Trial reduction while performing total hip replacement is an essential step of the procedure. This is to check the stability of the hip joint with the selected implant sizes and to assess the leg length to avoid discrepancy. Disengagement of the femoral head trial from the femoral rasp stem, with subsequent migration of the trial head into the pelvic cavity is a rare occurrence, but can be a very frustrating complication to both the surgeon and occasionally the patient. We present our experience with this exceptional situation and different management options, together with systematic review of the literature. We conducted Medline database search via Pubmed interface. MeSH search was used. Systematic review of English literature case reports was performed. 15 reports were found discussing intra-pelvic migration of different arthroplsty related materials. The total number of reported cases was 24 cases, out of those, 21 cases were related to migration of femoral trial head, 2 cases of migrated modular hemiarthroplasty bipolar heads and one case of migrated femoral head definitive implant.Introduction
Patients and methods
In a society whereby the incidence of obesity is increasing and medico-legal implications of treatment failure are more frequently ending with the consulting doctor, clarity is required as to any restrictions placed on common orthopaedic implants by manufacturing companies. The aim of this study was to identify any restrictions placed on the commonly used femoral stem implants in total hip replacement (THR) surgery, by the manufacturers, based on patient weight. The United Kingdom (UK) National Joint Registry (NJR) was used to identify the five most commonly used cemented and uncemented femoral stem implants during 2012. The manufacturing companies responsible for these implants were asked to provide details of any weight restrictions placed on these implants. The Corail size 6 stem is the only implant to have a weight restriction (60Kg). All other stems, both cemented and uncemented, were free of any restrictions. Fatigue fracture of the femoral stem has been well documented in the literature, particularly involving the high nitrogen stainless steel cemented femoral stems and to a lesser extent the cemented cobalt chrome and uncemented femoral stems. In all cases excessive patient weight leading to increased cantilever bending of the femoral stem was thought to be a major factor contributing to the failure mechanism. From the current literature there is clearly an association between excessive patient weight and fatigue failure of the femoral stem. We suggest avoiding, where possible, the insertion of small stems (particularly cemented stems) and large offset stems (particularly those with a modular neck) in overweight patients.
