Recognizing the challenges of transverse plane deformity correction of the lesser toes, this author discusses keys to a thorough workup, essential surgical considerations and step-by-step pearls to help ensure optimal outcomes.
Hammertoes are more complicated than they may appear and provide daily strife to patients as well as foot and ankle surgeons. All hammertoes are not created equal. One can commonly correct most sagittal plane deformities with proximal interphalangeal joint (PIPJ) arthroplasty or fusion and a combination of soft tissue releases. This allows the correction of the contracture of the distal digits and relieves the symptoms at the toe level. What I aim to discuss here are techniques to correct transverse plane deformities of the lesser toes.
As with most forefoot deformities and surgical reconstruction, an appropriate workup is essential. This includes a thorough non-weightbearing and in-stride examination of bilateral lower extremities in order to confirm a lack of rearfoot/ankle progressive deformities that may be contributing factors. The most common deformities are posterior muscle group tightness or contracture. The patient’s pain is typically at the second metatarsophalangeal joint (MPJ) dorsal and plantar.
Make certain to assess contractures of the MPJ, PIPJ and distal interphalangeal joints (DIPJ) for flexibility. There are instances, approximately 35 to 40 percent of the time, when the deformity is only in the transverse plane at the MPJ level without a digital contracture. Patients typically will also have a hallux valgus deformity, which surgeons can often correct in a single stage fashion.
Addressing both the medial column and central rays in the same surgery is not atypical, and one should do this to address all contractures. Otherwise, recurrence will be near 100 percent. Addressing the plantar plate’s integrity and structures is important. The surgeon can typically do so with a modified Lachman’s test to determine if there is greater than 50 percent dorsal translation of the proximal phalanx on the metatarsal head. If this is the case, one can diagnose a plantar plate tear with high sensitivity.1 This maneuver usually elicits a high degree of pain in these deformities. This being said, the most common ray involved is the second ray and in a medial direction. Lateral deviations are less common and typically involve the second, third and fourth MPJs.
Take three standard radiographic views of the weightbearing foot to assess for common hallux valgus angles and any arthritic changes. Again, with a transverse plane deformity or even a triplanar deformity, lesser toe deviation will typically be present at the MPJ level. There is no standard radiographic angle algorithm at this time to assess the degree of lateral collateral ligament damage or the degree of transverse plane deformity. If the surgeon wants confirmation of soft tissue attenuation and to rule out other pathologies, one may order advanced imaging, either ultrasound or MRI.2 We are striving to create a treatment algorithm for complex triplanar deformity correction of lesser digits as we are beginning to understand the pathomechanics.
Is Non-Operative Treatment Effective?
Non-operative treatments include toe spacers, metatarsal pads, orthotic offloading devices and taping. Due to the longstanding nature of these deformities, these options typically only provide temporary relief. For some patients, this is enough to provide comfort in a larger toe box shoe and accommodate their needs. After exhausting conservative treatment options, one may offer operative interventions.
Our new protocol for ruling in any subtle lateral collateral ligament damage and/or plantar plate lateral disruption would be to tape the second, third and fourth toes together daily for approximately two to four weeks. This places the MPJ and surrounding ligamentous structures in appropriate alignment, and will often relieve the pain significantly. This is obviously not a permanent solution but one can attempt it for a period of time.
Pertinent Principles And Considerations With Procedure Selection
The current concept of any osseous correction is to offload the MPJ and realign the metatarsal parabola to a more normal position. This would inherently offload the soft tissue structures related to this deformity and therefore relieve the patient’s pain. Soft tissue reconstruction and plantar plate repairs have been increasing sources of conversation and research.3-6 However, researchers have made few conclusions regarding the correction of both the transverse and sagittal plane deformity of the lesser toes.
Deficiency in the MPJ collateral ligaments as well as unbalanced muscular forces surrounding the lesser MPJ often lead to a deformity in all three planes.7 Most often, this angular contracture is present in the second MPJ due to the underlapping hallux with a concomitant moderate to severe hallux valgus deformity. We understand the natural history of this deformity as an instability of the lesser MPJ and contracture of the medial soft tissue structures, typically occurring with an unbalanced parabola and/or hypermobility/insufficiency of the first ray. This allows the digit to follow the pull of the flexor tendons.
Debate over the impact and existence of first ray hypermobility persists, but its existence is undeniable in the presence of hallux valgus deformity and research has shown that realignment of the first ray relieves hypermobility.8-10 Over time, the medial collateral ligaments contract and the lateral collateral ligaments attenuate. The digit typically follows the tightened flexor tendons and contracts at the digital interphalangeal joints as well. First ray pathology is not ubiquitous with angular deviation of the lesser MPJs but one should address this if it is present.
The Weil osteotomy has been one of the most common forefoot procedures surgeons perform for digital deformities and metatarsalgia, but there is a 36 percent incidence of postoperative floating toe deformity.11 Beyond the complications associated with Weil osteotomies, the Weil osteotomy is not well suited to correct transverse plane malalignment about the MPJ.
However, Devos and colleagues described a modification with transverse plane deviation of the Weil osteotomy toward the direction of deformity.12 In their study, they found that 43 of 43 patients had resolution of the focal metatarsalgia, one (2 percent) had transfer metatarsalgia and 13 (30 percent) had a floating toe. Despite the high incidence of floating toe, the patients in the study had an average postoperative American Orthopaedic Foot and Ankle Society (AOFAS) score of 93.5. The inability of the standard Weil osteotomy to correct transverse plane deformity adequately is clear and the notion of floating toe is not uncommon with Weil osteotomies. Devos and colleagues did develop the concept of a transverse plane translation to help correct transverse plane deformities of the MPJ, but this procedure not only involves osseous correction but soft tissue reconstruction as well.12
For predictable correction of the transverse deformity of a lesser digit, one must follow a sound surgical approach in order to optimize outcomes and reduce complications.
A Relevant Stepwise Approach To Transverse Plane Deformity Correction
Address hallux valgus first when present with the procedure at the discretion of the surgeon. Requisite reduction of first and second intermetatarsal deformity with a hallux valgus angle ranging between 0 to 15 degrees is necessary.
Once the first ray is in normal anatomic alignment, direct attention to the affected lesser MPJ(s). If one is correcting multiple digits, start with the most medial digit. Address digital contracture first, usually with PIPJ preparation for arthrodesis through a dorsal longitudinal incisional approach. The surgeon may place definitive fixation with a Kirschner wire or an intramedullary implant now, or delay placement until completing plantar plate repair (if necessary). Lengthen the incision proximally in a curvilinear fashion to gain exposure of the MPJ to prevent inadvertent dorsal skin (and digital) contracture. The surgeon can also make two separate incisions, one over the PIPJ and one just proximal to the lesser MPJ. Open the extensor digitorum longus in “Z” fashion to facilitate later repair in a lengthened state. Perform a dorsal transverse capsulotomy at the MPJ and transect the medial and lateral collateral ligaments and dorsal capsule mid-substance. This allows one to use appropriately working soft tissue for the collateral ligament repair.
At this point, perform the metatarsal osteotomy. With medial deviation of the digit, make the osteotomy in an oblique fashion to shorten and realign the toe. Orient the osteotomy from dorsal to plantar, perpendicular to the weightbearing surface of the foot. With translation of the cut from medial to lateral (or vice versa, depending on deformity), no dorsal or plantar shifting will occur. Most commonly, one would make the cut from distal lateral to proximal medial with a medial crossover toe. If there is lateral deviation of the digit, the osteotomy is the opposite direction. Of note, the osteotomy is approximately 45 degrees to the long axis of the metatarsal and starts just proximal (0.5 cm) to the articular cartilage of the metatarsal head within the neck.
Complete the osteotomy in the distal diaphysis. The intention is to have a large enough capital fragment for fixation without having to violate the articular surface. This will allow the surgeon to translate the capital fragment medially (or laterally) and proximally to the desired level. The surgeon can also translate dorsally 1 to 2 mm if desired to offload the plantar plate. This osteotomy has now been introduced as the B-Mac (Bouché-McAlister) metatarsal osteotomy.
After performing the osteotomy, translate the capital fragment to realign the toe to a rectus position, usually a minimum of one-third the width of the metatarsal. Temporarily fixate the capital fragment with a small Kirschner wire and be sure the toe has shifted in the appropriate position. After confirming the correct position, fixate the capital fragment with either threaded 0.062-inch Kirschner wire(s) or small screw(s) (1.5 mm to 2.5 mm) perpendicular to the osteotomy, distal to proximal or proximal to distal. The surgeon may use one or two points of fixation. Take care not to violate the articular surface of the metatarsal head or place fixation protruding from the plantar surface that may damage the plantar plate. The length of screw or Kirschner wire is typically near 16 mm.
Confirm correction on intraoperative fluoroscopy. I have found that a medial or lateral shift of at least one-third to one-half the width of the metatarsal is required. Take care not to overcorrect as this osteotomy is very powerful. Close the attenuated collateral ligaments and capsule with a non-absorbable suture in the mid- to plantar aspect of the joint so as not to cause an inadvertent dorsal contracture. Proceed to repair the extensor digitorum longus in a lengthened position.
When A Plantar Plate Tear Is Present
If a plantar plate tear is present, address it from a plantar approach. The diagnosis of a plantar plate tear may be at the discretion of the surgeon and can be based on magnetic resonance imaging (MRI), MRI arthrogram, arthrogram under fluoroscopy, and/or clinical examination. While indirect (non-anatomic) repairs via procedures like the flexor digitorum longus transfer, flexor digitorum brevis transfer or extensor digitorum brevis transfer are possible, we reserve these techniques for revision cases in which there is insufficient tissue for anatomic repair. In our experience, when a plantar plate tear is present, it is a persistent source of pain if it goes unaddressed. However, anecdotally, we have noted a negative Lachman’s test (with preoperative positive test) after performing and fixating the osteotomy. If the Lachman’s test is negative after the triplanar osteotomy, we forego the plantar plate repair.
To address the plantar plate, make a longitudinal curvilinear incision between the metatarsal heads, adjacent to the affected MPJ so as not to place the incision directly over the weightbearing surface of the metatarsal head. Release the flexor sheath and retract the flexor tendons, exposing the plantar plate. Similar to Blitz and coworkers, we favor elliptical removal of the tear with a small wedge from the torn/attenuated side and repairing the plantar plate with small gauge non-absorbable suture with the toe held in a slight overcorrected position.13 If the tear is directly off the base of the proximal phalanx, roughen the base of the phalanx and insert a small suture anchor (2.0 mm to 2.5 mm) to reattach the plantar plate. One may use a Kirschner wire prior to (our preference) or after plantar plate repair for PIPJ arthrodesis fixation, and the K-wire can cross the MPJ to hold the toe in corrected position for appropriate tension during healing of the plantar plate.
We favor pinning the toe in the corrected position after getting exposure of the plantar plate, which ensures slight over-tensioning with the digit well aligned. Delay dorsal skin closure until the osteotomy is complete. Typically, a flexor digitorum longus transfer is not required during the index procedure but one may utilize this if there is insufficient tissue for anatomic repair of the plantar plate, or in the case of revision.
Then close the plantar and dorsal soft tissues in a layered fashion. Bandage the affected toes in a slightly overcorrected position.
A Few Notes On The Post-Op Protocol
Postoperatively, the patient typically bears weight immediately in a controlled ankle motion (CAM) walker fracture boot for four to six weeks until radiographic healing occurs and then transitions to a supportive shoe. One would splint the lesser digits in the appropriate position (if no K-wires are present) for six weeks.
This operative strategy for transverse plane deformity has worked well in our sports medicine foot and ankle clinic over the past several years. Pitfalls would include undercorrection, increasing activity too soon, failure to address the lateral collateral ligament and undercorrection of hallux valgus deformity or lack thereof. With the aforementioned surgical approach and osteotomy, I have performed fewer tendon transfers and plantar plate repairs.
Dr. McAlister is in private practice at Arcadia Orthopedics and Sports Medicine in Phoenix. He is a Fellow of the American College of Foot and Ankle Surgeons. Please feel free to email or contact the author at Dr.firstname.lastname@example.org or www.drjeffmcalister.com
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