Intrinsic healing response of the human anterior cruciate ligament: An histological study of reattached ACL remnants

Abstract

A reattachment of the tibial remnant of the torn anterior cruciate ligament (ACL) to the posterior cruciate ligament is sometimes observed during surgery and apparently implies that the human ACL does have a healing response. The aim of this study was to investigate whether this reattachment tissue has similar histological characteristics of a healing response as the medial collateral ligament (MCL), which can heal spontaneously. Standard histology and immunostaining of a-smooth muscle actin and collagen type 3 was performed. The results shows that the reattached tissue has typical characteristics of a healing response: the reattached ACL remnant could not be released by forceful traction; microscopy showed that the collagen fibers of the reattached tissue were disorganized with no preferred direction; increased neovascularization; the presence of lipid vacuoles; the mean number of cells within the biopsy tissue was 631 AE 269 cells per mm 2 ; and 68 AE 20% was expressing a-SMA; semi-quantitative analysis of collagen type 3 expression showed that collagen type 3 had an high expression with an average score of 3. In conclusion, this study shows that the human proximal 1/3 ACL has an intrinsic healing response with typical histological characteristics similar to the MCL. ß

Acute Proximal Anterior Cruciate Ligament Tears: Outcomes After Arthroscopic Suture Anchor Repair Versus Anatomic Single-Bundle Reconstruction

“…As supported by Nguyen et al, 13 proximal avulsion tears behave differently than midsubstance ACL tears. On the basis of the findings by Sherman et al, 8 proximal avulsion tears with high tissue quality yielded the highest probability of successful results.…”

“…Nguyen et al 13 investigated the intrinsic healing response of the ACL with histologic characteristics of the medial collateral ligament (MCL). They concluded that the histologic features of the proximal third of the ACL and the MCL were similar and a similar healing response can be expected.…”

Extracellular Matrix Expression and Production in Fibroblast-Collagen Gels: Towards an In Vitro Model for Ligament Wound Healing

“…Uniform gel contraction of the stress-free gels also resulted in cells with a stellate like cell morphology with disorganized fiber organization that resembles early scar tissue. 34 Gel contraction may increase the number of cell-cell contacts, 2 and could play a role in modulating the different cellular responses observed between the three static stress conditions (Table 1). 3 …”

Key Determinants of Anterior Cruciate Ligament Spontaneous Healing

“…A better understanding of the reasons for the failure of ACL to spontaneously heal will help us develop newer treatment methods. Although we are still unaware of the entire mechanism, and the signaling pathways involved in ACL spontaneous healing, recent studies have identified few probable candidates that may be possible key players [41,[47][48][49][50]. Some studies have reported that injured ACL has the same functional healing response as other extra-articular ligaments in terms of cellularity and vascularity.…”