Artikel
Patients with a mechanically aligned TKA that had a 1 mm or more over-resection of the medial femoral condyle relative to the pre-arthritic articular surface had worse 1-year outcome scores
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Autoren
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Alexander Nedopil
- Adventist Health Lodi Memorial, Julius-Maximilians-Universität Würzburg, University of California, Davis, Lodi, United States
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Dominik Rak
- Orthopädische Klinik, König-Ludwig-Haus, Orthopädisches Zentrum für Muskuloskelettale Forschung, Lehrstuhl für Orthopädie der Universität Würzburg, Würzburg, Germany
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Maximilian Rudert
- Orthopädische Klinik, König-Ludwig-Haus, Orthopädisches Zentrum für Muskuloskelettale Forschung, Lehrstuhl für Orthopädie der Universität Würzburg, Würzburg, Germany
| Veröffentlicht: | 23. Oktober 2023 |
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Gliederung
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Objectives: Mechanically aligned (MA) total knee arthroplasty (TKA) changes pre-arthritic distal and posterior femoral joint lines. This prospective study determined the proportion of patients with a distal medial (DM), posterior medial (PM), distal lateral (DL), and posterior lateral (PL) femoral resection that set the femoral component with a deviation relative to the pre-arthritic articular surface, and which deviations changed the 1-year FJS, OKS, and WOMAC.
Methods: Four academic TKA specialists each supervised 30 primary MA TKAs on consecutive patients. The ‘reference resection thickness’ that restored the pre-arthritic articular surface was the femoral resection thickness plus 2 mm for missing cartilage and 1 mm for bone loss from the saw cut. The reference resection thickness minus the 8.5 mm thickness of the femoral component's condyle de-termined whether an over-resection (+) or under-resection (-) occurred and quantified the femoral component’s deviation relative to the pre-arthritic articular surface.
Results: The analysis comprised 103 of the 120 patients that filled out the patient-reported outcome scores. There were no significant differences in the proportion of females to males, mean age, mean BMI, the proportion of varus, valgus, and patellofemoral deformities, and preoperative OKS and WOMAC scores between surgeons (Table 1 [Tab. 1]).
The number of patients analyzed and the 1-year me-dian FJS, OKS, and WOMAC were not significantly different between surgeons (Table 2 [Tab. 2]).
Hence, the study combined the data from the 103 patients for analysis. The surgeons over-resected 84% of the DM and PM femurs 1 mm or more. A 1 to 2.5 mm and 3 to 4.5 mm DM over-resection lowered the median FJS 35 and 39 points, the OKS 9 and 14 points, and increased the WOMAC 9 and 16 points relative to those with a -0.5 to 0.5 mm deviation (p<0.0001 to 0.0013). A 1 to 2.5 mm and 3 to 4.5 mm PM over-resection lowered the median FJS 34 and 46 points, OKS 7 and 12 points, and increased the WOMAC 8 and 19 points relative to those with a -0.5 to 0.5 mm deviation (p=0.0003 to 0.0046).
DL and PL over- and underresection did not affect the FJS, OKS, and WOMAC.
Figure 1 [Fig. 1]
Conclusion: Surgeons can reduce the risk of poor patient satisfaction and function at one year by using a caliper to verify that the DM and PM femoral resections set the femoral component to re-store the medial pre-arthritic articular surface.
