Background

Roentgen Stereophotogrammetric Analysis (RSA) represents nowadays an excellent solution for high-accuracy fixation measurement of UKAs. To date, to the best of our knowledge, no previous study has investigated long-term micromotions of a UKA using RSA. For this reason, the main purpose of the present study is to determine long-term implant fixation of 15 UKAs with all-poly tibial component using RSA at a mean 10-years follow-up. The secondary purpose was to investigate whether the progressive loss of implant's fixation correlates with a reduction of KSS scores.

INTRODUCTION

Osteochondral defects are still a challenge for the orthopaedic surgeon, since most of the current surgical techniques lead to fibrocartilage formation and poor subchondral regeneration, often associated to joint stiffness and/or pain.

Thinking of the ideal osteochondral graft from both the surgical an commercial point of view, it should be an off-the-shelf product; this is the research direction and the explanation for the new biomaterials recently proposed to repair osteochondral defect inducing an “in situ” cartilage regeneration starting from the time of the implantation into the defect site.

For the clinical pilot study we performed, a newly developed nanostructured biomimetic scaffold was used to treat chondral and osteochondral lesions of the knee; its safety and manageability, as much as the surgical procedure reproducibility and the clinical outcome, were evaluated in order to test its intrinsic potential without any cells colture aid.

Nowadays, initial fixation and relative movements of the tibial baseplate with respect to the bone are not a hot topic anymore. Most surgeons have already accepted cement fixation and don't aim for bone ingrowth anymore. This might change if the trend towards implants that offer always a deeper flexion persists. These implants tend to load the tibial baseplate more posteriorly during deep flexion potentially causing a higher risk of lift_off and thus loosening. The ideal concept pushing our team was the search for a design of either a stem or other fixation features able to hold the baseplate to the bone keeping the amount of bone that needs to be removed within acceptable limits.

The Profix tibial baseplate (Smith & Nephew) has a wide range of fixation techniques available. It can be cemented or used cementless and, in both cases, several stem designs are available. One of these is the so-called Omega stem. It has the advantage of being thin (in fact it is a stem and a chisel at the same time) but also stiff, withstanding bending loads due to its curvature in the transversal plane. It is also relatively short compared to other stems and it is thus bone-sparing and suitable for MIS.

INTRODUCTION

The menisci play a fundamental biomechanical role in the knee and also help in the maintaining of the articular homeostasis; thus, either a lesion or the complete absence of the menisci can invalidate the physiological function of the knee causing important damages, even at long term. Unfortunately, meniscal tears are often found during the ordinary orthopaedic practice while the regenerative potential of this kind of tissue is very low and limited to its peripheral-vascularized part; this is why the majority of these common arthroscopic findings are not reparable and often the surgeon is almost forced to perform a partial, subtotal or even total meniscectomy, regardless of the well-known consequences of this kind of surgery.