Anterior and posterior cruciate ligament reconstruction in rhesus monkeys.

The mechanical properties of tendon autografts used in reconstruction of the anterior cruciate ligament (ACL) are reduced after surgery. Previous studies showed that growth factors such as transforming growth factor-(31 (TGF-(31) and epidermal growth factor (EGF) can stimulate fibroblast proliferation and increase collagen and noncollagenous protein synthesis by these cells. These factors might be useful, therefore, in preventing graft deterioration after transplantation or accelerating mechanical restoration of the deteriorated graft. The purpose of our study, therefore, was to clarify the effects of TGF-(31 and EGF on biomechanical properties using an in situ freeze-thaw ACL model in the rabbit. A total of 142 rabbits underwent the freeze-thaw treatment in the right ACL and were then divided into four groups. Group I served as a freeze-thaw, but otherwise untreated control. In Group 11, a delivery vehicle (fibrin sealant) alone was applied. In Group 111, 4-ng TGF-PI and 100-ng EGF mixed with the vehicle were applied, In Group IV, higher doses (2-pg TGF-(31 and 50-pg EGF) of growth factors were mixed with the vehicle. The groups were compared at 6 and 12 weeks on the basis of mechanical properties, water content, and histological and ultrastructural observations. The crosssectional area of Group 111 (average, 7.1 mm') was significantly less than that of Groups I, TI, and IV (9.0, 8.2, and 9.4 mm2, respectively) at 12 weeks. The tensile strength of Group I11 (62.2 MPa) was significantly greater than that of Groups I, 11, and IV (35.6, 43.7, and 36.9 MPa, respectively) at 12 weeks, while the water content of Group 111 (70.7'%,) was significantly lower than that of Group I (75.2%). No other significant differences occurred among Groups I, 11, and IV. A unirnodal distribution of collagen fibril diameters was noted in Groups I and 11, while a bimodal pattern was found in Group 111. This study demonstrated that low-dose application of TGF-P1 and EGF significantly inhibited not only the increased water content and cross-sectional area, but also the decreased tensile strength caused by the freeze-thaw treatment, while a high dose of TGF-PI and EGF does not have the same beneficial effects.

Section: Introductionmentioning

confidence: 99%

“…The mechanical properties of tendon autografts are reduced after surgery, and the properties remain abnormal even a year post-operatively [5,6]. Therefore, a goal in ligament reconstruction is to prevent graft deterioration *Corresponding author Tel ' +81-11-706-7211, fax +81-11-706-1822.…”

Section: Introductionmentioning

confidence: 99%

Effects of combined administration of transforming growth factor‐β1 and epidermal growth factor on properties of the in situ frozen anterior cruciate ligament in rabbits

Sakai

Yasuda

Tohyama

et al. 2002

“…Clancy et al [5] has stated that one year after reconstruction, grafts have approximately SO'%, of their pre-transfer tensile strength, inferring that initially stronger grafts have J. F. Cummings ct ul. I Journul of Ortliopurdic~ Rrwurch 20 (17002 I 33-34.5 greater post-reconstruction strength.…”

Section: Introductionmentioning

confidence: 99%

The effects of graft width and graft laxity on the outcome of caprine anterior cruciate ligament reconstruction

Cummings

Grood

Levy

et al. 2002

We studied how initial graft size and initial graft laxity alkcted the biomechanics of anterior cruciate ligament (ACL) reconstruction at six months. Sixteen goats had bilateral reconstructions staged eight weeks apart. Autografts 4 and 7 mm wide were taken from the central patellar tendon (PT). Lax grafts were created by adding 4 mm slack to the graft before fixing. We reconstructed each joint using a combination of width and laxity treatments. Both factors were changed for the contralateral joint and all combinations appeared with equal frequency. At six months we measured the joint extension limit, anterior-posterior (AP) translation, and osteoarthritic changes. The grafts were then tested to failure to determine their mechanical properties. After six months the difference in initial treatments had disappeared: there was no difference in graft cross-section due to the different initial widths and there was no difference in joint AP translation due to the initial graft laxity. We did observe that wide grafts were associated with a block to extension, decreased joint A P translation, and increased articular cartilage damage and osteophyte formation. While AP translation was reduced, it was correlated with decreased extension, possibly indicating an increase in scar tissue formation rather than a more functional graft. Neither graft width nor graft laxity produced differences in any graft mechanical properties. This suggests that the use of larger grafts to prevent increased A P translation has undesirable complications. Ultimately, we conclude that neither of these surgical treatments strongly affects the biomechanical result of caprine ACL reconstruction.

“…The bone-tendon junction is regenerated after surgical reconstruction of an enthesis [2,6,9,13,14,18,22,24,25,311. Formation of collagen fibers anchoring into bone has generally been regarded as a critical event in recovery [9,31].…”

Section: Introductionmentioning

confidence: 99%

Early anchoring collagen fibers at the bone—tendon interface are conducted by woven bone formation: light microscope and scanning electron microscope observation using a canine model

Oguma

Murakami

Takahashi-Iwanaga

et al. 2001

To clarify the early process of recovery at the bone-tendon interface, we used light microscopy and SEM to examine the process of anchoring of collagen fibers to bone in a canine model.At two weeks, tendon, scar tissue, woven bone and lamellar bone were present at the insertion site. SEM revealed anchoring of collagen fibril bundles of the scar to the woven bone. By 4 weeks, the number of anchoring fibers had increased and a parallel arrangement of fibers was observed. SEM demonstrated deep penetration of fibers into the woven bone layer. In addition, the fibers were observed to project into and intermingle with the scar tissue. By 6 weeks, the anchoring fibers had developed fully and were distributed densely over the interface. SEM also revealed that the collagen fibril bundles in the scar tissue had connected with the collagen fibrils of the woven bone by way of the anchoring bundles. The woven bone was identifiable throughout the early stages of recovery as the interface between soft tissue and hard tissue. Throughout all experimental periods, no staining was observed at the interface of the tendon and bone by Saffranin-0. The formation of woven bone was important during early recovery of the tendonbone interface prior to the completion of fibrocartilage-mediated insertion. 0