Synthetic Grafts for Anterior Cruciate Ligament Reconstruction

Radiographic assessment of bone tunnels after anterior cruciate ligament reconstruction: A comparison of hamstring tendon and bone-patellar tendon-bone autografting technique

Objectives

This study aims to compare the postoperative change of femoral and tibial tunnel widths after hamstring tendon (HT) and bone-patellar tendon-bone (BPTB) autografting in primary anterior cruciate ligament (ACL) reconstruction surgery with the anteromedial portal technique.

Patients and methods

This case-control and retrospective study included 39 patients (36 males, 3 females; mean age 30.1±7.9; range, 17 to 44 years) who underwent primary ACL reconstruction surgery with either BPTB autografting method (BPTB group, n=18) or HT autografting method (HT group, n=21) between March 2014 and December 2016. Femoral fixation was achieved with bioabsorbable screw in BPTB group and endobutton in HT group. Tibial fixation was achieved with bioabsorbable interference screw in both groups. Femoral and tibial tunnel widths of groups were compared on digital radiographs.

Results

When we compared the baseline values with the second-year results, the mean of femoral tunnel widths were significantly lower on radiographs at the second-year evaluation in both groups (p<0.001 for all). However, the means of tibial tunnel widths were significantly lower only in the BPTB group (p<0.001 for BPTB group and p=0.616 for HT group). Change levels of anteroposterior and lateral widths were more prominent in BPTB group than HT group (p<0.001 for all).

Conclusion

Changes in tunnel widths show us superior ossification in BPTB grafting. This can be explained by superior bone-to-bone healing. As a result of radiological evaluation, we think that BPTB grafting can be more strong and durable.

Anterior cruciate ligament reconstruction in skeletally immature patients : a systematic review

AIMS

Different methods of anterior cruciate ligament (ACL) reconstruction have been described for skeletally immature patients before closure of the growth plates. However, the outcome and complications following this treatment remain unclear. The aim of this systematic review was to analyse the outcome and complications of different techniques which may be used for reconstruction of the ACL in these patients.

MATERIALS AND METHODS

We performed a systematic review of the literature according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. This involved a comprehensive search of PubMed, Medline, CINAHL, Cochrane, Embase and Google Scholar databases using the following combinations of keywords, "knee", "anterior cruciate ligament", "reconstruction", "injury", "children", "adolescent", "skeletally immature", "open physis" and "surgery".

RESULTS

A total of 53 studies met the inclusion criteria and were included for analysis. The overall rate of disturbance of growth after ACL reconstruction was 2.6%, with no statistical difference between transphyseal and physeal-sparing techniques. Physeal-sparing techniques had a lower rate of post-operative complications compared with transphyseal techniques (p = 0.0045). Outcomes assessed were Lysholm score, International Knee Documentation Committee (IKDC) score, the IKDC grade, the Tegner score and the KT-1000. Both techniques had similar clinical outcomes.

CONCLUSIONS

This review reveals low rates of disturbance of growth after ACL reconstruction in skeletally immature patients. Although limited, the available evidence did not support any particular surgical technique when considering disturbance of growth or clinical outcome. Further randomised controlled trials are needed to investigate the efficacy of differing surgical techniques on outcomes in skeletally immature patients. Cite this article: Bone Joint J 2017;99-B:1053-60.

A Novel Silk Fiber-Based Scaffold for Regeneration of the Anterior Cruciate Ligament: Histological Results From a Study in Sheep

BACKGROUND

Because of ongoing problems with anterior cruciate ligament (ACL) reconstruction, new approaches in the treatment of ACL injuries, particularly strategies based on tissue engineering, have gained increasing research interest. To allow for ACL regeneration, a structured scaffold that provides a mechanical basis, has cells from different sources, and comprises mechanical as well as biological factors is needed. Biological materials, biodegradable polymers, and composite materials are being used and tested as scaffolds. The optimal scaffold for ACL regeneration should be biocompatible and biodegradable to allow tissue ingrowth but also needs to have the right mechanical properties to provide immediate mechanical stability.

HYPOTHESES

The study hypotheses were that (1) a novel degradable silk fiber-based scaffold with mechanical properties similar to the native ACL will be able to initiate ligament regeneration after ACL resection and reconstruction under in vivo conditions and (2) additional cell seeding of the scaffold with autologous stromal vascular fraction-containing adipose-derived stem cells will increase regenerative activity.

STUDY DESIGN

Controlled laboratory study.

METHODS

A total of 33 mountain sheep underwent ACL resection and randomization to 2 experimental groups: (1) ACL reconstruction with a scaffold alone and (2) ACL reconstruction with a cell-seeded scaffold. Histological evaluation of the intra-articular portion of the reconstructed/regenerated ligament was performed after 6 and 12 months.

RESULTS

After 6 months, connective tissue surrounded the silk scaffold with ingrowth in some areas. The cell-seeded scaffolds had a significant lower silk content compared with the unseeded scaffolds and demonstrated a higher content of newly formed tissue. After 12 months, the density of the silk fibers decreased significantly, and the ingrowth of newly formed tissue increased in both groups. No differences between the 2 groups regarding silk fiber degradation and regenerated tissue were detected at 12 months.

CONCLUSION

The novel silk fiber-based scaffold was able to stimulate ACL regeneration under in vivo conditions. Additional cell seeding led to increased tissue regeneration and decreased silk fiber content at 6 months, whereas these differences were not present at 12 months.

CLINICAL RELEVANCE

ACL regeneration using a silk fiber-based scaffold with and without additional cell seeding may provide a new treatment option after joint injuries.

Clinical and functional outcome after anterior cruciate ligament reconstruction using the LARS™ system at a minimum follow-up of 10 years

BACKGROUND

Since the 1980's several artificial ligaments were used for reconstruction of the anterior cruciate ligament (ACL) serving different complications. The aim of this study was to assess the clinical and functional outcomes of primary ACL reconstruction using the Ligament Augmentation Reconstruction System (LARS™) with a minimum follow-up of 10-years. The LARS™ presents a synthetic material consisting of non-absorbing polyethylene terephthalate fibres used for ligament reconstruction.

METHODS

Outcomes of 18 patients who underwent arthroscopic ACL reconstruction using the LARS™ system between 2000 and 2004 with a minimum follow-up of 10 years were observed. The International Knee Documentation Committee score (IKDC), Visual Analog Scale (VAS), Lysholm score, and Tegner Activity Scale were assessed. Clinical assessment was performed by Lachman testing, assessment of side-to-side difference on KT-2000 testing and plain radiography evaluation of osteoarthritis.

RESULTS

There were seven males and 11 females, mean age 29 years (range, 18 to 44 years) and a mean follow-up of 151.5 months. Five patients (27.8%) sustained a re-rupture of the LARS™ system and underwent revision surgery after a mean time of 23 months and four patients (22.2%) presented with a re-rupture. The average IKDC score was 76.60 ± 18.18, the average Lysholm score was 88.00 ± 10.07 and the average Tegner activity score was five at final follow-up.

CONCLUSION

Our results indicate that the LARS™ system should currently not be suggested as a potential graft for primary reconstruction of the ACL. In special cases, however, the LARS™ system can serve as an alternative graft.

Effects of Artificial Ligaments with Different Porous Structures on the Migration of BMSCs

Polyethylene terephthalate- (PET-) based artificial ligaments (PET-ALs) are commonly used in anterior cruciate ligament (ACL) reconstruction surgery. The effects of different porous structures on the migration of bone marrow mesenchymal stem cells (BMSCs) on artificial ligaments and the underlying mechanisms are unclear. In this study, a cell migration model was utilized to observe the migration of BMSCs on PET-ALs with different porous structures. A rabbit extra-articular graft-to-bone healing model was applied to investigate the in vivo effects of four types of PET-ALs, and a mechanical test and histological observation were performed at 4 weeks and 12 weeks. The BMSC migration area of the 5A group was significantly larger than that of the other three groups. The migration of BMSCs in the 5A group was abolished by blocking the RhoA/ROCK signaling pathway with Y27632. The in vivo study demonstrated that implantation of 5A significantly improved osseointegration. Our study explicitly demonstrates that the migration ability of BMSCs can be regulated by varying the porous structures of the artificial ligaments and suggests that this regulation is related to the RhoA/ROCK signaling pathway. Artificial ligaments prepared using a proper knitting method and line density may exhibit improved biocompatibility and clinical performance.