Posterior Blade Plate Arthrodesis for Failed Total Ankle Arthroplasty: An Intraoperative Masterclass

Welcome, fellows, to the operating theater. Today, we're tackling a challenging but increasingly common scenario: the salvage of a failed total ankle arthroplasty (TAA) with a posterior blade plate arthrodesis. The landscape of ankle replacement is evolving rapidly, with more designs and implantations globally. As foot and ankle specialists, we must anticipate and be proficient in managing the inevitable failures that will arise, whether from aseptic osteolysis, polyethylene wear, or septic complications. While primary TAA aims to restore motion, revision often necessitates arthrodesis, especially given the limited bone stock and complex anatomy of the ankle. We'll utilize a posterior approach, which offers distinct advantages in these complex revision cases.

Understanding TAA Failure: Pathogenesis and Clinical Presentation

The success of any joint replacement is truly measured after a minimum of 5 years. For TAA, while newer designs show promise, long-term survivorship has historically lagged behind hip and knee arthroplasty. This means we will increasingly encounter patients requiring revision or salvage surgery.

TAA failure can broadly be categorized into septic or aseptic etiologies.

Aseptic Failure Mechanisms

Aseptic failure is projected to be the predominant mechanism, mirroring hip and knee replacement data. Causes include:
* Polyethylene wear: Leads to osteolysis over time.
* Ballooning osteolysis: Progressive bone destruction around the implant, a poor prognosticator for impending subsidence.
* Subsidence: Sinking of the components into the surrounding host bone.
* Implant fracture or dislocation: Catastrophic mechanical failure.
* Malalignment or instability: Clinical and/or radiographic deterioration.
* Heterotopic ossification: New bone formation restricting motion.
* Periprosthetic fracture: Fracture around the implant.
* Syndesmotic nonunion: When applicable, contributing to instability.

Septic Failure Mechanisms

Infection can occur at any point post-implantation. If it's a non-acute infection (beyond 6 to 12 weeks post-surgery), implant removal and a staged or single-stage reconstruction are typically required for successful salvage.

Clinical Presentation

A thorough history and physical examination are paramount.

• Chief Complaint: Unremitting or new-onset pain is the most common symptom of a poorly functioning or infected TAA.
• Associated Symptoms: Assess for ankle swelling and warmth. Recent onset warrants a deeper investigation for infection or acute loosening. Any history of fever, chills, or sweats is highly suggestive of sepsis.
• Patient History:
  • Time from initial implantation.
  • Prior surgeries or implantations in the region.
  • History of diabetes, neuropathy, or systemic illness predisposing to infection or abnormal wear (e.g., Charcot arthropathy).
  • Recent dental surgery without antibiotic prophylaxis.
  • Complaints of ankle or hindfoot instability.
• Physical Examination:
  • Deformity: Look for obvious ankle or hindfoot deformity, new or old. Pay particular attention to varus or cavus malalignment, which has a high association with implant failure.
  • Range of Motion (ROM): Restricted ROM, pain, crepitance, or grinding on examination should be noted.
  • Wound Status: Inspect for surrounding fluctuance, erythema, or draining sinuses around the ankle. These are red flags for infection.

Diagnostic Workup

When TAA failure is suspected, a comprehensive diagnostic workup is essential.

Laboratory Studies

• Initial Sepsis Screen: Complete blood count (CBC) with differential, erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP) level. Elevated inflammatory markers suggest infection.
• Aspiration/Biopsy:
  • If infection is suspected or the examination is equivocal, an office-based or radiologically guided aspiration is indicated for Gram stain and culture.
  • Percutaneous biopsy can also be performed, though intraoperative cultures are considered most sensitive and specific. Pathological assessment for polymorphonucleocytes per high-power field and presence of bacteria/polyethylene debris is crucial.

  • Surgical Pearl: Always consider an implant infected until proven otherwise when history, physical, and blood work suggest it. If infection is documented, consult with an infectious disease team for appropriate microbiologic and chemotherapeutic management.

Imaging Studies

• Plain Radiographs: Weight-bearing, standing plain films (anteroposterior, lateral, and oblique views) of the affected ankle are fundamental. If mechanical malalignment of the foot is suspected, obtain routine foot films as well.
  • Signs of Loosening: Radiolucent lines around components, malposition, and subsidence. These are most valuable when identified as acute changes from previous films or shown to be slowly progressive.
  • Polyethylene Wear: A narrowed joint space is often identifiable.
  • Ballooning Osteolysis: A poor prognosticator for impending implant subsidence and failure.
    

    
    
    

Figure 3A: AP radiograph of a failed total ankle arthroplasty.

Differential Diagnosis for Ankle Pain Post-TAA

• Pain of Unknown Etiology (Implants still well fixed): Complex regional pain syndrome, stiffness, fibromyalgia, neuroma, tendon incarceration, neurovascular injury or compromise, heterotopic ossification, occult fracture, syndesmotic nonunion, arthritis or impingement of nearby joints.
• Septic Failure (Infection): Requires aggressive management.
• Aseptic Failure: Impingement, osteolysis, implant or polyethylene fracture, subsidence, circumferential loosening, malposition, malalignment, dislocation, instability, periprosthetic fracture, syndesmotic nonunion.

Nonoperative Management Considerations

• Septic TAA Failure: Generally not indicated. While acute cases occasionally respond to serial aspiration and antibiotics, surgical intervention (arthroscopy or single-stage exchange) is usually most effective.
• Aseptic TAA Failure: Treatment depends on the cause.
  • Surgical Indications: Gross instability, uncontrollable pain, catastrophic implant failure (fracture), periprosthetic fracture, and aggressive (ballooning) osteolysis are best treated surgically.
  • Conservative Options: Other causes may be managed with bracing, mechanical offloading with assistive devices, pharmacologic pain control (or osteolytic inhibition), and a RICE protocol.
• Patient Tolerance: Sometimes, simple tolerance is the most appropriate course, especially when the risks of complex revision surgery outweigh potential benefits. This discussion must include the possibility of below-knee amputation as a salvage option.

Surgical Management: The Posterior Blade Plate Arthrodesis

For failed TAA requiring arthrodesis, the posterior approach with a blade plate or fixed-angle device is our preferred method. It elegantly addresses many of the challenges associated with revision ankle surgery. This procedure can be performed as a single-stage or two-stage procedure, particularly if infection is suspected or documented.

Advantages of the Posterior Approach

• Soft Tissue Envelope: Provides the healthiest and deepest soft tissue bed for reconstruction, often unscarred by previous anterior approaches.
• Single Incision: Allows comprehensive access to the failed TAA, bone graft harvest site (PSIS), and subsequent hardware coverage without tension.
• Bone Graft Access: Ready access to the posterior superior iliac spine (PSIS) for maximal autologous bone graft procurement.
• Fibula Utilization: The fibula remains in its native position, aiding in healing and proper alignment. It rarely provides enough bone to fill large defects, making its structural role more valuable than as a graft source.
• Hardware Application: Permits the use of large fixed-angle devices applied on the tension side of the construct, which compresses the fusion mass under weight-bearing loads, facilitating safe and early postoperative weight-bearing.
• Intraoperative Assessment: Facilitates rapid and accurate intraoperative assessment of radiographic and clinical position, especially hindfoot alignment.

Versatility of the Technique

This technique is versatile, adaptable for both tibiotalar (ankle) and tibiotalocalcaneal (ankle and subtalar) arthrodesis. The primary difference lies in the size and configuration of the fixation device required to span the additional joint. A variety of implant sizes and types (small- to large-fragment, locking or nonlocking, fixed-angle or straight plates) can be used.

Prone Positioning Advantages

The prone position is key to this approach:
* Soft Tissue: Allows access to a deep, usually healthy, unscarred soft tissue bed.
* Exposure: Excellent for accessing and removing the indwelling TAA, as well as covering the hardware and bone graft without tension.
* Alignment: Easiest clinical determination of hindfoot position before fusion.
* Bone Graft: Affords direct access to the posterior iliac crest for maximal bone graft procurement.
* Comparison: The contralateral leg can be prepared into the field for comparison, if needed, for alignment assessment.
* Imaging: AP and lateral radiographic images are easily obtainable with minimal manipulation by the surgeon, provided the operative leg is elevated appropriately.

Preoperative Planning: The Blueprint for Success

Meticulous preoperative planning is non-negotiable for these complex cases.

Data Review

• Review all radiographs (plain films, CT scans), laboratory parameters, and the patient's skin envelope.

Infection Management

• If the patient has a suspected or documented infected TAA, this procedure must be performed in a staged fashion. The initial stage involves implant removal, thorough debridement, and placement of a carefully contoured, anatomic polymethylmethacrylate (PMMA) antibiotic spacer. We typically impregnate this with tobramycin and vancomycin. This spacer maintains alignment and soft tissue tension between stages. The definitive arthrodesis proceeds only after infection eradication is confirmed.

Subtalar Joint Assessment

• Carefully assess for symptom production from the subtalar joint preoperatively. This can be done with two-stage office-based or fluoroscopically guided diagnostic differential injections of the talocalcaneal and subtalar joints with local anesthetic. Intraoperative visual assessment can also confirm subtalar pathology.
• Surrounding bone quality and stock, particularly on the talar side, are major factors in determining the need for adding subtalar fusion to an isolated tibiotalar arthrodesis.

Surgical Setup Preparation

• Tourniquet: Place a pneumatic tourniquet about the proximal thigh of the operative leg.
• Bone Graft Site: Square off the ipsilateral posterior iliac crest with preliminary drapes in anticipation of bone graft procurement.
• Plate Pre-contouring: This is a critical time-saving step. Pre-contour the blade plate (and determine its size) using an ankle sawbones model and a preoperative template. This significantly reduces tourniquet time and intraoperative guesswork.
  

  
  
  

Figure 4A: Pre-contouring the blade plate.

Patient Positioning and Surgical Approach

Now, let's get the patient positioned correctly.

Positioning

• Prone Position: Position the patient prone on an image table. Use gel pads for pressure point protection.
• Leg Elevation: Place a few folded blankets or a specialized bolster as a "workbench" under the affected leg. This elevates the operative extremity sufficiently above the contralateral leg, allowing unimpeded imaging of the operated extremity in the cross-table lateral projection.
  

  
  
  

Figure 5A: Patient positioning, prone with leg elevated.

The Surgical Approach: Posterior Midline Incision

• Incision: We'll make a midline longitudinal incision, typically 12 to 16 cm in length. This incision starts just proximal to the insertion of the Achilles tendon and extends proximally along the posterior aspect of the leg. The exact length will depend on the extent of previous scarring and the required exposure for implant removal and fusion.

Intraoperative Execution: A Step-by-Step Masterclass

Alright, fellows, scalpel in hand. Let's begin the dissection.

Additional Intraoperative Imaging & Surgical Steps

References

FIG 8 • Weight-bearing lateral radiograph 3 months postoperatively.

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3. Hansen T, Cracchiolo A. The use of a 95 degree blasé plate and posterior approach to tibiotalocalcaneal arthrodesis. Foot Ankle Int 2002;23:704–710.

4. Peyvich M, Saltzman C. Total ankle arthroplasty: a unique design. J Bone Joint Surg Am 1998;80A:1410–1420.

5. Quill G. Tibiotalocalcaneal arthrodesis with medullary rod fixation. Tech Foot Ankle Surg 2003;2:135–143.

6. Wapner K. Salvage of failed and infected total ankle replacements with fusion. AAOS Instructional Course Lectures 2002;51:153–157.