Authors report the history of two patients with achondroplasia, treated for symptomatic lumbar spinal stenosis. Both patients underwent cross-limb lengthening. During control visits they reported lumbar spine pain with increasing neurogenic claudication. In magnetic resonance imaging of the lumbar spine, we measured dural sac cross-sectional area (DSCSA) and spinal canal cross-sectional area (SCCSA) and the patients were qualified to the group of patients with critical spinal stenosis. They underwent "split" type laminotomy in the lumbar spine. In both patients, based on the Oswestry questionnaire, we noted very good result of surgical treatment. The most important change was increase of the walking distance after the procedure. In patients suffering from achondroplasia, with critical lumbar spinal canal stenosis and neurological symptoms the procedure of choice is surgical treatment. Surgical decompression of the spinal canal using "split" type laminotomy is an effective technique, preventing the destabilization of the posterior column and sagittal imbalance of the spine.

Congenital dislocation of the knee is a rare deformity, with an unknown etiology. The treatment of this malformation depends on its extensiveness and applies both conservative approach and surgical procedures. The aim of this study is to evaluate treatment outcomes obtained in the patient with congenital dislocation of the right knee and other multiple abnormalities of the motor system as well as the suspicion of Apert syndrome. Between 2005 and 2019, patient with congenital knee dislocation was treated surgically in two medical centers. Authors performed a retrospective analysis of available data from medical archives. The patient first presented to the authors of this study at the age of nine months. Imaging diagnostics revealed complete luxation of the right knee, grade III according to Leveuf and club feet with no fibula bones in the lower legs. The objective of the multi-stage surgical treatment was to enable the patient to walk. Stage one involved a reposition of the congenital right knee dislocation following the Curtis and Fisher technique. The next stage involved a foot surgery – first the left one and then the right. At the age of 5, during the follow-up, the patient was very active: he kept walking, running and jumping and both his feet were in the right position. However, in the following year, a gradual increase of rotation disorders was observed in both lower legs. When the child was 6 years, he underwent derotation osteotomies in both tibia bones. Next, at the age of 12, he underwent anterior femoral hemiepiphysiodesis around right knee with two 8-plates. Plates were removed when he was 14. The last follow-up took place when the patient was 14. The patient is 100% able-bodied and can walk on his own. To sum up, patients with congenital knee dislocation make up a highly complex group that requires multidisciplinary care and frequently also multistage treatment.