Purpose: Dislocation is one of the most common complications following total hip arthroplasty (THA), with rates reported between 1% and 3%, but as high as 6% using a posterior approach with metal on polyethylene bearing surfaces. The purpose of this study was to assess the dislocation rates in ceramic-on-ceramic THAs.

Method: Primary ceramic-on-ceramic (Stryker Orthopaedics) THAs performed at 9 institutions from October 1996 through July 2005 were included in the study (1635 hips in 1485 patients). Sixty-one percent were male. The average age was 52 years (range 15–83). Osteoarthritis was the leading reason for surgical intervention (86%). A posterior approach and 32 mm or 36 mm femoral head was used in the majority of patients (90%). Patients returned for routine clinical examination or were contacted by telephone to assess for dislocations at a minimum of one year (average three years) after surgery.

Results: Of the 1635 ceramic-on-ceramic THAs performed, there were 18 dislocations (1.1%). Of these, 15 were 32 mm femoral heads; 3 were 28 mm; none were 36 mm. The majority of dislocations occurred within 3 months after surgery (72%). Closed reduction was successful in 17 hips with one requiring a revision.

Conclusion: A low rate of dislocations in ceramic-on-ceramic THAs occurred in this study (1.1%). Compared with reported metal-on-polyethylene bearing surfaces, the ceramic-on-ceramic articulation design appears to have fewer dislocations. Other factors associated with this low dislocation rate may be decreased femoral neck diameters and/or larger average femoral head size in patients receiving the ceramic-on-ceramic design. These results will need to be compared with contemporary THA using different articular surfaces.

Aims: To compare acetabular surface treatments in alumina on alumina clinical trial. Methods: Utilizing new improved alumina ceramic materials and implant design, 514 hips were implanted in a US IDE prospective randomized study. All patients received the same press-þt hydroxylapatite-coated (HA) femoral stem. Two-thirds (349 hips) received an alumina ceramic bearing surface, while one-third (165 hips) received a cobalt chrome on polyethylene bearing. The alumina group was further divided with approximately one-half receiving a porous-coated titanium shell and alumina insert (172 hips Ð System I), and one-half receiving an arc deposited titanium shell with HA coating and alumina insert (177 hips Ð System II). System III, the control group, had a porous-coated titanium shell and polyethylene insert. All acetabular shells were of identical external geometry. Results: At latest follow-up, minimum 2 years (2–4 year range), differences were noted in the pattern of development of radiolucent lines around the acetabular components. Radiolucent lines were noted most commonly in De Lee Charnley Zone 3 in porous-coated shells (25/164 hips Ð System I, 33/151 hips Ð System III respectively). Radiolucent lines in Zone 3 were absent in the arc deposited with HA shells (System II) (p=0.001). Conclusions: These results appear to demonstrate that PSL style cups with arc dep and HA coating may improve levels of primary þxation versus that of porous-coated acetabular components.

Aims: Todayñs major challenge for total hip arthroplasty is to minimize wear and osteolysis in our younger and more active patients. Alumina ceramic bearings have known superior wear resistance and lubrication and do not carry a risk of ion release. One objective of this clinical study was to evaluate the use of alumina-on-alumina ceramics with proven implants that have had successful track records with regard to þxation (on a prospective randomized basis)Methods: Utilizing new improved alumina ceramic materials and implant design 514 hips were implanted in a multicenter US IDE prospective and randomized study. The study compared alumina-on-alumina ceramic bearings to a cobalt chrome-on-polyethylene bearing. All patients received the same press-þt hydroxylapatite-coated femoral stem while two-thirds (349 hips) received alumina ceramic bearings and one-third (165 hips) received the cobalt chrome-on-polyethylene bearing. Results: With a mean follow-up of greater than 40 months (36–60 months) there is no signiþcant difference in clinical performance between the two patient cohorts. Radiographically proximal femoral osteolysis has been noted in the control patients but in no patients that received the ceramic bearing. With Continued Access, a total of 947 alumina ceramic bearings have been implanted to date. There have been no ceramic fractures or alumina bearing failures. Conclusions: This new alumina-alumina ceramic bearing provides for a safe option for the younger and more active patient population.