Jorge I. Acevedo and Peter Mangone
DEFINITION
Arthroscopy of the ankle has become an invaluable tool for evaluating and treating pathology in the ankle joint.
Arthroscopy allows a minimally invasive approach to the structures of the ankle with a magnified view.
Detailed knowledge of the anatomy surrounding the ankle joint as well as the different structural variations is key to avoiding complications.
ANATOMY
The anteromedial portal is located medial to the tibialis anterior tendon at the level of the ankle joint (FIG 1). Care should be taken to avoid injury to the long saphenous vein and nerve usually located medial to the portal.
The anterolateral portal lies on the anterior joint line just lateral to the peroneus tertius tendon or alternatively lateral to the extensor digitorum longus tendons (FIG 1). The intermediate cutaneous branch of the superficial peroneal nerve lies in close proximity to this portal.
Posteromedial and posterolateral coaxial portals lie parallel to the bimalleolar axis (FIG 2).
The posterolateral coaxial portal (FIG 3) is located immediately posterior to the peroneus longus tendon, and the posteromedial coaxial portal (FIG 4) ideally lies between the posterior colliculus (of the medial malleolus) and the posterior tibial tendon. (Placement between the flexor digitorum longus and the posterior tibial tendon is also acceptable.)
FIG 1 • Anatomic landmarks for anterior ankle arthroscopy. 1, anteromedial portal site; 2, anterolateral portal site.
The sural nerve is located an average of 6.6 mm from this posterolateral portal, while the posterior tibial nerve is found an average of 5.7 mm from the posteromedial portal.
DIFFERENTIAL DIAGNOSIS
Anterior ankle impingement
Ankle arthritis or frozen ankle
Osteochondral tibial or talar defects
Lateral ankle instability
Ankle fractures
Recalcitrant ankle synovitis (often seen in patients with systemic inflammatory disease)
NONOPERATIVE MANAGEMENT
In general, conservative treatment will include a trial with activity modification, immobilization with a brace, and nonsteroidal anti-inflammatories.
FIG 2 • Coaxial portal cross-sectional anatomy.
FIG 3 • Coaxial posterolateral portal anatomy.
FIG 4 • Coaxial posteromedial portal anatomy.
Physical therapy using modality treatment, range-of-motion exercises, neuromuscular coordination training (eg, balance board), and strengthening of the secondary or dynamic stabilizing muscles surrounding the ankle is a useful adjunct to most conditions.
SURGICAL MANAGEMENT
Preoperative Planning
Imaging studies are reviewed to determine ideal portals to be used.
Standard anteromedial and anterolateral portals are sufficient to access the anterior and central tibiotalar pathology.
Posterior portals are considered when drilling posterior talar lesions or when it is necessary to address pathology (eg, synovitis, loose bodies) within the posterior capsule.
A preoperative popliteal block is placed by anesthesia. Over the past 5 years, we have been able to perform 75% of ankle arthroscopies with regional anesthesia and light sedation.
An examination under anesthesia including anterior drawer as well as a talar tilt test should be performed before positioning.
Positioning
The patient is placed on a regular operating table with a well-padded tourniquet on the proximal thigh.
The supine position with a towel roll placed underneath the ankle is used when only anterior portals are necessary. In this situation the tourniquet may be placed on the proximal calf.
If access to posterior portals is likely, then we lower the leg extension of the bed and use a standard arthroscopy knee holder (FIG 5). This restricts thigh motion but allows free leg motion and access to the posterior hindfoot (FIG 6). The contralateral leg is placed in a well-padded holder or pillow (FIG 7).
Alternatively a noninvasive ankle distractor is used.
Approach
Currently the standard working approaches include the anteromedial and anterolateral portals.
Auxiliary anterior portals (such as the antero-central) should be used with caution because of the high incidence of neurovascular injury.
The standard posteromedial and posterolateral portals should also be used with extreme caution due to the close proximity of neurovascular structures (FIG 8).
FIG 5 • Leg holder position for posterior portal access.
FIG 6 • Bed position for posterior portal access.
FIG 7 • Position of operative leg and padded contralateral limb.
FIG 8 • Conventional posterior portal cross-sectional anatomy.
We prefer to use posterior coaxial portals parallel to the bimalleolar axis when addressing the posterior ankle joint.
Although the standard 4-mm arthroscope may be used, we prefer to use the 2.7-mm arthroscopic instruments, which facilitate access and simplify the approach.
Instruments usually include 2.5-mm shaver, 3.5-mm shaver, thermal ablation device (this is especially helpful for synovectomy and débridement of the joint; however, care must be taken to avoid articular cartilage damage), and small arthroscopic biter and grabber devices.
TECHNIQUES
ANTERIOR PORTAL PLACEMENT
The operative leg is identified and marked preoperatively.
The patient is placed supine on the operating table.
Inject the ankle with 10 cc of sterile saline via the anteromedial ankle. This step also allows identification of the correct orientation and location for the anteromedial arthroscopy portal.
Make a 5-mm longitudinal skin incision and spread the subcutaneous tissue down to and then through the capsule with a small hemostat. A small gush of fluid confirms the intra-articular location.
Use the blunt-tip trocar with the arthroscopic cannula to enter the joint. Insert the arthroscope and start the water flow. Place the water pressure about 5 mm Hg above the systolic pressure if possible (no higher than a pressure of 120 mm Hg). This significantly reduces bleeding, which often obscures the view.
Unless there is severe arthrofibrotic tissue in the anterior ankle, the anterolateral ankle is easily visualized upon introducing the arthroscope (TECH FIG 1).
Introduce an 18-gauge needle from the anterolateral portal location. This serves two purposes: (1) it allows for water flow through the needle, allowing for better visualization and (2) it identifies the correct location of the portal incision in order to access the joint properly.
Inspect the joint. Distraction allows for much greater joint inspection than otherwise would be possible.
Make the anterolateral portal in a similar fashion to the anteromedial portal.
Using both portals, various arthroscopic instruments are used to address the individual patient's pathology.
The addition of an anteromedial inferior portal is very helpful when dealing with synovitis near the deltoid insertion. This is performed by visualizing the medial gutter with the arthroscope through the anteromedial portal. An 18-gauge needle is introduced under arthroscopic visualization into the inferior medial gutter (usually about 10 mm inferior to the normal anteromedial portal location). Once the needle is confirmed to be in the proper position, a new portal is then made as described earlier. This portal in combination with the conventional anteromedial portal can be used to first inspect and then débride the far inferomedial ankle joint and deltoid insertion.
TECH FIG 1 • View of (A) anterolateral and (B) posterolateral gutter using simple distraction with towel roll underneath ankle.
POSTERIOR COAXIAL PORTALS
With the arthroscope and inflow in the anterolateral portal, make the posterolateral portal with a small, vertical skin incision immediately posterior to the peroneal tendon sheath and 1.5 cm proximal to the tip of the fibula (TECH FIG 2).
While holding the ankle in neutral dorsiflexion, insert the arthroscopic sheath and blunt trocar anterior and slightly inferior on a plane parallel to the bimalleolar axis. Confirm intracapsular placement by briefly inserting the arthroscope.
Insert a long switching rod through the cannula and direct it toward the medial malleolus. Use the rod to palpate the posterior colliculus and penetrate just anterior to the posterior tibial tendon (TECH FIG 3).
Tent and incise the skin over the posteromedial ankle. Subsequently, pass a second cannula over the switching stick into the posterior ankle recess.
Alternatively, the medial portal can be made directly using a small, vertical skin incision posterior to the medial malleolus (posterior colliculus). The arthroscopic sheath and blunt trocar are inserted anterior and slightly inferior on a plane parallel to the bimalleolar axis. Intracapsular placement is confirmed by briefly inserting the arthroscope (TECH FIGS 4 AND 5).
TECH FIG 2 • Lateral coaxial portal: clinical photograph with anatomic correlation.
TECH FIG 3 • Medial coaxial portal: clinical photograph with anatomic correlation.
For synovectomies or posteromedial osteochondral lesions, the arthroscope is placed in the posterolateral cannula while the posteromedial cannula is used as the working portal.
TECH FIG 4 • Medial coaxial portal: clinical photograph. (Courtesy of M.T. Busch, MD.)
TECH FIG 5 • Arthroscopic view of instrumentation through medial portal. (Courtesy of M.T. Busch, MD.)
ANKLE DISTRACTOR PLACEMENT
Inspect all instruments, and confirm that all parts of the noninvasive external distractor are sterile and on the operative field (TECH FIG 6).
The patient is placed supine on the operating table.
The patient is placed so the foot rests within 10 cm of the end of the bed.
A bump (made from a rolled blanket) is placed under the hip to rotate the leg so the toes point straight up.
A tourniquet is placed on the calf below the level of the fibular head to prevent peroneal nerve impingement (TECH FIG 7).
TECH FIG 6 • Distractor set-up: instruments.
TECH FIG 7 • Distractor set-up: tourniquet placement.
The hip is flexed 60 degrees and the posterior thigh is placed in a padded thigh holder and secured with straps. It is very important that the thigh holder be placed so that the leg rests in the holder and does not rest in the popliteal fossa. If the thigh holder rests in the popliteal fossa, the pressure on the popliteal vein will increase bleeding throughout the case and make arthroscopic visualization much more difficult. With limited pressure on the popliteal space, the tourniquet is rarely needed during the arthroscopic portion of the case (TECH FIG 8).
The operative leg and ankle region is prepared and then draped using a standard arthroscopy drape.
The distal portion of the arthroscopy drape is pulled off the end of the foot to allow for the distractor placement.
The bed clamp is placed as far distal on the bed as possible. For the clamp to fit properly, the circulating nurse should make sure all of the underlying drapes except the top layer are moved away from the clamp attachment site (TECH FIG 9).
TECH FIG 8 • Distractor set-up: thigh holder placement.
TECH FIG 9 • Distractor set-up: optimal clamp position placed as far distal as possible.
The external distractor strap is placed with the foam portions over the posterior inferior heel and on the dorsal foot. After creating equal lengths on the medial and lateral sides of the foot, the hook–loop is pulled distally with manual distraction.
The L-shaped metal post is placed and secured.
The foot is then pulled manually via the strap and connected to the threaded attachment rod. We recommend the initial placement requires moderate effort to get the hook–loop secured so that initial manual distraction provides the majority of distraction. Once this is connected, use the threaded rod to provide further distraction to the ankle (TECH FIG 10).
The joint can be flexed or extended while in the distraction device to allow for complete evaluation of the joint.
TECH FIG 10 • Distractor set-up: final ankle set-up with manual tensioning.
POSTOPERATIVE CARE
For most conditions addressed with ankle arthroscopy, patients are placed in a well-padded short-leg splint. Five to seven days postoperatively the splint is removed and patients are allowed weight bearing as tolerated in a brace.
In cases where drilling, microfracture, or retrograde bone grafting of an osteochondral lesion is performed, a period of non–weight-bearing is emphasized.
Early range of motion is always encouraged unless a fusion is performed.
OUTCOMES
Ankle arthroscopy allows the surgeon to address a myriad pathology with a minimally invasive technique. Success of outcomes varies according to underlying pathology but is generally in the range of 85% good to excellent.
The complication rate ranges from 0.7% to 17%, with neurologic injuries accounting for most of these problems. The superficial peroneal nerve is the most commonly injured nerve, followed by the sural nerve and then the saphenous nerve.2
In one study using the posterior coaxial portals in 29 ankles, no complications were observed at an average 45 months of follow-up.1
COMPLICATIONS
Neurovascular injury
Cartilage damage
Reflex sympathetic dystrophy
Sinus tract formation
Infection
Skin necrosis
REFERENCES
1. Acevedo JI, Busch MT, Ganey TM, et al. Coaxial portals for posterior ankle arthroscopy: an anatomic study with clinical correlation on 29 patients. Arthroscopy 2000;16:836–842.
2. Ferkel RD, Guhl JF, Heath DD. Neurological complications of ankle arthroscopy. Arthroscopy 1996;12:200–208.
3. Ferkel RD, Hewitt M. Long-term results of arthroscopic ankle arthrodesis. Foot Ankle Int 2005;26:275–280.
4. Golano P, Vega J, Perez-Carro L, et al. Ankle anatomy for the arthroscopist, part I: the portals. Foot Ankle Clin North Am 2006;11: 253–273.
5. Lui TH, Chan WK, Chan KB. The arthroscopic management of frozen ankle. Arthroscopy 2006;22:283–286.
6. Maiotti M, Massoni C, Tarantino U. The use of arthroscopic thermal shrinkage to treat chronic lateral ankle instability in young athletes. Arthroscopy 2005;21:751–757.
7. Nihal A, Rose DJ, Trepman E. Arthroscopic treatment of anterior ankle impingement syndrome in dancers. Foot Ankle Int 2005;26:908–912.
8. Sim J, Lee B, Kwak J. New posteromedial portal for ankle arthroscopy. Arthroscopy 2006;22:799.e1–799.e2.