Current Concepts Review: Insertional Achilles Tendinopathy

Transcription

1 FOOT &ANKLE INTERNATIONAL DOI: /FAI Current Concepts Review: Insertional Achilles Tendinopathy Todd A. Irwin, MD Ann Arbor, MI INTRODUCTION Pathology of the Achilles tendon is a common source of posterior ankle and heel pain. A variety of terms have been used to describe similar but clinically distinct conditions involving this tendon including tendinosis, tendinitis, paratenonitis, and peritendinitis. The latter are misleading because their suffixes imply an inflammatory process. However, inflammatory cells are rarely present in biopsies from involved tendons. 3 The most common histopathologic finding is a degenerative process characterized by disorganized collagen, abnormal neovascularization, necrosis and mucoid degeneration. 34,58 Based on these findings, Maffulli and colleagues advocated for the term tendinopathy to describe the syndrome characterized by pain, swelling and impaired performance. 39 While runners comprise the largest group of patients with chronic pain in the Achilles tendon, individuals of all activity levels and ages present with similar complaints. The location of the pain is an important discriminating factor, as insertional (tendon-bone junction) pain is often treated differently than noninsertional (2 to 6 cm proximal to the insertion) pain. This review will focus on insertional tendinopathy and will discuss related disorders including retrocalcaneal bursitis and Haglund s deformity. Recently, much has been learned regarding the pathophysiology of Achilles tendinopathy and this knowledge has lead to the development of new treatment options. However, the evidence to support these innovative approaches has not been appraised. This current concepts review will present the etiology, pathophysiology, and evaluate the merits of No benefits in any form have been received or will be received from a commercial party related directly or indirectly to the subject of this article. Corresponding Author: Todd A. Irwin, MD Clinical Assistant Professor Department of Orthopaedic Surgery University of Michigan 2098 S. Main St. Ann Arbor, MI tirwin@med.umich.edu For information on pricings and availability of reprints, call , x232. currently available treatment options for the management of insertional Achilles tendinopathy. BACKGROUND The etiology of Achilles tendinopathy is likely multifactorial. Numerous factors including pes cavus, hyperpronation, advancing age, hypertension, diabetes, obesity, steroid use, use of estrogen and fluoroquinolone antibiotics have been associated with Achilles tendon disorders. 6,23,34,52 Overuse and genetic predisposition are also believed to contribute to the onset of disease. 6,34,42 Shoewearmayalsoplayarole. Insufficient heel height, poor shock absorption, and wedging from uneven wear, are factors that may affect the stress applied to the tendon. Poor training habits including excessive training, training on hard or sloping surfaces, and abrupt changes in scheduling have been shown to contribute to the onset of tendinopathy. 6,34,52 Pain and swelling posterolaterally or anterior to the tendon, usually signifies retrocalcaneal bursitis. Meanwhile, a bony prominence present on the superolateral aspect of the calcaneal tuberosity is referred to as a Haglund s deformity (also called a pump bump). Pain and a tender subcutaneous adventitial bursa may occur over this prominence due to rubbing against the heel counter. While these two conditions are clinically distinct, both are often seen together and in conjunction with insertional Achilles tendinopathy. Most studies examining the epidemiology of Achilles tendinopathy have focused on the athletic population, specifically runners. One large retrospective study of competitive and recreational athletes with Achilles tendon problems reported that 66% had noninsertional tendinopathy and 23% had either retrocalcaneal bursitis or insertional tendinopathy. 33 Kujala and colleagues compared male runners to matched controls and found 29% of runners reported an overuse injury of the Achilles compared to 4% of a control group. 32 After following 60 elite runners, Lysholm and Wiklander reported an annual incidence of Achilles tendon disorders of 7% to 9%

2 934 Foot & Ankle International/Vol. 31, No. 10/October 2010 PATHOPHYSIOLOGY While advancing age, decreased vascularity and increased mechanical strain are frequently postulated as causative factors, the true pathogenesis of Achilles tendinopathy remains unknown. Lyman et al. investigated the distribution of tensile strain at the insertion of the Achilles tendon during functional range of motion. Based on the usual site of tendinopathy, they hypothesized that the location of highest strain would be anterior. Interestingly, their cadaveric biomechanical study showed increasing strain in the posterior portion of the tendon, with a trend toward decreasing strain in the anterior portion, thus describing a stress-shielding effect within the tendon. 37 A review of the biomechanical literature echoes this finding that the site affected with tendinopathy is generally stress shielded. 41 Rufai et al. described the tendency for cartilage-like changes to develop within the tendon on the stress-shielded side of the enthesis leading to intratendinous bone formation through endochondral ossification. 58 The work of Benjamin et al. suggests that that calcification and spur formation at the insertion is not dependent on inflammation or preceding microtears of the Achilles. These authors claim that spur formation was an adaptive process that increases the surface area at the bone-tendon junction, thereby protecting this area in the face of increased mechanical loads. 4 These findings suggest that the role of repetitive tensile loading in insertional Achilles tendinopathy is more complex than originally thought. Another common hypothesis maintains that decreased vascularity associated with advancing age contributes to overuse injury of the Achilles tendon. However, a recent study utilizing power Doppler ultrasound showed neovascularization in 55% of painful tendons compared to 4% of asymptomatic controls. 72 Knobloch et al. used laser Doppler flowmetry to reveal a significant elevation in microcirculatory blood flow within tendons with insertional and midsubstance disease compared to their uninvolved contralateral tendon and compared to a normal athletic control group. 31 These studies suggest the presence of a relationship between neovascularization and pain in tendinopathy, a reaction to a hypoxic, degenerative lesion within the tendon. CLINICAL PRESENTATION Patients will complain of pain, swelling, burning, and stiffness. They will frequently localize symptoms to the posterior midline of the tuberosity, but may identify a medial or lateral focus. Exercise, stair climbing, and running on hard surfaces are activities that exacerbate their symptoms. In the early stages, patients will report that their symptoms occur only after strenuous activity, but as the disease progresses and becomes chronic, any activity may cause symptoms, including walking. Patients may even experience symptoms at rest. Physical examination commonly reveals tenderness and swelling at the posterior aspect of the calcaneal tuberosity with a midline or posterolateral bony prominence. If the location of these findings is anterior, lateral, or less frequently medial to the tendon, then retrocalcaneal bursitis is more likely to be the diagnosis. IMAGING Weightbearing radiographs of the foot should be the initial imaging study. The anteroposterior view can identify a pes planovalgus or cavovarus foot. The width of the Achilles shadow and maintenance of Kager s triangle should be evaluated on the lateral view. The presence of intratendinous calcification and a bony spur is best seen on this view, but may also be appreciated on an axial view of the calcaneus. Magnetic resonance imaging (MRI) can provide additional information regarding the Achilles tendon. Most studies have evaluated MRI in the setting of chronic tendinopathy, both insertional and noninsertional. Karjalainen et al. evaluated 118 painful tendons and found that 15% had intrasubstance abnormalities within 2 cm of the insertion, 8% had increased signal in the calcaneus, and 19% had an enlarged retrocalcaneal bursa. 28 Haims et al. reviewed abnormal MR images in 94 feet and found only 64 were clinically symptomatic. The authors noted a significant overlap in findings between symptomatic and asymptomatic tendons, however, calcaneal edema was found almost exclusively in symptomatic patients. 19 Nicholson et al. retrospectively reviewed 157 patients with insertional Achilles tendinopathy, classified the degree of degeneration based on MRI findings, and predicted the success of nonoperative treatment based on the findings. They concluded that tendons with confluent areas of intrasubstance signal abnormalities are unlikely to respond to nonoperative treatment. 47 Shalabi proposed that serial studies could be used to monitor the effects of treatment for chronic Achilles tendinopathy. 59 The role of diagnostic ultrasound has increased in recent years. It is a less expensive alternative to MRI, and permits dynamic examination of the tendon. A case-control study showed enlargement of the mid and distal portions of the tendon, disruption of the fibrillar pattern, and an increase in vascularity in patients with chronic Achilles tendinopathy compared to normal controls. 36 Astrom et al. compared the images from ultrasound and MRI with surgical findings in 27 patients with chronic Achilles tendinopathy. They concluded both modalities gave similar information and may best be utilized as a prognostic instrument. 2 Overall, while neither ultrasound nor MRI is required to diagnose tendinopathy, both can assist in preoperative planning.

3 Foot & Ankle International/Vol. 31, No. 10/October 2010 INSERTIONAL ACHILLES TENDINOPATHY 935 NONOPERATIVE TREATMENT Activity and shoewear modification A period of rest or cessation of activities that incite symptoms is often the initial treatment for noninsertional tendinopathy. Often, the use of orthoses, heel lifts, braces and immobilization with a cast or pneumatic walking boot is combined with this period of modified activity. It is a generally held consensus that one or more of these options should be pursued prior to initiating any invasive treatments (Level V evidence), and there are no published studies documenting the efficacy of these options for insertional Achilles tendinopathy. Given this lack of data, insufficient evidence exists to recommend for or against the use of rest, activity and shoewear modification as treatment for this disorder (Grade I recommendation). Eccentric training Eccentric training, during which the tendon unit is lengthened during simultaneous muscle contraction, has shown good results in the treatment of noninsertional Achilles tendinopathy. 12,70 However, consistent results have not been observed with insertional tendinopathy. In one study, only 32% of patients with insertional Achilles tendinopathy demonstrated satisfactory results compared to 89% of patients with noninsertional pain. 12 Jonsson et al. evaluated a new protocol for eccentric training that eliminated ankle dorsiflexion to avoid impingement between the Achilles tendon, retrocalcaneal bursa and calcaneus which was the presumed source of prior poor results for insertional tendinopathy. This short-term pilot study (Level III evidence) showed improved clinical results in 67% of patients. 27 Knobloch et al. investigated the physiologic effects of eccentric training on diseased Achilles tendons compared to controls for 12 weeks (Level I evidence). Pain levels in the study group decreased by 48%; though this group contained patients with both insertional tendinopathy (nine of 15) and noninsertional tendinopathy (six of 15). All study group patients showed evidence for preserved paratendon oxygen saturation. Paratendinous postcapillary venous filling pressure, which can decrease the venous congestion seen in inflammation, was reduced in the Achilles midportion and deep insertional areas, but was increased at the superficial insertional region. 30 Eccentric training has been compared to extracorporeal shock wave therapy, in a randomized, controlled trial of patients with chronic insertional Achilles tendinopathy (Level I evidence). This study showed that the results for eccentric training were inferior, although the protocol for eccentric training utilized maximum dorsiflexion of the ankle. 57 Based on the limited data available evaluating the effects of eccentric training on insertional Achilles tendinopathy, there is insufficient evidence to support the use of this modality for this condition (Grade I recommendation). Extracorporeal shock wave therapy (ESWT) Extracorporeal shock wave therapy has been used to treat multiple orthopaedic disorders including plantar fasciitis, shoulder calcific tendinitis and lateral epicondylitis. 14,15,48 ESWT is hypothesized to improve symptoms by promoting neovascularization and angiogenesis at the tendon-bone junction and inducing degeneration of epidermal nerve fibers with subsequent reinnervation. 50,64 Randomized controlled trials comparing ESWT to placebo in noninsertional Achilles tendinopathy have shown conflicting results. 8,55 Two studies specifically evaluating the effect of ESWT on insertional Achilles tendinopathy have been reported. A Level III case-control study comparing high-energy ESWT to nonoperative therapy showed significant improvement in pain scores in the ESWT group. 13 This study also suggested a local anesthesia field block done prior to the application of the shock waves may decrease the effectiveness. Rompe et al. performed a randomized controlled trial comparing the effectiveness of eccentric loading therapy to low-energy ESWT (Level I evidence). While on average the outcome measures and pain scores improved for both groups, the low-energy ESWT group had significantly more favorable results than the eccentric loading group. 57 This study did not include a sham treatment group. Therefore, the contribution of a placebo effect to the shockwave results was not assessed. The limited number of studies in the literature and the variation in the timing and dosing of shockwaves provides insufficient evidence to support the use of ESWT in the treatment of insertional Achilles tendinopathy (Grade I recommendation). Corticosteroid injections Corticosteroid injections have been used to treat multiple orthopaedic conditions, including acute and chronic tendon disorders. 53 No consensus exists regarding their efficacy and concern for rupture after injection has limited their use in the management of insertional Achilles tendinopathy. 1,16,60 Animal studies have shown that collagen breakdown, cell death, and adverse biomechanical properties occur when corticosteroid is injected directly into a tendon. 24,25,53 Metcalfe et al. performed a systematic review to evaluate the effects of glucocorticoid injections into diseased Achilles tendons. Only 5 studies met their inclusion criteria, including one randomized controlled trial, three retrospective studies and one prospective case series. No study looked exclusively at insertional Achilles tendinopathy. Four examined peritendinous injection and one study assessed an intratendinous injection. The randomized controlled trial indicated there was no value in the use of peritendinous corticosteroid injection, while the remaining studies showed variable pain relief and safety. 45 In addition, while one study demonstrated the efficacy of using ultrasound guidance for peritendinous injection, the adherent nature of the paratenon near the Achilles insertion especially in affected tendons would make this approach

4 936 Foot & Ankle International/Vol. 31, No. 10/October 2010 difficult. Based on the lack of dedicated studies to the insertional region of the Achilles and the inherent risk of tendon rupture, there is insufficient evidence to support the use of corticosteroid injections for insertional Achilles tendinopathy (Grade I recommendation). Sclerosing therapy To test the theory that neovascularization contributes to the pain associated with tendinopathy, investigators have studied the effect of sclerosing therapy. Polidocanol is a sclerosing agent that destroys the neovessels and presumably, the adjacent nerves. Good results have been demonstrated for the use of this agent in the treatment of midsubstance Achilles tendinopathy. 7 A subsequent pilot study evaluated sclerosing therapy in chronic insertional tendinopathy. The short-term results showed increased patient satisfaction and decreased pain levels in eight of 11 patients. 49 A report of a single case of tendon rupture in an elite athlete after sequential injections with sclerosing agents has been reported. 20 The paucity of data lacks sufficient evidence to support the use of sclerosing therapy for insertional Achilles tendinopathy (Grade I recommendation). OPERATIVE TREATMENT Patients who do not respond to conservative treatment may become candidates for operative management. No consensus exists regarding the duration of conservative treatment before surgery, though most clinicians consider 3 to 6 months the minimum time necessary to assess its effect. The surgery typically includes excision of the retrocalcaneal bursa, resection of the prominent superior calcaneal tuberosity, and debridement of degenerative tendon including calcifications and, if necessary, reattachment of the tendon to bone. Several studies have investigated open retrocalcaneal decompression and tendon debridement through a variety of approaches. 29,62,66,71 Watson et al. compared the results of 16 cases of retrocalcaneal bursitis and 22 cases of bursitis with calcific insertional Achilles tendinopathy. Both groups were treated with an open retrocalcaneal decompression through a posterolateral approach and the latter group had a debridement of the Achilles with minimal detachment of the tendon. The patients with calcific insertional Achilles tendinopathy reported a significantly lower rate of satisfaction, more pain, more shoewear restrictions, and nearly twice as much time to reach symptomatic improvement 66 (Level II evidence). Yodlowski et al. retrospectively reviewed the results of 35 patients treated with open retrocalcaneal decompression through a lateral incision (Level IV evidence). In this study, intratendinous calcifications were excised through a longitudinal incision. Ninety percent of patients reported complete or significant relief of symptoms, and the remaining 10% felt improved 71 Another investigation evaluated the results of open retrocalcaneal decompression through a medially based J-shaped incision and compared partial or no detachment of the Achilles insertion with complete detachment and proximal V-Y lengthening (Level III evidence). The tendons were reattached to bone with suture anchors. Both groups demonstrated high rates of satisfaction with no significant difference found in subjective measures of clinical outcome. 63 Maffulli et al. achieved good clinical results through a medial approach and a variable amount of tendon detachment that was based on the extent of calcific tendinopathy present at the insertion. The number of suture anchors used for reattachment was based on the amount of tendon detached from its insertion 40 (Level IV evidence). A central tendon splitting approach has also provided good clinical results. 26,44 In these studies, suture anchors were used for reattachment when greater than 50% of the tendon was detached from its insertion,. In one study, age greater than 55 years correlated with advanced disease found intraoperatively and a trend towards a poor clinical outcome. 44 Interestingly, another study found no significant difference in outcome between patients older or younger than 50 years using a similar surgical technique 26 (Level IV studies). Decompression of the retrocalcaneal space can be performed endoscopically. This technique can address bony and soft tissue impingement, although its ability to debride the tendon and remove calcifications is limited. Leitze et al. compared the results of endoscopic and open decompression (Level II evidence). Both techniques had similar outcome scores and recovery times, however patients treated endoscopically had fewer complications and a better cosmetic result. 35 Two separate case series have reported good clinical outcomes with endoscopic decompression, however one of these studies reported an Achilles tendon rupture 3 weeks after surgery 51,61 (Level IV evidence). Many authors advocate for the addition of a tendon transfer after debridement and/or reattachment of the Achilles tendon. Transfer of the flexor hallucis longus (FHL) tendon is the preferred reconstruction based on its excellent strength, inphase contraction, and low-lying muscle belly to enhance the perfusion and healing of the reconstruction. 65 Several studies have investigated the use of FHL tendon transfer for chronic Achilles tendon ruptures and noninsertional Achilles tendinosis. 18,43,65,67,68 Wapner et al. initially described a double-incision harvest technique using a medial midfoot incision for distal release of the FHL. 65 Hansen and more recently Den Hartog have described a single-incision FHL harvest technique. 10,21 Two studies have evaluated the use of an FHL tendon transfer in patients with insertional Achilles tendinopathy treated with partial calcaneal ostectomy, intratendinous debridement with or without reattachment. Den Hartog reviewed his results with 29 cases in 26 patients (27 of 29 cases were insertional Achilles tendinopathy) (Level IV evidence). He found significant improvement in AOFAS ankle-hindfoot scores and 88% rate of patient satisfaction.

5 Foot & Ankle International/Vol. 31, No. 10/October 2010 INSERTIONAL ACHILLES TENDINOPATHY 937 The subgroup of patients greater than 50 years of age had at least as good an outcome as those less than 50 years. 10 Elias et al. utilized the same single-incision technique described by Den Hartog; however, in their study the FHL tendon was fixated in the calcaneus using a bioabsorbable interference screw 11 (Level IV evidence). In addition to excellent AOFAS ankle-hindfoot scores and significantly improved VAS pain score, there was no loss of plantarflexion strength or power, and only a four degree loss of active ankle range of motion. The rate of satisfaction in this study was 95%. A third study reported similar functional outcome and pain scores with the single incision technique. However, it was unclear if the patients with chronic Achilles tendinopathy were insertional or noninsertional 69 (Level IV evidence). Overall, the operative management of insertional Achilles tendinopathy is supported by the literature. The consistently good results from a spectrum of high and low quality investigations constitute fair evidence to support the excision of the superior calcaneal tuberosity, decompression of the retrocalcaneal bursa and debridement of insertional Achilles tendinopathy through an open procedure utilizing a medial, lateral or central tendon-splitting approach (Grade B recommendation). The paucity of evidence from well-designed comparative studies prevents a recommendation of one technique over another regarding the method of debridement, reattachment or fixation of the Achilles tendon. Partial or complete detachment from the insertion may be necessary to debride and remove intrasubstance calcifications adequately from the Achilles tendon. The decision to reattach and secure the tendon to bone with fixation occurs at the discretion of the surgeon. At this time, the evidence is insufficient to support the performance of these procedures endoscopically (Grade I recommendation). Lastly, the favorable results reported with transfer of the FHL tendon after debridement, reattachment, or both provides level IV evidence to support the use of this procedure (Grade B recommendation). Operative complications One series with a large cohort looked specifically at the rate of complication after the surgical management of chronic Achilles tendinopathy and reported an overall complication rate of 11%. In the insertional tendinopathy subgroup, a 4.7% complication rate was observed, including one skin necrosis, one superficial wound infection, two hematomas, and one fibrotic reaction or scar formation. 54 Avulsion of the Achilles tendon has been reported, and is usually precipitated by a fall that occurs in the early postoperative period. 5,63,66 Major wound complications, although rare, are potentially devastating. 63 Fortunately, the most common wound complications reported are related to the scar, with hypersensitivity, hypertrophy, and numbness frequently mentioned. Other complications reported include delayed wound healing, superficial infection, sural neuritis, recurrence of pain, and deep vein thrombosis. 26,40,44,63,66,71 Complications specific to FHL tendon transfer have also been reported. Medial plantar nerve transection and hallux cock-up deformity have been reported with the doubleincision technique. 18,22 A cadaver study showed injury to either the medial plantar nerve or lateral plantar nerve in 33% of specimens after the medial midfoot harvest of the FHL in the double-incision technique. 46 Decreased flexion power at the hallux interphalangeal joint was shown after singleincision FHL tendon transfer, although patient function was high. 56 The effect of FHL transfer on forefoot loading remains uncertain. 9,17,56 SUMMARY 1. Achilles tendinopathy is a clinical syndrome characterized by the combination of pain, swelling and impaired performance. Insertional tendinopathy is located at the tendon-bone junction on the posterior calcaneus, and noninsertional tendinopathy is usually located 2 to 6 cm proximal to the insertion. 2. The etiology of Achilles tendinopathy is multifactorial including anatomic factors such as hindfoot alignment, medical factors such as diabetes and fluoroquinolone use, mechanical factors such as shoewear and heel height, and training factors such as overuse. Genetic predisposition may also play a role. 3. The true pathogenesis of insertional Achilles tendinopathy is unknown. Studies suggest that there is a stressshielding effect on the anterior portion of the Achilles insertion, which may lead to calcification and spur formation. Neovascularization at the Achilles insertion has also been demonstrated, with some evidence this is one source of pain. Studies also suggest a degenerative process as opposed to an inflammatory process based on biopsy specimens. 4. While eccentric exercise has shown good results in the treatment of noninsertional Achilles tendinopathy, there is conflicting evidence and few quality studies investigating the effect of this treatment on insertional Achilles tendinopathy (Grade I recommendation). 5. Other conservative treatments such as extracorporeal shockwave therapy, corticosteroid injections, and sclerosing agents have been studied, though at this time there is insufficient evidence to support the use of one modality over another of these modalities (Grade I recommendation). 6. Fair evidence exists to support the use of surgical decompression of insertional Achilles tendinopathy that has failed conservative treatment (Grade B recommendation). Augmentation with a FHL transfer has gained in popularity, though currently only fair evidence exists to support the use of this procedure (Grade B recommendation).

6 938 Foot & Ankle International/Vol. 31, No. 10/October 2010 REFERENCES 1. Astrom, M: Partial rupture in chronic Achilles tendinopathy. A retrospective analysis of 342 cases. Acta Orthop Scand. 69:404 7, Astrom, M; Gentz, CF; Nilsson, P; et al.: Imaging in chronic Achilles tendinopathy: a comparison of ultrasonography, magnetic resonance imaging and surgical findings in 27 histologically verified cases. Skel Radiol. 25:615 20, Astrom, M; Rausing, A: Chronic Achilles tendinopathy. A survey of surgical and histopathologic findings. Clin Orthop Rel Res. 316:151 64, Benjamin, M; Rufai, A; Ralphs, JR: The mechanism of formation of bony spurs (enthesophytes) in the Achilles tendon. Arthritis Rheum. 43:576 83, Calder, JD; Saxby, TS: Surgical treatment of insertional Achilles tendinosis. Foot Ankle Int. 24:119 21, Clement, DB; Taunton, JE; Smart, GW: Achilles tendinitis and peritendinitis: Etiology and treatment. Am J Sports Med. 12:179 84, Clementson, M; Loren, I; Dahlberg, L; Astrom, M: Sclerosing injections in midportion Achilles tendinopathy: a retrospective study of 25 patients. Knee Surg Sports Traum Arthrosc. 16:887 90, Costa, ML; Shepstone, L; Donell, ST; Thomas, TL: Shock Wave Therapy for Chronic Achilles Tendon Pain. A Randomized Placebo-controlled Trial. Clin Orthop Rel Res. 440: , Coull, R; Flavin, R; Stephens, MM: Flexor hallucis longus tendon transfer: evaluation of postoperative morbidity. Foot Ankle Int. 24:931 4, Den Hartog, BD: Flexor Hallucis Longus Transfer for Chronic Achilles Tendonosis. Foot Ankle Int. 24:233 7, Elias, I; Raikin, SM; Besser, MP; Nazarian, LN: Outcomes of Chronic Insertional Achilles Tendinosis Using FHL Autograft Through Single Incision. Foot Ankle Int. 30: , Fahlstrom, M; Jonsson, P; Lorentzon, R; Alfredson, H: Chronic Achilles tendon pain treated with eccentric calf-muscle training. Knee Surg Sports Traum Arthrosc. 11:327 33, dx.doi.org/ /s z 13. Furia, JP: High-energy extracorporeal shock wave therapy as a treatment for insertional Achilles tendinopathy. Am J Sports Med. 34:733 40, Furia, JP: Safety and efficacy of extracorporeal shock wave therapy for chronic lateral epicondylitis. Am J Orthop. 24:13 9, Gerdesmeyer, L; Wagenpfeil, S; Haake, M; et al.: Extracorporeal shock wave therapy for the treatment of chronic calcifying tendonitis of the rotator cuff: a randomized controlled trial. JAMA. 290: , Gill, SS; Gelbke, MK; Mattson, SL; Anderson, MW; Hurwitz, SR: Fluoroscopically Guided Low-Volume Peritendinous Corticosteroid Injection for Achilles Tendinopathy. A Safety Study. J Bone Joint Surg Am. 86:802 6, Hahn, F; Maiwald, C; Horstmann, T; Vienne, P: Changes in plantar pressure distribution after Achilles tendon augmentation with flexor hallucis longus transfer. Clin Biomech. 23:109 16, Hahn, F; Meyer, P; Maiwald, C; Zanetti, M; Vienne, P: Treatment of Chronic Achilles Tendinopathy and Ruptures with Flexor Hallucis Tendon Transfer: Clinical Outcome and MRI Findings. Foot Ankle Int. 29: , Haims, AH; Schweitzer, ME; Patel, RS; Hecht P; Wapner, KL: MR imaging of the Achilles tendon: overlap of findings in symptomatic and asymptomatic individuals. Skel Radiol. 29:640 5, Hamilton, B; Remedios, D; Loosemore, M; Maffulli, N: Achilles tendon rupture in an elite athlete following multiple injection therapies. J Sci Med Sport. 11:566 8, Hansen, ST: Trauma to the heel cord. In: MH Jahss, (ed.) Disorders of the Foot and Ankle, 2nd ed, WB Saunders, Philadelphia, P , Herbst, SA; Miller, SD: Transection of the medial plantar nerve and hallux cock-up deformity after flexor hallucis longus tendon transfer for Achilles tendinitis: case report. Foot Ankle Int. 27:639 41, Holmes, GB; Lin, J: Etiologic factors associated with symptomatic Achilles tendinopathy. Foot Ankle Int. 27:952 9, Hossain, MA; Park, J; Choi, SH; Kim, G: Dexamethasone induces apoptosis in proliferative canine tendon cells and chondrocytes. Vet Comp Orthop Traum. 21:337 42, Hugate, R; Pennypacker J; Saunders, M; Juliano, P: The Effects of Intratendinous and Retrocalcaneal Intrabursal Injections of Corticosteroid on the Biomechanical Properties of Rabbit Achilles Tendons. J Bone Joint Surg Am. 86: , Johnson, KW; Zalavras, C; Thordarson, DB: Surgical management of insertional calcific Achilles tendinosis with a central tendon splitting approach. Foot Ankle Int. 27:245 50, Jonsson, P; Alfredson, H; Sunding, K; Fahlstrom, M; Cook, J: New regimen for eccentric calf-muscle training in patients with chronic insertional Achilles tendinopathy: results of a pilot study. Br J Sports Med. 42:746 9, Karjalainen, PT; Soila, K; Aronen, HJ; et al.: MR Imaging of Overuse Injuries of the Achilles Tendon. Am J Roent. 175:251 60, Keck, SW; Kelly, PJ: Bursitis of the Posterior Part of the Heel: Evaluation of surgical treatment of eighteen patients. J Bone Joint Surg Am. 47:267 73, Knobloch, K; Kraemer, R; Jagodzinski, M; et al.: Eccentric training decreases paratendon capillary blood flow and preserves paratendon oxygen saturation in chronic Achilles tendinopathy. J Orthop Sports Phys Ther. 37:269 76, Knobloch, K; Kraemer, R; Lichtenberg, A; et al.: Achilles tendon and paratendon microcirculation in midportion and insertional tendinopathy in athletes. Am J Sports Med. 34:92 7, dx.doi.org/ / Kujala, UM; Sarna, S; Kaprio, J: Cumulative incidence of Achilles tendon rupture and tendinopathy in male former elite athletes. Clin J Sport Med. 15:133 5, Kvist, M: Achilles tendon injuries in athletes. Ann Chir Gynaecol. 80: , PMid: Kvist, M: Achilles Tendon Injuries in Athletes. Sports Med. 18: , Leitze, Z; Sella, EJ; Aversa, JM: Endoscopic Decompression of the Retrocalcaneal Space. J Bone Joint Surg Am. 85: , Leung, JLY; Griffith, JF: Sonography of Chronic Achilles Tendinopathy: A Case-Control Study. J Clin Ultrasound. 36:27 32, Lyman, J; Weinhold, PS; Almekinders, LC: Strain behavior of the distal Achilles tendon: implications for insertional Achilles tendinopathy. Am J Sports Med. 32:457 61, / Lysholm, J; Wiklander, J: Injuries in runners. Am J Sports Med. 15:168 71, Maffulli, N; Khan, KM; Puddu, G: Overuse tendon conditions: time to change a confusing terminology. Arthroscopy. 14:840 3,

7 Foot & Ankle International/Vol. 31, No. 10/October 2010 INSERTIONAL ACHILLES TENDINOPATHY Maffulli, N; Testa, V; Capasso, G; Sullo, A: Calcific insertional Achilles tendinopathy: reattachment with bone anchors. Am J Sports Med. 32:174 82, Maganaris, CN; Narici, MV; Maffulli, N: Biomechanics of the Achilles tendon. Disab Rehab. 30:1542 7, / Magra, M; Maffulli, N: Genetic aspects of tendinopathy. J Sci Med Sport. 11:243 7, Martin, RL; Manning, CM; Carcia, CR; Conti, SF: An outcome study of chronic Achilles tendinosis after excision of the Achilles tendon and flexor hallucis longus tendon transfer. Foot Ankle Int. 26:691 7, McGarvey, WC; Palumbo, RC; Baxter, DE; Leibman, BD: Insertional Achilles tendinosis: surgical treatment through a central tendon splitting approach. Foot Ankle Int. 23:19 25, Metcalfe, D; Achten, J; Costa, ML: Glucocorticoid injections in lesions of the Achilles tendon. Foot Ankle Int. 30:661 5, Mulier, T; Rummens, E; Dereymaeker, G: Risk of neurovascular injuries in flexor hallucis longus tendon transfers: an anatomic cadaver study. Foot Ankle Int. 28:910 5, FAI Nicholson, CW; Berlet, GC; Lee, TH: Prediction of the success of nonoperative treatment of insertional Achilles tendinosis based on MRI. Foot Ankle Int. 28:472 7, Ogden JA; Alvarez, RG; Levitt, RL; Johnson, JE; Marlow, ME: Electrohydraulic high-energy shock-wave treatment for chronic plantar fasciitis. J Bone Joint Surg Am. 86: , Ohberg, L; Alfredson, H: Sclerosing therapy in chronic Achilles tendon insertional pain results of a pilot study. Knee Surg Sports Traum Arthrosc. 11:339 43, Ohtori, S; Inoue, G; Mannoji, C; et al.: Shock wave application to rat skin induces degeneration and reinnervation of sensory nerve fibres. Neurosci Lett. 315:57 60, Ortmann, FW; McBryde, AM: Endoscopic bony and soft-tissue decompression of the retrocalcaneal space for the treatment of Haglund deformity and retrocalcaneal bursitis. Foot Ankle Int. 28:149 53, Paavola, M; Kannus, P; Jarvinen, TAH; et al.: Achilles Tendinopathy. J Bone Joint Surg Am. 84: , Paavola, M; Kannus, P; Jarvinen, TAH; et al.: Treatment of tendon disorders: Is there a role for corticosteroid injection? Foot Ankle Clin. 7:501 13, Paavola, M; Orava, S; Leppilahti, J; Kannus, P; Jarvinen, M: Chronic Achilles tendon overuse injury: complications after surgical treatment. An analysis of 432 consecutive patients. Am J Sports Med. 28:77 82, Rasmussen, S; Christensen, M; Mathiesen, I; Simonson, O: Shockwave therapy for chronic Achilles tendinopathy: a double-blind, randomized clinical trial of efficacy. Acta Orthop. 79:249 56, Richardson, DR; Willers, J; Cohen, BE; et al.: Evaluation of the hallux morbidity of single-incision flexor hallucis longus tendon transfer. Foot Ankle Int. 30:627 30, FAI Rompe, JD; Furia J, Maffulli, N: Eccentric Loading Compared with Shock Wave Treatment for Chronic Insertional Achilles Tendinopathy. A randomized, controlled trial. J Bone Joint Surg Am. 90:52 61, Rufai, A; Ralphs, JR; Benjamin, M: Structure and Histopathology of the Insertional Region of the Human Achilles Tendon. J Orthop Res. 13:585 93, Shalabi, A: Magnetic resonance imaging in chronic Achilles tendinopathy. Acta Radiol Suppl (Stockholm). 432:1 45, dx.doi.org/ / Speed, CA: Corticosteroid injections in tendon lesions. BMJ. 323:382 6, van Dijk, CN; van Dyk, GE; Scholten, PE; Kort, NP: Endoscopic calcaneoplasty. Am J Sports Med. 29:185 9, Vulpiani, C; Guzzini, M; Ferretti, A: Operative treatment of chronic Achilles tendinopathy. Int Orthop. 27:307 10, dx.doi.org/ /s Wagner, E; Gould, JS; Kneidel, M; Fleisig, GS; Fowler, R: Technique and results of Achilles tendon detachment and reconstruction for insertional Achilles tendinosis. Foot Ankle Int. 27:677 84, Wang, CJ; Wang, FS; Yang, KD; et al.: Shock wave therapy induces neovascularization at the tendon-bone junction. A study in rabbits. J Orthop Res. 21:984 9, Wapner, KL; Pavlock, GS; Hecht, PJ; Naselli, F; Walther, R: Repair of chronic Achilles tendon rupture with flexor hallucis longus tendon transfer. Foot Ankle. 14:443 9, Watson, AD; Anderson, RB; Davis, WH: Comparison of results of retrocalcaneal decompression for retrocalcaneal bursitis and insertional Achilles tendinosis with calcific spur. Foot Ankle Int. 21:638 42, Wegrzyn, J; Luciani, J; Philippot, R; et al.: Chronic Achilles tendon rupture reconstruction using a modified flexor hallucis longus transfer. Int Orthop. Epub ahead of print, Wilcox, DK; Bohay, DR; Anderson, JG: Treatment of chronic Achilles tendon disorders with flexor hallucis longus tendon transfer/augmentation. Foot Ankle Int. 21: , Will, RE; Galey, SM: Outcome of Single Incision Flexor Hallucis Longus Transfer for Chronic Achilles Tendinopathy. Foot Ankle Int. 30:315 7, Woodley, BL; Newsham-West, RJ; Baxter, GD: Chronic tendinopathy: effectiveness of eccentric exercise. Br J Sports Med. 41:188 98, Yodlowski, ML; Scheller, AD Jr; Minos, L: Surgical treatment of Achilles tendinitis by decompression of the retrocalcaneal bursa and the superior calcaneal tuberosity. Am J Sports Med. 30:318 21, Zanetti, M; Metzdorf, A; Kundert, H; et al.: Achilles tendons: Clinical relevance of neovascularization diagnosed with power Doppler US. Radiology. 227:556 60, radiol