The Complex Process of Using the Interconnected Knee Arthroplasty Device Clearance Pathway

Background: The clearance of medical devices by the US Food and Drug Administration (FDA) has remained largely unchanged since 1976, when the Medical Device Amendments Act established a system classifying devices into 3 categories based on safety risk to the consumer. The system allows for the clearance of many orthopedics devices through the 510(k) premarket pathway, which is based on "predicate ancestors," previously cleared devices that are "substantially equivalent." Purpose: We sought to trace the predicate ancestors of modern total knee arthroplasty (TKA) devices, specifically those recently cleared for marketing by the 510(k) pathway that claim substantial equivalence to prior devices, despite potential differences in material science and design. In addition, we aimed to document which TKA devices cleared by the 510(k) pathway have substantial equivalence to devices that have since been recalled by the FDA. Methods: To create a comprehensive list of TKA devices, we used FDA Classification Process Codes corresponding to knee arthroplasty to search the FDA's databases from May 28, 1976, the start of the 510(k) process, to May 1, 2021. Of 1309 resulting devices, 89 were excluded as not related to arthroplasty. For each of the remaining devices, we analyzed the descendant devices that claimed substantial equivalence, either directly or indirectly. We used data of recalled designs to determine both the absolute number of recalled devices and the number of currently cleared devices that presented substantial equivalence claims upon predicates that have since been recalled. Results: Of 1220 knee devices cleared or approved, 6 (0.5%) were approved through the premarket approval application (PMA) process, and 1214 (99.5%) were cleared through the 510(k) pathway. Of the 1214 cleared devices, 217 (17.9%) have been recalled and 204 (16.8%) have ties to at least 1 recalled predicate device linked through generational claims of substantial equivalence. We found 90 devices (7.4%) linked directly to a recalled predicate device. Conclusions: Most knee arthroplasty devices are cleared for marketing through reliance on a complex web of equivalency to previously cleared predicates. We found that many TKA devices thus connected were cleared decades apart, with multiple iterations of design and material modifications. Many currently marketed TKA devices have claimed equivalency to predicates that have been recalled. Our findings suggest the need for novel regulatory strategies that might further patient safety while balancing the unwanted effects of regulatory burden.

Computed Tomography and Magnetic Resonance Imaging Overlay in the Spine for Surgical Planning: A Technical Report

BACKGROUND

Computed tomography (CT) and magnetic resonance imaging (MRI) studies are used separately for surgical planning of spine surgery. Advanced techniques exist for creating CT-MR fusion images, but at this time these techniques are not easily accessible for large-scale use.

TECHNIQUE

We propose a simple graphical technique for CT-MR image overlay, for use in the surgical planning of spinal decompression and guidance of intraoperative resection. The proposed technique involves overlaying a single cross-section from anatomically comparable MRI and CT studies on any software with basic image editing functions.

RESULTS

We demonstrate CT-MR fusion images of 8 patients of the senior author in which the technique was used. We found that it can also be referenced intraoperatively for navigation.

CONCLUSIONS

Compared to other techniques, our proposed method can be easily implemented by clinicians to create simple CT-MRI fusion images that can be useful for preoperative planning and intraoperative navigation.

Use of Implant-Mediated Guided Growth With Tension Band Plate in Skeletally Immature Patients With Knee Pathology: A Retrospective Review

Background: Skeletally immature patients with coronal plane angular deformity (CPAD) may be at increased risk for intra-articular pathology and patellofemoral instability (PFI). These patients may be candidates for implant-mediated guided growth (IMGG) procedures with tension band plates to address CPAD in addition to procedures for concomitant knee pathology. However, there are limited data on performing these procedures simultaneously. Questions/Purpose: We sought to demonstrate the feasibility of combined procedures to address both knee pathology and concomitant CPAD using IMGG in skeletally immature patients. Methods: We conducted a retrospective review of skeletally immature patients who underwent IMGG and concomitant surgery for anterior cruciate ligament reconstruction, osteochondritis dissecans repair, meniscus pathology, or PFI at a single institution by 2 surgeons between 2008 and 2019. Data on demographics, surgical details, follow-up, and complications were recorded. Deformity correction was assessed in a subset of eligible patients. Results: Of 29 patients meeting inclusion criteria, deformity correction was assessed in a subset of 17 patients (15 valgus, 2 varus). At final follow-up, 16 of 17 patients had mechanical tibiofemoral (mTFA) angles of <5° of varus or valgus. One patient developed "rebound" valgus >5° after plate removal. Conclusions: The IMGG performed in the setting of treating intra-articular knee pathology is feasible and should be considered for skeletally immature patients with CPAD undergoing surgery for concomitant knee pathology.

Surgical Scheduling Impacts Hospital Length of Stay and Associated Healthcare Costs for Patients Undergoing Total Hip and Knee Arthroplasty

BACKGROUND

Surgical scheduling, specifically the day of the week on which surgery is performed, has been associated with various postoperative outcomes in patients undergoing lower extremity joint arthroplasty.

PURPOSE

We sought to investigate surgical scheduling as a potential modifiable factor for patient quality metrics and related costs.

METHODS

In a retrospective prognostic study, all total knee and total hip arthroplasty (TKA/THA) cases that took place in 2017 to 2018 at a multihospital academic health system were queried. Patients were separated by the day of the week the surgery was performed, with Monday/Tuesday compared to Thursday/Friday. Outcomes included length of stay (LOS) (extended LOS defined as 3 days or longer), cost, and complications. Multivariable regression models measured associations between scheduling of surgery and outcomes; odds ratios (OR) and 95% confidence intervals (CIs) are reported.

RESULTS

Overall, 1,571 TKA and 992 THA patients were included (65% and 35%, respectively, performed on Monday/Tuesday and 70% and 30%, respectively, performed on Thursday/Friday). Patients undergoing TKA on Monday/Tuesday versus Thursday/Friday had higher American Society of Anesthesiologists scores (42% vs 33% with score of 3 or higher) but less often an extended LOS (31% vs 54%; adjusted OR: 2.76, 95% CI: 2.22-3.46), lower skilled nursing facility costs (unadjusted mean, $12,515 vs $14,154) and lower home health aide costs (unadjusted mean, $3,793 vs $4,192). Similar patterns were observed in THA patients.

CONCLUSION

These results from institutional data suggest that surgical scheduling is a modifiable factor possibly associated with postoperative outcomes. Furthermore, more rigorous study is warranted.

Decreased Implant Survival is Associated With Younger Patients Undergoing Total Knee Arthroplasty

Background: Younger patients are undergoing total knee arthroplasty (TKA) at increasing rates and may face multiple revisions during their lifetimes due to mechanical complications or infections. Questions/Purposes: We sought to compare the early complication rates and revision-free implant-survival rates across age groups of patients undergoing TKA, with particular focus on implant survival in younger patients. Methods: We conducted a retrospective analysis of data taken from a national insurance database on patients who underwent primary TKA from 2007 to 2015. Kaplan-Meier curve survival analysis and log rank test were performed to evaluate revision rates in 7 age groups (younger than 40, 40-49, 50-59, 60-69, 70-79, 80-89, and 90 or more years of age). Complication rates were compared to rates in the age 60 to 79 years age groups using multiple logistic regression, controlling for baseline demographics and comorbidities. Results: There were 114,698 patients included in the analysis. Patients in the younger than 40 years, 40 to 49 years, and 50 to 59 years age groups had increased rates of early mechanical complications; 90-day readmission rates were significantly higher in those age groups as well. Revision-free implant survival at 5 years was significantly worse in patients younger than 60 years of age, particularly those less than 40 years, who had a 77% revision-free implant-survival rate at 5 years. Conclusions: Younger patients had a higher risk of early revision after TKA, as well as an increased rate of mechanical complications and readmissions at 90 days. These outcomes suggest more study is needed to better understand these discrepancies and to better guide preoperative counseling for young patients considering TKA.

Improving Safety of Bilateral Knee Arthroplasty: Impact of Selection Criteria on Perioperative Outcome

Background: Bilateral total knee arthroplasty (BTKA) procedures are associated with an increased risk of complications when compared with unilateral approaches. In 2006, in an attempt to reduce this risk, our institution implemented selection criteria that specified younger and healthier patients as candidates for BTKA. Questions/Purpose: We sought to investigate the effect of these selection criteria on perioperative outcomes. Methods: In a retrospective cohort study, we used institutional data to identify patients who underwent BTKA between 1998 and 2014. Patients were divided into 2 groups: those who underwent surgery before the 2006 introduction of our selection criteria (1998-2006) and those who underwent surgery after (2007-2014). Groups were compared in terms of demographics, comorbidity burden, and incidence of perioperative complications. Regression analysis was performed, calculating incidence rate ratios to evaluate changes in complication rates. Results: Before the selection criteria were implemented in 2006, patients who underwent BTKA were older and had a higher comorbidity burden. The rate of major complications per 1000 hospital days decreased from 31.5 in 1998 to 7.9 in 2014. A reduction in cardiac complications was the most significant contributor to this decrease in major complications. Conclusion: After stringent criteria for BTKA candidates were implemented at our institution, selection of younger patients with lower comorbidity burden was accompanied by a reduction in the incidence of operative complications. This suggests that introducing such criteria can be associated with a reduction in adverse perioperative outcomes.

Bony Edema and Clinical Examination Findings Predict the Need for Distal Clavicle Excision at the Time of Shoulder Arthroscopy

Background: Deciding to perform a distal clavicle excision for acromioclavicular joint arthritis, especially in conjunction with other arthroscopic shoulder procedures, is challenging for surgeons. Studies have reported mixed results on the value of magnetic resonance imaging (MRI) in decision making. Purpose: We sought to correlate MRI findings with clinical symptoms and the surgeon's decision to perform a distal clavicle excision. Methods: We compared MRI, clinical examination, and MRI findings of 200 patients who underwent distal clavicle excision for symptomatic acromioclavicular joint arthritis with 200 patients who underwent arthroscopic shoulder procedures for other reasons. Univariate statistics were used to determine correlations between physical examination findings, MRI findings, and the decision to perform distal clavicle excision. A binary logistic regression model was used to determine independent predictors of need for distal clavicle excision. Results: There was no difference in mean age, sex, and race between groups. Advanced acromioclavicular joint osteoarthritis was strongly correlated with positive physical examination findings. Bony edema correlated strongly with tenderness at the acromioclavicular joint but not pain with cross-body adduction testing. There was no association between higher MRI grade of osteoarthritis and the need for distal clavicle excision. Regression analysis identified both physical examination findings and bony edema on MRI as independent predictors of the need for distal clavicle excision. Conclusion: In the setting of positive clinical examination findings and bony edema of the distal clavicle, surgeons should feel reassured that distal clavicle excision is likely indicated.

Less Invasive Pediatric Spinal Deformity Surgery: The Case for Robotic-Assisted Placement of Pedicle Screws

Introduction: Pediatric spinal deformity involves a complex 3-dimensional (3D) deformity that increases the risk of pedicle screw placement due to the close proximity of neurovascular structures. To increase screw accuracy, improve patient safety, and minimize surgical complications, the placement of pedicle screws is evolving from freehand techniques to computer-assisted navigation and to the introduction of robotic-assisted placement. Purpose: The aim of this review was to review the current literature on the use of robotic navigation in pediatric spinal deformity surgery to provide both an error analysis of these techniques and to provide recommendations to ensure its safe application. Methods: A narrative review was conducted in April 2021 using the MEDLINE (PubMed) database. Studies were included if they were peer-reviewed retrospective or prospective studies, included pediatric patients, included a primary diagnosis of pediatric spine deformity, utilized robotic-assisted spinal surgery techniques, and reported thoracic or lumbar pedicle screw breach rates or pedicle screw malpositioning. Results: In the few studies published on the use of robotic techniques in pediatric spinal deformity surgery, several found associations between the technology and increased rates of screw placement accuracy, reduced rates of breach, and minimal complications. All were retrospective studies. Conclusions: Current literature is of a low level of evidence; nonetheless, the findings suggest the accuracy and safety of robotic-assisted spinal surgery in pediatric pedicle screw placement. The introduction of robotics may drive further advances in less invasive pediatric spinal deformity surgery. Further study is warranted.

Comparing the Efficacy of Radiation Free Machine-Vision Image-Guided Surgery With Traditional 2-Dimensional Fluoroscopy: A Randomized, Single-Center Study

Background: Three-dimensional (3D) computer-assisted navigation (CAN) has emerged as a potential alternative to 2-dimensional (2D) fluoroscopy in the surgical placement of spinal instrumentation. Recently, 3D-CAN systems have improved significantly in their ability to provide real-time anatomical referencing while shortening the registration and set-up time. A novel system in navigation, Machine-Vision Image-Guided Surgery (MvIGS; 7D Surgical, Toronto, Canada) was cleared by the US Food and Drug Administration, but its potential benefits in reducing intra-operative radiation exposure to patients and enhancing surgical accuracy of pedicle screw placement are not fully known. Purpose: We sought to conduct a prospective, randomized, clinical study comparing the 3D-MvIGS spinal navigation system and 2D-fluoroscopy for pedicle screw insertion up to 3 levels (T10-S1) and for various measures of surgical efficacy. Methods: Sixty-two eligible patients were randomized to receive spine surgery using either the 3D-MvIGS group or the conventional 2D-fluoroscopy for pedicle screw fixation for the treatment of spinal stenosis and degenerative spondylolisthesis. Intra-operative parameters and procedure-related unintended protocol violations were recorded. Results: Operative time and estimated blood loss were not significantly different between groups. Radiation time and exposure to patients were significantly reduced in the 3D-MvIGS group. There was no difference between groups in pedicle screw placement accuracy (2D-fluoroscopy group, 96.6%; 3D-MvIGS group, 94.2%). There were no major complications or cases that required revision surgery. Conclusion: The 3D-MvIGS navigation system performed comparably with 2D-fluoroscopy in terms of pedicle screw placement accuracy and operative time. The 3D-MvIGS showed a significant reduction in radiation exposure to patients. In more complex cases or larger cohorts, the true value of greater anatomical visualization can be elucidated.