Similar 20-year survivorship for single and bilateral total knee arthroplasty

Long-term follow-up after total knee arthroplasty (TKA) is crucial to providing survivorship updates on available TKA implants to guide patient expectations when undergoing TKA. The purpose of this study was to compare implant survivorship between patients undergoing primary single, simultaneous bilateral, and staged bilateral TKA with 15-year minimum follow-up.

This retrospective study included 826 patients (n = 1089) who underwent primary single (n = 454), simultaneous bilateral (n = 266), or staged bilateral (n = 369) TKA using a single TKA system by a single surgeon from 1991-2005 with 15-year minimum follow-up. Demographics, clinical variables, and surgical outcomes were collected and compared using Student's t-test, chi-squared tests, or Kaplan-Meier analyses. Reoperation was defined as all surgeries performed on the knee after the index procedure; revision TKA was defined as complete implant exchange. p < 0.05 significant.

Patients in the staged TKA cohort were younger (65.4 years = staged, 67.8 = simultaneous, 67.1 = single, p < 0.019). Women were less likely to receive simultaneous TKAs (22 %vs.29%, p < 0.001). Postoperative range of motion was similar (116.8° = simultaneous, 114.9° = staged, 114.8° = single, p = 0.11). Overall 15-year implant survival based on revision TKA was similar (97.7% = simultaneous, 97.2% = staged, 96.7% = single, p = 0.45). The estimated 15-year reoperation rate was 7.0% (95% CI, 5.5-8.7%). Reoperations were secondary to infection (35.5%), implant wear (26.3%), arthrofibrosis (18.4%), traumatic injuries (10.5%), pain (6.6%), pathologic lesion (1.3%), and avascular necrosis (1.3%).

This study demonstrated a high implant survival rate of 95-97% at 20-years after primary single, staged bilateral and simultaneous bilateral TKA. Furthermore, simultaneous bilateral TKAs exhibited similar range of motion, implant survival, and rates of reoperation to staged bilateral and single TKA.