Assessment of Rod Material Types in Spine Surgery Outcomes: A Systematic Review

Vancomycin Antibiotic Prophylaxis Compared to Cefazolin Increases Risk of Surgical Site Infection Following Spine Surgery

Study DesignRetrospective analysis of randomized controlled trial.ObjectivesSurgical site infection (SSI) after spine surgery has severe negative health and financial consequences. Surgical antibiotic prophylaxis (SAP) is a routinely used method to prevent SSIs in the spine patient population. The most commonly used antibiotic is cefazolin, with vancomycin often being substituted in the case of penicillin or cephalosporin allergy. Vancomycin as SAP has been associated with increased SSI in the joint replacement literature, but this is not yet well defined in the spinal surgery population. The purpose of this study was to determine whether vancomycin SAP compared to cefazolin SAP is associated with increased risk of SSI.Methods535 patients, aged 16 years or older, underwent elective multi-level open posterior spinal fusion surgery at the thoracic, thoracolumbar, or lumbar levels. Demographic and operative characteristics as well as post-operative outcomes were compared between the following groups: (1) noninfected-cefazolin, (2) noninfected-vancomycin, (3) infected-cefazolin, and (4) infected-vancomycin. Primary outcomes were superficial and complicated (deep and organ/space) infections.ResultsThe following risk factors for SSI were identified in a logistic regression analysis: vancomycin (OR 2.498, 95% CI, 1.085-5.73, P = 0.031), increasing operating time (OR 1.006, 95% CI, 1.001-1.010 P = 0.010), weight (OR 1.020, 95% CI 1.006-1.034, P = 0.005), revision procedure (OR 2.343, 95% CI 1.283-4.277, P = 0.006), and depression (OR 2.366, 95% CI 1.284-4.360, P = 0.006).ConclusionsIn open posterior approach spinal fusion surgery, vancomycin SAP is associated with increased risk of infection compared to cefazolin SAP.

Forcefully engaging rods into tulips with gap discrepancy leading to pedicle screw loosening-a biomechanical analysis using long porcine spine segments

BACKGROUND CONTEXT

Long-segment pedicle screw instrumentation is widely used to treat complex spinal disorders. Rods are routinely precontoured to maximize assistance on the correcting side of the deformity, but there often exists a residual gap discrepancy between the precontoured rods and screw tulips. No previous research has investigated the diminished pullout strength of the most proximal or distal pedicle screw resulting from a mismatched rod in long-segment pedicle screw instrumentation.

PURPOSE

The present study aimed to investigate the decreased pullout force of pedicle screws affected by the gap discrepancy when forcefully engaging a mismatched rod into a tulip in a normal-density porcine spine.

STUDY DESIGN

The pedicle screw fixation strength under axial pullout force was compared among three different gap discrepancies between rods and tulips using long porcine spine segments.

METHODS

Twelve porcine lumbar vertebrae (L3-L6) were implanted with pedicle screws and rods. Screws on one side had no gap between the tulip and rod (0-mm group), while the most proximal screw on the other side had an intentional gap of 3 mm (3-mm group) or 6 mm (6-mm group). Three hours after forcefully engaging the rod into the tulips at room temperature, the set screws in all specimens were loosened, and each specimen was dissected into individual vertebrae for subsequent pullout testing.

RESULTS

The control group exhibited significantly greater pullout strength (1987.68 ± 126.80 N) than the groups from different rod-tulip configurations (p<.05), with significantly greater strength in the 3-mm group (945.62 ± 97.43 N) than the 6-mm group (655.30 ± 194.49 N) (p<.05). Only 47.6% and 33.0% of the pullout strength was retained in the 3-mm and 6-mm groups, respectively, compared to the control group.

CONCLUSIONS

Gap discrepancies between rods and tulips can significantly reduce pedicle screw pullout strength, with a correlation between decreased strength and increased gaps. Surgeons should avoid forcefully engaging mismatched rods and consider well-fitted contoured rods in spinal surgery to minimize the risk of screw loosening.

CLINICAL SIGNIFICANCE

The gap discrepancy between rod and tulip significantly affected pullout strength, with greater gaps leading to reduced strength. Forcefully engaging mismatched rods into tulips in degenerative spinal surgery should be avoided to minimize the risk of early screw pullout.

Comparison of MRI Visualization Following Minimally Invasive and Open TLIF: A Retrospective Single-Center Study

Analysis of magnetic resonance image (MRI) quality after open (Op)-transforaminal interbody fusion (TLIF) and minimally invasive (MI)-TLIF with the implantation of structurally different systems has not previously been performed. The objective of this study was to conduct a comparative analysis of the postoperative MRI following MI and Op one-segment TLIF. Material and Methods: The nonrandomized retrospective single-center study included 80 patients (46 men and 24 women) aged 48 + 14.2 years. In group I (n = 20) Op-TLIF with open transpedicular screw fixation (TSF) was performed, in II group (n = 60), the MI-TLIF technique was used: IIa (n = 20)—rigid interspinous stabilizer; IIb (n = 20)—unilateral TSF and contralateral facet fixation; IIc (n = 20)—bilateral TSF. Results: Comparison of the quality of postoperative imaging in IIa and IIb subgroups showed fewer MRI artifacts and a significantly greater MR deterioration after Op and MI TSF. Comparison of the multifidus muscle area showed less atrophy after MI-TLIF and significantly greater atrophy after Op-TLIF. Conclusion: MI-TLIF and Op-TLIF with TSF have comparable postoperative MR artifacts at the operative level, with a greater degree of muscle atrophy using the Op-TLIF. Rigid interspinous implant and unilateral TSF with contralateral facet fixation have less artifacts and changes in the multifidus muscle area.