Meniscal Allograft Transplantation Does Not Prevent or Delay Progression of Knee Osteoarthritis

Background Meniscal tears are common knee injuries. Meniscal allograft transplantation (MAT) has been advocated to alleviate symptoms and delay osteoarthritis (OA) after meniscectomy. We investigated (1) the long-term outcome of MAT as a treatment of symptomatic meniscectomy, (2) most important factors affecting survivorship and (3) OA progression. Methods From 1989 till 2013, 329 MAT were performed in 313 patients. Clinical and radiographic results and MAT survival were evaluated retrospectively. Failure was defined as conversion to knee arthroplasty (KA) or total removal of the MAT. Results Mean age at surgery was 33 years (15–57); 60% were males. No-to-mild cartilage damage was found in 156 cases, moderate-to-severe damage in 130. Simultaneous procedures in 118 patients included cartilage procedures, osteotomy or ACL-reconstruction. At a mean follow-up of 6.8 years (0.2–24.3years), 5 patients were deceased and 48 lost (14.6%), 186 MAT were in situ (56.5%) whilst 90 (27.4%) had been removed, including 63 converted to a KA (19.2%). Cumulative allograft survivorship was 15.1% (95% CI:13.9–16.3) at 24.0 years. In patients <35 years at surgery, survival was significantly better (24.1%) compared to ≥35 years (8.0%) (p = 0.017). In knees with no-to-mild cartilage damage more allografts survived (43.0%) compared to moderate-to-severe damage (6.6%) (p = 0.003). Simultaneous osteotomy significantly deteriorated survival (0% at 24.0 years) (p = 0.010). 61% of patients underwent at least one additional surgery (1–11) for clinical symptoms after MAT. Consecutive radiographs showed significant OA progression at a mean of 3.8 years (p<0.0001). Incremental Kellgren-Lawrence grade was +1,1 grade per 1000 days (2,7yrs). Conclusions MAT did not delay or prevent tibiofemoral OA progression. 19.2% were converted to a knee prosthesis at a mean of 10.3 years. Patients younger than 35 with no-to-mild cartilage damage may benefit from MAT for relief of symptoms (survivorship 51.9% at 20.2 years), but patients and healthcare payers and providers should be aware of the high number of surgical re-interventions

Towards Integrated Flexible Energy Harvester and Supercapacitor for Self-powered Wearable Sensors

We present the first results of a flexible energy harvester and a foldable supercapacitor to power wearable and flexible sensors. The flexible energy harvester is fabricated by using 38 mu m piezoelectric polyvinylidene difluoride (PVDF) sandwiched between carbon electrodes. Both the design and process excel in simplicity and cost-effectiveness. The flexible harvester demonstrates a power output of 2.6 mu W cm(-3) at a resonant frequency of 50 Hz with a 3dB bandwidth of about 11 Hz, which is higher than devices previously reported and similar to a commercial PZT harvester film of same size. A flexible energy storage supercapacitor (GP-SC) was fabricated using a graphite/VACNTs (vertically aligned carbon nanotubes) material as electrodes. A prototype GP-SCs has an areal capacitance of about 1.2 mF cm(-2). Finally, an integrated scheme is proposed for future work