Diagnostic Assessment

Before planning operative management, an accurate and thorough preoperative assessment is required to come to a diagnosis or at least provide a limited differential diagnosis. The location and nature of the ankle pathology determine the appropriate position, distraction method, and instrumentation to be used to perform the operative procedure most effectively. A thorough history, physical examination, and basic imaging should be used to make the diagnosis.

If doubt remains after this assessment, more advanced imaging and possibly diagnostic injections may assist in determining the nature and location of the pathology¹. Liberal use of preoperative diagnostic injections can pinpoint symptomatic pathology, which can aid in decision making for the operating room setup. A patient with anterior and posterior ankle pathology may have complete resolution of symptoms with an anterior ankle injection, obviating the need for posterior access and vice versa. For lesions on the talar dome, it is essential to assess the extent of ankle plantar flexion to determine whether an anterior approach alone is sufficient to access the lesion.

Operating Room Setup

The operating room must be large enough to accommodate all of the necessary personnel and equipment. Personnel usually include a surgeon and an assistant, a scrub nurse, a circulating nurse, and an anesthetist. The operating room must be large enough to allow each of these individuals to move around the room without contaminating the surgical field or instrumentation. The room must also contain an operating table, anesthesia equipment, an arthroscopy tower, an equipment table, and one or two Mayo stands.

Some surgeons may choose to use an arthroscopic pump. Occasionally, fluoroscopy is necessary, which requires a significant amount of space. The arthroscopy tower should be mobile to optimize its position for each case. The components of the arthroscopy tower are listed in Box 3-1 and shown in Figure 3-1. The equipment table is used for therapeutic instruments. The instruments routinely used during the diagnostic arthroscopy (e.g., scalpels, 18-gauge needle, trocars, cannulas, probes) are placed on a Mayo stand for easy accessibility (Fig. 3-2). Backup equipment should be readily available in the event that additional instrumentation is required.

FIGURE 3-1 The components of the arthroscopy tower.

FIGURE 3-2 The instruments routinely used during diagnostic arthroscopy include scalpels, an 18-gauge needle, trocars, cannulas, and probes.

Anesthesia and Positioning

Ankle arthroscopy may be conducted under general, spinal, or local anesthesia. Use of general or spinal anesthesia is preferable, because both facilitate tourniquet use, if needed, and muscle relaxation that can facilitate ankle distraction. However, local anesthesia remains an option if required because of patient characteristics.

The most appropriate patient positioning for ankle arthroscopy is a matter of the surgeon’s preference. Supine and lateral positions are well described. There are two common variations of the supine position (Fig. 3-3). In the first, the patient is placed supine with the operative leg placed in a knee holder. The knee is placed just distal to the break in the operating room table, and the foot of the bed is lowered to allow the lower leg to rest unsupported.² A second option is to place the patient supine and use a well-padded thigh holder to position the operative leg such that the hip is flexed 45 degrees and the leg is allowed to hang, providing access to the ankle.³ The lateral position has been described by Parisien (Fig. 3-4).⁴ It involves placing the patient in a 45-degree lateral position with the operative side up. A platform (box or sheets) is placed underneath the operative leg to elevate it above the nonoperative leg. The hip is externally rotated to access the anterior aspect of the ankle. The leg can be returned to neutral position for access to the lateral or posterior aspects of the ankle. Harbach⁵ modified the lateral position with the addition of a thigh holder, which allows the ankle to hang similar to the supine position described previously. Although all previously described positions may be used for subtalar arthroscopy, the most common approaches are from the lateral position or posteriorly with the patient in the prone position.

FIGURE 3-3 A and B, The two common variations of the supine position.

FIGURE 3-4 A and B, The lateral position involves placing the patient in a 45-degree lateral position with the operative side up. A platform (box or sheets) is placed underneath the operative leg to elevate it above the nonoperative leg. The hip is externally rotated to access the anterior aspect of the ankle.

Distraction

Interest in ankle arthroscopy resumed in the 1970s with the advent of smaller arthroscopes. Unfortunately, the smaller equipment provides less visibility and is susceptible to breaking. In the 1980s, ankle distraction was added to the procedure as a means of improving visibility and accessibility. Distraction can be classified as invasive or noninvasive. The noninvasive technique is further classified as controlled, semicontrolled, and uncontrolled traction.

Although several methods of invasive distraction exist, all involve drilling traction pins or wires into bone. The well-described Guhl technique uses two -inch threaded Steinmann pins and an external distraction device containing a strain gauge and a pivoting distal end.⁶ The proximal pin is placed into the distal tibia approximately 3 to 5 cm proximal to the ankle joint and 1 cm posterior to the anterior tibial crest. The distal pin is placed into the calcaneus 2 to 2.5 cm anterior to its posterior border and just beneath the peroneal tendons. Both pins are placed in unicortical fashion from lateral to medial aspects. The calcaneus pin should be aimed 20 degrees distally. Many other techniques have been described, including medial distraction with the distal pin in the talus⁷; medial and lateral distraction⁸; a single, smooth, 0.045-mm wire passed through the sinus tarsi and attached to weights⁹; and a single pin through the calcaneus attached to a fracture table.¹⁰

Noninvasive distraction techniques have largely replaced the need for invasive distraction. Uncontrolled techniques are simple to execute, but it is difficult to maintain a consistent amount of distraction. Gravity distraction achieved by hanging the leg with the knee flexed 90 degrees is the most basic form of uncontrolled distraction. Manual traction using the surgeon’s free hand or an assistant’s hand to grasp the foot and pull longitudinally is another method. Only small amounts of distraction are possible using these techniques.

Yates and Grana¹¹ described a means of applying semicontrolled distraction. A small loop is tied in the center of a Kerlix gauze roll. The free ends of the roll are wrapped around the ankle and then passed through the loop. The ends are tied together and then placed underneath the surgeon’s foot. Traction can be added by stepping (similar to stepping on a gas pedal) on the loop underfoot (Fig. 3-5A). Cameron¹² modified this technique by passing the loop behind the surgeon’s back, rather than underfoot (see Fig. 3-5B). To apply distraction, the surgeon leans backward.

FIGURE 3-5 To achieve semicontrolled distraction, a small loop is tied in the center of a Kerlix gauze roll. The free ends of the roll are wrapped around the ankle and then passed through the loop. The ends are tied together and placed underneath the surgeon’s foot. A, Traction can be added by stepping (similar to stepping on a gas pedal) on the loop underfoot. B, The technique can be modified by passing the loop behind the surgeon’s back, rather than underfoot.

Takao and colleagues¹³ use a different bandage configuration to produce equal distraction anteriorly and posteriorly (see Fig. 3-5B). These methods of distraction require little equipment and are very cost effective. However, it is difficult to maintain consistent traction, and some operators may find the multitasking of operating and controlling distraction somewhat onerous. Another disadvantage is that placing the Kerlix roll underfoot or behind the back may compromise the sterility of the procedure.

Through controlled methods, specific amounts of distraction can be applied and maintained with ease. The most common means of controlled distraction is to use one of the many commercially available, sterile foot straps and attach the sling to a tensioning device (Fig. 3-6). This system allows the surgeon to keep both hands free. The foot may be placed into various degrees of plantar flexion by modifying the position of the straps. In many of these systems, the entire apparatus is sterile, which avoids contamination concerns that exist with the semicontrolled techniques. Waseem and coworkers¹⁴ routinely use the foot strap technique. However, for tight arthritic ankles, they advocate using a clamp from the AO pinless fixator applied to the patient’s heel and attached to a traction setup. Aydin¹⁵ described a distraction technique in which a kyphoplasty balloon is inserted through an arthroscopic portal and is inflated to distract the joint. The entire joint can be visualized, but it is necessary to move the balloon to different positions within the ankle. The controlled techniques are more costly than the uncontrolled and semicontrolled methods.

FIGURE 3-6 The most common means of controlled distraction uses one of the many commercially available sterile foot straps and attaches the sling to a tensioning device.

The acceptable amount of weight and duration of traction depend on the technique used. Guhl⁶ recommends 7 to 8 mm of distraction with his invasive technique.

Distraction should not be increased after slight bending of the pins has been noticed. The distraction force required usually is 30 to 50 pounds, and it should not continue longer than 45 to 60 minutes to avoid excessive stretching of the ligament. Using cadaveric ankles, Albert and associates¹⁶ found that complications were avoided if less than 135 N of distraction force was used. Beyond 135 N, they encountered pin bending and bony destruction of the calcaneus. Takao and colleagues¹³ compared the bandage distraction technique described by Yates and Grana¹¹ with their own and found better distraction (90% anterior and posterior opening) using the Takao technique with 8 kg of force. They recommended a maximum of 8 to10 kg of force be used because the test subjects felt pain at greater than 10 kg of force. Dowdy and coworkers¹⁷ advise that foot straps be used for less than 1 hour at a maximum distractive force of 30 pounds because the subjects in their study developed reversible nerve conduction changes above this threshold.

Invasive distraction is now rarely used. Although it provides greater distraction,¹⁷ the risk of complications is also much greater. Box 3-2 lists the potential complications of invasive and noninvasive distraction. Despite the potential for complications with invasive distraction, studies have not shown a significant difference in morbidity for invasive or noninvasive distraction. Ferkel and associates³ found no difference in complication rates between invasive and noninvasive distraction. Guhl⁶ reported a 10% complication rate in his series using invasive distraction, but ultimately, only three complications were related to distraction and only one (i.e., scarred nodule adjacent to the peroneal sheath) resulted in patient morbidity. Tibial stress fractures through the pin site have been reported.^20,21 Stone and Guhl²¹ recommend avoidance of stressful activities for 6 to 12 weeks postoperatively after the use of invasive distraction.

The contraindications to distraction are found in Box 3-3. Several investigators have found that distraction is rarely necessary.^1,22,23 The need for distraction can be minimized or eliminated by using smaller arthroscopic instruments or by a more accurate preoperative diagnosis. Distraction may make some portions of ankle arthroscopy more difficult. The space available deep to the anterior capsule is decreased with traction.¹ Because most therapeutic ankle arthroscopy procedures occur within the anterior compartment, many surgeons find distraction unnecessary. Distraction usually is not employed in subtalar arthroscopy.

Preferred Method: Anesthesia, Position, and Distraction

Most ankle arthroscopies at our center are performed under general anesthesia. Spinal anesthesia is used if there is a contraindication to general anesthesia.

Ankle arthroscopy with local anesthesia alone has been used only in rare circumstances. We prefer to position the patient supine with the hip flexed 45 degrees and the patient’s thigh supported by a well-padded thigh holder (Fig. 3-7A). The foot is attached to a sterile foot strap, which is fixed to a sterile tensioning device (see Fig. 3-7B). Although the posterolateral portal is accessible, we prefer to use this position for anterior ankle arthroscopy alone. Preoperatively, we determine the need or potential need for posterior ankle arthroscopy. Patients who have posterior ankle pathology are placed in the prone position after an anterior ankle arthroscopy is performed or as a solitary procedure (see Chapter 7). Two separate setups are used for the rare patient who requires anterior and posterior ankle arthroscopies rather than trying to accomplish the anterior and posterior arthroscopies in the supine or lateral position. Noninvasive foot strap distraction is routinely used at 20 to 30 pounds of distraction to facilitate joint visualization. We decrease or remove the traction if increased space is needed for procedures in the anterior compartment beneath the anterior capsule.

FIGURE 3-7 Ankle arthroscopy with local anesthetic alone. A, The patient is positioned supine with the hip flexed 45 degrees and the thigh supported by a well-padded thigh holder. B, The foot is attached to a sterile foot strap, which is fixed to a sterile tensioning device.

Instrumentation

Arthroscopes

Arthroscopes are available in a variety of lengths, diameters, and lens angles. The most commonly used arthroscopes for ankle arthroscopy are the 4.0-mm, 30-degree arthroscope and the 2.7-mm, 30-degree arthroscope (Fig. 3-8). Occasionally a 70-degree arthroscope may be beneficial to improve visualization of the posterior aspect of the joint. We have found the 4.0-mm, 30-degree arthroscope is effective for most anterior ankle arthroscopies. This arthroscope has the advantage of a greater field of view and increased intra-articular flow compared with the 2.7-mm arthroscope. Subtalar arthroscopy is better and more safely performed with the 2.7-mm arthroscope because of increased joint congruency.

FIGURE 3-8 The most commonly used arthroscopes for ankle arthroscopy are the 4.0-mm, 30-degree arthroscope and the 2.7-mm, 30-degree arthroscope.

Handheld Instruments

Ankle arthroscopy instruments usually are smaller in length and diameter than those used in the knee and shoulder. Their decreased size improves accessibility to all areas of the ankle but increases the likelihood of instrument breakage.

Probes.

The probe is the most basic of instruments, and it the most frequently used. It acts as an extension of the surgeon’s hand, allowing mobilization and palpation of structures. It is also a useful tool for measuring the size of chondral lesions.

Calibrated probes can increase the accuracy of measurement. Calibrations are preferably marked in ink rather than scored into the metal, because scoring creates stress risers that can lead to instrument breakage.¹⁸ Probes come in various curvatures, lengths, and diameters (Fig. 3-9). Articulating probes are commercially available (Arthrex) and allow the probe to enter the joint straight and then articulate and lock at 90 degrees. Shorter probes are more useful in ankle arthroscopy because they have a shorter lever arm and are easier to control.

FIGURE 3-9 Probes come in various curvatures, lengths, and diameters.

Basket Forceps.

Basket forceps (i.e., punches) are used for débridement. Wide tips are available for greater efficiency, and narrow tips are available for improved control. A variety of angulations exist to facilitate maneuverability (Fig. 3-10).

FIGURE 3-10 A variety of angulations exist to facilitate maneuverability of basket forceps.

Curettes.

Curettes are available in ring or cup formation. Ring curettes are often helpful for débriding osteochondritis dissecans lesions. Straight and angled versions are available (Fig. 3-11).

FIGURE 3-11 Ring curettes are often helpful for débriding OCD lesions. Straight and angled versions are available.

Rasps.

Small rasps are occasionally useful for smoothing bony edges after débridement.

Graspers.

Graspers are used to remove loose bodies or broken instruments from the joint. They are available in straight or curved shafts and in a variety of tip angles (Fig. 3-12).

FIGURE 3-12 Graspers are used to remove loose bodies or broken instruments from the joint. They are available in straight or curved shafts and in a variety of tip angles.

Osteotomes.

Small osteotomes are useful for osteophyte removal (Fig. 3-13).

FIGURE 3-13 Small osteotomes are useful for osteophyte removal.

Aiming Devices.

Aiming devices are useful for accurate drilling when a transosseous approach is required. The aiming devices used for cruciate reconstruction in the knee are usually sufficient, but small joint devices can assist in tight joints.

Awls.

Awls are useful for microfracture of chondral lesions. A variety of tip angulations exist to facilitate appropriate access within the confined space of the ankle joint (Fig. 3-14).

FIGURE 3-14 Awls are useful for microfracture of chondral lesions. A variety of tip angulations exist to facilitate appropriate access within the confined space of the ankle joint.

Motorized Instruments

Motorized instruments frequently enable the surgeon to execute the procedure more efficiently. Shavers and burrs of various sizes, angles, and degrees of aggressiveness are available (Fig. 3-15). The larger instruments enable the procedure to be performed quickly; however, the amount of joint space available ultimately determines the size that is used. Less aggressive instruments should be used near vulnerable structures or when learning a new procedure. Conceptually, the instruments are constructed similarly, with a rotating blade or burr housed in a sheath that is attached to suction. The surgeon is able to adjust the direction of rotation and the amount of suction.

FIGURE 3-15 Motorized instruments often enable the surgeon to execute the procedure more efficiently. Shavers and burrs of various sizes, angles, and degrees of aggressiveness are available.