Alpha Lipoic Acid (L.A.) is an effective natural antioxidant discovered in the human body in 1951 from L.J. Reed and I.C. Gunslaus from liver. It is inside broccoli, spinach and red meats, especially liver and spleen. Actually it is largely used as antioxidant in antiaging products according to the low toxicity level of the product.

The present study take into consideration the possibility to reduce oxidation of medical irradiated UHMWPE GUR 1050, mixing together polyethylene powder and Alpha Lipoic Acid powder.

The study is composed of two parts.

Part 1 Thermostability of alpha lipoic acid during polyethylene fusion

Part 2 detection of oxygen level in artificially aged irradiated polyethylene

Solid pieces were made with Gur 1050 powder (Ticona Inc., Bayport, Tex, USA) and mixed with Alpha Lipoic Acid (Talamonti, Italy, Stock 1050919074) 0, 1% and gamma ray irradiated with 30 kGy (Isomedix, Northborough, MA).

An oven (80° Celsius) was used to produce an aging effect for 35 days in the doped and control samples (Conventional not doped polyethylene). This process simulate an aging effect of 10 years into the human body.

THERMAL STABILITY: a Fourier Transfer Infra Red (FTIR) test was made in pieces molded in a cell at 150° and 200°Celsius and pressure of 200 MPa comparing to the UHMWPE powder mixed with alpha lipoic acid. The presence of Alpha Lipoic Acid in the polyethylene was found at any depth in the manufacts.

figure 1: A Pure Lipoic Acid. B Lipoic Acid + UHMWPE melted 150° C. Lipoic Acid + UHMWPE melted 200° C° (A And B spectra subtracted UHMWPE)

OXIDATION: After 5 weeks at 80° Celsius in a oven (ASTM standard F-2003-02)A FOURIER TRANSFER INFRA RED TEST (FTIR) was made in the superficial layer and deeper on the undersurface of doped 0.1% and conventional UHMWPE.

The antioxidation limit is defined as the ratio of the area under 1740 cm/−1 carbonyl and 1370 cm/−1 Methylene absorbance peaks.

In conventional UHMWPE oxidation is detected on the surface and decreases in the deeper layers down to zero under 1500 Micron Fig 2.

figure 2 Pure polyethylene: A Surface, B 1500 Micron, C 3000 Micron

In the doped UHMWPE, FTIR demonstrate a very low oxidation limit on the surface and at any depth, comparing to conventional UHMWPE Fig 3.

figure 3 Doped UHMWPE A surface, B 700 micron deept, C 1700 micron deept

The examples show that Lipoic Acid is effective as antioxidant in irradiated UHMWPE and it is stable with respect to thermal treatment.

Introduction: Mechanical factors are thought to be one of the main reasons in determining tunnel enlargement after ACL reconstruction with hamstrings. The purpose of this prospective study was to evaluate how the different techniques may affect the bone tunnel enlargement.

Material and Method: Forty-five consecutive patients undergoing ACL reconstruction with the use of autologous doubled semitendinosus and gracilis tendons entered this study. They were randomly assigned to enter group A (In-Out technique, with cortical fixation and Interference screw) and group B (Out-In technique, metal cortical fixation on the femour and tibia). At a mean follow-up of 10 months, all the patients underwent clinical evaluation and a CT scan exam to evaluate the post-operative diameters of both femoral and tibial tunnels.

Results: The mean femoral tunnel diameter increased significantly from 9.05±0.3 mm (post op) to 10.01±2.3 mm (follow-up) in group A and from 9.04±0.8 mm to 9.3±1,12 mm in group B. The mean tibial tunnel diameter increased significantly from 9.03±0.04 mm to 10,68±2.5 mm in group A and from 9.04±0.03 mm to 10.±0,78 mm in group B. The mean increase in both femoral and tunnel diameters observed in group A was significantly higher than that observed in group B (p< 0.05). Stability evaluated with kt 1000 don’t significantly differ in the two groups

Conclusion: The results of this study suggest that different angular orientation techniques and different hardware devices may affect tunnel enlargement after hamstrings reconstruction. The reason can be reached from the different stiffness of the devices and their backlashes on the tunnels walls.

Septic arthritis after arthroscopic anterior cruciate ligament (ACL) reconstruction is a rare complication. In the literature, several different managements have been proposed.

A total of 1232 ACL reconstruction procedures were performed from January 2001 and December 2008. Twelve patients (0.97%) had a post-operative infection. The average age at trauma was 24 years (range:16–43). Treatment included continuous irrigation of the knee (4 hour/day for 2 days) and parenteral and oral antibiotics subsequently for a mean of 7 weeks (range:4–12 weeks). The average time at follow-up was 38 months (range 6–54 months). Follow-up included International Knee Documentation Committee (IKDC) forms, radiographs, the Tegner and Lysholm scores and KT-1000 arthrometric evaluation.

In all cases treatment of infection was successful. In no cases graft or hardware removal was needed. At final examination pivot shift was negative in 10/12 patients and 1+ in 2/12 patients. In all cases the Lachman was negative. The mean postoperative Tegner score was 7.2 (range 5–9), the mean Lysholm score was 98.3 (range 69–100). 10/12 patients were graded as Group A and 2/12 patients as group B using the IKDC. The mean postoperative manual maximum KT-1000 side to side difference was 2.3 (range1–4), with 10 patients between 0 and 3 mm and 2 between 3 and 5 mm. No significative bone tunnel enlargement was found.

The described treatment gives reliable results. There were no recurrences of septic arthritis or bone infection. No further surgeries were required. The graft can be retained during treatment of septic arthritis after ACL reconstruction.

Introduction: In the last few years minimally invasive surgery in hip replacement is becoming more popular among orthopaedic surgeons because of less morbidity and faster rehabilitation. However several complications have been reported expecially in the so called “learning curve” (first twenty cases). The purpose of this study is to evaluate the learning curve of three different minimally invasive approaches.

Methods and Materials: In this study three different surgical approaches of THA were evaluated: lateral mini incision (GroupA), minimally invasive anterior approach (GroupB) and minimally invasive antero lateral approach (GroupC). The first twenty cases of each surgical approach were selected and compared with a control group (GroupD) of 149 total hip replacement operated using a lateral standard approach (> 12 cm) in the same period by the same experienced surgeon.

In all cases a specialized dedicated surgical instrumentation was used. Inclusion criteria to enter the study group (A-B-C Groups) were:BMI< 30, diagnosis of primary osteoarthritis, age< 75 years.

Following parameters were evaluated: intra and post operative complications, total blood loss, time of surgery, component placement, length of hospital stay and functional outcomes (HHS, WOMAC) at six weeks.

Results: No dislocations, infections and early aseptic loosening were detected in groups A, B and C. No significant differences were detected regarding the length of hospital stay in all groups. In group B the time of surgery was significantly higher than in group D. The total blood loss of group A, B and C was statistically lower than group D. Clinical outcomes at six weeks in groups B and C were significantly better that in group A and D. The following complications were detected:

Group A: two sciatic nerve palsy (one transient and one permanent), one greater trochanter fracture, one femoral stem malposition.

Group B: one greater trochanter fracture, one proximal femoral fracture, one rupture of tensor fasciae latae, two haematomas.

Group C: no complications were detected.

In control group D (149 patients) the following complications were observed: one proximal femoral fracture, one case of cup malposition and one infection.

Conclusions: The main advantages of all MIS approaches seem to be the reduced total blood loss, even in the learning curve. However during learning curve the minimally invasive approaches seem to have a higher rate of complications than the standard procedures even in selected patients. In muscle sparing approaches (anterior and antero lateral) the early functional outcomes are better than other approaches (standard and mini incision). Among the evaluated minimally invasive procedures, the antero lateral approach seems to be safer and less demanding than others.

Polyethylene wear is the most important risk factor affecting the durability of total knee arthroplasty. We developed a new method of measuring wear of the tibial polyethylene insert in total knee arthroplasty (TKA) on standard standing radiographs.

Methods: We developed a new method of measuring the shortest distance between the femoral component and the tibial metal tray taking its 3-D position into consideration. The accuracy of the method was examined in 3 conditions. An in vitro examintion measured the thickness of the polyethylene on radiographs of a new PFC prosthesis set on a table. The radiographs were taken from various directions. An in vivo examination measured the polyethylene thickness on patient discharge radiographs of 78 knees. These measurements were compared with known thicknesses of the used inserts. In the third study, wear of the tibial polyethylene insert was measured retrospectively in a series of 84 PFC TKAs with follow-up of 2 to 10 years (6.6 years on average).

Results: The average measurement error was 0.05 mm (SD 0.09 mm) in the in vitro study and 0.14 mm (SD 0.17 mm) in the in vivo study using discharge radiographs. In the series of 84 PFC TKAs, impending failure occurred in 7 knees, 4 of which were revised. Radiographically measured wear of the tibial insert was significantly greater in these failed TKAs than in the other TKAs. The radiographic measurements were well correlated with 3-D measurements of 4 retrieved inserts.

Discussion: Although the radiographic measurement of the tibial insert in TKA was less accurate than that of the socket in THA, it is useful enough to identify TKAs at risk of failure. When the radiographic wear exceeded 1mm, there was a significantly increased probability of impending failure or need for revision.