Welke Bastian, Schwarze Michael, Hurschler Christof, Kedah Shadi, Daentzer Dorothea, Nebel Dennis
Hannover Medical School, Department of Orthopaedic Surgery, Laboratory for Biomechanics and Biomaterials, Hannover Medical School, Department of Orthopaedic Surgery, Laboratory for Biomechanics and Biomaterials, Germany.
Hannover Medical School, DIAKOVERE Annastift, Department of Orthopaedic Surgery, Spine Section, Hannover Medical School, DIAKOVERE Annastift, Department of Orthopaedic Surgery, Spine Section, Germany.
Eur Spine J. 2025 Aug 12. doi: 10.1007/s00586-025-09192-2.
Instrumented posterior lumbar fixation (PLF) with fusion is the surgical standard for treating various degenerative changes or deformities of the spine. Several studies have shown the risk of adjacent segment pathology following fusion. Therefore, revision procedures are often required which involve extension of instrumentation to adjacent levels. The purpose of this study was to evaluate the stability of multisegmental-instrumentation of the lumbar spine when extended with continuous rods or with connectors to the lower mid thoracic spine.
Eight human specimens from Th5 to S1 were used and loaded with moments of 7.5 Nm about the three anatomical axes. A total of eight different PLF configurations were examined, with three conditions in a short Th10-S1 instrumentation and five conditions with a long Th6-S1 instrumentation. Continuous rods, and axial and lateral connectors were used to extend the PLF. Total range of motion (tROM) and total neutral zone (tNZ), as well as the intersegmental range of motion (iROM), were evaluated.
Overall, all configurations of the PLF demonstrated high primary stability. The iROM was less than 2 degrees in all segments studied where lengthening was performed with continuous rods or connectors. We found only a few significant differences, which are unlikely to be clinically relevant due to their very small magnitudes.
From a biomechanical point of view, the axial and lateral connectors provide comparable primary stability to a continuous rod system. Thus, the use of connectors is likely to be a suitable approach of extending an existing lumbar fixation to the lower and mid thoracic spine.
Biomechanical study.
器械辅助下的后路腰椎融合固定术（PLF）是治疗各种脊柱退行性病变或畸形的手术标准。多项研究表明融合术后存在相邻节段病变的风险。因此，通常需要进行翻修手术，这涉及将内固定延伸至相邻节段。本研究的目的是评估腰椎多节段内固定在通过连续棒或连接器延伸至胸段中下部时的稳定性。
使用8个从T5至S1的人体标本，并围绕三个解剖轴施加7.5 Nm的力矩。总共检查了8种不同的PLF配置，其中3种情况为短节段T10-S1内固定，5种情况为长节段T6-S1内固定。使用连续棒、轴向和横向连接器来延伸PLF。评估了总活动范围（tROM）、总中立区（tNZ）以及节段间活动范围（iROM）。
总体而言，PLF的所有配置均显示出较高的初始稳定性。在所有使用连续棒或连接器进行延长的研究节段中，iROM均小于2度。我们仅发现了一些显著差异，由于其幅度非常小，不太可能具有临床相关性。
从生物力学角度来看，轴向和横向连接器提供的初始稳定性与连续棒系统相当。因此，使用连接器可能是将现有的腰椎固定延伸至胸段中下部的合适方法。
生物力学研究。
