The effects of femoral graft placement on cartilage thickness after anterior cruciate ligament reconstruction

Abstract

Altered joint motion has been thought to be a contributing factor in the long-term development of osteoarthritis after ACL reconstruction. While many studies have quantified knee kinematics after ACL injury and reconstruction, there is limited in vivo data characterizing the effects of altered knee motion on cartilage thickness distributions. Thus, the objective of this study was to compare cartilage thickness distributions in two groups of patients with ACL reconstruction: one group in which subjects received a non-anatomic reconstruction that resulted in abnormal joint motion and another group in which subjects received an anatomically placed graft that more closely restored normal knee motion. Ten patients with anatomic graft placement (mean follow-up: 20 months) and 12 patients with non-anatomic graft placement (mean follow-up: 18 months) were scanned using high-resolution MR imaging. These images were used to generate 3D mesh models of both knees of each patient. The operative and contralateral knee models were registered to each other and a grid sampling system was used to make site-specific comparisons of cartilage thickness. Patients in the non-anatomic graft placement group demonstrated a significant decrease in cartilage thickness along the medial intercondylar notch in the operative knee relative to the intact knee (8%). In the anatomic graft placement group, no significant changes were observed. These findings suggest that restoring normal knee motion after ACL injury may help to slow the progression of degeneration. Therefore, graft placement may have important implications on the development of osteoarthritis after ACL reconstruction.

In Vivo Measurement of Localized Tibiofemoral Cartilage Strains in Response to Dynamic Activity

“…Subjects were asked to not perform any strenuous lower body activity the night prior to or the morning of their participation. Subjects first lay supine on a stretcher immediately outside of the MR suite for 45 minutes to minimize cartilage deformation prior to scanning 6, 33, 39 . Subjects were then moved to a wheelchair without any weightbearing and transported to the MR suite where they underwent pre-activity imaging.…”

“…These calculations were used to generate cartilage thickness maps for each knee (Figure 2). The femoral and tibial bony surfaces of the pre-activity and post-activity models were aligned using an iterative closest point technique 11, 33, 48 . This registration process enabled the site-specific measurement of cartilage strain using the pre-activity and post-activity models.…”

Updates in biological therapies for knee injuries: anterior cruciate ligament

“…As already stated, given the better understanding of ACL anatomy, there has been a transition from the so-called isometric reconstruction to anatomic reconstruction of the ACL [4,5]. Allegedly, some studies pointed out that anatomical tunnel placement results in superior biological healing, biomechanical properties, knee stability, and even a protective cartilage effect, as compared with a nonanatomic reconstruction [45][46][47][48][49].…”

Different Techniques of ACL Reconstruction: Guidelines

“…These authors suggest that achieving anatomical graft placement on the femur is crucial to restoring normal knee function and may theoretically decrease the rate of joint degeneration after ACL reconstruction. Okafor et al (2014) showed that patients with nonanatomical ACL reconstruction demonstrated a significant decrease in cartilage thickness along the medial intercondylar notch in the operative knee relative to the intact knee. In the anatomic group, no significant changes were observed.…”