Kotani Y, McNulty P S, Abumi K, Cunningham B W, Kaneda K, McAfee P C
Department of Orthopaedic Surgery, Hokkaido University School of Medicine, Sapporo, Japan.
Spine (Phila Pa 1976). 1998 Jul 15;23(14):1559-65. doi: 10.1097/00007632-199807150-00011.
The biomechanical role of the cervical uncovertebral joint was investigated using human cadaveric spines. Sequential resection of cervical uncovertebral joints, including clinical anteromedial foraminotomy, was conducted, followed by biomechanical testing after each stage of resection.
To clarify the biomechanical role of uncovertebral joints and clinical anteromedial foraminotomy in the cervical spine and their effects on interbody bone graft stability.
Although the biomechanical role of the cervical uncovertebral joints has been considered to be that of a guiding mechanism in flexion and extension and a limiting mechanism in posterior translation and lateral bending, there have been no studies quantifying this role. According to results in quantitative anatomic studies, anatomic variations exist in uncovertebral joints, depending on the vertebral level, articular angulation, and relative height of the joints.
Fourteen human functional spinal units at C3-C4 and C6-C7 underwent sequential uncovertebral joint resection, with each stage of resection followed by biomechanical testing. The uncovertebral joint was divided anatomically into three parts on each side: the posterior foraminal part, the posterior half, and the anterior half. The loading modes included torsion, flexion, extension, and lateral bending. A simulated anterior bone graft construct was also tested after each uncovertebral joint resection procedure.
Significant changes in stability were observed after sequential uncovertebral joint resection in all loading modes (P < 0.05). The biomechanical contribution of uncovertebral joints decreased in the following order: the posterior foraminal part, the posterior half, and the anterior half. Unilateral and bilateral foraminotomy most affected the stability of the functional spinal unit during extension, causing a 30% and 36% decrease in stiffness of the functional spinal unit, respectively. The effect was less in torsion and lateral bending. After sequential resection, there was a statistically significant difference between decreases in torsional stiffness at C3-C4 and C6-C7 (P < 0.05). The stiffness of the simulated bone graft construct decreased progressively during flexion and lateral bending after each foraminotomy (P < 0.05). Increased bone graft height of 79% returned stability to the preforaminotomy level.
This is the first study to quantitate the biomechanical role of uncovertebral joints in cervical segmental stability and the effect at each intervertebral level. The effect differs because of anatomic variations in uncovertebral joints. The major biomechanical function of uncovertebral joints includes the regulation of extension and lateral bending motion, followed by torsion, which is mainly provided by the posterior uncovertebral joints. This study highlights the clinical assessment of additional segmental instability attributed to destruction of the uncovertebral joints during surgical procedures or by neoplastic lesions.
使用人体尸体脊柱研究颈椎钩椎关节的生物力学作用。依次切除颈椎钩椎关节，包括临床前路内侧椎间孔切开术，在每个切除阶段后进行生物力学测试。
阐明钩椎关节和临床前路内侧椎间孔切开术在颈椎中的生物力学作用及其对椎间植骨稳定性的影响。
尽管颈椎钩椎关节的生物力学作用被认为是屈伸运动中的导向机制以及后移和侧弯运动中的限制机制，但尚无研究对该作用进行量化。根据定量解剖学研究结果，钩椎关节存在解剖变异，这取决于椎体节段、关节角度和关节相对高度。
对14个C3-C4和C6-C7节段的人体功能性脊柱单元依次进行钩椎关节切除，每个切除阶段后进行生物力学测试。将钩椎关节在每侧解剖学上分为三个部分：椎间孔后部、后半部和前半部。加载模式包括扭转、前屈、后伸和侧弯。在每次钩椎关节切除术后还对模拟前路植骨结构进行了测试。
在所有加载模式下，依次切除钩椎关节后均观察到稳定性有显著变化（P < 0.05）。钩椎关节的生物力学贡献按以下顺序降低：椎间孔后部、后半部和前半部。单侧和双侧椎间孔切开术对功能性脊柱单元在后伸时的稳定性影响最大，分别导致功能性脊柱单元刚度降低30%和36%。在扭转和侧弯时影响较小。依次切除后，C3-C4和C6-C7节段扭转刚度降低之间存在统计学显著差异（P < 0.05）。每次椎间孔切开术后，模拟植骨结构在屈曲和侧弯时的刚度逐渐降低（P < 0.05）。植骨高度增加79%可使稳定性恢复到椎间孔切开术前水平。
这是第一项量化钩椎关节在颈椎节段稳定性中的生物力学作用以及在每个椎间水平的影响的研究。由于钩椎关节的解剖变异，其影响有所不同。钩椎关节的主要生物力学功能包括调节后伸和侧弯运动，其次是扭转，这主要由后钩椎关节提供。本研究强调了在手术过程中或因肿瘤病变导致钩椎关节破坏而引起的额外节段性不稳定的临床评估。
