Patient-specific Instrumentation Research Articles

“In-house” Design and Use of 3-dimensional Printed Patient-specific Bone Tumor Resection Guides for Geometric Osteotomies in Sarcoma Surgery

Three-dimensional printing technology has rapidly advanced as a promising technology for preoperative planning, education, and surgical execution in orthopedic surgery. Use of patient-specific instrumentation in orthopedic oncology sarcoma cases can streamline complex osteotomies while providing safe margins based on predetermined osteotomy levels. We describe use of an “in-house” protocol to create patient-specific bone tumor resection guides for use in orthopedic oncology cases. The described protocol bypasses expensive outsourcing options and facilitates use of preoperative surgical simulation and intimate involvement of the surgical team in the guide design. We report on the successful design and use of three-dimensional printed patient-specific bone tissue resection guides in a case of proximal tibial parosteal osteosarcoma resection and reconstruction with a size-matched allograft, and in a case of a secondary pelvic chondrosarcoma resection.

Comparative Cost Analysis of Four Different Computer-Assisted Technologies to Implant a Total Knee Arthroplasty over Conventional Instrumentation.

Several computer-assisted technologies, such as navigation and robotics, have been introduced to Total Knee Arthroplasty (TKA) in order to increase surgical precision and reduce complications. However, these technologies are often criticized due to the increased costs and effort associated with them; however, comparative data are missing. The aim of the present study was to evaluate differences in intraoperative workflows and the related perioperative cost-profiles of four current computer-assisted technologies, used to implant a TKA, in order to gain a comparison to conventional instrumentation. For the cost analysis, additional preoperative imaging and instruments, increased operating room (OR) and planning-time, and expenditures for technical support of the equipment and disposals were calculated, in comparison to conventional TKA, for (1) standard computer-navigation, (2) patient specific instruments (PSI), (3) image-based robotic assistance, and (4) imageless robotic assistance. Workflows at four expert centers which use these technologies were reviewed by an independent observer. The total cost calculation was based on a 125 TKA per year unit in Switzerland. Computer-navigation resulted in 14 min (+23%) increased surgery time and, overall, USD 650 in additional costs. PSI technology saved 5 min (8%) OR time but it created USD 1520 in expenditures for imaging and disposals. The image-based robotic system was the most expensive technology; it created overall additional costs of USD 2600, which predominately resulted from technical support, disposals, the CT-Scan, and 14 min of increased OR time. The imageless robotic assistance resulted in the largest increase in OR-time, as it resulted in an additional 25 min (+42%) on average. Overall, additional costs of USD 1530 were calculated. Every one of the assistive technologies in this study increased the total cost of TKA when compared to a conventional technique, and the most important variables, related to cost, were technical support and additional disposables. The longer surgical times and additional surgical trays required for the techniques had a marginal effect on overall costs. This comparative cost analysis gives valuable information for future efforts to calculate the real costs of these technologies and the subsequent return on investment of each technique.

The validity and accuracy of 3D-printed patient-specific instruments for high tibial osteotomy: a cadaveric study

ObjectiveHigh tibial osteotomy (HTO) has been used for the treatment of patients with knee osteoarthritis. However, the successful implementation of HTO requires precise intraoperative positioning, which places greater requirements on the surgeon. In this study, we aimed to design a new kind of 3D-printed patient-specific instrument (PSI) for HTO, including a positioning device and an angle bracing spacer, and verify its effectiveness using cadaveric specimens.MethodsThis study included ten fresh human lower-limb cadaveric specimens. Computed tomography (CT) and X-ray examinations were performed to make preoperative plans. PSI was designed and 3D-printed according to the preoperative plan. Then, the PSI was used to guide HTO. Finally, we performed X-ray and CT after the operation to verify its validity and accuracy.ResultsThe PSI using process was adjusted according to the pre-experimental procedure in 1 case. Hinge fracture occurred in 1 case. According to X-rays of the remaining eight cadaveric specimens, no statistically significant difference was noted between the preoperative planning medial proximal tibial angle (MPTA) and postoperative MPTA (P > 0.05) or the preoperative and postoperative posterior slope angle (PSA) (P > 0.05). According to the CT of 10 cadaveric specimens, no statistically significant difference was noted between the design angle and actual angle, which was measured according to the angle between the osteotomized line and the cross section (P > 0.05). The gap between the designed osteotomy line and the actual osteotomy line was 2.09 (0.8 ~ 3.44) mm in the coronal plane and 1.58 (0.7 ~ 2.85) mm in the sagittal plane.ConclusionThis 3D-printed PSI of HTO accurately achieves the angle and position of the preoperative plan without increasing the stripping area. However, its use still requires a certain degree of proficiency to avoid complications, such as hinge fracture.

Minimum 5-Year Outcomes of a Multicenter, Prospective, Randomized Control Trial Assessing Clinical and Radiological Outcomes of Patient-Specific Instrumentation in Total Knee Arthroplasty

BackgroundPatient-specific instrumentation (PSI) was developed to produce more accurate alignment of components and consequently improve clinical outcomes when used in total knee arthroplasty. We compare radiological accuracy and clinical outcomes at a minimum of 5-year follow-up between patients randomized to undergo total knee arthroplasty performed using PSI or traditional cutting block techniques. MethodsThis multicenter, randomized control trial included patients blinded to the technique 1used. Outcome measures were coronal alignment measured radiologically, Euroqol-5D, Oxford knee score, and International Knee Society Score measured at 1- and 5-year follow-up. ResultsAt a minimum 5-year follow-up, there were 38 knees in the PSI group and 39 in the conventional instrumentation group for analysis. Baseline demographics and clinical outcome scores were matched between groups. Overall, there was no significant difference in the coronal femoral angle (P = .59), coronal tibial angle (P = .37), tibiofemoral angle (P = .99), sagittal femoral angle (P = .34), or the posterior tibia slope (P = .12) between knees implanted using PSI and those implanted with traditional cutting blocks. On the measurement of coronal alignment, intraobserver reliability tests demonstrated substantial agreement (k = 0.64). Clinical outcomes at both 1-year and 5-year follow-up demonstrated statistically significant and clinically relevant improvement in scores from baseline in both groups, but no difference could be detected between the Euroqol-5D (P = .78), Oxford knee score (P = .24), or International Knee Society Score (P = .86) between the 2 groups. ConclusionThis study has shown no additional benefit to PSI in terms of improved alignment or functional outcomes at minimum 5-year follow-up over traditional techniques.

Accuracy of CT-Derived Patient-Specific Instrumentation for Total Ankle Arthroplasty: The Impact of the Severity of Preoperative Varus Ankle Deformity.

Significant preoperative varus tibiotalar deformity was once believed to be a contraindication for total ankle arthroplasty (TAA). Our primary goal was to evaluate the influence of increasing preoperative varus tibiotalar deformity on the accuracy of final implant positioning using computed tomography (CT)-derived patient-specific guides for TAA. Thirty-two patients with varus ankle arthritis underwent TAA using CT-derived patient-specific guides. Patients were subcategorized into varying degrees of deformity based on preoperative tibiotalar angles (0°-5° neutral, 6°-10° mild, 11°-15° moderate, and >15° severe). Postoperative weightbearing radiographs were used to measure coronal plane alignment of the tibial implant relative to the target axis determined by the preoperative CT template. Average follow-up at the time of data collection was 36.8 months. Average preoperative varus deformity was 6.06° (range: 0.66°-16.3°). Postoperatively, 96.9% (30/31) of patients demonstrated neutral implant alignment. Average postoperative tibial implant deviation was 1.54° (range: 0.17°-5.7°). Average coronal deviation relative to the target axis was 1.61° for the neutral group, 1.78° for the mild group, 0.94° for the moderate group, and 1.41° for the severe group (P = .256). Preoperative plans predicted 100% of tibial and talar implant sizes correctly within 1 size of actual implant size. Conclusion. Our study supports the claim that neutral postoperative TAA alignment can be obtained using CT-derived patient-specific instrumentation (PSI). Furthermore, final implant alignment accuracy with PSI does not appear to be impacted by worsening preoperative varus deformity. All but one patient (96.9%) achieved neutral postoperative alignment relative to the predicted target axis. Level IV, Clinical Case Series.

Digital orthopedics technology leads the new development direction of arthroplasty

Digital orthopedics technology is a new interdisciplinary subject, known as the third technological wave in the field of orthopedics. The development direction of arthroplasty is focused on hoping to improve the long-term prognosis of patients by imitating more natural kinematics and optimizing implant positioning strategies. At present, various digital orthopedic technologies such as virtual reality technology, navigation assistance systems, and patient-specific instrumentation (PSI) and robot-assisted surgery in joint surgery are in full swing. In this article, relevant domestic and foreign literature were extensively reviewed and the author's own experiences were summarize, and the advantages, disadvantages, clinical efficacy and future prospects of the above-mentioned various technologies were evaluated too.

Custom-made 3D-Printed Prosthesis in Periacetabular Resections Through a Novel Ileo-adductor Approach.

Resection of sarcomas around the acetabulum presents major challenges. The resulting bone effect can be reconstructed with personalized custom-made prostheses. Patient-specific instruments (PSIs) have been demonstrated to be of added value for bone-cutting accuracy, and they may improve pelvic surgery. The authors describe a novel ileo-adductor approach for pelvic tumor surgery and report the preliminary results of 5 reconstructions using custom 3D-printed prostheses associated with PSI surgical guides. This combined technique allows an optimal restoration of the anatomy with reduced surgical time and reduced postoperative complications such as infections and wound healing problems. [Orthopedics. 2022;45(2):e110-e114.].

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

AimsPatient-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.MethodsFifty-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).ResultsThere 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.ConclusionIn 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.

Accuracy of CT Derived Patient Specific Instrumentation for Total Ankle Arthroplasty: The Impact of the Severity of Preoperative Varus Ankle Deformity

Category:Ankle; Ankle ArthritisIntroduction/Purpose:Significant preoperative varus tibiotalar deformity was once believed to be a contraindication to performing total ankle arthroplasty (TAA). While correction of ankle deformity has been shown to be possible, the ability to restore neutral alignment in more severe ankle arthritis is still a concern. Preoperative CT derived navigation is gaining popularity for its ability to accurately restore neutral alignment in TAA, in addition to decreasing operative and fluoroscopic times. The primary goal of this study was to evaluate whether accuracy and reproducibility of final implant positioning using patient specific guides were influenced as varus deformity became more severe in patients undergoing TAA.Methods:A retrospective review of 32 patients with varus end-stage ankle arthritis who underwent TAA utilizing total ankle implants with CT derived patient-specific guides was conducted. Preoperative computed tomography (CT) scans were obtained to assess coronal plane deformity, mechanical and anatomic alignment, and build patient-specific guides that referenced bony anatomy. Preoperative weightbearing radiographs were used to measure the tibiotalar and talar tilt angles to assess coronal plane deformity severity and congruency, respectively. Patients were subcategorized into varying degrees of deformity based on their tibiotalar angles (<0-5° neutral, 6-10° mild, 11-15° moderate, and >15° severe). The first postoperative weightbearing radiograph following surgery was used to measure coronal plane alignment of the tibial implant relative to the target axis determined by the preoperative CT template.Results:The average preoperative varus deformity, as determined by the tibiotalar angle, was 6.06° (range: 0.66- 16.3°) for the entire cohort. Average preoperative varus deformity was 2.63° for the 'neutral' group, 7.64° for the mild group, 11.5° for the moderate group and 16.3° for the severe group. Postoperative weightbearing alignments for 96.9% (30/31) of patients demonstrated neutral implant alignment (< 5°). Relative to the CT derived target axis, the average tibial implant coronal deviation for all patients was 1.54° (range: 0.17-5.7°). The average postoperative coronal alignment relative to the target axis was 1.61° for the neutral group, 1.78° for the mild group, 0.94° for the moderate group, and 1.41° for the severe group. There was no statistically significant difference in final implant alignment relative to the target axis between deformity subgroups (p= 0.256).Conclusion:The results of our study further support that neutral postoperative TAA alignment can repeatably be obtained using preoperative CT derived patient specific instrumentation (PSI). Furthermore, the accuracy and reproducibility of achieving neutral postoperative radiographic alignment with PSI does not appear to be impacted by worsening varus ankle deformity. All but one patient (96.9%) achieved neutral postoperative alignment relative to the predicted target axis, with the only outlier being from the mild deformity subgroup. Future studies are warranted assessing the effect that even greater coronal plane deformity (>20 °) has on the accuracy of TAA implantation using PSI.

Accuracy of Patient-Specific Instrument for Cylindrical Axis Implementation in Kinematically Aligned Total Knee Arthroplasty.

In kinematically aligned total knee arthroplasty (KA-TKA), the cylindrical axis (CA) is very important in restoring the native joint line and kinematics of the pre-arthritic knee. This study aimed to determine the accuracy of patient-specific instrument (PSI) for restoring the CA for femoral bone resection in KA-TKA. Thirty KA-TKAs were performed using a computed tomography (CT)-based PSI system. Data from preoperative CT were reconstructed into three-dimensional (3D) models using 3D-planning software. The CA was created by connecting the centers of each virtual sphere to the medial and lateral femoral condyles using computer software. Femoral bone resection of the distal and posterior condyles was performed parallel to the sagittal planes of the CA. The thickness of the CA-referenced bone resection was determined based on the thickness necessary for the respective regions of the femoral component. The PSI was manufactured to locate the guide pin for a conventional cutting block. The accuracy of PSI for KA-TKA was evaluated as the absolute error between the preoperatively predicted thickness and the intraoperative measurements in each of the four regions, as well as the difference in error between distal-medial (DM) and posterior-medial (PM) and between distal-lateral (DL) and posterior-lateral (PL). The differences in thickness of bone cut in the DM, DL, PM, and PL were 0.79 ± 0.39 mm (range, -1.20 to 1.50), 0.70 ± 0.42 mm (range, -1.50 to 1.50), 0.80 ± 0.46 mm (range, -0.80 to 1.50), and 0.75 ± 0.47 mm (range, -2.10 to 1.40), respectively. There was no significant difference in the thickness error between DM and PM (p = 0.959) and between DL and PL (p = 0.812). In KA-TKA, PSI was effective for accurate femoral bone resection based on virtually planned thickness.

Three dimensional patient-specific guides for guide pin positioning in reverse shoulder arthroplasty: An experimental study on different glenoid types.

Incorrect positioning is one of the main factors for glenoid component loosening in reverse shoulder arthroplasty and component placement can be challenging. This study aimed to assess whether Patient-Specific Instrumentation (PSI) provides better guide pin positioning accuracy and is superior to standard guided and freehand instrumentation methods in cases of glenoid bone deformity. Based on the Walch classification, five different scapula types were acquired by computed tomography (CT). For each type, two different surgeons placed a guide pin into the scapula using three different methods: freehand method, conventional non-patient-specific guide, and PSI guide. Each method was repeated five times by both surgeons. In these experiments, a total of 150 samples of scapula models were used (5 × 2 × 3 × 5 = 150). Post-operative CT scans of the samples with the guide pin were digitally assessed and the accuracy of the pin placement was determined by comparison to the preoperative planning on a three-dimensional (3D) model. The PSI method showed accuracies to the preoperative plan of 2.68 (SD 2.10) degrees for version angle (p < .05), 2.59 (SD 2.68) degrees for inclination angle (p < .05), and 1.55 (SD 1.26) mm for entry point offset (p < .05). The mean and standard deviation errors compared to planned values of version angle, inclination angle, and entry point offset were statistically significant for the PSI method for the type C defected glenoid and non-arthritic glenoid. Using the PSI guide created by an image processing software tool for guide pin positioning showed advantages in glenoid component positioning over other methods, for defected and intact glenoid types, but correlation with clinical outcomes should be examined.

Patient-Specific Instrumentation Improves Rotational Alignment of the Tibial Component in Total Knee Arthroplasty

Patient-Specific Instrumentation Improves Rotational Alignment of the Tibial Component in Total Knee Arthroplasty

Accuracy of Weightbearing CT vs Non-Weightbearing CT Scans for Patient-Specific Instrumentation in Total Ankle Arthroplasty

Category:AnkleIntroduction/Purpose:Total ankle arthroplasty (TAA) is a popular and viable option for end stage ankle arthritis. Accuracy and reproducibility in placing the implant on the mechanical axis has been shown to be paramount in total ankle replacement. Patient specific pre-operative navigation up until this past year has been based off of non-weightbearing computerized tomography (CT). Our institution has created a protocol to use weightbearing CT in the pre-operative patient specific navigation for TAA using the ProphecyTM system. The purpose of our study was to compare the accuracy and reproducibility of implant alignment and size using WBCT versus prior studies using NWBCT for the Prophecy reports.Methods:Patients who underwent TAA using our WBCT protocol for their Prophecy scans had their charts reviewed to see if they met the proper inclusion criteria. Inclusion criteria was a primary TAA with proper follow-up to have first post-operative weightbearing radiographs. The first post-operative weightbearing radiographs were used to measure alignment of the axis of the implant in frontal and sagittal planes comparative to the tibial axis. These results were then compared to the pre-operative prophecy scans to determine reproducibility. The size of the implants components were also recorded for each patient and compared to the pre-operative predicted implant sizes from the patient specific reports. Our results were also compared to previous studies on reproducibility of patient specific navigation when using non-weightbearing CT.Results:Ten patients met our inclusion criteria of WBCT ProphecyTM preoperative planning. 100% of the TAA were within the intended target of less than 50 varus or valgus. The average post-operative coronal alignment was an average of 0.844 degrees. Average sagittal plane deformity was 1.88 degrees post-operative. Tibial component size was properly predicted 100% of the time and talar component in all but one patient.Conclusion:This data supports superior accuracy and reproducibility in pre-operative patient specific navigation when utilizing WBCT for TAA vs published controls with non-weightbearing CT.

Three-Dimensional Patient Specific Instrumentation and Cutting Guide for Medial Closing Wedge High Tibial Osteotomy to Correct Valgus Malalignment

Achievement of appropriate mechanical knee alignment is crucial to ensure optimal clinical outcomes following osteotomy procedures about the knee. The use of patient-specific instrumentation (PSI) to assist in preoperative planning and intraoperative realignment has gained increasing popularity. The purpose of this article is to describe a surgical technique involving a medial closing wedge high tibial osteotomy performed using three-dimensional (3D) PSI and cutting guide to revise residual valgus deformity following failed distal femoral osteotomy. The correction angle, 3D position of the hinge and wedge, as well as final plate and screw position are planned preoperatively using virtual software and computed tomography imaging to allow precise surgical execution.

The Novel Application of Three-Dimensional Printing Assisted Patient-Specific Instrument Osteotomy Guide in the Precise Osteotomy of Adult Talipes Equinovarus.

Objective This current research is aimed at assessing clinical efficacy and prognosis of three-dimensional (3D) printing assisted patient-specific instrument (PSI) osteotomy guide in precise osteotomy of adult talipes equinovarus (ATE). Methods We included a total of 27 patients of ATE malformation (including 12 males and 15 females) from June 2014 to June 2018 in the current research. The patients were divided into the routine group (n = 12) and 3D printing group (n = 15) based on different operative methods. The parameters, including the operative time, intraoperative blood loss, complications, time to obtain bony fusion, functional outcomes based on American Orthopedic Foot and Ankle Society (AOFAS), and International Congenital Clubfoot Study group (ICFSG) scoring systems between the two groups were observed and recorded regularly. Results The 3D printing group exhibits superiorities in shorter operative time, less intraoperative blood loss, higher rate of excellent, and good outcomes presented by ICFSG score at last follow-up (P < 0.001, P < 0.001, P = 0.019) than the routine group. However, there was no significant difference exhibited in the AOFAS score at the last follow-up and total rate of complications between the two groups (P = 0.136, P = 0.291). Conclusion Operation assisted by 3D printing PSI osteotomy guide for correcting the ATE malformation is novel and feasible, which might be an effective method to polish up the precise osteotomy of ATE malformation and enhance the clinical efficacy.

Augmented Reality as a Tool to Guide PSI Placement in Pelvic Tumor Resections.

Patient-specific instruments (PSIs) have become a valuable tool for osteotomy guidance in complex surgical scenarios such as pelvic tumor resection. They provide similar accuracy to surgical navigation systems but are generally more convenient and faster. However, their correct placement can become challenging in some anatomical regions, and it cannot be verified objectively during the intervention. Incorrect installations can result in high deviations from the planned osteotomy, increasing the risk of positive resection margins. In this work, we propose to use augmented reality (AR) to guide and verify PSIs placement. We designed an experiment to assess the accuracy provided by the system using a smartphone and the HoloLens 2 and compared the results with the conventional freehand method. The results showed significant differences, where AR guidance prevented high osteotomy deviations, reducing maximal deviation of 54.03 mm for freehand placements to less than 5 mm with AR guidance. The experiment was performed in two versions of a plastic three-dimensional (3D) printed phantom, one including a silicone layer to simulate tissue, providing more realism. We also studied how differences in shape and location of PSIs affect their accuracy, concluding that those with smaller sizes and a homogeneous target surface are more prone to errors. Our study presents promising results that prove AR’s potential to overcome the present limitations of PSIs conveniently and effectively.

Effects of Patient-Specific Instrumentation and Ancillary Surgery Performed in Conjunction With Total Ankle Implant Arthroplasty: Postoperative Radiographic Findings

Accuracy and reproducibility when performing total ankle implant arthroplasty (TAA) are essential for longevity of the implant, maintaining relative stability of the joint, and theoretically reducing the formation of adjacent joint arthritis in the subtalar and knee joints. Studies have helped to illustrate the accuracy of implantation when using patient-specific instrumentation in both knee and ankle implant arthroplasty. Despite the findings of these studies, few have gone on to evaluate the effects of ancillary procedures on TAA; particularly their effects on postoperative implant congruity when performed simultaneously with joint replacement surgery. In this study, preoperative plans on implant alignment based on patient-specific computed tomography images were compared with the alignment observed on immediate postoperative radiographs. Additionally, postoperative joint congruity was measured, and operative reports were assessed to determine if concomitant procedures performed with total ankle replacement had a significant effect on overall alignment. In our population, 46/47 implants were within 1.5° of their anticipated placement in the coronal plane, and 100% were within 2° of anticipated placement in the sagittal plane. Using a spearman's rank-order correlation, our data failed to show any significant relationship between conducting additional procedures in conjunction with TAA (rho=0.178; p value=.232) and postoperative congruency of the implant. These findings help support the accuracy of ankle implantation using patient-specific instrumentation, while also supporting the appropriate use of indicated procedures in conjunction with total ankle replacement to help obtain a congruent joint postoperatively.

Flexible patient-specific instruments for maxillary repositioning during Le Fort I osteotomy

Flexible patient-specific instruments for maxillary repositioning during Le Fort I osteotomy

Do TKAs in Patients with Higher BMI Take Longer, and is the Difference Associated with Surgeon Volume? A Large-database Study from a National Arthroplasty Registry.

Increased surgical time in TKA may impact economic costs and clinical outcomes. Prior work has found that TKAs in patients with high BMI take longer, and these patients may be at greater risk for postoperative complications like infection. However, these studies included small numbers of patients and surgeons from single institutions and they did not consider surgeon volume. Using the New Zealand Joint Registry (NZJR), we asked: (1) Is there a relationship between increasing patient BMI and TKA operative time? (2) Is the effect of BMI on surgical time less pronounced among surgeons who perform more TKAs per year than those who perform fewer? Data were collected from the NZJR between January 2010 and December 2018 as it is the only national registry that records both BMI and surgical time. Primary TKA performed for osteoarthritis by surgeons with more than 50 TKAs over the period of the study were identified. BMI and operative time (skin incision to closure in minutes) were recorded. Patients with the following were excluded: lateral parapatellar or minimally invasive approaches; navigated, patient-specific instrumentation, or robot-assisted TKA; uncemented or hybrid fixation; those with procedures performed by a trainee (all or part); or a nonosteoarthritic indication. Of 64,108 TKAs performed during the study period, a total of 42% (27,057) met our inclusion criteria. The primary outcome was the effect of BMI on operative time. Operative time is expressed in minutes as a mean for each single-unit BMI increase across all surgeons, controlled for other variables that might influence operative time such as patella resurfacing and cruciate-retaining versus posterior-stabilized designs. Overall, the mean operative time (skin incision to closure) was 79 ± 22 minutes. Surgical experience was assessed by subdividing surgeons into six groups according to the number of TKAs performed annually (< 10, 10 to 24, 25 to 49, 50 to 74, 75 to 99, and > 100). Statistical analyses were performed including a general linear model to assess the independent association between BMI and operative time, allowing for the effects of other patient and surgical features. In addition, linear regression analyses explored the associations between BMI and operative time in the whole group and within surgical volume groups. There was an association between increasing BMI and increasing surgical duration. The mean operative time increased from 75 ± 22 minutes in patients with a normal BMI of 25 kg/m2 to 87 ± 24 minutes in patients with a BMI of 40 kg/m2 to 94 ± 28 minutes in patients with a BMI > 50 kg/m2 (p < 0.001). Surgeons performing fewer than 25 TKAs per year took 14% longer to perform a TKA on a patient with a BMI of 40 kg/m2 than on a patient with a normal BMI of 25 kg/m2. However, surgeons performing greater than 25 TKAs per year took 10% longer. In this study, an increase BMI was associated with increased surgical time in TKA. Surgical duration for high-volume surgeons appears less influenced by increases in BMI than lower volume surgeons. Although the absolute increase in duration was small, prolonged surgical time may reduce theater productivity. Even though the issues around managing patients with high BMI are multifactorial and complex, considerations from these findings include ensuring appropriate theater scheduling and possibly referring patients with high BMI to specialist centers. Further studies should focus on assessing the effectiveness of such measures in reducing complications and improving outcomes in patients with elevated BMI. Level III, therapeutic study.

Research progress of anterior femoral notching in total knee arthroplasty

To summarize the research progress of the causes and prevention methods of anterior femoral notching in total knee arthroplasty (TKA). The related literature at home and abroad about the causes and prevention methods of the anterior femoral notching in TKA was extensively reviewed and summarized. The reasons for the occurrence of anterior femoral notching can be summarized as follows: the application of the posterior reference technique, the increase of the posterior condylar angle, the variant anatomical shape of anterior femoral cortex, the selective reduction of the femoral prosthesis size, backward movement of the entrance point, and the application of computer-assisted navigation technology or patient-specific instrumentation. To prevent the occurrence of anterior femoral notching, programs such as flex the femoral prosthesis, robot-assisted technology, and anterior and posterior reference techniques combination can be used. Anterior femoral notching is a common surgical complication of TKA. A complete preoperative plan, assessment of the patient's knee joint condition, and development of a reasonable surgical plan can effectively reduce the occurrence of anterior femoral notching.