Immediate weight bearing after uncemented total hip arthroplasty with an anteverted stem: a prospective randomized comparison using radiostereometry.
BACKGROUND
In uncemented total hip arthroplasty with hydroxyapatite coating, early weight bearing is frequently practiced but there is still not much evidence to support this recommendation.


METHODS
In a prospective randomized study we evaluated the effect of partial and full weight bearing after cementless total hip arthroplasty (ABG; Stryker-Howmedica) using radiostereometric analysis (RSA). Between February 1996 and February 2000, 43 consecutive patients (mean age 53 (41-63) years, 23 women) with hip osteoarthrosis received an uncemented and hydroxyapatite-coated prosthesis with an anteverted stem. All patients were operated in a standardized way by three experienced surgeons and they were randomized to partial (P) or full (F) weight bearing during the first 6 weeks after surgery. The patients in the partial weight bearing group were equipped with a pressuresensitive insole signaling when their load exceeded the prescribed weight limit.


RESULTS
At 3-month follow-up, the mean proximal (+)/ distal (-) migration of the stem was -0.14 mm (-1.93- 0.11) in group P and -0.31 mm (-4.30-0.16) in group F (p=0.6). At 1-year follow-up, the mean migration was -0.17 mm (-2.18-0.21) and -0.28 mm (-4.31-0.11), respectively (p=0.9). There was no significant difference in stem rotations either (p<0.2). The cup translations, rotations, and femoral head penetration were similar in the two groups (p<0.1). There were no re-operations during the first year.


CONCLUSIONS
We did not find any adverse effect of full weight bearing immediately after operation, which justifies use of this regimen after uncemented total hip arthroplasty of the ABG type.
Thien
Truike M
TM
Department of Orthopaedics, Sahlgrenska University Hospital, Mölndal, Sweden. truike.thien@vregion.se
Ahnfelt
Lennart
L
Eriksson
Mikael
M
Strömberg
Christer
C
Kärrholm
Johan
J
D000368:Aged; D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects / Q000379:methods / Q000534:rehabilitation*; D015519:Bone Density; D020099:Coated Materials, Biocompatible; D017886:Durapatite; D005260:Female; D005500:Follow-Up Studies; D006621:Hip Joint / Q000000981:diagnostic imaging; D006801:Humans; D008297:Male; D008875:Middle Aged; D015207:Osteoarthritis, Hip / Q000601:surgery; D011446:Prospective Studies; D011474:Prosthesis Design; D011475:Prosthesis Failure; D011859:Radiography; D016474:Weight-Bearing
D020099:Coated Materials, Biocompatible; D017886:Durapatite