Current Considerations For Surgical Treatment Of Chronic Ankle Instability

If patients fail conservative care for chronic ankle instability, there are a number of current and emerging surgical options. With this in mind, this author shares insights on the arthroscopic Broström procedure, the InternalBrace and the use of anchors in the distal fibula, and discusses how to approach revision and secondary repair of affected ligaments.

Chronic ankle instability, a term that refers to recurrent episodes of the ankle giving way and repetitive sprains, is one of the most frequent complaints encountered by foot and ankle surgeons.^1,2 The majority of these acute ankle injuries heal uneventfully without long-term consequence. Some patients bypass appropriate treatment, which may predispose them to developing chronic ankle instability.

On that note, it is important to differentiate the athletic population from the common population. The athletic population is more likely to suffer from long-term consequences after an ankle sprain. One study found a 30.2 percent incidence of residual pain in athletes after an acute ankle sprain and a 20.⁴ percent incidence of latent instability.³ These numbers may be inflated but they provide support for a higher incidence of latent pain and instability from acute ankle sprains in athletes. One reason may be inadequate treatment after the initial injury and a premature return to sport. The long-term consequence of untreated chronic ankle instability is ankle arthritis, experienced by 16 percent of patients with ankle osteoarthritis.⁴

In my experience, patients treated after a grade II or grade III acute sprain with the following protocol have had very rare development of chronic ankle instability. I keep patients in a non-weightbearing splint in neutral-eversion for seven to 10 days after surgery. Patients then have seven days of protected weightbearing with a walking boot and boot removal for dorsiflexion and plantarflexion range of motion exercises. The patient subsequently transitions to supportive brace and physical therapy (or a home therapy program).

Many patients do well with temporary immobilization and then functional rehabilitation. For those who do not improve adequately and have mechanical instability and ankle pain, a thorough workup is warranted. This begins with a clinical evaluation of foot type and any and all areas around the ankle where there is pain.

One should attempt conservative treatment for patients with chronic ankle instability. Non-surgical management should include bracing and appropriate physical therapy, consisting of balance training protocols and strengthening programs in the aim of achieving dynamic stability. Failure of these measures can lead one to consider surgical intervention.⁵

For every patient with chronic ankle instability who fails conservative care, one should obtain magnetic resonance imaging (MRI) prior to surgery. Often, a partial or complete chronic anterior talofibular ligament tear/irregularity is the only pathology MRI identifies but arthroscopic findings for these patients leave me skeptical of MRI findings. Many patients have concomitant chronic synovitis, osteochondral lesions, loose bodies, large fibrous bands in the anterior compartment and impingement lesions, especially anterolateral. Since I do not trust MRI for accurate assessment of all intra-articular joint derangement, the reason for obtaining MRI is primarily to confirm the presence of an anterior talofibular ligament injury.

Key Considerations When Patients Have Pes Cavus

Patients with pes cavus, especially those with a possible underlying neurogenic pes cavus, are at an increased risk of failure with a simple repair of the anterior talofibular ligament. If the pes cavus foot type is flexible without a rigid plantarflexed first ray and only mild heel varus, one would normally forgo a cavus foot reconstruction. Gait examination will allow for an accurate assessment of the impact and severity of the cavus foot. Also evaluate for suprapedal deformity, including tibial varum and collagen disorders with resultant ligament laxity.

One can consider custom orthotics postoperatively as orthoses are far less intrusive than doing a cavus foot reconstruction. This is not meant to discourage surgical correction of the cavus foot but rather to be sure correction is necessary. If there is a moderate to severe deformity with rigid osseous malalignment, realignment through osteotomy (i.e. Dwyer calcaneal osteotomy/lateral displacement calcaneal osteotomy, dorsiflexion wedge osteotomy of the first ray/dorsiflexory Lapidus) or fusion (corrective subtalar fusion, dorsiflexory Lapidus) is certainly warranted to avoid certain failure of isolated ligament reconstruction.
Also, if the patient has had previous stabilization of the ankle and has a cavus component, I would err on the side of correcting the deformity with osseous realignment and tendon balancing to avoid a secondary failure with the second attempt at stabilizing the lateral ankle.

Assessing And Addressing Intra-Articular Pathology

For patients with intra-articular pathology, concomitant intra-articular joint derangement is common. The vast majority of patients with chronic ankle instability have anterior ankle joint line tenderness and soft tissue impingement/scar tissue in the anterior compartment of the ankle, osteochondral lesions or loose bodies.^6,7

Choi and colleagues demonstrated a 96.9 percent (63 of 65 ankles) incidence of intra-articular lesions upon arthroscopic evaluation with patients having an ankle arthroscopy with an open modified Broström.⁶ This included an 81.5 percent incidence of soft tissue impingement, a 38.5 percent incidence of ossicles at the lateral malleolus, a 29.2 percent incidence of syndesmosis widening, a 23.1 percent incidence of osteochondral lesions of the talus and a 10.8 percent incidence of osteophyte formation.

DiGiovanni and coworkers demonstrated similar findings in a separate study.⁷ The authors utilized an open arthrotomy to evaluate 61 patients for intra-articular injuries. No patients had isolated lateral ankle ligament insufficiency. Every patient had notable additional pathology. Researchers identified 15 different concomitant injuries including anterolateral impingement lesions in 67 percent of the patients in the study and ankle synovitis in 49 percent of the patients. The literature and my experience lead me to perform an arthroscopic evaluation/debridement on almost every lateral ankle stabilization procedure.

Arthroscopy And Lateral Ankle Stabilization: What You Should Know

In only rare instances should surgeons exclude arthroscopy as part of routine lateral ankle stabilization. Routine arthroscopic evaluation allows for accurate assessment of any and all concomitant intra-articular injuries including, most commonly: impingement lesions, synovitis, osteochondral lesions, and loose bodies derived from the lateral malleolus.⁶

Take care to plan out incisions to avoid iatrogenic intermediate dorsal cutaneous nerve injury. Employ efficient arthroscopic techniques to limit time for fluid extravasation, which can distort the anatomy of the lateral ligaments during an open lateral ankle reconstruction. Don’t spend any more than 10 to 15 minutes on routine arthroscopic debridement.

For arthroscopic debridement in these patients, I prefer to utilize the following:

• Ipsilateral thigh tourniquet at 250 mmHg
• Ipsilateral hip bump to rotate the ankle internally
• Ipsilateral thigh holder with the thigh at 45 to 90 degrees of flexion
• Non-invasive distractor
• Insufflation of the ankle with 10 cc of 1% lidocaine with epinephrine via an 18 g spinal needle
• Standard anteromedial and anterolateral portals
• Arthroscopic pump (one can adjust settings to optimize visualization and limit fluid extravasation outside the joint)
• 4.0 mm arthroscopic camera and 3.5 mm shaver (sometimes I use a Lanza shaver (ConMed), which is 4.1 mm)

The use of non-invasive distraction is my preference based on experience. Common findings of meniscoid bodies, loose bodies and delaminated/fibrillated cartilage deeper in the joint are often inaccessible without distraction. The dorsiflexion method is an alternative method to safely perform arthroscopy as well but it is fairly limited to anterior compartment inspection/debridement.⁸

Keys To Performing An Arthroscopic Broström Procedure

The arthroscopic Broström is a minimally invasive procedure that is becoming popular.⁹ Recent clinical and biomechanical studies support arthroscopic lateral ankle ligament reconstruction as a viable alternative with similar results to open Broström-style repairs.^10–12

In a series of 38 patients available for follow-up at a mean of 9.8 years, Nery and colleagues found American Orthopaedic Foot and Ankle Society (AOFAS) scores were good to excellent in 94.7 percent of patients following the arthroscopic-assisted Broström Gould procedure for chronic ankle instability.¹¹ As long as there is an absence of severe laxity of the anterior talofibular ligament, avulsion fracture fragment off the distal fibula/intra-ligament calcification or concomitant peroneal tendon pathology, I will consider an arthroscopic Broström procedure for surgical repair.

When performing an arthroscopic Broström, one should have good arthroscopic skills and a helpful assistant. Preoperative topographical anatomic mapping is very helpful in preventing iatrogenic nerve and tendon injury, and ensuring accurate placement of sutures for the repair.

One should remove all soft tissue from the anterior distal fibula. This is aided greatly with the use of an ArthroWand (45 degrees) to facilitate removal of the synovium and get to osseous surface of the distal fibula. Surgeons can slightly increase the size of the anterolateral portal for the introduction of anchors.
Place the inferior anchor first, approximately 1 cm from the tip of the fibula and place the second anchor about 1 cm proximal to this (still beneath the ankle joint line). One can place these anchors with the noninvasive distractor in place but following this part of the procedure, remove the distractor.

Pass all sutures from the anchors directly out of the anterolateral portal. Use a CTX needle (Ethicon) with a lasso to sequentially pass each suture arm appropriately through the anterolateral portal. Graze the talus so you know you are in the appropriate intracapsular plane. Drive the CTX needle distal and anterior in the direction of the anterior talofibular ligament attachment on the talus, and pass the needle through the skin with four respective exit portals created with the suture (do this in sequential order with the top two exiting most dorsally) and spaced out about ¼-inch apart.

Make a small connecting incision between the middle two sutures only through the skin. Utilize a probe to drag the top (most dorsal), and bottom (most inferior) suture to the central, open stab incision. Make sure the suture holds well and then have an assistant hold the foot in a dorsiflexed/everted position and secure each suture with hand ties, making sure to seat the suture well so it holds. Check the tension of the anterior talofibular ligament by doing an anterior drawer test and ensure the repair is satisfactory. Trim the suture ends.

The Broström and modified Broström procedures for open lateral anterior talofibular ligament repair are time-tested and demonstrate great results.¹² However, one should be guarded in interpreting some of the data as the population studied is critical. At an 8.7-year follow-up, Maffulli and colleagues found an AOFAS score improvement from 51 to 90 points after the combination of arthroscopic ankle debridement and a simple Broström procedure (no inferior extensor retinaculum advancement).¹⁴ However, their study was in an athletic population and only 58 percent (22 of 38) of patients were able to return to sport at a pre-injury level.

Overall, the data still supports Broström techniques and a recent systematic review demonstrates a 1.2 percent revision rate.¹⁵ Although long-term data is scarcer on newer techniques for repair, in the athletic patient population, a primary repair with anchors or InternalBrace (Arthrex) may be more appropriate. These newer techniques may offer expedited recovery and less recurrent ankle instability and pain.

Pertinent Pearls For Utilizing Anchors In The Distal Fibula

My preference is for the utilization of anchors in the distal fibula. Numerous anchor devices are commercially available with and without preloaded non-absorbable sutures, and they can work well. A midline incisional approach centered over the distal lateral fibula with a curvilinear extension anteriorly over the sinus tarsi works very well.

Make an incision roughly 4 cm in length through the skin. Use a medium to large key elevator to create a tissue plane at the appropriate depth of the fibular periosteum and anterior lateral ankle joint capsule, lifting the subcutaneous tissue and skin in one full thickness flap (avoid undermining). Create an anterolateral arthrotomy at the ankle joint, erring on the side of the fibula and incising the native anterior talofibular ligament. Take care not to delve too far inferior as the calcaneofibular ligament and peroneal tendons can be easily injured.

Sharply elevate the periosteum off the distal fibula. Decorticate the distal fibula with a rongeur for reattachment of the anterior talofibular ligament with anchors. Typically, one would place two small anchors in the distal anterior fibula with suture and needle attached. Manually load the anchors by hand to ensure they are seated well. Then pass the suture through the cuff of healthy remnant anterior talofibular ligament and ankle joint capsule.

After passing all the sutures, check to ensure the suture adequately reefs the anterior talofibular ligament and joint capsule to appropriate tension. Then remove the needles from the suture. An assistant holds the foot in a dorsiflexed and everted position, and one secures the sutures with hand ties. Depending on stability with this construct, one can then advance the inferior extensor retinaculum to supplement the repair.

Emerging Insights On The InternalBrace

One popular emerging option allows patients with ankle sprains to get back to activity very quickly and helps prevent recurrence.¹⁶ The InternalBrace utilizes bioabsorbable anchors with fiber tape, tensioned off the fibula or the talus. One can place the InternalBrace in an intracapsular or extracapsular manner. The primary advantage with the InternalBrace is early return to activity. Waldrop and colleagues demonstrated the reason a more effective repair for the anterior talofibular ligament was necessary as suture repair and the use of suture anchors in the fibula or talus have significantly less strength than an intact anterior talofibular ligament.¹⁷

Purely for placement ease, my preference is intracapsular placement of the InternalBrace. This device can be very helpful in several situations. Patients who may benefit from this option include those with severe ankle instability on examination, those in need of a secondary repair, those with ligament laxity for any reason (i.e. benign hypermobility, collagen disorders such as Ehlers Danlos syndrome) and the athletic patient population. Utilization of the InternalBrace does not permit lax anatomic repair of the ligament or effectively replace a lack of adequate tissue for repair. Good technique for imbrication of the anterior talofibular ligament and anterolateral ankle joint capsule is mandatory. Insufficient tissue for repair is an effective contraindication to the use of this device and one should employ a tendon autograft/allograft procedure.

To summarize a few key points and pearls with the InternalBrace …

• Intracapsular placement is much easier.
• Do not overtighten the InternalBrace. Avoid this by having the foot in neutral position in the coronal plane and at slight plantarflexion (about 20 degrees).
• Tensioning from the fibula to the talus is easiest.
• Do not use the device when there is inadequate tissue to repair the native anterior talofibular ligament.
• For patients with insufficient native tissue, employ an autograft (split peroneus longus), allograft (peroneus longus), or synthetic graft (i.e. Artelon graft (Artelon)) with bone tunnels/suture anchors.

Essential Tips On Revision And Secondary Repair Of Ligaments

Failure is not common with primary repair of the anterior talofibular ligament. Recent advances in technology and technique refinements are likely to demonstrate superior outcomes, especially in the active patient population, and allow for an earlier return to activity. When failure does occur, it is critical to determine the cause of failure and subsequent instability/pain.

The most common biomechanical predisposition for latent instability is pes cavus. Osseous realignment and tendon balancing are crucial in secondary cases if the lack thereof drives primary failure. Additionally, ruling out ligament laxity is important. If the patient is active, Mafulli and colleagues demonstrated that despite decent recovery with scoring outcome measures, less than 60 percent of patients return to sport in the athletic patient population.¹⁴

In revision cases, consider newer techniques and products, such as Artelon with anchors or the InternalBrace for primary chronic ankle instability. Also consider these techniques as primary procedures in active patients to prevent the failure and need for secondary repair.

In general, I tend to shy away from non-anatomic repair technique such as tendon transfer techniques due to donor site morbidity, larger surgical exposure, over-tensioning, etc., in both the primary and revision setting. The most common technique I employ is utilizing Bio-Tenodesis screws (Arthrex) in the talus, fibula and calcaneus with peroneus longus allograft (pre-tensioned on an Acufex GraftMaster (Smith and Nephew)).

As I stated earlier, the long-term consequence of chronic ankle instability and repetitive sprains is often ankle arthritis, typically with incongruent ankle varus. In these cases, I also employ tendon allograft technique with Bio-Tenodesis screws. Typically, I do this in a staged fashion with the index procedure with the following steps:

1. Ankle arthrotomy with removal of obstructing periarticular osteophytes
2. Mobilization of the ankle joint in the coronal plane to neutral
3. Placement of a cement spacer in the ankle, often with a large Steinmann pin or a 4.5 mm fully threaded screw
4. Osseous realignment procedures such as fusions or osteotomies (if necessary)
5. Tendon balancing procedures (i.e. posterior tibial tendon transfer to the peroneals)
6. Ligament reconstruction with allograft tendon and the Bio-Tenodesis kit

In Conclusion

Chronic ankle instability manifests more often than previously thought. When patients fail conservative care, an MRI should confirm ligament insufficiency/damage. Determine foot type and possible ancillary pathologies. Determine an appropriate surgical plan, which may include arthroscopy (essentially 100 percent of the time), bone and soft tissue balancing if necessary.

Modern techniques are evolving. The InternalBrace and Artelon graft are promising new modalities that may offer earlier return to activity and better long-term results with less recurrence than simple suture repair techniques in primary repairs of chronic ankle instability. These devices may allow athletes to return to sport in primary repairs as well. In my experience, when it comes to secondary repairs, I would recommend utilizing autograft/allograft tendon or Artelon for tissue augmentation most of the time.

Ignoring the pathology with chronic ankle instability or inadequate stabilization can lead to long-term consequences such as ankle osteoarthritis, often with incongruent varus deformity and anterior talar listhesis.

Dr. Seidenstricker is in practice at New Mexico Orthopaedics in Albuquerque. He is an Associate of the American College of Foot and Ankle Surgeons.

References

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