The purpose of this randomized clinical trial was to compare the >20-year outcomes of cemented (n=124) versus cementless (n=126) total hip replacements (THRs) in patients with end-stage, unilateral hip osteoarthritis. At 20 years, 168 patients (67%) were available for follow-up, 78 (31%) had died, and 4 (2%) were lost.
A power analysis was performed to determine the number of patients needed in each study cohort. Patients were assessed pre- and postoperatively by validated disease-specific Western Ontario McMaster Osteoarthritis Score, patient-specific McMaster Arthritis Score, global health (sickness impact profile), functional capacity (6-minute walk), and cost utility (cost-to-quality adjusted life years). Patients were followed every 2 years clinically and radiographically.
The cementless THR outperformed its cemented counterpart in terms of overall (P=.01), socket (P=.009), and stem (P<.0001) Kaplan-Meier survivorships. Patients younger than 65 years had significantly poorer cemented and cementless socket survivorships, and male sex adversely affected cementless socket survivorship. The cementless tapered stem had 100% survivorship with aseptic loosening as the endpoint at 20 years. Although this study has demonstrated the superiority of the cementless THR over its cemented counterpart, care must be taken in generalizing these results to other cemented and cementless THRs.
Since the mid-1980s, controversy has existed about whether cemented or cementless fixation provides superior total hip replacement (THR) outcomes.1 To address this issue, we performed a double-blind, randomized clinical trial to compare 1 cemented THR with its cementless counterpart.2,3 The purpose of this study was to report the >20-year survivorship results of this clinical trial.
Materials and Methods
After obtaining institutional review board approval for our study and funding from the Medical Research Council of Canada, a double-blind, randomized clinical trial was instituted to compare cemented versus cementless THRs in patients with end-stage, unilateral hip osteoarthritis. We studied the Mallory Head cemented and cementless THRs (Biomet, Inc, Warsaw, Indiana).4 A power analysis was performed to determine the number of patients needed in each study cohort. Patients were assessed pre- and postoperatively as validated disease-specific Western Ontario McMaster Osteoarthritis Score (WOMAC), patient-specific McMaster Arthritis Score (MACTAR), global health (sickness impact profile), functional-capacity (6-minute walk) and cost-utility (cost-to-quality adjusted life years). Patients were followed every 2 years clinically and radiographically.
The cemented (n=124) and cementless (n=126) cohorts were of comparable size. At 20-year follow-up, 78 (31%) patients had died, 4 (2%) were unavailable for follow-up, and 168 (67%) were available for follow-up. The cementless Mallory Head THR (Figure 1) outperformed its cemented counterpart regarding Kaplan-Meier survivorships overall (P=.01) (Figure 2), for the socket (P=.001) (Figure 3), and for the stem (P<.0001) (Figure 4).5
Figure 1: Photograph of the Mallory Head cemented and cementless THRs studied.
Figure 2: Kaplan-Meier survivorship curve comparing overall survivorship of the cemented and cementless Mallory Head THRs at 20 years.
Figure 3: The Kaplan-Meier survivorship curve comparing acetabular socket survivorship of the cemented and cementless Mallory Head THR at 20 years.
Figure 4: The Kaplan-Meier survivorship curve comparing femoral stem survivorship of the cemented and cementless Mallory Head THRs at 20 years.
For the acetabular socket, male sex adversely effected cementless socket survivorship (revision rate for men was 31% vs 12% in women; P=.01), but not cemented socket survivorship (revision rate for men was 35% vs 36% in women; P=1.00). Age younger or older than 65 years significantly effected both cementless (>65, 12% vs <65, 36%; P=.003) and cemented (>65, 19% vs <65, 55%;P<.0001) acetabular socket revision rates.
For the femoral stems, gender did not affect cementless (men 1%, women 0%; P=1.000) or cemented (men 25%, women 22%; P=.829) revision rates. Age younger or older than 65 years did not influence cementless femoral stem survivorship (>65, 0%; <65, 2%; P=.465), but did so for cemented (>65, 16%; <65, 33%; P=.32) stems.
Health-related2,3 and radiographic6 outcomes of this study have been published elsewhere.
This randomized clinical trial comparing a single cemented to cementless THR has demonstrated that the Mallory Head cementless THR provides significantly better 20-year survivorship than its cemented counterpart. Cementless, tapered, proximally porous-coated, femoral stems performed particularly well with 100% survivorship at 20 years, excluding infections. Care should be taken in extrapolating these results to contemporary THRs, as the implants studied had many features that are no longer used today (ie, gamma-in-air sterilization of the polyethylene; ion-implanted titanium-alloy femoral heads; titanium-alloy-cemented stems; metal-backed cemented acetabular sockets; and a first generation cementless socket design). Caution should also be taken in generalizing these findings to other cemented and cementless THRs.
Nevertheless, this study has allowed us to conclude that cementless tapered femoral stems yield long-lasting fixation equaling or surpassing the best reported cemented-stem results.
- Rothman RH, Cohn JC. Cemented versus cementless total hip arthroplasty. A critical review. Clin Orthop Relat Res. 1990; (254):153-169.
- Laupacis A, Bourne RB, Rorabeck CH, Feeny D, Wong C, Tugwell P. Comparison of total hip arthroplasty with and without cement: A randomized clinical trial. J Bone Joint Surg Am. 2002; 84(10):1823-1828.
- Rorabeck CH, Bourne RB, Laupacis A, et al. A double-blind study of 250 cases comparing cemented with cementless total hip arthroplasty. Cost-effectiveness and its impact on health-related quality of life. Clin Orthop Relat Res. 1994; (298):156-164.
- Bourne RB, Rorabeck CH, Patterson JJ, Guerin J. Tapered titanium cementless total hip replacements: a 10- to 13-year followup study. Clin Orthop Relat Res. 2001; (393):112-120.
- Kaplan EL, Meier P. Nonparametric estimation from incomplete observations. J Am Stat Assoc. 1958; (53):457-481.
- Mulliken BD, Bourne RB, Rorabeck CH, Nayak N. A tapered titanium femoral stem inserted without cement in a total hip arthroplasty. Radiographic evaluation and stability. J Bone Joint Surg Am. 1996; 78(8):1214-1225.
Drs Bourne and Corten are from the Adult Reconstructive Unit, University Hospital, University of Western Ontario, London, Ontario, Canada.
Drs Bourne and Corten have no relevant financial relationships to disclose.
Presented at Current Concepts in Joint Replacement 2009 Winter Meeting; December 9-12, 2009; Orlando, Florida.
Correspondence should be addressed to: Robert B. Bourne, MD, FRCSC, University Hospital, 339 Windermere Rd, London, Ontario, Canada N6A 5A5 (email@example.com).