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Influence of canine recombinant somatotropin hormone on biomechanical and biochemical properties of the medial meniscus in stifles with altered stability

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  • 1 Department of Small Animal Clinical Sciences, College of Veterinary Medicine, University of Tennessee, Knoxville, TN 37901-1071.
  • | 2 Department of Small Animal Clinical Sciences, College of Veterinary Medicine, University of Tennessee, Knoxville, TN 37901-1071.
  • | 3 12430 Hartcliff St, San Antonio, TX 78249.
  • | 4 Department of Bioengineering, George R. Brown School of Engineering, Rice University, Houston, TX 77251-1892.
  • | 5 Comparative Orthopaedic Laboratory, University of Missouri, Columbia, MO 65211.
  • | 6 Comparative Orthopaedic Laboratory, University of Missouri, Columbia, MO 65211.
  • | 7 Monsanto Company, 700 Chesterfield Village Parkway, St Louis, MO 63198.

Abstract

Objective—To determine biomechanical and biochemical properties of the medial meniscus in a semistable stifle model and in clinical patients and to determine the effect of canine recombinant somatotropin hormone (STH) on those properties.

Animals—22 healthy adult dogs and 12 dogs with meniscal damage secondary to cranial cruciate ligament (CCL) rupture.

Procedure—The CCL was transected in 15 dogs, and stifles were immediately stabilized. Implants releasing 4 mg of STH/d were placed in 7 dogs, and 8 received sham implants. Seven dogs were used as untreated controls. Force plate analysis was performed before surgery and 2, 5, and 10 weeks after surgery. After 10 weeks, dogs were euthanatized, and menisci from surgical and contralateral stifles were harvested. The torn caudal horn of the medial meniscus in dogs with CCL rupture comprised the clinical group. Creep indentation determined aggregate modulus (HA), Poisson's ratio (v), permeability (k), and percentage recovery (%R). Water content (%W), collagen content (C), sulfated glycosaminoglycan (sGAG) content, and collagen type-I (cI) and -II (cII) immunoreactivity were also determined.

Results—Surgical and clinical groups had lower HA, k, %R, C, sGAG, cI, and cII and higher %W than the nonsurgical group. Surgical stifles with greater weight bearing had stiffer menisci than those bearing less weight. Collagen content was higher in the surgical group receiving STH than the surgical group without STH.

Conclusions and Clinical Relevance—Acute stabilization and moderate weight bearing of the CCL-deficient stifle appear to protect stiffness of the medial meniscus. Normal appearing menisci from CCL-deficient stifles can have alterations in biomechanical and biochemical properties, which may contribute to meniscal failure. (Am J Vet Res 2002;63:419–426)

Abstract

Objective—To determine biomechanical and biochemical properties of the medial meniscus in a semistable stifle model and in clinical patients and to determine the effect of canine recombinant somatotropin hormone (STH) on those properties.

Animals—22 healthy adult dogs and 12 dogs with meniscal damage secondary to cranial cruciate ligament (CCL) rupture.

Procedure—The CCL was transected in 15 dogs, and stifles were immediately stabilized. Implants releasing 4 mg of STH/d were placed in 7 dogs, and 8 received sham implants. Seven dogs were used as untreated controls. Force plate analysis was performed before surgery and 2, 5, and 10 weeks after surgery. After 10 weeks, dogs were euthanatized, and menisci from surgical and contralateral stifles were harvested. The torn caudal horn of the medial meniscus in dogs with CCL rupture comprised the clinical group. Creep indentation determined aggregate modulus (HA), Poisson's ratio (v), permeability (k), and percentage recovery (%R). Water content (%W), collagen content (C), sulfated glycosaminoglycan (sGAG) content, and collagen type-I (cI) and -II (cII) immunoreactivity were also determined.

Results—Surgical and clinical groups had lower HA, k, %R, C, sGAG, cI, and cII and higher %W than the nonsurgical group. Surgical stifles with greater weight bearing had stiffer menisci than those bearing less weight. Collagen content was higher in the surgical group receiving STH than the surgical group without STH.

Conclusions and Clinical Relevance—Acute stabilization and moderate weight bearing of the CCL-deficient stifle appear to protect stiffness of the medial meniscus. Normal appearing menisci from CCL-deficient stifles can have alterations in biomechanical and biochemical properties, which may contribute to meniscal failure. (Am J Vet Res 2002;63:419–426)