Introduction of a new repair technique in bony avulsion of the FDP tendon: A biomechanical study

Gabriel Halát,Lukas L Negrin,Jochen Erhart,Johannes Streicher,Ewald Unger,Stefan Hajdu,Patrick Platzer,Thomas Koch

doi:10.1038/s41598-018-28250-y

Gabriel Halát, Lukas L Negrin + Show 6 more

Open Access

https://doi.org/10.1038/s41598-018-28250-y

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Abstract

The purpose of this study was to determine the biomechanical characteristics of an innovative surgical technique based on a tension banding principle using a suture anchor in the repair of bony avulsions of the flexor digitorum profundus tendon. After injury simulation in 45 fresh frozen distal phalanges from human cadavers, repair was performed with minifragment screws, interosseous sutures and the innovative technique (15 per group). All repairs were loaded for a total of 500 cycles. Subsequently the specimens were loaded to failure. Load at failure, load at first noteworthy displacement (>2 mm), elongation of the system, gap formation at the avulsion site, and the mechanism of failure were assessed. The new techniques’ superior performance in load at failure (mean: 100.5 N), load at first noteworthy displacement (mean 77.4 N), and gap formation (median 0 mm) was statistically significant, which implies a preferable rigidity of the repair. No implant extrusion or suture rupture during cyclic loading were recorded when the new technique was applied. This innovative repair technique is superior biomechanically to other commonly used surgical tendon reattachment methods, particularly with respect to an early passive mobilisation protocol. Further, due to its subcutaneous position, reduction of complications may be achieved.

Highlights

Surgical approach to a bony avulsion of the flexor digitorum profundus (FDP) tendon is challenging due to a variety of avulsion fragment size, fragment displacement and the scarce soft tissue covering the injury and the repair
No statistically significant difference with respect to the cross-sectional area (CSA) of the FDP tendons was detected between the three study groups
Between the 50th and the 500th cycle, we observed a mean elongation of 0.3 ± 0.2 mm in the new technique group, 0.9 ± 0.4 mm in the interosseous group and 0.4 ± 0.2 mm in the specimens repaired with screws

Summary

Introduction

Surgical approach to a bony avulsion of the flexor digitorum profundus (FDP) tendon is challenging due to a variety of avulsion fragment size, fragment displacement and the scarce soft tissue covering the injury and the repair. When addressing small fragmentary avulsions, a risk of implant cut-out or disintegration of the bony fragment when being drilled and tightened has been observed. This may result in recurrence of the avulsion and/or loss of joint congruity, which contributes to subsequent loss of range of motion (ROM) and posttraumatic arthrosis at the DIP Joint. We expect to avoid a relevant range of reported complications as well as to address small fragmentary bony avulsions. We compared clinically relevant biomechanical parameters of our new technique to minifragment screw repair and interosseous sutures, the two nowadays most frequently used subcutaneous surgical repair techniques for type III FDP tendon avulsions

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