Avulsion fracture of the posterosuperior tuberosity of the calcaneus managed with lag screw fixation

A Biomechanical Study of Calcaneal Tuberosity Avulsion Fracture: A Comparison Between Three-Screw Versus Two-Screw Fixation Strength

A calcaneal tuberosity avulsion fracture constitutes a sub-group of calcaneal fractures and it poses a high risk of soft tissue compromise, necessitating urgent reduction and fixation. This fracture was commonly treated with screw fixation, and fixation failure associated with this method has been reported in the literature. In light of this, we tested and compared the strength of two-screw (2S) versus three-screw (3S) fixations, where the third screw was fixed from the posterior calcaneal tuberosity towards the anterior process in addition to the two parallel screws. Synthetic calcaneum models were tested with an Instron machine to measure the maximum tensile load and stiffness. The mean maximum tensile loads for 3S and 2S were 455.8 N (SD = 47.4) and 341.0 N (SD = 30.9), respectively, and the difference was statistically significant. The mean stiffnesses for 3S and 2S were 29.2 N/mm (SD = 1.8) and 29.7 N/mm (SD = 2.0), but this difference did not reach statistical significance. Based on our findings, the added third screw increased the pull-out strength and can be inserted percutaneously to minimize soft tissue compromise.

Calcaneal tuberosity avulsion fractures - A review

Calcaneal tuberosity avulsion fracture, an extra-articular injury, is a rare fracture caused internally by Achilles tendon driven following intense contraction of gastrocnemius-soleus complex, and externally by low-energy (possibly high-energy). Moreover, the risk of injuries of the skin and Achilles tendon around calcaneal tuberosity is closely related to Lee classification and Carnero-Martín de Soto Classification of calcaneal tuberosity avulsion fracture. Although the diagnosis confirmed by X-ray, digital imaging and computed tomography (CT), magnetic resonance imaging (MRI) should also be used to evaluate soft tissue. In recent years, the understanding of this fracture has witnessed the development of different internal fixation devices and surgical procedures. These advances have been further elaborated scientifically in terms of their ability to provide stable fracture reduction ad resistance to Achilles tendon forces. In order to obtain a comprehensive knowledge of the disease, this article reviewed the new understanding of the anatomy, typing, risk factors, and treatment modalities of calcaneal tuberosity avulsion fracture in recent years.

Thickness of simple calcaneal tuberosity avulsion fractures influences the optimal fixation method employed

Aims

This study aimed to establish the optimal fixation methods for calcaneal tuberosity avulsion fractures with different fragment thicknesses in a porcine model.

Methods

A total of 36 porcine calcanea were sawed to create simple avulsion fractures with three different fragment thicknesses (5, 10, and 15 mm). They were randomly fixed with either two suture anchors or one headless screw. Load-to-failure and cyclic loading tension tests were performed for the biomechanical analysis.

Results

This biomechanical study predicts that headless screw fixation is a better option if fragment thickness is over 15 mm in terms of the comparable peak failure load to suture anchor fixation (headless screw: 432.55 N (SD 62.25); suture anchor: 446.58 N (SD 84.97)), and less fracture fragment displacement after cyclic loading (headless screw: 3.94 N (SD 1.76); suture anchor: 8.68 N (SD 1.84)). Given that the fragment thickness is less than 10 mm, suture anchor fixation is a safer option.

Conclusion

Fracture fragment thickness helps in making the decision of either using headless screw or suture anchor fixation in treating calcaneal tuberosity avulsion fracture, based on the regression models of our study.

Outcomes of U-shaped internal fixation in the treatment of avulsion fracture of calcaneal tubercle

BACKGROUND

The purpose of this study was to analyze the efficacy of U-shaped internal fixation for calcaneal tubercle fracture after nearly 3 years of case follow-up and data collection.

METHOD

We retrospectively analyzed the collected data from 16 patients with avulsion fracture of calcaneal tubercle between December 2018 and February 2021 at our institute. All patients were required to conform to regular follow up postoperatively. X-ray film was applied to all cases. The American Orthopaedic Foot and Ankle Association (AOFAS) score, Cedell score and the visual analog scale (VAS) were used to evaluate functional results.

RESULTS

All patients achieved bone union. The preoperative AOFAS score was 26.34 ± 3.34, which was significantly different from 91.38 ± 6.15 half a year after operation (p = 0.003). The preoperative Cedell score was 31.05 ± 4.18 and the score half a year after operation was 92.17 ± 5.39(p = 0.011). The VAS score was 8.91 ± 1.51 before operation and decreased to 0.58 ± 1.31 half a year after operation (p = 0.014).

CONCLUSIONS

In the treatments of calcaneal tubercle fracture, U-shaped internal fixation is a new attempt. Through the short-term follow-up study, we found that its therapeutic effect is excellent, which is a recommended treatment in clinic.

Avulsion fracture of the calcaneal tuberosity treated with novel surgical technique using the combination of the side-locking loop suture technique and ring pins: a case report

A 78-year-old woman complained of right heel pain when tripping during walking. Radiographs revealed an avulsion fracture of the calcaneal tuberosity. Because the bone fragment was displaced, a novel osteosynthesis using the side-locking loop suture (SLLS) and ring pins was performed. At 3 months after the surgery, non-contrast computed tomography revealed complete bone union. At 2 years postoperatively, she had no symptoms and dysfunctions. Here, we describe a case of avulsion fracture of the calcaneal tuberosity in a 79-year-old female who treated with a novel surgical technique using combination the SLLS technique and ring pins. This surgical technique may be a useful option in the treatment for avulsion fractures of the calcaneal tuberosity.

Biomechanical Comparison of a Novel 3-Screw Fixation vs Conventional 2-Screw Fixation of Calcaneal Tuberosity Avulsion Fractures

BACKGROUND

Calcaneal tuberosity avulsion fractures are challenging to treat because of the poor bone stock and high risk of fixation failure secondary to the strong Achilles tendon pull. The purpose of this study is to compare the tensile force to failure of 2 different types of screw fixation construct in a cadaveric model of calcaneal tuberosity avulsion fracture.

METHODS

An oblique osteotomy was created in the calcanei of 7 matched pairs of cadaveric specimens to simulate a tuberosity avulsion fracture and one specimen from each pair randomized into one of the 2 groups for comparison. Two cancellous screws were inserted perpendicular to the fracture line at the posteromedial and posterolateral corners of the avulsed fragment for the 2-screw construct. For the second group, an additional stab incision was made at the midline of the Achilles insertional region for a screw placed between the initial 2 screws with a trajectory toward the calcaneocuboid joint in the 3-screw construct. These specimens were then mounted and loaded to failure.

RESULTS

The mean force to a predefined failure at 3.0-mm gap for the 3-screw construct was 468.7 ± 267.9 N vs 278.9 ± 164.0 N for the 2-screw construct (P < .001). The addition of a central nonparallel screw in the 3-screw construct significantly increased the force required for fracture gap displacement at all cut-off points (1.0-8.0 mm) when compared to the 2-screw construct (P < .001). Notably, the mean peak tensile force for the 3-screw construct was 499.4 ± 255.4 N occurred at the gap displacement of 4.1 mm for the 3-screw construct whereas the mean peak tensile force for the 2-screw construct was 315.9 ± 162.4 N displacing the gap at 4.3 mm.

CONCLUSION

This study showed that an additional central nonparallel screw in the 3-screw construct provided significant mechanical superiority compared to a 2-screw construct.

CLINICAL RELEVANCE

The present study supported the use of augmented fixation with an additional central off-axis screw to reduce risk of fixation failure in calcaneal tuberosity avulsion fractures.

Outcomes of operatively treated calcaneal tuberosity avulsion fractures

BACKGROUND

Calcaneal tuberosity avulsion fractures are uncommon but when present should be treated emergently due to the high risk of skin compromise. Multiple fixation techniques have been reported in the literature but there are little data regarding the ideal fixation construct and outcomes. We aimed to characterize the clinical presentation, focussing on soft tissue compromise and outcomes of operatively treated calcaneal tuberosity avulsion fractures with its associated complications.

METHODS

A retrospective review of all surgically treated calcaneus fracture in our institution from Jun 2008 to Jun 2017 was done. We reviewed patients' demographics, types of avulsion fracture, presence of preoperative skin compromise, age of fracture, time to operation, types of fixation construct, postoperative weight bearing regime, union rates, complications and revision surgeries if present.

RESULTS

We found 9 patients from our database who met the inclusion criteria. They had an average age of 55.6 (range: 43 - 90) years with 5 (55.6%) of them aged 60 years and older. Seven (77.8%) patients were female. Four out of 9 patients (44.4%) presented with soft tissue compromise (3 cases of skin tenting and 1 case of blistering). None of them required soft tissue reconstructive surgery for skin defects postoperatively. However, 2 patients (22.2%) had wound complications after surgery requiring prolonged wound care for up to 4 months. There were 2 patients with fixation failure whereby both were allowed weight bearing prematurely. All of them were able to ambulate independently at their last review.

CONCLUSION

Calcaneal tuberosity avulsion fractures have a high prevalence of soft tissue compromise and warrant early attention. This condition should be treated as both a bony and soft tissue injury rather than just a bony fracture alone. Management of this injury should take into account fracture reduction and stable fixation with neutralization of the Achilles tendon forces.

An Alternative Technique for Fixation of Tongue-Type Calcaneal Fractures: The "Hurricane Strap"

Traditionally, tongue-type calcaneal fractures have been treated using screw fixation or tension band wiring. In this work, we aim to present a technique guide for an alternative approach to fixation of these fractures given the high potential for failure with traditional methods. Additionally, we present the results of 4 patients treated with this technique. A modified lateral extensile incision is made for application of a midfoot fusion plate that is pre-bent and fit to the calcaneus with 2 holes covering the superior surface of the calcaneus for bicortical interfragmentary purchase. Four screws are then placed orthogonally into the calcaneus through the plate. Typically, this allows for 2 screws to be placed in the superior fragment and 2 screws to be placed in the inferior fragment. All 4 patients went on to timely osseous union and were weightbearing in regular shoe gear at their last follow-up appointment. Average follow-up time was 16.5 (range 15 to 21) months. We believe that the "hurricane strap" provides a more mechanically sound construct than other methods. This construct may be especially useful in patients with osteoporotic bone where screws alone may not maintain adequate reduction or in neuropathic patients where noncompliance with weightbearing status may jeopardize maintenance of reduction.