Impact of Minimally Invasive Spine Surgery Training on Surgeon Practice and Perceptions

1. Study Design

The Ohio State University institutional research board (2024E0921) exemption was obtained given that the study involved the use of survey procedures uninfluenced by the investigator and the information obtained is recorded without direct or indirect identifiers. All procedures performed followed the principles of the Declaration of Helsinki. The study was conducted through an online survey based on similar methodology from previous studies [6,7]. The survey collected responses from June 24 through December 31, 2024 using Qualtrics, which was accessible on the computer, laptop, and any tablets. Surveys were sent out through social media and emailed to members of AO Spine and American Association of Neurological Surgeons (AANS) within North America who listed “Spine” as one of their subspecialties. Reminder emails were sent monthly to maximize responses. The qualifications to participate were to be a practicing neurosurgical or orthopedic spine surgeon at the time of the survey. Informed consent was signed by qualified respondents before completing the survey. Surgeons were asked to answer a variety of questions regarding MISS training, techniques used in actual practice, and the outlooks surgeons have on MISS outcomes. MISS here is defined as any procedure using smaller incisions than standard open spine surgeries. Survey questions focused on MISS procedures performed in the lumbosacral (L1–S1) region.

It remained unimportant whether surgeons have previously performed MISS, although if they had responded “No” to having ever performed MISS, they would only respond to the outlooks portion of the survey. This sample was only included for the analysis between MISS usage and outlook, in which case the sample was placed with the “≤50%” group for questions relating to “What percentage of your current surgeries are MISS?”.

The study reported is in line with the STROBE (Strengthening the Reporting of Observational Studies in Epidemiology) guidelines [8].

2. Statistical Analysis

Sample sizes differed slightly across analyses because a small number of survey items had missing responses. Early in the data collection period, the survey was modified to require responses to all questions, minimizing missing data for subsequent participants.

Descriptive statistics were used to summarize surgeon training and practice characteristics. Categorical variables were reported as frequencies and percentages. Group comparisons between neurosurgeons and orthopedic surgeons were conducted using Fisher exact tests. Analysis using Fisher exact tests was also performed between MISS outcomes and the following surgeon characteristics: training background (neurosurgery vs. orthopedic surgery), current MISS performer status, receipt of formal MISS training during residency, completion of a fellowship in MISS, years of MISS practice (≤11 years vs. ≥12 years), and the proportion of current spine surgeries, decompressions, discectomies, and fusions performed using MISS (≤50% vs. >50%). Categorical variables were compared using Fisher exact test because several contingency tables contained small cell counts, making the chi-square approximation potentially unreliable. Fisher exact test provides an exact p-value and is appropriate for analyses with limited sample sizes or sparse data [9].

Multivariable ordinal logistic regression models were used to further examine associations between surgeon characteristics and perceptions of procedural outcomes. Three sets of models were fit separately for outcomes related to: (1) perceived procedural time (general MISS, decompressions, discectomies, fusions), (2) perceived complication rates (decompressions, discectomies, fusions), and (3) postoperative recovery outcomes (blood loss, length of stay, revision rates). In all models, the outcome was treated as an ordinal variable with 3 ordered response levels (“less,” “same,” “more”). Adjusted odds ratios (aORs) with 95% confidence intervals (CIs) were reported. Covariates included in all models were those listed for surgeon characteristics. All statistical tests were 2-sided, with significance defined as p<0.05. Analyses were performed using Stata 18 (StataCorp LLC, USA).

1. Surgeon Perceptions of Procedural Time

Table 3 displays the adjusted ordinal logistic regression results examining surgeon perceptions of procedural time in MISS compared to open spine surgery. Surgeons performing >50% of their laminectomies and fusions using MISS techniques had significantly lower odds of perceiving longer procedural times for MISS decompressions compared to those performing ≤50% (aOR, 0.19; p=0.005 and aOR, 0.20; p=0.024, respectively). Similarly, surgeons performing >50% of their discectomies using MISS reported significantly lower odds of perceiving longer procedural times for MISS discectomies (aOR, 0.11; p=0.001). While not significant, surgeons performing >50% of their fusions using MISS trended towards lower odds of perceiving longer procedural times for MISS fusions (aOR, 0.28; p=0.056). No significant associations were observed for other practice variables (all p>0.05).

Table 3.

Surgeon perceptions of minimally invasive spine surgery procedural times compared to open spine surgery (outcome scale 1=less, 2=same, 3=more)

2. Perceived Complication Rates

Table 4 displays the adjusted ordinal logistic regression results examining surgeon perceptions of complication rates after MISS compared to open spine surgery. Surgeons performing >50% of their overall surgeries using MISS had significantly lower odds of perceiving higher complication rates for laminectomies (aOR, 0.23; p=0.046). For discectomies, orthopedic surgeons had significantly higher odds of perceiving greater complication rates compared to neurosurgeons (aOR, 3.74; p=0.019). Additionally, surgeons performing >50% of their laminectomies using MISS reported significantly lower odds of perceiving higher complication rates for MISS discectomies (aOR, 0.22; p=0.010). For MISS discectomies, surgeons who took an MISS fellowship showed a trend toward lower perceived complication rates (aOR, 0.36; p=0.068). No significant associations were observed for other practice variables (all p>0.05).

Table 4.

Surgeon perceptions of minimally invasive spine surgery complication rates compared to open spine surgery during the following procedures (outcome scale 1=less, 2=same, 3=more)

3. Postoperative Recovery Outcomes

Table 5 displays the adjusted ordinal logistic regression results examining surgeon perceptions of postoperative recovery outcomes after MISS compared to open spine surgery. For revision rates, fellowship-trained surgeons had significantly lower odds of perceiving higher revision rates compared to nonfellowship-trained surgeons (aOR, 0.30; p=0.029). Additionally, surgeons performing >50% of their current surgeries using MISS had significantly lower odds of perceiving higher revision rates compared to those performing ≤50% (aOR, 0.13; p=0.005). No significant associations were observed for length of stay. Blood loss was excluded as outcome due to nonvariability in responses (94.4% responded for “less”).

Table 5.

Surgeon perceptions of minimally invasive spine surgery postoperative outcomes compared to open spine surgery (outcome scale 1=less, 2=same, 3=more)

While Fisher exact test between surgeon characteristics and MISS outcomes revealed additional significance, many of these associations were lost after adjusting for covariates (Supplementary Tables 1–9).

1. Findings Summary

This study examined how the relationship between MISS training background and usage influenced surgeon perceptions on MISS compared to open spine surgeries. Neurosurgeons reported greater MISS experience and utilized more MISS techniques than orthopedic surgeons, though neither group used endoscopic techniques. Routine performance of MISS decompressions and discectomies was associated with perceiving these procedures as faster than open surgery, whereas MISS fusions were not viewed as faster, likely reflecting their higher complexity and technical demands. However, those with greater MISS fusion experience reported shorter decompression times, suggesting possible skill transfer across related procedures. Likewise, more decompression experience corresponded to lower perceived discectomy complications. Higher MISS volume was also associated with lower perceived complication rates for decompressions, although orthopedic surgeons were more likely to perceive higher complication rates, particularly for discectomies. Fellowship training and higher MISS volume corresponded to lower perceived revision rates, while blood loss was considered lower for MISS regardless of variables. Overall, greater MISS experience correlated with more favorable views of MISS efficiency and patient outcomes relative to open spine surgery.

2. Specialty-Based Differences

While neurosurgeons were found to report greater MISS usage, longer experience, and less complications, there is a notable gap in the literature comparing exposure across specialties. Given that there were no significant differences found between having MISS training in residency and fellowship between neurosurgeons and orthopedic surgeons, other possibilities include the amount of MISS training, case exposure, and emphasis during residency. In contrast, a separate survey study involving a broader population had found that orthopedic surgeons were more likely than neurosurgeons to perform MISS and rated their mastery higher [6]. This discrepancy highlights how differences in training pathways and healthcare systems across regions can influence the use of MISS. They may also reflect evolving curricular trends in neurosurgery and orthopedic surgery that differ by country or institution.

Despite growing global interest in endoscopic techniques, adoption remains limited, as demonstrated by the lack of endoscopic spine surgery among respondents. This pattern is consistent with recent studies identifying multiple barriers to the widespread use of endoscopic MISS, including limited training opportunities, technical difficulty, steep learning curves, and high equipment costs [10-13]. In an international survey by Alostaz et al. [10], over half of surgeons noted that their primary barrier to performing endoscopic spine decompressions was from a lack of training or equipment availability. Technical challenges, such as limited visualization, reduced tactile feedback, and the need for high-level hand-eye coordination, also pose significant obstacles to implementation, especially in centers without structured mentorship programs [11-13].

Conversely, neurosurgeons reported significantly greater use of MISS techniques such as mini-open, tubular-based, XLIF, and percutaneous pedicle screw fixation. Although direct comparisons in the literature remain limited, several training-related factors may contribute to this finding. Studies have shown that neurosurgery residents consistently log substantially higher spine case volumes and procedural hours than orthopedic residents, promoting earlier and more frequent opportunities to familiarize and develop proficiency with microscope-based and image-guided navigation [14,15]. Additionally, access to MISS technology has also been reported to be greater in neurosurgery than for orthopedic surgery [16]. Given that MISS often relies on working through narrow or indirect access corridors, these techniques may feel more intuitive to neurosurgeons with prior experience in minimally invasive cranial and spinal procedures [17]. In contrast, orthopedic surgeons may receive more early exposure to open fixation techniques and deformity correction, potentially delaying comfort with narrow corridor approaches. Nevertheless, these differences underscore the clinical importance of studying early, structured exposure to a range of MISS techniques during residency and fellowship training in shaping long-term practice patterns.

3. Impact of Learning Curves

MISS has become an increasingly adopted technique in spine procedures due to its potential to reduce tissue disruption, shorten hospital stays, and improve postoperative recovery. However, the transition from open to minimally invasive approaches presents significant challenges, particularly in relation to surgeon training and the steep learning curve associated with mastering these techniques. Recent work has advocated for structured training programs that include cadaver labs, simulation, mentorship, and modular credentialing to mitigate the impact of this learning curve, but further clinical studies will be needed to assess their effectiveness [7,18]. As seen with this study, surgeons who frequently perform decompressions and discectomies reported increased time efficiency, whereas this association was present but not as strong for fusions. This may be due to the increased technical demands of fusion procedures, which require advanced skills in navigation, instrumentation, and anatomical orientation. This trend has been well-supported in previous literature, with multiple studies indicating that learning curves and complications plateau for MISS decompression/discectomy range between 20-30 cases, and an upwards of 44 cases or more for fusion procedures like MISS transforaminal lumbar interbody fusion [17,19-23].

Furthermore, different MISS techniques may also pose their own unique learning curves, with the aforementioned endoscopic spine surgery remaining as one of the steeper ones. A comprehensive meta-analysis of endoscopic spinal surgery found that surgeons typically require 32.5±10.5 cases to reach mastery, with experienced surgeons showing shorter operating times and better outcomes [22]. A similar study expands on these findings, explaining that there may be separate learning curves for operating times and complications. While transforaminal endoscopic discectomies revealed that approximately 20 cases are needed to overcome 80% of operative time inefficiencies, true proficiency across both operating time and complication reduction approached true plateau after about 60 cases [23].

These findings collectively emphasize that proficiency in MISS requires considerable repetition and time, especially for complex procedures. Surgeons who reported faster decompression or discectomy times likely benefited from repetition and volume. Yet, given the lack of opportunities, this may explain why orthopedic surgeons perceived greater complications even with MISS decompressions and discectomies within this study. For more intricate procedures like fusions or techniques using endoscopy, perceived efficiency may lag until proficiency is well established.

Our findings may reflect cross-procedural skill transfer, whereby experience gained in MISS fusion procedures improves efficiency in related MISS decompression techniques. Motor learning theory suggests that transfer of training is most likely when tasks share overlapping psychomotor and cognitive demands, a concept often referred to as near transfer [24-26]. Decompression constitutes a core technical component of many fusion procedures, particularly in MISS approaches where surgeons repeatedly perform bony resection, neural element identification, and work through constrained operative corridors. Repeated exposure to these shared elements while performing a more difficult procedure may help reduce cognitive load, thereby shortening operative time when the decompression is performed as a standalone procedure [27,28]. While our study design does not permit causal inference, the observed association between fusion experience and shorter decompression times is consistent with established principles of motor learning and skill acquisition.

4. Patient Versus Provider Perspectives

Patients consistently demonstrate a preference for MISS over traditional open procedures, largely due to expectations of reduced pain, quicker recovery, and fewer complications. In a study by Narain et al. [1], 80% of patients preferred a minimally invasive approach, viewing open surgery as more painful, risky, expensive, and associated with longer recovery. Another study by White et al. [2] not only agreed with this finding but also found that patients were more confident in MISS procedures and preferred MISS in the future regardless of whether they had received an open or MISS procedure originally. These patient preferences are supported by growing evidence comparing outcomes between MISS and open surgery. Although studies have shown that MISS operative times may be longer initially and has a similar long-term outcome for up to 10 years, it is also associated with reduced blood loss, length of hospital stays, infection risks, reoperation rates, and earlier functional recovery compared to open spine surgery [29-33].

Notably, perceived differences in blood loss and length of stay were not significant while lower revision rates were reported among surgeons who had completed MISS fellowships or performed a high volume of MISS procedures. When examining response distributions across all groups, perceptions of reduced blood loss and shorter hospital stay remained consistent regardless of surgeon background or experience, indicating a widespread acceptance of these benefits. The perception of fewer revisions among experienced surgeons likely reflects the effect of surpassing the learning curve and increased procedural confidence. Although many spine surgeons recognize the potential advantages of MISS techniques, exact reasons for the hesitation in their widespread adoption requires the need for further clinical studies to clarify long-term outcomes and technical reliability.

The observed disconnect between patient enthusiasm and provider caution highlights a critical gap in MISS expectations versus implementation. While patient demand for MISS continues to rise, provider confidence may depend heavily on technical experience, institutional resources, and consistent long-term data. Encouragingly, our findings suggest that as surgeons gain experience, their perceptions of MISS tend to align more closely with the positive patient outlook, reinforcing the value of structured training and assessing longitudinal outcomes.

5. Limitations

This study has several limitations that should be acknowledged. First, the absence of a standardized definition of MISS may have influenced how respondents interpreted the survey when identifying the techniques they use, potentially leading to overestimation or underestimation of MISS technique utilization. Although respondents were asked, “How many years have you practiced MISS?”, the response options were somewhat arbitrary and did not account for surgeons’ age, total years in practice, or the exact duration of MISS experience. Consequently, career stage and the extent to which MISS has been integrated into practice cannot be precisely characterized. In addition, surgeons who began practicing before the establishment of formal MISS fellowship programs may have limited access to structured training, which could have influenced their confidence, familiarity, and perceptions regarding MISS. Contextual variables such as geographic distribution, practice setting (academic vs. private), and institutional resources were also not collected, limiting adjustment for confounding and generalizability. Second, the sample was skewed by specialty, with neurosurgeons overrepresented relative to orthopedic surgeons. Responses were self-reported and participation was voluntary, raising the possibility of self-selection and unit nonresponse bias; surgeons more familiar with or favorable toward MISS may have been more likely to participate. Because the survey was distributed through professional society channels, the total number of recipients is unknown and we could not compare respondents with nonrespondents, limiting generalizability. Moreover, distribution was limited to AANS and AO Spine members, which may not capture broader regional or international perspectives; differences from prior international work [6] suggest that regional and institutional context may shape MISS attitudes and practice patterns.

Third, the outcomes reflect surgeon perceptions rather than patient-level measures, so associations should not be interpreted as clinical effects on perioperative outcomes. The modest sample size also resulted in sparse cells for several covariates and limited variability for some endpoints, which can yield unstable regression estimates (e.g., wide CIs and occasional quasi-complete/complete separation leading to nonestimable parameters). To obtain estimable models, some predictors were analyzed using collapsed categories (e.g., experience groupings) when finer coding produced sparse-data estimation problems; while this improves stability, it reduces granularity and may obscure heterogeneity. Finally, multiple outcomes and models were examined across the main tables. Because analyses were exploratory, formal multiplicity adjustments were not applied and marginal p-values should be interpreted cautiously with emphasis on effect sizes and 95% CIs.

Future research should address these limitations by refining survey designs to better capture years of practice, objective clinical outcomes, and aim to include a larger, more globally representative cohort to further elucidate regional differences in MISS practice patterns.