Primary anterior lumbar interbody fusion, with and without posterior instrumentation: a 1,377-patient cohort from a multicenter spine registry.

BACKGROUND CONTEXT: Lumbar interbody instrumentation techniques are common and effective surgical options for a variety of lumbar degenerative pathologies. Anterior lumbar interbody fusion (ALIF) has become a versatile and powerful means of decompression, stabilization, and reconstruction. As an anterior only technique, the integrity of the posterior muscle and ligaments remain intact. Adding posterior instrumentation to ALIF is common and may confer benefits in terms of higher fusion rate but could contribute to adjacent segment degeneration due to additional rigidity. Large clinical studies comparing stand-alone ALIF with and without posterior supplementary fixation (ALIF+PSF) are lacking. PURPOSE: To compare rates of operative nonunion and adjacent segment disease (ASD) in ALIF with or without posterior instrumentation. STUDY DESIGN: Retrospective cohort study. PATIENT SAMPLE: Adult patients (≥18 years old) who underwent primary ALIF for lumbar degenerative pathology between levels L4 to S1 over a 12-year period. Exclusion criteria included trauma, cancer, infection, supplemental decompression, noncontiguous fusions, prior lumbar fusions, and other interbody devices. OUTCOME MEASURES: Reoperation for nonunion and ASD compared between ALIF only and ALIF+PSF. METHODS: Reoperations were modeled as time-to-events where the follow-up time was defined as the difference between the primary ALIF procedure and the date of the outcome of interest. Crude cumulative reoperation probabilities were reported at 5-years follow-up. Multivariable Cox proportional hazard regression was used to evaluate risk of operative nonunion and for ASD adjusting for patient characteristics. RESULTS: The study consisted of 1,377 cases; 307 ALIF only and 1070 ALIF+PSF. Mean follow-up time was 5.6 years. The 5-year crude nonunion incidence was 2.4% for ALIF only and 0.5% for ALIF+PSF; after adjustment for covariates, a lower operative nonunion risk was observed for ALIF+PSF (HR=0.22, 95% CI=0.06-0.76). Of the patients who are deemed potentially suitable for ALIF alone, one would need to add posterior instrumentation in 53 patients to prevent one case of operative nonunion at a 5-year follow-up (number needed to treat). Five-year operative ASD incidence was 4.3% for ALIF only and 6.2% for ALIF+PSF; with adjustments, no difference was observed between the cohorts (HR=0.96, 95% CI=0.54-1.71). CONCLUSIONS: While the addition of posterior instrumentation in ALIFs is associated with lower risk of operative nonunion compared with ALIF alone, operative nonunion is rare in both techniques (<5%). Accordingly, surgeons should evaluate the added risks associated with the addition of posterior instrumentation and reserve the supplemental posterior fixation for patients that might be at higher risk for operative nonunion. Rates of operative ASD were not statistically higher with the addition of posterior instrumentation suggesting concern regarding future risk of ASD perhaps should not play a role in considering supplemental posterior instrumentation in ALIF.

Brain and lung metastasis of uterine leiomyosarcoma: illustrative case.

BACKGROUND: Uterine leiomyosarcoma is a rare, extremely aggressive tumor with a high rate of metastasis. Five-year survival for individuals with metastatic disease is only 10%-15%. Metastases to the brain are exceptionally rare and are associated with poor survival. OBSERVATIONS: The authors report a case of uterine leiomyosarcoma that metastasized to the brain in a 51-year-old woman. A single lesion on magnetic resonance imaging was discovered in the right posterior temporo-occipital region 44 months after resection of the primary uterine tumor. The patient underwent a right occipital craniotomy with gross-total resection of the tumor and is receiving adjuvant stereotactic radiosurgery and chemotherapy with gemcitabine and docetaxel. At 8 months postresection, the patient remains alive and asymptomatic with no sign of recurrence. A literature review of prior reported cases was conducted to analyze patterns of approach to patient treatment and survival. LESSONS: The authors found an apparent survival benefit in patients receiving adjuvant radiation therapy.

Do PEEK Rods for Posterior Instrumented Fusion in the Lumbar Spine Reduce the Risk of Adjacent Segment Disease?

BACKGROUND: Polyetheretherketone (PEEK) rods were clinically introduced in the mid-2000s as an alternative to titanium (Ti) rods for posterior instrumented lumbar spine fusion, theorized to reduce the risk of adjacent segment disease (ASD). However, few studies have follow-up beyond 2 years. Consequently, we conducted a matched cohort study using data from Kaiser Permanente's spine registry to compare the 2 rod systems and risk for outcomes. METHODS: Patients aged ≥18 undergoing first posterior lumbar fusion for a degenerative diagnosis from 2009 to 2018 using either a PEEK or a Ti rod were identified. Fusions using Ti rods were 2:1 propensity score matched to PEEK rods on the following factors: patient age, body mass index, smoking, American Society of Anesthesiologists classification, diagnosis, interbody use, bone morphogenic protein use, number of levels fused, fusion levels, and operative year. The matched sample included 154 PEEK and 308 Ti fusions. We used Cox regression to evaluate ASD and nonunion, and logistic regression to evaluate 90-day emergency department (ED) visit, readmission, and complication. RESULTS: We did not observe a difference in risk for ASD (hazard ratio = 1.02, 95% confidence interval [CI] = 0.66-1.59) or ED visit (odds ratio [OR] = 0.88, 95% CI = 0.48-1.59). A lower likelihood of readmission (OR = 0.34, 95% CI = 0.13-0.94) was observed following PEEK fusion compared with Ti. No nonunions or 90-day complications were observed for the PEEK group; 5 (2-year cumulative incidence = 0.7%) nonunions and 4 (1.3%) complications were observed for the Ti group. CONCLUSIONS: Our multicenter study did not support the hypothesis that PEEK rods are associated with a lower ASD risk. Reasons for readmission need to be identified to better understand the differences observed here. Further study of patients with TLIF using Ti and PEEK rods and posterolateral fusion with Ti and PEEK rods is needed. CLINICAL RELEVANCE: The present study adds to the literature supporting their midterm effectiveness of PEEK rods compared with Ti rods for both their safety and their effectiveness at the 5-7-year follow-up. LEVEL OF EVIDENCE: 3.

Minimally invasive surgery for lumbar synovial cysts with coexisting degenerative spondylolisthesis.

BACKGROUND: About one third of lumbar synovial cysts are associated with degenerative spondylolisthesis. Segmental instability is thought to contribute to the pathogenesis and recurrence of synovial cysts and lumbar fusion has been advocated as a treatment of choice in the presence of spondylolisthesis. In patients with spondylolisthesis, minimally invasive resection of lumbar synovial cysts, without fusion, could minimize surgically induced segmental instability while providing good pain relief. METHODS: Clinical and radiological outcomes of lumbar synovial cyst patients with and without spondylolisthesis were retrospectively compared. Pain outcomes were assessed with modified Macnab criteria. RESULTS: Fifty-three patients (18 with grade 1 spondylolisthesis) underwent minimally invasive synovial cyst resection and all had either excellent or good pain outcome at ≤ 8 post- operative weeks (P = 1.000, n = 53). At > 8 post-operative weeks (mean (SD) follow-up of 200 (175) weeks), excellent or good outcomes were noted in 89% of patients without spondylolisthesis and in 75% of patients with spondylolisthesis (P = 0.425, n = 40). Four patients developed a new grade 1 spondylolisthesis at a mean follow-up of 2.6 ± 2.1 years. Nine patients were assessed for spondylolisthesis measurements at 1.2 ± 1.3 years of follow up and no significant difference was observed (5 ± 0 vs 5 ± 1 mm; P = 0.791). Two patients without spondylolisthesis and none of the patients with spondylolisthesis had a synovial cyst recurrence. CONCLUSION: Patients with concomitant lumbar degenerative spondylolisthesis and synovial cyst can have good short- and long-term clinical outcomes with minimally invasive surgery without fusion. Post-operative segmental instability does not appear to be significant in patients with spondylolisthesis. All patients included in this article signed an informed consent for the use of their medical information for research.