The purpose of this study was to evaluate the accuracy of the sonication fluid cultures (SFC) for the diagnosis of prosthetic joint infection and compare it with frozen section and periprosthetic tissue cultures.

108 patients underwent revision or explantation procedure for any reason. Frozen sections of intraoperative specimen were analized and multiple periprosthetic samples (at least 5) were collected and cultured. All explanted prosthesis components were subject to sonication and cultured. All cultures were incubated for 14 days.

PJI was diagnosed in 52 patients (48%). Sonication achieved the highest sensivity with 95% and specificity of 98%. Frozen section showed low sensivity (44%) and specificity (80%) and periprosthetic tissue cultures showed sensivity of 75% and specificity of 98%.

Sonication fluid culture is a cheap, easy, accurate and sensitive diagnostic method and helps to detect about 30% more PJI compared to frozen section and 16% more compared to periprosthetic tissue cultures. It also detect about 25% more pathogens than periprosthetic tissue cultures

The clinical success and long-term outcomes of total knee arthroplasty (TKA) depend not only on the accuracy of femoral and tibial components positioning, but also on the restoration of a proper mechanical axis (MA). Coronal and rotational mal-alignment may affect significantly the final result of a knee replacement. Patient specific cutting guides and intra-operative Computer-Assisted Surgery (CAS) have recently been introduced as options to improve implant alignment during TKA. The purpose of this study was to compare the alignment accuracy and implant positioning of Patient Matched technique to CAS system in patients with primary TKA.

A cohort of 68 consecutive patients who underwent TKA was enrolled for this study: 34 patients received a TKA using CAS system while 34 patients received a TKA using a MRI-based Patient Matched system. Mechanical axis and kinematics were digitally measured pre- and post-operatively in all knees using the intra-operative navigation system but data were blinded for the operating surgeon in the Patient Matched group. A post-operative CT-scan evaluation was performed in all patients to analyse the prosthetic components alignment (coronal, sagittal and axial alignment according to Perth Protocol from CT-scan). CT-scan measurements were used as landmarks as this tool is considered the gold standard. MA, posterior tibial slope (PTS) and femoral component rotation (FCR) in CAS group were compared to data of Patient Matched group. All patients also underwent a clinical evaluation with Knee Society Score (KSS) and Knee injury and Osteoarthritis Outcome Score (KOOS) at 6 and 12 months of follow up.

KSS, KOOS and range of motion were comparable in the two groups after surgery. Operative time was significantly shorter in the Patient Matched group. No differences were found regarding complications rate.

Mean angles, respectively for CAS and Patient Matched groups, were the following: MA was 1,7° (SD 0,9°) vs 0.8° (SD 2.1°); PTS was 3.1° (SD 0.9°) vs 3.4° (SD 2.1°); FCR was 1.5° (SD 2.2°) vs 1.36° (DS 1.2°). The outcomes of the CT scan evaluation were the following: MA was 1.5° (SD 0.8°) vs 1.0° (DS 1.5°); PTS was 2.3° (SD 0.8°) vs 3.0° (SD 2.6°); FCR was 0.4° (SD 0.8°) vs 0.2° (SD 0.3°). MA was within 3° of neutral alignment in 94% of patients for CAS group and in 97% of knees for Patient Matched group.

After a short follow up, there weren't statistically significant differences between CAS and Patient Matched techniques as regards clinical and functional scores. Both the systems achieved the goal of neutral alignment within 3° of varus and valgus. We only observed greater precision for Patient Matched technique in optimizing femoral component rotation. Actually it is unpredictable if this difference may determine long term effects.

Patient Matched technique and CAS for TKA surgery will certainly continue to have an impact in the future. Studies are needed to define which technique is better, in terms of long term results, failure rate and cost-effectiveness.

Measurement of precision in positioning multiple autologous osteochondral transplantation in comparison to the conventional free hand technique.

The articular surfaces of 6 cadaveric condyles (medial – lateral) were used. The knee was referenced by a navigation system (Praxim). The pins carrying the navigation detectors were positioned to the femur and to the tibia. The grafts were taken from the donor side (measurement I) with the special instrument which carried the navigation detectors. The recipient site was prepared and the donor osteochondral grafts were forwarded to the articular surface (II). The same procedure took place without navigation. The articular surface congruity was measured with the probe (measurement III)

The angle of the recipient plug removal (measurement I) with the navigation technique was 3,27° (SD 2,05°; 0°–9°). The conventional technique showed 10,73° (SD 4,96°; 2°–17°). For the recipient plug placement (measurement II) under navigated control a mean angle of 3,6° (SD 1,96°; 1°–9°) was shown, the conventional technique showed results with a mean angle of 10,6° (SD 4,41°; 3°–17°). The mean depth (measurements III) under navigated control was 0,25mm (SD 0,19mm; 0mm–0,6mm). With conventional technique the mean depth was 0,55mm (SD 0,28mm; 0,2mm –1,1mm).

The application of navigation showed that complications like diverging of the grafts leading to breakage or loosening as well as depth mismatch which can lead to grafts sitting over or under the articular surface can be avoided providing better results in comparison to the free hand procedure

The chioce of the graft and its fixation in LCA reconstruction is basic for the outcome of the surgical procedure. Several solutions have been proposed; each of them had advantages and disavantages. The choice of the graft and the surgical technique is often due to surgeon’s opinion.

The goal of the fixation is stability which allowes incorporation of the graft in the bone tunnels. Bone-patellar tendon-bone graf has the advantage of bone to bone fixation which is impossible using tendon grafts. Femoral fixation techniques for hamstrings can be classified in: compression tecniques, expansion tecniques and suspension tecniques (cortical or canellous).

TTS (Top Traction System) is a new tecnique for femoral fixation using hamstrings. The fixation is achieved by a retrograde screw that allowes fixation to the antero-lateral cortex of the femur. A ring is fixed to the screw to allow tendons passing. The screw is sefl-threading, its lenght is 28 millimeters and its diameter is 6,5 millimeter; its pull-out strenght is 1350 N. The screw is built in titanium alloy and only one size.

Surgical technique is simple an reproducible and the instruments are easy to use. The positioning of the screw is fully guided by instruments that minimize errors.

This fixation device allowes further graft traction after tibial fixation without twisting hamstrings. Results after 5 years are good but we need long term follow-up for final opinion.