Minimally Invasive Patients Research Articles

P40. Reduced complications but no differences in readmissions with minimally invasive versus open posterior based lumbar interbody fusion, a national study

<h3>BACKGROUND CONTEXT</h3> In single and multi-institution studies, minimally invasive (MIS) posterior and transforaminal lumbar interbody fusion (LIF) has been associated with decreased blood loss, length of stay, costs and improved short term functional outcomes. No national studies exist directly comparing MIS to traditional open posterior-based lumbar interbody fusion procedures. <h3>PURPOSE</h3> We aim to analyze the utilization of anterior MIS-LIF procedures and compare complications, readmissions and reoperations to open-LIF procedures. <h3>STUDY DESIGN/SETTING</h3> Retrospective, administrative databases. <h3>PATIENT SAMPLE</h3> National Inpatient Sample (NIS), National Readmissions Database (NRD), 2016 to 2019. <h3>OUTCOME MEASURES</h3> Readmissions, reoperations, mortality, index hospitalization complications, costs, length of stay, discharge destination. <h3>METHODS</h3> The NIS and NRD databases were queried from 2016 to 2019 to identify patients undergoing posterior-based one- or two-level LIF with a diagnosis of degenerative disc disease, spondylosis, spondylolysis and spondylolisthesis. MIS was defined as procedures utilizing percutaneous or endoscopic approaches. Multivariate regression was used to assess factors associated with procedure type, cost, LOS and discharge destination. Propensity score matching was used to compare index hospital complications, readmission and reoperations at 30, 90 and 180-day intervals. <h3>RESULTS</h3> A total 382,395 posterior-based LIF were estimated to have occurred in the US between 2016 and 2019, with 4,260 (1.1%) of those utilizing MIS techniques. The proportion of MIS procedures did not change significantly over the study period (p=0.40). Two-level procedures were identified in 27.8% and 29.4% of cases for MIS and open procedures, respectively (p=0.32). On multivariate modeling, patients receiving care in the western census regions were significantly less likely to undergo an MIS procedure (OR 0.38, p < 0.0001) relative to the midwest region, while patients receiving care in a medium sized hospital were more likely to receive an MIS procedure relative to a large hospital (OR 1.34, p=0.0003). Patients with a history of coagulopathy, cardiac arrhythmia and fluid & electrolyte disorders were significantly less likely to undergo MIS procedures. MIS procedures were associated with a decreased LOS of 0.69 days (p < 0.0001) and decreased rate of nonhome discharge (OR 0.71, p=0.003). Cost did not differ by procedure type (p=0.35). On matched analysis, MIS patients had a lower rate of overall complications (10.7 vs 14.6%, p < 0.001), neurologic complications (2.8 vs 5.2%, p < 0.001) and blood transfusion (1.7 vs 4.6%, p<0.001). In analysis of 30-day outcomes, there were no differences with regard to all cause readmission (3.5 vs 3.3%, p=0.74), related readmission (1.0 vs 1.5%, p=0.085), readmission for a specific related indication, repeat LIF or mortality. At 90 days, there were no differences in all cause readmission (6.5 vs 6.3%, p=0.81), related readmission (1.7 vs 2.5%, p=0.064), readmission for a specific related indication, repeat LIF or mortality. Finally, at 180-day analysis, there were no differences in all cause readmission (10.1 vs 9.4%, p=0.50), related readmission (2.1 vs 3.1%, p=0.076), readmission for a specific related indication, repeat LIF or mortality. <h3>CONCLUSIONS</h3> Utilization of posterior-based MIS LIF remains low nationally, with 1.1% of procedures utilizing these techniques between 2016 to 2019. MIS is associated with reduced hospital costs, length of stay and blood transfusions compared to open approaches. Short-term rates of readmission and reoperation were similar between MIS and open LIF. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.

141. Comparative analysis of utilization of artificial intelligence in minimally invasive adult spinal deformity surgery

<h3>BACKGROUND CONTEXT</h3> Advancements in artificial intelligence (AI), machine learning, and minimally-invasive (MIS) technique may offer enhanced preoperative planning, intraoperative robotic or navigational guidance, and prediction of postoperative complications for adult spinal deformity patients. Despite relatively widespread utilization, few studies in the literature assess the clinical and radiographic impact of AI in MIS surgery. <h3>PURPOSE</h3> To assess the impact of artificial intelligence on peri- and postoperative course in minimally-invasive adult spinal deformity corrective surgery. <h3>STUDY DESIGN/SETTING</h3> Retrospective cohort review. <h3>PATIENT SAMPLE</h3> This study included 524 MIS patients. <h3>OUTCOME MEASURES</h3> Intra- and postoperative complication rates; reoperation rate; HRQLs <h3>METHODS</h3> Operative cervical deformity patients 18 years old with complete pre-(BL) and up to 2-year (2Y) postop radiographic/HRQL data were stratified by primary utilization AI-based patient-specific rod customization and robotic or navigational assistance in pre- and perioperative course (AI+) or not (AI-). Differences in demographics, clinical outcomes, radiographic alignment targets, perioperative factors and complication rates were assessed via means comparison analysis. Analysis of covariance (ANCOVA) assessed postoperative complications while controlling for BL age and gender. <h3>RESULTS</h3> A total of 133 MIS patients were included (51.74±11.59 years, 41% female, 30.85±6.93 kg/m²). Of these patients, 44 (33.1%) were classified as AI+. At baseline, patient groups were comparable in BL age, BMI and CCI (all p>.05), though AI+ patients were more likely to be male (p=.040). Patient groups were comparable in terms of both regional and global radiographic alignment, as well as HRQLs at BL (all p>.05). Surgically, AI+ patients had significantly shorter operative times overall (p=.022) and decreased EBL (p=.001), as well as decreased likelihood of undergoing corpectomy (p=.001). Furthermore, AI+ patients reported significantly lower hospital LOS vs AI- patients (p=.012). At 2 years postoperatively, AI+ patients with custom rods were noted to have significantly improved segmental alignment in terms of decreased pelvic tilt (S1PT) and pelvic incidence (S1PI) (both p <.001). Adjusted complications analysis revealed that AI+ patients were significantly less likely to experience any postoperative complication (p=.003), neurological complications (p=.021) or complication requiring reoperation (p=.003). <h3>CONCLUSIONS</h3> Artificial intelligence and machine learning technologies may provide a substantial benefit to patients undergoing minimally-invasive adult spinal deformity surgery. The findings in this study demonstrate that patients operated on using AI-based robotic or navigational guidance, as well as the utilization of customized instrumentation, may reduce intraoperative invasiveness, shorten hospital length of stay, and decrease complication rates. As such, surgeons should consider utilization of AI-based technology in practice. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.

220. An analysis of intraoperative neurophysiological monitoring events during single position minimally invasive spine surgery

<h3>BACKGROUND CONTEXT</h3> The single position minimally invasive (MIS) lateral approach allows access to the anterior and posterior columns with the patient positioned in the lateral decubitus position. The purpose of this approach was to mitigate complications associated with open procedures while achieving circumferential fusion. More recently, an alternative prone-lateral technique has been developed streamlining surgical access with potential advantages. The purpose of this study was to identify differences in intraoperative neurophysiological monitoring (IOM) event rates between single position lateral decubitus and prone-lateral patients during MIS spine surgery. <h3>PURPOSE</h3> To determine if lateral decubitus positioning will correlate with the occurrence of neurophysiological monitoring events during MIS spine surgery. <h3>STUDY DESIGN/SETTING</h3> Retrospective cohort. <h3>PATIENT SAMPLE</h3> A total of 524 MIS patients were included. <h3>OUTCOME MEASURES</h3> Intraoperative neurophysiological monitoring, lateral decubitus, prone lateral. <h3>METHODS</h3> MIS spine surgery patients with available surgical positioning and IOM data were included if they were in a single position. Patients were stratified into 2 groups based on operative positioning: lateral decubitus (Lat) and prone lateral (PL). IOM was performed using somatosensory evoked potentials (SSEPs) and electromyography (EMG) techniques. An abnormal event was defined as any confirmed loss of signal during the operative period in the anatomical distribution of the surgery. Means comparison tests and multivariable logistic regression analysis assessed differences between patient groups. <h3>RESULTS</h3> Of 524 patients eligible, 226 (43.1%) had available positioning and IOM data. Of these, 88 met inclusion criteria (52 Lat and 36 PL). The majority were male (49, 55.7%), mean age of 49.2 yrs and 2.0 levels fused and 18 (20.5%) undergoing an osteotomy. In total, 19 (21.6%) patients had an abnormal IOM event. There was a significant difference in abnormal IOM event rates for patients who were in Lat (31%) and PL (8%) positioning, p=0.012. Multivariable analysis adjusting for surgical invasiveness showed that PL patients were 76.8% less likely to experience an abnormal IOM event than Lat patients (OR .232 [CI .060-.905], p=.035). Of the Lat patients with an abnormal IOM, 6.3% had postoperative sensory loss in the saphenous nerve. <h3>CONCLUSIONS</h3> Lateral decubitus positioning appears to be independently associated with abnormal intraoperative neurophysiological monitoring events when compared to prone lateral positioning during MIS. This has the potential to help with risk stratification in the future when determining patients undergoing a single position procedure. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.

112. The effect of preoperative rehabilitation on minimally invasive spine surgery patient outcomes

<h3>BACKGROUND CONTEXT</h3> Minimally invasive (MIS) spine surgery techniques were developed to mitigate complications associated with open procedures while achieving functional outcomes. More recently, preoperative rehabilitation programs have been implemented to prepare patients for surgery and to promote patient health. The purpose of this study was to identify the effect of preoperative rehabilitation on MIS spine surgery patient outcomes. <h3>PURPOSE</h3> Identify if preoperative rehabilitation influences patient outcomes following MIS spine surgery. <h3>STUDY DESIGN/SETTING</h3> Retrospective cohort. <h3>PATIENT SAMPLE</h3> This study included 524 MIS patients. <h3>OUTCOME MEASURES</h3> Preoperative rehabilitation, perioperative complications, patient outcomes. <h3>METHODS</h3> MIS spine surgery patients with baseline (BL) and two-year (2Y) follow-up were included if they had preoperative rehabilitation data. Patients were divided into two groups: those who had preoperative rehabilitation [Prehab] and those who did not [no Prehab]. Prehab consisted of physical and mental components, ie, physical therapy for 3 months, 3 days a week for core, paraspinal and leg strengthening, with a review of postop protocols to do at home, including gait and balance training. Patients were also referred for cognitive behavioral therapy for 2 weeks to prepare for the stress of surgery. Patients were excluded if they presented with any of the following at baseline: severe neurological deficit (< 3/5), minimal ambulation, or current depression/anxiety. Means comparison tests and logistic regression analysis controlling for age, CCI, ASA grade, and invasiveness assessed differences between patient groups. Conditional inference tree (CIT) analysis determined thresholds for continuous variables. <h3>RESULTS</h3> A total of 216 patients met inclusion criteria (76 Prehab, 140 no Prehab). The majority were male (97, 44.9%), mean age of 55.17 years, and 2.3 levels fused and 28 (13.0%) undergoing 3-CO. There was a significant difference in LOS for patients who had (3.6 days) and didn't have (5.3 days) Prehab, p <.05. Multivariate regression showed that Prehab was an independent predictor of a shorter LOS (OR .686 [CI .484-.972], p=.034). CIT analysis determined Prehab patients were 85.0% less likely to have a LOS greater than 2.0 days (OR .015 [CI .001-.258], p=.004). By 2 years, Prehab patients had lower rates of readmissions (6.7% vs 20.0%) and reoperations (4.0% vs 15.3%) than no Prehab patients, both p <.05. <h3>CONCLUSIONS</h3> Preoperative rehabilitation appears to be independently associated with a shorter length of stay following minimally invasive spine surgery. Patients who had preoperative rehabilitation also had lower rates of readmissions and reoperations by two years postoperatively. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.

P117. An evaluation of preoperative patient weight and body mass index during single-position minimally invasive spine surgery

<h3>BACKGROUND CONTEXT</h3> The single position minimally invasive (MIS) approach allows access to the anterior and posterior columns with the ability to mitigate complications associated with open procedures while achieving circumferential fusion. The purpose of this study was to identify if patient weight or body mass index (BMI) leads to differences in intraoperative event rates. <h3>PURPOSE</h3> To determine if patient weight and BMI will correlate with the occurrence of intraoperative events during MIS spine surgery. <h3>STUDY DESIGN/SETTING</h3> Retrospective cohort. <h3>PATIENT SAMPLE</h3> A total of 524 MIS patients. <h3>OUTCOME MEASURES</h3> Weight (kg), BMI (kg/m2), Aborted procedures, estimated blood loss (EBL), operative time (OpTime). <h3>METHODS</h3> Of 524 patients eligible, 226 (43.1%) had available data. Of these, 88 met inclusion criteria (52 Lat and 36 PL). The majority were male (49, 55.7%), mean age of 49.2 yrs and 2.0 levels fused and 18 (20.5%) undergoing an osteotomy. Lat patients with a weight > 130 kg had significantly longer OpTime (p=0.003) and more EBL (p=0.019). There was a significant difference in mean weight for lat patients with (121.8 kg) and without (97.7 kg) an aborted procedure, p=0.021. There was also a significant difference in mean BMI for lat patients with (35.3 kg/m2) and without (29.6 kg/m2) an aborted procedure, p=0.015. Multivariable analysis showed that weight (OR 1.03 [CI 1.01-1.06], p=.020) and BMI (OR 1.15 [CI 1.02-1.30], p=.026) were independent predictors for aborted procedures in lat patients. In an analysis of PL patients, there was one aborted case (weight > 120 kg), but no significant findings for EBL or OpTime. <h3>RESULTS</h3> Of 524 patients eligible, 226 (43.1%) had available data. Of these, 88 met inclusion criteria (52 Lat and 36 PL). The majority were male (49, 55.7%), mean age of 49.2 yrs and 2.0 levels fused and 18 (20.5%) undergoing an osteotomy. Lat patients with a weight > 130 kg had significantly longer OpTime (p=0.003) and more EBL (p=0.019). There was a significant difference in mean weight for lat patients with (121.8 kg) and without (97.7 kg) an aborted procedure, p=0.021. There was also a significant difference in mean BMI for lat patients with (35.3 kg/m2) and without (29.6 kg/m2) an aborted procedure, p=0.015. Multivariable analysis showed that weight (OR 1.03 [CI 1.01-1.06], p=.020) and BMI (OR 1.15 [CI 1.02-1.30], p=.026) were independent predictors for aborted procedures in lat patients. In an analysis of PL patients, there was one aborted case (weight > 120 kg), but no significant findings for EBL or OpTime. <h3>CONCLUSIONS</h3> Weight and BMI appear to be independently associated with aborted procedures for patients in the lateral decubitus position during minimally invasive spine surgery. Patients in the lateral decubitus position who weighed 130 kg or more had on average longer operative times and more estimated blood lost. This study has the potential to help with risk stratification in the future when determining patients undergoing a single position procedure. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.

Minimally Invasive Tubular Lumbar Discectomy Versus Conventional Open Lumbar Discectomy: An Observational Study From the Canadian Spine Outcomes and Research Network.

Retrospective cohort study. We evaluated the effectiveness of minimally invasive (MIS) tubular discectomy in comparison to conventional open surgery among patients enrolled in the Canadian Spine Outcomes and Research Network (CSORN). We performed an observational analysis of data that was prospectively collected. We implemented Minimum Clinically Important Differences (MCIDs), and we adjusted for potential confounders with multiple logistic regression. Adverse events were collected according to the Spinal Adverse Events Severity (SAVES) protocol. Three hundred thirty-nine (62%) patients underwent MIS tubular discectomy and 211 (38%) underwent conventional open discectomy. There were no significant differences between groups for improvement of leg pain and disability, but the MIS technique was associated with reduced odds of achieving the MCID for back pain (OR 0.66, 95% CI 0.44 to 0.99, P < 0.05). We identified statistically significant differences in favor of MIS for each of operating time (MIS mean (SD) 72.2 minutes (30.0) vs open 93.5 (40.9)), estimated blood loss (MIS 37.9 mL (36.7) vs open 76.8 (71.4)), length of stay in hospital (MIS 73% same-day discharge vs open 40%), rates of incidental durotomy (MIS 4% vs open 8%), and wound-related complications (MIS 3% vs open 9%); but not for overall rates of reoperation. Open and MIS techniques yielded similar improvements of leg pain and disability at up to 12 months of follow-up, but MIS patients were less likely to experience improvement of associated back pain. Small differences favored MIS for operating time, blood loss, and adverse events but may have limited clinical importance.

Minimally invasive mitral valve surgery after previous sternotomy: A propensity-matched analysis.

Although the incidence of mitral valve (MV) surgery after previous open-heart surgery is increasing, there is no consensus regarding the optimal surgical approach. Reoperative MV surgery is most commonly performed via sternotomy (ST). We sought to determine whether minimally-invasive (MIS) reoperative MV surgery is safe and feasible. All patients with a history of ST undergoing MV surgery with or without concomitant tricuspid or atrial fibrillation surgery at a single institution from 2007 to 2018 were retrospectively reviewed. ST and MIS approaches were compared using propensity-matched analysis. The coprimary endpoints were operative mortality and 1-year survival, and secondary endpoints were operative complications and length of stay. A total of 305 isolated MV reoperations were performed: 199 (65%) MIS and 106 (35%) ST. MIS patients were older than ST patients (71 [63, 76.5] vs. 66 [56, 72] years, p < .01), more likely to have undergone prior coronary artery bypass grafting (57% vs. 27%, p < .01), and less likely to have had prior valve surgery (55% vs. 78%, p < .01). In unmatched comparisons, operative mortality was significantly lower among MIS patients (3.0% vs. 8.5%, p = .04), but 1-year mortality was similar (14.4% vs. 15.6%, p = .8). After propensity matching, 88 pairs had excellent balance across baseline characteristics. Mortality was similar among MIS and ST patients at 30 days (3.4% vs. 8%, p = .19) and 1 year (15.9% vs. 16.5%, p = .9). RBC and fresh frozen plasma transfusions were significantly lower in the MIS group (p < .01). A minimally invasive approach is a safe alternative in patients with prior ST undergoing MV surgery.

A cost benefit analysis of increasing surgical technology in lumbar spine fusion

Numerous advances have been made in the field of spine fusion, such as minimally invasive (MIS) or robotic-assisted spine surgery. However, it is unknown how these advances have impacted the cost of care. Compare the economic outcomes of lumbar spine fusion between open, MIS, and robot-assisted surgery patients. Retrospective review of a single center spine surgery database. Three hundred sixty propensity matched patients. Costs, EuroQol-5D (EQ5D), cost per quality adjusted life years (QALY). Inclusion criteria: surgical patients >18 years undergoing lumbar fusion surgery. Patients were categorized into 3 groups based on procedure type: open, MIS, or robotic. Open patients undergoing poster spinal fusion were considered as the control group. MIS patients included those undergoing transforaminal or lateral lumbar interbody fusion with percutaneous screws. Robotic patients were those undergoing robot-assisted fusion. Propensity score matching was performed between all groups for the number of levels fused. Costs were calculated using the PearlDiver database, which reflects both private insurance and Medicare reimbursement claims for ICD-9 codes. For robotic cases, costs were reflective of operational fees and initial purchase cost. Complications and comorbidities and major complications and comorbidities were assessed according to CMS.gov manual definitions. QALYs and cost per QALY were calculated using a 3% discount rate to account for residual decline to life expectancy (78.7 years). Costs per QALY were calculated for both 1 year and life expectancy, assuming no loss of benefit. A 10,000 trial Monte Carlo simulation with probabilistic sensitivity analysis (PSA) assessed our model parameters and costs. Three hundred sixty propensity matched patients (120 open, 120 MIS, 120 robotic) met inclusion criteria. Descriptive statistics for the cohort were: age 58.8±13.5, 50% women, BMI 29.4±6.3, operative time 294.4±119.0, LOS 4.56±3.31 days, estimated blood loss 515.9±670.0 cc, and 2.3±2.2 average levels fused. Rates of post-op complications were significantly higher in robotic cases versus open and MIS (43% vs. 21% and 22% for open and MIS, p<.05). However, revision rates were comparable between all groups (3% open, 3% MIS, 5% robotic, p>.05). After factoring in complications, revisions, and purchasing and operating fees, the costs of robotic cases was significantly higher than both open and MIS surgery ($60,047.01 vs. $42,538.98 open and $41,471.21 MIS). In a subanalysis of 42 patients with baseline (BL) and 1Y EQ5D data, the cost per QALY at 1Y for open, MIS, and robot-assisted cases was $296,624.48, $115,911.69, and $592,734.30. If utility gained was sustained to life expectancy, the cost per QALY was $14,905.75, $5,824.71, $29,785.64 for open, MIS, and robot-assisted cases. Results of the PSA were consistent with MIS surgery having the most incremental cost effectiveness when compared to open and robotic surgery. Numerous advances have been made in the field of spine surgery, however, there has been limited discussion of the effect these advances have on economic outcomes. When matched for levels fused, robot-assisted surgery patients had significantly higher rates of complications and 30% higher costs of surgery compared to minimally invasive and open spine surgery patients. While 1 year economic outcomes were not optimal for robotic surgery cases, the projected costs per QALYs at life expectancy were well below established acceptable thresholds. The above findings may be reflective of an educational learning curve and emerging surgical technologies undergoing progressive refinement.

Minimally invasive sigmoidectomy for diverticular disease decreases inpatient opioid use: Results of a propensity score-matched study

BackgroundPatients undergoing gastrointestinal surgery are at high risk for postoperative opioid use. MethodsWe evaluated inpatient opioid use among patients undergoing sigmoidectomy for diverticular disease from the Premier Hospital Database and compared across surgical approaches using propensity score-matching analysis. ResultsAfter the day of surgery, minimally invasive (MIS) patients were administered significantly lower doses of parenteral opioids (median daily morphine milligram equivalents [MME]: 33.3 versus 48.3, p < 0.001). Within MIS, significantly less parenteral opioids were used by the robotic-assisted (RS) than the laparoscopic (LS) group (median daily MME: 30.0 versus 36.8, p = 0.012). MIS patients were more likely than open to start oral opioids on the day of surgery (MIS vs. OS: 8.7% vs. 6.6%, p < 0.001; RS vs. LS: 12.6% vs. 10.2%, p = 0.048). ConclusionMinimally invasive sigmoidectomy for diverticular disease was associated with less postoperative parenteral opioid use and starting oral opioids sooner after surgery compared to the open approach.

P2.16-50 Do Patients Have Preconceived Ideas on Various Surgical Approaches? Patient Perspective: Open vs. Minimally Invasive Surgery (PROMIS) Survey

Patient perspectives on minimally invasive (MIS) versus open surgical approaches have not been well studied. Health care workers often presume that patients prefer MIS. The aim of this survey was to objectively document patient viewpoints on pain, complication risks, cosmesis, travel burden, and functional outcomes throughout the course of treatment. From 2012-2017, of the 206 consented patients, 184 lung and esophageal surgical patients were prospectively enrolled in this observational cohort study. Participants were asked to complete a RAND36 short form health survey (SF-36), which measures functional outcomes. They also completed the PROMIS questionnaire, which measures expectations regarding travel burden, pain, complications, and cosmesis on a continuous visual analog scale (VAS). The PROMIS questions were also classified into three anatomic regions (neck, chest, and abdomen). Patients were surveyed pre-operatively, at 1 month and at 6 months. McNemar’s test, and paired and independent t-test were used as appropriate. Of 206 patients, 184 (89%) completed the survey at least once. SF-36 showed physical functioning, role limitations due to physical health, energy level, pain, and social functioning worsened significantly at 1 month. All indices recovered to baseline at 6 months. Recovery of indices was similar in both MIS and open surgery patients. Patients indicated that pain after surgery (mean VAS = 7.3; 95% CI 6.9-7.6) was more important than size of incision (mean VAS = 4.5; 95% CI 3.9-5.1, p < 0.001) and travel burden (mean VAS = 4.0; 95% CI 3.4-4.5, p < 0.001). The risk of complications (mean VAS = 7.5; 95% CI 7.2-7.9) was more important than size of incision (mean VAS = 4.5; 95% CI 3.9-5.1, p < 0.001) and travel burden (mean VAS = 4.0; 95% CI 3.4-4.5, p < 0.001). These findings were similar at each time point and across each body regions. The MIS group perceived pain following surgery (mean VAS = 7.12; 95% CI 6.35-7.89) was more important than the open group though it was not statistically different (mean VAS = 6.02; 95% CI 5.25-6.79, p = 0.07). Early postoperative deterioration followed by 6-month recovery in functional outcomes was reported by all patients regardless of surgical approach (MIS vs. open). Complication risk and pain after surgery were perceived as more important than size of incisions and distance traveled for treatment. Patients maybe more open-minded to participation in trials comparing MIS to open surgery than expected.

Perioperative outcomes in minimally invasive lumbar spine surgery: A systematic review.

To compare minimally invasive (MIS) and open techniques for MIS lumbar laminectomy, direct lateral and transforaminal lumbar interbody fusion (TLIF) surgeries with respect to length of surgery, estimated blood loss (EBL), neurologic complications, perioperative transfusion, postoperative pain, postoperative narcotic use, and length of stay (LOS). A systematic review of previously published studies accessible through PubMed was performed. Only articles in English journals or published with English language translations were included. Level of evidence of the selected articles was assessed. Statistical data was calculated with analysis of variance with P < 0.05 considered statistically significant. A total of 11 pertinent laminectomy studies, 20 direct lateral studies, and 27 TLIF studies were found. For laminectomy, MIS techniques resulted in a significantly longer length of surgery (177.5 min vs 129.0 min, P = 0.04), shorter LOS (4.3 d vs 5.3 d, P = 0.01) and less perioperative pain (visual analog scale: 16 ± 17 vs 34 ± 31, P = 0.04). There is evidence of decreased narcotic use for MIS patients (postoperative intravenous morphine use: 9.3 mg vs 42.8 mg), however this difference is of unknown significance. Direct lateral approaches have insufficient comparative data to establish relative perioperative outcomes. MIS TLIF had superior EBL (352 mL vs 580 mL, P < 0.0001) and LOS (7.7 d vs 10.4 d, P < 0.0001) and limited data to suggest lower perioperative pain. Based on perioperative outcomes data, MIS approach is superior to open approach for TLIF. For laminectomy, MIS and open approaches can be chosen based on surgeon preference. For lateral approaches, there is insufficient evidence to find non-inferior perioperative outcomes at this time.

Clinical and radiological outcomes of open versus minimally invasive transforaminal lumbar interbody fusion.

Prospective observational cohort study. Comparison of clinical and radiological outcomes of single-level open versus minimally invasive (MIS) transforaminal lumbar interbody fusion (TLIF) at 6 months and 2-year follow-up. There is recognition that more data are required to ascertain the benefits and risks of MIS vis-a-vis open TLIF. This study aims to report on one of the largest currently available series comparing the clinical and radiological outcomes of the two procedures with a minimum follow-up of 2 years. From January 2002 to March 2008, 144 single-level open and MIS TLIF were performed at our centre, with 72 patients in each group. Clinical outcomes were based on patient-reported outcome measures recorded at the Orthopaedic Diagnostic Centre by independent assessors before surgery, at 6 months and 2 years post-operatively. These were visual analogue scores (VAS) for back and leg pain, Oswestry disability index (ODI), short form-36 (SF-36), North American Spine Society (NASS) scores for neurogenic symptoms, returning to full function, and patient rating of the overall result of surgery. Radiological fusion based on the Bridwell grading system was also assessed at 6 months and 2 years post-operatively by independent assessors. In terms of demographics, the two groups were similar in terms of patient sample size, age, gender, body mass index (BMI), spinal levels operated, and all the clinical outcome measures (p > 0.05). Perioperative analysis revealed that MIS cases have comparable operative duration (open: 181.8 min, MIS: 166.4 min, p > 0.05), longer fluoroscopic time (open: 17.6 s, MIS: 49.0 s, p < 0.05), less intra-operative blood loss (open: 447.4 ml, MIS: 50.6 ml, p < 0.05) and no post-operative drainage (open: 528.9 ml, MIS: 0 ml, p < 0.05). MIS patients needed less morphine (open: 33.5 mg, MIS: 3.4 mg, p < 0.05) and were able to ambulate (open: 3.4 days, MIS: 1.2 days, p < 0.05) and be discharged from hospital earlier (open: 6.8 days, MIS: 3.2 days, p < 0.05). At 6 months, clinical outcome analysis showed both groups improving significantly (>50.0%) and similarly in terms of VAS, ODI, SF-36, return to full function and patient rating (p > 0.05). Radiological analysis showed similar grade 1 fusion rates (open: 52.2%, MIS: 59.4%, p > 0.05) with small percentage of patients developing asymptomatic cage migration (open: 8.7%, MIS: 5.8%, p > 0.05). One major complication (open: myocardial infarction, MIS: screw malpositioning requiring subsequent revision) and two minor complications in each group (open: pneumonia and post-surgery anemia, MIS: incidental durotomy and pneumonia) were noted. At 2 years, continued improvements were observed in both groups as compared to the preoperative state (p > 0.05), with 50.8% of open and 58% of MIS TLIF patients returning to full function (p > 0.05). Almost all patients have Grade 1 fusion (open: 98.5 %, MIS: 97.0%, p > 0.05) with minimal new cage migration (open: 1.4 %, MIS: 0%, p > 0.05). MIS TLIF is a safe option for lumbar fusion, and when compared to open TLIF, has similar operative duration, good clinical and radiological outcomes, with additional significant benefits of less perioperative blood loss and pain, earlier rehabilitation, and a shorter hospitalization.

424 Minimally invasive left ventricular assist device implantation improves clinical outcomes

424 Minimally invasive left ventricular assist device implantation improves clinical outcomes

A minimally invasive approach is more cost-effective than a traditional sternotomy approach for mitral valve surgery

The aim of this study was to compare the cost and effectiveness of a minimally invasive (MI) versus traditional sternotomy (ST) approach for mitral valve surgery (MVS). From January 1, 2003, to December 31, 2008, a total of 847 patients underwent isolated MVS at our institution. Propensity matching on 22 clinical variables was carried out to generate a study cohort of 434 patients (217 matched pairs). Direct and indirect costs from the hospital perspective were retrospectively obtained from our finance department. Total hospital costs were further stratified into 13 standardized institutional billing categories. In addition, data on morbidity, mortality, discharge location, hospital readmissions within 1 year, and freedom from reoperation were obtained. Compared with ST, MIMVS was associated with a $9054 ± $3302 lower mean total hospital cost (P=.006), driven largely by a reduction in direct (P=.003) versus indirect costs (P=.06). Among the 13 billing categories, MIMVS was associated with a significant reduction in costs of cardiac imaging (P=.004), laboratory tests (P=.005), boarding and nursing (P=.001), and radiology (P=.002). More patients in the ST group required intubation for more than 72 hours (P=.019); however, there were no differences in morbidity or long-term survival (P=.334). A higher proportion of MI patients were discharged home with no nursing services (P=.018), and a higher proportion of ST patients required readmission within 1 year (P=.023). There were no differences in freedom from reoperation between groups (P=.574). With equivalent efficacy across a range of measures and lower costs compared with ST, MIMVS represents a cost-saving strategy for MVS.

Minimally Invasive Versus Sternotomy Approach for Mitral Valve Surgery: A Propensity Analysis

Over the past decade, minimally invasive (MI) mitral valve surgery has grown in popularity. The purpose of this study was to compare both short- and long-term outcomes of mitral valve repair and replacement performed through a MI versus traditional sternotomy (ST) incision using a propensity analysis approach to account for differences in baseline risk. From January 2000 to December 2008, a total of 1,121 isolated mitral valve operations were performed at our institution (548 ST, 573 MI). Data were retrospectively collected on all patients, and a logistic regression model was created to predict selection to a MI versus ST approach. Propensity scores were then generated based on the regression model and matched pairs created using 1:1 nearest neighbor matching. There were 382 matched pairs in the analysis for a total sample size of 764, or 68.2% of the original cohort. Major outcomes of interest included cardiopulmonary bypass time, cross-clamp time, hospital length of stay, major in-hospital complications, and both short- and long-term survival. Cardiopulmonary bypass time was 117.1 ± 2.0 minutes in the ST group and 139.7 ± 2.6 minutes in the MI group (p < 0.0001), and cross-clamp time was 79.6 ± 1.5 minutes in the ST group and 83.7 ± 1.9 in the MI group (p = 0.106). The average hospital length of stay was 9.81 ± 0.61 days among ST patients and 7.76 ± 0.37 days among MI patients (p = 0.0043). There was no significant difference in the frequency of major in-hospital complications between groups. The mean duration of survival follow-up was 4.2 ± 2.4 years. There was no significant difference in mortality at 30 days (p = 0.622) or 1 year (p = 0.599). In addition, there was no significant difference in long-term survival between groups (p = 0.569). Although minimally invasive mitral valve surgery required a slightly longer cardiopulmonary bypass time, there was no difference in cross-clamp time, morbidity, or mortality, and hospital length of stay was significantly shorter when compared with matched sternotomy control patients.

Clinical and Radiological Outcomes of Minimally Invasive Versus Open Transforaminal Lumbar Interbody Fusion

Prospective study. Comparison of clinical and radiologic outcomes of minimally invasive (MIS) versus Open transforaminal lumbar interbody fusion (TLIF). Open TLIF has been performed for many years with good results. MIS TLIF techniques have recently been introduced with the aim of smaller wounds and faster recovery. From 2004-2006, 29 MIS TLIF were matched paired with 29 Open TLIF. Patient demographics and operative data were collected. Clinical assessment in terms of North American Spine Society, Oswestry Disability Index, Short Form-36, and Visual Analogue scores were performed before surgery, 6 months and 2 years after surgery. Fusion rates based on Bridwell grading were assessed at 2 years. The mean age for MIS and Open procedures were 54.1 and 52.5 years, respectively. There were 24 females and 5 males in both groups. Fluoroscopic time (MIS: 105.5 seconds, Open: 35.2 seconds, P < 0.05) and operative time (MIS: 216.4 minutes, Open: 170.5 minutes, P < 0.05) were longer in MIS cases. There was less blood loss in MIS (150 mL) versus Open (681 mL) procedures (P < 0.05). The total morphine used for MIS cases (17.4 mg) was less compared to Open (35.7 mg, P < 0.05). MIS (4 days) patients have shorter hospitalization compared to Open (6.7 days, P < 0.05). Both MIS and Open groups showed significant improvement in Oswestry Disability Index (P < 0.05), back pain and lower limb symptoms (North American Spine Society and Visual Analogue scores, P < 0.05), and Quality of Life scores (Short Form-36, P < 0.05) at 6 months and 2 years, but there was no significant difference between the 2 groups. Eighty percent of MIS and 86.7% of Open TLIF levels achieved grade 1 fusion (P > 0.05). MIS TLIF has similar good long-term clinical outcomes and high fusion rates of Open TLIF with the additional benefits of less initial postoperative pain, early rehabilitation, shorter hospitalization, and fewer complications.

HiRes 90K implantation using a minimally invasive surgical technique

This retrospective study compared safety and device outcomes for the HiRes 90K implant between (1) a minimally invasive (MI) surgical approach and early initial stimulation and (2) conventional surgical procedures and traditional initial programming schedules. Eight adults and 21 children were implanted using the MI approach and were programmed initially within 1 week after surgery. Surgical complications and device stability were compared to 55 adults and 16 children who were implanted using conventional surgery and programmed initially 4–6 weeks after surgery. No clinical differences were noted between patients undergoing MI surgery and patients implanted using more common surgical procedures. Electrode impedances stabilized earlier in the MI patients, and comfort levels for electrical stimulation were comparable between the two groups. Patients and families in the MI group have responded favorably to the shorter healing time, minimal hair shave, and shorter wait until initial programming.

A clinicopathologic study of minimally invasive follicular carcinoma of the thyroid gland with a review of the English literature.

The criteria for minimally invasive (low grade) follicular carcinoma of the thyroid (MI) remain controversial, often resulting in unnecessary treatment. The records of 130 patients with minimally invasive (MI) follicular thyroid carcinoma were retrieved from the files of the Endocrine Tumor Registry of the Armed Forces Institute of Pathology. Ninety-five patients were confirmed to have MI based on the authors' criteria of small-to-medium vessel invasion, capsular invasion of up to full thickness, no parenchymal tumor extension, and no tumor necrosis (patients with oxyphilic tumors were excluded). The remaining 35 patients had tumors that were reclassified as "not low grade" based on large vessel invasion, extension into parenchyma, and tumor necrosis (oxyphilic cases excluded). The MI patients included 67 women and 28 men, ages 20-95 years (average, 42.0 years). Nearly all patients presented with a thyroid mass (n = 90 patients). The mean tumor size was 2.8 cm. Histologic features examined for tumor classification included cellularity, capsule nature, capsular invasion, vascular invasion, extension into parenchyma, cytoplasmic oxyphilia, mitotic activity, and necrosis. All patients were treated with surgical excision. Adjuvant radioactive iodine therapy was performed in 24 patients. Five patients developed recurrent disease: four were alive or had died without evidence of disease after additional treatment (mean, 18.1 years), and one patient died with disease (MI tumor) at 15.1 years. All of the remaining patients were disease free (mean follow-up, 16.5 years). There are reproducible histologic criteria to diagnose patients with MI follicular carcinoma. The overall excellent long term prognosis and a good patient outcome suggests that no additional surgery is necessary.