HTO could be improved upon to allow an earlier return to activities by patients and to achieve better rates of healing - both in terms of time and maturity of the regenerated bone. Ellipse Technologies have devised a new nail system for high tibial osteotomy that differs from the established 'locked' plate and nail systems. Their system functions in a more gradual fashion. The wedge is created in the tibia as per normal but then the Ellipse nail is inserted and per day the nail is extended in small measures (appr 1.5 mm per day) until the desired correction has been achieved. Currently the new Ellipse system is being trialed in various countries in Europe, including the Netherlands and the UK. The main Ellipse trial is seeking to establish whether the corrective power of this medical device is more accurate than the plate/nail systems in use at present. The degree of bone regeneration in the open wedge is reported on, but not in detail - e.g. by one reporting radiologist - and by using standard X-ray imaging which is primarily used for angle measurements.