Effect of Skeletal Maturity on Fixation Techniques for Tibial Eminence Fractures

Abstract

Background: Several fixation methods have been reported for the operative treatment of tibial eminence fractures. Previous biomechanical studies have demonstrated that suture fixation may be a stronger construct; however, the maturity status of these specimens was not scrutinized. Purpose: To examine if suture fixation remains a biomechanically superior fixation method to screw fixation in both skeletally mature and immature specimens. Study Design: Controlled laboratory study. Methods: Sixteen total matched porcine (Yorkshire) knees (8 skeletally immature knees and 8 skeletally mature knees) were procured, and a standardized tibial eminence fracture was created. In each age-matched group of knees, 4 knees underwent randomization to fixation with 2 screws while 4 knees were randomized to fixation using a dual-suture technique. Once fixation was complete, the specimens underwent cyclic loading (200 cycles) in the anteroposterior plane of the tibia and load-to-failure testing, both with the knee positioned at 30° of flexion. Relevant measurements were recorded, and data were analyzed. Results: Among mature specimens, load to failure was 1.9 times higher in the suture fixation group compared with the screw fixation group (1318.84 ± 305.55 vs 711.66 ± 279.95 N, respectively; P = .03). The load to failure was not significantly different between the groups in immature specimens (suture: 470.00 ± 161.91 N vs screw: 348.79 ± 102.46; P = .08). Conclusion: These findings suggest that suture fixation may represent a better construct choice for fixation of tibial eminence fractures in the skeletally mature population. However, in the skeletally immature population, fixation with screws or suture may be equivalent. Displacement after cyclic loading did not appear to differ by fixation method, nor did stiffness. Clinical Relevance: A stronger fixation construct may be beneficial and allow for earlier range of motion to help potentially decrease postoperative stiffness. Clinical studies are warranted to see if these results may be replicated in humans.

Screws or Sutures? A Pediatric Cadaveric Study of Tibial Spine Fracture Repairs

“…Regarding screw fixations, Ye et al 36 recently conducted a meta-analysis of studies comparing single-screw fixation versus the FiberWire suture fixation described in our study, concluding that suture fixation was superior across the spectrum of biomechanical properties. 6,9,11,20,26,29 Eggers et al 9 and Thome et al, 34 who studied skeletally mature porcine knees, concluded that the ultimate failure load of 2-screw fixation was approximately half that of FiberWire suture fixation. However, Thome et al also reported equivalency between 2-screw and 2-suture fixation in skeletally immature porcine knees, providing the initial motivation for our study.…”

“…These low failure loads seen in pediatric specimens throughout this study have potential implications for postoperative rehabilitation protocols. For example, biomechanical studies in adults have found that in situ forces on the ACL-tibial spine complex can reach up kk References 2,3,6,9,15,20,[27][28][29]34,36. {{ to 303 N during early rehabilitation activities, such as contralateral toe-off during walking. 30 Because no reports of biomechanical forces on the pediatric ACL-tibial spine complex during early rehabilitation are available, we are unable to provide quantitative recommendations about the specific rehabilitation protocols that pediatric patients with TSFs should undergo.…”

“…8,12,32 A recent study in skeletally immature porcine bone found no difference between 2-screw and 2-suture fixation. 34 However, no previous study has evaluated tibial spine fixation in human pediatric tissue, where the disease burden is most densely concentrated. Therefore, there exists a critical need to determine the biomechanical properties of screw and suture TSF fixation methods in pediatric knees compared with adult and porcine knees.…”