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Published on: May 5, 2023
The Effect of the Design of Polyethylene Inserts in Total Knee Arthroplasty on Patient Reported Outcomes
Bhavana Gunda1, Leah Goldberg, Angie Alban
1From the Bone and Joint Institute, Hartford Hospital, Hartford, CT (Ms. Gunda, Ms. Goldberg, Ms. Alban, Dr. Strecker, McCracken, Dr. Carangelo, and Dr. Witmer); the University of Connecticut Medical School, Farmington, CT (Ms. Gunda); and the Orthopedic Associates of Hartford, Hartford, CT (Dr. Carangelo and Dr. Witmer).
Introduction:
Several types of polyethylene liners have been developed to address the specific needs of patients' anatomy within total knee arthroplasty (TKA). In modern TKA, the posterior-stabilized (PS) and the cruciate-retaining (CR) designs are the most common, with the medial congruent (MC) design becoming more popular. The MC total knee arthroplasty has a posterior dwell point allowing for more flexion. The purpose of this study was to determine differences in patient-reported outcomes (PROMs) or postoperative outcomes between these three TKAs.
Methods:
Patients who underwent a primary, elective, unilateral TKA between June 2021 and July 2023 were identified. Demographics and perioperative and postoperative outcomes were extracted from the medical record. PROMs from 624 patients were obtained through a digital engagement platform. A P value ≤0.05 was considered statistically significant.
Results:
Patients were subdivided into three groups; 111 PS-TKA, 278 CR-TKA, and 235 MC-TKAs. Most implants were Zimmer (71.5%) and were cemented (92.9%). Patients in the CR group were predominantly male (P = 0.003) and had a lower body mass index (P < 0.001). No differences were seen in Knee Injury and Osteoarthritis Outcome Score for Joint Replacement scores at any time point (preoperative: P = 0.073; 12 weeks: P = 0.144; 6 months: P = 0.666; 1 year: P = 0.622). A similar percentage of patients met the minimal clinically important difference (P = 0.480), and Forgotten Joint Scores were equivalent (P = 0.930). Patient physical therapy parameters (Timed Up and Go test [P = 0.779] and ambulation distance [P = 0.103]), inpatient pain levels (at rest: P = 0.101, with activity: P = 0.052), or morphine milligram equivalents dosed (P = 0.608) were comparable. No differences were seen in 30-day complications.
Conclusion:
This study fails to demonstrate a difference in PROMs, functional parameters, or complications between the PS-TKAs, CR-TKAs, and MC-TKAs. All three constructs perform similarly in the immediate postoperative period. Because equivalent outcomes occur with each polyethylene, implant choice should be left to physician preference.
