Perioperative outcomes, complications, and costs associated with lumbar spinal fusion in older patients with spinal stenosis and spondylolisthesis

Protective effect of calcitonin on lumbar fusion-induced adjacent-segment disc degeneration in ovariectomized rat

Background

Intervertebral disc (IVD) degeneration and pathological changes in the spinal cord are major causes of back pain. In addition to its well-established anti-resorptive effect on bone, calcitonin (CT) potentially exerts protective effects on IVD degeneration in ovariectomized rats. However, possible therapeutic effects of CT on lumbar fusion-induced adjacent-segment disc degeneration (ASDD) have not been investigated yet. In this study, we examined the effects of CT on IVD degeneration adjacent to a lumbar fusion in ovariectomized rats.

Methods

Posterolateral lumbar fusion (PLF) at L4–5 was performed 4 weeks after ovariectomy (OVX) or sham surgery in female Sprague–Dawley rats. Following PLF + OVX, rats received either salmon CT (OVX + PLF + sCT, 16 IU/Kg/2d) or vehicle (OVX + PLF + V) treatment for 12 weeks; the remaining rats were divided into Sham + V, OVX + V, and PLF + V groups. Fusion status was analyzed by manual palpation and radiography. Adjacent segment disc was assessed by histological, histomorphometric, immunohistochemical analysis. L6 vertebrae microstructures were evaluated by micro-computed tomography.

Results

Histological analysis showed more severe ASDD occurred in OVX + PLF + V rats compared with the OVX + V or PLF + V groups. CT treatment suppressed the score for ASDD, increased disc height, and decreased the area of endplate calcification. Immunohistochemical staining demonstrated that CT decreased the expression of collagen type-I, matrix metalloproteinase-13, and a disintegrin and metalloproteinase with thrombospondin motifs-4, whereas it increased the expression of collagen type-II and aggrecan in the disc. Micro-computed tomography indicated that CT increased bone mass and improved the microstructure of the L6 vertebrae.

Conclusions

These results suggest that CT can prevent ASDD, induce beneficial changes in IVD metabolism, and inhibit deterioration of the trabecular microarchitecture of vertebrae in osteoporotic rats with lumbar fusion.

Burden of disease of reoperations in instrumental spinal surgeries in Germany

PURPOSE

To estimate the incidence of instrumental spinal surgeries (ISS) and consecutive reoperations and to calculate the related resource utilization and costs.

METHODS

ISS and subsequent reoperations were identified retrospectively using surgery codes in claims data. The study period included January 01, 2009 to December 31, 2011. The reoperation rate was calculated for 1 year after the primary ISS. Resource utilization and costs were analyzed by group comparison.

RESULTS

A total of 3316 incident ISS patients were identified in 2010 with an annual reoperation rate of 9.98% (95% CI 8.98-11.02%). Mean costs per patient were €11,331 per ISS and €11,370 per reoperation, with €8432 directly attributed to the reoperation and €2938 to additional resources.

CONCLUSIONS

Costs of ISS and subsequent reoperations have a significant impact on health insurances budgets. The annual cost of reoperations exceeds the direct cost of the primary surgery driven by the need for further inpatient and outpatient care.

Therapeutic sustainability and durability of coflex interlaminar stabilization after decompression for lumbar spinal stenosis: a four year assessment

BACKGROUND

Approved treatment modalities for the surgical management of lumbar spinal stenosis encompass a variety of direct and indirect methods of decompression, though all have varying degrees of limitations and morbidity which potentially limit the efficacy and durability of the treatment. The coflex(®) interlaminar stabilization implant (Paradigm Spine, New York, NY), examined under a United States Food and Drug Administration (US FDA) Investigational Device Exemption (IDE) clinical trial, is shown to have durable outcomes when compared to posterolateral fusion in the setting of post-decompression stabilization for stenotic patients. Other clinical and radiographic parameters, more indicative of durability, were also evaluated. The data collected from these parameters were used to expand the FDA composite clinical success (CCS) endpoint; thus, creating a more stringent Therapeutic Sustainability Endpoint (TSE). The TSE allows more precise calculation of the durability of interlaminar stabilization (ILS) when compared to the fusion control group.

METHODS

A retrospective analysis of data generated from a prospective, randomized, level-1 trial that was conducted at 21 US sites was carried out. Three hundred forty-four per-protocol subjects were enrolled and randomized to ILS or fusion after decompression for lumbar stenosis with up to grade 1 degenerative spondylolisthesis. Clinical, safety, and radiographic data were collected and analyzed in both groups. Four-year outcomes were assessed, and the TSE was calculated for both cohorts. The clinical and radiographic factors thought to be associated with therapeutic sustainability were added to the CCS endpoints which were used for premarket approval (PMA).

RESULTS

Success rate, comprised of no second intervention and an ODI improvement of ≥ 15 points, was 57.6% of ILS and 46.7% of fusion patients (p = 0.095). Adding lack of fusion in the ILS cohort and successful fusion in the fusion cohort showed a CCS of 42.7% and 33.3%, respectively. Finally, adding adjacent level success to both cohorts and maintenance of foraminal height in the coflex cohort showed a CCS of 36.6% and 25.6%, respectively. With additional follow-up to five years in the U.S. PMA study, these trends are expected to continue to show the superior therapeutic sustainability of ILS compared to posterolateral fusion after decompression for spinal stenosis.

CONCLUSION

There are clear differences in both therapeutic sustainability and intended clinical effect of ILS compared to posterolateral fusion with pedicle screw fixation after decompression for spinal stenosis. There are CCS differences between coflex and fusion cohorts noted at four years post-op similar to the trends revealed in the two year data used for PMA approval. When therapeutic sustainability outcomes are added to the CCS, ILS is proven to be a sustainable treatment for stabilization of the vertebral motion segment after decompression for lumbar spinal stenosis.

The impact of generalized joint laxity on the clinical and radiological outcomes of single-level posterior lumbar interbody fusion

BACKGROUND CONTEXT

Recent reports have suggested that excessive motion of the lumbar spine might be associated with low back pain and accelerated disc degeneration and may negatively influence the outcome of posterior lumbar interbody fusion (PLIF) surgery. These findings suggest that generalized joint laxity (GJL) might be a negative factor affecting PLIF outcome, although this relationship has not been well studied. In addition, the impact of GJL on adjacent segment pathology (ASP) after PLIF has not been reported.

PURPOSE

To explore the relationship between GJL and the outcome of single-level PLIF, we compared fusion rates, clinical outcomes, and ASP in PLIF patients with and without GJL.

STUDY DESIGN

Retrospective comparative study.

PATIENT SAMPLE

A total of 256 patients who underwent PLIF and were followed for at least 2 years after surgery were classified into two groups: Group A (37 patients with GJL) and Group B (219 patients without GJL).

OUTCOME MEASURES

The primary outcome measure was the fusion rate on dynamic radiographs and computed tomography scans. The secondary outcome measures were pain intensity in the low back based on a visual analog scale, functional outcome based on the Oswestry Disability Index, and prevalence and severity of ASP on lumbar spine magnetic resonance imaging 2 years postoperatively compared with preoperative images.

METHODS

We compared baseline data for the two groups studied. To evaluate the effects of GJL on the outcome of PLIF, we also compared outcome measures between the two groups. No funds were received in support of this work.

RESULTS

Successful fusion 2 years after surgery was achieved in 91.9% of patients in Group A and 91.8% of patients in Group B according to dynamic radiographs (p=.85) and in 86.5% of patients in Group A and 90% of patients in Group B according to computed tomography scans (p=.14). Secondary endpoints including pain intensity (visual analog scale) and Oswestry Disability Index scores were not significantly different between the two groups (p=.71 and .86, respectively). Adjacent segment pathology was present in both the superior and inferior adjacent segments in both groups and was not significantly different (p=.07 and .06, respectively), although severe degeneration that was greater than Grade III on modified Pfirrmann classification was more frequently observed in Group A (15 of 37, 40.5%, at the superior segment and 11 of 20, 55%, at the inferior segment) than in Group B (60 of 219, 27.4%, at the superior segment and 30 of 111, 27%, at the inferior segment), which was statistically significant (p=.02 and .01, respectively). Moreover, ASP was more prominent at the superior adjacent segment compared with the inferior adjacent segment and was most commonly observed at the inferior adjacent segment (L5-S1) after L4-L5 PLIF and the superior adjacent segment (L4-L5) after L5-S1 PLIF (p=.02 and .03, respectively).

CONCLUSIONS

Generalized joint laxity at baseline does not impact fusion rate or clinical outcome with respect to pain intensity or functional status but could negatively impact ASP compared with that in patients without GJL. Consequently, GJL should be evaluated preoperatively, and patients with GJL undergoing PLIF should be informed of the potential risks of surgery.

Minimally invasive decompression versus open laminectomy for central stenosis of the lumbar spine: pragmatic comparative effectiveness study

OBJECTIVE

To test the equivalence for clinical effectiveness between microdecompression and laminectomy in patients with central lumbar spinal stenosis.

DESIGN

Multicentre observational study.

SETTING

Prospective data from the Norwegian Registry for Spine Surgery.

PARTICIPANTS

885 patients with central stenosis of the lumbar spine who underwent surgery at 34 Norwegian orthopaedic or neurosurgical departments. Patients were treated from October 2006 to December 2011.

INTERVENTIONS

Laminectomy and microdecompression.

MAIN OUTCOME MEASURES

The primary outcome was change in Oswestry disability index score one year after surgery. Secondary endpoints were quality of life (EuroQol EQ-5D), perioperative complications, and duration of surgical procedures and hospital stays. A blinded biostatistician performed predefined statistical analyses in unmatched and propensity matched cohorts.

RESULTS

The study was powered to detect a difference between the groups of eight points on the Oswestry disability index at one year. 721 patients (81%) completed the one year follow-up. Equivalence between microdecompression and laminectomy was shown for the Oswestry disability index (difference 1.3 points, 95% confidence interval -1.36 to 3.92, P<0.001 for equivalence). Equivalence was confirmed in the propensity matched cohort and full information regression analyses. No difference was found between groups in quality of life (EQ-5D) one year after surgery. The number of patients with complications was higher in the laminectomy group (15.0% v 9.8%, P=0.018), but after propensity matching for complications the groups did not differ (P=0.23). The duration of surgery for single level decompression was shorter in the microdecompression group (difference 11.2 minutes, 95% confidence interval 4.9 to 17.5, P<0.001), but after propensity matching the groups did not differ (P=0.15). Patients in the microdecompression group had shorter hospital stays, both for single level decompression (difference 1.5 days, 95% confidence interval 1.7 to 2.6, P<0.001) and two level decompression (0.8 days, 1.0 to 2.2, P=0.003).

CONCLUSION

At one year the effectiveness of microdecompression is equivalent to laminectomy in the surgical treatment of central stenosis of the lumbar spine. Favourable outcomes were observed at one year in both treatment groups.Trial registration ClinicalTrials.gov NCT02006901.