Anterior ankle arthroscopy is carried out as an outpatient procedure under general or spinal anaesthesia. The patient is placed in the supine position with slight elevation of the ipsilateral buttock. The heel of the affected ankle in placed at the very end of the operating table. This way, the surgeon can fully dorsiflex the ankle by leaning against the foot sole. Routine anterior portals used are the anteromedial and anterolateral portal. A soft-tissue distraction device can be used when indicated.
Non- invasive Distraction Device
The non-invasive distractor enables the surgeon to change quickly from the dorsiflexed position to the distracted position and vice versa. We measured the amount of distraction that can be gained with this device and measured the distraction force applied in a consecutive series of 25 patients.
The average forced distraction was 150 N while we gained an average joint distraction of 4.5 mm on the medial side and 4.3 mm on the lateral side. This is comparable to other authors.
The maximum amount of possible distraction is limited by the fact that the patient is pulled off the table if distraction is applied over an average of 280 N. This in itself protects the ankle joint from being overtightened. The working area can be enlarged by leaning backwards with distraction forces up to 280 N. These high forces are only used for a short period of time to ease access to the pathology. The distraction force can be diminished once the extra space is no longer needed. We encountered no neurologic or vascular problems.
The advantage of this system is that it is inexpensive, gives reproducible results that are comparable to other existing systems, and is very easy to apply. The main advantage is that the choice to perform distraction can be made at any moment during the arthroscopic procedure. Moreover, the amount of distraction can be easily adjusted during the procedure. The surgery can start in the relatively simple and preferred dosiflexed position and, if needed, the distraction device can be applied.
We feel that the use of this device makes ankle arthroscopy a much simpler and more effective procedure.
Is joint distraction necessary to perform anterior ankle arthroscopy?
In patients with anterior impingement due to soft tissue or spur formation, distraction results in tightening of the anterior joint capsule, thereby decreasing the anterior working area. When the joint is brought into the forced dorsiflexion position, however, the anterior compartment opens up and the pathology can more easily be identified and treated.
Loose bodies are usually located in the anterior aspect of the ankle joint. Dorsiflexion creates an anterior working area and makes removal easy. Distracting the joint enables the loose body to "fall" into the posterior aspect of the joint, thus making removal more difficult.
The main reason for entering the ankle joint itself is inspection of the talar dome and tibial plafond in case of an osteochondral defect (OCD). As stated earlier a diagnosis must be established pre-operatively using history, physical examination and standard X-rays. For the pre-operative planning the CT-scan has the advantage of exact sizing and locating an OCD. An osteochondral talar defect can be brought into the anterior working area by bringing the ankle in hyper- plantarflexion. In a consecutive series of 43 patients with an osteochondral talar defect, the defect could be identified and treated without the use of mechanical joint distraction. All defects were brought into the anterior working area by maximal plantar flexion of the ankle joint. Adding some soft tissue distraction can be helpful at this point.
There is one other situation in which distraction is beneficial. In a patient with deep ankle pain and a negative CT-scan and/ or negative MRI (no OCD), the diagnosis can be anterolateral soft tissue impingement. The soft tissue impediment can be located posterior from the anterior tibial fibular ligament in the so called intrinsic syndesmotic area. For the treatment of these soft tissue impingements as well as for the treatment of an osteochondral defect of the distal tibia, we need distraction of the ankle joint. If the soft tissue distraction is not sufficient for the 5 mm arthroscope to enter the joint, the scope is left into the anterior working area and with the 30° angle we can inspect the intrinsic syndesmotic area and the tibial plafond from the front. The distraction will always be sufficient to enter the joint using a probe in order to palpate the defect and subsequently debride it with a curette. In case of an osteochondral tibial plafond lesion it can be microfractured with a microfracture probe.
A 4.0 mm and 2.7 mm arthroscope with 30° obliquity can be used for ankle arthroscopy. The new small diameter short arthroscopes yield an excellent picture that is difficult to distinguish from a standard 4 mm scope. The small diameter arthroscope sheath, however, cannot deliver the same amount of irrigation fluid per time as the standard sheath. This is an important drawback when motorized instruments are used, as in these cases an adequate amount of irrigation is beneficial. In the author's opinion, for routine arthroscopic procedures such as anterior impingement syndrome, loose body removal, treatment of synovitis and the vast majority of osteochondral defects, it is beneficial to use the 4.0 mm arthroscope. A 2.7 mm arthroscope should be used only for osteochondral defects of the posterior talar dome (less than 8% of all osteochondral defects in the ankle joint), pathology of the articular part of the tibiofibular joint (intrinsic syndesmosis), such as a soft tissue impediment or impremated ossicles or loose bodies, posterior ankle problems that are treated by an anterior approach, and patients without a pre-operative diagnosis. But even in these cases we use the 4.0 mm arthroscope; the scope stays in front, and with the 30 degree angle we can inspect the ankle joint.
Different fluids can be used for arthroscopic irrigation during arthroscopy: normal saline, glycine or Ringer’s lactate. When a 4 mm arthroscope is used, gravity inflow is usually adequate if the fluid is introduced through the arthroscope sheath. When a 2.7 mm arthroscope is used, the gravity inflow should be introduced through a separate cannula. Alternatively an arthroscopic pump can be used.
Apart from the standard excisional and motorized instruments for treatment of osteophytes and ossicles, a 4 mm chisel and/or small periosteal elevator can be useful. For the treatment of osteochondral defects a small diameter closed cup curette and motorized instruments for debridement and drilling are mandatory.
Proper portal placement is critical for any arthroscopic procedure. Two primary anterior portals are used in ankle arthroscopy: the anteromedial and anterolateral portals. The anteromedial portal is always made first since it is easy to access. This is especially true in the hyperdorsiflexed position. The exact point of entry in this position is very reproducible and the risk of neurovascular complications is minimal. Accessory anterior portals are located just in front of the tip of the medial or lateral malleolus. Some advocate the use of posterior portals in anterior ankle arthroscopy. In these cases, a posterolateral portal is recommended. Because of the potential for serious complications, most authors feel the posteromedial portal is contraindicated when performing anterior ankle arthroscopy.
The anteromedial portal is located just medial to the anterior tibial tendon at the joint line. In the hyperdorsiflexed position, a depression can be palpated. In the horizontal plane, this depression is located between the anterior tibial tendon and the medial malleolus, while in the vertical plane this depression is located between the anterior tibial rim and the talus. The surgeon's palpating thumb first detects the interval in the horizontal plane and subsequently locates the vertical position. By moving the ankle joint from the plantarflexed position to the dorsiflexed position, the talus can be felt to move in relation to the distal tibia. The surgeon's palpating thumb thus gets locked into this "soft spot". A small longitudinal incision is made through the skin only. Blunt dissection is performed with a mosquito clamp through the subcutaneous layer and through the capsule into the ankle joint. With the ankle in the forced dorsiflexed position, cartilage damage is avoided. In this forced dorsiflexed position, the arthroscope shaft with the blunt trocar is introduced. When the trocar is felt to contact the underlying bony "joint line", the shaft with the blunt trocar now is very gently pushed further into the anterior working area in front of the ankle joint towards the lateral side. The anterior compartment is irrigated and inspected.
When the trocar is touching the underlying bony joint line, it is very gently pushed further into the anterior working area, towards the lateral side. Now the 4.0 mm 30 degree arthroscope can be introduced.
The anterolateral portal is the second standard anterior portal. It is made under direct vision by introducing an spinal needle. In the horizontal plane, it is situated at the level of the joint line. In the vertical plane, this anterolateral portal is located lateral to the common extensor tendons and peroneus tertius tendon. Care must be taken to avoid the superficial peroneal nerve as it runs subcutaneously. It can usually be palpated or visualized by placing the foot in forced hyperplantarflexion and supination. The lateral dorsocutaneus branch of the superficial peroneal nerve can often thus be visualized. The intermediate dorsal cutaneous branch of the superficial peroneal nerve crosses the anterior aspect of the ankle joint superficial to the common extensor tendons. Damage to this branch can be avoided by staying lateral to the extensor tendons. If the lateral branch can be identified, its position should be marked with a marking pen on the skin.
The location of the anterolateral portal may vary depending on the location of the lesion in the ankle joint. For treatment of anteromedial ankle pathology, the anterolateral portal is located between the lateral branch and the peroneus tertius tendon as far medial as possible (close to the peroneus tertius tendon). For treatment of lateral pathology, the anterolateral portal is placed more laterally.
After making a small skin incision, the subcutaneous layer and capsule are bluntly divided with a mosquito clamp.
To make the anterolateral portal, a spinal needle is inserted under direct vision at the level of the joint line, just lateral form the peroneus tertius tendon (or if not present the extensor digitorum tendon)
Inferior anteromedial and anterolateral portals
The lateral accessory portal is placed just below the anterior talofibular ligament. After introduction of a spinal needle, a skin incision is made in line with the anterior talofibular ligament. The surgical knife can be introduced into the joint under direct vision. On the medial side (after locating the portal with a spinal needle), the incision is made in line with the deltoid ligament fibres. The knife can consequently be introduced into the joint under direct vision.
Portals we use for anterior ankle arthroscopy. the two standard protals we use are the anteromedial and anterolateral portal. The anterolateral portal is made under direct vision, just lateral to the peroneus tertius tendon. Two additional portals can be made during the procedure, depending on the indication. These are the inferior anteromedial- and lateral portals. You can find these portals in the section surgical procedures (last 6 pictures).
The anterocentral portal is located directly over the common extensor tendon. It presents some risk to the neurovascular structures and, in the author's experience, use of this portal has never been necessary.