Ankle “sprains” are one of the most common injuries sustained by athletes, and most of these involve the lateral ligament complex (LCL). Most patients will make a full functional recovery when treated with a period of relative rest and physical therapy. However, as many as 20% of such patients will develop chronic symptomatic ankle instability.

There are a number of surgical options for these patients, and they have been divided into “anatomical” (the torn ligaments are repaired, such as the Brostrom’s procedure) and “non-anatomical” (tenodesis procedures where tendons are rerouted to perform a similar function to that of the dysfunctional LCL). The “anatomical” procedures have been significantly modified since Brostrom’s original description, and now the procedure is often performed using non-absorbable sutures and sutures anchors. In essence, these procedures use a non-biological internal splint system, which runs along a similar course to that of the natural ligaments and support the ligaments while they heal. Often, when the patient has had chronic lateral instability for periods of 3 months or more, there is significant degeneration within the torn ligaments and the quality of the end product after healing may still be weak. Therefore a primary repair without reinforcement is likely to fail. Hence these modifications of the Brostrom procedure are not purely anatomical as they rely, initially at least, on non-biological reinforcement.

Post-operatively the ankle is often held immobilized for up to 4 weeks post surgery. Weight bearing in an ankle support orthosis is progressed to full weight bearing between weeks 4-6, and running may be possible within 12 weeks of surgery. Full return to pivoting sports is usually not possible until 16 weeks post surgery.

The modified Brostrom-Gould (MBG) procedure is widely accepted the most appropriate operation to perform on patients with ankle instability. However it is unsuitable for patients with recurrent ankle instability following previous surgery, patients with generalized ligamentous laxity, high demand and heavy patients, as well as those patients in which preservation of full ankle range of motion is essential (swimmers, gymnasts, dancers, etc.) This “consensus” of opinions is based on weak scientific data.

Reconstructive procedures on the ankle use a graft taken from the patient or donated. The former is associated with potential complications at the harvest site, and the latter with the small risk of disease transmission. However, these procedures are becoming more popular and have better outcomes than the MBG.

Reconstructing the LCL of the ankle using an artificial ligament may achieve the same outcomes without the risks associated with a biologic graft. The use of these artificial ligaments within a joint (such as for ACL reconstructions in the knee) is associated with a risk of synovitis and later osteoarthritis of the joint. This is not the case when the LARS is used in a position outside of the joint, such as ankle lateral ligament reconstruction.

Artificial ligaments are now available to reconstruct torn ligaments in multiple joints of the body, and the LARS is one example. This artificial ligament can be used to reinforce a repair of the LCL. Effectively this is a reinforcement of the original Brostrom’s procedure using an artificial ligament rather than the various “modifications” that have been described.

One of the potential advantages of using the LARS system is that the stronger construct can withstand earlier mobilization and a quicker return to full training and competition. The advantages of this to the competitive athlete, or keen participant, are obvious.

However, use of the LARS in this situation is experimental and clinical studies need to verify that it is more efficacious and more cost-effective than the current gold standard procedure, before it can be regarded as a proven treatment.

Currently I am conducting a randomized controlled trial to compare the outcomes of the modified Brostrom’s procedure with the use of a LARS to reinforce a primary repair of the LCL for patients with chronic lateral ankle instability. Patients who satisfy the inclusion and exclusion criteria below, and who provide informed consent to take part in the study are enrolled.

Inclusion criteria

1. Chronic ankle instability which has failed to improve with 3 months of supervised conservative management (rest, bracing or taping, proprioceptive/ balance retraining, and strengthening work)
2. Skeletally mature patient
3. An MRI proven rupture of the anterior talofibular ligament and/or calcaneofibular ligament
4. Physical signs of LCL dysfunction
5. Medically fit for surgery
6. Willing to sign an informed consent for either procedure

Exclusion criteria

1. generalized ligamentous laxity
2. Unsuitable for a MBG procedure
3. Previous surgery on the injured ankle
4. The presence of an osteochondral lesion or other fracture ankle dislocations or concomitant MCL and/or distal tibiofibular joint injury any contraindication for surgery (local or systemic)
5. Unable or unwilling to provide written informed consent in English

Randomization

As soon as the patient has willingly enrolled in the study, and has been booked and consented for either procedure, the patient is randomly allocated to either undergo the MBG procedure, or the LARS augmentation of the LCL repair.

Surgical techniques

An arthroscopy of the ankle is routinely performed before the ankle stabilization. The Gould modification of the Brostrom’s procedure is performed in the standard manner, using suture anchors and non-absorbable sutures to repair the LCL to the fibula with imbrication of the capsuloligamentous structures (ATFL and CFL), and reinforcement using the inferior extensor mechanism. The LARS procedure involves performing a primary repair of the capsuloligamentous structures using bioabsorbable sutures, and reinforcement with the LARS ligament running along a similar course to the native ankle ligaments.

Assessment tools & outcomes of interest

1. The Foot and Ankle Outcome Score (FAOS) – is a validated patient scored outcome applicable to patients with ankle instability – completed at baseline, 12 and 24 months post surgery. The change in scores over time is a measure of improvement resulting from surgery.
2. Time to return to full pre-injury status
3. The nature and incidence of complications.

Blinding

Patients will not be routinely informed as to which procedure they underwent, however the incisions for the two procedures are different because of the extra incision required for distal fixation of the CFL when performing the LARS. Ethically it is not justifiable to make an extra sham incision when this incision is not required. However, if the patients wish to know, they will be told which procedure they had. Patients may be able to tell from the post-operative x-rays and invoices from the hospital, which procedure they underwent. The independent assessor measuring the ROM in the ankle was a specialty trained physiotherapist, but was not routinely informed which procedure the patient underwent. Blinding of the surgeon was obviously not possible.

Complications

The occurrence of any complications is noted as well as the treatment required.

Analysis of results

The outcomes of interest in the two groups will be compared using statistical analysis with the level of significance set at P<0.05. Once there is sufficient power in the study, the results will be analyzed and the paper submitted for publication.

Results

A total of 34 patients have been enrolled in the study, 16 were randomized to the LARS group and 18 to the modified Brostrom Gould procedure. Statistical analaysis (ANOVA test) demonstrated a significantly better outcome for the LARS in all five sub-scales of the FAOS score. The study is on-going.

Complications

LARS group – one patient had to have the screw in the fibula removed as it was causing irritation of the adjacent tendons. Removal of the screw solved the problem. Another patient developed a superficial infection that required wound debridement and a period of intravenous antibiotics in hospital. Both patients have had an excellent final outcome.

MBG group – one patient sustained a recurrent ankle sprain within 3 months of the original surgery. Another patient developed a “pseudoaneurysm” which required a return to theatre for removal of the pseudaneurysm but has had an excellent final outcome.

Presentation

The pilot paper was presented at the Scientific Meeting of the ACT branch of the Australian Orthopaedic Association, in November of 2011.