Principles of Foot and Ankle Surgery: Tourniquets, Instrumentation, and Regional Anesthesia

INTRODUCTION TO OPERATIVE FOOT AND ANKLE PRINCIPLES

The successful execution of foot and ankle surgery demands a profound understanding of regional anatomy, meticulous preoperative planning, and the precise application of surgical principles. Unlike other orthopedic subspecialties, the foot and ankle present unique challenges due to their complex biomechanics, delicate soft tissue envelope, and terminal vascular supply. Achieving optimal outcomes requires the surgeon to master the creation of a bloodless surgical field, utilize highly specialized instrumentation, and implement effective regional anesthesia protocols.

This comprehensive guide expands upon the foundational principles of operative foot and ankle surgery, detailing the step-by-step application of an ankle tourniquet, evidence-based thromboprophylaxis, the strategic organization of surgical instrumentation, and the administration of regional forefoot blocks.

APPLICATION OF A TOURNIQUET AND EXSANGUINATION

The use of a tourniquet is indispensable in foot and ankle surgery to provide a bloodless field, thereby facilitating precise anatomical dissection and minimizing operative time. While proximal thigh tourniquets are commonly used, the application of a distal Esmarch bandage or a dedicated ankle tourniquet is highly advantageous for forefoot and midfoot procedures. Distal tourniquets significantly reduce the ischemic volume of the limb and dramatically decrease the incidence of tourniquet-induced pain, which is a common limiting factor in procedures performed under regional anesthesia or monitored anesthesia care (MAC).

Biomechanics and Indications

The primary indication for an ankle tourniquet is any surgical procedure distal to the mid-substance of the leg, provided the anticipated tourniquet time does not exceed 90 to 120 minutes. The biomechanical advantage of placing the tourniquet just proximal to the malleoli lies in the anatomical composition of the distal leg. In this region, the tibia and fibula are primarily surrounded by tendinous structures rather than bulky muscle bellies. Consequently, lower compressive forces are required to achieve arterial occlusion compared to the proximal calf or thigh.

💡 Clinical Pearl: Tourniquet Placement

Always place the ankle tourniquet distal to the muscle mass of the gastrocnemius and soleus. Placing the tourniquet over the muscle belly not only requires higher inflation pressures to achieve arterial occlusion but also significantly increases postoperative pain and the risk of muscle ischemia.

Step-by-Step Surgical Technique: The Esmarch Bandage

When utilizing an Esmarch bandage for both exsanguination and as a definitive tourniquet (the "Martin bandage" technique), meticulous application is critical to prevent skin necrosis, nerve palsy, and venous congestion.

1. Patient Positioning and Limb Elevation: Elevate the operative limb for 2 to 3 minutes prior to application to allow for passive venous drainage.
2. Initial Anchoring: Have an assistant hold the distal end of the Esmarch wrap at a 45-degree angle to the foot. The assistant must place continuous, firm tension on the free end. Simultaneously, the surgeon’s thumb must hold the initial wrap firmly against the skin to prevent slippage.
3. Overlapping Technique: Begin wrapping the tourniquet tightly around the foot and ankle. Do not overlap each turn by more than half the width of the tourniquet. This ensures even distribution of pressure and prevents the creation of high-pressure ridges that can cause focal skin necrosis or nerve compression.
4. Skin Protection: Wrap the tourniquet meticulously above the ankle, being exceptionally careful not to leave any skin uncovered between the wraps. Ensure that the edges of the Esmarch bandage do not roll on themselves, as a rolled edge acts as a narrow band of extreme pressure.
5. Proximal Progression: As the wrap proceeds proximally above the ankle, stop no more than 8 to 10 cm proximal to the malleoli. It is imperative to stay distal to the muscular mass of the calf. Proceeding more proximally will exponentially increase the discomfort caused by the tourniquet and reduce the efficacy of the block.
6. Securing the Tourniquet: Complete the exsanguination with no more than three or four tight “cinches” around the distal leg, followed by a secure tuck of the remaining bandage under the proximal-most wrap.

🚨 Surgical Warning: The Superficial Peroneal Nerve

The superficial peroneal nerve pierces the deep fascia to become subcutaneous approximately 10 to 12 cm proximal to the lateral malleolus. Applying a tight Esmarch bandage directly over this exit point can result in a severe crush injury to the nerve, leading to postoperative neuropathy or complex regional pain syndrome (CRPS). Always ensure the proximal extent of the wrap remains distal to this anatomical landmark.

VENOUS THROMBOEMBOLISM (VTE) PROPHYLAXIS

The necessity of routine deep venous thrombosis (DVT) prophylaxis in isolated foot and ankle surgery remains a topic of academic debate. However, the consensus among major orthopedic societies, including the American Academy of Orthopaedic Surgeons (AAOS) and the American College of Chest Physicians (ACCP), is that the baseline risk of VTE in this population is exceedingly low.

Evidence-Based Incidence

In large-scale epidemiological studies and meta-analyses, the occurrence of symptomatic deep venous thrombosis following foot and ankle surgery ranges from 0.22% to 3.5%. Furthermore, the incidence of fatal pulmonary embolism (PE) in isolated foot and ankle procedures is virtually zero in patients without significant systemic risk factors. The lower incidence of VTE compared to hip and knee arthroplasty is attributed to the smaller surgical footprint, reduced systemic inflammatory response, and the lack of major venous kinking or femoral vein manipulation during surgery.

Institutional Protocols and Risk Stratification

Due to the low baseline risk, routine prophylactic anticoagulation (e.g., Low Molecular Weight Heparin, Direct Oral Anticoagulants) is not universally recommended after standard foot and ankle surgery. At most tertiary orthopedic institutions, chemical prophylaxis is reserved for patients who exhibit specific, high-risk criteria based on validated scoring systems (such as the Caprini Risk Assessment Model).

Risk factors that may warrant chemical prophylaxis include:
* Personal or strong family history of VTE.
* Known hypercoagulable states (e.g., Factor V Leiden, Protein C/S deficiency).
* Active malignancy.
* Use of oral contraceptives or hormone replacement therapy.
* Procedures requiring prolonged postoperative immobilization in a non-weight-bearing cast (e.g., Achilles tendon repair, complex hindfoot arthrodesis).

For the vast majority of patients, early mobilization, mechanical prophylaxis (if immobilized), and adequate hydration are sufficient to mitigate VTE risk.

SPECIALIZED SURGICAL INSTRUMENTATION

The soft tissue envelope of the foot and ankle is notoriously unforgiving. The skin is thin, subcutaneous fat is sparse (except on the plantar aspect), and the vascular supply is easily compromised by excessive tension or rough handling. Therefore, the use of specialized, delicate instrumentation is mandatory. Organizing instruments into designated "soft tissue" and "bone" trays streamlines the surgical workflow and ensures the appropriate tools are immediately available.

The "Foot Tray—Soft Tissue"

The soft tissue tray is designed for atraumatic dissection and the preservation of the microvascular circulation. Indelicate dissection leads to a severe edematous reaction, delayed wound healing, and increased risk of infection.

• Blades and Handles: A No. 15 Bard-Parker blade attached to a multisided (round or hexagonal) handle is essential. The multisided handle allows the surgeon to roll the instrument between the fingers, facilitating quick, fluid changes in the angle of dissection without awkward wrist movements.
• Forceps: Delicate forceps with 1.5 mm between the teeth (e.g., Adson or fine Bishop-Harmon forceps) are required for skin edges. Brown-Adson forceps, with their multiple fine teeth, are highly effective for grasping small bone fragments, retinacular tissue, and bulky soft tissues without causing crush injuries.
• Dissection Technique: Sharp dissection with a scalpel is strictly indicated whenever practical. Tearing tissue with blunt instruments causes microvascular thrombosis and subsequent tissue necrosis. When blunt dissection is absolutely necessary, small scissors with gently curved and slightly blunted tips (e.g., tenotomy or Stevens scissors) should be utilized.
• Retractors: Narrow and wide-neck mini-Hohmann retractors, along with small double-ended, right-angle retractors (e.g., Senn or Ragnell), are invaluable. These allow the assistant’s hands to remain out of the surgical field while affording excellent, low-tension exposure.
• Hemostasis and Suturing: Mosquito hemostats are used for the precise occlusion of small vessels prior to electrocautery. Webster needle holders, featuring smooth jaws, are critical for grasping fine (4-0 to 5-0) monofilament sutures without fraying or weakening the suture material. A 70-degree angled probe completes the tray, allowing for the atraumatic exploration of tendon sheaths and joint spaces.

The "Foot Tray—Bone"

The bone tray contains scaled-up versions of the soft tissue instruments, designed to handle the robust osseous and tendinous structures encountered in midfoot and hindfoot arthrodeses, osteotomies, and major tendon transfers.

• Heavy Instrumentation: Heavier blades (No. 10 or No. 11), robust toothed forceps, Mayo dissecting scissors, and heavy-duty needle holders are required for thick plantar fascia, Achilles tendon, and joint capsule management.
• Bone Preparation: Thin osteotomes (curved and straight), a small well-balanced mallet, and small curets (sizes 0 to 3-0) are necessary for cartilage debridement and osteotomy creation.
• Specialized Retractors: Heavy-duty two-tooth retractors and wide dissecting probes are utilized for deeper exposures. The modified Inge retractor is a cornerstone of the bone tray. By thinning the arms and narrowing the teeth of a standard Inge retractor, the surgeon can distract small joints (e.g., the subtalar or transverse tarsal joints) without obstructing the visual field or damaging adjacent articular cartilage.

Power Instruments and Visualization

Efficiency in foot and ankle surgery relies heavily on appropriate power tools and enhanced visualization.

• Wire Drivers: A Kirschner wire (K-wire) inserter that operates via a trigger mechanism, rather than requiring a key release, is highly recommended. This allows the surgeon to rapidly change wires or adjust the length of the wire protruding from the collet, significantly reducing operative time during complex forefoot reconstructions.
• Saws: A power oscillating saw equipped with thin, narrow blades is essential for precise osteotomies (e.g., Chevron or Scarf osteotomies of the first metatarsal) to minimize thermal necrosis and bone loss from the saw kerf.
• Magnification: The intricate neurovascular anatomy of the foot necessitates magnification. The routine use of 2.5× to 3.5× magnification loupes is standard practice for identifying digital nerves, repairing small tendons, and ensuring meticulous wound closure.
• Documentation: A high-definition, easily operable camera should be available in the operating room to document the pathology, the intraoperative correction, and the final result. This is invaluable for academic purposes, patient education, and medicolegal documentation.

ANESTHESIA AND REGIONAL BLOCKS

The landscape of foot and ankle surgery has shifted dramatically toward the outpatient, ambulatory setting. Consequently, the benefits of regional anesthesia—specifically forefoot and ankle blocks—have become paramount. Regional blocks provide excellent intraoperative anesthesia, profound postoperative analgesia, reduce the need for systemic opioids, and facilitate rapid discharge.

Pharmacological Agents

A highly effective and widely utilized local anesthetic mixture is a 50/50 combination of 1% lidocaine (Xylocaine) and 0.5% bupivacaine (Marcaine) without epinephrine. Lidocaine provides a rapid onset of action (within 5 to 10 minutes), while bupivacaine ensures prolonged postoperative analgesia lasting 8 to 12 hours. The volume administered must be carefully calculated based on the patient's weight (mg/kg) to avoid Local Anesthetic Systemic Toxicity (LAST).

Typically, these blocks are performed in the preoperative holding area or the operating room by the surgical team or anesthesia personnel, who simultaneously provide intravenous sedation (e.g., midazolam and propofol) and monitor the patient's hemodynamics.

The Forefoot Block

The forefoot block is an elegant, highly effective technique for distal procedures, including distal first metatarsal osteotomies (e.g., for hallux valgus), sesamoidectomies, Morton's neuroma excisions, and hammer toe corrections.

A complete forefoot block requires the systematic anesthetization of the terminal branches of five specific nerves:

1. Deep Peroneal Nerve: Supplies the first web space. Approached dorsally, injecting between the extensor hallucis longus (EHL) and extensor digitorum longus (EDL) tendons at the level of the tarsometatarsal joints.
2. Superficial Peroneal Nerve: Supplies the dorsum of the foot. Blocked via a subcutaneous wheal extending from the medial malleolus to the lateral malleolus across the dorsal aspect of the midfoot.
3. Saphenous Nerve: Supplies the medial aspect of the midfoot and forefoot. Blocked via a subcutaneous injection anterior to the medial malleolus.
4. Sural Nerve: Supplies the lateral aspect of the foot. Blocked via a subcutaneous injection posterior to the lateral malleolus.
5. Posterior Tibial Nerve (Medial and Lateral Plantar Branches): Supplies the plantar aspect of the foot. While a formal ankle block targets the nerve behind the medial malleolus, a forefoot block can target the medial and lateral plantar nerves more distally in the sole of the foot, though this is often more painful and requires careful needle placement to avoid intravascular injection.

💡 Clinical Pearl: Regional Block Execution

Always aspirate prior to injecting local anesthetic to rule out intravascular placement, particularly when blocking the deep peroneal nerve near the dorsalis pedis artery, or the posterior tibial nerve near the posterior tibial artery. Use a 25-gauge or 27-gauge needle to minimize tissue trauma and patient discomfort.

POSTOPERATIVE PROTOCOLS AND REHABILITATION

The success of foot and ankle surgery is as dependent on postoperative care as it is on intraoperative execution.

1. Elevation: Strict elevation of the operative limb above the level of the heart is mandatory for the first 48 to 72 hours. This is the single most effective method for controlling postoperative edema, reducing pain, and preventing wound dehiscence.
2. Dressing Management: The initial surgical dressing should be bulky, mildly compressive, and left undisturbed until the first postoperative clinic visit (typically 10 to 14 days), unless there is suspicion of infection or excessive bleeding.
3. Weight-Bearing Status: Weight-bearing protocols are strictly dictated by the procedure performed. Soft tissue procedures and stable internal fixation may allow for immediate heel-weight-bearing in a rigid postoperative shoe. Conversely, arthrodeses and complex osteotomies require strict non-weight-bearing in a cast or controlled ankle motion (CAM) boot for 6 to 8 weeks to ensure osseous union.
4. Suture Removal: Due to the tenuous vascularity of the foot, sutures are typically left in place longer than in other areas of the body. Removal between 14 and 21 days is standard, ensuring the incision is fully epithelialized and capable of withstanding the mechanical stresses of mobilization.