Emerging Insights On Insertional Calcific Achilles Tendinosis

The high impacts on the Achilles tendon during sports can leave athletes at risk for insertional calcific Achilles tendinosis. Accordingly, this author offers examination pearls, reviews conservative and surgical treatment options, and discusses post-op principles.

Insertional calcific Achilles tendinosis is an overuse injury that commonly occurs in athletes, particularly those involved in long-distance running (marathons, triathlons), jumping sports, skiing and skating. Patients often describe the pain at the insertion of the Achilles tendon and its insertion into an altered bony configuration of the calcaneus. This condition, which is common among “baby boomer athletes,” is typically associated with hypertrophy of the posterior portion of the calcaneus, a prominent posterosuperior angle “calcaneal step,” retrocalcaneal bursitis and an insertional traction exostosis with ossification or spurring of the Achilles tendon creating a calcific tendinosis.

Additionally, calcification can occur within the tendon body itself. This can create a functional shortening of the Achilles tendon, placing a strain on the tendon and causing chronic irritation as well as increased shoe pressure. Chronic traction forces upon the Achilles tendon can result in fracturing or fragmentation of the spur. This can be due to a violent impact of the foot on the ground during sporting activity. Fractures of the hyperostosis can also result from a forced eccentric contraction (loading) of the Achilles and the gastrocnemius soleus due to sudden excessive dorsiflexion. Microavulsions, again due to excessive traction forces of the Achilles at the level of the insertion, can result in similar pathology.¹

Although the exact etiology of the calcific tendinitis and tendinosis is not known, researchers believe the condition is related to age, overuse and enthesopathies, and note it has a high recurrence rate.²  

The Achilles tendon is subject to forces as great as 900 kg during periods of intense physical activity. Examples include speed or interval running, acceleration in football playing, volleyball jumping, mogul skiing, ice skating, etc. Similar pathological changes occur at the origin of the plantar fascia as well as the Achilles at its insertion. Anatomically, the posterosuperior prominence or the bursal projection of the calcaneus functions to lengthen the lever arm of the Achilles tendon, increasing the mechanical advantage of the gastrocnemius soleus when the ankle dorsiflexes. The stress on the Achilles varies between 2,000 and 7,000 Newtons of force.

The tendo-Achilles experiences forces of six to ten times body weight during a running cycle.³ Due to the Achilles’ insertion point into the calcaneus, talocalcaneal motion places an uneven rotational stress on the tendon fibers.⁴ The insertion of the Achilles tendon bears high loads and is typically the site of localized pain. “Achilles tendinitis” is the general term commonly used for this type of pain. However, “Achilles tendinosis” is a more accurate term for the condition. Enthesopathy describes the disease process specifically involving the enthesis, which is the insertion of tendon, fascia, muscle or articular capsule into bone.⁵

The pathophysiology of insertional Achilles tendinosis results most commonly from “accumulated impact loading.”⁶ Some have proposed that the Achilles tendinosis is a true inflammatory reaction within the tendon as opposed to the tendinopathy present in non-insertional Achilles tendinosis. What occurs is a combination of chronic overuse associated with retrocalcaneal bursitis and bony impingement, creating a chronic inflammatory response with chemical attrition and mechanical abrasion of the Achilles tendon.

We may consider the formation of cartilage-like changes in the enthesis a physiologic adaptation to the compressive loads. As a result, the tendon may not maintain its ability to withstand high tensile loads. As the stress shielding increases, it may lead to tensile weakening over time. Accordingly, an injury may occur more easily in this region. Therefore, we could consider insertional tendinosis an overuse injury but patients are predisposed by preexisting weakening of the tendon. The condition strongly correlates with age and we may consider it an “underuse” injury rather than an overuse injury due to stress shielding.⁷

Microscopic changes within the tendon include fibrinoid and myxomatous degeneration, fibrosis and eventual metaplastic calcification, creating thickening and nodularity of the tendon.⁸ Another area of interest is that after the third and fourth decades of life, there is a significant decrease in blood flow to the tendon. This reduction of blood flow primarily affects the region of the Achilles tendon 2-6 cm superior to its insertion, which is the site where rupture most often occurs.^9,10 It is rare to see distal tears of the Achilles tendon through areas of calcification just proximal to the insertion. These tears are commonly visible when there is a concomitant posterosuperior calcaneal prominence, often referred to as a “calcaneal step.” During dorsiflexion the tendon often becomes irritated, which then leads to thickening and microscopic tearing of the tendon.

Essential Diagnostic Pearls
The physical examination typically will demonstrate a retrocalcaneal exostosis at the insertion of the Achilles with or without calcification within the tendon itself. The hyperostosis may be visible as a “wraparound” enlargement of the calcaneus (both medially and laterally). The patient will often describe a dull, aching soreness or a sharp pain at the insertion upon dorsiflexion, occasionally with lateral radiating pain along the course of the sural nerve. It is not unusual to see entrapment of the nerve due to chronic irritation causing adhesions and scar tissue surrounding the nerve.

I advise physically comparing the two heel regions as a thickening of the Achilles tendon will be visible at the insertion on the pathological side. The patient/athlete will describe pain during the activity that one can reproduce upon direct palpation or with active/passive ankle joint range of motion. Schepsis and colleagues noted that ankle joint passive dorsiflexion will be decreased (equinus) on the symptomatic side.¹¹ As a result of chronic inflammatory infiltrate and fibrin deposition within the tendon, one may reproduce crepitus upon ankle joint dorsiflexion.  

What You Should Know About Conservative Treatment
I advise conservative treatment of the insertional tendinopathy, paratendinitis and calcific tendinosis, particularly in active patients or athletes. The management is similar for a patient with a painful Haglund’s deformity. The use of physical therapy modalities is an example. These treatments include ice massage, eccentric stretching and strengthening exercises, and cross-friction massage. The stretching program should pay particular attention to the gastrocnemius soleus complex, due to tightness in the posterior muscle group. Other physical therapy modalities include nerve stimulation, ultrasound and iontophoresis patches.

Oral and topical non-steroidal anti-inflammatory medications (NSAIDs) can also be beneficial.

Extracorporeal shockwave therapy has proven to be an effective conservative alternative.¹² Although research studies have shown that platelet-rich plasma (PRP) has great promise, evidence-based studies have not concluded that it has a high success rate for treating Achilles tendinosis.¹³ One of the advantages of PRP is that it does not cause degeneration or inhibit the healing process, but does activate hormonal response.

Platelet rich plasma is indicated for patients who have failed previous treatment or those who are unable to tolerate oral NSAIDs.

As an alternative, cortisone injections do reduce inflammation but can cause weakening of structures and potential rupture. The injections typically will mask the problem until the healing process begins. In the case of an inflamed retrocalcaneal or insertional bursa, one may use a one-time injection of corticosteroid, homeopathic medication or PRP, followed by cessation of all physical activity for two weeks.² When a posterior prominence of the calcaneus is present, clinicians may use an athletic shoe modification with accommodative padding surrounding the posterior heel counter to reduce the friction and irritation.

Another conservative intervention is prescribing an orthotic with a mild heel raise, which will help neutralize the irritation to the heel and prevent the development of chronic changes with the condition. Conservative treatment of insertional Achilles tendinosis is successful in the majority of cases. Ninety-five percent of patients with this disorder responded to conservative treatment in one study.¹⁴

Key Insights On Surgical Techniques
When one has attempted all conservative measures and the patient has had no relief from pain and irritation at the insertion site of the tendon, and athletic performance has been affected, surgical intervention may be the only viable option to remedy the condition.

After deciding on surgical intervention as the only remaining alternative for intractable retrocalcaneal pain, there are various surgical approaches to consider. The surgical approach for resection of the posterior calcaneal exostosis and/or insertional Achilles calcific tendinosis depends on the site of the pathology, whether it is medial, lateral or on both sides of the calcaneus. With the patient in the prone position, one may utilize a single longitudinal mid-linear incision, a two-incision medial and lateral linear approach, or a curvilinear and mildly oblique incision. When the retrocalcaneal hyperostosis (spurs) are present at the insertion, I advise a midline tendon splitting approach, which allows for adequate exposure to the calcaneus to resect the spur.^8,11

For the spur that is centrally located and for calcification within the tendon and its insertion at the midline, I recommend the “tendon splitting” incision. This approach minimizes underscoring and allows for an equal medial and lateral half of the tendon to remain intact to the calcaneus distally. Then reflect the medial and lateral portions of the tendon, providing adequate exposure of the pathology site and allowing for resection of any intratendinous calcification. In cases in which there is a deeply inflamed retrocalcaneal bursa, paratendinosis and a superior “calcaneal step,” a “deepening split tenotomy” may be necessary. It is imperative to resect an enlarged “calcaneal step” to prevent recurrence.

After resection of the hyperostosis (spur) and the intratendinous calcification, and remodeling of the calcaneus, reattach the medial and lateral halves of the Achilles tendon with an absorbable or non-absorbable bone/tissue anchor with either Mersilene (Ethicon) or FiberWire (Arthrex) non-absorbable suture. The PushLock (Arthrex), SpeedBridge (Arthrex) or other absorbable anchors come preloaded with sutures. To ensure the repair of the tendon, using additional absorbable 2-0 Vicryl can reinforce the anchoring of the tendon to the bone.

Another option is to place an acellular dermal matrix (skin substitute) over the repaired tendon to prevent adhesions and allow for earlier mobilization.

With the advancement of the absorbable tissue anchors for securing the repaired Achilles tendon, the athletic patient can progress postoperatively at a much faster pace. Postoperatively, there are many opinions as to the time period before weightbearing occurs and to what degree the patient should rest the foot/ankle with immobilization, which depends on the patient’s adherence.¹

Prevention of deep venous thrombosis (DVT) is paramount. Preoperative questioning of the patient is important to determine if there has been any prior history of DVT, a familial or inherited disorder of coagulation (i.e. antithrombin III deficiency, prothrombin 20210A), protein C or protein S deficiency, or factor V Leiden. If the patient is significantly overweight, on birth control medication or a smoker, provide preemptive care postoperatively. This consists of a standard dose of aspirin or, in some cases, enoxaparin sodium (Lovenox, Sanofi) 30 mg subcutaneous q 12 h for seven days.

A Guide To Effective Post-Op Care
The first post-op week is the most important. One should first place the patient in a non-weightbearing posterior splint cast with the ankle at a right angle or in slight equinus, allowing him or her to move with the assistance of crutches or a “knee scooter.” In the second week, the patient wears a hard, non-weightbearing lower leg fiberglass cast with a surgical shoe with the ankle held at neutral position, again ambulating with crutch or “knee scooter” assistance. After two weeks, remove the sutures and the patient may either return to a below-knee semi-weightbearing cast or advance to a removable controlled ankle motion (CAM) walker cast boot.

Postoperative rehabilitation depends on the integrity of the reattachment of the Achilles tendon. Physical therapy modalities may begin in the third to fourth week with active/passive range of motion, which is similar to postoperative care of a repaired Achilles tendon. I also recommend deep cross friction massage, icing, topical anti-inflammatory and anti-scar creams to prevent scar tissue formation and facilitate earlier mobilization.
After the reattachment of the Achilles is secure and one has re-established tensile strength at the repaired insertion, the patient can begin eccentric loading exercises. One of the keys to prevent recurrence is paying attention to the equinus of the posterior muscle groups. The physical therapist should work on stretching and flexibility of the gastroc soleus and hamstring muscle groups.

In Conclusion
Thanks to advances in surgical technique and improved soft tissue/bone anchors, the postoperative patient can move forward at a much faster pace than in years past. Earlier mobilization will help reduce scar tissue formation, improve flexibility and reduce the chances for regeneration of insertional spurring. This will help ensure a more successful result.
However, for some athletes, postoperative recuperation and resumption of the preoperative competitive level can take up to a year. It is important with both athletes and non-competitive patients to note that the desired results make take longer than expected. Healing rates may differ from one patient to another. Therefore, one should discuss expectations with the patient preoperatively in order to attain mutual goals.

Dr. Ross is an Associate Clinical Professor of Medicine and Chief of the Diabetic Foot Clinic at Quentin Meese General Hospital in Houston. He is a Fellow of the American College of Foot and Ankle Surgeons, and a Diplomate of the American Board of Podiatric Surgery. Dr. Ross is a Past President of the American Academy of Podiatric Sports Medicine and a Fellow of the American College of Sports Medicine.  

References

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