Pearls: Individualized Approach to ACL Reconstruction—One Size Does Not Fit All

Given how common ACL injuries have become, it not surprising that both research and industry have attempted to simplify orthopaedic procedures like ACL reconstruction by creating “one-size-fits-all” approaches for surgical devices and graft sizes. While such treatments may work well for most patients, human variation often creates a bell curve of anatomy, size, injury patterns, and athletic goals, and applying a standardized approach will poorly serve patients whose injuries, anatomies, and ambitions are in the tails of the bell-shaped curve. Indeed, using the same size graft and positioning tunnels in the same location simply does not make sense given the wide variation in bony morphology; the same may be true for the operation itself (“ACL reconstruction” is not a single operation, but a family of operations that includes a wide menu of surgical options), and its aftercare. Ensuring that the surgery fits the patient’s individual anatomy, injury pattern, and athletic demands can prevent many surgical complications, including graft rupture and the revision procedures that might follow.

A narrow intercondylar notch cannot accommodate a large graft diameter (Fig. 1). A graft too large for the available space will either limit motion or will stretch to the point of failure (Fig. 2A-D). A long distance between the tibial and femoral insertion sites may call for the use of a bone block to create a long enough graft to keep sutures out of the intraarticular space and sufficient tissue inside the tibial tunnel for fixation (Fig. 3A-B). For individuals with a thin patella (less than 14 mm), the narrow bone bridge created by harvesting a 10 mm bone block increases the risk of intraoperative and postoperative fracture. A few simple measurements from the preoperative MRI can help a surgeon determine the ideal graft diameter and length to restore the native anatomy as well as identify some potential graft limitations specific to each patient. Using this technique is inexpensive, quick, and in my experience, can help to avoid graft failure in 10% to 15% of patients.

Fig. 1.

A 1-year postoperative MRI shows a large graft within a small intercondylar notch impinging at the anterior aspect, preventing full extension.

Fig. 2 A-D.

(A) A preoperative exam with the patient under anesthesia shows a 15° extension deficit relative to the nonoperative knee. (B) Arthroscopic image of graft impingement and regrowth of prior notchplasty is shown. (C) An intraoperative arthroscopic image of over-the-top graft position is shown. (D) An immediate postoperative photograph indicates neutral extension following revision ACL reconstruction to the over-the-top position.

Fig. 3 A-B.

An oblique sagittal MRI shows a short (A) and a long (B) native ACL. A longer distance between tibial and femoral insertion sites will require a longer graft (> 80 mm) for sufficient fixation within the tunnels compared to the graft required for a shorter distance where a 65-70 mm graft may be sufficient.

Many options exist for the ACL reconstruction procedure itself, and each has an indication. Single-bundle reconstruction probably is appropriate for most ACL tears. However, for some large ACL insertion sites (AP length of the tibial insertion site greater than 18 mm), a double-bundle reconstruction may be indicated. The key here is to restore 50% to 80% of the patient’s tibial insertion site. If this can be done with a single-bundle graft, then I will choose the single-bundle approach in order to avoid the potential complications and additional expense of using four tunnels instead of two. When I treat a patient who has a single-bundle tear, a one-bundle augmentation allows for retention of the intact bundle along with its neurovascular bundles, which may be advantageous for improved postoperative proprioception and biological healing [2]. When preoperative MRI indicates a substantial remnant and an operation can be performed shortly after injury, the tibial remnant may be well-preserved enough to perform remnant-preservation reconstruction. There are several potential benefits to preserving the remnant tissue including better identification of the native ACL footprint for a more anatomical reconstruction, improved post-operative proprioception, and improved graft healing [1]. Passing the graft through the remnant preserves the borders of the tibial insertion site and any remaining neurovascular supply. In any ACL restoration surgery, it is important to do only what the individual patient’s injury and anatomy require to improve outcomes, reduce complication risks, and to reduce healthcare costs.

Individualizing treatment to a particular patient’s need extends beyond the operation to physical therapy and return-to-sport. Anatomic ACL reconstruction, defined as the functional restoration of the ACL to its native dimensions, collagen orientation, and insertion sites according to individual anatomy [3], restores native forces. Thus, the graft may need to be protected, in my opinion, until 9 to 12 months following reconstruction to ensure sufficient healing has occurred.

The “one-size does not fit all” principle extends beyond ACL reconstruction, applying to most instances of “one-size fits all” orthopaedic surgery. The more techniques a surgeon can perform with confidence, the more he or she can tailor the individual procedure to a particular patient, which, I believe, gives the patient a greater chance of achieving the desired result.