Evaluating and Treating Chronic Ankle Instability

Ankle sprains are by far the most common athletic injury and a common orthopedic problem presenting for urgent treatment across the United States.1-3 A majority of ankle sprains will end in asymptomatic recovery with conservative care.3 This conservative care can include rest, ice, anti-inflammatory medication, bracing and functional physical therapy. However, there will be a subset of ankle sprains that progress to chronic ankle instability or chronic ankle pain, resulting in residual issues past the acute three-month period of injury. Such cases of chronic ankle instability and pain are the focus of this article.

Whether it is a patient who presents for an acute sprain which is now chronic or a new patient who has chronic ankle pain and instability after a sprain, the minimal time to chronic status is three months post-injury. Patients will often seek treatment six months to a year after a sprain due to chronic pain and discomfort.

Symptoms of chronic ankle instability include the ankle “giving way,” either with normal walking or with sports and activity. Patients often relate that a brace improves their symptoms. Additional findings may include catching or locking of the ankle, chronic deep pain in the ankle and possible pain along the peroneal tendons. It is common for patients to present with generalized ankle pain and swelling with instability or giving out of the ankle as the main complaints. 

The physical exam should include range of motion of the ankle in comparison with the contralateral limb. One should also evaluate for swelling and regions of pain along the medial gutter, central ankle and lateral gutter. The patient may exhibit a positive anterior drawer and/or positive talar tilt test of the ankle along with tenderness of and pain with resistance of the peroneal tendons. Long-standing cases of peroneal injury, usually the peroneus brevis, will result in the peroneus longus being overworked and a greater cavus of the affected foot. This is due to the posterior tibial tendon functionally being stronger than the peroneals and the peroneus longus plantarflexing the first ray.4 

The severity of the anterior drawer is somewhat of a debate and not all cases of ankle instability require the presence of severe laxity. Instability can be partially a functional issue, which means the ankle is not grossly unstable but may give out on uneven surfaces, or during athletic activity. Other cases may show gross instability. In either case, be aware that ligament instability is somewhat subjective and not a given standard. If the ankle is grossly stable in comparison to the contralateral ankle, there may be other unidentified sources of pain.

Radiographs allow one to check for loose bodies in the ankle, possible avulsion fracture of the lateral fibula and to perform a gross check of the syndesmosis position. In cases of chronic instability with syndesmosis injury, the treatment is challenging and far beyond the scope of this article. 

The main diagnostic examination for chronic, painful ankle instability is magnetic resonance imaging (MRI). One may utilize MRI to evaluate almost all aspects of ankle instability including the bone, cartilage, ligaments, tendons and overall position of the joints. The most common findings to consider on MRI are bone bruising, osteochondral lesions of the talus, ligament injury to the lateral ankle, peroneal tendon tear and loose bodies or synovitis of the joint. It is possible to identify all of these findings with MRI but there are some issues to consider.

Not all osteochondral lesions will present clearly. An osteochondral lesion may appear to be a minor bruise of the talus or very minor marrow edema of the talus. If there is associated pain, an osteochondral lesion could be a source of the problem. Peroneal tears often involve the peroneus brevis and will not show as a compete tendon tear, but more as an unraveling of the normally coiled tendon. Usually, there will be a C-shaped tendon instead of an O-shaped tendon. 

Alternately, the peroneus brevis may split completely in two longitudinal pieces in the tear region. In such cases, you will see the peroneus longus sitting anteriorly and between the two pieces of the peroneus brevis tear. The ankle ligaments may not show as complete tears on MRI and only show thickening or scarring. Remember that the ligaments are present but may be lax. This is a normal finding as one would usually identify laxity more by mechanical testing as opposed to it being a radiological finding. Bone bruising in the body of the talus or tibia with minimal cartilage damage can be an issue on its own and treatment for such issues is different than it would be for an osteochondral lesion. 

A Few Thoughts On Other Conservative Care Options

After three months of conservative care for an acute ankle sprain, there is no way to tighten the ankle ligaments further. However, functional stability training and muscle strengthening may provide enough stability to avoid surgery. This is truly dependent on the level of activity and how a patient feels after a period of physical therapy. As the injury is chronic, there is no harm in trying six weeks of therapy prior to surgical planning.

Furthermore, platelet rich plasma (PRP), in my experience, is helpful in some cases for patients with bone bruising, joint pain and small osteochondral lesions in the ankle. By restarting the acute injury cascade and increasing the healing potential in the region of injury, a patient may experience less pain and discomfort in the ankle joint. I do not find PRP helpful in cases of peroneal tendon tears or ligament laxity cases. That said, I have found that PRP is effective in cases of peroneal tendinopathy with scar formation in an intact tendon.

Step-By-Step Insights On Surgical Intervention For Chronic Ankle Sprains

When it comes to cases of chronic ankle sprains with pain and instability, one can perform surgical stabilization of the ankle. One of the most common primary techniques is a modified Brostrom ankle stabilization procedure. With this procedure, the surgeon cuts the anterior talofibular ligament and the calcaneofibular ligament off the fibula in addition to releasing the lateral capsule. One then repairs the ligaments in a pants-over-vest fashion with anchors. Surgeons may also perform extensor retinaculum tightening in the same manner without the use of anchors for an added layer of stability.

In certain cases, there may have been multiple sprains to collateral ligaments that require augmentation of the tear. In such cases, I prefer to add a ligament augmentation system from Arthrex called InternalBrace™. This allows the surgeon to place a thick FiberTape® from the fibula to the talus for additional stability. I believe the InternalBrace system is at risk for overuse as most cases of primary ankle instability do not require this system. Additionally, one should take care not to over tighten the ligaments with the InternalBrace as this can limit ankle range of motion and cause a feeling of stiffness. Furthermore, the InternalBrace should not replace the collateral ligament but augment it. If the patient has very lax ankles with several sprains and/or a possible failed primary repair, this may warrant a secondary ankle ligament repair with a tendon reconstruction.

I always perform an ankle arthroscopy with my ligament repairs. It is very rare for me not to find internal synovitis, scar formation or fibrous bands in the ankle that may have resulted from the ankle injury. Cleaning these out will help the ankle heal better. Arthroscopy is also my preferred method for cartilage repair. I will perform an arthroscopic exam of the ankle and clean out scar tissue and cartilage lesion damage. Depending on the associated size and depth of the lesion, I use either BioCartilage® Extracellular Matrix (Arthrex) or DeNovo NT Natural Tissue Graft (Zimmer Biomet) for the lesion. In most primary repair cases, I find that BioCartilage is more commonly approved by insurers due to cost. 

After arthroscopic preparation of the lesion, I perform microfractures and dry out the ankle. Then I arthroscopically place the BioCartilage and seal it with fibrin glue. If the lesion is difficult to treat arthroscopically, I implement a mini-arthrotomy and treat the lesion the same way with an open incision. The only difference with DeNovo treatment is that the surgeon does not microfracture the lesion and leaves the underlying subchondral bone intact. Surgeons can utilize DeNovo arthroscopically or via open repair.

Peroneal repairs are often straightforward. After identifying the peroneal tear, the surgeon roughens the edges of the tear with cautery and then sews the tendon onto itself with a running, locking non-absorbable suture. My preferred material is 4-0 nylon suture, which is less rough to the surrounding tendon and ligaments. If the tendon has a split tear, one will need to suture the front and back sides with the same technique. Finally, if one or both of the tendons are very badly damaged, one can combine the two tendons to make one solid tendon by suturing the peroneus brevis and longus tendons together. For this, I prefer to use a 2-0 FiberWire® (Arthrex) suture, which is more secure and strong. 

If there is long-standing instability along with a long-standing tendon tear, the surgeon may need to address a cavus foot position. In these cases, one may perform tendon repair and a Dwyer calcaneal osteotomy with or without an elevation osteotomy of the first ray. I often find that the brevis tendon is dry and of bad quality. In these cases, the surgeon may transect the longus tendon and transfer it to the distal stump of the brevis attachment for better function.

Finally, bone bruising can be a debilitating issue that can be a source of pain and aching in the ankle. Surgeons often treat this by infiltrating a bone substitute material into the bruised region, a procedure known as subchondroplasty. I have gotten away from this procedure as there are reports of avascular necrosis of the bone.5 I prefer to use a bone aspirate taken from the tibia or calcaneus, and place it into the area of the bone bruise to help with healing. This has worked well for me and is fairly easy at the time of surgery. 

Essential Postoperative Considerations 

I place the patient in a bivalved cast for the first week and then transition to a non-weightbearing cast for an additional two weeks. At three weeks, the patient can transition to a removable cast boot, which allows dorsiflexion and plantarflexion range of motion, and prevents scar formation in the joint. I allow the patient partial weightbearing on the ankle at this point unless I have treated an osteochondral lesion. In this case, weightbearing is restricted for six weeks with partial weightbearing in a boot and subsequent transition to a brace. Physical therapy starts at week three or four post-surgery and the patient moves into a brace at six weeks without lesion treatment. 

In Conclusion

Ankle sprains heal well with proper conservative care but there is a fraction of sprains that result in chronic ankle instability. The common triad of pain to consider is synovitis or scarring of the joint, ankle instability and peroneal tendon tear. Additional factors are osteochondral lesions of the talus, bone bruising and loose bodies in the ankle joint. With proper care of ankle instability and associated factors, surgeons can facilitate full healing and return patients to pre-injury levels in a large majority of cases.

Dr. Baravarian is an Assistant Clinical Professor at the UCLA School of Medicine. He is the Director and Fellowship Director at the University Foot and Ankle Institute in Los Angeles.

References

1. Nelson AJ, Collins CL, Yard EE, Fields SK, Comstock RD. Ankle injuries among United States high school sports athletes, 2005-2006. J Athl Train. 2007;42(3):381-387.

2. Schuerman L. Evaluation and management of ankle injuries in urgent care. J Urgent Care Med. Available at: https://www.jucm.com/evaluation-management-ankle-injuries-urgent-care/ . Accessed June 3, 2020.

3. Petersen W, Rembitski IV, Koppenburg AG, et al. Treatment of acute ankle ligament injuries, a systematic review. Arch Orthop Trauma Surg. 2013;133(8):1129-1141.

4. Davda K, Malhotra K, O’Donnell P, Singh D, Cullen N. Peroneal tendon disorders. EFORT Open Rev. 2017;2(6):281-292.

5. Yang A, Kruse DL, Stone PA. Case report: avascular necrosis of the talus after using subchondroplasty for treatment of a subchondral cyst and bone marrow lesion. Poster presented at: American College of Foot and Ankle Surgeons Annual Scientific Conference. February 19-22, 2020. San Antonio, Tx.