Patient-specific guide systems decrease the major perforation rate of pedicle screw placement in comparison to the freehand technique for adolescent idiopathic scoliosis.

PURPOSE: This study aimed to compare the accuracy of pedicle screw (PS) placement between a low-profile three-dimensional (3D) printed patient-specific guide system and freehand technique for adolescent idiopathic scoliosis (AIS) surgery. METHODS: Patients with AIS who underwent surgery between 2018 and 2023 at our hospital were included in the study. The 3D-printed patient-specific guide was used since 2021 (guide group). PS perforation was classified using Rao and Neo's classification (grade 0, no violation; grade 1, < 2 mm; grade 2, 2-4 mm; grade 3, > 4 mm). Major perforations were defined as grades 2 or 3. The major perforation rate of PS, operative time, estimated blood loss (EBL), and correction rate were compared between the two groups. RESULTS: A total of 576 PSs were inserted in 32 patients (20 patients in the freehand (FH) group and 12 patients in the guide group). The major perforation rate was significantly lower in the guide group than in the FH group (2.1% vs. 9.1%, p < 0.001). Significantly fewer major perforations were observed in the guide group than in the FH group in the upper thoracic (T2-4) region (3.2% vs. 20%, p < 0.001) and lower thoracic (T10-12) region (0% vs. 13.8%, p = 0.001). The operative time, EBL, and correction rate were equivalent between the two groups. CONCLUSION: The 3D-printed patient-specific guide notably reduced the major perforation rate of PS without increasing EBL and operative time. Our findings indicate that this guide system is reliable and effective for AIS surgery.

Computer-guided contouring of craniofacial fibrous dysplasia involving fronto-orbital or fronto-cranial region using patient specific surgical depth guide: A prospective case series.

The aim of this study was to introduce a new computer guided technique for debulking and contouring the craniofacial fibrous dysplasia involving the fronto-orbital and fronto-cranial regions. Computer-guided contouring was performed using a modified patient-specific surgical depth guide for six patients with craniofacial fibrous dysplasia involving the fronto-orbital and fronto-cranial regions. Virtual planning was performed to determine the desired amount of bone removal and construct the patient-specific surgical depth guide. Then, the guide was printed using rapid prototyping. In the surgical theatre, the guide was seated in position. Implant drills were inserted through the created depth holes according to the planned fixed depth to create depth holes. Finally, the bone in between the created holes was removed using cutting discs, bone chisels and surgical burs. Satisfaction with facial aesthetics was evaluated by the patients using a Likert scale, and by the surgeons using the Whitaker rating scale. The surgical procedures were uneventful for all the patients. All the patients were satisfied with the post-operative facial esthetics and categorized as category I Whitaker rating scale. Patient-specific surgical guide technique for recontouring of fronto-orbital and fronto-cranial fibrous dysplasia can be considered an accurate substitution technique that overcomes the drawbacks of the unpredictable conventional one. Further investigations are required.

Minimally invasive mini-hemilaminectomy-corpectomy in cadaveric dogs: evaluation of the accuracy and safety of a three-dimensionally printed patient-specific surgical guide.

BACKGROUND: As the frequency of spine surgery increases in the veterinary field, many studies have been conducted on minimally invasive spine surgery (MISS). Although many studies have been conducted on the thoracolumbar spine about MISS in animals, several problems and limitations have emerged regarding this method. Therefore, we developed a three-dimensional (3D) printed patient-specific surgical guide (3DPSSG) using 3D printing technology to overcome these problems. We aimed to evaluate the accuracy and safety of the 3DPSSG in minimally invasive mini-hemilaminectomy-corpectomy (MI-MHC). MI-MHC using 3DPSSG and an endoscopic system was performed at L1-L2 in 15 cadaveric dogs. The procedure of fixing the surgical guide to the vertebral body through screws and the surgical procedure using the guide were performed by two surgeons with different experiences. Postoperative computed tomography was used to measure planned and postoperative screw trajectories (angle, protruding from the far cortex) and to create 3D rendering images of vertebrae to evaluate the direction of bone window formation, corpectomy slot length, depth, and height ratio. RESULTS: The two groups which performed by two surgeons with different experiences did not differ in terms of screw angle deviation and length of the screw protruded from the far cortex. The corpectomy slot-length ratio was not different between the two groups; however, the slot-depth and height ratios were different. CONCLUSIONS: No differences were detected in screw trajectory and corpectomy slot-length ratio between the two groups. The 3DPSSG for MI-MHC is classified as accurate and safe; therefore, it can be an alternative to the conventional technique in dogs.

Three-Dimensional Planning and Patient-Specific Instrumentation for the Fixation of Distal Radius Fractures.

Background and Objectives: Three-dimensional planning and guided osteotomy utilizing patient-specific instrumentation (PSI) with the contralateral side used as a reference have been proven as effective in the treatment of malunions following complex fractures of the distal radius. However, this approach has not yet been described in relation to fracture reduction of the distal radius. The aim of this study was to assess the technical and logistical feasibility of computer-assisted surgery in a clinical setting using PSI for fracture reduction and fixation. Materials and Methods: Five patients with varied fracture patterns of the distal radius underwent operative treatment with using PSI. The first applied PSI guide allowed specific and accurate placement of Kirschner wires inside the multiple fragments, with subsequent concurrent reduction using a second guide. Results: Planning, printing of the guides, and operations were performed within 5.6 days on average (range of 1-10 days). All patients could be treated within a reasonable period of time, demonstrating good outcomes, and were able to return to work after a follow-up of three months. Mean wrist movements (°) were 58 (standard deviation (SD) 21) in flexion, 62 (SD 15) in extension, 73 (SD 4) in pronation and 74 (SD 10) in supination at a minimum follow-up of 6 months. Conclusions: Three-dimensional planned osteosynthesis using PSI for treatment of distal radius fractures is feasible and facilitates reduction of multiple fracture fragments. However, higher costs must be taken into consideration for this treatment.

Patient-specific Instrumentation Versus Standard Surgical Instruments in Primary Reverse Total Shoulder Arthroplasty: A Retrospective Comparative Clinical Study.

Aims: Patient-specific instrumentation (PSI) in primary shoulder arthroplasty has been studied; results supported the positive impact of the PSI on the glenoid positioning. Nevertheless, no clinical outcomes have been reported. We compare the clinical outcomes of primary reverse total shoulder arthroplasty using PSI versus the standard methods. Methods: Fifty-three patients with full records and a minimum of 24-months follow-up were reviewed, 35 patients received primary standard RSTA, and 18 patients received primary PSI RSTA. All patients were operated on in a single center. The median follow-up was 46 months (53 months in the standard group vs 39 months in the PSI group). Results: There was an overall significant post-operative improvement in the whole cohort (P< 0.05). The standard group had more deformed glenoids (B2, B3, C&D) and significantly low preoperative constant score and forward flexion (P=0.02 & 0.034). Compared to the PSI group (all were A1, A2, B1 &one type D), there were no statistically significant differences in any clinical outcome postoperatively. PSI neither prolonged the waiting time to surgery (P=0.693) nor the intraoperative time (P=0.962). Radiologically, PSI secured a higher percentage of optimum baseplate position and screw anchorage; however, no statistical correlation was found. Conclusion: In this series, both groups achieved comparable good outcomes. PSI did not achieve significantly better clinical outcomes than Standard after primary RSTA. Yet comparison has some limitations. PSI did not negatively impact the waiting time or the surgical time.

Computer guided calvarial bone grafting for reconstruction of orbital floor blow out fracture.

BACKGROUND: Calvarial grafts represents a superior option for orbital floor reconstruction, however the difficulty of intraoperative moulding and placement remains as a major limitation. We used patient specific guides and sterolithographic models to facilitate this procedure. METHODS: The study was conducted on 10 patients with orbital floor blow out fracture. A graft harvesting guide was virtually constructed based on the defect using mirroring of the normal side. The virtual guide and the defective orbital floor were then printed. The graft was harvested using the guide and adjusted to the defect using the model, finally seated in place. RESULTS: All patients showed no enophthalmos or diplopia. Orbital volume was comparable for both traumatised and normal orbits with no statistical significance difference (p value 0.28), and orbital volume ratio was 101.76 ± 4.7%. CONCLUSION: The use of graft harvesting guide and orbital floor models for intraoperative graft moulding showed promising results.

Effectiveness of a patient-specific guide for femoral stem implantation in primary total hip arthroplasty: a randomized control trial.

PURPOSE: The purpose of the present study was to evaluate the efficacy and feasibility of a novel CT-based patient-specific femoral alignment guide (PSG) as compared with conventional pre-operative planning during THA. METHODS: From March 2020 to September 2020, patients receiving unilateral primary THA were enrolled and randomly allocated to the conventional pre-operative planning group and the PSG group. Primary outcomes were radiographic measurements including lower limb length, femoral offset, femoral anteversion and stem varus/valgus angle, and post-operative perception of leg length discrepancy (LLD). Secondary outcomes were surgical time, intra-operative blood loss, total blood loss, visual analogue scale (VAS), and Harris Hip Score (HHS). The occurrence of post-operative complications was also recorded. RESULTS: Of the 104 patients screened, 80 cases were enrolled for analysis. The demographics of the two groups were similar. The PSG group illustrated significant improvements (p < 0.001) in lower limb length, femoral offset, femoral anteversion, and stem varus/valgus angle. Patients in the PSG group showed more favourable HHS (p < 0.001) at seven day, four week, andthree month (p = 0.003) follow-up. Perception of LLD was found significantly lower in the PSG group at three tmonth (p = 0.043), six month (p = 0.025), and 12-month (p = 0.048) follow-up. Utilization of the PSG had no significant increase in operative time, intra-operative blood loss, total blood loss, or VAS. No complication was noted in either group. CONCLUSION: Relative to conventional pre-operative planning, the application with the PSG could potentially provide a simple and reliable solution for improving femoral prosthesis orientation in THA with high accessibility and low healthcare costs. TRN: ChiCTR2000031043 Date of registration: 2020/3/21.

Complex joint-preserving bone tumor resection and reconstruction using computer navigation and 3D-printed patient-specific guides: A technical note of three cases.

In selected extremity bone sarcomas, joint-preserving surgery retains the natural joints and nearby ligaments with a better function than in traditional joint-sacrificing surgery. Geometric multiplanar osteotomies around bone sarcomas were reported with the advantage of preserving more host bone. However, the complex surgical planning translation to the operating room is challenging. Using both Computer Navigation and Patient-Specific Guide may combine each technique's key advantage in assisting complex bone tumor resections. Computer Navigation provides the visual image feedback of the pathological information and validates the correct placement of Patient-Specific Guide that enables accurate, guided bone resections. We first described the digital workflow and the use of both computer navigation and patient-specific guides (NAVIG) to assist the multiplanar osteotomies in three extremity bone sarcoma patients who underwent joint-preserving bone tumor resections and reconstruction with patient-specific implants. The NAVIG technique verified the correct placement of patient-specific guides that enabled precise osteotomies and well-fitted patient-specific implants. The mean maximum deviation errors of the nine achieved bone resections were 1.64 â€‹± â€‹0.35 â€‹mm (95% CI 1.29 to 1.99). The histological examination of the tumor specimens showed negative resection margin. At the mean follow-up of 55 months (40-67), no local recurrence was noted. There was no implant loosening that needed revision. The mean MSTS score was 29 (28-30) out of 30 with the mean knee flexion of 140° (130°-150°). The excellent surgical accuracy and limb function suggested that the NAVIG technique might replicate the surgical planning of complex bone sarcoma resections by combining the strength of both Computer Navigation and Patient-Specific Guide. The patient-specific approach may translate into clinical benefits. The translational potential of this article: The newly described technique enhances surgeons' capability in performing complex joint-preserving surgery in bone sarcoma that is difficult to be achieved by the traditional method. The high precision and accuracy may translate into superior clinical outcomes.

Simulated operation combined with patient-specific instrumentation technology is superior to conventional technology for supramalleolar osteotomy: a retrospective comparative study.

OBJECTIVE: Over the past seven years, our team has designed a simulated operation combined with patient-specific instrumentation (SO-PSI) assisted supramalleolar osteotomy (SMOT) method and applied it in the clinic. This study aimed to evaluate the differences between SO-PSI technology and conventional operation (CO) technology for SMOT in preoperative planning, intraoperative application, and postoperative curative effect. METHODS: We retrospectively analyzed SMOT data collected from our hospital between October 2014 and December 2018. Patients (n = 28) were enrolled and divided into CO (n = 17) and SO-PSI (n = 11) groups; mean follow-up time was 33.4 (range, 13 to 59) months. We statistically analyzed and compared perioperative data, accuracy of preoperative planning, intraoperative application, difference between pre- and post-operative radiologic ankle angles, changes in American Orthopaedic Foot & Ankle Society (AOFAS) score, visual analogue scale (VAS) score, range of ankle motion, and Takakura stage after surgery. RESULTS: All ankle alignments and positions were recovered for both groups. Compared with the CO group, the SO-PSI group had a shorter mean operating time and postoperative hospital stay, a decreased number of fluoroscopy examinations, lower albumin reduction, longer preoperative planning time and preoperative hospital stay, and increased hospitalization expenses. In the SO-PSI group, comparison of ankle angles at preoperative planning and postoperatively revealed good correlation, while this was not the case in the CO group. Mean tibial ankle center discrepancy for the SO-PSI group was 1.86 ± 1.06 mm. On follow-up, all radiologic parameters for the two groups improved significantly; however, the improvement of the tibial anterior surface angle and tibiotalar tilt angle for the SO-PSI group were more obvious than those for the CO group. AOFAS score, VAS score, ankle range of motion, and Takakura stage improved after surgery in both groups; however, the improvements in the SO-PSI group were greater than those in the CO group overall. CONCLUSIONS: SO-PSI technology can facilitate accurate and rapid preoperative planning for SMOT. In general, compared with conventional technology, SO-PSI has advantages for preoperative planning, intraoperative application, and postoperative curative effect.

Comparison of Clinical Outcomes After Transforaminal Interbody Fusion Using Cortical Bone Trajectory versus Percutaneous Pedicle Screw Fixation.

OBJECTIVE: The study aim was to compare clinical outcomes between patients undergoing transforaminal lumbar interbody fusion (TLIF) using percutaneous pedicle screw (PPS) and cortical bone trajectory (CBT) by a single surgeon. METHODS: This was a retrospective matched-cohort study of 77 patients (mean age, 71.7 years; 56% female) who underwent TLIF using CBT or PPS. Thirty-nine consecutive patients in the CBT group and 38 patients in the PPS group were matched for age, sex, and fused levels. All CBT screws were inserted by using a three-dimensional patient-specific guide (MySpine MC, Medacta). Perioperative outcomes of operative time, estimated blood loss, numeric rating scale scores, and serum concentration of creatine kinase were compared between the 2 groups. At 1 year postoperatively, clinical outcomes and radiographic outcomes, including cage subsidence, screw loosening, and fusion rates, were compared between the 2 groups. RESULTS: The numeric rating scale scores on postoperative days 3 and 7 and serum creatine kinase levels on postoperative days 1 and 3 were significantly lower in the CBT group than in the PPS group (all P < 0.005). There were no significant intergroup differences in operation time and estimated blood loss. At postoperative 1 year, there were no significant differences in cage subsidence, screw loosening, and fusion rates between the CBT group and PPS group. Clinical outcomes were equivalent between the 2 groups. CONCLUSIONS: The CBT technique using three-dimensional patient-specific guides resulted in lower perioperative pain and quicker recovery after surgery, which suggests that CBT is a less invasive procedure than PPS.

Intra-and interobserver reliability of determining the femoral footprint of the torn anterior cruciate ligament on MRI scans.

BACKGROUND: Re-injury rates following reconstruction of the anterior cruciate ligament (ACL) are significant; in more than 20% of patients a rupture of the graft occurs. One of the main reasons for graft failure is malposition of the femoral tunnel. The femoral origin of the torn ACL can be hard to visualize during arthroscopy, plus many individual variation in femoral origin anatomy exists, which may lead to this malpositioning. To develop a patient specific guide that may resolve this problem, a preoperative MRI is needed to identify the patient specific femoral origin of the ACL. The issue here is that there may be a difference in the reliability of identification of the femoral footprint of the ACL on MRI between different observers with different backgrounds and level of experience. The purpose of this study was to determine the intra- and interobserver reliability of identifying the femoral footprint of the torn ACL on MRI and to compare this between orthopedic surgeons, residents in orthopedic surgery and MSK radiologists. METHODS: MR images of the knee joint were collected retrospectively from 20 subjects with a confirmed rupture of the ACL. The 2D (coronal, sagittal, transversal) proton-density (PD) images were selected for the segmentation procedure to create 3D models of the femurs. The center of the femoral footprint of the ACL on 20 MRI scans, with visual feedback on 3D models (as reference) was determined twice by eight observers. The intra- and interobserver reliability of determining the center of the femoral footprint on MRI was evaluated. Intraclass correlation coefficients (ICCs) were calculated for the X, Y and Z coordinates separately and for a 3D coordinate. RESULTS: The mean 3D distance between the first and second assessment (intraobserver reliability) was 3.82 mm. The mean 3D distance between observers (interobserver reliability) was 8.67 mm. ICCs were excellent (> 0.95), except for those between the assessments of the two MSK radiologists of the Y and Z coordinates (0.890 and 0.800 respectively). Orthopedic surgeons outscored the residents and radiologists in terms of intra- and interobserver agreement. CONCLUSION: Excellent intraobserver reliability was demonstrated (< 4 mm). However the results of the interobserver reliability manifested remarkably less agreement between observers (> 8 mm). An orthopedic background seems to increase both intra- and interobserver reliability. Preoperative planning of the femoral tunnel position in ACL reconstruction remains a surgical decision. Experienced orthopedic surgeons should be consulted when planning for patient specific instrumentation in ACL reconstruction.

A modified rotating isosceles triangle osteotomy using a 3D-printed patient-specific guide for the treatment of cubitus varus in children: a case report and literature review.

After corrective osteotomy of cubitus varus, the lateral condylar prominence is a common problem, which is believed to be due to the unequal relative cuts of the lateral base wedge osteotomy. Therefore, several related solutions have been proposed, such as dome osteotomy and step-cut osteotomies, which solve the above problems to a certain extent. This study aimed to: (I) use a modified corpectomy to correct the deformity, and (II) present a new corpectomy method that uses a 3D-printed specific guide with an isosceles triangle osteotomy. A 12-year-old male presented with a -30-degree cubitus varus deformity 5 years after a supracondylar fracture of the right humerus. The degree of correction was determined from the varus angle and the normal carrying angle on the normal side. A rotating isosceles triangle osteotomy was determined by using Mimics software. The accuracy of the osteotomy angle was confirmed by postoperative radiography. The mean postoperative carrying angle was found to be preserved at the 10-month follow-up, with no complications. A rotating isosceles triangle osteotomy with a 3D-printed patient-specific guide may be providing a relative accurate result. However, in order to obtain more rigorous research conclusions, more cases should be added to examine this methodology for bone deformity surgery in the near future.

Computer-guided contouring of craniofacial fibrous dysplasia involving the zygoma using a patient-specific surgical depth guide.

The aim of this study was to introduce a new computer-guided technique for contouring and shaving of craniofacial fibrous dysplasia involving the zygoma. Computer-guided contouring was performed for five patients with unilateral craniofacial fibrous dysplasia involving the zygoma, using a patient-specific surgical depth guide. This patient-specific guide with depth holes was virtually designed for each patient based on mirroring of the unaffected side. The guide was printed using rapid prototyping. In the surgical theatre, the guide was seated in place and implant drills were inserted through the guide holes, creating depth holes according to the preoperative planning. Bone removal was then continued using surgical burs and/or bone chisels, connecting the guiding depth holes. Satisfaction with facial aesthetics was evaluated by the patients using a Likert scale, and by the surgeons using the Whitaker rating scale. All patients were satisfied with the postoperative facial aesthetics. Four patients were rated category I on the Whitaker rating scale, and one patient as category II. In conclusion, this patient-specific surgical depth guide appears to offer a solution for the unpredictability of conventional bone removal in unilateral craniofacial fibrous dysplasia, especially in three-dimensional multiplanar areas such as the zygoma. Further investigations are required.

3D printing and spine surgery.

Rapid prototyping (RP), also known as three-dimensional printing (3DP), allows the rapid conversion of anatomical images into physical components by the use of special printers. This novel technology has also become a promising innovation for spine surgery. As a result of the developments in 3DP technology, production speeds have increased, and costs have decreased. This technological development can be used extensively in different parts of spine surgery such as preoperative planning, surgical simulations, patient-clinician communication, education, intraoperative guidance, and even implantable devices. However, similar to other emerging technologies, the usage of RP in spine surgery has various drawbacks that are needed to be addressed through further studies.

Accuracy and safety of cortical bone trajectory screw placement by an inexperienced surgeon using 3D patient-specific guides for transforaminal lumbar interbody fusion.

Cortical bone trajectory (CBT) is an alternative method for pedicle screw insertion. However, identification of the optimal entry point and the direction of the CBT can be challenging for less-experienced surgeons. The purpose of this study was to evaluate the accuracy of the CBT screw placement by an inexperienced surgeon using a three-dimensional (3D) patient-specific guide for transforaminal lumbar interbody fusion (TLIF). Retrospective analysis of the data pertaining to 30 patients (128 screws) who underwent TLIF with CBT by an inexperienced surgeon using a 3D patient-specific guide (MySpine MC, Medacta) at a single center was performed. The accuracy of the CBT screw was graded into four groups (no perforation; Grade A, 0-2 mm; Grade B, 2-4 mm; and Grade C, > 4 mm). The accuracy of the CBT screw placement was 91% (116/128). Out of the 12 misplaced screws, Grade A was observed in 7 screws (5%), Grade B was observed in 3 screws (2%), and Grade C was observed in 2 screws (2%). There were no cases of medial pedicle wall perforation. The mean screw size was 5.95 ± 0.34 mm in diameter and 40.15 ± 2.83 mm in length. Note that, the accuracy of the CBT screws increased to 97% (83/86) over the first10 cases. Preoperative planning and 3D patient-specific guide enabled the use of longer and thicker screws and an optimal entry point. These results suggest the possibility of efficacy and safety in using 3D patient-specific guides for CBT screw placement by an inexperienced surgeon.

Three-dimensional-printed patient-specific Kirschner-wire guide for percutaneous fixation of undisplaced scaphoid fractures: a cadaveric study.

Undisplaced scaphoid waist fractures can be managed by percutaneous fixation. The purpose of this study is to compare percutaneous fixation using a three-dimensional (3-D)-printed guide with the conventional method in a cadaveric study. Twelve wrists were divided into two groups: standard fluroscopic technique group, and a patient-specific 3-D-printed guide group. In the patient-specific group, using high resolution CT scans, we manufactured a mould-guide including a wire guide sleeve aligned with the planned ideal path, and 3-D printed it. On postoperative CT scans we measured the angular deviation of the screw axis from the ideal axis, and compared the two groups. The angular deviation was significantly lower in the patient-specific guide group. We concluded that a 3-D-printed guide for scaphoid percutaneous fixation allows a more accurate placement of the screw than a fluoroscopy guide in our cadaveric model.

An Open-Label, Single-Arm Study of a Patient-Specific Femoral Guide for Total Hip Arthroplasty via the Anterolateral Supine Approach, Linked with Three-Dimensional Surgical Support Software: Study Protocol.

In total hip arthroplasty (THA), it is generally accepted that the bones of the acetabular cup and femur of hip joint must be accurately cut and components (artificial joint parts) be implanted in exact positions at exact angles to achieve improvement of daily living (ADL) and quality of life (QOL). However, with the conventional surgical method, it is difficult to grasp and measure the acetabular cup and femoral stem precisely during surgery, making some kind of reliable guide necessary. Although it was reported that an accurate angle was achieved in acetabular cup implantation by support instruments for surgical planning, an effective support instrument is now being developed for stem implantation on the out-of-reach femur side. This is the first clinical study to assess the efficacy and safety of anterolateral approach THA using an extracorporeal patient-specific femoral guide (PSG) for stem implantation with three-dimensional (3D) surgical support software in patients with hip joint disease.

Patient-specific Guides Using 3-dimensional Reconstruction Provide Accuracy and Reproducibility in Reverse Total Shoulder Arthroplasty.

BACKGROUND: We aimed to evaluate whether the use of our novel patient-specific guide (PSG) with 3-dimensional reconstruction in reverse total shoulder arthroplasty (RTSA) would allow accurate and reliable implantation of the glenoid and humeral components. METHODS: 20 fresh-frozen cadaveric shoulders were used. The PSG group (n=10) and conventional group (n=10) was evaluated the accuracy and reproducibility of implant positioning between before and after surgery on the computed tomography image. RESULTS: The superoinferior and anteroposterior offset in the glenoid component were 0.42 ± 0.07, 0.50 ± 0.08 in the conventional group and 0.45 ± 0.03, 0.46 ± 0.02 in the PSG group. The inclination and version angles were -1.93° ± 4.31°, 2.27° ± 5.91° and 0.46° ± 0.02°, 3.38° ± 2.79°. The standard deviation showed a smaller difference in the PSG group. The anteroposterior and lateromedial humeral canal center offset in the humeral component were 0.45 ± 0.12, 0.48 ± 0.15 in the conventional group and 0.46 ± 0.59 (p=0.794), 0.46 ± 0.06 (p=0.702) in the PSG group. The PSG showed significantly better humeral stem alignment. CONCLUSIONS: The use of PSGs with 3-dimensional reconstruction reduces variabilities in glenoid and humerus component positions and prevents extreme positioning errors in RTSA.

Patient-specific Guides Using 3-dimensional Reconstruction Provide Accuracy and Reproducibility in Reverse Total Shoulder Arthroplasty

BACKGROUND: We aimed to evaluate whether the use of our novel patient-specific guide (PSG) with 3-dimensional reconstruction in reverse total shoulder arthroplasty (RTSA) would allow accurate and reliable implantation of the glenoid and humeral components. METHODS: 20 fresh-frozen cadaveric shoulders were used. The PSG group (n=10) and conventional group (n=10) was evaluated the accuracy and reproducibility of implant positioning between before and after surgery on the computed tomography image. RESULTS: The superoinferior and anteroposterior offset in the glenoid component were 0.42 ± 0.07, 0.50 ± 0.08 in the conventional group and 0.45 ± 0.03, 0.46 ± 0.02 in the PSG group. The inclination and version angles were −1.93° ± 4.31°, 2.27° ± 5.91° and 0.46° ± 0.02°, 3.38° ± 2.79°. The standard deviation showed a smaller difference in the PSG group. The anteroposterior and lateromedial humeral canal center offset in the humeral component were 0.45 ± 0.12, 0.48 ± 0.15 in the conventional group and 0.46 ± 0.59 (p=0.794), 0.46 ± 0.06 (p=0.702) in the PSG group. The PSG showed significantly better humeral stem alignment. CONCLUSIONS: The use of PSGs with 3-dimensional reconstruction reduces variabilities in glenoid and humerus component positions and prevents extreme positioning errors in RTSA.

Instrumentation with 3D printed patient-specific guides versus conventional techniques in supramalleolar osteotomy for varus ankle osteoarthritis / 中华创伤骨科杂志

Objective To compare instrumentation with 3D-printed patient-specific guides versus conventional techniques in supramalleolar osteotomy for varus ankle osteoarthritis.Methods A retrospective analysis was done of the 21 patients with varus ankle osteoarthritis who had been treated at Department of Orthopaedics,Shanghai JiaoTong University Affiliated Sixth People's Hospital from January 2017 to December 2018.They were divided into 2 groups by their treatment methods.In the 9 patients treated by instrumentation with 3D-printed patient-specific guides,there were 6 males and 3 females with an age of 54.6 ±8.6 years,4 left and 5 right sides involved,and one case of Takakura stage 1,3 cases of Takakura stage 2 and 5 cases of Takakura stage 3a.In the 12 patients treated by conventional techniques,there were 7 males and 5 females with an age of 53.0 ± 6.5 years,7 left and 5 right sides involved,and one case of Takakura stage 1,5 cases of Takakura stage 2 and 6 cases of Takakura stage 3a.The 3D printed guide group and the conventional group were compared in terms of operation time,intraoperative blood loss and frequency of intraoperative fluoroscopy,tibial anterior surface angle (TAS),talar tilt angle (TT),and tibial lateral surface angle (TLS).The differences in TAS,TT and TLS between pre-and post-operation in the 3D printed guide group were also evaluated.Results There were no significant differences in the preoperative general data between the 2 groups (P ＞ 0.05),indicating they were comparable.All the patients were available for follow-up for an average of 7.8 months (from 3 to 15 months).The 3D printed guide group incurred significantly shorter operation time (106.2 ± 10.6 min),less intraoperative blood loss (207.2 ± 16.0 mL) and lower fluoroscopy frequency (2 ± 0) than the conventional osteotomy group (all P ＜ 0.01).The post-operative TAS (94.3° ± 3.2°) and TT (3.8° ± 0.8°) angles in the 3D guide group were significantly different from their preoperative values (84.6°±3.5° and 7.6°± 1.6°) (P ＜ 0.01).The 3D printed guide group was not significantly different from the conventional group in postoperative TAS (94.3°± 3.2° versus 92.4°±5.9°),TT (3.8° ± 0.8° versus 4.2° ± 1.1°) or TLS (83.7° ± 3.4° versus 84.2° ± 2.2°) angles (P ＞0.05).Conclusions Compared with conventional techniques,instrumentation with 3D-printed patient-specific guides can shorten operation time and reduce intraoperative blood loss and fluoroscopy frequency.The 3D printed patient-specific guides in osteotomy can facilitate accurate correction of varus deformity,leading to similar efficacy compared with conventional osteotomy.