Operative Management of Midfoot Cavus: The Japas V-Osteotomy and Tarsal Reconstructions

Comprehensive Introduction and Patho-Epidemiology

Cavus foot deformities present an exceptionally complex, multiplanar reconstructive challenge for the orthopedic surgeon, demanding a profound understanding of lower extremity biomechanics and neuromuscular pathology. Characterized fundamentally by an abnormally high longitudinal arch, the deformity is rarely isolated to a single anatomical plane. Instead, it manifests as a triplanar structural abnormality involving forefoot equinus, midfoot cavus, and hindfoot varus. The midfoot cavus specifically localizes the apex of the deformity to the midtarsal joints (talonavicular and calcaneocuboid articulations) or the naviculocuneiform joints. While the midtarsal joint is the most common site of apex angulation, the rigidity of the deformity and the underlying etiology dictate the surgical algorithm.

The patho-epidemiology of midfoot cavus is inextricably linked to neuromuscular disorders, which account for approximately 60% to 80% of all bilateral cavovarus foot deformities. Charcot-Marie-Tooth (CMT) disease, particularly Type 1A (associated with the PMP22 gene duplication), is the most prevalent etiology. Other critical neurological drivers include spinal dysraphism (such as tethered cord syndrome or myelomeningocele), poliomyelitis, cerebral palsy, Friedreich’s ataxia, and intraspinal tumors. Unilateral cavus deformities should raise immediate clinical suspicion for localized pathology, such as post-traumatic malunion, compartment syndrome (Volkmann's ischemic contracture of the foot), or unilateral tethered cord manifestations. Idiopathic cavus feet do exist, but a diagnosis of exclusion must only be made after an exhaustive neurological workup, including electromyography (EMG) and magnetic resonance imaging (MRI) of the neuraxis.

Historically, the operative management of fixed midfoot cavus relied heavily on anterior tarsal wedge osteotomies, most notably the Cole osteotomy described in 1940. The Cole procedure involves the resection of a dorsal biplanar wedge from the navicular and cuboid, effectively closing the dorsal gap to flatten the arch. However, these traditional techniques possess a significant biomechanical and cosmetic disadvantage: the deformity is corrected by resecting a dorsal wedge, which shortens the convex dorsal surface of the foot rather than lengthening the concave plantar surface. Consequently, the resulting foot is often shortened, widened, thickened, and functionally compromised—a cosmetically unappealing and biomechanically altered outcome that patients frequently find unsatisfactory.

To circumvent the inherent limitations of dorsal wedge resections, advanced osteotomy techniques were developed, most prominently the Japas V-osteotomy introduced in 1968. The Japas technique represents a paradigm shift in the management of midfoot cavus by utilizing a zero-resection, V-shaped cut through the tarsus that corrects the deformity by lengthening the plantar aspect of the foot. When combined with appropriate soft tissue releases and, if necessary, distal tarsometatarsal resections (such as the Jahss procedure), the orthopedic surgeon can reliably restore a plantigrade, stable, and cosmetically acceptable foot. This chapter provides an exhaustive, master-level exploration of the indications, biomechanical principles, surgical techniques, and postoperative protocols for midfoot osteotomies.

Detailed Surgical Anatomy and Biomechanics

The successful execution of midfoot osteotomies requires a masterful command of the intricate surgical anatomy and the complex biomechanical forces that drive the cavus deformity. The midfoot is anatomically defined as the osseous structures between Chopart’s joint (the talonavicular and calcaneocuboid articulations) proximally, and the Lisfranc joint complex (the tarsometatarsal articulations) distally. It comprises the navicular, the cuboid, and the three cuneiforms (medial, intermediate, and lateral). The structural integrity of the midfoot is maintained by a dense network of dorsal, plantar, and interosseous ligaments, with the plantar fascia acting as the primary static restraint to arch collapse via the windlass mechanism.

The biomechanical genesis of the cavovarus foot is classically described as a dynamic muscle imbalance that progressively transitions into a rigid structural deformity. In conditions like Charcot-Marie-Tooth disease, there is a predictable pattern of muscle denervation and weakness. The intrinsic muscles of the foot (lumbricals and interossei) are typically the first to atrophy, leading to a loss of flexion at the metatarsophalangeal (MTP) joints and a loss of extension at the interphalangeal (IP) joints, culminating in rigid claw toes. This clawing depresses the metatarsal heads, exacerbating the forefoot equinus.

More proximally, a profound imbalance occurs between the extrinsic invertors and evertors, as well as the dorsiflexors and plantarflexors. The peroneus brevis and tibialis anterior muscles become profoundly weak, while the peroneus longus and tibialis posterior muscles retain their strength. The unopposed pull of the robust peroneus longus—which inserts on the plantar-lateral aspect of the medial cuneiform and the base of the first metatarsal—drives the first ray into severe, rigid plantarflexion. This plantarflexed medial column acts as a rigid "kickstand" during the stance phase of gait. As the patient bears weight, the ground reaction forces push against the plantarflexed first metatarsal, forcing the entire hindfoot into a secondary, compensatory varus position to allow the lateral border of the foot to contact the ground.

Over time, this dynamically driven deformity causes secondary soft tissue contractures. The plantar fascia, the short plantar ligaments, and the spring ligament complex become rigidly contracted, converting a flexible, dynamically correctable deformity into a fixed osseous abnormality. Once the midtarsal or naviculocuneiform joints become rigidly deformed, soft tissue releases alone are insufficient, necessitating osseous correction via tarsal osteotomy. Understanding the "kickstand" phenomenon is paramount; if the midfoot deformity is the primary driver of the hindfoot varus, correcting the midfoot cavus via a Japas osteotomy or first metatarsal dorsiflexion osteotomy will spontaneously correct the hindfoot alignment, provided the subtalar joint remains flexible.

The surgical anatomy of the dorsal midfoot approach is fraught with critical neurovascular structures that must be meticulously protected. The dorsalis pedis artery, a continuation of the anterior tibial artery, courses longitudinally over the dorsal aspect of the navicular and intermediate cuneiform, typically running between the extensor hallucis longus (EHL) and the extensor digitorum longus (EDL) tendons. Accompanying the artery is the deep peroneal nerve, which provides motor innervation to the extensor digitorum brevis and sensory innervation to the first web space. The superficial peroneal nerve branches (medial and intermediate dorsal cutaneous nerves) course within the subcutaneous tissues and are highly susceptible to iatrogenic injury during the initial surgical exposure, which can result in debilitating postoperative neuromas.

Exhaustive Indications and Contraindications

The selection of the appropriate midfoot osteotomy is entirely dependent on the apex of the deformity, the rigidity of the joints, the patient's age, and the underlying etiology. A nuanced understanding of the indications and contraindications for the Japas V-osteotomy, the Cole anterior tarsal wedge osteotomy, and the Jahss tarsometatarsal resection is critical for optimizing patient outcomes and avoiding catastrophic surgical failures.

The Japas V-osteotomy is uniquely designed to produce a more normal-appearing, functional foot by lengthening the plantar surface rather than shortening the dorsal surface. It is primarily indicated for moderate, fixed midfoot cavus deformities where the apex of the deformity lies within the navicular or the naviculocuneiform joints. It is particularly advantageous in pediatric and adolescent patients (typically aged 6 years and older) where preservation of foot length is a primary concern. Because the Japas procedure does not resect bone, it avoids the "dumpy," shortened foot characteristic of the Cole procedure.

Conversely, the Cole anterior tarsal wedge osteotomy is reserved for severe, rigid midfoot cavus deformities where the apex is located at the midtarsal joint, and the deformity is too severe to be corrected by a zero-resection technique. The Jahss truncated wedge resection is indicated when the apex of the cavus deformity is located more distally, specifically at the tarsometatarsal (Lisfranc) joints, presenting as a fixed forefoot equinus.

Contraindications for midfoot osteotomies include isolated hindfoot deformities (which require calcaneal osteotomies or triple arthrodesis), isolated forefoot deformities (which require metatarsal osteotomies), and severe degenerative joint disease of the midfoot (which necessitates arthrodesis rather than joint-sparing osteotomy). Furthermore, any midfoot osteotomy is contraindicated in the presence of active infection, severe peripheral vascular disease, or profound sensory neuropathy with active Charcot neuroarthropathy.

Pre-Operative Planning, Templating, and Patient Positioning

Thorough preoperative evaluation and meticulous surgical templating are the cornerstones of successful midfoot cavus reconstruction. The clinical assessment must begin with a comprehensive gait analysis to evaluate the dynamic components of the deformity, focusing on the foot progression angle, the presence of a foot drop, and the stance phase biomechanics. A detailed neurological examination is mandatory, assessing motor strength (specifically evaluating the peroneus longus, peroneus brevis, tibialis anterior, and tibialis posterior), deep tendon reflexes, and sensory mapping.

The cornerstone of the clinical examination is the Coleman block test, which differentiates between a forefoot-driven and a hindfoot-driven varus deformity. The patient is asked to stand with the heel and the lateral border of the foot on a 1-inch wooden block, allowing the plantarflexed first ray to drop off the medial edge of the block into free space. If the hindfoot varus corrects to neutral or valgus when the first ray is unconstrained, the hindfoot deformity is deemed flexible and is entirely driven by the forefoot/midfoot. In such cases, correcting the midfoot cavus (e.g., via a Japas osteotomy) will spontaneously correct the hindfoot varus, negating the need for a primary calcaneal osteotomy. If the hindfoot varus remains rigid and uncorrected on the block, a concomitant hindfoot procedure (such as a Dwyer calcaneal osteotomy or a lateralizing calcaneal slide) must be incorporated into the surgical plan. Additionally, the Silfverskiöld test must be performed to assess for concomitant gastrocnemius equinus, which may necessitate a simultaneous gastrocnemius recession or Achilles tendon lengthening.

Radiographic evaluation requires high-quality, weight-bearing anteroposterior (AP), lateral, and Harris heel views of the foot and ankle. Preoperative templating is absolutely critical to determine the exact apex of the deformity.
* Meary’s Angle (Talus-First Metatarsal Angle): On the lateral weight-bearing radiograph, a line is drawn through the longitudinal axis of the talus and the longitudinal axis of the first metatarsal. In a normal foot, these lines are collinear (0 degrees). In a midfoot cavus deformity, the angle intersects at the midtarsal or naviculocuneiform joint, with the first metatarsal plantarflexed relative to the talus. The intersection point dictates the apex of the V-cut in the Japas procedure.
* Hibbs Angle (Calcaneus-First Metatarsal Angle): Formed by the intersection of the longitudinal axis of the calcaneus and the longitudinal axis of the first metatarsal. Normally approaching 150 degrees, this angle acutely decreases (often approaching 90 degrees) in severe cavus deformities.
* Calcaneal Pitch: The angle between the inferior border of the calcaneus and the plantar supporting surface. An angle greater than 30 degrees indicates a true calcaneocavus deformity, which may require distinct management strategies.

Patient positioning is standardized for midfoot osteotomies. The patient is placed supine on the operating table. A bump is placed under the ipsilateral hip to internally rotate the leg to a neutral, vertically oriented position, counteracting the natural external rotation of the lower extremity. A well-padded pneumatic thigh tourniquet is applied. Prophylactic intravenous antibiotics (typically a first-generation cephalosporin) are administered prior to exsanguination and tourniquet inflation. The entire lower extremity is prepped and draped in a standard sterile fashion. The fluoroscopy unit (C-arm) must be positioned to easily enter the sterile field from the contralateral side, allowing for unhindered intraoperative AP, lateral, and oblique views of the midfoot.

Step-by-Step Surgical Approach and Fixation Technique

The surgical execution of the Japas V-osteotomy demands precision, meticulous soft tissue handling, and a thorough understanding of the three-dimensional geometry of the midfoot. The procedure is almost universally preceded by a plantar fascial release to permit the necessary lengthening of the plantar surface.

1. Soft Tissue Release: The Steindler Stripping

Before addressing the osseous deformity, the rigid plantar soft tissue constraints must be released. A 3- to 4-centimeter longitudinal incision is made along the medial aspect of the calcaneal tuberosity. Dissection is carried down to the plantar fascia. The superficial and deep layers of the plantar fascia are identified and sharply transected near their origin on the medial calcaneal tubercle. Using a periosteal elevator or a Cobb elevator, the origins of the short plantar musculature—specifically the abductor hallucis, flexor digitorum brevis, and abductor digiti minimi—are subperiosteally stripped from the calcaneus and allowed to slide distally. This critical step releases the "bowstring" effect of the plantar structures, enabling the subsequent osseous correction to lengthen the foot without excessive tension.

2. Surgical Approach to the Midfoot

A dorsal longitudinal incision, approximately 6 to 8 centimeters in length, is made centered over the apex of the cavus deformity, which is most commonly located at the navicular.
* Carefully incise the skin and superficial fascia. Meticulous hemostasis is achieved using bipolar electrocautery to protect the delicate subcutaneous tissues.
* Identify and carefully retract the superficial peroneal nerve branches to avoid neuroma formation.
* Deep dissection exposes the extensor retinaculum. The extensor hallucis longus (EHL) tendon is retracted medially, while the extensor digitorum longus (EDL) tendons are retracted laterally.
* The neurovascular bundle, consisting of the dorsalis pedis artery and the deep peroneal nerve, is identified coursing over the intermediate cuneiform. These structures must be meticulously mobilized, protected with a vessel loop, and gently retracted either medially or laterally depending on the specific location of the osteotomy cuts.
* The periosteum over the navicular, cuneiforms, and cuboid is incised longitudinally and reflected medially and laterally using a key elevator to expose the osseous anatomy.

3. The Japas V-Osteotomy Cut

The exact location of the osteotomy is confirmed using intraoperative fluoroscopy, ensuring the apex of the "V" aligns perfectly with the apex of Meary's angle (typically within the body of the navicular).
* The Apex: A drill hole or a small K-wire is placed at the planned apex in the proximal aspect of the navicular to serve as a visual guide.
* The Medial Limb: Using a fine-toothed oscillating saw under continuous, copious cold saline irrigation (to prevent thermal necrosis of the bone), the medial limb of the V is cut. The saw blade starts at the apex and is directed distally and medially, passing through the medial (first) cuneiform to exit at the medial border of the foot.
* The Lateral Limb: The saw blade is repositioned at the apex and directed distally and laterally, passing through the lateral cuneiform and the cuboid to exit at the lateral border of the foot.
* Critical Technique: The cuts must be made strictly perpendicular to the plantar aspect of the foot. Angulating the saw blade dorsally or plantarly will inadvertently induce a varus or valgus malalignment when the osteotomy is shifted. The osteotomy is a zero-resection cut; no wedge of bone is removed.

4. Deformity Correction and Plantar Lengthening

Once the V-osteotomy is complete, osteotomes are gently inserted into the limbs of the cut to ensure the distal fragment is completely mobile and free of any plantar cortical hinges.
* The surgeon applies firm dorsal pressure to the metatarsal heads, elevating the forefoot out of equinus.
* Simultaneously, downward (plantarward) pressure is applied to the proximal border of the distal osteotomy fragment.
* This synchronized maneuver depresses the apex of the deformity, flattens the longitudinal arch, and effectively lengthens the plantar surface of the foot. The proximal fragment (the talus and proximal navicular) remains stationary while the distal fragment shifts plantarly and rotates dorsally.

5. Fixation Strategy

Once the desired clinical correction is achieved, the position is temporarily held with reduction forceps or manual pressure. Intraoperative lateral fluoroscopy is utilized to confirm that Meary's angle has been restored to 0 degrees and that the midfoot is plantigrade.
* Rigid internal fixation is achieved using multiple heavy Kirschner wires (typically 2.0 mm or 2.4 mm) or stout Steinmann pins.
* The pins are driven from the dorsal aspect of the midfoot, starting in the cuneiforms or metatarsal bases, crossing the osteotomy site, and anchoring solidly into the proximal tarsal bones (the talus and the calcaneus).
* Typically, two to three crossed pins are required to provide adequate rotational and multiplanar stability. The pins are often left protruding through the skin, bent, and capped for easy removal in the clinic setting, although buried headless compression screws or low-profile midfoot locking plates can be utilized in older adolescents or adults.
* The wound is irrigated and closed in layers. A bulky Jones compression dressing and a well-padded short-leg splint are applied with the foot held in neutral dorsiflexion.

Complications, Incidence Rates, and Salvage Management

Despite meticulous surgical technique and comprehensive preoperative planning, midfoot osteotomies for cavus deformities carry a significant risk of complications. The multiplanar nature of the deformity and the inherently compromised soft tissue envelope in neuromuscular patients contribute to a challenging postoperative course. Surgeons must be adept at recognizing and managing these complications to prevent long-term disability.

The most frequent complication is undercorrection or recurrence of the deformity. This is almost exclusively the result of an inadequate initial soft tissue release (failure to perform a complete Steindler stripping) or the failure to recognize and address a concomitant, rigid hindfoot varus deformity. If the midfoot is corrected but the hindfoot remains in varus, the abnormal biomechanical forces will rapidly drive the midfoot back into a cavus position.

Conversely, overcorrection is a devastating complication that transforms a cavus foot into an iatrogenic rocker-bottom deformity (pes planovalgus). This typically occurs due to excessive dorsal wedge resection in a Cole osteotomy or over-depression of the distal fragment during a Japas procedure. A rocker-bottom foot drastically alters gait biomechanics, leading to severe midfoot pain, intractable plantar ulcerations, and profound disability.

Nonunion and delayed union are also significant risks, particularly given the reliance on osteotomies through cortical bone in the midfoot. Thermal necrosis from the oscillating saw, excessive periosteal stripping, or inadequate internal fixation are the primary culprits. Furthermore, the dorsal surgical approach places the deep peroneal nerve and the dorsalis pedis artery at high risk of iatrogenic transection or traction injury.

Phased Post-Operative Rehabilitation Protocols

The ultimate functional outcome of a midfoot osteotomy relies as heavily on strict adherence to a phased postoperative rehabilitation protocol as it does on the surgical execution itself. The reconstructed midfoot is highly vulnerable to displacement and hardware failure during the early phases of bone healing.

Phase 1: Immediate Postoperative Period (Weeks 0-6)

Immediately following surgery, the patient is placed in a bulky Jones dressing reinforced with a posterior short-leg splint, maintaining the ankle in neutral dorsiflexion (0 degrees).
* Weight-Bearing Status: The patient is strictly non-weight-bearing (NWB) on the operative extremity. The use of crutches, a walker, or a knee scooter is mandatory.
* Edema Control: Strict elevation of the operative limb above the level of the heart is critical for the first 7 to 14 days to manage postoperative edema, promote wound healing, and mitigate the risk of compartment syndrome.
* Follow-up: At 2 weeks postoperatively, the initial splint and sutures are removed. The wound is inspected, and the patient is transitioned into a well-padded, rigid short-leg fiberglass cast. The NWB status is strictly maintained.

Phase 2: Intermediate Healing Phase (Weeks 6-10)

At the 6-week postoperative mark, the patient returns to the clinic for cast removal and radiographic evaluation. AP, lateral, and oblique radiographs are obtained out of the cast to assess the progression of osseous consolidation at the osteotomy sites.
* Hardware Management: If percutaneous Steinmann pins or K-wires were utilized and left protruding through the skin, they are typically removed in the clinic at this time, provided there is radiographic evidence of early callus formation and clinical stability.
* Immobilization: The patient is transitioned from a fiberglass cast to a rigid controlled ankle motion (CAM) boot.
* Weight-Bearing Status: Progressive, partial weight-bearing is initiated. The patient is instructed to begin with 25% of their body weight, utilizing crutches, and gradually advance to full weight-bearing in the CAM boot over the next 4 weeks, guided by pain and radiographic healing.

Phase 3: Rehabilitation and Functional Restoration (Weeks 10+)

Once absolute clinical and radiographic union is achieved (typically between 10 and 12 weeks), the CAM boot is discontinued.
* Footwear and Orthotics: The patient transitions to supportive, athletic footwear. Because the architectural dynamics of the foot have been fundamentally altered, custom-molded orthotics are frequently prescribed to support the newly reconstructed longitudinal arch and accommodate any residual fixed deformities.
* Physical Therapy: A rigorous physical therapy program is initiated. The primary goals include restoring active and passive range of motion to the ankle and subtalar joints, which often become stiff during the prolonged period of immobilization.
* Strengthening: Targeted strengthening of the peroneus brevis and tibialis anterior is crucial to prevent the recurrence of the dynamic muscle imbalance that initially drove the deformity. Gait retraining focuses on restoring a normal heel-to-toe progression and eliminating compensatory movement patterns.

Summary of Landmark Literature and Clinical Guidelines

The evolution of midfoot cavus surgery is deeply rooted in several landmark publications that have shaped modern orthopedic guidelines. The historical standard, established by Cole in 1940 (Journal of Bone and Joint Surgery), described the anterior tarsal wedge osteotomy. While Cole’s procedure successfully corrected severe deformities, the long-term follow-up studies consistently demonstrated high rates of patient dissatisfaction due to the resulting "dumpy," shortened, and widened foot, which frequently caused profound difficulty with shoe wear.

Recognizing these severe biomechanical and cosmetic limitations, Japas published his revolutionary technique in 1968 (Journal of Bone and Joint Surgery). Japas detailed the V-osteotomy in a cohort of patients with varied neuromuscular etiologies. His seminal paper demonstrated that by utilizing a zero-resection technique and shifting the distal fragment plantarly, surgeons could effectively flatten the arch and lengthen the foot, dramatically improving both the aesthetic appearance and the biomechanical function of the foot. The Japas osteotomy rapidly became the gold standard for moderate, fixed midfoot cavus deformities, particularly in the pediatric and adolescent populations where preserving foot length is paramount.

Further refining the surgical algorithm, Jahss in 1980 (Foot & Ankle) described the truncated wedge resection across the tarsometatarsal joints. This procedure provided a critical solution for deformities localized more distally at the Lisfranc complex, offering a reliable method to correct fixed forefoot equinus without disrupting the proximal midtarsal joints.

Modern clinical guidelines, as established by the American Orthopaedic Foot & Ankle Society (AOFAS) and contemporary pediatric orthopedic consensus statements, emphasize a tailored, patient-specific approach. The current paradigm dictates that soft tissue releases (Steindler stripping) and first metatarsal osteotomies should be the first line of defense for flexible