Background:

We sought to compare clinical efficacy among endoscopy-assisted radio-frequency ablation under local anesthesia, extracorporeal shockwaves (ESWs), and eccentric exercises in treating insertional Achilles tendinosis.

Methods:

In this retrospective study, 78 patients diagnosed as having unilateral insertional Achilles tendinosis were enrolled. These participants underwent endoscopy-assisted radio-frequency ablation, ESWs, and eccentric calf muscle exercises between March 1, 2006, and February 28, 2011. Clinical efficacy was evaluated by the visual analog scale (VAS), the American Orthopaedic Foot and Ankle Society (AOFAS) ankle/hindfoot scale, and the Victorian Institute of Sport Assessment–Achilles (VISA-A) scale before and after treatment.

Results:

Before treatment, there were no statistically significant differences in VAS, AOFAS ankle/hindfoot scale, and VISA-A scale scores among the different groups (all P > .05). For the endoscopy and ESW groups, VAS, AOFAS ankle/hindfoot scale, and VISA-A scale scores were significantly improved after 18 months of treatment (all P < .05). The VAS, AOFAS ankle/hindfoot scale, and VISA-A scale scores in the endoscopy group were significantly higher than those in the ESW and eccentric exercise groups after 18 months of therapy (all P < .05).

Conclusions:

Combined with synovectomy and tendon debridement, endoscopy-assisted radio-frequency ablation yields better clinical efficacy compared with ESWs in treating insertional Achilles tendinosis.

Achilles tendinopathy is one of the most common sports injuries. It has been estimated that 7% to 9% of professional long-distance running athletes have experienced this illness at some point.1  Achilles tendinopathy may cause heel pain and functional limitations, and even partial or complete rupture of the Achilles tendon if not treated properly. In general, the incidence of Achilles tendinopathy is correlated with sports movement and overuse injuries. Recent research also indicates that the incidence of Achilles tendinopathy involves other factors, including lipid metabolic disorders, tenocyte apoptosis, and mutations in genes encoding collagen fiber.2  Astrom3  noted that sports movement is not associated with the severity of pathologic changes of the Achilles tendon tissues, concluding that sports movement is a potential factor inducing relevant symptoms rather than pathologic changes. Achilles tendon pain probably arises from both excessive growth of nerves and vessels and topical production of substance P during the healing process after injuries.4 

Achilles tendinopathy can be categorized into insertional and noninsertional Achilles tendinosis according to the position of the affected sites. The first case of insertional Achilles tendinosis was reported by Clain and Baxter,5  and they suggested that the possible cause was Haglund deformity and retrocalcaneal bursitis, whereas other investigators have proposed contrasting arguments.6 

A variety of methods have been applied in treating Achilles tendinosis, including physical therapy, injection therapy, eccentric calf muscle exercises, and extracorporeal shockwaves (ESWs). It has been shown that eccentric exercises and ESW therapy yield the highest clinical efficacy in the clinical setting.7  However, eccentric exercise is primarily applied in noninsertonal Achilles tendinopathy, and its clinical efficacy in treating insertional Achilles tendinosis remains elusive. Treatment with ESWs is suitable for Achilles tendinosis and probably yields relatively high efficacy in insertional Achilles tendinosis. Up to approximately one-fourth of all patients require surgical treatment.8  Recently, minimally invasive techniques, especially radio-frequency ablation, have been selectively applied in treating Achilles tendinopathy; these techniques induce small operative wounds and have low complication rates, receiving widespread recognition from patients.9  At present, to our knowledge, no studies comparing clinical efficacy among different treatment options for insertional Achilles tendinosis have been conducted.

Patients and Methods

Patients

This study was a retrospective clinical analysis conducted in the Department of Orthopedics, Chinese PLA General Hospital (Beijing, China) between March 1, 2006, and February 28, 2011. Of the 78 patients, 18 received endoscopic debridement under local anesthesia combined with radio-frequency ablation, 30 underwent ESW treatment, and the remaining 30 received eccentric exercises.

Patients were included in the study if they 1) experienced Achilles tendon pain and tenderness accompanied by decreased movement ability, 2) had symptoms not alleviated by resting or medication treatment for up to 6 months, or 3) underwent magnetic resonance imaging of the Achilles tendon before surgery. None of the enrolled patients had a medical history of local or systemic corticosteroid use.

This study excluded patients with 1) bilateral Achilles tendinosis, 2) complicated Achilles tendon rupture, or 3) a systemic disease (such as rheumatic disease or diabetes).

Techniques

Endoscopic Microdebridement Combined with Ablation Under Topical Anesthesia

Patients were locally anesthetized using 10 mL of 2% lignocaine plus 20 mL of 0.9% normal saline solution. Surgical portals were chosen approximately 2 cm to the medial and lateral Achilles tendon at the proximal end of lesions. A 5-mL portion of solution was injected into each surgical incision, and 20 mL of solution was injected between the Achilles tendon and the surface skin. Under endoscopic examination, hyperplastic synovium of the Achilles tendon was excised, calcified masses in the Achilles tendon were removed, and the Achilles tendon was treated by radio frequency. A radio-frequency probe (Topaz; ArthroCare, Sunnyvale, California) was inserted to create holes at an interval of 2 mm. The patients were told to avoid intense physical exercise for 3 months after the procedure.

ESW Treatment

A portable shockwave system (Swiss DolorClast; EMS, Nyon, Switzerland) was used in this study. The patients were in a prone position. After marking the extent of the pain on the Achilles tendon, the patients were treated at an energy flow density of 0.12 mJ/ mm2 and a frequency of 10 Hz. The pain spots were scanned horizontally and vertically, and the energy flows were focused on the localized pain spots. The treatment period included 2,000 cycles repeated three times at 1-week intervals. The patients were warned against participating in intense physical activities.

Eccentric Exercise

In the beginning, the loading was the body weight. Patients stood with all of their body weight on the forefoot of the injured leg from an upright body position with the ankle joint in plantarflexion. The calf muscle was loaded by lowering the affected limb down and dorsiflexing the ankle until the heel was below the level of the step with the ankle in maximum dorsiflexion. The exercises were performed with the knee straight to eccentrically load the gastrocnemius and with the knee flexed to eccentrically load the soleus. Patients relied on the noninjured leg to return to the start position. Eccentric calf muscle exercises (3-15 repetitions with straight and bent knee) were prescribed twice daily for 12 consecutive weeks.10  Moreover, physiotherapy was started at the same time for all three groups. Patients were advised to continue the exercises through mild or moderate pain, stopping only if the pain became unbearable. When these exercises could be completed without pain or discomfort, patients progressed to carry a 5-kg dumbbell and continued to add weight in multiples of 5 kg if they did not experience pain in the Achilles tendon by the end of the third set of the eccentric exercises. All of the patients were contacted by telephone after 6 weeks to check training compliance and patients' concerns. All of the patients were reexamined in the outpatient department every 4 weeks.

Efficacy Evaluation

Clinical efficacy was evaluated by the visual analog scale (VAS), the American Orthopaedic Foot and Ankle Society (AOFAS) ankle/hindfoot scale, and the Victorian Institute of Sport Assessment–Achilles (VISA-A) scale before and 6, 12, and 18 months after treatment. The score evaluation was performed by the physicians who performed the surgery, which properly guaranteed the consistency of the evaluation process.

A statistical software program (SPSS for Windows, version 10.0; SPSS Inc, Chicago, Illinois) was used for statistical analysis in this study. Group comparison was statistically analyzed by the Student's t test. A P < .05 was considered statistically significant.

Results

In the endoscopy group, 14 patients were engaged in regular sports activities and four were manual laborers. In the ESW group, 26 patients were engaged in regular sports activities and four were manual laborers. In the eccentric exercise group, 24 patients were engaged in regular sports activities and six were manual laborers.

In the endoscopy group, all 18 patients completed follow-up, and one presented with delayed wound healing. Of the 30 patients in the ESW group, six refused treatment due to intolerable pain, and 24 completed follow-up. Of the 30 patients in the eccentric exercise group, three were lost to follow-up, one had surgery after 12 months, and the remaining 26 finished follow-up. As shown in Table 1, no statistically significant differences were noted in age, sex, and body mass index (calculated as the weight in kilograms divided by the square of the height in meters) among the groups (all P > .05).

Table 1

Demographic Data for the Study Participants

Demographic Data for the Study Participants
Demographic Data for the Study Participants

Before treatment, there was no statistically significant difference in the VAS scores among the different groups (all P > .05). In the endoscopy and ESW groups, the VAS scores were significantly improved after 18 months of treatment (both P < .05). The VAS scores in the endoscopy group were significantly lower than those in the ESW and eccentric exercise groups after 18 months (both P < .05) (Table 2).

Table 2

Comparison of VAS Scores Among the Three Study Groups

Comparison of VAS Scores Among the Three Study Groups
Comparison of VAS Scores Among the Three Study Groups

Before treatment, there was no statistically significant difference in the AOFAS ankle/hindfoot scale scores among the different groups (all P > .05). In the endoscopy and ESW groups, the AOFAS ankle/hindfoot scale scores were significantly improved after 18 months of treatment (both P < .05). The AOFAS ankle/hindfoot scale score in the endoscopy group was significantly higher than those in the ESW and eccentric exercise groups after 18 months of therapy (both P < .05) (Table 3).

Table 3

Comparison of AOFAS Ankle/Hindfoot Scale Scores Among the Three Study Groups

Comparison of AOFAS Ankle/Hindfoot Scale Scores Among the Three Study Groups
Comparison of AOFAS Ankle/Hindfoot Scale Scores Among the Three Study Groups

Before treatment, no statistically significant differences were observed in the VISA-A scale scores among the different groups (all P > .05). In the endoscopy and ESW groups, the VISA-A scale scores were significantly elevated after 18 months of treatment (both P < .05). The VISA-A scale score in the endoscopy group was significantly higher than those in the ESW and eccentric exercise groups after 18 months (both P < .05) (Table 4).

Table 4

Comparison of VISA-A Scale Scores Among the Three Study Groups

Comparison of VISA-A Scale Scores Among the Three Study Groups
Comparison of VISA-A Scale Scores Among the Three Study Groups

Discussion

In general, conservative therapy is recommended as the primary choice for treating Achilles tendinitis in most patients (>70%),11  among which eccentric calf muscle training and ESWs have been shown to yield the highest clinical efficacy. These findings were later confirmed by other investigators.12  Eccentric exercises can reshape and enhance the tolerability of Achilles tendon by strengthening the fiber cross-link in the tendon.13  A 5-year follow-up study14  suggested that patients experienced a significant increase in the VISA-A scale scores after receiving eccentric exercises, whereas only a mild degree of pain remained. Another 5-year study15  indicated that the overall efficacy rate was as high as 80%, whereas the recurrence rate was approximately 15%. However, the studies mentioned previously herein were limited to the treatment of noninsertional tendinopathy. Consequently, clinical outcomes regarding insertional Achilles tendinosis remained elusive.16  In this retrospective study, the clinical efficacy of eccentric exercises in treating insertional Achilles tendinosis was proved to be poor, probably due to the fact that the self-repair ability declined at the presence of local chondrification and abnormal increases in the levels of type II and III collagen fiber.17 

Recently, ESWs have been introduced as an effective treatment against Achilles tendinosis. Wiegerinck et al18  conducted a systematic review of the common therapies for insertional Achilles tendinopathy and concluded that ESWs were used in most of the searched literature and that, overall, 49 of 64 recruited patients (77%) with Achilles tendinopathy were satisfied with the clinical outcomes after ESW therapy, suggesting that ESW therapy was superior to wait-and-see and the eccentric training regimen in terms of clinical efficacy and safety. In addition, it is easily accepted by most patients because it does not require surgery.18  Maffulli et al19  performed ESW on 127 patients diagnosed as having Achilles tendinitis, and the results showed a 2-month effective rate of 47%, which increased to 73% after 1 year and 76% at the end of 2 years of treatment. Furia20  also conducted a 1-year follow-up study in patients with insertional Achilles tendinosis and also achieved high efficacy. By generating acoustic cavitation, ESWs are able to downregulate the expression of matrix metalloproteinases and interleukins in tenocytes,21  increase the levels of transforming growth factor-β1 and insulin-like growth factor 1,22  and, thereby, initiate the repairing response. A comparative study revealed that ESWs combined with eccentric exercises shows higher clinical efficacy than eccentric exercises alone.23  However, for patients with insertional Achilles tendinosis, ESW therapy yields better clinical efficacy than do eccentric exercises alone. In the present investigation, ESW therapy yields significantly higher efficacy compared with eccentric exercises, which is consistent with previous findings. Clinical efficacy in the endoscopy group was superior to that in the ESW group because 20% of patients (six of 30) in the ESW group discontinued treatment due to intolerable pain, which may affect the evaluation of the clinical efficacy instead. Moreover, there is a risk of tendon rupture during the treatment of calcified Achilles tendinitis. Consequently, the actual scores in the ESW group should be lower than those in the endoscopy group.

It has been reported that approximately 25% of all patients do not respond to conservative therapy8  and ultimately require surgical intervention. However, the surgical effect is still uncertain, and many patients require repeated surgeries before their symptoms are completely alleviated. Surgical outcomes are especially poor in patients with retrocalcaneal bursitis.24  Johnson et al25  performed surgery on 22 patients with insertional Achilles tendinosis via middle and posterior surgical approaches, accurately localized the sites of pathologic changes, and maintained normal Achilles tendon fibers. Mean follow-up was 34 months. The AOFAS ankle/hindfoot scale scores increased from 53 to 89, and three patients presented with surgical complications. Although conventional open surgery has gained certain clinical efficacy, it has been reported to cause surgical complications at a rate up to 11%.26  In recent years, minimally invasive techniques have rapidly emerged and have been successfully applied in treating Achilles tendinitis.27  The ablation electrode can decompose gas into plasmas. The particles, which have high energy, can repair the rupture of the chemical bond in soft tissues. However, Van Dijk28  performed percutaneous radio-frequency coblation in 47 patients with insertional Achilles tendinosis and demonstrated that seven required surgical treatment and three had tendon rupture, suggesting that this technique should be applied cautiously in patients with a high body mass index. In contrast, another study29  has shown that radio-frequency ablation yields high efficacy in treating insertional Achilles tendinosis, probably resulting from the reason that radio-frequency ablation promotes tenocyte activity, initiates cell proliferation, facilitates the healing process, and, thus, restores the blood supply of muscular tendons during the process of creating holes. Then, abnormal nerve fiber degenerates and subsequently initiates a cascade of repairing responses, thereby alleviating topical symptoms. In this study, we successfully integrated an endoscopic technique under topical anesthesia and radio-frequency ablation, which fully used the benefits of this minimally invasive technique. During the arthroscopy procedures, the physicians could perform local infiltration anesthesia by palpation of the pain scope of the Achilles tendon and mark the site of pain. During anesthesia, the doctors asked the patients about changes in their pain sensation. If the patients presented no pain, then the sites could be determined as sites of lesions. Under endoscopy, the synovial tissue on the surface of affected Achilles tendon can be clearly observed and thoroughly debrided, the sites of pathologic changes can be precisely located, and the calcified lesions can be removed completely. In addition, Haglund deformity and painful bursitis at the back of the heel could be effectively treated simultaneously. The combined benefits of endoscopy, synovectomy, and tendon debridement collectively enhance clinical efficacy and reduce surgical complications.30 

Conclusions

The combined therapies of synovectomy and tendon debridement and endoscopy-assisted radio-frequency ablation yield higher clinical efficacy compared with ESWs in treating insertional Achilles tendinosis.

Financial Disclosure: None reported.

Conflict of Interest: None reported.

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