Suboptimal (thin) distal cement mantle thickness as a contributory factor in total hip arthroplasty femoral component failure. A retrospective radiographic analysis favoring distal stem centralization.
One hundred cemented total hip arthroplasties (THAs) were evaluated regarding the potential benefit of THA femoral component distal stem centralization, specifically regarding cement mantle thickness. Factors potentially predictive of femoral component mechanical loosening, both relating (22 factors) and not relating (41 factors) to cement, were analyzed on initial postoperative radiographs. Nine THAs with femoral component mechanical failure (group 1) were compared to (1) 88 non-failed THAs (group 2) and (2) 9 matched-paired, nonfailed THAs (group 3). Significant differences were evident regarding minimum and maximum cement mantle thickness in Gruen zone 5 and combined zones 5/6 (groups 1 vs 2 and groups 1 vs 3), with failed femoral components having thinner cement mantles. Discriminate analysis determined minimum cement mantle thickness in zone 5 to be the factor most predictive of femoral component failure. These data indicate that a suboptimal (thin) cement mantle at the medial diaphysis (Gruen zones 5 and 6) contributed to femoral component mechanical loosening in this THA series. This relationship may not pertain to femoral stems of different materials or cross-sectional characteristics. Many THA systems currently provide for a method of centralization of the femoral component distal stem as a mechanism to ensure an adequate circumferential distal cement mantle. Continued investigation into techniques directed toward centralization of the distal femoral stem is warranted by the findings of this study.
Division of Orthopaedic Surgery, Scripps Clinic and Research Foundation, La Jolla, California 92037.
M J
MJ
Star
C W
CW
Colwell
G J
GJ
Kelman
R T
RT
Ballock
R H
RH
Walker
D000497:Alloys; D001843:Bone Cements; D016002:Discriminant Analysis; D006615:Hip / Q000000981:diagnostic imaging; D006621:Hip Joint / Q000000981:diagnostic imaging; D006622:Hip Prosthesis / Q000706:statistics & numerical data; D006801:Humans; D011183:Postoperative Complications / Q000000981:diagnostic imaging / Q000453:epidemiology; D011474:Prosthesis Design; D011475:Prosthesis Failure; D011859:Radiography; D012189:Retrospective Studies; D014025:Titanium
D000497:Alloys; D001843:Bone Cements; D014025:Titanium