Insertional Achilles tendinopathy is a troublesome condition, most often seen among middle-aged to older individuals who are not physically active and are overweight.1 The suggested aetiology is degenerative lesions at the enthesis due to either excessive tensile loading2 3 or, more recently, to stress-shielding.4 There is often a combination of pathologies, including superficial and retrocalcaneal bursitis, Haglund deformity of the upper calcaneus and tendinopathy.5 6

The mechanisms behind this painful condition are unknown7 8 and treatment is often ineffective.7 9 Consequently, many different conservative treatments have been proposed, including rest, nonsteroidal anti-inflammatory drugs (NSAIDs), ice, strength training and high-energy extracorporeal shock-wave therapy.1 10 11

Eccentric training is a frequently-used treatment model.12^–15 The eccentric exercise programme that has been shown to be successful for patients with mid-portion Achilles tendinosis was less successful for patients with insertional Achilles tendinopathy.12 It was thought that this was because of differences in pathology; however, the pathology appears similar in both mid-tendon and insertional tendinopathy.16 The concept of an “enthesis organ”,17 where the insertion is subject to compressive forces in dorsiflexion because of impingement between tendon, bursa and bone suggests that the Achilles tendon insertion may respond to eccentric load without dorsiflexion.

This pilot study aimed to evaluate eccentric calf-muscle training without dorsiflexion in patients with chronic painful insertional Achilles tendinopathy.

MATERIAL AND METHODS

Participants

Participants with pain in the Achilles tendon insertion for more than 3 months were recruited from the Sports Medicine Unit in Umeå and the Capio Artro Clinic in Stockholm, Sweden. Participants were included if they had insertional pain and pathology based on a clinical examination (HA) and abnormality on ultrasonography. A high-resolution grey-scale ultrasound with the aid of colour Doppler (Siemens Acuson Segoia) and a linear multifrequency (8–13 MHz) probe was used. Abnormalities included Achilles tendon and bursal thickening, bone pathology (calcification, spur, fragment), and neovascularisation. The contralateral tendon was also examined. Participants with chronic inflammatory disease were excluded. All patients gave written consent to participate in the study. The study was approved by the ethics committee of the Medical Faculty at the University of Umeå.

Eccentric training regimen

All patients were given a practical demonstration and hand-written instructions of the exercises by the same physiotherapist (PJ) at the beginning of the study. The eccentric calf-muscle training was performed in an upright body position with a straight leg. The patients performed a heel raise with the non-injured leg, then all body weight was transferred to the injured side and from the heel-raised position the patients slowly lowered the heel to the floor level (fig 1a, b). There was no load with the ankle in dorsiflexion. This was done 3 times for 15 repetitions, twice a day, 7 days/week for 12 weeks. Participants with bilateral symptoms performed a leg press while standing on a box to get up to the start position. This was done to avoid, as much as possible, concentric contraction in the calf muscle (fig 2).

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Figure 1 A. Start position for the eccentric insertional Achilles exercise. The patients stand with a straight leg, all weight on the affected side. From this position the heel is slowly lowered to floor level. To get up to the start position, the patients performed a heel-raise on the unaffected side. B. End position for the eccentric insertional Achilles exercise.

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Figure 2 If there were bilateral symptoms the patients performed a leg press while standing on a box or a staircase to get up to the start position. This was done to avoid as much as possible concentric because of contraction in the calf muscle.

If there was no pain during the exercise the load was increased by using a backpack that was gradually filled with weights to reach a new level of painful training (fig 3). Patients were informed that calf muscle soreness, and increased pain in the Achilles insertion, could appear during the first 2 weeks of eccentric training. All patients were contacted by telephone after 2 and 6 weeks to check training compliance. All patients could contact an investigator (PJ) during working hours if they had questions about the training programme. After 6 weeks the patients were told to slowly return to their previous sports/recreational activity.

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Figure 3 If there was no pain during the exercise the patients gradually filled a backpack with weights to reach a new level of painful training.

Evaluation

At baseline and follow-up pain was evaluated with a 100 mm visual analogue scale (VAS) that recorded the worst amount of pain during Achilles-tendon-loading activity.18 After 12 weeks, the participants recorded whether they were “satisfied” (back to previous tendon loading activity) or “not satisfied” (not back to previous tendon loading activity) with treatment.

Statistical analysis

Data were entered into statistics software (SPSS version 11.5, SPSS Inc., Chicago, Illinois, USA). The results are presented as mean (SD). Differences between the groups were calculated using a Student t test for independent samples. A p value <0.05 was considered significant.

RESULTS

Twenty-seven participants (12 men, 15 women, mean age 53.4 years, range 25–77) with chronic pain in the Achilles insertion were included in the study (table 1).

Twenty of the participants had unilateral symptoms, seven had bilateral symptoms, giving a total of 34 painful Achilles tendons. All participants had a long duration of pain (mean 26.5 months, range 6–96) and were not able to participate in their regular Achilles-tendon-loading activities because of pain.

Participants undertook a variety of activities, including walking (15), running (6) and other sports (6) and had tried a variety of treatments including rest (27), NSAID (22), local cortisone injections (6), eccentric training (13), shock-wave therapy (1), laser (1), ultrasound (8), heel-lift (8) and acupuncture (5).

At baseline the mean estimated pain on the VAS was 72.4 (SD 16.5) for the whole group. At the follow-up (mean 4 months), 18 patients (with 23 painful tendons) were satisfied with the treatment and were back to their previous Achilles-tendon-loading activities. In this group, estimated pain on the VAS had decreased significantly from 69.9 (18.9) to 21.0 (20.6) (p<0.001).

Nine patients (with 11 painful tendons) were not satisfied, though the estimated pain on the VAS had decreased significantly from 77.5 (8.6) to 58.1 (14.8) (p<0.006). These nine patients were not back in their previous Achilles-tendon-loading activities.

During the 12-week training regimen one patient could not perform the exercise because of pain.

This patient was registered as unsatisfied with the treatment.

Age, gender, body mass index (BMI), duration of symptoms, activity level, occurrence of bone pathology unilateral or bilateral tendon pathology had no effect on the outcome of the treatment (table 2).

DISCUSSION

The patients in our study had had a long duration of insertional pain, and the majority had pathology in multiple tissues (tendon, bone, bursa). Therefore, we believe that our group of patients is representative for individuals with insertional Achilles tendinopathy.

Painful eccentric training beyond plantargrade has shown good clinical results in patients with mid-portion Achilles tendinosis.12 To the best of our knowledge only one study has evaluated this type of painful eccentric training on patients with chronic pain in the Achilles insertion. In that study only 32% of the patients had good clinical results.12 It was hypothesised that the reason for the poor results was a mechanical impingement between the prominent calcaneus and the tendon and bursa, when the ankle was in the dorsiflexed position.

In the current study, based on the findings from the previous study,12 we used an eccentric training model without dorsiflexion in the ankle joint to avoid possible mechanical impingement. The new training model resulted in 67% satisfied patients. The results were similar whether there was tendon pathology alone, Haglund’s deformity, bursae pathology or bone spurs. Interestingly, combined pathology in the insertion does not seem to exclude a satisfactory response to this eccentric training regimen. This might be of clinical importance, since surgical treatment of this condition has shown varying clinical results.19^–22

Interestingly, in a recent study ultrasound and Doppler-guided sclerosing polidocanol injections, targeting the area with increased vascularity in the Achilles tendon insertion, were shown to give good clinical results in patients with chronic insertional pain.23 This possibly indicates that the increased vascularity, together with nerves, is closely related to the source of pain. In that study, the increased vascularity was found in relation to the tendon, bursae, and bone, alone, or in combination. In the current study there are similar findings. We have not fully evaluated the tendon changes before and after this type of training, but it seems that the increased blood flow found at inclusion decreased dramatically in the successfully treated patients, after the 12 weeks of eccentric training. Evaluation of the tendon structure and blood flow, before and after treatment, is in focus for a future study.

In conclusion, 12 weeks of painful eccentric calf-muscle training without dorsiflexion showed promising clinical results in 67% of the patients. Longer-term follow-ups with more participants are needed to verify the results.