Bearing thickness of unicompartmental knee arthroplasty is a reliable predictor of tibial bone loss during revision to total knee arthroplasty - 25/04/20
, Alberto Grassi, Giuseppe Agrò, Sergio Cialdella, Cosimo Vasco, Maria Pia Neri, Ilaria Cucurnia, Stefano Zaffagnini
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Abstract |
Background |
Bone defects during revision procedures for failed UKA represent a challenge even for the most experienced surgeons; therefore, an accurate preoperative planning remains essential to prevent dramatic scenarios in the surgical theatre.
Hypothesis |
Our hypothesis is that bearing thickness used in original UKA represents a reliable predictor of severe tibial bone loss, requiring a metallic augment or constrained implant, during revision to TKA.
Patients and methods |
Forty-two patients who underwent a total knee arthroplasty from failed UKA were identified from our institutional database and evaluated clinically using the Knee Society Score (KSS). A multivariate logistic regression analysis was performed using the presence of tibial augments or the need of varus-valgus constrained (VVC) prosthesis as depend variables, and patients’ gender, age at revision procedure, side (medial or lateral), UKA tibial tray (all-polyethylene or metal back), bearing thickness (composite thicknesses of the metal-backed tray and insert or all-polyethylene tibial component ≤8mm or more than 8mm) and cause of failed UKA as independent variables.
Results |
A posterior-stabilized prosthesis was used in 27 cases (64.3%). An augment was necessary in 12 patients (28.6%). Initial bearing thickness greater than 8mm was associated with greater likelihood of a VVC implant (OR=11.78, 95% CI, 1.6583 to 83.6484, p=0.0137) and a tibial augment (OR=9.59, 95% CI, 1.327 to 69.395, p=0.0251). Tibial tray design, patients’ gender or age during revision surgery, side or cause of failure were not associated to increased risk of augmentation or constrained implants.
Discussion |
Surgeons should be aware of the particular challenges that the conversion of a UKA to a TKA presents and be prepared to address them intraoperatively, with particular care to proper bone loss manage. Satisfying results can be achieved at mid-to-long term follow-up, if these procedures are planned accurately, and a precise analysis of failed UKA components, in particular bearing thickness, represents a helpful support in this context.
Level of evidence |
IV, retrospective case series.
Le texte complet de cet article est disponible en PDF.Keywords : Unicompartmental knee arthroplasty, UKA, Revision, Bone loss, Augmentation
Plan
Vol 106 - N° 3
P. 429-434 - mai 2020 Retour au numéro
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