Percutaneous physiodesis is an established technique for treating mild leg-length discrepancy and problems of expected extreme height. Angular deformities resulting from incomplete physeal arrest have been reported, and little is known about the time interval from percutaneous physiodesis to actual physeal arrest. This procedure was carried out in ten children, six with leg-length discrepancy and four with expected extreme height. Radiostereometric analysis was used to determine the three-dimensional dynamics of growth retardation. Errors of measurement of translation were less than 0.05 mm and of rotation less than 0.06°. Physeal arrest was obtained in all but one child within 12 weeks after physiodesis and no clinically-relevant angular deformities occurred. This is a suitable method for following up patients after percutaneous physiodesis. Incomplete physeal arrest can be detected at an early stage and the procedure repeated before corrective osteotomy is required

Aims. To compare the structural durability of hydroxyapatite-tricalcium phosphate (HATCP) to autologous iliac crest bone graft in calcaneal lengthening osteotomy (CLO) for pes planovalgus in childhood. Patients and Methods. We present the interim results of ten patients (HATCP, n = 6 and autograft, n = 5) with a mean age of 11.5 years (8.2 to 14.2) from a randomised controlled non-inferiority trial with six months follow-up. The primary outcome was the stability of the osteotomy as measured by radiostereometric analysis. A non-inferiority margin of ≤ 2 mm osteotomy compression was set. Results. At six months the data showed that the osteotomy had been compressed by a mean 1.97 mm (99.8% confidence interval -1.65 to 5.60) more in the HATCP group than in the autograft group. Migration of the CLO grafted with HATCP stabilised at six months rather than at six weeks with autograft. Conclusion. This is the first randomised trial to compare the efficacy of HATCP graft with autograft in terms of stability of CLO in children. Because of problems with the HATCP the trial was stopped. We do not recommend HATCP graft in its current structure for use in unfixed CLOs. Cite this article: Bone Joint J 2016;98-B:1554–62