How To Handle Lapidus Complications
The lapidus arthrodesis for the treatment of symptomatic hallux valgus remains a controversial subject in foot surgery. Since its inception in the early 1900s, the lapidus arthrodesis has been abandoned by many surgeons mainly due to its high complication rate, particularly nonunion. However, it has regained popularity in recent years due to better fixation techniques and an improved understanding of first ray biomechanics. The major advantage of performing a metatarsocuneiform arthrodesis is it allows you to realign the first metatarsal at the apex of the deformity along with stabilizing the first ray. Moreover, the efficiency of peroneus longus in stabilizing the medial column is enhanced as well. The procedure also enhances the efficiency of the peroneus longus in stabilizing the medial column. The indications for lapidus are hallux valgus with an increased intermetatarsal angle, metatarsocuneiform joint arthrosis, hypermobility of the medial column and/or lesser metatarsal overload. It is also used as a salvage procedure for recurrent hallux valgus after a failed metatarsal osteotomy. One may treat some cases of hallux limitus secondary to a long metatarsal by shortening the metatarsal through the arthrodesis site. In 1935, Dudley Morton described a foot type in which first ray hypermobility is associated with ankle equinus and a short first ray and/or long second metatarsal. The concept of first ray hypermobility is difficult to quantify. However, its existence becomes obvious with certain clinical scenarios. You will typically see lesser metatarsalgia associated with discrete callosities in cases of first ray insufficiency. Radiographic features suggestive of hypermobility include metatarsocuneiform joint obliquity greater than 30 degrees, diastasis at the first metatarsocuneiform intercuneiform joint, cortical thickening of the lesser metatarsal shafts and a dorsal metatarsocuneiform traction spur. Longstanding hypermobility results in altered weightbearing mechanics and the ground reactive forces are transferred onto the lesser metatarsals and midfoot. In the early stages, one may see rupture of the second metatarsophalangeal plantar plate with digital dislocation. Stress fracture of the second and/or third metatarsal shafts is also an indicator of first ray insufficiency. Arthritis of the midfoot is typically an end-stage manifestation of untreated hypermobility. Using Two-Screw Fixation In First Metatarsocuneiform Joint Arthrodesis While there are several fixation techniques described for first metatarsocuneiform joint arthrodesis, two-screw fixation is required for a stable construct and is considered the standard of care. We utilize long cross screw fixation with 3.5-mm cortical screws, a technique advocated by Hansen. You would insert the first screw approximately 2 cm distal to the fusion site along the dorsal aspect of the midshaft region of the first metatarsal. One should position the screw’s long axis almost perpendicular to the fusion site. Doing so increases the screw’s compressive force. This orientation also resists the cantilever bending moment of the first ray. Place the second screw from the dorsal lateral aspect of the medial cuneiform into the metatarsal base. A third screw may be used if additional stability is needed. There are several options in regard to the alignment of subsequent screws. Patients with a wider first metatarsal may accommodate a third screw directly across the fusion site. Other options include placing a temporary screw from the first metatarsal base into either the second metatarsal base or intermediate cuneiform. This technique is often used to add stability to the construct during the bone healing process. A previous cadaveric study performed by the senior author demonstrated greater medial column stiffness with the second metatarsal screw when compared to the intermediate cuneiform screw. However, this finding was not statistically significant. Removing the second metatarsal screw does involve a risk for a stress fracture so one should closely monitor the patient’s progress after screw removal. How To Safeguard Against Incision Complications The dorsal medial cutaneous nerve is often located directly over the first metatarsocuneiform joint and is at risk for iatrogenic injury, especially with the typical dorsal medial incision. Be sure to direct the incision from proximal lateral to distal medial, paralleling the course of the medial dorsal cutaneous nerve. Making the incision in this manner allows you to easily identify the nerve and gently retract it so you may avoid a postoperative traction neuritis. A two-incision approach may reduce the risk of potential injury to the medial dorsal cutaneous nerve. This approach involves making a medial first metatarsophalangeal joint incision and an incision directly over the first interspace. One would perform a standard exostectomy and capsulotomy through the medial incision. You should be able to access the interspace and metatarsocuneiform joint through the incision directly over the first interspace, extending from the toes to the naviculocuneiform joint. Keep in mind that the deep peroneal nerve is more susceptible to injury with a widespread interspace dissection. The dorsalis pedis artery and the proximal intermetatarsal perforator are also at risk and transecting these structures may result in dehiscence of the surgical incision. In rare circumstances, injury to the dorsalis pedis artery or vein may lead to a pseudoaneurysm. What About Hardware Complaints? When it comes to fixating a first metatarsocuneiform joint arthrodesis, the hardware is not removed unless patients complain of prominent hardware or simply request its removal. We typically do not remove any hardware until six months to one year postoperatively and when the fusion site is completely solid. When employing the fixation technique described above, using a burr to countersink the screw head may help decrease the occurrence of a prominent distal to proximal screw head. However, be aware that using the burr too aggressively may sink the screw head into the metatarsal shaft and fixation will be compromised. A washer is a useful salvage device for increasing the surface area of the screw head, but you will need to remove this screw once patients return to their regular shoe gear. What You Should Know About Proper Positioning And Intermetatarsal Angles Proper positioning of the first metatarsal segment is the most critical aspect of the procedure. One should relocate the first metatarsal parallel to the second metatarsal and restore the weightbearing presence of the first metatarsal head. You should also return the sesamoids to a position beneath the metatarsal head. Improper reduction of the intermetatarsal angle (undercorrection) is usually well tolerated but it may be considered a poor cosmetic result and warrant revision. Failure to reduce the intermetatarsal angle may be caused by a poorly reduced fibular sesamoid, increased obliquity of the metatarsal cuneiform joint and/or abutting of the lateral flare of the first metatarsal base against the second metatarsal base. Some surgeons pre-emptively remove the lateral flare, although we typically leave it undisturbed to maximize the surface area at the fusion site. Some investigators have reported average postoperative intermetatarsal angles ranging from 2 to 9 degrees. However, McInnes and Bouche noted that a residual intermetatarsal angle greater than 10 degrees may be predictive of a poor outcome. We advocate aligning the first metatarsal parallel with the second metatarsal. Conversely, a negative intermetatarsal angle (overcorrection) may be the result of an aggressive resection of the metatarsocuneiform joint and/or a large resection of the lateral metatarsal base flare. Performing an interspace release with a sesamoidectomy may result in overcorrection and a postoperative hallux varus. An improperly positioned metatarsal in the sagittal plane is destined for problems. An elevated first ray will likely cause hallux limitus and potentiate transfer metatarsalgia. Stress fracture of the second metatarsal after a lapidus suggests that the first ray remains elevated. Improper resection of the metatarsal cuneiform joint often results in a dorsiflexed first ray, especially when the surgeon does not have a strong view of the inferior aspect of the joint. This is a common mistake by those who are inexperienced with the procedure and metatarsocuneiform joint anatomy. The metatarsocuneiform articulation is approximately 3 cm deep and one should use a modified lamina spreader to gain access to the plantar aspect of the joint during resection. Slight plantar positioning of the first ray is desirable for restoring both the windlass mechanism and the weightbearing ability of the first metatarsal. One can accomplish this by either translating the metatarsal plantarly or removing a plantar based wedge during joint resection. A rigid plantarflexed first ray will no doubt produce sesamoiditis and some patients may develop a discrete callus directly beneath the first metatarsal head. This occurrence rarely requires a surgical revision and responds well with an accommodative orthotic. Other Potential Complications To Keep In Mind • Hypertrophic fusion site. In these cases, the fusion site may become “bulky” and patients may complain of difficulty fitting shoes. Radiographs will often demonstrate excessive bone production and an exostectomy will likely solve the problem. If the deep musculature is injured during the fusion, a plantar hematoma may form and patients will complain of a firm nodule in the arch. Use deep massage to soften the muscle. Ultrasound may be helpful in some cases. • Shortening. Classically, numerous investigators have advocated a complete resection of the joint surfaces and shortening of the first ray is expected. However, one may preserve metatarsal length by removing only the articular cartilage. You may anticipate shortening of 0.5 cm of the first ray, depending on the joint preparation technique you utilize. Also anticipate increased bone loss when performing joint resection (via the saw) as opposed to articular cartilage curettage. Additionally, exuberant removal of bone to achieve correction will inevitably produce significant shortening. In some situations, a laterally based wedge from the medial cuneiform is needed to reduce the intermetatarsal angle and may shorten the metatarsal as well. Critical evaluation of the preoperative weightbearing X-ray is mandatory. In many situations, a shorter metatarsal segment may be tolerated as long as the first ray is in a fixed, plantarflexed position. However, shortening greater than 1 cm and symptomatic lesser metatarsalgia may benefit from restoration of the parabola with shortening osteotomies of the lesser metatarsals and/or a distraction lapidus arthrodesis. Key Pointers For Preventing Reoccurrence Unappreciated hypermobility at the naviculocuneiform or first metatarsocuneiform intercuneiform articulation is the culprit for reoccurrence after a lapidus bunionectomy. The prevailing thinking is that hypermobility predominately affects sagittal plane stability. However, some patients exhibit multiplanar instability. You should evaluate both the sagittal and transverse planes intraoperatively after stabilizing the first metatarsocuneiform. Splaying of the intermetatarsal angle indicates concomitant transverse plane instability and excessive sagittal plane motion indicates associated proximal instability. Transverse plane reoccurrence is often due to inadequate reduction of the intermetatarsal angle at the index operation. A residual hallux valgus will produce a persistent adducting retrograde force on the metatarsal and will likely cause intercuneifom joint widening among patients who have instability apart from the first metatarsocuneiform joint. A cadaveric study by Roling, et. al., demonstrated that the naviculocuneiform joint contributes up to 50 percent of total medial column sagittal plane range of motion. Faber, et. al., evaluated cadaveric hallux valgus feet and reported 57 percent motion at the metatarsocuneiform joint and 35 percent at the naviculocuneifom joint. Nonetheless, when there is intraoperative hypermobility after metatarsocuneiform joint fixation, you should address this with additional joint arthrodesis. In these situations, we have found that concomitantly fusing the first metatarsocuneiform intercuneiform articulation helps ensure sufficient first ray stabilization. In the original article by Lapidus, the first and second metatarsal bases were fused in conjunction with the first metatarsocuneiform joint. Alternatively, it may be necessary to perform a naviculocuneiform joint fusion as well. This should be determined on a case by case basis. In most situations, an isolated first metatarsocuneiform is sufficient to control medial column hypermobility. Pertinent Pearls For Dealing With Nonunions Delayed union or nonunion is a well-known complication with the lapidus procedure and occurs in approximately 3 to 12 percent of cases. This figure may be grossly inflated because many researchers reported total radiographic nonunions and did not distinguish amongst symptomatic nonunions. A radiographic nonunion may be considered a satisfactory result as long as the fusion site is stable and not painful. Symptomatic nonunions requiring revision likely account for the lower estimated percent of nonunion occurrence. McInness and Bouche reported a symptomatic revision rate in two of 25 patients (4.8 percent). Smokers account for a majority of nonunions and are four times more likely to develop bone healing complications. Encourage your patients to quit smoking prior to surgery and until a stable fusion is obtained. Some spinal fusion studies suggest the cessation of smoking may return the nonunion rate to that of non-smokers. Since nicotine is the active substance responsible for osteoblastic inhibition, all products containing nicotine (i.e. patches and gums) possess the same risk for nonunion and should not be substituted for smoking. An iatrogenic nonunion is typically the result of poor technique. Incomplete resection of the articular surface may not allow for adequate bone to bone contact. Additionally, one should perforate the subchondral plate to allow for osseous ingrowth. Be aware that thermal necrosis of the bone may occur if you use the oscillating saw for joint preparation. Copious irrigation is encouraged to decrease this occurrence. Stable fixation is necessary to obtain a solid fusion, and improper or poor fixation will promote a nonunion. In situations in which the crossed screw fixation is compromised intraoperatively, you may use a medial plate with screws as a salvage technique. Theoretically, one could employ an external fixator if the bone has been severely compromised but we have found the medial plate and screws work adequately. The plate may span the naviculocuneiform joint and/or the screws may traverse the intercuneiform joints to achieve a stable construct. Therefore, proper screw placement and technique are extremely important to avoid fixation difficulties. One may repair a symptomatic nonunion as early as six months postoperatively despite the defined terminology of a nonunion to be present after nine months of an inability to fuse. In most cases, one may attempt to use an external bone stimulator to consolidate the arthrodesis site prior to a revision surgery. However, it is essential to identify the etiologic causes that may have contributed to the nonunion in order to avoid the same result as the previous surgeon. The cornerstone for surgical treatment of a nonunion includes bone debridement, autologous bone grafting and solid stable fixation. Debride the fibrous bone until you see healthy bleeding bone, which may be difficult to ascertain if you are using a tourniquet. The amount of bone resected and the length of the first ray in relation to the second metatarsal will influence the autologous bone graft selection. Typically, we use the lateral calcaneus or distal tibia as the donor site. Avoid strictly cortical bone as it possesses less osteoconductive potential and a longer incorporation time in comparison to cancellous bone. In many situations, the cortical bone stability is needed and may be used in conjunction with cancellous bone as a bone block, but you should evaluate this on a case by case basis. If you use a bone block autologous graft, be aware that the fixation often involves a medial plate as well as interfragmentary screws. In some situations, one may use an internal bone stimulator (EBI) as well. How One Can Rectify Postoperative Complications Superficial cellulitis is a common complication after any surgery and is handled similarly for a lapidus arthrodesis. It’s often treated with oral antibiotics unless patients are demonstrating systemic symptoms. In these cases short-term treatment with intravenous antibiotics may be indicated. A deep infection of the fusion site is more problematic. Once you suspect osteomyelitis, the treatment will undoubtedly involve a six-week course of antibiotics. If an incision and drainage is necessary, tailor the antibiotics towards cultured pathogens. Otherwise, direct antibiotic therapy against the most likely pathogen, Staphylococcus aureus. The operative management of an infected fusion varies depending on the clinical presentation and the presence of a solid arthrodesis. An established bone infection early in the bone healing phase may require screw removal to eliminate the nidus for continued infection. In these situations, we may use a small monorail external fixator to stabilize the arthrodesis site until we’ve achieved a fusion, which may take approximately three months. We recommend adding autologous bone graft to the fusion site once the infection is controlled. Nonetheless, a fusion in the presence of infection is difficult to obtain and patients may undergo several revisions. How To Manage Post-Op Weightbearing Many surgeons avoid the lapidus arthrodesis mainly because the postoperative course involves a period of non-weightbearing until bony fusion has occurred, which takes approximately six to eight weeks. However, the postoperative weightbearing protocol varies among surgeons, institutions and geographic regions. Gentle weightbearing may begin as early as two weeks postoperatively and you can advance this accordingly if you have achieved solid internal fixation. Some investigators advocate a strict non-weightbearing period of eight weeks. Advance to full weightbearing once you identify radiographic evidence of consolidation along with the absence of tenderness at the arthrodesis site. Return patients to a stable sneaker eight to 12 weeks postoperatively. Lastly, postoperative compliance is crucial in obtaining a successful union. Avoid performing the lapidus arthrodesis for patients with a history of noncompliance. Unlike base wedge osteotomies, plastic deformation elevatus of the metatarsal is not seen in lapidus after early weightbearing. Be aware that noncompliance often results in slower bone healing, fixation failure and/or possibly nonunion. When The Lapidus Is Contraindicated Some authors suggest the lapidus is contraindicated in the presence of a short first metatarsal, hallux metatarsophalangeal joint arthrosis, in adolescent patients with open growth plates and in cases of gross osteoporosis. However, these are not absolute contraindications and one may use the lapidus cautiously in the above scenarios. The lapidus arthrodesis is the procedure of choice for treating adolescent hallux valgus with concomitant hypermobility. You may obtain a successful fusion with open growth plates and Steinmann pins are recommended to limit damage to the physis. Often, adolescents are encouraged to postpone surgery until skeletal maturity. Osteoporosis is a relative contraindication for the lapidus arthrodesis and has been avoided by some surgeons for a variety of reasons. Rarefaction of bone reduces the ability of internal fixation to gain adequate purchase and maintain stability across the fusion site, especially in advanced stages of osteoporosis. One may overcome the loss of stability by adding a plate with screws and this should be considered prior to attempting isolated screw fixation. Osteoporosis typically involves an older/geriatric population so maintaining compliance with the postoperative weightbearing protocol may be difficult. Most importantly, you must consider the daily living activities of older patients. Some may be better served by alternative methods of treatment. Nonetheless, one should closely monitor elderly patients with osteoporosis who undergo a midfoot fusion. Final Thoughts Performing the lapidus arthrodesis corrects metatarsal primus adductus as it enables you to address the etiology at the apex of the deformity along with stabilization of the first ray. It is a powerful, predictable procedure but it is not without its limitations. First metatarsocuneiform joint arthrodesis is not the answer for all symptomatic hallux valgus and patients should be carefully selected based on age, duration of symptoms, activity level, deformity, compliance and expectations. The lapidus arthrodesis is technically challenging and possesses a large learning curve. Understanding the potential complications will help curtail postoperative errors and lead to better overall results. Dr. Blitz is an attending podiatric surgeon within the Department of Orthopedics at the Kaiser Permanente Medical Center in Santa Rosa, Calif. Dr. Ray is in private practice at the Foot and Ankle Clinic of Montana in Great Falls, Mt.
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