Effect of Implanting a Soft Tissue Autograft in a Central-Third Patellar Tendon Defect: Biomechanical and Histological Comparisons

Abstract

Previous studies by our laboratory have demonstrated that implanting a stiffer tissue engineered construct at surgery is positively correlated with repair tissue stiffness at 12 weeks. The objective of this study was to test this correlation by implanting a construct that matches normal tissue biomechanical properties. To do this, we utilized a soft tissue patellar tendon autograft to repair a central-third patellar tendon defect. Patellar tendon autograft repairs were contrasted against an unfilled defect repaired by natural healing (NH). We hypothesized that after 12 weeks, patellar tendon autograft repairs would have biomechanical properties superior to NH. Bilateral defects were established in the central-third patellar tendon of skeletally mature (one year old), female New Zealand White rabbits (n = 10). In one limb, the excised tissue, the patellar tendon autograft, was sutured into the defect site. In the contralateral limb, the defect was left empty (natural healing). After 12 weeks of recovery, the animals were euthanized and their limbs were dedicated to biomechanical (n = 7) or histological (n = 3) evaluations. Only stiffness was improved by treatment with patellar tendon autograft relative to natural healing (p = 0.009). Additionally, neither the patellar tendon autograft nor natural healing repairs regenerated a normal zonal insertion site between the tendon and bone. Immunohistochemical staining for collagen type II demonstrated that fibrocartilage-like tissue was regenerated at the tendon-bone interface for both repairs. However, the tissue was disorganized. Insufficient tissue integration at the tendon-to-bone junction led to repair tissue failure at the insertion site during testing. It is important to re-establish the tendon-to-bone insertion site because it provides joint stability and enables force transmission from muscle to tendon and subsequent loading of the tendon. Without loading, tendon mechanical properties deteriorate. Future studies by our laboratory will investigate potential strategies to improve patellar tendon autograft integration into bone using this model.

Mechanical properties of murine and porcine ocular tissues in compression

“…Thus, directing stem cell differentiation and cellular proliferation with mechanical cues (Zoldan et al 2011, Lee et al 2013) has long been utilized for generating cartilage (Little et al 2011) and bone (Parekh et al 2011). More recently this concept has also been applied to materials meant to regenerate softer tissues such as tendons (Kinneberg et al 2011), cardiac valves (Wang et al 2013), cardiac muscles (Guillemette et al 2010, Chen et al 2008), and neurons (Banerjee et al 2009, Yao et al 2013). In order to obtain an optimal match between implant and native tissue, therefore, the mechanical properties of the native tissue need to be thoroughly characterized in normal and diseased states.…”

Murine patellar tendon biomechanical properties and regional strain patterns during natural tendon-to-bone healing after acute injury

“…Gradations in matrix composition, collagen alignment, cell phenotype, and mineralization (Genin et al, 2009; Thomopoulos et al, 2003; Thomopoulos et al, 2006) help facilitate optimal force transmission while also dissipating potentially damaging interfacial stress concentrations between these mechanically dissimilar materials (Liu et al, 2011; Shaw and Benjamin, 2007). Unfortunately, once disrupted, the insertion site does not regenerate its complex natural architecture and is instead replaced by scar tissue, resulting in a mechanically inferior interface that is susceptible to further injury (Galatz et al, 2006; Kinneberg et al, 2011; Newsham-West et al, 2007; Rodeo et al, 1993). …”

Razones para la cirugía precoz en las luxaciones acromioclaviculares tipo iii

“…Por un lado, la potencial alteración de la biomecánica escapulotorácica comprometiendo tanto el futuro del hombro como el resultado funcional de cualquier tratamiento una vez se ha establecido el cuadro, y por otro, el conocimiento de que el tejido cicatricial de los ligamentos rotos será de peores características biomecánicas a las originales 18 , siendo el aporte de colágeno autólogo una de las opciones de mejorar la calidad de esa cicatrización 19 .…”