Use Of Patient-specific Guides Research Articles

Use of patient-specific guides and 3D model in scapula osteotomy for symptomatic malunion

BackgroundScapular osteotomy for malunion can lead to resolution of pain and functional improvement in scapula fracture sequelae. Understanding three-dimensional bone morphology and analysing post-traumatic deformity is the main step of planning and the key to success of the procedure. 3D models and patient-specific guides are a growing technology to enhance accuracy of planning and to assist during surgery.Case presentationWe report the case of a 50 years old male, complaining of pain and limited function after a malunited scapular body fracture. Clinical assessment showed a severe impairment of shoulder function with active and passive forward flexion limited to 80°, absent external rotation, and internal rotation limited to the buttock. X-rays and CT scan showed an excessive lateral border offset of 53 mm and complete displacement of the glenoid segment anteriorly and medially to the scapular body, with impingement between the lateral most prominent scapular bone spur and humeral shaft. Glenopolar angle was 19°, scapular body angulation on the sagittal plane was 12°. Corrective osteotomy was planned on a virtual interactive rendering and on 3D printed models. Patient-specific guides were developed to perform a body-spine osteotomy with removal of a bone wedge, and a glenoid-spine osteotomy; a patient-specific wedge spacer was used to hold the reduction during plate fixation. Follow-up up to 12 months after surgery demonstrated improvement in scapula anatomy, shoulder girdle function, and patient-reported outcomes.ConclusionsFor the first time in scapula malunion surgery, patient-specific osteotomy guides were succesfully used during surgery to perform osteotomies and to assist in reduction maneuvers.

3D-printed, patient-specific cutting guides improve femoral and tibial cut alignment in canine total knee replacement.

The purpose of this cadaveric study was to determine whether patient-specific guides (PSGs) improve the accuracy of tibial and femoral cut alignment in canine total knee replacement (TKR), as compared with generic cutting guides. Original research. Sixteen pelvic limbs from skeletally mature medium- to large-breed canine cadavers. Specimens were randomly allocated to one of two groups (PSG or Generic; N = 8/group). In the Generic group, femoral and tibial ostectomies were made using the standard canine TKR femoral cutting blocks and tibial alignment guide. In the PSG group, the cuts were made using a series of custom 3D-printed cutting guides. "Planned" and "actual" tibial and femoral cut alignments were compared in the frontal and sagittal planes, and errors were calculated by subtracting actual from planned values. Use of 3D-printed PSGs improved tibial cut alignment in the frontal plane but not the sagittal plane. PSGs also improved the alignment of the cranial and distal femoral ostectomies but did not impact varus-valgus alignment. These findings support the use of PSGs for TKR in dogs. Clinical trials are now needed to determine whether the benefits of PSGs translate into measurable improvements in joint function and implant longevity. PSGs have the potential to improve femoral and tibial component alignment in canine TKR.

A comparison of patient-specific instrumentation to navigation for conducting humeral head osteotomies during shoulder arthroplasty.

BackgroundThe humeral head osteotomy during shoulder arthroplasty influences humeral component height, version and possibly neck-shaft angle. These parameters all potentially influence outcomes of anatomic and reverse shoulder replacement to a variable degree. Patient-specific guides and navigation have been studied and utilized clinically for glenoid component placement. Little, however, has been done to evaluate these techniques for humeral head osteotomies. The purpose of this study, therefore, was to evaluate the use of patient-specific guides and surgical navigation for executing a planned humeral head osteotomy.MethodsThe DICOM images of 10 shoulder computed tomography scans (5 normal and 5 osteoarthritic) were used to print 3D polylactic models of the humerus. Each model was duplicated, such that there were 2 identical groups of 10 models. After preoperative planning of a humeral head osteotomy, Group 1 underwent osteotomy via a patient-specific guide, while group 2 underwent a real time navigated osteotomy with an optically tracked sagittal saw. The cut height (millimeters), version (degrees) and neck-shaft angle (degrees) were recorded and statistically compared between groups.ResultsThere were no statistically significant differences between patient-specific guides and navigation for osteotomy cut height (P = .45) and humeral version (P = .059). Navigation, however, resulted in significantly less neck-shaft angle error than the patient specific guides (P = .023). Subgroup analysis of the osteoarthritic cases showed statistical significance for navigation resulting in less version error than the patient specific guides (P = .048).ConclusionNo significant differences were found between patient specific guides and navigation for recreation of the preoperatively planned humeral head cut height and version. Neck-shaft angle, however, had significantly less deviation from the preoperative plan when conducted with navigation.

Computer navigation leads to more accurate glenoid targeting during total shoulder arthroplasty compared with 3-dimensional preoperative planning alone

Commercially available preoperative planning software is now widely available for shoulder arthroplasty. However, without the use of patient-specific guides or intraoperative visual guidance, surgeons have little in vivo feedback to ensure proper execution of the preoperative plan. The purpose of this study was to assess surgeons' ability to implement a preoperative plan in vivo during shoulder arthroplasty. Fifty primary shoulder arthroplasties from a single institution were retrospectively reviewed. All surgical procedures were planned using a commercially available software package with both multiplanar 2-dimensional computed tomography and a 3-dimensional implant overlay. Following registration of intraoperative visual navigation trackers, the surgeons (1 attending and 1 fellow) were blinded to the computer navigation screen and attempted to implement the plan by simulating placement of a central-axis guide pin. Malposition was assessed (>4 mm of displacement or >10° error in version or inclination). Data were then blinded, measured, and evaluated. Mean displacement from the planned starting point was 3.2± 2.0 mm. The mean error in version was 6.4° ± 5.6°, and the mean error in inclination was 6.6° ± 4.9°. Malposition was observed in 48% of cases after preoperative planning. Malposition errors were more commonly made by fellow trainees vs. attending surgeons (58% vs. 38%, P = .047). Despite preoperative planning, surgeons of various training levels were unable to reproducibly replicate the planned component position consistently. Following completion of fellowship training, significantly less malposition resulted. Even in expert hands, the orientation of the glenoid component would have been malpositioned in 38% of cases. This study further supports the benefit of guided surgery for accurate placement of glenoid components, regardless of fellowship training.

Patient-Specific Guides/Instrumentation in Shoulder Arthroplasty.

Optimal outcomes following total shoulder arthroplasty TSA and reverse shoulder arthroplasty RSA are dependent on proper implant position. Multiple cadaver studies have demonstrated improved accuracy of implant positioning with use of patient-specific guides/instrumentation compared to traditional methods. At this time, there are 3 commercially available single use patient-specific instrumentation systems and 1 commercially available reusable patient-specific instrumentation system. Currently though, there are no studies comparing the clinical outcomes of patient-specific guides to those of traditional methods of glenoid placement, and limited research has been done comparing the accuracy of each system's 3-dimensional planning software. Future work is necessary to elucidate the ideal indications for the use of patient-specific guides and instrumentation, but it is likely, particularly in the setting of advanced glenoid deformity, that these systems will improve a surgeon's ability to put the implant in the best position possible.

3D PRINTING TECHNIQUE FOR PATIENT-SPECIFIC INSTRUMENTATION IN TOTAL KNEE ARTHROPLASTY

The aim of the study was to evaluate clinical and radiological outcomes of knee arthroplasty using patient specific guides produced using physical prototypes and 3D printing that are applied for positioning of resection blocks. Materials and methods. The authors analyzed the treatment outcomes of 4 patients during the period from 2015 to 2016 who underwent total knee arthroplasty for posttraumatic gonarthrosis of III-IV stage with the use of patient specific guides for resection blocks positioning. The mean age of patients was 59±12 years. Initially, all patients reported marked limitation of movement in the knee joint. The average flexion prior to surgery was 53.3±35.1°. According to FLFS roentgenography all patients had a varus deformity of the lower limb with an average value of 15.0±12.3°.Results. In all cases the axis of the lower limb was normalized postoperatively. The average KOOS score for “pain” was 85.2±14.0, for “daily physical activity” — 74.5±14.8, for “symptoms and stiffness” — 69.0±11.0, for “quality of life” — 62.5±12.5 points. Average knee ROM after arthroplasty: flexion 113.3±5.787° and full extension. Such outcomes can be considered as excellent considering preoperative marked knee movement limitations in all patients.Conclusion. Preoperative planning using the technology of producing patient specific guides and prototyping on physical tibia and femur models allowed to restore normal axis of the lower limb. The authors observed a significant improvement in joint function and a pain syndrome reduction in all patients. In authors’ opinion patient specific precision guides can be used in the following cases: inflammatory process or deformation of the femur in patient’s history; when the use of intramedullary guides is difficult and does not allow positioning of the prosthesis components with sufficient accuracy or is associated with an increased risk of a purulent-inflammatory process; ipsilateral hip joint prosthesis when it is desirable to avoid opening the medullary canal; substantial bone defects or massive osteophytes of the posterior portion of femoral condyles that impede correct rotation of the femoral component; severe movement limitations in the knee joint, when it is technically impossible to perform TKA using computer navigation and the use of a standard set of instruments poses significant technical difficulties.

Resection accuracy of patient-specific cutting guides in total knee replacement.

Patient-specific guides (PSGs) have been thoroughly investigated with regards to reconstitution of mechanical alignment in total knee arthroplasty (TKA). The ability to replicate the preoperative surgical plan is essential for optimal outcomes but intraoperative measurements to confirm accurate progression through the operation are limited. This leads to our clinical question: can PSGs replicate the planned bone resection depth during TKA? This is a prospective case series of 118 patients who underwent TKA using magnetic resonance imaging-based patient-specific cutting guides. Intraoperative bone resection thickness was measured and compared with the preoperative planned bone resections as a primary outcome. Secondary outcomes included the need for additional bone resections, the number of cases for which the PSG technique was abandoned, final component sizes and mechanical alignment. PSGs could not accurately recreate preoperative plan. PSGs resulted in over-resection in all bone cuts compared with the preoperative surgical resection plan. Secondary osteotomies were required in 37% of patients. PSGs had to be abandoned in 10.5% of cases, mostly due to suboptimal fit of the femoral block. The tibial component size was altered more frequently than the femoral. Intraoperatively, PSGs could not accurately recreate the preoperative plan. PSGs are marketed as user-friendly tools to simplify TKA but our research demonstrates the need for surgeons to monitor surgical progression and compensate for errors occurring during the use of PSGs.

Three-dimensional corrective osteotomies of complex malunited humeral fractures using patient-specific guides

Corrective osteotomies of malunited fractures of the proximal and distal humerus are among the most demanding orthopedic procedures. Whereas the restoration of the normal humeral anatomy is the ultimate goal, the quantification of the deformity as well as the transfer of the preoperative plan is challenging. The purpose of this study was to provide a guideline for 3-dimensional (3D) corrective osteotomies of malunited intra-articular fractures of the humerus and a detailed overview of existing and novel instruments to enlarge the toolkit for 3D preoperative planning and intraoperative realization using patient-specific guides. We describe the preoperative 3D deformity analysis, relevant considerations for the preoperative plan, design of the patient-specific guides, and surgical technique of corrective osteotomies of the humerus. The presented technique demonstrates the benefit of computer-assisted surgery for complex osteotomies of the humerus from a preoperative deformity analysis to the creation of feasible surgical procedures and the generation of patient-specific guides. A 3D analysis of a post-traumatic deformity of the humerus, 3D preoperative planning, and use of patient-specific guides facilitate corrective osteotomies of complex malunited humeral fractures.

Computer-Assisted 3-Dimensional Reconstructions of Scaphoid Fractures and Nonunions With and Without the Use of Patient-Specific Guides: Early Clinical Outcomes and Postoperative Assessments of Reconstruction Accuracy

To present results regarding the accuracy of the reduction of surgically reconstructed scaphoid nonunions or fractures using 3-dimensional computer-based planning with and without patient-specific guides. Computer-based surgical planning was performed with computed tomography (CT) data on 22 patients comparing models of the pathological and the opposite uninjured scaphoid in 3 dimensions. For group 1 (9 patients), patient-specific guides were designed and manufactured using additive manufacturing technology. During surgery, the guides were used to define the orientation of the reduced fragments. The scaphoids in group 2 (13 patients) were reduced with the conventional freehand technique. All scaphoids in both groups were fixed with a headless compression screw or K-wires, and all bone defects (except one) were filled with autologous bone grafts or vascularized grafts. Postoperative CT scans were acquired 2 or more months after the operations to monitor consolidation and compare the final result with the preoperative plan. The clinical results and accuracy of the reconstructions were compared. In group 1, 8 of 9 scaphoids healed after 2 to 6 months, and partial nonunion after 9 months was observed in one patient. In group 2, 11 of 13 scaphoids healed between 2 and 34 months whereas 2 scaphoids did not consolidate. Comparison of the preoperative and postoperative 3-dimensional data revealed an average residual displacement of 7° (4° in flexion-extension, 4° in ulnar-radial deviation, and 3° in pronation-supination) in group 1. In group 2, residual displacement after surgery was 26° (22° in flexion-extension, 12° in ulnar-radial deviation, and 7° in pronation-supination). The difference in the accuracy of reconstruction was significant. Although the scaphoid is small, patient-specific guides can be used to perform scaphoid reconstructions. When the guides were used, the reconstructions were significantly more anatomic compared with those resulting from the freehand technique. Therapeutic III.

Analyse fonctionnelle après implantation d’une prothèse d’épaule inversée – comparaison d’une méthode traditionnelle et d’une méthode avec guides personnalisés

Recent studies reported the use of patient-specific guides in aim to improve accuracy in glenoid component positioning for RSA. Most of the guides assessed in the literature have shown promising results on following preoperative plans. However, there are no direct comparisons for glenoid placement and functional outcomes of a standard RSA surgery to a guided RSA surgery. This study was designed to perform RSA surgery from a single surgeon in 20 cadaveric specimens with two methodologies for glenoid baseplate placement: – traditional procedure in using a standard surgical instrumentation; – assisted procedure with a specific-guide according to a preoperative plan. The Biomet Comprehensive RSA was used. In both methods, the surgeon aimed to achieve glenoid baseplate version and tilt placement to anatomical values (0 to 5°). For the guided surgeries, a preoperative plan was performed using an interactive shoulder model (Newcastle Shoulder Model). The plan aimed to maximize impingement free range of motion (abduction, internal and external rotation). Specific guides were manufactured based on these plans by a 3D printer. Pre- and postoperative CTs were used to assess the glenoid orientation as well as the position of the baseplate. The impingement free range of motion was evaluated with a motion analysis system postoperatively. In average both standard and guided RSA surgeries changed the postoperative glenoid version and tilt, but none of the changes were statistically significant (P > 0.05). The guided surgery had a significant impact on the placement of the glenoid baseplate, which was in average 4.2 mm (SD 4.0) more inferiorly compared to the standard procedure (P < 0.05). This difference in baseplate placement had also an effect on the impingement results. The average inferior impingement was recorded at 10.4° (SD 4.3) and superior impingement averaged at 67.9° (SD 4.3) for the guide surgery specimens. It was better than the cadavers that received traditional procedure (average inferior and superior impingement - 29.6° (SD 13.7), 59.3° (SD 1.54), respectively, P < 0.05). Rotation range of motion was 113° (SD 15.0) for the specific guide group and 63.3° (SD 27.4) for the standard guide group (P < 0.05). The specific guides allowed to achieve a more inferior glenoid placement compared to the standard instrumentation. The latter translated in a better functional outcome with a larger free impingement range of motion. The guided surgeries had no effect on the postoperative glenoid alignment but this was expected since the cadaveric specimens had no arthritis or abnormal glenoid deformities.

Three-dimensional planning and use of patient-specific guides improve glenoid component position: an in vitro study

Glenoid component positioning is a key factor for success in total shoulder arthroplasty. Three-dimensional (3D) measurements of glenoid retroversion, inclination, and humeral head subluxation are helpful tools for preoperative planning. The purpose of this study was to assess the reliability and precision of a novel surgical method for placing the glenoid component with use of patient-specific templates created by preoperative surgical planning and 3D modeling. A preoperative computed tomography examination of cadaveric scapulae (N = 18) was performed. The glenoid implants were virtually placed, and patient-specific guides were created to direct the guide pin into the desired orientation and position in the glenoid. The 3D orientation and position of the guide pin were evaluated by performing a postoperative computed tomography scan for each scapula. The differences between the preoperative planning and the achieved result were analyzed. The mean error in 3D orientation of the guide pin was 2.39°, the mean entry point position error was 1.05 mm, and the mean inclination angle error was 1.42°. The average error in the version angle was 1.64°. There were no technical difficulties or complications related to use of patient-specific guides for guide pin placement. Quantitative analysis of guide pin positioning demonstrated a good correlation between preoperative planning and the achieved position of the guide pin. This study demonstrates the reliability and precision of preoperative planning software and patient-specific guides for glenoid component placement in total shoulder arthroplasty.

Patient-specific Guides Do Not Improve Accuracy in Total Knee Arthroplasty: A Prospective Randomized Controlled Trial

Recently, patient-specific guides (PSGs) have been introduced, claiming a significant improvement in accuracy and reproducibility of component positioning in TKA. Despite intensive marketing by the manufacturers, this claim has not yet been confirmed in a controlled prospective trial. We (1) compared three-planar component alignment and overall coronal mechanical alignment between PSG and conventional instrumentation and (2) logged the need for applying changes in the suggested position of the PSG. In this randomized controlled trial, we enrolled 128 patients. In the PSG cohort, surgical navigation was used as an intraoperative control. When the suggested cut deviated more than 3° from target, the use of PSG was abandoned and marked as an outlier. When cranial-caudal position or size was adapted, the PSG was marked as modified. All patients underwent long-leg standing radiography and CT scan. Deviation of more than 3° from the target in any plane was defined as an outlier. The PSG and conventional cohorts showed similar numbers of outliers in overall coronal alignment (25% versus 28%; p = 0.69), femoral coronal alignment (7% versus 14%) (p = 0.24), and femoral axial alignment (23% versus 17%; p = 0.50). There were more outliers in tibial coronal (15% versus 3%; p = 0.03) and sagittal 21% versus 3%; p = 0.002) alignment in the PSG group than in the conventional group. PSGs were abandoned in 14 patients (22%) and modified in 18 (28%). PSGs do not improve accuracy in TKA and, in our experience, were somewhat impractical in that the procedure needed to be either modified or abandoned with some frequency.

Kinematically Versus Mechanically Aligned Total Knee Arthroplasty

The purpose of this study was to compare 2 alignment methods for total knee arthroplasty (TKA): kinematic alignment with the use of patient-specific guides and mechanical alignment with conventional instruments. A randomized, controlled trial of 41 kinematically aligned and 41 mechanically aligned patients was conducted with the patient, radiographic evaluator, and clinical evaluator blinded to the alignment technique. Radiographic measurements were made from long-leg computer tomography scanograms. Clinical outcome scores and motion were measured preoperatively and 6 months postoperatively. The hip-knee-ankle angle (0.3° difference; P=.693) and anatomic angle of the knee (0.8° difference; P=.131) were similar for both groups. In the kinematically aligned group, the angle of the femoral component was 2.4° more valgus (P<.000) and the angle of the tibial component was 2.3° more varus (P<.000) than the mechanically aligned group. At 6 months postoperatively, the Western Ontario and McMaster Universities Osteoarthritis Index score was 16 points better (P<.000), Oxford Score was 7 points better (P=.001), combined Knee Society Score was 25 points better (P=.001), and flexion was 5.0° greater (P=.043) in the kinematically aligned group than in the mechanically aligned group.Our findings suggest that the risk of early failure related to limb or knee alignment should be similar in kinematic and mechanically aligned TKA. More anatomic alignment of the implant was associated with better flexion and better clinical outcome scores in the kinematically aligned group.