How Four Weeks of Implantation Affect the Strength and Stiffness of a Tendon Graft in a Bone Tunnel

Singhatat, Wamis; Lawhorn, Keith W.; Howell, Stephen M.; Hull, Maury L.

doi:10.1177/03635465020300041001

Cited by 92 publications

(83 citation statements)

References 19 publications

(45 reference statements)

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“…The sheep and goat have commonly been chosen as animal models for the knee [30][31][32][33] because of anatomical [34][35][36][37] and mechanical [38][39][40][41] similarities to human ACLs. These sheep were obtained from the Michigan Livestock Exchange, various farms in the area or intra-university transfer.…”

Section: Animal Model and Animal Carementioning

confidence: 99%

Three-Dimensional Engineered Bone–Ligament–Bone Constructs for Anterior Cruciate Ligament Replacement

Smietana

Kostrominova

et al. 2012

Tissue Engineering Part A

114

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The anterior cruciate ligament (ACL), a major stabilizer of the knee, is commonly injured. Because of its intrinsic poor healing ability, a torn ACL is usually reconstructed by a graft. We developed a multi-phasic, or boneligament-bone, tissue-engineered construct for ACL grafts using bone marrow stromal cells and sheep as a model system. After 6 months in vivo, the constructs increased in cross section and exhibited a well-organized microstructure, native bone integration, a functional enthesis, vascularization, innervation, increased collagen content, and structural alignment. The constructs increased in stiffness to 52% of the tangent modulus and 95% of the geometric stiffness of native ACL. The viscoelastic response of the explants was virtually indistinguishable from that of adult ACL. These results suggest that our constructs after implantation can obtain physiologically relevant structural and functional characteristics comparable to those of adult ACL. They present a viable option for ACL replacement.

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Section: Animal Model and Animal Carementioning

confidence: 99%

Three-Dimensional Engineered Bone–Ligament–Bone Constructs for Anterior Cruciate Ligament Replacement

Smietana

Kostrominova

et al. 2012

Tissue Engineering Part A

114

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“…Once the graft has been biologically incorporated into the bone tunnels, the stiffness of fixation may either increase or decrease depending on the fixation device [36].…”

Section: Importance and Interpretutionmentioning

confidence: 99%

How the fixation method stiffness and initial tension affect anterior load?displacement of the knee and tension in anterior cruciate ligament grafts: a study in cadaveric knees using a double-loop hamstrings graft

EAGAR

2004

Journal of Orthopaedic Research

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There were two objectives to this study. The first was to investigate the relationship of graft fixation stiffness and graft initial tension on the anterior load-displacement behavior of knees reconstructed with a double-loop hamstrings tendon graft. The second was to determine the corresponding graft tensions at 225 N of anterior force applied to the knee. To satisfy these objectives, the anterior-load displacement curves were measured for seven cadaveric knees with the ACL intact a t flexion angles ranging from 0" to 90". The ACL was reconstructed in the same knees using a double-loop hamstrings graft. A/P load-displacement curves of the knee and graft tension were measured as the fixation method stiffness and the initial tension applied at full extension were varied (25-326 N/mm and 25-300 N). The 0 N posterior limit (unloaded position of tibia) and the anterior laxity (difference between the 0 N posterior limit and 225 N anterior limit) were computed to characterize the A/P load-displacement of the intact and reconstructed knees. The key results were that the 0 N posterior limit of the tibia was insensitive to changes in stiffness (p > 0.6503) but that increasing initial tension caused increasing posterior subluxation of the tibia with respect to the femur (p = 0.0001). The tibia was subluxed posteriorly by 5-6 mm on average at high levels of initial tension. Both initial tension and stiffness significantly affected the anterior laxity (p = 0.0001 for both factors). Anterior laxity was restored closely to normal (i.e. < I mm difference) by relatively high initial tension of 200 N in combination with low stiffness of 25 N/mm and by low initial tension of 25 N in combination with higher stiffness ranging between 94 and 326 Nlmm. When anterior laxity is restored to normal using a high initial tension-low stiffness combination however, the tibia undergoes a large posterior subluxation with respect to the femur in the unloaded state (approximately 5 mm) and a relatively high graft tension of 275 N is developed at 225 N of anterior force. Both the tibial subluxation and graft tension are reduced substantially with low initial tension-higher stiffness combinations because the amount of initial tension required to restore anterior laxity to normal is reduced by about 200 N.

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“…The factors that influence the healing of a tendon within a bone tunnel are many and include the amount of the tendon within the tunnel at the time of surgery, the initial fit of the tendon within the tunnel, the length of time from implantation and the fixation methods used. To our knowledge, only one study [9] has compared the biomechanics of two fixation devices at the time of implantation and three weeks later; this study served as a model for the present study. In that study, Singhatat et al [9] demonstrated that the biomechanical properties of a complex measured after implantation are not the same as those measured at implantation and may either deteriorate or improve, depending on the type of fixation, either distant from the joint entrance (suspended fixation) or near the tunnel entrance (aperture or anatomical fixation).…”

Section: Discussionmentioning

confidence: 99%

“…To our knowledge, only one study [9] has compared the biomechanics of two fixation devices at the time of implantation and three weeks later; this study served as a model for the present study. In that study, Singhatat et al [9] demonstrated that the biomechanical properties of a complex measured after implantation are not the same as those measured at implantation and may either deteriorate or improve, depending on the type of fixation, either distant from the joint entrance (suspended fixation) or near the tunnel entrance (aperture or anatomical fixation). Among the devices tested by the authors, the WasherLoc (Arthrotek, Warsaw, Indiana, USA), which provided a suspended fixation, maintained its strength and improved its stiffness three weeks after implantation, while the BioInterference Screw (Arthrex, Naples, Florida, USA) significantly lost its strength and stiffness after implantation.…”

Section: Discussionmentioning

confidence: 99%

“…Moreover, a labora-which is still considered the weak point of this technique. Although several studies [5] investigated the biomechanics of the initial strength and stiffness of various devices for tibial fixation of hamstring grafts, very few in vivo studies [4,[6][7][8][9] dealt with the effect of a fixation device on healing of a tendon graft to the bone tunnel and how strength and stiffness of the complex (tendon-devicebone) change after implantation.…”

Section: Introductionmentioning

confidence: 99%

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How four and twelve weeks of implantation affect the strength and stiffness of a tendon graft securely fixed in a bone tunnel: a study of Evolgate fixation in an extra-articular model ovine model

Ferretti

Monaco

Labianca

et al. 2006

J Orthopaed Traumatol

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Healing of a tendon graft to a bone tunnel is slower than the healing of a bone plug. Therefore, the device chosen for hamstring fixation may need to maintain its strength and stiffness longer than the device chosen for bone-tendon-bone fixation. We evaluated, in an extraarticular ovine model, how 4 and 12 weeks of implantation affect the strength of a tendon graft fixed to bone with the Evolgate. The long digital extensor tendon was transplanted and fixed with the Evolgate into a 30-mm long, 8 mm diameter bone tunnel drilled in the tibial metaphysis of both posterior limbs of 15 skeletally mature Suffolk sheep. Immediately after implantation, and 4 and 12 weeks later, biomechanical cyclic load tests in 50 N increments were performed until failure to evaluate the ultimate failure load (UFL). Histological analysis was also performed at 4 and 12 weeks. Biomechanical tests revealed a UFL of 339±120 N at time 0, and increases to 635±19 N (4 weeks) and to 867±80 N (12 weeks). The differences between all 3 groups were significant (p<0.001, paired t test). The histological evaluation showed a layer of cellular, fibrous tissue between the tendon and the bone, along the length of the bone tunnel; this layer progressively matured and reorganized during the healing process. The collagen fibers that attached the tendon to the bone resembled Sharpey's fibers. The strength of the interface significantly and progressively increased between weeks 4 and 12 after transplantation, and was associated with a degree of bone ingrowth noted histologically. The use of the Evolgate seems not to interfere with the bone ingrowth after implantation, allowing an improvement in strength of the bonetendon-device complex.

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How Four Weeks of Implantation Affect the Strength and Stiffness of a Tendon Graft in a Bone Tunnel

Abstract: The pace of rehabilitation may need to be adjusted based on the type of fixation device used to secure a soft tissue graft.

Cited by 92 publications

References 19 publications

Three-Dimensional Engineered Bone–Ligament–Bone Constructs for Anterior Cruciate Ligament Replacement

Three-Dimensional Engineered Bone–Ligament–Bone Constructs for Anterior Cruciate Ligament Replacement

How the fixation method stiffness and initial tension affect anterior load?displacement of the knee and tension in anterior cruciate ligament grafts: a study in cadaveric knees using a double-loop hamstrings graft

How four and twelve weeks of implantation affect the strength and stiffness of a tendon graft securely fixed in a bone tunnel: a study of Evolgate fixation in an extra-articular model ovine model

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