Trabecular microstructure and surface changes in the greater tuberosity in rotator cuff tears

Objective: When planning surgery in patients with rotator cuff tear, strength of bone at the tendon insertion and trabecular bone struc- ture in the greater tuberosity are usu- ally taken into consideration. We in- vestigated radiographic changes in bone structure of the greater tuberosi- ty in rotator cuff tears. Design: Twen- ty-two human cadaveric shoulders from subjects ranging from 55 to 75 years of age were obtained. The integrity of the rotator cuff was ex- amined by sonography to determine if it is intact without any tear, or torn partially or completely. The humeral head was sectioned in 3 mm thick co- ronal slab sections and microradio- graphed. After digitization of the mi- croradiographs and imaging process- ing with in-house semi-automated image processing software tools de- veloped using software interfaces on a Sun workstation, the trabecular histomorphometrical structural pa- rameters and connectivity in the greater tuberosity were quantified. The degenerative changes on the sur- face of the greater tuberosity were in- terpreted blindly by 2 independent readers. Results: Among the 22 shoulder specimens, the rotator cuff was found intact in 10 shoulders, par- tially in 7 and fully torn in 5. Statisti- cally significant loss in apparent tra- becular bone volume fraction, num- ber of trabecular nodes, and number of trabecular branches, and a statisti- cally significant increase in apparent trabecular separation and number of trabecular free ends were found in the greater tuberosity of the shoul- ders with tears. The loss was greater in association with full tear than in partial tear. Thickening of the cortical margin of the enthesis, irregularity of its surface, and calcification beyond the tidemark were observed in 2 (20%) shoulders with intact rotator cuff, in 6 (86%) shoulders with par- tial tear, and in 5 (100%) shoulders with full tear. Conclusions: Rotator cuff tears are associated with degen- erative changes on the bone surface and with disuse osteopenia of the greater tuberosity. Aging, degenera- tive enthesopathy of the supraspina- tus tendon, and rotator cuff tears ap- pear closely related.