Chronic Plantar Fasciitis: Is Cryosurgery The Answer?

   Cryosurgery is the specialized field of using extremely low temperatures (controlled by a handheld probe) to destroy pathological tissue. This technique has been used for decades to treat malignant tumors of the prostate, liver and other organs.1-3 Cryosurgery is also gaining acceptance in dermatology, plastic surgery, urology and pain management.4-6 Now clinicians are using this technology to help manage common foot and ankle conditions.7-9    I have been performing cryosurgery for plantar fasciitis for approximately three years with excellent results. All of my patients who have had this procedure previously tried other treatments, including multiple steroid injections, NSAIDs, orthotics/arch supports and physical therapy, without success. Some have used night splints. Two patients had shockwave therapy, one underwent an endoscopic plantar fasciotomy and another had a percutaneous medial fascial release.    After undergoing cryosurgery, approximately 90 percent of the patients had complete resolution of pain or had only minor residual pain that required no treatment.    There have been very few complications with cryosurgery. Infection has been rare. The most common sequella has been the development of pain in another location of the heel or arch. This is the result of a postoperative compensatory gait and usually resolves in three to four weeks after the procedure. If patients receive this treatment, this compensatory fasciitis responds well to a course of NSAIDs, low dye taping or over-the-counter arch supports. Although the cryosurgery literature suggests that the analgesic relief with this procedure is temporary, a three-year follow-up has revealed virtually no recurrences of the plantar fasciitis.

Understanding The Scientific Principles Behind Cryosurgery

   How does cryosurgery work? The basic principle of current cryosurgery systems is based on forcing gas under pressure of between 600 and 800 psig between the inner and outer tubes of the cryoprobe. The gas is released through a small opening into a chamber at the tip of the probe. As the pressurized gas is released into the chamber, it expands and results in a rapid drop in temperature. This is referred to as the Joule-Thompson effect and results in an ice ball forming at the uninsulated tip of the probe.10 The temperature can reach - 70ºC and the size of the ice ball can range from 3.5 mm to 10 mm depending on the amount of tube that is not insulated. Because these units are a closed system, no gas escapes from the cryoprobe.    In addition, the units can contain nerve stimulator capability and the cryosurgery systems by Cryotech (Cryomed Group Ltd.) have programmable freeze cycles and utilize multiple nitrous oxide tanks with automatic conversion from an empty to a full tank.    When one performs cryosurgery on peripheral nerves, the process is referred to as cryoneurolysis or cryogenic neuroablation. The nerve cells are destroyed as a result of the freezing process. The cold causes destruction of the axon with breakdown of the myelin sheath and Wallerian degeneration. This breakdown of the axon is more complete with repeated freezing of the nerve followed by periods of thawing. However, be aware that excessive freezing can lead to gross destruction of all tissues and prevent regeneration.4    Preserving the basic structural components of the peripheral nerve, the epineurium and perineurium, along with a very limited inflammatory reaction differentiate cryoneurolysis from other forms of neurolysis. An intact epineurium and perineurium permit ordered axonal regeneration and prevent the formation of amputation neuromas.    Given that the axons can regenerate at the rate of 1 to 3 mm per day, the analagesic or anesthetic effect of cryoneurolysis can be considered temporary. Cellular necrosis following cryoneurolysis results in the release of tissue proteins and this facilitates a change in protein antigenic properties. This could result in an autoimmune response specific to the cryolesion. This autoimmune response might explain the prolonged analgesic relief that lasts longer than the time required for regeneration of the axon.1,2

Key Insights On Performing The Cryosurgery Procedure

   The most important aspect of a successful cryosurgery procedure for the treatment of plantar fasciitis is locating the exact area of heel pain. One can accomplish this by simply palpating the heel and marking the painful area with a surgical pen. If one locates several areas of pain, mark them all and measure the combined diameter. Regardless of the diameter, the target area for the tip of the cryoprobe is the central area of greatest pain.    Generally, the ice ball that forms on the plantar aspect of the heel with the Cryostar plantar fascial probe (Cryomed Group Ltd.) is approximately 3.5 by 2.5 cm in diameter. This is much larger than the 1 cm ice ball that forms on the exposed tip of the probe. The prevailing thinking is the dense fibrous tissue of the fascia may act as a thermal barrier, resulting in a larger ice ball. Keep in mind that areas of pain larger than this may require two separate approaches.    One should inject approximately 4 cc of 1% lidocaine HCl with epinephrine 1:100,000 into the heel from either the medial or lateral aspect of the heel, whichever is closest to the area of pain. A nerve block is not necessary. Prep the surgical site and drape the foot. Using a #65 Beaver Blade, make a 3 mm percutaneous incision. Clinicians may use a trocar to separate the tissue but it is not necessary as one can easily insert and advance the cryoprobe between the tissue planes without the trocar.    Insert the probe from the incision site directly inferior to the plantar fascia and advance the tip of the probe to the fascial pain site. Using the Cryostar plantar fascial probe, it is usually adequate to emphasize a two-minute freeze cycle and 30-second defrost followed by another two-minute freeze cycle. The freeze cycle can vary based on the size of the heel and the area of pain but I would not recommend a cycle longer than two minutes and 30 seconds.    For a large area of pain extending the width of the fascia attachment, one can insert the probe from medial to the central lateral aspect for the first freeze cycle. Then withdraw the probe and reinsert it at the junction of the central and medial bands of the plantar fascia for the second cycle. This technique permits coverage of a larger area without increasing the length of the freeze cycles. Excessively long freeze cycles can result in tissue necrosis, delayed healing and abscess formation at the incision site.    One can irrigate the wound with saline but I prefer using a mixture of 2 cc of 1% lidocaine and 0.25 cc of 0.4 mg dexamethasone. Apply antibiotic ointment to the incision with a mild compression dressing. No sutures are necessary.    The cryosurgery procedure provides ablation of the divisional branches of the medial calcaneal nerve medially and the branches of the lateral calcaneal nerve laterally.    In terms of contraindications, one should not use cryosurgery in areas of infection. It is also contraindicated for patients who have peripheral vascular disease or Raynaud’s disease.

What Does Postoperative Care Entail?

   Following the cryosurgery procedure, one should instruct patients to reduce their activity significantly for about three days. They can drive and walk around the house but should avoid excessive weightbearing for the first 72 hours. They are permitted to change the dressing two days after the procedure. At that time, they can get the foot wet and subsequently apply antibiotic ointment and a Band-Aid. They should do this until the 3 mm incision heals. The incision usually heals in about three to four days.    Most patients report virtually no pain 24 hours after the procedure due to the effects of the cryogenic neuroablation and the steroid irrigation. Postoperative pain usually ranges from 0 to 3 out of 10 and most patients report that any discomfort they have is related to the procedure and not the original plantar fasciitis.    Instruct patients to take NSAIDs for three to five days postoperatively. Generally, the discomfort will increase slightly as the patient becomes more active during the first postoperative week. Pain typically dissipates during the second week with complete resolution by the end of the week.    The most common adverse effect of the cryosurgery plantar fascial procedure is some of the patients will develop discomfort on another location of their heels or arches. This is the result of patients favoring the medial aspect of their heels by supinating their feet and straining another portion of their fascias. When this happens, it is usually the lateral band that becomes inflamed but it can also occur at the junction of the arch and heel. This compensatory fascial strain usually resolves in one to two weeks with taping, NSAIDs or the use of arch supports. These patients will rarely require a steroid injection.    Studies are currently being conducted to see if performing routine cryogenic neuroablation at the entire proximal attachment of the fascia, rather than just at the area of pain, will reduce the incidence of the compensatory fascial strain.

Case Study One: When A Sedentary Patient Reports Great Pain Walking After Rest

   A 58-year-old sedentary female with a body mass index (BMI) of 32 presented to the office complaining of left heel pain that she had for six months.    She said the pain was greatest when she walked after a rest period. She graded the pain as 8 out of 10 in terms of severity. The patient had previous treatment consisting of at least four corticosteroid injections, shoe modification, orthotics, NSAIDs and physical therapy with no significant improvement. Her foot structure was within normal limits with no gross abnormalities although mild pronation was evident. Her neurovascular status was intact and she had a negative Tinel’s sign. Radiographs did reveal a 3 mm heel spur. Pain to palpation was greatest on the medial plantar aspect of her left heel.    We performed cryosurgery in the office, using a two-minute, 15-second freeze cycle and a 30-second defrost, and followed that with another two-minute, 15-second freeze cycle. We irrigated the wound with 2 cc of lidocaine and 0.25 cc dexamethasone 4 mg and applied a mild compressive dressing.    Twenty-four hours after the procedure, the patient reported pain at 2 of of 10 on the pain scale. She felt the discomfort was due to the procedure and not her fasciitis. During the first postoperative week, as her activity increased in regular shoes, her discomfort also increased to a 3 out of 10 on the pain scale. As the small surgical site healed during the second week, the pain decreased. Two weeks after undergoing the cryosurgery procedure, the patient had no plantar fascial pain. She was at full activity in regular shoes. A two-year follow-up visit revealed no recurrence of the plantar fasciitis.

Case Study Two: Treating The Active, Noncompliant Patient

   A 67-year-old active male with a BMI of 29 presented to the office complaining of pain to both heels. While the patient experienced the typical heel pain with walking after rest, he also played racquetball five days a week and noted severe pain in his left heel during this activity. He graded the pain as a 10 out of 10 in terms of severity.    The examination revealed a mild flexible pes valgo planus foot structure. His neurovascular status was intact with no evidence of nerve entrapment. Pain to palpation was greatest on the medial plantar aspect of his heel but there was also mild pain in the central plantar area.    Previous treatment consisted of taking several different NSAIDs, orthotics, physical therapy, numerous injections and using a night splint. The injections helped the most but the patient said the pain would return after a week. The patient previously had shockwave therapy for his left heel but that was unsuccessful. The patient did not want a fascial release procedure because of the prolonged healing period.    We performed cryosurgery on his left heel. One day after the procedure, his pain was 2 out of 10 on the pain scale. One week after the procedure, he presented to the office stating that he still had heel pain and he did not think the procedure worked.    A subsequent examination revealed that the patient had absolutely no pain at the original medial and central location but had developed pain at the lateral band of the fascia. The patient had also returned to playing racquetball five days per week against instructions. We gave the patient a prescription for naproxen 500 mg, one tablet twice daily. We applied a low dye dressing to his foot and instructed him to stop playing racquetball.    Ten days later, the patient was still experiencing pain on the lateral aspect of his heel. He graded the pain at 8 out 10 on the pain scale. He continued on naproxen and received an injection of 2 cc of 1% lidocaine and 0.5 cc of triamcinalone 10 mg to the lateral plantar aspect of his heel. We replaced his sports orthotics temporarily with a softer over-the-counter arch support.    Approximately nine days later, the patient graded his pain at 4 out of 10. He had also returned to playing racquetball three days per week. We modified his arch support by adding additional padding in the medial arch.    Three weeks later, all pain had subsided and he was wearing his sports orthotics and playing racquetball five days per week. The patient stated that was the first time in two years that he did not have heel pain. One year after undergoing cryosurgery, the patient remains asymptomatic.

In Conclusion

   Cryosurgery is an effective, new treatment modality for managing plantar fasciitis. This percutaneous procedure is minimally invasive, provides excellent results and has a very short postoperative course. Dr. Fallat is a Clinical Assistant Professor within the Department of Family Medicine at the Wayne State University School of Medicine in Detroit. He is the Director of Podiatric Surgical Residency for the Oakwood Healthcare System in Dearborn, Mich. He is board-certified by the American Board of Podiatric Surgery and is a Fellow of the American College of Foot and Ankle Surgeons.
 

References:

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