Abstract
The cranial cup is now a standardised implant in acetabular revision surgery. In order to illustrate the positive results of a standardised implant in acetabular revision surgery in comparison to other possibilities of reconstruction, we analysed results of all data in our study group.
Aseptic loosening of implants often causes segmental and cavitary acetabular deficiency. Experiences gained in radical tumour surgery with reconstruction by custommade endoprostheses induced the development of the cranial cup for revision total hip arthroplasty. This new cementless revision cup has an oval shape and a special cranial flap, as well as an intramedullary rod if necessary.
This type of cranial cup has been used since 1993. From 9/97 to 1/99, we implanted 30 cranial cups in revision hip surgery and collected all data of these patients prospectively. Clinical and x-ray follow-up was documented on a regular basis.
Acetabular deficiency occurred twice in type 1, five times in type 2, twenty-two times in type 3 and once in type 4. The AAOS D’Antonio score was used. Cranial cups were implanted without cranial flap in 10 cases, with cranial flap in 20 cases and once using the intramedullary rod additionally. Only 28 patients were included in our last examination because one patient had died and one was bedridden because of a reason other than the hip. The Harris hip score increased from an average of 32 points preoperatively to 63 points postoperatively. Twenty-one patients are satisfied or very satisfied with their surgery. Radiograph examinations showed an average inclination angle of 42.5° in all cranial cups.
Up to now there have been complications in four patients who suffered luxations, but only one required a change of inlay. One intraoperative injury of the urinary bladder had to be revised later. Three implants showed a change of position in x-ray. One was the patient with the urinary bladder injury and possible septic loosening, the second was a patient with extreme osteoporosis, and the third was a patient who did not receive an intramedullary rod for a type 4 lesions. Currently, these three patients do not have any complaints.
We have always achieved primary stability. Morselised bone autografts or bone substitute materials were used to fill remaining defects. An intramedullary rod should be used in pelvis discontinuity and is obligatory to achieve the necessary stability. Developed from the experiences of custom-made tumour endoprostheses, the cranial cup with all possible variations is an appropriate intraoperative variable implant in revision acetabular surgery.
The abstracts were prepared by David P. Davlin. Correspondence should be addressed to him at the Orthopedic Clinic Bulovka, Budínova 2, 18081 Prague 8, Czech Republic.
