, , , , , , , , , , , , , , , , , , , ,

Cemented Total Hip Arthroplasty With Boneloc Bone Cement

David C. Markel, MD, Daniel B. Hoard, MD, Charles A. Porretta, MDAuthors and DisclosuresPosted: 04/17/2002; J South Orthop Assoc. 2001;10(4) © 2001 Southern Medical Association www.medscape.com


(WK-345, Biomet Inc, Warsaw, Ind) attempted to improve cement characteristics by reducing exotherm during polymerization, lowering residual monomer and solubility, raising molecular weight, and lowering airborne monomer and aromatic amines. To study the efficacy of this cement, a selected group of 20 patients were prospectively enrolled and followed up after hip arthroplasty. All components were cemented. During the enrollment period, approximately 70 other hip arthroplasties were performed. Clinical evaluation was based on the Harris hip score. Radiographic evaluation was based on assessment of position of the components, subsidence, and/or presence of radiolucencies. Patients had follow-up for an average of 42 months (11 to 58 months); 1 was lost to follow-up. Of these, 7 (35%) had failure at last follow-up. Despite its initial promise, Boneloc cement had an unacceptably high failure rate over a relatively short follow-up period and is not recommended for use. Despite the longevity and odor toxicity problems with conventional bone cement, new cement technologies must be approached with caution. Introduction Cemented hip arthroplasty has been performed since the late 1960s.[1] It became clear over the ensuing years that cemented arthroplasties had a limited longevity and that the mechanical construct would fail via a process of aseptic loosening. In addition, a number of less than desirable characteristics were noted. The fumes of the polymerizing cement were found to be noxious to the operating room staff, and the exotherm of the polymerizing cement was potentially damaging to the bone. To address these concerns, several implant manufactures developed or are developing newer cement technologies.

In 1986, development was begun of a new bone cement, which was later marketed by Biomet Inc (Warsaw, Ind) as Boneloc. The first objective for Boneloc was to create a cement equal to or better than conventional methyl methacrylate/polymethyl methacrylate in both efficacy and longevity. The second objective was to create a product that was safer for operating room personnel.

By decreasing the chemical and thermal damage to bone during implantation, it was believed that the clinical efficacy of conventional polymethyl methacrylate could be improved. It was hoped that by preventing bone necrosis at the bone-cement interface the mechanical grouting action of the cement would be better preserved and perhaps improve the longevity of the construct. Therefore, the first goal was to reduce the exothermic temperature generated during cement polymerization, lower the residual monomer content, and create a product with both a lower solubility and a higher molecular weight. The second objective was protection of operating room personnel. Nursing staff have been noted to complain about the odor of cement and have anecdotally associated exposure to cement fumes with headache, nausea, and/or dizziness. While there is no clear evidence that the cement fumes are teratogenic, pregnant nurses are often not used to staff joint replacement procedures done with cement at many hospitals, including ours. Thus, the second objective would be accomplished by lowering the residual content of the airborne monomer and aromatic amines, as well as containing the noxious airborne material by modifying the cement delivery system.

The resultant Boneloc cement consisted of a two-component self-curing system. The powdered polymer component consisted of butylmethyl methacrylate copolymers in a ratio of 40%:60%. The liquid monomer component contained 50% methyl methacrylate, 30% n-decyl methacrylate and 20% isobornyl methacrylate. An integrated packaging, mixing, and delivery system was developed to minimize operating room staff exposure to the monomer vapor. The system used a double-chambered high-density polyethylene cartridge into which the two cement components were packeted. Within the chambers, an aluminum membrane separated the monomer and polymer. When the separating aluminum membrane barrier was broken, the polymer and monomer mixed, yet the entire process was kept isolated from the operating room environment and staff. Initial reports noted difficulty with the mixing and cement delivery. Therefore, in 1993, a more conventional vacuum mixing and delivery system replaced the cartridge system.

Analysis and evaluation of new technology is, of course, important and is required in the United States by the Food and Drug Administration. The index study and patient population were based on participation in the United States’ Boneloc cement Investigational Device Exemption during the years 1991 to 1993. We present the results of the cemented total hip arthroplasties done at our institution.

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.[3-5]

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).


At last follow-up, 7 hips showed failure both clinically and radiographically. Of these, 4 had been revised (stem only in 1, cup only in 2, and both stem and cup in 1). All failures occurred between 2 and 5 years postoperatively. Three patients had radiographic evidence of loosening,[8-13] as well as pain and clinical failure.[6] Two of them had radiographic evidence of stem subsidence and had pain with weight-bearing and passive range of motion. One patient had radiographic evidence of stem subsidence and a change in position of the cup, as well as pain on weight-bearing and passive range of motion. These 3 patients were awaiting revision surgery.

The 13 patients without either clinical or radiographic signs of loosening had an average follow-up of 42 months (11 to 58 months). The average hip score[6] at last follow-up was 89.6 (range, 53 to 100). Results were rated as excellent in 8 (61%), good in 4 (31%), and poor in 1 (8%).

The overall failure rate (radiographic loosening of at least one component, clinical failure, and/or revision surgery) was 35% at an average follow-up of 42 months. The femoral component failed at an overall rate of 25% and the acetabular component at an overall failure rate of 20%.


Surgical techniques and procedures are always evolving, and surgeons strive to improve on what they know. It is difficult to decide when a new product should be introduced, especially when the new product is designed to replace or improve on an existing product that has a long history of clinical success. This notion is further convoluted by the fact that surgical products are commonly introduced with financial incentives by industry. When a new product or procedure is introduced to the medical community, it is imperative to compare its performance with the established standards of care. The use of cement for component fixation in total hip arthroplasty has a well-documented history with respect to survivorship and clinical success. Therefore, historic controls were readily available for comparison when evaluating Boneloc cement. Polymethyl methacrylate acts as a grout and forms a mechanical link or interlock between an implant and the bone. The cement is a weak link in this bone-cement-prosthesis construct.

Unfavorable mechanical properties such as low tensile or fatigue strength, poor fracture toughness, and a low elastic modulus compared with cortical bone or prosthetic metals may lead to cement failure.[14] When disrupted by bony resorption or mechanical failure of the cement, the interlock is lost and loosening results. Loosening therefore can be the result of biologic or mechanical factors. The primary objective for Boneloc was to create a cement that improved the mechanical and chemical properties of conventional polymethyl methacrylate. It was believed that the efficacy would be improved by decreasing bone necrosis as well as more subtle chemical and thermal damage to bone during implantation. Therefore, the material was designed to reduce the exothermic temperatures generated during polymerization, to lower residual monomer content, and to have a lower solubility and a higher molecular weight. Charnley performed what is considered to be the benchmark series of cemented total hip arthroplasties even without the use of what are considered modern cement techniques.[4,12-14] In 1973, Charnley and Cupic[1] reported a 92% satisfactory outcome at 9 and 10 years of follow-up. In 1986, Wroblewski[15] reviewed the Charnley and Cupic series at a 15- to 21-year follow-up and found that 85% of the survivors with an intact implant were pain free and 11% had only occasional discomfort. Several other reports cite excellent survivorship over long-term follow-up. Hozack et al[16] reported 99% survivorship of the acetabular component and 96% survivorship of the femoral component of 1,041 Charnley total hip arthroplasties at 10-year follow-up. McCoy et al[17] reported a survivorship of 91% at 15 years in 100 Charnley low-friction arthroplasties. The acetabular survivorship was 98% and femoral survivorship 93%, with 87% good or excellent clinical scores. Sarmiento et al[18] reported an 11-year survivorship of 91.4% and 92.7% when Charnley and Sarmiento prostheses were compared.

Recent data on cemented total hip arthroplasty using conventional bone cements have similarly shown good long-term results. Keisu and Lindgren[19] had a 10-year revision rate of 5% using the Harris-Design 2 chrome-cobalt femoral implant and an all-polyethylene acetabular implant cemented with CMW-1 (Wright Medical Technologies, Arlington, Tenn) or Palacos (Smith & Nephew, Memphis, Tenn) bone cements. Ziegler and Lachiewicz[20] reported an acetabular revision rate of 10% and a femoral revision rate of 8.6% at an average follow-up of 9 years in 70 total hip arthroplasties cemented with Simplex-P cement (Stryker-Howmedica-Osteonics, Allendale, NJ). Mulroy and Harris[4] reported 3% femoral loosening in 105 hips at 10-year follow-up using Simplex-P bone cement and second-generation techniques. Marston et al[21] reported a 4% revision rate at 6.5 years in 413 hips cemented with Simplex-P cement.

These series reflect the historic standards against which cemented total hip arthroplasties using new technologies must be judged, since it is the expectation that the new technology, products, or procedures should match if not exceed the efficacy, safety, and durability of those that are already established. While one could question the ability to improve on the historic success of cemented arthroplasty using Simplex-P, Palacos, and CMW, Biomet developed Boneloc cement to achieve two objectives: (1) to improve longevity and efficacy by decreasing the chemical and thermal damage to bone during implantation, and (2) to create a product that was safer for operating room personnel.

With the development of Boneloc cement, Biomet created a more biocompatible monomer mixture that polymerized more completely and generated less heat during polymerization (62°C vs 70° to 82°C).[22] Wykman and Sandersjoo[23] reported a maximum attained temperature of 43°C at the bone-cement interface in 10 of 11 acetabuli cemented with Boneloc cement. This was a considerable reduction in polymerization exotherm temperature compared with earlier studies using conventional bone cements. In addition, the delivery system appeared to decrease exposure to the noxious cement fumes. Unfortunately, although these goals were attained, the clinical success of the product was poor. The index series (the only US report) revealed a dismal outcome over a relatively short follow-up. European series reflected a similarly unacceptably high rate of failure. In Denmark, Riegels-Nielsen et al[24] reported loosening in 24 of 43 hips cemented with Boneloc at an average 18-month follow-up. In a Norwegian series, Nilsen and Wiig[25] reported loosening in 102 of 157 hips at an average follow-up of 2 years. In Finland, Suominen[26] reported loosening in 4 of 8 stems in hybrid reconstructions after only 32 months of follow-up. Thanner et al[27] postulated that the failure in these cases was due to poor mechanical properties such as a reduced tensile strength and elastic modulus when compared with a standard cement (Palacos). In addition, an increased amount of monomer appeared to be released from the cement, contrary to one of the original objectives for the Boneloc cement.

Because of these reports of possible early failure of the bone cement at both the femoral and acetabular component interfaces, Boneloc cement was withdrawn from the market in April 1995. Negative publicity, poor sales, and the pending nature of the Food and Drug Administration investigational device exemption contributed to the withdrawal. Although Boneloc cement was never released for general use in the United States, continued follow-up and evaluation of the cement is important. Knowledge of this and other new cements may explain otherwise unclear failure of a cemented construct in a new patient, as well as provide insight into the evaluation of other new cements. The results of this trial certainly provide food for thought when contemplating participation in an investigational protocol or when beginning use of an approved but as yet unproven new product.


Despite initial promise, Boneloc cement was found to have an unacceptably high failure rate over a relatively short follow-up period and is not recommended for use in total hip arthroplasty. Although conventional bone cements and their delivery systems present problems (eg, limited longevity, high exotherm, and noxious airborne material), long-term success has been established. Caution should be exerted before using new cement technology.


  1. Charnley J, Cupic Z: The nine and ten year results of the low friction arthroplasty of the hip. Clin Orthop 95:9, 1973
  2. Hardinge K: The direct lateral approach to the hip. J Bone Joint Surg Br 64:17, 1982
  3. Mulroy WF, Estok LI, Harris WH: Total hip arthroplasty with the use of so-called second-generation cementing techniques. a fifteen-year average follow-up study. J Bone Joint Surg Am 77:1845-1852, 1995
  4. Mulroy RD, Harris WH: The effect of improved cementing techniques on component loosening in total hip replacement. J Bone Joint Surg Br 72:757, 1990
  5. Oishi CS, Walker RH, Colwell CW Jr: The femoral component in total hip arthroplasty. six to eight year follow-up of 100 consecutive patients after use of third-generation cementing techniques. J Bone Joint Surg Am 76:1130-1136, 1994
  6. Harris WH: Traumatic arthritis of the hip after dislocation and acetabular fractures: treatment by mold arthroplasty. J Bone Joint Surg Am 51:737, 1969
  7. Yoder SA, Brand RA, Pedersen DR, et al: Total hip acetabular component position affects component loosening rates. Clin Orthop 228:79-87, 1988
  8. Gruen TA, McNeice GM, Amstutz HC: Modes of failure of cemented stem-type femoral components: a radiologic analysis of loosening. Clin Orthop 141:17, 1979
  9. DeLee JG, Charnley J: Radiological demarcation of cemented sockets in total hip replacement. Clin Orthop 121:20, 1976
  10. Harris WH, White RE: Socket fixation using a metal-backed acetabular component for total hip replacement. J Bone Joint Surg Am 64:745-748, 1982
  11. Dorr LD, Takei GK, Conaty JP: Total hip arthroplasty in patients less than 45 years old. J Bone Joint Surg Am 65:474-479, 1983
  12. Harris WH, McCarthy JC Jr, O’Neill DA: Femoral component loosening using contemporary techniques of femoral cement fixation. J Bone Joint Surg Am 64:1063, 1982
  13. Harris WH, McGann WA: Loosening of the femoral component after use of the medullary-plug cementing technique. J Bone Joint Surg Am 68:1064, 1986
  14. Berry DJ, Chao EYS: Cemented femoral components. Reconstructive Surgery of the Joints. Morrey BF (ed). New York, Churchhill-Livingstone, 2nd Ed, 1996, pp 943-960
  15. Wroblewski BM: 15-21 year results of the Charnley low-friction arthroplasty. Clin Orthop 211:30, 1986
  16. Hozack WJ, Rothman RH, Booth RE, et al: Survivorship analysis of 1041 Charnley total hip arthroplasties. Proceedings of the AAOS 55th Annual Meeting, Atlanta, Ga, Feb 4-9, 1988
  17. McCoy TH, Salvati EA, Ranawat CS, et al: A fifteen-year follow-up study of 100 Charnley low-friction arthroplasties. Orthop Clin North Am 19:467, 1988
  18. Sarmiento A, Natarajan V, Gruen TA, et al: Radiographic performance of two different total hip cemented arthroplasties: a survivorship analysis. Orthop Clin North Am 19:505, 1988
  19. Keisu K, Lindgren U: Outcome of total hip arthroplasties with cement. J Arthrop 11:789, 1996
  20. Ziegler BS, Lachiewicz PF: Survivorship analysis of cemented total hip arthroplasty acetabular components implanted with second-generation techniques. J Arthrop 11:750, 1996
  21. Marston RA, Cobb AG, Bentley G: Stanmore compared with Charnley total hip replacement. J Bone Joint Surg Br 78:178, 1996
  22. Kindt-Larsen T, Smith DB, Jensen JS: Innovations in acrylic bone cement and application equipment. J Appl Biomaterials 6:75-83, 1995
  23. Wykman AG, Sandersjoo GA: Low polymerization temperature with Boneloc. in vivo measurements in 11 hip replacements. Acta Orthop Scand 66:218, 1995
  24. Riegels-Nielsen P, Sorensen L, Andersen HM, et al: Boneloc cemented total hip prosthesis. loosening in 28/43 cases after 3-38 months. Acta Orthop Scand 66:215, 1995
  25. Nilsen AR, Wiig M: Total hip arthroplasty with Boneloc: loosening in 102/157 cases after 0.5-3 years. Acta Orthop Scand 67:57, 1996
  26. Suominen S: Early failure with Boneloc bone cement. 4/8 femoral stems loose within 3 years. Acta Orthop Scand 66:13, 1995
  27. Thanner J, Freij-Larsson C, Karrholm J, et al: Evaluation of Boneloc. chemical and mechanical properties, and a randomized clinical study of 30 total hip arthroplasties. Acta Orthop Scand 66:207, 1995


Technorati Tags: , , , , , , , , , , , , , , , , ,