Functional Outcome After Total Shoulder Arthroplasty in the Obese Patient Population

Xinning Li, MD
Hospital for Special Surgery

Phillip Williams, MD
Hospital for Special Surgery

Andromahi Trivellas, BS
Hospital for Special Surgery

Joseph Nguyen, MPH
Hospital for Special Surgery


Edward V. Craig, MD, MPH

Attending Orthopaedic Surgeon, Sports Medicine and Shoulder Service, Hospital for Special Surgery
Professor of Clinical Surgery, Weill Cornell Medical College

Russell F. Warren, MD

Attending Orthopaedic Surgeon, Hospital for Special Surgery
Professor of Orthopaedic Surgery, Weill Cornell Medical College

Lawrence V. Gulotta, MD

Assistant Attending Orthopaedic Surgeon, Hospital for Special Surgery
Assistant Professor of Orthopaedic Surgery, Weill Cornell Medical College

While obese patients comprise a significant and increasing portion of the patients who need joint replacements, there is little established evidence of whether or not obesity affects the successful outcome of total shoulder arthroplasty (TSA). Now, HSS has examined the impact of patient weight on the results of TSA.

3 Weight Groups Studied

The study reviewed the outcomes of 76 patients who received primary total shoulder replacement at HSS between 2009 to 2010. The patients were divided into 3 study groups according to their body mass index (BMI).

One group of 26 patients had a BMI of less than 25, which is considered normal weight. Another group of 25 patients had a BMI between 25 to 30, which is considered overweight. The third group of 25 patients had a BMI over 30, which classifies them as obese.

All three groups were followed prospectively for 2 years after their TSA, with interim follow-up at one year, using data collected before, during, and after their surgeries.

Function Improved

All of the patients showed significant improvement in their functional outcomes, as well as pain relief, after TSA. (Complete scores below)

Functional measurements used for comparison and statistical analysis in the study included results on the standard American Shoulder and Elbow Surgeons Evaluation Form (ASES), as well as scores from two components of the Short Form Health Survey (SF-36), the physical component (PC) and mental component (MC). 

Even though the obese group started at a lower level of function on the ASES before surgery, at two-year follow-up, the obese group scored at the same improved level of function as the normal BMI group.

While all 3 groups improved, in one area, obese and overweight patients did have significantly lower scores than the normal BMI group, and that was on the physical component of the Short Form Health Survey (SF-36). No differences were found for the groups in SF-36 MC scores or general health and fatigue scales.

Pain Reduced

All three groups experienced important pain relief after shoulder replacement, showing similar degrees of improvement, with the obese group reporting the highest though not significantly so level of pain reduction.

Pain levels were measured using the Visual Analog Score (VAS) methodology, where patients report self-evaluation of their own pain.

No Significant Differences in Operating Room

While operating room (OR) time and intraoperative blood loss was higher in the obese group, it was not significant. There were also no significant differences among the groups on any studied measurement of OR or hospital experience, including the American Society of Anesthesia (ASA) Classification Scores.

Weight did not affect number of days in the hospital, complications during surgery, or postoperative blood transfusion.

TSA Benefitted All Patients

Overall, while patients with lower weight were able to demonstrate greater function after TSA, having a shoulder replacement was shown to benefit all three groups of patients. This study indicates obesity does not prevent a patient from experiencing improved function and reduced pain from TSA. Nor does weight affect patient experience in the operating room or hospital stay.

Functional Outcomes Scores Before and After TSA:

Normal BMI Group:

  • Average ASES: Improved from 38.4 +/- 15.5 (pre-op) to 80.2 +/- 19.4 (2yr)
  • SF-36 PC: Improved from 38.3 +/- 6.5 (pre-op) to 53.7 +/- 11.3 (2yr)
  • VAS: Pain decreased from 62 to 12 (2yr)

Overweight BMI Group:

  • Average ASES scores: Improved from 37.4 +/- 18.1 (pre-op) to 75.2 +/- 24.9 (2yr)
  • SF-36 PC: Improved rom 36.1 +/- 8.0 (pre-op) to 39.8 +/- 12.2 (2yr)
  • VAS: Pain decreased from 68 to18 (2yr)

Obese BMI group:

  • Average ASES scores: Improved from 35.8 +/- 12.5 (pre-op) to 80.0 +/- 20.6 (2yr)
  • SF-36 PC: Improved from 36.3 +/- 8.4 (pre-op) to 40.7 +/- 12.4 (2yr)
  • VAS: Pain decreased from 66 to 11 (2yr)

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