Rheumatology News

Thigh muscle weakness

a risk factor for knee

replacement in women

BY NICOLA GARRETT

Frontline Medical News

From Arthritis & Rheumatology

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.

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

The results showed that knee extensor strength at the examina-

tion prior to knee replacement (time T

), 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

and 2 years prior to 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.

Functional dependence linked to risk of

complications after spine surgery

BY DOUG BRUNK

Frontline Medical News

At CSRS 2015, Toronto

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.

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.”

Dr Patel reported having no conflicts of interest.

Benefits, risks of total knee replacement for

OA illuminated in trial

BY MARY ANN MOON

Frontline Medical News

From the New England Journal of Medicine

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

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.

Vol. 4 • No. 1 • 2016 •

heumatology

ews

ORTHOPEDICS