Background/Objectives: Osteoporosis and osteoarthritis are age-related musculoskeletal disorders with a high socio-health burden, affecting both healthcare systems and individuals’ quality of life. Both conditions are generally accompanied by a concomitant decline in muscle mass and strength, referred to as sarcopenia. In this context, tensiomyography emerges as a novel, non-invasive potential diagnostic strategy for assessing muscle quality, as this parameter influences the progression of both conditions. Methods: Histomorphometric and immunohistochemical analyses were performed on vastus lateralis muscle tissue obtained from patients undergoing surgery for femoral fracture affected by osteoporosis or osteopenia, patients operated for hip osteoarthritis, and patients undergoing hip arthroplasty for osteoarthritis, concomitantly affected by osteoporosis or osteopenia. In addition, muscle function was assessed in these patients using tensiomyographic analysis. Results: In osteoarthritic, osteoporotic, and osteopenic patients, a reduction in muscle quality and function was observed compared with the other two experimental groups, indicating an unfavorable effect of the coexistence of the two conditions on the muscular component. Furthermore, contraction time (Tc) measured by tensiomyography was negatively correlated with lumbar spine bone mineral density values and positively correlated with the percentage of type II muscle fibers. Conclusions: This study highlights how tensiomyography may represent a valuable non-invasive diagnostic strategy for assessing muscle status in osteoporotic and osteoarthritic patients, as it is able to detect muscle alterations that parallel the worsening of bone status and that cannot be inferred from simple biopsy analysis. Thus, tensiomyography could be considered a practical adjunct tool in the clinical assessment of musculoskeletal frailty.