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]. Fractures of Types I and III are difficult to fix rigidly because they have small fragments. Various operative techniques using screws, Kirschner wires (K-wires), Steinmann pins, suture anchors, or tension band wiring have been described [
]. However, these techniques are unable to resist the force of the Achilles tendon or require a bulky construct, which may lead to soft tissue complications. On the other hand, Banerjee et al. describe a technique using a suture passed through bone tunnels in the calcaneal tuberosity [
]. We applied this technique to rigidly fix a Type I calcaneal tuberosity fracture. Here, we report our case of avulsion fracture of the calcaneal tuberosity treated using the SLLS technique.
2. Case report
A 64-year-old man fell when riding his bicycle. He had severe pain in his heel and visited an orthopedic medical practitioner. He was referred to our hospital with a diagnosis of fracture of the calcaneal tuberosity 1 week after the accident. Physical examination revealed swelling and tenderness at the left heel and medial malleolus. Plantar flexion range of motion (ROM) was limited to 20° because of sharp pain. There was no sensory or circulatory disturbance. There was subcutaneous bleeding around the heel without skin necrosis. Plane radiographs of the left ankle showed a completely detached avulsion fracture of the calcaneus and a fracture of the medial malleolus (Fig. 1A,B). Computed tomography showed that a small shell of cortical bone had avulsed from the tuberosity. Based on these findings, we confirmed a Type I calcaneal tuberosity fracture according to the Beavis classification, and performed surgery 10 days after the injury.
Surgery was conducted under general anesthesia in the prone position. The fractured calcaneal tuberosity was approached through a posterior midline incision over the Achilles tendon. The Achilles tendon was avulsed from the calcaneus with small fragments that were displaced about 20 mm proximally. There was also fibrous tissue and an abnormal callus. First, the fragments were excised using a curette, and adhesion around the Achilles tendon was released manipulatively. We then culled some fragments found unexpectedly where the bone fuses to the calcaneus. Next, the Achilles tendon was sutured using the SLLS technique with a United States Pharmacopeial Convention (USP) size 5 braided polyethylene and polyester suture thread (FiberWire; Arthrex Co., Naples, FL, USA). A dual suture thread was used; the suture started from the stump and captured the tendon 3 cm from the stump according to the modified SLLS technique (Fig. 2A) [
]. Two passing pins were passed through the fracture site to the plantar site of the calcaneus. The pins were set parallel to each other and perpendicular to the axis of the calcaneus, and they penetrated to the plantar arch. Using these passing pins, two dual-suture threads were pulled from the fracture side to the plantar side of the calcaneus (Fig. 2B). A small incision was made on the plantar posterior third of the foot. The suture threads were exposed under the plantar fascia and were tied using an anti-slip knot (Fig. 2C) [
]. In addition, a peripheral suture was tied around the fracture site to reinforce it, using USP 4-0 nylon (Fig. 2D). The medial malleolus fracture was fixed rigidly using tension band wiring.
Postoperatively, the patient's lower extremity was put in a splint that extended from approximately one-third distal to the fibular head to the forefoot, with the ankle in a plantar flexion of 20°. Two weeks after surgery, active ROM exercise was permitted. Four weeks after surgery, the patient was able to dorsiflex about 5° and partial weight-bearing was started. Full weight-bearing was permitted at 6 weeks after surgery. Half a year after surgery, radiographs showed complete bone union (Fig. 3). Two years after surgery, the patient has no symptoms and he has achieved 100 points on the Japanese Society for Surgery of the Foot (JSSF) ankle/hindfoot scale [
The present study is a retrospective case report. Informed consent was obtained from the patient preoperatively. This study was approved by the Institutional Committee on Ethics of the Shimane University Faculty of Medicine.
The forces generated by the Achilles tendon during normal walking have been estimated to be between 1962 and 2354 N [
]. Therefore, the method of fixation for calcaneal tuberosity fractures must be able to resist this amount of force. When the fragments is small (Beavis classification Type I or III), fixation is particularly difficult.
A wide variety of surgical techniques for calcaneal tuberosity fractures have been proposed. Lag screw fixation has been advocated as a means of maintaining reduction [
]. However, the use of suture anchors alone is also likely to be insufficient. Tension band constructs for the fixation of displaced calcaneal tuberosity fractures have been suggested as a method of ensuring stabilization of the fragment and resisting the force of the Achilles tendon [
]. A figure-8 tension band wire is passed around the ends of the K-wire over the lateral wall of the calcaneus. Although the tension band acts to neutralize the force of the Achilles tendon, this requires a bulky construct on the posterior or lateral aspect of the calcaneus, which may lead to soft tissue complications and/or peroneal tendon irritation.
Banerjee et al. describe a technique in which sutures are passed through the tuberosity fragment and Achilles tendon using a modified Krackow suture [
]. These sutures are then passed through bone tunnels drilled in the body of the calcaneus and tied through a small incision on the plantar aspect of the heel. This technique is advantageous in that it can be used independently for smaller fracture fragments. However, there is no definitive evidence regarding whether it is able to resist the force of the Achilles tendon during early rehabilitation.
To start early postoperative rehabilitation safely, we applied the SLLS technique, which provides higher antigap strength than the Krakow suture technique [
]. In the present case, the strength of fixation was calculated at roughly 1500 N because we used a dual-suture thread; i.e., 4 strands. The tensile strength of an Achilles tendon during bicycle riding has been reported to be 489–661 N [
]. Therefore, we believed that this technique would provide sufficient strength for the patient to perform early ROM exercise and gentle weight-bearing. Additionally, the polyethylene and polyester suture threads have high tensile strength, but require many throws to tie a secure knot because they are inherently slippery [
]. A large knot on the sole would probably cause persistent pain while walking after surgery. To reduce this problem as much as possible, we used an anti-slip knot, which is smaller but has similar or even greater strength than a conventional reef knot.
Scar formation on the sole may be a problem because this technique requires a skin incision on the sole, and even a small knot may cause persistent pain in the sole due to irritation of the plantar fascia. Due to these potential complications, it is essential to obtain informed consent before surgery and careful observation is required after surgery.
Given the encouraging results of the present case, we believe that pullout fixation with SLLS and the anti-slip technique should be considered when treating avulsion fractures of the calcaneal tuberosity.
Conflict of interest
The authors declare that they have no conflict of interest.
Avulsion fracture of the calcaneal tuberosity: a case report and literature review.