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The reverse planning method was used in the author's center in more than 500 cases of deformity correction and lower extremity lengthening using the Fitbone intramedullary lengthening nail, but the planning and surgical principles are applicable to lengthening and deformity correction with other intramedullary straight devices or for "lengthening over a nail" procedures.

Objective. It is currently unknown whether human cartilage properties change during short periods of partial load bearing. We used a post-ankle fracture model to explore whether changes in cartilage morphology occur in the knee under conditions of partial load bearing.Methods. The knees of 20 patients with Weber type B and type C fractures were examined using magnetic resonance imaging. The first scan was obtained shortly (mean ؎ SD 3.2 ؎ 3.0 days) after the injury, and a second scan was obtained 7 weeks later (mean ؎ SD 50.7 ؎ 5.5 days). The morphology (mean and maximum thickness, volume, and surface area) of the patellar, tibial, and femoral cartilage was determined from coronal and axial magnetic resonance images (fat-suppressed gradient-echo).Results. Between week 0 and week 7, the crosssectional area of the quadriceps muscle was reduced by 11% (P< 0.001). Changes in the mean (؎SD) cartilage thickness ranged from ؊2.9 ؎ 3.2% in the patella to ؊6.6 ؎ 4.9% in the medial tibia. No significant change in cartilage morphology of the contralateral knee was observed. Conclusion.Results of this study demonstrate that in a post-ankle fracture model of partial load bearing, cartilage morphology in all knee compartments is subject to significant change. Changes in the femorotibial joint exceeded those in the patella, whereas no change was observed in the contralateral knee. These findings raise the question of whether cartilage is mechanically less competent and particularly vulnerable after states of partial or complete immobilization.Quantitative magnetic resonance imaging (MRI) is a novel, but established, technique for studying cartilage morphology under physiologic and pathophysiologic conditions (1-5). Recent studies have shown that cartilage thinning occurs during aging (4), in osteoarthritis (OA) (2,6,7), after partial meniscectomy (8), and after spinal cord injury (3,9). Results from animal models have shown that cartilage morphology, composition, and mechanical properties are subject to change during immobilization (10). However, it is as yet unknown whether changes occur in human cartilage during short periods of immobilization or partial load bearing. Such information is important in the postoperative management of OA and in the context of space travel (i.e., when astronauts return to normal gravity conditions after long-term space flight). The relevant question here is whether or not cartilage properties change under conditions of partial load bearing, and, supposing that such changes do occur, whether cartilage is vulnerable to injury when normal load-bearing conditions are reestablished.In this study, we made use of the fact that patients who have undergone operative treatments of ankle fractures are subject to a 7-week period of partial load bearing. We explored the extent to which the cartilage morphology of the ipsilateral knee changed during the postoperative period in relation to the loss of cross-sectional area of the quadriceps muscle.

Ollier's disease is characterised by severe deformity of the extremities and retarded growth because of multiple enchondromas. For correction of deformity, the Ilizarov method has been used although it has many complications. A 17-year-old boy with Ollier's disease had a limb-length discrepancy of 17.4 cm, with a valgus deformity of the right knee and recurvatum of the femur of 23 degrees . He had undergone three unsuccessful attempts to correct the deformities by using external fixators. We used a fully implantable, motorised, lengthening and correction nail (Fitbone) to achieve full correction of all the deformities without complications. We decided to carry out the procedure in three stages. First, we lengthened the femur by 3.6 cm and the tibia by 4 cm. We then exchanged the femoral nail for a longer implant and achieved a further 6 cm of length. This reduced the shortening to 3.8 cm. When the boy has finished secondary school we will adjust the remaining discrepancy.

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