Pain alleviation and functional improvement: ultra-early patient-reported outcome measures after full endoscopic spine surgery

J Neurosurg Spine 40:465–474, 2024

Questions regarding anticipated pain improvement and functional recovery postsurgery are frequently posed in preoperative consultations. However, a lack of data characterizing outcomes for the first postoperative days only allows for anecdotal answers. Hence, the assessment of ultra-early patient-reported outcome measures (PROMs) is essential for patient-provider communication and patient satisfaction. The aim of this study was to elucidate this research gap by assessing and characterizing PROMs for the first days after full endoscopic spine surgery (FESS).

METHODS This multicenter study included patients undergoing lumbar FESS from March 2021 to July 2023. After informed consent was provided, data were collected prospectively through a smartphone application. Patients underwent either discectomy or decompression. Analyzed parameters included demographics, surgical details, visual analog scale scores for both back and leg pain, and the Oswestry Disability Index (ODI) score. Data were acquired daily for the 1st postoperative week, as well as after 2 weeks, 3 months, and 6 months.

RESULTS A total of 182 patients were included, of whom 102 underwent FESS discectomy and 80 underwent FESS decompression. Significant differences between the discectomy and decompression groups were found for age (mean 50.45 ± 15.28 years and 63.85 ± 13.25 years, p < 0.001; respectively), sex (p = 0.007), and surgery duration (73.45 ± 45.23 minutes vs 98.05 ± 46.47 minutes, p < 0.001; respectively). Patients in both groups reported a significant amelioration of leg pain on the 1st postoperative day (discectomy group VAS score: 6.2 ± 2.6 vs 2.4 ± 2.9, p < 0.001; decompression group: 5.3 ± 2.8 vs 1.9 ± 2.2, p < 0.001) and of back pain within the 1st postoperative week (discectomy group VAS score: 5.5 ± 2.8 vs 2.8 ± 2.2, p < 0.001; decompression group: 5.2 ± 2.7 vs 3.1 ± 2.4, p < 0.001). ODI score improvement was most pronounced at the 3-month time point (discectomy group: 21.7 ± 9.1 vs 9.3 ± 9.1, p < 0.001; decompression group: 19.3 ± 7.8 vs 9.9 ± 8.3, p < 0.001). For both groups, pain improvement within the 1st week after surgery was highly predictive of later benefits.

CONCLUSIONS Ultra-early PROMs reveal an immediate pain improvement after FESS. While the benefits in pain reduction plateaued within the 1st postoperative week for both groups, functional improvements developed over a more extended period. These results illustrate a biphasic rehabilitation process wherein initial pain alleviation transitions into functional improvement over time.

Validation of age-adjusted pelvic incidence minus lumbar lordosis and lordosis distribution index for assessing adjacent-segment disease after short-level lumbar fusion surgery

J Neurosurg Spine 40:143–151, 2024

The purpose of this study was to investigate the influence of sagittal alignment according to age-adjusted pelvic incidence minus lumbar lordosis (PI-LL) and lordosis distribution index (LDI) on the occurrence of adjacent-segment disease (ASD) after lumbar fusion surgery.

METHODS This study retrospectively reviewed 234 consecutive patients with lumbar degenerative diseases who underwent 1- or 2-level lumbar fusion surgery. Demographic and radiographic (preoperative and 3-month postoperative) data were collected and compared between ASD and non-ASD groups. Binary logistic regression analysis was performed to evaluate adjusted associations between potential variables and ASD development. A subanalysis was further conducted to assess their relationships in the range of different PI values.

RESULTS With a mean follow-up duration of 70.6 months (range 60–121 months), 118 patients (50.4%) were diagnosed as having cranial radiological ASD. Univariate analyses showed that older age, 2-level fusion, worse preoperative pelvic tilt and LL, lower pre- and postoperative LDI, and more improvement in sagittal vertical axis were significantly correlated with the occurrence of ASD. No significant differences in the PI-LL and age-adjusted PI-LL (offset) were detected between ASD and non-ASD groups. Multivariate analysis identified postoperative LDI (OR 0.971, 95% CI 0.953–0.989, p = 0.002); 2-level fusion (OR 3.477, 95% CI 1.964–6.157, p < 0.001); and improvement of sagittal vertical axis (OR 0.992, 95% CI 0.985–0.998, p = 0.039) as the independent variables for predicting the occurrence of ASD. When stratified by PI, LDI was identified as an independent risk factor in the groups with low and average PI. Lower segmental lordosis (OR 0.841, 95% CI 0.742–0.954, p = 0.007) could significantly increase the incidence of ASD in the patients with high LDI.

CONCLUSIONS Age-adjusted PI-LL may have limited ability to predict the development of ASD. LDI could exert an important effect on diagnosing the occurrence of ASD in the cases with low and average PI, but segmental lordosis was a more significant risk factor than LDI in individuals with high PI.

Hospital cost differences between open and endoscopic lumbar spine decompression surgery

J Neurosurg Spine 40:77–83, 2024

In recent years, fully endoscopic decompression surgery for degenerative spine disease has become increasingly popular in the US. Although an endoscopic approach has demonstrated some benefits compared with open procedures in randomized controlled trials, the cost of advanced technologies remains contested. The authors evaluated the differences in costs and cost drivers between open and endoscopic decompression surgical procedures performed at a single institution.

METHODS Using associated Current Procedural Terminology codes, the authors identified all open and endoscopic decompression lumbar surgical procedures performed from January 1, 2016, through December 31, 2022. Preoperative comorbidities, surgical characteristics, and postoperative outcomes were captured. The costs of index surgery–related readmission for revision, washout, or other complications were included in the index surgery expenses. Associated inhospital costs were collected; these were reported in comparative percentages with open surgical procedures as the baseline because of an institutional agreement. Univariate and multivariate analyses were performed.

RESULTS The retrospective search identified 633 open surgical procedures and 195 endoscopic surgical procedures for inclusion. The two patient cohorts were similar, with clinically nonrelevant but statistically significant differences in mean age (open 55.7 years vs endoscopic 59.4 years, p = 0.01) and mean American Society of Anesthesiologists physical status class (open 2.3 vs endoscopic 2.4, p = 0.03). Postoperatively, patients who underwent open surgical procedures had significantly longer mean hospital stays (open 1.4 days vs endoscopic 0.7, p < 0.01) and more perioperative complications (open 7.9% of patients vs endoscopic 3.1%, p = 0.02), and they required washout surgical procedures in some cases (open 1.3% vs endoscopic 0%, p = 0.12). The largest cost difference between open and endoscopic surgical procedures was the significantly greater cost of disposable supplies for endoscopic cases (10.1% vs 31.7% of the total cost of open procedures, p < 0.01), and open surgical procedures were generally less costly in total (100.0% vs 115.1%, p < 0.01). In multivariate linear regression, endoscopic surgery was independently associated with greater total costs (standardized beta 15.9%, p < 0.01), although length of hospital stay (standardized beta 34.0%) and readmissions (standardized beta 30.0%, p < 0.01) had larger effects on cost.

CONCLUSIONS The endoscopic approach was associated with greater total in-hospital costs compared with open procedures. The findings of further cost evaluations, including those of patient-reported outcomes, social cost, and capital costs per procedure type, need to be included in operational and clinical decisions.

Anatomical study of the thoracolumbar radiculomedullary arteries, including the Adamkiewicz artery and supporting radiculomedullary arteries

J Neurosurg Spine 38:233–241, 2023

OBJECTIVE The aim of this paper was to identify and characterize all the segmental radiculomedullary arteries (RMAs) that supply the thoracic and lumbar spinal cord.

METHODS All RMAs from T4 to L5 were studied systematically in 25 cadaveric specimens. The RMA with the greatest diameter in each specimen was termed the artery of Adamkiewicz (AKA). Other supporting RMAs were also identified and characterized.

RESULTS A total of 27 AKAs were found in 25 specimens. Twenty-two AKAs (81%) originated from a left thoracic or a left lumbar radicular branch, and 5 (19%) arose from the right. Two specimens (8%) had two AKAs each: one specimen with two AKAs on the left side and the other specimen with one AKA on each side. Eight cadaveric specimens (32%) had 10 additional RMAs; among those, a single additional RMA was found in 6 specimens (75%), and 2 additional RMAs were found in each of the remaining 2 specimens (25%). Of those specimens with a single additional RMA, the supporting RMA was ipsilateral to the AKA in 5 specimens (83%) and contralateral in only 1 specimen (17%). The specimens containing 2 additional RMAs were all (100%) ipsilateral to their respective AKAs.

CONCLUSIONS The segmental RMAs supplying the thoracic and lumbar spinal cord can be unilateral, bilateral, or multiple. Multiple AKAs or additional RMAs supplying a single anterior spinal artery are common and should be considered when dealing with the spinal cord at the thoracolumbar level.

Artificial disc replacement and adjacent-segment pathology: 10-year outcomes of a randomized trial

J Neurosurg Spine 36:945–953, 2022

Artificial disc replacement (ADR) is designed to preserve motion and thus protect against adjacent segment pathology (ASP) and act as an alternative treatment to fusion surgery. The question remains, how well do ADR devices perform after 10 years of follow-up compared with fusion surgery in terms of patient satisfaction, sustainability, and protection against ASP?

METHODS This was the 10-year follow-up study of 153 participants who underwent ADR or fusion surgery after anterior decompression due to cervical degenerative radiculopathy (ISRCTN registration no. 44347115). Scores on the Neck Disability Index (NDI), EQ-5D, and visual analog scale for neck and arm pain were obtained from the Swedish Spine Registry and analyzed using ANCOVA. Information about secondary surgical procedures was collected from medical records and presented as Kaplan-Meier curves. MRI and flexion-extension radiography were performed, and ASP was
graded according to the Miyazaki classification system.

RESULTS Ten participants were lost to follow-up, which left 143 participants (80 underwent ADR and 65 underwent anterior cervical discectomy and fusion). There were no differences between groups in terms of patient-reported outcome measures (10-year difference in NDI scores 1.7 points, 95% CI −5.1 to 8.5, p = 0.61). Nineteen (24%) participants in the ADR group compared with 9 (14%) in the fusion group underwent secondary surgical procedures. The higher reoperation rate of the ADR group was mainly due to 11 female participants with device loosening. The rates of reoperation due
to ASP were similar between groups, which was confirmed with MRI assessment of ASP that also showed no differences between the groups (p = 0.21).
CONCLUSIONS This was the first 10-year follow-up study to compare ADR with fusion surgery and to provide MRI information for the assessment of ASP. The authors found no benefit of ADR over fusion surgery after anterior  decompression for cervical degenerative radiculopathy.

 

Minimally invasive versus open lumbar spinal fusion: a matched study investigating patient-reported and surgical outcomes

J Neurosurg Spine 36:753–766, 2022

With the expanding indications for and increasing popularity of minimally invasive surgery (MIS) for lumbar spinal fusion, large-scale outcomes analysis to compare MIS approaches with open procedures is warranted.

METHODS The authors queried the Quality Outcomes Database for patients who underwent elective lumbar fusion for degenerative spine disease. They performed optimal matching, at a 1:2 ratio between patients who underwent MIS and those who underwent open lumbar fusion, to create two highly homogeneous groups in terms of 33 baseline variables (including demographic characteristics, comorbidities, symptoms, patient-reported scores, indications, and operative details). The outcomes of interest were overall satisfaction, decrease in Oswestry Disability Index (ODI), and back and leg pain, as well as hospital length of stay (LOS), operative time, reoperations, and incidental durotomy rate. Satisfaction was defined as a score of 1 or 2 on the North American Spine Society scale. Minimal clinically important difference (MCID) in ODI was defined as ≥ 30% decrease from baseline. Outcomes were assessed at the 3- and 12-month follow-up evaluations.

RESULTS After the groups were matched, the MIS and open groups consisted of 1483 and 2966 patients, respectively. Patients who underwent MIS fusion had higher odds of satisfaction at 3 months (OR 1.4, p = 0.004); no difference was demonstrated at 12 months (OR 1.04, p = 0.67). Lumbar stenosis, single-level fusion, higher American Society of Anesthesiologists Physical Status Classification System grade, and absence of spondylolisthesis were most prominently associated with higher odds of satisfaction with MIS compared with open surgery. Patients in the MIS group had slightly lower ODI scores at 3 months (mean difference 1.61, p = 0.006; MCID OR 1.14, p = 0.0495) and 12 months (mean difference 2.35, p < 0.001; MCID OR 1.29, p < 0.001). MIS was also associated with a greater decrease in leg and back pain at both follow-up time points. The two groups did not differ in operative time and incidental durotomy rate; however, LOS was shorter for the MIS group. Revision surgery at 12 months was less likely for patients who underwent MIS (4.1% vs 5.6%, p = 0.032).

CONCLUSIONS In patients who underwent lumbar fusion for degenerative spinal disease, MIS was associated with higher odds of satisfaction at 3 months postoperatively. No difference was demonstrated at the 12-month follow-up. MIS maintained a small, yet consistent, superiority in decreasing ODI and back and leg pain, and MIS was associated with a lower reoperation rate.

Decompression alone versus decompression and instrumented fusion for the treatment of isthmic spondylolisthesis: a randomized controlled trial

J Neurosurg Spine 35:687–697, 2021

The most advocated surgical technique to treat symptoms of isthmic spondylolisthesis is decompression with instrumented fusion. A less-invasive classical approach has also been reported, which consists of decompression only. In this study the authors compared the clinical outcomes of decompression only with those of decompression with instrumented fusion in patients with isthmic spondylolisthesis.

METHODS Eighty-four patients with lumbar radiculopathy or neurogenic claudication secondary to low-grade isthmic spondylolisthesis were randomly assigned to decompression only (n = 43) or decompression with instrumented fusion (n = 41). Primary outcome parameters were scores on the Roland Disability Questionnaire (RDQ), separate visual analog scales (VASs) for back pain and leg pain, and patient report of perceived recovery at 12-week and 2-year follow-ups. The proportion of reoperations was scored as a secondary outcome measure. Repeated measures ANOVA according to the intention-to-treat principle was performed.

RESULTS Decompression alone did not show superiority in terms of disability scores at 12-week follow-up (p = 0.32, 95% CI −4.02 to 1.34), nor in any other outcome measure. At 2-year follow-up, RDQ disability scores improved more in the fusion group (10.3, 95% CI 3.9–8.2, vs 6.0, 95% CI 8.2–12.4; p = 0.006, 95% CI −7.3 to −1.3). Likewise, back pain decreased more in the fusion group (difference: −18.3 mm, CI −32.1 to −4.4, p = 0.01) on a 100-mm VAS scale, and a higher proportion of patients perceived recovery as showing “good results” (44% vs 74%, p = 0.01). Cumulative probabilities for reoperation were 47% in the decompression and 13% in the fusion group (p < 0.001) at the 2-year follow-up.

CONCLUSIONS In patients with isthmic spondylolisthesis, decompression with instrumented fusion resulted in comparable short-term results, significantly better long-term outcomes, and fewer reoperations than decompression alone. Decompression with instrumented fusion is a superior surgical technique that should in general be offered as a first treatment option for isthmic spondylolisthesis, but not for degenerative spondylolisthesis, which has a different etiology. Clinical trial registration number: NTR1300 (Netherlands Trial Register)

Surgery for Degenerative Cervical Myelopathy: A Nationwide Registry-Based Observational Study With Patient-Reported Outcomes

Neurosurgery 89:704–711, 2021

Indications and optimal timing for surgical treatment of degenerative cervical myelopathy (DCM) remain unclear, and data from daily clinical practice are warranted.

OBJECTIVE: To investigate clinical outcomes following decompressive surgery for DCM.

METHODS: Data were obtained from the Norwegian Registry for Spine Surgery. The primary outcome was change in the neck disability index (NDI) 1 yr after surgery. Secondary endpoints were the European myelopathy score (EMS), quality of life (EuroQoL 5D [EQ- 5D]), numeric rating scales (NRS) for headache, neck pain, and arm pain, complications, and perceived benefit of surgery assessed by the Global Perceived Effect (GPE) scale.

RESULTS: We included 905 patients operated between January 2012 and June 2018. There were significant improvements in all patient-reported outcome measures (PROMs) including NDI (mean −10.0, 95% CI −11.5 to −8.4, P < .001), EMS (mean 1.0, 95% CI 0.8-1.1, P < .001), EQ-5D index score (mean 0.16, 95% CI 0.13-0.19, P < .001), EQ-5D visual analogue scale (mean 13.8, 95% CI 11.7-15.9, P < .001), headache NRS (mean −1.1, 95% CI −1.4 to −0.8, P < .001), neck pain NRS (mean −1.8, 95% CI −2.0 to −1.5, P < .001), and arm pain NRS (mean −1.7, 95% CI −1.9 to −1.4, P < .001). According to GPE scale assessments, 229/513 patients (44.6%) experienced “complete recovery” or felt “much better” at 1 yr. There were signif- icant improvements in all PROMs for both mild and moderate-to-severe DCM. A total of 251 patients (27.7%) experienced adverse effects within 3 mo.

CONCLUSION: Surgery for DCM is associated with significant and clinically meaningful improvement across a wide range of PROMs.

Is the Goutallier grade of multifidus fat infiltration associated with adjacent-segment degeneration after lumbar spinal fusion?

J Neurosurg Spine 34:190–195, 2021

The aim of this study was to investigate whether fat infiltration of the lumbar multifidus (LM) muscle affects revision surgery rates for adjacent-segment degeneration (ASD) after L4–5 transforaminal lumbar interbody fusion (TLIF) for degenerative spondylolisthesis.

METHODS A total of 178 patients undergoing single-level L4–5 TLIF for spondylolisthesis (2006 to 2016) were retrospectively analyzed. Inclusion criteria were a minimum 2-year follow-up, preoperative MR images and radiographs, and single-level L4–5 TLIF for degenerative spondylolisthesis. Twenty-three patients underwent revision surgery for ASD during the follow-up. Another 23 patients without ASD were matched with the patients with ASD. Demographic data, Roussouly curvature type, and spinopelvic parameter data were collected. The fat infiltration of the LM muscle (L3, L4, and L5) was evaluated on preoperative MRI using the Goutallier classification system.

RESULTS A total of 46 patients were evaluated. There were no differences in age, sex, BMI, or spinopelvic parameters with regard to patients with and those without ASD (p > 0.05). Fat infiltration of the LM was significantly greater in the patients with ASD than in those without ASD (p = 0.029). Fat infiltration was most significant at L3 in patients with ASD than in patients without ASD (p = 0.017). At L4 and L5, there was an increasing trend of fat infiltration in the patients with ASD than in those without ASD, but the difference was not statistically significant (p = 0.354 for L4 and p = 0.077 for L5).

CONCLUSIONS Fat infiltration of the LM may be associated with ASD after L4–5 TLIF for spondylolisthesis. Fat infiltration at L3 may also be associated with ASD at L3–4 after L4–5 TLIF.

Topping-off technique for stabilization of lumbar degenerative instabilities in 322 patients

J Neurosurg Spine 32:366–372, 2020

Semi-rigid instrumentation (SRI) was introduced to take advantage of the concept of load sharing in surgery for spinal stabilization. The authors investigated a topping-off technique in which interbody fusion is not performed in the uppermost motion segment, thus creating a smooth transition from stabilized to free motion segments. SRI using the topping-off technique also reduces the motion of the adjacent segments, which may reduce the risk of adjacent segment disease (ASD), a frequently observed sequela of instrumentation and fusion, but this technique may also increase the possibility of screw loosening (SL). In the present study the authors aimed to systematically evaluate reoperation rates, clinical outcomes, and potential risk factors and incidences of ASD and SL for this novel approach.

METHODS The authors collected data for the first 322 patients enrolled at their institution from 2009 to 2015 who underwent surgery performed using the topping-off technique. Reoperation rates, patient satisfaction, and other outcome measures were evaluated. All patients underwent pedicle screw–based semi-rigid stabilization of the lumbar spine with a polyetheretherketone (PEEK) rod system.

RESULTS Implantation of PEEK rods during revision surgery was performed in 59.9% of patients. A median of 3 motion segments (range 1–5 segments) were included and a median of 2 motion segments (range 0–4 segments) were fused. A total of 89.4% of patients underwent fusion, 73.3% by transforaminal lumbar interbody fusion (TLIF), 18.4% by anterior lumbar interbody fusion (ALIF), 3.1% by extreme lateral interbody fusion (XLIF), 0.3% by oblique lumbar interbody fusion (OLIF), and 4.9% by combined approaches in the same surgery. Combined radicular and lumbar pain according to a visual analog scale was reduced from 7.9 ± 1.0 to 4.0 ± 3.1, with 56.2% of patients indicating benefit from surgery. After maximum follow-up (4.3 ± 1.8 years), the reoperation rate was 16.4%.

CONCLUSIONS The PEEK rod concept including the topping-off principle seems safe, with at least average patient satisfaction in this patient group. Considering the low rate of first-tier surgeries, the presented results seem at least comparable to those of most other series. Follow-up studies are needed to determine long-term outcomes, particularly with respect to ASD, which might be reduced by the presented approach.

Posterior foraminotomy versus anterior decompression and fusion in patients with cervical degenerative disc disease with radiculopathy

J Neurosurg Spine 32:344–352, 2020

The long-term efficacy of posterior foraminotomy compared with anterior cervical decompression and fusion (ACDF) for the treatment of degenerative disc disease with radiculopathy has not been previously investigated in a population-based cohort.

METHODS All patients in the national Swedish Spine Register (Swespine) from January 1, 2006, until November 15, 2017, with cervical degenerative disc disease and radiculopathy were assessed. Using propensity score matching, patients treated with posterior foraminotomy were compared with those undergoing ACDF. The primary outcome measure was the Neck Disability Index (NDI), a patient-reported outcome score ranging from 0% to 100%, with higher scores indicating greater disability. A minimal clinically important difference was defined as > 15%. Secondary outcomes were assessed with additional patient-reported outcome measures (PROMs).

RESULTS A total of 4368 patients (2136/2232 women/men) met the inclusion criteria. Posterior foraminotomy was performed in 647 patients, and 3721 patients underwent ACDF. After meticulous propensity score matching, 570 patients with a mean age of 54 years remained in each group. Both groups had substantial decreases in their NDI scores; however, after 5 years, the difference was not significant (2.3%, 95% CI −4.1% to 8.4%; p = 0.48) between the groups. There were no significant differences between the groups in EQ-5D or visual analog scale (VAS) for neck and arm scores. The secondary surgeries on the index level due to restenosis were more frequent in the foraminotomy group (6/100 patients vs 1/100), but on the adjacent segments there was no difference between groups (2/100).

CONCLUSIONS In patients with cervical degenerative disc disease and radiculopathy, both groups demonstrated clinical improvements at the 5-year follow-up that were comparable and did not achieve a clinically important difference from one another, even though the reoperation rate favored the ACDF group. This study design obtains population-based results, which are generalizable.

Artificial disc replacement versus fusion in patients with cervical degenerative disc disease with radiculopathy: 5-year outcomes from the National Swedish Spine Register

J Neurosurg Spine 30:159–167, 2019

The long-term efficacy of artificial disc replacement (ADR) surgery compared with fusion after decompression for the treatment of cervical degenerative disc disease and radiculopathy has not previously been investigated in a population-based setting.

METHODS All patients with cervical degenerative disc disease and radiculopathy who were in the national Swedish Spine Registry (Swespine) beginning in January 1, 2006, were eligible for the study. Follow-up information was obtained up to November 15, 2017. The authors compared, using propensity score matching, patients treated with anterior decompression and insertion of an ADR with patients who underwent anterior decompression combined with fusion surgery.
The primary outcome was the Neck Disability Index (NDI), a patient-reported function score ranging from 0% to 100%, with higher scores indicating greater disability and a minimum clinically important difference of > 15%.

RESULTS A total of 3998 patients (2018:1980 women/men) met the inclusion criteria, of whom 204 had undergone arthroplasty and 3794 had undergone fusion. After propensity score matching, 185 patients with a mean age of 49.7 years remained in each group. Scores on the NDI were approximately halved in both groups after 5 years, but without a significant mean difference in NDI (3.0%; 95% CI -8.4 to 2.4; p = 0.28) between the groups. There were no differences between the groups in EuroQol–5 Dimensions or in pain scores for the neck and arm.

CONCLUSIONS In patients with cervical degenerative disc disease and radiculopathy, decompression plus ADR surgery did not result in a clinically important difference in outcomes after 5 years, compared with decompression and fusion surgery.

Radiological adjacent-segment degeneration in L4–5 spondylolisthesis: comparison between dynamic stabilization and minimally invasive transforaminal lumbar interbody fusion

J Neurosurg Spine 29:250–258, 2018

Pedicle screw–based dynamic stabilization has been an alternative to conventional lumbar fusion for the surgical management of low-grade spondylolisthesis. However, the true effect of dynamic stabilization on adjacent segment degeneration (ASD) remains undetermined. Authors of this study aimed to investigate the incidence of ASD and to compare the clinical outcomes of dynamic stabilization and minimally invasive transforaminal lumbar interbody fusion (MI-TLIF).

METHODS The records of consecutive patients with Meyerding grade I degenerative spondylolisthesis who had undergone surgical management at L4–5 in the period from 2007 to 2014 were retrospectively reviewed. Patients were divided into two groups according to the surgery performed: Dynesys dynamic stabilization (DDS) group and MI-TLIF group. Pre- and postoperative radiological evaluations, including radiography, CT, and MRI studies, were compared. Adjacent discs were evaluated using 4 radiological parameters: instability (antero- or retrolisthesis), disc degeneration (Pfirrmann classification), endplate degeneration (Modic classification), and range of motion (ROM). Clinical outcomes, measured with the visual analog scale (VAS) for back and leg pain, the Oswestry Disability Index (ODI), and the Japanese Orthopaedic Association (JOA) scores, were also compared.

RESULTS A total of 79 patients with L4–5 degenerative spondylolisthesis were included in the analysis. During a mean follow-up of 35.2 months (range 24–89 months), there were 56 patients in the DDS group and 23 in the MI-TLIF group. Prior to surgery, both groups were very similar in demographic, radiological, and clinical data. Postoperation, both groups had similarly significant improvement in clinical outcomes (VAS, ODI, and JOA scores) at each time point of evaluation. There was a lower chance of disc degeneration (Pfirrmann classification) of the adjacent discs in the DDS group than in the MI-TLIF group (17% vs 37%, p = 0.01). However, the DDS and MI-TLIF groups had similar rates of instability (15.2% vs 17.4%, respectively, p = 0.92) and endplate degeneration (1.8% vs 6.5%, p = 0.30) at the cranial (L3–4) and caudal (L5–S1) adjacent levels after surgery. The mean ROM in the cranial and caudal levels was also similar in the two groups. None of the patients required secondary surgery for any ASD (defined by radiological criteria).

CONCLUSIONS The clinical improvements after DDS were similar to those following MI-TLIF for L4–5 Meyerding grade I degenerative spondylolisthesis at 3 years postoperation. According to radiological evaluations, there was a lower chance of disc degeneration in the adjacent levels of the patients who had undergone DDS. However, other radiological signs of ASD, including instability, endplate degeneration, and ROM, were similar between the two groups. Although none of the patients in the present series required secondary surgery, a longer follow-up and a larger number of patients would be necessary to corroborate the protective effect of DDS against ASD.

Does MIS Surgery Allow for Shorter Constructs in the Surgical Treatment of Adult Spinal Deformity?

Neurosurgery 80:489–497, 2017

The length of construct can potentially influence perioperative risks in adult spinal deformity (ASD) surgery. A head-to-head comparison between open and minimally invasive surgery (MIS) techniques for treatment of ASD has yet to be performed.

OBJECTIVE: To examine the impact of MIS approaches on construct length and clinical outcomes in comparison to traditional open approaches when treating similar ASD profiles.

METHODS: Two multicenter databases for ASD, 1 involving MIS procedures and the other open procedures, were propensity matched for clinical and radiographic parameters in this observational study. Inclusion criteria were ASD and minimum 2-year follow-up. Independent t-test and chi-square test were used to evaluate and compare outcomes.

RESULTS: A total of 1215 patients were identified, with 84 patients matched in each group. Statistical significance was found for mean levels fused (4.8 for circumferential MIS [cMIS] and 10.1 for open), mean interbody fusion levels (3.6 cMIS and 2.4 open), blood loss (estimated blood loss 488 mL cMIS and 1762 mL open), and hospital length of stay (6.7 days cMIS and 9.7 days open). There was no significant difference in preoperative radiographic parameters or postoperative clinical outcomes (Owestry Disability Index and visual analog scale) between groups. There was a significant difference in postoperative lumbar lordosis (43.3◦ cMIS and 49.8◦ open) and pelvic incidence-lumbar lordosis correction (10.6◦ cMIS and 5.2◦ open) in the open group. There was no significant difference in reoperation rate between the 2 groups.

CONCLUSION: MIS techniques for ASD may reduce construct length, reoperation rates, blood loss, and length of stay without affecting clinical and radiographic outcomes when compared to a similar group of patients treated with open techniques.

Minimally invasive lateral fusion for adjacent disease

Minimally invasive lateral interbody fusion for the treatment of rostral adjacent-segment lumbar degenerative stenosis without supplemental pedicle screw fixation

J Neurosurg Spine 21:861–866, 2014

Adjacent-segment degeneration and stenosis are common in patients who have undergone previous lumbar fusion. Treatment typically involves a revision posterior approach, which requires management of postoperative scar tissue and previously implanted instrumentation. A minimally invasive lateral approach allows the surgeon to potentially reduce the risk of these hazards. The technique relies on indirect decompression to treat central and foraminal stenosis and placement of a graft with a large surface area to promote robust fusion and stability in concert with the surrounding tensioned ligaments. The goal in this study was to determine if lateral interbody fusion without supplemental pedicle screws is effective in treating adjacent-segment disease.

Methods. For a 30-month study period at two institutions, the authors obtained all cases of lumbar fusion with new back and leg pain due to adjacent-segment stenosis and spondylosis failing conservative measures. All patients had undergone minimally invasive lateral interbody fusion from the side of greater leg pain without supplemental pedicle screw fixation. Patients were excluded from the study if they had undergone surgery for a nondegenerative etiology such as infection or trauma. They were also excluded if the intervention involved supplemental posterior instrumented fusion with transpedicular screws. Postoperative metrics included numeric pain scale (NPS) scores for leg and back pain. All patients underwent dynamic radiographs and CT scanning to assess stability and fusion after surgery.

Results. During the 30-month study period, 21 patients (43% female) were successfully treated using minimally invasive lateral interbody fusion without the need for subsequent posterior transpedicular fixation. The mean patient age was 61 years (range 37–87 years). Four patients had two adjacent levels fused, while the remainder had single-level surgery. All patients underwent surgery without conversion to a traditional open technique, and recombinant human bone morphogenetic protein–2 was used in the interbody space in all cases. The mean follow-up was 23.6 months. The mean operative time was 86 minutes, and the mean blood loss was 93 ml. There were no major intraoperative complications, but one patient underwent subsequent direct decompression in a delayed fashion. The leg pain NPS score improved from a mean of 6.3 to 1.9 (p < 0.01), and the back pain NPS score improved from a mean of 7.5 to 2.9 (p < 0.01). Intervertebral settling averaged 1.7 mm. All patients had bridging bone on CT scanning at the last follow-up, indicating solid bony fusion.

Conclusions. Adjacent-segment stenosis and spondylosis can be treated with a number of different operative techniques. Lateral interbody fusion provides an attractive alternative with reduced blood loss and complications, as there is no need to re-explore a previous laminectomy site. In this limited series a minimally invasive lateral approach provided high fusion rates when performed with osteobiological adjuvants.