Initial evaluation on subsidence of cemented collarless polished tapered stem applied to the patients with narrow femoral medullar canal.
OBJECTIVE
The geometry of the proximal femur is one of the important factors for choosing the suitable stem. We have been applied cemented collarless polished tapered (CPT) stem to the patients with small femur. Radiographic evaluation was performed to access the clinical feature of the stem in early stage of the follow-up.


METHODS
One hundred total hip arthroplasties with CPT system were performed between October 2004 to February 2006. This study focused on the 53 cases to whom size 1 or smaller sized stem were implanted, and its post-operative period was 41 months (30-46 months). Morphologic classification of preoperative proximal femur, stem alignment, thickness of the cement mantle, cementing technique, subsidence of the stem, improvement in the bone-cement interface, and stress shielding were assessed.


RESULTS
The size of the inserted stem was X-SMALL in one case, SMALL in two cases, SIZE 0 in 12 cases, and SIZE 1 in 38 cases. Canal shape of proximal femur was stovepipe type in five cases, normal type in 43 cases, and champagne-flute type in five cases. There was no subsidence in eight cases. 44 stems subsided within 1 mm, one stem subsided 1 to 2 mm, and no stem subsided over 2 mm. In 39 of 45 cases, subsidence was appeared within six months after operation. Marked progressive and excessive subsidence was not seen after the two years of follow-up.


CONCLUSIONS
Short term radiographic results of THA with CPT stem to small femur were satisfactory with less unfavorable radiographic findings, which imply contribution to longer survivorship of the stem.
Dairaku
Katsuyuki
K
Department of Orthopaedic Surgery, Yamagata University School of Medicine, 2-2-2 Iida-Nishi, Yamagata 990-9585, Japan.
Ishii
Masaji
M
Kobayashi
Shinji
S
Kawaji
Hiroyuki
H
Sasaki
Kan
K
Takakubo
Yuya
Y
Takagi
Michiaki
M
Nihon Seikeigeka Gakkai Zasshi. 1994 Sep;68(9):763-73
7963930
Clin Orthop Relat Res. 1979 Jun;(141):17-27
477100
Clin Orthop Relat Res. 1998 Oct;(355):47-56
9917590
J Bone Joint Surg Br. 1992 May;74(3):385-9
1587883
J Arthroplasty. 2005 Apr;20(3):275-81
15809942
J Arthroplasty. 2002 Feb;17(2):189-95
11847618
J Bone Joint Surg Br. 1998 Sep;80(5):754-6
9768879
Clin Orthop Relat Res. 2008 Jun;466(6):1429-37
18343979
J Arthroplasty. 2001 Dec;16(8 Suppl 1):37-41
11742449
Orthop Clin North Am. 1988 Jul;19(3):477-89
3269211
J Arthroplasty. 2008 Feb;23(2):188-96
18280411
Clin Orthop Relat Res. 1988 Oct;(235):148-65
3416522
J Bone Joint Surg Br. 1998 Jul;80(4):573-6
9699814