How Does the Presence of Unstable Chondral Lesions Affect Patient Outcomes After Partial Meniscectomy? The ChAMP Randomized Controlled Trial

Approximately One Half of Patients Greater Than 40 Years Old Achieve Patient Acceptable Symptomatic State 6 Months After Arthroscopic Partial Meniscectomy

Purpose

The purposes of this study were to 1) calculate the minimal clinically important difference (MCID) in a population of patients undergoing arthroscopic partial meniscectomy (APM) based on Knee Injury and Osteoarthritis Outcomes Scores (KOOS), 2) quantify the difference between the proportion of patients reaching MCID based on KOOS versus the proportion who considered surgery to be successful based on a "yes" answer to a patient acceptable symptom state (PASS) question, and 3) calculate the percentage of patients experiencing treatment failure (TF).

Methods

A large, single-institution clinical database was queried for patients undergoing isolated APM (>40 years of age). Data were collected at regular time intervals, including KOOS and PASS outcome measures. Calculation of MCID using a distribution-based model was performed using preoperative KOOS scores as baseline. Comparison of the proportion of patients surpassing MCID was made to the proportion of patients answering "yes" to a tiered PASS question at 6 months after APM. Proportion of patients experiencing TF was calculated using patients who responded "no" to a PASS question and "yes" to a TF question.

Results

Three-hundred and fourteen of 969 patients met inclusion criteria. At 6 months following APM, the percentage of patients meeting or exceeding the MCID for each respective KOOS subscore ranged from 64 to 72% compared to 48% who achieved a PASS (P < .0001 for each subscore). Fourteen percent of patients experienced TF.

Conclusions

Six months after APM, approximately one half of the patients achieved a PASS and 15% experienced TF. The difference between achieving MCID based on each of the KOOS subscores and achieving success via PASS ranged from 16% to 24%. Thirty-eight percent of patients undergoing APM did not fit neatly into overt success or failure categorization.

Level of Evidence

Level III, retrospective cohort study.

Arthroscopic repair of degenerative medial meniscus tears in patients aged over 45 years resulted in favorable clinical outcomes and low clinical failure rates at a minimum 2-year follow-up

PURPOSE

This study aimed to investigate clinical and radiological results of arthroscopic repair for isolated medial degenerative meniscus tears (DMTs) in patients over 45 years old at a minimum 2-year follow-up.

METHODS

From 2013 to 2017, patients aged over 45 years with isolated medial DMT refractory to conservative management or with true mechanical symptoms who had undergone arthroscopic repair were retrospectively reviewed. Arthroscopic meniscus repair was performed using all-inside or all-inside and inside-out technique in combination with bone marrow venting procedure. Tear patterns were classified according to arthroscopic findings. Magnetic resonance imaging (MRI) and outcome evaluations, including Lysholm score, Tegner activity score, and International Knee Documentation Committee (IKDC) score, were evaluated preoperatively and at the final follow-up. International Cartilage Repair Society grades of the medial compartments and MRI signal at tear sites were assessed preoperatively and at the final follow-up. A grade 0 to 2 signal at the repair site suggested a healed meniscus, whereas a grade 3 signal suggested an unhealed meniscus. Clinical failure was determined according to Barrett criteria.

RESULTS

Twenty-seven patients (mean age, 57.7 ± 7.4 years) were enrolled. The mean follow-up was 52.0 ± 15.6 months. Among tear patterns, 48% were complex tears, 30% were horizontal tears, and 22% were other patterns. The mean Lysholm score and IKDC score significantly improved from 53 ± 25 to 89 ± 15 (p < 0.001) and 34 ± 24 to 72 ± 15 (p < 0.001) at the final follow-up, respectively. The median Tegner activity score significantly improved from 1 (range 1-4) to 4 (range 2-7, p < 0.001). Three (11%) patients were considered clinical failures, and five patients (19%) had cartilage lesion progression. At the final follow-up, MRI showed grade 0 in one (4%) patient, grade 1 in nine (33%) patients, grade 2 in six (22%) patients, and grade 3 in eleven (41%) patients.

CONCLUSION

Arthroscopic repair of isolated medial DMT refractory to conservative management or with true mechanical symptoms in patients aged over 45 years had good to excellent clinical outcomes with low clinical failure rates, despite unhealed menisci being observed on MRI in 41% of patients at a mean 4.3-year follow-up. Arthroscopic repair could be a treatment option for these patients.

LEVEL OF EVIDENCE

IV.

Better Outcomes but No Difference in Joint Space Narrowing at Five Years Among Patients Without Unstable Chondral Lesions Versus Those With Unstable Chondral Lesions (Left In Situ) at the Time of Arthroscopic Partial Meniscectomy

PURPOSE

To compare 5-year outcomes among patients with and without unstable chondral lesions undergoing arthroscopic partial meniscectomy (APM).

METHODS

Using data from the Chondral Lesions And Meniscal Procedures (ChAMP) Trial, we compared outcomes for patients with unstable chondral lesions found at the time of APM and left in situ (CL-noDeb, N = 71) versus patients without unstable chondral lesions (NoCL, N = 47) at 5 years after APM. Outcomes included the Western Ontario and McMaster Universities Arthritis Index (WOMAC), Knee Injury and Osteoarthritis Outcome Score (KOOS), visual analog pain scale, Short-form Health Survey (SF-36), physical knee measurements, progressive joint space narrowing on radiographs, and the rate of additional knee surgery. Multivariate linear regression was used to obtain mean differences (MDs) with corresponding 95% confidence intervals (CIs) adjusted for age, body mass index, and preoperative score (for postoperative scores).

RESULTS

Compared with CL-noDeb, NoCL subjects had significantly greater improvement at 5 years in the KOOS score for function in sport and recreation (MD = 9.9 [95% CI, 0.7-19.1]), SF-36 pain (MD = 13.9 [95% CI, 5.5-22.3]), knee extension (MD = 0.8 [95% CI, 0.1-1.5]), and decreased quadriceps circumference at the mid-portion of the patella (MD = -1.5 [95% CI, -2.7 to -0.3). A greater proportion of patients in the NoCL group achieved the MCID for all outcome scores except for the WOMAC pain score (89% CL-NoDeb vs 87% NoCL) and SF-36 general (29% CL-NoDeb vs 23% NoCL). There were no significant group differences in measures of progressive radiographic joint space narrowing in any compartments of the operative knee and no significant difference in the rate of additional knee surgery within 5 years of the initial APM.

CONCLUSIONS

Patients undergoing APM without unstable chondral lesions had statistically significantly better outcomes than patients with unstable chondral lesions at 5 years after surgery; however, there were no group differences in progressive radiographic joint space narrowing.

LEVEL OF EVIDENCE

Level II, prospective comparative study.

Observation Versus Debridement of Unstable Chondral Lesions During Partial Meniscectomy: Analysis of Patient Outcomes and Degenerative Joint Disease at 5 Years in the Chondral Lesions And Meniscus Procedures (ChAMP) Randomized Controlled Trial

BACKGROUND

The purpose of this study was to examine the effect of debridement (CL-Deb) versus observation (CL-noDeb) of unstable chondral lesions on knee pain 5 years after arthroscopic partial meniscectomy (APM) in patients enrolled in the Chondral Lesions And Meniscus Procedures (ChAMP) Trial. Secondarily, other knee symptoms, function, general health, and the rate of additional surgery on the affected knee were examined.

METHODS

Patients aged ≥30 years who had an unstable Outerbridge grade-II, III, or IV chondral lesion when undergoing APM were randomly allocated to the CL-Deb (n = 98) or CL-noDeb (n = 92) group; ∼80% in each group completed a 5-year follow-up. Outcomes were measured preoperatively and at 5 years postoperatively, and included the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), Knee injury and Osteoarthritis Outcome Score (KOOS), visual analog scale (VAS) for pain, Short Form-36 (SF-36), physical knee measurements, knee radiographs, and rate of additional knee surgery at 5 years. The primary outcome was the 5-year WOMAC pain score. Group comparisons were made using the t test for continuous outcomes and the Fisher exact test for categorical outcomes.

RESULTS

There were no significant differences between the groups with respect to the primary outcome, the WOMAC pain score (CL-Deb: 86.0 [95% confidence interval (CI): 82.9 to 89.1]) versus CL-noDeb: 88.3 [95% CI: 85.5 to 91.1]; p = 0.27), or secondary outcomes at 5 years. There were also no differences in radiographic measurements of joint-space narrowing in any compartment (medial or lateral tibiofemoral or medial, central, or lateral patellofemoral) as well as no difference in the rate of additional knee surgery within 5 years after APM between the CL-Deb and CL-noDeb groups.

CONCLUSIONS

Outcomes for the CL-Deb and CL-noDeb groups did not differ at 5 years postoperatively, suggesting that there is no long-term benefit of arthroscopic debridement of chondral lesions encountered during APM.

LEVEL OF EVIDENCE

Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence.

Degenerative Joint Disease After Meniscectomy

The meniscus has an important role in stabilizing the knee joint and protecting the articular cartilage from shear forces. Meniscus tears are common injuries and can disrupt these protective properties, leading to an increased risk of articular cartilage damage and eventual osteoarthritis. Certain tear patterns are often treated with arthroscopic partial meniscectomy, which can effectively relieve symptoms. However, removal of meniscal tissue can also diminish the ability of the meniscus to dissipate hoop stresses, resulting in altered biomechanics of the knee joint including increased contact pressures. This makes meniscal repair an important treatment consideration whenever possible. Understanding the incidence and mechanism of osteoarthritis development after arthroscopic partial meniscectomy as it relates to different tear morphologies and other treatment alternatives (ie, meniscus repair) is important to appropriately treat meniscus tears.

Arthroscopic debridement for focal articular cartilage lesions of the knee: A systematic review

BACKGROUND AND PURPOSE OF THE STUDY

Arthroscopic debridement, the most commonly applied surgical technique for focal cartilage lesions in the knee, is not included in most treatment algorithms because of discouraging results in the management of osteoarthritis of the knee. The present systematic review evaluates the outcome of arthroscopic cartilage debridement as the primary treatment of focal knee chondral lesions in adults, and defines its indications and role as the primary treatment of focal knee chondral lesions.

METHODS

Two independent investigators searched PubMed, Cochrane CENTRAL, and Virtual Health Library databases using the terms "knee", "cartilage", "chondral", "lesions", "injury", "damage", "debridement", "chondroplasty", "chondrectomy", alone and in combination. Clinical studies evaluating the effect of mechanical cartilage debridement in adults with symptomatic focal cartilage lesions in the knee joint regardless of the defect size and depth were included. We excluded studies if patients had a concomitant ligament or meniscus injury, and/or had additional debridement with monopolar radiofrequency energy.

MAIN FINDINGS

Available studies suggest good to excellent short and medium-term functional outcomes (KOOS, LKSS, Tegner scale) for focal cartilage lesions treated with debridement regardless of the defect size and depth. Data are lacking comparing cartilage debridement versus other cartilage repair techniques.

CONCLUSIONS

Arthroscopic debridement of focal articular cartilage lesions of the knee is associated with good to excellent short and medium-term postoperative outcomes, especially in terms of functional improvement. Arthroscopic debridement may be considered in the primary treatment of focal cartilage injuries regardless of the defect size and depth. However, available studies are limited and the level of evidence is low.

Prognostic Factors of Mid- to Long-term Clinical Outcomes after Arthroscopic Partial Meniscectomy for Medial Meniscal Tears

Backgroud

Arthroscopic partial meniscectomy (APM) continues to be the popular treatment for meniscal tears, but recent randomized controlled trials have questioned its efficacy. To provide more evidence-based criteria for patient selection, we undertook this study to identify prognostic factors associated with clinical failure after APM for medial meniscus tears.

Methods

Medical records of 160 patients followed up for at least 5 years after APM for medial meniscal tears were retrospectively reviewed. Demographic data (age, sex, and body mass index), radiographic variables (Kellgren-Lawrence [K-L] grade and hip-knee-ankle [HKA] angle), and clinical scores (International Knee Documentation Committee score, Tegner activity scale score, Lysholm score, and Knee injury and Osteoarthritis Outcome Score) were recorded. Clinical failure was defined as the need for an additional surgical procedure (arthroscopy, osteotomy, or arthroplasty) or the presence of intolerable pain. Survivorship analysis with clinical failure as an end point was performed using Kaplan-Meier survival curves. Factors related to clinical failure were analyzed using a Cox proportional hazard model. Cutoff values were determined using areas under receiver operating characteristic (ROC) curves. Radiographic progression of osteoarthritis was analyzed using the chi-square test, and serial changes of clinical scores were analyzed using a linear mixed model.

Results

Clinical success rates were 95.7% at 5 years, 75.6% at 10 years, and 46.3% at 15 years. Age, HKA angle, and K-L grade (p = 0.01, p = 0.02, and p = 0.04, respectively) were found to be significant risk factors of clinical failure. Cutoff values at 10 years postoperatively as determined by ROC analysis were 50 years for age (sensitivity = 0.778, 1−specificity = 0.589), grade 2 for K-L grade (sensitivity = 0.778, 1−specificity = 0.109), and 5.5° for HKA angle (sensitivity = 0.667, 1−specificity = 0.258). In patients who had clinical success until 10 years after APM, radiological osteoarthritis progressed gradually. However, the clinical scores of patients who achieved clinical success did not decrease significantly over the 10-year follow-up.

Conclusions

The poor prognostic factors found to be related to clinical failure after APM for a medial meniscal tear were patient age (≥ 50 years), preoperative K-L grade (≥ grade 2), and preoperative HKA angle (≥ varus 5.5°).

Predictors of Successful Treatment 1 Year After Arthroscopic Partial Meniscectomy: Data from the OME Cohort

Arthroscopic partial meniscectomy (APM) is one of the most common orthopaedic procedures. Understanding factors that predict better patient-reported outcomes is important for guiding patient and clinician decision-making. The purpose of this study was to evaluate predictors of pain and function after APM in a large, multisite, academic health system cohort.

METHODS

We prospectively enrolled 665 patients who were ≥40 years of age and who had APM without any concomitant ligament or cartilage-resurfacing procedures. There were 486 subjects (73%) who completed baseline and follow-up questionnaires including demographic variables (age, sex, body mass index [BMI], education level), surgical findings (meniscal tear type, articular cartilage grade), and patient-reported outcomes (Knee injury and Osteoarthritis Outcome Score [KOOS] Pain, Physical Function Short Form [PS], and knee-related Quality of Life [QOL]; and Veterans RAND 12-Item [VR-12] Mental Component Score [MCS] and Physical Component Score [PCS]). We constructed multivariable statistical models to assess predictors of improvement in patient-reported outcomes, as well as a model to assess predictors of a successful improvement of at least 10 points in either KOOS Pain or KOOS-PS.

RESULTS

The mean age was 55 years, 46% of patients were female, and the mean BMI was 30 kg/m2. There were clinically important and significant improvements (p < 0.001) in all patient-reported outcomes from baseline to the 1-year follow-up. The following factors predicted less improvement in at least 1 patient-reported outcome: higher baseline score, higher BMI, older age, less education, current smoking, lower VR-12 MCS, prior ipsilateral surgical procedure, bipolar medial compartment cartilage lesions, and a lateral meniscal tear. Eighty-three percent of subjects had a successful improvement of 10 points in either KOOS Pain or KOOS-PS. The odds of successful improvement were lower in patients with a medial meniscal root tear, a lateral meniscal tear, or higher baseline KOOS Pain score.

CONCLUSIONS

Eighty-three percent of patients improved by at least 10 points in pain and function after APM. Patients with a medial meniscal root tear or a lateral meniscal tear had decreased odds of a clinically important improvement in pain or function after APM. Increased BMI, smoking, and worse VR-12 MCS are potentially modifiable risk factors that predict less improvement after APM and warrant further study.

LEVEL OF EVIDENCE

Prognostic Level I. See Instructions for Authors for a complete description of levels of evidence.

Comparison of Clinical and Semiquantitative Cartilage Grading Systems in Predicting Outcomes After Arthroscopic Partial Meniscectomy

OBJECTIVE. Cartilage loss on preoperative knee MRI is a predictor of poor outcomes after arthroscopic partial meniscectomy. The purpose of this study was to compare the ability to predict outcomes after arthroscopic partial meniscectomy with a clinically used modified Outerbridge system versus a semiquantitative MRI Osteoarthritis Knee Score system for grading cartilage loss. MATERIALS AND METHODS. Patients who underwent preoperative knee MRI within 6 months of arthroscopic partial meniscectomy and who had outcomes available from the time of surgery and 1 year later were eligible for inclusion. Cases were evaluated by two radiologists and one radiology fellow with the use of both grading systems. The accuracy of each system in discriminating between surgical success and failure was estimated using the ROC curve (AUC) with 95% CIs. A Wald test was used to assess noninferiority of the clinical grading system. Interreader agreement regarding the accuracy of the grading systems in predicting outcomes was also compared. RESULTS. A total of 78 patients (38 women and 40 men; mean age, 56.6 years) were included in the study. A prediction model using clinical grading (AUC = 0.695; 95% CI, 0.566-0.824) was noninferior (p = 0.047) to a model using MRI Osteoarthritis Knee Score grading (AUC = 0.683; 95% CI, 0.539-0.827). Both MRI prediction models performed better than a model using demographic characteristics only (AUC = 0.667; 95% CI, 0.522-0.812). Inter-reader agreement with clinical grading (80.8%) was higher than that with MRI Osteoarthritis Knee Score grading (65.0%; p = 0.012). CONCLUSION. A clinically used system to grade cartilage loss on MRI is as effective as a semiquantitative system for predicting outcomes after arthroscopic partial meniscectomy, while also offering improved interreader agreement.

Stability Enhanced Variable Selection for a Semiparametric Model with Flexible Missingness Mechanism and Its Application to the ChAMP Study

This paper is motivated by the analytical challenges we encounter when analyzing the ChAMP (Chondral Lesions And Meniscus Procedures) study, a randomized controlled trial to compare debridement to observation of chondral lesions in arthroscopic knee surgery. The main outcome, WOMAC (Western Ontario and McMaster Universities Osteoarthritis Index) pain score, is derived from the patient's responses to the questionnaire collected in the study. The major goal is to identify potentially important variables that contribute to this outcome. In this paper, the model of interest is a semiparametric model for the pain score. To address the missing data issue, we adopt a flexible missingness mechanism which is much more versatile in practice than a single parametric model. Then we propose a pairwise conditional likelihood approach to estimate the unknown parameter in the semiparametric model without the need of modeling its nonparametric counterpart nor the missingness mechanism. For variable selection we apply a regularization approach with a variety of stability enhanced tuning parameter selection methods. We conduct comprehensive simulation studies to evaluate the performance of the proposed method. We also apply the proposed method to the ChAMP study to demonstrate its usefulness.

Estimation of data adaptive minimal clinically important difference with a nonconvex optimization procedure

Understanding the limitation of solely relying on statistical significance, researchers have proposed methods to draw biomedical conclusions based on clinical significance. The minimal clinically important significance is one of the most fundamental concepts to study clinical significance. Based on an anchor question usually available in the patients' reported outcome, Hedayat et al. presented a method to estimate minimal clinically important significance using the classification technique. However, their method implicitly requires that the binary outcome of the anchor question is equally likely, i.e. the balanced outcome assumption. This assumption cannot be guaranteed a priori when one designs the study; hence, it cannot be satisfied in general. In this paper, we propose a data adaptive method, which can overcome this limitation. Compared to Hedayat et al., our method uses a faster gradient based algorithm and adopts a more flexible structure of the minimal clinically important significance at the individual level. We conduct comprehensive simulation studies and apply our method to the chondral lesions and meniscus procedure study to demonstrate its usefulness and also its outperformance.

Factors Associated With Clinically Significant Patient-Reported Outcomes After Primary Arthroscopic Partial Meniscectomy

PURPOSE

The purpose of this study was to establish minimal clinically important difference (MCID), substantial clinical benefit (SCB), and patient-acceptable symptom state (PASS) after meniscectomy and factors associated with achieving these goals.

METHODS

A prospectively maintained institutional registry was retrospectively reviewed for all patients undergoing isolated arthroscopic partial meniscectomy from 2014 through 2017. MCID, SCB, and PASS were calculated for the International Knee Documentation Committee (IKDC) and Knee Injury and Osteoarthritis Outcome Score (KOOS) subscores by using the anchor-based methodology and nonparametric receiver operating characteristic curves. Subscores included joint replacement (JR), physical function (PF), symptoms (Sx), pain, activities of daily living (ADL), sport, and quality of life (QOL).

RESULTS

A total of 269 patients were analyzed in the study, which reported outcomes between 6 and 7 months after surgery. The average age of our population was 48.9 ± 12.4 years. Twenty patients reported no change, 53 reported minimal improvement, and 137 reported substantial change after surgery; whereas 59 patients reported worse outcomes. One hundred seventy-seven patients were satisfied and 92 were not satisfied with the outcome of surgery. Established MCID/SCB/PASS for the IKDC, KOOS JR, KOOS PF, KOOS Sx, KOOS Pain, KOOS ADL, and KOOS QOL were 10.6/25.3/57.9, 10.7/13.2/68.3, -8.2/-11.3/26.2, 8.9/7.1/71.4, 9.7/22.2/76.4, 11.0/16.9/89.0, 12.5/27.5/55.6, and 15.6/34.4/46.9, respectively. Higher preoperative scores were associated with reduced odds of achieving MCID and SCB but greater odds of achieving PASS for nearly all scores (P < .05). Workers' compensation status, degenerative tears, medial-sided tears, and root tears were associated with reduced odds of achieving 2 or more clinically meaningful outcomes in 2 or more scores (P < .05).

CONCLUSIONS

Clinically meaningful outcomes were established by patient self-assessment. Variables associated with achieving these outcomes include preoperative score (positively correlated with MCID/SCB, negatively correlated with PASS); workers' compensation; degenerative, medial-sided tears; and root tears (remaining negatively correlated with MCID/SCB/PASS). These variables should be accordingly measured for confounding in future outcome reporting.

Interval Estimation for Minimal Clinically Important Difference and its Classification Error via a Bootstrap Scheme

With the improved knowledge on clinical relevance and more convenient access to the patient-reported outcome data, clinical researchers prefer to adopt minimal clinically important difference (MCID) rather than statistical significance as a testing standard to examine the effectiveness of certain intervention or treatment in clinical trials. A practical method to determining the MCID is based on the diagnostic measurement. By using this approach, the MCID can be formulated as the solution of a large margin classification problem. However, this method only produces the point estimation, hence lacks of ways to evaluate its performance. In this paper we introduce an m-out-of-n bootstrap approach which provides the interval estimations for MCID and its classification error, an associated accuracy measure for performance assessment. A variety of extensive simulation studies are implemented to show the advantages of our proposed method. Analysis of the chondral lesions and meniscus procedures (ChAMP) trial is our motivating example and is used to illustrate our method.

Association Between Bone Marrow Lesions, Chondral Lesions, and Pain in Patients Without Radiographic Evidence of Degenerative Joint Disease Who Underwent Arthroscopic Partial Meniscectomy

Background

Bone marrow lesions (BMLs) have been found on magnetic resonance imaging in patients with meniscal tears.

Purpose

We sought to determine the prevalence and location of BMLs, the association between BMLs and chondral lesions, and the association between BMLs and pain in patients without radiographic evidence of degenerative joint disease who underwent arthroscopic partial meniscectomy (APM).

Study Design

Cohort study; Level of evidence, 2.

Methods

We performed a secondary analysis of the Chondral Lesions And Meniscus Procedures (ChAMP) randomized controlled trial. BMLs were assessed on preoperative magnetic resonance imaging, and chondral lesions were documented at the time of surgery. Pain was assessed preoperatively and at 1 year after APM using the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and the Knee injury and Osteoarthritis Outcome Score (KOOS). The chi-square test was used to examine the association between BMLs and chondral lesions, and the F test was used to examine the association between BMLs and pain.

Results

Of 241 patients, 58.9% had ≥1 BMLs, and most were located on the medial tibial plateau (MTP; 74.6%) and/or medial femoral condyle (MFC; 28.9%). Most MTP BMLs were submeniscal (56%), and most MFC BMLs extended beyond the meniscus (73%). There were more MFC chondral lesions for patients with any MFC BMLs (P = .01) and submeniscal MFC BMLs (P = .02) versus those without BMLs, and there was no association between BMLs and chondral lesions on the MTP. There was also no association between BMLs and preoperative or postoperative pain scores.

Conclusion

In patients without radiographic evidence of degenerative joint disease who underwent APM, BMLs were found in 58.9% of knees and were primarily located in the medial compartment. There was a borderline statistically significant association between BMLs and chondral lesions for the MFC; however, BMLs were not associated with pain scores preoperatively or at 1 year after surgery.