Point-Counterpoint: Is Fusion The Best Option For Crossover Toe Deformity?

Author(s): 
By William D. Fishco, DPM, and Lawrence Ford, DPM

Yes, this author says surgeons can successfully incorporate arthrodesis in the repair of this deformity. He says a strong knowledge of the second toe anatomy and other influencing structures can facilitate good treatment outcomes. By William D. Fishco, DPM    In theory, surgery on the toes sounds pretty simple. After all, how hard can it be? Technically speaking, we consider toes to be “easy,” especially when we first start out in residency training. Most of us remember getting our first chance handling a scalpel while performing toe surgery. However, anyone who has been in practice for awhile has seen his or her share of less than favorable results following hammertoe surgery. Indeed, digital surgery can be quite a humbling experience for even the most seasoned foot surgeons.    Hammertoe surgery of the second digit, in particular, can be the most challenging. This is partly due to abnormal biomechanics (first ray function) and influences from the great toe. When considering hammertoe surgery on the second toe, the sagittal plane component is rather straightforward. However, medial drift and eventual crossover toe deformity represent the hard part. There is not a procedure or group of procedures that works every time but understanding the anatomy and function of the structures influencing the second toe can help one in procedure(s) selection.    When dealing with a crossover deformity, there are a number of things to consider. Certainly, if there is concomitant first ray pathology, then one needs to correct that concurrently with the second toe surgery. For example, in the case of a dysfunctional first ray, whether it is hallux abductovalgus, hallux limitus or metatarsus primus elevatus, the second metatarsophalangeal joint will be abused, owing to lesser metatarsal overload. This lesser metatarsal overload leads to a cascade of events that may start out as predislocation syndrome and ultimately evolve into a crossover deformity. Moreover, certain structural abnormalities, such as a short first ray or long second ray, have an impact on the second toe joint. This can be congenital or from prior surgery. Often, one will see a medial pull of the second toe, which is probably due to strain on the intermetatarsal ligament.    There are two schools of thought when it comes to hammertoe surgery, namely arthrodesis versus arthroplasty. I am a proponent of digital arthrodesis for the correction of most hammertoe deformities. The main exceptions include the fifth toe and in the case of a relatively inactive geriatric patient who is getting an ulcer on the toe or simply can’t get a shoe on the foot without pain. This type of patient does well with a simple arthroplasty. In this instance, appearance and/or function is not as important as pain relief.

Understanding The Role Of The Long Flexor Tendon

   There has been debate about the cause of crossover deformity. In the past five to 10 years, plantar plate insufficiency has gotten a lot of attention as being the culprit. Others blame a tight, long extensor tendon for causing imbalance to the toe. Certainly, we do not understand everything and there may be a number of structures and influences that ultimately may cause the second toe to drift medially. It is my personal opinion that the long flexor tendon is the key structure to understanding the second toe.    Flexor stabilization is a term I use to describe the intent of my surgical intervention when it comes to hammertoe correction. For this reason, arthroplasty (without any adjunctive procedures such as a flexor tendon transfer) of the second toe is inadequate to control the deformity, especially in the long term. E. Dalton McGlamry, DPM, taught us to change the fulcrum of the long flexor tendon from the interphalangeal joint to the metatarsophalangeal joint. When the toe is a rigid lever, the long flexor tendon can pull the toe down at the level of the metatarsophalangeal joint. This in turn creates a performing force from a deforming force. With an arthroplasty of the toe, one is creating instability, which may prevent the long flexor tendon to adequately control the deformity. In addition, retrograde buckling may persist if the proximal interphalangeal joint is not stiffened.    Medial drift of the second toe and non-purchasing toes are usually caused by dysfunction of the plantar plate and the long flexor tendon. Transverse plane deviation of the toe occurs when the plantar plate attenuates, allowing the long flexor tendon to migrate medially. This is analogous to the sesamoid apparatus of the great toe joint. In the great toe joint, the flexor tendons are fixed in space with the sesamoid apparatus. As the first metatarsal drifts medially, the great toe’s position is altered because of soft tissue attachments. The base of the great toe acts like a hinge. The base of the toe does not translocate laterally but the angle of the toe changes (i.e. abduction).

How To Prevent The Post-Op Floating Toe

   When looking at causes of a floating toe after surgery, in most of the cases, it has to do with excessive shortening of the toe and/or the metatarsal. If one performs an arthroplasty, the toe is decompressed and this will usually resolve the sagittal plane hammertoe deformity. However, as the toe shortens, the long flexor tendon has slack. The net effect is the loss of the tendon’s mechanical advantage as the long flexor tendon cannot pull the toe down.    For this reason, when I perform an arthrodesis, I will only resect cartilage of the proximal phalangeal head and base of the middle phalanx. This enables me to preserve as much bone length as possible to empower the flexor tendon. I can always resect more bone if there is difficulty apposing the proximal and middle phalanges.    Correcting a floating toe will usually require a flexor to extensor transfer. An exception would be in the case of severe shortening of the proximal phalanx. In these cases, obtaining a cortical bone graft may be important to regain length. Always remember that, in most cases, a non-purchasing toe (floating toe) is not due to a tight/contracted long extensor tendon or skin/scar contracture but rather a weak and dysfunctional long flexor tendon. Shortening the metatarsal can also cause the same problem.    Therefore, one must exercise caution when attempting to address a floating toe with an extensor digitorum longus lengthening and dorsal metatarsophalangeal joint capsulotomy. It has been my experience that this fails to correct the deformity in the long term. We have all tried to splint a toe with a dressing or K-wire with high hopes that it will maintain its correction over time. The ultimate outcome is usually less than satisfactory. An important point that I teach my surgical residents is whatever correction one obtains on the operating room table is the best one can ever expect.    When I am addressing a second hammertoe deformity with medial drift, I usually include arthrodesis in the surgical repair. If the transverse plane deformity is reducible, I will perform a metatarsophalangeal joint release of the tight medial capsule and subsequently perform a lateral capsulorrhaphy with non-absorbable suture. I employ K-wire fixation and generally cross the joint to the metatarsal. If the transverse plane deformity is semi-rigid, I consider adding a release of the flexor tendon sheath to help mobilize the tendon under the metatarsal. If further correction is necessary, I will consider a flexor tendon transfer in part or total to help lateralize the tendon vector. Finally, in cases where the second toe has a completely rigid deformity, usually from long-standing malposition, I will perform a base resection of the proximal phalanx with syndactyly to the third toe.

Final Notes

   As podiatric surgeons, we are pursing the ultimate goal … to perform the perfect bunionectomy and second hammertoe repair every time we get in the operating room. The second toe is still somewhat of an enigma that frustrates us all. Hopefully, understanding the anatomic structures and their influences on the second toe can help one in choosing the best procedure(s) for reconstruction. Dr. Fishco is board-certified in foot surgery and reconstructive rearfoot and ankle surgery by the American Board of Podiatric Surgery. He is a teaching faculty member of the Phoenix Baptist Residency Program and is in private practice in Phoenix. He is also a faculty member of the Podiatry Institute. No, this author says the varying spectrum of deformity and individual factors such as age and activity level warrant the consideration of various surgical options. By Lawrence Ford, DPM    Fusion is not the best option for treating crossover second toe deformity. It is one option among many. Larry Karlock, DPM, reported on 11 patients who underwent second MTPJ fusion for crossover toe. Although he demonstrated good to excellent results with this procedure, he only performed this for those patients with severe, progressive deformity. He stated “this procedure is not advocated in the mild or moderate deformity, which can be addressed with traditional surgical means.” His study has not yet been replicated.    Although it appears that second MTPJ fusion is a viable option in advanced cases, one should keep in mind that not all crossover toes are severe. There is a spectrum of deformity ranging from reducible subluxation to rigid dislocation, not to mention the precursor of predislocation.    The crossover toe is a very complex problem that is both frustrating to the patient and surgeon alike. Even though it has been extensively researched clinically and in the laboratory, the etiology is still not clear. Surgical results are unpredictable, sometimes resulting in recurrence, lack of toe purchase, stiffness, continued pain and overall patient dissatisfaction. Many different procedures have been advocated to fix the crossover second toe but none have been universally successful.    The search for a predictable correction led to the consideration of second MTPJ fusion. One of the obvious attractions of the second MTPJ fusion is that it is definitive and more predictable. However, as with all procedures, it is not without its drawbacks. Nonunion and malunion are very realistic complications. Even in a perfectly executed surgery with optimal results, we do not know what kind of impact the fusing of the joint will have on the patient’s gait.

Emphasizing The Different Variables That Play A Role In Appropriate Procedure Selection

   Different procedures for crossover second toe deformity have garnered variable success. The key is selecting the correct procedure based upon the particular influences on each individual foot. It is important for surgeons to have an array of tools for surgery. It is impractical to rely on any one procedure as all cases have nuances that make them somewhat unique. It has become clear that treatment — similar to what one would use to correct a hammertoe — that involves fusing the PIPJ, performing a sequential release of the MTPJ and pinning across the joint for several weeks will usually fail for crossover toe.    Ideally, surgeons would be able to correct the etiology of the crossover toe but this is not always practical if the patient cannot entertain prolonged post-op immobilization. In certain instances, perhaps only treating the symptoms is more in tune with the patient’s goals. When attempting to correct the etiology, one must consider that the joint is unstable because the anatomic restraints to dislocation have been compromised. The plantar plate, collateral ligaments and the unique intrinsic musculature to this joint have all been implicated as local factors. However, when looking at the bigger picture of nontraumatic cases, it must be the biomechanical forces going through the second MTPJ that weaken these restraints. Therefore, correcting the underlying etiology may require addressing equinus, first ray insufficiency and/or an abnormally long metatarsal.    How to best address the second MTPJ is an area that warrants much more research to improve surgical results. There are many approaches for realigning the second MTPJ and toe anatomic position, and they depend upon several factors like age, activity level, severity and patient goals.

A Closer Look At Alternative Options For Milder And Rigid Deformities

   For patients who have a milder reducible deformity, performing a flexor tendon transfer can be effective. One can accomplish this by combining a Girdlestone-Taylor type of approach from the lateral side of the toe with a release of the contracted medial MTPJ structures. However, if the medial subluxation force is strong, a flexor tendon transfer alone may not be enough.    When confronted by a more advanced contracture that is still reducible, using a dorsal approach with PIPJ fusion is better. The lateral slip of the FDL transfer can be tensioned more than the medial slip in order to create more of a lateral pull on the toe. Of course, the surgeon would combine this with K-wire fixation, complete release of the soft tissue and balancing of the contracture at the MTPJ. There is a lot of room for error with this particular procedure, especially when one considers that the appearance on the operating room table does not necessarily correlate with the final outcome. The toe itself may be straight and rectus but getting the toe to rest on the ground with normal purchase is very difficult and not easily predictable.    Although plantar plate advancement has not been clinically substantiated with evidence-based medicine, it has been used effectively to realign the MTPJ, and resist dorsal and medial subluxation in milder cases of crossover second toe deformity. Toe purchase is more predictable but it is still unknown whether this procedure stabilizes the joint long term with pain relief.    For those patients who suffer from a rigidly subluxed crossover second toe deformity, soft tissue work alone will not suffice. Sometimes a shortening metatarsal osteotomy is necessary to decompress the joint in order to allow the soft tissue balancing to be more effective. If the metatarsal is not abnormally long, this can lead to further transfer metatarsal overload, which would make this procedure a poor choice. In these cases, a more aggressive correction may be necessary. Toe amputation rarely works as the third toe takes the place of the second toe by overriding the hallux. Metatarsal head resection does treat the rigidity of the dislocated crossover toe but it is well known that the cost of walking on four metatarsals instead of five also makes this a poor choice of procedures. This is certainly a scenario where second MTPJ fusion may have its merits.    William Fishco, DPM, introduced me to a procedure several years ago that I have been able to use with good success. This procedure definitively addresses a rigid crossover toe with good patient acceptance and satisfaction. This procedure involves performing an arthroplasty of the base of the proximal phalanx, which essentially renders the toe and MTPJ floppy. The surgeon would then partially syndactylize the toe to the third toe. Recovery is quick in a surgical shoe. Antecdotally, this procedure has worked quite well in the subset of patients who are less active and only wish to be able to walk in a reasonable shoe without pain.    The indications for this procedure are similar to the indications for second MTPJ fusion in that they are both reserved for severe rigid deformity. The former procedure has the advantages of a less difficult technique and a quicker recovery. In employing this salvage procedure for severe deformity, surgeons can attain realistic goals without much compromise in gait for less active individuals.

In Conclusion

   Although fusion of the second MTPJ is a viable option for treating the complex problem of crossover second toe, there are other choices available in the spectrum of mild to severe deformity that one should consider first. Obviously, this is an area of foot surgery where more research is needed in order to achieve more predictable and satisfying surgical results. Dr. Ford is the Residency Director of the San Francisco Bay Area Foot and Ankle Residency Program at Kaiser Permanente in Richmond and Oakland, Ca. He is a Fellow of the American College of Foot and Ankle Surgeons. References 1. Karlock LG. Second Metatarsophalangeal Joint Fusion: A New Technique for Crossover Hammertoe Deformity. A Preliminary Report. JFAS 42(4):178-182, 2003. 2. McGlamry ED. Lesser ray deformities. In Comprehensive Textbook of Foot Surgery, 2nd ed, pp321-378 3. Yu GV, Judge MS, Hudson JR, Seidelmann FE. PreDislocation Syndrome. Progressive Subluxation/Dislocation of the Lesser Metatarsophalangeal Joint. JAPMA 92(4):182-199, 2002. 4. Deland JT, Sung I. The medial crossover toe: a cadaveric dissection. Foot Ankle 21:375, 2000 5. Coughlin MJ. Crossover second toe deformity. Foot Ankle 8:29-39, 1987.

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