The perichondrial ring as a reservoir for precartilaginous cells. In vivo model in young chicks’ epiphysis

Background: The purpose of this study is to illustrate the routes of migration of precartilaginous cells from the perichondrial ring of LaCroix, as a potential reservoir for growth-plate germ cells. Methods: Chondrocytes derived from the ring of LaCroix of young chicks’ proximal tibia were cultured in vitro and transfected with adenovirus vector containing the gene encoding for Escherichia coli (beta)-galactosidase (lacZ) gene, which allows assessment of the migratory routes of these cells. The lacZ- transfected cells were injected back into the perichondrial ring of LaCroix of young chicks’ proximal tibias. Four weeks later the migration root was assessed microscopically. Results: Injection of cells derived from the ring of LaCroix of neonate chicks, transfected in culture with adenoviruses containing LacZ reporter gene, allows the assessment of migratory potential of these cells. Stained cells were found at the outer layer of the epiphysis, particularly in areas adjacent to the perichondrial ring. Further longitudinal histopathological studies along the bone axis demonstrated a condensed layer of the stained cells arranged horizontally along parts of the physis. Conclusion: The perichondrial ring of LaCroix represents a potential reservoir of growth-plate germ cells in young chicks

Percutaneous pinning using threaded pins as a treatment option for unstable two- and three-part fractures of the proximal humerus: a retrospective study

A retrospective study was designed to evaluate the results of closed reduction and percutaneous pinning using threaded pins as a treatment option for fractures of the humeral head. Patients who suffered two- and three-part fractures of the proximal humerus treated by this method of fixation were included. Fifty patients (32 females and 18 males) with an average age of 50 years were clinically evaluated at an average of 2.5 years after this procedure (range 1–4 years). The Constant score was used to evaluate the clinical outcome. Preoperative and postoperative X-rays were also assessed. Out of 50 patients, 18 (36%) obtained excellent results, 17 (34%) good results, eight (16%) fair results and seven (14%) achieved only poor results. The average Constant score was 81 (range 60–100). Fractures confined to the surgical or anatomical neck generally did better than those associated with a greater tuberosity fragment (average score 86 versus 78). Patients who required shaft stabilisation and in addition to reduction and fixation of the greater tuberosity showed a lower average score (68). There were no cases of avascular necrosis, neurovascular complications or deep infections. A significant loss of fracture position due to failure of internal fixation occurred in seven cases, three of these patients underwent revision surgery. Closed reduction and percutaneous pinning offers a good fracture position and stability with minimal soft tissue damage. We recommend that displaced two- and three- part fractures of the humeral head should be treated in this manner. However these patients should be monitored closely for a period of four weeks, since secondary displacement and failure of fixation can occur in this period. Careful patient selection may minimise these complications