Principles of Ankle Arthroscopy

Sterile Instruments/Equipment

Scope

· The 2.7-mm scope is most frequently used and is our preference.

The 2.7-mm scope is ideal for the ankle and allows anterior ankle arthroscopy as well as intra-articular evaluation. Furthermore, the 2.7-mm scope can be safely used for posterior ankle arthroscopy, subtalar arthroscopy, and tendoscopy.
Occasionally, the 1.9-mm scope is used in tight ankles and pediatric cases.
Some advocate the use of the 4.0-mm scope, which can be useful in anterior ankle arthroscopy but can pose a challenge for intra-articular evaluation. 1

· The 30-degree scope is adequate in most situations; however, a 70-degree

· scope is useful for viewing the posterior joint from anterior portals. Standard arthroscopy tower

· Monitor, light source, shaver motor, printer.

· We do not routinely use an arthroscopic pump for fluid inflow, instead we rely on gravity flow from 3-L saline bags.

· Intra-articular instruments (Fig. 61-1)

Commercially available sets designed for ankle arthroscopy incorporate smaller instruments to facilitate safe intra-articular work. These sets generally include the following:

· Probes

· Basket forceps in a variety of sizes and angles

· Useful for creating a “leading edge” in thickened soft tissue or scar tissue that can then be debrided with a motorized shaver.

· Also useful for the debridement of loose cartilage flaps.

· Graspers

· For removal of loose bodies or debris created from the debridement of osteochondral defects.

· Curettes in a variety of sizes and angles

· For debridement of osteochondral defects.

· Microfracture picks in a variety of angles Osteotomes

· Useful for removal of impinging osteophytes or for removal of cartilage in arthroscopic ankle arthrodesis.

· Motorized instruments

· Shavers: Generally a 2.5-mm full-radius shaver is used, although a 3.5-mm shaver can be used as needed.

Burrs: 3.0-5.0-mm round burr is useful for debridement of anterior osteophytes or debridement for arthroscopic ankle arthrodesis.

Figure 61-1 An example of a commercially available ankle/small joint

arthroscopy instrument set. A. A variety of graspers, basket punches, an osteotome, and curettes. B. A variety of open and closed curettes. C. Microfracture picks.

Positioning

Supine

Unlike most foot and ankle procedures, the patient)s heels are not positioned at the end of the table to accommodate the space required for the noninvasive distraction device. Another option is to use a table rail extender.

Thigh holder

Places the hip in approximately 45 degrees of flexion while the knee is in ~90 degrees of flexion. The proper position allows the heel to gently touch the OR table. We are careful to position the thigh holder proximal to the popliteal fossa to decrease pressure on the vessels in the posterior knee (Fig. 61-2).

Figure 61-2 Properly positioned patient. Note the location of the thigh holder slightly proximal to the popliteal fossa and the foot gently resting on the OR table.

Noninvasive distractor (Fig. 61-3)

Noninvasive ankle distraction improves access to the ankle joint.

It is important, however, to limit the time distraction is used to decrease both postoperative neurapraxia and compression of the terminal nerve branches at the midfoot. 2 , 3

Joint distraction can decrease access to the anterior compartment and can be

removed during debridement deep to the anterior capsule. 1

As demonstrated in Figure 61-4, the distractor can pull the talus anteriorly and paradoxically decrease access to the ankle joint in unstable ankles. We have found that unstable ankles can often be approached without the use of a distractor

Figure 61-3 The foot properly placed into a sterile noninvasive distraction device. Note that the clamp is positioned at the level of the toes.

Figure 61-4 A. The talus pulled anteriorly (red arrow) by the non invasive distractor in the setting of instability. This can decrease access to the joint. B. The talus in an improved position out of distraction facilitating improved access to the ankle joint.

Tourniquet

A thigh tourniquet can be used at the discretion of the surgeon.

Surgical Anatomy

Portal placement (Fig. 61-5)

Proper placement is crucial given the constrained nature of the ankle joint. The joint is insufflated with 10-15 cc of sterile saline to confirm portals. The needle should easily fall into the joint medially and result in a bulge where the lateral portal will be placed.

Portals are created using the “nick and spread” technique to prevent injury to the saphenous nerve and vein medially and the superficial peroneal nerve (SPN) laterally.

The anterior portals are used interchangeably for viewing and working.

Typically, it is easiest to use the portal nearest the pathology as the working portal.

Medial portal

Established first and used for the diagnostic portion of the case. Placed at the joint line, medial to the anterior tibial tendon.

The correct location is typically 1 cm proximal to the tip of the medial malleolus and is characterized by a palpable soft spot.

Lateral portal

Lateral to the extensor digitorum longus tendons or, alternatively, lateral to the peroneus tertius tendon.

Localized with a spinal needle under direct visualization (Fig. 61-6).

Figure 61-5 A-C.Surface anatomy aids in the establishment of

proper portal placement.

MM, medial malleolus; TA, tibialis anterior; SaN, saphenous nerve; MP, medial portal; ICSPN, intermediate cutaneous branch of the superficial peroneal nerve; LP, lateral portal; F, Fibula.

Figure 61-6 Needle visualization of lateral portal placement ensures a functional portal for intra-articular instruments.

Careful attention should be paid to the intermediate dorsal cutaneous branch of the SPN, which lies very near a properly placed portal.

The nerve can be identified using the fourth toe flexion sign. 4

Intra-articular anatomy

A routine should be developed to systematically evaluate the ankle joint. Listed below are the structures visualized during ankle arthroscopy.

It is often helpful to debride the anterior gutter before a thorough diagnostic arthroscopy.

Medial ankle examination (Fig. 61-7)

Deltoid ligament—impinging ossicles at the tip of the medial malleolus

Medial gutter—loose bodies

Medial shoulder of the talus—osteochondral lesions

Figure 61-7 Intra-articular examination of medial ankle. DL, deltoid ligament; MM, medial malleolus.

Anterior ankle examination

Anterior gutter—synovial hypertrophy and loose bodies

This area must be carefully debrided to prevent injury to the deep peroneal nerve and anterior tibial artery. 5 It can be helpful to remove traction to allow the neurovascular bundle to relax away from the motorized shaver (Fig. 61-8).

Figure 61-8 A. Traction can be released to allow the anterior capsule to relax. B. The neurovascular bundle is drawn closer to the joint while in traction.

Inflamed synovial tissue can bleed and obscure the view if overaggressive debridement is performed.

Impinging osteophytes on talar neck and distal tibial plafond (Fig. 61-9)

We move the ankle through dorsiflexion and plantar flexion when evaluating for impingement.

Figure 61-9 A. Anterior osteophytes on the distal tibia. B. Following debridement.

Lateral ankle examination (Fig. 61-10) Lateral gutter—loose bodies

Lateral shoulder of the talus—osteochondral lesions

“Trifurcation”—the area where the tibial plafond, distal fibula, and talus articulate (Fig. 61-11)

Inability to visualize the trifurcation suggests the presence of a Bassett lesion or synovial hypertrophy and should be debrided until this is visible. 6

A probe can be placed in this area to assess

competence of the syndesmosis.

Figure 61-10 Intra-articular examination of the lateral ankle. S, syndesmosis; AITFL, anterior inferior tibiofibular ligament.

Figure 61-11 A probe can placed into the trifurcation to stress the syndesmosis (not pictured). S, Intra-articular syndesmosis.

Anterior inferior tibiofibular ligament Posterior ankle examination

Posterior inferior tibiofibular ligament and transverse tibiofibular ligament (Fig. 61-12)

Figure 61-12 Posterior structures of the ankle as viewed through an anterior portal. PITFL, posterior inferior talofibular ligament; TTFL, transverse tibiofibular ligament.

Extensor hallucis longus tendon

Loose bodies can “hide” in the posterior ankle because of the posterior slope of the joint. A gentle squeeze anterior to the Achilles tendon can decrease space in the posterior ankle and bring loose bodies into the visual field of the scope.

References

van Dijk NC, van Bergen CJ. Advancements in ankle arthroscopy. J Am Acad Orthop Surg. 2008;16:635-646.
Dowdy PA, Watson BV, Amendola A. Noninvasive ankle distraction: relationship between force, magnitude of distraction, and nerve conduction abnormalities. Arthroscopy. 1996;12:64-69.
Young BH, Flanigan RM, DiGiovanni BF. Complications of ankle arthroscopy utilizing a contemporary noninvasive distraction technique. J Bone Joint Surg Am. 2001;93:963-968.
Stephens MM, Kelly PM. Fourth toe flexion sign: a new clinical sign for identification of the superficial peronea nerve. Foot Ankle Int. 2000;21:800-863.
Darwish A, Ehsan O, Marynissen H, et al. Pseudoaneurysm of the anterior tibial artery after ankle arthroscopy Arthroscopy. 2004;20:e63-e64.
Bassett FH, Gates HS, Billys JB, et al. Talar impingement by the anteroinferior tibiofibular ligament. J Bone Joint Surg Am. 1990;72:55-59.