The aims of this study were (1) to assess whether rotational stability testing in Gartland III supracondylar fractures can be used intra-operatively in order to assess fracture stability following fixation with lateral-entry wires and (2) to quantify the incidence of rotational instability following lateral-entry wire fixation in Gartland type III supracondylar humeral fractures in children.

Twenty-one consecutive patients admitted with Grade III supracondylar fractures at the Children's Hospital at Westmead were surgically treated according to a predetermined protocol. Following closed fracture reduction, 2 lateral-entry wires were inserted under radiographic control. Stability was then assessed by comparing lateral x-ray images in internal and external rotation. If the fracture was found to be rotationally unstable by the operating surgeon, a third lateral-entry wire was inserted and images repeated. A medial wire was used only if instability was demonstrated after the insertion of three lateral wires.

Rotational stability was achieved with two lateral-entry wires in 6 cases, three lateral-entry wires in 10 cases and with an additional medial wire in 5 cases. Our results were compared to a control group of 24 patients treated at our hospital prior to introduction of this protocol. No patients returned to theatre following introduction of our protocol as opposed to 6 patients in the control group. On analysis of radiographs, the protocol resulted in significantly less fracture position loss as evidenced by change in Baumann's angle (p<0.05) and lateral rotational percentage (p<0.05).

We conclude that the introduction of rotational stability testing allows intra-operative assessment of fracture fixation. Supracondylar fractures that are rotationally stable intra-operatively following wire fixation are unlikely to displace post-operatively. Only a small proportion (26%) of these fractures were rotationally stable with 2 lateral-entry wires. This may be a reflection of either the fracture configuration or inability to adequately engage the medial column.

Total hip arthroplasty (THA) using modular components offers many advantages such as a reduction in the implant inventory required and increased intra-operative flexibility with component sizing and selection. However, it also comes at the price of the additional complication of component dissociation, in particular at the non-fixed interface between the polyethylene cup and the acetabular metal backing.

A review of 110 patients requiring revision THA from June 1993 to December 2000 performed by the senior authors revealed seven patients presenting with the triad of signs suggestive of this complication – a previously successful, painless THA that had become acutely painful and with radiographic evidence of femoral head asymmetry in the acetabular cup. Each of these patients had Harris - Galante II porous acetabular cups. At the time of the revision, these patients were found to have dissociated polyethylene cup liners and several with broken locking mechanisms warranting replacement of the acetabular cups, the liners and the worn femoral heads.

This is an uncommon complication of THA, with characteristic presenting symptoms and signs. The importance of comparison of previous radiographs with those at presentation and the postulated mechanisms for dissociation is stressed. Certain precautions are imperative when using modular implants and the pitfalls of the Harris - Galante II porous acetabular component locking mechanism should be acknowledged.