Arthroscopic Monopolar Radiofrequency Thermal Stabilization: Can It Have An Impact For Chronic Lateral Ankle Instability?

One component of my residency training was extensive arthroscopy training by one of the leaders in podiatric arthroscopy, Richard Lundeen, DPM. He was an innovator in this field and I learned much from him.

One of the procedures he started doing while I was a resident was an arthroscopic lateral ankle stabilization using an arthroscopic staple. Over the years, I became a big fan of the modified Brostrom procedure with or without an arthroscopy of the joint. I grew to believe this was a more predictable procedure, which yielded excellent stability while maintaining as normal a range of motion as possible.

The one thing I did not like when doing an arthroscopy with a modified Brostrom was the fluid infiltration of the soft tissues that occurs during the arthroscopy. This would make the open procedure dissection much more difficult.

Then last year while I was lecturing at the American Podiatric Medical Association National Meeting for an arthroscopic workshop, Lawrence Oloff, DPM, (who was the workshop coordinator) presented a video lecture on arthroscopic monopolar radiofrequency thermal stabilization for chronic lateral ankle instability. Then at our annual Indiana Podiatric Medical Association Meeting, Ron Raducanu, DPM, also presented a lecture on this topic. My interest had been piqued and it was time for me to give this procedure a try.

I have thus far performed three of these procedures and have been very pleased with the results. During the diagnostic portion of the arthroscopy, I always do a talar tilt stress test. I feel this is much more accurate than a radiographic examination for a talar tilt without the patient under anesthesia and the potential splinting and guarding of the affected ankle joint. When there is lateral widening of the ankle joint with an inversion stress and the parallel relationship is lost, this is considered abnormal.

With this arthroscopic lateral ankle thermal stabilization, one can perform the same procedure to evaluate its effectiveness. I have seen restoration of the normal parallel relationship between the tibia and talus. This occurs when one applies thermal energy to connective tissue, which causes a linear reduction of the crossed-linked collagen fibers and results in shrinking of the tissue.1 The amount of shrinkage ranges from 50 to 60 percent range of the original length at 65º to 75ºC.1 This occurs with a monopolar radiofrequency setting between a 30 to 40 W power setting. Additionally, there is postoperative scar tissue contracture, which results in further increased stability.

In Oloff’s 10-patient study, the average preoperative AOFAS ankle-hindfoot score was 58.3 and the average postoperative score was 88.1 for a 10-patient study.1 Eight of the 10 patients returned for long-term anterior drawer stress exams, which were all negative relative to the preoperative examination. Finally, all patients reported increased subjective stability and were able to return to desired activities. This was a small, preliminary study, which showed that this procedure was a less invasive option for chronic lateral ankle instability.1

It must be clear that this study and both of the aforementioned lectures indicate that this procedure is indicated for mild to moderate chronic lateral ankle instability. Severe ankle instability requires an open procedure as does any case with calcaneofibular ligament involvement. This procedure is indicated for anterior talofibular ligament and lateral capsular injuries. I think it is important to perform a diagnostic and operative arthroscopy to debride the joint and evaluate for pathology, and do the thermal stabilization at the end of the procedure.

In terms of postoperative management, I emphasize non-weightbearing for two weeks with subsequent assisted weightbearing in a cast boot for four weeks. Once patients come out of the cast boot, I place them in an ankle brace and gym shoe for two weeks. Patients are then allowed to return to unrestricted activities at eight weeks postoperatively. One can recommend physical therapy as needed.

If you are an experienced arthroscopic surgeon, I would suggest giving this procedure a try. It will help you if you know the sales representative for the arthroscopic equipment company you use as the sales rep will be able to provide insight from other surgeons who have used this equipment.

I think you will find this a welcome addition to your surgical armamentarium.

Reference

1. Oloff LM, Bocko AP, Fanton G. Arthroscopic monopolar radiofrequency thermal stabilization for chronic lateral ankle instability: a preliminary report on 10 Cases. J Foot Ankle Surg. 2000; 39(3):144-153.