Efficacy of bone marrow-stimulating technique in rotator cuff repair

BACKGROUND: This study used a chronic rotator cuff (RC) tear model to investigate
the effect of microfracture as a bone marrow-stimulating (BMS) technique for RC
healing.
METHODS: A chronic retracted RC tendon tear model was created bilaterally in the
subscapularis tendons of 20 New Zealand rabbits. The tendons were repaired after
8 weeks using a single-row configuration. Tendons in the right shoulder were
repaired in standard fashion (control group). Microfractures were performed in
the left shoulders before repair (microfracture group). The animals were
euthanized 8 and 16 weeks after repair. The repaired tendons were tested
biomechanically for their ultimate failure load, linear stiffness, and elongation
at failure. Gross and histologic evaluations of the tendon-to-bone healing were
evaluated.
RESULTS: Macroscopically, subscapularis tendons were attached on the lesser
tuberosity. In the microfracture group, collagen fibers were organized in
relatively thicker bundles. The mean ultimate failure load of the microfracture
group was significantly greater at 8 weeks (148.4 ± 31 N vs. 101.4 ± 26 N,
respectively; P = .011) and 16 weeks (155 ± 30 N vs. 114.9 ± 25 N, respectively;
P = .017) after repair. There were no significant differences between the groups
for linear stiffness at 8 weeks (15.9 ± 2.7 N/mm vs. 15.8 ± 1.3 N/mm,
respectively; P = .798) and 16 weeks (16.9 ± 4.3 N/mm vs. 17.1 ± 3.6 N/mm,
respectively, P = .848) and elongation at failure at 8 weeks (4.7 ± 1.1 mm vs.
4.7 ± 1.3 mm, respectively; P = .848) and 16 weels (4.8 ± 1.5 mm vs.
4.9 ± 0.9 mm, respectively; P = .749).
CONCLUSION: The microfracture on the tuberosity of the repaired chronic rotator
cuff tear promoted dynamic tendon healing with significantly increased ultimate
force to failure and with thicker collagen bundles and more fibrocartilage
histologically at 8 weeks.