Varus or valgus positioning of the tibial component of a unicompartmental fixed-bearing knee arthroplasty does not increase wear.
Knee Surg Sports Traumatol Arthrosc
; 28(9): 3016-3021, 2020 Sep.
Article
em En
| MEDLINE
| ID: mdl-31690992
ABSTRACT
PURPOSE:
Higher revision rates were shown in varus- or valgus-positioned tibias in unicompartmental knee arthroplasty (UKA), but more than 15% of UKA prostheses are implanted with more than 5° of varus or valgus. This study aimed to analyze the wear rate in UKA when implanting the tibial component in either varus or valgus position versus a neutral placement at 90° to the tibial anatomical axis. The study hypothesized that a 5° varus or valgus positioning of the tibial plateau will generate less wear compared to a neutral alignment.METHODS:
Wear was experimentally analyzed on a medial anatomical fixed-bearing unicompartmental knee prosthesis (Univation, Aesculap, Germany) in vitro with a customized, four-station, servohydraulic knee wear simulator, reproducing the walking cycle. The forces, loading and range of motion were applied as specified in the ISO 14243-12002, 5 million cycles were analyzed. The tibial components of the medial prostheses were inserted in a neutral position, with 5° varus, and 5° valgus (n = 3, each group).RESULTS:
The wear rate decreased significantly with a 5° varus positioning (6.30 ± 1.38 mg/million cycles) and a 5° valgus positioning (4.96 ± 2.47 mg/million cycles) compared to the neutral position (12.16 ± 1.26 mg/million cycles) (p < 0.01 for the varus and the valgus position). The wear area on the inlay was slightly reduced in the varus and valgus group.CONCLUSION:
A varus or valgus "malpositioning" up to 5° will not lead to an increased wear. Wear was even less because of the reduced articulating contact area between the inlay and the femur. A slight varus positioning of the tibial component (parallel to the anatomical joint line) positioning can be advocated from a point of wear. LEVEL OF EVIDENCE Experimental study.Palavras-chave
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Teste de Materiais
/
Falha de Prótese
/
Ajuste de Prótese
/
Artroplastia do Joelho
/
Prótese do Joelho
Limite:
Humans
Idioma:
En
Revista:
Knee Surg Sports Traumatol Arthrosc
Assunto da revista:
MEDICINA ESPORTIVA
/
TRAUMATOLOGIA
Ano de publicação:
2020
Tipo de documento:
Article
País de afiliação:
Alemanha