Abstract
Background A recent advance in spine surgery instrumentation is the awl-tipped screw, which allows for a reduction in the number of steps during a procedure. This innovation has the potential to decrease surgical time and affect overall efficiency. The purpose of the present study was to determine whether the use of awl-tipped pedicle screws reduces surgical time and blood loss compared with the use of conventional pedicle screws.
Methods Using a retrospective records review, 410 patients who underwent open posterior lumbar spinal fusion surgery were analyzed. We compared 205 cases that used awl-tipped screws to 205 matched controls that used conventional pedicle screws that required tapping. The awl-tipped screw and control groups were matched for instrumented spine levels fused and were equivalent regarding other patient characteristics.
Results Surgeries with awl-tipped pedicle screws took less time (mean [SD] = 94.35 [24.09] minutes) than surgeries with conventional screws that required tapping (mean [SD] = 111.11 [33.00] minutes; t 408 = 5.87, P < 0.001). The amount of blood loss did not differ significantly between the 2 groups but trended in the expected direction.
Conclusion Clinicians who use pedicle screws in their practice should consider utilizing awl-tipped screws rather than traditional ones, as the reduced surgical time they can provide may translate into benefits for patients.
Introduction
As surgical instrumentation improves, it is important to determine the impact of new technology on important outcomes such as surgical time and efficiency. One recent advance in spine surgery instrumentation is the creation and implementation of the awl-tipped pedicle screw. This type of screw has a number of beneficial features that may reduce surgical time in comparison to conventional pedicle screws that require tapping. In particular, awl-tipped pedicle screws may reduce the number of operative steps (by removing the need for a tapping step) and save time during surgical procedures, thereby optimizing the efficiency to patients in terms of infection, blood loss, sedation, and potential surgical errors.1 Studies are emerging that examine the relative efficiency of awl-tipped pedicle screws compared with conventional pedicle screws, but this is still a relatively new technology that requires further investigation as to precisely how awl-tipped screws affect surgical time. What remains unsubstantiated scientifically is whether the use of awl-tipped screws in spine surgery reduces surgical time and blood loss.
This study aimed to add to the literature by analyzing spine surgery cases that used awl-tipped pedicle screws, along with matched controls that used conventional pedicle screws that require tapping. We hypothesized that the cases that used the awl-tipped screws would have reduced surgical time and less blood loss in comparison to the use of conventional pedicle screws that required tapping.
Technology Description
The primary benefit of awl-tipped pedicle screws in comparison to conventional pedicle screws is that they do not require a separate tap prior to implantation. When using conventional pedicle screws, surgeons typically first drill a starter hole. Once the start point is established, they pass a probe through the pedicle and then pass a tap, all prior to inserting the screw.1 However, the pyramidal configuration of the awl-tipped screw allows the surgeon to create a pilot hole in the pedicle, followed by a probe, and then move directly to screw insertion without a tap step.1
Methods
Participants
Records of patients in this retrospective review were collected from 410 open posterior lumbar spinal fusion surgeries conducted by 1 practice at Christiana Hospital between 2016 and 2022. Patients undergoing open posterior lumbar fusion were included only if their procedures utilized screws; patients undergoing procedures using clamps or any other nonpedicle screw fixation devices were omitted from this study. Additionally, only patients undergoing open instrumented fusion surgeries were included. Procedures such as in situ fusions with bone grafting alone do not employ screws of any kind, so they were not included. Additionally, patients younger than 18 years were excluded.
Materials
Each awl-tipped pedicle screw had an awl tip, allowing it to be inserted into the vertebra bone through the body of the pedicle. Each conventional pedicle screw lacked an awl tip and required tapping. Pedicle screw instrumentation included commercially available awl-tipped screws as well as conventional screws with a traditional blunt-tipped design. For clarity, screws are categorized in this report by design type (awl-tipped vs conventional) rather than by manufacturer, as the defining feature under investigation is the awl-shaped tip. Electronic navigation was employed for all screw insertions in both groups.
Procedure
Data for this study were collected from an existing private practice medical records database and stored on a private, secure drive. Data points such as demographics, the number of instrumented spine levels fused, surgical incision and closure time, and estimated blood loss were collected from the database. Beginning in 2016, the CPT codes of patients’ procedures were used to isolate patients who had 1-level or multilevel fusions, and the number of instrumented spine levels fused was detailed in the operative reports. The operative reports also indicated which type of screw was used during the procedure: awl-tipped pedicle screws or conventional pedicle screws that required tapping.
Total surgical time was defined as incision to closure. Blood loss was estimated blood loss determined by the surgeon, anesthesiologist, and nursing staff and recorded in the nursing note. Data collection for patients in the awl-tipped group began in 2019, which is when our practice began to use awl-tipped pedicle screws in procedures. Data collection for patients in the conventional screw group began in 2016. Patients’ records continued to be collected chronologically until both groups matched in number of cases for each level of instrumented fusion.
Statistical Methods
Data analyses were conducted using the Statistical Package for Social Sciences (SPSS) version 26. We assessed the statistical significance of our findings using between-groups t tests, with the threshold for significance set at a P value of 0.05.
Results
Of the 410 patients, 205 patients’ surgeries used awl-tipped pedicle screws, and 205 patients’ surgeries used conventional pedicle screws that required tapping. Within each of the 2 main groups, awl-tipped vs conventional screws that required tapping, 100 patients had 1-level instrumented open posterior spinal fusions, 74 patients had 2-level instrumented open posterior spinal fusions, 28 patients had 3-level instrumented open posterior spinal fusions, and 3 patients had 4-level instrumented open posterior spinal fusions.
From the group whose surgeries used awl-tipped screws, 51% were women (n = 104) and 49% were men (n = 101) with a mean age of 61.31 years (SD = 12.69) and a mean body mass index of 31.57 (SD = 6.45). From the group whose surgeries used conventional pedicle screws, 57% were women (n = 116) and 43% were men (n = 88) with a mean age of 59.86 years (SD = 13.18) and a mean body mass index of 31.16 (SD = 6.52). For awl-tipped patients, 72% were white (n = 148), 23% were black (n = 47), and 5% were other (n = 10). For conventional screw patients, 74% were white (n = 151), 20% were black (n = 42), and 6% were other (n = 12). Patients across groups did not differ statistically in any of these demographic categories (all P > 0.05).
Confirming our main hypothesis, findings indicated that surgeries with awl-tipped pedicle screws took less time (mean [SD] = 94.35 [24.09] minutes) than surgeries with conventional pedicle screws that required tapping (mean [SD] = 111.11 [33.00] minutes; t 408 = 5.87, P < 0.001; Figure 1). Viewed another way, surgeries that used awl-tipped screws were on average 15% briefer than those that used conventional screws. This same main finding held across all 4 fusion levels (Figure 2). Compared with those using conventional screws, surgeries using awl-tipped screws were briefer for 1-, 2-, 3-, and 4-level fusions, though there were very few 4-level fusion patients. Table 1 lists mean surgery times across screw type and fusion level.
Briefer open lumbar fusion surgeries with awl-tipped screws (n = 205) compared with conventional screws (n = 205) that require tapping. * t 408 = 5.87, P < 0.001, n = 205.
Briefer open lumbar fusion surgeries with awl-tipped screws compared with conventional screws that require tapping. 1-level fusion, n = 100 for each group; 2-level fusion, n = 74 for each group; 3-level fusion, n = 28 for each group; and 4-level fusion, n = 3 for each group.
Reduced open lumbar fusion surgery times (in minutes) for awl-tipped vs conventional screws that require tapping.
The amount of blood loss did not differ significantly between the 2 surgery groups but trended in the expected direction. Surgeries that used awl-tipped screws produced slightly less blood loss (mean [SD] = 195.98 [215.06] mL) on average than surgeries that used conventional screws (mean [SD] = 198.34 [202.45] mL; t 408 = 0.12, P = 0.91; Table 2 for mean blood loss across screw type and fusion level). The SD was larger than the mean for blood loss because although most surgeries had relatively little blood loss, some had relatively high blood loss.
Comparable blood loss (in milliliters) in open lumbar fusion surgeries using awl-tipped and conventional screws that require tapping.
Finally, we demonstrated that the main findings replicated. First, we randomly sorted our sample into 2 replication subsamples via the select cases function in SPSS. Replication group 1 was composed of 205 patients, and replication group 2 was composed of the remaining 205 patients. For replication group 1, surgeries with awl-tipped screws took less time (mean [SD] = 95.28 [25.99] minutes) than surgeries with conventional screws (mean [SD] = 113.11 [31.43] minutes; t 203 = 4.43, P < 0.001. The same finding held for replication group 2; surgeries with awl-tipped screws took less time (mean [SD] = 93.39 [22.06] minutes) than surgeries with conventional screws (mean [SD] = 109.16 [34.49] minutes; t 203 = 3.89, P < 0.001).
For replication group 1, surgeries with awl-tipped screws lost statistically equivalent amounts of blood (mean [SD] = 187.98 [246.78] mL) as surgeries with conventional screws (mean [SD] = 186.83 [179.93] mL; t 203 = −0.04, P = 0.97). The same held for replication group 2: surgeries with awl-tipped screws lost statistically equivalent amounts of blood (mean [SD] = 204.21 [177.45] mL) as surgeries with conventional screws (mean [SD] = 209.52 [222.46] mL; t 203 = 0.19, P = 0.85).
Discussion
Findings confirmed one of our hypotheses. Surgical time was significantly lower when using awl-tipped pedicle screws compared with conventional pedicle screws that required tapping. By fusion level, awl-tipped screws were associated with operative time reductions of approximately 20% for 1-level fusions, 14% for 2-level fusions, 1% for 3-level fusions, and 20% for 4-level fusions compared with conventional screws. Blood loss was lower with awl-tipped screws, but that finding did not reach statistical significance. Both the significant finding regarding surgical time and the nonsignificant finding regarding blood loss replicated within our sample. The surgical time saved by awl-tipped screws may translate in multiple ways, including increased surgical efficiency and fewer surgical complications. By documenting that this main result holds across 2 subsamples, our study adds objective support to what might otherwise remain an anecdotal or intuitive assumption.
Regarding complications, it has been well substantiated that increased surgical times are associated with increased risk of complications.2 In a study that documented 2320 patients who underwent lumbar spine surgery, results showed that perioperative complications were positively associated with increased operative times.2 A 2018 meta-analysis that examined all types of surgery found that each 1 minute of additional surgical time increased the odds of complications by 1%.3 Given that awl-tipped screws reduce surgical time by an average of 16.76 minutes, one might reasonably hypothesize that the use of awl-tipped pedicle screws may reduce the incidence of overall complications by a significant margin. Reducing surgical times may affect the likelihood of complications in a number of ways. For example, reducing surgical time reduces anesthesia exposure, and prolonged anesthesia increases the risk of overall complications, including pulmonary complications, cardiac complications, and sepsis.4
Reducing surgical time may also have monetary benefits. A 2005 US study, for example, found the cost per minute of operating room time to be just over $66 USD,5 which translates to $109 in 2024 dollars.6 This analysis included all expenses except for surgeon’s fees, so the true cost is almost certainly higher. Considering that surgeons in the United States perform more than 400,000 spinal fusion surgeries annually,7 the conservative annual savings to the US health care system would be just over $700 million every year. Considered another way, each surgeon using these screws would save time, opening opportunities to care for additional patients.
Limitations
This sutdy is not without limitations. Although it is not a randomized controlled trial, it is a valuable study that includes matched controls, and it fills a gap in the literature surrounding awl-tipped screws and the reduction in surgery time. Future research may investigate the time savings within an even more rigorous methodological design. Though that study would have clear benefits, it would lack the real-world application that the current study captures. Another limitation is that this study reports on data from a single institution. Surgical practices, patient populations, and equipment may differ at other centers; therefore, future multicenter studies are warranted to confirm the generalizability of these findings. It will be important to investigate the extent to which this finding generalizes across practices throughout the United States and across the world.
There are also a couple of technical limitations. For example, intraoperative blood loss was recorded using surgeon estimates, which is a common practice, though future work incorporating volumetric or gravimetric methods could provide greater precision. Also, specific spinal levels were not recorded in this study; future research with larger samples stratified by individual spinal levels may help clarify whether operative time varies by location. Another important future direction involves determining precisely where the time savings is observed. How much time is saved because of not having to tap prior to screw placement? Is any time saved because of a particular thread pitch, handle ergonomics, or perhaps some combination of factors?
Conclusion
Across a study of 205 patients with 205 matched controls, awl-tipped pedicle screws reduced operative time during the screw insertion phase, corresponding to an approximate 15% reduction in overall surgical time. This finding held across a number of levels fused. In addition, awl-tipped screws reduced blood loss by a nonsignificant amount. However, it is important to note that this study focused on the short-term benefits of using awl-tipped screws. Additional work is needed to investigate the long-term benefits or complications associated with using awl-tipped screws. While there is a lot of potential in this new technology, more work is needed to detail all of the benefits and drawbacks of these screws.
Footnotes
Funding Multiple authors (S.B., J.M., G.K., and A.F.) were supported by The Summer Program in Orthopedic Spine Research, which was funded by Medtronic via an educational grant: Medtronic MDT230030833. This grant did not support this particular research.
Declaration of Conflicting Interests The authors have no conflicts of interest to disclose.
Ethics Approval This study was approved by an institutional review board CCC# 43050/DDD# 605423.
- This manuscript is generously published free of charge by ISASS, the International Society for the Advancement of Spine Surgery. Copyright © 2026 ISASS. To see more or order reprints or permissions, see http://ijssurgery.com.
References
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