ObjectiveTo evaluate the effect of dynamic long leg casting in paediatric patients with developmental dysplasia of hip (DDH) diagnosed at 12–18 months.MethodsThe adductor tenotomy, closed reduction, and dynamic long leg casting method was adopted to treat paediatric patients with DDH. The hips were divided into four groups according to the Tonnis radiographic dislocation classification. Groups were also classified according to the baseline acetabular index (AI): 30°–35°, 36°–40°, and > 40°. The outcomes of the reductions were evaluated according to McKay’s hip function criteria and Severin’s radiological criteria.ResultsA total of 246 patients (339 hips) had complete follow-up data. After 3 months of orthosis fixation, the results were satisfactory in 264 hips (77.88%). Hip function was rated as ‘excellent’ or ‘good’ in 43 of 51 (84.31%) Tonnis type 1 hips, 125 of 155 (80.65%) type 2 hips, 70 of 90 (77.78%) type 3 hips, and 34 of 43 (79.07%) type 4 hips. The higher the baseline AI, the lower the rates of ‘excellent’ and ‘good’ hip function. Favourable radiological results (Severin types I and II) were found in 266 of 339 (78.47) hips.ConclusionsDynamic long leg casting is an effective method for treating patients with DDH aged 12–18 months at diagnosis.

Level II.

Rationale:Leakage of bone cement from femoral medullary cavity is a rare complication after hip arthroplasty, and there is no report on the leaked bone cement entering into iliac vessels.Patient concerns:An 89-year-old woman presented with a fracture in the right femoral neck. She had well-fixed right femoral head replacement after careful preoperative examinations, and no adverse reactions appeared. She was able to get off bed to walk at the 2nd day after surgery.Diagnoses:Postoperative radiograph showed leakage of bone cement into the joint through femoral medullary cavity entering into iliac vessels, but the patient complained no discomforts. She received a treatment with low-molecular weight heparin and rivaroxaban.Outcomes:The patient was able to walk with normal gait, without swelling in both lower extremities and discomfort in the hip. There was no other complication concerning intravascular foreign bodies.Lessons:This case calls into the phenomenon of leakage of injected bone cement in femoral head replacement regardless of complete and nonfractured femur, which may be into the lower limb and pelvic veins, given that, dangerous consequences will not occur.

Background Accurate femoral neck anteversion angle (FNA) measurement is of great significance in the diagnosis and treatment of developmental dysplasia of the hip (DDH) in children. The FNA measurement still remains a controversy. We aimed to verify the accuracy of our CT method by 3D printing technology and to evaluate its clinical value. Methods Sixty-eight children with unilateral DDH were enrolled, and their FNA was measured using 2D-CT and 3D-CT, respectively, by three observers. This procedure was repeated 3 months later. The above measurement outcomes were then compared with the results in the 3D-printed femur (3D-PF) model. The FNA in the 3D-PF model was measured by three observers (two radiologists and one orthopedist; all were professors) collectively through electronic angle instrument. Results The primary measurement of FNA at the affected hips by 2D-CT was 44.0 ± 6.1, 49.5 ± 8.9, and 52.8 ± 7.9°, respectively. On the 3D-CT, it was 47.6 ± 5.4, 49.3 ± 6.8, and 48.6 ± 6.2°. Three months later, the FNA on 2D-CT was 49.3 ± 10.5, 42.8 ± 7.4, and 45.1 ± 9.3°, and it was 48.0 ± 6.5, 48.9 ± 7.2, and 49.0 ± 5.7° on 3D-CT, respectively. The FNA in the 3D-PF model at the affected and unaffected hips was 48.5 ± 6.6 and 36.9 ± 13.1°. There were significant differences between 2D-CT and 3D-PF measurements, but no significant difference was found between 3D-CT and 3D-PF measurements. The results by 2D-CT showed significant differences among groups and between the groups. However, the results by 3D-CT had no significant differences among groups or between the groups. Conclusion The results of our study showed that 3D-CT is a more precise, and reproducible method for FNA measurement in DDH. The FNA at the affected hips is 11.6° larger than the unaffected in DDH children aged 3–8 years.