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.

The employment of biophysical therapy to accelerate the healing of tissues is by now a well-established practice in many orthopaedic situations, indicated mainly for osteogenesis and chondrogenesis. Assessments of the effects of biophysical stimuli on joint cartilage (CRES, Cartilage Repair & Elecromagnetic Stimulation) performed with pre-clinical studies and clinical studies (in operations to reconstruct LCA and microfractures) have shown how biophysical stimulation controls the microambience, and have suuplied the rationale for passing to an evaluation of the effects also in the case of joint replacement.

We launched a randomized prospective clinical study of 30 patients aged between 60 and 85 years, afflicted with gonarthrosis and undergoing operation for prosthesis. The randomization involved subdividing them into two homogeneous groups: the first with biophysical treatment with I-ONE therapy (Igea-Clinical Biophysics) (experimental group); the second not undergoing the biophysical treatment (control group). In the experimenal group, the I-ONE therapy was commenced at 3–7 days from the operation, administered for 4 hours per day and maintained for 60 days consecutively. The clinical evaluations were performed by compiling functional reports (swelling of the knee, Knee Score, SF-36 and VAS) in the pre-operative period and postoperatively at 1, 2, 6 and 12 months. The data processing was subjected to statistical evaluation by an independent observer using Student’s two-tail t test and the Generalized Linear Mixed Effects Model.

The preliminary results showed that at the baseline there are no differences between the groups either for the KNEE score, nor the VAS, or the SF-36. Already after 1 month the differences between the groups are statistically significant (p< 0.05 for KNEE score, p< 0.001 for swelling, p< 0.0001 for VAS and SF-36). At 2 months the differences between the groups are highly significant (p< 0.0001). The study entails a long-term evaluation with monitoring of the patients at one year from operation.

The results of this study supply the basis for clinical employment of biophysical treatment with I-ONE immediately following joint surgery, enabling inflammation to be controlled and increasing anabolic activity and protecting its microambience.

The osteoclastogenesis is regulated by a complex signaling system between the pro-apoptotic factors (Bax-Cyclin E2-Cdk2) and the tumor necrosis factor family (RANKL-RANK-OPG).

Extracorporeal Shock Waves Therapy (ESWT) have recently been used in orthopaedic treatments to induce bone repair, but their mechanisms of action are not sufficiently investigated. So we studied the effect of shock-waves on murine osteoblastic cells.

Osteoblast cultures were subjected to a single shock-wave with combinations of low energy intensities (0.05mJ/mm2) and 500 number of shocks (impulses), whereas control cells received no treatment. We valued the cell viability quantifying the expressions of Bax and Opg by PCR.

We found an immediate negative effect on cell viability, that occurs with an increase of Bax protein expression after 3 hours of treatment. After a longer time lapse a stimulatory effect on cell proliferation, as reflected by the increase of a G(1)-S phase marker, was observed. In fact, in the following 24, 48 and 72 hours after ESW treatment, we found a stronger association of Cyclin E2 and Cdk2, forming active cyclin E-Cdk2 kinase, compared to untreated cells at the same times.

We further explored the molecular mechanism for the ESW induction of osteogenesis: by Real Time PCR an enhancement of Runx2 mRNA, evident 48 hours after the treatment, was found. A link between physical ESW and Runx2 activation has been already demonstrated. ESW-induced

O2- production, followed by tyrosine kinase mediated ERK activation and Runx2 activation, resulted in osteogenic cell growth and maturation. Moreover, we analyzed the cytokines RANK-L and OPG osteoblast expression, involved in regulation of osteoclastogenesis. A decrease in RANK-L/OPG ratio was found, perhaps leading to a reduced osteoclastogenesis.

The Shock waves have a repair action on bone and it can been explained by the regulation on osteoclastogenesis by the apoptoic pathway of BAX and OPG.