Increased platelet concentration does not improve functional graft healing in bio-enhanced ACL reconstruction

Abstract

Purpose The use of an extra-cellular matrix scaffold (ECM) combined with platelets to enhance healing of an ACL graft (“bio-enhanced ACL reconstruction”) has shown promise in animal models. However, the effects of platelet concentration on graft healing remains unknown. The objectives of this study were to determine if increasing the platelet concentration in the ECM scaffold would; 1) improve the graft biomechanical properties, and 2) decrease cartilage damage after surgery. Methods Fifty-five adolescent minipigs were randomized to 5 treatment groups; untreated ACL transection (n=10), conventional ACL reconstruction (n=15), and bio-enhanced ACL reconstruction using 1X (n=10), 3X (n=10) or 5X (n=10) platelet-rich plasma. The graft biomechanical properties, anteroposterior (AP) knee laxity, graft histology and macroscopic cartilage integrity were measured at 15 weeks. Results The mean linear stiffness of the bio-enhanced ACL reconstruction procedure using the 1X preparation was significantly greater than traditional reconstruction while the 3X and 5X preparations were not. The failure loads of all the ACL reconstructed groups were equivalent but significantly greater than untreated ACL transection. There were no significant differences in the ligament maturity index or AP laxity between reconstructed knees. Macroscopic cartilage damage was relatively minor, though significantly less when the ECM-platelet composite was used. Conclusions Only the 1X platelet concentration improved healing over traditional ACL reconstruction. Increasing the platelet concentration from 1X to 5X in the ECM scaffold did not further improve the graft mechanical properties. The use of an ECM-platelet composite decreased the amount of cartilage damage seen after ACL surgery.

Sex Influences the Biomechanical Outcomes of Anterior Cruciate Ligament Reconstruction in a Preclinical Large Animal Model

“…16 Therefore, separate analyses were conducted on the animals that received conventional ACL reconstruction and those that underwent bio-enhanced ACL reconstruction. Female pigs had a greater degree of cartilage damage after conventional ACL reconstruction than their male counterparts (Figure 5).…”

“…16 Complete transaction was confirmed by a positive Lachman test. Conventional ACL reconstruction was performed using fresh-frozen bone-patellar tendon-bone allografts from age-, weight-, and sex-matched donors.…”

“…Following IACUC approval, 41 normal adolescent Yucatan mini-pigs (23 Males, 18 Females; Age: 15±1months; Weight: 48.0±9.6 Kg) underwent unilateral ACL transection and were randomly assigned to one of 4 treatment groups: 16 conventional ACL reconstruction (n=13; 8 males, 5 females), or bio-enhanced ACL reconstruction with 1× (n=10; 7 males, 3 females), 3× (n=9; 3 males, 6 females) and 5× (n=9; 5 males, 4 females) platelet-rich plasma (PRP). The surgical knee was randomly selected, and the contralateral ACL-intact knee served as a control.…”

“…Conventional ACL reconstruction was performed using fresh-frozen bone-patellar tendon-bone allografts from age-, weight-, and sex-matched donors. 16 The entire patellar tendon (∼10 mm in width) was used for the soft tissue portion of the graft with trimmed bone plugs. Femoral and tibial tunnels were created in the standard positions for ACL reconstruction, with the tibial tunnel exiting in the center of the tibial ACL attachment and the femoral tunnel placed in the center of the femoral ACL attachment site.…”

“…16 Surgeries were done by an experienced board-certified orthopaedic surgeon (MMM), fellowship trained in sports medicine, to ensure consistency in all surgical factors including tunnel placement and graft tension. All animals were housed in individualized pens and periodically checked for 15 weeks post-surgery.…”