Rheumatology News

7 ORTHOPEDICS

Vol. 4 • No. 1 • 2016 • R heumatology N ews

Functional dependence linked to risk of complications after spine surgery

Thigh muscle weakness a risk factor for knee replacement in women

Dr Patel reported findings from 24,357 patients: 23,620 (97.0%) functionally independent, 664 (2.7%) partially de- pendent, and 73 (0.3%) totally dependent. Dependent patients were significantly older and had higher rates of all comorbidi- ties (P < 0.001), with the exception of obesity (P = 0.214). In addition, 30-day complication rates were higher for all com- plications (P < 0.001) other than neurological (P = 0.060) and surgical site complications (P = 0.668). When the researchers controlled for type of procedure and for disparities in patient preoperative variables, multivariate analyses demonstrated that functional dependence was independently associated with sepsis (odds ratio 6.40; P < 0.001), pulmonary (OR 4.13; P < 0.001), venous thromboembolism (OR 4.27, P < 0.001), renal (OR 3.32; P < 0.001), and cardiac complications (OR 4.68; P = 0.001), along with mortality (OR 8.31; P < 0.001). “The very strong association between functional dependence and mortality was quite surprising,” Dr Patel said. “It was, to the contrary, also surprising to see that, despite wide vari- ance in medical comorbidities and functional status, surgical complications such as infection and neurological injury were similar in all groups.” He characterised the study as “the first large-scale assessment of functional status as a predictor of patient outcomes after cervical spine surgery. It fits in line with other studies utilising large databases. Big data analysis of outcomes can be used to identify risk factors for complica- tions including death after surgery. Identifying these factors is important if we are going to improve the care we provide. Accu- rately quantifying the impact of these risk factors is also critical when we risk stratify and compare hospitals and physicians.” He acknowledged certain limitations of the study, including the fact that it is a retrospective study “with a heterogeneous population of patients, surgeons, hospitals, and procedures. This adds uncertainty to the analysis at the level of the indi- vidual patient but does provide generalisability to a broader patient population.”

BY DOUG BRUNK Frontline Medical News At CSRS 2015, Toronto

BY NICOLA GARRETT Frontline Medical News From Arthritis & Rheumatology

F unctional dependence following elective cervical spine procedures was associated with a significantly increased risk of almost all 30-day complications analysed, includ- ing mortality, a large retrospective analysis of national data demonstrated. The findings suggest that physicians should “include the patient’s level of functional independence, in addition to more traditional medical comorbidities, in the risk-benefit analysis of surgical decision making,” Dr Alpesh A. Patel said in an interview in advance of the annual meeting of the Cervical Spine Research Society. “Those individuals with dependence need to be counselled appropriately about their increased risk of complications including mortality.” Dr Patel, professor and director of orthopaedic spine surgery at Northwestern University Feinberg School of Medicine, Chi- cago, and his associates retrospectively reviewed the American College of Surgeons National Surgical Quality Improvement Program (ACSNSQIP) data files from 2006 to 2013 and limited their analysis to patients undergoing elective anterior cervi- cal fusions, posterior cervical fusions, cervical laminectomy, cervical laminotomy, cervical discectomy, or corpectomy. They divided patients into one of three groups based on the follow- ing preoperative functional status parameters: independent, comprising those not requiring assistance or any equipment for activities of daily living (ADLs); partially dependent, includ- ing those with equipment such as prosthetics, equipment, or devices and requiring some assistance from another person for ADLs; and totally dependent, in which patients require total assistance for all ADLs. The researchers used univariate analysis to compare patient demographics, comorbidities, and 30-day postoperative complications among the three groups, followed by multivariate logistic regression to analyse the independent association of functional dependence on 30-day complications when controlling for procedure and comorbidity variances.

W omen with knee osteoarthritis who had low thigh muscle strength were more likely to need a knee replacement in a case-control study of participants in the Osteoarthritis Initiative (OAI). In particular, predictors of knee replacement included knee extensor weakness in the year prior to knee replacement and longitudinal deterioration in knee extensor strength over a 2-year observation period prior to surgery. Measurement of knee exten- sor strength in women with knee osteoarthritis may then indicate who could benefit from weight training exercises to potentially delay or prevent the need for knee replacement surgery, said the researchers, led by Dr Adam Culvenor of Paracelsus Medical University in Salzburg, Austria.

Dr Patel reported having no conflicts of interest.

The optimal knee extensor strength threshold for differentiat- ing those with and without knee replacement risk was approxi- mately 200 N or 0.9 Nm/kg; or prevention of any loss of knee extensor strength over 2 years. “There appears to be a considerable window for women below this threshold to obtain realistic strength gains and potentially lower the risk of knee replacement,” the study authors concluded. In the multicentre, longitudinal, case-control study of 4796 participants in the OAI (60% of whom were women), the investigators identified 136 participants who had received a knee replacement and matched them with controls who had not received a knee replacement and were similar in age, body mass index (BMI), and radiographic stage. The mean age of the women was 65 years and the mean BMI was 29 kg/m 2 . The results showed that knee extensor strength at the examina- tion prior to knee replacement (time T 0 ), which occurred 2 years or less before surgery, was significantly lower in females who had received a knee replacement than in matched controls (pain- adjusted odds ratio, 1.72; 95% confidence interval, 1.16–2.56; P = 0.007). Measurement of the longitudinal change in knee extensor and flexor strength between T 0 and 2 years prior to T 0 (T -2 ) also provided similar results (pain-adjusted OR, 4.30; 95% CI, 1.34–13.79; P = 0.014). The findings were independent of age, BMI, and radiographic disease severity, the researchers noted. The investigators found no relationship between knee extensor or flexor muscle strength in men and subsequent need for knee replacement surgery. The relationship between thigh muscle strength and knee replacement for women did not extend to measurements made at T -2 or T -4 or the change in thigh muscle strength between T -2 and T -4 . The OAI receives funding from the National Institutes of Health, Merck Research Laboratories, Novartis, GlaxoSmithKline, and Pfizer. The work was also funded by a grant from the European Union Seventh Framework Programme. One author disclosed consulting or preparing educational sessions for pharmaceutical companies and for receiving research support. Two authors reported being employees of Chondrometrics GmbH, a company providing MR image analysis services to academic researchers and to industry.

Benefits, risks of total knee replacement for OA illuminated in trial

nonsurgical intervention (50 patients) or receive the comprehensive nonsur- gical intervention alone (50 patients) at two specialised university clinics in Denmark. The 12-week nonsurgical intervention comprised a twice-weekly group exercise program to restore neu- tral, functional realignment of the legs; two 1-hour education sessions regard- ing osteoarthritis characteristics, treat- ments, and self-help strategies; a dietary (weight-loss) program; provision of indi- vidually fitted insoles with medial arch support and a lateral wedge if patients had knee-lateral-to-foot positioning; and as-needed pain medication for pain – acetaminophen and ibuprofen – and pantoprazole, a proton-pump inhibitor. The primary outcome measure in the trial was the between-group difference at 1 year in improvement on four subscales of the Knee Injury and Osteoarthritis Outcome Scores (KOOS) for pain, symptoms, activities of daily living, and quality of life. The surgical group showed a significantly greater improvement (32.5 out of a possible 100 points) than the nonsurgical group (16.0 points) in this outcome. The surgical group also showed significantly greater improvements in all

five individual subscales and in a timed chair-rising test, a timed 20-metrewalk test, and on a quality-of-life index, the investigators said. However, it is important to note that patients who had only the nonsurgical intervention showed clinically relevant improvements, and only 26% of them chose to have the surgery after the con- clusion of the study. As expected, the surgical group had more serious adverse events than did the nonsurgical group (24 vs 6), including three cases of deep venous thrombosis and three cases of knee stiffness requiring brisement forcé while the patient was anesthetised, Dr Skou and his associates said. This study was supported by the Obel Family Foundation, the Danish Rheu- matism Association, the Health Science Foundation of the North Denmark Region, Foot Science International, Spar Nord Foundation, the Bevica Foundation, the Association of Danish Physiotherapists Research Fund, the Medical Specialist Heinrich Kopp’s Grant, and the Danish Medical Association Research Fund. Dr Skou and his associates reported hav- ing no relevant financial disclosures.

BY MARY ANN MOON Frontline Medical News

From the New England Journal of Medicine T otal knee replacement was superior to nonsurgical treatment in reliev- ing pain, restoring function, and improving quality of life for patients with moderate to severe knee osteoarthritis, according to a report published online Oct. 22 in the New England Journal of Medicine . Even though the number of total knee replacements performed each year is large and steadily increasing – with more than 670,000 done in 2012 in the US alone – no high-quality randomised, controlled trials have ever compared the effective- ness of the procedure against nonsurgical treatment, said Søren T. Skou, PhD, of the Research Unit for Musculoskeletal Function and Physiotherapy, Institute of Sports Science and Clinical Biomechan- ics, University of Southern Denmark, Odense, and his associates. Dr Skou and his colleagues remedied that situation by randomly assigning 100 adults (mean age, 66 years) who were eligible for unilateral total knee replace- ment to either undergo the procedure and then receive a comprehensive