A comparison of patellar tendon autograft and allograft used for anterior cruciate ligament reconstruction in the goat model

Abstract

Similar-sized patellar tendon autografts and fresh-frozen allografts were used to reconstruct the anterior cruciate ligament of one knee in 40 female goats. Evaluations of the reconstructions and contralateral controls at the 6-week and 6-month postoperative periods included anterior-posterior translation, mechanical properties determined during tensile failure tests, measurement of cross-sectional area, histology, collagen fibril size and area distribution, and associated articular cartilage degenerative changes. Six months after anterior cruciate ligament reconstruction, the autografts demonstrated a smaller increase in anterior-posterior displacement, values of maximum force to failure two times greater, a significant increase in cross-sectional area, a more rapid loss of large-diameter collagen fibrils, and an increased density and number of small-diameter collagen fibrils compared to the allografts. Clinical significance. More surgeons are allowing their patients to return to running and sports 6 months after anterior cruciate ligament reconstruction. While the structural and material properties of autografts and allografts at time zero are similar, in the goat model during the first 6 months they differ. The allografts demonstrate a greater decrease in their implantation structural properties, a slower rate of biologic incorporation, and the prolonged presence of an inflammatory response. At 6 months the autograft demonstrates a more robust biologic response, improved stability, and increased strength to failure values.

Remodeling of ACL Allografts is Inhibited by Peracetic Acid Sterilization

“…This led to impaired functional knee stability and reduced structural properties of PAA grafts during subsequent healing up to 3 months. Our finding of inhibited graft remodeling due to PAA sterilization confirms findings of several other authors' [1,12,35] and our own report [22] of nonsterilized allo-and autograft ACL reconstructions in vivo. Both graft types undergo a maturation process, which is characterized by overall hypocellularity and hypervascularity as early as 6 weeks postoperatively, and a significant recellularization and revascularization that occurs from the periphery towards the center of the grafts [22].…”

“…Both graft types undergo a maturation process, which is characterized by overall hypocellularity and hypervascularity as early as 6 weeks postoperatively, and a significant recellularization and revascularization that occurs from the periphery towards the center of the grafts [22]. By 12 weeks, the cellularity of the intact ACL was restored in autografts [1,12,35] and allografts [1,12,35] and that hypervascularity remained. This graft maturation has been defined as the ligamentization process [1,12,35].…”

“…By 12 weeks, the cellularity of the intact ACL was restored in autografts [1,12,35] and allografts [1,12,35] and that hypervascularity remained. This graft maturation has been defined as the ligamentization process [1,12,35]. In contrast, PAA graft cellularity only slightly increased during early healing and did not recover to values of the intact ACL, while graft vascularity never exceeded the values for the intact ACL and substantially lagged behind nonsterilized ACL alloand autografts [1,12,35].…”

“…This graft maturation has been defined as the ligamentization process [1,12,35]. In contrast, PAA graft cellularity only slightly increased during early healing and did not recover to values of the intact ACL, while graft vascularity never exceeded the values for the intact ACL and substantially lagged behind nonsterilized ACL alloand autografts [1,12,35]. The longer crimp of ACL autoand allografts than in the intact ACL, appears characteristic for the time of simultaneous degradation and reorganization of the extracellular matrix [7].…”

The effect of initial graft tension on the biomechanical properties of a healing ACL replacement graft: A study in goats

“…44.3 & 6.2 kg; mean& SD) were used for this study. The goat was chosen for this study because, unlike the canine and rabbit models, ACL reconstructions have been deemed successful out to three years with very low rates of graft failures or severe articular cartilage degeneration [23,33,34]. All goats were required to pass a veterinary examimtion to rule out any physical or physiological abnormalities prior to testing.…”