Surgical repair of the rotator cuff repair is one of the most common procedures in orthopedic surgery. Despite it
being the focus of much research, the physiological tendon-bone insertion is not recreated following repair and there is an
anatomic non-healing rate of up to 94%. During the healing phase, several growth factors are upregulated that induce cellular
proliferation and matrix deposition. Subsequently, this provisional matrix is replaced by the definitive matrix. Leukocyte-
and platelet-rich fibrin (L-PRF) contain growth factors and has a stable dense fibrin matrix. Therefore, use of LPRF
in rotator cuff repair is theoretically attractive. The aim of the present study was to determine 1) the optimal protocol
to achieve the highest leukocyte content; 2) whether L-PRF releases growth factors in a sustained manner over 28 days; 3)
whether standard/gelatinous or dry/compressed matrix preparation methods result in higher growth factor concentrations.
1) The standard L-PRF centrifugation protocol with 400 x g showed the highest concentration of platelets and leukocytes.
2) The L-PRF clots cultured in medium showed a continuous slow release with an increase in the absolute release of
growth factors TGF-β1, VEGF and MPO in the first 7 days, and for IGF1, PDGF-AB and platelet activity (PF4=CXCL4)
in the first 8 hours, followed by a decrease to close to zero at 28 days. Significantly higher levels of growth factor were
expressed relative to the control values of normal blood at each culture time point. 3) Except for MPO and the TGFβ-1,
there was always a tendency towards higher release of growth factors (i.e., CXCL4, IGF-1, PDGF-AB, and VEGF) in the
standard/gelatinous- compared to the dry/compressed group. L-PRF in its optimal standard/gelatinous-type matrix can
store and deliver locally specific healing growth factors for up to 28 days and may be a useful adjunct in rotator cuff repair.
Keywords: Fibrin, leukocytes, L-PRF, platelets, rotator cuff, shoulder, sports medicine.
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