Calcaneocuboid Joint Arthrodesis: A Comprehensive Surgical Guide

INTRODUCTION TO CALCANEOCUBOID JOINT ARTHRODESIS

Calcaneocuboid (CC) joint arthrodesis is a foundational procedure in reconstructive foot and ankle surgery. While occasionally performed as an isolated fusion for localized post-traumatic osteoarthritis, it is most frequently executed as a critical component of a double or triple arthrodesis to address complex hindfoot deformities, such as stage III or IV posterior tibial tendon dysfunction (PTTD), severe cavovarus foot, or advanced rheumatoid arthritis.

The primary objective of a calcaneocuboid arthrodesis is to eliminate painful articulation, restore the structural integrity of the lateral column, and re-establish a stable, plantigrade foot. Achieving a successful fusion requires a profound understanding of transverse tarsal joint biomechanics, meticulous soft tissue handling, precise articular preparation, and rigid internal fixation. This comprehensive guide delineates the evidence-based surgical technique, anatomical considerations, and postoperative protocols required to optimize clinical outcomes.

SURGICAL ANATOMY AND BIOMECHANICS

A thorough appreciation of the regional anatomy is paramount for safe surgical exposure and effective joint preparation.

The Calcaneocuboid Articulation

The calcaneocuboid joint forms the lateral half of the transverse tarsal (Chopart) joint. Unlike the highly mobile talonavicular joint, the CC joint is inherently restricted in its motion.
* Articular Geometry: The joint surfaces are uniquely saddle-shaped (sinusoid). The distal calcaneus presents a convex surface transversely and a concave surface vertically, which perfectly interlocks with the reciprocal articular surface of the proximal cuboid. This interlocking geometry provides substantial intrinsic osseous stability.
* Plantar and Medial Extension: The articular surface extends significantly further plantarward and medially than is often appreciated on standard radiographs. Failure to recognize this extension can lead to incomplete cartilage removal and subsequent nonunion.

Ligamentous Support

The CC joint is fortified by a robust ligamentous complex:
* Bifurcate Ligament: Originates on the anterior process of the calcaneus and divides into the calcaneonavicular and calcaneocuboid bands.
* Dorsal Calcaneocuboid Ligament: A broad, thin band reinforcing the dorsal capsule.
* Plantar Ligaments: The short plantar (plantar calcaneocuboid) and long plantar ligaments provide critical support to the lateral longitudinal arch and must be carefully managed during plantar exposure.

Neurovascular Considerations

• Sural Nerve: The sural nerve and its lateral dorsal cutaneous branches traverse the dorsolateral aspect of the hindfoot and midfoot. These structures are highly vulnerable during the initial incision and superficial dissection.
• Extensor Digitorum Brevis (EDB): The muscle belly of the EDB originates on the dorsolateral calcaneus, directly overlying the CC joint, and must be mobilized to achieve adequate exposure.

🔪 Surgical Warning: Lateral Column Length

The calcaneocuboid joint dictates the length of the lateral column. Aggressive, flat-cut resections using a saw will inevitably shorten the lateral column, potentially inducing an iatrogenic forefoot abduction deformity. Joint preparation must preserve the native saddle contour using curettes and osteotomes.

INDICATIONS AND CONTRAINDICATIONS

Indications

• Primary or Post-Traumatic Osteoarthritis: Often secondary to intra-articular calcaneus or cuboid fractures.
• Inflammatory Arthritis: Advanced rheumatoid arthritis involving the transverse tarsal joint.
• Adult Acquired Flatfoot Deformity (AAFD): Stage III or IV PTTD requiring a triple arthrodesis or lateral column lengthening/fusion.
• Cavovarus Deformity: Neuromuscular conditions (e.g., Charcot-Marie-Tooth disease) requiring rigid stabilization of the hindfoot.
• Tarsal Coalition: Symptomatic, recalcitrant calcaneonavicular coalitions with secondary CC joint degenerative changes.

Contraindications

• Absolute: Active local or systemic infection, severe peripheral arterial disease (PAD) precluding wound healing, and medically unstable patients.
• Relative: Charcot neuroarthropathy (requires specialized fixation techniques and prolonged immobilization), severe osteopenia, and active smoking (significantly increases nonunion rates).

PREOPERATIVE PLANNING

Comprehensive preoperative evaluation is essential. Weight-bearing anteroposterior (AP), lateral, and oblique radiographs of the foot and ankle are mandatory to assess joint space narrowing, osteophyte formation, and overall foot alignment.

Computed Tomography (CT) is highly recommended to evaluate the extent of subchondral sclerosis, cystic changes, and the precise three-dimensional geometry of the deformity. If avascular necrosis of the cuboid or calcaneus is suspected, Magnetic Resonance Imaging (MRI) may be indicated.

PATIENT POSITIONING AND ANESTHESIA

1. Anesthesia: A regional popliteal sciatic nerve block combined with a saphenous nerve block provides excellent intraoperative anesthesia and postoperative analgesia. General anesthesia or monitored anesthesia care (MAC) is utilized based on patient and anesthesiologist preference.
2. Positioning: The patient is placed in the supine position. A well-padded bump is placed under the ipsilateral hip to internally rotate the leg, bringing the lateral aspect of the foot into a direct, accessible view.
3. Tourniquet: A pneumatic thigh or calf tourniquet is applied over adequate padding to ensure a bloodless surgical field.

SURGICAL TECHNIQUE: STEP-BY-STEP

1. Incision and Superficial Dissection

• Incision Placement: Begin with a straight or slightly curved incision on the dorsolateral surface of the foot. The joint can be palpated and localized by gently abducting and adducting the forefoot on the hindfoot. The incision should extend from 2 to 3 cm proximal to the CC joint to 2 to 3 cm distal to it.
• Nerve Protection: Carefully deepen the incision through the subcutaneous tissue. Identify, mobilize, and protect any branches of the sural nerve using vessel loops or gentle retraction.
• Flap Elevation: Raise full-thickness dorsal and plantar flaps sharply from the bone. This technique minimizes the risk of skin edge necrosis.
• Muscle Mobilization: Elevate the extensor digitorum brevis (EDB) muscle belly dorsally off its origin on the calcaneus to expose the underlying joint capsule.

2. Deep Exposure and Capsulotomy

• Plantar Exposure: Expose the plantar aspect of the calcaneocuboid joint by elevating the full-thickness plantar flap. It is critical to recognize that the articular surface of the CC joint is sinusoid and extends further plantarward and medially than expected.
• Capsular Release: Open the capsule dorsally and laterally.
• Ligamentous Excision: Systematically remove the bifurcate ligament, the dorsolateral calcaneocuboid ligament, and the lateral calcaneocuboid ligaments to allow for adequate joint distraction. A lamina spreader or a Hintermann retractor can be inserted to distract the joint and visualize the deep medial and plantar articular surfaces.

🔪 Clinical Pearl: Joint Distraction

When inserting a lamina spreader, place the tines carefully into the subchondral bone rather than the soft cancellous bone to prevent iatrogenic crush fractures of the cuboid or calcaneus, which can compromise subsequent screw purchase.

3. Articular Surface Preparation

Meticulous joint preparation is the most critical factor in preventing nonunion.
* Debridement: Using a combination of sharp curettes and a small, thin osteotome, meticulously denude the articular cartilage from both the calcaneal and cuboid surfaces.
* Preserving the Contour: Do not use a power saw. The saddle shape of the joint must be preserved to maintain lateral column length and intrinsic stability.
* Subchondral Drilling: Once the subchondral bone is exposed, stimulate osteogenesis by drilling multiple holes into both the calcaneus and the cuboid. We routinely use a 2.0-mm or 2.5-mm drill bit for this purpose.
* Crosshatching: Further prepare the surfaces by crosshatching the subchondral bone with a 1/4-inch osteotome. This technique, often referred to as "fish-scaling," increases the surface area for fusion and promotes the release of bone marrow elements rich in mesenchymal stem cells.

4. Sequencing in Multiple Arthrodeses

If the calcaneocuboid arthrodesis is being performed as part of a triple arthrodesis, the sequence of fixation is paramount.
* Perform the talonavicular (TN) joint arthrodesis first. The TN joint is the "key" to the transverse tarsal joint; its reduction and internal fixation dictate the alignment of the entire midfoot and hindfoot.
* Once the TN joint has been anatomically reduced and internally fixed, return to the calcaneocuboid joint for final fixation.

5. Internal Fixation

Rigid compression is required for successful arthrodesis.
* Screw Selection: Arthrodese the joint using a partially threaded, 6.5-mm or 7.0-mm cancellous screw.
* Trajectory: The screw is placed from the distal dorsal surface of the cuboid and directed posteriorly and plantarward into the anterior process and body of the calcaneus. This trajectory crosses the joint perpendicular to its primary plane, maximizing compression.
* Countersinking: It is absolutely critical to countersink the drill hole in the cuboid. The dorsal cortex of the cuboid is thin and fragile; failure to countersink will result in the screw head fracturing the cortex, leading to a catastrophic loss of compression and hardware failure.
* Alternative Fixation: Depending on patient anatomy and bone quality, two 4.0-mm or 4.5-mm fully threaded cancellous screws (utilized as lag screws by overdrilling the near cortex) can be used instead of one large screw to provide rotational stability. Alternatively, modern anatomically contoured locking plates can be utilized, particularly in revision scenarios or poor bone quality.

🔪 Surgical Pitfall: Hardware Prominence

Ensure the screw head is fully seated within the countersunk recess of the cuboid. A prominent screw head on the dorsolateral foot will cause severe postoperative shoe-wear irritation, often necessitating a secondary procedure for hardware removal.

6. Closure

• Irrigation and Hemostasis: Deflate the tourniquet and achieve meticulous hemostasis using electrocautery. Copiously irrigate the wound with sterile saline.
• Drainage: Drain the wounds using a closed-suction drain if significant dead space or bleeding is present.
• Layered Closure: Close the capsule and EDB fascia with 2-0 or 3-0 absorbable sutures. Close the subcutaneous tissue with 3-0 absorbable buried sutures, and approximate the skin with 4-0 non-absorbable nylon or a subcuticular closure.
• Dressing: Apply a sterile, non-adherent dressing followed by a large, bulky compression dressing and a rigid short-leg posterolateral splint with the foot in a neutral, plantigrade position.

POSTOPERATIVE CARE PROTOCOL

Successful calcaneocuboid arthrodesis relies heavily on strict adherence to postoperative immobilization and weight-bearing restrictions.

Phase 1: Immediate Postoperative (Weeks 0 to 2)

• The patient is strictly non-weight-bearing (NWB) on the operative extremity.
• Strict elevation of the limb above heart level is mandated to minimize edema and promote wound healing.
• At 2 to 3 weeks post-surgery, the patient returns to the clinic. The splint and sutures are removed. Clinical evaluation of the incision is performed.
• A short-leg, nonwalking fiberglass cast is applied.

Phase 2: Intermediate Healing (Weeks 3 to 6)

• The patient remains strictly non-weight-bearing in the short-leg cast.
• The cast is worn continuously until the end of the sixth postoperative week.
• Deep vein thrombosis (DVT) prophylaxis should be considered based on patient risk factors during this period of immobility.

Phase 3: Transition to Weight-Bearing (Weeks 6 to 12)

• At the 6-week mark, radiographs (AP, lateral, and oblique) are obtained to assess the progression of the arthrodesis.
• Depending on the radiographic appearance of bridging trabecular bone and clinical absence of pain, a short-leg walking cast or a removable, prefabricated controlled ankle motion (CAM) boot is applied.
• The patient is allowed to begin progressive weight-bearing, gradually discontinuing the use of crutches as tolerated.
• Physical therapy is initiated to focus on proximal muscle strengthening and gentle range of motion of the unfused joints.

Phase 4: Long-Term Rehabilitation (3 Months and Beyond)

• At 3 months, the arthrodesis is evaluated clinically and radiographically for solid fusion.
• Once solid union is confirmed, the patient is transitioned out of the cast or CAM boot.
• Usually, support hose (compression stockings) and a well-padded, soft-soled shoe or a shoe with a rigid rocker-bottom sole may be worn to accommodate the altered biomechanics of the foot.
• The transition from cast to shoe may be made easier by the short-term use of the removable CAM boot during periods of prolonged standing or walking.

COMPLICATIONS AND MANAGEMENT

While generally highly successful, CC joint arthrodesis carries specific risks:
* Nonunion/Delayed Union: The CC joint has historically higher nonunion rates compared to other hindfoot joints, often due to inadequate preparation of the deep plantar/medial articular extensions. Management includes prolonged immobilization, bone stimulators, or revision surgery with bone grafting.
* Sural Nerve Neuritis: Injury or entrapment of the sural nerve can cause debilitating lateral foot pain. Careful surgical dissection and avoidance of aggressive retraction are preventative.
* Lateral Column Shortening: Over-resection of the joint surfaces leads to lateral column shortening, resulting in forefoot abduction and medial column overload.
* Adjacent Segment Disease: Fusion of the CC joint alters transverse tarsal kinematics, increasing stress on the adjacent talonavicular and tarsometatarsal joints, which may lead to accelerated degeneration over time.