Anthony Watson
DEFINITION
Calcific Achilles tendinopathy is the most common cause of posterior heel pain.
Intratendinous degeneration results in ectopic calcification and ossification at the Achilles tendon insertion to the calcaneus.
ANATOMY
The Achilles tendon inserts over the inferior half of the posterior calcaneal tuberosity (FIG 1).
The insertion expands over the tuberosity to become the calcaneal periosteum.
The inferior half of the posterior calcaneal tuberosity has a rough surface with an extensive Sharpey fiber network.
The superior half of the posterior calcaneal tuberosity has a smooth, almost articular surface.
The retrocalcaneal bursa occupies the interval between the Achilles tendon and the superior half of the posterior calcaneal tuberosity. The bursa also extends superiorly over the posterosuperior process of the calcaneus.
The ossification–calcification typically develops at the insertion, extends proximally into the tendon, and may comprise several segments within the more proximal tendon.
PATHOGENESIS
The pathogenesis is not well understood.
Two patient groups are typically affected: athletically active individuals in their 30s and 40s and overweight women in their 50s and 60s.
Biochemical and histologic findings include:
Degenerative changes2
An anaerobic environment1
Longitudinal tears of the Achilles tendon2,5
Chondral metaplasia and endochondral ossification without insertional fibers from the tendon3,5
NATURAL HISTORY
Symptoms compromise the patient's ability to wear shoes with a heel counter and participate in activity ranging from walking to intense athletic activity.
Symptoms may improve in at least 50% of cases with activity modification, physical therapy, or shoe modifications.6
Disabling symptoms that do not improve with nonoperative treatment may benefit from surgery.
Achilles tendon rupture in the presence of insertional calcification is extremely rare, even without any form of treatment.
PATIENT HISTORY AND PHYSICAL FINDINGS
The typical patient complaint is posterior heel pain aggravated by activity or shoe wear.
Symptoms develop insidiously over time.
Inflammatory enthesopathies such as psoriasis, Reiter syndrome, and inflammatory bowel disease may be present.
Tenderness localized to the Achilles insertion on palpation (the examiner should press directly posteriorly on the heel where the Achilles tendon inserts) confirms the diagnosis.
Tenderness may also be present in the Achilles tendon itself or over the retrocalcaneal bursa. The examiner should lightly squeeze the tendon between the index finger and thumb; squeezing hard on the tendon can result in a falsepositive result. A thickened or painful tendon will require MRI to determine whether tendon transfer reconstruction is necessary.
Peritendinous swelling is rare, but increased caliber of the Achilles tendon may be present.
Weakness is rare, but Achilles tendon contracture is common.
Achilles tightness should be addressed with stretching before considering nonoperative treatment a failure.
Pain with resisted plantarflexion suggests more extensive tendinosis.
FIG 1 • Anatomy of insertional calcification of the Achilles tendon. Note expansion of Achilles tendon fibers over posterior calcaneal tuberosity and intratendinous location of calcification.
FIG 2 • Lateral radiograph of heel with insertional calcification of the Achilles tendon.
Pain with maximum passive plantarflexion suggests inflammation of the paratenon.
Palpation of the retrocalcaneal bursa will differentiate retrocalcaneal bursitis from insertional tendinosis because a tender retrocalcaneal bursa may benefit from bursectomy.
Pain with toe walking supports the diagnosis. Inability to do either suggests the need for rehabilitation before considering surgery.
The surgeon must accurately assess the neurovascular status of the foot and the presence and appearance of any previous incisional scars.
IMAGING AND OTHER DIAGNOSTIC STUDIES
Lateral radiograph of heel (FIG 2)
The examiner should identify insertional ossification, characterize the size of the posterosuperior process of the calcaneus, and identify intratendinous calcification more proximally.
Parallel pitch lines and the Fowler angle provide no diagnostic, therapeutic, or prognostic information.
MRI is indicated when the tendon is thickened, tender, or calcified to determine whether greater than 50% of the crosssectional area of the tendon is involved (FIG 3).
DIFFERENTIAL DIAGNOSIS
Retrocalcaneal bursitis
Calcaneal stress fracture
Plantar fasciitis
Calcaneal periostitis
Achilles tendinosis without insertional calcification
NONOPERATIVE MANAGEMENT
Nonoperative management is helpful in at least 50% of cases.
Initial treatment is with a removable walker boot with removable wedges.
Two or three wedges are used for 2 weeks, and then a wedge is removed every 2 weeks.
Use of the boot is continued for 2 weeks after removal of the last wedge.
Weight bearing as tolerated is permitted in the boot.
Physical therapy is started upon completion of removable walker boot immobilization and should include eccentric closed-chain strengthening exercises.6
Corticosteroid injection is contraindicated.
SURGICAL MANAGEMENT
Surgical treatment is indicated for disabling symptoms that do not improve with thorough nonoperative treatment.
Patients should be counseled that recovery can be a lengthy and sometimes frustrating process, as it is often 12 to 18 months before maximum improvement occurs, especially in nonathletic patients.4,7
Recurrent prominence occurs in 50% of cases but is rarely symptomatic.7
Preoperative Planning
It may be helpful to have patients undergo crutch training preoperatively.
A flexor hallucis longus tendon transfer reconstruction of the Achilles tendon will be necessary if an MRI demonstrates that greater than 50% of the cross-sectional area of the Achilles tendon is involved with degenerative tendinosis.
Positioning
The lateral or prone position is necessary. The heel is more accessible in older or heavier patients when positioned prone. Anesthesia concerns may require lateral positioning.
Approach
Lateral, medial, posterior, and combined approaches have all been described. The lateral approach will be described here.
Advantages of the lateral approach are:
Direct exposure of the insertional calcification
Less compromise of the Achilles insertion expansion than other approaches because the strongest insertion is medial
The scar is less likely to be irritated by shoes, as with the posterior approach.
FIG 3 • Axial T1-weighted MRI showing intratendinous degeneration comprising greater than 50% of the cross-sectional area of the Achilles tendon (white arrow).
TECHNIQUES
RETROCALCANEAL DECOMPRESSION BY LATERAL APPROACH
After administration of anesthesia, position the patient lateral decubitus or prone.
Apply a thigh tourniquet.
Prepare and drape the leg, exsanguinate the leg, and inflate the tourniquet.
Make a longitudinal incision along the lateral heel anterior to the anterior margin of the Achilles tendon. The incision should extend distally to nearly the plantar surface and proximally superior to the retrocalcaneal bursa (TECH FIG 1).
Carefully perform sharp dissection to create full-thickness flaps, taking care to identify and protect any branches of the sural nerve.
TECH FIG 1 • Location of incision.
Make a longitudinal periosteal incision and extend it proximally through the retrocalcaneal bursa, and excise the retrocalcaneal bursa.
Elevate the periosteum anteriorly, then elevate it posteriorly.
Continue sharp elevation of the calcaneal periosteum and Achilles tendon insertion expansion medially along the posterior calcaneal tuberosity all the way to the medial aspect of the tuberosity.
Subperiosteal exposure of the insertional ossification requires careful dissection to preserve the Achilles sleeve.
Resect any degenerative tendinosis of the Achilles tendon. If preoperative MRI showed tendinosis affecting greater than 50% of the cross-sectional area of the Achilles tendon, a flexor hallucis longus tendon transfer, described elsewhere, will be necessary.
Resect the posterior calcaneus along a line from inferior to the insertional ossification to anterior to the posterosuperior process of the calcaneus using a saw or osteotome (TECH FIG 2).
Round over the sharp edges medially and laterally with a rasp or rongeur.
Place two suture anchors in the cancellous bone left after ostectomy and repair the Achilles tendon to the calcaneus (TECH FIG 3).
Repair the periosteum laterally.
Close the incision.
Apply a sterile dressing and plaster posterior mold splint with the ankle in resting plantarflexion.
TECH FIG 2 • Location of ostectomy to include the posterosuperior process of the calcaneus and the insertional calcification.
TECH FIG 3 • Location of suture anchors and repair of Achilles tendon to ostectomy surface of calcaneus.
POSTOPERATIVE CARE
Non–weight-bearing is continued for 4 weeks postoperatively.
Two weeks after surgery, the postoperative splint is changed to a removable walker boot with an Achilles wedge like that used for nonoperative care.
The removable walker boot is continued for 6 weeks, for a total of 8 weeks of immobilization.
Active, nonresistive ankle and hindfoot range-of-motion exercises are begun once the incision has healed.
Physical therapy begins 8 weeks after surgery.
OUTCOMES
Fifty to 85% of patients report good or excellent results 2 years after surgery.4,7
The percentage of good or excellent results is higher in athletic than nonathletic patients.4
Radiographically recurrent insertional calcification occurs in 50% of patients, but symptoms do not always recur with radiographic recurrence.7
Some patients have recurrent symptoms without radiographic recurrence.7
Maximum symptomatic relief may not occur until 12 to 18 months after surgery.
A 1to 2-month period of temporary symptomatic recurrence often occurs 7 to 10 months after the surgery.7
COMPLICATIONS
Superficial or deep infection is especially common in diabetic and overweight patients.
Delayed wound healing is also especially common in diabetic and overweight patients.
Paresthesias and hypoesthesias can be avoided by identifying and protecting the sural nerve and its calcaneal branch.
Achilles avulsion
Deep venous thrombosis
Recurrence
REFERENCES
1. Alfredson H, Bjur D, Thorsen K, et al. High intratendinous lactate levels in painful chronic Achilles tendinosis: an investigation using microdialysis technique. J Orthop Res 2002;20:934–938.
2. Astrom M, Rausing A. Chronic Achilles tendinopathy: a survey of surgical and histopathologic findings. Clin Orthop Relat Res 1995; 316:151–164.
3. Maffulli N, Reaper J, Ewen SW, et al. Chondral metaplasia in calcific insertional tendinopathy of the Achilles tendon. Clin J Sports Med 2006;16:329–334.
4. Maffulli N, Testa V, Capasso G, et al. Surgery for chronic Achilles tendinopathy yields worse results in nonathletic patients. Clin J Sports Med 2006;16:123–128.
5. Rufai A, Ralphs JR, Benjamin M. Structure and histopathology of the insertional region of the human Achilles tendon. J Orthop Res 1995; 13:585–593.
6. Shalabi A, Kristoffersen-Wilberg M, Svensson L, et al. Eccentric training of the gastrocnemius-soleus complex in chronic Achilles tendinopathy results in decreased tendon volume and intratendinous signal as evaluated by MRI. Am J Sports Med 2004;32: 1286–1296.
7. 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 2000; 21:638–642.