Skip to main content
NCBI home page
Clinical Orthopaedics and Related Research logoLink to Clinical Orthopaedics and Related Research
. 2020 Mar 11;478(6):1283–1291. doi: 10.1097/CORR.0000000000001203

What Is the Long-term (27- to 32-year) Survivorship of an Uncemented Tapered Titanium Femoral Component and Survival in Patients Younger Than 50 Years?

Marcus R Streit 1,2,✉, Burkhard Lehner 1,2, David S Peitgen 1,2, Moritz M Innmann 1,2, Georg W Omlor 1,2, Tilman Walker 1,2, Christian Merle 1,2, Babak Moradi 1,2
PMCID: PMC7319397  PMID: 32187099

Abstract

Background

Uncemented femoral components in primary THA are in widespread use, especially in patients younger than 50 years, but few studies have evaluated their survival into the late third and early fourth decade.

Questions/purposes

We evaluated (1) survivorship using femoral revision for any reason as the endpoint, (2) survivorship using femoral revision for aseptic loosening as the endpoint, (3) survival in patients younger than 50 years, (4) cumulative incidence of stem revision for periprosthetic femoral fracture and (5) the overall risk of revision (change of any part of the implanted components) at a minimum of 27 years of follow-up with an uncemented tapered titanium stem still in clinical use today.

Methods

We reviewed the clinical and radiographic results of 326 THAs performed in 326 patients (for 28 patients with bilateral THA, only the first hip was included in the analysis to ensure independent observations) using an uncemented grit-blasted, tapered collarless titanium alloy (TiAl6Nb7) stem between January 1985 and December 1989. In that same timeframe, we performed 1038 primary THAs. During that time, we used cementless stems in patients without severe femoral canal deformity and adequate bone stock for uncemented femoral fixation as determined by using the indication criteria described by the developer. In all, 34% (354 of 1038) were cementless; all cementless stems implanted during that time were the stem being studied here. No others were used. The mean (range) age at the time of surgery was 56 years (13-81 years). Sixty-seven patients were younger than 50 years at the time of primary THA. A competing risk survivorship analysis was used to estimate long-term survival. The minimum follow-up was 27 years (mean 28 years; range 27-32 years); at that time, 169 patients had died, and four patients were lost to follow-up.

Results

Survivorship at 28 years with revision of the femoral component for any reason as the endpoint was 87% (95% CI 83 to 90). Survivorship for femoral revision for aseptic loosening as the endpoint was 94% at 28 years (95% CI 90 to 96). Survival in patients younger than 50 years at the time of primary THA was 89% (95% CI 78 to 95) and 95% (95% CI 86 to 98) at 28 years for the endpoints of all stem revisions and aseptic stem loosening, respectively. The overall cumulative incidence of stem revision for periprosthetic femoral fracture was 4% (95% CI 2 to 7) at 28 years. The overall THA survival rate at 28 years with revision for any reason as the endpoint was 57% (95% CI 51 to 62).

Conclusions

Uncemented femoral fixation of a tapered collarless titanium alloy stem was reliable into the early fourth decade, especially in patients younger than 50 years. Late stem failures in the third and early fourth decade were mainly because of periprosthetic femoral fracture, while aseptic loosening occurred in undersized stems during the early second decade.

Level of Evidence

Level IV, therapeutic study.

Introduction

There are few reports on the survival of uncemented stems with a follow-up of 25 years or more [9, 15, 17, 21, 25], which might be relevant especially for younger patients undergoing THA. Highly active patients with longer life expectancies place high demands on prosthetic components and the implant-bone interface. To determine the long-term durability of cementless femoral components compared with cemented femoral fixation in the late third decade [3], data with a minimum follow-up period of 25 years in young patients are needed.

We previously reported the mean (range) 22-year (20-25 years) follow-up data of this patient cohort [31]. However, there are few studies on cementless femoral stems with minimum 25 years follow-up that are still in clinical use today [15, 21, 25, 28], and there is only one study evaluating the results of a cementless stem still available on the market in patients younger than 50 years [17, 21] of a cementless stem still available on the market in patients younger than 50 years [17, 21].

We therefore sought to determine the (1) survivorship using femoral revision for any reason as the endpoint, (2) survivorship using femoral revision for aseptic loosening as the endpoint, (3) survival in patients younger than 50 years, (4) cumulative incidence of stem revision for periprosthetic femoral fracture and (5) the overall risk of revision (change of any part of the implanted components) at a minimum of 27 years of follow-up using the uncemented tapered titanium CLS Spotorno stem (Zimmer Inc, Warsaw, IN, USA), which is still in clinical use today.

Patients and Methods

We retrospectively evaluated the clinical and radiographic results of a series of 326 THAs performed in 326 patients (for 28 patients with bilateral THA, only the first hip was included in the analysis to ensure independent observations) who underwent surgery between January 1985 and December 1989 with an uncemented grit-blasted, tapered collarless titanium femoral stem (CLS Spotorno stem) (Fig. 1). The FDA cleared this femoral component for use in the United States. Between January 1985 and December 1989, we performed 1038 primary THAs. In all, 34% (354 of 1038) were cementless; all cementless stems implanted during that time were the stem being studied here. No others were used. During that time, we used cementless stems in patients without severe femoral canal deformity and adequate bone stock for uncemented femoral fixation as determined by using the indication criteria described by the developer Spotorno et al. [29]. This indication protocol uses five parameters: age (0-4 points), sex (0-1 point), Singh index for osteoporosis [27] (0-4 points), femoral anatomy as determined by the morpho-cortical index [11] (0-4 points), and planned long-term cortisone therapy (0-1 point). All points are added and the CLS stem was implanted in all patients with 0-4 points in total. The mean (range) age at the time of surgery was 56 years (13-81 years). Sixty-seven patients were younger than 50 years at the time of primary THA. The mean (range) age of the subcohort of patients younger than 50 years was 42 years (13-49 years). The patients’ demographics showed the typical distribution of diagnoses leading to THA (Table 1). Informed consent for inclusion in our center’s research database was obtained from all patients. The institutional review board of the University of Heidelberg approved all procedures and the study was conducted in accordance with the Helsinki Declaration of 1975 as revised in 2008 [34].

Fig. 1.

Fig. 1

Open in a new tab

The photograph shows the uncemented straight titanium alloy (TiAl6Nb7) CLS Spotorno (Zimmer, Warsaw, IN, USA) femoral component with proximal fins and a grit-blasted surface finish.

Table 1.

Diagnoses in the 326 patients (100%)

graphic file with name abjs-478-1283-g002.jpg

Open in a new tab

The femoral stems had a neck-shaft angle of 145° and were implanted using the press-fit technique described by Spotorno et al. [29]. The rectangular stem is collarless, wedge-shaped, and tapered in all three planes with proximal-, anterior-, and posterior-located ribs or flutes (Fig. 1). The implant is made of TiAl6Nb7 alloy with a microporous surface treatment (Ra = 4.4 μm). Secondary osseointegration is achieved by osseous on-growth to the grit-blasted implant surface. This component has remained relatively unchanged since its first implantation in 1984, except for a minor modification to the shape of the ribs in 1992 (proximally sharpened edges to enhance stem penetration and reduce the risk of fissures) and two offset options added in 1997 (135°) and 2004 (125°).

Ninety-eight percent (320 of 326) of hips underwent acetabular reconstruction using smooth and uncemented threaded cups; 205 of 326 hips (63%) received threaded, spherical, and uncemented Mecron cups (Mecron GmbH, Berlin, Germany) and 115 of 326 hips (35%) received a threaded, conical, uncemented Weill ring (Zimmer Inc). Six of 326 hips (2%) received cemented cups (B. Braun Aesculap, Tuttlingen, Germany). In all hips, ultra-high-molecular-weight polyethylene bearing surfaces and 32-mm Al2O3 ceramic heads (Biolox; CeramTec, Plochingen, Germany) were used.

Twenty-three surgeons performed the procedures at our center. We used either a modified Watson-Jones approach or the transgluteal lateral approach of Bauer et al. [2] with the patient in the supine position. The femoral canal was prepared using a series of chip-toothed broaches of increasing size. No attempt was made to achieve cortical fixation; the surgeons did not consider that cortical contact would be necessary to achieve stability with this implant and relied on the feel of rotational and axial stability to determine fit. Fixation was regarded as satisfactory when a series of moderate hammer blows did not change the final position of the femoral implant.

Postoperative partial weightbearing was encouraged for 6 weeks and thereafter as tolerated. No regular prophylaxis (such as irradiation or NSAIDs) to prevent heterotopic ossification was given.

Patients were followed at regular intervals at 3 months, 6 months, 1 year, and every 5 years thereafter [13]. For radiographic evaluation, standard pelvic AP and lateral radiographs of the hip were taken. Osteolysis at the femoral bone-prosthesis interface were evaluated using the zones described by Gruen et al. [12]. Femoral component fixation was graded according to the criteria described by Engh et al. [10]. Femoral component loosening was defined as progressive distal implant migration or if there were unambiguous clinical signs of femoral loosening. The canal-fill index was defined as the ratio of the implant to canal width in the AP plane at 3 cm below the level of the lesser trochanter, as described previously [19], and measured on an intraoperative or first postoperative radiograph. Our criterion for defining an undersized stem was a canal-fill index of ≤ 80%.

At a minimum of 27 years postoperatively, 169 patients had died, and four were lost to follow-up (Fig. 2). The mortality rate in this study cohort was comparable to that of the native population in Germany [30]. In the patients who died, the femoral prosthesis was in situ at the time of death. We excluded revision surgery between the last clinical review and death in deceased patients using information from relatives, health insurance, general practitioners, or a review of clinical notes. Forty-three hips (13%) underwent femoral revision and the remaining 110 hips were available for review at a minimum follow-up of 27 years (mean 28 years; range 27-32 years).

Fig. 2.

Fig. 2

Open in a new tab

This flowchart demonstrates the distribution of hips at the final follow-up examination.

A competing risk and Kaplan-Meier survivorship analysis was used to determine long-term survival rates for different endpoints. Although the competing-risks estimator is the more appropriate one for this dataset, the differences between the two estimators here in fact were very small, and so we are presenting both analyses to facilitate comparisons with earlier studies on related topics (Table 2). We considered p values of < 0.05 to be significant. SPSS version 24 (SPSS Inc, Chicago, IL, USA), NCSS 2019 Statistical Software (NCSS, LLC, Kaysville, Utah, USA) and Graphpad Prism version 6.01 (Graphpad Software, La Jolla, CA, USA) were used to record and analyze the data.

Table 2.

Results of uncemented and cemented femoral components with 25-year follow-up

graphic file with name abjs-478-1283-g004.jpg

Open in a new tab

Results

Competing risk survivorship at 28 years, using revision of the femoral component for any reason as the endpoint (Fig. 3), was 87% (95% CI 83 to 90; 78 hips at risk). Of the 43 hips with femoral revision, 11 underwent revision for infection, 13 underwent revision for late periprosthetic fracture and stem loosening resulting from trauma, and 19 underwent revision for aseptic stem loosening.

Fig. 3.

Fig. 3

Open in a new tab

This graph shows the competing risk survivorship curve and 95% CI with femoral revision for any reason as the endpoint. Twenty-eight-year survival was estimated as 87% (95% CI 83 to 90; 78 hips at risk).

Survivorship at 28 years using femoral revision for aseptic loosening as the endpoint was 94% (95% CI 90 to 96; 78 hips at risk) (Fig. 4).

Fig. 4.

Fig. 4

Open in a new tab

This graph shows the competing risk survivorship curve and 95% CI with femoral revision for aseptic loosening as the endpoint. Twenty-eight-year survival was estimated as 94% (95% CI 90 to 96; 78 hips at risk).

Survival in patients younger than 50 years at the time of primary THA was 89% (95% CI 78 to 95; 29 hips at risk) and 95% (95% CI 86 to 98; 29 hips at risk) at 28 years for the endpoints of all stem revisions (Fig. 5) and aseptic stem loosening (Fig. 6), respectively.

Fig. 5.

Fig. 5

Open in a new tab

This graph shows the competing risk survivorship curve and 95% CI with femoral revision for any reason as the endpoint in patients younger than 50 years at the time of primary THA. Twenty-eight-year survival was estimated as 89% (95% CI 78 to 95; 29 hips at risk).

Fig. 6.

Fig. 6

Open in a new tab

This graph shows the competing risk survivorship curve and 95% CI with femoral revision for aseptic loosening as the endpoint in patients younger than 50 years at the time of primary THA. Twenty-eight-year survival was estimated as 95% (95% CI 86 to 98; 29 hips at risk).

The overall cumulative incidence of stem revision for periprosthetic femoral fracture was 4% (95% CI, 2%-7%; 78 hips at risk) at 28 years.

The overall THA survival rate at 28 years with revision for any reason as the endpoint was 57% (95% CI 51 to 62, 34 hips at risk).

Kaplan-Meier survival estimates using stem revision for any reason and stem revision for aseptic loosening as the endpoint were calculated to facilitate comparisons with earlier studies on related topics, the differences in long-term survival between the two estimators were only small (Table 2). Other than in stems already revised for loosening, there was no radiographic or clinical evidence of definite loosening of the femoral components. Osteolysis around the femoral component was mainly detected in Gruen Zones 1 and 7 (Fig. 7). When comparing the minimum 20-year follow-up with the minimum 27-year follow-up, progressive osteolytic lesions were detected in 20 of 64 hips (31% of the hips that were evaluated radiographically). In 20% (13 of 64) of hips, a new osteolytic lesion developed between the 20-year and 27-year minimum follow-up periods. Twenty-two percent of the stems (71 of 326 hips) had a canal-fill index of ≤ 80% and were graded as undersized at the time of primary THA.

Fig. 7.

Fig. 7

Open in a new tab

This figure illustrates the distribution of radiologic osteolysis in zones according to Gruen et al. [12] and its mean area and SD at a minimum of 27 years of follow-up.

Discussion

Cementless femoral stems have been studied extensively and have been shown to be successful over the 15- to 20-year follow-up period with survival rates ranging from 87% to 98% [22]; however, few studies have evaluated the survival with a follow-up of 25 years or more. THA indications are expanding to younger patients [26]; by the year 2030, 52% of primary THAs are projected to be implanted in patients younger than 65 years, with the strongest increase in patients aged 45-55 years [18]. Consequently, it is important for patients, arthroplasty surgeons, and public healthcare authorities to estimate the durability of available implants into the third and fourth decade after surgery. Further, it is important to know which long-term complications are associated with the procedure to improve shared decision making. In this study, using a cementless femoral component that is still in frequent clinical use, we found a stem survival of 87% at 28 years after surgery using stem revision for any reason as the endpoint. Stem survival using aseptic loosening as the endpoint was 94% at 28 years. The cumulative stem survival in patients younger than 50 years of age at the time of THA was not inferior (89% and 95% for the endpoints any stem revision and stem revision for aseptic loosening at 28 years) to survival in older patients. An increasingly important failure mode in the third and fourth decade was stem revision for periprosthetic femoral fracture with a cumulative incidence of 4% at 28 years. Due to the high acetabular failure rate, THA survival was 57% at 28 years using any implant revision as the endpoint. Our long-term results into the fourth decade after surgery support the use of uncemented titanium femoral components in THA, especially in young patients. Patients should be informed about the main stem failure modes in the long-term, predominantly about the risk and incidence of periprosthetic femoral fracture.

The major limitations of the study are the high rate of acetabular revisions and undersized stems with a canal-fill index less than 80%, which may have biased the results. On the one hand, hips that have undergone acetabular revision surgery might be at risk for stem revision due to infection, dislocation, or other complications. However, those patients may have a lower functional outcome after revision surgery, be less active, and put lower strain on the stem and therefore may have a lower risk for aseptic stem loosening. Undersized stems show higher rates of aseptic loosening during the second decade [31]. When compared with later series in which the CLS Spotorno stem was combined with a good performing acetabular component and the percentage of undersized stems was lower, the stem survival in the present study was considerably lower [32, 33]. Further, there might be a selection bias as indications for cementless stems have changed over the last 30 years, and cementless stems are being used more frequently in older patients. When the stems in this study were implanted, only 34% of hips were implanted with cementless stems; however, these numbers have changed and, today, in Germany 78% of the hips are cementless. Patients in this study had a relatively low mean age at primary THA, therefore, one should take care when generalizing the findings from this study to an older patient cohort. In addition, there might be an assessment bias; we used stem loosening as the endpoint and due to the lack of preoperative clinical data, it is impossible to compare the preoperative clinical status to the clinical results at final follow-up. Finally, because four patients were lost-to-follow-up, there might be some transfer bias, as in general missing patients do not do as well as those who are accounted for. However, the number of patients lost to follow-up is relatively low compared with the number of revised stems, therefore this bias should not be a severe limitation in this study.

Long-term survival of the CLS Spotorno stem remains excellent into the fourth decade after surgery with a low stem revision rate for any reason at 28 years.

Biological implant fixation using a cementless grit-blasted titanium alloy stem was stable in the long run, as aseptic loosening occurred mainly in grossly undersized stems (canal-fill index less than 80%) during the second decade, while aseptic stem loosening was very rare during the third and early fourth decade (Fig. 4), which is an important finding in this study.

In patients younger than 50 years, we found a 28-year survival rate of 95%, and a survival rate of 98% if the stems were adequately sized (canal-fill index higher than 80% at the time of primary THA) using aseptic stem loosening as the endpoint. The long-term results found in the present study in young patients compare favorably with those of cemented femoral stems in patients younger than 50 years. A systematic review [3] demonstrated minimum 20-year survival rates ranging from 68% to 94% at 25 years using a Kaplan-Meier survivorship analysis for cemented stems in young patients under 50 years. Additionally, 4% to 53% of the stems showed radiographic loosening at the final follow-up examination. The Finnish Arthroplasty Register and Nordic Arthroplasty Register [20, 24] demonstrated survival rates of 81% and 80.5%, respectively, at 15 years for cemented stems in patients 55 years and younger, with the endpoint of aseptic stem loosening. Considering the reported long-term aseptic loosening rates in young patients and the results found in the present study, we believe cementless titanium hip stems with documented high long-term survival are a durable solution for THA in young patients and might be preferred to cemented stems in this patient cohort.

Postoperative periprosthetic femoral fractures after THA are a major concern because they may lead to limited functional results and reduced life expectancy [5, 23]. The cumulative incidence of late periprosthetic femoral fractures with consecutive revision of the stem was 4% at 28 years, and the cumulative incidence of any late periprosthetic femoral fractures was 6.1% at 20 years in our study. Abdel et al. [1] found a 7.7% probability at 20 years for postoperative femoral fractures after cementless arthroplasty and 3.5% probability at 20 years for cemented arthroplasty (including any late fractures). These findings are consistent with our results. Therefore, late periprosthetic femoral fractures are not only an issue with the CLS Spotorno stem but also an important failure mode in cementless hip arthroplasty using other stems as well and, to a lesser extent, in cemented fixation [1, 8]. There are conflicting data about the risk of late periprosthetic femoral fracture between cemented and cementless arthroplasty. Abdel et al. [1] reported higher rates of late periprosthetic femoral fracture in cementless fixation than in cemented fixation. However, data from the New Zealand joint registry showed cementless implants have comparable rates to cemented ones regarding periprosthetic femoral fracture as the reason for revision surgery after 7 years postoperatively [14]. There are only few data about late periprosthetic femoral fractures with stem revisions in the long-term (> 25 years). Jacquot et al. [15] reported that late periprosthetic fractures were the reason for stem revision in one third of patients using the Corail stem (DePuy, Warsaw, IN, USA) at a mean of 27 years postoperatively. The relative stem revision rate for periprosthetic fractures was comparable to our results (four of 12 revised stems), while the total stem revision risk at 27 years was lower in their cohort (4%) than in ours (13% at 28 years). Therefore, we do not believe that late periprosthetic fractures are an implant-specific problem of the CLS stem but might be underreported because of insufficient follow-up periods and inconsistent methods [15].

Overall survival of the THA with revision for any reason as the endpoint (cup and/or stem) was estimated at 57% at 28 years and therefore can be considered as low in the long-term due to the poor performance of the smooth threaded cups used in this series. Jacquot et al. [15] reported 74% survival with any THA revision as the endpoint in their long-term follow-up of the Corail stem mainly using roughened, HA-coated titanium-backed press-fit cups. Pisecky et al. [25] reported 85% survival at 30 years using the Zweymüller stem (AlloPro/Sulzer Medica, Winterthur, Switzerland and Centerpulse, Winterthur, Switzerland) mainly in combination with the grit-blasted, titanium Alloclassic CSF cup (AlloPro/Sulzer Medica, Winterthur, Switzerland and Centerpulse, Winterthur, Switzerland). Slaven et al. [28] reported 75% survival at 27 years using the porous-coated anatomic THA. Berry et al. [4] reported 81% survival for cemented Charnley THA at 25 years postoperatively.

Small focal osteolysis was mainly limited to Gruen zones 7 (41%) and 1 (10%). Jacquot et al. [15] reported radiolucencies around 23% of the Corail stems mostly seen in the proximolateral region; they were nonprogressive and not clinically relevant at final follow-up. Pisecky et al. [25] reported 70% of focal osteolysis in Gruen zone 1 and 21% in Gruen zone 7 for the Zweymülller stem. McLaughlin et al. [21] reported osteolysis in 10% of the hips using the Taperloc (Zimmer Biomet, Warsaw, IN, USA) stem, most commonly in zone 1. Slaven et al. [28] described osteolysis in 27% of the femoral components using the PCA hip system. Kim et al. [17] reported femoral osteolysis in zones 1 and 7 in 29% of the hips using a cementless stem and in 25% using a cemented hip stem. In none of these reports did femoral osteolysis affect the clinical outcome or lead to failures of the femoral component, which is in contrast to the acetabular site.

In conclusion, uncemented femoral fixation of a cementless titanium alloy femoral stem was reliable into the early fourth decade, especially in patients younger than 50 years. Late stem failures in the third and early fourth decade were mainly because of periprosthetic femoral fracture, while aseptic loosening occurred in undersized stems during the early second decade. Our results might help patients and surgeons to reasonably choose the type of stem fixation with regard to long-term outcome in the context of shared decision making. Future studies should compare the long-term incidence of periprosthetic femoral fracture between different cementless stem designs, especially those of straight stems and the increasingly popular short stems because periprosthetic femoral fracture seems to be an important long-term failure mode on the femoral side after cementless THA.

Acknowledgments

We thank Prof. Dr. Peter Aldinger, of the Orthopädische Klinik Paulinenhilfe in Stuttgart, Germany, for his inspiring mentorship and help with interpretation of the data.

Footnotes

Each author certifies that neither he, nor any member of his immediate family, has funding or commercial associations (consultancies, stock ownership, equity interest, patent/licensing arrangements, etc.) that might pose a conflict of interest in connection with the submitted article.

All ICMJE Conflict of Interest Forms for authors and Clinical Orthopaedics and Related Research® editors and board members are on file with the publication and can be viewed on request.

Clinical Orthopaedics and Related Research® neither advocates nor endorses the use of any treatment, drug, or device. Readers are encouraged to always seek additional information, including FDA approval status, of any drug or device before clinical use.

Each author certifies that his institution approved the human protocol for this investigation and that all investigations were conducted in conformity with ethical principles of research.

This work was performed at the University of Heidelberg, Heidelberg, Germany.

The first two authors contributed equally to this work.

References

  • 1.Abdel MP, Watts CD, Houdek MT, Lewallen DG, Berry DJ. Epidemiology of periprosthetic fracture of the femur in 32 644 primary total hip arthroplasties: a 40-year experience. Bone Joint J. 2016;98-B:461-467. [DOI] [PubMed] [Google Scholar]
  • 2.Bauer R, Kerschbaumer F, Poisel S, Oberthaler W. The transgluteal approach to the hip joint. Arch Orthop Trauma Surg. 1979;95:47-49. [DOI] [PubMed] [Google Scholar]
  • 3.Bedard NA, Callaghan JJ, Stefl MD, Liu SS. Systematic review of literature of cemented femoral components: what is the durability at minimum 20 years followup? Clin Orthop Relat Res. 2015;473:563-571. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 4.Berry DJ, Harmsen WS, Cabanela ME, Morrey BF. Twenty-five-year survivorship of two thousand consecutive primary Charnley total hip replacements: factors affecting survivorship of acetabular and femoral components. J Bone Joint Surg Am. 2002;84-A:171-177. [DOI] [PubMed] [Google Scholar]
  • 5.Boylan MR, Riesgo AM, Paulino CB, Slover JD, Zuckerman JD, Egol KA. Mortality following periprosthetic proximal femoral fractures versus native hip fractures. J Bone Joint Surg Am. 2018;100:578-585. [DOI] [PubMed] [Google Scholar]
  • 6.Buckwalter AE, Callaghan JJ, Liu SS, Pedersen DR, Goetz DD, Sullivan PM, Leinen JA, Johnston RC. Results of Charnley total hip arthroplasty with use of improved femoral cementing techniques. a concise follow-up, at a minimum of twenty-five years, of a previous report. J Bone Joint Surg Am. 2006;88:1481-1485. [DOI] [PubMed] [Google Scholar]
  • 7.Callaghan JJ, Bracha P, Liu SS, Piyaworakhun S, Goetz DD, Johnston RC. Survivorship of a Charnley total hip arthroplasty. A concise follow-up, at a minimum of thirty-five years, of previous reports. J Bone Joint Surg Am. 2009;91:2617-2621. [DOI] [PubMed] [Google Scholar]
  • 8.Carli AV, Negus JJ, Haddad FS. Periprosthetic femoral fractures and trying to avoid them: what is the contribution of femoral component design to the increased risk of periprosthetic femoral fracture? Bone Joint J. 2017;99:50-59. [DOI] [PubMed] [Google Scholar]
  • 9.Cruz-Pardos A, Garcia-Rey E, Garcia-Cimbrelo E. Total hip arthroplasty with use of the cementless Zweymuller Alloclassic system: a concise follow-up, at a minimum of 25 years, of a previous report. J Bone Joint Surg Am. 2017;99:1927-1931. [DOI] [PubMed] [Google Scholar]
  • 10.Engh CA, Bobyn JD, Glassman AH. Porous-coated hip replacement. The factors governing bone ingrowth, stress shielding, and clinical results. J Bone Joint Surg Br. 1987;69:45-55. [DOI] [PubMed] [Google Scholar]
  • 11.Engh CA, Massin P, Suthers KE. Roentgenographic assessment of the biologic fixation of porous-surfaced femoral components. Clin Orthop Relat Res. 1990:107-128. [PubMed] [Google Scholar]
  • 12.Gruen TA, McNeice GM, Amstutz HC. "Modes of failure" of cemented stem-type femoral components: a radiographic analysis of loosening. Clin Orthop Relat Res. 1979:17-27. [PubMed] [Google Scholar]
  • 13.Harris WH. Traumatic arthritis of the hip after dislocation and acetabular fractures: treatment by mold arthroplasty. An end-result study using a new method of result evaluation. J Bone Joint Surg Am. 1969;51:737-755. [PubMed] [Google Scholar]
  • 14.Hooper GJ, Rothwell AG, Stringer M, Frampton C. Revision following cemented and uncemented primary total hip replacement: a seven-year analysis from the New Zealand Joint Registry. J Bone Joint Surg Br. 2009;91:451-458. [DOI] [PubMed] [Google Scholar]
  • 15.Jacquot L, Bonnin MP, Machenaud A, Chouteau J, Saffarini M, Vidalain JP. Clinical and radiographic outcomes at 25-30 years of a hip stem fully coated with hydroxylapatite. J Arthroplasty. 2018;33:482-490. [DOI] [PubMed] [Google Scholar]
  • 16.Keener JD, Callaghan JJ, Goetz DD, Pederson DR, Sullivan PM, Johnston RC. Twenty-five-year results after Charnley total hip arthroplasty in patients less than fifty years old: a concise follow-up of a previous report. J Bone Joint Surg Am. 2003;85:1066-1072. [DOI] [PubMed] [Google Scholar]
  • 17.Kim YH, Park JW, Kim JS, Kim IW. Twenty-five- to twenty-seven-year results of a cemented vs a cementless stem in the same patients younger than 50 years of age. J Arthroplasty. 2016;31:662-667. [DOI] [PubMed] [Google Scholar]
  • 18.Kurtz SM, Lau E, Ong K, Zhao K, Kelly M, Bozic KJ. Future young patient demand for primary and revision joint replacement: national projections from 2010 to 2030. Clin Orthop Relat Res. 2009;467:2606-2612. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 19.Laine HJ, Pajamaki KJ, Moilanen T, Lehto MU. The femoral canal fill of two different cementless stem designs. The accuracy of radiographs compared to computed tomographic scanning. Int Orthop. 2001;25:209-213. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 20.Makela KT, Eskelinen A, Pulkkinen P, Paavolainen P, Remes V. Results of 3,668 primary total hip replacements for primary osteoarthritis in patients under the age of 55 years. Acta Orthop. 2011;82:521-529. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 21.McLaughlin JR, Lee KR. Total hip arthroplasty with an uncemented tapered femoral component in patients younger than 50 years of age: a minimum 20-year follow-up study. J Arthroplasty. 2016;31:1275-1278. [DOI] [PubMed] [Google Scholar]
  • 22.Merle C, Clarius M, Aldinger PR. [Long-term results of uncemented stems in total hip arthroplasty: analysis of survival rates with a minimum 15-year follow-up]. Orthopade. 2010;39:80-86. [DOI] [PubMed] [Google Scholar]
  • 23.Moreta J, Aguirre U, de Ugarte OS, Jauregui I, Mozos JL. Functional and radiological outcome of periprosthetic femoral fractures after hip arthroplasty. Injury. 2015;46:292-298. [DOI] [PubMed] [Google Scholar]
  • 24.Pedersen AB, Mehnert F, Havelin LI, Furnes O, Herberts P, Karrholm J, Garellick G, Makela K, Eskelinen A, Overgaard S. Association between fixation technique and revision risk in total hip arthroplasty patients younger than 55 years of age. Results from the Nordic Arthroplasty Register Association. Osteoarthritis Cartilage. 2014;22:659-667. [DOI] [PubMed] [Google Scholar]
  • 25.Pisecky L, Hipmair G, Schauer B, Bohler N. 30-years of experience with the cementless implanted Alloclassic total hip arthroplasty system-An ultra-long-term follow-up. J Orthop. 2018;15:18-23. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 26.Schreurs BW, Hannink G. Total joint arthroplasty in younger patients: heading for trouble? Lancet. 2017;389:1374-1375. [DOI] [PubMed] [Google Scholar]
  • 27.Singh M, Nagrath AR, Maini PS. Changes in trabecular pattern of the upper end of the femur as an index of osteoporosis. J Bone Joint Surg Am. 1970;52:457-467. [PubMed] [Google Scholar]
  • 28.Slaven SE, Purcell RL, Mack AW, Bedard NA, Warth LC, Callaghan JJ. Results of porous-coated anatomic total hip arthroplasty without cement at 25 to 30 years: a concise follow-up of a previous report. J Bone Joint Surg Am. 2017;99:1647-1653. [DOI] [PubMed] [Google Scholar]
  • 29.Spotorno L, Romagnoli S, Ivaldo N, Grappiolo G, Bibbiani E, Blaha DJ, Guen TA. The CLS system. Theoretical concept and results. Acta Orthop Belg. 1993;59(Suppl 1):144-148. [PubMed] [Google Scholar]
  • 30.Statistisches Bundesamt. Statistisches Jahrbuch 2019. Available at: https://www.destatis.de/DE/Themen/Querschnitt/Jahrbuch/jb-bevoelkerung.pdf?__blob=publicationFile. Accessed November 29, 2019.
  • 31.Streit MR, Innmann MM, Merle C, Bruckner T, Aldinger PR, Gotterbarm T. Long-term (20- to 25-year) results of an uncemented tapered titanium femoral component and factors affecting survivorship. Clin Orthop Relat Res. 2013;471:3262-3269. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 32.Streit MR, Schroder K, Korber M, Merle C, Gotterbarm T, Ewerbeck V, Aldinger PR. High survival in young patients using a second generation uncemented total hip replacement. Int Orthop. 2012;36:1129-1136. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 33.Streit MR, Weiss S, Andreas F, Bruckner T, Walker T, Kretzer JP, Ewerbeck V, Merle C. 10-year results of the uncemented Allofit press-fit cup in young patients. Acta Orthop. 2014;85:368-374. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 34.World Medical Association. Declaration of Helsinki, Ethical Principles for Medical Research Involving Human Subjects. 2008. Available at: https://www.wma.net/wp-content/uploads/2018/07/DoH-Oct2008.pdf. Accessed November 29, 2019.

Articles from Clinical Orthopaedics and Related Research are provided here courtesy of The Association of Bone and Joint Surgeons

RESOURCES