Pertinent Insights On Ankle Arthroscopy
- Volume 26 - Issue 1 - January 2013
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• The final basic principle of arthroscopy is rotation. Rotation enables one to visualize the areas around the lens in all directions without pistoning the camera.
Key Treatment Considerations With Ankle Arthroscopy
Now that we have discussed the background, terminology and instrumentation, how can we use them to treat patients?
For example, chondroplasty is the debridement of fibrillated or uneven cartilage that hinders the normal motion of the joint. One can perform this technique with a power shaver, abrader or a curette. It is important to be gentle. Surgeons should smooth the joint surface and take care not to create osteochondral defects. Chondroplasty is generally not the initial choice of treatment for cartilage pathologies because it does not revascularize the defects themselves but simply restores normal contour to the cartilage.
Abrasion arthroplasty is another useful technique in ankle arthroscopy. This method involves resecting islands of necrotic cartilage and subchondral bone down to the tidemark. The tidemark is the anatomical level in the subchondral bone lying between the calcified and non-calcified cartilage. The tidemark is typically about 1 mm into the subchondral bone. This level is important because it is vascularized, which will facilitate healing of the defect with fibrocartilage. Since the tidemark or zone of calcified cartilage is only 1 mm down, it is once again important to be gentle with the debridement of the cartilaginous lesions. Overzealous debridement of the subchondral bone can predispose the joint to arthritic changes. One can easily perform abrasion arthroplasty with a small burr.
Arthroscopy of the ankle generally occurs in the outpatient setting with the patient under general, regional or spinal anesthesia. The patient should be in the supine position unless the surgeon opts to use the posterior portals to access pathologies that the typical anterior portals cannot reach. In these cases, a prone position may be warranted with the proper offloading of bony prominences. The patient’s knee can either be extended or the hip and knee can be flexed. Positioning is based upon surgeon preference.
Distraction of the ankle joint can offer easier maneuverability of the instrumentation within the joint space. Distraction can be either invasive with pins above and below the joint line, or noninvasive with a harness. However, De Leeuw and colleagues showed that the distracted ankle places the neurovascular structures about the ankle joint at a higher risk of iatrogenic injury when the bulk of the procedure focuses on the anterior portion of the joint.5 Ankle joint dorsiflexion can be a substitute for distraction in these cases, such as debridement of a bony exostosis on the anterior tibia.
The tourniquet should be at the level of the thigh. Before portal dissection and inserting instruments into the joint, inflate the space with 15 to 20 mL of lactated Ringer’s solution or saline through the same location as the anteromedial portal with an 18-gauge needle. The injected fluid will help to distend the joint space and the synovium for better visibility, and maximize the space in which the surgeon can work.
Pertinent Pointers On Post-Op Care
Postoperative management focuses on early range of motion. Two to five days following ankle arthroscopy, the patient can remove the posterior splint and begin passive range of motion exercises. This early range of motion will help the new fibrocartilage to better contour to the joint as it is deposited and will prevent stiffness of the joint.
The patient should then wear a partial weightbearing cast for four to six weeks to allow the cartilage to repair and fill in with fibrocartilage. After six weeks, the patient should begin physical therapy to regain range of motion. Patients should postpone all impact activities for 12 weeks. Typically, NSAIDs provide satisfactory analgesia following ankle arthroscopy. It is also important to inform the patient that for many months after the procedure, considerable edema may be present at the level of the ankle where arthroscopy occured.