Lateral ankle stabilization with a polyester fiber construct implant as a revision for failed primary lateral ligament reconstruction

Objective: The aim of this study is to demonstrate an original technique in which a stable construct is made by fibular and calcaneal bone tunnels producing a figure of 8 with a Polyester implant as revision for failed primary ligament reconstruction. Methods: This is a retrospective study of 19 patients with persistent lateral ankle instability diagnosis after a primary ligament repair treated between 2011 and 2019. The surgical technique is described in detail in which stabilization of the lateral ankle is performed. 11 men and 8 women with a mean age of 30.94 years (15-53). Follow up was 29.05 months (6-109). Pre and postoperative AOFAS ankle score were used as well as an AVS and a satisfaction questionnaire. Results: There was a significant improvement in AOFAS score, 76.31 to 91.47 (<0.001). All the patients except one, stated to have a stable ankle and be Very satisfied (16) or satisfied (2) with the procedure. No infection was presented in any patient. Conclusion: This technique is a reliable alternative in patients in which primary ankle ligaments have failed and no autograft or allograft are wanted to be used. Level of Evidence V; Therapeutic Study; Expert Opinion.


Introduction
Currently, most of the lateral ankle instabilities are treated with an anatomical Broström procedure described in 1966 (1) and with all the modifications and augmentations developed since then either open or arthroscopic.
Good to excellent results have been published for this techniques as primary reconstruction of the ankle lateral ligaments (2,3) and no study has proved superiority in between open or arthroscopic conduct, both of them having excellent results (4) .
Factors leading to failure of this primary repair include a brand-new trauma, hindfoot varus and also overuse associated with microtrauma and final failure. Also hyperlaxity is considered an important topic for this situation (5) .
In this article, we will describe a Surgical Technique in which we produce bone tunnels on the fibula and calcaneus in order to do a construct to stabilize the lateral ankle of 19 patients with a Polyester implant.

Methods
This is a demonstration of the surgical technique and a retrospective study of 19 patients with history of ankle instability that previously had a lateral ankle ligament reconstruction and persisted with such instability that were operated with this technique from January 2011 to January 2019.
None of the patients on this study were professional athletes.
Exclusion criteria: patients with an advanced ankle arthrosis with limited ankle range of motion.
The failure of the primary surgery was determined as follows: 1. Patients claiming to have instability as or near as before the first surgery and not having a reliable ankle for everyday and recreational activities; 2. Physical exam with clinical instability sings (anterior drawer and talar tilt); 3. Evident Positive Ap X rays with stress. Follow up was of 29.05 months  in which the AOFAS scale was filled and physical exam was made looking for clinical instability and stress X rays.

Surgical technique
With the patient in prone position, sedation and popliteal block on the affected limb are completed. Also, a thigh tourniquet was applied.
An incision is made starting 2cms above the tip of the fibula on the center of it down to the sinus tarsi until 1cm of the anterior calcaneus process is seen.
When there was a procedure different than classic Broström, the tissue or implant (native Peroneal brevis, tendon graft or fiber tape) was removed.
A bone tunnel with a 3.5mm drill is done 1.0 to 1.5cms above de tip of the fibula from anterior to posterior in a horizontal line (Figure 1), care is taken to protect peroneal tendons. Then, dissection is carried down passing the sinus tarsi to the anterior aspect of the subtalar joint and the calcaneus is exposed in a way we can see the dorsal anterior tuberosity without exposing the calcaneocuboid joint (CC joint).
The second tunnel is produced on the most posterior aspect of the anterior tuberosity just anterior to the subtalar joint which must be protected at all the time.  Then we use a ligament prosthesis manufactured out of polyester yarn in the form of bands with lateral edges rolled inside with a 3mm of width.
So, this "new ligament" is passed through the tunnels in a figure of 8 as show in Figure 3.
Just before tightening the knot, the ankle is placed in neutral position with no valgus or varus at all. Then we do 2 simple knots and use cyanoacrylate glue to fuse it.
Before closing the wound, remaining tissue around the anterior fibula is closed, we never used anchors at this stage. In most of the cases the Anterior talo-fibular ligament (ATFL) is not touched and just let it in place as it was.
We close the wound deep and superficial with absorbable suture and skin with non-absorbable.
A suropodalic splint is left for 2 weeks with non-weight bearing and then the patient can walk with a boot for 3 weeks so at 5 weeks postoperative he or she can walk with no orthopedic device.
Sutures are removed at 3 weeks postoperative and physical therapy is started at 6 weeks.

Results
AOFAS Ankle Score improved from pre-op 76.31 to 91.47 and this was statistically significant (<0.001) ( Table 1, 2 and Figure 4). Patients were followed for an average of 60.15 months (96 to 12) and were asked to fill the AOFAS scale on the final follow up (January 2020). AVS was 4.3 preop and 0.5 postoperative, this could be explained because pain was not the main symptom on this group of patients but was improved as well anyway.
Also, X rays with varus stress were taken postoperative to compare with the initial one, in all patients there was an evident difference on the talar tilt.
Clinically there was a very stable ankle on the physical exam and patients expressed security during uneven surfaces as well as stability during recreational sports and long-distance walking.
Concomitant procedures were: 9 ankle arthroscopies of which 4 had microfractures done.
Complications included: wound delayed healing in 2 cases that finally healed in 8 weeks with no infection. Scar hypersensitivity was present for 3 months in 5 of the 19 patients that eventually disappeared.
1 patient had a rupture of the implant at 18 months of surgery that required a second revision where we could document the implant rupture at the level of the calcaneal tunnel. Her very first surgery was a Broström with Fiber tape, she also had poor bone quality due to intense smoking habit and severe peroneal brevis tendon weakness which we think it led to a more sever instability, an Evans Procedure was done in this case with a mediocre outcome.

Disscusion
The kind of construct used in this article is an original idea but is clearly influenced by the Chrisman Snook/Watson Jones fashion (6,7) .
Non anatomic procedures like this tend to be discarded because of over tightening subtalar motion (5) . In none of our patients at the time for follow up, we had this kind of claim, in the other way they confirmed to have a very stable ankle and no ankle joint deterioration was seen in x rays.
Also, it is important to report that in 6 patients of this group, there was an intraoperative gross subtalar instability that could be the cause of the persistent instability sensation and this was clearly improved postoperative.
Regarding this topic, there are publications that believe that the sinus tarsi is a very important proprioceptive zone, due to sinus tarsi biopsy, Morsy and Filler (8) found that histological examination revealed the presence of large amount of neural elements (mechanoreceptors) together with abundant elastic fibers in all of the excised subtalar tissues.
Cho et al. (9) have done revision of failed Broström with a new augmented Broström with a fiber tape with very good results having only one failed case after this second surgery requiring a 3rd surgery where they used an allograft. This numbers are very similar to the ones of this study in which we only had 1 patient failing due to implant rupture.
It is recommended to do non anatomic surgery (allograft or autograft) in a previously failed anatomic reconstruction because it is a poor prognosis to repeat it.
We think that not using patient´s healthy tissue like a peroneal, plantaris tendons, etc., or using cadaveric graft is an advantage because of the morbidity associated with it.
There was never a biological reaction to the implant or deep infection that required medical or surgical treatment.
The limitations of the study are a not very large patient population and despite the good results we don't really know what happens in a biological level with the implant and its bio-integration to bone.
Having a failed Broström procedure should always make us think about a new and more aggressive surgical act, allograft or autografts are very accepted conducts with very good results (5) , but not free of donor site morbidity and possible immunological reaction or deep infection.

Conclusion
The present technique is an alternative for the revision surgery for lateral ankle stabilization due to strong construct, no biological reaction.