Improved lag screw positioning in the treatment of proximal femur fractures using a novel computer assisted surgery method: a cadaveric study

Poor usability of computer-assisted navigation for hip fracture surgery

INTRODUCTION

The STRYKER ADAPT computer-assisted navigation system provides intraoperative feedback to the surgeon regarding implant placement of the Gamma3 nail. The usability of the ADAPT system has not been evaluated. The aim of the study was to investigate the perceived usability of the ADAPT system.

MATERIALS AND METHODS

This was a descriptive study with prospectively collected data. ADAPT was introduced at Aarhus University Hospital in February 2021. Prior to introduction, surgeons at the department attended a general introduction to the system. ADAPT was introduced to the surgical nurses and was on display at the surgical ward at more than one occasion, where personal introduction to the system was possible. After introduction, it was mandatory to use ADAPT when using the Gamma3 nail to treat intertrochanteric femur fractures. After each procedure, primary and an eventual supervisor answered a questionnaire, which encompassed the System Usability Scale (SUS) questionnaire. The SUS is a ten-item questionnaire regarding the perceived usability of a system. SUS scores were translated to adjectives, describing user experience on a 7-point adjective scale (worst imaginable, awful, poor, ok, good, excellent, best imaginable). User acceptability, defined as "not acceptable", "marginal" or "acceptable", was also used to interpret the SUS scores.

RESULTS

ADAPT was used in 50 procedures by 29 different surgeons, with varying skill-level. Median SUS-score after first-time use of ADAPT for all 29 surgeons was 43 (range: 5-60), which translated to "poor" or "not acceptable". For surgeons who performed ≥ 3 ADAPT-assisted procedures, there were no statistically significant difference in their first to latest SUS-score (median difference: 4.3, p = 0.5). In free text comments ADAPT was positively described as helpful in placement of K-wire and providing educational opportunities for inexperienced surgeons and negatively as inconsistent, slow, time consuming, and causing excessive fluoroscopy.

CONCLUSIONS

Usability and acceptability of ADAPT was rated as "poor" or "not acceptable" by the majority of operating surgeons. ADAPT has not been used at our institution based on these findings. The System Usability Scale may be used in further research exploring usability and acceptability of novel computer-assisted navigation systems for orthopaedic surgery.

Does computer-assisted orthopaedics system (ADAPT system) improve outcomes of intertrochanteric hip fractures?

INTRODUCTION

Intramedullary nailing (IMN) is a general treatment for intertrochanteric hip fractures. The computer-assisted orthopaedics system (CAOS), ADAPT system (Stryker, NJ), has been developed to facilitate lag screw insertion. When compared to the conventional freehand method, the efficacy of CAOS has not been clearly clarified. Therefore, we conducted this systematic review and meta-analysis to answer: does the CAOS performed better than freehand method in IMN.

MATERIALS AND METHODS

Studies published up to January 2023 were searched in the PubMed, Embase, Web of Science and Cochrane Library databases with predetermined key words. Comparative clinical studies between CAOS (ADAPT system) and freehand method were included. The primary outcomes of interest were the tip-apex-distance (TAD) and positions of lag screw. Fluoroscopy use, operation duration and intraoperative/postoperative complications were also extracted. A meta-analysis was performed for pooled analysis.

RESULTS

There were seven studies with 326 fractures in CAOS group and 325 fractures in Freehand group. All studies included presented high qualities. The CAOS group showed a statistically smaller TAD than Freehand group (weighted mean difference = -3.24 mm; 95% confidence interval [CI] -5.10 to -1.37 mm; p = 0.0007) and a better lag screw position (83/92 [90.2%] VS 64/92 [69.6%]; RR = 1.3; 95% CI 1.12 to 1.51; p = 0.0007). The operative time and radiation use revealed no difference between two groups.

CONCLUSIONS

The current evidence indicated that ADAPT system could help to perform a more accurate lag screw than freehand manipulation while the operative time and radiation time was not reduced as expectations on such new technique. Long-term follow-up studies are appealed.

Improving Cephalad Lag Screw Placement in the Femoral Head During Cephalomedullary Nailing Using a Novel Augmented Reality System

OBJECTIVES

To measure the effect of a novel augmented reality software designed to aid in lag screw placement into the femoral head for cephalomedullary nails.

DESIGN

Retrospective cohort study.

SETTING

Single Level I trauma center.

PATIENTS

Between November 2017 and December 2020, 114 consecutive patients with a hip fracture that underwent repair with a cephalomedullary nail by one of 2 orthopaedic trauma surgeons were reviewed. Fracture classifications included OTA/AO 31-A1, 31-A2, 31-A3, and 31-B3.

INTERVENTION

The first 57 patients underwent fracture repair without the software (control) and the subsequent 57 patients underwent repair with use of the augmented reality software (AR).

MAIN OUTCOME MEASUREMENTS

Tip apex distance (TAD) and femoral head zone (AP: superior, center, inferior; Lateral: anterior, center, posterior) were measured using standardized techniques.

RESULTS

The mean TAD was lower for the AR versus control cohort (10.7 ± 2.9 mm vs. 15.4 ± 3.8 mm; P < 0.001). TAD <10 mm for AR versus control: 25 (43.9%) versus 3 (5.3%), P < 0.001. TAD <15 mm for AR versus control: 50 (87.7%) versus 44 (77.2%), P < 0.001. On the AP view, center position was achieved in 50.9% versus 7.0% of cases for the AR versus control cohort, respectively. On the lateral view, center position was achieved in 68.4% versus 12.3% of cases for the AR versus control cohort, respectively.

CONCLUSION

This study suggests that use of the novel augmented reality software for assistance in lag screw positioning within the femoral head improves overall TAD and ability to achieve the center-center position.

LEVEL OF EVIDENCE

Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Navigated intramedullary nailing for patients with intertrochanteric hip fractures is cost-effective at high-volume hospitals in mainland China: A markov decision analysis

Objective

Previous studies have reported that navigation systems can improve clinical outcomes of intramedullary nailing (IMN) for patients with intertrochanteric fractures. However, information is lacking regarding the relationship between the costs of navigated systems and clinical outcomes. The present research aimed to evaluate the cost-effectiveness of navigated IMN as compared with traditional freehand IMN for patients with intertrochanteric fractures.

Methods

A Markov decision model with a 5-year time horizon was constructed to investigate the costs, clinical outcomes and incremental cost-effectiveness ratio (ICER) of navigated IMN for a 70-year-old patient with an intertrochanteric fracture in mainland China. The costs [Chinese Yuan (¥)], health utilities (quality-adjusted life-years, QALYs) and transition probabilities were obtained from published studies. The willingness-to-pay threshold for ICER was set at ¥1,40,000/QALY following the Chinese gross domestic product in 2020. Three institutional surgical volumes were used to determine the average navigation-related costs per patient: low volume (100 cases), medium volume (200 cases) and high volume (300 cases).

Results

Institutes at which 300, 200 and 100 cases of navigated IMN were performed per year showed an ICER of ¥43,149/QALY, ¥76,132.5/QALY and ¥1,75,083/QALY, respectively. Navigated IMN would achieve cost-effectiveness at institutes with an annual volume of more than 125 cases.

Conclusions

Our analysis demonstrated that the navigated IMN could be cost-effective for patients with inter-trochanteric fracture as compared to traditional freehand IMN. However, the cost-effectiveness was more likely to be achieved at institutes with a higher surgical volume.

ADAPT system is a dramatic advance in computer-assisted surgery for femoral trochanteric fractures

Introduction: In recent years, computer-assisted surgery has made it possible to undergo surgery with a high degree of precision. This study aimed to investigate the usefulness of computer-assisted surgery for femoral trochanteric fractures using the ADAPT (ADAptive Positioning Technology) system. Methods: A total of forty patients with femoral trochanteric fracture underwent intramedullary nailing for fracture fixation: in twenty patients, the ADAPT system (ADAPT group), and in the other twenty, it was not used (control group). The operative time, intraoperative fluoroscopy time, tip apex distance (TAD), and tip to head surface distance (TSD) were measured and compared between the two groups to assess the efficiency and accuracy of the surgery. Results: The operative time was significantly shorter (P < 0.05), intraoperative fluoroscopy time was significantly reduced (P < 0.01), and implant placement was significantly better in the ADAPT group (P < 0.01). Conclusion: Navigation systems have been developed to improve the efficiency of surgery. The ADAPT system was considered a very useful device for intramedullary nailing of femoral trochanteric fractures, as it reduced the intraoperative fluoroscopy time and improved the accuracy of implant placement, also reducing the operative time.

Effect of a computer-assisted navigation system on the lag screw placement accuracy of less experienced surgeons

BACKGROUND

Femoral trochanteric fracture is treated by osteosynthesis using an angle-fixed implant. Lag screw cut-out is a postoperative complication, and a tip-apex distance (TAD) of 20 mm or shorter is recommended to prevent it. The use of a navigation system for lag screw placement has been reported, but the use and non-use of navigation systems by less experienced surgeons has not been assessed. The objective of this study was to retrospectively investigate the usefulness of a navigation system for short femoral nailing.

METHODS

The subjects were 101 patients with femoral trochanteric fracture treated by osteosynthesis at our hospital between May 2017 and December 2018 (male, 14; female, 87; mean age, 84.7 years; navigation use group, 55; non-navigation use group, 46). The patients were divided into four groups: groups treated by less experienced surgeons with (Navigation-Young surgeon [NY] group, n = 35) and without (Manual-Young surgeon [MY] group, n = 23) the use of a navigation system; and groups treated by experienced surgeons with (Navigation-Aged surgeon [NA] group, n = 20) and without (Manual-Aged surgeon [MA] group, n = 23) the use of a navigation system. TAD (mm) and operative time (min) were compared.

RESULTS

The TAD was significantly longer in the MY group than in the NY group. The percentages of patients with 10-20 mm TAD were as follows: NY group, 94.3%; MY group, 65.2%; NA group, 100%; MA group, 100%. The mean operative time was significantly longer in the NY group than in the MA group, but no significant difference in mean operative time was noted between the NY and MY groups or between the NA and MA groups.

CONCLUSIONS

A computer-assisted navigation system improves the accuracy of lag screw placement performed by less experienced operators without increasing the operative time.

Generic Implant Positioning Technology Based on Hole Projections in X-Ray Images

Implant placement plays a key role in trauma and orthopedics. In this paper, a generic technological concept for implant positioning assistance is outlined. The system utilizes conventional radiographic devices for imaging and tracking and embeds into surgical workflows without the need for complex navigation equipment. It is based on feature extraction from cylindrical hole-projections in X-ray images for determining spatial alignment of implant and anatomy. Basic performance of a prototype system was experimentally verified in terms of tracking accuracy and robustness under varying conditions. In a second step, the system was developed into a set of application modules, each serving a pressing clinical need: Plating of the proximal humerus, cephalic nail and dynamic hip-screw placement, general anatomic plating, distal nail interlocking with adjustment of femoral anteversion and corrective osteotomies. Module prototypes were tested according to their degree of maturity from feasibility assessment in wet-labs to clinical handling tests. Orientation tracking of reference objects yielded an accuracy and precision of 0.1±0.71 deg (mean±standard deviation) with a maximum error of 4.68 deg at unfavorable conditions. This base-performance translated, e.g., into a precision of ±1.2 mm (standard deviation) screw-tip to joint distance at proximal humerus plating, or into a precision of lag screw positioning in the femoral head of ±0.6 mm in craniocaudal and ±1.6 mm in anterioposterior direction. The concept revealed strong potential to improve surgical outcomes in a broad range of orthopedic applications due to its generic and simplistic nature. Comprehensive validation activities must follow for clinical introduction.

Does Computer-assisted Surgery Improve Lag Screw Placement During Cephalomedullary Nailing of Intertrochanteric Hip Fractures?

BACKGROUND

Computer-assisted surgery (CAS) techniques have been shown to improve implant placement and reduce the radiation time during cephalomedullary nailing in cadaveric and pilot clinical studies of intertrochanteric hip fractures. However, clinical comparisons of CAS and conventional techniques are lacking. It is unclear whether CAS offers clear advantages in terms of radiation time, operative time, and accuracy of lag-screw placement in patients undergoing surgery for intertrochanteric hip fractures and whether any potential difference in accuracy is associated with a change in the risk of lag-screw cut-out postoperatively.

QUESTIONS/PURPOSES

In patients undergoing cephalomedullary nailing for intertrochanteric hip fractures compared with the conventional technique, we asked: (1) Is the CAS technique associated with a decrease in tip-apex distance (TAD), with less variation and fewer outliers at the standard (25 mm) and lower (15 mm) TAD thresholds? (2) Is the CAS technique associated with a decrease in radiation and operative time? (3) If the CAS technique results in a decrease in TAD, is this decrease associated with a decrease in lag screw cut-out postoperatively?

METHODS

Between Oct 2007 and June 2015, 964 stable and unstable intertrochanteric hip fractures were treated surgically at our institution. Of these, 23% (225 of 964) were isolated, acute intertrochanteric hip fractures managed by a single surgeon. Ninety-five percent (213 of 225) of hip fractures were surgically treated with the same cephalomedullary nail based on the general indications of displaced fractures, poor bone quality, and medical complexity. This same surgeon used a sliding hip screw device in the remaining 5% (12 of 225) of hip fractures for the treatment of nondisplaced and minimally displaced fractures in younger patients with fewer medical comorbidities and good bone quality. Between October 2007 and August 2011, all procedures were performed with conventional lag screw placement (n = 110), and between September 2011 and June 2015, all procedures were performed with CAS (n = 103) for lag screw placement. Postoperative radiographs were missing or unavailable for TAD analysis for 3% (3 of 110) of the conventional technique group and 6% (6 of 103) of the CAS group, so these patients were excluded. The remaining 97% (107 of 110) of conventional procedures and 94% (97 of 103) of CAS procedures were included in the TAD, radiation time, and operative time analysis. For the evaluation of cut-out postoperatively, 24% (26 of 107) of conventional patients and 25% (24 of 97) of CAS patients were excluded due to mortality and/or loss to follow-up at a minimum of 1 year. The remaining 76% (81 of 107) of conventional patients and 75% (73 of 97) of CAS patients were included in the cut-out analysis. A retrospective chart review was performed to obtain the data and then compare TAD, radiation time, operative time, and cut-out between the two cohorts.

RESULTS

The median TAD for the CAS procedures was lower than the median TAD for the conventional procedures (median 13 mm versus median 16 mm, median difference 3 mm; p < 0.001 power for difference = 85%). In addition, the TAD variation was also less for the CAS procedures compared with the conventional procedures (interquartile range [IQR] 4 mm versus IQR 9 mm, IQR difference 5 mm; p < 0.001, power for difference = 98%). A TAD greater than 25 mm was found in 1% (1 of 97) of the CAS procedures and 12% (13 of 107) of the conventional procedures. A difference between the proportions could be detected indicating a lesser chance of a TAD > 25 mm in the CAS cohort (odds ratio = 0.075 [95% confidence interval 0.010 to 0.587]; p = 0.002, power for difference 90%). A TAD > 15 mm was found in 23% (22 of 97) of the CAS procedures and 56% (60 of 107) of the conventional procedures, also indicating a lesser chance of a TAD > 15 mm in the CAS cohort (OR = 0.230 [95% CI 0.125 to 0.423], relative risk for TAD > 15 mm = 0.404 [95% CI 0.270 to 0.606]; p < 0.001, power for difference > 99%). The median radiation time for the CAS cohort was lower than the median radiation time for the conventional cohort (median 1.4 minutes versus median 1.7 minutes, median difference 0.3 minutes; p = 0.002, power for difference = 81%). No difference in median total operating time was found for the CAS procedures compared with the conventional procedures (median 36 minutes versus median 38 minutes, median difference 2 minutes; p = 0.227, power for difference = 18%, power for equivalency = 93%). There was no difference in cut-out noted with the use of the CAS compared with the conventional technique with the numbers available. Based on the current results, the upper 95% probability for a cutout complication ranges from 0% to 5% in the CAS cohort versus 0% to 9% in the conventional cohort (difference of upper 95% CI = 4%).

CONCLUSION

CAS use is associated with a decrease in median TAD with less variation and fewer outliers during cephalomedullary nailing. Compared with the conventional technique, fewer outliers were noted with the CAS at the standard TAD threshold of 25 mm and a lower TAD threshold of 15 mm. Additional research is needed to determine the association of TAD variation and outliers on cut-out and to determine if there is any clinical value to the decrease in TAD variation and outliers noted here. The patient and surgical team are exposed to less radiation with the CAS compared with the conventional technique, but this difference is small and it is unclear if this benefit justifies CAS use. Incorporating CAS into the cephalomedullary nailing procedure is not associated with a change in operative time, so there are no costs or risks associated with increased operative time. More procedures would be needed to provide adequate power to better analyze the risk of lag screw cut-out, allowing a more complete understanding of the value of this technology compared with its cost.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Comparing the usefulness of a fluoroscopic navigation system in femoral trochanteric fracture for orthopaedic residents with the conventional method

INTRODUCTION

Lag screw insertion into the ideal position is essential to obtain good results in open reduction and internal fixation for femoral trochanteric fracture. Tip-apex distance (TAD) is a widely adopted method for evaluating the risk of lag screw cut-out. Adaptive positioning technology (ADAPT) is a fluoroscopic computer-assisted surgery system that enables orthopaedic surgeons to guide the screw into a proper position intraoperatively. A randomized control study concluded that ADAPT resulted in excellent TAD. However, it was not significantly better than conventional methods when performed by fellowship-trained traumatologists. Therefore, we hypothesised that ADAPT would be useful to orthopaedic residents and evaluated this usefulness.

METHODS

We reviewed 102 patients who underwent open reduction and internal fixation for femoral trochanteric fracture from May 2017 to March 2019 using Gamma-3 intertrochanteric nails. Two residents performed all procedures; 51 patients underwent surgery using ADAPT and the others underwent surgery without navigation. The number of attempts to drill guide-wire, operation time, lag screw insertion time, radiation exposure time, TAD, and lag screw position were evaluated for each surgeon.

RESULTS

In one resident, when using the ADAPT system, the number of attempts to drill guide-wire (p=0.001), lag screw insertion time (p=0.000), radiational exposure time (p=0.009) and TAD (p=0.007) were lower, and the percentage of ideal lag screw position (p=0.035) were better than that in the conventional method. However, there was no significant difference in the performance of another resident with respect to the aforementioned factors, whether using ADAPT or not.

CONCLUSION

One resident showed better results with the ADAPT system than with conventional osteosynthesis. However, another resident received no benefit from ADAPT. The efficiency may not apply to everyone as individual competence can influence efficiency when using ADAPT system. Therefore, as a new device, it must be used cautiously because skill or experience may influence its use, especially by orthopaedic residents.

How to get better TAD? Relationship between anteversion angle of nail and position of femoral neck guide pin during nailing of intertrochanteric fractures

Background

To demonstrate the correlation between guide pin-shaft angle (PSA) at the anteroposterior film and anteversion angle of guide pin at the lateral film and investigate whether excellent tip–apex distance (TAD) can be obtained by changing the entry point via axial rotation of the main intramedullary nail.

Methods

Fifty patients with intertrochanteric femoral fractures (IFFs) undergoing internal fixation with intramedullary nails under 2D fluoroscopy were retrospectively enrolled. Both of the PSA at the anteroposterior film and anteversion angle at the lateral film before and after adjustment of the guide pin were collected. Pearson correlation analysis was performed to investigate their correlation. Intraoperative and postoperative outcomes were recorded. Furthermore, the software of Mimics 10.0 and Pro/E were used to establish the 3D models of the proximal femur and main intramedullary nail/guide pin, respectively. Surgery was simulated on the Pro/E software platform and solid geometry analysis was conducted to calculate the correlation between the PSA and the anteversion angle.

Results

Pearson correlation analysis indicated there was a positive correlation between PSA and anteversion angle, with the correlation coefficient of 0.902 (p < 0.01). By altering the PSA and anteversion angle, TAD was adjusted to be less than 25 mm in all patients. The mean operative time, fluoroscopy time and length of hospital stay were 65.82 ± 11.16 min, 2.03 ± 0.79 min and 6.66 ± 2.49 d. Thirty-one patients received blood transfusions (3.55 ± 1.95 U). Fracture reduction was considered to be good or acceptable in all patients. Complications occurred only in 6 patients (12.00%). At a 3-month follow-up, the mean Timed Up and Go was 31.54 ± 20.95 s and Harris Hip Score was 72.88 ± 8.79. The 3D surgery model also showed when the main intramedullary nail was externally rotated or internally rotated of 20° at the standard location, the PSA of guide pin at the anteroposterior position and anteversion angle of the guide pin at the lateral position were simultaneously increased or decreased.

Conclusion

Our findings suggest altering the PSA and anteversion angle may be beneficial for obtaining excellent TAD and achieving superior outcomes.

Evolution of imaging in surgical fracture management

Intraoperative imaging has been advanced substantially over the last decades. It supports localization of the region of interest, verification of the preoperatively classified fracture pattern, identification of correct insertion point of the implant, placement of instruments and fixation material, and verification of correct fracture reduction and implant positioning. While conventional fluoroscopic 2D imaging remains the gold standard in intraoperative imaging, critical anatomical regions are predestined for intraoperative 3D imaging. Additional options such as perioperative virtual planning, simulation, and surgical training, 3D printing techniques and 3D augmented reality visualization may potentially open new windows to improve surgical results in fracture care. This manuscript presents an update on current and upcoming imaging techniques in orthopaedic and trauma surgery focusing on technical advances for decreasing malreduction, malalignment, and malposition, as well as tips and tricks for daily surgical practice in order to improve clinical outcomes and patients' and surgeons' safety.

Fluoroscopic Marker-Based Guidance System Improves Gamma Lag Screw Placement During Nailing of Intertrochanteric Fractures: A Randomized Controlled Trial

OBJECTIVES

To determine whether a fluoroscopy-based navigation system would improve tip-apex distance (TAD) compared with the conventional technique.

DESIGN

Randomized controlled trial.

SETTING

Level 1 trauma center.

PATIENTS

A total of 161 patients were screened for inclusion in the study. After meeting inclusion and exclusion criteria, 31 patients were randomized (n = 18 navigated vs. n = 13 control group), with the patient blinded to the result.

INTERVENTION

Fluoroscopy-based navigated guidance of lag screw length and position.

MAIN OUTCOME MEASURES

Average TAD and the proportion of TAD over 25 mm.

RESULTS

TAD was lower in the navigated group compared with the control group (mean = 17.5 vs. 24.2 mm; P = 0.0018). No navigated cases exceeded the 25 mm TAD threshold, compared with 39% of conventional cases (P = 0.0076). Navigation resulted in fewer drilling attempts compared with the conventional technique (median = 1 vs. 4 attempts; P < 0.0001). We detected no significant differences in operation time or total number of fluoroscopic images (P > 0.05).

CONCLUSIONS

Fluoroscopy-based computer navigated Gamma nailing for intertrochanteric fractures improved TAD and reduced the number of drilling attempts without increasing operation time compared with the conventional fluoroscopy-guided technique in a teaching hospital setting.

LEVEL OF EVIDENCE

Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence.

[Evolution and principles of intramedullary locked nailing]

Key factors for successful osteosynthetic fracture stabilization are anatomical fracture reduction, restoration of axis and torsion alignment as well as tissue-preserving operative techniques. In long bone fractures, the use of intramedullary long bridging nailing offers ideal conditions for bone healing, as axial and rotational stability is provided by canal-filling nails and locking screws. In addition, the tissue in the fracture region is protected as the intramedullary nail insertion is distant from the fracture. The indication spectrum for modern intramedullary locked nailing includes diaphyseal fractures of long bones, metaphyseal fractures and reconstructions, as well as treatment of nonunion, osteotomy and arthrodesis of the lower extremities. Continuous improvements in nail design and instrumentation as well as the introduction of anatomical reconstruction nails will optimize the spectrum and effectiveness of intramedullary osteosynthesis even further.

Optimising the tip-apex-distance in trochanteric femoral fracture fixation using the ADAPT-navigated technique, a longitudinal matched cohort study

INTRODUCTION

The annual incidence of proximal femoral fractures is 100-150/100,000 and continues to increase with an aging population. Cut-out of hip screws after fracture fixation has been quoted as 8% in the literature. The tip-apex distance (TAD) is the strongest predictor for cut-out after operative fracture stabilisation. The aim of this study was to evaluate the novel ADAPT system (Adaptive Positioning Technology, Stryker, USA), a navigation device for intramedullary nailing of trochanteric fractures and its effect on optimising the TAD. This is the first clinical study to evaluate this new technology.

METHODS

The study group of 36 consecutive patients with a pertrochanteric fracture underwent intramedullary nailing for fracture fixation using ADAPT technology, while the matched control group underwent conventional Gamma-3-nailing. Matching criteria included fracture classification, gender and age. We measured the operative time and the postoperative TAD in anteroposterior (AP) and lateral radiographs of the 72 patients.

RESULTS

The mean TAD using ADAPT was 16.9 mm (range 8.4-33.7 mm) compared with 24.9 mm (range 14.6-40.2 mm) in the reference group treated without ADAPT. Using the ADAPT system significantly improved (p < 0.0005) the accuracy of lag screw placement but had no effect on operating time in fixation of femoral pertrochanteric fractures.

CONCLUSION

Working with the novel ADAPT system for positioning the lag screw using the Gamma-3-nail led to a statistically highly significant reduction of the TAD compared to the reference group (p < 0.001). The ADAPT system proved to be a very useful device in achieving higher surgical standards for the treatment of trochanteric fractures with intramedullary nailing. It enables higher accuracy in screw positioning and therefore better placement of the implant.

Accuracy analysis of computer-assisted surgery for femoral trochanteric fracture using a fluoroscopic navigation system: Stryker ADAPT® system

PURPOSE

ADAPT is a fluoroscopic computer-assisted surgery system which intraoperatively shows the distance from the tip of the screw to the surface of the femoral head, tip-to-head-surface distance (TSD), and the tip-apex distance (TAD) advocated by Baumgaertner et al. The study evaluated the accuracy of ADAPT.

PATIENTS AND METHODS

A total of 55 patients operated with ADAPT between August 2016 and March 2017 were included as subjects. TSD and TAD were measured postoperatively using computed tomography (CT) and X-rays. The intraclass correlation coefficient (ICC) was checked in advance. The error was defined as the difference between postoperative and intraoperative measurement values of ADAPT. Summary statistics, root mean square errors (RMSEs), and correlations were evaluated.

RESULTS

ICC was 0.94 [95% CI: 0.90-0.96] in TSD and 0.99 [95% CI: 0.98-0.99] in TAD. The error was -0.35 mm (-1.83 mm to 1.12 mm) in TSD and +0.63 mm (-5.65 mm to 4.59 mm) in TAD. RMSE was 0.63 mm in TSD and 1.53 mm in TAD. Pearson's correlation coefficient was 0.79 [95% CI: 0.66-0.87] in TSD and 0.83 [95% CI: 0.72-0.89] in TAD. There were no adverse events with ADAPT use.

CONCLUSION

ADAPT is highly accurate and useful in guiding surgeons in properly positioning the screws.

Numerical Optimization of the Position in Femoral Head of Proximal Locking Screws of Proximal Femoral Nail System; Biomechanical Study

Background:

Proximal femoral fracture rates are increasing due to osteoporosis and traffic accidents. Proximal femoral nails are routinely used in the treatment of these fractures in the proximal femur.

Aims:

To compare various combinations and to determine the ideal proximal lag screw position in pertrochanteric fractures (Arbeitsgemeinschaft für Osteosynthesefragen classification 31-A1) of the femur by using optimized finite element analysis.

Study Design:

Biomechanical study.

Methods:

Computed tomography images of patients’ right femurs were processed with Mimics. Afterwards a solid femur model was created with SolidWorks 2015 and transferred to ANSYS Workbench 16.0 for response surface optimization analysis which was carried out according to anterior-posterior (-10°<anterior-posterior<10°), inferior-superior (-6°<inferior-superior<7°) and tip-apex distance (10 mm<tip-apex distance<30 mm) proximal lag screw positions in the fracture region. The optimum position of the proximal lag screw was determined based on the von Mises stress values occurring on the fracture line. Initial analysis of the system was realized under the surgeon’s normal positioning conditions (anterior-posterior, inferior-superior=0°; tip-apex distance=12 mm).

Results:

The maximum and minimum (compression) von Mises stresses were found to be 438 MPa and 0.003 MPa, respectively, and risky stresses for the system occurred in the regions where the proximal lag screw passes through the proximal femoral nail hole, the small diameter portion of stem joints with a large diameter and lag screw mounts to the stem. The most suitable position of the proximal lag screw was found at the middle position of the tip-apex distance (20 mm) and femoral neck (anterior-posterior, inferior-superior=0°), according to von Mises compression stress values occurring on the fracture line.

Conclusion:

In our study, we couldn’t find any correlation between proximal lag screw movement and tip-apex distance on stresses of the fracture surfaces, but the proximal lag screw position in the inferior (inferior-superior<0)-superior (inferior-superior>0) and posterior-anterior directions of the femur neck significantly increased these stresses. The most suitable position of the proximal lag screw was confirmed as the middle of the femoral neck by using optimized finite element analysis.

[Clinical application of computer-assisted cannulated screw internal fixation system based on error correction method for femoral neck fractures]

Objective

To investigate the clinical efficacy of computer-assisted cannulated screw internal fixation system based on error correction method for femoral neck fractures.

Methods

A retrospective analysis was made on the clinical data of 20 femoral neck fracture patients treated by computer-assisted cannulated screw internal fixation system based on error correction method between January 2014 and October 2015 (trial group), and 36 femoral neck fracture patients undergoing traditional manual surgery with closed reduction by cannulated screw fixation in the same period (the control group). There was no significant difference in gender, age, injury cause, side of fracture, types of fracture, and time from injury to operation between 2 groups ( P>0.05). The operation time, intraoperative blood loss, intraoperative frequency of fluoroscopy and guide pin insertion, fracture healing time, fracture healing rate, and Harris hip score were compared between 2 groups.

Results

All incisions healed by first intention after operation, and no complication of blood vessel and nerve injury occurred. The operation time of trial group was significantly longer than that of control group ( t=2.290, P=0.026), however, the intraoperative blood loss, intraoperative frequency of fluoroscopy and guide pin insertion of trial group were significantly less than those of control group ( t=-10.650, P=0.000; t=18.320, P=0.000; t=-16.625, P=0.000). All patients were followed up 12-18 months (mean, 14.7 months). X-ray films showed that fracture healing was obtained in 2 groups, showing no significant difference in fracture healing time between 2 groups ( t=0.208, P=0.836). No complication of ischemic necrosis of femoral head occurred during follow-up period. At last follow-up, the Harris hip score was 87.05±3.12 in trial group and was 86.78±2.83 in control group, showing no significant difference ( t=0.333, P=0.741).

Conclusion

Computer-assisted cannulated screw internal fixation surgery based on error correction method for femoral neck fractures is better than traditional manual surgery in decreasing intraoperative radiation and surgical trauma during operation.

Enhanced cephalomedullary nail lag screw placement and intraoperative tip-apex distance measurement with a novel computer assisted surgery system

OBJECTIVE

The goal of this study was to evaluate the ability of a novel computer assisted surgery system to guide ideal placement of a lag screw during cephalomedullary nailing and then accurately measure the tip-apex distance (TAD) measurement intraoperatively.

DESIGN

Retrospective case review.

SETTING

Level II trauma hospital.

PATIENTS

The initial 98 consecutive clinical cases treated with a cephalomedullary nail in conjunction with a novel computer assisted surgery system were retrospectively reviewed.

INTERVENTION

A novel computer assisted surgery system was utilized to enhance lag screw placement during cephalomedullary nailing procedures. The computer assisted surgery system calculates the TAD intraoperatively after final lag screw placement.

MAIN OUTCOME MEASURES

The ideal TAD was considered to be within a range of 5mm-20mm. The ability of the computer assisted surgery system (CASS) to assist in placement of a lag screw within the ideal TAD was evaluated. Intraoperative TAD measurements provided by the computer assisted surgery system were then compared to standard postoperative TAD measurements on PACS (picture archiving and communication system) images to determine whether these measurements are equivalent.

RESULTS

79 cases (80.6%) were available with complete information for a retrospective review. All cases had CASS TAD and PACS TAD measurements >5mm and<20mm. In addition, no significant difference could be detected between the intraoperative CASS TAD and the postoperative PACS TAD (p=0.374, Wilcoxon Test; p=0.174, paired T-Test). A cut-out rate of 0% was observed in all patients who were treated with CASS in this case series (95% CI: 0 - 3.01%).

CONCLUSIONS

The novel computer assisted surgery system tested here is an effective and reliable adjunct that can be utilized for optimal lag screw placement in cephalomedullary nailing procedures. The computer assisted surgery system provides an accurate intraoperative TAD measurement that is equivalent to the standard postoperative measurement utilizing PACS images.

LEVEL OF EVIDENCE

Therapeutic Level IV.