Biomedical subjects
I Benareau
Publications and source records attributed to I Benareau.
[Intra-prosthetic dislocation of the Bousquet dual mobility socket].
PURPOSE OF THE STUDY: The Bousquet system is a dual mobility head-polyethylene polyethylene-metal cup socket. The polyethylene insert retaining the femoral head moves in the noncemented metal cup, increasing both mobility and stability. MATERIAL AND METHOD: Between 1989 and 1997, seven cases of intra-prosthetic dislocation (six patients) were observed. The femoral head escaped from the polyethylene insert due to wear. On the average, this complication occurred ten Years after implantation. Risk of dislocation was high in six of the seven hips. All patients had a large sized stem screwed into the femoral neck. There was a characteristic radiological aspect with loss of the concentric head metal cup configuration. The head was applied against the upper wall of the metal cup. RESULTS: Surgical replacement was undertaken early in six patients by simply changing the insert without modifying the other stable components. Outcome remained good at three to eight Years. One patient underwent late surgery. The insert and the cup were replaced with a classical implant. Functional outcome was good but recurrent dislocation occurred. DISCUSSION: At mid-term, intra-prosthetic dislocation of dual mobility sockets appears to be exceptional. Dislocation results from polyethylene wear leading to failure of the insert to retain the prosthetic head. Wear is favored by direct phenomena (direct contact between neck and insert which can occur early if there is a small difference in the head and neck diameters) or indirect phenomena (factors limiting polyethylene metal-cup mobility). Surgical treatment is necessary. If undertaken early, replacement with a modular head and insert can be sufficient if the prosthesis has not loosened but the metal cup may have to be replaced in the event of metal-metal contact between the head and the cup. Prosthesis loosening, wear of the metal cup, or an identified cause of dislocation imply replacing the failing implants. Implantation of the dual mobility system is particularly interesting for patients with a high risk of dislocation or a chronically unstable hip prosthesis. Careful technique is required to reduce or retard the risk of intra-prosthetic dislocation. CONCLUSION: Intra-prosthetic dislocation of a dual mobility socket is an exceptional complication at mid-term. Surgical treatment is required but may be limited to simple insert replacement. Systematic use of this type of implant in young subjects must be carefully examined, but for us, the risk of dislocation does not outweigh the advantages of this original concept of dual mobility. This type of socket remains an useful preventive technique for high-risk hips or for curative treatment of recurrent dislocation.
[Traction-mobilization in 2-stage treatment of infected total knee prosthesis. Apropos of 12 cases].
INTRODUCTION: A two stages reimplantation is advised by most authors in salvage of infected total knee arthroplasty. This treatment is more difficult, but seems more successful in controlling infection. It set the problem of the attitude between the two operative stages: an antibiotic cement spacer is usually used, but articular mobilization is not possible, except with an articulating spacer. MATERIAL AND METHODS: Since 1989, we use traction-mobilisation between the two operative stages, with mobilization under traction up to 50 degrees, and on edge of bed up to 70-90 degrees, till the reimplantation. We used this method on 12 cases of chronic infection in total knee arthroplasty. The reimplantation was done 34 to 47 days later. The reimplantation was more easy and more comfortable in approach and exposition, and post operative mobilisation easier. RESULTS: We did not have any recurrence of infection in this patients, but the follow up is too short for some of them. One prosthesis was removed for mechanical failure. The mean range of motion is 86 degrees at two months, 96 degrees at one year. DISCUSSION: The antibiotic cement spacer presents the disadvantage of leaving material in a potentially infected environment. It does not allow mobilisation, except using an articulating spacer. Traction-mobilisation keep articular flexion, allows mobilization, and does not leave any material in articulation. But this method has the disadvantage of requiring an hospital care between the two stages: that is reasonable if the delay is short. CONCLUSION: Traction mobilization seems to be an alternative to cement spacer. It makes the reimplantation easier, facilitates post operative recovery of mobility, and does not seem to increase recurrence of infection.