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Anterior cruciate ligament (ACL) injuries are common in the athletic population. ACL repair with bridge enhancement is an emerging technology with promising clinical outcomes in patients with a proximal to midsubstance ACL tears. Currently, there are a variety of fixation methods described for isolated ACL repair, including suspensory and anchor techniques. This Technical Note describes a bridge enhanced ACL restoration procedure technique, using suture anchors for the femoral fixation. Advantages of this technique include more rigid fixation and avoiding need for accessory over-the-top incision. Additionally, the surgical workflow is more similar to an ACL reconstruction with intra-articular screw fixation, which may be more readily adopted by some surgeons.

Articular cartilage defects in the knee and ankle are frequently seen in football (soccer) players and are often a result of trauma, but occasionally are the consequence of occult underlying conditions such as osteochondritis dissecans. Symptoms such as pain, swelling, and inability to ramp up may limit an athlete's performance and ability to compete. Initial evaluation includes a careful history and physical exam, including assessment of overall limb and joint alignment, ligamentous stability, meniscal damage, as well as associated degenerative change. Though nonoperative management serves as the mainstay for treatment in high-level athletes, surgical options are indicated in situations where symptoms persist. Osteochondral allograft (OCA) transplantation, in particular, allows for restoration of hyaline cartilage with predictable healing and accelerated return to activity. With appropriate indications and surgical technique, graft survival following OCA transplantation can exceed 90% at 10 years postoperatively, allow for predictable (70%-80%) return to sport, and produce clinically meaningful improvements in patient-reported outcomes. Full return to sports is often possible between 4 and 10 months postoperatively. Careful attention to postoperative rehabilitation and strength progression prior to return to sport is imperative to prevent graft overload, joint inflammation, or secondary injury to other knee structures such as meniscus or ligamentous structures. This article reviews the overall indications, technique, and outcomes of OCA transplantation in the athletic population.

Revision hip arthroplasty in the setting of periacetabular bone loss presents a significant challenge, as options for restoring bone loss are limited. Recombinant human bone morphogenetic protein-2 may offer a solution by promoting bone growth to restore bone stock before implant reimplantation. Here we present a case of a patient with a periprosthetic acetabulum fracture, resulting in pelvic discontinuity as the result of significant periacetabular bone loss. Using a staged approach, periacetabular bone stock was nearly entirely reconstituted using recombinant BMPs and allograft, which resulted in stable fixation, but with abundant heterotopic bone formation. Recombinant BMP-2 offers a useful tool for restoring bone stock in complex hip arthroplasty revision cases with periacetabular bone loss; however, caution must be used as overabundant bone growth as heterotopic ossification may result.

N6-methyladenosine (m6A) is a common modification of mRNA with potential roles in fine-tuning the RNA life cycle. Here, we identify a dense network of proteins interacting with METTL3, a component of the methyltransferase complex, and show that three of them (WTAP, METTL14, and KIAA1429) are required for methylation. Monitoring m6A levels upon WTAP depletion allowed the definition of accurate and near single-nucleotide resolution methylation maps and their classification into WTAP-dependent and -independent sites. WTAP-dependent sites are located at internal positions in transcripts, topologically static across a variety of systems we surveyed, and inversely correlated with mRNA stability, consistent with a role in establishing “basal” degradation rates. WTAP-independent sites form at the first transcribed base as part of the cap structure and are present at thousands of sites, forming a previously unappreciated layer of transcriptome complexity. Our data shed light on the proteomic and transcriptional underpinnings of this RNA modification.