"Trend" Statement Use in the Orthopaedic Literature.

INTRODUCTION: For research to effectively guide clinical decision making, appropriate interpretation of data is paramount. The P-value is a useful tool for guiding the interpretation of data. However, despite its utility, the P-value is not without limitations. Of particular concern is the use of "trend statements" to describe non-statistically significant findings, a practice which introduces subjectivity and variability into data interpretation and can lead to the drawing of undue conclusions. METHODS: An audit of original research articles published from January 2022 to December 2022 in four high-impact orthopaedic journals was conducted. The selected journals were queried to identify instances in which a non-statistically significant result was labeled as a "trend." The use of trend statements and associated information was recorded and analyzed. RESULTS: One thousand two hundred sixty articles were included in the analysis. 81 articles (6.4%) included a trend statement to describe a non-statistically significant result. Only two articles (2.5%) formally defined what constituted a trend. In 28.8% of cases, the associated P-value was > 0.10. DISCUSSION: Trend statements are used to describe non-statistically significant findings with moderate frequency in the orthopaedic literature. Given the potentially misleading effects of trend statements, efforts should be made to mitigate their use. If trend statements are to be used, attention should be paid to defining what constitutes a "trend", explicitly acknowledging the lack of statistical significance of the finding to which the trend statement refers, and avoiding drawing undue conclusions from non-statistically significant data.

Preoperative planning with three-dimensional CT vs. three-dimensional magnetic resonance imaging does not change surgical management for shoulder instability.

Background: This study aims to determine the effect of time and imaging modality (three-dimensional (3D) CT vs. 3D magnetic resonance imaging (MRI)) on the surgical procedure indicated for shoulder instability. The hypothesis is there will be no clinical difference in procedure selection between time and imaging modality. Methods: Eleven shoulder surgeons were surveyed with the same ten shoulder instability clinical scenarios at three time points. All time points included history of present illness, musculoskeletal exam, radiographs, and standard two-dimensional MRI. To assess the effect of imaging modality, survey 1 included 3D MRI while survey 2 included a two-dimensional and 3D CT scan. To assess the effect of time, a retest was performed with survey 3 which was identical to survey 2. The outcome measured was whether surgeons made a "major" or "minor" surgical change between surveys. Results: The average major change rate was 14.1% (standard deviation: 7.6%). The average minor change rate was 12.6% (standard deviation: 7.5%). Between survey 1 to the survey 2, the major change rate was 15.2%, compared to 13.1% when going from the second to the third survey (P = .68). The minior change rate between the first and second surveys was 12.1% and between the second to third interview was 13.1% (P = .8). Discussion: The findings suggest that the major factor related to procedural changes was time between reviewing patient information. Furthermore, this study demonstrates that there remains significant intrasurgeon variability in selecting surgical procedures for shoulder instability. Lastly, the findings in this study suggest that 3D MRI is clinically equivalent to 3D CT in guiding shoulder instability surgical management. Conclusion: This study demonstrates that there is significant variability in surgical procedure selection driven by time alone in shoulder instability. Surgical decision making with 3D MRI was similar to 3D CT scans and may be used by surgeons for preoperative planning.

Graft Resorption After Posterior Distal Tibial Allograft Augmentation for Posterior Shoulder Instability: A Case Report.

CASE: A 19-year-old man underwent arthroscopic posterior glenoid reconstruction with a distal tibia allograft (DTA) after failing 2 posterior, soft-tissue instability surgeries. Although he experienced near-complete resolution of symptoms and return to sport, graft resorption was noted 7 months postoperatively. The patient underwent revision surgery for screw removal. CONCLUSION: Graft resorption has not previously been reported in the setting of arthroscopic DTA use for posterior instability. It is believed that stress shielding contributed to resorption. In such situations, screw removal may be warranted. Consideration of alternative fixation techniques and additional investigation into the causes, clinical significance, and optimal management of posterior DTA resorption are warranted.

The Finger, Wrist, and Shoulder are the Most Commonly Injured Areas in Youth Volleyball Players but the Incidence of Injuries Decreased Overall Between 2012 and 2022.

Purpose: To analyze epidemiology, mechanisms, and diagnoses of upper extremity volleyball injuries in youth who present to United States emergency departments. Methods: Data from the National Electronic Injury Surveillance System were analyzed for upper extremity volleyball injuries in patients ≤18 years old from January 1, 2012, to December 31, 2022. Data were collected for body part, diagnosis, mechanism of injury, and disposition. Weighted national estimates were calculated using the hospitals' corresponding statistical sample weights. Linear regressions were used to analyze annual trends. χ2 tests were used to analyze categorical variables. Results: A weighted national estimate of 131,624 upper extremity volleyball-related injuries occurred in the study period. Average age was 13.9 ± 2.3 years. Female patients constituted 77.6% of patients; 99.3% of patients did not require admission. The most common body parts injured were fingers (43.0%), wrists (22.8%), and shoulders (12.2%). The most common identifiable mechanisms of injury were impacts with the floor (19.4%), impacts with the ball (14.7%), and spikes/serves (5.7%). Most common diagnoses were strains/sprains (42.6%) and fractures (19.5%). Most common locations of fracture were fingers (57.4% of all fractures), wrists (16.6%), and lower arms (12.4%). There was a decrease of 544 overall injuries per year (P = .03, 95% confidence interval [CI] -1031 to -58). Female players experienced more contusions/abrasions (16.0% vs 9.9%, P < .001) and strains/sprains (46.1% vs 30.4%, P < .001) compared with male players. Female patients had decreases of 513 overall injuries (P = .01, 95% CI -881 to -144), 349 strains/sprains (P = .002, 95% CI -530 to -168), 102 contusions/abrasions (P = .008, 95% CI 170 to -34), and 92 fractures per year (P = .03, 95% CI -175 to -10). Conclusions: Youth volleyball players are at risk of upper extremity injury, particularly involving the fingers, wrist, and shoulder. Despite increasing national participation in youth volleyball, there is a decreasing incidence of upper extremity injuries. Level of Evidence: Level IV, prognostic case series.

Job satisfaction and practice characteristics of shoulder and elbow surgeons: a survey of American Shoulder and Elbow Surgeons society members.

BACKGROUND: The purpose of this study is to assess the current trends in fellowship training, career satisfaction, practice characteristics, and surgical case volume among shoulder and elbow surgeons. METHODS: A web-based, anonymous 25-item survey was sent to the membership of the American Shoulder and Elbow Surgeons (ASES) in October of 2022. Questions posed included respondent demographics, fellowship training, career satisfaction, practice characteristics, and surgical case characteristics. Descriptive statistics were performed to report demographic information, assess job and training satisfaction rates, and evaluate practice characteristics. Chi-squared and independent samples t-tests were performed to analyze satisfaction rates, job applications, and surgical case volume with regard to years in practice and practice setting. RESULTS: Twenty percent (243/1248) of ASES members satisfactorily completed the survey. Of the 243 ASES member respondents, 97% (236/243) stated that they would pursue their fellowship training again. Ninety-eight percent (239/243) of respondents were satisfied with their specialty choice. One-hundred percent (242/243) were satisfied with their training in shoulder. Seventy-two percent (176/243) were satisfied with their training in elbow. Seventy-four percent (179/243) were satisfied with their job availability and 85% (207/243) were satisfied with their job location. The mean total number of orthopedic surgical cases per year was 393 ± 171. The mean total number of shoulder cases per year was 253 ± 149. The mean total number of elbow cases per year was 41 ± 41. Physicians who have been in practice for 11 years or more were comparatively more satisfied (90% vs. 80%) with their job location (P value = .008) and job availability (81% vs. 64%, P value < .001). Additionally, senior surgeons completed more orthopedic (431 vs. 347, P value < .001) and shoulder (279 vs. 220, P value = .002) cases annually than surgeons earlier in their careers. Satisfaction rates, job applications, and surgical case volume did not associate with practice setting. CONCLUSIONS: The majority of ASES member shoulder and elbow surgeons are satisfied with their training, their case volume and complexity, and their specialty choice. Fewer surgeons are satisfied with their elbow training and overall elbow case volume remains low among shoulder and elbow surgeons. Shoulder and elbow surgeons earlier in their careers perform fewer surgical cases, are less satisfied with their job availability and location, and completed more job applications for their first job after fellowship when compared to more senior surgeons.

Post-operative Baseplate Radiographic Evaluation Using Routine pre-Operative CT.

Background: There is limited data evaluating post-operative component position and fixation in reverse shoulder arthroplasty (RSA). Therefore, the purpose of this study was to evaluate baseplate position and fixation using routine pre-operative CT and post-operative radiographs. Methods: A retrospective analysis of a series consecutive patient who underwent primary RSA was performed. Pre-operative and post-operative glenoid retroversion and inclination were measured using radiographs aligned with projection silhouettes of 3D scapula models in Mimics software. Baseplate retroversion and inclination were measured followed by evaluating for the presence of radiolucent lines (RLLs). Results: Twenty-four patients met inclusion criteria. The average age was 73.4 ± 10.7 years (range, 45-89 years). Radiographic follow-up was 3.4 ± 1.3 years. Post-operative glenoid baseplate retroversion was 2 ± 10 degrees (range, 30 to -9). Post-operative glenoid baseplate inclination was 3.8 ± 9.1 (range, -13 to 19). Five (21%) RSAs had baseplate retroversion >10 degrees. Follow-up radiographs revealed no RLLs around the baseplate, central post, or peripheral screws in any patient. Conclusions: Pre-operative CT imaging enabled evaluation of baseplate component placement and fixation on post-operative radiographs. Baseplate version was within 10 degrees of neutral in 79% (19/24) of patients. No RLLs or loss of fixation were found in any cases. Level of Evidence: Level IV: Diagnostic Study.

Determining the True Incidence of Glenohumeral Instability Among Players in the National Football League: An Epidemiological Study of Non-Missed Time Shoulder Instability Injuries.

Background: Shoulder instability encompasses a spectrum of glenohumeral pathology ranging from subluxation to dislocation. While dislocation frequently leads to removal from play, athletes are often able to play through subluxation. Previous research on glenohumeral instability among athletes has largely focused on missed-time injuries, which has likely disproportionately excluded subluxation injuries and underestimated the overall incidence of shoulder instability. Purpose: To describe the epidemiology of shoulder instability injuries resulting in no missed time beyond the date of injury (non-missed time injuries) among athletes in the National Football League (NFL). Study Design: Descriptive epidemiology study. Methods: The NFL's electronic medical record was retrospectively reviewed to identify non-missed time shoulder instability injuries during the 2015 through 2019 seasons. For each injury, player age, player position, shoulder laterality, instability type, instability direction, injury timing, injury setting, and injury mechanism were recorded. For injuries that occurred during games, incidence rates were calculated based on time during the season as well as player position. The influence of player position on instability direction was also investigated. Results: Of the 546 shoulder instability injuries documented during the study period, 162 were non-missed time injuries. The majority of non-missed time injuries were subluxations (97.4%), occurred during games (70.7%), and resulted from a contact mechanism (91.2%). The overall incidence rate of game-related instability was 1.6 injuries per 100,000 player-plays and was highest during the postseason (3.5 per 100,000 player-plays). The greatest proportion of non-missed time injuries occurred in defensive secondary players (28.4%) and offensive linemen (19.8%), while kickers/punters and defensive secondary players had the highest game incidence rates (5.5 and 2.1 per 100,000 player-plays, respectively). In terms of direction, 54.3% of instability events were posterior, 31.9% anterior, 8.5% multidirectional, and 5.3% inferior. Instability events were most often anterior among linebackers and wide receivers (50% and 100%, respectively), while posterior instability was most common in defensive linemen (66.7%), defensive secondary players (58.6%), quarterbacks (100.0%), running backs (55.6%), and tight ends (75.0%). Conclusion: The majority of non-missed time shoulder instability injuries (97.4%) were subluxations, which were likely excluded from or underreported in previous shoulder instability studies due to the inherent difficulty of detecting and diagnosing shoulder subluxation.

Clavicle Nonunion and Malunion: Surgical Interventions for Functional Improvement.

Clavicle nonunion and malunion are relatively uncommon but, when symptomatic, can result in pain and dysfunction that requires surgical intervention. Various reconstructive and grafting techniques are available to achieve stable fixation and union. In the setting of persistent nonunion, vascularized bone grafting may be necessary. A thorough understanding of the patient's type of nonunion and potential for healing is crucial for achieving satisfactory results because is thoughtful preoperative planning and surgical fixation.

Artificial intelligence-based applications in shoulder surgery leaves much to be desired: a systematic review.

Background: Artificial intelligence (AI) aims to simulate human intelligence using automated computer algorithms. There has been a rapid increase in research applying AI to various subspecialties of orthopedic surgery, including shoulder surgery. The purpose of this review is to assess the scope and validity of current clinical AI applications in shoulder surgery literature. Methods: A systematic literature review was conducted using PubMed for all articles published between January 1, 2010 and June 10, 2022. The search query used the terms as follows: (artificial intelligence OR machine learning OR deep learning) AND (shoulder OR shoulder surgery OR rotator cuff). All studies that examined AI application models in shoulder surgery were included and evaluated for model performance and validation (internal, external, or both). Results: A total of 45 studies were included in the final analysis. Eighteen studies involved shoulder arthroplasty, 13 rotator cuff, and 14 other areas. Studies applying AI to shoulder surgery primarily involved (1) automated imaging analysis including identifying rotator cuff tears and shoulder implants (2) risk prediction analyses including perioperative complications, functional outcomes, and patient satisfaction. Highest model performance area under the curve ranged from 0.681 (poor) to 1.00 (perfect). Only 2 studies reported external validation. Conclusion: Applications of AI in the field of shoulder surgery are expanding rapidly and offer patient-specific risk stratification for shared decision-making and process automation for resource preservation. However, model performance is modest and external validation remains to be demonstrated, suggesting increased scientific rigor is warranted prior to deploying AI-based clinical applications.

The subacromial bursa is a key regulator of the rotator cuff and a new therapeutic target for improving repair.

Rotator cuff injuries result in over 500,000 surgeries performed annually, an alarmingly high number of which fail. These procedures typically involve repair of the injured tendon and removal of the subacromial bursa. However, recent identification of a resident population of mesenchymal stem cells and inflammatory responsiveness of the bursa to tendinopathy indicate an unexplored biological role of the bursa in the context of rotator cuff disease. Therefore, we aimed to understand the clinical relevance of bursa-tendon crosstalk, characterize the biologic role of the bursa within the shoulder, and test the therapeutic potential for targeting the bursa. Proteomic profiling of patient bursa and tendon samples demonstrated that the bursa is activated by tendon injury. Using a rat to model rotator cuff injury and repair, tenotomy-activated bursa protected the intact tendon adjacent to the injured tendon and maintained the morphology of the underlying bone. The bursa also promoted an early inflammatory response in the injured tendon, initiating key players in wound healing. In vivo results were supported by targeted organ culture studies of the bursa. To examine the potential to therapeutically target the bursa, dexamethasone was delivered to the bursa, prompting a shift in cellular signaling towards resolution of inflammation in the healing tendon. In conclusion, contrary to current clinical practice, the bursa should be retained to the greatest extent possible and provides a new therapeutically target for improving tendon healing outcomes. One Sentence Summary: The subacromial bursa is activated by rotator cuff injury and regulates the paracrine environment of the shoulder to maintain the properties of the underlying tendon and bone.

Comparing Skill Acquisition and Validity of Immersive Virtual Reality with Cadaver Laboratory Sessions in Training for Reverse Total Shoulder Arthroplasty.

Immersive virtual reality (iVR) allows surgical trainees to practice skills without risking harm to patients or the need for cadaveric training resources. However, iVR has never been directly compared with cadaver training, the longtime gold standard for surgical skill training. We aimed to compare skill acquisition using cadaver laboratory and iVR training methods for augmented baseplate implantation during reverse total shoulder arthroplasty (rTSA). Methods: In a randomized controlled trial, junior orthopaedic surgery residents were assigned to a 1-hour training with either iVR or a cadaveric laboratory session with shoulder specimens. Before training, all participants viewed an overview lecture and technique video demonstrating key steps of augmented baseplate implantation for rTSA. Participants were assessed by a blinded evaluator using validated competency checklists during cadaveric glenoid baseplate implantation. Continuous and categorial variables were analyzed using the 2-sample t test and Fisher exact test. Results: Fourteen junior residents (3 incoming matched postgraduate year [PGY1], 6 PGY1s, 1 PGY2, and 4 PGY3s) were randomized to training with either iVR (n = 6) or cadaver laboratory (n = 8). There were no significant differences in demographic data, previous experience with rTSA, or previous use of iVR (p > 0.05). There were no significant difference in total Objective Structured Assessment of Technical Skill score (91.2% [15.2] vs. 93.25% [6.32], -0.1406 to 0.1823, p = 0.763), Global Rating Scale score (4.708 [0.459] vs. 4.609 [0.465], -0.647 to 0.450, p = 0.699), or time to completion (546 seconds [158] vs. 591 seconds [192], -176.3 to 266.8, p = 0.655) in cadaveric glenoid baseplate implantation. Average cost of iVR hardware and a 1-year software license was $4,900, and average cost of a single cadaver laboratory was $1,268.20 per resident. Conclusions: Among junior orthopaedic residents, there is similar skill acquisition when training with either cadaver laboratory or iVR. Although additional research into this field is needed, iVR may provide an important and cost-effective tool in surgical education. Clinical Relevance: Emerging simulation and iVR technology simulation in surgical training programs can increase access to effective and high-level surgical training across the globe and improve quality of care.

Orthopaedic Surgery Residency: Perspective of Applicants and Program Directors on Medical Student Virtual Experiences.

INTRODUCTION: Orthopaedic Residency Directors advised against visiting subinternship rotations in the peak of the pandemic. To adapt, programs offered multiple virtual experiences. The purpose of this study was to evaluate programs and applicants perceptions regarding the value of virtual experiences during the 2020 to 2021 application cycle and their utility in future application cycles. METHODS: A survey was disseminated to 31 residency programs gathering data about virtual experiences offered in this cycle. A second survey was disseminated to interns who have successfully matched at those programs to identify how interns think to have benefited from the experiences. RESULTS: Twenty-eight programs completed the survey (90% response rate). One hundred eight new interns completed the survey (70% response rate). Virtual information sessions and resident socials were the highest attended (94% and 92%, respectively). Interns and leadership agreed that virtual rotations provided students with a good understanding of program culture and what the programs offer educationally. Neither the leadership nor the interns would recommend replacing in-person aways with virtual experiences. CONCLUSION: Virtual experiences helped bridge the gap after away rotations were canceled. Alongside in-person aways, virtual experiences are likely to play a role in future cycles. However, virtual experiences remain incomparable to in-person away rotations and are not recommended as a replacement.

Quantifying the Opportunity Cost of Resident Involvement in Academic Orthopedic Shoulder Arthroplasty: A Matched - Pair Analysis.

Background: There is minimal work defining the economic impact of resident participation in shoulder arthroplasty. Thus, this study quantified the opportunity cost of resident participation in total shoulder arthroplasty (TSA) and hemiarthroplasty (HA) by determining differences in operative time, relative value units (RVUs)/hour, and RVUs/case. Methods: A retrospective analysis of shoulder arthroplasty procedures were identified from the ACS-NSQIP database from 2006 to 2014 using CPT codes. Demographic, comorbidity, preoperative laboratory data and surgical procedure were used to develop matched cohorts. Mean differences in operative time, RVUs/case and RVUs/hour between attending-only (AO) cases and cases with resident involvement (RI) were examined. Cost analysis was performed to identify differences in RVUs generated per hour in dollars/case. Results: A total of 1786 AO and 1102 RI cases were identified. With the exception of PGY-3 and PGY-4 cases, RI cases had lower mean operative times compared to AO cases. The cost of RI was highest for PGY-3 ($199.87 per case) and PGY-4 ($9 .2 9) residents with all other postgraduate years providing a cost reduction. Discussion: Involvement of residents was associated with shorter operative times leading to a savings of $29.64 per case. Involvement of intermediate-level (PGY-3) residents were associated with increased costs that ultimately decreased as residents became more senior.

Machine Learning Can Accurately Predict Overnight Stay, Readmission, and 30-Day Complications Following Anterior Cruciate Ligament Reconstruction.

PURPOSE: This study aimed to develop machine learning (ML) models to predict hospital admission (overnight stay) as well as short-term complications and readmission rates following anterior cruciate ligament reconstruction (ACLR). Furthermore, we sought to compare the ML models with logistic regression models in predicting ACLR outcomes. METHODS: The American College of Surgeons National Surgical Quality Improvement Program database was queried for patients who underwent elective ACLR from 2012 to 2018. Artificial neural network ML and logistic regression models were developed to predict overnight stay, 30-day postoperative complications, and ACL-related readmission, and model performance was compared using the area under the receiver operating characteristic curve. Regression analyses were used to identify variables that were significantly associated with the predicted outcomes. RESULTS: A total of 21,636 elective ACLR cases met inclusion criteria. Variables associated with hospital admission included White race, obesity, hypertension, and American Society of Anesthesiologists classification 3 and greater, anesthesia other than general, prolonged operative time, and inpatient setting. The incidence of hospital admission (overnight stay) was 10.2%, 30-day complications was 1.3%, and 30-day readmission for ACLR-related causes was 0.9%. Compared with logistic regression models, artificial neural network models reported superior area under the receiver operating characteristic curve values in predicting overnight stay (0.835 vs 0.589), 30-day complications (0.742 vs 0.590), reoperation (0.842 vs 0.601), ACLR-related readmission (0.872 vs 0.606), deep-vein thrombosis (0.804 vs 0.608), and surgical-site infection (0.818 vs 0.596). CONCLUSIONS: The ML models developed in this study demonstrate an application of ML in which data from a national surgical patient registry was used to predict hospital admission and 30-day postoperative complications after elective ACLR. ML models developed performed well, outperforming regression models in predicting hospital admission and short-term complications following elective ACLR. ML models performed best when predicting ACLR-related readmissions and reoperations, followed by overnight stay. LEVEL OF EVIDENCE: IV, retrospective comparative prognostic trial.

My Reverse Has Failed: Top Five Complications and How to Manage Them.

Reverse total shoulder arthroplasty implantation has increased dramatically over the past 4 decades since it was first introduced in France in 1985. It has greatly improved the ability to treat patients with cuff tear arthropathy, proximal humeral fractures, and osteoarthritis with severe bone loss. However, with the increased implementation of reverse total shoulder arthroplasty, there has been a corresponding rise in complications. Five of the most common complications following reverse total shoulder arthroplasty are instability, scapular fractures, periprosthetic humeral fractures, glenoid baseplate loosening, and infection.

Preference-Signaling During the Orthopaedic Surgery Residency Application Process.

The orthopaedic surgery residency selection process has grown more competitive over recent years, with programs receiving an unprecedented number of applications. As an effort to target applications to programs of interest, the American Orthopaedic Association has announced the introduction of a formal preference-signaling program into the 2022 to 2023 orthopaedic surgery residency selection cycle. This system will allow applicants to assign "signals" to a total of 30 programs. The purpose of this article was to (1) discuss implications of the new preference-signaling program, (2) introduce the framework of the "strategic signaling spear" for applicants to conceptualize the power of all methods of preference-signaling to improve their odds of matching, and (3) describe the role of strong mentorship at all stages of the residency application process.

Comparison of glenoid bone grafting vs. augmented glenoid baseplates in reverse shoulder arthroplasty: a systematic review.

BACKGROUND: Management of bone loss and glenoid deformity can present a significant challenge to surgeons. The purpose of this review was to compare outcomes of reverse shoulder arthroplasty (RSA) using either bone graft or augmented baseplates for the management of glenoid bone loss and deformity. METHODS: A comprehensive search of MEDLINE, Embase, and Cochrane indices was performed for studies reporting clinical outcomes following primary RSA with bone grafting or use of augmented baseplates. Pooled and frequency-weighted means, standard deviations, and ranges were calculated and reported for comparison. RESULTS: Overall, 19 studies and 652 patients with bone grafting (n = 401) and augmented baseplates (n = 251) were included in the study. Mean patient age and gender were 70.3 ± 3.1 years and 47% female in the bone grafting group and 72.9 ± 3.7 years and 59.0% female in the augmented baseplate group. Mean follow-up for the augmented baseplate group was 23.1 ± 8.2 months and 29.5 ± 10.1 months for the bone grafting group. Overall complication and revision rates were 11.7% and 4.5% for the bone grafting group and 11.8% and 3.7% for the augmented baseplate group. Range of motion as well as patient-reported and functional outcome scores were similar between both techniques. Infections, component loosening, and notching were 1.9%, 3.6%, and 24.6% in the bone grafting group and 0.7%, 1.6%, and 4.7% in the augmented baseplate group. CONCLUSIONS: Glenoid bone grafting and augmented baseplates are effective treatment options for the management of bone loss and glenoid deformity. Both treatments improve overall clinical outcomes with relatively low complication rates and revision rates.