Intrinsically disordered proteins are important in signaling, regulation, and translocation. Understanding their diffusion under physiologically relevant conditions will yield insight into their functions. We used NMR to quantify the translational diffusion of a globular and a disordered protein in dilute solution and under crowded conditions. In dilute solution, the globular protein chymotrypsin inhibitor 2 (CI2, 7.4 kDa) diffuses faster than the disordered protein α-synuclein (14 kDa). Surprisingly, the opposite occurs under crowded conditions; α-synuclein diffuses faster than CI2, even though α-synuclein is larger than CI2. These data show that shape is a key parameter determining protein diffusion under crowded conditions, adding to the properties known to be affected by macromolecular crowding. The results also offer a clue about why many signaling proteins are disordered.

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The use of biologics in sports medicine is increasing rapidly. An osteochondral defect in a young active patient remains a difficult issue to treat. Autograft cartilage has tremendous advantages for the treatment of full-thickness defects, but harvesting and preparation have been difficult in the past. Disadvantages have included donor-site morbidity and the need for further surgery. With the recent development of the GraftNet device (Arthrex, Naples, FL), harvesting and delivery of autograft have become easier and can be performed arthroscopically in a single surgical procedure. Bone marrow concentrate has recently increased in popularity owing to the presence of mesenchymal stem cells. These stem cells combined with autograft cartilage and BioCartilage (Arthrex) could lead to better incorporation and healing. In this article, we show how this unique biological composite is obtained and then added in the cartilage defect during a singlestage arthroscopic procedure.

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The quad tendon has increasingly became a very common option for anterior cruciate ligament reconstruction. Minimally invasive approaches are one of the many advantages to the quad tendon graft. One of the issues with a small incision is assuring appropriate proximal closure. In this technique, we use the arthroscope to view proximally and a Scorpion (Arthrex) device to close our proximal quad harvest. We also describe the updated preparation of the quad tendon with FiberTag TightRope (Arthrex) and FiberTag ABS (Arthrex). These implants have FiberTag incorporated to the suspensory devices that creates a stable construct that is faster to incorporate into the quad with the slotted clamp. Together, these updates to the preparation and harvest should make the construct more reproducible and decrease donorsite morbidity respectively.

Purpose: To examine the early clinical outcomes as well as safety of the Fertilized anterior cruciate ligament (ACL) reconstruction procedure. Methods: A total of 16 consecutive patients with a mean age of 24 years (range, 16-45 years), who had been treated with the fertilized ACL were evaluated and followed over 2 years. Four patients underwent reconstruction using an FGL GRAFTLINK allograft (LifeNet Virginia Beach, VA) and 12 using quadriceps autografts. All patients received the fertilized ACL as previously described using bone marrow composite, demineralized bone matrix, and an internal brace (Arthrex, Largo, FL). Clinical outcomes at 2 years including International Knee Documentation Committee and Marx scores were evaluated. Complication rates, including return to operating room, arthrofibrosis, infection, and rerupture rates, were also assessed. Results: All patients were followed for 6 months and all were released to full activity. In total, 11 of 16 patients were available for 2-year follow-up after the fertilized ACL reconstruction. At 2 years, the average International Knee Documentation Committee and Marx scores were 81 (standard deviation, 5.9) and 9 (standard deviation, 5.7), respectively. One patient required a return trip to the operating room for manipulation under anesthesia. No reruptures were observed at the 2-year mark. Nine of 11 patients had returned to their preinjury activity status at 2 years. Conclusions: The fertilized ACL, which adds biology and an internal brace to an ACL reconstruction, is a reliable and safe option when performing an ACL reconstruction. Very low complication risks were seen in this consecutive series followed for 2 years. Patients consistently returned to their preinjury activity status. Level of Evidence: Level IV, therapeutic case series.

The use of biologics in sports medicine is increasing rapidly. Bone marrow concentrate has recently increased in popularity because it includes mesenchymal stem cells which, combined with AlloSync Pure, could lead to better incorporation and healing. The mixture of bone marrow concentrate and Allosync Pure can be used in anterior cruciate ligament reconstruction. We recently expanded on this approach with the addition of saving the host bone normally lost from tunnel reaming, using the GraftNet. After harvesting the autograft bone, we combine it with the AlloSync Pure and bone marrow concentrate. In this Technical Note, we show how this unique biologic composite is obtained and then added back into the tunnels on both the femur and tibia during a quadriceps tendon autograft all-inside anterior cruciate ligament reconstruction.