Evaluation of Three-Dimensional Bioprinted Human Cartilage Powder Combined with Micronized Subcutaneous Adipose Tissues for the Repair of Osteochondral Defects in Beagle Dogs.

Cartilage lesions are difficult to repair due to low vascular distribution and may progress into osteoarthritis. Despite numerous attempts in the past, there is no proven method to regenerate hyaline cartilage. The purpose of this study was to investigate the ability to use a 3D printed biomatrix to repair a critical size femoral chondral defect using a canine weight-bearing model. The biomatrix was comprised of human costal-derived cartilage powder, micronized adipose tissue, and fibrin glue. Bilateral femoral condyle defects were treated on 12 mature beagles staged 12 weeks apart. Four groups, one control and three experimental, were used. Animals were euthanized at 32 weeks to collect samples. Significant differences between control and experimental groups were found in both regeneration pattern and tissue composition. In results, we observed that the experimental group with the treatment with cartilage powder and adipose tissue alleviated the inflammatory response. Moreover, it was found that the MOCART score was higher, and cartilage repair was more organized than in the other groups, suggesting that a combination of cartilage powder and adipose tissue has the potential to repair cartilage with a similarity to normal cartilage. Microscopically, there was a well-defined cartilage-like structure in which the mid junction below the surface layer was surrounded by a matrix composed of collagen type I, II, and proteoglycans. MRI examination revealed significant reduction of the inflammation level and progression of a cartilage-like growth in the experimental group. This canine study suggests a promising new surgical treatment for cartilage lesions.

Satisfactory Outcomes in Patients Operated With Primary Total Hip Arthroplasty for Perthes-like Deformities: Results From a Surgical Technique Utilizing a Conical Stem, an Elevated Hip Center, and No Shortening Femoral Osteotomy.

BACKGROUND: Total hip arthroplasty (THA) performed on patients with Perthes-like deformities are technically challenging because of the patient's abnormal hip anatomy. Patients with Perthes-like deformities are at a higher risk of revision, aseptic loosening, nerve injury, and intraoperative fracture after THA, especially if shortening osteotomies are performed. This analysis sought to examine the clinical and radiographic outcomes of a patient cohort with Perthes-like deformities receiving THA with a conical stem, an elevated hip center, and no shortening femoral osteotomy. METHODS: Twenty-six patients (27 hips) received THA with MODULUS femoral stems, ceramic or metal femoral heads, and highly cross-linked polyethylene liners between April 2011 and March 2016. All patients were treated at a single center by 4 participating surgeons. Patients completed 2 questionnaires preoperatively and at the final follow-up visit (between 1 and 5 years postoperatively): Harris Hip Score and Japanese Orthopaedic Association Hip-Disease Evaluation Questionnaire. Differences in patient-reported outcome measures (PROM) scores were measured by paired t-tests. Preoperative and postoperative anteroposterior radiographs were analyzed to monitor patient outcomes. RESULTS: Significant clinical improvements were observed in all individual subcategories of the Harris Hip Score and of the Japanese Orthopaedic Association Hip-Disease Evaluation Questionnaire; the largest magnitude improvements were observed in the subcategory of pain relief for both questionnaires. No complications, including intraoperative and postoperative femoral fractures, nerve palsy, dislocations, or deep venous thrombosis, were observed. CONCLUSION: This study found that patients treated with an elevated hip center and low stem-positioning technique using a conical, modular implant system had good clinical outcomes and did not suffer complications at the mean follow-up from surgery of 2.8 years (range: 1-5 years).

Elevated Body Mass Index Is a Risk Factor for Failure to Achieve the Knee Disability and Osteoarthritis Outcome Score-Physical Function Short Form Minimal Clinically Important Difference Following Total Knee Arthroplasty.

BACKGROUND: The aims of this study are (1) to assess the association between body mass index (BMI) and failure to achieve the 1-year Knee Disability and Osteoarthritis Outcome Score-Physical Function Short Form (KOOS-PS) minimal clinically important difference (MCID) for total knee arthroplasty (TKA) patients and (2) to determine if there is a BMI threshold beyond which the risk of failing to achieve the MCID is significantly increased. METHODS: A regional arthroplasty registry was queried for TKA patients from 2016 to 2019 with completion of preoperative and 1-year postoperative KOOS-PS. The MCID threshold was derived using a distribution-based approach. Demographic and patient-reported outcome measure variables were collected. BMI was analyzed continuously and categorically using cutoffs defined by the Centers for Disease Control and Prevention. The association between failure to achieve 1-year MCID and BMI was analyzed using multiple logistic regression. A BMI threshold was determined using the Youden index and receiver operating characteristic curve. RESULTS: In total, 1059 TKAs were analyzed. BMI assessed continuously was significantly associated with failure to achieve the KOOS-PS MCID (odds ratio 1.03, 95% confidence interval 1.00-1.05, P = .025). Analysis of BMI categorically revealed that "overweight" (25-30 kg/m2), "obese class I" (30-35 kg/m2), "obese class II" (35-40 kg/m2), and "obese class III" (>40 kg/m2) patients faced 77%, 76%, 83%, and 106% greater risk, respectively, of failing to achieve the KOOS-PS MCID compared to "normal BMI" (<25 kg/m2) patients. CONCLUSION: Elevated BMI was associated with an increased risk of failure to achieve the 1-year KOOS-PS MCID following TKA.

Class III Obesity Increases Risk of Failure to Achieve the 1-Year Hip Disability and Osteoarthritis Outcome Score-Physical Function Short Form Minimal Clinically Important Difference Following Total Hip Arthroplasty.

BACKGROUND: The relationship between obesity and failure to achieve a minimal clinically important difference (MCID) following total hip arthroplasty (THA) has not been well defined. The aims of this study are to determine whether increasing body mass index (BMI) is associated with failure to achieve the 1-year Hip Disability and Osteoarthritis Outcome Score-Physical Function Short Form (HOOS-PS) MCID and to determine a threshold BMI beyond which this risk is significantly increased. METHODS: A multi-institutional arthroplasty registry was queried for THA patients from 2016 to 2018 with completion of preoperative and 1-year postoperative HOOS-PS. A previously defined anchor-based MCID threshold of 23 was used. Variables collected included demographics and patient-reported outcome measures. BMI was analyzed continuously and categorically. The association was analyzed via logistic regression. A BMI threshold was determined using the Youden index and receiver operating characteristic curve. RESULTS: A total of 1256 THAs were included. The average HOOS-PS improvement was 27.6 ± 18 points. The area under the receiver operating characteristic curve for BMI and risk of failure to achieve HOOS-PS MCID was 0.54 (95% confidence interval [CI], 0.50-0.57). Increasing BMI assessed continuously was a significant risk factor (odds ratio [OR], 1.03; 95% CI, 1.01-1.05; P value = .010). When BMI was analyzed categorically, this association was only observed for obese class III patients (>40 kg/m2) (OR, 2.5; 95% CI, 1.21-5.3; P value = .010). CONCLUSION: This study found an association between increasing BMI and failure to achieve the 1-year HOOS-PS MCID. Obese class III patients (>40 kg/m2) face a near 3-fold increased risk of suffering this adverse outcome.

Do Knee Osteoarthritis Patterns Affect Patient-Reported Outcomes in Total Knee Arthroplasty? Results From an International Multicenter Prospective Study With 3-Year Follow-Up.

BACKGROUND: The aim of this multicenter study is to answer (1) Does patellofemoral osteoarthritis (OA) affect preoperative Knee Injury and Osteoarthritis Outcome Score (KOOS) scores in total knee arthroplasty (TKA)? and (2) Do different OA patterns affect preoperative and postoperative KOOS scores in TKA? METHODS: This international, multicenter prospective study examined 384 TKA patients. Compartmental OA was divided into (1) medial, (2) medial + patellofemoral, (3) lateral, (4) lateral + patellofemoral, (5) medial + lateral (bicompartmental), and (6) medial + lateral + patellofemoral (tricompartmental), based on preoperative anterior-posterior and lateral ± skyline radiographs with Kellgren-Lawrence grade III-IV and joint space width <2.5 mm. KOOS was collected preoperatively, 1 year postoperatively, and 3 years postoperatively. Higher KOOS score represented better clinical state, for example, higher KOOS Pain score indicated less pain. RESULTS: Patellofemoral OA had no effect on preoperative KOOS scores (P > .15). Compared to medial ± patellofemoral OA patients, bicompartmental/tricompartmental OA patients had less preoperative pain (KOOS Pain 7.4, P = .03) and higher daily function (KOOS-ADL [Activities of Daily Living] 7.1, P = .05), and higher 1-year postoperative daily function (KOOS-ADL 9.2, P = .03) and sports activity (KOOS Sports & Recreation Function 15.0, P = .04), while lateral ± patellofemoral OA patients had more symptoms (KOOS-Symptoms 7.0, P < .01), more pain (KOOS-Pain 7.5, P = .01), lower daily function (KOOS-ADL 9.3, P < .01), and lower quality of life (KOOS-QOL 9.0, P = .04), at 3 years postoperatively. CONCLUSION: Patellofemoral OA does not affect medial ± lateral OA patients' preoperative KOOS scores, challenging the importance of patellofemoral OA in TKA. Lateral ± patellofemoral OA patients have lower postoperative KOOS scores than medial/more progressed compartmental OA patients, indicating that patients with less common OA patterns present with unique surgical challenges. Further development of indications for and correct timing of TKA surgery in different patient subgroups is needed.

Low Body Mass Index Is a Predictor for Mortality and Increased Length of Stay Following Total Joint Arthroplasty.

BACKGROUND: Malnutrition is a devastating condition which disproportionally affects the elderly population. Malnutrition furthers the pre-existing elevated risk for osteoarthritis in this population, thus exacerbating joint damage in patients and furthering the need for total joint arthroplasty (TJA). A marker for malnutrition is a low body mass index (BMI). The purpose of this study is to investigate whether low BMI status increased the risk for 2-year mortality or reoperation, 90-day readmission, or extended length of stay (LOS) following TJA. METHODS: A retrospective study was performed using the Partners Arthroplasty Registry which contains data from 2016 to 2019. The registry was queried for primary total hip and primary total knee arthroplasty (TKA) patients that had a minimum of 2-years follow-up data. Demographic, surgical, and clinical outcome variables were obtained from these patients. The association between underweight BMI and objective outcomes of reoperation, 90-day readmission, mortality, and LOS was evaluated by univariate analysis followed by multiple logistic and linear regression analyses. RESULTS: The final cohort used for analysis consisted of 4802 TJA cases. After accounting for potential confounders, underweight BMI was found to be independently associated with increased risk of mortality within 2 years following TJA (odds ratio 8.77) (95% confidence interval 2.14-32.0) and increased LOS of 0.44 days (95% confidence interval 0.02-0.86). CONCLUSION: Our findings demonstrate that TJA patients with an underweight BMI experience an 8 times increased risk of 2-year mortality and an increased LOS of 0.44 days. Orthopedic surgeons should consider nutritional consultation and medical optimization in these high-risk patients prior to surgery.

Obesity Increases Risk of Failure to Achieve the 1-Year PROMIS PF-10a Minimal Clinically Important Difference Following Total Joint Arthroplasty.

INTRODUCTION: The aims of this study were to determine if increasing body mass index (BMI) is a risk factor for failure to attain the 1-year Patient Reported Outcomes Measurement Information System Physical Function (PROMIS PF-10a) minimal clinically important difference (MCID) following total joint arthroplasty (TJA) and to determine a possible BMI threshold beyond which this risk increases significantly. METHODS: This retrospective study was performed using 3506 TJAs sourced from a regional-based registry. An anchor-based MCID threshold of 7.9 was chosen. PROMIS PF-10a scores were collected at the preoperative and 1-year postoperative timepoints, and the change was used to determine failure to achieve the 1-year MCID. Demographic and surgical variables were also collected. The association between BMI and failure to achieve 1-year PROMIS PF-10 MCID was then evaluated using logistic regression. A BMI threshold was determined using receiver operating characteristic (ROC) curve analysis. RESULTS: Increasing BMI assessed continuously was a significant risk factor for failure to achieve the MCID (P < .001). "Obese Class I" (30-35 kg/m2), "Obese Class II" (35-40 kg/m2), and "Obese Class III" (>40 kg/m2) subgroups compared to "Normal BMI" (<25 kg/m2) were significantly associated (P < .05) with this adverse outcome as well. CONCLUSION: Our study showed that increasing BMI is a risk factor for failure to achieve the 1-year PROMIS PF-10a MCID following TJA. Among our patients, an increase in 1 kg/m2 increased the risk of failure to achieve the MCID by 2%. With these findings, surgeons will be better equipped to preoperatively advise patients with elevated BMIs considering TJA.

Development and early findings of a semiautomated arthroplasty registry in a multi-institutional healthcare network.

AIMS: The primary aim of this paper was to outline the processes involved in building the Partners Arthroplasty Registry (PAR), established in April 2016 to capture baseline and outcome data for patients undergoing arthroplasty in a regional healthcare system. A secondary aim was to determine the quality of PAR's data. A tertiary aim was to report preliminary findings from the registry and contributions to quality improvement initiatives and research up to March 2019. METHODS: Structured Query Language was used to obtain data relating to patients who underwent total hip or knee arthroplasty (THA and TKA) from the hospital network's electronic medical record (EMR) system to be included in the PAR. Data were stored in a secure database and visualized in dashboards. Quality assurance of PAR data was performed by review of the medical records. Capture rate was determined by comparing two months of PAR data with operating room schedules. Linear and binary logistic regression models were constructed to determine if length of stay (LOS), discharge to a care home, and readmission rates improved between 2016 and 2019. RESULTS: The PAR captured 16,163 THAs and TKAs between April 2016 and March 2019, performed in seven hospitals by 110 surgeons. Manual comparison to operating schedules showed a 100% capture rate. Review of the records was performed for 2,603 random operations; 2,298 (88.3%) had complete and accurate data. The PAR provided the data for three abstracts presented at international conferences and has led to preoperative mental health treatment as a quality improvement initiative in the participating institutions. For primary THA and TKA surgeries, the LOS decreased significantly (p < 0.001) and the rate of home discharge increased significantly (p < 0.001) between 2016 and 2019. Readmission rates did not correlated with the date of surgery (p = 0.953). CONCLUSION: The PAR has high rates of coverage (the number of patients treated within the Partners healthcare network) and data completion and can be used for both research purposes and quality improvement. The same method of creating a registry that was used in the PAR can be applied to hospitals using similar EMR systems. Cite this article: Bone Joint J 2020;102-B(7 Supple B):90-98.

Patient-acceptable symptom state for the Oxford Hip Score and Forgotten Joint Score at 3 months, 1 year, and 2 years following total hip arthroplasty: a registry-based study of 597 cases.

Background and purpose - Patient-acceptable symptom states (PASS) represent the level on a patient-reported outcome measure (PROM) at which patients are satisfied with postoperative outcomes. We defined the PASS for the Oxford Hip Score (OHS) and Forgotten Joint Score (FJS-12) at 3-month, 1-year, and 2-year intervals after primary total hip arthroplasty (THA).Patients and methods - Between July 2018 and April 2019, primary THA patients in an academic medical center's registry completed the OHS, FJS-12, and a satisfaction anchor question at 3-month (n = 230), 1-year (n = 180), or 2-year (n = 187) postoperative intervals. PASS thresholds were derived with receiver operating characteristic analysis using the 80% specificity method. 95% confidence intervals (CI) were calculated using 1,000 non-parametric bootstrap replications.Results - 74%, 85%, and 86% of patients reported having a satisfactory symptom state at 3 months, 1, and 2 years after surgery, respectively. At 3-month, 1-year, and 2-year intervals, PASS thresholds were 34 (CI 31-36), 40 (CI 36-44), and 39 (CI 35-42) points for the OHS and 59 (CI 54-64), 68 (CI 61-75), and 69 (CI 62-75) points for the FJS-12.Interpretation - PASS thresholds varied with time for both the OHS and the FJS-12, with lower 3-month compared with 1-year and 2-year thresholds. These PASS thresholds represent OHS and FJS-12 levels at which the average patient is satisfied with THA outcomes, helping to interpret PROMs and serving as clinically significant benchmarks and patient-centered outcomes for research.

The AAHKS Clinical Research Award: No Evidence for Superior Patient-Reported Outcome Scores After Total Hip Arthroplasty With the Direct Anterior Approach at 1.5 Months Postoperatively, and Through a 5-Year Follow-Up.

BACKGROUND: The direct anterior approach to total hip arthroplasty (THA) may result in superior early postoperative patient-reported outcome measures (PROMs). This study compared PROMs between THA patients treated with the direct anterior or posterolateral approach between 1.5 months and 5 years, using literature-derived patient acceptable symptom state (PASS) and minimal clinically important improvement (MCII) thresholds. METHODS: A propensity score match of 93 direct anterior patients to 93 posterolateral patients from a multicenter US collaboration (6 centers, 398 patients) was performed. The Harris Hip Score (HHS), the Short-Form 36, and a Numerical Rating Scale for Pain were collected preoperatively, postoperatively (mean days: 47), and at 1, 3, and 5 years. The proportion of patients reaching the HHS PASS, Pain MCII, and Function MCII in the direct anterior and posterolateral groups was compared using binary logistic regressions, controlling for age, gender, body mass index, and Charnley score. RESULTS: Direct anterior patients were less likely to reach the HHS PASS at the postoperative visit (P = .015; odds ratio = 0.454), but not at later visits (P > .082). Direct anterior patients had no difference from posterolateral patients in their tendency to reach the Pain MCII postoperatively or at 1 year (P > .090). The direct anterior patients were less likely to reach the Function MCII at the postoperative visit (P = .011; odds ratio = 0.422), but not at 1 year (P = .958). CONCLUSION: No evidence was found of superior early postoperative PROM scores in THA patients treated with the direct anterior approach. No PROM differences were found at or beyond 1 year, indicating that patients reach similar final symptom states, regardless of surgical approach.

Which Preoperative Factors are Associated with Not Attaining Acceptable Levels of Pain and Function After TKA? Findings from an International Multicenter Study.

BACKGROUND: Although TKA is a common and proven reliable procedure for treating end-stage knee osteoarthritis, a minority of patients still do not achieve satisfactory levels of pain relief and functional improvement. Even though several studies have attempted to identify patients at risk of having poor clinical outcomes, few have approached this issue by considering the outcome of the patient-acceptable symptom state (PASS), defined as the value on a patient-reported outcome measure scale above which the patient deems their current symptom state acceptable. QUESTIONS/PURPOSES: (1) What is the proportion of patients who do not attain the PASS in pain and function at 1 year after TKA? (2) Which preoperative patient factors are associated with not achieving the PASS in pain at 1 year after TKA? (3) Which preoperative patient factors are associated with not achieving the PASS in function at 1 year after TKA? METHODS: This retrospective study is a secondary analysis of the 1-year follow-up data from a prospective, international, multicenter study of a single TKA system. Inclusion criteria for that study were patients diagnosed with primary osteoarthritis or post-traumatic arthritis and who were able to return for follow-up for 10 years; exclusion criteria were infection, osteomyelitis, and failure of a previous joint replacement. Between 2011 and 2014, 449 patients underwent TKA at 10 centers in five countries. At 1 year, 13% (58 of 449) were lost to follow-up, 2% could not be analyzed (eight of 449; missing 1-year KOOS), leaving 85% (383 of 449) for analysis here. The primary outcomes were not surpassing evidence-derived PASS thresholds in the Knee Injury and Osteoarthritis Outcome Score (KOOS) Pain and Activities in Daily Living (ADL) sub-scores. Multivariate binary logistic regressions considering preoperative demographic, radiographic, and patient-reported outcome measure data were constructed using a forward stepwise elimination algorithm to reach the simplest best-fit regression models. RESULTS: At 1 year after TKA, 38% of the patients (145 of 383) did not reach the PASS in KOOS Pain, 36% (139 of 383) did not reach the PASS in KOOS ADL, and 29% (110 of 383) did not achieve the PASS in either KOOS Pain or ADL. After controlling for potentially confounding variables such as gender, age, BMI, and comorbidity scores, we found that men (odds ratio 2.09; p = 0.01), and patients with less-than-advanced radiographic osteoarthritis (OR 2.09; p = 0.01) were strongly associated with not achieving the PASS in pain. After controlling for the same potentially confounding variables, we found that patients with less-than-advanced radiographic osteoarthritis (OR 2.09; p = 0.01) were also strongly associated with not achieving the PASS in function. CONCLUSIONS: We found that patients with less severe osteoarthritis were much less likely to attain the PASS in pain and function at 1 year after TKA, and that men were much less likely to achieve the PASS in pain at 1 year after TKA. Based on these findings, surgeons should strongly consider delaying surgery in patients who present with less-than-severe osteoarthritis, with increased caution in men. Surgeons should counsel their patients on their expectations and their chances of achieving meaningful levels of pain and functional improvement. Future regional and national registry studies should assess the true proportion of patients attaining PASS in pain and function after TKA and confirm if the preoperative factors identified in this study remain significant in larger, more diverse patient populations. LEVEL OF EVIDENCE: Level III, therapeutic study.

Changes in Patient Satisfaction Following Total Joint Arthroplasty.

BACKGROUND: The primary aim is to identify the degree to which patient satisfaction with the outcome of total hip arthroplasty (THA) or total knee arthroplasty (TKA) changes between 1 and 3 years from the procedure. The secondary aim is to identify variables associated with satisfaction. METHODS: Data were sourced from 2 prospective international, multicenter studies (919 THA and 450 TKA patients). Satisfaction was assessed by a 10-point numerical rating scale, at 1- and 3-year follow-up. Linear mixed-effects models were used to assess factors associated with satisfaction. RESULTS: For the THA cohort, higher preoperative joint space width (odds ratio [OR] = 0.28; P = .004), pain from other joints (OR = 0.26; P = .033), and lower preoperative health state (OR = -0.02; P < .001) were associated with consistently lower levels of satisfaction. The model also showed that patients with preoperative anxiety/depression improved in satisfaction between 1 and 3 years (OR = -0.26; P = .031). For the TKA cohort, anterior (vs neutral or posterior) tibial component slope (OR = 0.90; P = .008), greater femoral component valgus angle (OR = 0.05; P = .012), less severe osteoarthritis (OR = -0.10; P < .001), and lower preoperative health state (OR = -0.02; P = .003) were associated with lower levels of satisfaction across the study period. In addition, patients with anterior tibial component slope improved in satisfaction level over time (OR = -0.33; P = .022). CONCLUSION: Changes in satisfaction following THA and TKA are rare between 1- and 3-year follow-up. The findings of this study can be used to guide patient counseling preoperatively and to determine intervals of routine follow-up postoperatively.

Regional differences between the US, Scandinavia, and South Korea in patient demographics and patient-reported outcomes for primary total knee arthroplasty.

INTRODUCTION: Differences in total knee arthroplasty (TKA) patient demographics and clinical outcomes may exist between international regions, yet research is limited. The aim of this study was, therefore, to compare TKA patient demographics and patient-reported outcome measure (PROM) scores between the US, Scandinavia, and South Korea. MATERIALS AND METHODS: A total of 398 TKA patients from three regions were assessed: 169 in Scandinavia (3 centers), 129 in the US (3 centers), and 100 patients in South Korea (2 centers). Regional variation in patient demographics was assessed using Kruskal-Wallis H tests. Regional variation in PROM scores from preoperative, 1-, 3- and 5-year visits was assessed using piecewise linear mixed effect models. The PROMs analyzed were a numerical rating scale for satisfaction and the Knee Osteoarthritis Outcome Score. RESULTS: South Korean patients were the oldest (p < 0.001) and had the highest Charnley class (p < 0.001); US patients had the highest BMI (p < 0.001); Scandinavian patients had the lowest preoperative KL grade (p < 0.001). Scandinavian patients were associated with better preoperative and worse postoperative PROM scores. Scandinavian patients were also associated with moderately lower levels of satisfaction. These differences were lessened but remained significant after controlling for relevant demographic and surgical factors. CONCLUSIONS: Regional differences were found in TKA patient demographics and PROMs between the US, Scandinavia, and South Korea. The regional differences in patient demographics support the need for more research and clear guidelines related to TKA appropriateness criteria. The better preoperative and worse postoperative Scandinavian PROM scores may have been related to their less severe KL grade but might also reflect cultural differences in how patients reflect on their health state when answering PROMs. Clinicians should be aware of these international differences in PROM scores when interpreting studies conducted in different international regions. Future studies should investigate TKA variation between more international regions and assess intraregional variation. LEVEL OF EVIDENCE: Level III.

Patient Acceptable Symptom State at 1 and 3 Years After Total Knee Arthroplasty: Thresholds for the Knee Injury and Osteoarthritis Outcome Score (KOOS).

BACKGROUND: To facilitate the interpretation of numerical patient-reported outcome measure (PROM) scales, concepts such as the patient acceptable symptom state (PASS) have been introduced. Currently, no PASS thresholds have been established for the Knee injury and Osteoarthritis Outcome Score (KOOS) after total knee arthroplasty. The aims of the current study were to define PASS thresholds for the KOOS subscales and several other generic and knee-specific PROMs at 1 and 3 years after total knee arthroplasty using data from an international, multicenter clinical outcome study of a modern, well-performing implant system. METHODS: The study cohort consisted of 499 patients undergoing total knee arthroplasty from an international, multicenter study. At 1 and 3 years after a total knee arthroplasty, patients completed the KOOS, EuroQoL 5-dimension 3-level (EQ-5D-3L), EuroQol visual analog scale (EQ-VAS), and numerical rating scales (NRS) for knee-related pain and satisfaction. PASS thresholds were calculated at each follow-up interval using 3 anchor-based approaches, using patient-reported satisfaction as the anchor. RESULTS: According to our satisfaction anchor, 302 (78.9%) of 383 responding patients were satisfied at 1 year, and 242 (80.4%) of 301 responding patients were satisfied at 3 years. PASS thresholds were 84.5 points at 1 year and 87.5 points at 3 years for KOOS pain, 80.5 points at 1 year and 84.0 points at 3 years for KOOS symptoms, 83.0 points at 1 year and 87.5 points at 3 years for KOOS activities of daily living, 66.0 points at 1 year and 66.0 points at 3 years for KOOS quality of life, 83.0 points at 1 year and 90.5 points at 3 years for EQ-VAS, 0.80 point at 1 year and 0.80 point at 3 years for EQ-5D, and 1.8 points at 1 year and 1.8 points at 3 years for NRS pain. CONCLUSIONS: The current study is the first, to our knowledge, to propose PASS thresholds for the KOOS subscales at 1 and 3 years after total knee arthroplasty and contributes to PASS literature on other common PROMs. These findings will provide a useful reference for future total knee arthroplasty outcome studies and will help to determine what patients consider to be satisfactory operations. LEVEL OF EVIDENCE: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

What Preoperative Factors are Associated With Not Achieving a Minimum Clinically Important Difference After THA? Findings from an International Multicenter Study.

BACKGROUND: Despite innovations in THA, there remains a subgroup of patients who experience only modest pain relief and/or functional improvement after the procedure. Although several studies have previously sought to identify factors before surgery that were associated with achieving or not achieving a meaningful improvement after THA, there is no consensus on which factors are most associated; many studies have relied on single-center or single-country multicenter studies for their cohorts. QUESTIONS/PURPOSES: We sought to identify (1) the proportion of patients who do not achieve a minimum clinically important difference (MCID) in pain and function 1 year after THA, and (2) the preoperative factors that were associated with not achieving MCIDs in pain and function 1 year after THA. METHODS: This retrospective study analyzed data gathered from a prospective international, multicenter study examining the long-term clinical outcomes of two different polyethylene liners and two different acetabular shells. A total of 814 patients from 12 centers across four countries were enrolled in the study, with the final cohort consisting of 594 patients (73%) who all had complete preoperative and 1-year PROMs as well as a valid preoperative radiograph used to measure minimum joint space width. The outcomes in this study were achieving evidence-derived MCIDs in (1) pain, defined as a reduction of two points on an 11-point (0 = very little, 10 = worst imaginable) numerical rating scale (NRS) for hip-related pain or reporting a 1 year NRS-pain score of 0, and (2) function, defined as an increase equal to or greater than 8.3 on the SF-36 Physical Function subscore (range: 0 to 100; 0 = maximum disability, 100 = no disability) or reporting a 1-year SF-36 Physical Function subscore within the 95th percentile of scores in our cohort. All demographic variables, such as age, sex, country; surgical factors, including body mass index (BMI), surgical approach, acetabular liner type, and preoperative PROMs, were included as covariates in a binary logistic regression model. We used a backwards stepwise elimination algorithm to reach the simplest, best-fit model. RESULTS: In the final analysis cohort of 594 patients, 54 patients (9%) did not achieve the MCID in pain and 146 (25%) patients did not achieve the MCID in physical function after THA. After controlling for potential confounding variables such as age, BMI, and preoperative PROMs, we found that higher joint space width (odds ratio (OR) = 2.19; 95% confidence interval (CI) = 1.49-3.22; p < 0.001), lower preoperative SF-36 Mental Component Summary (MCS) (OR = 0.95; 95% CI = 0.93-0.98; p = 0.001), and female sex (OR = 2.04; 95% CI = 1.08-3.82; p = 0.027) were associated with failing to achieve a MCID in pain. It is important to note that the effect size of having a higher preoperative SF-36 MCS is small, with a 1- or 10-point increase in SF-36 MCS decreasing the odds of a patient not achieving the pain MCID by 5% or 63%, respectively.In a separate multivariable model, after controlling for potential confounding variables such as age, BMI, and preoperative PROMs, we found that higher joint space width (OR = 1.54; 95% CI = 1.18-2.02; p = 0.002), higher preoperative Harris hip score (HHS) (OR = 1.01; 95% CI = 1.00-1.03; p = 0.019) and undergoing surgery in Scandinavia (OR = 1.73; 95% CI = 1.17-2.55; p = 0.006) were associated with failing to achieve a MCID in physical function. It is important to note that the effect size of having a higher preoperative HHS is very small, with a 1- or t10-point increase in HHS increasing the odds of not achieving the physical function MCID by only 1% or 15%, respectively. CONCLUSIONS: These findings suggest that surgeons should counsel patients with high joint space width, female patients, and patients undergoing surgery in Scandinavia that they may be much less likely to experience meaningful pain relief or functional improvement after THA, and in light of that, determine whether indeed surgery should be postponed or avoided in those patients. Lower SF-36 MCS score and higher HHS before surgery were also found to be associated with not achieving MCIDs in pain and physical function, respectively, after surgery, but both had relatively small effect sizes. Future prospective studies may consider exploring the relationship between less pain relief or functional improvement and the risk factors identified in this study, such as high joint space width, to validate our findings and determine if the variables we identified are truly predictive of worse postoperative outcomes. Future retrospective studies of regional or national registry data should use the analysis methods presented within this study to both identify the portion of the THA patients who do not achieve a MCID in pain or physical function after surgery and confirm if the preoperative risk factors for poor improvement identified within our international, multicenter cohort are also found in a larger patient population with more diverse implants and comorbidities. LEVEL OF EVIDENCE: Level III, therapeutic study.

The Benefits of National and Regional Arthroplasty Registries.

Since the first arthroplasty registries were established in the 1970s, they have become powerful tools in improving the efficiency of health care delivery and patient outcomes. As demonstrated over the past decades, registries can offer benefits not only to patients and surgeons but also to a variety of other stakeholders, such as hospitals, payers, and implant manufacturers. Registry data may be leveraged to address a variety of pressing concerns in the field of arthroplasty. These examples include the role of registries in (1) informing the financial aspects of an increasingly value-based payment system, (2) identifying best clinical practices, (3) improving the outcomes of individual health care providers, and (4) selecting new technologies through outlier detection and benchmarking. As registries continue to mature by improving data coverage and quality, they will play a central role in shaping the future of arthroplasty as well as orthopaedics in general.

Arthroplasty implant registries over the past five decades: Development, current, and future impact.

Local, regional, and national registries have played an important role in the development of hip and knee arthroplasty and the treatment of patients with various maladies of these joints. Four arthroplasty registries stand out as leading forces behind the drive to popularize the use of registries and pursue the concept of evidence based medicine. The Mayo registry, started by Mark Coventry, is recognized as the oldest continuing registry for arthroplasty. The Harris Registry at Massachusetts General Hospital, along with the Mayo Registry, has greatly contributed to the advancement of arthroplasty surgery and have served an important role of identifying poorly performing implants and techniques in the United States. The Swedish Knee Arthroplasty Registry is the oldest national registry dedicated to joint arthroplasty and along with the Swedish Hip Arthroplasty Registry have established the infrastructure, analysis and reporting mechanisms, and leadership that has enabled other countries to subsequently develop national registries around the world. As more countries have adopted the concept of national registries, a new area of research is possible by pooling the resources of large registries as is now occurring with the Nordic countries. Several international organizations have been formed to promote future collaboration and develop international standards. The process of globalization of registries is a result of continued efforts over the past 50 years in improving and disseminating the knowledge gained from the early registries. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:2319-2330, 2018.

Scoring the Current Risk Stratification Guidelines in Follow-up Evaluation of Patients After Metal-on-Metal Hip Arthroplasty: A Proposal for a Metal-on-Metal Risk Score Supporting Clinical Decision-Making.

BACKGROUND: In the follow-up evaluation of patients with metal-on-metal (MoM) hip replacements, current evidence suggests that orthopaedic surgeons should avoid reliance on any single investigative tool. Current risk stratification guidelines can be difficult to interpret because they do not provide guidance when there are several risk factors in different groups (high and low risk). To improve the clinical utility of risk stratification guidelines, we designed a scoring system to assess the risk of revision. METHODS: The study population consisted of 1,709 patients (1,912 hips) enrolled in a multicenter follow-up study of a recalled MoM hip replacement. Eleven scoring criteria were determined on the basis of existing follow-up algorithm recommendations and consisted of patient-related factors, symptoms, clinical status, implant type, metal ion levels, and radiographic imaging results. Forward stepwise logistic regression was conducted to determine the minimum set of predictive variables for the risk of revision and to assign variable weights. The MoM risk score for each hip was then created by averaging the weighted values of each predictive variable. RESULTS: Receiver operating characteristic curve analysis yielded good discrimination between all revised and unrevised hips, with an area under the curve of 0.82 (p < 0.001). The odds of revision for the group with a high MoM risk score were increased by 5.8-fold (95% confidence interval [CI], 3.1 to 11.0) relative to the moderate risk group and by 21.8-fold (95% CI, 9.9 to 48.0) compared with the low risk group. CONCLUSIONS: Although the use of MoM hip arthroplasty has been limited since 2010, we continue to be faced with the follow-up and risk assessment of thousands of patients who have not had a revision. As more knowledge about risk stratification is gained, the complexity of the algorithms is expected to increase. We propose the use of the MoM risk score as a tool to aid in the clinical decision-making process. LEVEL OF EVIDENCE: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.