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.
In forced dorsiflexion the talus is concealed in the joint which protects the weight bearing cartilage of the talus from potential iatrogenic damage. Therefore always introduce your instruments in the dorsiflexed position.
In case of medial malleolar osteophytes, overcorrection of the medial malleolus is generally pursued by shaving some of it away after resection of the osteophyte.
To determine the size of the osteophytes during an arthroscopy you have to identify the normal contour of the distal tibia proximal to the osteophyte. To achieve this you need to shave away the tissue just superior to the osteophyte.
In anterolateral impingement the arthroscope remains introduced through the anteromedial portal, while the anterolateral portal is the working portal.
In anteromedial impingement the scope is introduced through the anterolateral portal, while the anteromedial portal now is your working portal.
The large diameter 5.5 mm bonecutter shaver has the advantage of adequate flow and good 'bite' on the bone. In unexperienced hands it has the disadvantage of resecting too much of the front ankle capsule. Less experienced surgeons should therefore start with the 4.5 mm shaver.
1). This is the right position of the shaver. The opening is facing bone.
2). In this picture, the opening of the shaver is towards the medial soft tissue. This might give iatrogenic damage to the ankle capsule, ligaments and neurovascular structures.
3). Again, the shaver is in the wrong position. The opening is facing the articular cartilage of the talus, which causes iatrogenic damage to this weight-bearing cartilage when touched by accident.
In case the inferior edge of a tibial osteophyte cannot be reached with a shaver, some distraction of the ankle joint can be beneficial.
When an osteophyte is (partly) detached with a chisel, the grasper is used to remove it from the ankle. The easiest way to remove a fragment is to grasp it in a longitudinal direction so that the portal does not have to be enlarged.
Distraction results in tightening of the anterior capsule which makes it more difficult to identify the osteophytes.
Osteophytes are covered by scar tissue and synovial folds. They can easily be missed during arthroscopy. Preoperative planning with correct visualization of the location and size of the osteophytes is of vital importance.
Remember that when the X-ray shows no spurs, during arthroscopy you are probably not prepared to take away any bone.