[Application of digital orthopedic technology for observing degenerative lumbar segmental instability of three-dimensional kinematic characteristics in vivo].
OBJECTIVE
To explore the characteristics of three-dimensional motion of lumbar instability segmental in vivo under physiological weight bearing so as to establish three-dimensional diagnostic criteria for degenerative lumbar segmental instability (DLSI).


METHODS
Eight patients aged 29-65 years with DLSI at L3/4 were studied as instability group (L3/4), 9 patients aged 51-60 years with DLSI at L4/5 as instability group (L4/5) and 10 healthy volunteers aged 26-51 years as normal group. Three-dimension (3D) reproductions by matching lumbar spine models were reconstructed from thin-section computed tomography scans. Spine motions were then reproduced by matching lumber spine models and images from dual fluoroscopic imaging system (DFIS). The models were matched to the osseous outlines of images from two orthogonal views to determine the SD position of vertebrae for each pose. From local coordinate systems at end plates, the motion of cephalad vertebrae relative to cauddal vertebrae was calculated for vertebrae levels.


RESULTS
The motion pattern at L3/4 was altered . During flexion-extension, migration was significantly larger than normal group along sagittal axis (P < 0.05); rotation was significantly larger than normal group along vertical axis; migration was significantly smaller than normal group along vertical axis; during left-right twisting, rotation was significantly larger than normal group along vertical axis (P < 0.05). The motion pattern at L4/5 was also altered . During flexion-extension, migrations was significantly larger than normal group along sagittal axis (P < 0.05). During left-right twisting, migration and rotation were significantly smaller than normal group along vertical axis (P < 0.05). Rotation was significantly larger than normal group along sagittal axis. During left-right bending, rotation was significantly larger than normal group along sagittal axis (P < 0.05).


CONCLUSIONS
Lumbar instability segments were significantly different compared with normal lumbar segments. And lumbar instability segments (at L3/4) were also different from lumbar instability segments (at L4/5). Different three-dimensional diagnostic criteria should be formulated for different lumbar instability segments.
Tianjin University Graduate School of Chinese Medicine, Tianjin 300193, China.
Botao
B
Wang
Spinal Surgery, Tianjin Hospital, Tianjin 300211, China. Email: xiaqun6@163.com.
Qun
Q
Xia
Jun
J
Miao
Hongda
H
Xu
Hua
H
Yu
Shaobai
S
Wang
Guoan
G
Li
D000328:Adult; D000368:Aged; D001696:Biomechanical Phenomena; D005471:Fluoroscopy; D006801:Humans; D007593:Joint Instability; D008159:Lumbar Vertebrae / Q000502:physiology*; D008161:Lumbosacral Region; D008279:Magnetic Resonance Imaging; D008875:Middle Aged; D009983:Orthopedic Equipment; D011187:Posture; D016059:Range of Motion, Articular; D012399:Rotation