Background: Precise insertion of pedicle screws is important to avoid injury to closely adjacent neurovascular structures. The standard method for the insertion of pedicle screws is based on anatomical landmarks (free-hand technique). Head-mounted augmented reality (AR) devices can be used to guide instrumentation and implant placement in spinal surgery. This study evaluates the feasibility and precision of AR technology to improve precision of pedicle screw insertion compared to the current standard technique. Methods: Two board-certified orthopedic surgeons specialized in spine surgery and two novice surgeons were each instructed to drill pilot holes for 40 pedicle screws in eighty lumbar vertebra sawbones models in an agarbased gel. One hundred and sixty pedicles were randomized into two groups: the standard free-hand technique (FH) and augmented reality technique (AR). A 3D model of the vertebral body was superimposed over the AR headset. Half of the pedicles were drilled using the FH method, and the other half using the AR method. Results: The average minimal distance of the drill axis to the pedicle wall (MAPW) was similar in both groups for expert surgeons (FH 4.8 ± 1.0 mm vs. AR 5.0 ± 1.4 mm, p = 0.389) but for novice surgeons (FH 3.4 mm ± 1.8 mm, AR 4.2 ± 1.8 mm, p = 0.044). Expert surgeons showed 0 primary drill pedicle perforations (PDPP) in both the FH and AR groups. Novices showed 3 (7.5%) PDPP in the FH group and one perforation (2.5%) in the AR group, respectively (p > 0.005). Experts showed no statistically significant difference in average secondary screw pedicle perforations (SSPP) between the AR and the FH set 6-, 7-, and 8-mm screws (p > 0.05). Novices showed significant differences of SSPP between most groups: 6-mm screws, 18 (45%) vs. 7 (17.5%), p = 0.006; 7-mm screws, 20 (50%) vs. 10 (25%), p = 0.013; and 8-mm screws, 22 (55%) vs. 15 (37.5%), p = 0.053, in the FH and AR group, respectively. In novices, the average optimal medio-lateral convergent angle (oMLCA) was 3.23°(STD 4.90) and 0.62°(STD 4.56) for the FH and AR set screws (p = 0.017), respectively. Novices drilled with a higher precision with respect to the cranio-caudal inclination angle (CCIA) category (p = 0.04) with AR. Conclusion: In this study, the additional anatomical information provided by the AR headset superimposed to realworld anatomy improved the precision of drilling pilot holes for pedicle screws in a laboratory setting and decreases the effect of surgeon's experience. Further technical development and validations studies are currently being performed to investigate potential clinical benefits of the herein described AR-based navigation approach.

In our study, the revision rate was within the range of published results after ACL reconstructions. In over 90% of patients, the native ACL was preserved with no need for a secondary reconstruction. Most of the non-revision reinterventions were minor and included hardware removals and manipulations under anesthesia. The re-arthroscopy rate was lower than that after ACL reconstruction with fewer secondary meniscal sutures and partial meniscectomies. Early treatment of meniscal tears may be one crucial benefit of ACL repair with DIS.

Augmented reality-guided facet joint injections are feasible and accurate without potentially harmful needle placement in an experimental setting.

Background: Patients undergoing acute left main (LM) coronary artery revascularization have a high mortality and natriuretic peptides such as N-terminal pro-B-type (NT-proBNP) have been shown to have prognostic value in patients with acute coronary syndromes. The present study looked at the prognostic value of NT-proBNP in these patients. Methods and Results:We studied all consecutive patients undergoing acute LM coronary artery percutaneous coronary intervention between January 2005 and December 2008 in whom NT-proBNP was measured (n=71). We analyzed the clinical characteristics and the short- and long-term outcomes in relation to NT-proBNP level at admission. Median NT-proBNP was 1,364 ng/L, ranging from 46 to 70,000 ng/L. NT-proBNP was elevated in 63 (89%) patients and was ≥1,000 ng/L in 42 (59%). Log NT-proBNP (hazard ratio [HR] 3.51, 95% confidence interval [CI] 1.55-7.97, P=0.003) and left ventricular ejection fraction (HR 0.95, 95%CI 0.91-0.99, P=0.007) were predictors for all-cause mortality. Log NT-proBNP was the only independent significant predictor of cardiovascular mortality. In-hospital mortality was 0% for patients with NT-proBNP <1,000, but 17% for those with NT-proBNP ≥1,000 (P= 0.036). Conclusions:NT-proBNP is a strong predictor of outcome in patients undergoing acute LM coronary artery stenting. Mortality in such patients is high, but those with NT-proBNP <1,000 ng/L may have a favorable short- and longterm prognosis. Further research, including a larger patient population, is needed to determine the optimal cut-off value for NT-proBNP in patients undergoing acute LM coronary artery intervention. (Circ J 2011; 75: 2648 - 2653

Background An optimal osteotomy angle avoids shortening of the first metatarsal bone after hallux valgus surgery and therefore reduces the risk of transfer-metatarsalgia. The purpose of the present ex-vivo study was to investigate whether augmented reality (AR) would improve accuracy of the distal osteotomy during hallux valgus surgery. Methods Distal osteotomies of the first metatarsals were performed on a foot model by two surgeons with different levels of surgical experience each with (AR, n = 15 × 2) or without (controls, n = 15 × 2) overlay of a hologram depicting an angle of osteotomy perpendicular to the second metatarsal. Subsequently, the deviation of the osteotomy angle in the transverse plane was analyzed. Results Overall, AR decreased the extent of deviation and the AR guided osteotomies were more accurate (4.9 ± 4.2°) compared to the freehand cuts (6.7 ± 6.1°) by tendency (p = 0.2). However, while the inexperienced surgeon performed more accurate osteotomies with AR with a mean angle of 6.4 ± 3.5° compared to freehand 10.5 ± 5.5° (p = 0.02), no significant difference was noticed for the experienced surgeon with an osteotomy angle of around 3° in both cases. Conclusion This pilot-study suggests that AR guided osteotomies can potentially improve accuracy during hallux valgus correction, particularly for less experienced surgeons.

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Category: Bunion Introduction/Purpose: An optimal osteotomy angle can avoid shortening of the first metatarsal bone after hallux valgus surgery and therefore reduce the risk of transfer-metatarsalgia. Up to date the osteotomy is performed free-hand without guidance and is therefore prone to unwanted variability in accuracy. The purpose of the present ex-vivo study was to investigate whether overlaying a hologram (augmented reality, AR) would improve accuracy of the distal osteotomy during hallux valgus surgery. Methods: A polyamide foot skeleton was constructed based a CT scan of a cadaveric foot and covered with medical silicon soft tissue. Three different polyamide first metatarsals were inserted to simulate a light, moderate and severe hallux valgus deformity. Distal Osteotomies of the first metatarsals were performed by two surgeons with different levels of surgical experience each with (AR, n=15x2) or without (controls, n=15x2) overlay of a hologram depicting an angle of osteotomy perpendicular to the second metatarsal in the transverse plane. Subsequently, the deviation to the plumb line of the second metatarsal in the transverse plane of all 60 osteotomies angles were optically measured and statistically analyzed. Results: Overall, the AR-guided osteotomies were more accurate (4.9 ± 4.2°) compared to the freehand cuts (6.7± 6.1°) by tendency (p=0.2). However, while the inexperienced surgeon performed more accurate osteotomies with AR with a mean angle of 6.4± 3.5° compared to freehand 10.5 ± 5.5° (p=0.02), no significant difference was noticed for the experienced surgeon with an osteotomy angle of around 3° in both cases. Conclusion: This pilot-study suggests that augmented reality guided osteotomies can potentially improve accuracy during hallux valgus surgery, particularly for less experienced surgeons. However, clinical studies are needed to investigate the clinical benefit of augmented reality in hallux valgus surgery.

Background An optimal osteotomy angle avoids shortening of the first metatarsal bone after hallux valgus surgery and therefore reduces the risk of transfer-metatarsalgia. The purpose of the present ex-vivo study was to investigate whether augmented reality (AR) would improve accuracy of the distal osteotomy during hallux valgus surgery. Methods Distal osteotomies of the first metatarsals were performed on a foot model by two surgeons with different levels of surgical experience each with (AR, n=15x2) or without (controls, n=15x2) overlay of a hologram depicting an angle of osteotomy perpendicular to the second metatarsal. Subsequently, the deviation of the osteotomy angle in the transverse plane was analyzed. Results Overall, the AR decreased the range of impression and the AR guided osteotomies were more accurate (4.9 ± 4.2°) compared to the freehand cuts (6.7± 6.1°) by tendency (p=0.2). However, while the inexperienced surgeon performed more accurate osteotomies with AR with a mean angle of 6.4± 3.5° compared to freehand 10.5 ± 5.5° (p=0.02), no significant difference was noticed for the experienced surgeon with an osteotomy angle of around 3° in both cases. Conclusion This pilot-study suggests that AR guided osteotomies can potentially improve accuracy during hallux valgus correction, particularly for less experienced surgeons.