Exercise Medicine Helps Patient With ‘Osteobesity’ Avoid Knee Replacement

A 50-year-old white female with hypertension and a body mass index (BMI) of 53.4 presented with progressively worsening bilateral knee pain over three months. She denied any recent injury or change in activity and reported a fairly sedentary lifestyle.

Imaging showed bilateral knee degenerative arthritis, tricompartmental marginal osteophytes and marked medial compartment narrowing with no joint effusion or soft tissue swelling.

Treatment conundrum

While total knee arthroplasty (TKA) is a definitive treatment for knee osteoarthritis, this patient had a 7.41% risk of not being discharged home after surgery due to class 3 obesity. Conventionally, obesity has been linked with higher risk of infection and other complications after TKA, leading many surgeons to consider patients for TKA only if their BMI is 40 or lower.

“What should we advise patients who are at high risk for complication after TKA because of their high BMI, which is partly due to their sedentary lifestyle?” asks Matthew Kampert, DO, a sport and exercise medicine physician at Cleveland Clinic. “I have named their condition ‘osteobesity.’ It’s a downward spiral of worsening joint pain due to high BMI and increasing BMI due to immobilizing joint pain.”

Value of treatment with semaglutide

Anti-obesity medication like semaglutide could be a first-line treatment for this patient’s joint pain, notes Dr. Kampert. While often an effective weight-loss therapy, semaglutide can cost up to $1,365 per month. (Actual price can vary.)

In the STEP 4 study comparing semaglutide with placebo over 68 weeks, researchers reported significant weight loss: 17.3% fewer pounds with semaglutide compared to 2.0% fewer pounds with placebo. However, 52 weeks after stopping use of semaglutide, patients had regained 67.1% of the lost weight, adjusting their total weight loss to only 5.7%.

The value of using semaglutide over those 120 weeks can be represented as 5.7% weight loss for $23,205 (17 months [68 weeks] of semaglutide x $1,365) — or 1% weight loss for $4,071.

Quality of treatment with semaglutide

“We know that patients taking these drugs lose weight, but where is the weight loss coming from?” asks Dr. Kampert.

He points to the STEP 1 trial in which a cohort of patients taking semaglutide had 14.9% weight loss. However, according to DEXA scan, 5.4% of the loss came from lean body mass.

“These participants in the STEP 1 trial also were prescribed a reduced-calorie diet and increased physical activity — 150 minutes per week,” Dr. Kampert says. “But according to American College of Sports Medicine guidelines, adults with obesity may benefit from progression to 250-300 minutes of exercise per week. Some may require progression up to 630 minutes per week. And on at least two days per week, resistance training should be incorporated — something that was not prescribed in the trial. If exercise is medicine, the trial treatment was poor medical management.”

To treat patients for obesity, Dr. Kampert recommends using guideline-based exercise prescriptions and a periodized approach to anti-obesity medication. The medication provides a jump start for people who are conditioned to a sedentary lifestyle and have lower exercise capacity.

“Anti-obesity medication phentermine is less expensive than semaglutide, about $11 per month, although the price can vary,” Dr. Kampert says. “However, it is effective for only about three months at a time. Individuals then need to be off the medication for several months to resensitize to it. Alternating phentermine with semaglutide enables continued weight loss at lower cost.”

Combining medication with exercise prescription

For the patient with obesity and knee osteoarthritis, Dr. Kampert first provided viscosupplementation injections to treat the knee pain. He also prescribed moderate to strenuous exercise more than 300 minutes per week (alternating swimming and land-based cardiorespiratory exercise) along with resistance training five to six days per week.

These lifestyle changes were augmented by sequential anti-obesity medications to help reduce the patient’s appetite. For 12 weeks, the patient took phentermine and lost 24 pounds. For the next 48 weeks, she took semaglutide and lost 97 pounds, followed by another 12 weeks of phentermine, during which she lost 27 more pounds.

Outcome

Over 72 weeks of treatment, the patient lost 148 pounds (50.6%) and reduced her BMI to 26.3. As a result, the patient’s risk of nonhome discharge after TKA decreased from 7.41% to 2.33%.

The total cost of anti-obesity medications was $16,431 — or 1% weight loss for $325 — a fraction of the cost had the patient taken only semaglutide for 72 weeks.

“This profound increase in value and the more significant weight loss compared to other studies are thanks to a more comprehensive approach involving lifestyle interventions,” Dr. Kampert says. “Additionally, the value of care was enhanced by reducing the cost of medication through a periodized approach to anti-obesity medication.”

Although she has been cleared for TKA, the patient has thus far declined surgical intervention and continues to manage her knee pain with viscosupplementation injections every six months and guideline-based exercise. She no longer has hypertension or needs hypertension medication.

Writing exercise prescriptions

Dr. Kampert recommends these practices for writing exercise prescriptions.

Physicians who need help writing guideline-based exercise prescriptions can collaborate with exercise professionals, he notes. Exercise professionals can advise on prescriptions, assess patients’ progress and update prescriptions to ensure continued improvement in cardiorespiratory fitness, muscular fitness and body composition.