Abstract
Aims
The aim of this study was to compare the functional and radiological outcomes in patients with a displaced fracture of the hip who were treated with a cemented or a cementless femoral stem.
Patients and Methods
A four-year follow-up of a randomized controlled study included 141 patients who underwent surgery for a displaced femoral neck fracture. Patients were randomized to receive either a cemented (n = 67) or a cementless (n = 74) stem at hemiarthroplasty (HA; n = 83) or total hip arthroplasty (THA; n = 58).
Results
Early differences in functional outcome, assessed using the Harris Hip Score, the Short Musculoskeletal Functional Assessment score and EuroQol-5D, with better results in cemented group, deteriorated over time and there were no statistically significant differences at 48 months. Two (3%) patients in the cemented group and five (6.8%) in the cementless group underwent further surgery for a periprosthetic fracture. This difference was statistically significant (p = 0.4). No patient underwent further surgery for instability or infection between one and four years postoperatively. The mortality and the radiological outcomes were similar in both groups.
Conclusion
Patients with a displaced femoral neck fracture treated with an arthroplasty using a cemented or cementless stem had good function and few complications up to four years postoperatively. However, due to the poor short-term functional outcomes in the cementless group, the findings do not support their routine use in the treatment of these elderly patients.
Cite this article: Bone Joint J 2018;100-B:1087–93.
A displaced femoral neck fracture in an elderly patient is a life-threatening injury. Primary operative treatment with an arthroplasty as soon as possible after the injury has proven satisfactory outcomes in several studies. Most patients regain good or acceptable function and pain relief, whether a hemiarthroplasty (HA) or a total hip arthroplasty (THA) is used.1-3 The risk of complications and mortality is, however, high.4,5 One risk factor for cardiopulmonary events is fat embolism from the femoral canal when using a cemented stem.6,7 This risk is reduced by using a cementless stem. A number of authors have compared cemented and cementless stems in these patients.8-15 In some, the stems performed similarly,8,10,12,15 whereas in others, cemented stems performed better in restoring function and pain relief with fewer complications in the short term.9,11,13,14,16-18 However, there is a higher incidence of periprosthetic fractures when using cementless stems.9,19,20 Although most studies support the use of a cemented stem, few have compared cemented and cementless stems beyond two years.
The aim of this study was to investigate the mid-term outcomes, including the need for further surgery, function, health-related quality of life (HRQoL), and radiological appearance in elderly patients with a femoral neck fracture treated with arthroplasty, comparing a cemented with a cementless stem.
Patients and Methods
Between October 2009 and April 2013, 964 patients with a displaced femoral neck fracture (Garden grade 3 or 4)21 were treated at the unit of Orthopaedics, Stockholm South General Hospital. Inclusion criteria for the study were: age ≥ 65 years old, living and moving independently (with or without walking aids) and without drug or alcohol abuse. The trauma also had to be low-energy and the patients had to be without severe cognitive dysfunction, thus able to give > three correct answers on the Short Portable Mental Status Questionnaire.22 Patients with symptomatic osteoarthritis, rheumatoid arthritis or trauma > 48 hours before admission were excluded. A total of 141 patients fulfilling these criteria gave written consent and were included. Randomization was performed using sealed envelopes. This was originally designed as two studies with a cutoff between the studies at the age of 80 years. Due to slow recruitment, the decision was made in November 2012 to pool all patients into one study. Patients aged between 65 and 79 years were allocated to a cemented or reversed hybrid THA, while patients aged > 80 years were allocated to a cemented or cementless unipolar HA.
All operations were performed by a group of 14 orthopaedic surgeons who were experienced in both techniques. A routine direct lateral approach was used with the patient in a lateral decubitus position.23 The components used in the cemented group were an Exeter stem (Stryker, Kalamazoo, Michigan) with a unipolar head in patients undergoing HA and a 32 mm head and a cross-linked polyethylene (XLPE) Marathon cup (DePuy Synthes, Warsaw, Indiana) in those undergoing THA. For the cementless group, a hydroxyapatite-coated Bimetric stem (Zimmer Biomet, Warsaw, Indiana) was used with a unipolar head for those undergoing HA and a 32 mm head and the same type of acetabular component as in the cemented group for those undergoing THA. Gentamicin-loaded Optipac (Zimmer. Biomet, Warsaw, Indiana) cement was used for all cemented components. Antibiotic prophylaxis involved three doses of intravenous Cloxacillin 2 g given between 30 and 60 minutes before surgery, and three and six hours after the first dose. Surgery was performed under spinal anaesthesia, if possible, and all patients received thromboembolic prophylaxis with low molecular heparin (4500 IU Tinzaparin) for 30 days with the first dose being given on the evening after the surgery.
Primary assessment
Preoperatively, self-administered questionnaires regarding living conditions, activities of daily living (ADL),24 health-related quality of life (EuroQol(EQ)-5D),25 and the Short Musculoskeletal Function Assessment questionnaire (SMFA)26 were completed with the help of a research nurse, to include information that the patients could recall for the week before the fracture. Patients were reviewed four, 12, 24 and 48 months postoperatively. The results from the four- and 12-month reviews have been published in this journal.11 At each review, a research nurse collected the EQ-5D and SMFA scores. An orthopaedic surgeon recorded the Harris Hip Score (HHS).27 Complications were recorded as described by the patients and from the medical records if a complication was treated at another hospital.
Radiographic outcome
An anteroposterior (AP) view of the pelvis and AP and lateral views of the hip were obtained before and after surgery, and at the time of the routine reviews. A radiologist (ZA) reviewed all the radiographs. The proximal femoral bone stock was classified according to Dorr (type A, B, or C).28 Heterotopic ossification (HO) was graded as described by Brooker et al,29 and acetabular erosion in the HA group was assessed as described by Baker et al.30 Significant radiological loosening of either the acetabular or femoral component was defined as a radiolucent zone of > 2 mm around the whole component.31 Significant subsidence of the stem was defined as > 5 mm.32
Statistical analysis
A power analysis was performed after pooling the two original studies. This indicated that 140 patients were needed at the 12-month review, assuming 10% mortality, to detect a five-point difference in HHS, with 80% power and a 5% level of significance. The intention-to-treat principle was used in the analysis. Analysis was performed using the IBM SPSS 22.0 software package for Macintosh (IBM Corp., Armonk, New York). Nominal variables were tested by chi-squared test or Fisher’s exact test. Ordinal variables and non-normality distributed interval and ratio scale variables were evaluated by the Mann–Whitney U test. The tests were two-sided and the results were considered significant at p < 0.05.
Ethical approval
The study was approved by the local ethics committee (2009/1188-3/1 and 2013/412-32) and was registered at www.clinicaltrials.gov (NCT 01798472).
Results
A total of 141 patients were included, and 67 patients were randomized to a cemented, and 74 to a cementless stem. At the final follow-up after four years, 86 patients were alive and willing to participate. The baseline data of the patients are shown in Table I and a flowchart of the study in Figure 1.
Fig. 1
Flowchart of all the patients. THA, total hip arthroplasty; HA, hemiarthroplasty; ORIF, open reduction and internal fixation.
Table I
Baseline data for all patients (n = 141) in relation to the type of stem used
| Cemented stem (n = 67) | Cementless stem (n = 74) | |
|---|---|---|
| Mean age, yrs (range) | 81.2 (65 to 96) | 81.3 (66 to 93) |
| Mean cognitive function, SPMSQ score (range) | 9.3 (5 to 10) | 9.0 (6 to 10) |
| Female gender, n (%) | 46 (69) | 53 (72) |
| ASA33 class 1 or 2, n (%) | 35 (52) | 32 (43) |
| Mobility: no walking aid or just one stick, n (%) | 56 (84) | 57 (77) |
| ADL n in Katz group A, n (%)* | 63 (94) | 66 (89) |
| Hemiarthroplasty, n (%) | 39 (58) | 44 (60) |
| Total hip arthroplasty, n (%) | 28 (42) | 30 (41) |
| At 24-mth follow-up | (n = 53) | (n = 53) |
| Age, mean (range) | 82.3 (68 to 99) | 82.8 (68 to 95) |
| Gender, female n (%) | 37 (49) | 38 (51) |
| At 48-mth follow-up | (n = 43) | (n = 43) |
| Age, mean (range) | 84.4 (69 to 99) | 83.6 (71 to 94) |
| Gender, female n (%) | 31 (49) | 32 (51) |
-
*Katz group A, totally independent in all activities of daily living
SPMSQ, Short Portable Mental Status Questionnaire; ASA, American Society of Anesthesiologists; ADL, activities of daily living
Mortality and adverse events
Since the review, 12 months postoperatively, 25 patients had died at 48 months. The mortality 24-months postoperatively was 13% (9/67) in the cemented group and 14% (10/74) in the cementless group (p = 1.0). The mortality 48 months postoperatively was 24% (16/67) in the cemented group and 28% (20/74) in the cementless group (p = 0.8). Seven patients, (two of 67 (3%) in the cemented group and five of 74 (6.8%) in the cementless group) underwent further surgery due to a periprosthetic fracture, between 12 and 48 months postoperatively (p = 0.4). One patient with a cemented HA underwent conversion to a THA after 12 months due to acetabular erosion. No patient required further surgery due to dislocation or infection after 12 months. Details on adverse events are shown in Table II.
Table II
Adverse events between 12 and 24 months follow-up.
| Adverse event | Cemented stem | Cementless stem |
|---|---|---|
| Reoperation due to periprosthetic fracture, n (%) | 2 (3.0) | 5 (6.8) |
| Revision to total hip arthroplasty, n (%) | 1/26 (3.8)* | 0 (0) |
| Trendelenburg limp, n (%) | 1 (1.5) | 3 (4.1) |
| Trochanteric pain, n (%) | 2 (3.0) | 0 (0) |
-
*Proportion calculated according to the 26 patients with cemented HA that were assessed at the 12-month follow-up
Functional outcome
Apart from a higher mean total HHS in the cemented group after four months and a higher mean HHS pain subscore at 24 months for the cemented group, the groups had similar HHS at all follow-ups. The mean SMFA scores in the cemented group were better for dysfunction and/or bother scores at the early follow-ups compared with the cementless group, but the scores deteriorated for the cemented group and at the final follow-up the scores were similar. The functional outcome scores are shown in Table III. HRQoL assessed by EQ-5D is shown in Figure 2. The results were statistically better in the cemented group for the first 24 months, but were similar in both groups thereafter (Fig. 2a). Additional results in the subgroups of patients who underwent a HA and THA are shown in Figs. 2b and 2c, respectively, and although there remained a visible difference between groups in the THA subgroup at 48 months, this difference was not statistically significant.
Figs. 2a - 2c
a) Graph showing the mean EuroQol-5D (EQ-5D) scores for all patients (a) those undergoing a hemiarthoplasty (b) and total hip arthroplasty (c). N/S, not significant.
Table III
Functional outcome by Harris Hip Score (HHS) and Short Musculoskeletal Function Assessment (SMFA) score
| Functional outcome | n | Cemented stem | Cementless stem | p-value* |
|---|---|---|---|---|
| Mean HHS score, total (sd) | ||||
| 4 mths | 127 | 78 (14) | 70.7 (14.6) | 0.004† |
| 12 mths | 123 | 82.3 (13.1) | 78.6 (17.1) | 0.09 |
| 24 mths | 104 | 76.7 (15.1) | 70.7 (19.1) | 0.06 |
| 48 mths | 84 | 76.8 (13.1) | 72.1 (19.8) | 0.49 |
| Mean HHS score, pain (sd) | ||||
| 4 mths | 127 | 39.6 (8.2) | 37.2 (9.1) | 0.07 |
| 12 mths | 123 | 40.7 (8.8) | 38.9 (9.0) | 0.10 |
| 24 mths | 106 | 39.4 (8.8) | 36.8 (9.4) | 0.04† |
| 48 mths | 86 | 40.8 (6.6) | 37.2 (10.1) | 0.07 |
| Mean SMFA score, dysfunction (sd) | ||||
| Preoperative | 138 | 17.9 (13.8) | 21.2 (14.3) | 0.14 |
| 4 mths | 125 | 29.8 (17.5) | 39.2 (19.6) | 0.007† |
| 12 mths | 118 | 22.3 (16.3) | 34.9 (22.2) | 0.001† |
| 24 mths | 102 | 26.4 (19.4) | 33.2 (21.8) | 0.12 |
| 48 mths | 82 | 32.4 (25.0) | 34.3 (24.3) | 0.63 |
| Mean SMFA score, bother (sd) | ||||
| Preoperative | 133 | 12.7 (14) | 12.5 (11.3) | 0.55 |
| 4 mths | 117 | 26.9 (19.4) | 32,2 (19.9) | 0.11 |
| 12 mths | 116 | 18.6 (16.8) | 29 (21.1) | 0.007† |
| 24 mths | 102 | 18.7(16.0) | 28.3 (21.3) | 0.027† |
| 48 mths | 81 | 25.2 (22.6) | 28.1(22.0) | 0.57 |
-
*Student’s t-test
†Statistically significant
Radiological assessment
Subsidence of the stem by > 5 mm was seen in 8.5% (4/47) of the cemented group and in 6.4% (3/47) of the cementless group at the 24-month follow-up (p = 0.7); and in 14% (5/37) of the cemented group and 8.3% (3/36) of the cementless group at 48 months (p = 0.5). No component showed signs of loosening at any time. The frequency of HO formation and acetabular erosion were similar in the two groups (Table IV).
Table IV
Radiological assessment; the data are presented as the numbers according to available radiographs at the different follow-ups
| Assessment | Cemented stem | Cementless stem |
|---|---|---|
| Brooker, 24 mths* | ||
| None | 9/48 | 8/46 |
| Islands | 19/48 | 21/46 |
| Spurrs > 1 cm apart | 15/48 | 13/46 |
| Spurrs < 1 cm apart | 4/48 | 3/46 |
| Ankylosis | 1/48 | 1/46 |
| Brooker, 48 mths* | ||
| None | 6/37 | 8/37 |
| Islands | 15/37 | 16/37 |
| Spurrs > 1 cm apart | 13/37 | 12/37 |
| Spurrs < 1 cm apart | 3/37 | 1/37 |
| Baker, 24 mths† | ||
| None | 15/24 | 15/23 |
| Joint space narrowing | 9/24 | 8/23 |
| Joint space disappeared | 1/24 | 0/23 |
| Baker, 48 mths† | ||
| None | 10/17 | 10/17 |
| Joint space narrowing | 6/17 | 6/17 |
| Joint space disappeared | 0/17 | 1/17 |
| Protrusio | 1/17 | 0/17 |
-
*For all arthroplasty types
†For hemiarthroplasty patients only
Discussion
The main finding in this study was that the differences in function one year postoperatively in patients with a fracture of the hip treated with a cemented or cementless stem disappeared with the passage of time. Good functional outcomes followed the use of both forms of fixation, two years postoperatively, with few adverse events and similar mortality. The function, assessed by the HHS, peaked 12 months postoperatively and subsequently decreased although the pain subscore remained similar in both groups. This finding differs from that of Langslet et al,18 who reported better HHSs after five years for patients with a cementless stem. The mean HHS in our patients was similar to theirs at one and four years postoperatively for the cemented group, but there was a large difference for the cementless group. However, in their series, less than 50% of the patients who were available one year postoperatively were available five years postoperatively. Only 34% of the patients remained in the cementless group, compared with 58% in our series. We noted a trend of decreasing HRQoL, EQ-5D and an increasingly impaired SMFA in the cemented group over time. We interpret this as reflecting older age and decreasing general health rather than an effect of the different methods of fixation of the stem. It could also be an effect of the mixed population of patients undergoing THA and HA, as the decrease in the EQ-5D seemed to be more pronounced in the cemented HA subgroup.
We noted five postoperative periprosthetic fractures, two in the cemented group (3%) and five in the cementless group (6.8%) between one and four years postoperatively. This difference was not statistically significant (p = 0.4). In a randomized trial comparing 112 cemented bipolar arthroplasties with 108 cementless bipolar arthroplasties, Langslet et al18 found 7.4% periprosthetic fractures in the cementless group, compared with 1% in the cemented group after five years. However, only three out of the eight fractures in the cementless group occurred after the one-year follow-up. Sköldenberg et al34 reported six (12%) fractures, all after two years, in a series of patients with a fracture of the femoral neck treated with a cementless THA.
In summary, few patients in these studies have follow-up of up to five years and the differences in frequency of periprosthetic fractures between the types of fixation after 4 years could be explained by chance. It seems reasonable to assume that the long-term risk of a periprosthetic fracture in these patients will be more affected by the risk of falling again rather than by the type of fixation of the stem. The long-term risk of developing a complication with a cementless stem might be acceptable but combined with the risk of an early complication the picture is different. There was a higher frequency of intraoperative complications in the cementless group in the initial report of this study,11 leading to a higher total risk of a complication for patients treated in this way. This reasoning is in line with the current literature. In a recent meta-analysis, Veldman et al35 reported that the risk of a complication was a factor favouring the use of a cemented stem. Chammut et al9 stopped their randomized controlled trial due to a high rate of early complications in the cementless group, and Rogmark et al14 found a hazard ratio for reoperation of 3.6 due to periprosthetic fracture after the use of a cementless compared with a cemented stem in their register study.
Few patients with either form of fixation require further surgery up to four years postoperatively. In the early report of this study, one patient underwent surgery due to instability and one due to infection, during the first postoperative year.11 No patient has subsequently required further surgery for these indications. The mortality in this study was similar to other studies.9,17,18,36 The size of the study makes further analyses of mortality uncertain, but there seemed to be no differences between the groups. There are reports from large cohorts that a higher mortality one day postoperatively follows the use of a cemented stem. Costain et al37 found a statistically significant difference, with a mortality one day postoperatively of 0.5% in a cementless group and 0.8% in a cemented group (p < 0.001). The risk of death was, however, reversed after one week and remained higher in the cementless group, with mortality of 21% after one year in the cemented group and 30% in the cementless group (p < 0.001). Our interpretation of these findings is that the risk of cement syndrome leading to an increased risk of death is not a valid argument for choosing a cementless stem, the 0.3% lower risk the first day is not comparable with the higher mortality from one week adding up to 9% higher mortality after 1 year in the cementless stem group.
The main strengths of the study are the relatively long follow-up and the well-structured study protocol. The study, however, has limitations. The power analysis was performed to compare the one-year results and the conclusions are weakened by the subsequent loss to follow-up and selection bias in relation to the patients that were available at the final follow-up. Some of the patients who were alive and declined to take part did so because of comorbidities which were not related to the fracture, such as dementia or general health issues due to age. The study was originally designed as two separate studies and the mixed cohort of patients undergoing THA and HA could be a confounding factor, especially regarding function and HRQoL. However, the stems used were the same, and the same method of randomization was used for the THA and HA groups. The proportion of patients treated with THA and HA in the groups remained similar over time. We deem the effect from the mixed groups to have a very minor impact on the results of the stems because there were similar amounts of drop outs in all groups.
In conclusion, we confirmed that patients with a displaced femoral neck fracture treated with an arthroplasty using a cemented or a cementless stem had good function and few complications up to four years postoperatively. However, due to the poor short-term functional results in the cementless group, the findings do not support their routine use in the treatment of these elderly patients.
Take home message:
-This randomized controlled trial reports similar results four years after a displaced femoral neck fracture treated with a cemented or cementless arthroplasty, but due to the earlier published one year results with higher complication frequencies in the cementless stem group, the cemented stem solution is deemed a safer choice for this patient group.
- The clinical relevance of the study is that orthopaedic surgeons treating patients with displaced femoral neck fractures should be aware of the early complications in their treatment choice because the long-term results for the survivors are good regardless of fixation.
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Author contributions:
B. Barenius: Designing and planning the study, Collecting and analyzing the data, Writing the manuscript.
C. Inngul: Designing and planning the study, Collecting and analyzing the data, Writing the manuscript.
Z. Alagic: Designing and planning the study, Analyzing the radiographs. Writing the manuscript.
A. Enocson: Designing and planning the study, Collecting and analyzing the data, Writing the manuscript.
Funding statement:
No benefits in any form have been received or will be received from a commercial party related directly or indirectly to the subject of this article.
Acknowledgements:
The authors wish to thank Sari Ponzer and Richard Blomfeldt, both at Department of Orthopaedics and Clinical Science and Education, Karolinska Institute, Stockholm South Hospital, Stockholm, Sweden, for their valuable contribution to the study.
To make this study possible the authors also would like to acknowledge the work by the research nurses Catharina Levander and Elisabeth Skogman, and the study surgeons Buster Sandgren, Radford Ekholm, Carl-Johan Hedbeck, Per Hamberg, Rickard Miedel, Ulla Lind, Karl Eriksson, Lasse Lapidus, Anders Norrman, Richard Blomfeldt, Uffe Hylin, Christian Inngul, Anders Enocson and Hasse Törnkvist.
This article was primary edited by J. Scott.
