Heel pain is a general term of various diseases process affecting the daily work and life of patients. The etiologies are complicated and include plantar fasciitis, rupture of plantar fascia, calcaneal stress fracture, heel fat pad atrophy and or inflammation caused by strain and degeneration, retrocalcaneal bursitis, Achilles tendinitis, and irritation of calcaneal osteophytes formation. Many supports that plantar fasciitis is one of the main causes. Epidemiological studies show that plantar fasciitis is estimated to account for 11%-15% of all foot disease that require medical attention[15]. It is common in the elderly population aged from 40 to 70 years. Workers with long standing hours, runners and obese patients with BMI more than 30 kg/m2 are the high-risk population with higher intensity of pain[16].
It is estimated that about 90% of patients with plantar fasciitis received conservative treatment with satisfactory effect, and no further surgical intervention were needed[17, 18]. Therefore, the American Orthopedic Foot and Ankle Society recommends that patients diagnosed with plantar fasciitis should receive at least 6 months of conservative treatment before undergoing surgical intervention[8]. Conservative treatment methods include stretching traction training, splinting, bracing, extracorporeal shock wave, oral administration of drugs, and local injections of corticosteroid medications. Drug injection is also a common treatment for fasciitis. Rastega et al found that steroid injection could palliate plantar heel pain rapidly but dry needling can provide more satisfactory results for patients with plantar fasciitis in the long term in a random clinical trail.[19] PRP injection was associated with improved pain and function scores at three month follow-up when compared with corticosteroid injections[20, 21]. Polydeoxyribonucleotide was certificated as an effective and safe treatment option and may be considered for plantar fasciitis by Kim JK and Chung JY[22].
For patients with intractable plantar fasciitis failed at least 6 months of conservative treatment, surgical intervention can be considered. Open plantar fascia release is the most traditional operation method. According to the reports, the postoperative satisfaction rate of open release was 50%-95%[23, 24]. However, disadvantages of the surgery include large wound, longer postoperative recovery time, and potential postoperative occurrence of complex regional pain syndrome. Although plantar fascia release under arthroscopy has the advantage of minimally invasive, there are still postoperative complications mostly reported with incomplete pain-relieving occurring higher in rate than the traditional open plantar fascia release[24–27]. Xu reported a modified minimally invasive surgical system in open release of plantar fascia[28]. In this study, all of the patients in the open plantar fascia release were operated with this modified minimally invasive technique.
Bipolar radiofrequency ablation technique was first used in the treatment of cardiovascular disease to promote the regeneration of ischemic myocardium in patients with chronic heart failure[29–31]. Weil and his colleagues applied this technique for the treatment of intractable plantar fasciitis in the early stage with good results[32]. In a prospective study consisting of 21 cases in 2011, Sorensen et al. supported the curative effect of this type of technique; In the same year, Hormozi et al. also reported the therapeutic effect of this operation based on a prospective study of 14 cases[33, 34].
In this study, the average age of the enrolled 31 patients was 52.13 years old, among which, there were 26 patients at the age of 40–70 years old accounting for 83.87% of the total subjects which was similar to the demographics reported from the previous investigations. There were 14 overweight patients (24 ≤ BMI < 28) and 10 obese patients (BMI ≥ 28), accounting for 45.16% and 32.26% respectively.
The results of this study showed a shorter average operation time of percutaneous radiofrequency ablation than the open plantar fascia release. We contribute this result to the relatively simple operation process of this method as reported also in the previous[33, 34]. At the same time, the average recovery time was shorter in the percutaneous radiofrequency ablation group, and the result was also consistent with the previous literature[33]. Possible reasons might be that percutaneous radiofrequency ablation had relatively smaller individual wounds and thus retained the integrity of the plantar fascia[34]. There was no difference of postoperative VAS scores and the AOFAS-AH scores between the two groups, indicating that the two types of surgical procedures share the same curative effects. There were no major postoperative complications in both groups in our study.
Calcaneal osteophytes is also known as calcaneal spur. Many scholars believed that the calcaneal osteophytes is one of the major factors responsible for heel pain, and some scholars even described heel pain as calcaneal osteophytes syndrome[1]. Johal et al. in their study insisted that there was a positive correlation between calcaneal osteophytes and plantar fasciitis. However, the hypothesis was not able to explain the asymptomatic calcaneal osteophytes[35]. Kumai supported that calcaneal osteophytes was associated with the degeneration of cartilage cells at the insertion of the plantar fascia, regardless of the role of the traction of the plantar fascia[36]. In this study, there were 18 cases out of 31 had calcaneal osteophytes, of which only 1 case underwent intraoperative calcaneal osteophytes resection. All patients had significant improvement with pain postoperatively. We may speculated that there was no significant correlation between calcaneal osteophytes and the incidence of heel pain.
During the follow-up period, 29 patients were satisfied with the operation with a satisfaction rate of 93.55%. Two patients reported poor clinical results. Among which, one patient had a combined Achilles tendinopathy. The pain from plantar fascia pain was completely relieved after operation while there was still pain of the Achilles tendinopathy; The other patient had a flatfoot deformity treated before the plantar fascia operation. The irritation of the subtalar tarsal screw remained after our intervention of the plantar fascia. However, heel pain symptoms and limb function were both improved in the two patients after plantar fasicia operation.
With the design limitation of a retrospective study, our results could be affected by various factors, such as selection bias, small sample size, and lack of long-term follow-up period. Small sample size is common in many of the available reports. We believe that the results of this study will be helpful for relevant design of prospective studies in the future.
Collectively, based on the experiences in the treatment of 31 patients with intractable plantar fasciitis, we believe that open plantar fascia release and percutaneous radiofrequency ablation can significantly relief the pain and improve limb function in patients with intractable plantar fasciitis. Percutaneous radiofrequency ablation has shown the advantages of shorter operation time, shorter postoperative recovery time, higher postoperative function scores and therefore may be a better option while selecting surgical interventions of the intractable plantar fasciitis.