In vivo dynamic motion characteristics of the lower lumbar spine: L4–5 lumbar degenerative disc diseases undergoing unilateral or bilateral pedicle screw fixation combined with TLIF

Abstract

Objective To evaluate the short-term in vivo dynamic motion characteristics of the lower lumbar spine (L3–S1) after unilateral pedicle screw fixation (UPSF) or bilateral pedicle screw fixation (BPSF) combined with TLIF for treatment of L4–5 lumbar degenerative disc diseases (DDD). Methods Twenty-eight patients were recruited (13 UPSF, 15 BPSF). Each patient was CT-scanned to construct 3D models of the L3–S1 vertebrae. The dual fluoroscopic imaging system (DFIS) was then used to image the lumbar spine while the patient performed seven functional activities (upright standing, maximum extension, flexion, left–right twist, and left–right bend). The in vivo vertebral positions were reproduced using the 3D vertebral models and DFIS images. The ranges of motion (ROMs) of L3–4, L4–5, and L5–S1 segments were analyzed. Results At the index L4–5 segment, the primary ROM of left–right twist of the UPSF group (2.11 ± 0.52°) was significantly larger ( p = 0.000) than the BPSF group (0.73 ± 0.32°). At the proximal adjacent L3–4 segment, the primary ROMs of left–right twist, and left–right bend of the UPSF group (2.16 ± 0.73°, 2.28 ± 1.03°) were significantly less ( p = 0.003, 0.023) than the BPSF group (3.17 ± 0.88, 3.12 ± 1.04°), respectively. However, at distal adjacent L5–S1 segment, no significant difference was found between the two groups during all activities. Conclusions The ROM in left–right twisting of UPSF group was significantly larger compared with BPSF group at the index level in the short term. The UPSF has less impact on the cranial adjacent level (L3–4) in left–right twisting and bending activities compared to the BPSF. The data implied that the UPSE and BPSF combined with TLIF would result in different biomechanics in the index and cranial adjacent segment biomechanics. Long-term follow-up studies are necessary to compare the clinical outcomes of the two surgeries. Electronic supplementary material The online version of this article (10.1186/s13018-019-1198-6) contains supplementary material, which is available to authorized users.

Biomechanical evaluation of a short-rod technique for lumbar fixation surgery

“…Spinal stability was analyzed by measuring the range of motion (ROM) and compressive stiffness around the neutral zone of the spinal segment ( Chen et al, 1990 ; Christine et al, 2019 ). Common instrument-related complications were also assessed, including the risk of endplate fracture, degeneration of facet joints, and screw loosening and breakage ( DieeN et al, 1999 ; Nie et al, 2019 ; Xi et al, 2021 ). These risks were assessed using the stress distribution and displacement of the model (Chen et al, 2001 ).…”

“…Assessing the stability of the lumbar spine, such as ROM and axial stiffness ( Christine et al, 2019 ), is the most important indicator of the effectiveness of surgery. Postoperative complications are a major cause of re-operation and reduced patient quality of life, with endplate fracture, facet joint degeneration, screw loosening, and breakage being the most commonly reported ( DieeN et al, 1999 ; Chang et al, 2017 ; Nie et al, 2019 ; Xi et al, 2021 ). The biomechanical evaluation of screw fixation systems by experimental methods is time-consuming, labor-intensive, and expensive.…”

Biomechanical Characterization of Unilateral and Bilateral Posterior Lumbar Interbody Fusion Constructs

“…This study showed that the increase in axial rotation observed in biomechanics studies does translate to the clinical scenario, with an average left-right twist ROM of 2.11 ± 0.52 degrees for unilateral constructs compared to 0.73 ± 0.32 degrees for bilateral constructs. The authors also reported a reduced effect on adjacent segments with unilateral constructs, as indicated by a reduction in adjacent segment motion [ 5 ]. Unfortunately, no outcome data was included in this report making it difficult to determine the clinical implications of these differences in motion characteristics.…”

“…Numerous clinical studies have been published in the last decade comparing the efficacy of unilateral and bilateral PLIF and TLIF constructs, underscoring the importance of a sound biomechanical understanding of each treatment modality [5,9,[18][19][20][21]. Results of these studies are not as clear as those biomechanics studies previously discussed in terms of establishing the superiority of unilateral or bilateral pedicle screw fixation.…”

“…Numerous techniques have been studied in order to combat these deleterious effects. For example, minimally invasive approaches—such as the use of unilateral pedicle screw fixation—have the potential to increase graft loading while decreasing operating time, intraoperative blood loss, recovery time, and the risk of adjacent segment disease [ 4 , 5 ]. One of the major advantages of unilateral fixation is the decrease in patient morbidity.…”