Total knee arthroplasty (TKA) is an efficacious procedure for end-stage knee arthritis. Although TKA is cost-effective and has a high rate of success,1-6 TKAs fail and may require revision surgery. Failure mechanisms include periprosthetic fracture, aseptic loosening, wear, osteolysis, instability, and infection.7-9 In these cases, revision arthroplasty may be needed in order to restore function.
There has been a steady increase in the number of primary and revision TKAs performed in the United States.8,10,11 Revision rates are 4% at 5 years after index TKA and 8.9% at 9 years.12 However, surgical techniques and improved implants have led to improved outcomes after primary TKA, as evidenced by the reduction in revisions performed for polyethylene wear and osteolysis.13 Given the continuing need for revision TKAs (despite technical improvements13), evidence-based standard protocols that improve outcomes after revision TKA are necessary.
The Total Joint Replacement Perioperative Surgical Home (TJR-PSH) implemented and used by surgeons and anesthesiologists at our institution has shown that an evidence-based perioperative protocol can provide consistent and improved outcomes in primary TKA.14-16 TJR-PSH is a clinical care pathway that defines and standardizes preoperative, intraoperative, postoperative, and postdischarge management for patients who undergo elective primary total knee and total hip arthroplasty.14,15
Garson and colleagues14 and Chaurasia and colleagues15 found that patients who underwent primary TKA in a TJA-PSH had a predicted short length of stay (LOS): <3 days. About half were discharged to a location other than home, and 1.1% were readmitted within the first 30 days after surgery. There were no major complications and no mortalities. Conversely, as shown in different nationwide database analysis,17,18 mean LOS after primary unilateral TKA was 5.3 days, 8.2% of patients had procedure-related complications, 30-day readmission rate was 4.2%, and the in-hospital mortality rate was 0.3%. As with TJA-PSH, about half the patients were discharged to a place other than home.
We conducted a study to test the effect of the TJA-PSH clinical pathway on revision TKA patients. Early perioperative outcomes, such as LOS, readmission rate, and reoperation rate, are invaluable tools in measuring TKA outcomes and correlate with the dedicated orthopedic complication grading system proposed by the Knee Society.14,15,17,19 We hypothesized that the TJR-PSH clinical pathway would close the perioperative morbidity gap between primary and revision TKAs and yield equivalent perioperative outcomes.
Materials and Methods
In this study, which received Institutional Review Board approval, we performed a prospective cross-sectional analysis comparing the perioperative outcomes of patients who underwent primary TKA with those of patients who underwent revision TKA. Medical records and our institution’s data registry were queried for LOS, discharge disposition, readmission rates, and reoperation rates.
The study included all primary and revision TKAs performed at our institution since the inception of TJA-PSH. Unicompartmental knee arthroplasties and exchanges of a single component (patella, tibia, or femur) were excluded. We identified a total of 285 consecutive primary or revision TKAs, all performed by a single surgeon. Three cases lacked complete data and were excluded, leaving 282 cases: 235 primary and 50 revision TKAs (no simultaneous bilateral TKAs). The demographic data we collected included age, sex, body mass index (BMI), American Society of Anesthesiologists (ASA) score, calculated Charlson Comorbidity Index (CCI), LOS, and discharge disposition.
The same established perioperative surgical home clinical pathway was used to care for all patients, whether they underwent primary or revision TKA. The primary outcomes studied were LOS, discharge disposition (subacute nursing facility or home), 30-day orthopedic readmission, and return to operating room. All reoperations on the same knee were analyzed.
Statistical Analysis
Primary and revision TKAs were compared on LOS (with an independent-sample t test) and discharge disposition, 30-day readmissions, and reoperations (χ2 Fisher exact test). Multivariate regression analysis was performed with each primary outcome, using age, sex, BMI, ASA score, and CCI as covariates. Statistical significance was set at P ≤ .05. All analyses were performed with SPSS Version 16.0 (SPSS Inc.) and Microsoft Excel 2011 (Microsoft).
Results
Mean (SD) age was 66 (13.2) years for primary TKA patients and 62 (12.8) years for revision TKA patients. The cohort had more women (62.5%) than men (37.5%). There was no statistical difference in patient demographics with respect to age (P = .169) or BMI (P = .701) between the 2 groups. There was an even age distribution within each group and between the groups (Table).
