Titanium cages versus autogenous iliac crest bone grafts in anterior cervical discectomy and fusion treatment of patients with cervical degenerative diseases: a systematic review and meta-analysis.

OBJECTIVE: A systematic review and partial meta-analysis is conducted to compare the efficacy and safety of anterior cervical decompression and fusion procedures employing either rectangular titanium cages or iliac crest autografts in patients suffering from cervical degenerative disc diseases. METHODS: Medline, PubMed, CENTRAL, and Google Scholar databases were searched up to June 2015, using the key words cervical discectomy; bone transplantation; titanium cages; and iliac crest autografts. Outcomes of interbody fusion rates were compared using odds ratios (ORs) with 95% confidence intervals (CIs). Values of the Japanese Orthopaedic Association score, and visual analog scale before and after operation were also compared. RESULTS: The rate of interbody fusion was similar between patients in the iliac crest autograft and titanium cage groups (pooled OR = 0.33, 95% CI = 0.07 to 1.66, P = .178). The overall analysis showed that patients in the two groups did not have significantly different post-surgery Japanese Orthopaedic Association score (pooled difference in means = -0.05, 95% CI = 0.73 to 0.63, P = .876). Improvement in arm and neck pain scores were assessed with a visual analog scale and differed significantly between patients in the iliac crest autograft and titanium cage groups (pooled difference in means = 0.16, 95% CI = -0.44 to 0.76, P = .610; and pooled difference in means = -0.44, 95% CI = -2.23 to 1.36, P = .634, respectively). CONCLUSIONS: Our results suggest that the use of titanium cages constitutes a safe and efficient alternative to iliac crest bone autografts for anterior cervical discectomy with fusion.

Can an Endplate-conformed Cervical Cage Provide a Better Biomechanical Environment than a Typical Non-conformed Cage?: A Finite Element Model and Cadaver Study.

OBJECTIVES: To evaluate the biomechanical characteristics of endplate-conformed cervical cages by finite element method (FEM) analysis and cadaver study. METHODS: Twelve specimens (C2 -C7 ) and a finite element model (C3 -C7 ) were subjected to biomechanical evaluations. In the cadaver study, specimens were randomly assigned to intact (I), endplate-conformed (C) and non-conformed (N) groups with C4-5 discs as the treated segments. The morphologies of the endplate-conformed cages were individualized according to CT images of group C and the cages fabricated with a 3-D printer. The non-conformed cages were wedge-shaped and similar to commercially available grafts. Axial pre-compression loads of 73.6 N and moment of 1.8 Nm were used to simulate flexion (FLE), extension (EXT), lateral bending (LB) and axial rotation (AR). Range of motion (ROM) at C4-5 of each specimen was recorded and film sensors fixed between the cages and C5 superior endplates were used to detect interface stress. A finite element model was built based on the CT data of a healthy male volunteer. The morphologies of the endplate-conformed and wedge-shaped, non-conformed cervical cages were both simulated by a reverse engineering technique and implanted at the segment of C4-5 in the finite element model for biomechanical evaluation. Force loading and grouping were similar to those applied in the cadaver study. ROM of C4-5 in group I were recorded to validate the finite element model. Additionally, maximum cage-endplate interface stresses, stress distribution contours on adjoining endplates, intra-disc stresses and facet loadings at adjacent segments were measured and compared between groups. RESULTS: In the cadaver study, Group C showed a much lower interface stress in all directions of motion (all P < 0.05) and the ROM of C4-5 was smaller in FLE-EXT (P = 0.001) but larger in AR (P = 0.017). FEM analysis produced similar results: the model implanted with an endplate-conformed cage presented a lower interface stress with a more uniform stress distribution than that implanted with a non-conformed cage. Additionally, intra-disc stress and facet loading at the adjacent segments were obviously increased in both groups C and N, especially those at the supra-jacent segments. However, stress increase was milder in group C than in group N for all directions of motion. CONCLUSIONS: Endplate-conformed cages can decrease cage-endplate interface stress in all directions of motion and increase cervical stability in FLE-EXT. Additionally, adjacent segments are possibly protected because intra-disc stress and facet loading are smaller after endplate-conformed cage implantation. However, axial stability was reduced in group C, indicating that endplate-conformed cage should not be used alone and an anterior plate system is still important in anterior cervical discectomy and fusion.

Mast Quadrant-assisted minimally invasive modified transforaminal lumbar interbody fusion: single incision versus double incision.

BACKGROUND: The concept of minimally invasive techniques is to make every effort to reduce tissue damage. Certainly, reducing skin incision is an important part of these techniques. This study aimed to investigate the clinical feasibility of Mast Quadrant-assisted modified transforaminal lumbar interbody fusion (TLIF) with a small single posterior median incision. METHODS: During the period of March 2011 to March 2012, 34 patients with single-segment degenerative lumbar disease underwent the minimally invasive modified TLIF assisted by Mast Quadrant with a small single posterior median incision (single incision group). The cases in this group were compared to 37 patients with single-segment degenerative lumbar disease in the double incision group. The perioperative conditions of patients in these two groups were statistically analyzed and compared. The Oswestry Disability Index (ODI) scores, Visual Analog Scale (VAS) scores, and sacrospinalis muscle damage evaluation indicators before operation and 3, 12 months postoperation were compared. RESULTS: A total of 31 and 35 cases in the single incision and double incision groups, respectively, completed at least 12 months of systemic follow-up. The differences in perioperative conditions between the two groups were not statistically significant. The incision length of the single incision group was significantly shorter than that of the double incision group (P < 0.01). The ODI and VAS scores of patients in both groups improved significantly at 3 and 12 months postoperation. However, these two indicators at 3 and 12 months postoperation and the sacrospinalis muscle damage evaluation indicators at 3 months postoperation did not differ significantly between the two groups (P ≥ 0.05). CONCLUSIONS: Mast Quadrant-assisted modified TLIF with a small single posterior median incision has excellent clinical feasibility compared to minimally invasive TLIF with a double paramedian incision.