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The use of type I collagen to activate clotting of PRP may be a safe and effective alternative to bovine thrombin. The use of collagen results in less clot retraction and equal release of PDGF-AB and VEGF compared with currently available methods of clot activation.

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Platelets and erythrocytes are major components of wound provisional scaffolding. In this study, we hypothesized that the concentration of platelets and erythrocytes would significantly affect fibroblast-mediated contraction of three-dimensional scaffolds or the release of cytokines from the scaffold. To test this hypothesis, human anterior cruciate ligament fibroblasts were cultured in one of four scaffolds: a collagen matrix, a collagen-fibrin matrix containing the same concentration of platelets as whole blood, a collagen-fibrin matrix containing a high platelet concentration, and a collagen-fibrin matrix containing a high platelet concentration and red blood cells. Cytokine release from the four groups of gels and gel contraction were measured over a 10-day period. The results of these assays supported greater cytokine release, fibroblast proliferation, and gel contraction in scaffolds with higher platelet concentration. In contrast, the addition of erythrocytes did not significantly stimulate or suppress scaffold contraction or growth factor release from the provisional scaffolds. We concluded that while platelet concentration can significantly impact cytokine release and scaffold retraction in a provisional scaffold, the inclusion of erythrocytes does not have a significant effect on these same behaviors. Therefore, while platelets may be an important regulator of repair processes after injury, it is less likely that erythrocytes have a similar function.Enhancing healing of ligaments using growth factors has been an area of great interest and research. While the majority of studies have focused on the use of a single growth factor to stimulate healing, 1,2 the natural wound healing process is an orchestration of multiple growth factors released by platelets and other cells over time. 3 To try to reproduce this in the in vitro and in vivo environment, prior investigators have looked at sustained release carriers 1,4 and viral vectors 5 for release of these cytokines over days or weeks, as well as examining applications of multiple growth factors. 6,7 These studies have shown some additive effects of applied combinations of growth factors on the wound healing of ligaments; however, even with advanced application techniques, the myriad possible combinations of growth factors, timing of release, and concentration of release make optimization of these systems a complex and daunting task.An alternative method recently used to stimulate healing of the anterior cruciate ligament (ACL) is the application of a substitute provisional scaffolding material containing platelets, NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author Manuscript erythrocytes, and plasma proteins to the injured tissue. 8 Each of these elements is likely to have a significant role in wound healing. When platelets are activated by the exposed collagen of a ligament injury, they begin to aggregate and release multiple growth factors including platelet-derived growth factor (PDGF-AA, PDGF-AB, PDGF-BB), 3 members of the transfo...

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Purpose To determine in-vivo effects of modifications to core and epitendinous suture techniques in a canine intrasynovial flexor tendon repair model using clinically relevant rehabilitation. Our null hypothesis was that gap formation and rupture rates would remain consistent across repair techniques. Methods We evaluated gap formation and rupture in 75 adult mongrel dogs that underwent repair of intrasynovial flexor tendon lacerations followed by standardized post-operative therapy. The current suture technique was a 4-0, 8-strand core suture with a purchase of 1.2 cm and a 5-0, epitendinous suture repair with a 2 mm purchase length and depth. Gap and failure were compared by chi-squared analysis to a historical group of in-vivo repairs (n=76) from the same canine model using 8-strand core suture repair with purchase of 0.75 cm and 6-0 epitendinous suture with a 1 mm purchase length and depth. Results Ninety-three percent of tendons (n = 70) demonstrated gapping of <3 mm using the current suture technique. Five percent of tendons (n = 4) had a gap of 3 mm or greater, and there was 1 repair site failure. This was significantly improved over the comparison group of historical 8-strand core repair technique which resulted in 82% (n = 62) and 81% (n=112) of repairs with a gap of <3 mm and 7 failures (9%). Conclusions In an in-vivo model, current modifications of suture techniques for intrasynovial flexor tendon repair demonstrated significant improvements in gap formation and rupture compared to a similar technique using shorter purchase lengths and shallower purchase depth. Clinical Relevance Suggested repair modifications for the treatment of Zone 2 flexor tendon transections demonstrate improvements in gap formation and tendon rupture in-vivo.

Introduction Rupture of the extensor pollicis longus (EPL) tendon has been reported in the setting of distal radius fracture, chronic inflammatory arthritis, following steroid injection, and with excessive or repetitive activities. Truly, spontaneous EPL rupture, without an identifiable predisposing factor, has rarely been reported. Methods We present a retrospective case series of eight patients with spontaneous EPL rupture who were treated in our institution. Results The majority of the cases were female (75 %, n=6), and the nondominant (75 %, n=6) hand was most commonly involved. No identifiable predisposing factor could be identified in four patients. While four patients reported a history of a fall, radiographs failed to demonstrate skeletal abnormality in all four cases. No additional pathology could be identified at the time of surgery. Patients were treated using tendon transfer (n=7) or interpositional graft (n=1). There has been no case of clinical recurrence in the mean of 74.8 months (range 23-140 months) follow-up period. ConclusionThe EPL tendon is at risk for spontaneous rupture even in the absence of identifiable predisposing risk factor. Rather than pure mechanical irritation, vascular and metabolic factors may also play a substantial role in the etiology of this uncommon diagnosis.