Surgical Procedure
Overview. Standard approach of right ankle. The foot is placed on a triangular pad, straight down, and over the end of the operating table so that the ankle can be moved freely.
The medial and lateral malleolus are marked.
A probe is 'hooked' under the lateral malleolus, parallel to the footsole.
The level of the probe is marked.
In this pictue, the level above which the portals should be made (red) and the contours of the Achilles tendon (green) are marked.
The position of the portals is marked (blue). The incisions will be made right next to the Achilles tendon.
Vertical stab incisions.
With a curved mosquito, the subcutaneous layers are split.
The direction of the mosquito is towards the first interdigital webspace.
The scope is introduced, also pointing towards the first interdigital webspace. The direction of view is to the lateral side. We use this grip on the scope to be able to change direction of view with the thumb, and placing the langest finger on the skin for optimal control. At this point, there is no clear image yet.
A mosquito clamp is introduced in a 90 degree position into the medial portal, until the tip touches the shaft of the arthroscope.
The mosquito now has to glide anteriorly, over the shaft of the scope. Then the scope is pulled back, and the tip of the mosquito comes into view. Now the subcutaneous layers can be spread under endoscopic view.
Then a 5.0 mm bonecutter shaver is introduced into the medial portal. The shaver is put onto the posterolateral talar process.
Now, whilst shaving, a defect can be created in the fascia to visualize the subtalar joint.
Defect in the fascia. When pushing the scope past this defect, the subtalar joint will become visible.
Subtalar joint.
The defect in the fascia is enlarged to create more working space. Again, this is done by positioning the scope onto the posterolateral talar process.
Overview of image after enlargement of the defect in the fascia.
When still more space needs to be created, with a punch part of the fascia and Rouviere ligament can be removed using a punch.
The level of the ankle joint now comes into view.
Level of the ankle joint.
As a final step, the flexor hallucis longus needs to be located. This is done by putting the saver onto the posterior talar process, carefully shaving towards medial.
After this, in one movement, the shaver can be tilted proximally, and the FHL comes into view. If not, the previous step can be repeated.
Result of this standard posterior approach. From here, multiple pathologies can be addressed.
Pearls & Pitfalls
Pearls
- For the correct orientation and reproducibility always start with the arthroscope in the posterolateral portal. Initially it is directed towards the first interdigital webspace.
- Instruments introduced through the posteromedial portal are inserted perpendicular to the arthroscopic shaft. The shaft is subsequently used as a guide to direct the instruments anteriorly. The direction of the arthroscopic view (30 degree angulation) is routinely to the lateral side for a good and persistent orientation throughout the procedure.
Pitfalls
- Correct portal placement is important to prevent neurovascular complications. The posteromedial and lateral portal must be positioned 5-7 mm anterior to the Achilles tendon, just above the level of the tip of the lateral malleolus.
- In the hindfoot the crural fascia can be quite thick. This local thickening is called the ligament of Rouvière. This ligament needs to be at least partially excised of sectioned, using arthroscopic punch or scissors, to approach the ankle joint.
- The FHL tendon must always be located first before addressing the pathology. Medial to this tendon the posterior tibial nerve and artery are situated. The working area is therefore lateral to the FHL tendon. The video above is an example of arterial bleeding posteromedial to the FHL. Bleeding is controlled using the Vapor (see video above: Haemostasis with vapor)
- Posterior ankle arthroscopy is an advanced endoscopic procedure, surgeons not familiar with endoscopic surgery are advised to train themselves in a cadaveric setting.