The acromioclavicular ligament shows an early and dynamic healing response following acute traumatic rupture

Abstract

Purpose: Symptomatic horizontal instability is clinically relevant following acute acromioclavicular joint dislocations. However, the intrinsic healing response is poorly understood. The present study sought to investigate timedependent healing responses of the human acromioclavicular ligament following acute traumatic rupture. Methods: Biopsies of the acromioclavicular ligament were obtained from patients undergoing surgical treatment for acute acromioclavicular joint dislocations. Specimens were stratified by time between trauma and surgery: group 1, 0-7 days (n = 5); group 2, 8-14 days (n = 6); and group 3, 15-21 days (n = 4). Time-dependent changes in cellularity, collagen (type 1 and 3) concentration, and histomorphological appearance were evaluated for the rupture and intact zone of the acromioclavicular ligament. Results: Group 1 was characterized by cellular activation and early inflammatory response. The rupture zone exhibited a significantly higher count of CD68-positive cells than the intact zone (15.2 vs 7.4; P ≤ 0.05). Consistently, synovialization of the rupture end was observed. Within the second week, the rupture zone was subject to proliferation showing more fibroblast-like cells than the intact zone (66.8 vs 43.8; P ≤ 0.05) and a peak of collagen type 3 expression (group 1: 2.2 ± 0.38, group 2: 3.2 ± 0.18, group 3: 2.8 ± 0.57; P ≤ 0.05). Signs of consolidation and early remodeling were seen in the third week. Conclusions: The acromioclavicular ligament exhibits early and dynamic healing responses following acute traumatic rupture. Our histological findings suggest that surgical treatment of acute ACJ dislocations should be performed as early as possible within a timeframe of 1 week after trauma to exploit the utmost biological healing potential. Prospective clinical studies are warranted to investigate whether early surgical treatment of ACJ dislocations translates into clinical benefits.

The Morphology of the Acromioclavicular Joint Does Not Influence the Postoperative Outcome Following Acute Stabilization—A Case Series of 81 Patients

“…The acute nature of the injury, associated with superior biological healing potential of the AC capsular tissue, may contribute to the explanation of this finding. 40 , 41 , 42 The potential of biological healing is most accentuated during the posttraumatic inflammatory and proliferative biological phases. 40 , 41 , 42 Thus, if an anatomically stable coracoclavicular situation is surgically established in this acute phase and ROM and load are limited—as performed in the acutely treated collective of the present study—the optimal biological healing potential may be leveraged and result in an acceptable integrity and stability of the AC joint capsule.…”

“… 40 , 41 , 42 The potential of biological healing is most accentuated during the posttraumatic inflammatory and proliferative biological phases. 40 , 41 , 42 Thus, if an anatomically stable coracoclavicular situation is surgically established in this acute phase and ROM and load are limited—as performed in the acutely treated collective of the present study—the optimal biological healing potential may be leveraged and result in an acceptable integrity and stability of the AC joint capsule. Indeed, a radiologic evaluation of the AC and CC ligaments via magnetic resonance imaging demonstrated adequate AC-ligament consolidation following isolated CC stabilization in acute cases.…”

Ligamentous healing potential of the acromioclavicular ligament following acute anatomical reconstruction

“…In conclusion, present findings suggest that acute anatomical reconstruction of ACLC ruptures reliably leads to intrinsic ligamentous healing. A recent experimental study of the ACLC healing response defined the first 3 weeks after trauma as the acute phase [ 24 ]. Histomorphologically, reparative changes peaked as early as within the second week after ACLC rupture.…”

“…These studies confirmed that ligament healing progresses in typical overlapping phases of inflammation, proliferation and remodeling but shows fundamental differences between intra- and extraarticular ligaments. Recently, a fundamental histological study described the dynamic healing responses of the ACLC following acute traumatic rupture [ 24 ]. However, the authors are not aware of any study investigating the intrinsic healing characteristics of the human ACLC.…”

Arthroscopic Anatomical Acromioclavicular Joint Reconstruction using a Button Device and a Semitendinosus Graft

“…Although this technique can be used in any AC joint dislocation to be treated surgically, it's especially advantageous in subacute or chronic AC joint dislocations after 3 weeks, when the healing potential of the native CC ligaments is diminished 18 .…”