Introduction: Lag screw cut-out in gamma nailing is reported between 1,1% and 7.1% in the literature. Searching for predictive factors we performed a retrospective study, and we analyzed our cut-out cases.

Material & Methods: We reviewed our first 1000 gamma nailings. A detailed analysis of the cut-out cases was performed. We focused on fracture type and the technical failures of the primary surgery. Fractures were classified according to AO. Timing of surgery, implant type and an estimated value of osteoporosis on x-ray was investigated. Distance of the tip of the lag screw from the cortical bone, from the ideal central line of the neck and head in AP and lateral view, and precision of reduction was measured and classified. We recorded the direction of cut-out and the occurrence of secondary varus displacement.

Results: We had 29/1000 (2,9%) cut-outs. Average age was: 76 years. 14/29 (48%) AO A2.2 type and 8/29 (28%) A3.3 type fractures were found in the cut out group. Normal collo-diaphyseal angle was achieved in all cases primarily. In 21/29 (72%) the gap between main fragments was narrower than 5 mm, and in 8/29 (28%) it was bigger. The subjective evaluation of the reduction was 2/29 excellent, 9/29 good, 12/29 satisfactory and 6/29 bad. Primary position of the lag screw tip was caudal in 13/29, central in 10/29 and cranial in 6/29 cases. The distance of the lag screw from the central line in frontal/dorsal direction was 0–4 mm in 5/29, 5–9 mm in 12/29, 10–14 mm in 7/29 and 15–19 mm in 5/29 cases. The numbers of too short or too long lag screws were not high in this patient group. The cut out was cranial in 24/29 (83%) cases and central at 5/29 (17%) patients. We recorded 20/29 (68%) secondary varus displacement. We found 2/29 (7%) patients where none of the above mentioned technical problems could be justified.

Conclusion: AO A2.2 and A3.3 fracture type is a predisposing factor. Cut-out appears relatively early. Correct positioning of the lag screw in both views is essential. Leaving the fracture in a significantly displaced position increases the risk of cut out, too. The lag screw migrates mainly cranial with a secondary varus dislocation. With adequate technique the majority of cut-outs can be avoided, but there is a little percentage of the cases when the primary mistake is not obvious. A possible explanation could be osteoporosis, but further investigation is necessary to clarify these unknown factors.

Aims: Evaluation of the clinical and radiological results after primary surgical treatment of CDH in children with late discovered CDH. Methods: We have studied 64 hips of 58 patients (51 female and 7 male), who were between 18 months-8 years old with late discovered CDH. The study was made between 1991–2000. Teratological and neuromuscular cases were excluded. None of the patients have had previous treatment before admission in hospital. Preoperative radiographic evaluation of the cases was made based on the Tšnnis classiþcation system (12-gr.I, 26-gr.II, 19-gr.III, 7-gr.IV). Preliminary traction was used in 5 hips (4 patients). 8 of them were treated by open reduction, 18 by open reduction and pericapsular osteotomy of the ilium described by Pemberton, 38 by combined pelvic osteotomy (29 Pem-berton osteotomy, 9 Chiari osteotomy) and femoral derotation and/or varus osteotomy (with femoral shortening in 8 cases). Postoperatively, a plaster cast was applied for 6 weeks. Average follow-up period was 6.8 years. Results: The radiological results are based on Severin Classiþcation. We obtained in 77.5% of the cases excellent, good and satisfactory results. Using the clinical rating system of Fergusson and Howard, the results were good and satisfactory in 78.8 of the cases. Avascular necrosis occurred in 6 cases, being rated as group II and III according to the Kalamchi and Mac Ewen classiþcation system. Conclusions: In case of late discovered CDH, the results of conservative treatment are not satisfactory, the surgical treatment being recommended. Four years old or elder children can be treated safely with one stage operation consisting of open reduction, pelvic osteotomy with or without femoral derotation and varus osteotomy (with shortening if it is necessary).

Aims: The late effect of intramedullary nailing of the femur on proximal femur growth, particularly on growth plate of the greater trochanter and femoral neck, being known that losing the balance in the growth of the three ossiþcation points of the femurñs proximal extremity, the gap canñt be compensated by the greater trochanterñs remaining growth cartilage. Methods: During 1980–1995 we have performed 55 intramedullary femoral osteosyn-theses using KŸntscher rods in children 5–14 years of age. We have had the opportunity to observe 29 children during their later somatic growth: 25 femoral diaphyseal fractures and 4 non-unions. The average folow-up period has been 8.3 years. The patientñs average age has been 9,5 years. The hips were evaluated clinically for walking, mobility, limb length discrepancy. Radiological evaluation was based, according to Edgren, on following parameters of the joint architecture: cervico-diaphyseal angle (CDA), articulo-trochanteric distance (ATD), intertro-chanteric distance (TTD), femoral neck diameter (FND). Results: Clinical, one child presented 1.3 cm femur shortening. The evaluation of the radiological parameters on coxo-femoral joint showed increased CDA value between 10–30¡ in 8 children, increased ATD value (10–20mm) in 7 children, reduction of the TTD value in 6 patients and reduction of the FND (5–10mm) in 3 children. Conclusions: Insertion of intramedullary nail via the greater trochanter should be avoided in children less than 13–14 years of age, having tardy valgus effect and thinning of the femoral neck. We recommend osteosynthesis with plate and screws or, in little ones, transfragmentar screws, followed by immobilisation in plaster cast.