Five years ago, all-inside ACL reconstruction using the no-incision technique involved use of transtibial drilling of the ACL femoral socket.² Unfortunately, the transtibial technique for creating the ACL femoral socket is known to be a risk factor for anatomically mismatched posterior tibial tunnel placement and high anteromedial (AM) femoral tunnel placement.^3–7 As a result, over the last 5 years some surgeons have transitioned to the AM portal technique for creating the ACL femoral tunnel.^4,6,8,9–18 This technique, however, is not without associated potential pitfalls.^{4,8,9,12,13,15,16,19,20} In response to these concerns, in 2011 we recommended creating the ACL femoral socket with use of an outside-in technique as an alternative to the anatomic AM portal technique.^{3,5,14,15,21–23}

Historically, the outside-in technique for creating the ACL femoral socket fell out of favor because of the requirement for two-incision technique involving a lateral muscle-splitting dissection at the distal femur.3,4,21,23 Recently, however, new technology including narrow-diameter guide pins that are transformed into retrograde drills^14,15 allows for a “no-incision” outside-in technique to create the ACL femoral socket. The advantages of an outside-in technique for creating the femoral socket include the ability of the surgeon to operate in the comfortable and familiar position of 90 degrees of knee flexion (unlike the AM portal technique), independent placement the femoral socket in an anatomic position unconstrained from drilling through the tibial tunnel, and drilling of a longer socket than with the AM portal technique.¹⁵ In addition, outside-in drilling allows for measurement of the femoral interosseous distance before socket creation with use of standard, outside-in femoral guides and guide pin sleeves. Premeasurement of the socket depth is a safety feature of the outside-in technique because a short tunnel may necessitate that less graft tissue be contained within the femoral socket.²⁴

In addition to the use of retrograde drilling pins, two additional technical developments simplify all-inside ACL reconstruction. The first development represents an evolution of cortical suspensory fixation button devices. First-generation cortical suspensory fixation buttons have fixed length graft loops, whereas second-generation cortical suspensory fixation buttons have graft loops that are adjustable in length, such that after the button flips on the cortex, the graft loop may be tightened. This pulls the graft into the socket to completely fill the socket with graft substance. Whereas the first-generation cortical suspensory fixation buttons were designed for femoral fixation, the second-generation adjustable graft loop buttons are also effective for tibial fixation. In addition, the second-generation adjustable graft loop buttons allow for an increase in graft tension while the loop is tightened, allowing the ACL surgeon for the first time to adjust graft tension even after the graft has been fixed in place.

The second important technical development that simplifies all-inside ACL reconstruction is the use of cannulas. Arthroscopic shoulder and hip surgeons have long understood the importance of cannulas for maintaining portals and preventing soft tissue from becoming intertwined in sutures. As a result, we recommend the use of a cannula in the AM arthroscopic instrumentation portal to prevent soft tissue interposition. Furthermore, we introduced a unique guide pin sleeve that transforms into a cannula to maintain access to the narrow-diameter guide pin tracks used to create all-inside sockets, allowing for suture passage and for later graft passage after ACL socket retroconstruction.¹