Bone filling decreases donor site morbidity after anterior cruciate ligament reconstruction with bone-patellar tendon-bone autografts.

PURPOSE: Bone-patellar tendon-bone (BTB) autograft remains the most widely used graft source for anterior cruciate ligament reconstruction (ACLR). The drawback associated with BTB is increased donor-site morbidity, such as anterior knee pain. The purpose of this study was to evaluate and compare anterior knee pain after refilling the patella bony defect with bone substitute. METHODS: This is a retrospective analysis of consecutive patients who underwent BTB ACLR at a single institution between January 2015 and December 2020. The cohort was divided into two groups; one in which the patellar bony defect was refilled with bone substitute (Bone Graft group) and another in which this the bony defects were not treated (No Bone Graft group). Demographic variables, reported anterior knee pain, visual analog scale (VAS) score, complications, re-operation, and patient reported outcome measures, such as the IKDC, LYSHOLM and SF-12 scores, were compared between groups. RESULTS: A total of 286 patients who underwent BTB ACLR were included. The No Bone Graft group included 88 (30.7%) patients and the Bone Graft group included 198 (69.3%) patients. The Bone Graft group had less anterior knee pain at last clinic follow up (33.3% vs. 51.1% p = 0.004) as well as lower VAS anterior knee pain scores (2.18 vs. 3.13, p = 0.004). The Bone Graft group had lower complications rates (21.7% vs 34.1, p = 0.027). No differences were found in the LYSHOLM, IKDC, and SF-12 scores. CONCLUSION: Bone refilling in BTB ACLR significantly reduces prevalence and severity of anterior knee pain. Larger randomized trials are needed to confirm the benefits of bone refilling in ACLR patients. LEVEL OF EVIDENCE: Retrospective study-III.

LY6S, a New IFN-Inducible Human Member of the Ly6a Subfamily Expressed by Spleen Cells and Associated with Inflammation and Viral Resistance.

Syntenic genomic loci on human chromosome 8 and mouse chromosome 15 (mChr15) code for LY6/Ly6 (lymphocyte Ag 6) family proteins. The 23 murine Ly6 family genes include eight genes that are flanked by the murine Ly6e and Ly6l genes and form an Ly6 subgroup referred to in this article as the Ly6a subfamily gene cluster. Ly6a, also known as Stem Cell Ag-1 and T cell-activating protein, is a member of the Ly6a subfamily gene cluster. No LY6 genes have been annotated within the syntenic LY6E to LY6L human locus. We report in this article on LY6S, a solitary human LY6 gene that is syntenic with the murine Ly6a subfamily gene cluster, and with which it shares a common ancestry. LY6S codes for the IFN-inducible GPI-linked LY6S-iso1 protein that contains only 9 of the 10 consensus LY6 cysteine residues and is most highly expressed in a nonclassical spleen cell population. Its expression leads to distinct shifts in patterns of gene expression, particularly of genes coding for inflammatory and immune response proteins, and LY6S-iso1-expressing cells show increased resistance to viral infection. Our findings reveal the presence of a previously unannotated human IFN-stimulated gene, LY6S, which has a 1:8 ortholog relationship with the genes of the Ly6a subfamily gene cluster, is most highly expressed in spleen cells of a nonclassical cell lineage, and whose expression induces viral resistance and is associated with an inflammatory phenotype and with the activation of genes that regulate immune responses.