Multi-walled carbon nanotube induced frustrated phagocytosis, cytotoxicity and pro-inflammatory conditions in macrophages are length dependent and greater than that of asbestos.

The potential toxicity of carbon nanotubes (CNTs) has been compared to pathogenic fibres such as asbestos. It is important to test this hypothesis to ascertain safe methods for CNT production, handling and disposal. In this study aspects reported to contribute to CNT toxicity were assessed: length, aspect ratio, iron content and crystallinity; with responses compared to industrially produced MWCNTs and toxicologically relevant materials such as asbestos. The impacts of these particles on a range of macrophage models in vitro were assessed due to the key role of macrophages in particle clearance and particle/fibre-induced disease. Industrially produced and long MWCNTs were cytotoxic to cells, and were potent in inducing pro-inflammatory and pro-fibrotic immune responses. Short CNTs did not induce any cytotoxicity. Frustrated phagocytosis was most evident in response to long CNTs, as was respiratory burst and reduction in phagocytic ability. Short CNTs, metal content and crystallinity had less or no influence on these endpoints, suggesting that many responses were fibre-length dependent. This study demonstrates that CNTs are potentially pathogenic, as they were routinely found to induce detrimental responses in macrophages greater than those induced by asbestos at the same mass-based dose.

Tunnel communication and increased graft signal intensity on magnetic resonance imaging of double-bundle anterior cruciate ligament reconstruction.

PURPOSE: This study aimed to evaluate the association between magnetic resonance imaging (MRI) findings of tunnel communication and increased graft signal intensity (SI) and clinical evaluation of knee stability and outcome after double-bundle (DB) anterior cruciate ligament (ACL) reconstruction. METHODS: Fifty-nine patients were evaluated with 1.5 T MRI and with clinical evaluation 2 years after DB ACL reconstruction. The MRI finding of tunnel communication was defined as the absence of a bony bridge between the anteromedial (AM) and posterolateral (PL) tunnels. The SI of the intra-articular portion of both grafts was analyzed on proton-density (PD)-weighted and T2-weighted images and graded on a scale, with I being a normal SI similar to that of the posterior cruciate ligament, II being > 50% of the graft having a normal SI, and III being < 50% of the graft having a normal SI. The clinical evaluation of knee stability and function included KT-1,000 arthrometric side-to-side difference, pivot shift test, and International Knee Documentation Committee (IKDC) and Lysholm knee evaluation scores. The association between the MRI findings and the clinical findings was calculated using the Fisher exact test and the 2-tailed t test. RESULTS: Tunnel communication was seen in the femur in 10% of patients and in the tibia in 27% of patients. Increased graft SI was seen in 15% of the AM grafts and 59% of the PL grafts. No statistically significant association (P < .05) between the MRI findings of tunnel communication or increased graft SI and knee laxity was found. CONCLUSIONS: The MRI findings of tunnel communication or increased graft SI were not associated with knee laxity 2 years after DB ACL reconstruction. Tibial tunnel communication was associated with increased range of movement with flexion, and increased AM graft SI was associated with reduced range of flexion in the knee. LEVEL OF EVIDENCE: Level IV, therapeutic case series.

Effect of tunnel placements on clinical and magnetic resonance imaging findings 2 years after anterior cruciate ligament reconstruction using the double-bundle technique.

PURPOSE: The purpose of the study reported here was to find out if the clinical and magnetic resonance imaging (MRI) findings of a reconstructed anterior cruciate ligament (ACL) have an association. Our hypothesis, which was based on the different functions of the ACL bundles, was that the visibility of the anteromedial graft would have an impact on anteroposterior stability, and the visibility of the posterolateral graft on rotational stability of the knee. METHODS: This study is a level II, prospective clinical and MRI study (NCT02000258). The study involved 75 patients. One experienced orthopedic surgeon performed all double-bundle ACL reconstructions. Two independent examiners made the clinical examinations at 2-year follow-up: clinical examination of the knee; KT-1000, International Knee Documentation Committee and Lysholm knee evaluation scores; and International Knee Documentation Committee functional score. The MRI evaluations were made by two musculoskeletal radiologists separately, and the means of these measurements were used. RESULTS: We found that the location of the graft in the tibia had an impact on the MRI visibility of the graft at 2-year follow-up. There were significantly more partially or totally invisible grafts if the insertion of the graft was more anterior in the tibia. No association was found between the clinical results and the graft locations. CONCLUSION: Anterior graft location in the tibia can cause graft invisibility in the MRI 2 years after ACL reconstruction, but this has no effect on the clinical recovery of the patient.

Comparison of tunnel placements and clinical results of single-bundle anterior cruciate ligament reconstruction before and after starting the use of double-bundle technique.

PURPOSE: To investigate whether the locations of the grafts in single-bundle (SB) anterior cruciate ligament (ACL) reconstruction have changed to more anatomical as the double-bundle (DB) method has become more familiar. METHODS: Operation using anteromedial (not transtibial) portal and freehand technique [Group A (N = 25) in 2003, Group B (N = 25) in 2007]. The evaluation methods preoperatively and at the 2-year follow-up (two blinded examiners): clinical examination, stability measurement (KT-1000 arthrometer), the International Knee Documentation Committee (IKDC), and the Lysholm knee scores. A musculoskeletal radiologist made tunnel measurements from the magnetic resonance imaging (MRI). RESULTS: The average tunnel placement in the femoral side: from Blumensaat's line 27 % (Group A) and 26 % (Group B), from the posterior edge of the femur 32 % (Group A) and 29 % (Group B). The average tunnel placement in the tibial side: from the anterior edge 45 % (Group A) and 45 % (Group B), from the lateral side 57 % (Group A) and 54 % (Group B) (P = 0.024). Graft failures ending up to revision ACL surgery: 4 (Group A) and 0 (Group B) (P = 0.045). Operation time reduced 19 min (P = 0.001). CONCLUSION: Tunnel placement at the femoral side was already very low (anatomical) in patients operated in 2003. No significant difference was found when comparing to the patients operated in 2007. There were significantly more graft failures in the Group A, suggesting that the use of the DB method in ACL surgery in 2007 may have also improved the technique and results of the SB ACL reconstruction. LEVEL OF EVIDENCE: Prospective comparative study, Level II.

Double-bundle versus single-bundle anterior cruciate ligament reconstruction: randomized clinical and magnetic resonance imaging study with 2-year follow-up.

BACKGROUND: One aspect of the debate over the reconstruction of the anterior cruciate ligament is whether it should be carried out with the single-bundle or double-bundle technique. HYPOTHESIS: The double-bundle technique results in fewer graft failures than the single-bundle technique in anterior cruciate ligament reconstruction. STUDY DESIGN: Randomized controlled trial; Level of evidence, 1. METHODS: A total of 153 patients were prospectively randomized into 2 groups of anterior cruciate ligament reconstruction with hamstring autografts using aperture interference screw fixation: single-bundle technique (SB group, n = 78) and double-bundle technique (DB group, n = 75). The evaluation methods were clinical examination, KT-1000 arthrometric measurement, the International Knee Documentation Committee (IKDC) and the Lysholm knee scores, and magnetic resonance imaging (MRI) evaluation. All of the operations were performed by 1 experienced orthopaedic surgeon, and all clinical assessments were made by 2 blinded and independent examiners. A musculoskeletal radiologist blinded to the clinical data made the MRI interpretation. RESULTS: There were no differences between the study groups preoperatively. Ninety percent of patients (n = 138) were available at a minimum 2-year follow-up (range, 24-37 months). Eight patients (7 in the SB group and 1 in the DB group) had graft failure during the follow-up and had anterior cruciate ligament revision surgery (P = .04). In addition, 7 patients (5 in the SB group and 2 in the DB group) had an invisible graft on the MRI assessment at the 2-year follow-up. Also, the anteromedial bundle was partially invisible in 2 patients and the posterolateral bundle in 9 patients. Together, the total number of failures and invisible grafts were significantly higher in the SB group (12 patients, 15%) than the DB group (3 patients, 4%) (P = .024). No significant group differences were found in the knee scores or stability evaluations at the follow-up. CONCLUSION: This 2-year randomized trial showed that the revision rate of the anterior cruciate ligament reconstruction was significantly lower with the double-bundle technique than that with the single-bundle technique. However, additional years of follow-up are needed to reveal the long-term results.

Tunnel enlargement after double-bundle anterior cruciate ligament reconstruction: a prospective, randomized study.

PURPOSE: The aim of this study was to compare tunnel enlargement in patients with double-bundle and single-bundle anterior cruciate ligament (ACL) reconstruction. METHODS: Sixty patients were randomized by closed envelopes into 2 different groups of ACL reconstruction with hamstring tendons: double-bundle technique with bioabsorbable screw fixation (n = 35) and single-bundle technique with bioabsorbable screw fixation (n = 25). Magnetic resonance imaging evaluation was performed in 53 patients (88%) (32 in double-bundle group and 21 in single-bundle group) for a mean of 27 months' follow-up (range, 24 to 36 months). Tunnel enlargement was determined by digital measurement of the widths perpendicular to the long axis of the tunnels on an oblique coronal and sagittal plane. The magnetic resonance imaging measurements were compared with the intraoperative drill diameter. RESULTS: No significant differences were found between the double-bundle group and the single-bundle group in tunnel enlargement on the femoral side. However, on the tibial side, tunnel enlargement was greater in the single-bundle group than in the double-bundle group in each tunnel (P = .051). In all knees, tunnel enlargement both on the tibial side and on the femoral side correlated significantly with the anterior and rotational laxity of the operated knee. In the double-bundle group, no tunnel communication between the anteromedial and posterolateral tunnels was seen in any of the patients on either the tibial side or femoral side. CONCLUSIONS: This prospective, randomized study showed that our double-bundle ACL reconstruction technique results in less tunnel enlargement in each tunnel on the tibial side than the single-bundle technique with similar fixation methods, graft material, and rehabilitation. In addition, no tunnel communication was observed in the patients undergoing double-bundle ACL reconstruction. The clinical results were good in both groups. However, the patients who had more tunnel enlargement had significantly more anterior and rotational laxity of the operated knee as well. LEVEL OF EVIDENCE: Level I, therapeutic randomized controlled trial.

Comparison of the bioabsorbable and metal screw fixation after ACL reconstruction with a hamstring autograft in MRI and clinical outcome: a prospective randomized study.

There has never been an MRI study of tunnel widening comparing bioabsorbable to metal screw fixation in autologous hamstring anterior cruciate ligament (ACL) reconstruction. We randomized 62 patients to hamstring ACL reconstruction with either a bioabsorbable (n=31) or metal screw (n=31) fixation. The evaluation methods were clinical examination, KT-1000 arthrometric measurement, the International Knee Documentation Committee and Lysholm scores, and MRI. There were no differences between the groups preoperatively. Fifty-five patients (89%) were available at a minimum of 2-year follow-up (range 24-36 months). There was tunnel widening in both groups, but the increase was significantly greater in the AP dimension of the femoral tunnel in the bioabsorbable screw group compared to metal group (P=0.01). The tibial tunnels showed no intergroup difference. Ninety-four percent of the knees were normal or nearly normal according to the IKDC scores and the average Lysholm score was 91 with no intergroup difference. The follow-up AP tibial tunnel diameter was smaller with normal knee laxity compared to abnormal knee laxity. The graft failure rate in the bioabsorbable screw group was 23% (7/31 patients) and 6% (2/31 patients) in the metal screw group. The use of bioabsorbable screws resulted in more femoral tunnel widening, and more graft failures compared to metal screws. The tunnel widening in the tibia was associated with the knee laxity (P=0.02).

Double-bundle anterior cruciate ligament reconstruction using hamstring autografts and bioabsorbable interference screw fixation: prospective, randomized, clinical study with 2-year results.

BACKGROUND: Conventional anterior cruciate ligament reconstruction techniques have focused on restoration of the anteromedial bundle only, which, however, may be insufficient in restoring the rotational stability of the knee. HYPOTHESIS: Rotational stability of the knee is better when using a double-bundle technique instead of a single-bundle technique for anterior cruciate ligament reconstruction. STUDY DESIGN: Randomized controlled clinical trial; Level of evidence, 1. METHODS: Seventy-seven patients were randomized into 3 different groups for anterior cruciate ligament reconstruction with hamstring tendons: double-bundle with bioabsorbable screw fixation (n = 25), single-bundle with bioabsorbable screw fixation (n = 27), and single-bundle with metallic screw fixation (n = 25). The evaluation methods were clinical examination, KT-1000 arthrometric measurement, and the International Knee Documentation Committee and Lysholm knee scores. RESULTS: There were no differences between the study groups preoperatively. Seventy-three patients (95%) were available at a minimum 2-year follow-up (range, 24-35 mo). The rotational stability of the knee, as evaluated by the pivot-shift test, was the best in the patients in the double-bundle group. In addition, the patients in the single-bundle groups had more graft failures than those in the double-bundle group. Concerning the anterior stability of the knee as measured with the KT-1000 arthrometer, the group differences were not statistically significant. No significant differences were found between the groups in knee scores. CONCLUSION: Rotational stability of the knee is better when using the double-bundle technique instead of the single-bundle technique in anterior cruciate ligament reconstruction.

High-performance carbon nanotube fiber.

With their impressive individual properties, carbon nanotubes should form high-performance fibers. We explored the roles of nanotube length and structure, fiber density, and nanotube orientation in achieving optimum mechanical properties. We found that carbon nanotube fiber, spun directly and continuously from gas phase as an aerogel, combines high strength and high stiffness (axial elastic modulus), with an energy to breakage (toughness) considerably greater than that of any commercial high-strength fiber. Different levels of carbon nanotube orientation, fiber density, and mechanical properties can be achieved by drawing the aerogel at various winding rates. The mechanical data obtained demonstrate the considerable potential of carbon nanotube assemblies in the quest for maximal mechanical performance. The statistical aspects of the mechanical data reveal the deleterious effect of defects and indicate strategies for future work.

The effect of graft placement on the clinical outcome of the anterior cruciate ligament reconstruction: a prospective study.

The effect of the graft placement on the clinical outcome of patients after anterior cruciate ligament (ACL) reconstruction has been studied sparsely. We conducted a prospective follow-up of 140 patients who underwent an arthroscopic ACL reconstruction with a hamstring graft. One hundred and four of them (74%) could be examined at the 2-year follow-up. Clinical examination included Lysholm, Tegner, and International Knee Documentation Committee rating scores, arthrometric anterior-posterior knee laxity assessment, and muscle strength assessments. The graft placement was measured from lateral radiographs using a system recommended for measuring the attachment positions of the cruciate ligaments as well as a method called 'the sumscore of the graft placement', which takes into account both the femoral and the tibial graft placements simultaneously. The sumscore was smaller in knees with normal anterior-posterior knee laxity in the Lachman test (P = 0.002) and normal rotational knee laxity in the pivot shift test (P = 0.01) than in those with abnormal laxity. The tibial graft placement was more anterior when the Lachman test was normal (P = 0.04). The Lysholm score was better when the femoral graft placement was more posterior (r = -0.20, P = 0.04). The optimal femoral graft placement was between 25 and 29% of length of the femoral condyle along the Blumensaat's line from posterior to anterior. The optimal tibial graft placement was between 32 and 37% of the length of the tibial plateau from the anterior corner, and the optimal sumscore was between 61 and 66. The sumscore and its components (the femoral and tibial graft placements) showed a clear association with the clinical outcome of the patients. The best outcome was achieved when the sumscore was small; that is the graft placement showed posterior enough in the femur, and anterior enough in the tibia.

A novel hybrid carbon material.

Both fullerenes and single-walled carbon nanotubes (SWNTs) exhibit many advantageous properties. Despite the similarities between these two forms of carbon, there have been very few attempts to physically merge them. We have discovered a novel hybrid material that combines fullerenes and SWNTs into a single structure in which the fullerenes are covalently bonded to the outer surface of the SWNTs. These fullerene-functionalized SWNTs, which we have termed NanoBuds, were selectively synthesized in two different one-step continuous methods, during which fullerenes were formed on iron-catalyst particles together with SWNTs during CO disproportionation. The field-emission characteristics of NanoBuds suggest that they may possess advantageous properties compared with single-walled nanotubes or fullerenes alone, or in their non-bonded configurations.