A novel rat model of interbody fusion based on anterior lumbar corpectomy and fusion (ALCF)

Background Rats have been widely used as experimental animals when performing fundamental research because they are economical, rapidly reproducing, and heal quickly. While the rat interbody fusion model has been applied in basic studies, existing rat models generally have shortcomings, such as insufficiently simulating clinical surgery. The purpose of this study was to develop a novel rat model of interbody fusion which more closely represents clinical surgery. Methods The internal fixation was designed based on physical measurements of the rats’ lumbar spine. Then, ten rats divided into two groups (A and B) underwent anterior lumbar corpectomy and fusion of the L5 vertebrae. Groups A and B were sacrificed four and 8 weeks post-surgery, respectively. Micro-CT and histological examination were used to evaluate the model. Fusion rate, bone volume fraction (BV/TV), trabecular bone number (Tb.N), trabecular bone thickness (Tb.Th), and the area ratio of newly formed bone (NB) were calculated for quantitative analysis. Results Based on the L5 body dimensions of individual rats, 3D-printed titanium cage of the appropriate size were printed. The operations were successfully completed in all ten rats, and X-ray confirmed that internal fixation was good without migration. Micro-CT suggested that fusion rates in group B (100%) were greater than group A (40%, P < 0.05). The BV/TV (B: 42.20 ± 10.50 vs. A: 29.02 ± 3.25, P < 0.05) and Tb.N (B: 4.66 ± 1.23 vs. A: 1.97 ± 0.40, P < 0.05) were greater in group B than A, and the Tb.Th in group B was lower than group A (B: 0.10 ± 0.04 vs. A: 0.15 ± 0.02, P < 0.05). Histomorphometry results demonstrated that the area ratio of NB in group B were greater than group A (B: 35.72 ± 12.80 vs. A: 12.36 ± 16.93, P < 0.05). Conclusion A rat interbody fusion model based on anterior lumbar corpectomy and fusion has successfully been constructed and verified. It could provide a new choice for fundamental research using animal models of spinal fusion.

A Novel Rat Model of Interbody Fusion based on Anterior Lumbar Corpectomy and Fusion (ALCF)

Background: Rats have been widely used as experimental animals when performing fundamental research because they are economical, rapidly reproducing, and heal quickly. While the rat interbody fusion model has been applied in basic studies, existing rat models generally have shortcomings, such as insufficiently simulating clinical surgery. The purpose of this study was to develop a novel rat model of interbody fusion which more closely represents clinical surgery.Methods: The internal fixation was designed based on physical measurements of the rats’ lumbar spine. Then, ten rats divided into two groups (A and B) underwent anterior lumbar corpectomy and fusion of the L5 vertebrae. Groups A and B were sacrificed four and eight weeks post-surgery, respectively. Micro-CT and histological examination were used to evaluate the model. Fusion rate, bone volume fraction (BV/TV), trabecular bone number (Tb.N), trabecular bone thickness (Tb.Th), and the area ratio of newly formed bone (NB) were calculated for quantitative analysis.Results: Based on the L5 body dimensions of individual rats, 3D-printed titanium cage of the appropriate size were printed. The operations were successfully completed in all ten rats, and X-ray confirmed that internal fixation was good without migration. Micro-CT suggested that fusion rates in group B (100%) were greater than group A (40%, P<0.05). The BV/TV (B: 42.20±10.50 vs. A: 29.02±3.25, P<0.05) and Tb.N (B: 4.66±1.23 vs. A: 1.97±0.40, P<0.05) were greater in group B than A, and the Tb.Th in group B was lower than group A (B: 0.10±0.04 vs. A: 0.15±0.02, P<0.05). Histomorphometry results demonstrated that the area ratio of NB in group B were greater than group A (B: 35.72±12.80 vs. A: 12.36±16.93, P<0.05).Conclusion: A rat interbody fusion model based on anterior lumbar corpectomy and fusion has successfully been constructed and verified. It could provide a new choice for fundamental research using animal models of spinal fusion.

Prone transpsoas lumbar corpectomy: simultaneous posterior and lateral lumbar access for difficult clinical scenarios

OBJECTIVE Lateral lumbar corpectomy with interbody fusion has been well described via a transpsoas approach in the lateral position, as has lumbar interbody fusion with posterior fixation in the prone position. However, no previous report has described the use of both an open posterior approach and a lateral transpsoas approach simultaneously in the prone position. Here, the authors describe their technique of performing transpsoas lumbar corpectomy in the prone position in order to have simultaneous posterior and lateral access for difficult clinical scenarios, and they report their early clinical experience. METHODS The surgical technique for simultaneous posterior and lateral transpsoas access to the lumbar spine was reviewed and described in detail. The cases of 2 patients who underwent simultaneous posterior and lateral access in the prone position for complex lumbar pathology were retrospectively reviewed. Clinical presentation, preoperative radiographs, postoperative course, and postoperative radiographs were reviewed. RESULTS The first patient presented after previous transforaminal lumbar interbody fusion that was complicated by significant subsidence of the intervertebral cage, vertebral body split fracture, rotational instability, and resulting spinal stenosis. A simultaneous posterior and lateral transpsoas approach in the prone position allowed for removal of the previous cage, lumbar corpectomy, and rigid posterior fixation with direct decompression. The second patient had a significant pathologic burst fracture secondary to a plasmacytoma with retropulsion, resulting in vertebra plana and significant canal stenosis. Simultaneous approaches allowed for complete resection of the plasmacytoma, restoration of lumbar alignment, rigid fixation, and direct posterior decompression. There were no short-term complications, and both patients had resolution of their preoperative symptoms. CONCLUSIONS Simultaneous posterior and lateral transpsoas access to the lumbar spine in the prone position is a previously unreported technique that allows a safe surgical approach to difficult clinical scenarios.

Minimally invasive lateral transpsoas approach for lumbar corpectomy and stabilization

Background: Here, we present our experience with the minimally invasive (MI) transpsoas approach for lumbar corpectomy and stabilization. Transpsoas approach accesses the lumbar spine and includes both the direct lateral interbody fusion and extreme lateral interbody fusion techniques. Both procedures utilize a tubular retractor system which facilitates adequate retraction and direct visualization of the target, while supposedly reducing soft tissue trauma. Case Description: We evaluated two patients, one with a traumatic L2 wedge compression fracture and the other with an L3 pathological compression fracture due to multiple myeloma. Both patients underwent MI transpsoas lumbar corpectomy, anterior column reconstruction with an expandable cage, and posterior pedicle screw instrumentation to correct a kyphotic deformity. Both patients were mobilized on the 1st postoperative day and experienced significant postoperative pain relief. Conclusion: In two cases involving L2 and L3 compression fractures, MI transpsoas lumbar corpectomy was safely performed, with reduced perioperative and postoperative morbidity. Here, the transpsoas approach also allowed for early mobilization, adequate postoperative biomechanical stability, and resulted in immediate good outcomes.