Revision of partial knee to total knee arthroplasty with use of patient-specific instruments results in acceptable femoral rotation.
Knee Surg Sports Traumatol Arthrosc 2018;
26:1656-1661. [PMID:
28785788 DOI:
10.1007/s00167-017-4674-8]
[Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Accepted: 08/02/2017] [Indexed: 01/27/2023]
Abstract
PURPOSE
Patient-specific instruments (PSI) were initially developed for the alignment of both total knee- (TKA) and partial knee arthroplasty (PKA). We hypothesize that CT-based PSI for PKA-to-TKA revision surgery can restore biomechanical limb alignment and prosthetic component positioning in vivo as calculated pre-operatively, resulting in a limited percentages of outliers.
METHODS
An imaging analysis was performed using CT-based 3D measurement methods based on a pre- and post-revision CT scan. Imaging data were gathered on 10 patients who were operated for PKA-to-TKA revision with the use of PSI based on CT imaging. The planned femur and tibia component position in vivo were compared with the pre-revision planned component position. Outliers were defined as deviations >3.0° from pre-revision planned position for the individual implant components. Adjustments (e.g. resection level and implant size) during surgery were recorded.
RESULTS
The HKA axis was restored accurately in all patients with a mean post-operative HKA axis of 178.1° (1.4°). Five femoral (2 varus, 2 internal rotation and 1 extension) and 14 tibial guides (2 varus, 6 anterior slope, 3 internal rotation and 3 external rotation) on a total of 60 outcome measures were identified as outliers. During surgery, an intraoperative tibial resection of 2 mm extra was performed in three patients. In 80 and 70% for, respectively, the femur and tibia, the surgeon-planned size was implanted during surgery. All patient-specific guides fitted well in all patients. No intraoperative or post-operative complications related to surgery were registered.
CONCLUSIONS
This study introduced a unique new concept regarding PSI, PKA-to-TKA revision surgery. Based on the results, we were unable to fully confirm our hypothesis. PSI as a "new" tool for PKA-to-TKA revision surgery appears to be an accurate tool for the alignment of the TKA femur component. The tibial guide seems more susceptible to errors, resulting in a substantial percentage of outliers.
LEVEL OF EVIDENCE
Prospective cohort study, Level II.
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