Outcome of meniscal allograft transplantation related to articular cartilage status: advanced chondral damage should not be a contraindication

© 2014, European Society of Sports Traumatology, Knee Surgery, Arthroscopy (ESSKA). Purpose: Advanced chondral damage (bare bone) at presentation is considered a contraindication to meniscal allograft transplantation (MAT), yet there are few other options for young patients where arthroplasty is not appropriate. This study hypothesis is that MAT in patients with advanced chondral damage can obtain good clinical outcomes, equivalent to patients with minimal chondral damage.Results: Mean follow-up was 2.9 years (range 1.1–9.1, SD 1.23), with a similar male to female and lateral to medial ratios between the groups (n.s). The age of Group B was significantly older than Group A (35 vs 29 years, p = 0.002). The status of the articular cartilage at the time of transplant was directly related to the number of years since index meniscectomy [(A) Mean 6.9 years, SD 6.3; (B) 11.9 years, SD 7.4; p = 0.001]. Pre-operatively, patients in Group B had significantly worse pain and functional outcome scores (KOOS p = 0.022, Lysholm p = 0.025, IKDC pain subset p = 0.035). The mean increase PROMs was significant in both groups at 1 year (KOOS p \u3c 0.05, IKDC p \u3c 0.001, Lysholm p \u3c 0.001), and the pain and functional scores were no longer significantly different between groups (n.s.). The outcome measures continued to improve in both groups at 2 and 3 years, with slightly greater improvement in Group A. Failure of the meniscal allograft occurred in 9 patients (A:1, B:8) at a mean time of 1.1 years (SD 0.55). Kaplan–Meier survival at 2 years was 97.9 % (A) and 78 % (B) (p = 0.002). Logistic regression analysis demonstrated a relationship between survival and chondral grade (p = 0.001) and number of concomitant procedures (p \u3c 0.001).Level of evidence: III.Method: A prospective longitudinal study of 99 consecutive patients who underwent MAT between May 2005 and Feb 2013, with a minimum of 1-year follow-up. Patients were categorised into two groups: 60 in Group A (Good) up to ICRS Chondral grade 3b involving 1 cm2 or worse. Outcomes were assessed by PROMS (KOOS, IKDC, Lysholm, Tegner Activity Scale), with an endpoint of meniscal allograft failure.Conclusion: Patients with advanced chondral damage should not be excluded from MAT. Though there is a higher initial failure rate, these patients obtain a similar therapeutic benefit to the traditional, ideal patient group

In-situ TEM observation of the response of ultrafine- and nanocrystalline-grained tungsten to extreme irradiation environments

The accumulation of defects, and in particular He bubbles, can have significant implications for the performance of materials exposed to the plasma in magnetic-confinement nuclear fusion reactors. Some of the most promising candidates for deployment into such environments are nanocrystalline materials as the engineering of grain boundary density offers the possibility of tailoring their radiation resistance properties. In order to investigate the microstructural evolution of ultrafine- and nanocrystalline-grained tungsten under conditions similar to those in a reactor, a transmission electron microscopy study with in He1 ion irradiation at 9506C has been completed. A dynamic and complex evolution in the microstructure situ 2 keV was observed including the formation of defect clusters, dislocations and bubbles. Nanocrystalline grains with dimensions less than around 60 nm demonstrated lower bubble density and greater bubble size than larger nanocrystalline (60–100 nm) and ultrafine (100–500 nm) grains. In grains over 100 nm, uniform distributions of bubbles and defects were formed. At higher fluences, large faceted bubbles were observed on the grain boundaries, especially on those of nanocrystalline grains, indicating the important role grain boundaries can play in trapping He and thus in giving rise to the enhanced radiation tolerance of nanocrystalline materials