Introduction and Objectives: meniscal lesions in the avascular zone are difficult to heal because of the poor biological potential of the avascular tissue. Little is known about the molecular mechanisms that develop after a meniscal lesion in this low activity zone. The purpouse of this study is to determine the levels of gene expression of five different growth factors (IGF, IL-1β; TGF-β, PDGF-β and VEGF) in the first three weeks after a meniscal lesion in the avascular zone of rabbit menisci.

Materials and Methods: 28 white female New Zealand rabbits were used in this study. Through a small arthrotomy a 5mm longitudinal lesion was performed in the avascular zone of the anterior horn of the medial meniscus of each rabbit. The rabbits were sacrificed after 0, 1, 3, 7, 14 and 21 days (4 rabbits each). After sacrifice, the zone in which the meniscal lesion was performed was disected from the rest of the mensicus. It was then divided in two parts: a peripheric vascular zone and a central avascular zone. After ARNm extraction cuantitative PRC anaylisis with Sybergreen technology was performed using specific primers for each gene.

Results: There were significant expression increases of IGF, TGF-β and PDGF-β, in the vascular zone at two weeks but no variations of note in these genes in the avasacular zone. The expression of IL-1β is increased in the first day after injury in both zones but only last up to the thrid day in the vascular zone. There is an increase in VEGF expresion in the avascular zone at two weeks that is related to a symetric decrease in the vascular zone.

Introduction and Objectives: patellar tendinopaty (or jumper’s knee) is a frequent problem that affects active young adults. In some cases the different conservative treatment options are innefective and surgical treatment is considered. The purpouse of this study is to determine if repeated intratendinous inyections of platelet rich plasma (PRP) are effective for the treatment of these refractary cases.

Materials and Methods: Eight consecutive patients (4 males and 4 females, mean age 24+/−5,9) who presented refractary patellar tendinopathies were included. All patients had presented symptoms for at least 6 months and had recieved treatmet for at least 3 months. All patients had been subjected to activity limitation, physical therapy, NSAID’s and laser and ultrasound therapy. In 3 cases corticosteroid inyections had been used. The subjects were assesed before treatment and 3 months and one year later with a Visual Analoge pain Scale (0 to 100mm, VAS), the Victorian Institute of Sport Assessment Patellar tendinopathy assesment scale(VISA-P) and the Lysholm score. Treatment consisted of 3 infiltrations (one week apart) of 3 cm3 of PRP extracted from their own blood with the GPS^® system (Biomet, Warsaw, Indiana, U.S.A). The PRP was infiltrated at the level of the tender tendon and inmediately behind the tendon at the proximal tendinous insertion and 1 cm distal to it through a single cutaneous puncture.

Results: Of the 8 patients, 7 presented a significant increase (more than 20 points) in the VISA-P score and 1 did not present any noticeable improvement. No complications related to the injections were observed. The VISA-P score increased from a pretreatment mean of 29 +/− 10.7 to 79 +/− 10.7 at one year (significant differences, p< 0.001). A similar decrease was observed in the VAS pain score (pretreatment values of 75+/−28 to one year values of 21+/−19). There were not significat differences in the Lysholm score.

Conclusions: PRP seems to be a possible alternative to surgical treatment in refractary patellar tendinopathy.