Obesity may limit overall function two years after shoulder replacement surgery

Patients with obesity undergo a disproportionately higher number of elective orthopaedic surgeries in the U.S. Obesity has been linked to higher costs, complications, infections and revisions in total knee and total hip replacement surgeries. In a new study published in the Journal of Bone and Joint Surgery, researchers looked at the impact of obesity on the costs and outcomes of total shoulder arthroplasty (TSA) surgery.

"Our study found that with short-term follow-up, obesity does not have a detrimental effect on functional outcomes and complication rates in patients after TSA," said orthopaedic surgeon and lead study author Xinning Li, MD. "In the normal body mass index (BMI) patient group, both the shoulder function and the overall physical function improved after TSA. However, among patients diagnosed with obesity, we found that the shoulder function improved after TSA, but the overall physical function did not improve at final follow-up."

Specific Study Details

The study involved 76 shoulder arthroplasty (replacement) patients who were grouped according to body mass index (BMI). Patients with a BMI of <25 kg/m² were classified as "normal" (26 patients); those with a BMI of 25 to 29.9 kg/m², "overweight" (25 patients); and ≥30 kg/m², "obese" (25 patients). Preoperative demographics and complications during and after surgery were recorded. Patients were assessed before surgery, and at two years after surgery, through the American Shoulder and Elbow Surgeons (ASES) questionnaire for pain and function; the Physical Component Summary (PCS) Short Form-36, a more comprehensive assessment of overall function; and analog pain scores.

Key Study Findings

The study results included:

• Pain diminished comparably in all weight groups at two years post-surgery: from a score of 62 to 12 in the normal weight group, 68 to 18 in the overweight group, and 66 to 11 in the obese group.
• There was one infection among patients who were overweight that required surgical intervention, and two surgical revisions in the normal weight group.
• In the normal weight group, the mean ASES scores increased from 38.4 ±15.5 preoperatively to 80.2 ±19.2 at two years post-surgery. The PCS score increased from 38.3 ±6.5 points preoperatively to 53.7 ±11.3 points at two years post-surgery.
• In the group with patients who were overweight, ASES scores increased from 37.4 ±18.1 points to 75.2 ± 24.9; PCS scores increased from 36.1 ±8 points to 39.8 ±12.2.
• In the group diagnosed with obesity, ASES scores increased from 35.8 ±12.5 to 80 ±20.6; PCS scores increased from 36.3 ±8.4 to 40.7 ±12.4.

"This data suggests that in the normal BMI patient group who are active, that their overall physical function may have been limited due to shoulder pain," said Dr. Li. "Therefore, a total shoulder replacement was able to provide this patient population (normal BMI) with improved shoulder function which resulted in a better physical function.

"Total shoulder arthroplasty is an excellent procedure for pain relief and functional improvement in patients with shoulder arthritis," said Dr. Li.