Jamie E. Collins

Estimating the Burden of Total Knee Replacement in the United States

BACKGROUND In the last decade, the number of total knee replacements performed annually in the United States has doubled, with disproportionate increases among younger adults. While total knee replacement is a highly effective treatment for end-stage knee osteoarthritis, total knee replacement recipients can experience persistent pain and severe complications. We are aware of no current estimates of the prevalence of total knee replacement among adults in the U.S. METHODS We used the Osteoarthritis Policy Model, a validated computer simulation model of knee osteoarthritis, and data on annual total knee replacement utilization to estimate the prevalence of primary and revision total knee replacement among adults fifty years of age or older in the U.S. We combined these prevalence estimates with U.S. Census data to estimate the number of adults in the U.S. currently living with total knee replacement. The annual incidence of total knee replacement was derived from two longitudinal knee osteoarthritis cohorts and ranged from 1.6% to 11.9% in males and from 2.0% to 10.9% in females. RESULTS We estimated that 4.0 million (95% confidence interval [CI]: 3.6 million to 4.4 million) adults in the U.S. currently live with a total knee replacement, representing 4.2% (95% CI: 3.7% to 4.6%) of the population fifty years of age or older. The prevalence was higher among females (4.8%) than among males (3.4%) and increased with age. The lifetime risk of primary total knee replacement from the age of twenty-five years was 7.0% (95% CI: 6.1% to 7.8%) for males and 9.5% (95% CI: 8.5% to 10.5%) for females. Over half of adults in the U.S. diagnosed with knee osteoarthritis will undergo a total knee replacement. CONCLUSIONS Among older adults in the U.S., total knee replacement is considerably more prevalent than rheumatoid arthritis and nearly as prevalent as congestive heart failure. Nearly 1.5 million of those with a primary total knee replacement are fifty to sixty-nine years old, indicating that a large population is at risk for costly revision surgery as well as possible long-term complications of total knee replacement.

Clinical Outcome of Metastatic Spinal Cord Compression Treated with Surgical Excision ± Radiation Versus Radiation Therapy Alone: A Systematic Review of Literature

Study Design. Systematic literature review from 1970 to 2007. Objective. This study reports the results of a systematic review comparing surgical decompression ± radiation to radiation therapy alone among patients with metastatic spinal cord compression. Summary of Background Data. Currently, the optimal treatment of metastatic spine lesions is not well defined and is inconsistent. Radiation and surgical excision are both accepted and effective. There appears to be a favorable trend for improved neurological outcome with surgical excision and stabilization as part of the management. Methods. A review of the English literature from 1970 to 2007 was performed in the Medline database using general MeSH terms. Relevant outcome studies for the treatment of metastatic spinal cord compression were selected through criteria defined a priori. The primary outcome was ambulatory capacity. A random effects model was built to compare results between treatment groups, based on calculated proportions from each study. Results. Of the 1595 articles screened, 33 studies (2495 patients) were selected based on our inclusion and exclusion criteria. Sixty-four percent of the patients who underwent surgical decompression, tumor excision, and stabilization had neurological improvement from nonambulatory to ambulatory status. Twenty-nine percent of the radiation therapy group regained the ability to ambulate after treatment (P < 0.001). Paraplegic patients had a 4-fold greater recovery rate to functional ambulation with surgical intervention than with radiation therapy alone (42% vs. 10%, P < 0.001). Pain relief was noted in 88% of the patients in the surgical studies and in 74% of the patients in studies of radiation therapy (P < 0.001). The overall surgical complication rate was 29%. Conclusion. This systematic review suggests that surgical excision of tumor and instrumented stabilization may improve clinical outcomes compared with radiation therapy alone, with regard to neurological function and pain. However, most data in the current literature are from observational studies, where variations in patient population and treatments cannot be controlled. This compromised our ability to compare the results of both treatments directly.

Trajectories and Risk Profiles of Pain in Persons with Radiographic, Symptomatic Knee Osteoarthritis: Data from the Osteoarthritis Initiative

BACKGROUND Little is known about the temporal evolution of pain severity in persons with knee osteoarthritis (OA). We sought to describe the pain trajectory over 6 years in a cohort of subjects with radiographic, symptomatic knee OA. METHODS We used data from the Osteoarthritis Initiative (OAI), a multi-center, longitudinal study of subjects with diagnosed radiographic evidence of knee OA. Pain was assessed at baseline and annually for 6 years. Our analysis cohort included subjects with symptomatic knee OA at baseline, defined as baseline Kellgren-Lawrence (KL) score ≥2 with Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain score >0. We used group-based trajectory modeling to identify distinct patterns of pain progression over a 6-year follow-up. Factors examined included sex, race, education, comorbidities, age, body mass index (BMI), alignment, KL grade, and depression. RESULTS We used data from 1753 OAI participants with symptomatic knee OA. Mean baseline WOMAC pain score was 26.5 (0-100, 100=worst) with standard deviation (SD) 19. Group-based trajectory modeling identified five distinct pain trajectories; baseline pain scores for each ranged from 15 to 62. None of the trajectories exhibited substantial worsening. One fifth of subjects in the two trajectories with the greatest pain underwent total knee replacement (TKR) over follow-up. Higher KL grade, obesity, depression, medical comorbidities, female sex, non-white race, lower education, and younger age were associated with trajectories characterized by greater pain. CONCLUSION We found that knee pain changes little, on average, over 6 years in most subjects. These observations suggest knee OA is characterized by persistent rather than inexorably worsening symptoms.

Influence of maternal BMI on genetic sonography in the FaSTER trial

We sought to evaluate the influence of maternal body mass index (BMI) on sonographic detection employing data from the FaSTER trial.

Patient satisfaction after primary total and unicompartmental knee arthroplasty: An age-dependent analysis

BACKGROUND Patient-related outcomes have become the focus of increased attention when assessing knee arthroplasty. METHODS We retrieved questionnaires from 485 (584 knees) patients at a minimum of 3years after undergoing primary knee arthroplasty. We excluded bilateral knee arthroplasty, leaving 141 UKA and 245 TKA who rated their satisfaction and expectation regarding pain, range of motion (ROM), daily living function (DLF), return to recreational activity (RRA) and ability to kneel (ATK) on a scale of 0 (worst) to 10 (best). We further collected data on pain level and the modified Cincinnati rating scale. Range of motion was documented pre- and postoperatively at a minimum of six months. The cohort was subdivided into three age groups and compared with each other (Group 1: <55, n=113; Group 2: 55-64, n=117; Group 3: 65+, n=155). RESULTS Average satisfaction with pain, ROM and ATK for patients under 55 was higher for UKA than for TKA. Patients>65 with TKA were on average more satisfied than patients with UKA in these three items. However, patients under 55 with UKA were up to 2.9 times more likely to have their expectations met when compared to patients receiving TKA. Patients with UKA under 55 rated their joint as good/excellent in 96.0% versus patients in the same age group with TKA in 81.0%. CONCLUSIONS We found that overall, younger patients who were treated with UKA demonstrated higher satisfaction scores in most subsets when compared with the patients of the same age group who received TKA.

Predictive validity of biochemical biomarkers in knee osteoarthritis: data from the FNIH OA Biomarkers Consortium

Objective To investigate a targeted set of biochemical biomarkers as predictors of clinically relevant osteoarthritis (OA) progression. Methods Eighteen biomarkers were measured at baseline, 12 months (M) and 24 M in serum (s) and/or urine (u) of cases (n=194) from the OA initiative cohort with knee OA and radiographic and persistent pain worsening from 24 to 48 M and controls (n=406) not meeting both end point criteria. Primary analyses used multivariable regression models to evaluate the association between biomarkers (baseline and time-integrated concentrations (TICs) over 12 and 24 M, transposed to z values) and case status, adjusted for age, sex, body mass index, race, baseline radiographic joint space width, Kellgren-Lawrence grade, pain and pain medication use. For biomarkers with adjusted p<0.1, the c-statistic (area under the curve (AUC)), net reclassification index and the integrated discrimination improvement index were used to further select for hierarchical multivariable discriminative analysis and to determine the most predictive and parsimonious model. Results The 24 M TIC of eight biomarkers significantly predicted case status (ORs per 1 SD change in biomarker): sCTXI 1.28, sHA 1.22, sNTXI 1.25, uC2C-HUSA 1.27, uCTXII, 1.37, uNTXI 1.29, uCTXIα 1.32, uCTXIβ 1.27. 24 M TIC of uCTXII (1.47–1.72) and uC2C-Human Urine Sandwich Assay (HUSA) (1.36–1.50) both predicted individual group status (pain worsening, joint space loss and their combination). The most predictive and parsimonious combinatorial model for case status consisted of 24 M TIC uCTXII, sHA and sNTXI (AUC 0.667 adjusted). Baseline uCTXII and uCTXIα both significantly predicted case status (OR 1.29 and 1.20, respectively). Conclusions Several systemic candidate biomarkers hold promise as predictors of pain and structural worsening of OA.

Outcomes of open carpal tunnel release at a minimum of ten years.

BACKGROUND There is little research on the long-term outcomes of open carpal tunnel release. The purpose of this retrospective study was to determine the functional and symptomatic outcomes of patients at a minimum of ten years postoperatively. METHODS Two hundred and eleven patients underwent open carpal tunnel release from 1996 to 2000 performed by the same hand fellowship-trained surgeon. Follow-up with validated self-administered questionnaire instruments was conducted an average of thirteen years after surgery. The principal outcomes included the Levine-Katz symptom and function scores, ranging from 1 point (best) to 5 points (worst), and satisfaction with the results of surgery. The patients self-reported current comorbidities. RESULTS After a mean follow-up of thirteen years (range, eleven to seventeen years), 92% (194) of 211 patients were located. They included 140 who were still living and fifty-four who had died. Seventy-two percent (113) of the 157 located, surviving patients responded to the questionnaire. The mean Levine-Katz symptom score (and standard deviation) was 1.3 ± 0.5 points, and 13% of patients had a poor symptom score (≥2 points). The mean Levine-Katz function score was 1.6 ± 0.8 points, and 26% had a poor function score (≥2 points). The most common symptom-related complaint was weakness in the hand, followed by diurnal pain, numbness, and tingling. The least common symptoms were nocturnal pain and tenderness at the incision. Eighty-eight percent of the patients were either completely satisfied or very satisfied with the surgery. Seventy-four percent reported their symptoms to be completely resolved. Thirty-three percent of men were classified as having poor function compared with 23% of women. Two (1.8%) of 113 patients underwent repeat surgery. CONCLUSIONS At an average of thirteen years after open carpal tunnel release, the majority of patients are satisfied and free of symptoms of carpal tunnel syndrome.

Cumulative incidence of ACL reconstruction after ACL injury in adults: Role of age, sex and race

Background: Anterior cruciate ligament (ACL) injuries are common and potentially disabling and frequently prompt surgical reconstruction. The utilization of ACL reconstruction among ACL-injured patients has not been examined rigorously. Purpose: This study reports the 3-year cumulative incidence of ACL reconstruction among adults with ACL injury and compares demographic and clinical characteristics of ACL-injured patients who do and do not go on to undergo ACL reconstruction. Study Design: Cohort study; Level of evidence, 3. Methods: A tertiary health care system patient data repository was used to identify patients diagnosed with an ACL injury between January 1, 2001, and December 31, 2007. Follow-up data were obtained to determine how many patients with ACL injury underwent ACL reconstruction within 3 years of ACL injury diagnosis. Stratified analyses were used to examine incidence rates separately by sex, age, race, primary language, socioeconomic status (SES), and health insurance status. Multivariable logistic regression models were built to examine the association of patient characteristics with utilization of ACL reconstruction. Results: There were 2304 patients, with a mean age of 47 years, diagnosed with an ACL injury between 2001 and 2007. The 3-year cumulative incidence of ACL reconstruction after ACL injury diagnosis was 22.6% (95% CI, 20.9%-24.3%). Eighty-six percent of patients undergoing reconstruction did so within 6 months of injury diagnosis, while 94% underwent reconstruction within 1 year. In multivariable models, several patient features were independently associated with a higher adjusted odds of undergoing ACL reconstruction, including male sex (adjusted odds ratio [aOR], 1.4; 95% CI, 1.1-1.7), younger age (aOR per decade, 1.8; 95% CI, 1.7-2.0), white race (aOR, 1.4; 95% CI, 0.94-1.9), higher SES (aOR, 1.4; 95% CI, 1.04-1.8 for high vs low SES; aOR, 1.3; 95% CI, 1.02-1.8 for medium vs low SES), and private health insurance versus self-pay (aOR, 1.9; 95% CI, 1.04-3.5). Conclusion: Less than a quarter of patients with a diagnosed ACL injury underwent ACL reconstruction in the 3 years after diagnosis. The odds of having surgery were higher for men, whites, younger patients, patients with higher SES, and patients with private health insurance.

Brief Report: Cartilage Thickness Change as an Imaging Biomarker of Knee Osteoarthritis Progression: Data From the Foundation for the National Institutes of Health Osteoarthritis Biomarkers Consortium.

To investigate the association of cartilage thickness change over 24 months, as determined by magnetic resonance imaging (MRI), with knee osteoarthritis (OA) progression at 24–48 months.

Longitudinal validation of periarticular bone area and 3D shape as biomarkers for knee OA progression? Data from the FNIH OA Biomarkers Consortium

Objective To perform a longitudinal validation study of imaging bone biomarkers of knee osteoarthritis (OA) progression. Methods We undertook a nested case–control study within the Osteoarthritis Initiative in knees (one knee per subject) with a Kellgren and Lawrence grade of 1–3. Cases were defined as knees having the combination of medial tibiofemoral radiographic progression and pain progression at the 24-month, 36-month or 48-month follow-up compared with baseline. Controls (n=406) were eligible knees that did not meet both endpoint criteria and included 200 with neither radiographic nor pain progression, 103 with radiographic progression only and 103 with pain progression only. Bone surfaces in medial and lateral femur, tibia and patella compartments were segmented from MR images using active appearance models. Independent variables of primary interest included change from baseline to 24 months in (1) total area of bone and (2) position on three-dimensional (3D) bone shape vectors that discriminate OA versus non-OA shapes. We assessed the association of bone markers changes over 24 months with progression using logistic regression. Results 24-month changes in bone area and shape in all compartments were greater in cases than controls, with ORs of being a case per 1 SD increase in bone area ranging from 1.28 to 1.71 across compartments, and per 1 SD greater change in 3D shape vectors ranging from 1.22 to 1.64. Bone markers were associated most strongly with radiographic progression and only weakly with pain progression. Conclusions In knees with mild-to-moderate radiographic OA, changes in bone area and shape over 24 months are associated with the combination of radiographic and pain progression over 48 months. This finding of association with longer term clinical outcome underscores their potential for being an efficacy of intervention biomarker in clinical trials.