Cell death-inducing DFF45-like effector (CIDE) domains, initially identified in apoptotic nucleases, form a family with diverse functions ranging from cell death to lipid homeostasis. Here we show that the CIDE domains of Drosophila and human apoptotic nucleases Drep2, Drep4, and DFF40 all form head-to-tail helical filaments. Opposing positively and negatively charged interfaces mediate the helical structures, and mutations on these surfaces abolish nuclease activation for apoptotic DNA fragmentation. Conserved filamentous structures are observed in CIDE family members involved in lipid homeostasis, and mutations on the charged interfaces compromise lipid droplet fusion, suggesting that CIDE domains represent a scaffold for higher-order assembly in DNA fragmentation and other biological processes such as lipid homeostasis.

Purpose: The purpose of the present study was to evaluate the long‐term outcome of combined medial unicompartmental knee arthroplasty (UKA) and anterior cruciate ligament reconstruction (ACLR). The authors hypothesized that the combined procedure leads to good long‐term outcome in patients with isolated medial knee osteoarthritis (OA) and anterior cruciate ligament (ACL) deficiency. Methods: Twenty‐three patients with ACL deficiency and concomitant medial knee OA were treated from 2008 to 2016 with a combined UKA (Oxford Partial Knee) and ACLR using a hamstring tendon autograft. The follow‐up assessment included VAS pain score, Lysholm score, Oxford Knee Score (OKS), American Knee Society scores (AKSS), International Knee Documentation Committee (IKDC 2000), Tegner and UCLA activity scores. Instrumented laxity test was done using the KT‐1000 arthrometer. Survivorship analysis was performed using the Kaplan–Meier method. Implant loosening and disease progression was assessed by conventional radiography. Results: Average follow‐up duration was 10 years (6–14.5). VAS, Lysholm, Tegner and UCLA scores improved significantly. OKS, AKSS and IKDC 2000 showed excellent results on follow‐up. Implant survivorship was 91.4% at 14.5 years. There were 2 revisions with conversion to total knee arthroplasty at 6 and 12 years postoperatively due to trauma and disease progression, respectively. There were no radiological or clinical signs of instability or disease progression in any of the remaining knees. The side‐to‐side difference using the KT‐1000 arthrometer was insignificant. Conclusions: UKA combined with ACLR is an effective therapeutic option with good outcome and return to sport rate on the long‐term.Level of evidence: IV.