Is removal of subchondral bone plate advantageous in cemented cup fixation? A randomized RSA study.
There is uncertainty regarding whether and how the subchondral bone plate should be treated during acetabular preparation for cemented cup fixation in a total hip arthroplasty. We hypothesized that removing the bone plate would improve the cement-bone interface without jeopardizing the initial cup stability, and therefore, be advantageous to long-term cup survival. We randomized 50 patients with primary osteoarthritis into two groups, one for removal and one for retention of the subchondral bone plate. The patients were evaluated during 2 years followup using repeated radiostereometric examinations, analyses of radiolucent lines, and clinical followups. Patient scoring was done using the Western Ontario and McMaster Universities Osteoarthritis Index, the Short Form-12, and the Harris hip score. Removal of the subchondral bone plate resulted in a superior cement-bone interface with less development of radiolucent lines. The radiostereometry results showed small migrations in both groups. We found no differences in cup stability between groups, although a difference was observed in rotational behavior with the removal group stabilizing in a slightly vertical position whereas the retention group showed slight but progressive rotation into a more horizontal position. No differences were found during clinical followups. Removing the subchondral bone plate, where possible, improves the cement-bone interface without jeopardizing the stability, implying better long-term cup survival. However, it is a more demanding surgical technique.


METHODS
Therapeutic study, Level I (high quality randomized controlled trial with statistically significant difference or no statistically significant difference but narrow confidence intervals). See the Guidelines for Authors for a complete description of levels of evidence.
Flivik
Gunnar
G
Department of Orthopedics, Lund University Hospital, Sweden. Gunnar.Flivik@med.lu.se
Kristiansson
Ingvar
I
Kesteris
Uldis
U
Ryd
Leif
L
D000077:Acetabulum / Q000000981:diagnostic imaging / Q000601:surgery*; D000368:Aged; D000369:Aged, 80 and over; D019644:Arthroplasty, Replacement, Hip / Q000379:methods*; D001843:Bone Cements; D005260:Female; D005500:Follow-Up Studies; D006621:Hip Joint / Q000000981:diagnostic imaging / Q000601:surgery*; D006622:Hip Prosthesis; D006801:Humans; D008297:Male; D008875:Middle Aged; D015207:Osteoarthritis, Hip / Q000000981:diagnostic imaging / Q000601:surgery*; D011446:Prospective Studies; D011474:Prosthesis Design; D011859:Radiography; D016896:Treatment Outcome
D001843:Bone Cements