Mechanical Study Of Superior Capsular Reconstruction Of Shoulder Joint By Allograft Fascia Lata

Objective(s): To investigate the mechanical feasibility of superior capsular reconstruction by allograft fascia lata,and compare the mechanical properties of grafts in different treatment groups.Methods: According to the standard procedure of Organ Procurement Organizations,bilateral bulk fascia lata tissue were obtained asepticically within 24 hours of donor death and cryogenically preserved.The donors included 5 men and 3women aged 33-42 years.During the experiment,deep-cryogenic fascia lata allografts were taken out and randomly divided into non-irradiation group,15 k Gy dose γirradiation group and 25 k Gy dose γ irradiation group for treatment,with 5 pieces in each group.Then,the conjoint tendon part and iliotibial tract part of fascia lata were made into grafts respectively.All grafts were divided into 4 groups with 5 grafts in each group according to the difference of γ-irradiation and fascia lata location.The specific groups were: non-irradiation conjoint tendon group(group A),15 k Gy irradiation conjoint tendon group(group B),25 k Gy irradiation conjoint tendon group(group C),and non-irradiation iliotibial tract group(group D).The width and thickness of the grafts in each group were measured and the cross-sectional area was calculated.Then the initial length of the grafts was designed to be 20 mm.The ultimate load,maximum stress,elastic modulus and elongation of the grafts at fracture were obtained by tensile fracture test.The differences of graft width,thickness and cross-sectional area among the four groups were compared by single-factor ANOVA analysis.Single sample t-test was used to compare the cross-sectional area,ultimate load and maximum stress of grafts in each group with the existing mechanical test results of supraspinalis tendon.Single-factor ANOVA analysis was used to compare the differences of ultimate load,maximum stress,elastic modulus and elongation of grafts in groups A,B and C.The t-test of two independent samples was used to compare the differences of ultimate load,maximum stress,elastic modulus and elongation of grafts in groups A and D.Results: There were no statistical differences in gender and age composition among the four groups(p > 0.05).There were no significant differences in the width,thickness and cross-sectional area of the grafts among the four groups(p > 0.05).The cross-sectional area of grafts in the four groups was significantly larger than that of supraspinatus tendon(p < 0.01).The ultimate load of grafts in group A and B was significantly higher than that of supraspinatus tendon(p < 0.01),and that in group C was significantly lower than that of supraspinatus tendon(p < 0.05).There was no statistical difference between the ultimate load of grafts in group D and that of supraspinatus tendon(p > 0.05).The maximum stress of grafts in four groups was significantly lower than that of supraspinatus tendon(p < 0.01).There were no statistical differences in the ultimate load,maximum stress,elastic modulus and elongation of grafts in group A and B(p > 0.05).The ultimate load,maximum stress and elongation of grafts in groups A and B were significantly greater than those in group C(P < 0.01).The ultimate load and elastic modulus of grafts in group A were significantly higher than those in group D(P < 0.05),and the maximum stress and elongation of grafts in group A were significantly higher than those in group D(P <0.01).Conclusion(s): The ultimate load of the grafts made by the non-irradiation or15 k Gy irradiation conjoint tendon part of the fascia lata and non-irradiation iliotibial tract part of fascia lata can reach the level of supraspinatus tendon.The grafts made by the non-irradiation or 15 k Gy irradiation conjoint tendon part of the fascia lata had similar mechanical properties,and both were better than those made by 25 k Gy irradiation conjoint tendon part of the fascia lata.The grafts made by the non-irradiated conjoint tendon part of the fascia lata had better mechanical properties than those made by the non-irradiated iliotibial tract part of fascia lata.