Abstract
Background:
Achilles tendinopathy is a common clinical problem that can be either insertional or noninsertional. A variety of treatment methods have been described, although little consensus exists on an optimal method or methods. We sought to investigate the current evidence on different treatment methods for noninsertional Achilles tendinopathy, with a focus on functional outcomes.
Methods:
We performed a review of the available literature in PubMed and the Cochrane Central Register of Controlled Trials. Data from included studies were categorized according to treatment method and analyzed with respect to functional outcome and complication rate.
Results:
In total, 1420 abstracts were reviewed, of which 72 articles containing 3523 patients met inclusion criteria. Within the 72 studies included, 6 operative techniques and 19 nonoperative treatments were evaluated.
Conclusion:
A wide variety of treatments are available for noninsertional Achilles tendinopathy, although newer treatments and most operative methods lack high-level evidence. Eccentric exercise is the most thoroughly studied and supported nonoperative treatment, while tenotomy and debridement is the operative procedure with the most evidence of efficacy. Platelet-rich plasma injections and extracorporeal shockwave therapy have proven to be viable second-line nonoperative treatments. Gastrocnemius recession and flexor hallucis longus transfer have shown benefit in case series.
Level of Evidence:
Level II, systematic review.
The largest and strongest tendon in the body, the Achilles tendon provides the propulsive power of gait. Although the colloquial term tendonitis is used in common parlance, tendinosis is a much more common clinical problem. Tendinosis is defined as degeneration or a failed healing response of the tendon, as opposed to an inflammatory process. 5 Although the exact pathogenesis of Achilles tendinopathy is not well understood, it may at least in part be due to a longstanding gastrocnemius equinus contracture.18,46,60
Achilles tendinopathy is generally classified by its anatomic location as insertional or noninsertional. Insertional tendinopathy occurs at the calcaneal insertion of the Achilles tendon and appears to be less common.5,55 Noninsertional (midportion, midsubstance) tendinopathy occurs in the body of the tendon and is thought to be more common. 5 Although insertional and noninsertional Achilles tendinopathy can occur in any one patient, it is generally thought that insertional tendinopathy generally occurs in older, less active patients, while noninsertional tendinopathy generally occurs in younger, more active patients.
A variety of different treatment methods have been described spanning the gamut from conservative to operative techniques. The last current concepts review specifically on noninsertional Achilles tendinopathy from 2009 provided a weak recommendation for eccentric exercises, sclerosing injections, and topical glyceryl trinitrate as options for initial conservative management. Surgical management with tenotomy and debridement was recommended for recalcitrant cases. 14 This current concepts review sought to assess the updated evidence regarding treatment options for noninsertional Achilles tendinopathy and functional outcomes associated with the various treatment options.
Methods
We performed a literature review following the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines using the PubMed/Medline and Cochrane Central Register of Controlled Trials (CENTRAL). Our search terms included Achilles, tendinopathy, and treatment, and all studies in English that described the treatment and functional outcome of Achilles tendinopathy were included. Only studies of level IV or above, including randomized control trials (RCTs), prospective studies, retrospective studies, and case series, were evaluated. Duplicate results, reviews, systematic reviews, meta-analyses, cadaveric studies, animal studies, non-English studies, study protocols, and articles that did not investigate noninsertional Achilles tendinopathy were excluded. Furthermore, studies that did not specify whether the tendinopathy was insertional or noninsertional were excluded as well. Due to the heterogeneity of the data, pre- and posttreatment outcome data were presented per study with stratified significance levels.
The findings were categorized based on the different treatment options, study design, study size, mean age, treatment protocol, and control protocol (if applicable). Functional outcome measurements, functional outcomes and their significance, patient satisfaction, complications, and mean follow-up period were extracted.
For the search terms used, we found 1475 articles published between 1965 and 2018, including 55 duplicates. Abstract screening resulted in the exclusion of 1129 articles. The full texts of 291 articles investigating treatment outcomes of insertional and noninsertional Achilles tendinopathy were assessed, of which 99 met inclusion criteria. Of these, 72 articles evaluated noninsertional tendinopathy alone. Forty-eight studies described conservative treatment, 23 described operative treatment, and 1 described both (Figure 1).
Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) flow diagram. IAT, insertional Achilles tendinopathy; NIAT, noninsertional Achilles tendinopathy.
Nonoperative Treatment
Forty-nine studies with 2668 patients investigating 19 nonoperative treatment modalities were identified. The majority of studies focused on eccentric exercises, platelet-rich plasma (PRP) injection, and extracorporeal shockwave therapy (ESWT) (Table 1). Other less commonly used treatments include topical glyceryl trinitrate, polidocanol injection, alternative medicine modalities, blood injection, hyaluronic acid injection, intense pulsed light, stromal vascular fraction (SVF) injection, aprotinin injection, nonsteroidal anti-inflammatory drugs (NSAIDs; ibuprofen), and corticosteroid injection (Table 2).
Functional Outcomes of Nonoperative Treatments for Noninsertional Achilles Tendinopathy. a
Abbreviations: AOFAS, American Orthopaedic Foot & Ankle Society; ESWT, extracorporeal shockwave therapy; FAOS, Foot and Ankle Outcome Score; HVI, high-volume injection; PRP, platelet-rich plasma; RCT, randomized controlled trial; VAS, visual analog scale; VISA-A, Victorian Institute of Sports Assessment–Achilles questionnaire.
w: not significant; x: P < .05; y: P < .01; z: P < .001.
Includes studies categorized under multiple treatment modalities.
Functional Outcomes of Nonoperative Treatments for Noninsertional Achilles Tendinopathy (Less Common). a
Abbreviations: AOS, Ankle Osteoarthritis Scale; NSAID, nonsteroidal anti-inflammatory drug; RCT, randomized controlled trial; VAS, visual analog scale; VISA-A, Victorian Institute of Sports Assessment–Achilles questionnaire.
w: not significant; x: P < .05; y: P < .01; z: P < .001.
Includes studies categorized under multiple treatment modalities.
Treatment outcomes were reported for multiple different modalities. Data corresponding to each treatment method of interest were extracted from the respective study and included. Some studies looked at more than 1 treatment option. This resulted in studies being stratified under more than 1 treatment method and thus being accounted for multiple times. Within these 49 articles, 25 studies looked at eccentric exercises followed by 6 studies on PRP injection, 5 studies on ESWT, and 16 studies on various other treatment techniques.
Eccentric exercises
Eccentric exercise remains the first-line treatment for noninsertional Achilles tendinopathy with the most literature supporting its use. Within the 25 articles on eccentric exercises, 14 investigated eccentric exercises alone, 9 looked at eccentric exercises in conjunction with an additional treatment technique, and 2 reported results on both eccentric exercises and eccentric exercises with an adjunctive treatment. Regarding eccentric exercises alone, 12 of the studies were RCTs. Twelve of 16 studies, including 10 RCTs, reported a statistically significant improvement after treatment with no complications.* Athletes may benefit more from the exercises than sedentary patients. Two prospective studies of 15 and 45 recreationally athletic patients reported a significant improvement in visual analog scale (VAS) and Victorian Institute of Sports Assessment–Achilles questionnaire (VISA-A), respectively, by the end of the 12-week exercise program.3,37 In contrast, another study of all sedentary, nonathletic patients found no significant improvement after a similar 12-week program. 57 Beyer et al 9 found that both eccentric training and heavy slow resistance training yielded clinical improvement in pain as well as significant reduction in tendon thickness and neovascularization. In a 5-year follow-up study, initial improvements were maintained as the average VISA-A score increased from 49.2 at baseline to 83.6 (N = 58) at the 5-year follow-up (P < .001) and from 75.0 at 1 year to 83.4 (N = 55) at the 5-year follow-up (P < .01). In total, 48.3% of patients did receive 1 or more alternative treatments. 69 Another study found no difference in outcome in twice-daily exercise regimens as compared to 2 sessions per week. 66
In the 11 studies in which eccentric exercises with an adjunctive treatment were assessed, there was little evidence of improvement over eccentric exercises alone. Three studies on eccentric exercises with orthotic devices found significant improvement in outcomes compared to baseline but no difference compared to eccentric exercises alone.31,43,51 The devices used were heel pads, custom orthoses, and the AirHeel brace. Two other studies showed similar findings regarding eccentric training with PRP injection.16,17 Boesen et al 10 did find a greater effect on pain, activity level, and tendon thickness and vascularity when eccentric training was combined with either PRP injection or high-volume injection of steroid, saline, and local anesthetic between the anterior aspect of the tendon and Kager’s fat pad. Additional studies investigating eccentric exercises in combination with other treatments such as laser therapy, prolotherapy, and ESWT also found no significant difference when compared with eccentric training alone.52,62,67,74 Yelland et al 74 reported more rapid improvements in pain symptoms when eccentric exercises were paired with prolotherapy but similar outcomes at 12 months.
PRP injections
PRP injection has been increasingly studied as a treatment option for noninsertional Achilles tendinopathy (NIAT), with 6 studies published since 2010. Of the 6 studies, 4 found significant improvements in VISA-A scores with PRP injection.19,20,22,30,56 However, the 1 randomized control trial did not report a significant difference compared to placebo saline injections at 3 months. 30 The intended 12-month follow-up was not adequately powered due to a high dropout rate. Salini et al 56 found better results in younger patients compared to patients above age 60 years in a retrospective study. A prospective cohort study noted significant improvement in VISA-A from baseline at 18-month follow-up (24 to 96; P = .000655). 22 While recent prospective and retrospective studies have shown promising results, more high-quality evidence is needed to fully support PRP injections in treating NIAT.
ESWT
ESWT has shown promising results as a treatment option, with 3 of 5 studies reporting a statistically significant improvement in either VISA-A or VAS scores compared to baseline.21,53,70 Of the 3 randomized controlled trials, Rompe et al 53 reported a significant improvement compared to the “wait and see” group, an increase in VISA-A from baseline to 4 months (50.3 to 70.4; P < .001). The authors found no statistical difference when ESWT was compared to eccentric loading. A further placebo-controlled RCT noted no significant difference in VAS pain score at 12 months. 12 A more recent 2017 RCT found ESWT to be less effective than peritendinous hyaluronic acid injection. 33 A case-control study comparing high-energy ESWT and traditional nonoperative therapies found lower VAS scores in the ESWT group at 1, 3, and 12 months. 21 Similar to PRP injections, extracorporeal shockwave therapy has shown promising results.
Other nonoperative treatments
The less frequently investigated treatment procedures included topical glyceryl trinitrate, polidocanol injection, alternative medicine, blood injection, hyaluronic acid injection, intense pulsed light, SVF injection, NSAIDs, and corticosteroids. A 3-year follow-up randomized control trial reported 28 of 32 tendons to be completely asymptomatic after continued treatment with topical glyceryl trinitrate therapy. 49 Three studies on sclerosing polidocanol injections found significant improvement in VAS pain scores.1,2,73 Acupuncture produced significant improvements in both VISA-A and VAS scores in another study. 75 Patients treated with SVF injection obtained faster relief (15- and 30-day follow-up) than those who received PRP injection. 68 Blood injections, intense pulsed light, aprotinin injections, and NSAIDs did not provide significant benefit.7,11,25,27,50
Operative Treatment
Operative management is indicated for noninsertional Achilles tendinopathy that is refractory to conservative treatments. Twenty-four studies that included 855 patients assessed 6 operative treatments for noninsertional Achilles tendinopathy (Table 3). The surgical procedures used were tenotomy and debridement, gastrocnemius recession, flexor hallucis longus tendon transfer, tendon release from ventral soft tissue, soleus fiber transfer, and the Topaz procedure. Again, several studies reported outcomes for different treatments and procedures and were categorized under multiple treatment modalities.
Functional Outcomes of Operative Treatments for Noninsertional Achilles Tendinopathy. a
Abbreviations: AOFAS, American Orthopaedic Foot & Ankle Society; ATSS, Achilles Tendinopathy Scoring System; DVT, deep vein thrombosis; FFI, Foot Function Index; FHL, flexor hallucis longus; RCT, randomized controlled trial; VAS, visual analog scale; VISA-A, Victorian Institute of Sports Assessment–Achilles questionnaire.
w: not significant; x: P < .05; y: P < .01; z: P < .001.
Includes studies categorized under multiple treatment modalities.
Tenotomy and debridement
Tenotomy and debridement remains the most extensively studied and supported operative method for noninsertional tendinopathy. Ten articles investigated tenotomy and debridement, including 1 RCT, 2 case-control studies, 6 prospective studies, and 1 retrospective study. Specific surgical techniques described as “tenotomy” and “debridement” varied across the studies. Seven studies performed traditional open tenotomy and debridement and 3 used minimally invasive techniques (endoscopic, ultrasound guided). Eight of those studies measured either significant improvement in VISA-A scores, excellent/good results in at least 75% of patients, or patient satisfaction in 90% of patients.8,36,39,42,45,47,58,64 Results were considered excellent if there was full return to activity with no residual symptoms, while good results consisted of a return to preoperative activity level with some stiffness/discomfort. Open tenotomy and debridement provided improved outcomes at final follow-up in each study in which it was performed, with only 2 delayed wound closures as complications out of 20 procedures. A case-control study comparing nonathletic and athletic (defined as having played at least club-level sports before symptom onset) patients reported better outcomes and less postoperative complications in the athletic group. 36 A similar study by the same authors found better outcomes in males compared to females. 35 A prospective cohort study reported endoscopic tenotomy and debridement provided complete resolution of symptoms at final follow-up (mean 7.7 years) in 96% of patients with minimal complications. 39 Another small prospective study on endoscopic tenotomy and debridement showed immediate pain relief that was consistent at 6-month follow-up. 65 Ultrasound-guided percutaneous tenotomy provided excellent/good results in 47 of 63 patients but was less effective in cases with more extensive tendinopathy. 64 Less invasive methods of tenotomy and debridement (endoscopic and ultrasound guided) have some evidence supporting their use and may ultimately have equal efficacy with a lower risk of complications, although complications are generally low for either option.
Gastrocnemius recession
As many surgeons believe that a tight gastrocnemius is related to the genesis of the pathology, recession of the gastrocnemius has been used to address NIAT. Seven studies since 2011 (2 retrospective studies and 5 case series) have assessed the use of gastrocnemius recession for this pathology. Recession of the medial head of the gastrocnemius in sedentary patients with NIAT resulted in improved VISA-A scores but decreased strength and circumference, although patients could still perform the same daily activities. 34 Another small retrospective study on gastrocnemius recession reported improvement in VAS pain score from 6.8 to 1.6 at a mean of 18 months of follow-up. 39 Three of the 5 case series reported a statistically significant improvement in their respective outcome measures at final follow-up.18,24,41 All 4 studies that reported functional outcome scores (VISA-A, American Orthopaedic Foot & Ankle Society [AOFAS]) noted significant improvement at final follow-up.18,24,29,41 Molund et al 41 found no difference in gastrocnemius-soleus function between the side that had a recession vs the normal leg at a 37.5-month follow-up. Duthon et al 18 reported a return to regular occupation for all 14 patients. Three studies reported complications, including deep vein thrombosis (DVT), sural nerve injury, Achilles tendon rupture, and wound infection.24,41,60
Flexor hallucis longus tendon transfer
The preliminary evidence for flexor hallucis longus (FHL) tendon transfer is less robust than that for gastrocnemius recession, although it has shown benefit regarding pain and function. Five case series have looked at FHL transfer for operative management of NIAT. Four of the studies also performed an Achilles tendon debridement before the FHL transfer. Martin et al 40 performed a whole Achilles excision in addition to the transfer and reported 95.5% of the patients had satisfactory pain relief. However, they did find significant strength deficits in plantarflexion. Another case series also found deficits in plantarflexion compared to US norms despite a postoperative AOFAS score of 86. 71 Only 1 study reported a statistical difference in outcome measure from pre- to postoperative, an improvement in VAS pain score from 7.5 to 0.6. 72 A series of 62 cases reported an improvement in modified AOFAS score (maximum 63) from 20.4 to 51.5. The authors did report 14 complications (9 patients with cellulitis and 5 with wound dehiscence). 13
Other operative treatments
Several studies have evaluated more novel procedures for NIAT treatment in comparison to traditional tenotomy and debridement. Release of the tendon from ventral soft tissue provided pain relief in 2 small prospective studies.2,4 Benazzo et al 8 investigated outcomes from transferring soleus fibers to degenerative tendons in athletes. Compared to traditional tenotomy, soleus fiber transfer resulted in similar functional outcome scores and faster recovery but also a higher incidence of tendon thickening. Postoperative complications included 3 delayed wound closures in the soleus fiber transfer group. A randomized control trial comparing the Topaz procedure (radiofrequency microdebridement) to traditional surgical decompression found no significant difference in VISA-A scores at 6-month follow-up. 42
Limitations
There was significant heterogeneity among and across the treatment categories. The number of studies under each treatment type ranged widely, with 10 or more for some procedures and only 1 or 2 for more uncommon methods. Treatment protocol, functional outcome measurement, and follow-up period varied greatly. Generally speaking, all of the surgical trials were limited by small sample sizes and methodologic issues (ie, retrospective without control or comparator). Furthermore, we had to exclude 21 studies from our review as the authors failed to distinguish whether the tendinopathy was insertional or noninsertional. While insertional and noninsertional tendinopathies are certainly related, there are significant enough differences in the respective pathologies to warrant their separate assessment. Although we attempted to include only the highest-level evidence, there is still a relatively low level of evidence among the included studies. It was not uncommon that some retrospective and prospective studies reported significant improvements compared to baseline, but a randomized controlled trial on the same treatment found no difference compared with the placebo group. As ever, more rigorous data are necessary to more definitively determine the most appropriate treatments, especially for newer operative techniques.
Conclusion and Clinical Recommendations
Many operative and nonoperative treatment options for noninsertional Achilles tendinopathy have been explored. Despite some more novel techniques providing benefit, the bulk of the evidence still supports eccentric training as the first-choice nonoperative treatment and tenotomy and tendon debridement as the first-choice operative treatment, with minimally invasive approaches potentially lowering the risk of complications. PRP injection and ESWT are well supported as second-line nonoperative measures. It should be noted that the level of evidence for the operative studies was considerably lower than nonoperative studies. FHL transfer and gastrocnemius recession have been shown to be beneficial in smaller nonrandomized case series. More high-level research is needed to explore these treatments and further substantiate their utility for noninsertional Achilles tendinopathy management. As with all operative treatment modalities, there is a higher risk of complications compared to conservative management. Better outcomes can be expected in younger, more active patients. In summary, we recommend an eccentric exercise regimen as the first-line treatment of noninsertional Achilles tendinopathy. PRP injection and ESWT can be used if eccentric training is insufficient, especially in those patients who are keen to avoid surgery. If conservative measures fail, tenotomy and debridement is indicated.
Supplemental Material
FAI914605_ICMJE – Supplemental material for Noninsertional Achilles Tendinopathy: Topical Review
Supplemental material, FAI914605_ICMJE for Noninsertional Achilles Tendinopathy: Topical Review by Ian Jarin, Henrik C. Bäcker and J. Turner Vosseller in Foot & Ankle International
Footnotes
Declaration of Conflicting Interests
The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article. ICMJE forms for all authors are available online.
Funding
The author(s) received no financial support for the research, authorship, and/or publication of this article.
References
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