Ankle Arthroscopy: Diagnostics, Débridement, and Removal of Loose Bodies

Carol Frey, MD

Dr. Frey or an immediate family member serves as a paid consultant to or is an employee of Ossur and Pacira Pharmaceutials.

PATIENT SELECTION

Indications

The most common reasons for ankle arthroscopy are given in Table 1. Extensive débridement, removal of anterior ankle impingement, and excision of osteochondral defects are the most common indications for ankle arthroscopy. Anterior impingement is generally caused by soft-tissue or bone obstruction. Anterior tibial spurs are a common source of anterior impingement. Anterior impingement and spurs are common in athletes, especially those who dorsiflex their ankles with force, such as runners, dancers, and football players. An incidence of 45% was reported in football players and 59% in dancers.¹ Physical examination will reveal anterior ankle pain, exacerbated by forced dorsiflexion of the ankle. The pain is usually localized along the anterior ridge of the tibia.

Although the cause of anterior spurs is unknown, they most likely result from repetitive minor injuries rather than one traumatic episode. They may be part of an early degenerative process in the ankle. Although anterior spurs are usually asymptomatic, surgery may be required when they are painful. The procedure is recommended for patients who have persistent anterior ankle pain and loss of dorsiflexion after nonsurgical treatment has failed. Anterior spurs on the tibia and talus can be removed with the arthroscope.

TABLE 1 Conditions That Can Be Treated Arthroscopically

Diagnosis/Indications	Percentage of Cases That Can Be Treated Arthroscopically
Ankle arthritis	25
Loose body	90
Synovectomy	90
Acute infection	80
Lateral impingement	95-100
Osteochondral defects	95-100
Anterior osteophytes	90-95
Stabilization	25
Ankle arthrodesis	50
Foreign body	90-100

Anterolateral soft-tissue impingement, another cause of anterior ankle impingement, occurs mainly in three sites: the superior portion of the anterior inferior tibiofibular ligament (AITFL), the distal portion of the AITFL, and along the anterior talofibular ligament (ATFL) and the lateral gutter near the area of the lateral talar dome. Physical examination will again reveal anterior ankle pain, made worse by forced dorsiflexion of the ankle. The pain is usually present in the lateral gutter area of the ankle. Anterolateral impingement of the ankle should be considered in a patient with chronic anterolateral pain after an inversion injury, regardless of the stability of the ankle joint. Anterior soft-tissue impingement lesions may be removed with the arthroscope.¹^,²^,³^,⁴^,⁵^,⁶

A recent review of over 15,000 ankle arthroscopy procedures revealed that there was a significant increase in the number of ankle arthroscopies performed from 2007 to 2011, outpacing shoulder, elbow, and knee arthroscopy. The procedure was performed more often in female patients and in patients younger than 50 years. Concomitant ankle arthroscopy and lateral ligament stabilization procedures increased significantly.⁷

PREOPERATIVE IMAGING

Radiographs obtained in the early stages of anterior bone impingement may be negative. A lateral radiograph may reveal the spur. A forced dorsiflexion lateral radiograph may confirm anterior impingement. The talus may show secondary dorsal spur formation (Figure 1), and loose bodies may be seen.

MRI will often show cartilage thinning and soft-tissue reaction, in addition to an osteophyte. Although not indicated in all cases of anterior impingement of the ankle, MRI can be useful in cases where additional pathology in the ankle or subtalar joint must be evaluated. In the
diagnosis of anterior soft-tissue impingement, MRI has been reported to be approximately 79% accurate and 84% sensitive.⁴ As noted previously, anterolateral soft-tissue impingement occurs mainly in three sites: the superior portion of the AITFL; the distal portion of the AITFL, which may have a separate fascicle involved; and along the ATFL and the lateral gutter near the area of the lateral talar dome. All these areas can be visualized on MRI. Sagittal T1-weighted and STIR (short tau inversion recovery) images are particularly useful. Displacement of subcutaneous fat by fluid (effusion) or soft tissue can be seen using these sequences (Figure 2).

FIGURE 1 A lateral radiograph of the ankle reveals an anterior tibial spur.

Ultrasonography has been found to be accurate in detecting synovial lesions in the anterior lateral gutter, demonstrating ligament injuries, and differentiating soft-tissue from bone impingement. Ultrasonography will not show osteochondral lesions or stress fracture. It may also overlook some loose bodies.⁸

FIGURE 2 Axial T1-weighted (A) and fast spin-echo T2-weighted (B) MRIs of the ankle of a 39-year-old man with anterolateral ankle impingement. Thickening and scarring of the distal fascicle is evident in these images taken 3 mo after an anterior inferior tibiofibular ligament injury.

VIDEO 84.1 Subtalar Arthroscopy. Richard D. Ferkel, MD (9 min)

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Video 84.1

PROCEDURE

Room Setup/Patient Positioning

Ankle arthroscopy is usually performed as an outpatient procedure. The use of spinal anesthesia is preferred, although general anesthesia can be administered. In carefully selected patients, ankle block anesthesia using 1% lidocaine is appropriate, but this is rarely used.

The patient is placed in the supine position on the operating room table with a well-padded tourniquet on the proximal thigh. The limb is prepared and draped with a standard lower limb extremity set, and a bolster is placed under the thigh to elevate the extremity off the table. A well-padded thigh holder can also be used. The limb is exsanguinated, and the tourniquet is inflated. The well-padded straps or stirrups of a noninvasive distraction device are then applied (Figure 3).

Noninvasive distraction is recommended for this procedure to allow for better access to the spur and to prevent cartilage damage. Care must be taken not to excessively distract the joint because this will pull the synovium and capsule tight up against the spur and make visualization and access difficult.

Special Instruments/Equipment

The following instruments and equipment should be on hand: a No. 11 scalpel; a straight mosquito clamp; a 20-mL syringe; an 18-gauge spinal needle; a lightweight camera with compatible light source; a video/TV monitor; a blunt trochar/cannula; a thigh holder/large sterile bump; a 2.9-mm arthroscope, with 30° and 70° angulations; small curets; a rasp; small grasping forceps, probes, and biters; a 2.9- to 3.5-mm arthroscopic
full-radius shaver; an acromionizer (burr); a radiofrequency wand; a high-flow infusion pump; and a noninvasive distractor.

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