Revisional Pes Cavus and Clubfoot Deformity Correction

Revisional Pes Cavus and Clubfoot Deformity Correction

Mikhail Samchukov, Alexander Cherkashin, Anthony I. Riccio, Jacob R. Zide, Daniel D. Bohl, Zachary Meyer


Pes cavus and clubfoot deformities occur across a wide disease spectrum and have a variable clinical presentation. Although surgery is often indicated, the individual nature of these deformities can result in unexpected outcomes and dissatisfied patients. Revision surgery can be extraordinarily complex depending on the severity of the deformity, size and shape of the foot, joint stiffness, soft tissue envelope, and underlying medical conditions.

Acute Deformity Correction

Results of isolated revision soft tissue releases have unsatisfactory complication rates.4,5 Adaptive changes in the articular surfaces of subluxated or dislocated tarsal bones can make tibiotalar and hindfoot reduction difficult, even after complete release of the joint capsule, resulting in insufficient deformity correction and early recurrence.6 Furthermore, skin necrosis often requiring grafts and/or flaps is common given the massive corrections in a region with little skin excursion.7,8 Hence, revision soft tissue release is an effective surgical modality only in the mildest recurrent deformities.

Common corrective osteotomies include distal tibial dorsiflexion osteotomy for persistent equinus,9,10 cuboid closing wedge and cuneiform opening wedge osteotomies (either in isolation or combination) for forefoot adduction,1115 and lateralizing calcaneal osteotomies to correct varus.1618 Although clinical and radiographic long-term improvements in forefoot position using these osteotomies can be achieved,19,20 correction of severe multiplanar deformities may require resection of large bony wedges resulting in significant foot shortening, especially in pediatric feet and feet that are already short preoperatively. In addition, corrective osteotomies performed for acute deformity correction can result in skin and wound healing issues and present risks for malunion and nonunion.

Isolated calcaneocuboid and talonavicular arthrodesis, as well as triple arthrodesis, should be considered a viable option for acute deformity correction as they can produce symptomatic improvement and high-level patient satisfaction in patients with severe and rigid pes cavus and recurrent clubfoot.2025 On the other hand, joint arthrodesis has also been shown to be complicated by residual deformities, wound infection, pseudoarthrosis, osteomyelitis, osteonecrosis, and nonunion.2628 Moreover, the majority of studies on triple arthrodesis in patients with clubfoot are limited to adults25 and, therefore, further research specific to the pediatric recurrent deformity population is needed to better understand how this more aggressive motion-sacrificing procedure compares with joint-sparing alternatives in the long term.

Gradual Deformity Correction

To overcome the challenges associated with acute correction while reducing or preventing associated complications, gradual repositioning of foot segments using circular external fixation was introduced as an alternative and an effective approach for revisional pes cavus and clubfoot surgery. Based on Ilizarov principles including new bone formation under the influence of tension stress (distraction osteogenesis), correlation between mechanical loading and blood supply, and soft tissue adaptation to gradual stretching (distraction histogenesis), this method allows for correction of severe and complex deformities of the foot and ankle via controlled, guided distraction across the rigid soft tissues, osteotomized bone segments, and contracted joints.2931

External Fixation Configurations

Ilizarov-type universal frame configuration for correction of pes cavus and clubfoot deformities (Figure 15.1A and B) consists of a proximal double-ring block, calcaneal half ring or 5/8 ring, and forefoot half ring or 5/8 ring secured to the tibia, calcaneus, and metatarsals, respectively, using cross tensioned oppositely directed olive-stopper wires and/or half pins.31,3339 For gradual correction of hindfoot equinus and midfoot varus, the distal tibial ring and calcaneal external support are interconnected with medial and lateral multiplanar joints and a posterior angular distractor. In general, correction of hindfoot equinus is achieved by gradually increasing the angular distractor length while varus deformity is corrected by differential distraction between medial and lateral tibiocalcaneal threaded rods. Talonavicular dislocation, which is often seen in clubfoot deformities, can also be reduced by tensioning of opposing olive wires placed from lateral to medial through the talar neck and from medial to lateral through the navicular.34,40

Figure 15.1 Ilizarov-type modular fixator; A, tibial double-ring block, calcaneal half ring, and forefoot 5/8 ring interconnected by multiplanar hinges and angular distractors; B, top view of the T-module assembly for gradual forefoot repositioning; C, photo illustrating clinical application of the Ilizarov modular fixator. Note 5 toe extension maintaining wires inserted across the interphalangeal and metatarsophalangeal joints.(C: Courtesy of Dr. Alexander Kirienko, Milan, Italy)

Gradual forefoot repositioning is accomplished using a unique T-module consisting of 2 inline anterior posts and a twisted plate assembly, pivotably connected to the distal tibial ring. The T-module is also connected to the forefoot half ring or 5/8 ring via 2 hinged threaded rods. Correction of cavus deformity is achieved by equal shortening of both tibial-forefoot rods while correction of residual supination is completed by differential compression between those 2 threaded rods.31,3537,41,42 Finally, forefoot adduction can be corrected by increasing the length of the anterior threaded rod interconnecting the distal tibial ring and twisted plate, often combined with gradual medial distraction using calcaneal-forefoot threaded rod.

Although Ilizarov-type circular fixators provide multiple advantages for complex deformity correction including multiplanar frame configuration, stable segmental bone fixation with preserved micromotion, and 3-dimensional consecutive or simultaneous adjustment, there are several limitations of these devices. The main disadvantages include the complexity of frame assembly and complicated manipulations with different modules to achieve the desired correction. Furthermore, frames can be unstable during these manipulations owing to deliberate toggle between the multiple frame components. These limitations led to the development and introduction of new advanced technology, namely, hexapod circular external fixation.

Similar to Ilizarov-type devices, hexapod circular fixators consist of tibial, hindfoot, and forefoot external supports secured to the tibia, calcaneus, and metatarsals, respectively, using cross-tensioned wires and/or half pins (Figure 15.2A and B). However, the frame relies on 6 interconnecting telescoping struts arranged in a specific configuration between those external supports creating a parallel kinematic system or Stewart-Gough platform.32,40 Hexapod frames require a computer-generated prescription to provide precise strut length adjustments for simultaneous bone segment repositioning in multiple planes. This makes them especially attractive for complex foot and ankle deformities requiring multiple levels of correction in a limited space.

Figure 15.2 Hexapod external fixation assemblies (TL-Hex, Orthofix, Verona, Italy): A, single-level horizontal (6H) fixator for acute hindfoot deformity correction and gradual correction of midfoot deformity; B, double-level orthogonal (6VX6H) fixator for consecutive or simultaneous gradual correction of hindfoot and midfoot deformities.

Despite the use of a single universal 6-strut correction module, multiple hexapod frame constructs can be assembled, some of which are quite complex. Standard descriptions of those different hexapod frame assemblies have been presented in our Modular Classification.32 These are based on the number of correction levels and orientation of the common vector of connecting struts (eg, single-level vertical or horizontal, double-level vertical inline or parallel, double-level orthogonal hexapod frames). Two of them are most commonly used for revisional pes cavus and clubfoot deformity correction, specifically the single-level horizontal (6H) fixator previously described by Charlie Taylor using carpentry terms as a butt frame (Figure 15.2A) and the double-level orthogonal (6VX6H) assembly also known as a miter frame (Figure 15.2B).


In general, our practice is to manage the majority of foot and ankle deformities, whether primary or revision cases, with acute correction and internal fixation. However, certain deformities and/or patient characteristics may make the use of gradual correction and external circular fixation preferable. These include:

This is not a decision to be taken lightly. Gradual deformity correction requires a great deal of presurgical education, psychological capacity to tolerate the external fixation device, and patient/parent compliance in strut adjustment.

Preoperative Considerations

Preoperative planning for revisional correction of pes cavus and clubfoot deformities must begin with a thorough assessment and documentation of the anomalies creating the resultant malposition of the hindfoot, midfoot, and forefoot. Moreover, such segmental deformities must be assessed not only individually with regard to their deviation from normal parameters but also relative to each other. This is particularly important in planning correction of complex deformities in which typical relationships between segments of the foot are not maintained or when unusual rotational differences are present between those segments.

Hindfoot Deformity Correction

Options for hindfoot deformity management in the sagittal plane include acute and gradual correction either through the tibiotalar joint or above the ankle through the distal tibia. Correction of hindfoot deformity in the coronal plane is usually achieved acutely either through the talocalcaneal articulation or below the subtalar joint through the calcaneus.

Figure 15.3 Severe equinocavovarus foot deformity in an 11-year-old female patient secondary to Charcot-Marie-Tooth disease: A and B, preoperative anterior-posterior and lateral radiographs illustrating equinocavovarus foot deformity with congruent ankle articular surfaces; C, preoperative lateral view photograph demonstrating equinocavus deformity and associated forefoot deformity with toe hyperextension; D and E, Coronal and sagittal plane deformity correction planning using Hex-Ray software module on the downloaded anterior-posterior and lateral x-rays; F, intraoperative photograph showing Z-plasty tendon Achilles lengthening and plantar fascia release followed by acute hindfoot deformity correction; G, intraoperative photograph demonstrating Gigli saw percutaneously inserted through 4 small stab incisions as a preparation for midfoot osteotomy; H, intraoperative anterior-posterior radiograph illustrating fluoroscopic guidance in exact placement of the Gigli saw; I, intraoperative lateral radiograph confirming temporary stabilization of calcaneus by extra-articular Kirschner wire in the desired orientation; J, intraoperative photograph illustrating precise leg positioning inside the T-shaped support block using 3 leg holders; K, intraoperative photograph showing T-shaped external support stabilization with calcaneal crossing wires and tibial half pins; L and M, intraoperative frontal and lateral view photographs demonstrating final 6H frame assembly after forefoot ring placement with attached metatarsal wires; N, immediate postoperative lateral radiograph showing position of foot segments after midfoot osteotomy before cavus correction; O and P, postoperative frontal view and lateral view photographs demonstrating completion of deformity correction. Note hexapod struts replacement with 4 static rapid adjust struts for better stability and bone regenerate visualization; Q, postoperative lateral radiograph confirming final position of foot segments after completion of cavus correction; R and S, clinical frontal and lateral view photographs at 1-year follow-up illustrating plantigrade position of the foot after deformity correction; T and U, anterior-posterior and lateral radiographs at 1-year follow-up.

Correction of equinus through soft tissue procedures, either acute or gradual, requires congruency of the tibiotalar articulation and that the joint be free of significant degenerative change. Joint incongruence and global degenerative disease should be considered contraindications unless this method is being used to correct deformity to allow for proper positioning of the ankle prior to a planned tibiotalar arthrodesis. In other situations, correction of equinus should be considered through the osteotomy of the distal tibia.

Acute osseous correction almost always mandates an open approach to the distal tibia and fibula to allow for proper positioning of the planned osteotomy (Figure 15.4A-C). Isolated sagittal plane deformity correction in those without a significant limb length difference is perhaps most easily accomplished by creating a sagittal dome osteotomy. Anterior closing wedge osteotomy is also useful especially in instances in which shortening of the operative extremity is desired for limb length equalization. If lengthening and sagittal plane deformity correction are needed, consideration should be given to a transverse osteotomy followed by gradual correction. For patients with isolated coronal plane deformity at the distal tibia and/or ankle, coronal dome, closing wedge, or opening wedge osteotomies with allograft placement may be used based on the need for concomitant management of a limb length difference.

Figure 15.4 Outlines of distal tibial osteotomies for equinus deformity correction: A, sagittal dome osteotomy for correction without tibial length alteration; B, anterior closing wedge for correction with some tibial shortening; C, transverse opening wedge osteotomy for gradual correction with tibial lengthening.

Determination of the ideal means of hindfoot deformity correction in the coronal plane (predominantly varus) is predicated foremost upon flexibility of the subtalar joint. In patients with supple subtalar motion, various soft tissue procedures should be considered to improve alignment prior to determining the need for bony correction. Patients with cavovarus deformities secondary to peripheral neuropathy usually have muscle imbalance, which must be addressed, not only to facilitate varus correction but also to prevent recurrence following surgical improvement of alignment. This is most often accomplished by performing a peroneus longus-to-brevis transfer to augment eversion forces across the hindfoot, a posterior tibial tendon lengthening or transfer to reduce inversion forces across the hindfoot, and, when indicated, a TAL to improve overall subtalar mobility. Patients in whom these procedures alone can correct hindfoot varus often have milder deformities that do not necessitate management in a ring fixator. However, the importance of these means of improving hindfoot varus, even in patients with severe deformity, cannot be understated provided that subtalar motion is present. Any improvement of alignment that can be achieved with soft tissue management will obviously decrease the amount of correction required via bony surgery whether it is done acutely or gradually.

Perhaps the easiest method of acutely altering hindfoot alignment in the coronal plane is through the use of a posterior calcaneal tuberosity (heel slide) osteotomy. In such cases, correction of hindfoot malalignment is achieved by establishing a more normal relationship between the tibia and posterior calcaneus. A calcaneal slide osteotomy is typically created in an oblique fashion in a dorsal-proximal to plantar-distal direction. The proximal fragment may then be mobilized to translate into a more lateral, medial, dorsal, or plantar position depending on the required deformity correction. If difficulty is encountered in obtaining complete coronal plane correction by translation alone, adding a closing wedge to the osteotomy can both decrease soft tissue tension to facilitate mobilization and allow further acute angular correction. This is particularly useful when addressing hindfoot varus, as the osteotomy for a heel slide is typically performed via a lateral approach, which facilitates addition of a lateral closing wedge osteotomy.

Biplanar correction may also be facilitated by altering the obliquity of the osteotomy to translate the posterior segment in both the sagittal and coronal planes. Orienting the osteotomy more vertically will allow for easier dorsal or plantar displacement in addition to any medial or lateral displacement necessary. This option is commonly reserved for cases in which degenerative changes of the tibiotalar joint, a poor soft tissue envelope, or severely abnormal distal tibial deformity or bone quality precludes a more proximal level of equinus deformity correction.

Following acute correction, fixation of the osteotomy may be accomplished using partially threaded cannulated screws or staples or by incorporation into the frame construct. If screws are used, care should be taken to place them in a trajectory that will not interfere with wires stabilizing the calcaneus to the external fixation assembly. The use of smaller 4.0-mm or 4.5-mm-diameter screws will also limit interference during incorporation of the calcaneus to the frame.

It is critical to consider the possibility of incomplete hindfoot deformity correction (predominantly equinus) when acute correction is attempted owing to a lack of soft tissue compliance. Therefore, the potential need for 2-staged correction for residual equinus is ever present and must always be considered during preoperative planning. Furthermore, even when the desired sagittal plane deformity correction is achieved, subsequent or simultaneous gradual correction of cavus may create increased tension across the hindfoot resulting in some loss of equinus correction following frame removal. In addition, in patients with both severe equinus and cavus deformities, failure to obtain full correction may result in ongoing forefoot overload and an inability to appropriately load the hindfoot during ambulation. In such circumstances, providing increased dorsiflexion in a staged fashion may be necessary.

Oct 22, 2022 | Posted by in ORTHOPEDIC | Comments Off on Revisional Pes Cavus and Clubfoot Deformity Correction
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