Operative Management of Tarsal Malunions: A Comprehensive Surgical Guide

Comprehensive Introduction and Patho-Epidemiology

Malunion of the lesser tarsal bones—encompassing the navicular, the cuboid, and the three cuneiforms—represents one of the most formidable reconstructive challenges encountered by the orthopaedic foot and ankle surgeon. Unlike isolated fractures of the talus or calcaneus, which often follow predictable fracture lines dictated by specific vectors of force, injuries to the midtarsal region are overwhelmingly the result of violent, high-energy, and chaotic trauma. Motor vehicle collisions, severe industrial crush injuries, and falls from extreme heights impart massive axial and sheer loads across the midfoot. Consequently, these injuries rarely occur in isolation. They are typically characterized by multiple contiguous bone fractures, severe osseous comminution, and concomitant subluxation or frank dislocation of one or more midtarsal (Chopart) or tarsometatarsal (Lisfranc) joints.

The epidemiology of midfoot trauma reveals a concerning propensity for delayed diagnosis and inadequate initial treatment, which directly fuels the incidence of subsequent malunions. Up to 20% to 30% of severe midfoot sprains and subtle fracture-dislocations are missed during the initial emergency department evaluation, particularly in polytraumatized patients where life-threatening injuries take precedence. Even when identified acutely, the sheer complexity of the comminution, coupled with severe soft tissue compromise, often precludes perfect anatomical reduction. As the initial fracture consolidates in a non-anatomic position, the resulting malunion drastically and permanently alters the biomechanics of the entire lower extremity. The patient, typically a young, working-age male, is left with a severely debilitating, rigid, and painful foot that precludes normal ambulation and significantly impacts their socio-economic status.

When these severe injuries heal in a non-anatomic position, the primary goal of reconstructive surgery fundamentally shifts from the acute restoration of perfect radiographic anatomy to the pragmatic creation of a functional limb. The overriding objective is the surgical engineering of a stable, pain-free, and plantigrade foot that can tolerate normal weight-bearing forces during the stance phase of gait. Surgeons must recognize that attempting to dissect out and perfectly realign every malunited fragment in a chronic setting is not only biologically detrimental to the tenuous blood supply but also biomechanically futile. Functional alignment supersedes perfect anatomical restoration. The operative focus must remain on eliminating painful plantar pressure points, restoring the longitudinal and transverse arches, and realigning the weight-bearing axis of the lower extremity.

Detailed Surgical Anatomy and Biomechanics

A profound understanding of the complex osteology, ligamentous restraints, and pathomechanics of the midfoot is an absolute prerequisite for successful preoperative planning and surgical execution. The midfoot functions as the keystone of both the longitudinal and transverse arches of the foot, bridging the dynamic hindfoot to the propulsive forefoot. The osseous architecture is inherently stable, with the trapezoidal shape of the cuneiforms and the interlocking articular facets providing a rigid Roman arch configuration. This bony stability is heavily augmented by a dense network of robust plantar ligaments, the spring ligament complex, and the bifurcate ligament, all of which must fail for significant displacement to occur during acute trauma.

Pathomechanics of Deformity Patterns

When violent trauma disrupts this intricate architecture, a highly predictable pattern of displacement and subsequent malunion occurs, dictated by the unyielding pull of the extrinsic musculature. In a typical midtarsal crush injury or fracture-dislocation, the distal osseous fragments, or the entire distal tarsal row, are forcefully driven and displaced dorsalward. This initial traumatic displacement is relentlessly exacerbated over time by the unopposed, tonic pull of the extrinsic toe extensors (extensor hallucis longus and extensor digitorum longus) and the tibialis anterior. Conversely, the proximal fragments are often driven plantarward by the initial traumatic vector and held there by the intrinsic plantar fascia and musculature.

This multiplanar, opposing displacement creates a classic and highly debilitating clinical presentation characterized by two distinct morphological abnormalities. First, the dorsally displaced distal fragments overlap the proximal bones, creating a hard, unyielding bony prominence on the dorsum of the foot. This dorsal bossing frequently leads to profound difficulty with standard shoe wear, chronic skin irritation, and eventual ulceration over the prominence. Second, the proximal fragments, driven inferiorly, form a rigid, bony mass on the sole of the foot. This completely disrupts the normal plantar contour, leading to focal pressure areas, intractable plantar keratoses, and severe, localized pain during the stance phase of gait, effectively creating a rigid rocker-bottom deformity.

Kinematic Consequences and the Coxa Pedis

The kinematic consequences of a tarsal malunion extend far beyond the localized deformity. The midtarsal joints, specifically the talonavicular and calcaneocuboid joints, function as a coupled unit often referred to as Chopart's joint, working in intimate concert with the subtalar joint (the coxa pedis) to allow inversion and eversion. This complex triplanar motion is essential for adapting the foot to uneven terrain and for absorbing shock during the initial heel strike. Malunion in the lesser tarsus invariably leads to a significant, if not complete, loss of these lateral and accommodative movements.

Even if the articular surfaces themselves are not directly involved in the fracture lines, the altered spatial relationship of the malunited tarsal bones restricts the normal, physiological excursion of the midfoot joints. During normal gait, the transverse tarsal joint unlocks during heel strike to allow the foot to become a supple shock absorber, and rigidly locks during push-off to provide a rigid lever arm. Tarsal malunion abolishes this critical locking and unlocking mechanism. The foot remains rigidly fixed, transferring immense, pathological sheer and bending forces to the adjacent, uninvolved joints. Over time, this mechanical overload leads to rapid, accelerated post-traumatic osteoarthritis in the ankle, subtalar, and tarsometatarsal joints, compounding the patient's disability.

Exhaustive Indications and Contraindications

The decision to proceed with the operative reconstruction of a tarsal malunion requires meticulous clinical judgment, balancing the severity of the patient's symptoms against the significant risks of complex midfoot surgery. A critical tenet in the management of these deformities is the timing of surgical intervention. Unless the deformity is exceptionally severe, directly threatening skin viability via pressure necrosis, or causing intolerable, intractable pain at rest, early operative intervention for a newly established malunion is generally contraindicated. The soft tissue envelope surrounding the midfoot is notoriously thin and unforgiving, and operating through traumatized, edematous tissue exponentially increases the risk of wound dehiscence and deep infection.

A mandatory trial of exhaustive conservative management for a minimum of 6 to 12 months is strongly recommended before considering surgical reconstruction. During this protracted period, the foot undergoes significant biological remodeling. The soft tissues adapt, post-traumatic edema subsides, and the patient may spontaneously accommodate to the altered biomechanics. Conservative modalities must be aggressively pursued, including the use of custom-molded total contact orthotics to offload plantar prominences, rigid-sole shoes with rocker-bottom modifications to bypass the rigid midfoot during gait, and potentially custom ankle-foot orthoses (AFOs) or Charcot Restraint Orthotic Walkers (CROW) for severe instability. Surgery is indicated only when this comprehensive conservative trial definitively fails to relieve painful plantar pressure, when dorsal bossing precludes all modified shoe wear, or when progressive deformity threatens adjacent joint integrity.

Pre-Operative Planning, Templating, and Patient Positioning

Thorough preoperative planning is the cornerstone of successful tarsal malunion reconstruction. Relying solely on standard radiographic evaluation is a common pitfall that invariably leads to intraoperative surprises and suboptimal outcomes. While standard weight-bearing radiographs (anteroposterior, lateral, and medial oblique views) are the necessary starting point to assess the gross deformity, evaluate Meary's angle, and measure the calcaneal pitch, plain films severely underestimate the three-dimensional complexity, rotational malalignment, and articular involvement of midfoot malunions. Overlapping osseous shadows in the midfoot make it impossible to accurately delineate the exact areas of bony coalition, cystic degeneration, or subchondral sclerosis.

Advanced Imaging and Digital Templating

A fine-cut Computed Tomography (CT) scan (0.5mm to 1.0mm slice thickness) in the axial, coronal, and sagittal planes, coupled with high-resolution 3D surface reconstructions, is absolutely mandatory for surgical planning. The CT scan allows the surgeon to meticulously assess the degree of articular cartilage damage in the midtarsal and subtalar joints, which dictates whether a joint-sparing osteotomy is feasible or if an extended arthrodesis is required. Furthermore, the CT scan quantifies the exact degree of dorsal or plantar translation, angular deformity, and column shortening. It is critical for evaluating the remaining bone stock, identifying avascular or cystic regions that will not support hardware, and calculating the exact dimensions of structural bone graft that will be required to restore column length.

Digital templating should be performed utilizing the CT multiplanar reformats. The surgeon must predetermine the apex of the deformity to plan the exact location and angle of the corrective osteotomy or wedge resection. If the medial or lateral column has collapsed, the contralateral normal foot should be radiographed and templated to determine the exact millimeter length of structural intercalary graft required. Advanced planning also involves selecting the appropriate fixation constructs, ensuring that plates and screws will have adequate purchase in dense, viable bone rather than osteopenic or cystic voids.

Patient Positioning and Operating Room Setup

The patient is typically positioned supine on a radiolucent, flat Jackson table. A bump is placed under the ipsilateral hip to internally rotate the lower extremity until the patella points directly towards the ceiling, bringing the foot into a neutral position and preventing the natural tendency for external rotation. A well-padded thigh tourniquet is applied, though some surgeons prefer a calf tourniquet to allow access to the proximal tibia if autologous bone graft harvesting is anticipated. The entire lower extremity, extending above the knee, is prepped and draped to allow for assessment of overall limb alignment during the procedure.

Fluoroscopy is an indispensable tool and must be positioned optimally. The C-arm should be brought in from the contralateral side of the table, perpendicular to the operative field, allowing for unimpeded anteroposterior, lateral, and oblique imaging without compromising the sterile field. The surgeon must ensure that true lateral views of the midfoot can be easily obtained, as visualizing the restoration of the longitudinal arch and ensuring that plantar hardware does not penetrate the plantar cortex are critical intraoperative steps.

Step-by-Step Surgical Approach and Fixation Technique

Accessing the lesser tarsal bones requires meticulous, atraumatic handling of the notoriously thin dorsal soft tissue envelope. The choice of surgical approach is dictated by the specific columns involved in the malunion. Often, a dual-incision technique is required to access both the medial and lateral columns simultaneously, allowing for global mobilization of the midfoot.

Surgical Approaches: Dorsomedial and Dorsolateral

The Dorsomedial Approach is utilized for addressing deformities of the navicular, medial cuneiform, and the entire medial column. A longitudinal incision is meticulously planned, centered over the talonavicular joint and extending distally to the first tarsometatarsal joint. The incision is placed just lateral to the prominent tibialis anterior tendon to avoid direct pressure on the scar postoperatively. Deep dissection requires identifying and gently retracting the extensor hallucis longus (EHL) laterally, along with the critical dorsalis pedis artery and deep peroneal nerve bundle. The tibialis anterior is retracted medially. Subperiosteal dissection is then performed to expose the dorsal aspect of the navicular and cuneiforms. Extreme care must be taken to preserve the plantar soft tissue attachments, as the plantar arterial network provides the primary blood supply to the navicular; aggressive circumferential stripping will inevitably lead to avascular necrosis and subsequent nonunion.

The Dorsolateral Approach is utilized for addressing the cuboid and the lateral column. A longitudinal incision is made over the dorsolateral aspect of the foot, directly centered over the calcaneocuboid joint. In the subcutaneous tissue, the sural nerve and the lesser saphenous vein must be meticulously identified, mobilized, and protected. The extensor digitorum brevis (EDB) muscle belly is identified, elevated from its proximal origin on the lateral calcaneus, and reflected distally. This provides excellent, wide exposure of the calcaneocuboid joint, the entire dorsal surface of the cuboid, and the bases of the 4th and 5th metatarsals.

Operative Strategy: Arthrodesis (The Gold Standard)

While joint-sparing corrective osteotomies through the old fracture lines are theoretically possible for strictly extra-articular malunions in highly selected, young patients, they are rarely applicable. In the vast majority of severe crush injuries, lateral movements are already permanently lost due to capsular scarring, and traumatic arthritis is either present or inevitable. Therefore, partial or total resection of the deformity and rigid midtarsal arthrodesis remains the gold standard of treatment. Arthrodesis that entirely eliminates lateral midfoot motion does not significantly add to the patient's existing disability, provided the foot is rendered solidly plantigrade, pain-free, and biomechanically aligned.

Step 1: Joint Preparation and Deformity Resection
The involved joints and the malunion mass are widely exposed. Using a combination of oscillating saws, sharp osteotomes, rongeurs, and curettes, the remaining articular cartilage, fibrous nonunion tissue, and sclerotic subchondral bone are aggressively resected down to healthy, bleeding, punctate cancellous bone (the "paprika sign"). To correct the classic dorsal prominence and plantar mass, a biplanar wedge resection is frequently necessary. A dorsally based wedge of bone is carefully excised from the apex of the deformity. This allows the plantarflexed proximal fragments to be elevated and the dorsiflexed distal fragments to be plantarflexed, effectively closing the wedge and bringing the foot up into a neutral, plantigrade position, thereby recreating the longitudinal arch.

Step 2: Preservation of the Subtalar Joint
A paramount biomechanical principle must be strictly observed during this reconstruction: When the subtalar joint is not involved in the post-traumatic arthrosis, its motion must be preserved at all costs. The surgeon should limit the fusion strictly to the midtarsal joints (Chopart and distal). Fusing an uninvolved subtalar joint unnecessarily stiffens the hindfoot, obliterates whatever accommodative motion remains, and drastically increases the risk of rapidly progressive, adjacent segment disease at the ankle joint.

Step 3: Structural Restoration and Biological Augmentation
Violent midfoot trauma often results in significant bone loss, and the wedge resection required for deformity correction further shortens the foot. Restoring the anatomical length of the medial or lateral column is vital to prevent secondary, acquired deformities (such as an acquired flatfoot or a severe cavovarus deformity). If a void is created after correcting the overlap and restoring the column length, a structural, tricortical iliac crest bone graft (ICBG) or a robust structural allograft must be precisely fashioned and intercalated into the defect. Furthermore, because of the tenuous blood supply, copious cancellous autograft (harvested from the proximal tibia or the calcaneal tuberosity) should be aggressively packed into all interstices, gaps, and around the structural graft to maximize the osteogenic potential and promote solid union.

Step 4: Rigid Internal Fixation Constructs
Rigid, absolute stability is paramount to maintain the corrected alignment, resist the massive deforming forces of the extrinsic musculature, and achieve solid arthrodesis. For the medial column, stabilization is typically achieved using robust, low-profile dorsal bridging locking plates. Alternatively, large fragment (4.5mm or 6.5mm) partially threaded cannulated screws can be utilized as "home run" or beaming screws, driven from the medial cuneiform, through the navicular, and directly into the talar body. For the lateral column, the calcaneocuboid joint is best stabilized with a dedicated, anatomically contoured locking plate. If length has been restored with a structural intercalary graft, a bridging plate provides vastly superior biomechanical stability compared to isolated interfragmentary screw fixation. Whenever anatomically possible, eccentric drilling techniques or external compression devices should be utilized to dynamically compress the arthrodesis sites prior to final locked plate fixation.

Complications, Incidence Rates, and Salvage Management

The operative reconstruction of tarsal malunions is fraught with potential complications. The combination of a compromised soft tissue envelope, tenuous regional vascularity, and immense biomechanical forces creates a highly challenging environment for healing. Surgeons must be acutely aware of these risks, employ meticulous preventive strategies, and possess the technical armamentarium to manage failures when they occur. Thorough preoperative patient counseling regarding these high complication rates is an absolute medicolegal and ethical necessity.

The most dreaded complication is nonunion, particularly at the talonavicular joint, which has a notoriously high failure rate due to the watershed vascular supply of the navicular bone. Hardware prominence is also exceedingly common; once the chronic postoperative edema finally subsides, the rigid dorsal plates often become palpable beneath the thin skin, leading to tendon irritation and painful shoe wear. Furthermore, the biomechanical consequence of a successful midfoot fusion is the altered transfer of stress, which inevitably leads to adjacent segment disease over time.

Phased Post-Operative Rehabilitation Protocols

The ultimate success of a complex midtarsal reconstruction relies just as heavily on strict, unwavering adherence to postoperative rehabilitation protocols as it does on flawless surgical execution. The reconstructed midfoot, reliant entirely on hardware and consolidating bone graft, is highly susceptible to catastrophic failure, hardware pullout, and nonunion if subjected to axial loading or shear forces prematurely. The rehabilitation process is protracted, demanding immense patience and compliance from the patient.

Phase 1: Maximum Protection and Biological Healing (Weeks 0-6)

The immediate postoperative phase prioritizes wound healing, edema control, and absolute protection of the fragile fixation. In the operating room, the patient is placed in a bulky, well-padded, short-leg splint with the ankle in neutral dorsiflexion. Strict, absolute non-weight-bearing (NWB) status is enforced, utilizing crutches, a walker, or a knee scooter. The patient is instructed to keep the limb strictly elevated above the level of the heart for the first 14 days to mitigate swelling and protect the dorsal incisions. Chemical deep vein thrombosis (DVT) prophylaxis is highly recommended during this period of immobility. At approximately 2 to 3 weeks, the patient returns to the clinic for splint removal, wound inspection, and suture removal. If the wounds are impeccably healed, the patient is transitioned to a rigid, total-contact fiberglass cast or a locked, rigid CAM (Controlled Ankle Motion) boot, remaining strictly NWB for the remainder of the 6-week period.

Phase 2: Progressive Loading and Early Mobilization (Weeks 6-12)

At the 6-week postoperative mark, the patient undergoes comprehensive clinical and radiographic evaluation. Anteroposterior, lateral, and oblique radiographs are obtained out of the cast to assess for hardware integrity and the presence of early bridging callus or obscuration of the arthrodesis lines. If there is radiographic evidence of early consolidation, no hardware shifting, and no clinical pain upon gentle palpation of the midfoot, the patient may begin a meticulously supervised protocol of progressive partial weight-bearing (PWB) in the CAM boot. Weight-bearing is typically advanced by 25% of body weight per week. Concurrently, formal physical therapy is initiated. The focus during this phase is on active and active-assisted range of motion of the ankle, subtalar (if unfused), and metatarsophalangeal joints to combat capsular contractures. Isometric strengthening of the extrinsic foot musculature and intrinsic foot intrinsic muscles is commenced.

Phase 3: Maturation, Remodeling, and Orthotic Support (Weeks 12+)

At 12 weeks, definitive radiographic union must be confirmed. Because plain radiographs are notoriously unreliable for confirming solid midfoot arthrodesis, a follow-up fine-cut CT scan is highly recommended before allowing full, unprotected weight-bearing. Once solid osseous union is unequivocally confirmed, the patient is gradually transitioned out of the CAM boot and into regular, supportive footwear. However, the newly fused midfoot remains vulnerable to immense bending moments during the propulsive phase of gait. Therefore, a custom-molded, rigid-sole orthotic with a well-contoured medial arch support, or a shoe with a carbon-fiber footplate and a rocker-bottom sole, is absolutely critical for the first 12 to 18 months postoperatively. This orthotic management protects the arthrodesis mass from excessive cyclical loading, allows the bone graft to fully remodel according to Wolff's Law, and significantly mitigates the stress transferred to the adjacent, unfused joints.

Summary of Landmark Literature and Clinical Guidelines

The evolution of operative strategies for tarsal malunions is deeply rooted in several landmark biomechanical and clinical studies that have shaped modern orthopaedic foot and ankle surgery. Historically, conservative management was championed even for severe deformities due to the high complication rates of early surgical interventions. However, the paradigm shifted dramatically with the foundational work of Sangeorzan et al., who meticulously detailed the devastating kinematic consequences of midfoot malalignment, specifically demonstrating how minor degrees of dorsal displacement in the lesser tarsus exponentially increase contact pressures in the adjacent subtalar and ankle joints. Their work established the absolute necessity of restoring the longitudinal arch and rendering the foot plantigrade to prevent widespread hindfoot arthrosis.

Myerson's extensive clinical series on the management of chronic Lisfranc and Chopart fracture-dislocations further solidified the modern treatment algorithm. His research definitively demonstrated that delayed, joint-sparing intra-articular osteotomies for chronic midfoot malunions yielded universally poor functional outcomes due to pre-existing, irreversible cartilage necrosis and capsular scarring. Myerson’s guidelines established rigid, extended midtarsal arthrodesis as the definitive gold standard for these chronic, complex deformities, emphasizing that sacrificing painful, microscopic midfoot motion in favor of a stable, painless, plantigrade platform leads to vastly superior patient-reported outcome measures (PROMs).

Current clinical guidelines endorsed by the American Orthopaedic Foot & Ankle Society (AOFAS) and the Orthopaedic Trauma Association (OTA) heavily emphasize the critical role of advanced 3D imaging in preoperative planning. Consensus statements highlight that the routine use of fine-cut CT scanning is no longer optional but a mandatory standard of care for evaluating midfoot trauma and malunions. Furthermore, contemporary literature strongly advocates for the use of robust, multi-planar rigid internal fixation—specifically utilizing anatomically contoured locking plates combined with structural autograft or allograft—to bridge defects and maintain column length, significantly reducing the historical nonunion rates associated with isolated screw fixation. The overarching consensus remains clear: while the operative management of tarsal malunions is a formidable undertaking, precise surgical execution aimed at biomechanical restoration provides a profound, life-altering improvement in the patient's functional capacity.