Augmented Reality-Assisted Spine Surgery: An Early Experience Demonstrating Safety and Accuracy with 218 Screws

STUDY DESIGN

Prospective cohort study.

OBJECTIVES

In spine surgery, accurate screw guidance is critical to achieving satisfactory fixation. Augmented reality (AR) is a novel technology to assist in screw placement and has shown promising results in early studies. This study aims to provide our early experience evaluating safety and efficacy with an Food and Drug Administration-approved head-mounted (head-mounted device augmented reality (HMD-AR)) device.

METHODS

Consecutive adult patients undergoing AR-assisted thoracolumbar fusion between October 2020 and August 2021 with 2 -week follow-up were included. Preoperative, intraoperative, and postoperative data were collected to include demographics, complications, revision surgeries, and AR performance. Intraoperative 3D imaging was used to assess screw accuracy using the Gertzbein-Robbins (G-R) grading scale.

RESULTS

Thirty-two patients (40.6% male) were included with a total of 222 screws executed using HMD-AR. Intraoperatively, 4 (1.8%) were deemed misplaced and revised using AR or freehand. The remaining 218 (98.2%) screws were placed accurately. There were no intraoperative adverse events or complications, and AR was not abandoned in any case. Of the 208 AR-placed screws with 3D imaging confirmation, 97.1% were considered clinically accurate (91.8% Grade A, 5.3% Grade B). There were no early postoperative surgical complications or revision surgeries during the 2 -week follow-up.

CONCLUSIONS

This early experience study reports an overall G-R accuracy of 97.1% across 218 AR-guided screws with no intra or early postoperative complications. This shows that HMD-AR-assisted spine surgery is a safe and accurate tool for pedicle, cortical, and pelvic fixation. Larger studies are needed to continue to support this compelling evolution in spine surgery.

Technological Advances in Spine Surgery: Navigation, Robotics, and Augmented Reality

Accurate screw placement is critical to avoid vascular or neurologic complications during spine surgery and to maximize fixation for fusion and deformity correction. Computer-assisted navigation, robotic-guided spine surgery, and augmented reality surgical navigation are currently available technologies that have been developed to improve screw placement accuracy. The advent of multiple generations of new technologies within the past 3 decades has presented surgeons with a diverse array of choices when it comes to pedicle screw placement. Considerations for patient safety and optimal outcomes must be paramount when selecting a technology.

Opioid use after elective spine surgery: Do spine surgery patients consume less than prescribed today?

BACKGROUND

The opioid epidemic in the US has led prescribers to reevaluate postoperative pain control particularly in the field of spine surgery, where postoperative analgesia requirements and consumption have historically been high. There is a need to mitigate the quantity of unused pills after surgery by adjusting prescribing practices. Achieving the balance of pain control after surgery without overprescribing opioids may be accomplished by developing a modified approach to prescribing practices; however, there is a need to first understand the opioid requirements of the modern spine surgery patient with respect to their elective spine surgery. Therefore, the primary aim of this study was to determine the percentage of opioids not utilized at 90-days after elective spine surgery. Secondary aims were to identify differences in the percentage of unused opioids between surgical subgroups and preoperative opioid status, to determine factors associated with opioid utilization, and to estimate the distribution of opioids consumed to control pain up to the 90th percentile in each surgical subgroup.

METHODS

In this prospective, observational cohort study, adults undergoing elective spine surgery at a multi-surgeon, single center were prospectively enrolled and divided into subgroups: anterior cervical, lumbar decompression, and short-segment lumbar fusion. Prescribed MMEs were identified from prescriptions, consumed MMEs were obtained from pill counts, and the percent leftover was calculated. Distributions of MMEs consumed were analyzed to compare utilization between preoperative opioid users or non-users within each surgical subgroup.

RESULTS

Of 117 patients, 41.9% were preoperative opioid users. The percentage of unused opioids by surgical subgroup was: 45.4% cervical, 57.3% lumbar decompression, and 37.4% lumbar fusion (p=0.066). The percentage of unused opioids by preoperative opioid exposure was greater in the opioid non-users (58.0%) than users (28.4%, p<0.001)). Regression analysis showed that surgical subgroup and preoperative opioid exposure were associated with leftover opioids.

CONCLUSIONS

At 90-days, the percentage of unused opioids was over 45% in this cohort of elective spine surgery patients and was nearly double in the group without preoperative opioid exposure. These results suggest the modern elective spine surgery patient is using less opioids than prescribed, supporting the conclusion that the number of MMEs prescribed can be reduced to minimize quantities of leftover pills available for diversion, without sacrificing the priority of appropriate postoperative pain control.

Novel artificial intelligence algorithm: an accurate and independent measure of spinopelvic parameters

OBJECTIVE

The analysis of sagittal alignment by measuring spinopelvic parameters has been widely adopted among spine surgeons globally, and sagittal imbalance is a well-documented cause of poor quality of life. These measurements are time-consuming but necessary to make, which creates a growing need for an automated analysis tool that measures spinopelvic parameters with speed, precision, and reproducibility without relying on user input. This study introduces and evaluates an algorithm based on artificial intelligence (AI) that fully automatically measures spinopelvic parameters.

METHODS

Two hundred lateral lumbar radiographs (pre- and postoperative images from 100 patients undergoing lumbar fusion) were retrospectively analyzed by board-certified spine surgeons who digitally measured lumbar lordosis, pelvic incidence, pelvic tilt, and sacral slope. The novel AI algorithm was also used to measure the same parameters. To evaluate the agreement between human and AI-automated measurements, the mean error (95% CI, SD) was calculated and interrater reliability was assessed using the 2-way random single-measure intraclass correlation coefficient (ICC). ICC values larger than 0.75 were considered excellent.

RESULTS

The AI algorithm determined all parameters in 98% of preoperative and in 95% of postoperative images with excellent ICC values (preoperative range 0.85-0.92, postoperative range 0.81-0.87). The mean errors were smallest for pelvic incidence both pre- and postoperatively (preoperatively -0.5° [95% CI -1.5° to 0.6°] and postoperatively 0.0° [95% CI -1.1° to 1.2°]) and largest preoperatively for sacral slope (-2.2° [95% CI -3.0° to -1.5°]) and postoperatively for lumbar lordosis (3.8° [95% CI 2.5° to 5.0°]).

CONCLUSIONS

Advancements in AI translate to the arena of medical imaging analysis. This method of measuring spinopelvic parameters on spine radiographs has excellent reliability comparable to expert human raters. This application allows users to accurately obtain critical spinopelvic measurements automatically, which can be applied to clinical practice. This solution can assist physicians by saving time in routine work and by avoiding error-prone manual measurements.

Minimally Invasive Posterior Facet Decortication and Fusion Using Navigated Robotic Guidance: Feasibility and Workflow Optimization

Minimally invasive spine surgery reduces tissue dissection and retraction, decreasing the morbidity associated with traditional open spine surgery by decreasing blood loss, blood transfusion, complications, and pain. One of the key challenges with a minimally invasive approach is achieving consistent posterior fusion. Although advantageous in all fusion surgeries, solid posterior fusion is particularly important in spinal deformity, revisions, and fusions without anterior column support. A minimally invasive surgical approach accomplished without sacrificing the quality of the posterior fusion has the potential to decrease both short- and long-term complications compared to the traditional open techniques. Innovations in navigated and robotic-assisted spine surgery continue to address this need. In this article, we will outline the feasibility of achieving posterior facet fusion using the Mazor X Stealth Edition Robotic Guidance System.

Ninety-day complication, revision, and readmission rates for current-generation robot-assisted thoracolumbar spinal fusion surgery: results of a multicenter case series

OBJECTIVE

Robotics is a major area for research and development in spine surgery. The high accuracy of robot-assisted placement of thoracolumbar pedicle screws is documented in the literature. The authors present the largest case series to date evaluating 90-day complication, revision, and readmission rates for robot-assisted spine surgery using the current generation of robotic guidance systems.

METHODS

An analysis of a retrospective, multicenter database of open and minimally invasive thoracolumbar instrumented fusion surgeries using the Mazor X or Mazor X Stealth Edition robotic guidance systems was performed. Patients 18 years of age or older and undergoing primary or revision surgery for degenerative spinal conditions were included. Descriptive statistics were used to calculate rates of malpositioned screws requiring revision, as well as overall complication, revision, and readmission rates within 90 days.

RESULTS

In total, 799 surgical cases (Mazor X: 48.81%; Mazor X Stealth Edition: 51.19%) were evaluated, involving robot-assisted placement of 4838 pedicle screws. The overall intraoperative complication rate was 3.13%. No intraoperative implant-related complications were encountered. Postoperatively, 129 patients suffered a total of 146 complications by 90 days, representing an incidence of 16.1%. The rate of an unrecognized malpositioned screw resulting in a new postoperative radiculopathy requiring revision surgery was 0.63% (5 cases). Medical and pain-related complications unrelated to hardware placement accounted for the bulk of postoperative complications within 90 days. The overall surgical revision rate at 90 days was 6.63% with 7 implant-related revisions, representing an implant-related revision rate of 0.88%. The 90-day readmission rate was 7.13% with 2 implant-related readmissions, representing an implant-related readmission rate of 0.25% of cases.

CONCLUSIONS

The results of this multicenter case series and literature review suggest current-generation robotic guidance systems are associated with low rates of intraoperative and postoperative implant-related complications, revisions, and readmissions at 90 days. Future outcomes-based studies are necessary to evaluate complication, revision, and readmission rates compared to conventional surgery.

A multicenter study of the 5-year trends in robot-assisted spine surgery outcomes and complications

BACKGROUND

Although a growing amount of literature that suggests robots are safe and can achieve comparable outcomes to conventional techniques, much of this literature is limited by small sample sizes and single-surgeon or single center series. Furthermore, it is unclear what the impact of robotic technology has made on operative and clinical outcomes over time. This is the first and largest multicenter study to examine the trends in outcomes and complications after robot-assisted spine surgery over a 5-year period.

METHODS

Adult (≥18 years old) patients who underwent spine surgery with robot-assistance between 2015 and 2019 at four unique spine centers. The robotic systems used included the Mazor Renaissance, Mazor X, and Mazor Stealth Edition. Patients with incomplete data were excluded from this study. The minimum follow-up was 90 days.

RESULTS

A total of 722 adult patients were included (117 Renaissance, 477 X, 128 Stealth). Most patient and operative factors (e.g., sex, tobacco status, total instrumented levels, and pelvic fixation,) were similar across the years. Mean ± standard deviation Charlson comorbidity index (CCI) was 1.5±1.5. The most commonly reported diagnoses included high grade spondylolisthesis (40.6%), degenerative disc disease (18.4%), and degenerative scoliosis (17.6%). Mean (standard deviation) number of instrumented levels was 3.8±3.4. From 2015 to 2019, average robot time per screw improved from 7.2 to 5.5 minutes (P=0.004, R²=0.649). Average fluoroscopy time per screw improved from 15.2 to 9.4 seconds (P=0.002). Rates of both intraoperative screw exchange for misplaced screw (2015-2016: 2.7%, 2019: 0.8%, P=0.0115, R²=0.1316) and robot abandonment (2015-2016: 7.1%, 2019: 1.1%, P=0.011, R²=0.215) improved significantly over time. The incidence of other intraoperative complications (e.g., dural tear, loss of motor/sensory function, blood transfusion) remained consistently low, but similar throughout the years. The length of stay (LOS) decreased by nearly 1 day from 2015 to 2019 (P=0.007, R²=0.779). 90-day reoperation rates did not change significantly.

CONCLUSIONS

At four institutions among seven surgeons, we demonstrate robot screw accuracy, reliability, operative efficiency, and radiation exposure improved significantly from 2015 to 2019. 90-day complication rates remained low and LOS decreased significantly with time. These findings further validate continued usage of robot-assisted spine surgery and the path toward improved value-based care.

Adoption of enhanced surgical recovery (ESR) protocol for adult spinal deformity (ASD) surgery decreases in-hospital and 90-day post-operative opioid consumption

PURPOSE

Retrospective observational cohort study of primary adult spinal deformity (ASD) surgery during the transitional period prior to and after the implementation of Enhanced Surgical Recovery (ESR) at a single center. We sought to determine if ESR reduces in-hospital and 90-day post-operative opioid consumption for ASD surgery.

METHODS

We evaluated patients undergoing primary ASD surgery in the transition period prior to (N = 29) and after (N = 56) adoption of ESR, comparing in-hospital and 90-day post-operative opioid consumption. Regression analysis was used to control for confounders including age, number of surgical levels, surgical approach, staged vs same-day surgery, insurance type and pre-op opioid use.

RESULTS

Mean age of the cohort was 53 years with 57 (60%) females. Regression analysis showed that pre-operative opioid use and number of levels fused were associated with higher in-hospital and 90-day post-operative opioid consumption, while use of ESR was associated with lower in-hospital and 90-day post-operative opioid consumption. Secondary analysis showed that patients on ESR ambulated earlier (0.6 days vs 1.1, p = 0.028) and had their urinary catheter removed earlier (2.7 days vs 3.9, p = 0.006) compared to non-ESR patients.

CONCLUSIONS

ESR was associated with a significantly decreased in-hospital and 90-day post-operative opioid consumption and earlier mobilization with earlier urinary catheter removal in patients undergoing primary ASD surgery. These results demonstrate ESR's potential to improve outcomes in ASD perioperative care.

LEVEL OF EVIDENCE

3.

What Is the Comparison in Robot Time per Screw, Radiation Exposure, Robot Abandonment, Screw Accuracy, and Clinical Outcomes Between Percutaneous and Open Robot-Assisted Short Lumbar Fusion?: A Multicenter, Propensity-Matched Analysis of 310 Patients

STUDY DESIGN

Multicenter cohort.

OBJECTIVE

To compare the robot time/screw, radiation exposure, robot abandonment, screw accuracy, and 90-day outcomes between robot-assisted percutaneous and robot-assisted open approach for short lumbar fusion (1- and 2-level).

SUMMARY OF BACKGROUND DATA

There is conflicting literature on the superiority of robot-assisted minimally invasive spine surgery to open techniques. A large, multicenter study is needed to further elucidate the outcomes and complications between these two approaches.

METHODS

We included adult patients (≥18 yrs old) who underwent robot-assisted short lumbar fusion surgery from 2015 to 2019 at four independent institutions. A propensity score matching algorithm was employed to control for the potential selection bias between percutaneous and open surgery. The minimum follow-up was 90 days after the index surgery.

RESULTS

After propensity score matching, 310 patients remained. The mean (standard deviation) Charlson comorbidity index was 1.6 (1.5) and 53% of patients were female. The most common diagnoses included high-grade spondylolisthesis (grade >2) (48%), degenerative disc disease (22%), and spinal stenosis (25%), and the mean number of instrumented levels was 1.5(0.5). The operative time was longer in the open (198 min) versus the percutaneous group (167 min, P value = 0.007). However, the robot time/screw was similar between cohorts (P value > 0.05). The fluoroscopy time/ screw for percutaneous (14.4 s) was longer than the open group (10.1 s, P value = 0.021). The rates for screw exchange and robot abandonment were similar between groups (P value > 0.05). The estimated blood loss (open: 146 mL vs. percutaneous: 61.3 mL, P value < 0.001) and transfusion rate (open: 3.9% vs. percutaneous: 0%, P value = 0.013) were greater for the open group. The 90-day complication rate and mean length of stay were not different between cohorts (P value > 0.05).

CONCLUSION

Percutaneous robot-assisted spine surgery may increase radiation exposure, but can achieve a shorter operative time and lower risk for intraoperative blood loss for short-lumbar fusion. Percutaneous approaches do not appear to have an advantage for other short-term postoperative outcomes. Future multicenter studies on longer fusion surgeries and the inclusion of patient-reported outcomes are needed.Level of Evidence: 3.

Complications and Revision Rates in Minimally Invasive Robotic-Guided Versus Fluoroscopic-Guided Spinal Fusions: The MIS ReFRESH Prospective Comparative Study

STUDY DESIGN

Prospective, multicenter, partially randomized.

OBJECTIVE

Assess rates of complications, revision surgery, and radiation between Mazor robotic-guidance (RG) and fluoro-guidance (FG).

SUMMARY OF BACKGROUND DATA

Minimally invasive surgery MIS ReFRESH is the first study designed to compare RG and FG techniques in adult minimally invasive surgery (MIS) lumbar fusions.

METHODS

Primary endpoints were analyzed at 1 year follow-up. Analysis of variables through Cox logistic regression and a Kaplan-Meier Survival Curve of surgical complications.

RESULTS

Nine sites enrolled 485 patients: 374 (RG arm) and 111 (FG arm). 93.2% of patients had more than 1 year f/u. There were no differences for sex, Charlson Comorbidity Index, diabetes, or tumor. Mean age of RG patients was 59.0 versus 62.5 for FG (P = 0.009) and body mass index (BMI) was 31.2 versus 28.1 (P< 0.001). Percentage of smokers was almost double in the RG (15.2% vs. 7.2%, P = 0.029). Surgical time was similar (skin-to-skin time/no. of screws) at 24.9 minutes RG and 22.9 FG (P = 0.550). Fluoroscopy during surgery/no. of screws was 15.5 seconds RG versus 35.4 seconds FG, (15 seconds average reduction). Fluoroscopy time during instrumentation/no. of screws was 3.6 seconds RG versus 17.8 seconds FG showing an 80% average reduction of fluoro time/screw in RG (P < 0.001). Within 1 year follow-up, there were 39 (10.4%) surgical complications RG versus 39 (35.1%) FG, and 8 (2.1%) revisions RG versus 7 (6.3%) FG. Cox regression analysis including age, sex, BMI, CCI, and no. of screws, demonstrated that the hazard ratio (HR) for complication was 5.8 times higher FG versus RG (95% CI: 3.5-9.6, P < 0.001). HR for revision surgery was 11.0 times higher FG versus RG cases (95% CI 2.9-41.2, P < 0.001).

CONCLUSION

Mazor robotic-guidance was found to have a 5.8 times lower risk of a surgical complication and 11.0 times lower risk for revision surgery. Surgical time was similar between groups and robotic-guidance reduced fluoro time per screw by 80% (approximately 1 min/case).Level of Evidence: 2.

Robotic-guidance allows for accurate S2AI screw placement without complications

The study design is retrospective, multi-surgeon, single-center review. The objective is to evaluate complication rates, revision rates, and accuracy grading for robotic-guided S2 alar-iliac (S2AI) screws. Sixty-five consecutive patients underwent S2AI fixation (118 screws) as part of a posterior spine fusion using robotic-guidance. Screws were placed percutaneously in 14 cases and 51 were placed in an open fashion by three board-certified spine surgeons using the Mazor core technology robotic systems (Mazor X, n = 42; Mazor XSE, n = 23). Medical charts were retrospectively reviewed for revisions and complications. All patients were followed for 90 days or greater. Postoperative CT scans were obtained in 22 of the 51 patients, allowing for 46 screws to be reviewed by an independent neuroradiologist who graded the screws for accuracy. There were no intraoperative or postoperative complications associated with S2AI screw placement. There were no revisions found to be related to the S2AI screw placement. All 46 screws evaluated with postoperative CT scans were reported as being at the highest level of accuracy, grade A, with a breach distance of 0 mm (no breach). The robotic-guided technique for S2AI screw placement is a reliable method to achieving pelvic fixation with low complication and revision rates. In addition, a high degree of accuracy can be achieved without relying on visible and tactile landmarks needed for the freehand technique or the additional radiation associated with fluoroscopic-guidance.

Is there a difference between navigated and non-navigated robot cohorts in robot-assisted spine surgery? A multicenter, propensity-matched analysis of 2,800 screws and 372 patients

BACKGROUND CONTEXT

Robot-assisted spine surgery continues to rapidly develop as evidenced by the growing literature in recent years. In addition to demonstrating excellent pedicle screw accuracy, early studies have explored the impact of robot-assisted spine surgery on reducing radiation time, length of hospital stay, operative time, and perioperative complications in comparison to conventional freehand technique. Recently, the Mazor X Stealth Edition was introduced in 2018. This robotic system integrates Medtronic's Stealth navigation technology into the Mazor X platform, which was introduced in 2016. It is unclear what the impact of these advancements have made on clinical outcomes.

PURPOSE

To compare the outcomes and complications between the most recent iterations of the Mazor Robot systems: Mazor X and Mazor X Stealth Edition.

STUDY DESIGN

Multicenter cohort PATIENT SAMPLE: Among four different institutions, we included adult (≥18 years old) patients who underwent robot-assisted spine surgery with either the Mazor X (non-navigated robot) or Stealth (navigated robot) platforms.

OUTCOME MEASURES

Primary outcomes included robot time per screw, fluoroscopic radiation time, screw accuracy, robot abandonment, and clinical outcomes with a minimum 90 day follow up.

METHODS

A one-to-one propensity-score matching algorithm based on perioperative factors (e.g. demographics, comorbidities, primary diagnosis, open vs. percutaneous instrumentation, prior spine surgery, instrumented levels, pelvic fixation, interbody fusion, number of planned robot screws) was employed to control for the potential selection bias between the two robotic systems. Chi-square/fisher exact test and t-test/ANOVA were used for categorical and continuous variables, respectively.

RESULTS

From a total of 646 patients, a total of 372 adult patients were included in this study (X: 186, Stealth: 186) after propensity score matching. The mean number of instrumented levels was 4.3. The mean number of planned robot screws was 7.8. Similar total operative time and robot time per screw occurred between cohorts (p>0.05). However, Stealth achieved significantly shorter fluoroscopic radiation time per screw (Stealth: 7.2 seconds vs. X: 10.4 seconds, p<.001) than X. The screw accuracy for both robots was excellent (Stealth: 99.6% vs. X: 99.1%, p=0.120). In addition, Stealth achieved a significantly lower robot abandonment rate (Stealth: 0% vs. X: 2.2%, p=0.044). Furthermore, a lower blood transfusion rate was observed for Stealth than X (Stealth: 4.3% vs. X: 10.8%, p=0.018). Non-robot related complications such as dura tear, motor/sensory deficits, return to the operating room during same admission, and length of stay was similar between robots (p>0.05). The 90-day complication rates were low and similar between robot cohorts (Stealth: 5.4% vs. X: 3.8%, p=0.456).

CONCLUSION

In this multicenter study, both robot systems achieved excellent screw accuracy and low robot time per screw. However, using Stealth led to significantly less fluoroscopic radiation time, lower robot abandonment rates, and reduced blood transfusion rates than Mazor X. Other factors including length of stay, and 90-day complications were similar.

Adoption of Enhanced Surgical Recovery (ESR) Protocol for Lumbar Fusion Decreases In-Hospital Postoperative Opioid Consumption

STUDY DESIGN

Retrospective observational cohort.

OBJECTIVES

We sought to evaluate the impact of ESR on in-hospital and 90-day postoperative opioid consumption, length of stay, urinary catheter removal and postoperative ambulation after lumbar fusion for degenerative conditions.

METHODS

We evaluated patients undergoing lumbar fusion surgery at a single, multi-surgeon center in the transition period prior to (N = 174) and after (N = 116) adoption of ESR, comparing in-hospital and 90-day postoperative opioid consumption. Regression analysis was used to control for confounders. Secondary analysis was preformed to evaluate the association between ESR and length of stay, urinary catheter removal and ambulation after surgery.

RESULTS

Mean age study participants was 52.6 years with 62 (47%) females. Demographic characteristics were similar between the Pre-ESR and ESR groups. ESR patients had better 3-month pain scores, ambulated earlier, had urinary catheters removed earlier and decreased in-hospital opioid consumption compared to Pre-ESR patients. There was no difference in 90-day opioid consumption between the 2 groups. Regression analysis showed that ESR was strongly associated with in-hospital opioid consumption, accounting for 30% of the variability in Morphine Milligram Equivalents (MME). In-hospital opioid consumption was also associated with preoperative pain scores, number of surgical levels, and insurance type (private vs government). Pre-op pain sores were associated with 90-day opioid consumption. Secondary analysis showed that ESR was associated with a shorter length of stay and earlier ambulation.

CONCLUSIONS

This study showed ESR has the potential to improve recovery after lumbar fusion for degenerative conditions with reduced in-hospital opioid consumption and improved postoperative pain scores.

Do robot-related complications influence 1 year reoperations and other clinical outcomes after robot-assisted lumbar arthrodesis? A multicenter assessment of 320 patients

BACKGROUND

Robot-assisted platforms in spine surgery have rapidly developed into an attractive technology for both the surgeon and patient. Although current literature is promising, more clinical data is needed. The purpose of this paper is to determine the effect of robot-related complications on clinical outcomes METHODS: This multicenter study included adult (≥18 years old) patients who underwent robot-assisted lumbar fusion surgery from 2012-2019. The minimum follow-up was 1 year after surgery. Both bivariate and multivariate analyses were performed to determine if robot-related factors were associated with reoperation within 1 year after primary surgery.

RESULTS

A total of 320 patients were included in this study. The mean (standard deviation) Charlson Comorbidity Index was 1.2 (1.2) and 52.5% of patients were female. Intraoperative robot complications occurred in 3.4% of patients and included intraoperative exchange of screw (0.9%), robot abandonment (2.5%), and return to the operating room for screw exchange (1.3%). The 1-year reoperation rate was 4.4%. Robot factors, including robot time per screw, open vs. percutaneous, and robot system, were not statistically different between those who required revision surgery and those who did not (P>0.05). Patients with robot complications were more likely to have prolonged length of hospital stay and blood transfusion, but were not at higher risk for 1-year reoperations. The most common reasons for reoperation were wound complications (2.2%) and persistent symptoms due to inadequate decompression (1.5%). In the multivariate analysis, robot related factors and complications were not independent risk factors for 1-year reoperations.

CONCLUSION

This is the largest multicenter study to focus on robot-assisted lumbar fusion outcomes. Our findings demonstrate that 1-year reoperation rates are low and do not appear to be influenced by robot-related factors and complications; however, robot-related complications may increase the risk for greater blood loss requiring a blood transfusion and longer length of stay.

Reduction in complication and revision rates for robotic-guided short-segment lumbar fusion surgery: results of a prospective, multi-center study

Studies evaluating robotic guidance in lumbar fusion are limited primarily to evaluation of screw accuracy and perioperative complications. This is the first study to evaluate granular differences in short and long-term complication and revision rate profiles between robotic (RG) fluoroscopic (FG) guidance for minimally invasive short-segment lumbar fusions. A retrospective analysis of a prospective, multi-center database was performed. Complications were subdivided into surgical (further subcategorized into adjacent segment disease, new-onset back pain, radiculopathy, motor-deficit, hardware failure, pseudoarthrosis), wound, and medical complications. Complication and revision rates were compared between RG and FG groups cumulatively at 30, 90 days, and 1 year. 374 RG and 111 FG procedures were performed. RG was associated with an 86.25, 83.20, and 69.42% cumulative reduction in complication rate at 30, 90 days, and 1 year, respectively, compared to FG (p < 0.001). At all follow-up points, new-onset radiculopathy and medical complications were most prevalent in both groups. The greatest reductions in complication rates were seen for new-onset back pain (88.13%; p = 0.001) and wound complications (95.05%; p < 0.001) at 30 days, new-onset motor deficits (90.11%; p = 0.004) and wound complications (85.16%; p < 0.001) at 90 days, and new-onset motor deficits (85.16%; p = 0.002), wound (85.16%; p < 0.001), and medical complications (75.72%; p < 0.001) at 1 year. RG was associated with a 92.58% (p = 0.002) reduction in revision rate at 90 days and a 66.08% (p = 0.026) reduction at 1 year. RG was associated with significant reductions in postoperative complication rates at all follow-up time points and significant reductions in revision rates at 90 days and 1 year.

Fluoroscopy time analysis of a prospective, multi-centre study comparing robotic- and fluoroscopic-guided placement of percutaneous pedicle screw instrumentation for short segment minimally invasive lumbar fusion surgery

BACKGROUND

As minimally invasive spine surgery becomes more widespread, concerns regarding radiation exposure to surgeons and patients alike have become a growing concern. Robotic guidance has been developed as a way to increase the accuracy of instrumentation while decreasing radiation burden.

METHODS

A retrospective analysis of a large, multi-centre, prospective study comparing robotic-guided (RG) to fluoroscopic-guided (FG) (Multi-centre, Partially Randomized, Controlled Trial of MIS Robotic vs. Freehand in Short Adult Degenerative Spinal Fusion Surgeries) was performed to evaluate for differences in radiation exposure between study groups.

RESULTS

RG was associated with 78.3% (p < 0.001) and 79.8% (p < 0.001) reduction in total and per screw fluoroscopy times, respectively, as compared to FG. RG was also associated with a 50.8% (p < 0.001) reduction in total operative fluoroscopy time.

CONCLUSIONS

RG was associated with significantly lower fluoroscopy times compared to FG. This suggests that utilization of robotic navigation systems may result in decreased operative radiation exposure, which is a growing concern for surgeons performing minimally invasive spine surgery.

Effect of radiofrequency energy on glenohumeral fluid temperature during shoulder arthroscopy

BACKGROUND

Reports of glenohumeral chondrolysis following arthroscopy have raised concern about the deleterious effects that thermal devices may have on articular cartilage. The purpose of this study was to investigate the effects of flow and duration of treatment with a thermal device on temperatures within cadaveric glenohumeral joint specimens. It was hypothesized that the use of a thermal device during surgery increases the temperature of fluid within the joint to >45 degrees C, which has been shown to cause chondrocyte death.

METHODS

Temperature was measured at four locations within ten cadaver shoulder joints. Eight heating trials were performed on each cadaver shoulder to test three variables: the method of heating (continuous or intermittent), the fluid-pump flow rate (no flow, 50% flow, or 100% flow), and the location of the radiofrequency probe (the radiofrequency energy was either applied directly to anterior capsular tissue in a paintbrush pattern or held adjacent to the glenoid without tissue contact).

RESULTS

Temperatures of >45 degrees C occurred in every trial. The average maximum temperatures in all no-flow conditions were significantly higher than those in the trials with flow. Higher temperatures were measured by the anterior probe in all trials. When the heating had been applied adjacent to the glenoid, without tissue contact, the time needed to cool to a safe temperature was significantly longer in the no-flow states (average, 140.5 seconds) than it was in the 50% flow states (average, 12.5 seconds) or the 100% flow states (average, 8.5 seconds).

CONCLUSIONS

Use of a thermal probe during arthroscopy may cause joint fluid temperatures to reach levels high enough to cause chondrocyte death. Maintaining adequate fluid-pump flow rates may help to lower joint fluid temperatures and protect articular cartilage.

Glenohumeral chondrolysis after shoulder arthroscopy with thermal capsulorrhaphy

Glenohumeral chondrolysis is a rare but devastating complication that can occur after shoulder arthroscopy and thermal capsulorrhaphy. We retrospectively reviewed the medical records and imaging studies of 8 patients in whom glenohumeral chondrolysis developed after shoulder arthroscopy in which thermal energy was used. Of the 8 patients, 5 had previous thermal capsulorrhaphy for the diagnosis of instability. Two patients were diagnosed with instability with associated labral tears and underwent labral repair with thermal capsular shrinkage. One patient was diagnosed with a labral tear and underwent labral debridement with an extensive glenohumeral synovectomy via a thermal probe. No patients had evidence of chondral damage at their index arthroscopy, and none received postoperative pain pumps. In all patients, radiographic evidence of chondrolysis developed and repeat arthroscopy was performed to confirm the diagnosis. Open surgical stabilization has not been known to have this complication, and it is speculated that heating of the joint fluid at the time of arthroscopy from any source plays a role in cartilage death. Further studies are warranted to determine whether adequate outflow during shoulder arthroscopy where the fluid volume is relatively small will aid in avoiding complications associated with the use of heat sources.

Arthroscopic treatment of symptomatic discoid meniscus in children: classification, technique, and results

PURPOSE

The purpose of this study was to review the operative results of children and young adults treated arthroscopically for symptomatic discoid lateral menisci.

METHODS

The medical records and radiographic studies of 27 consecutive patients (30 knees) who underwent arthroscopic treatment for symptomatic discoid meniscus between 1998 and 2002 were reviewed.

RESULTS

The mean patient age was 10.1 years (range, 3 to 20 years), with 19 female and 8 male patients. The mean duration of symptoms before surgery was 13.9 months, with 28 knees (93%) having pain and 20 knees (67%) having mechanical symptoms. All patients were treated arthroscopically. Arthroscopic saucerization was successful in 28 of 30 knees. In 2 cases with large complex tears meniscal salvage was not possible and a complete arthroscopic meniscectomy was performed. Operative classification of the menisci revealed 22 complete (4 Wrisberg type) and 8 incomplete discoid menisci, with meniscal tears being present in 23 of 30 (77%). Meniscal instability was noted in 77% of knees (23 of 30), with anterior horn instability in 53% (n = 16), posterior instability in 16% (n = 5), and combined anterior and posterior instability in 6% (n = 2). All cases of anterior horn instability were treated with an outside-in arthroscopic repair technique, whereas all cases of posterior horn instability were treated with meniscal repair via an inside-out arthroscopic technique. Twenty-one patients (23 knees) had full follow-up of greater than 1 year. For these 21 patients, the mean length of follow-up was 37.4 months (range, 12 to 77 months), and at final follow-up, all patients exhibited full knee flexion beyond 135 degrees. Three patients reported residual knee pain, and four reported intermittent mechanical symptoms. At final follow-up, 2 patients felt that their activity level remained partially limited.

CONCLUSIONS

Our results show the short-term efficacy of arthroscopic saucerization and repair to the capsule in selected cases of symptomatic discoid menisci. On the basis of this experience and other recent reports documenting a high rate of anterior horn instability, an arthroscopic classification system for discoid lateral menisci is proposed. Menisci are classified as complete or incomplete discoid and are then subclassified based on the presence of instability as a result of deficient capsular attachment and, finally, based on the location of the absent capsular attachment.

LEVEL OF EVIDENCE

Level IV, therapeutic case series.

Biomechanical fixation in arthroscopic rotator cuff repair

Rotator cuff repair remains a challenging and rapidly evolving field. Several recent studies have shown that arthroscopic repair yields functional results similar to those of mini-open and open procedures, with all of the benefits of minimally invasive surgery. However, the "best" repair construct remains relatively unknown, with wide variations in surgeon preference and conflicting evidence in the literature. The most recent developments in basic science, suture and suture anchor technology, and innovative prospects for arthroscopic rotator cuff repair are reviewed.

Traumatic shoulder dislocation in the adolescent athlete: advances in surgical treatment

PURPOSE OF REVIEW

The shoulder joint has the greatest range of motion of any joint in the body and as a result is particularly susceptible to dislocation and subluxation. Recurrent instability is a common complication after traumatic shoulder dislocation in young people, with rates as high as 100% in skeletally immature patients and 96% in for adolescents. Treatment for shoulder dislocation has traditionally involved immobilization followed by a rehabilitation program. Recent studies have reported decreased rates of recurrent instability and improved outcomes in patients treated with surgical stabilization of acute, traumatic shoulder dislocation. The purpose of this review is to review recent publications concerning the treatment of traumatic shoulder dislocations in adolescents.

RECENT FINDINGS

Lawton et al. retrospectively reviewed 70 shoulders in 66 patients 16 years old or younger treated for shoulder instability with follow-up more than 2 years. Forty-two shoulders were successfully treated with physical therapy, whereas 28 eventually required surgery. Subsequently, Deitch et al. retrospectively identified 32 patients between 11 and 18 years of age with radiographically documented traumatic anterior shoulder dislocation. Instability recurred in 75% of patients and 50% eventually required surgical stabilization. Bottoni et al. reported results of a prospective randomized trial comparing arthroscopic stabilization to nonoperative treatment of acute, traumatic shoulder dislocations in patients aged 18 to 26 years. Recurrent instability developed in 75% of patients treated conservatively versus 11% in those treated with surgery. DeBerardino et al. prospectively evaluated arthroscopic stabilization of acute shoulder dislocations in 48 young athletes with an average follow-up of 37 months and reported a 12% rate of recurrent instability. All patients with stable shoulders were able to return to their previous levels of activity.

SUMMARY

Conservative management of traumatic shoulder dislocations in young patients is associated with high rates of recurrent instability. Recent studies have demonstrated improved results and significant reduction in recurrent instability in patients treated with surgical stabilization when compared with nonoperative treatment.

Immunohistochemical study of receptor activator of nuclear factor kappa-B ligand (RANK-L) in human osteolytic bone tumors

BACKGROUND AND OBJECTIVES

Osteolytic bone tumors produce intercellular signaling proteins that regulate bone remodeling by altering the rates of osteoclast and osteoblast differentiation and activity. This report examines osteolytic bone tumor expression of receptor activator of nuclear factor B-ligand (RANK-L), a cytokine that is arguably the most critical regulator of osteoclast differentiation and activation.

METHODS

This prospective immunohistochemical study examined RANK-L expression in frozen tissues from sixteen surgical specimens of patients who underwent surgery for the treatment of osteolytic bone tumors between 1999 and 2000.

RESULTS

RANK-L was positive in 13 of the 16 cases. Primary benign bone tumors, primary malignant bone tumors, and metastasis to bone were positive for RANK-L.

CONCLUSIONS

The cells in some, but not all, osteolytic tumors produce the cytokine RANK-L. Further study is necessary to determine in which specific tumors RANK-L is the cytokine responsible for increased osteoclastic activity, and to develop possible therapeutic use of RANK-L antagonists such as osteoprotegerin (OPG).

Tolerability of oral loading of divalproex sodium in child psychiatry inpatients

OBJECTIVE

To determine a well-tolerated oral load of divalproex sodium that quickly and reliably achieves therapeutic drug levels in child psychiatry inpatients.

METHODS

A retrospective chart review revealed that during a 6-month period, divalproex sodium therapy was initiated in 16 male inpatients (ages 5-14 years). The patients were divided into two groups based on the initial dosing regimen. The first group received approximately 15 mg/kg/day based on actual weight, and the second group received approximately 15 mg/kg/day based on an adjusted ideal body weight (IBW). Weight was adjusted in these patients according to the following formula: IBW + 40% (Observed Weight - IBW). A trough blood level was obtained on day 5 of therapy.

RESULTS

Initial drug levels ranged from 46-146 ug/mL (mean = 90.6), of which 13 of 16 (81.3%) were considered within therapeutic range (50-120 ug/mL). Eight of 16 patients (50%) had reported side effects, including sedation and gastrointestinal upset. The majority of these side effects occurred in patients with drug levels > or = 90 ug/mL and were noted to improve with 1-2 days of therapy +/- dosage adjustment. Overweight patients (> or = 15% above IBW) who received the unadjusted 15 mg/kg oral load had significantly higher drug levels than their normal weight counterparts and overweight children who received weight-adjusted dosing (p < 0.003).

CONCLUSION

A 15 mg/kg/day oral load of divalproex sodium resulted in therapeutic drug levels on day 5 of treatment and is well tolerated in normal weight children. Overweight children are significantly more likely to experience supratherapeutic drug levels on this regimen, which may affect tolerability. Overweight children appear to benefit from weight-adjusted oral loading.