Abstract
Objective:
Patient-specific or “custom” total knee replacements have been designed to fit the arthritic knee in primary total knee arthroplasty (TKA) better than “off-the-shelf” implants. Using computer technology, patient-specific cutting-blocks and custom-made implants are created to more accurately fit the contour of the knee and reproduce the anatomic J-curve with the hope of providing a better functional outcome.
Purpose:
This retrospective, matched-pair study evaluates manipulation under anesthesia (MUA) rates in cemented patient-specific cruciate-retaining (PSCR) TKA compared to that in both cemented posterior-stabilized (PS) and non-cemented cruciate-retaining rotating-platform (NC CR RP) TKA.
Materials and Methods:
From 2010 through November of 2012, 21 PSCR TKAs were performed in 19 patients. Using medical records from our patient database, these patients were matched for age, side, deformity, diagnosis, Charnley Class, and preoperative range of motion (ROM) with 42 PS TKAs performed during the same time period by the same surgeon using the same intra- and post-operative protocols. Additionally, 11 NC CR RP TKA were performed and evaluated based on the same criteria. Pre- and postoperative radiographs were performed using criteria as described by The Knee Society.
Results:
Preoperatively the custom CR RP TKA cohort had a larger average ROM compared to the PS TKA cohort (P-value = 0.006). Postoperatively, however, the custom CR RP TKA cohort overall was found to have a significantly decreased average ROM compared to both the PS and NC CR RP TKA cohorts (2.0°–110.6° P-value = 0.0002 and 2.4°–117.3° P-value = 0.0003, respectively). 6 of the 21 (28.6%) PSCR TKAs performed underwent MUA to improve postoperative ROM. One manipulation was unsuccessful and the patient is scheduled for revision for arthrofibrosis. No patients in either the matched PS group or the CR RP group underwent postoperative MUA. Clinical and radiographic analysis including pre-operative ROM, deformity, side, Charnley Class, posterior tibial slope angle, epicondylar axis and posterior condylar offsets provided no insight into the reason for this higher MUA rate in the PSCR knees.
Conclusion:
MUA rates in the patient-specific TKA group were significantly higher than that in the matched PS and NC CR RP groups. No correlations were found to clearly indicate the cause of the higher MUA rate among the PSCR knees. Early manipulation is recommended for stiffness with these custom devices.
Level of Evidence: Level III, Retrospective comparative study
Keywords: Patient-specific total knee, Manipulation, TKA
