How common is acute pelvic fixation failure after adult spine surgery? A single-center study of 358 patients

Sacropelvic Fixation with Porous Fusion/Fixation Screws: A Technical Note and Retrospective Review

OBJECTIVE

The goal of this study was to analyze our initial experience using a novel porous fusion/fixation screw (PFFS) for pelvic fixation and determine our rate of screw malposition requiring intraoperative repositioning.

METHODS

We reviewed 83 consecutive patients who underwent sacropelvic fixation with PFFS at our institution from June 1, 2022 to June 30, 2023 using intraoperative computed tomography-based computer-assisted navigation via an open posterior approach. Following PFFS insertion, intraoperative computed tomography scans were obtained to assess screw positioning. Demographic data were collected, and operative reports and patient images were reviewed to determine what implants were used and if any PFFS required repositioning.

RESULTS

Seventy-four patients (26M:48F) were included, and 57 (77.0%) had a prior sacroiliac joint or lumbar spine surgery. A stacked screw configuration was used in 62/74 cases (83.8%). A total of 235 PFFS were used and six (2.6%) were malpositioned. Of 88 cephalic screws placed in stacked configuration, 4 were malpositioned (4.5%) and 1/123 caudal screws were malpositioned (0.8%). One of 24 sacral-alar-iliac screws placed in a stand-alone configuration was malpositioned (4.2%). Malpositions included 4 medial, 1 lateral, and 1 inferior, and all were revised intraoperatively without major sequela.

CONCLUSIONS

Although PFFSs are larger than traditional sacropelvic fixation screws, stacked sacral-alar-iliac instrumentation can be done safely with computer-assisted navigation. We found a low malposition rate in our initial series of patients, the majority being the cephalad screw in a stacked configuration. This isn't surprising, as these are placed after the caudal screws, which reduces the available corridor size and increases the placement difficulty.

S2 alar-iliac screws are superior to traditional iliac screws for spinopelvic fixation in adult spinal deformity: a systematic review and meta-analysis

PURPOSE

Spinopelvic fixation (SPF) using traditional iliac screws has provided biomechanical advantages compared to previous constructs, but common complications include screw prominence and wound complications. The newer S2 alar-iliac (S2AI) screw may provide a lower profile option with lower rates of complications and revisions for adult spinal deformity (ASD). The purpose of this study was to compare rates of complications and revision following SPF between S2AI and traditional iliac screws in patients with ASD.

METHODS

A PRISMA-compliant systematic literature review was conducted using Cochrane, Embase, and PubMed. Included studies reported primary data on adult patients undergoing S2AI screw fixation or traditional IS fixation for ASD. Primary outcomes of interest were rates of revision and complications, which included screw failure (fracture and loosening), symptomatic screw prominence, wound complications (dehiscence and infection), and L5-S1 pseudarthrosis.

RESULTS

Fifteen retrospective studies with a total of 1502 patients (iliac screws: 889 [59.2%]; S2AI screws: 613 [40.8%]) were included. Pooled analysis indicated that iliac screws had significantly higher odds of revision (17.1% vs 9.1%, OR = 2.45 [1.25-4.77]), symptomatic screw prominence (9.9% vs 2.2%, OR = 6.26 [2.75-14.27]), and wound complications (20.1% vs 4.4%, OR = 5.94 [1.55-22.79]). S2AI screws also led to a larger preoperative to postoperative decrease in pain (SMD = - 0.26, 95% CI = -0.50, - 0.011).

CONCLUSION

The findings from this review demonstrate higher rates of revision, symptomatic screw prominence, and wound complications with traditional iliac screws. Current data supports the use of S2AI screws specifically for ASD.

PROSPERO ID

CRD42022336515.

LEVEL OF EVIDENCE

III.

Biomechanical evaluation of multiple pelvic screws and multirod construct for the augmentation of lumbosacral junction in long spinal fusion surgery

Background: Posterior long spinal fusion was the common procedure for adult spinal deformity (ASD). Although the application of sacropelvic fixation (SPF), the incidence of pseudoarthrosis and implant failure is still high in long spinal fusion extending to lumbosacral junction (LSJ). To address these mechanical complications, advanced SPF technique by multiple pelvic screws or multirod construct has been recommended. This was the first study to compare the biomechanical performance of combining multiple pelvic screws and multirod construct to other advanced SPF constructs for the augmentation of LSJ in long spinal fusion surgery through finite element (FE) analysis.

Methods: An intact lumbopelvic FE model based on computed tomography images of a healthy adult male volunteer was constructed and validated. The intact model was modified to develop five instrumented models, all of which had bilateral pedicle screw (PS) fixation from L1 to S1 with posterior lumbar interbody fusion and different SPF constructs, including No-SPF, bilateral single S2-alar-iliac (S2AI) screw and single rod (SS-SR), bilateral multiple S2AI screws and single rod (MS-SR), bilateral single S2AI screw and multiple rods (SS-MR), and bilateral multiple S2AI screws and multiple rods (MS-MR). The range of motion (ROM) and stress on instrumentation, cages, sacrum, and S1 superior endplate (SEP) in flexion (FL), extension (EX), lateral bending (LB), and axial rotation (AR) were compared among models.

Results: Compared with intact model and No-SPF, the ROM of global lumbopelvis, LSJ, and sacroiliac joint (SIJ) was decreased in SS-SR, MS-SR, SS-MR, and MS-MR in all directions. Compared with SS-SR, the ROM of global lumbopelvis and LSJ of MS-SR, SS-MR, and MS-MR further decreased, while the ROM of SIJ was only decreased in MS-SR and MS-MR. The stress on instrumentation, cages, S1-SEP, and sacrum decreased in SS-SR, compared with no-SPF. Compared with SS-SR, the stress in EX and AR further decreased in SS-MR and MS-SR. The most significantly decreased ROM and stress were observed in MS-MR.

Conclusion: Both multiple pelvic screws and multirod construct could increase the mechanical stability of LSJ and reduce stress on instrumentation, cages, S1-SEP, and sacrum. The MS-MR construct was the most adequate to reduce the risk of lumbosacral pseudarthrosis, implant failure, and sacrum fracture. This study may provide surgeons with important evidence for the application of MS-MR construct in the clinical settings.