Second Generation Patient Specific Total Knees Demonstrate a Higher Manipulation Rate Compared with “Off-the-shelf” Implants

Introduction. Patient specific total knee arthroplasty (TKA) theoreticallyprovides a more accurate fit to the native knee but mayhave difficulty achieving full range of motion (ROM) post-operatively.Post-operative ROM data were compared between patientswho underwent cemented patient-specific cruciate-retaining(PSCR) and standard cemented posterior-stabilized (SPS) TKAs. Methods. PSCR and SPS TKAs that were performed from January2014 to September 2015 by the same surgeon using the same postoperativeprotocols at two selected facilities were reviewed. Twoandsix-week post-operative ROM data were obtained and thenumber of patients with knee flexion less than 110° was recorded. Results. Twenty-one patients in the PSCR group and 57 patientsin the SPS group were included. The percentage of patientswith knee flexion less than 110° was similar in both groups preoperatively(10% vs 14%, p = 0.60) and two-week post-operatively(57% vs 68%, p = 0.35). However, at six-week post-operativelythere was significant difference (29% vs 7%, p = 0.01). Conclusions. These results provide evidence to alert orthopaedicsurgeons when using these patient specific implants versus conventionalTKA methods. Patients whose TKA was performed usingpatient specific cutting guides struggled to obtain 110° of kneeflexion. Close monitoring, aggressive physical therapy, and earlymanipulation are recommended when using patient specific cuttingguides and custom total knee implants. Further evaluation ina larger group of patients is warranted. KS J Med 2016;9(4):88-92.