Basics of Ankle Arthroscopy Part 2: Surface Anatomy, Portal Placement, and Diagnostic Evaluation for Anterior Ankle Arthroscopy

Abstract

Ankle arthroscopy is an important diagnostic and therapeutic tool in the treatment of pathologies of the ankle joint. In a series of 7 articles, the basics of ankle arthroscopy are reviewed. In this article (Part II), anterior ankle surface anatomy, portal placement, and diagnostic arthroscopy are reviewed. We also review benefits and drawbacks associated with a 1.9-mm 0° arthroscope in comparison to a standard 2.7-mm or 4.0-mm 30° arthroscope.

Anterior ankle arthroscopy is a commonly performed procedure to address and diagnose a litany of pathologies of the ankle joint.¹ Indications for anterior ankle arthroscopy include diagnostic arthroscopy, anterior ankle impingement resection, bone marrow stimulation for osteochondral lesions of the talus, loose body removal, arthroscopically assisted ankle fracture fixation, and lateral ankle ligament reconstruction.1, 2, 3 In this 7-part series reviewing the basics of ankle arthroscopy, we present a comprehensive review of the complete surgical technique for the basics of ankle arthroscopy. This article will review the relevant surface anatomy, portal placement, and diagnostic arthroscopy of the anterior ankle. All procedures were performed in compliance with laws and institutional guidelines and have been approved by the appropriate institutional committees.

Diagnostic anterior ankle arthroscopy involves visualization of all the intra-articular structures of the ankle. A complete diagnostic arthroscopy includes visualization of the anterior compartment, central compartment, posterior compartment, lateral compartment, lateral gutter, medial compartment, and medial gutter.⁴ Access to these regions may be restricted by excessive fibrotic tissue and/or bony exostoses. In this article and video, we provide a standardized, step-by-step approach to ankle arthroscopy using a 1.9-mm 0° arthroscope (Arthrex, Naples, FL). We also review the benefits and drawbacks associated with a 1.9-mm 0° arthroscope in comparison to a standard 2.7-mm (Arthrex) or 4.0-mm 30° arthroscope (Arthrex) with noninvasive distraction in a formal operating suite.

Surgical Technique

Surface Anatomy

The relevant bony landmarks include the distal tibia, lateral malleolus, anterior joint line, and the talus (Fig 1). To establish the anteromedial portal, begin by identifying the anterior tibial tendon and the anterior joint line. Passive dorsiflexion of the ankle facilitates palpation of the anterior joint line, located 2 cm proximal to the tip of the lateral malleolus and 1 cm proximal to the tip of the medial malleolus. Locate the premalleolar depression or “soft spot” just medial to the anterior tibial tendon, and insert the portal at this site, ensuring it is positioned just medial to the anterior tibial tendon. Caution must be observed to avoid iatrogenic injury to the saphenous vein and nerve, which crosses the ankle joint along the anterior edge of the medial malleolus.⁵

Fig 1.

Arthroscopic approach to the left cadaveric ankle via the anterolateral and anteromedial portals. Visualized are the anteromedial portal, anterolateral portal, fibula, medial malleolus, talus, and anterior joint line. Figure used with permission from the senior author (J.G.K.), published by Colasanti et al.

For the anterolateral portal, identify the tendon of the peroneus tertius and the joint line, again using the bony landmark of the lateral malleolus for orientation. The peroneal tendons pass immediately posterior to the lateral malleolus. Position the anterolateral portal lateral to peroneus tertius tendon at the level of the joint line. Care must be taken during placement of the anterolateral portal due to several delicate nerve branches that traverse the anterolateral aspect of the ankle joint, including the superficial peroneal nerve (SPN), which divides 6.5 cm proximal to the tip of the fibula into the intermediate dorsal and medial dorsal cutaneous branches.⁶ The superficial peroneal nerve can be rendered visible via the fourth toe flexion sign or “Stephens’” sign, which involves inversion of the ankle and plantarflexion of the foot⁶ (Fig 2). The SPN is often palpated as a thin, tense cord-like structure.

Fig 2.

Inversion and plantarflexion of the right ankle, demonstrating the superficial peroneal nerve (SPN). Visualized are the SPN, anteromedial portal, and anterolateral portal.

Portal Placement and Diagnostic Arthroscopy

Following sterile preparation and draping of the operative extremity, the surgeon uses a sterile marking pen to outline the anteromedial portal, anterolateral portal, and the SPN. The anteromedial portal is established first due to ease of access compared to the anterolateral portal and lower risk of injury to the associated neurovascular structures. If the procedure is performed in a formal operating theatre, 10 mL of sterile saline is injected into the anteromedial portal with a 22-gauge needle angled in a posterolateral direction. If the procedure is performed in the office setting, a 9-mL cocktail of 1% lidocaine (3 mL), 0.5% bupivacaine (3 mL) and 1:100,000 lidocaine:epinephrine (3 mL) is injected into the anteromedial portal and anterolateral portals 10 minutes before the beginning of the procedure and again immediately prior to commencing the procedure. Joint distention is confirmed by outpouching of the anterolateral capsular wall and passive dorsiflexion of the ankle joint.

A 1-cm vertical skin incision is created using a No. 11 blade. When using a 2.7-mm arthroscope, a mosquito clamp is next inserted through the subcutaneous tissue and capsule. This step is not necessary when using a 1.9-mm arthroscope. Next, a blunt trocar is inserted with the ankle in dorsiflexion to avoid iatrogenic cartilage injury. The obturator is then exchanged for the arthroscope, and the fluid flow is commenced. The initial pressure is typically set to 30 to 40 mm Hg. If the joint is easily visualized, a spinal needle is inserted into the anterolateral portal under arthroscopic guidance. In a similar fashion, a No. 11 blade is used to make a small, 1-cm vertical incision, with extreme caution taken not to injure the branches of the SPN, followed by insertion of a mosquito clamp to establish the anterolateral portal. This is followed by insertion of a 3.0-mm dissecting shaver (Arthrex) into the joint. At this juncture, if distraction across the tibiotalar joint is felt to be inadequate, additional distraction can be applied.

The arthroscopic examination is always performed initially through the anteromedial portal and then through the anterolateral portal. Theoretically, a diagnostic ankle arthroscopy initially involves assessment of the central and medial aspect of the ankle joint through the anteromedial portal followed by assessment of the central and lateral aspect of the ankle joint through the anterolateral portal. However, in reality, a diagnostic ankle arthroscopy is rarely performed in isolation and will always entail some resection of bony and/or soft tissue pathology. These impinging structures may significantly disrupt both visualization and maneuvering of the arthroscope through the joint, warranting transfer of the arthroscope and various instruments between each portal multiple times. Thus, it is impractical and unrealistic to suggest that a diagnostic arthroscopy can be reproducibly performed in the exact same fashion for each procedure. However, listed below are step-by-step instructions on performing a diagnostic arthroscopy under ideal circumstances, the relevant surgical anatomy, common pathologies that can be encountered, and how to address them.

The first structure visualized following insertion of the arthroscope is the central talar articulation with the tibial plafond (Fig 3). The distal aspect of the tibial lip projects slightly anteriorly in the sagittal plane, articulating within the sagittal groove. The sagittal groove lies between the medial and lateral talar shoulders and projects from anterior to posterior. The anterior tibial lip is lined by hyaline cartilage that extends from the undersurface of the tibial plafond around the anterior corner superiorly. The synovial recess lies between the anterior tibial lip and the capsular reflection and is a frequent site for tibial osteophyte development and synovial and capsular adhesion. Osteophytes are less commonly found at the talar neck. If an osteophyte is identified, a 3.0 mm shaver is introduced through the anterolateral portal. The osteophyte is initially addressed with the shaver and then further debrided using a 3.0 mm burr. At this point, and throughout the entire arthroscopic examination, any osteochondral lesions of the talus and/or tibial plafond are noted and recorded.

Fig 3.

Arthroscopic view of the anterocentral aspect of the of the right ankle through the anteromedial portal. Visualized is the articulation between the tibial plafond and talus, with some surrounding scar tissue.

Attention is then drawn to the medial corner of the ankle, the site of the articulation between the tibia and medial talar dome. The anterior articular margin of the tibia shifts from a horizontal configuration laterally and centrally, to a convex configuration coronally. This has a rate of osteochondral lesions of the talus and bony exostoses (Fig 4). The notch of Harty enables the arthroscope to navigate down into the medial gutter without iatrogenic injury to the articular cartilage. The medial gutter extends from the inferior aspect of the medial talar dome down toward the deltoid ligament, and is a common site of talar osteophytes, which must be resected if identified (Fig 5). Dense fibrotic tissue is often encountered in this region and must be debrided with a shaver or biter.

Fig 4.

Arthroscopic view of the anteromedial aspect of the of the right ankle through the anterolateral portal. Visualized is a bony exostosis of the tibial plafond with adjacent fibrotic tissue and the articulating talar dome.

Fig 5.

Arthroscopic view of the medial gutter of the right ankle through the anterolateral portal. Visualized is an exostosis of the talus and the shaver.

The arthroscope is then maneuvered back up through the medial gutter, over the notch of Harty, toward the anterocentral region of the ankle and is directed toward the lateral aspect of the ankle. The “trifurcation,” which consists of the lateral talar dome, fibula, and distal lateral tibial plafond is visualized and examined (Fig 6). The trifurcation is a common site of both bony and soft tissue pathologies. The distal fascicle of the anterior inferior tibiofibular ligament (ATiFLdf) runs inferior and parallel to the ATiFL. This is an intra-articular structure that is in constant contact with the anterolateral talar dome and is often hypertrophied in the setting of anterolateral impingement. A hypertrophic ATiFLdf can snap against the lateral talar dome causing an attritional injury to the adjacent articular cartilage. Fastidious inspection must be performed by the operating surgeon to identify and treat any osteochondral lesions, which are often not captured on preoperative magnetic resonance imaging (MRI). Debulking of the hypertrophied ATiFLdf, first with a shaver followed by a biter, is recommended to reduce the damage to the articular cartilage. Synovitis is also commonly encountered at the trifurcation, particularly in the setting of chronic lateral ankle instability (CLAI), and the inflamed tissue must be resected with a shaver and biter. The arthroscope is then maneuvered down into the lateral gutter. The lateral gutter is located between the medial border of the fibular articulation and the lateral border of the talar articulation, extending from below the ATiFL to the ATFL. This region has a propensity to develop scar tissue, particularly in the setting of CLAI.

Fig 6.

Arthroscopic view of the trifurcation of the right ankle through the anterolateral portal. Visualized is the lateral talar dome, fibula, distal lateral tibial plafond, and hypertrophic distal fascicle of the anterior tibio-fibular ligament (ATiFLdf).

Finally, the arthroscope is reinserted into the anteromedial portal, the ankle is plantarflexed, and the arthroscope is manuevered through the medial tibial notch, to evaluate the central aspect of the talar dome and tibial plafond for any osteochondral lesions. First, the centromedial aspect of the talar dome is assessed, followed by gentle maneuvering of the arthroscope laterally to assess the central-central compartment and the centrolateral compartment. The ankle is then put through a full range of dorsiflexion and plantarflexion to evaluate for any remaining impingement.

In the setting of osteochondral lesions of the talus, arthroscopic delivery of orthobiologics such as extracellular matrix cartilage allograft can be performed when appropriate. This must be performed with no fluid in the joint. Although autologous orthobiologics such as platelet-rich plasma, concentrated bone marrow aspirate, and microfragmented adipose tissue can be delivered arthroscopically, it is our recommendation to inject these products at the end of the case through the anteromedial portal, with the arthroscope removed and without fluid in the joint.

When using a standard 2.7-mm or 4.0-mm arthroscope, the portal sites are closed with nylon sutures. When using a 1.9-mm arthroscope, the portal sites are closed with Steri-Strips (Steri-Strip, 3M, Saint Paul, MN). The patient is placed in a bulky, padded soft dressing bandage. Following arthroscopy with a 1.9-mm arthroscope, the patient can weight bear, as tolerated, immediately following the procedure.

Discussion

Anterior ankle arthroscopy is a powerful diagnostic and therapeutic modality for orthopedic foot and ankle surgeons.¹ A comprehensive diagnostic anterior ankle arthroscopy involves visualization of the anterior compartment, central compartment, posterior compartment, lateral compartment, lateral gutter, medial compartment, and medial gutter.⁴ This procedure is rarely performed as an isolated diagnostic tool, and typically involves some form of intervention, particularly with regard to resection of soft tissue and bony impinging structures.⁴

Pearls and pitfalls of the procedure are detailed in Table 1. First, iatrogenic neurological injury is a common complication of anterior ankle arthroscopy.⁷ The most frequently injured nerve is the SPN, followed by the saphenous nerve. Following identification of the SPN via the 4th toe flexion maneuver,⁶ the branches of the SPN must be marked out with a sterile marking pen. Furthermore, iatrogenic injury to the articular cartilage can occur during negligent insertion of the trocar into the joint.⁷ The ankle joint should be placed into dorsiflexion and the trocar should be inserted carefully in a posterolateral direction. Dense scar tissue is often found in the lateral gutter in patients with CLAI, which must be resected. The ATiFLdf is often hypertrophic in the setting of CLAI.⁸ This structure can snap against the lateral talar dome, precipitating the development of an osteochondral lesion.⁸ Thus, surgeons should meticulously evaluate the adjacent cartilage surrounding a hypertrophic ATiFLdf for any evidence of a chondral defect, which should be appropriately addressed. In addition, bony exostoses are often identified in the medial gutter, which also must be resected.

Table 1.

Pearls and Pitfalls of Anterior Ankle Arthroscopy

Pearls	Pitfalls
Identify and mark out the SPN via the 4th toe flexion sign.	Negligent portal placement can lead to iatrogenic cutaneous nerve injury.
Insert the trocar with the ankle in dorsiflexion to reduce the risk of iatrogenic articular cartilage injury.	Inadequate scar tissue resection can disrupt visualization.
Dense scar tissue is often found in the lateral gutter in patients with chronic lateral ankle instability and must be thoroughly resected.	Inadequate inspection of the adjacent cartilage surrounding a hypertrophic distal fascicle of the anterior tibiofibular ligament can lead to a missed osteochondral lesion of the talus.
Bony exostoses are often found in the medial gutter in patients with medial ankle pain and must be thoroughly resected.	Inadequate resection of bony exostoses of the tibial plafond can lead to persistent anterior impingement postoperatively.

The utilization of a 1.9-mm arthroscope is the preferred technique by the senior author for all patients undergoing an anterior ankle arthroscopic procedure, in lieu of a standard 2.7-mm or 4.0-mm arthroscope. The benefits of each arthroscope is detailed in Table 2. A 1.9-mm arthroscope produces less trauma to the soft tissue envelope, thus reducing the risk of hematoma formation and wound complications.⁹ Additionally, by preserving the soft tissue envelope via smaller incisions, the use of a 1.9-mm arthroscope facilitates rapid return to work, daily activities, and sport. Colasanti et al. evaluated clinical outcomes following the use of a 1.9-mm arthroscope in a cohort of patients with anterior ankle impingement.⁹ The authors found that patients returned to work at a mean time of 1.98 days and returned to sporting activities at a mean time of 3.9 weeks. Furthermore, the smaller diameter of the arthroscope and sheath reduces the risk of iatrogenic cartilage injury.⁴ Finally, no distraction is required when using a 1.9-mm arthroscope. Conversely, a standard 2.7-mm or 4.0-mm arthroscope can provide a higher flow and pressure, which may improve visualization of the joint. Additionally, larger shavers and burrs can be used during traditional arthroscopy to provide more aggressive resection of bony and soft tissue impinging structures, which can reduce the total operative time. Furthermore, because of current limitations in 1.9-mm arthroscopic technology, only a 0° arthroscope is available. However, 30°, 70°, and 120° 2.7-mm or 4.0-mm arthroscopes are available.

Table 2.

Benefits of the 1.9-mm Arthroscope and 2.7-mm or 4.0-mm Arthroscope

1.9-mm Arthroscope	2.7-mm or 4.0-mm Arthroscope
Distraction is not required to gain access to the ankle joint.	Greater flow can be provided to improve visualization.
Less trauma to the soft tissue envelope	Larger shavers and burrs can be used to provide more aggressive resection of bony and soft tissue impinging structures, which can reduce the operative time.
General anesthesia not required	Options for 30°, 70°, or 120° field of view
Immediate weight-bearing after the procedure
Faster time to return to work and activity
Reduced risk of articular cartilage injury

The steps of the procedure with either the 1.9-mm arthroscope or standard 2.7-mm or 4.0-mm arthroscope are almost identical, although, some slight modifications are necessary (Table 3). If the procedure is performed in the office setting, the patient does not warrant general anaesthesia and a lock anesthetic block of 1% lidocaine (3 mL), 0.5% bupivacaine (3 mL) and 1:100,000 lidocaine:epinephrine is injected into both the anteromedial and anterolateral portals 10 minutes before the beginning of the procedure and again immediately prior to commencing the procedure. If the procedure is performed in a formal operating theatre, the ankle joint is injected with 10 mL of sterile saline through the anteromedial portal. A slightly larger incision is warranted to accommodate the standard 2.7-mm or 4.0-mm arthroscope, followed by the use of a mosquito clamp prior to insertion of the trocar. Additionally, noninvasive traction of the ankle is often necessary to access the joint with a standard arthroscope. Furthermore, the portal sites are closed with nylon sutures when using a standard 2.7-mm or 4.0-mm arthroscope. When using a 1.9-mm arthroscope, the portal sites are closed with Steri-Strips (Steri-Strip, 3M, Saint Paul, MN). Patients are kept non–weight-bearing for 1 day following ankle arthroscopy using a standard 2.7-mm or 4.0-mm arthroscope, while patients bear weight, as tolerated, immediately following the arthroscopic procedure when using a 1.9-mm arthroscope.

Table 3.

Step-by-Step Instructions for Anterior Ankle Arthroscopy

1	Position the patient supine with the foot at the edge of the operation table. If using a standard 2.7-mm or 4.0-mm arthroscope, place the ankle into traction.
2	Identify and mark out the relevant bony landmarks with a sterile marking pen: distal tibia, lateral malleolus, anterior joint line, and talus.
3	Locate the anteromedial portal by placing the ankle into dorsiflexion, palpating the anterior tibial tendon and identifying the anterior joint line. The anteromedial portal should be positioned in the soft spot palpable just medial to the anterior tibial tendon in line with the joint line.
4	Locate the anterolateral portal lateral to the peroneus tertius tendon at the joint line level.
5	Inject 10 mL of sterile saline (or a 9-mL anesthetic cocktail of lidocaine, bupivacaine, and epinephrine in office setting) into the anteromedial portal. Joint distention is confirmed by outpouching of the anterolateral capsular wall and passive dorsiflexion of the ankle joint.
6	Make a 1-cm vertical skin incision at the anteromedial portal using a No. 11 blade followed by blunt dissection with a mosquito clamp through the subcutaneous tissue and capsule.
7	Insert the blunt trocar with the ankle in dorsiflexion to avoid cartilage injury, and then exchange the cannula for the arthroscope.
8	Set the initial fluid pressure to 30-40 mm Hg.
9	Use the anteromedial portal to initially assess the central and medial aspects of the ankle for scar tissue, osteochondral lesions, osteophytes, and synovitis.
10	Insert a spinal needle into the anterolateral portal under arthroscopic guidance and make a 1-cm vertical incision followed by blunt dissection with a mosquito clamp through the subcutaneous tissue and capsule.
11	Evaluate for any scar tissue, osteochondral lesions, osteophytes, and synovitis.
12	Use a shaver and burr to debride any scar tissue, osteophytes, or synovitis as necessary through the appropriate portal.
13	Inspect the medial gutter for fibrotic tissue, synovitis, or osteophytes, and debride with a shaver or biter.
14	Examine the lateral trifurcation area for hypertrophic distal fascicle of the anterior talofibular ligament or soft tissue impingement, resecting, as needed, with a shaver and biter.
15	Reassess the central talar dome and tibial plafond by switching portals and evaluate for osteochondral lesions.
16	Close the portal sites with sutures for a standard arthroscope or Steri-Strips for a smaller scope and apply a soft dressing bandage.

Disclosures

The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: J.G.K. is a consultant for In2Bones and Arthrex and receives financial support from the Ohnell Family Foundation, Mr. Winston Fisher, and Ms. Tatiana Rybak. All other authors (K.L., J.J.B., D.L., A.P.S., S.K., J.P., D.A.B.) declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Supplementary Data

Video 1

Walkthrough of surface anatomy, portal placement, and diagnostic evaluation.