Sturm Christopher D, Mayer Sarah, Tandio Joshua, Leasure Jeremi M, Raji Oluwatodimu Richard
Mercy Clinic Neurosurgery: 621 S New Ballas Rd Tower A Suite 297A, St. Louis, MO 63141 United States.
Medical Device Development: 2390 Mission Street, Ste 8, San Francisco, CA, 94110, United States.
N Am Spine Soc J. 2025 Jun 29;23:100766. doi: 10.1016/j.xnsj.2025.100766. eCollection 2025 Sep.
Facet incompetency can lead to altered spine biomechanics. However, while total posterior arthroplasty techniques in lieu of fusion are of increasing interest, unilateral techniques are yet to be investigated. This study aimed to assess the biomechanical effect of a unilateral facet arthroplasty (UFA) system on motion and loading characteristics at the treated L4-5 level.
Seven cadaveric spines from L3-Sacrum were tested within the multidirectional pure moment bending model between 0 to ± 10 Nm in flexion-extension (FE), flexion-extension with 400 N of compressive follower load (FE-FL), axial rotation (AR), and lateral bending (LB). We measured the L4-L5 angular range of motion, the intradiscal pressure, and the contralateral facet contact force. Each specimen was tested in intact (I), capsulotomy (C), medial facetectomy (MF), total facetectomy (TF), and UFA conditions. We also measured the load transfer at the bone-implant interface in the UFA condition.
UFA significantly restored 93% (FE), 77% (FE-FL), 123% (AR), and 106% (LB) of the native range of motion (p<.05). UFA significantly restored the native intradiscal pressure during compressive follower load (I:173±67KPa vs. TF:103± 82KPa vs. UFA:174±69KPa), and partially during contra-axial rotation (I:32±27KPa vs. TF:81±55KPa vs. UFA:59±46KPa). No significant changes were observed in facet contact force. Contra-axial rotation induced the most substantial loads transferred through the bone-implant interface.
UFA is most effective at restoring native intervertebral disc load transfer without altering facet loading at the treated level. UFA is equivalent to the intact condition in FE, FE-FL, and LB, but larger in AR, even after reverting 55% of induced instability.
小关节功能不全可导致脊柱生物力学改变。然而，尽管全后路关节成形术替代融合术越来越受到关注，但单侧技术尚未得到研究。本研究旨在评估单侧小关节置换术（UFA）系统对L4-5治疗节段运动和负荷特征的生物力学影响。
在多向纯力矩弯曲模型中，对7个L3-骶骨尸体脊柱进行测试，屈伸（FE）、400N压缩跟随负荷下的屈伸（FE-FL）、轴向旋转（AR）和侧方弯曲（LB）时的力矩范围为0至±10 Nm。我们测量了L4-L5的运动角度范围、椎间盘内压力和对侧小关节接触力。每个标本在完整（I）、关节囊切开术（C）、内侧小关节切除术（MF）、全小关节切除术（TF）和UFA条件下进行测试。我们还测量了UFA条件下骨-植入物界面的负荷转移。
UFA显著恢复了93%（FE）、77%（FE-FL）、123%（AR）和106%（LB）的原始运动范围（p<0.05）。UFA在压缩跟随负荷期间显著恢复了原始椎间盘内压力（I：173±67KPa vs. TF：103±82KPa vs. UFA：174±69KPa），在对侧轴向旋转期间部分恢复（I：32±27KPa vs. TF：81±55KPa vs. UFA：59±46KPa）。小关节接触力未观察到显著变化。对侧轴向旋转引起通过骨-植入物界面转移的负荷最大。
UFA在恢复原始椎间盘负荷转移方面最有效，且不会改变治疗节段的小关节负荷。在FE、FE-FL和LB方面，UFA与完整状态相当，但在AR方面更大，即使在恢复55%的诱发不稳定性后也是如此。
