Remnants-preserving ACL reconstruction using direct tendinous graft fixation: a new rat model

Abstract

Background Anterior cruciate ligament (ACL) repair techniques are new emerging strategies prevailing, in selected cases, over standard reconstruction of the ACL with excision of its remnants. Mid-substance ACL tears represent a challenge for ACL repair techniques, and remnants-preserving ACL reconstruction (rp-ACLR) using an autograft remains the recommended treatment in this situation. However, morbidity associated with the autograft harvesting prompts the need for alternative surgical strategies based on the use of synthetic scaffolds. Relevant small animal models of mid-substance tears with ACL remnants preservation and reconstruction are necessary to establish the preliminary proof of concept of these new strategies. Methods A rat model of rp-ACLR using a tendinous autograft after complete mid-substance ACL transection was established. Twelve weeks following surgery, clinical outcomes and knee joints were assessed through visual gait analysis, Lachman tests, thigh perimeter measurements, magnetic resonance imaging, micro-computed tomography, and histology, to evaluate the morbidity of the procedure, accuracy of bone tunnel positioning, ACL remnants fate, osteoarthritis, and autograft bony integration. Results were compared with those obtained with isolated ACL transection without reconstruction and to right non-operated knees. Results and discussion Most operated animals were weight-bearing the day following surgery, and no adverse inflammatory reaction has been observed for the whole duration of the study. Autograft fixation with cortical screws provided effective graft anchorage until sacrifice. Healing of the transected ACL was not observed in the animals in which no graft reconstruction was performed. rp-ACLR was associated with a reduced degeneration of the ACL remnants (p = 0.004) and cartilages (p = 0.0437). Joint effusion and synovitis were significantly lower in the reconstructed group compared to the transected ACL group (p = 0.004). Most of the bone tunnel apertures were anatomically positioned in the coronal and/or sagittal plane. The most deviated bone tunnel apertures were the tibial ones, located in median less than 1 mm posteriorly to anatomical ACL footprint center. Conclusion This study presents a cost-effective, new relevant and objective rat model associated with low morbidity for the preliminary study of bio-implantable materials designed for remnants-preserving ACL surgery after mid-substance ACL tear.

Adenosine, lidocaine, and magnesium therapy augments joint tissue healing following experimental anterior cruciate ligament rupture and reconstruction

“… 20 The IFP was selected as the region of interest since it shows the largest fibrotic response after knee injury/surgery. 20 A five parameter, 0-to-3 scale scoring system was used to assess ACL graft inflammation, 24 remodelling, and degenerative changes within the graft midsubstance in H&E and Masson-Goldner trichrome (MGT)-stained sections. Assessment of bone-tendon healing within the femoral and tibial bone tunnels was performed on safranin O/fast green (SafO)-stained sections using a modified five parameter, 0-to-3 scale scoring system, where a score of 15 reflects the highest degree of graft osseointegration.…”

“…Assessment of bone-tendon healing within the femoral and tibial bone tunnels was performed on safranin O/fast green (SafO)-stained sections using a modified five parameter, 0-to-3 scale scoring system, where a score of 15 reflects the highest degree of graft osseointegration. 24 Since cartilage degenerative changes occur more frequently in the medial compartment after ACLR, cartilage degradation within the MFC, and medial tibial plateau (MTP), was assessed in SafO-stained sections according to the Osteoarthritis Research Society International (OARSI) scoring scale. 21 , 25 Average MFC and MTP scores were combined to provide a summed score joint value, with a maximum possible score of 10.…”

A Comprehensive Model of Blood Flow Restriction in the Post-surgical Rat

“…BFR-exercise is used to attenuate muscle loss following common orthopedic surgeries, including ACL-R surgery in humans 4,6,39 . Rat models of ACL-R have been previously described to explore technical modifications and to trial engineered allografts of the ACL for ACL-R [40][41][42][43][44] . ACL-R as a model of post-surgical muscle loss for BFR-exercise in rats has not been extensively described but offers a clinically relevant foundation to study the hypertrophic effects of BR-exercise in rats.…”