Case-control study. To evaluate clinical and radiological results of transforaminal lumbar interbody fusion (TLIF) performed with cortical bone trajectory (CBT) pedicle screw insertion with those of TLIF using 'conventional' or percutaneous pedicle screw insertion. CBT is a new trajectory for pedicle screw insertion in the lumbar spine; clinical and radiological results of TLIF using pedicle screws inserted with CBT are unclear. In total, 26 patients (11 males, 15 females) were enrolled in this retrospective study and divided into three groups: TLIF with pedicle screw insertion by conventional minimally invasive methods via the Wiltse approach (M-TLIF, n=10), TLIF with percutaneous pedicle screw insertion (P-TLIF, n=6), and TLIF with pedicle screw insertion with CBT (CBT-TLIF, n=10). Surgical results and preand postoperative radiological findings were evaluated and compared. Intraoperative blood loss was significantly less with CBT-TLIF (p=0.03) than with M-TLIF. Postoperative lordotic angles did not differ significantly among the three groups. Complete fusions were obtained in 10 of 12 levels (83%) with M-TLIF, in seven levels (100%) with P-TLIF, and in 10 of 11 levels (91%) with CBT-TLIF. On postoperative computed tomography, correct positioning was seen in 84.1% of M-TLIF screws, 88.5% of P-TLIF screws, and 90% of CBT-TLIF screws. CBT-TLIF resulted in less blood loss and a shorter operative duration than M-TLIF or P-TLIF. Postoperative rates of bone union, maintenance of lordotic angles, and accuracy of pedicle screw positions were similar among the three groups.

Osteoporosis is the result of imbalance in bone remodeling caused by increased bone resorption and decreased bone formation. In terms of the mechanisms for the age-related impairment in bone formation, a deficiency in growth hormone (GH) / insulin-like growth factor (IGF) system that occurs with age has been proposed to play a major role. The potential causes for age-related decline in GH secretion are under active investigation and may involve multiple mechanisms including GH secretagogues, sex hormones, nutritional status and physical activity. Although a number of animal and clinical studies have provided experimental evidence for potential use of GH / IGF system components to increase bone mass, the clinical utility of GH / IGF system components for treatment of osteoporosis has not come to fruition because of our incomplete understanding of the regulation of production and actions of GH / IGF system components. Regarding the actions of GH in target tissues, there is evidence that IGF system plays a major role in mediating the GH effects. In addition, GH may also exert effects on certain target tissues independent of IGFs. It is also known that GH effects on target tissue involve multiple components of the IGF system including the ligands, receptors, IGF binding proteins (IGFBP), IGFBP proteases and activators and inhibitors of IGFBP proteases. Future studies on the mechanisms that contribute to age-related impairment in GH / IGF axis and the molecular pathways that contribute to the bone forming effects of GH / IGF axis may provide a foundation for the development of safe and effective therapies involving one or more IGF system components to correct bone formation deficit in the elderly subjects.

Lumbar kyphosis and the decreased mobility of the lumbar spine increase the risk of falls and impair both the quality of life and the ability to perform activities of daily living. However, in the elderly Japanese population, little is known about the age-related changes and sex-related differences in muscle strength, including of the upper and lower extremities and back extensors. An adequate kyphotic or lordotic angle has also not been determined. In this study, we evaluated the age-related changes in muscle strength and spinal kyphosis in 252 males and 320 females ≥50 years of age. Grip, back extensor, hip flexor, and knee extensor strength; thoracic and lumbar kyphosis; and spinal inclination in the neutral standing position were assessed, together with the range of motion of the thoracic and lumbar spine and spinal inclination. Grip strength, back extensor strength, and the strength of the hip flexors and knee extensors decreased significantly with aging, both in males (P<0.0001) and in females (P=0.0015 to P<0.0001). The lumbar but not the thoracic kyphosis angle decreased significantly with aging, only in females (P<0.0001). Spinal inclination increased significantly with aging in both males (P=0.002) and females (P<0.0001). Back extensor strength and the thoracic kyphosis angle were significant variables influencing the lumbar kyphosis angle in both sexes. Spinal inclination correlated significantly with both the lumbar kyphosis angle and hip flexor strength in males, as well as with the lumbar kyphosis angle in females.