Remodeling of ACL Allografts is Inhibited by Peracetic Acid Sterilization

Abstract

Sterilization of allografts for anterior cruciate ligament (ACL) reconstruction has become an important prerequisite to prevent disease transmission. However, current sterilization techniques impair the biological or mechanical properties of such treated grafts. Peracetic acid (PAA) has been successfully used to sterilize bone allografts without these disadvantages and does not impair the mechanical properties of soft tissue grafts in vitro. We asked whether PAA sterilization would influence recellularization, restoration of crimp length and pattern, and revascularization of ACL grafts during early healing. We used an in vivo sheep model for open ACL reconstruction. We also correlated the histologic findings with the restoration of anteroposterior stability and structural properties during load-to-failure testing. PAA slowed remodeling activity at 6 and 12 weeks compared to nonsterilized allografts and autografts. The mechanical properties of PAA grafts were also reduced compared to these control groups at both time points. We conclude PAA sterilization currently should not be used to sterilize soft tissue grafts typically used in ACL reconstruction.

Tissue Processing: Role of Secondary Sterilization Techniques

“…37,38 Analyses of the mechanical function of BPTB grafts in vitro revealed no adverse effects of PAA sterilization compared with unsterilized grafts. 39 A more recent study, 40 however, found in a goat model that PAA sterilization delayed or partially inhibited the biological remodeling of PAA grafts, leading to impaired functional knee stability and reduced structural properties of the graft during subsequent healing up to 3 months. The authors recommend caution when considering PAA-sterilized allografts for ACL reconstruction.…”

Anterior Cruciate Ligament Reconstruction With Autografts Compared With Non-irradiated, Non-chemically Treated Allografts

“…39,40 Other authors have also encouraged caution with the continued widespread use of peracetic acid, which may further inhibit graft incorporation in animal models. 41 Continued clinical surveillance and US Food and Drug Administration scrutiny of current sterilization practices used by the American Association of Tissue Banks are warranted, particularly with increased use of musculoskeletal allograft tissue in current orthopaedic practice. Although debate exists, the current literature shows a trend toward a longer remodeling period and delayed biologic healing in allograft tissue when compared with autografts, [42][43][44] possibly up to 2 years or more after surgery.…”

Radiation sterilization of tissue allografts: A review

“…Several studies have demonstrated the antimicrobial efficacy of this method. Although the peracetic acid treatment is an established sterilization method of bone, dermis and amniotic membrane transplants with no evidence to impair the transplants properties, it has caused significantly reduced biomechanical strength and decreased remodeling activity in anterior cruciate ligament reconstruction tendon grafts [35] . Chemical processing and antibiotic soaks have certain limitations for sterilization of allograft tissues due to the lack of complete penetration for inactivation of deep-seated bioburden.…”