Published 5/1/2009
Jennie McKee

Outpatient knee replacement requires ‘perfect execution’

Some problems, including readmission and ED visits, can occur

Total knee arthroplasty (TKA) and unicompartmental knee arthroplasty (UKA) are traditionally considered inpatient surgical procedures. But can recent advances—including minimally invasive techniques, improved perioperative anesthesia, and expedited rehabilitation protocols—enable them to be performed on an outpatient basis?

According to Richard A. Berger, MD, lead author of a study presented at the 2009 AAOS Annual Meeting, outpatient TKA and UKA can be performed, provided everything is “perfectly executed.” The study focused on the feasibility and perioperative complications of outpatient knee replacement.

Benefits of decreased hospital stays
Improved postoperative clinical pathways—including improved pain management protocols, early mobilization, careful monitoring, and early preventive intervention for the most common medical complications—have helped decrease the average length of hospital stay following TKA and UKA.

The potential benefits of a shorter hospital stay, according to Dr. Berger, include fewer complications, improved outcomes, and increased patient satisfaction. In addition, he said, considering that approximately 1 million U.S. patients were hospitalized for 4 to 5 days last year after undergoing joint replacement surgery, shorter hospital stays could have eliminated 3 million to 4 million hospital days.

“Think of how much money that could have saved our ailing medical system,” added Dr. Berger.

Dr. Berger and colleagues found that outpatient TKA and UKA were feasible in an unselected group of patients, but problems could require some patients to be readmitted to the hospital or to visit the emergency department (ED) within the first week after surgery.

He emphasized that “everything must be perfectly executed to perform outpatient total joint arthroplasty; any error or delay from any part of the team will result in the patient’s having to stay overnight.”

Prospective study
The study involved 111 patients (45 female; 66 male) who had primary knee arthroplasty (25 UKA; 86 TKA) between January 2006 and October 2006. All surgeries were performed by Dr. Berger and were completed by noon on the day of surgery.

Patients ranged in age from 48 years to 85 years; they had an average weight of 195.2 pounds, and Body Mass Index (BMI) ranged from 18.7 to 43.2. Preoperatively, 102 patients were diagnosed with osteoarthritis, 1 with osteonecrosis, 3 with rheumatoid arthritis, and 5 with posttraumatic injuries.

“All patients were enrolled in a comprehensive clinical pathway that encompassed the preoperative, intraoperative, and postoperative periods,” explained Dr. Berger. “Patients received preoperative teaching, regional anesthesia, pre-emptive oral analgesia, pre-emptive antiemetics, and a rapid rehabilitation protocol that included initiation of physical therapy within 5 to 6 hours after surgery.”

To be considered for home dis­charge, patients had to have stable vital signs, including heart rate, blood pressure, respiratory rate, and temperature during physical therapy exercises. Dr. Berger ex­plain­ed that patients also had to be able to tolerate a regular diet and maintain adequate pain control with oral pain medication. Patients who met all these criteria were given the option of discharge to home.

Low rates of hospitalization and readmission
Patients were followed for 3 months to record any postoperative complications and the clinical results of their procedures. Telephone and office visits resulted in 100 percent follow-up.

Among the patients in the study, 94 percent were discharged directly to home the day of surgery. The most common reason for delay in discharge was nausea that required additional treatment.

Of the seven patients who stayed in the hospital overnight, four remained hospitalized because of difficulty with pain control. Each of those patients had undergone TKA that was completed late in the morning (between 11 a.m. and noon).

“Late completion of their surgery did not allow adequate time for the pathway and our nurse clinician to adjust the pain regimen to achieve a same-day discharge,” said Dr. Berger.

Four patients (3.6 percent), all of whom had undergone TKA, were readmitted (two for symptomatic anemia, one for gastrointestinal bleeding, and one for deep venous thrombosis). Another patient who had undergone TKA visited the ED within the first week after surgery for uncontrolled nausea; the patient was not readmitted to the hospital. No deaths, cardiac events, or pulmonary complications occurred.

Analysis found no statistically significant differences between patients who required an overnight stay and those treated as an outpatient with regard to average age, body weight, BMI, or medical comorbidities.

Dr. Berger noted that the findings of this study contradict the results of other studies that suggest patients older than 70 years as well as patients with a BMI greater than 40 require a longer length of stay after TKA.

“Notwithstanding these other reports and our own preconceived biases,” said Dr. Berger, “the primary factor that prevented same-day discharge in our patient group was TKA completed late in the morning and the difficulties in completing the pathway due to that late time. BMI, medical comorbidities, and age were related to postoperative hospital readmissions.”

Implications—and caveats
According to Dr. Berger, the low readmission rates may have been avoided completely if patients had a standard postoperative hospital stay of 3 to 5 days. He noted that all acute hospital readmissions were in patients who had undergone TKA.

“This result suggests two things: first, in our patient population, TKA patients are at higher risk for early postoperative readmission than are UKA patients,” he said. “Second, the selection criteria we used in previous reports for outpatient knee arthroplasty candidates successfully screened out those patients who were at risk for early postoperative readmissions.”

From these results, Dr. Berger concluded that more stringent screening criteria should be used when selecting outpatient TKA candidates, but may not be necessary for outpatient UKA candidates.

Lastly, Dr. Berger issued a word of caution to those who might consider adopting outpatient knee arthroplasty.

“We have been perfecting same-day discharge for hips since 2001 and for knees since 2003,” he noted. “Our excellent discharge rate of 94 percent in this series of unselected patients may suggest that even patients with multiple medical comorbidities, high BMIs, and increased age can be discharged home the day of surgery; however, this high percentage of same-day discharge may simply reflect the expertise developed by our team in remedying problems that inevitably arise in the perioperative period.”

Dr. Berger recommended that those who wish to begin performing same-day discharges after knee arthroplasty procedures should initially aim to reduce the length of stay in a large cohort of patients from 3 or 4 days to 2 days.

“Once this has been successfully implemented, we then recommend the careful selection and intense monitoring of healthy patients for knee arthroplasty with a 1-day hospitalization,” he said. “Only when you are comfortable with next-day discharge should same-day discharge be attempted with healthy patients.”

Dr. Berger’s coauthors included Sharat K. Kusuma, MD; Sheila Sanders, RN; Elizabeth S. Thill, RN; Scott M. Sporer, MD; and Craig J. Della Valle, MD.

Dr. Berger reported ties to Biomet, Zimmer, TissueLink, Wright Medical Technology, Inc., and Smith & Nephew. Co-authors included Sharat K. Kusuma, MD; Sheila Sanders, RN; and Elizabeth S. Thill, RN, all of whom reported no conflicts. Additional co-authors include Scott M. Sporer, MD, who reported ties to Zimmer; and Craig J. Della Valle, MD, who reported ties to Angiotech, Zimmer, Biomet, Kinamed, Smith & Nephew, and Stryker.

Jennie McKee is a staff writer for AAOS Now. She can be reached at mckee@aaos.org