A Modified Technique for Augmentation of Chronic Lateral Ankle Instability
An ankle injury is the most common sports injury and one of the most common pathologies treated by foot and ankle surgeons.1–3 With up to 25% of ankle sprains leading to chronic lateral ankle instability, foot and ankle surgeons need to have a successful and reproduceable surgical technique to treat the condition.1 In patients with a significant deformity, poor soft tissue, or revision cases, soft tissue augmentation may be required during ligament repair. Soft tissue augmentation has been vital to successful outcomes when a primary repair may not be effective.4–9
Several techniques have been described for augmented lateral ankle ligament repairs including autograft, allograft, suture anchors, suture tape, and more recently, dynamic matrix biomaterial. The advent of recent technology has led to improvements in surgical techniques for anatomic lateral ankle ligament reconstruction. With new biomaterials, surgeons are now able to preserve native tendons traditionally used for autograft augmentation and the technique is straightforward and reproducible.
The purpose of this article is to describe the author’s preferred technique for augmented lateral ankle ligament reconstruction using a dynamic matrix biomaterial.
A Review of Current Repair Options
A primary Broström-Gould procedure has been the standard for patients with lateral ankle ligament instability.10,11 However, this procedure may not be powerful enough in patients with hyperlaxity, significant chronic instability, or those who have failed a primary procedure. In these cases, augmented lateral ligament reconstruction is appropriate. There are many options available for augmented lateral ankle ligament reconstruction. Autograft tendon augmentation has been described with success.12–15 However, this requires harvesting a local tendon, often one of the peroneal tendons, which can compromise the native structures in the area. It is also shown that autograft can lengthen and weakens quickly after its use in ligament repair.16
Allograft tendon repair has also been described with significant success.17,18 There are also disadvantages to allograft tendon repairs, however. There have been reports of allograft tendon reconstruction leading to over-constraint of the ankle motion and altering normal ankle kinematics.19,20 The use of an allograft requires sterilization, a process that can weaken the structure and integrity of the graft.21,22 There also is evidence, similar to autograft, that allograft tendons demonstrate creep over time and lose strength.23
The advent of suture tape has provided a good alternative to autograft or allograft.5–9 Although its success has been demonstrated, suture tape can have its drawbacks. There are concerns for applying the appropriate tension and possible over-constraining the normal ankle and subtalar joint motion.7,24 There can be a learning curve to tensioning the graft appropriately. It also can create stress shielding of the native lateral ankle ligaments secondary to the rigidity of the suture tape material.25
Insights on a Dynamic Matrix Biomaterial
An emerging augmentation technology is becoming more popular. A dynamic matrix biomaterial (Artelon Flexband, Artelon Inc, Atlanta, GA) is proven to be a safe and effective graft material for lateral ankle ligament reconstructions.26–29 The material is very strong yet flexible and is designed to mimic the normal kinematics required of the lateral ankle ligaments during gait and function. The material is very inert and incorporates into normal collagen tissue over several years while continuing to hold its strength over time. The author has had significant success utilizing the dynamic matrix in double anatomic lateral ankle ligament reconstruction. The matrix can be substituted for allograft/autograft in anatomic lateral ankle repairs and has demonstrated successful outcomes.
In the case of significant lateral ankle instability, the author prefers to reconstruct both the anterior talofibular ligament (ATFL) and the calcaneofibular ligament (CFL). In these cases, there is concern for subtalar joint instability in combination with ankle instability. Adding the CFL reconstruction stabilizes the subtalar joint and can provide improved clinical outcomes.30–32 When performing traditional reconstruction of both the ATFL and CFL, 2 drill tunnels are generally placed into the distal fibula—a tunnel for the ATFL arm and a tunnel for the CFL arm. This technique has been modified and is presented by the author. The 2-tunnel technique can often be challenging. The distal fibula is a relatively small structure and has limited real estate. These tunnels are generally between 4–6mm in diameter. If the tunnels are placed too close together, the bone bridge can fracture and fixation is lost. It can also be challenging to avoid medial or lateral cortical breakthrough when drilling these tunnels. The technique demonstrated in this article uses a single blind tunnel in the distal fibula. This technique requires a significantly smaller area of bone within the distal fibula and can allow alternative options if fixation is lost (Figure 1).
Begin with the patient lying in a lateral position, or supine with a large hip bump. An incision is made over the distal fibula oriented from the posterior aspect of the fibula near the peroneal tendons, directed distal and anterior toward the lateral talus. Dissection then continues deep and the inferior extensor retinaculum is identified. The retinaculum is elevated and preserved for later Gould modification reinforcement. Evaluation of the anterior talofibular ligament and calcaneofibular ligament will determine the need for augmentation.
If augmentation is appropriate, the native ligaments are incised off the distal fibula. A cuff of tissue is created on the distal fibular for later closure of the native tissue. The author prefers the augmented repair to be intracapsular; however, the repair can easily be placed extracapsular over the native ligament tissue pending surgeon preference. The native ligaments are reflected and retracted distally to their insertion on the lateral talus as well as lateral calcaneus. Often, the peroneal tendons will need to be retracted in order to gain access to the insertion of the calcaneofibular ligament. If needed, release the superior peroneal retinaculum and retract the peroneal tendons safely. Peroneal tendon pathology can be addressed at this time.
Once the lateral talus and calcaneus are exposed, the augmentation procedure can begin. Guidewires for fixation anchors are then placed. One wire is placed into the distal fibula, approximately halfway between the origin of the ATFL and CFL. A pilot drill hole is then placed into the distal fibula. This is a blind tunnel allowing for fixation of both ATFL and CLF arms into the fibula. Guidewires are then placed into the lateral talus and calcaneus at the insertions of the ATFL and CFL. A good lateral X-ray will confirm proper placement of the guidewires. Pilot holes are then drilled into the lateral talus as well as lateral calcaneus.
Attention is then directed back to the distal fibula. The graft is placed into the anchor eyelet and the anchor is positioned halfway down the length of the graft. The graft is then secured into the fibula with an anchor and allows for one arm of the graft to be directed to the talus and one arm to the calcaneus (Figure 1 and Figure 2). The author’s preference is to secure the graft into the lateral talus next, prior to the lateral calcaneus. The foot is dorsiflexed and everted. The graft will self-tension as it is secured into the lateral talus with an anchor (Figure 3).
Attention then directed to the calcaneus and with the foot everted, the graft is secured into the lateral calcaneus in the same fashion (Figure 4). The native tissue is then repaired over the augmented repair utilizing a pants-over-vest repair back into the tissue cuff off the distal fibula. The superior peroneal retinaculum is repaired as needed. The inferior extensor retinaculum is advanced over the native tissue repair and sewn into the distal fibular periosteum for reinforcement. A standard layered closure is then performed.
The author’s postoperative protocol is a non-weight-bearing splint for 1 week, followed by 2 weeks non-weight-bearing in a cast. Sutures are removed at the third week post-op and patients are allowed to begin protected weight-bearing in a boot. Postoperative physical therapy begins at the third week with passive range of motion and advances appropriately. Therapy generally lasts 6 to 12 weeks. Augmented repairs allow for confidence in early rehabilitation.
In Conclusion
The author has had great results with the above technique when appropriate. There are many different options available for the repair of chronic ankle instability and surgeons should be aware of emerging technologies and successful techniques.
Travis Langan, DPM, FACFAS, is a fellowship-trained foot and ankle surgeon who practices at UnityPoint Foot and Ankle Surgery in Sioux City, IA.
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