Thermogravimetric analysis of cancellous bone of humerus head in patients undergoing total shoulder arthroplasty

Prior to shoulder replacement, the quality of cancellous bone stock of humerus head should be evaluated. Thermogravimetric analysis (TGA) has already been utilized to assess thermal stability of cancellous bone mineral, collected from the femoral head of patients with osteoarthritis and osteoporosis. Our workgroup has recently examined the thermal parameters of rotator cuff of patients undergoing reversed shoulder replacement. We hypothesized that TGA of humerus head would indicate difference in the bone quality of orthopedic and trauma patients. We also hypothesized that the calorimetric data could correlate with the grade of degenerative changes. Cylindrical subchondral humeral head samples were collected from patients subjected to reversed shoulder replacement due to orthopedic or trauma indications. Then, calorimetric parameters were measured using DTA/TG analysis. Radiological evaluation was also performed to classify the grade of osteoarthritis. In case of orthopedic samples, the calorimetric parameters indicated a moderate to severe degree of bone damage and loss of mineralization, because of the progressed osteoarthritis. Meanwhile, the trauma samples exhibited only moderate or minimal subchondral bone degeneration. DTA curves showed different patterns and indicated shifts in transition temperatures, comparing control and pathologic samples. In addition, correlation was found between the degree of osteoarthritis and calorimetric enthalpy. DTA/TG analysis of humerus head samples indicated marked differences in bone quality of orthopedic and trauma patients. Further investigation is needed to differentiate the calorimetric parameters of different layers of subchondral bone.