These authors argue that first ray hypermobility is a result of a bunion deformity and not its cause, and assert that the term “instability” is more accurate.
Hallux valgus deformity is a common pathologic forefoot condition that continues to be a large part of the podiatric practice. When asked about the etiology of a bunion deformity, physicians’ responses variously include foot type, shoes, hypermobility, genetics, abnormal anatomy and numerous other reasons, but the true etiology of hallux valgus is ambiguous at best. Many of the proposed etiologies are theories and have little support in the available literature.
The idea of hypermobility and the function of the first tarsometatarsal joint factoring into the formation of hallux valgus deformities is a notion that some believe. Physicians typically discuss hypermobility as sagittal plane motion and this has been an area of controversy and much debate.
In 1928, Morton first described hypermobility at the first tarsometatarsal joint as cause of further forefoot deformity but never associated the presence of hypermobility with the development of hallux valgus deformity.1 In 1934, Lapidus proposed the association of hypermobility with hallux valgus deformity and determined a first tarsometatarsal joint fusion was an appropriate means to stabilize the hypermobile joint and definitively correct the bunion deformity.2 Neither author quantified mobility of the first ray or specifically mobility of the first tarsometatarsal joint, and the term hypermobility went undefined.
These authors discussed the idea of hypermobility, which led to many studies discussing the use of the Lapidus bunionectomy to address hypermobility of the first tarsometatarsal joint in hallux valgus deformities.1,2 Physicians diagnosed hypermobility with a subjective maneuver, which entailed using one hand to stabilize the lesser metatarsal heads and putting the first metatarsal through plantar and dorsal translation while holding the ankle in a neutral position. At this point, one would estimate the dorsal displacement to determine the mobility of the first tarsometatarsal joint.
A Closer Look At Recent Research On Hypermobility
In a series that involved 15 patients and three practitioners, Glasoe and coworkers looked at the inter-rater reliability of this manual maneuver, which they did not find to be reliable between providers in the assessment of first ray mobility.3 The available studies rarely quantify hypermobility preoperatively or postoperatively to justify use of the Lapidus procedure.4
Dayton and colleagues developed a device to quantify first ray mobility and they defined hypermobility as 8 mm or more of sagittal translation.5 They found an association between hypermobility and hallux valgus deformity when comparing the use of the device on those with the deformity and the control group made up of people with normal feet. Other studies used the Klaue device or other methods such as radiography and fluoroscopy to establish the association of hypermobility and hallux valgus deformities.6 These studies primarily used cadaver limbs and no studies have isolated the first tarsometatarsal joint in determining hypermobility.
Faber and colleagues demonstrated that the first tarsometatarsal joint is responsible for roughly 57 percent of the sagittal plane motion of the first ray while the remaining motion is from the naviculocuneiform and talonavicular joints.7 The study authors compared 10 patients with normal feet to 10 feet diagnosed with hallux valgus through the use of weightbearing computed tomography (CT) evaluation and 3D reconstruction of those images. Kimura and colleagues observed significant displacement at the first tarsometatarsal joint, but also noted displacement along the first ray and medial column with loading of the foot.8
This should lead us to think critically about hypermobility as the etiology of bunion formation. Should we be fusing the entire medial column to achieve the absolute best results in regard to bunion correction? Obviously, this is not the answer. There is increased mobility in the first ray in patients who have hallux valgus deformities. The aforementioned studies found an association of hypermobility and hallux valgus deformity, but could not determine whether this was a cause or result of the bunion deformity.
Is First Ray Hypermobility The Result Of The Bunion Rather Than The Cause?
More recently, emerging literature supports the idea that hypermobility of the first ray is possibly the result of the bunion deformity, not the cause.
Kim and colleagues looked at preoperative and postoperative hypermobility for 82 patients having a proximal chevron osteotomy and distal soft tissue release. The sagittal plane translation decreased from 6.8 mm to 3.2 mm at one year postoperative.9 In a prospective study looking at 122 feet with hallux valgus and hypermobility, Coughlin and Jones looked at the results of a proximal osteotomy and distal soft tissue release at a mean follow-up of 27 months.10 First ray mobility reduced from 7.5 mm to 4.2 mm. All studies noted a positive association between the mobility of the first ray in the sagittal plane and coronal plane deformity. Authors have also noted that procedures sparing the first tarsometatarsal joint led to a decrease in hypermobility in the sagittal plane, leading them to speculate that the sagittal instability is a result of the hallux valgus deformity.9–11
The objective measurement of hypermobility has not been reproducible and studies rarely define or cite quantified measurements of hypermobility.11,12 Roukis and Landsman further stated “there is no consensus for hypermobility’s definition or clinical evaluation, no proven causation with pathology, and no meaningful influence on surgical procedure selection.”12
The concept of hypermobility may exist as a result of a bunion but this should not be the focus of the practitioner as it is significantly decreased after bunion correction, regardless of surgical procedure.
Through the available literature and more recent studies, hypermobility of the first ray leading to hallux valgus deformities is an overused term and diagnosis. Joint hypermobility syndrome is defined by abnormal laxity in multiple joints in association with symptomatic joint pain.13 Scher and colleagues estimated the prevalence of hypermobility in hallux valgus deformities as 0.06 per 1,000 person-years, making the incidence of hypermobility with hallux valgus uncommon.
The term hypermobility is best reserved for pediatric populations and those who truly have a hypermobile joint as would be the case with connective tissue disorders. The term instability (rather than hypermobility) may be better suited to describe the resultant excessive sagittal plane motion along the first ray in hallux valgus deformity.
Regardless of the term clinicians use to describe the excessive mobility, surgical correction of the hallux valgus deformity stabilizes the first ray, whether the surgeon performs an Austin osteotomy, scarf osteotomy, first metatarsophalangeal joint arthrodesis or a Lapidus procedure. Without further research in the form of a large prospective study on the diagnosis of hypermobility and appropriate treatment outcomes, the theory of hypermobility will remain a myth.
Dr. Waverly is a Fellow with the Weil Foot and Ankle Institute in Des Plaines, Ill. He is an Associate of the American College of Foot and Ankle Surgeons.
Dr. Haller is a Fellow with the Weil and Foot Ankle Institute. She is an Associate of the American College of Foot and Ankle Surgeons.
Dr. Weil is the President and Fellowship Director of the Weil Foot and Ankle Institute. He is a Fellow of the American College of Foot and Ankle Surgeons.
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. Glasoe WM, Allen MK, Saltzman CL, Ludewig PM, Sublett SH. Comparison of two methods used to assess first-ray mobility. Foot Ankle Int. 2002; 23(3):248–252.
4. Bednarz PA, Manoli A 2nd. Modified Lapidus procedure for the treatment of hypermobile hallux valgus. Foot Ankle Int. 2000; 21(10):816-21.
5. Dayton P, Kauwe M, Feilmeier M. Is our current paradigm for evaluation and management of the bunion deformity flawed? A discussion of procedure philosophy relative to anatomy. J Foot Ankle Surg. 2015; 54(1):102-111.
6. Dietze A, Bahlke U, Martin H, Mittlmeier T. First ray instability in hallux valgus deformity: a radiokinematic and pedobarographic analysis. Foot Ankle Int. 2013; 34(1):124-130.
7. 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; 22(12):965-969.
8. Kimura T, Kubota M, Taguchi T, Suzuki N, Hattori A, Marumo K. Evaluation of first-ray mobility in patients with hallux valgus using weight-bearing CT and a 3-D analysis system: a comparison of normal feet. J Bone Joint Surg. 2017; 99(3):247-55.
9. Kim J, Park JS, Hwang SK, Young KW, Sung IH. Mobility changes of the first ray after hallux valgus surgery: clinical results after proximal metatarsal chevron osteotomy and distal soft tissue procedure. Foot Ankle Int. 2008; 29(5):468-472.
10. Coughlin MJ, Jones CP. Hallux valgus and first ray mobility. a prospective study. J Bone Joint Surg. 2007; 89(9):1887-98.
11. Doty JF, Coughlin MJ. Hallux valgus and hypermobility of the first ray: facts and fiction. Int Orthop. 2013; 37(9):1655-1660.
12. Roukis TS, Landsman AS. Hypermobility of the first ray: a critical review of the literature. J Foot Ankle Surg. 2003;42(6):377-390.
13. Scher DL, Owens BD, Sturdivant RX, Wolf JM. Incidence of joint hypermobility syndrome in a military population: Impact of gender and race. Clin Orthop Rel Res. 2009; 468(7):1790-1795.
14. Coughlin MJ, Jones CP. Hallux Valgus: demographics, etiology, and radiographic assessment. Foot Ankle Int. 2007; 28(12):759-777.
15. Coughlin MJ, Smith BW. Hallux valgus and first ray mobility. J Bone Joint Surg. 2008; 90(Suppl 2 Pt 2):153-170.
16. Greisberg J, Sperber L, Prince DE. Mobility of the first ray in various foot disorders. Foot Ankle Int. 2012; 33(1):44-49.
17. Smith BW, Coughlin MJ. The first metatarsocuneiform joint, hypermobility, and hallux valgus: What does it all mean? Foot Ankle Surg. 2008; 14(3):138-141.
18. Van Beek C, Greisberg J. Mobility of the first ray: review article. Foot Ankle Int. 2001; 32(9):917-922.
These authors cite evidence of hypermobility’s relationship to hallux valgus and maintain that addressing hypermobility can be beneficial in bunion repair without having an adverse effect on the biomechanics of the first ray.
Bunion surgery is likely the most common surgery performed on the foot, yet there remains significant controversy as to what exactly causes bunions to develop in the first place. Generally, podiatrists would agree that a combination of genetic and environmental factors is to blame, but pinpointing what these genetic factors actually are and their percentile contribution to hallux valgus remains somewhat of a mystery.
First ray hypermobility remains at the center of this controversy despite what I believe is overwhelming clinical evidence of its relationship to hallux valgus and a variety of other foot problems.
Hypermobility itself is a dividing subject for podiatrists: either one believes in it or not. This seems to stem from the fact that hypermobility is hard to measure clinically and therefore its definition is ill-defined. The best definition of hypermobility is excessive motion and the adage “you know it when you see it” seems to be appropriate. Surgeons don’t particularly like ambiguity. Testing for hypermobility involves measuring the overall sagittal plane excursion of the first ray as a whole and in relation to the lesser metatarsal level. More than 1 cm is considered abnormal but this may not be clinically significant.1
The presence of hypermobility, however, is not always pathological and therefore one should consider only using the term pathological hypermobility when it is combined with clinical disorders that are a product of this hypermobility. An unstable first ray can contribute to bunions, hammertoes, metatarsalgia, plantar plate tears, lesser metatarsal stress fractures and flat feet. While it is true that hypermobility can be present without a bunion, its presence is very common, especially in the face of larger bunions.
A Closer Look At Triplanar Motion In Hallux Valgus
Most only consider the sagittal plane mobility when assessing for hypermobility, forgetting that motion is triplanar and neglecting the transverse and coronal components. Quantifying motion in these other planes is nearly impossible. We know transverse plane instability exists because how else would one explain bunion recurrence after arthrodesis of the first tarsometatarsal joint?
Frankly, it’s not entirely clear just how hypermobility causes bunions. Perhaps the instability of the medial column destabilizes the first metatarsophalangeal joint (MPJ), creating a muscular imbalance. Perhaps it is dysfunction of peroneus longus that ultimately leads to the bunion formation. Maybe it is the hallux valgus, which wedges the intermetatarsal angle open, that eventually causes the first ray hypermobility. We may never solve this chicken and egg scenario.
We know hypermobility is real and can be a pathological entity because of the Lapidus procedure, which not only realigns the transverse position of the metatarsal segment but also reduces or eliminates medial column motion. If hypermobility did not exist with bunions, then why does fusion of the midfoot correct bunions? Additionally, why is the Lapidus procedure effective in correcting forefoot overload? Stabilizing the medial column is effective in these scenarios.
The solution for hypermobility at first glimpse appears to be midfoot fusion to stabilize the first ray. However, cadaveric studies have also demonstrated that performing a metatarsal osteotomy to realign the first ray with bunions also stabilizes the midfoot through the windlass mechanism.2 The fact that we can stabilize hypermobility with bunions through midfoot fusion or osteotomy also indicates that hypermobility is indeed a reality and not a myth.
Key Insights On Hypermobility And The First Tarsometatarsal Joint
Another argument by those who don’t believe hypermobility is an entity when it comes to bunions surrounds performing the Lapidus procedure for bunions. There are those who believe that fusion of the first tarsometatarsal joint is unnecessary and surgeons should never perform it, and the solution should be a metatarsal osteotomy (head, shaft or base). However, hypermobility of the first ray is a combination of motion of the first tarsometatarsal joint, first intercuneiform joint, naviculocuneiform joint and talonavicular joint.
Faber and colleagues demonstrated that the first tarsometatarsal joint contributes 57 percent to medial column motion with the naviculocuneiform joint and talonavicular joint contributing 35 percent and 8 percent respectively to overall medial column motion.3 Similarly, Roling and coworkers found that the first tarsometatarsal joint contributes 41 percent to medial column motion with the naviculocuneiform joint and talonavicular joint contributing 50 percent and 9 percent respectively to medial column motion.1 This suggests that after first tarsometatarsal joint fusion, approximately 30 to 50 percent of the preoperative sagittal plane motion will still exist, contributing to hypermobility caused by the naviculocuneiform joint. Metatarsal osteotomy does not solve this issue whereas selective fusion does.
Symptomatic hallux valgus may indeed be associated with abnormal first ray motion, specifically the first tarsometatarsal joint.3 Medial column fusions have a significant dampening effect on first ray motion.4 Also, research has shown that intercuneiform fusion as an adjunct to first tarsometatarsal joint fusion limits first ray motion to a greater extent than isolated medial column fusions.1 Roling and coworkers found that the isolated medial column fusion did not have a significant effect in regard to range of motion limitation at the other associated joints.1 We can extrapolate that first tarsometatarsal joint fusion does not negatively affect first ray biomechanics and therefore should not increase adjacent joint stress.
As I previously mentioned, medial column hypermobility is triplanar and may persist, even after a first metatarsocuneiform fusion. Authors have shown that the “intraoperative hypermobility test” is critical in assessing transverse plane instability as the test identifies areas of hypermobility other than the first tarsometatarsal joint.4 Surgeons can do this test intraoperatively after intermetatarsal angle reduction and first tarsometatarsal joint screw fixation. One would perform this test by placing an index finger between the metatarsal heads in the first interspace. The metatarsal heads should be situated close together. If the metatarsals splay open, then proximal transverse plane instability exists.5
Whether we refer to it as reduced first ray dorsiflexion stiffness, excessive first ray dorsiflexion compliance, hypermobility or ground reaction force-induced excess motion, there can be triplanar pathological instability of the medial column that is associated with bunion formation. Hypermobility is certainly poorly quantifiable but when surgeons properly address and treat this condition, it can help treat hallux valgus without negatively affecting first ray biomechanics.
Dr. Blitz, the creator of the Bunionplasty® procedure, is in private practice in both Midtown Manhattan, New York and Beverly Hills, Calif. He is board-certified by the American Board of Foot and Ankle Surgery, and is a Fellow of the American College of Foot and Ankle Surgeons. To learn more about minimally invasive bunion surgery, visit www.bunionplasty.com.
Dr. Aitali is a second-year podiatric medicine and surgery resident within the Department of Surgery at Cedars Sinai Medical Center in Beverly Hills, Calif.
1. Roling BA, Christensen JC, Johnson CH. Biomechanics of the first ray. Part IV: the effect of selected medial column arthrodeses. A three-dimensional kinematic analysis in a cadaver model. J Foot Ankle Surg. 2002; 41(5):278–285.
2. Rush SM, Christensen JC, Johnson CH. Biomechanics of the first ray. Part II: Metatarsus primus varus as a cause of hypermobility. A three-dimensional kinematic analysis in a cadaver model. Foot Ankle Surg. 2000; 39(2):68- 77.
3. Faber F, Kleinrensink G, Verhoog M, et al. Mobility of the first tarsometatarsal joint in relation to hallux valgus deformity: anatomical and biomechanical aspects. Foot Ankle Int. 1999; 20(10):651-656.
4. Blitz NM. Current concepts in medial column hypermobility. Podiatry Today. 2005; 18(6):68–79.
6. McInnes BD, Bouche RT. Critical evaluation of the modified Lapidus procedure. J Foot Ankle Surg. 2001;40(2):71-90.