A Transosseous Suture as an Alternative to Suture Anchor on Anterior-Avulsion Greater Tuberosity Fragment Fixation in Neer Three-Part Proximal Humeral Fracture: A Biomechanical Study

Objective

Greater tuberosity (GT) fragments were communicated, and additional techniques to increase the GT fragment stability after the locking plate fixation was necessary. This study aimed to analyze the reinforcement effects on the anterior-avulsion GT fragment in Neer three-part proximal humeral fractures (PHFs) using transosseous suture and suture anchor techniques.

Methods

Eighteen fresh-frozen human cadaveric shoulder specimens were used in the study. Standardized fracture of the GT and surgical neck was created in 18 human cadaveric proximal humerus. The GT fragments were reinforced with transosseous suture (TS), suture anchor (SA), and suture in addition to the PHILOS plate fixation. The fixed humerus was tested by applying static loading to the supraspinatus tendon. Load forces and fragment displacement were evaluated by a biomechanical testing machine, and the load to 3- and 5-mm displacements, load to failure, and mode of failure were recorded for all specimens. Nonparametric variables were examined by the Kruskal–Wallis test, and the Bonferroni post hoc test was used to analyze the mean loads to create 3- and 5-mm displacements as well as the failure load.

Results

The age, female proportion, and bone mineral density showed no statistically significant differences between the three groups. The mean loading force to create 3-mm and 5-mm displacement in the TS group (254.9 ± 77.4, 309.6 ± 152.7) were significantly higher than those in the suture group (136.1 ± 16.7, 193.4 ± 14.5) (P = 0.024, P = 0.005). For the SA group, the force to create 3- and 5-mm displacement (204.3 ± 60.9, 307.8 ± 73.5) were comparable to those in the TS group (P = 0.236, P = 0.983). Moreover, the loading force to failure in the TS group (508.6 ± 217.7) and SA group (406.6 ± 114.9) was significantly higher than that in the suture group (265.9 ± 52.1) (P = 0.021, P = 0.024). In the TS group, three failed due to tendon-bone junction rupture; bone tunnel broken occurred in two specimens; suture rupture could also be seen in one specimen. All specimens in the suture group failed because of suture rupture. In the SA group, three specimens failed due to suture rupture; two failed secondary to tendon-bone junction rupture; and one failed because of shaft fracture.

Conclusions

Transosseous suture is a new type of reinforcement for GT fragment in Neer-three part PHFs. The transosseous suture was superior to the suture only in the reinforcement of the anterior-avulsion GT fragment of Neer three-part PHFs, and it had comparable biomechanical strength to the suture anchor.