Purpose: To conduct a more comprehensive study of sagittal alignment in patients with thoracolumbar/lumbar (TL/L) degenerative kyphosis. Methods: A total of 133 consecutive patients from September 2016 to March 2019 with degenerative spinal kyphosis were enrolled. These patients were divided into different types according to sagittal alignment, including thoracolumbar junctional kyphosis (TLJK). Then, we divided the patients with TLJK into two groups: the Sagittal Balance group (C7-SVA < 50 mm) and the Sagittal Imbalance group (C7-SVA ≥ 50 mm). The sagittal parameters of each type or group were compared and correlation analysis was conducted. Results: Thoracolumbar/lumbar degenerative kyphosis consists of four types: Type I, lumbar kyphosis; Type II, degenerative flat back; Type III, thoracolumbar junctional kyphosis; and Type IV, global kyphosis. According to different sagittal alignments, Type III can further be divided into three subtypes: IIIA, with smooth kyphosis of thoracic and upper lumbar; IIIB, like a clasp knife, with a flat thoracic and lumbar angle; and IIIC, with bigger thoracic kyphosis and lumbar lordosis. The thoracolumbar kyphosis angle (°) of the three subtypes were −23.61 ± 5.37, −25.40 ± 7.71, and −40.01 ± 8.40, respectively. Lumbar lordosis was correlated with thoracic kyphosis (IIIA, r = −0.600, p = 0.005; IIIB, r = −0.312, p = 0.046; IIIC, r = −0.657, p = 0.015), and correlated with sacral slope (IIIA, r = 0.537, p = 0.015; IIIB, r = 0.654, p = 0.000; IIIC, r = 0.578, p = 0.039). All spinopelvic parameters were compared between the Sagittal Balance group and the Sagittal Imbalance group, and only the thoracolumbar kyphosis angle showed statistical difference (t = −2.247, p = 0.028). Conclusions: The common characteristics of thoracolumbar junctional kyphosis were found to be a bigger thoracolumbar junctional angle and vertex of kyphosis located in the thoracolumbar junction (T10-L2). Despite TLJK, a change in the thoracic angle was still important to maintain sagittal balance. The thoracolumbar junction plays an important role in sagittal alignment and balance.

Degenerative scoliosis (DS), encompassing conditions like spondylolisthesis and spinal stenosis, is a common type of spinal deformity. Lumbar interbody fusion (LIF) stands as a conventional surgical intervention for this ailment, aiming at decompression, restoration of intervertebral height, and stabilization of motion segments. Despite its widespread use, the precise mechanism underlying spinal fusion remains elusive. In this review, our focus lies on endochondral ossification for spinal fusion, a process involving vertebral development and bone healing. Endochondral ossification is the key step for the successful vertebral fusion. Endochondral ossification can persist in hypoxic conditions and promote the parallel development of angiogenesis and osteogenesis, which corresponds to the fusion process of new bone formation in the hypoxic region between the vertebrae. The ideal material for interbody fusion cages should have the following characteristics: (1) Good biocompatibility; (2) Stable chemical properties; (3) Biomechanical properties similar to bone tissue; (4) Promotion of bone fusion; (5) Favorable for imaging observation; (6) Biodegradability. Utilizing cartilage-derived bone-like constructs holds promise in promoting bony fusion post-operation, thus warranting exploration in the context of spinal fusion procedures.

Neck pain is a prevalent musculoskeletal condition among middle-aged and older adults and may contribute to the development of depressive symptoms. However