Cemented Total Hip Arthroplasty With Boneloc Bone Cement

David C. Markel, MD, Daniel B. Hoard, MD, Charles A. Porretta, MD

Disclosures

J South Orthop Assoc. 2001;10(4) 

In This Article

Materials and Methods

After agreeing to participate in Biomet's United States Investigational Device Exemption protocol and after obtaining Institutional Review Board approval, we undertook the study protocol. No financial support was received by the surgeons for participation. All patients properly consented and were free not to participate. Twenty selected patients were ultimately prospectively enrolled for study over an 18-month period. All patients scheduled for cemented hip arthroplasty by one of us (C.A.P.) were invited to participate in the study. The patients were required to be interviewed by the hospital's surgical physician's assistant to ensure an understanding of the requirements of participation (follow-up periods, questionnaires, release of information). The patients were required to consent to use of the experimental cement product.

From October 1991 to April 1993, we used the Boneloc bone cement and the dual cartridge injection system to do 20 total hip arthroplasties in 20 patients. The senior investigator (C.A.P.) performed approximately 70 other total hip arthroplasties during this period. The 20 study patients ranged in age from 43.5 to 86.8 years (mean, 67.3 years). Ten patients were men and 10 were women. Seventeen procedures were primary cemented total hip arthroplasties. In all cases, both components (femur and acetabulum) were implanted with the investigational Boneloc bone cement. Of these 17 patients having a primary hip replacement, 13 had a preoperative diagnosis of osteoarthritis, 1 had rheumatoid arthritis, and 3 had osteonecrosis of the femoral head (1 idiopathic, 2 posttraumatic). Each of the 3 patients having revision arthroplasty was believed to have bone stock compatible with cemented revision arthroplasty. One of them had revision of both acetabulum and femur, 1 had revision of a bipolar hemiarthroplasty with removal of the femoral component and conversion to a total hip arthroplasty, and 1 had revision of a femoral head resurfacing arthroplasty to a total hip arthroplasty. As in the primary procedures, all revision components were implanted with the Boneloc cement.

According to the protocol, one of three femoral components was available for use. These included the Biomet nonporous (cemented) Mallory-Head stem, manufactured from a cobalt-chrome-molybdenum alloy; the Biomet Bimetric cemented femoral stem, manufactured from a titanium alloy (Ti-6Al-4V); and the porous coated Biomet Mallory-Head uncemented stem, also manufactured from the titanium alloy. Similarly, the protocol limited acetabular reconstruction to use of one of three acetabular components. These included the molded Mallory-Head acetabular component and the Superior-Loc Acetabular System, both of which were polyethylene-titanium metal-backed shells and both of which could be implanted with or without cement. The third option was the Biomet all-polyethylene acetabular component designed to be implanted with cement. The femoral components used a taper fit modular head manufactured from titanium alloy, cobalt-chrome-molybdenum, or zirconia ceramic. In this study, 19 chrome-cobalt-molybdenum nonporous Mallory-Head stems and 1 titanium alloy Bimetric stem were cemented in place. All had a cobalt-chrome head. A cemented all-polyethylene acetabular component was used in all 20 of the patients in this investigation.

Seventeen of the procedures were done by one surgeon (C.A.P.) and the other 3 by attending surgeons. All cases were performed through an anterolateral approach.[2] Modern third-generation cementing techniques were used in all cases and included the use of a distal cement restrictor, retrograde filling of the canal, and pressurization of the cement.[3,4,5]

Patients were prospectively enrolled and had predetermined regular follow-up with clinical and radiographic evaluation. Clinical evaluation was done immediately before surgery, at 6 months postoperatively, 12 months postoperatively, and annually thereafter for 5 years. The clinical assessment was based on the Harris hip scoring system.[6] Of the 100 possible points in this system, 44 are based on pain, 47 on function, 4 on the presence or lack of deformity, and 5 on range of motion.[6]

Radiographic evaluation was based on standard anteroposterior and lateral radiographs of the hip immediately after operation, 6 months and 12 months postoperatively, and annually thereafter for 5 years. The immediate postoperative radiographic evaluation included a baseline assessment of the initial component position as outlined by Yoder et al,[7] the cement mantle thickness, and the presence of radiolucencies at the bone-cement and cement-prosthesis interfaces. The follow-up radiographic evaluations included assessment of change in component position (rotation, settling) relative to fixed bony points such as the lesser or greater trochanter or the teardrop, fractures of the cement, and/or radiolucency at the bone-cement and cement-prosthesis interfaces. Radiolucencies and/or fractures of cement, if present, were categorized and recorded according to the radiographic zones of Gruen et al[8] for the femur and of DeLee and Charnley[9] for the acetabulum. Acetabular loosening was graded by a modification of the systems of Harris and White[10] and Dorr et al[11] (definite loosening -- component migration; probable loosening -- complete radiolucency; possible loosening -- radiolucency comprising 2 of 3 Delee and Charnley zones; no loosening -- lucency in a single zone or no radiolucency). Femoral component fixation was graded according to the criteria of Harris et al[12,13] (definite loosening -- migration of component or cement; probable loosening -- complete radiolucency; possible loosening -- radiolucency in >50% of the bone-cement interface).

For the purposes of this study, failure was narrowly defined as either revision surgery or definite radiographic loosening combined with clinical failure (poor Harris hip score, significant complaints of pain, and dysfunction).

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