Introduction: Platelet-rich plasma (PRP) is a platelet concentration obtained from a few millilitres of blood. It releases several growth factors and can enhance tissue repair(). The aim of the study was to evaluate the efficacy and the safety of PRP in the treatment of experimental induced muscle lesions.

Materials and Methods: 22 adult Wistar rats were used. Blood collected from 2 rats was mixed with citrate-phosphate-dextrose and centrifuged to a gel consistency. Growth factor release was stimulated by the addition of CaCl and thrombin. Identical bilateral incisions were performed on the longissimum dorsi muscle of 20 Wistar rats. Each site was marked by placing a hollow PVC vessel containing PRP on the bottom of the defect. An empty marker was placed on the bottom of the contralateral lesion, as control. Animals were killed 40 or 60 days from surgery. Muscle samples were stained with haematoxylin-eosin. Histomorhometric parameters investigated were: number of regenerating fibres, amount of neoangiogenesis and fibrous tissue, presence of inflammatory cells, metaplasia, calcification and ossification (Leika, Quantimet SD).

Results: Treated muscles exhibited greater neoangiogenesis and a larger number of miocytes in regenerating phase compared with controls. Both groups showed a similar amount of fibrous tissue and some inflammatory cells. Metaplasia, ossification or heterotopic calcification were seen in none of the samples.

Conclusions: To our knowledge this is the first investigation of PRP in muscle healing. Data showed that PRP is effective in improve muscle healing without adverse local effects. Additional experiments are in progress in view of a clinical trial.

Aims: Degradation of articular cartilage in gonarthritis seems to be modiþable pharmacologically. For these to be helpful, early diagnosis is essential. Weight bearing radiograms obtained at various degrees of ßexion, have shown to provide more information about joint space narrowing (JSN). Methods: Between March and November 2001, 28 consecutive patients whom have been admitted to hospital for knee surgery due to knee osteoarthritis, enrolled for study. Their mean age was 57.5 years (in range of 35–78). Extension weight bearing A/P, lateral and tangential views were made on standard examinations. 30û Flexion standing P/A, and at 45û ßexion standing P/A knee xÐrays were made with the consent of patient. Surgical þndings of the cartilage (Outerbridge classiþcation) were compared with radiological þndings. Results: The statistical evaluations revealed that there is no signiþcant correlation between JSN and observed clinical osteoarthritis level at MFC, LFC, and LTP. A signiþcant correlation was found between the degree of JSN measured at weight-bearing A/P, 30û ßexion P/A and 45û ßexion P/A radiographs and the degree of cartilage degradation at MTP (p< 0.05). The semifelxion radiograms were found to demonstrate Conclusions: Radiograms taken at weight-bearing semißexed positions are more effective than standing A/P knee x-rays, in demonstrating the JSN, and JSN þnding is associated only with the medial compartment gon-arthritis. We concluded that the degree of ßexion (30û–45û) during radiographic examination is not an important factor and for the evaluation of the lateral compartment new positions should be deþned.