Posttraumatic Reconstruction of the Foot and Ankle







Additional videos related to the subject of this chapter are available from the Medizinische Hochschule Hannover collection. The following videos are included with this chapter and may be viewed at expertconsult.inkling.com :



  • 68-1.

    Surgical technique—ankle arthrodesis with a retrograde nail.


  • 68-2.

    Surgical technique—ankle arthrodesis by external fixation.


  • 68-3.

    Surgical technique for dislocation fractures of the Chopart and Lisfranc joints.


  • 68-4.

    Operative techniques for ankle arthrodesis, including techniques with severe bone loss.


  • 68-5.

    Correction of poorly healed tarsal fractures.


  • 68-6.

    Open repair of Achilles tendon (mini-open).




Lower Limb Alignment and Joint Orientation


Residuals of trauma are a major cause of symptoms in the foot and ankle. The reason is that, until recently, foot injuries were not treated as aggressively and expertly at the time of initial trauma as were the long bone and other joint injuries. In addition, the foot and the ankle are less prone to pure degenerative arthritis or osteoarthritis than are the knee, hip, spine, or even hands.


It is widely recognized that injuries to soft tissues, including the ligaments and tendons, can lead to significant arthrosis in the ankle and in the foot itself. Many case reports of ankle fusion or arthroplasty list osteoarthritis as the primary diagnosis. However, on careful evaluation of histories and physical examinations, it is clear that the ankle arthrosis was caused by old lateral ligament injuries. In the same way, posterior tibial tendon trauma or degeneration leads to valgus malalignment and secondary arthrosis in the foot and, eventually, the ankle. Even peroneus brevis or brevis and longus tears or ruptures lead to increased varus and eventual arthrosis. Trauma involving the joints of the ankle and foot is the most common cause of symptoms leading to the need for ankle and foot reconstruction requiring fusion.


Pilon fractures in the ankle, in which the weight-bearing articular surfaces have been damaged, are the most susceptible to arthrosis either with or without good initial treatment. In most other ankle fractures (except chondral injuries), deformity and late complications can be significantly reduced by good initial treatment. Severe intraarticular calcaneal fractures can lead to arthrosis in the subtalar joint with or without good initial treatment. Naturally, treatment is simplified when the body of the calcaneus has been anatomically reconstructed and maintained. Trauma to the talus resulting in a type III or IV fracture may lead to avascular necrosis (AVN) despite good initial treatment and present a reconstructive challenge. In types I and II talar fractures, as well as in many body and peripheral fractures, optimal initial treatment minimizes complications and the need for reconstruction.


Intraarticular fractures in nonessential joints, for example, the naviculocuneiform, the intercuneiform, and the first, second, and third tarsometatarsal joints, are easier to treat or reconstruct because, by definition, stability is important in these joints but motion is not. Fusions can provide adequate treatment here if the anatomic structure has been restored.




Principles


An important principle in reconstructive foot surgery is to identify the cause of a problem. It might seem obvious that if a patient develops midfoot arthrosis following a Lisfranc injury, arthrosis and collapse are caused by inadequate fixation of the Lisfranc injury. However, it is less commonly recognized that a tight gastrocnemius might be a contributing factor if it applies a strong plantar flexion force to the hind foot and stresses the healing midfoot and its supportive plantar ligaments. Prior to a Lisfranc injury, the plantar fascia, the long plantar ligament, and the plantar articular ligaments can resist this force, but once damaged, they no longer can. Treatment by realignment and fusion of the affected Lisfranc joints might be inadequate, and gastrocnemius lengthening should be included in the treatment. In the author’s Foot and Ankle Institute training program, we propose the philosophy that “nothing happens for no reason.”




Physical Examination


The purpose of the initial physical examination of a symptomatic foot is to ascertain the underlying condition causing the problem. Evaluation begins with a careful examination of the noninjured or asymptomatic foot, assuming that the other side was spared injury. With this information, the surgeon can make theoretical assumptions about the condition of the foot before it was injured and answer some basic questions, such as the following: Did the patient have a tight gastrocnemius or heel cord ( Fig. 68-1 ), varus or valgus heel alignment, a low or high arch? Was muscle balance in the long toe flexors and extensors good or was it disordered ( Fig. 68-2 )? Does the long peroneal show signs of overuse or overdrive? Is plantar flexion in the first metatarsal dynamic or static ( Fig. 68-3 )? Is there evidence of forefoot-driven hind foot varus or valgus ( Figs. 68-4 and 68-5 )?




Figure 68-1


A, To inspect for gastrocnemius equinus, the examiner sits in front of the patient on the examining table and stabilizes the hind foot and medial column in a neutral anatomic position. Using the right hand for the right foot, the examiner places the thumb on the head of the talus just proximal to the navicular tubercle while the fingers grasp the heel to keep the hind foot out of valgus. The examiner’s opposite hand holds the forefoot in adduction and the lateral metatarsals plantar flexed in line with the hind foot. B, The patient is asked to relax, neither assisting nor resisting the examiner, and passive range of dorsiflexion is tested with the knee straight (gastrocnemius on stretch proximally) and with the knee bent (proximal end of gastrocnemius relaxed). If dorsiflexion from neutral is essentially absent with the knee straight or, in fixed equinus, if dorsiflexion with the knee bent is greater than 20 ± 5 degrees, the gastrocnemius is probably pathologically short or tight and adds functional stress to the heel cord, plantar fascia, plantar ligaments, and the posterior tibial muscle and tendon. C, Confusion can arise if the examination is done inconsistently or incorrectly. Unless the foot is stabilized with the medial column locked, the ankle may appear to be in approximately 10 degrees of dorsiflexion. D, When a patient actively dorsiflexes the foot while it is not stabilized, it may dorsiflex 10 degrees or more. The test must be done with the muscles relaxed and the foot stabilized in exactly the same way each time. Each examiner develops a feel for the range between normal and abnormal in this examination. I think gastrocnemius lengthening is warranted when there is essentially no dorsiflexion with the knee straight and the foot stabilized and (with the foot held in exactly the same way) when dorsiflexion reaches or exceeds 15 degrees with the knee bent.



Figure 68-2


The patient is attempting to dorsiflex the ankle with the knee straight. Notice that the toes are all maximally extended. Such recruited activity indicates a very tight gastrocnemius. In this situation, it is common for “extensor recruitment” to occur—the toe extensors help the tibialis anterior and the peroneus tertius (the primary dorsiflexors) to dorsiflex the ankle. When the intrinsics are weak, denervated (e.g., diabetic neuropathy), or destroyed by inflammation (e.g., rheumatoid arthritis), subluxation and eventual dislocation of the toes will occur. Treatment consists of lengthening the gastrocnemius and transferring the long toe extensors into the midfoot or the peroneus tertius.



Figure 68-3


A, This patient has a plantar-flexed first metatarsal. Notice the dorsiflexed lesser toes and the presence of heavy callus primarily under the first metatarsal head. A dynamic deformity exists when the apparent medial cavus can be reduced by passively pushing the first metatarsal up to the level of the lesser metatarsals. If this maneuver does not correct the deformity, it is determined to be static or bony. B, To ascertain whether first metatarsal plantar flexion deformity is static or dynamic, the examiner places one thumb under the lesser metatarsal heads and the other thumb under the first. If the first metatarsal head plantar-flexes below the lesser heads only when the patient plantar-flexes the ankle and foot, the cause is dynamic overactivity of the peroneus longus.



Figure 68-4


A standing view from behind shows a patient with long-standing flat feet and mild heel valgus. A couple of years earlier, the patient experienced proximal medial arch pain on the left side and progressive flattening of the arch with severe heel valgus. Examination of that side revealed a very tight gastrocnemius, inability to do a single-leg heel rise, and inability to plantar-flex and invert the foot. The first metatarsal is hypermobile and elevated. These symptoms are classic indications of rupture of the posterior tibial tendon.



Figure 68-5


Both heels of this young woman are in varus, more pronounced on the right than on the left. She was more symptomatic on the right and experienced pain and swelling behind the lateral malleolus. On a Coleman block test, the hind foot straightened out to near normal but did not go into valgus. The peroneus brevis was very tender. These findings are all consistent with a combined forefoot-driven and fixed hind foot varus deformity, commonly seen with a longitudinal tear of the peroneus brevis. Treatment involves moving the peroneus longus into the distal brevis on the lateral side of the foot, carrying out a lateralizing calcaneal osteotomy, and repairing the peroneus brevis.


With knowledge of the probable preinjury status in mind, the examiner turns next to the affected foot. Other injuries in the same extremity, such as posttraumatic tibial varus or valgus, extension or malrotation, a shortened leg, a longer leg, must be noted. The injured foot must be evaluated for adequate circulation and sensation as well as muscle power and balance. Circulation can be evaluated by noting the quality of the skin and soft tissues and capillary refill. Pulses are palpated, and lower extremity pressures are compared with those in the upper extremity. If circulatory capacity appears to be inadequate, Doppler studies or angiography might be needed before major reconstruction is planned.


Neuropathy caused by nerve injury, diabetes, excessive height in older patients, or other diseases or idiopathic causes can greatly affect the type of treatment that should be prescribed. For example, ankle joint replacement is contraindicated in a neuropathic foot, but gastrocnemius lengthening is more strongly indicated here than in a foot without neuropathy. Motor power in all intrinsic and extrinsic muscles should be evaluated, as well as any limitation in range of motion that might be related to tethering or chronic compartment syndromes. Intrinsic flexor deformity and fixed claw toes are commonly seen in patients with calcaneal fractures.


Muscle imbalance between the plantar flexors and dorsiflexors of the ankle, the plantar flexors and dorsiflexors of the first metatarsal, and the invertors and evertors must be noted and corrected. Peroneus brevis or combined peroneus brevis and peroneus longus ruptures, for example, frequently go undiagnosed and lead to a progressive cavovarus deformity in the foot and instability in the ankle ( Fig. 68-6 ). More commonly, deficits in the posterior tibial tendon lead to progressive valgus deformity in the foot with collapse of the medial column (arch) by stretching of the spring ligament or plantar capsule and the ligaments of the naviculocuneiform and cuneiform–first metatarsal joints. Eventually, this leads to lateral erosion in the ankle and/or stretching of the deltoid ligament.




Figure 68-6


The left foot of a 50-year-old man with a long history of moderately severe cavovarus feet abruptly became more symptomatic and the ankle unstable after rupture of the long and short peroneal tendons. Notice the proximal displacement of the os peroneum. Muscle balancing plus calcaneal and first metatarsal osteotomies resulted in a satisfactory outcome.


Whether the heel is in neutral, varus, or excessive valgus, weight-bearing alignment in the hind foot must be evaluated, in addition to the relative position of the midfoot and forefoot to the hind foot. The relative length of the medial and lateral columns controls the position of the forefoot relative to the hind foot. Rigid plantar flexion in the first metatarsal can cause forefoot-driven hind foot varus, whereas a hypermobile first metatarsal or medial column allows the arch to sink and the hind foot to go into secondary valgus. This condition is frequently called “excessive pronation.”


After all the information is gathered from the physical examination, appropriate radiographs should be taken and a treatment plan formulated.




Imaging Studies


Radiographs of the foot are taken with the patient standing with full weight-bearing and the knee extended to reveal whether the gastrocnemius is a contributing factor to the abnormality. Voluntary attempts by the patient or the radiographer to correct the position of the foot should not be allowed. The goal is to show the deformity or functional problem, including sag or subluxation at the normally stable midfoot joints, on the radiographs. The radiography series should include at least weight-bearing anterior-posterior (AP) and lateral projections of the foot, and oblique views are needed if abnormalities are suspected in the more lateral cuneiform or cuneiform-metatarsal joints. In the ankle, weight-bearing lateral, AP, and mortise views are obtained. A computerized axial tomography (CAT) scan may be helpful before reconstruction of complex malunions in the talus or the calcaneus and, rarely, of pilon fractures.


Magnetic resonance imaging (MRI) is sometimes used for evaluation of soft tissue injuries, but they usually can be diagnosed perfectly well by physical examination alone. In my experience, MRIs produce many false-positive pathologic diagnoses in the foot and ankle. Malunions frequently require complex osteotomies, particularly in the talus and calcaneus, and CAT scans can be very useful there. They are less necessary for diagnosing ankle or pilon fractures but can be helpful for planning reconstruction.


Nonunions are easier to treat if they are not malpositioned. Avascular necrosis takes time to stabilize and may take as long as 18 to 36 months. MRI tends to overread AVN and usually indicates a larger area of necrosis than actually exists. I base my diagnosis on evaluation of the initial injuries and watch what happens over time, especially with weight-bearing. Good plain films and, to some extent CAT scans, provide an idea of how much bone is necrotic and interferes with function, requiring removal. Posttraumatic AVN tends to be irregular and incomplete when compared with AVN caused by use of corticosteroids or other drugs, and it is compatible with fusion, arthroplasty procedures, or both.




Malunion, Nonunion, and Degenerative Spur Formation on the Talus, Including the Os Trigonum, and Osteochondrosis


The key to correction of many problems in the talus is adequate surgical exposure. Surgery in this area requires visualization of the affected part of the talus with enough room to manipulate a fragment. It is important not to disturb the blood supply, the local nerves, or the ligamentous structures in the course of making the incision. These are general requirements of all surgical exposures, but access to the talus is more demanding because it is hidden under the malleoli medially and laterally and is covered by deep soft tissues over its posterior aspect, and the major neurovascular structures and tendon groups to the foot are located at its posteromedial corner.


I recommend anteromedial and anterolateral surgical incisions for access to the talar neck and virtually always use a combination of these approaches. For the posterior body, I prefer a transmalleolar (medial) approach through an extended medial utility incision. For an approach to the lateral body that entails a double osteotomy of the fibula, I use a fibular “window” approach made through a vertical-lateral skin incision. For the posteromedial corner fragments, I make an inferomedial approach, which, in fact, is the upper end of a medial utility incision and allows access to the talus between the posterior tibial and flexor digitorum longus tendons and neurovascular structures. To approach the os trigonum and the posterior aspect of the talus and posterior degenerative spurs, I make a vertical posteromedial incision well in front of the heel cord. I go in laterally through the deep posterior compartment fascia and lateral to the neurovascular structures and the flexor hallucis longus. The sheath of the flexor hallucis longus can be loosened and the tendon pulled medially along with the neurovascular structures to provide excellent exposure of the posterior subtalar joint and the posterior talus. A straight vertical posterolateral approach, with care taken around the sural nerve, provides probably the most complete exposure of the posterior ankle, talus, and subtalar joint. This approach requires the patient to be positioned laterally, whereas the posteromedial approach requires the patient to be supine while the foot is rolled up in a figure-four position.


The author no longer inserts screws from posterior for talar neck fractures, since this offers no real advantage to compensate for the awkward positioning of the patient. However, posterior medial talar body fractures are seriously disabling if not recognized and fixed early, after which they generally do very well. For these, I continue to employ a posterior approach.


Débridement of the anterior aspect of the ankle, including spurs or bossing on the neck of the talus, is carried out through slightly more proximal anteromedial and anterolateral surgical approaches in order to visualize the ankle joint from both sides. Care must be taken on the lateral side to avoid coming in too low and inadvertently dividing the anterior talofibular ligament in the sinus tarsi. Either or both of these incisions may be used, depending on whether the abnormalities are located more medially or more laterally. For extensive reconstruction, I frequently make both exposures and use a – or -inch gouge to completely redevelop the neck of the talus and provide adequate clearance at the ankle joint. Note that we no longer débride more than obvious spurs on the tibial anterior malleolus in order to not diminish the anterior containment function of the anterior malleolus. Aggressive débridement increases instability and, therefore, arthrosis. Most of the impinging bone is removed by grooving the neck of the talus and taking very little bone from the front of the tibia. Bone wax is placed on raw bone in this area.


Débridement of the sinus tarsi is done through a short section of the Ollier approach. This oblique surgical approach is made along the skin line and can be placed directly over the sinus tarsi. The approach is made after lifting the proximal end of the extensor digitorum brevis off the anterior calcaneus and removing some fat and possibly part of the cervical ligament from the sinus tarsi. Débridement of any prominence or excrescence and fracture stabilization of the anterolateral shoulder of the talus can be done then as needed. Again, care is taken to avoid going in too high in this approach and risking division of the anterior talofibular ligament. Sinus tarsi débridement may be needed and can be helpful when an ankle fusion is performed. In a stiff, arthritic ankle, especially one that has been in varus, spurs may have developed in the subtalar joint laterally on the anterior process of the posterior facet and also posteriorly at the subtalar joint. After ankle fusion, full range of motion will be needed in this joint; this can be facilitated by débriding spurs both in the sinus tarsi and posteriorly.


Osteochondrotic Lesions on the Dome of the Talus


The author has begun to use osteochondral plugs to repair osteochondrotic defects in the talus that are up to 1.5 cm in diameter. The ipsilateral knee is used as the donor site, and the talus is visualized through an arthroscope both to determine an indication for the procedure and to assess the size of the plug that will be needed. The operation is carried out through an open surgical approach. On the medial side, a medial malleolar osteotomy is performed and the talar dome is tilted out. This is followed by the standard approach and placement of an osteochondral plug taken from the lateral condyle of the ipsilateral knee. This approach is less common on the lateral side to provide a vertical look at a lesion on the lateral dome of the talus. However, it can easily be done through the fibular window approach. A straight vertical and lateral incision is made over the fibula to expose it, and the fibula is transected just below and approximately 6 to 8 cm proximal to the dome of the talus. The fibula is rotated posteriorly on its peroneal tendon and sheath attachments. A Schanz pin is placed into the anterior body of the talus, and the talus is pulled slightly to the lateral side and tilted and then flexed or extended until the lesion presents in the fibular notch of the tibia. This approach allows direct vertical visualization of the lesion as well as simple removal of the defect and implantation of the osteochondral plug in the standard manner.




Calcaneal Malunion and Nonunion


Good visualization of the calcaneus is much easier to achieve than visualization of the talus. The lateral extensile incision commonly used for open reduction and internal fixation (ORIF) of the calcaneus also works well for reconstruction. However, for other procedures, such as medializing or lateralizing osteotomies perpendicular to the tuber, other incisions are smaller and safer. I use extensile lateral L or J incisions for triplane osteotomies and to correct intraarticular malunions without subtalar fusion. A small lateral oblique incision over the tuber is satisfactory for simple medial, lateral, or plantar displacement osteotomies of the tuber. For subtalar fusion with bone block distraction, I frequently make a long vertical posterolateral incision and occasionally sacrifice the sural nerve. A femoral distractor is used on the medial side to ensure that the distracted joint is not pushed into varus, a common event with distraction from the lateral side.


Every malunion is unique, and only general principles can be described in a discussion of nonspecific conditions. However, some guidelines apply to all calcaneal malunions. The original fracture line or a composite of the original fracture lines must be re-created by an osteotomy and the original anatomy of the calcaneus restored as well as possible. Common findings in many os calcis fractures that were not restored by immediate ORIF include a tuber that is tilted into varus but displaced laterally and a heel that is shortened in terms of lateral column length and vertical height. All these abnormalities can be corrected by an oblique osteotomy started more anteriorly on the lateral side of the heel and angled posteriorly and medially ( Fig. 68-7 ). Usually, the obliquity is located closer to the frontal plane than to the sagittal plane, and, in this case, the amount of valgus that is corrected is greater than the amount of lateral column lengthening that occurs. This is usually desirable.




Figure 68-7


Osteotomy for triplane correction. A, A posterior illustration depicts residuals of a calcaneal fracture displaced in valgus. Notice the impingement under the tip of the fibula and lateral displacement in relation to the weight-bearing line of the tibia. Solid and dotted lines outline the osteotomy for correction. Displacement of the tuber medially will correct the valgus. B, Seen from the lateral side, the hind foot demonstrates loss of height and calcaneal pitch as a result of a crushing fracture through the subtalar joint. Solid and dotted lines indicate the plane of the potential corrective osteotomy. The osteotomy line helps the surgeon visualize how plantar translation of the tuber can correct height and calcaneal pitch. C, Seen from above, it is clear how medial translation of the heel, the third (transverse) plane of correction, will add overall length to the heel. D, After osteotomy and fixation, the posterior tuber is displaced medially, inferiorly, and posteriorly. Two 3.5-mm or, preferably, 4.0-mm cortical screws are placed in lag fashion perpendicular to the osteotomy. Two 6.5-mm cancellous screws are placed from the tuber across the osteotomy and nearly perpendicular to the posterior facet, where the joint has been curetted and packed with cancellous bone chips removed from the expanded lateral wall. E, The position of the tuber has been corrected in three planes and stabilized with screw fixation. Plantar displacement and increased height and pitch angle of the heel are obvious. F, Medial and posterior translation of the heel and the angles of the fixation screws are seen from above.


In addition to the osteotomy, the local soft tissues should be carefully stretched without damage inflicted to the nerves or blood supply going to the bony fragments. Sometimes the tendo Achilles should be lengthened; in other cases, just the scarred sheath and periosteal tissues should be stretched. This allows the surgeon to slide the posterior or tuber fragment in three directions along a single plane. The tuber can be moved medially and posteriorly, or it can be displaced inferiorly (or both). After the heel cord is lengthened, the fragment can be rotated slightly out of varus tilt. Rotation is simple when the osteotomy is transverse but becomes quite complex when the osteotomy is made oblique to the frontal plane to obtain lateral calcaneal length. The osteotomy is then stabilized with at least two screws placed into the os calcis perpendicular to the osteotomy plane. When the subtalar joint is severely arthritic, a small amount of cartilage may be curetted from the subtalar joint or a divot or burr hole made in the joint and filled with cancellous bone. Bone can be taken from the Gerdy tubercle area or the expanded lateral wall that was excised at the beginning of the procedure. Two additional screws may be placed from the tuber and angled across the osteotomy and up through the subtalar joint.


Intraarticular malunions that can be reconstructed require a surgical approach similar to that used for an os calcis fracture. The joint is visualized and appropriate osteotomies are made to simulate the initial fracture and realign the articular surface in its original anatomic position. This is not always possible, and this procedure is difficult at best. The same precautions that are observed during a lateralizing calcaneal osteotomy apply: The surgeon must be careful to avoid the neurovascular structures, particularly the lateral plantar nerve when it is entrapped in scar. This nerve runs close to the medial calcaneus in the area of the usual osteotomy and is sandwiched between the quadratus plantae and the flexor digitorum brevis, which may be damaged by fracture and scar down the nerve. The nerve can be damaged easily by pinching or stretching, and it can be inadvertently cut by an osteotome. When possible nerve damage is anticipated, it may be prudent to add a medial approach, similar to that used for a tarsal tunnel release, to protect the neurovascular structures by direct observation and mobilization.




Navicular Nonunion and Malunion and Talonavicular Arthrosis


As in the talus, the blood supply of the navicular must be protected during a surgical approach to the navicular. The navicular is vascularized through peripheral soft tissue attachments and periosteum, so stripping of these structures must be minimized. The approach should be made directly over the fracture or nonunion site, usually on the dorsal or dorsolateral side. An incision in this area should be longitudinal and in line with the neurovascular structures, which must be identified and moved aside. The fracture or nonunion site can be entered directly, and any hematoma or fibrous tissue can be removed with little or no stripping of soft tissue attachments.


When a nonunion is to be taken down, a slightly longer incision is made to open the talonavicular joint (and possibly the naviculocuneiform joint) wider to determine where to make the osteotomy cuts. The objective is to reconstruct the talonavicular joint as anatomically as possible without much concern for the naviculocuneiform joint, which moves very little and can be fused without loss of function. The fracture can be reduced by direct visualization and compressed with a Weber or other sharp-tipped (towel clip–like) forceps. Appropriate drill holes are made, and lag screws are inserted through stab wounds, usually from the lateral side and with the help of image intensifier guidance, if desired. The peripheral tissues on the lateral side should not be stripped more to make room for placing the screws under direct vision.


This technique works particularly well for treatment of displaced or nonunited stress fractures, which generally are more or less vertical fracture lines lying slightly lateral to the midline. In recurrent or persistent navicular stress fractures, the presence of a calcaneonavicular coalition should be ruled out by careful inspection of an oblique radiographic view and possibly a CAT scan. In my experience, other types of nonunions are rare, but the same principles would apply to their correction. The site at which the surgical approach is made varies with the site of the nonunion, as does the direction from which the screw is inserted. Unfortunately, the lateral portion of the navicular is extremely comminuted in some nonunions and cannot be reduced as a block to the medial column. In such cases, it is important to position the medial (usually larger) block in precise relationship to the first and possibly the second cuneiform. These bones (the navicular and the first and second cuneiforms) are fused without shortening but rather by inserting a bone block graft or chips of cancellous bone into a shear strain–relieved site. Alternatively, a block or cylinder rotated at 90 degrees may be used. This technique can be used in acute situations to keep the usually intact larger medial fragment correctly positioned and to allow the comminuted lateral segments to be trapped in place and to regenerate. The articular surface fragments may be pushed up against the head of the talus, and the talonavicular joint may be stabilized temporarily with large Kirschner wire (K-wire) fixation for 2 to 6 weeks. Fusion of the navicular and the first and second cuneiforms is particularly advantageous in the treatment of nonunion because it provides stability and possibly enhances blood flow to the healing site ( Fig. 68-8 ).




Figure 68-8


Naviculocuneiform joint fusion. A, The solid line shows the location of the medial utility incision, which is used to expose the naviculocuneiform joints for arthrodesis. B, Arthrosis (with sag) is seen in the naviculocuneiform joint. Notice the anterior tibial tendon, which is used as a guide to the joint and which must be protected during exposure of the medial cuneiform while screws are being placed. The anterior tibial tendon attaches on the medial plantar surface of the base of the first metatarsal and can be moved distally or proximally on the medial cuneiform. Cartilage at the first and second naviculocuneiform joints is débrided with small osteotomes and curettes, and the subchondral bone is perforated at multiple sites with a 2.0-mm drill. The bones are then aligned and stabilized. C, A dorsal-plantar view of the area depicts the screw configuration we have found to be most successful. Because these joints are hard to fuse, they must be rigidly stabilized. Shear strain–relieved bone grafts are placed at least in dorsomedial and plantar medial sites (not shown). The more plantar screw (3.5- or 4.0-mm cortical) runs from the tubercle of the navicular nearly parallel to the medial border of the foot and into the lower half of the first cuneiform. The second screw runs from a site more dorsal on the tubercle across and into the shallower second cuneiform. The third screw is started distal to the crossed anterior tibial tendon and angled across and into the lateral navicular. In some cases, a fourth screw is angled from the medial border of the cuneiform back across and into the navicular. D, The screw configuration across the reduced naviculocuneiform joints is depicted on a medial view. The same principles apply when this fusion is done in conjunction with nonunion at the mid to lateral third of a navicular fracture with comminution of the lateral navicular body.

(Source: Adapted from Hansen ST Jr: Functional reconstruction of the foot and ankle, Philadelphia, 2000, Lippincott Williams & Wilkins.)


After temporary fixation and placement of the bone grafts, at least three (and possibly four) screws should be placed. I generally use 2.7- or 3.5-mm screws, depending on the size of the patient, running one screw from the tubercle of the navicular across to each of the first and second cuneiforms. The third, and possibly the fourth, screw is placed retrograde from the distal medial first cuneiform into the lateral navicular. Newly developed 4.0-mm, so-called Lisfranc screws with a cortical thread design, are ideal for use in larger patients, and at the Foot and Ankle Institute, we have begun to use them in most patients. In cortical screws, the core diameter is significantly bigger and breakage is less common, but they still have equal compressive ability, sometimes called “pullout strength.”


Talonavicular Fusion for Arthrosis


The major difficulty in the treatment of talonavicular arthrosis is attaining the correct alignment. Basically, the talus, the navicular, and the first cuneiform–first metatarsal should be aligned almost exactly straight in both AP and lateral radiographic projections. The next consideration is to not shorten the medial column, which would be similar to over-reducing the navicular medially on the head of the talus and placing the foot into supination. Subchondral bone is preserved on the joint to avoid shortening. At least two shear strain–relieved bone graft sites are made by burring evenly spaced divots into the joint surfaces on each side and packing them with cancellous bone. As a result, the screws transfixing the joint need not be compressed, and they function as position screws that maintain the foot in exact position.


A supinated foot is rigid and can produce significant disability. Patients frequently walk on the base of the fifth metatarsal, often with the heel in varus and with a stiff, uncushioned gait. A small amount of pronation is preferable, but excessive pronation stresses the deltoid ligament and the posterior tibial tendon and eventually causes failure in the lateral portion of the ankle, just as excessive varus or valgus does in the knee.


Talonavicular fusion without repair of a navicular fracture, nonunion, or malunion is done through a medial utility incision. It is carried along the medial side of the joint between the anterior and posterior tendons, far from any significant neurovascular structures other than veins with multiple branches (see Fig. 68-19 ).




Cuboid Malunions and Nonunions with and Without Lateral Column Shortening


Problems with the surgical approach and the blood supply are not as significant in the cuboid because the proportion of soft tissue attachment to articular surface is greater there than in the talus and the navicular. The major problem with cuboid fractures is to regain the length of the lateral column, since lateral column shortening causes forefoot abduction and progressive disruption of normal function. The amount of abduction, and possibly pain from arthrosis, in the calcaneocuboid and/or cuboid fourth and fifth metatarsal joints is directly related to the amount of shortening.


A dorsolateral linear incision is used to approach the cuboid, taking care to protect the sural nerve, and a lateral external fixation device or a distractor is attached from the lateral os calcis to the base of the fifth metatarsal. If the fracture has united short, the distractor can be lengthened gradually as the osteotomized fracture is manipulated to length. The incision must be low enough along the border to enable the surgeon to reach underneath to reapproximate the joint surfaces. Sometimes the calcaneocuboid joint requires bone block fusion to restore adequate or anatomic lateral column length. The surgeon must decide whether to lengthen the lateral column through the cuboid or the calcaneonavicular joint by evaluating the radiograph to determine where the shortening exists. It is usually better to lengthen the cuboid and preserve the calcaneocuboid joint if lateral column shortening is caused by a compression fracture.


Cuboid–Metatarsal Fourth and Fifth Joint Arthrosis


Treatment of arthrosis in the cuboid-fourth and -fifth metatarsal joints is an enigma. These joints do not fuse readily, and when they do, they frequently remain symptomatic because the small amount of motion they normally have is needed to provide cushioning along the lateral border. Normally there is no lateral arch, and the only soft tissue structure to enter the foot from the lateral side is the long peroneal coming through a groove in the cuboid.


It seems that the lateral side of the foot requires a certain amount of cushioning or expansion joint function, and when the calcaneocuboid joint is fused, the cuboid fourth and fifth metatarsal joints are pressed into service. These joints can be symptomatic when they are overstressed, and discomfort can be alleviated by use of orthotics or a thick, soft-soled shoe. Fusion here is unreliable and probably unwise. In rare cases, arthroplasty by a type of “anchovy” procedure is helpful, but there is no definitive solution to cuboid fourth and fifth metatarsal joint arthrosis.




Metatarsal Nonunions and Malunions


Significant malunion in major metatarsal fractures, particularly multiple fractures, can disrupt forefoot alignment significantly and disturb normal forefoot weight-bearing. Disabling symptoms can develop whenever weight-bearing is concentrated under one or two metatarsals or any number fewer than the normal six contact points. These contact points are the tibial and fibular sesamoids under the first metatarsal head and the four lesser metatarsal heads. Contrary to what was taught a few decades ago, there is no such thing as a transverse metatarsal arch at the metatarsal head level, and ideally all the metatarsal heads should make contact with the ground upon forefoot weight-bearing, distributing the weight equally among the six contact surfaces. In fact, however, the second, third, and possibly fourth metatarsals commonly bear slightly more weight than the others do. More concentrated weight-bearing on fewer contact surfaces results in earlier and more severe symptoms.


A metatarsal head takes its proper share of weight when its length and inclination are appropriate to the adjacent metatarsals. Fractured metatarsals may heal in an elevated position, less frequently in a depressed position, and commonly with dysfunctional shortening. Metatarsal heads that bear an increased share of weight gradually can develop a number of abnormalities, including painful plantar keratosis, metatarsophalangeal synovitis with swelling, metatarsal stress fracture, or synovitis and eventual arthrosis at the tarsometatarsal joint. These various manifestations can occur independently or in any combination in a given patient. Long-term metatarsophalangeal synovitis in a foot with a congenitally long and stable second metatarsal and a hypermobile first metatarsal can cause synovitic damage in the capsule and the intrinsic muscles, an extensor (intrinsic minus) clawing deformity, and eventually dislocation of the metatarsophalangeal joint with severe dorsal clawing. Rarely, the exuberant synovitis presents as a “tumor” between the metatarsal heads.


Each abnormality calls for specific treatment. Correction is most important in the first metatarsal, which is prone to excessive motion and tends to transfer weight to the second metatarsal. Fusion of the first tarsometatarsal joint and appropriate osteotomies may be needed to reconstruct anatomic length, inclination, and rotation before normal weight-bearing can be restored to the six weight-bearing points in the forefoot ( Fig. 68-9 ).




Figure 68-9


Stabilization of the first metatarsal and shortening osteotomy of the second metatarsal. A, The forefoot has a short first metatarsal and a long, obviously hypertrophied, overloaded second metatarsal. In general foot reconstruction, this is called a Morton foot, and it is usually associated with gastrocnemius equinus. Symptoms usually include pain around the second metatarsal head, with heavy callus formation or a painful plantar keratosis under the head. In later stages, symptomatic synovitis, eventual dislocation of the second metatarsophalangeal joint, and arthrosis can mimic a missed Lisfranc injury at the second tarsometatarsal joint. B, The disorder is treated by removing the cartilage from the first tarsometatarsal joint and stabilizing the first metatarsal in appropriate inclination with three 4.0-mm cortical screws. Cancellous grafting is usually necessary at two sites on the dorsal side of the joint. The overly long second metatarsal is managed by a diaphyseal shortening osteotomy with plating and grafting. Weight-bearing should become equalized across the metatarsal heads at the six weight-bearing points: the medial and lateral sesamoids and four lesser metatarsal heads.

(Source: Adapted from Hansen ST Jr: Functional reconstruction of the foot and ankle, Philadelphia, 2000, Lippincott Williams & Wilkins.)


Osteotomy in the lesser metatarsals generally is done at the site of malunion or nonunion and then plated and grafted. Intramedullary K-wire fixation does not provide precise enough positioning or stability for healing, and intrafragmental screws alone may not be strong enough to maintain position, although they can be used together with a neutralization plate ( Fig. 68-10 ). I generally use a burr to remove dorsal callus and reestablish the normal cortex across the osteotomy site. Next, I place cancellous autograft bone taken from the proximal tibia into the fusion site, particularly when an opening wedge is done. A one-quarter–tubular four- to six-hole plate on the dorsal side of the metatarsal provides fixation. In large patients with good soft tissue coverage, a stronger plate (such as a 2.7-mm dynamic compression plate [DCP]) may be preferable. For osteotomies located near the metatarsal neck or head, small T- or L-plates may be needed to get at least two screws into the distal fragment. Grafting and protected weight-bearing are required for up to 8 weeks.


Jun 11, 2019 | Posted by in ORTHOPEDIC | Comments Off on Posttraumatic Reconstruction of the Foot and Ankle
Premium Wordpress Themes by UFO Themes