Obesity affects outcomes after distal radius fracture surgical treatment

The first study to examine the impact of obesity on outcomes after surgical treatment of distal radius fractures finds worse outcomes for obese patients than for their non-obese counterparts.

“Based on our data, obese patients appear to have some worse outcomes than non-obese patients 1 year following operative fixation of distal radius fractures,” said Kenneth A. Egol, MD. “This may be due to the increased energy of impact and associated soft-tissue injury seen in obese patients during falls and other accidents.”

Dr. Egol and Eric Strauss, MD, presented the study—“Does body mass index (BMI) impact the outcomes after the operative treatment of distal radius fractures?”—at the 2009 AAOS Annual Meeting last month.

BMI scores divide patients
In this retrospective study, 394 consecutive patients with distal radius fractures were enrolled in a database over 4 years. Patients were classified as obese or not obese based on their BMI score (BMI of 30 or greater is considered obese).

Of the 394 patients, 190 received surgical treatment for their fractures and completed at least 1 year of follow-up. Approximately 1 in 5 patients treated surgically (43, or 22.6 per­cent) were classified as obese; 147 surgical patients (77.4 per­cent) were classified as non-obese.

Open reduction and internal fixation—utilizing a volar locked plate—was used for 113 non-obese patients (76.9 percent) and 31 obese patients (72 percent).

Of the 46 patients who received bridging external fixation, 34 (23.1 percent) were categorized as non-obese and 12 (28.0 percent) as obese.

Following surgery, range of motion (ROM) of the wrist and fingers was assessed using a goniometer. Grip strength was compared to the contralateral uninjured wrist with a dynamometer.

At each visit, fracture union, loss of reduction, and the development of arthritis was evaluated radiographically by the treating surgeon.

“Measurement of radial inclination, height, tilt, ulnar variance, and intra-articular set-off was made on each radiograph,” explained Dr. Egol. “We noted the presence of arthritic changes at the 6-month and 12-month exams.”

Impact of obesity on outcomes
Obese patients sustain “an increased energy of impact and associated soft-tissue injury during falls and other accidents,” according to Dr. Egol.

He believes his study supports this because the obese patients had a “higher percentage of the more complex Orthopaedic Trauma Association type C fracture pattern.”

This confluence of factors could have also contributed to the poorer outcomes.

After short-term (6 weeks) and long-term (1 year) postoperative follow up, Dr. Egol and his colleagues compared the following outcomes from the two patient groups: postoperative pain, radio­graphic appearance, wrist ROM, finger ROM, grip strength, and functional outcomes.

At 6 weeks, obese patients had significantly more pain, as measured by the visual analog scale, than the non-obese group (3.3 vs. 2.6; P < 0.03).

Obese patients also had significantly worse grip strength (17.8 vs. 24.2; P < 0.03) and fewer index, middle, and ring finger total arcs of motion.

No difference in range of wrist motion was noted between the two groups and evaluation of radiologic parameters showed similar mean values.

Results were slightly different at the 12-month follow-up. Although the obese group continued to experience more pain than their non-obese counterparts (2.7 vs. 1.6; P < 0.005), the finger range of motion between the groups was no longer significantly different. The obese group did, however, have worse wrist flexion and supination (Fig. 1).

Although radiographic parameters at 12 months showed similar mean values between the groups, “a greater extent of degenerative change within the radiocarpal joint, with significantly higher osteoarthritis scores” was seen in obese patients, reported Dr. Egol.

Obese patients demonstrated a higher degree of disability than those in the non-obese group, with considerably higher scores on the Disabilities of the Arm, Shoulder and Hand outcome measure and lower scores on the SF-36 Health Survey (Fig. 2). They also had a significantly higher total number of comorbidities (1.9 vs. 1.4, P < 0.001).

Patient considerations
Although he does not advise treating obese and non-obese patients differently, Dr. Egol believes it is important to consider that “obesity may be an independent predictor of persistent postoperative pain and a poorer functional outcome following the operative fixation of a distal radius fracture.”

Obese patients should be counseled by their orthopaedic surgeons that their outcomes could be adversely affected by their obesity.

Co-authors of the study include Craig M. Capeci, MD; Allison B. Spitzer, BA, and Michael Walsh, PhD.

Dr. Egol reported the following disclosures: Exactech; Biomet, Smith & Nephew, Stryker, Synthes, and Johnson & Johnson. His co-authors did not report any conflicts of interest.

Annie Hayashi is the senior science writer for AAOS Now. She can be reached at hayashi@aaos.org