Posterior Ankle Arthroscopy and Hindfoot Endoscopy/Tendoscopy

Florian Nickisch

Frank R. Avilucea

Phinit Phisitkul

Brad D. Blankenhorn

INTRODUCTION

The posterior ankle and hindfoot is a complex region with diverse pathology affecting several important structures that are in close proximity to each other. Due to the location of some lesions, open surgical treatment can lead to substantial morbidity requiring extensive rehabilitation.¹ Posterior hindfoot endoscopy is a minimally invasive approach that minimizes soft tissue trauma, decreases patient discomfort and morbidity, and speeds rehabilitation compared to open surgery. It offers excellent access to the posterior aspect of the tibiotalar joint, the posterior facet of the subtalar joint, and the majority of the posterior periarticular structures.

INDICATIONS

Posterior hindfoot arthroscopy often allow for both intra- and extra-articular pathology to be efficiently addressed. Surgery is generally indicated for patients with recalcitrant pain that substantially interferes with activities of normal living. Common intra-articular indications include treatment of posterior osteochondral lesions of the ankle joint, debridement of ankle or subtalar arthritis without substantial malalignment, loose body excision, synovectomy, Achilles tendon pathology, and the treatment of intraosseous talar ganglia. The surgical indications for the treatment of these lesions through a posterior arthroscopic approach are the same as for an open approach. Not only does posterior arthroscopy ease access to lesions that would be difficult to reach via an open approach, it also decreases the wound healing risks for surgical treatment of patients with soft tissue issues that would otherwise be a contraindication to surgery.

PATIENT POSITIONING

Posterior hindfoot arthroscopy is performed in the prone position. Before positioning on the operative table, general endotracheal anesthesia is induced, a thigh tourniquet is applied, and appropriate perioperative antibiotics are administered. The patient is then positioned prone on the operative table with the distal third of the tibia extended past the end of the table (Fig. 19-1). This allows for unrestricted ankle and subtalar motion as well as appropriate positioning of the fluoroscopy unit. The contralateral knee is then flexed to 90 degrees and stabilized against a post attached to the table (Fig. 19-1). A safety strap is positioned around the patient in a manner that provides countertraction, and the operative extremity is prepped and draped in a sterile fashion.

After draping, a 1.8-mm wire can be placed in the tuberosity of the calcaneus, which allows for skeletal traction and joint distraction. The wire is attached to a tension bow and traction device (Fig. 19-2). A sterile drape is placed over the traction device (Fig. 19-3). The fluoroscopy unit is then brought next to the end of the table around the patient’s hindfoot and positioned to obtain a lateral view (Fig. 19-3). This allows for hands-free fluoroscopic guidance for establishing portals for optimal access to either the posterior ankle or subtalar joints.

SURGICAL APPROACH

First described in 2000, a two-portal endoscopic approach remains the technique we most often employ to access the posterior ankle and hindfoot.²^, ³ The advantage of a two-portal technique with the patient in the prone position, is the working space available between the Achilles tendon and the posterior aspect of the tibiotalar or subtalar articulation. Moreover, this position is ergonomic for the surgeon and skeletal distraction may be easily applied.

Landmarks on the hindfoot that are essential for proper portal placement include the medial and lateral malleoli, the lateral and medial border of the Achilles tendon, and the sole of the foot. As noted, a 1.8-mm traction pin is placed into the calcaneal tuberosity from a medial to lateral direction to avoid injuring the medial
neurovascular structures (Fig. 19-2). For patients with pathology of the posterior ankle joint, skeletal traction is recommended to distract the joint.⁴ This allows for easier introduction of arthroscopic instruments. Skeletal traction is less helpful for distracting the posterior facet of the subtalar joint; nevertheless, placing a small amount of tension on the foot and ankle through skeletal traction stabilizes the foot and ankle and aids in instrument placement.

Figure 19-1. Patient positioning for posterior hindfoot arthroscopy. The patient is brought down the table until the distal third of their tibia extends beyond the end of the table. This facilitates access with the mini C-arm. The contralateral knee is flexed 90 degrees and held with a leg holder. The safety strap over the gluteal region provides counter traction (arrow).

Judicious use of fluoroscopy is employed to confirm proper portal location before making incisions. The direction of the portal placement depends on the location of the structures that need to be accessed. Portals are made just medial and lateral to the Achilles tendon. Using fluoroscopic guidance, a spinal needle is used to distend either the tibiotalar or subtalar joint. The medial and lateral borders of the Achilles tendon are then palpated and 1-cm parallel skin incisions flanking the tendon are created (Fig. 19-4). The incisions are made through only skin to avoid damage to subcutaneous nerves, in particular the sural nerve on the lateral aspect of the Achilles tendon.

Figure 19-2. Placement of a calcaneal traction pin allows for distraction of the tibiotalar joint or stabilization of the subtalar joint. A sterile drape is placed over the traction device once it is in place.

Figure 19-3. Positioning the mini C-arm below the operative leg allows for hands-free fluoroscopic assistance throughout the procedure.

Beginning at the lateral portal, a straight hemostat is used to bluntly dissect through the subcutaneous layer while aiming toward the web space between the first and second toe. For intra-articular procedures the hemostat is advanced through the joint capsule. A trocar for a 2.7-mm arthroscope is then inserted into this incision and an arthroscope is introduced. The surgeon must remain cognizant of the close proximity of the sural nerve to the posterolateral portal (3 to 12 mm).⁵^, ⁶ Fluoroscopy is used as necessary to ensure instruments do not stray into areas containing neurovascular structures during the procedure.

Establishment of a posteromedial portal is accomplished in a similar fashion. In approaching the posteromedial hindfoot, it is important to remain cognizant of
crucial medial structures. Care is taken to direct the subcutaneous tissue dissection laterally to avoid injury to the medial structures. All arthroscopic instruments should remain lateral to the flexor hallucis longus (FHL) tendon.

Figure 19-4. Medial and lateral portals placed on either side of the Achilles tendon. These portals may be localized using a spinal needle and fluoroscopy. The position is dependent on the structures that are going to be accessed during the procedure.

Figure 19-5. Magnetic resonance imaging of an ankle with a symptomatic posterior osteochondral defect (OCD). Posterior arthroscopy allows for improved access to this lesion for debridement compared to anterior arthroscopy.

When approaching extra-articular structures, saline is injected around the structure to distend potential spaces and create a working area. A blunt instrument is then used to further expand this space until enough room is present to place the arthroscope. Once the arthroscope is in place, a second portal is established and the working space is expanded using the arthroscopic shaver.

COMMON CONDITIONS TREATED WITH POSTERIOR ANKLE ARTHROSCOPY

Debridement and Microfracture of Osteochondral Lesions

One of the most common indications for posterior ankle arthroscopy is debridement and microfracture of a talar osteochondral lesion. Posterior ankle arthroscopy allows
for access to lesions that cannot be easily reached from traditional anterior arthroscopic portals. Osteochondral lesions located posterior to the midcoronal line of the medial malleolus are typically accessible through posterior arthroscopic portals (Fig. 19-5). Loose cartilage fragments and necrotic bone are debrided and microfracture of the lesion is conducted in a similar manner as anterior arthroscopic debridement using a combination of curettes and arthroscopic instruments (Fig. 19-6). Once all nonviable tissue has been debrided, an arthroscopic pick is used to perforate the underlying bone. This will facilitate fibrous cartilage healing (Fig. 19-6). No studies have been conducted to specifically examine the outcomes of osteochondral lesions undergoing posterior debridement and microfracture, but these lesions are expected to behave similarly to lesions debrided by anterior arthroscopy. Debridement of painful impinging osteophytes emanating from the subtalar or posterior tibiotalar joint can be debrided in a similar fashion.

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