Valoración clínica y radiológica de las prótesis unicompartimentales de rodilla implantadas con técnica mínimamente invasiva

Abstract

Purpose To assess the radiological position and the short-term clinical outcome of a series of unicompartmental knee prostheses implanted through a small incision. Materials and methods Retrospective review of the first 44 arthroplasties of this kind performed in our Department with a minimum 1-year follow-up. The study includes an analysis of the relationship between the result obtained in terms of the American Knee Society score and the patients’ age, gender, body mass index, diagnosis, number of previous surgeries and 25 radiological variables recorded on the basis of anteroposterior, lateral and axial views. Any errors in the positioning of each of the components on the different planes were also determined. Results The results obtained are significantly poorer the higher the body mass index (r=−0.42; P=.01) and the higher the degree of posterior inclination of the tibial component (r=−0.34; P=.02); this difference is statistically significant from 8° (t=−2.15; P=.04) onwards. The greatest variability in terms of prosthetic placement is found in the degree of rotation of the tibial component on the axial plane and in the flexion-extension of the femoral component on the sagittal plane. Surgical expertise is crucial when it comes to sound prosthetic placement, with significantly fewer errors being committed by surgeons who perform the procedure habitually (t=2.06; P=.04). Conclusions Unicondylar knee replacement is an attractive yet technically demanding therapeutic alternative for unicompartmental pathology, which is associated to a mandatory learning curve. In addition to appropriate patient selection, correct implant placement is crucial to obtain a satisfactory end result.