Displaced fractures of the radial neck in children can lead to limitation of elbow and forearm movements if left untreated. Several management techniques are available for the treatment of radial neck fractures in children. Open reduction can disturb the blood supply of the soft tissue surrounding the radial head epiphysis and is associated with more complications.

We report our experience of treating 14 children between the age of 4 and 13 years, who had severely displaced radial neck fractures (Judet type 111 and 1V). 12 patients were treated with indirect reduction and fixation using the Elastic Stable Intramedullary Nail (ESIN) technique, (3 with assisted percutaneous K-wire reduction) and 2 had open reduction followed by ESIN fixation of the radial head fragment. This method reduces the need for open reduction and thus the complication rate. Three patients had associated fractures of the same forearm which was also treated surgically at the same time. We routinely immobilised the forearm for two weeks and removed the nail in all cases in an average of 12 weeks. We had no complication with implant removal.

All 14 patients have been followed up for average of 28 months. One patient (7%) developed asymptomatic avascular necrosis (AVN) of the head of radius. Thirteen patients (93%) had excellent result on final review. One patient had neuropraxia of the posterior interosseous nerve which recovered within 6 weeks.

In conclusion we advocate ESIN for the closed reduction and fixation of severely displaced radial neck fractures in children. It remains a useful fixation method even if open reduction is required and allows early mobilisation.

Introduction: Many designs exist for the femoral component of cemented total hip arthoplasty, but cemented acetabular cups are largely similar. All are essentially hemispheres, made of polyethylene. An important factor determining survival time of cemented implants is cement penetration into the surrounding bone. To ensure sufficient penetration, many surgeons remove the smooth subchondral bone in the acetabulum and drill anchoring holes. This may however weaken the bone. Larger cement pressure during setting will improve penetration. For an acetabular cup, fixation at the rim is most important to prevent loosening, and therefore cement pressure should be high at the rim. A spherical geometry is not ideal to ensure high rim cement pressures. Based on a computer model of cement pressure generation during cup insertion, we designed an improved geometry to ensure higher rim pressures. The aim of this study is to compare the fixation strength of this new design to a conventional design. The effect of the design change will be compared with that of drilling anchoring holes and removing subchondral bone.

Methods: From a larger stock of young bovine acetabula, 14 similarly sized specimens were chosen. Twelve were prepared for a factorial experiment with three factors, based on three cup designs (Ogee either with or without flange, DePuy, Leeds, and the alternative design), preservation or removal of subchondral bone, and presence or absence of anchoring holes. Depth, diameter and position of the anchoring holes were chosen to optimise fixation strength. Two were prepared for replicates of two experiments with the new design, both with sub-chondral bone removed. The order of the experiments was randomised. CMW-3 cement (CMW-DePuy, UK) was hand-mixed for one minute. After four minutes, it was packed in the acetabulum and pressurised for one minute. Then a cup was inserted and manual force applied until setting of the cement. Next, acetabulum and cup were mounted in a materials testing machine and torque applied to the cup until gross failure. Applied force and displacement were sampled into a computer, and used to determine maximum torque.

Results and Discussion: Analysis was done in two steps. First, two-way ANOVA of main effects plus first order interactions was performed. Anchoring holes significantly increased strength (41±8 vs. 114±9 Nm; p=0.004, mean±SEM). No significant effect of reaming or cup design was found. For all experiments, the conventional cups with or without flange behaved almost identical. In step two, these two variations were combined into one “conventional” group, and three-way ANOVA with interactions was performed. Significant interaction between all three factors was found (p=0.02). This indicates that one unique combination (new cup design in acetabula with subchondral bone removed and without anchoring holes) achieved a high average strength. Under these circumstances, the fixation strength of the new design (114±9 Nm) was equal to the overall average achieved with anchoring holes. On average, the new design also had significantly larger fixation strength than a conventional spherical design (95±5 vs. 69±4 Nm; p=0.009). These results justify further studies.