Periprosthetic bone mineral density and fixation of the uncemented CLS stem related to different weight bearing regimes: A randomized study using DXA and RSA in 38 patients followed for 5 years.
OBJECTIVE
There is no consensus on the best rehabilitation regime after uncemented total hip arthroplasty. Theoretically, bone ingrowth into the implant should benefit from initial partial weight bearing. We investigated whether the degree of postoperative weight bearing influences the periprosthetic bone mineral density (BMD) and/or the stability of the CLS stem.


METHODS
38 patients received an uncemented CLS stem and were randomized to either unrestricted postoperative weight bearing or to partial weight bearing for 3 months. Periprosthetic BMD was measured in the 7 Gruen zones with DXA and the stability of the femoral stem was assessed by radiostereometric analysis (RSA) after surgery and at 3, 12, 24, and 60 months.


RESULTS
Periprosthetic BMD was not influenced by the type of postoperative weight bearing. BMD was reduced by 8-15% in all Gruen zones at 3 months. Restoration toward initial BMD was observed in all zones except in zone 7 (calcar region), where BMD was reduced by 22% at 5 years. Immediate weight bearing after surgery had no influence on the stability of the CLS stem, as assessed by RSA.


CONCLUSIONS
Immediate full weight bearing after uncemented total hip arthroplasty is safe. There is no difference in the periprosthetic BMD or in stability of the stem as measured by RSA compared to partial weight bearing for 3 months. BMD is reduced by more than 20% in the calcar region around a CLS stem after 5 years.
Wolf
Olof
O
Department of Orthopedics, Uppsala University Hospital, Uppsala, Sweden. olof.wolf@akademiska.se
Mattsson
Per
P
Milbrink
Jan
J
Larsson
Sune
S
Mallmin
Hans
H
D015502:Absorptiometry, Photon; D000328:Adult; D000368:Aged; D019644:Arthroplasty, Replacement, Hip / Q000379:methods / Q000534:rehabilitation; D015519:Bone Density; D002484:Cementation; D005260:Female; D005500:Follow-Up Studies; D006622:Hip Prosthesis; D006801:Humans; D008297:Male; D008875:Middle Aged; D015207:Osteoarthritis, Hip / Q000601:surgery; D010780:Photogrammetry; D013997:Time Factors; D016474:Weight-Bearing
Acta Orthop. 2007 Dec;78(6):730-8
18236178
Clin Orthop Relat Res. 2007 Jan;454:127-32
16936584
J Bone Miner Res. 2001 Jun;16(6):1056-61
11393782
Acta Orthop. 2006 Dec;77(6):877-85
17260195
J Arthroplasty. 2004 Jun;19(4):469-75
15188106
J Bone Joint Surg Am. 1997 May;79(5):707-14
9160943
Acta Orthop. 2006 Jun;77(3):386-92
16819676
J Arthroplasty. 2006 Aug;21(5):689-95
16877154
J Arthroplasty. 2007 Dec;22(8):1122-9
18078880
Scand J Surg. 2006;95(1):55-60
16579257
Acta Orthop. 2009 Oct;80(5):531-7
19916684
Hip Int. 2006 Jan-Mar;16(1):8-17
19219772
Clin Orthop Relat Res. 1997 Nov;(344):94-110
9372762
Calcif Tissue Int. 2003 Aug;73(2):115-21
14565592
Acta Orthop Scand. 2003 Feb;74(1):31-6
12635789
Soc Sci Med. 1995 Nov;41(10):1349-58
8560302
J Bone Joint Surg Br. 1993 Sep;75(5):681-7
8397213
Acta Orthop Belg. 1993;59 Suppl 1:144-8
8116390
Acta Orthop Scand. 2004 Feb;75(1):21-9
15022801
Acta Orthop. 2005 Aug;76(4):563-72
16195075
Int Orthop. 2001;25(2):85-8
11409458
Acta Orthop. 2009 Jun;80(3):291-7
19562565
J Arthroplasty. 2007 Aug;22(5):689-91
17689776