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Background: The Knee Society Clinical Rating System was developed in 1989 and has been widely adopted. However, with the increased demand for TKA, there is a need for a new, validated scoring system to better characterize the expectations, satisfaction, and physical activities of the younger, more diverse population of TKA patients.Questions/purposes: We developed and validated a new Knee Society Scoring System.Methods: We developed the new knee scoring system in two stages. Initially, a comprehensive survey of activities was developed and administered to 101 unilateral TKA patients (53 women, 48 men). A prototype knee scoring instrument was developed from the responses to the survey and administered to 497 patients (204 men, 293 women; 243 postoperatively, 254 preoperatively) at 15 medical institutions within the United States and Canada. Objective and subjective data were analyzed using standard statistical and psychometric procedures and compared to the Knee Injury and Osteoarthritis Score and SF-12 scores for validation. Based on this analysis, minor modifications led to the new Knee Society Scoring System.Results: We found the new Knee Society Scoring System to be broadly applicable and to accurately characterize patient outcomes after TKA. Statistical analysis confirmed the internal consistency, construct and convergent validity, and reliability of the separate subscale measures.Conclusions: The new Knee Society Scoring System is a validated instrument based on surgeon- and patient-generated data, adapted to the diverse lifestyles and activities of contemporary patients with TKA. This assessment tool allows surgeons to appreciate differences in the priorities of individual patients and the interplay among function, expectation, symptoms, and satisfaction after TKA. [ABSTRACT FROM AUTHOR]

Unlabelled: With substantial interest devoted to improving knee flexion after TKA, it is important to document the relationship between high range of motion and patient-rated outcomes shown. We therefore asked whether single-design high-flexion mobile-bearing posterior-stabilized TKA resulted in: (1) improved knee function; (2) satisfying subjective results; (3) participation recreational and sporting activities; and (4) function correlated to the final range of motion. We prospectively followed 445 consecutive patients having 516 TKAs from September 2000 to January 2005. The same high-flexion posterior-stabilized mobile-bearing implant was used in all patients. Mean patient age was 71 +/- 8 years and mean body mass index was 28 +/- 4 kg/m(2). The minimum clinical followup was 2 years (mean, 3 years; range, 2-4 years). The postoperative range of knee flexion was 128 degrees +/- 4 degrees and the mean Knee Society function and knee scores were 91 +/- 6 and 96 +/- 3, respectively. Eighty-two percent of patients were involved in sporting activities and 86% returned to their previous level of activity. These data confirm that high postoperative range of knee flexion improve patient-rated outcomes.Level Of Evidence: Level IV, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence. [ABSTRACT FROM AUTHOR]

The results of TKA during the past two decades have been reliable and favorable. While success rates are high, some patients experience pain and impaired function. This clinical scenario can be frustrating to both the patient and the surgeon who is accustomed to good outcomes. A systematic evaluation of the patient and arthroplasty can lead to a definitive diagnosis of the cause of the patient's symptoms. Problems can be caused by a broad spectrum of possible etiologies. It is helpful to divide the differential diagnosis into two broad categories: extra-articular and intra-articular etiologies. When trying to establish the diagnosis, it is important to approach the task in a systematic fashion. Evaluation must begin with a thorough history and physical examination. Laboratory tests and imaging studies can provide additional evidence supporting a particular diagnosis. Once the etiology has been established, symptomatic relief may be achieved with appropriate treatment including revision TKA. However, revision TKA that is performed for unexplained pain is associated with a low probability of success. [ABSTRACT FROM AUTHOR]

Patellar tendon (PT) rupture following total knee arthroplasty (TKA) is a rare, but devastating complication. These injuries occur most frequently in the acute period following TKA due to trauma to the knee. PT ruptures that disrupt the extensor mechanism create a marked functional deficit, impacting every facet of daily life. In complete ruptures of the PT, repair or reconstruction is typically indicated; however, complication rates following intervention remain high. Operative intervention remains the mainstay of treatment, with only certain specific situations where nonoperative intervention is appropriate. Operative techniques are chosen based on the acuity, location of disruption, and status of the residual soft tissues. Treatment options include repair with or without augmentation or reconstruction. Augmentation does reduce the high risk of complications, bringing rates down from 63 to 25%. Augmentation options include autografts, allografts, synthetic grafts, or synthetic meshes. Despite advancements, outcomes are unpredictable and complications are common, highlighting the need for further research to improve treatment protocols. This article provides an overview of PT ruptures following TKA, the various treatment options, and the recommendations of the M.M., R.D., G.S. for each common type of PT injury encountered., Competing Interests: M.A.M. report royalties from Medicus Works LLC, Stryker and consulting fee from 3M, Exactech, Inc, Johnson & Johnson, Kolon TissueGene, Next Science, Pacira, Smith & Nephew, Stryker, also payment or honoraria from Johnson & Johnson, Medtronic, National Institutes of Health (NIAMS & NICHD), Organogenesis, Orthofix, Inc, Patient-Centered Outcomes Research Institute (PCORI), Stryker. He is in leadership role in American Association of Hip and Knee Surgeons, Hip Society, Knee Society. Also has stocks in CERAS Health, MirrorAR, Peerwell, USMI.R.E.D. is a board member of Baltimore City Medical Society. He reports research support from : Biocomposites, Inc.; CyMedica Orthopedics; DePuy Synthes Product, Inc.; Flexion Therapeutics; Microport; Orthopedics, Inc.; Orthofix, Inc.; Patient-Centered Outcomes Research Institute (PCORI); Smith & Nephew; Stryker; Tissue Gene; and United Orthopedic Corporation.G.S. reports royalties from Biomet, Springer, Zimmer and consulting fee from 3M, Biomet, KCI, Zimmer. Also Payment or honoraria from 3M, Biomet, Next Science and stocks from Enhanced medical nutrition, Force Therapeutics, ROM Tech., (Thieme. All rights reserved.)

Post-traumatic arthritis (PTA) of the knee is a complex problem, requiring foresight and careful preoperative planning. Each case of PTA is unique, requiring understanding of the altered anatomy, management of any retained hardware, and also the ability to provide the appropriate stability for each affected knee. Successful treatment of PTA with total knee arthroplasty (TKA) requires the creation of stable and well-balanced joint. TKA for PTA provides comparable improvements in pain and function when compared with primary osteoarthritis, however, these patients are at increased risk of post-operative complications, including instability and infection., Competing Interests: Disclosure The authors have nothing to disclose., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Background: Sensor technology embedded within the total knee arthroplasty (TKA) implant has the potential to record data that can track recovery and provide diagnostic information. In this study, we introduce the concept of physical function recovery curve analytics, which are created from daily spatial-temporal gait metrics and step counts from a large cohort of TKA patients., Methods: In our study population, 258 patients underwent a primary TKA with a smart implanted tibial extension between October 4, 2021, and July 15, 2022, by 33 surgeons. The average age was 63 years, with 138 (54%) women. All kinematic data were collected on a Health Insurance Portability and Accountability Act-compliant cloud data management platform., Results: Summaries of the gait parameters at 6 weeks are suggestive of differences between people over and under 65 years, with the older patients walking more slowly and having shorter stride lengths. The 6-week percentiles demonstrated a strong linear correlation to the 12-week percentiles for each gait parameter, with correlation coefficients ranging from 0.87 to 0.92., Conclusions: A novel screening gait test at 6 weeks shows promising results for predicting patients who will likely have poor recovery based on at least one gait parameter recovery curve at 12 weeks with high sensitivity and specificity. A future study is needed to validate the screening tool with an independent set of patients., (Copyright © 2024. Published by Elsevier Inc.)

» Patellar instability is challenging to address, and although there are many surgical options, proximal patellar realignment (PPR) and medial patellofemoral ligament (MPFL) reconstruction are both used-recently, the MPFL reconstruction has become more popularized.» Both procedures have demonstrated similar recurrent dislocation rates and rates of arthritic progression.» PPR is a cost-efficient procedure using just suture alone as compared with MPFL reconstruction, which uses different grafts and methods of fixation.» PPR has demonstrated durable results, with a lower overall complication rate, much of which is caused by the MPFL reconstruction having unique complications due to fixation methods.» The PPR is a beneficial procedure and should still be considered when dealing with patellar instability., Competing Interests: Disclosure: The Disclosure of Potential Conflicts of Interest forms are provided with the online version of the article (http://links.lww.com/JBJSREV/B152)., (Copyright © 2024 by The Journal of Bone and Joint Surgery, Incorporated.)

Periprosthetic patella fractures are a rare complication that can lead to severe disability following total knee arthroplasty (TKA). There are several factors that increase the risk of this injury, including patient comorbidities, anatomic considerations, and surgical technique. With these factors limiting healing ability in the area, periprosthetic patellar fractures can pose a major challenge to treat, with potentially lasting morbidity for affected patients. These fractures can occur at any time following TKA and are classified based on their associated implant stability and disruption of the extensor mechanism using the Ortiguera and Berry classification system. Each of the three types of fractures can be managed in their own unique way; however, outcomes remain poor, and the complication rates remain high regardless of fracture type. This article provides an overview of the current literature and the recommended management of periprosthetic patella fractures., Competing Interests: None declared., (Thieme. All rights reserved.)

Background: Artificial intelligence in the field of orthopaedics has been a topic of increasing interest and opportunity in recent years. Its applications are widespread both for physicians and patients, including use in clinical decision-making, in the operating room, and in research. In this study, we aimed to assess the quality of ChatGPT answers when asked questions related to total knee arthroplasty., Methods: ChatGPT prompts were created by turning 15 of the American Academy of Orthopaedic Surgeons Clinical Practice Guidelines into questions. An online survey was created, which included screenshots of each prompt and answers to the 15 questions. Surgeons were asked to grade ChatGPT answers from 1 to 5 based on their characteristics: (1) relevance, (2) accuracy, (3) clarity, (4) completeness, (5) evidence-based, and (6) consistency. There were 11 Adult Joint Reconstruction fellowship-trained surgeons who completed the survey. Questions were subclassified based on the subject of the prompt: (1) risk factors, (2) implant/intraoperative, and (3) pain/functional outcomes. The average and standard deviation for all answers, as well as for each subgroup, were calculated. Inter-rater reliability (IRR) was also calculated., Results: All answer characteristics were graded as being above average (ie, a score > 3). Relevance demonstrated the highest scores (4.43 ± 0.77) by surgeons surveyed, and consistency demonstrated the lowest scores (3.54 ± 1.10). ChatGPT prompts in the Risk Factors group demonstrated the best responses, while those in the Pain/Functional Outcome group demonstrated the lowest. The overall IRR was found to be 0.33 (poor reliability), with the highest IRR for relevance (0.43) and the lowest for evidence-based (0.28)., Conclusions: ChatGPT can answer questions regarding well-established clinical guidelines in total knee arthroplasty with above-average accuracy but demonstrates variable reliability. This investigation is the first step in understanding large language model artificial intelligence like ChatGPT and how well they perform in the field of arthroplasty., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Background: Anatomic referencing in total knee arthroplasty places the femoral component flush to the anterior cortex while maintaining posterior condylar offset (PCO). The intent of this study was to evaluate how component position influences the femoral component size., Methods: Digital surface models were created using 446 femora from an established computed tomography database. Virtual bone resections, component sizing, and component placement were performed assuming neutral (0°) flexion and neutral (3°) rotation relative to the posterior condyles. The appropriately sized femoral component, which had 2 mm of incremental size, was placed flush with the anterior cortex for optimal restoration of the PCO. Sizing and placement were repeated using 3 and 6° flexion and 0, 5, and 7° external rotation (ER)., Results: At 0° flexion, decreasing ER from 3 to 0° resulted in an average decreased anterior-posterior height (APH) of 1.9 mm, corresponding to a component size decrease of 1 for 88% of patients. At 7° ER, component size increased by an average of 2.5 mm, corresponding to a size increase for 80% of patients. Flexing the femoral component to 3° with ER at 3° resulted in a decrease in APH of 2.2 mm (1 size decrease in 93% of patients). At 3° flexion and 3° ER, 86% had the same component size as at 0° flexion and 0° ER. Increasing ER at 3° flexion increased APH by 1.2 mm at 5° and 3.1 mm at 7° on average, relative to 3° ER. Increasing flexion from 3 to 6° extended this effect., Conclusions: Flexion decreases the APH when the ER is held constant. The ER of the femoral component increases the APH across all tested flexion angles, causing an increase in the ideal femoral component size to maintain PCO. With anatomic referencing, alterations in femoral component positioning and subsequent changes in component size can be accounted for., (Copyright © 2024 Elsevier Inc. All rights reserved.)

This report provides an updated analysis for patients with osteoporosis following total hip arthroplasty (THA). The comorbidities of alcohol abuse, chronic kidney disease, cerebrovascular disease, obesity, and rheumatoid arthritis continue to be significant risk factors for periprosthetic femur fracture (PPFFx) and aseptic loosening in the population with osteoporosis. Patients with dual-energy x-ray absorptiometric (DEXA) scans were at risk for PPFFx regardless of femoral fixation method, and patients with DEXA scans with cementless fixation were at risk of aseptic loosening after THA. The patient population with severe osteoporosis may have higher risks for aseptic loosening and PPFFx than previously recognized., (Copyright © 2024 Elsevier Inc. All rights reserved.)

One of the critical steps in total knee arthroplasty is femoral component positioning and sizing. Historically, there was wider variability between femoral component sizes, necessitating the concepts of anterior referencing (AR) and posterior referencing (PR). With the introduction of smaller increments between sizes, the concept of anatomic referencing has been introduced to replace AR and PR. The intent of this study was to validate the concept of anatomic referencing and show that with 2 mm increments in femoral sizes, the femoral component can be placed flush to the anterior cortex while maintaining posterior condylar offset (PCO). Digital surface models were created using 515 femurs from an established computed tomography database. Virtual bone resections, component sizing and placement were performed assuming neutral mechanical axis and a cartilage thickness of 2 mm. The appropriately sized femoral component, which had 2 mm incremental sizes, was placed flush with the anterior cortex with restoration of the PCO. The anterior-posterior distance from the posterior surface of the component to the medial and lateral surfaces of the posterior condylar cartilage were measured. The medial condyle was the limiting condyle in the majority of cases (73%). The average medial gap after appropriate femoral component matching was 0.6 mm (0.39-1.41 mm) across all sizes. The overall average condylar gap was 1.02 mm. The most common femoral component was a size 7 (57.2 mm) and the average femoral AP width was 55.9 mm. Anatomic referencing with an implant system that has 2-mm increments in femoral component sizing provides an alternative to AR and PR without compromise. Anatomic referencing allows for perfect alignment of the anterior flange of the femoral component to the anterior cortex of the femur while restoring the native PCO to within 1 mm. This avoids having to choose between AR or PR when in between femoral sizes., Competing Interests: J.B. reports being a board member of Orthopaedic Research Society. Stocks Zimmer Biomet. G.R.S. reports royalties from Zimmer Biomet. Consulting fee from Zimmer Biomet, 3M KCI, and Canary. Payment or honoraria from Zimmer Biomet and 3M KCI. Participation on a Advisory Board of Canary and Enhanced Medical Nutrition. Stocks of ROM Tech, KAT Robotics, and Enhanced Medical Nutrition., (Thieme. All rights reserved.)

Testosterone replacement therapy (TRT) is an indicated treatment of several medical conditions including late-onset hypogonadism, congenital syndromes, and gender affirmation hormonal therapy. Increasing population age, medical benefits, and public awareness of TRT have resulted in increased prevalence of its utilization. However, TRT is not without concern for adverse risks including venous thromboembolic complications, cardiovascular events, and prostate issues. In the field of orthopaedic surgery, research is beginning to delineate the complex relationship between TRT and the development of orthopaedic conditions and potential effects on surgical interventions and outcomes. In this review, we discuss current literature surrounding TRT and subsequent development of osteoarthritis, incidence of total joint arthroplasty, musculotendinous pathology, postoperative infection risk, improvements in postoperative rehabilitation metrics, enhancement of osseous healing, and increased bone-implant integration. The authors suggest future areas of investigation that may provide guidance on how surgeons can mitigate adverse risks while optimizing benefits of TRT in the orthopaedic patient., (Copyright © 2024 by the American Academy of Orthopaedic Surgeons.)

Introduction: Prosthetic joint infection (PJI) risk continues to receive much attention given its associated morbidity and costs to patients and healthcare systems. It has been hypothesized that invasive colonoscopies may increase the risk of PJI. However, the decision to administer antibiotic prophylaxis lacks clinical guidance. In this study we aimed to compare PJI rates in patients undergoing colonoscopies with and without antibiotic prophylaxis against a control group, analyzing PJI occurrences at 90 days, 6 months, 9 months, and 1-year post-procedure and (2) assess the impact of antibiotic prophylaxis on PJI rates to inform clinical guidelines., Methods: We queried a national, all-payer database to identify all primary total knee arthroplasty procedures without prior history of PJI between January 2010 and October 2020 (n = 1.9 million). All patients who had a diagnosis of PJI within one year of index procedure were excluded. There were three cohorts identified: colonoscopy with biopsy without antibiotic prophylaxis; colonoscopy with biopsy with antibiotic prophylaxis; and a control of no prior colonoscopy. Both colonoscopy cohorts were slightly younger and had higher comorbidities than the controls. The PJI diagnoses were identified at four separate time intervals within one-year after colonoscopy: 90-days; 6-months; 9-months; and 1-year. Chi -square analyses with odds ratios (ORs) and 95% confidence intervals were conducted for PJI rates between groups at all time-points., Results: Among all cohorts, no significant differences in PJI rates were found at 90-days ( P  = 0.459), 6-months ( P  = 0.608), 9-months ( P  = 0.598), and 1-year ( P  = 0.330). Similarly, direct comparison of both colonoscopy groups, with and without antibiotic prophylaxis, demonstrated no PJI rate differences at 90-day ( P  = 0.540), 6-months ( P  = 0.812), 9-months ( P  = 0.958), and 1-year ( P  = 0.207). Ranges of ORs between the colonoscopy cohorts were 1.07-1.43., Conclusion: Invasive colonoscopy does not increase the risk of PJI in patients who have pre-existing knee implants. Furthermore, antibiotic prophylaxis may not be warranted in patients undergoing colonoscopy who have a planned biopsy., Competing Interests: JD- None. DH-None. SB- None. MA- None. GS- 3 M: Paid presenter or speakerBiomet: IP royalties; Paid consultant; Paid presenter or speaker Force Therapeutics: Stock or stock Options Journal of Knee Surgery: Editorial or governing board KCI: Paid consultant Operation Walk USA: Board or committee member ROM Tech: Stock or stock Options SpringerElsevierThiemeWorld Scientific: Publishing royalties, financial or material support Zimmer: IP royalties; Paid consultant; Paid presenter or speaker. JN- Arthritis Foundation: Board or committee member, Journal of Arthroplasty, Journal of the American Osteopathic Medicine Association, Orthopedic, Knowledge Online: Editorial or governing board, Journal of Knee Surgery: Editorial or governing board, Knee: Editorial or governing board, Microport: Paid consultant; Paid presenter or speaker; Research support, Stryker: Research support United: Research support RD- Baltimore City Medical Society.: Board or committee member, Biocomposites, Inc.: Research support, CyMedica Orthopedics: Research support, DePuy Synthes, Product, Inc.: Research support, Flexion Therapeutics: Research support, Microport Orthopedics, Inc.: Research support, Orthofix, Inc.: Research support,Patient-Centered Outcomes Research Institute (PCORI): Research support, Smith & Nephew: Research support, Stryker: Research support, Tissue Gene: Research support, United Orthopedic Corporation: Research support MM-receives consultant fees from Stryker 3MCentrexion CERAS Health Johnson & Johnson Kolon Tissuegene Mirror-AR NXSCI Pacira Peerwell Pfizer Lily Skye Biologics SOLVD Health Smith & Nephew, payments for lectures from Stryker, leadership role for The Knee Society The Hip Society Journal of Arthroplasty Journal of Knee Surgery Surgical Technology International Orthopedics and stock options from CERAS Health MirrorAR Peerwell USMI., (© 2024 Professor P K Surendran Memorial Education Foundation. Published by Elsevier B.V. All rights reserved.)

Historically, anterior referencing and posterior referencing are two specific techniques that surgeons can use for proper sizing of the femoral component in total knee arthroplasty (TKA). In this review, we introduce the concept of "anatomic referencing" which has become useful with more incremental sizes of the femoral component to more perfectly match the native anatomy of each patient and reduce overstuffing of the patellofemoral joint and medial-lateral (ML) overhang. Fifty consecutive TKA cases were reviewed where the novel anatomic referencing technique was used. Lateral radiographic projections were obtained preoperatively and postoperatively. The posterior condylar offset (PCO) was evaluated on the lateral radiographs by measuring the distance between the tangent line of the femoral diaphysis posterior cortex and the posterior condylar margin. PCO ratio (PCOR) was calculated by dividing the PCO by the distance between the posterior condylar border and a tangent line along the anterior cortex of the femoral diaphysis. Forty-five patients (50 TKAs) were reviewed. Average age of the patients was 70.34, range: 47-91. There were 19 males and 26 females reviewed in this series. On average, the delta PCOR was 0.022 (standard deviation = 0.032; min: -0.049, max: 0.082). When grouping our results into three main groups: < -0.03, -0.03 to 0.03, and > 0.03, we found that 62% fell within the -0.03 to 0.03 range. There was no statistically significant difference in delta PCOR between standard and narrow implants ( p  = 0.418). The proposed novel anatomic referencing technique has allowed for proper sizing of patients' femurs in the anteroposterior and ML direction while avoiding component overhang or the need for component downsizing to obtain a proper ML fit. This radiographic review confirmed this to be a highly accurate and reproducible technique., Competing Interests: None declared., (Thieme. All rights reserved.)

Competing Interests: None declared.

An estimated 10 to 15% of total knee arthroplasties (TKAs) are implanted for a diagnosis of arthritis when a valgus deformity is present. There are various techniques and considerations that must be considered for a successful TKA in a patient with a valgus deformity. This article provides a detailed summary of the anatomy, pathology, bone preparation, soft tissue management, implant selection, and complications when performing a TKA in a patient with valgus deformity., Competing Interests: None declared., (Thieme. All rights reserved.)

A review article summarizes the existing literature on intraoperative injury to medial collateral ligament (MCL) during total knee arthroplasty (TKA), methods of fixation, repair, and the outcomes after these injuries. The options for increasing implant constraint and repair of the MCL injury are discussed with the potential indications for each. There is also a review of risk factors for MCL injury during TKA to help anticipate potential issues preoperatively. The proper use of retractors during total knee replacement is also discussed with a focus on careful protection of the MCL during surgery., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Background: Post anesthesia care units (PACU) await return of motor function in lower extremities, prior to discharge for patients undergoing spinal anesthesia. The purpose of this study was to assess the impact of a newly utilized recovery protocol that facilitated early discharges of patients undergoing total hip and knee arthroplasties (THA/TKA) to the floor before full motor recovery from spinal anesthesia is achieved., Methods: A total of 647 patients undergoing spinal anesthesia for primary THA (n = 190) and TKA (n = 457) were divided into 2 groups: (1) Early PACU discharge group: patients with partial or full motor blockade at discharge. (2) Control PACU discharge group: patients with full motor recovery at discharge. Readiness for discharge was assessed using a modified Aldrete Score system. The primary outcome was incidences of hypotension or rapid responses post-operatively., Results: There was no significant difference in the incidence of hypotension between the two groups (1.4 versus 1.39%, P = 1.0) and zero rapid responses were noted. Early discharge shortened mean PACU LOS time from 86.50 minutes to 70.27 minutes (P < .01). There was no difference in the incidence of nausea (0.55 versus 0%; P = .51) ordizziness (2.22 versus 0.35%; P = .09)., Conclusion: In this retrospective observational study, we found that early PACU discharge did not result in an increase in hemodynamic consequences on the surgical floor. Thus, discharge from PACU can be safely and more expeditiously performed without waiting for return of motor function in patients receiving spinal anesthesia for THA/TKA using a modified Aldrete Score recovery protocol., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Case: A 79-year-old man status post total knee arthroplasty (TKA) sustained atraumatic nondisplaced fracture of the inferior pole of the patella 1 year postoperatively. The patient had full radiographic healing and clinical resolution. Two years after injury, the patient reported new-onset knee pain and was found to have atraumatic inferior migration of the patellar component. The lateral radiograph appeared to demonstrate 2 patellae, coined "the double-patella sign.", Conclusion: Nondisplaced patellar fractures after TKA should be monitored even after full osseous healing for component loosening. Inferior migration of a loose patellar component can mimic 2 patellae on the lateral radiograph, mimicking a double patella., Competing Interests: Disclosure: The Disclosure of Potential Conflicts of Interest forms are provided with the online version of the article (http://links.lww.com/JBJSCC/C237)., (Copyright © 2023 by The Journal of Bone and Joint Surgery, Incorporated.)