Acta chirurgiae orthopaedicae
et traumatologiae Čechoslovaca

Acta Chir Orthop Traumatol Cech. 2020; 87(2):75-81 | DOI: 10.55095/achot2020/012

Clinical Outcomes after Total Knee Replacement in Dependence on Femoral Component Rotation Relative to the Original Anatomy of Distal FemurOriginal papers

J. SOBEK^1,*, R. HART^1,2, M. KOMZÁK^1,3

¹ Ortopedicko-traumatologické oddělení, Nemocnice Znojmo

² Klinika traumatologie, Lékařská fakulta, Masarykova univerzita, Brno

³ Oddělení fyzioterapie, Katedra podpory zdraví, Fakulta sportovních studií, Masarykova univerzita, Brno

PURPOSE OF THE STUDY:
The number of patients who underwent total knee replacement is on an increase globally. According to the current literature, 10-30% of patients is dissatisfied with the outcome of surgery. The purpose of this study was to focus on preoperative planning of femoral components position relative to the original anatomy and to find out how it affects the satisfaction of patients after the surgery.

MATERIAL AND METHODS:
A total of 74 total knee replacements were examined at the authors' department one year after the surgery in order to determine the function of knee replacement. The patients underwent a preoperative and postoperative CT scan of the knee joint in order to determine the rotation of the dorsal line of femoral condyles relative to the transepicondylar line, the so-called condylar twist angle (CTA). The study did not explore the absolute value of CTA, but the difference between the preoperative and postoperative angle. The patients were divided into two groups. In Group 1 composed of 53 knees, the difference of the CTA was lower than 3°, Group 2 included the cases with the difference greater than 3°. After 1 year, the patients filled in the Knee Society Clinical Rating Score and WOMAC questionnaires. The statistical significance was evaluated with the use of the unpaired T-test.

RESULTS:
Group 1 where the original anatomy of the knee joint was respected, reported the mean value of Part 1 of the KSCRS of 83.5 points, the mean value of Part 2 of this questionnaire was 83.5 points. The mean WOMAC score was 86.4 and the mean VAS score was 2.6. In Group 2, with a difference in rotation as against the preoperative status of 3° or more, the mean value of Part 1 and Part 2 of the KSRCS was 72.4 points and 72.1 points, respectively, the mean WOMAC score was 75.5 points and the mean VAS score was 4.7. The comparison by the Student's t-test, in all the monitored values at the level of significance of p < 0.05 the patients' satisfaction and the implant's function depend on respecting the original anatomy of the distal femur.

DISCUSSION:
It is generally accepted that the internal rotation of the femoral component causes patellar hyperpression, thus reduces the satisfaction of patients. There are several ways how to determine the rotation of the femoral component. An error is inherent in all of them, inversely proportional to the surgeon's experience. The purpose of our study was to show that in case of appropriately selected preoperative planning the postoperative outcome and the patients' satisfaction can improve.

CONCLUSIONS:
Our study confirms that for the patient's satisfaction after total knee replacement it is fitting to perform preoperative planning regarding the rotation of the femoral component and to seek to maintain the original anatomy, even if the femoral component is implanted in slight internal rotation.

Keywords: rotation of the femoral component, total knee replacement, condylar twist angle, preoperative planning

Published: April 1, 2020  Show citation