problems but was the first to admit that there was no reliable method to quantify the magnitude of first ray hypermobility.

   This historic dilemma continued in the subsequent decade when Lapidus introduced the tarsometatarsal fusion in 1934 as a surgical treatment for hallux valgus with associated hypermobility.2 Lapidus believed strongly in hypermobility as a cause of hallux valgus and felt this procedure stabilized and corrected the anatomic deviation.

   The Lapidus bunionectomy fell out of favor for many reasons, most notably complications including delayed unions and nonunions. Through the decades, we have modified and improved our understanding of foot biomechanics, and there have been technological advances in fixation options and surgical techniques. These developments have led us to revisit the indications for the Lapidus procedure for correction of hallux valgus deformity. While many reports dealing with correction of bunion deformities implicate first ray hypermobility as a cause, there is little evidence-based medicine to support hypermobility as either a cause or an effect of hallux valgus.

   Many of us who perform the Lapidus procedure stick to its original indications: larger intermetatarsal half-angles of greater than 15 degrees; obliquity of the first metatarsocuneiform joint; and as a salvage procedure for previously failed correction and hypermobility. However, inherent in our thought processes must be concern for satisfactory long-term outcomes. If the patient is younger and more active, why not fuse that joint in the hopes of a potentially lower recurrence rate?

What The Research Reveals About Hypermobility

Many of our orthopedic colleagues have repeatedly debated hypermobility as a cause of bunions. Coughlin, Myerson and other foot and ankle orthopedists have provided studies supporting the implication of hypermobility causing hallux valgus and the use of the first metatarsal joint fusion as a surgical treatment option for symptomatic hallux valgus.3-6

   In an effort to quantify hypermobility objectively, Klaue and co-workers describe the application of a noninvasive metal caliper to the foot.7 The device is a modified ankle-foot orthosis with an external micrometer to quantify first ray mobility. The authors found measurable, reproducible values for normal and hypermobile first rays. They have concluded that hypermobility is often associated with the development of hallux valgus deformity. Admittedly, the studies have been mostly conducted on cadavers and the device is still not widely utilized or available in the podiatric community.

   The radiograph examination can provide objective information regarding the presence of hypermobility. Once again, dating back to Morton’s 1928 publication on hypermobility, he proposed the most notable evidence of the problem to be a hypertrophy of the second metatarsal diaphysis seen on an AP radiograph.1 Several authors have subsequently debated this issue without arriving at a strong conclusion.8

   Roukis and Landsman expand on the concept that throughout time, practitioners have tried to come up with a definition for hypermobility but have been unsuccessful.9 They point out that the problem begins with the way that various authors have attempted to conduct evidence-based medicine to answer this question.

   Roukis and Landsman say some studies attempt to measure first ray range of motion during open kinetic chain, closed kinetic chain, in vivo, in vitro, through measurement apparatuses and by theory.9 Their conclusion states: “A thorough review of the literature by the authors shows that an accurate and factual definition of hypermobility of the first ray is elusive at best.”

Other Perspectives On Hypermobility As A Possible Causal Factor

To this day, most of us define hypermobility for ourselves clinically. We know a first ray is hypermobile because the excursion during our clinical exam is more than the usual motion we get during a routine bunion examination. Our clinical assessment involves placing the ankle in a neutral position, stabilizing the lateral aspect of the forefoot with one hand and grasping the first ray with the other hand. The physician then translates the ray in a dorsal
and plantar motion until obtaining a soft endpoint.

   Roukis and Landsman estimated that only 10 percent of symptomatic hallux valgus deformity is associated with hypermobility or instability of the first ray.9 As clinicians, we know it when we feel it. It is a strong consideration in our surgical procedure planning.

   As Root keenly recognized, another problem in assessing hypermobility of the first ray is that the sagittal plane motion does not occur in isolation.10 As the first ray dorsiflexes, it inverts. As the first ray plantarflexes, it everts. Thus, Root defined “hypermobility” as abnormal dorsiflexion motion of the first metatarsal head due to instability of the first metatarsal base. The instability of the base is associated either with peroneus longus insufficiency or subtalar joint pronation through the stance phase of gait.

   Both of these biomechanical deficiencies are widely accepted causative factors in the formation of bunions. Here is a simple algorithm to follow.

   Hypermobility → Peroneus Longus Insufficiency + Pronation → Bunion Formation

   Cornwall and colleagues discussed an even more elegant causal pathway linking hypermobility as a cause of hallux valgus.11 This pathway is summarized below.
• During gait, the medial longitudinal arch collapses because of excess dorsal motion of the first ray.
• This collapse decreases the ability of the body to propel forward during gait.
• The increased dorsal excursion causes pronation and the second metatarsal supports excess body weight during propulsion.
• The peroneus longus continues to attempt to stabilize the first metatarsal.
• Joint laxity occurs.
• These mechanical consequences are associated with hallux valgus deformity, excessive pronation, lesser metatarsalgia, flatfoot, posterior tibial tendon dysfunction, plantar fasciitis and shin splints.

In Conclusion

The role of hypermobility of the first ray in the etiology and treatment of hallux valgus is still unclear. Despite multiple attempts to define the term itself, there is currently a lack of universal acceptance on the definition of hypermobility.

   However, when a surgeon clinically decides that there is a component of hypermobility, usually one can address this through a fusion of the tarsometatarsal joint. When one performs the Lapidus procedure correctly, it allows for excellent intermetatarsal angle correction, secure stabilization of the deformity and potentially good long-term results.

   The debate continues but for me, I believe that hypermobility is a cause of hallux valgus.

   Dr. Rothenberg is the Director of Residency Training and an Attending Podiatrist at the Miami Veterans Affairs Healthcare System in Miami. He is a Fellow of the American College of Foot and Ankle Surgeons.

References

1. Morton DJ. Hypermobility of the first metatarsal bone: The interlinking factor between metatarsalgia and longitudinal arch strain. J Bone Joint Surg 1928; 10:187-196.
2. Lapidus PW. Operative correction of the metatarsus varus primus in hallux valgus. Surg, Gynec & Obst 1934; 58:183-191.
3. Coughlin MJ, Jones CP. Hallux valgus and first ray mobility. A prospective study. J Bone Joint Surg Am 2007 Sep; 89(9):1887-98.
4. Smith BW, Coughlin MJ. The first metatarsocuneiform joint, hypermobility, and hallux valgus: what does it all mean? Foot Ankle Surg 2008; 14(3):138-41.
5. Coughlin MJ, Shurnas PS. Hallux valgus in men. Part II: First ray mobility after bunionectomy and factors associated with hallux valgus deformity. Foot Ankle Int 2003 Jan; 24(1):73-8.
6. Myerson MS, Badekas A. Hypermobility of the first ray. Foot Ankle Clin 2000 Sep; 5(3):469-84.
7. Klaue K, Hansen ST, Masquelet AC. Clinical, quantitative assessment of first tarsometatarsal mobility in the sagittal plane and its relation to hallux valgus deformity. Foot Ankle Int 1994 Jan; 15(1):9-13.
8. Faber FW, Kleinrensink GJ, Mulder PG, Verhaar JA. Mobility of the first tarsometatarsal joint in hallux valgus patients: a radiographic analysis. Foot Ankle Int 2001 Dec; 22(12):965-9.
9. Roukis TS, Landsman AS. Hypermobility of the first ray: a critical review of the literature. J Foot Ankle Surg 2003 Nov-Dec; 42(6):377-90.
10. Root ML, Orien WP, Weed JH. Normal and abnormal function of the foot: clinical biomechanics, vol. 2. Los Angeles, Clinical Biomechanics Corp., 1977.
11. Cornwall MW, Fishco WD, McPoil TG, et al. Reliability and validity of clinically assessing first ray mobility of the foot. J Am Pod Med Assoc 2004; 94(5):470-76.

Additional References

12. Rink-Brüne O. Lapidus arthrodesis for management of hallux valgus--a retrospective review of 106 cases. J Foot Ankle Surg 2004 Sep-Oct; 43(5):290-5.
13. Faber FW, Mulder PG, Verhaar JA. Role of first ray hypermobility in the outcome of the Hohmann and the Lapidus procedure. A prospective, randomized trial involving one hundred and one feet. J Bone Joint Surg Am 2004 Mar; 86-A(3):486-95.
14. Lee KT, Young K. Measurement of first-ray mobility in normal vs. hallux valgus patients. Foot Ankle Int 2001 Dec; 22(12):960-4.

Effect.

This author says there is a prevailing lack of validated diagnostic testing methods and clarity on the definition of first ray hypermobility, and also cautions physicians to avoid confusing first ray hypermobility with first ray instability.

By Michael M. Cohen, DPM, FACFAS

I thought this article would be a good opportunity to spark thought by bucking a recent trend advocating the liberal use of the Lapidus procedure in the treatment of the “hypermobile” hallux valgus deformity. Before this discussion can even begin, one has to accept there is no debating that the mere concept of first ray hypermobility is vague at best and one which continues to undergo evolution. In the end, for the discussion to be meaningful, we should clarify pertinent terminology, which may be even more significant than determining the role of hypermobility.

   It was more than 75 years ago that Lapidus and the anatomist Morton described the hypermobile (or dorsally mobile) first metatarsal and listed the myriad of pathology related to the finding.1-3 Hansen, a strong advocate of the Lapidus arthrodesis, emphasized the importance of the first metatarsal, giving specific attention to the function of the first metatarsocuneiform joint.4,5 With respect to arthrodesis, he states, “In a way, the attempt is to complete the evolutionary goal for the ideal foot for a biped. The first metatarsal is the key structure in this effort.”

Does Hypermobility Exist?

Most foot and ankle specialists generally identify with the concept of first ray hypermobility and it is not uncommon for our colleagues to say, “I may not be able to measure it but I know it when I see it.” This “feel” alone for hypermobility has traditionally provided the impetus to perform a first metatarsocuneiform arthrodesis for moderate to severe hallux valgus deformities.

   Yet even if one accepts the concept, it is clear that a concrete description of first ray hypermobility is sorely lacking. It is not surprising then to see that the idea of hypermobility continues to be plagued with controversy and misconceptions.

What Does The Evidence Reveal About First Ray Hypermobility And Hallux Valgus?

Since hypermobility of the first ray is ill defined, our present diagnostic methodologies have yet to be universally validated. Clearly, validation is essential and should be the first step in determining the role of first ray hypermobility and foot pathology. Traditionally, clinicians have relied on manual assessment in a static environment by gauging dorsal excursion of the first ray in the sagittal plane. One can do this by evaluating the first metatarsal position relative to the second metatarsal by placing the ankle and subtalar joints in a neutral position. We have recently recognized that attempts to validate this technique using experienced examiners have proven to be futile and subsequently deemed grossly unreliable.

   Glasoe and colleagues investigated the relationship between static and dynamic first ray sagittal excursion.6 The study concluded that static observation of first ray mobility is a poor indicator of abnormal first ray function during gait and the concurrent assessment of windlass function is necessary to predict insufficiency.

   Investigators suspect that the majority of hypermobility associated with hallux valgus is in the transverse plane and sagittal static excursion does not reliably replicate first ray function.7,8 In this scenario, the subluxed metatarsophalangeal joint is functioning out of its axis and is unable to engage the windlass mechanism. It would be easy then for the examiner to incorrectly deduce that hyperexcursion of the metatarsal is secondary to joint hypermobility. Christensen and colleagues recognized the significance of transverse instability and stressed that first ray function demands a complex and intricate interplay of ligaments, tendons and muscles.7

   In 2000, Rush and Christensen introduced the “windlass activation test” via a clever modification of Root’s method.8 In this test, one performs manual assessment of sagittal first ray excursion in conjunction with a dorsiflexed hallux. The technique theoretically simulated the action of the first ray during late mid-stance and propulsion by engaging the windlass mechanism and enhancing the detection of instability (as opposed to hypermobility). They stressed that transverse plane instability appears to be an essential pathomechanical component of hallux valgus deformity.

   In 2003, Roukis and Landsman recommended an essentially identical method of manual testing they termed the “dynamic Hicks test,” which is complemented with live imaging.9 Unfortunately, manual stress tests lead to a gross assessment, are unvalidated and difficult to perform if the deviated hallux is manually irreducible.

   Unreliable testing methods prompted the development of external mechanical devices. Klaue pioneered one of these devices and Glasoe later introduced a similar device.10,11 Although these devices appeared to provide a more accurate measurement of first metatarsal displacement, they too had shortcomings. To begin with, first ray motion is triplanar yet these devices essentially test uniplanar excursion and, like manual techniques, evaluated sagittal displacement only. Their inception, however, began with the hopes of setting the stage for enhanced evidence based research.

   Unfortunately, a recent study published by Cornwall and colleagues refuted some of these diagnostic modalities.12 In an effort to investigate the reliability and validity of first ray mobility, three clinicians examining 60 asymptomatic feet indicated poor clinical agreement using traditional static assessment and poor correlation with a device constructed to Glasoe’s specifications.

   Jones and Coughlin consequently validated the Klaue caliper in 2005.13 Using the device, Coughlin and Jones subsequently investigated the incidence of first ray hypermobility in moderate to severe hallux valgus deformities.14 The investigators discovered that the presence of first ray hypermobility was indeed greatly exaggerated. The finding was consistent with others using various testing methods.

   Regardless, given the premise that first ray hypermobilty coexists with hallux valgus, it is difficult to determine whether hypermobility has a secondary or causal role, or is the primary etiology. Unfortunately, prospective studies linking the two and proving cause and effect are limited.

   Perhaps the most convincing prospective piece of evidence refuting hypermobility of the first ray as a cause of hallux valgus came from Coughlin and Jones.14 In 2007, the authors published a level IV study evaluating 103 patients (122 feet) with moderate to severe hallux valgus, 23 of whom demonstrated hypermobility using the Klaue device. All feet underwent a proximal crescentic osteotomy with distal soft tissue realignment and follow-up lasted an average of 27 months. All 23 hypermobile feet consistently reduced to a normal sagittal excursion range after the procedure. The authors concluded, “We believe that increased sagittal mobility of the first ray occurs as a result of hallux valgus deformity and (is) not the cause of that deformity.”

Have We Blamed The Wrong Culprit?

Even if one accepts the cause and effect theory, it still fails to explain why not all patients with first ray hypermobility have hallux valgus and why those without first ray hypermobility also get the deformity. The simple answer is that one should not confuse first ray hypermobility with first ray instability. They are not one and the same. As Blitz aptly stated, “while the first ray may be hypermobile, it may be functionally stable.”15 Palladino astutely pointed out several years ago that even a non-hypermobile first ray may be dynamically unstable with pronation.16

   We must realize that hypermobility is not necessarily a pathological entity. Rather, the true determining factor in establishing proper first ray function is predicated on the foot’s ability to convert the medial column into a stable lever arm during late mid-stance and propulsion. Failure to accomplish this chain of events correctly results in instability, which is often translated as metatarsophalangeal joint pathology. Simply stated, hallux valgus subsequently develops if instability is predominantly in the transverse plane and hallux limitus/rigidus ensues if instability is sagittally oriented. The culprit therefore is first ray instability, not hypermobility.

Is The Lapidus Arthrodesis The Best Option For First Ray Instability?

Bear in mind the fact that first ray motion is not isolated to the metatarsocuneiform joint but is the result of a combination of movement occurring at multiple levels, beginning proximally as far as the talonavicular joint and extending distally to include the intercuneiform joints. Lundgren, Rolling and their respective colleagues have disputed the notion that motion centers around the first metatarsocuneiform joint.17,18 They determined that the majority of first ray motion occurs at the naviculocuneiform joint.

   With this in mind, even if first ray hypermobility is thought to be a significant etiological factor of hallux valgus, one wonders whether an isolated metatarsocuneiform arthrodesis would be an appropriate surgical solution. Proponents of the procedure feel that regardless of etiology, the Lapidus procedure and/or its various modifications would be most effective in controlling first ray hypermobility (instability) while providing the best long term outcome. The jury remains out on this issue and is a topic for further discussion.

In Conclusion

One should be especially cautious when relying upon clinical testing to diagnose hypermobility as our present diagnostic tools have proven to be inefficient indicators. Moreover, first ray hypermobility is not necessarily a pathological entity. Rather, one would best describe the condition, if pathological, as functional first ray instability.

   In this setting, the exaggerated motion is likely secondary to the inability of the first ray to engage the windlass mechanism as the metatarsal head escapes the joint pocket medially. Current studies suggest that proper realignment of the first ray restores normal joint anatomy and re-establishes a functionally stable first ray with normal mobility. Perhaps in time, we will witness the concept of hypermobility, as it relates to hallux valgus, devolve and the concept of instability evolve.

   With this in mind, corrective procedures may ultimately be directed at addressing the specific dynamic and static etiologies of first ray instability, and prompt the development of clear-cut indications for the Lapidus arthrodesis. Regardless of this debate, the fact that there is still much more work to be done is indisputable and the issue will undoubtedly continue to challenge foot and ankle specialists for years to come.

   Dr. Cohen is the Chief of Podiatric Surgery at the Miami Veterans Affairs Medical Center in Miami. He is a Fellow of the American College of Foot and Ankle Surgeons.

References

1. Lapidus PW. Operative correction of the metatarsis primus varus in hallux valgus. Surg Gynecol Obstet 1934; 58: 183-91.
2. Morton DJ. The human foot. Columbia University Press; 1935.
3. Morton DJ. Hypermobility of the first metatarsal bone; the interlinking factor between metatarsalgia and longitudinal arch strains. J Bone Joint Surg 1928; 10:187-96
4. Hansen ST. The first metatarsal: its importance in the human foot. Clin Pod Med Surg July 2009; 26(3):351-4.
5. Hansen ST Jr. Hallux valgus surgery. Morton and Lapidus were right. Clin Pod Med Surg 1996 Jul; 13(3):347-54.
6. Glasoe WM, Allen MK, Ludewig PM. Comparison of first ray dorsal mobility in relation to hallux valgus deformity and first intermetatarsal angle. Foot Ankle Intl 2001; 22:98-101
7. Christensen JC, Meagan JM. Normal and abnormal function of the first ray. Clin Pod Med Surg July 2009; 26(3):355-371.
8. Rush SM, Christensen JC, et al. Biomechanics of the first ray. Part II;metatarsus primus varus as a cause of hypermobility. A three dimensional kinematic analysis in a cadaver model. J Foot Ankle Surg 2000; 39(2):68-77.
9. Roukis TS, Landsman AS. Hypermobility of the first ray: a critical review of the literature. J Foot Ankle Surg 2003 Nov-Dec; 42(6):377-390.
10. Klaue K, Hansen ST, Masquelet AC. Clinical quantitative assessment of first tarsometatarsal mobility in the sagittal plane and it’s relation to hallux valgus deformity. Foot Ankle Int 1994; 15(1):9-13.
11. Glasoe VM, Yack HJ, Saltzman CL. The reliability and validity of a first ray measurement device. Foot Ankle Int 2000 Mar; 21(3):240-6.
12. Cornwall MW, Fishco WD, McPoil TG, et al. Reliability and validity of clinically assessing first-ray mobility of the foot. J Am Pod Med Assoc Sept/Oct 2004; 94(5):470-476
13. Jones CP, Coughlin MJ, Pierce-Villadot R, et al. The validity and reliability of the Klaue device. Foot Ankle Int 2005 Nov; 26(11):951-6.
14. Coughlin MJ, Jones CP. Hallux valgus and first ray mobility, a prospective study. J Bone Joint Surg (Am) 2007; 89(9):1887-98.
15. Blitz NM. Current concepts in medial column hypermobility. Pod Today 2005; 18(6):68-79.
16. Palladino S. Preoperative evaluation of the first ray in hallux abductovalgus and hallux limitus. In (Gerbert J, ed.): Textbook of Bunion Surgery. WB Saunders Co., Philadelphia, 3rd edition, 2000.
17. Lundgren P, Nester C, Liu A, et al. Invasive in vivo measurement rear-, mid and forefoot motion during walking. Gait Posture 2008; 28(1):93-100.
18. Rolling BA, Christensen JC, Johnson CH. Biomechanics of the first ray. Part IV; the effect of selected medial column arthrodesis. A three dimensional analysis in a cadaver model. J Foot Ankle Surg 2002 Sep-Oct; 41(5):278-85.