The crossover second toe is an extremely difficult problem for foot and ankle surgeons. Often, with the initial presentation, the deformity has progressed to the point where it is one subsection of a multitude of forefoot deformities. This makes the condition more challenging as you must treat the associated deformities at the same time in order to achieve a good outcome.
The etiology of crossover second toe syndrome is not fully understood. Although multiple theories have been suggested, the true underlying cause of the deformity is multifactorial and only some of these factors have been scientifically studied.
What is clear about the underlying deformity is an imbalance between the pull and position of the flexor and extensor apparatus. In a cadaveric dissection study done by Deland and Sung, the medial crossover second toe deformity was associated with an abnormal position of the long and short flexor tendons on the involved foot versus central position of the flexor tendons in the uninvolved foot.1 They found the flexor tendons to be medially deviated and sitting very close to the first interspace region.
Furthermore, Deland noted the plantar plate was medially and distally deviated on the plantar surface of the joint line. The researchers also noted poor continuity and thickness of the lateral plantar plate attachment to the proximal phalynx base.
Multiple studies have noted a second factor contributing to the deformity is a tear of the lateral collateral ligament structures.2-4, 6 The collateral ligament tears may include the metatarsophalangeal joint (MPJ) collateral, the accessory collateral which attaches to the plantar plate, or in most cases, both lateral collateral structures. With time, a shortening and overpowering of the medial collateral ligaments aggravates the underlying problem.
Although it’s essential to consider soft tissue deformity in such cases, there is a great deal of interest in the osseous deformity associated with crossover second toes. Inevitably, those who treat the condition commonly note there is a long metatarsal associated with the deformity. We must consider metatarsal length and possible wear and tear to the plantar soft tissue structures associated with prolonged periods of high peak pressures during gait.
A second area of concern is hypermobility of the first ray in association with high peak pressures plantar to the second metatarsal head region. It is possible that in those patients with laxity at the metatarso-cuneiform joint, there is poor plantar pressure distribution on the medial aspect of the foot resulting in high peak pressure values plantar to the second metatarsal head. Even in cases of hallux valgus deformity with minimal instability at the metatarso-cuneiform joint, there may be a decrease in direct pressure plantar to the first MPJ, resulting in increased peak pressure distribution plantar to the second MPJ capsule. This direct pressure coupled with adductus of the hallux, which may cause dorsal displacement of the second toe, may be one of the underlying causes of the crossover second toe.
Looking For Common Causes In Crossover Toe Cases
Presently, there is not one accepted cause for the problem of crossover toe. My impression is the problem often, if not always, involves a long second metatarsal, resulting in increased peak values plantar to the second MPJ. In most cases, surgeons note an associated hallux valgus deformity as well. This deformity is far worse in cases of severe crossover second toe deformity. However, since the problem does not present in its initial phase very often, it is difficult to consider if the hallux valgus deformity contributed to the cause or if the poor buttress function of the second toe resulted in the hallux valgus deformity increasing in severity.
Clearly, many cases of severe crossover second toe deformity have an underlying flexible first metatarsal, which is often elevated and lax at the metatarso-cuneiform joint. With increased peak pressure values plantar to the long second metatarsal, there is trauma or fraying of the plantar plate apparatus. It is not clear why the lateral aspect of the second MPJ plantar joint tears more often than the medial aspect. However, this lateral tearing of the plantar plate allows multiple deforming factors to occur.
The first and most critical of these deforming forces is medial deviation of the plantar plate and flexor apparatus. This allows the second toe to begin a medial pattern of deviation at the MPJ. Over time, an increased medial pull of the flexor apparatus results in rupture or attenuation of the lateral collateral ligaments of the second MPJ complex, exacerbating the underlying problem.
A second deforming force is the dorsal pull of the long and short extensor tendons without opposition from the plantar plate resulting in a hammertoe deformity with dorsal contracture or dislocation of the toe at the MPJ. Finally, in Deland and Sung’s cadaver study of the crossover second toe deformity, there was an associated direct pressure from the medial base of the third toe proximal phalynx on the second metatarsal lateral aspect.1 No conclusion was made about this pressure but it may be possible that this direct pressure from the third toe may be partly responsible in the tearing of the lateral ligamentous structure about the second toe.
The ultimate result of a crossover second toe is a dorsal contracture of the second toe at the MPJ with possible dislocation, contracture of the proximal phalynx at the interphalangeal joint, possible hallux valgus deformity (in moderate to severe cases), possible plantar keratoma formation and difficulty with shoe gear.
Most patients complain of pain about the joint and may even have certain symptoms similar to a neuroma in the second interspace. During the early stages, there is often pain directly plantar to the second MPJ associated with a partial tear of the plantar plate. However, there is less pain with an increase in the deformity. I associate this with complete attenuation of the plantar plate and minimal functional stability on the plantar surface of the joint. The most common complaint associated with a crossover second toe is difficulty with shoe gear due to the abnormal position of the second toe and the associated bunion deformity.
Essential Examination Pointers
Examining the patient with crossover second toe syndrome is quite simple with progression of the deformity. The essential stages of testing are grade II and III. At this time, it is essential to treat the deformity before complete dislocation of the joint occurs.
Begin your examination with a complete vascular and neurological examination of the foot. You should consider a vascular examination of the second toe given the dorsal contracture of the toe. I will often pull the toe into a corrected position and note any color changes while holding the toe in this position for several minutes. Although it is rare to see a dramatic change, such a test may help to identify cases which may be difficult to fully correct in one sitting due to tight vascular structures about the second toe.
Before testing the local deformity, first identify any structure that will make reduction of the second toe difficult. Often, there is an associated hallux valgus deformity and possibly adducted third and fourth toes which may be taking space in the location of the second toe. In cases in which you suspect a plantar plate tear of the second MPJ, consider possible laxity of the first ray or dynamic increased length of the second metatarsal. (Address these factors at the time of surgical correction of the crossover second toe.)
Then direct your attention to the second toe. Check the plantar MPJ of the second toe with direct pressure. Place pressure directly plantar to the second MPJ and it does not have to be very strong to illicit pain. As you move the area of pressure away from the metatarsal head and closer to the second toe, the level of patient discomfort should increase. This is due to the fact that most plantar plate tears are found to be off the base of the proximal phalynx.
Then check the second toe to determine the looseness of the plantar structures. Check the plantar plate with a dorsal drawer test. This is the single most important test in grade II and some grade III cases. If there is pain and dorsal puckering of the second MPJ with dorsal pull of the second toe, consider a plantar plate tear as the primary diagnosis until ruling it out.
Finally, check the crossover second toe for dorsal tightness of the joint capsule, extensor tendon and skin. In progressive deformity cases, it is not rare to have extremely tight skin in the region of the second MPJ and you must consider this factor since it may be necessary to perform skin lengthening at the same time as surgical correction of the underlying problems.
Radiographic examination is also very useful for proper diagnosis and treatment of the second toe symptoms. Be sure to consider adjacent structures in order to clear room for proper positioning of the second toe. In cases of hallux valgus deformity, you must also consider elevation of the first metatarsal. Additionally, you should visualize the position of the second toe in both a sagittal and transverse plane.
Finally, consider evaluation of second metatarsal length in comparison to adjacent metatarsals. It is very difficult to ascertain what is a long metatarsal and what is not, yet it is important to make sure that the second metatarsal is not far out of line in comparison to the other metatarsals.
What About Conservative Treatment Options?
Treatment of the crossover second toe is somewhat grade-dependent, although there is a great deal of overlap. In all cases, attempt conservative care for a period of time prior to planning any surgical correction. Conservative care is fairly easy in grade I cases and works very well most of the time. Begin by applying simple taping over the second toe with half-inch wide paper tape, as close to the MPJ as possible. Once the toe is in the ideal position, pull the tape onto the plantar arch region. In order to avoid strangulating the toe, do not cross the tape too close to the toe on the plantar surface.
An alternative treatment, but one which does not seem to work as well, is using a prefabricated device with an elastic strap and a plantar flat surface to hold the toe in the ideal position. You would combine this with stiff shoes and an orthotic device in cases of poor metatarsal length and/or laxity of the first ray. You may further customize the orthotic with a metatarsal pad or an accommodation plantar to the second metatarsal head, if you deem it necessary.
If treatment is not successful, consider a five-day course of oral steroid therapy which you may combine with physical therapy in order to resolve the inflammation and possible partial tear of the second MPJ plantar plate. When patients are not improving with stiff shoes, a below the knee walker or surgical shoe is an excellent option. Resolution of symptoms is supported with orthotic use and shoe changes.
Grade II cases are not treated much differently than grade I cases. What is important to consider in treating grade II cases is that there is a probable partial tear of the plantar plate. Therefore, you should use a below-knee walker and strict taping from the outset of initial presentation. Once you’ve achieved resolution of pain, provide support via orthotic accommodation. However, it is essential to alert the patient that the position of the toe will not correct itself with resolution of pain and the problem may progress over time.
Grade III cases are treated far differently than the first two grades. Often, the patient has already dealt with the pain of the plantar plate tear and is now complaining of the crossover second toe restricting his or her shoe wear.
Conservative care should focus on shoe modification and resolving shoeing problems, which can be accomplished with shoe stretching and extra depth or custom shoes. In early stage cases, it may be possible to use prefabricated toe holders to pull the second toe into a better position during ambulatory activity. In cases of joint inflammation which occurs from time to time, a course of physical therapy or five-day course of oral steroids may resolve the problem. Although local steroid use is no longer an issue in cases of complete crossover second toe, I believe local steroid injections weaken the surrounding soft tissue structures and cause further deformity.
Grade IV cases are very difficult to treat. Conservative care for these cases is handled in the same manner as grade III cases.
What Testing Should You Use If Conservative Care Fails?
If a course of conservative care does not resolve symptoms and you suspect a plantar plate tear in grade I and grade II cases, it is suggested that you pursue an MRI or arthrogram to diagnose the deformity. Both tests have shortcomings but they can provide a wealth of information. (In most cases, it is better to have a radiologist read and consider the arthrogram.) A tear in the plantar plate is associated with leakage of dye into the flexor tendon sheath or into the surrounding soft tissue associated with the location of the tear.
However, if there is scar formation in the region of the tear, dye leakage may not be enough to diagnose a tear and you should then consider an MRI for further diagnostic information. (The MRI is a far better test if it is conducted by someone with enough radiologic foot and ankle experience, but be aware the actual location of tear is often missed if wide slices are used.)
In cases of MRI, the actual plantar plate may be seen in association with a tear of the plate or a small fracture fragment off the base of the proximal phalynx of the second toe. One common finding you would see in cases of plantar plate tear, without actual visualization of the tear site, is an increase in plantar edema surrounding the second MPJ. Although this is not diagnostic, in such cases, you must consider an arthrogram to rule out the problem.
You may use radiographic examination to plan the surgical approach to grade I and II cases, but be aware that radiographs do not provide the same level of information as a MRI or arthrogram examination.
In cases of late grade III and grade IV crossover, it is not necessary to perform an MRI or arthrogram examination since the plantar plate tear is not of concern and radiographic examination is adequate for surgical planning. The points of interest on radiographic examination are the length of the second ray, the degree of second toe crossover and the amount of contact between the second toe and second metatarsal. Also consider possible dislocation and subluxation at the second MPJ. Finally, you should check for arthritis of the first or second MPJ on radiographs, although it is rare.
Essential Surgical Insights For The Various Stages Of Deformity
Surgical planning in all cases needs to deal with correcting the toe position in both the transverse, sagittal and frontal planes, in addition to reducing pain, correcting adjunctive disorders and stabilizing the plantar structures below the second MPJ.
Grade I cases are often treated conservatively. However, since there is not any deformity, primary repair of the plantar plate or correction of mild flexible deformity with a flexor to extensor transfer with possible release of the dorsal MPJ structures is often sufficient. In cases of a very long second ray, add metatarsal shortening to the above procedures. Furthermore, consider stabilization of the first ray with either a Lapidus procedure or first MPJ fusion if a deformity exists.
Grade II cases have a slight level of deformity and require correction of the underlying cause as well as subsequent deformity. In most cases, treatment is not very different from grade I cases, although you may need a more aggressive approach. Due to the dorsal contracture at the MPJ and mild medial deviation, perform a full MPJ release and hammertoe correction with proximal interphalangeal joint fusion.
A shortening osteotomy of the second ray may be necessary in order to correct the metatarsal parabola. In these cases, a flexor to extensor transfer is the preferred treatment over primary repair of the plantar plate since it is easier to correct the medial deviation of the toe with a tendon transfer. If you find that the second MPJ is still tight or contracting medially after release, then fully release the medial capsule and tighten the lateral capsule with 4-0 non absorbable suture to correct the transverse plane deformity.
Treat grade III and IV cases in the same manner. This treatment includes fusing the proximal interphalangeal joint of the second toe and performing flexor to extensor transfer to correct sagittal plane deformity. Often, a shortening metatarsal osteotomy is necessary to allow the second toe to be positioned properly without tension. Shortening of the second ray should not exceed the length of the third metatarsal.
In certain cases, you may use the extensor brevis tendon to the second toe to augment the correction by routing the tendon plantar to the intermetatarsal ligament between the second and third metatarsals. Then you would tie the extensor tendon into the lateral proximal phalynx with either a mini-anchor device or non-absorbable suture. Although this procedure is excellent in theory, be aware that it is very difficult to perform and often does not alter the surgical outcome dramatically.
In the case of a flexor to extensor transfer, a correction in the transverse plane is better achieved by placing the tendon though a direct drill hole in the proximal phalynx base, correcting the toe position in the sagittal plane and then tying the flexor tendon laterally for further transverse plane pull.
Other Step-By-Step Tips You Should Know About
It is essential to do a proper release of all the dorsal structures, including the extensor apparatus, dorsal capsule, and, in certain cases, the dorsal skin. Begin the release with the skin. In cases of severe tightness, perform a V-Y extension of the skin. Identify the extensor tendon and release it transversely at the second MPJ. Then release the dorsal second MPJ, the medial and lateral collateral ligaments and the entire base of the second toe. I try to leave the lateral capsule intact and also try to keep all lateral collateral ligaments as whole as possible for later repair. On the other hand, I will perform a full and complete release of the medial aspect to the second toe.
Once you’ve performed a full release, check metatarsal length. If relocation is difficult, perform a shortening of the second metatarsal. Then proceed to fixate the osteotomy and relocate the toe. Harvest the flexor tendon at the proximal interphalangeal joint and rout it into the base of the proximal phalynx through a drill hole in the central base. Perform the peg in hole fusion, tighten the flexor tendon and tie it into the lateral extensor tendon. Drive a K-wire, which has been previously retrograded out of the distal second toe, proximally across the MPJ and into the metatarsal with the toe in rectus position. Do not repair the extensor and capsule at the MPJ. Proceed to close subcutaneous tissue and skin.
In cases of severe grade IV deformity in an elderly patient or a patient who is a poor surgical candidate, amputation of the second toe with or without hallux valgus correction is also an option. Furthermore, fusion of the second MPJ is currently being done on severe cases with excellent outcomes being reported. Further research is needed to gauge the function of the second ray following fusion, yet this is an excellent procedure for deformity correction and may offer a far better long-term option in the future.
Following surgery and in those cases in which the first metatarsal is not stabilized, orthotic care is essential in order to correct pressure distribution across the forefoot. A stiffer shoe is also preferred to prevent high peak pressure plantar to the second MPJ.
With proper workup, detailed testing and thorough and regimented surgical correction, you can attain good to excellent outcomes in these difficult cases.
Dr. Baravarian is an Assistant Clinical Professor in the Department of Surgery/Division of Podiatric Surgery of the UCLA School of Medicine. His e-mail address is Bbaravarian@mednet.ucla.edu.
References 1. Deland, J. T., Sung, I.H.: The Medial Crossover Toe: A Cadaveric Dissection. Foot Ankle Int. 21(5): 375-8, 2000 2. Haddad, S.L., Sabbagh, R.C., Myerson, B, Myerson, M.S.: Results of Flexor to Extensor and Extensor Brevis Transfer for Correction of the Crossover Second Toe Deformity. Foot Ankle Int. 20(12): 781-8, 1999 3. Graziano, T.A.: Correction of Crossover Second Toe Deformity. Clin. Poditar. Med. Surg. 13 (2): 269-78, 1996 4. Coughlin, M.J.: Crossover Second Toe Deformity. Foot Ankle. 8(1): 29-39, 1987 5. Hatch, D.J., Burns, M.J.: An Anomalous Tendon Associated With Crossover Second Toe Deformity. J. Am. Podiatr. Med. Assoc. 84(3), 131-2, 1994 6. Johnson, J.B., Price T.W. 4th: Crossover Second Toe Deformity: Etiology and Treatment. J. Foot Surg. 28(5): 417-20, 1989