The Tibial Tuberosity-Trochlear Groove Distance Can either Increase or Decrease during Adolescent Growth.

Increased Tibial Tuberosity-Trochlear Groove (TT-TG) distance is a risk factor for recurrent lateral patella dislocations (RLPD). Population-based cross-sectional studies on healthy subjects demonstrate that the TT-TG increases gradually during growth until skeletal maturity, but changes in the TT-TG distance during adolescence in patients with RLPD on an individual basis have not been previously investigated. This study aimed to measure changes in TT-TG distance during skeletal maturity. The TT-TG of 13 consecutive patients with open physes (mean age 13 years) with RLPD was measured on MRI at baseline and three years later. The change in TT-TG distance over the three-year period was measured. The mean change in TT-TG distance from the baseline to the three-year follow-up increased overall (2.9 mm, 95% Confidence Interval (CI) 2.1-3.7). However, the TT-TG distance could either increase or decrease during final growth. Our results suggest that the TT-TG distance in patients suffering from RLPD may either decrease or increase individually during the growth spurt. This contradicts the current concept that the TT-TG distance increases gradually during growth.

Body Mass Index Did Not Affect the Risk of Revision 3-9 Years After Total Knee Replacement Surgery.

Background: There are conflicting reports in the literature regarding the risk of revision after primary total knee replacement (TKR) in obese patients. The purpose of this study was to investigate if body mass index (BMI) influences the risk of revision 3-9 years after primary TKR. Methods: All patients undergoing a primary TKR in our institution from 2014 to 2018 were included in a retrospective study. The effect of BMI on all-cause revision was estimated in a logistic regression analysis. A directed acyclic graph was created to identify variables affecting the primary endpoint (revision). According to the directed acyclic graph, adjustment was only needed for age and smoking. However, we also included variables thought to influence the revision risk based on clinical experience and previous research. The final logistic regression analysis was therefore adjusted for age, sex, smoking status, diabetes mellitus and the American Society of Anesthesiologists classification. Results: One thousand fifty-nine primary TKR patients with a mean age of 68.1 (standard deviation 9.4) years were included. There were 609 (57.5%) women, and the median follow-up time was 5.6 (range 3.0-9.0) years. There were 41 (3.9%) revisions. BMI did not affect the risk of revision when adjusted for relevant covariates in a multivariate logistic regression analysis (odds ratio 0.99, 95% confidence interval 0.93-1.05, P = .6). Conclusions: BMI did not influence the risk of revision rate 3-9 years after TKR.

Autologous Chondrocyte Implantation Is Not Better Than Arthroscopic Debridement for the Treatment of Symptomatic Cartilage Lesions of the Knee: Two-Year Results From a Randomized-Controlled Trial.

Purpose: To compare the functional and patient-reported outcome measures after autologous chondrocyte implantation (ACI) and arthroscopic debridement (AD) in symptomatic, isolated cartilage injuries larger than 2 cm2 in patients aged 18 to 50 years. Methods: Twenty-eight patients were included and randomized to ACI (n = 15) or AD (n = 13) and followed for 2 years. The primary outcome was the change in the Knee injury and Osteoarthritis Outcome Score (KOOS) Quality of Life (QoL) subscale. Results: The mean age at inclusion was 34.1 (standard deviation [SD] 8.5) years. There were 19 (68%) male patients. The mean size of the lesion was 4.2 (SD 1.7) cm2. There was a statistically significant and clinically meaningful improvement in patient-reported outcome measures from baseline to 2 years in both groups. The improvement from baseline to final follow-up for the primary endpoint (the KOOS QoL subscale) was larger for the AD group (39.8, SD 9.4) compared with the ACI group (23.8, SD 6.7), but this difference was not statistically significant (P = .17). However, according to a mixed linear model there were statistically significantly greater scores in the AD group for several KOOS subscales at several time points, including KOOS QoL, KOOS pain, and KOOS sport and recreation at 2 years. Conclusions: This study indicates that AD followed by supervised physiotherapy is equal to or better than ACI followed by supervised physiotherapy in patients with isolated cartilage lesions of the knee larger than 2 cm2. The improvement in KOOS QoL score from baseline to 2 years was clinically meaningful for both groups (23.8 points for ACI and 39.8 points AD), and larger for the AD group by 16 points. Level of Evidence: Level I, prospective randomized controlled trial.

Prevalence of malpractice claims after arthroscopic shoulder surgery: analysis of 69,097 procedures from a national registry in Norway.

BACKGROUND: Systematic analysis of compensation claims following patient injuries is helpful in improving patient safety. The objective of the current study was to assess compensation claims after arthroscopic treatment of rotator cuff ruptures, impingement, and acromioclavicular joint osteoarthritis reported to the Norwegian System of Patient Injury Compensation and evaluate if there was regional variation on the risk of patient injuries leading to an accepted compensation claim. METHODS: Data from the Norwegian System of Patient Injury Compensation and the Norwegian Patient Registry (NPR) from 2008 to 2018 were collected. Demographics (age and sex) and type of claim and reasons for accepted claims were obtained from the Norwegian System of Patient Injury Compensation, while the number of arthroscopic procedures was collected from NPR. The treating institutions were grouped on geography according to Norway's four regional Health Trusts and private institutions and the effect of geography on the probability of an accepted claim was estimated. RESULTS: NPR registered 69,097 shoulder arthroscopies during the study period, of which 216 (0.3%) compensation claims were filed for patient injury. A total of 38% of the claims were accepted, representing 0.1% of the arthroscopic procedures. Infection (37.8%) was the most common reason for accepted claim, followed by no surgical indication (15.9%) and wrong surgical technique (12.2%). We found a statistically significantly increased odds ratio for a claim being accepted in both the smallest and largest regional Health Trusts compared to the other regional Health Trusts and private institutions. CONCLUSIONS: Compensation claims due to patient injury following shoulder arthroscopy are rare (0.3% of patients file a claim, of which a third is accepted (0.1% of all shoulder arthroscopy patients)). The most common reason for accepted claim was infection followed by lack of indication.

Compensation Claims After Hip Fracture Surgery in Norway 2008-2018.

Background: Surgical complications contribute to the significant mortality following hip fractures in the elderly. The purpose of this study was to increase our knowledge of surgical complications by evaluating compensation claims following hip fracture surgery in Norway. Further, we investigated whether the size and location of performing institutions would influence surgical complications. Methods: We collected data from the Norwegian System of Patient Injury Compensation (NPE) and the Norwegian Hip Fracture Register (NHFR) from 2008 to 2018. We classified institutions into 4 categories based on annual procedure volume and geographical location. Results: 90,601 hip fractures were registered in NHFR. NPE received 616 (.7%) claims. Of these, 221 (36%) were accepted, which accounts for .2% of all hip fractures. Men had nearly a doubled risk of ending with a compensation claim compared to women (OR: 1.8, CI, 1.4-2.4, P < .001). Hospital-acquired infection was the most frequent reason for accepted claims (27%). However, claims were rejected if patients had underlying conditions predisposing to infection. Institutions treating fewer than 152 hip fractures (first quartile) annually, had a statistically significant increased risk (OR: 1.9, CI, 1.3-2.8, P = .005) for accepted claims compared to higher volume facilities. Discussion: The fewer registered claims in our study could be due to the relatively high early mortality and frailty in this patient group, which may decrease the likelihood of filing a complaint. Men could have undetected underlying predisposing conditions that lead to increased risk of complications. Hospital-acquired infection may be the most significant complication following hip fracture surgery in Norway. Lastly, the number of procedures performed annually in an institution influences compensation claims. Conclusions: Our findings indicate that hospital acquired infections need greater focus following hip fracture surgery, especially in men. Lower volume hospitals may be a risk factor.

Evidence-based objective performance criteria for the evaluation of hip and knee replacement devices and technologies.

BACKGROUND: Objective performance criteria (OPC) is a novel method to provide minimum performance standards and improve the regulated introduction of original or incremental device innovations in order to prevent patients from being exposed to potentially inferior designs whilst allowing timely access to improvements. We developed 2-year safety and effectiveness OPC for total hip and knee replacement (THR and TKR). METHODS: Analyses of large databases were conducted using various data sources: a systematic literature review; a direct data analysis from The Functional Outcomes Research for Comparative Effectiveness in Total Joint Replacement and Quality Improvement Registry (FORCE-TJR) and the Kaiser Permanente Implant Registry (KPIR); and claims data analyses from longitudinal discharge data in New York and California states. The literature review included U.S. patients (≥18 years) who received THR or TKR for primary end-stage osteoarthritis and prospectively collected data on patient-reported outcome measures (PROMs) from at least 100 subjects and/or 2-year implant survival for at least 250 implants. Random effects models were used for meta-analysis. RESULTS: Data were available from a total of 951 100 patients. After screening of 7979 abstracts, 294 studies underwent full-text review and 31 studies contributed to the evidence synthesis (333 995 implants). Direct data analysis of FORCE-TJR contributed 9223 joint replacement patients to the construction of OPC for effectiveness; KPIR contributed 262 044 patients for the construction of OPC for safety. Claims database analysis contributed 345 838 patients to the construction of safety OPC. OPC for safety were constructed for cumulative incidences of 2-year all-cause and septic revision (THR/TKR 2.0%/1.6% and 0.6%/0.7%), and OPC for effectiveness were constructed based on four disease-specific and three general health-related quality of life PROMs (HOOS/KOOS 87.1/80.6; HSS/KSS function 94.4/90.6; SF-12/SF-36, PCS 46.5/41.9, EQ-5D 0.88/0.84). CONCLUSION: This study is the first to construct a 2-year OPC for the safety and effectiveness of THR and TKR based on U.S. real-world data. Based on these OPC, potential benchmarks for (single-arm study) evaluation of new device innovations are suggested for a regulated and safe introduction to the (commercial) market.

Analysis of Polyethylene-Related Revisions After Total Ankle Replacements Reported in US Food and Drug Administration Medical Device Adverse Event Database.

BACKGROUND: There are 2 general types of total ankle replacement (TAR) designs with respect to the polyethylene insert, mobile-bearing (MB) and fixed-bearing (FB) TARs. The aim of this study is to compare polyethylene-related adverse events (AEs), particularly revisions, reported for MB TARs and FB TARs using the US Food and Drug Administration's (FDA's) Manufacturer and User Facility Device Experience (MAUDE) database. METHODS: A text mining method was applied to the medical device reporting (MDR) in the MAUDE database from 1991 to 2020, followed by manual reviews to identify, characterize, and describe all polyethylene-related AEs, including revisions, reported for MB and FB TARs. RESULTS: We found 1841 MDRs for MB (STAR Ankle only) and 1273 MDRs for 40+ FB TARs approved/cleared by the FDA. For the MB design, 33% (606/1841) of the AEs reported related to the polyethylene component, compared to 24% (291/1273) of the AEs reported for FB designs. Polyethylene fractures were reported in 11.3% (208/1841) for the MB designs compared to 0.2% (2/1273) for the FB designs. Half of the polyethylene-related revisions occurred within an average of 4.1 years after implantation for the MB design compared within an average of 5.2 years for FB designs. CONCLUSION: Analysis of this database revealed a higher proportion of reported polyethylene fractures and greater need for earlier revisions for polyethylene-related issues with use of the primary MB design in the database as compared with FB TAR designs. Further study of device-related complications with more recent designs for both MB and FB ankle replacement components are needed to improve the outcomes of total ankle replacement. LEVEL OF EVIDENCE: Level III, retrospective comparative study.

Association between single leg hop tests and patient reported outcome measures and patellar instability in patients with recurrent patellar dislocations.

Objectives: To assess the associations between the single leg hop tests at two premises; baseline and the change after 12 months, and change in patient reported outcome measures and persistent instability after 12 months in patients with recurrent lateral patellar dislocation (RLPD). Methods: 61 RLPD patients aged 12-30 with a mean (±SD) of 19.2 (±5.3) were assessed at baseline, and at 12 months after treatment with either active rehabilitation alone, or medial patellofemoral ligament reconstruction and active rehabilitation. Single leg hop for distance, triple hop for distance, crossover hop for distance and 6-metre timed hop were performed for both legs, and the Limb Symmetry Index (LSI) was calculated. Persistent patellar instability was self-reported as 'Yes' or 'No' at 12-month follow-up. Knee function in sport and recreational activities and knee-related quality of life were assessed at baseline and 12 months follow-up using the Knee injury and Osteoarthritis Outcome Score (KOOS). Results: LSI for the baseline single leg hop for distance and the triple hop for distance was significantly associated with persistent patellar instability at 12 months follow-up with an OR of 0.94 (95% CI 0.88 to 0.99) and OR of 0.91 (95% CI 0.84 to 0.99), respectively. No other statistically significant associations were detected. Conclusion: Individuals with higher LSI values for the single leg hop for distance and triple hop for distance conducted at baseline had lower odds for persistent patellar instability at 12 months follow-up. Clinicians can use results from these hop tests to assess the risk of future recurrent patellar instability prior to treatment. Study design: Retrospective cohort study. Trial registration number: NCT02263807.

The Effect of Ulnar Styloid Fractures on Patient-Reported Outcomes After Surgically Treated Distal Radial Fractures.

Ulnar styloid fractures (USFs) are often associated with distal radial fractures (DRFs). When unstable DRFs are treated surgically, any associated USF is most commonly left untreated. The purpose of this study was to evaluate the effect of a concomitant USF on outcome after surgical stabilization of a DRF. Methods: Data from 2 randomized controlled trials on the treatment of unstable DRFs were pooled. The effect of a USF on the QuickDASH, EQ-5D, pain, and range of motion at 2 years was evaluated. Results: Two hundred and eighty-one patients were included; 177 (63%) had an associated, untreated USF. An unadjusted analysis demonstrated no significant difference in functional or patient-reported outcome measures (PROMs) at 2 years between patients with or without a concomitant USF. When controlling for confounding factors, the presence of a USF did not predict change in any of the PROMs from baseline to 2 years. A concomitant USF also did not predict change in grip strength or range of motion, except for a small effect on extension (-4.1°; 95% confidence interval, -7.5° to -0.8°; p = 0.02), which probably does not have clinical relevance. Conclusions: A USF in combination with a DRF does not affect PROMs, range of motion, or grip strength. We recommend that concomitant USFs be left untreated when treating a DRF with surgical fixation. Level of Evidence: Prognostic Level I. See Instructions for Authors for a complete description of levels of evidence.

Two-Year Revision Rates in Total Ankle Replacement Versus Ankle Arthrodesis: A Population-Based Propensity-Score-Matched Comparison from New York State and California.

The aim of this study was to compare outcomes between total ankle replacement (TAR) and ankle arthrodesis (AA) for ankle osteoarthritis using real-world data. Methods: We used longitudinal claims data from New York State from October 2015 to December 2018, and from California from October 2015 to December 2017. The primary outcome was revision. Secondary outcomes were in-hospital complications and below-the-knee amputation. Propensity-score matching adjusted for differences in baseline characteristics. To determine predictors of the main outcome, each group was analyzed using multivariable Cox regressions. Results: There were 1,477 TAR procedures (50.2%) and 1,468 AA procedures (49.8%). Patients undergoing TAR were less likely to belong to a minority group and had fewer comorbidities compared with those undergoing AA. Crude analyses indicated that the TAR group had a lower risk of revision (5.4% versus 9.1%), in-hospital complications (<1% versus 1.8%), and below-the-knee amputation (<1% versus 4.9%) (p < 0.001 for all). However, in the propensity-score-matched analysis, the risk of revision was no longer significantly lower (TAR, 5.6% versus AA, 7.6%; p = 0.16). In the multivariable analyses, older age was predictive of a lower risk of revision after TAR (hazard ratio [HR], 0.96 [95% confidence interval (CI), 0.93 to 1.00]), but age was not predictive of revision after AA (HR, 0.99 [95% CI, 0.97 to 1.01]). Female patients were less likely to undergo revision after AA (HR, 0.61 [95% CI, 0.39 to 0.96]), but sex was not predictive of revision after TAR (HR, 0.90 [95% CI, 0.51 to 1.60]). Conclusions: The 2-year adjusted revision risk was 5.6% after TAR and 7.6% after AA. This difference did not reach significance. Older age was a predictor of lower revision risk after TAR. Men had a higher risk of revision than women after AA. The number of TAR procedures has now caught up with the number of AA procedures. Level of Evidence: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

The Effect of Lesion Size on Pain and Function in Patients Scheduled for Cartilage Surgery of the Knee.

OBJECTIVE: Despite an increased interest in treatment options for cartilage lesions of the knee, the relationship between lesion characteristics and the symptoms they elicit is not well understood. We evaluated the relationship between lesion characteristics and the patient-reported outcome measures (PROMs) and compared this with symptoms reported by patients scheduled for knee ligament reconstruction and knee arthroplasty. DESIGN: Preoperative data, including Lysholm score and The Knee Injury and Osteoarthritis Outcome Score (KOOS), in 90 consecutive patients scheduled for surgery for symptomatic isolated cartilage lesions were prospectively collected. RESULT: The patients had a mean age of 33.2 years. There were 62 (69%) males. There was no statistically significant difference in PROMs between patients with cartilage lesions smaller or larger than 2 cm2, except for the KOOS subscale symptoms, with patients with smaller lesions reporting higher scores, 62.8 (95% confidence interval [CI] 58.3-67.3) vs. 51.9 (95% CI 45.5-58.4), P = 0.005. There was a small correlation between lesion size and Lysholm score. However, when adjusted for age, sex, body mass index, and lesion localization, this effect was not statistically significant. The International Cartilage Regeneration & Joint Preservation Society grade did not affect preoperative PROMs. Cartilage patients reported worse preoperative symptoms than patients scheduled for knee ligament reconstruction, and approaching the symptoms reported by patients scheduled for knee arthroplasty. CONCLUSION: The size, depth, and location of cartilage lesions have little impact on the symptoms experienced by the patients. Cartilage patients have comparable symptoms to patients scheduled for knee arthroplasty.

Medial patellofemoral ligament reconstruction is superior to active rehabilitation in protecting against further patella dislocations.

PURPOSE: Isolated reconstruction of the medial patellofemoral ligament (MPFL-R) has become the predominant stabilizing procedure in the treatment of recurrent lateral patellar dislocation (LPD). To minimize the risk of re-dislocations, isolated MPFL-R is recommended in patients with no significant trochlea dysplasia and tibial tuberosity trochlear groove distance < 20 mm on computed tomography (CT). Incidentally, these criteria are the same that are used to identify first time LPD patients where conservative treatment is recommended. The purpose of this study was therefore to compare MPFL-R with active rehabilitation for patients with recurrent LPD (RLPD) in absence of the above mentioned underlying anatomical high-risk factors for further patellar dislocations. METHODS: RLPD-patients aged 12-30 without underlying anatomical high-risk factors for further LPD were randomized into treatment either with isolated MPFL-R or active rehabilitation provided and instructed by a physiotherapist. All patients underwent diagnostic arthroscopy for concomitant problems. The main outcome measure was persistent patellar instability at 12 months. Knee function at baseline and 12 months was asses using the following patient reported outcomes measures (PROMS); KOOS, Kujala, Cincinnati knee rating, Lysholm score and Noyes sports activity rating scale. RESULTS: Between 2010 and 2019, 61 patients were included in the study (MPFL-R, N = 30, Controls, N = 31). Persistent patellar instability at 12 months was reported by 13 (41.9%) controls, versus 2 (6.7%) in the MPFL-group (RR 6.3 (95% CI 1.5-25.5). No statistically significant differences in activity level were found between the MPFL-group and the Controls at neither baseline nor follow up. The patients with persistent instability at 12 months did not score significantly lower on any of the PROMs compared to their stable peers, regardless of study group. CONCLUSION: Patients with recurrent patellar dislocations have a six-fold increased risk of persistent patellar instability if treated with active rehabilitation alone, compared to MPFL-R in combination with active rehabilitation, even in the absence of significant anatomical risk factors. Active rehabilitation of the knee without MPFL-R improves patient reported knee function after one year, but does not protect against persistent patellar instability.

Patient-Reported Outcome, Return to Sport, and Revision Rates 7-9 Years After Anterior Cruciate Ligament Reconstruction: Results From a Cohort of 2042 Patients.

BACKGROUND: Long-term patient-reported outcome measures (PROMs), rates of return to sport, and revision risk after anterior cruciate ligament (ACL) reconstruction (ACLR) are not well understood. PURPOSE: To provide long-term follow-up of PROMs, return-to-sport rates, and revision rates after ACLR and to identify predictors for poor outcome. STUDY DESIGN: Case-control study; Level of evidence, 3. METHODS: A total of 2042 patients were included in an institutional ACL registry (2009-2013) and longitudinally followed. PROMs were completed preoperatively and at all follow-up time points. Questions regarding return to sport and knee stability were completed at final follow-up. Predictors for poor outcome on the International Knee Documentation Committee (IKDC) score were estimated in a regression model incorporating risk factors such as patient characteristics, graft choice, and concomitant injuries. Revision rates and risk of subsequent non-ACL surgeries were calculated. RESULTS: Autografts were used in 76% of the patients (patellar tendon, 62%; hamstring grafts, 38%). Allografts were used in 24% of patients. The questionnaires were returned by 1045 (51.2%) patients at a mean of 7.2 years (range, 5.0-9.8 years) after surgery. Improvements in IKDC score of >30 points were sustained for all patient categories. The strongest predictor for lesser improvement in IKDC score was a cartilage lesion >2 cm2 identified during surgery. Male sex and college education completion were associated with improved IKDC scores. Meniscal lesions did not predict change) in the IKDC score. A total of 69% of patients had returned to sport after 8.1 years (range, 6.7-9.8 years). The main reason for not returning to sport was fear of reinjury. The revision rate was 7.2% after 9 years (range, 8-11 years), 13% of patients needed subsequent ipsilateral non-ACL surgery, and 6% underwent contralateral ACLR. The absence of a meniscal tear, younger age, and male sex were predictors for revision. Graft choice did not predict PROM results or revision risk. CONCLUSION: Improvements in IKDC scores were sustained 7 years after ACLR. The strongest predictor for poor outcome was a cartilage lesion >2 cm2. Patients can expect a 70% return-to-sport rate and an 87% chance of their knee feeling stable during daily and athletic activities after 8 years. Young male patients have better PROM scores but a higher risk of revision. There is a 26% chance of subsequent knee surgery within 9 years, including a revision rate of 7%, subsequent non-ACL surgery to the operated knee in 13%, and a 6% chance of contralateral ACLR.

Can Generic Outcome Questionnaires Replace QuickDASH in Monitoring Clinical Outcome Following Surgical Treatment of Distal Radius Fractures?

PURPOSE: In contrast to region-specific patient-reported outcome measures (PROMs), generic PROMs can be argued to have an added benefit of enabling cost-utility analyses and allowing for comparisons to be made across different conditions. The aim of this study was to assess the responsiveness and strength of the association between region-specific and generic PROMs in patients treated operatively for a displaced intra-articular distal radius fracture. METHODS: Over a 4-year period, 166 patients aged 18-70 years with a displaced intra-articular fracture of the distal radius were treated with either a volar locking plate or external fixation augmented by K-wires and followed-up prospectively for 2 years. The main outcome measure was the Quick Disabilities of the Arm, Shoulder, and Hand (QuickDASH) score, but EuroQol-5D (EQ-5D) and 36-Item Short Form Survey (SF-36) were also employed. The associations between the QuickDASH score and EQ-5D and between the QuickDASH score and SF-36 were assessed using a linear mixed model. RESULTS: There was a significant positive association between the QuickDASH score and EQ-5D and between the QuickDASH score and SF-36 throughout the follow-up period, although wide dispersion existed for the outcome measures at an individual level. However, the association between the QuickDASH score and SF-36 was significantly weaker at 6 weeks and 3 months than that at baseline, indicating that EQ-5D more closely mirrors changes in the QuickDASH score in the early postoperative period. CONCLUSIONS: The study demonstrates that the QuickDASH score and EQ-5D correlate well on a group level, but large individual variations exist. The SF-36 had decreased sensitivity for the changes in the QuickDASH score at 6 weeks and 3 months. CLINICAL RELEVANCE: Our findings indicate that generic PROMs cannot fully replace the region-specific QuickDASH score when evaluating the outcomes of distal radius fractures.

Differences in Baseline Characteristics and Outcome Among Responders, Late Responders, and Never-Responders After Anterior Cruciate Ligament Reconstruction.

BACKGROUND: Loss to follow-up in registry studies might affect generalizability and interpretation of results. PURPOSE: To evaluate the effect of nonresponder bias in our anterior cruciate ligament (ACL) registry. STUDY DESIGN: Case-control study; Level of evidence, 3. METHODS: A total of 2042 patients with ACL reconstruction in the Hospital for Special Surgery ACL Registry between 2009 and 2013 were included in the study. Patients who completed the patient-reported outcome measures at 2 or 5 years were considered responders (n = 808). Baseline data and patient characteristics were compared between responders and nonresponders (n = 1234). Both responders and nonresponders were contacted and invited to complete the International Knee Documentation Committee (IKDC) and Marx scores electronically and respond to questions regarding return to sports and subsequent surgeries. Nonresponders who completed the questionnaires after reminders were considered late responders. The remaining nonresponders were considered never-responders. The late responders (n = 367) completed the questionnaires after a mean follow-up of 7.8 years (range, 6.7-9.6 years), while follow-up for the responders was 6.8 years (range, 5.0-9.7 years). Responders and late responders were then compared in terms of differences in IKDC and Marx scores from baseline to final follow-up. RESULTS: Nonresponders were younger (28.5 vs 31.5 years; P < .001) and more often male (60% vs 53%; P = .003) compared with responders. Responders had a higher level of education and were more likely to be White (79% vs 74%; P = .04). There were no substantial differences in patient characteristics or baseline IKDC and Marx scores between the late responders and never-responders. There were no statistically significant differences in patient-reported outcomes, return to sports, or subsequent surgeries between responders and late responders at a mean follow-up time of 8.8 years (range, 6.7-9.7 years). Repeat email reminders and telephone calls increased response rate by 18% (from 40% to 58%). CONCLUSION: There was no difference in clinical outcome as evaluated using IKDC and Marx scores between responders and late responders.

Application of Machine Learning Algorithms to Predict Clinically Meaningful Improvement After Arthroscopic Anterior Cruciate Ligament Reconstruction.

BACKGROUND: Understanding specific risk profiles for each patient and their propensity to experience clinically meaningful improvement after anterior cruciate ligament reconstruction (ACLR) is important for preoperative patient counseling and management of expectations. PURPOSE: To develop machine learning algorithms to predict achievement of the minimal clinically important difference (MCID) on the International Knee Documentation Committee (IKDC) score at a minimum 2-year follow-up after ACLR. STUDY DESIGN: Case-control study; Level of evidence, 3. METHODS: An ACLR registry of patients from 27 fellowship-trained sports medicine surgeons at a large academic institution was retrospectively analyzed. Thirty-six variables were tested for predictive value. The study population was randomly partitioned into training and independent testing sets using a 70:30 split. Six machine learning algorithms (stochastic gradient boosting, random forest, neural network, support vector machine, adaptive gradient boosting, and elastic-net penalized logistic regression [ENPLR]) were trained using 10-fold cross-validation 3 times and internally validated on the independent set of patients. Algorithm performance was assessed using discrimination, calibration, Brier score, and decision-curve analysis. RESULTS: A total of 442 patients, of whom 39 (8.8%) did not achieve the MCID, were included. The 5 most predictive features of achieving the MCID were body mass index ≤27.4, grade 0 medial collateral ligament examination (compared with other grades), intratunnel femoral tunnel fixation (compared with suspensory), no history of previous contralateral knee surgery, and achieving full knee extension preoperatively. The ENPLR algorithm had the best relative performance (C-statistic, 0.82; calibration intercept, 0.10; calibration slope, 1.15; Brier score, 0.068), demonstrating excellent predictive ability in the study's data set. CONCLUSION: Machine learning, specifically the ENPLR algorithm, demonstrated good performance for predicting a patient's propensity to achieve the MCID for the IKDC score after ACLR based on preoperative and intraoperative factors. The femoral tunnel fixation method was the only significant intraoperative variable. Range of motion and medial collateral ligament integrity were found to be important physical examination parameters. Increased body mass index and prior contralateral surgery were also significantly predictive of outcome.

Two-Year Recall Bias After ACL Reconstruction Is Affected by Clinical Result.

Recall bias is a systematic error caused by inaccuracy in reporting past health status and can be a substantial methodological flaw in the retrospective collection of data. Little is known about recall bias following anterior cruciate ligament reconstruction (ACLR). The purpose of this study was to evaluate patients' recall bias regarding preinjury knee function at 2 years after ACLR. METHODS: Patients undergoing ACLR were enrolled in an institutional ACL registry. Preoperatively and at 2 years postoperatively, patients quantified their preinjury knee function on a scale of 0 to 10 (10 = best). Recall bias was quantified as the difference in the reported preinjury function between the 2 time points. The clinical result of ACLR was evaluated according to the International Knee Documentation Committee (IKDC) Subjective Knee Evaluation score. Patients meeting the minimal clinically important difference (MCID) in the IKDC score were considered to have had a good outcome, while patients who did not reach the MCID were considered to have had failure of treatment. Recall bias was compared between the 2 groups. RESULTS: Of 2,109 patients enrolled in the registry, 1,219 were included in the study. Patients with a good outcome remembered their preinjury knee function on a 0-to-10 scale to be better than what they reported at baseline, by a mean difference of 0.40 points (95% confidence interval [CI], 0.22 to 0.58 points). The recall bias was stronger for patients with a poor outcome, who remembered their knee function to be worse than reported at baseline, by a mean difference of -0.81 (95% CI, -1.4 to -0.26). The mean difference in recall between the 2 groups was -1.21 (95% CI, -1.74 to -0.67) (p < 0.0001). CONCLUSIONS: The recall bias of preinjury knee function following ACLR was small and not clinically meaningful for the majority of patients. However, patients with a poor outcome had a clinically relevant and significant recall bias. CLINICAL RELEVANCE: Our findings suggest that patients with a poor outcome have a substantial recall bias. This has clinical relevance when considering treatment effects of revision surgery, whereby the clinical benefit of the treatment might be affected by recall bias.