The medial opening-wedge high tibial osteotomy (OW-HTO) is an accepted option to treat the isolated medial compartment osteoarthritis (OA) in varus knee. Despite satisfactory outcomes were described in literature, consistent complication rate has been reported and the provided accuracy of coronal alignment correction using conventional HTO techniques falls short. Patient specific instrumentations has been introduced with the aim to reduce complications and to improve the intra-operative accuracy according to the pre-operative plan, which is responsible for the clinical result of the surgery. In this talk, an overview of the clinical results of HTO patient specific instrumentation available in literature will be performed. Moreover, preliminary intra-operative and clinical results of a new customised 3-D printed cutting guide and fixation plate for OW-HTO will be presented

Summary Statement. Preoperative bone-marrow-derived cell mobilization by G-CSF is a safe orthopaedic procedure and allows circulation in the blood of high numbers of CD34+ve cells, promoting osseointegration of a bone substitute. Introduction. Granulocyte-colony-stimulating-factor(G-CSF) has been used to improve repair processes in different clinical settings for its role in bone-marrow stem cell(CD34+ and CD34-) mobilization. Recent literature suggests that G-CSF may also play a role in skeletal-tissue repair processes. Aim of the study was to verify the feasibility and safety of preoperative bone-marrow cell (BMC) mobilization by G-CSF in orthopaedic patients and to evaluate G-CSF efficacy in accelerating bone regeneration following opening-wedge high tibial valgus osteotomy(HTVO) for genu varum. Patients/Methods. 24 patients were enrolled in a prospective phase II trial. The osteotomy gap was filled by a hydroxyapatite-tricalciumphosphate bone substitute(HATriC). Patients were randomised to receive (GROUP A) or not receive (GROUP B) preoperatively a daily dose of 10µg/kg of G-CSF for three consecutive days, with an additional dose 4 hours before surgery. BMC-mobilization was monitored by white blood cell (WBC)-count, flow-cytometry analysis of circulating CD34+cells and Colony-forming cell assays. Patients were evaluated by: Lysholm and SF-36 scores preoperatively and at 1, 2, 3, 6, and 12 months after surgery;. X-ray evaluation preoperatively and at 1, 2, 3, 6, and 12 months after surgery, in order to compare the percentage of osseointegration of the bone-graft junction using the semi-quantitative score of Dallari[1]. CT-scan of the host bone-substitute interface at 2 months, in order to estimate the quality of the newly formed bone at the bone-graft junction by a quantitative measure of bone density (by Hounsfield unit) at the proximal and distal bone-graft junctions. Results. All patients completed the treatment program without major side effects; G-CSF was well tolerated. BMC-mobilization occurred in all Group A patients, with median peak values of 110/µL (range 29–256) of circulating CD34+ve cells. Circulating clonogenic progenitors paralleled CD34+ve cell levels. A significant improvement in the SF-36-Role-Physical scale and in the Lysholm score was recorded at follow-up in Group A compared to Group B(p<0.05). At the X-ray-evaluation, there was a significant increase in osseointegration at the bone-graft junction in Group A at 1, 2, 3 and 6 months post-surgery compared to Group B(p<0.05). CT-scans of the grafted area at 2 months post-surgery showed no significant difference in the quality of the newly formed bone between the two Groups. Discussion/Conclusions. These results suggest that G-CSF can be safely administered preoperatively in subjects undergoing HTVO. In addition, the clinical, radiographic and CT monitoring indicate that preoperative G-CSF administration promotes bone graft substitute osseointegration. Enhanced osseointegration might be the result of the direct activity of G-CSF on the host bone or a cellular effect mediated by bone marrow-derived progenitors mobilised by G-CSF, or by a combination of all these factors. This study is a proof-of-principle that preoperative G-CSF might be an alternative treatment option to enhance bone regeneration in the field of bone marrow stem cell therapy and reconstructive orthopaedic surgery