Proximal and mid-thigh fascia lata graft constructs used for arthroscopic superior capsule reconstruction show equivalent biomechanical properties: an in vitro human cadaver study

BACKGROUND: The proximal fascia lata (FL) graft construct used for arthroscopic superior capsule reconstruction (ASCR) is openly harvested, whereas the mid-thigh FL graft construct is minimally invasively harvested. The purpose of the current study was to compare the biomechanical properties of proximal thigh and mid-thigh-harvested FL graft constructs used for ASCR. The hypothesis was that, despite the different morphological characteristics of the proximal thigh and mid-thigh FL graft constructs used for ASCR, their biomechanical properties would not significantly differ. This information may assist orthopedic surgeons in the choice of the harvest location, technique, and type of graft construct for ASCR. METHODS: Forty FL specimens, 20 proximal thigh and 20 mid-thigh, were harvested from the lateral thighs of 10 fresh human cadavers (6 male, 4 female; average age, 58.60 ± 17.20 years). The thickness of each 2-layered proximal thigh and 6-layered mid-thigh FL graft construct was measured. Each construct was mechanically tested in the longitudinal direction, and the stiffness and Young’s modulus were computed. Data were compared by Welch’s independent t-test and analysis of variance, and statistical significance was set at P < .05. RESULTS: The average thickness of the proximal thigh FL graft construct (7.17 ± 1.97 mm) was significantly higher than that of the mid-thigh (5.54 ± 1.37 mm) [F (1,32) = 7.333, P = .011]. The average Young’s modulus of the proximal thigh and mid-thigh graft constructs was 32.85 ± 19.54 MPa (range, 7.94 – 75.14 MPa; 95% confidence interval [CI], 23.71 – 42.99) and 44.02 ± 31.29 MPa (range, 12.53 –120.33 MPa; 95% CI, 29.38 – 58.66), respectively. The average stiffness of the proximal thigh and mid-thigh graft constructs was 488.96 ± 267.80 N/mm (range, 152.96 – 1086.49 N/mm; 95% CI, 363.63 – 614.30) and 562.39 ± 294.76 N/mm (range, 77.46 – 1229.68 N/mm; 95% CI, 424.44 – 700.34), respectively. There was no significant difference in the average Young’s modulus or stiffness between the proximal thigh and mid-thigh graft constructs (P = .185 and P = .415, respectively). CONCLUSION: Despite the different morphological characteristics of the proximal thigh and mid-thigh FL graft constructs used for ASCR, their Young’s modulus and stiffness did not significantly differ.