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[Implant-related fractures of the femoral neck cone adapter of a modular short-stem hip prosthesis - patient management and operative technique].

AIM
In cases of unexpected and implant-related mechanical failures, optimal surgical treatment and provident information for the patients are mandatory. We describe the surgical method to revise the hip stem after fracture of the modular cone adapter of a short-stem hip prosthesis and the management of and information for all patients who have received a fracture-prone implant.


METHOD
We present two out of four cases in a series of fractures of the femoral neck cone adapter of a modular short-stem hip prosthesis. The patients in our hospital were male, aged 69 and 52 years with a body weight of 73 and 88 kg. Implant failures occurred 18 and 20 months after the index THA.


RESULTS
Using special instruments available at short notice, the revision operation can be carried out with a primary implant (case 2) with reasonable technical expenditure, unless pathological-anatomic reasons do not allow it (case 1 with varus-flexion deformity and a rotational deviation that required a revision long-stem with combined correction osteotomy). Once the implants were fully integrated and tightly secured to the bone, they were loosened with flexible thin chisels. Drilling a hole and a thread into the fractured cone adapter allows the connection of a removal instrument for implant extraction. The clinical and radiological examination showed good results with an HSS of 100 points at 24 months follow-up. Our institution decided to inform all 54 patients who had received the failure-prone implant device. The provision of advice to the patients at risk proved to be effective.


CONCLUSIONS
When using new implants and procedures, the surgeons must inform the patients of hitherto unknown risks. The recipients of a failure-prone implant must be provided with comprehensive information. It is advisable for both the clinic and the manufacturer to contact the patients and advise them on how to cope with the situation. In most cases, the revision operation of the stem component can be performed with a primary implant without significant additional bone loss.