Revisional Surgery of the Lesser Metatarsals and Metatarsophalangeal Joints
John S. Anderson, Vikram A. Bala, Gregory A. Foote
Revisional surgical interventions for recurrent pathology at the lesser metatarsophalangeal joint (MTPJ) include repeat ligament repair, flexor tendon transfer, revisional osteotomy, joint arthroplasty, and arthrodesis. The term metatarsalgia has been used to loosely describe the pain associated with the forefoot and surrounding structures. This forefoot pain is a common problem in older individuals, with a reported incidence of 25% in those over 65 years of age.1 Several authors have attempted to classify this pathology with most in agreement on the major contributing factors.2 The symptoms associated with metatarsalgia can generally be divided into 3 groups: primary, secondary, and iatrogenic. Primary metatarsalgia references symptoms from anatomical or biomechanical imbalances. Secondary metatarsalgia refers to symptom-related systemic conditions such as gout, rheumatoid arthritis, or other inflammatory arthritis. Finally, iatrogenic-induced metatarsalgia refers to those symptoms directly related to the complications of previous forefoot surgery.3
Initial surgical interventions for primary metatarsalgia are focused on the restoration of anatomic and biomechanical imbalances. These structural and biomechanical deficiencies of the forefoot most commonly involve first ray insufficiency or central ray overload syndrome.4 In chronic insufficiency of the first ray, there is a resultant secondary overload and irritation of the second MTPJ.5 Central ray overload syndrome occurs in patients with lateral metatarsal heads longer or more plantarflexed or plantar displaced in relation to the first metatarsal.4 A “normal” metatarsal parabola has been described by Viladot4 with the formula of 1 < 2 > 3 > 4 > 5. Variations of this parabola and abnormalities in metatarsal length disrupt the pressure distribution.7 These structural abnormalities of the forefoot are typically inherited and predispose these patients to the development of forefoot pathology. Abnormalities in metatarsal length appear in approximately 56% of the population and, when symptomatic, are most commonly addressed through surgical intervention.5,6
The Weil shortening metatarsal osteotomy has become the increasingly accepted method for restoring the metatarsal length relationship. Coughlin8 found that an average second metatarsal protrusion of less than 3.8 mm in relation to the first and third metatarsal resulted in the lack of forefoot pain (Figure 8.1). The most ideal position of the second metatarsal is at a position 1 to 2 mm longer than the first metatarsal.9 Prolonged increase in pressures to the metatarsal heads leads to a chronic static and dynamic irritation of the plantar plate.5 Klein et al10 suggested that the metatarsal parabola should be corrected to maintain long-term correction of plantar plate pathology.
Iatrogenic-induced metatarsalgia is often secondary to the disregard or inadequate correction of the underlying biomechanical imbalance. The most common complications of these procedures are floating toe or lack of toe purchase, transfer lesion, recurrence of symptoms, joint contracture, and delayed union, nonunion, or malunion of the osteotomy.11 The loss of MTPJ range of motion with excessive elevation of the metatarsal and secondary degenerative changes has also occurred as a result of improper osteotomy placement or osteonecrosis.12 The largest literature review to best summarize the overall complications of the Weil osteotomy including retrospective and prospective studies was performed by Highlander et al.13 The authors examined 1131 Weil osteotomies in 576 patients over 17 studies. They reported an average incidence of floating toe in 36%, transfer metatarsalgia in 7%, recurrence of symptoms postoperatively in 12.5%, and a 3% incidence of nonunion, malunion, or delayed-union.13
The Weil osteotomy itself is an inherently stable osteotomy created parallel to the weight-bearing surface. This, coupled with consistent and reproducible fixation, makes bone healing issues exceedingly rare. Fixation is typically left to surgeon’s preference ranging from a nonfixated osteotomy to wire and most typically screw fixation. Although this fixation may be variable between surgeons, 2 points of fixation are encouraged to provide both positional and rotational stability in early ambulation. In revisional cases, the use of plate fixation may be required depending on the bone stock available at the distal metatarsal.
The remaining complications involve the concept of a balanced forefoot parabola that must be maintained for optimal outcomes. Undercorrection and overcorrection are the primary factors leading to recurrence of symptoms. The lack of adequate joint decompression and inadequate shortening may lead to continued pain and redislocation of the MTPJ. A small wedge or a “double” Weil osteotomy with further bone resection from the plantar metatarsal may be required to obtain adequate joint decompression. Overcorrection or over-shortening of the capital fragment is likely to drive such complications as transfer lesions, joint contracture, floating toe, or lack of toe purchase.
Improper positioning of the metatarsal head in the transverse plane may also contribute to continued deformity at the toe level or intermetatarsal bursitis. The metatarsal head should be translated medially or laterally from its initial position with slight lateral rotation to further drive the position of the toe at the joint level. The ultimate goal of these procedures should be establishment of a normal weight-bearing relationship to the forefoot and creation of a normal parabola which may require balance and shortening of adjacent metatarsals. In some cases, bone grafting may be required to restore the length of the lesser metatarsal as opposed to shortening multiple metatarsals. In cases of decreased viability of the capital fragment, a metatarsal head resection, lesser MTPJ soft tissue interpositional arthroplasty, or prosthetic joint implant may need to be considered. The remaining factors necessitating revisional surgery involve inadequate or improper balancing and correction of the lesser MTPJ soft tissue in conjunction with metatarsal osteotomy.
Lesser MTPJ instability, if left unaddressed, may contribute to poor prognosis after an isolated Weil osteotomy and has been managed historically via either direct and indirect repairs of the deformity. Stability of the lesser MTPJ hinges upon the structural integrity of the plantar plate, as well as, the medial and lateral collateral ligaments. Isolated compromise of the plantar plate led to a 19% displacement of the MTPJ, while isolated release of the medial and lateral collateral ligaments resulted in 13% and 17% displacement, respectively. Release of both collaterals resulted in 37% instability. Compromise of all 3 structures resulted in 63% joint displacement.14
Indirect methods of repair are those that do not directly address the plantar plate or collateral ligaments. Indirect repair options include soft tissue release, extensor or flexor tendon transfer, and metatarsal osteotomy, as previously discussed.15 Unsatisfactory clinical results have been reported for tendon transfer procedures, which have been associated with prolonged swelling and stiffness.16
Alternatively, direct repair acts exclusively on the distal aspect of the plantar plate, by repairing the attenuated or failed distal portion of the plantar plate back onto the base of the proximal phalanx of the toe. Direct plantar plate repair can be augmented via collateral ligament repair as well. Weil metatarsal osteotomy performed in conjunction with a direct plantar plate repair was initially described in an effort to eliminate complications associated with a floating toe as a sequela of an isolated metatarsal osteotomy.17,18 Several plantar plate repair techniques have been described, ranging from the traditional plantar approach to modifications of a dorsal approach, both with and without a metatarsal osteotomy.16,19–22
Bouche and Heit23 evaluated a plantar approach plantar plate repair performed in conjunction with a flexor digitorum longus (FDL) transfer. The addition of the FDL transfer was found to enhance the toe stability to 100%, however 40% of the patients complained of joint stiffness. Overall, 30% of patients had poor toe purchase.23 In a review of 144 plantar approach plantar plate repairs, 87.1% of cases resulted in a well-aligned toe, with a recurrence rate, specifically lack of toe purchase, of 7.6% and an overall revision rate of 2.8%, while 4.2% complained of a painful plantar scar.24 In a recent review of 204 plantar approach plantar plate repairs in 185 patients, 31 (15%) complications, 14 (6.8%) superficial infections, and 17 (8.3%) painful scars were reported. Overall, there were 3 (1.4%) reported reoperations for recurrent deformity or instability.25
Nery et al,16 combined dorsal plantar plate repair and Weil osteotomy and reported 67.5% achieving a stable dorsal drawer of the MTPJ with 63% able to successfully perform the paper pull-out test by final assessment. Another large study evaluating the dorsal approach plantar plate repair combined with metatarsal osteotomy reported 95.7% of patients achieving a stable dorsal drawer as well as a significant mean reduction in visual analogue scale (VAS) pain of 3.9 points on a 10-point scale.26 However, only 54% could perform a successful paper pull-out test by the final follow-up.26
More recent studies by Cook et al27,28 evaluated direct anatomic repair of both the collateral ligaments and the plantar plate. A case-control study was performed to evaluate traditional capsulotendinous balancing of the lesser MTPJ versus anatomic reconstruction. The anatomic MTPJ reconstruction group was found to have 94% postoperative toe stability compared with 60% toe stability in the traditional repair group. Anatomic repair was also superior in terms of dorsal drawer and paper pull-out test, compared to the traditional repair group.27 In a 2020 retrospective review, Cook et al,28 report a 100% and 92% stability based on dorsal drawer and paper pull-out, respectively. These authors found a 0% recurrence rate in 50 patients. Nery et al,16 concluded that grading the type of tear allowed one to plan their management appropriately. They were the first to grade plantar plate tears and tailor the management plans accordingly. The success of anatomic lesser MTPJ reconstruction via plantar plate and collateral ligament repair versus traditional capsulotendinous balancing procedures such as tendon transfers, capsular procedures, tendon lengthening, hammertoe procedures, and MTPJ pinning lends further credence to Nery et al16 theory that MTPJ instability is multifactorial and needs to be addressed accordingly.
In our experience, the most common reported complications secondary to a plantar plate repair are continued joint instability or stiffness, lack of toe purchase, scar pain, and continued pain to the metatarsal head. Joint instability can result secondary to insufficient repair or rerupture of either the collateral ligaments or the plantar plate itself. Rerupture may occur due to inadequate fixation/suture-purchase or with insufficient débridement of attenuated or diseased plantar plate. Stiffness is typically the result of incomplete liberation of the plantar plate from the metatarsal head using a scoop-type elevator. One pearl to prevent MTPJ stiffness is to ensure capsular repair is performed with the joint in a functional or open-packed position, about 10° to 15° of plantarflexion. Lack of toe purchase results secondary to inadequate repair, recurrence, or improper positioning of the MTPJ during the repair. Inadequate decompression via the metatarsal osteotomy or débridement of diseased or attenuated tissue can lead to continued pain at the level of the metatarsal head. Intraoperative assessment of the repair and position of the toe is paramount in ensuring successful outcome. Upon loading of the forefoot, the repaired toe should rest in approximately 10° to 15° of plantarflexion in relation to the adjacent toes. Quality of repair is confirmed via dorsal drawer test intraoperatively. It is also imperative to obtain smooth, noncrepitant range of motion with simulated forefoot weight-bearing prior to completing skin closure.
Lesser toe subluxation/dislocation at the MTPJ joint that could be secondary to a number of factors, including but not limited to pain, trauma, microtrauma, chronic degeneration of joint and/or soft tissue, elongated or plantarflexed metatarsal, unaddressed metatarsal protrusion distance, or previous fracture with malunion.
Any form of revisional or reconstructive surgery should be avoided in the setting of peripheral vascular disease, acute/chronic infection, open wounds, and chronic rigid contractures at both the MTPJ and interphalangeal joints or in the setting of avascular necrosis (AVN) of the metatarsal head when osteotomy is considered. Amputation may be considered a viable option in the presence of these issues.
After the initial evaluation and meeting with the patient, but before any surgical discussion, one must acquire as much information and data from the previous surgery(s) that had been performed on the patient. Not only surgical and office records but also any medical imaging such as magnetic resonance imaging (MRI), computed tomography (CT), or vascular studies. It is essential to know what procedures were performed and prepare the surgeon for the most appropriate revisional procedure. This is extremely pertinent in regards to possible hardware removal, implantation of new hardware, bone size and stock for possible osteotomy/need for bone grafting, and availability of tissue for repair or transfer. The authors require all at-risk patients to medical clearance prior to any surgical procedures. Also, if the patient has any significant medical comorbidities or has had adverse effects in the past with anesthesia, the anesthesia team can provide a safe approach for the surgical procedure. General anesthesia is preferred with either popliteal/saphenous or ankle block. Supine positioning with or without bump under the ipsilateral hip and thigh tourniquet is applied. If dealing with bone graft or implants, one must make sure to have backup implants and grafts. This accounts for issues that may arise in the operating room during revisional surgery.
Surgical Techniques With Clinical Case Examples
Revisional Plantar Plate Repair With and Without Metatarsal Osteotomy
The lack of toe purchase, or more commonly “floating toe,” is historically the most common complication following the initial surgical treatment of lesser MTPJ pathology. The incidence of floating toe secondary to a Weil osteotomy has been reported as high as 57% to 68% at 3 to 6 months postoperatively.29,30 This may be secondary to the development of scar tissue and subsequent dorsal capsular contracture with a functional shortening of the extensor digitorum longus (EDL). Placing the toe in the open pack position or slight plantarflexion during capsular closure may hasten the formation of dorsal joint adhesions and subsequent contracture. The initial revisional treatment in these cases should involve an extensor tendon lengthening and dorsal capsulotomy.
From a structural standpoint, an undiagnosed plantar plate ligament tear, attenuation/deformity, previous inadequate resection of diseased plate, and unaddressed biomechanical deformities are commonly responsible for dorsal subluxation of the toe following the incident procedure (Figure 8.2). In these cases, repeat surgical intervention is required. A standard lesser MTPJ arthrotomy is performed as per surgeon’s preference. Once reaching the extensor tendons and capsule/hood and wing (if visible), these authors31 prefer to incise between the EDL and the extensor digitorum brevis (EDB) tendons for enhanced exposure to the MTPJ capsule for dissection purposes.31 It is important to note that with the development of scar tissue, adherence to solid surgical dissection to avoid any pitfalls of altered and abnormal anatomy is essential (Figure 8.3A.). A scoop-type elevator is then used, with care taken of the articular surface, to release any scar tissue or adhesion from the plantar metatarsal neck (Figure 8.3B). Once completed, the remaining soft tissue attachments at the MTPJ level are released to allow eventual distraction of the joint. The remaining portion of the ligament must be released from the base of the proximal phalanx which we find is best accomplished using a fine scalpel blade for more precise dissection around the irregularities of the phalangeal base. Proper attention must be given when this is performed, as the flexor tendons are directly inferior to the plantar plate. When releasing the medial and lateral collateral ligaments of the MTPJ from the metatarsal head, one must ensure the accessory collateral ligaments are adequately released as well (31). This full release is imperative to permit the ligament’s anterior translation allowing this to be redirected entirely beneath the base of the proximal phalanx, maximizing bone to ligament contact, thus creating a more stable and solid repair. Once the release is completed and the ligament is freely mobile, a Weil metatarsal osteotomy may be performed in standard fashion. Shortening is not necessarily needed unless the metatarsal is elongated or the previous osteotomy was inadequate in the amount of shortening required to reestablish the metatarsal parabola. The Weil metatarsal osteotomy is versatile in nature, as the capital fragment can be translated proximally to help shorten the metatarsal or decompress the joint.8,31 This can also be translated either medially or laterally in order to help redirect the toe/ray to move in a purely sagittal plane (Figure 8.3C).32–34 Quite often, once the osteotomy is made, the capital fragment will translate proximally and fall into the proper position.35 Next, the capital fragment is then pushed proximally, while remaining parallel along the metatarsal shaft, to a distance of 10 mm (Figure 8.3D) and then temporarily fixated to the metatarsal shaft with a pin. A pin is then placed in the base of the proximal phalanx of the corresponding toe (Figure 8.4A). A distractor is then placed on the pins, and the joint is distracted revealing the ligament and tear (Figure 8.4B). The diseased and remnant portion of the distal plate must be excised at this time to the level of optimal tissue. A healthy portion of the ligament is then grasped distally with a suture passing device. This can be a tight fit, so it is recommended to enter the joint with the instrument jaws closed and then deploy them once inside (Figure 8.4C). When passing sutures, try and place them in an articulated format which allows a more direct and balanced pull of the ligament ultimately aiding in the repair/reattachment as well as increasing pull-out strength (Figure 8.4D). Even a third separate strand of suture tape may be used to secure and incorporate the medial and lateral collateral portions of the joint (Figure 8.5). This can provide additional stability at the MTPJ level in the transverse plane and offers correction to medial-lateral deviation of the toe.
Once the sutures have been securely placed in the ligament, the distractor is removed and the toe is placed in plantarflexion to prepare the proximal phalanx to accept sutures. Caution must be taken to protect the distal overhang of the metatarsal from colliding with the toe and fracturing. This will be useful in determining measurements in order to maintain the most optimal parabola length pattern possible. With the toe held in plantarflexion, the plantar base of the proximal phalanx is roughed up using a rasp to aid in reattachment of the ligament. Next, the drill holes are placed into the base of the proximal phalanx from dorsal to plantar making sure to be distal to the subchondral plate to avoid invasion of the articular surface of the phalanx. Next, the sutures from the plantar plate are passed from the plantar aspect of the phalanx exiting the dorsal aspect of the phalanx in the holes that were previously drilled (Figure 8.6A to C). The ligament is then advanced anteriorly as the sutures are advanced dorsally (Figure 8.6D) holding the toe in a rectus and slightly plantarly displaced position. You should be able to visualize the ligament migrating back beneath the base of the proximal phalanx. In revisional cases, double-bundle repairs should be performed. Depending on the size of the patient, a third row may be useful to provide a more robust repair. Once this is completed, the distractor is removed. The capital fragment is returned to the desired length and position and fixated using 2 headless compression screws (Figure 8.7). This still allows for purchase of 3 cortices as the distal screw does not violate the weight-bearing surface of the metatarsal head. If shortening was involved, the overhanging portion of the distal metatarsal must be removed and smoothed down using a rasp. One may now start repairing the capsule with the toe held in a plantarflexed position to allow elongation of the dorsal capsule.35 Once your capsular closure reaches the sutures exiting the dorsal aspect of the base of the proximal phalanx, hold the toe in a slightly exaggerated plantarflexed position. Check to make sure the ligament is beneath the base of the proximal phalanx, and then tie the suture exiting the dorsal toe. Standard capsular and skin closure is performed. The authors prefer to tape the toe in a plantarflexed position using adhesive strips.