Pearls & Pitfalls
General Pearls & Tips for Anterior Ankle Arthroscopy
The portals should be made in the neutral position or in slight dorsiflexion, to minimize the risk of damage to the underlying structures. The anteromedial portal is regarded to be relatively safe, nevertheless neurovascular complications have been reported.
Introduction of the instruments through the anteromedial and anterolateral portal must be done with the ankle in dorsiflexion. In this position the nerves and vessels are not in tension, resulting in a minimal risk of iatrogenic damage. Moreover, this forced dorsiflexed position is the best prevention for iatrogenic cartilage damage.
The superficial peroneal nerve is visible in 40% of patients. To reduce the risk of damage it should be localized when possible (plantarflexion and inversion).
Osteophytes can be removed more easily in dorsiflexion, since it will increase the anterior working area in combination with the saline used for irrigation.
The saphenous nerve and great sapheneus vein are potentially at risk when making the anteromedial portal.
The superficial peroneal nerve is at risk in creating the anterolateral portal. To prevent damage:
1) make the incision through the skin only;
2) use blunt mosquito clamp to spread the soft tissue and to enter the joint cavity;
3) use only blunt instruments to enter the joint cavity;
4) introduce your instruments and scope with the ankle in the slightly or fully dorsiflexed position.
Preoperative planning is vital. The location and exact borders of the bony involvement of the lesions should be known.
When visualizing the defect, with a probe the talar cartilage can be palpated. The cartilage is soft at the location of the OCD, and you will feel the probe 'falling' into the defect.
The non-invasive distraction device can be used to inspect the defect.
In doubtful cases, before introduction of the bonecutter shaver, it can be useful to identify the defect by introducing a spinal needle, thereby penetrating the underlying defect bone area.
If there is any doubt about the direction and the extent of the defect, the arthroscope can be moved over to the portal opposite of the defect (the anteromedial portal in case of an anteromedial osteochondral defect) and the completeness of the debridement is assessed.
Every step in the debridement procedure should be checked by regularly switching portals.
Ideally all unstable cartilage should be removed since theoretically this area could give a rise to new subchondral bone cyst formation and complaints.
Bone marrow stimulation by means of a microfracture probe offers the possibility to work "around the corner". Always make sure that the calcified area is penetrated.
A 2 mm drill can break more easy than a K-wire if the position of the ankle is changed during drilling. When a 2 mm drill is used, a drill sleeve is necessary to protect the tissue.
Make sure when debriding the defect that no loose bodies escape into the ankle joint. These may cause pain and cartilage damage.