Secondary Logo

Journal Logo

Advanced Search
Clinical Research

Randomized Trial of Hemiarthroplasty versus Internal Fixation for Femoral Neck Fractures: No Differences at 6 Years

Støen, Ragnhild Øydna MD1, 2, 3, a; Lofthus, Cathrine M. MD, PhD4; Nordsletten, Lars MD, PhD1, 2; Madsen, Jan Erik MD, PhD1, 2; Frihagen, Frede MD, PhD1, 2, 3

Author Information

1 Department of Orthopaedic Surgery, Oslo University Hospital, Oslo, Norway

2 University of Oslo, Oslo, Norway

3 Department of Orthopaedics, Ringerike Hospital, Vestre Viken Hospital Trust, 3500, Hønefoss, Norway

4 Department of Endocrinology, Oslo University Hospital, Oslo, Norway

a e-mail; [email protected]

Received: January 28, 2013 / Accepted: August 12, 2013 / Published online: August 24, 2013

Funding was provided by the South-Eastern Norway Regional Health Authority.

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 prior to clinical use.

Each author certifies that his or her institution approved the human protocol for this investigation, that all investigations were conducted in conformity with ethical principles of research, and that informed consent for participation in the study was obtained.

Data collection was performed at Oslo University Hospital, Ullevål, Norway.

A comment to this article is available at http://dx.doi.org/10.1007/s11999-013-3296-9.

Clinical Orthopaedics and Related Research: January 2014 - Volume 472 - Issue 1 - p 360-367
doi: 10.1007/s11999-013-3245-7
  • Free

Abstract

Introduction

Among orthopaedic injuries, none accounts for more morbidity, mortality, and healthcare costs than hip fracture [3, 25, 35]. Cooper et al. [6] have estimated that as a result of an increasing proportion of elderly people in the world, the number of hip fractures will approximate four million in 2025. A hip fracture changes the patient’s life; 20% to 25% of patients die after 1 year [10], 40% are still unable to walk independently, 60% have difficulty with at least one essential activity of daily living, and 80% are restricted in other activities such as grocery shopping or driving [5]. Hip fractures are classified as either intracapsular femoral neck fractures or extracapsular fractures, which are either trochanteric or subtrochanteric fractures. Femoral neck fractures constitute approximately half of all hip fractures [36].

Treatment of displaced intracapsular femoral neck fractures has been controversial since the early 20th century [12, 18], although increasing evidence has been presented supporting arthroplasty as superior to internal fixation in these fractures [17, 27]. Data from followup longer than 1 or 2 years are sparse, however. Studies with bipolar hemiarthroplasty indicate that acetabular wear is less of a problem than previously thought [8, 31]. Several reports show, however, high rates of pain, migration, and the need for revision to THA in middle- and long-term followup [24, 38].

We sought to compare hemiarthroplasty with internal fixation in terms of (1) outcome scores for pain, hip function, and quality of life at a minimum of 5 years after surgery in a randomized trial. A secondary purpose was to compare (2) patient survival and (3) frequency of reoperation between the two groups.

Patients and Methods

A total of 222 consecutive patients from September 2002 to March 2004 were included in the study (Fig. 1). Results up to 2 years have been published previously [10]. The resident on call included patients when they presented in the emergency department at Ullevål University Hospital (now Oslo University Hospital), Oslo, Norway, with a displaced intracapsular femoral neck fracture judged by angular displacement in either radiographic plane. The patients were not eligible for inclusion if they were not ambulant before the fracture, were unfit for arthroplasty according to the anesthesiologist, had previous symptomatic hip pathology, had a pathological fracture, if there was delay of more than 96 hours from injury to treatment, or if they lived outside the hospital’s area.

F1-52
Fig. 1:
Flowchart is shown of included patients in the study, their survival, and randomization group. IF = internal fixation; HA = hemiarthroplasty.

The randomization was performed by placing 115 notes with the word “hemi” and 115 notes with the word “screws” in opaque envelopes, which were sealed and mixed before numbering. After inclusion, the resident on call opened the envelope with the lowest number in the emergency department. At the end of inclusion, there were eight remaining envelopes that were collected. All envelopes for randomization were accounted for at the end of the study.

During the inclusion period, 445 consecutive patients with femoral neck fracture presented to the department. Of them, 185 did not meet the inclusion criteria and 38 were not included, mainly because of refusal of consent (n = 31). The 222 included patients were randomized to internal fixation (n = 112) or hemiarthroplasty (n = 110). In the internal fixation group, 102 were treated according to the protocol, nine with hemiarthroplasty because of irreducible fracture (n = 8) or poor screw purchase (n = 1), and one died before surgery. In the hemiarthroplasty group, 105 patients were treated according to the protocol, three were operated on with internal fixation, one with a sliding hip plate because of a new ipsilateral fracture before surgery, and one patient died before surgery.

Of the 222 patients included in the study, 70 patients were alive and 68 patients continued participation in the study after a minimum of 5 years, of whom 37 were in the hemiarthroplasty group and 31 were in the internal fixation group (Fig. 1). The 68 patients (52 females, 16 males) were examined after 5 to 7 years (mean, 71 months; range, 59-86 months). The patients who did not come to the outpatient clinic were visited at their place of residence (n = 26 [39%]) or contacted by phone (n = 1). More than half of the patients lived independently (n = 38 [56%]) (Table 1).

T1-52
Table 1:
Characteristics of all included patients and patients followed at 5 to 7 years (all data for both groups at baseline)

Intervention

Surgery was performed by the doctors on call. For hemiarthroplasty, a cemented Charnley-Hastings bipolar hemiprosthesis (DePuy/Johnson and Johnson, Leeds, UK) was used through a direct lateral approach. Internal fixation was performed with two parallel cannulated screws (Olmed; DePuy/Johnson and Johnson, Uppsala, Sweden) after closed reduction. Both procedures were routine operations in the department before the study started. Spinal anesthesia was preferred in both groups. The hemiarthroplasty group was intravenously given 2 g cephalotin preoperatively with another three doses the first 24 hours after surgery. Both groups received 5000 IE low-molecular-weight heparin subcutaneously daily until they were well mobilized. Early mobilization with full weightbearing was encouraged regardless of treatment group.

Followup

Patients were seen in the outpatient clinic after 4, 12, and 24 months and at a mean of 6 years (range, 5-7 years). At inclusion, the surgeon filled in data on retrospective prefracture Harris hip score (HHS) as well as ability to walk independently, place of residence, and comorbidity, including dementia. At later visits, these data were also recorded.

At every scheduled visit, hip function, activities of daily living, and quality of life were assessed with questionnaires [11]. The patients were asked to fill in the Eq5D questionnaire, a patient-reported measure of health-related quality of life [7, 37]. The Barthel Activities of Daily Living (ADL) questionnaire [23] was filled out by a study nurse blinded to the initial treatment. The Barthel ADL index score was split into good function (score 95 or 100) and reduced function (score below 95) for the analysis.

HHS [15] was examined by a study physiotherapist blinded to the initial treatment. The last part of the HHS (ROM) was not filled in as a result of difficulties with precise assessment. The maximum HHS was therefore 95 in this study. The patients were asked not to inform the nurse and physiotherapist about their treatment and kept their clothes on to obtain a blinded examination. A chart review was performed of all originally included patients before the last followup to record reoperations or other problems. Radiographs were obtained of all patients who visited the outpatient clinic. In addition, some of the patients had films obtained where they lived by a mobile xray unit. The films were analyzed by two of the authors (FF, RØS) together and consensus was reached on any new findings.

Statistics

All analyses were conducted with IBM® SPSS® Statistics Version 19 (SPSS Inc, Chicago, IL, USA). All comparisons were made according to randomization group as defined by the intention-to-treat principle. The Mann-Whitney U test was used for comparison between groups and median and 95% confidence intervals for median were used unless otherwise stated. The t-test was used for comparison of mean values and Pearson chi-square was used for comparison of the dichotomous variable Barthel index score ≥ 95% and mortality.

Ethics

The study was approved by the Regional Committee for Medical and Health Research Ethics Committee. All patients who were able signed an informed consent. Patients with permanent or temporary cognitive impairment were included after acceptance from their family.

Results

The registered data on hip function, ADL, or quality of life showed no difference between the randomization groups. Per-protocol analyses did not change this. The participants after 5 to 7 years were younger at inclusion than the initial patient group, more of them lived independently, less had diagnosed dementia, and more walked without any aid. The distribution between the sexes was, however, unchanged (Table 2).

T2-52
Table 2:
Hip function, activities of daily living, and quality of life in patients randomized to internal fixation compared with hemiarthroplasty

There was no difference in patient survival between the groups with 33.6% (37 of 110) of the patients undergoing hemiarthroplasty and 29.5% (33 of 112) of the patients undergoing internal fixation still alive after a mean of 6 years (p = 0.51) (Fig. 2).

F2-52
Fig. 2:
Survival of patients (Kaplan-Meier) up to 6 years for hemiarthroplasty and internal fixation groups is shown.

Of patients alive after 5 to 7 years, only 39 % (12 of 31) in the group randomized to internal fixation had their native hips, whereas 95% (35 of 37) patients initially receiving hemiarthroplasty still had the hemiarthroplasty (p < 0.001). The total percentage of reoperations for all patients originally included in the study was 43% (48 of 112) in the internal fixation group and 10% (11 of 110) in the hemiarthroplasty group (p < 0.001) after 5 to 7 years. From 2 to 6 years, two patients, both in the internal fixation group, were reoperated on, none in the hemiarthroplasty group (Fig. 3). One had a deep infection around the screws and was revised several times and the screws removed; the other had avascular necrosis and received THA. The chart review revealed no new surgical complications or reoperations in the patients who died between the followup at 24 months and the last followup. Radiographs were obtained of 56 of the patients. Changes from previous films were seen in three patients, one avascular necrosis of the femoral head, one loosening of the femoral stem (fractured cement and movement of the stem), and one acetabular wear (obliterated medial joint space). These patients were clinically doing well and no revision surgeries were planned.

F3-52
Fig. 3:
Kaplan-Meier plot is shown of patients without any reoperation up to 6 years for hemiarthroplasty and internal fixation groups.

Discussion

As the population is getting older, the number of hip fractures will increase all over the world. Hip fracture leads to morbidity, mortality, and healthcare costs. Femoral neck fractures are treated with hemiarthroplasty or internal fixation; each of these treatments has different complications. Internal fixation has a high reoperation rate the first year after surgery compared with hemiarthroplasty [27], but concerns have been raised that hemiarthroplasty will lead to long-term complications because of loosening and acetabular wear [21]. Our study demonstrates that patient survival, hip function, quality of life, and ADL were similar at a mean 6 years after fracture regardless of randomization group. Reoperations were, however, more frequent in the internal fixation group. The short life expectancy in this group of patients was again demonstrated [14].

The present study has several limitations, among which lack of power resulting from the high mortality rate is the most important. The very low number of patients lost to followup is, however, an important advantage of this study compared with other studies comparing internal fixation and hemiarthroplasty. Furthermore, the unselected patient material and inclusion of demented patients make the results valid for the entire population of patients with displaced femoral neck fractures.

The present study was not statistically powered to detect differences in functional outcomes after a mean of 6 years. Thus, the present results do not necessarily imply that the outcomes are equal. The results of the predefined main end point of the study, HHS, was, however, very similar after 6 years. A chart review was performed for all originally included patients, and no new reoperations or complications were discovered. Some patients may, however, have been reoperated on elsewhere, although the organization of the healthcare system in Oslo is that each hospital is responsible for a defined part of the city population, so this number is probably low. The concern that the treatment with hemiarthroplasty for femoral neck fractures leads to long-term problems such as acetabular wear and loosening with corresponding pain, loss of function, and the need for revision surgeries could not be verified in the present work at intermediate-term followup. Leonardsson et al. [22] published in 2010 similar results with no differences in functional outcome but a higher reoperation rate in the group of hemiarthroplasty. A study by Parker et al. [30] did not show any differences in clinical outcomes either.

The Kaplan-Meier curves did not identify any differences in the two groups in patient survival either early on or in the present report at a minimum followup of 5 years. This has also been documented in registry studies [13]. Hemiarthroplasty may represent a heavier surgical burden for the patient compared with internal fixation, which may lead to increased early mortality. If there is a difference in mortality between the methods, it would be an important factor in decision-making, even when including the functional benefits of treatment with hemiarthroplasty. No randomized study has reported a higher mortality rate after hemiarthroplasty [2, 28], and it would require a very large study to conclude on this matter; Bhandari et al. [2] estimated that demonstrating a 5% increased mortality rate would require a study sample size of 26,641 patients. Regarding mortality in this patient group overall, it is high the first year after fracture [20]. Later on, however, the mortality rate approaches the mortality rate of persons of the same age and sex [9], which makes it important to differentiate the treatment between patients with short and long life expectancies.

Hemiarthroplasty has in later years been established as the treatment of choice for displaced femoral neck fractures [30, 34]. However, hemiarthroplasty has also been shown to have an unacceptably high risk of pain and revision compared with THA when used to treat degenerative osteoarthritis or osteonecrosis of the femoral neck [19, 27, 32]. This has led to a concern that the long-term survivors after hip fracture may experience late problems with their hemiarthroplasty. The present study gave no indication that this is true. On the contrary, only patients in the internal fixation group were reoperated on between 2 and 6 years. This is similar to results reported by Leonardsson et al. [22], in which 89 patients randomized to hemiarthroplasty had no reoperations between 2 and 10 years. Hemiarthroplasty may thus provide adequate function for this patient group. One study has even shown that hemiarthroplasty has better results than THA in this unsorted total patient population with hip fracture, mainly because of problems with hip prosthesis dislocation in fragile patients with THA [39].

Despite hemiarthroplasty being the treatment of choice in an unsorted population, the healthiest patients with long life expectancy might have a better result with THA [1]. This is the conclusion in a Cochrane review in which THA in a majority of relatively young and healthy patients had significantly less residual pain and better function at 1, 2, and 4 years after fracture at the cost of increased risk of dislocation and increased surgical time [28], also shown by Hedbeck et al. [16]. A cost-effectiveness analysis concluded that it is likely that THA is associated with increased costs in the initial 2-year period, but the longer-term costs favor THA as a result of lower revision rates [4]. Regarding cost of hemiarthroplasty versus internal fixation, hemiarthroplasty has been reported to be favorable [40].

As expected, there were demographic differences between patients who died within the first 6 years after fracture and the one-third who still were alive after 6 years. The patients who died were older at inclusion, more of them were cognitively impaired, and fewer lived home at inclusion [26].

The overall short life expectancy and the superior short-term function in the hemiarthroplasty group reinforce bipolar hemiarthroplasty as the treatment of choice in elderly patients with a displaced intracapsular hip fracture [10, 13, 29, 33]. The excess mortality compared with the background population is well demonstrated for the first year after fracture [20]. One-third of the patients are dead after 2 years, and they have been demonstrated to do best with hemiarthroplasty compared with both internal fixation and THA [39]. However, there is a small patient group that will live for 5 years or more; approximately 31% were still alive at that time point in the present report, and it is important to consider this group as decisions are made about treatment approaches. Further studies should focus on the subgroup of the relatively youngest and fittest patients with displaced femoral neck fractures to elucidate whether internal fixation, hemiarthroplasty, or THA might be the preferred treatment for them.

Acknowledgments

We thank study nurse Kenneth Nilsen and physiotherapists Åsa Axelsson and Marte T. Magnusson who participated in the collection of data.

References

1. Baker, RP., Squires, B., Gargan, MF. and Bannister, GC. Total hip arthroplasty and hemiarthroplasty in mobile, independent patients with a displaced intracapsular fracture of the femoral neck. A randomized, controlled trial. J Bone Joint Surg Am. 2006; 88: 2583-2589. 10.2106/JBJS.E.01373
2. Bhandari, M., Devereaux, PJ., Swiontkowski, MF., Tornetta, P, III, Obremskey, W., Koval, KJ., Nork, S., Sprague, S., Schemitsch, EH. and Guyatt, GH. Internal fixation compared with arthroplasty for displaced fractures of the femoral neck. A meta-analysis. J Bone Joint Surg Am. 2003; 85: 1673-1681.
3. Burge, R., Dawson-Hughes, B., Solomon, DH., Wong, JB., King, A. and Tosteson, A. Incidence and economic burden of osteoporosis-related fractures in the United States, 2005-2025. J Bone Miner Res. 2007; 22: 465-475. 10.1359/jbmr.061113
4. Carroll, C., Stevenson, M., Scope, A., Evans, P. and Buckley, S. Hemiarthroplasty and total hip arthroplasty for treating primary intracapsular fracture of the hip: a systematic review and cost-effectiveness analysis. Health Technol Assess. 2011; 15: 1-74.
5. Cooper, C. The crippling consequences of fractures and their impact on quality of life. Am J Med. 1997; 103: 12S-17S. 10.1016/S0002-9343(97)90022-X
6. Cooper, C., Campion, G. and Melton, LJ, III, Hip fractures in the elderly: a world-wide projection. Osteoporos Int. 1992; 2: 285-289. 10.1007/BF01623184
7. EurQol. EuroQol—a new facility for the measurement of health-related quality of life. The EuroQol Group. Health Policy. 1990;16:199-208.
8. Figved, W., Dahl, J., Snorrason, F., Frihagen, F., Rohrl, S., Madsen, JE. and Nordsletten, L. Radiostereometric analysis of hemiarthroplasties of the hip—a highly precise method for measurements of cartilage wear. Osteoarthritis Cartilage. 2012; 20: 36-42. 10.1016/j.joca.2011.11.006
9. Finnes, TE., Meyer, HE., Falch, JA., Medhus, AW., Wentzel-Larsen, T. and Lofthus, CM. Secular reduction of excess mortality in hip fracture patients >85 years. BMC Geriatr. 2013;13:25. 3610125. 10.1186/1471-2318-13-25.
10. Frihagen, F., Grotle, M., Madsen, JE., Wyller, TB., Mowinckel, P. and Nordsletten, L. Outcome after femoral neck fractures: a comparison of Harris Hip Score, Eq-5D and Barthel Index. Injury. 2008; 39: 1147-1156. 10.1016/j.injury.2008.03.027
11. Frihagen, F., Nordsletten, L. and Madsen, JE. Hemiarthroplasty or internal fixation for intracapsular displaced femoral neck fractures: randomised controlled trial. BMJ. 2007;335:1251-1254. 2137068. 10.1136/bmj.39399.456551.25.
12. Garden, RS. Low angle fixation in fractures of the femoral neck. J Bone Joint Surg Br. 1961; 43: 647-663.
13. Gjertsen, JE., Vinje, T., Engesaeter, LB., Lie, SA., Havelin, LI., Furnes, O. and Fevang, JM. Internal screw fixation compared with bipolar hemiarthroplasty for treatment of displaced femoral neck fractures in elderly patients. J Bone Joint Surg Am. 2010; 92: 619-628. 10.2106/JBJS.H.01750
14. Haentjens, P., Magaziner, J., Colon-Emeric, CS., Vanderschueren, D., Milisen, K., Velkeniers, B. and Boonen, S. Meta-analysis: excess mortality after hip fracture among older women and men. Ann Intern Med. 2010;152:380-390. 3010729. 10.7326/0003-4819-152-6-201003160-00008.
15. 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.
16. Hedbeck, CJ., Enocson, A., Lapidus, G., Blomfeldt, R., Tornkvist, H., Ponzer, S. and Tidermark, J. Comparison of bipolar hemiarthroplasty with total hip arthroplasty for displaced femoral neck fractures: a concise four-year follow-up of a randomized trial. J Bone Joint Surg Am. 2011; 93: 445-450.
17. Heetveld, MJ., Rogmark, C., Frihagen, F. and Keating, J. Internal fixation versus arthroplasty for displaced femoral neck fractures: what is the evidence? J Orthop Trauma. 2009; 23: 395-402. 10.1097/BOT.0b013e318176147d
18. Hinchey, JJ. and Day, PL. Primary prosthetic replacement in fresh femoral neck fractures. A review of 294 cpnsecutive cases. J Bone Joint Surg Am. 1964; 46: 223-240.
19. Hwang, KT., Kim, YH., Kim, YS. and Choi, IY. Is bipolar hemiarthroplasty a reliable option for Ficat stage III osteonecrosis of the femoral head? 15- to 24-year follow-up study. Arch Orthop Trauma Surg. 2012; 132: 1789-1796. 10.1007/s00402-012-1613-5
20. Kanis, JA., Oden, A., Johnell, O., DeLaet, C., Jonsson, B. and Oglesby, AK. The components of excess mortality after hip fracture. Bone. 2003; 32: 468-473. 10.1016/S8756-3282(03)00061-9
21. Kim, YS., Kim, YH., Hwang, KT. and Choi, IY. The cartilage degeneration and joint motion of bipolar hemiarthroplasty. Int Orthop. 2012;36:2015-2020. 3460100. 10.1007/s00264-012-1567-9.
22. Leonardsson, O., Sernbo, I., Carlsson, A., Akesson, K. and Rogmark, C. Long-term follow-up of replacement compared with internal fixation for displaced femoral neck fractures: results at ten years in a randomised study of 450 patients. J Bone Joint Surg Br. 2010; 92: 406-412. 10.1302/0301-620X.92B3.23036
23. Mahoney, FI. and Barthel, DW. Functional evaluation: the Barthel Index. Md State Med J. 1965; 14: 61-65.
24. Muraki, M., Sudo, A., Hasegawa, M., Fukuda, A. and Uchida, A. Long-term results of bipolar hemiarthroplasty for osteoarthritis of the hip and idiopathic osteonecrosis of the femoral head. J Orthop Sci. 2008; 13: 313-317. 10.1007/s00776-008-1238-2
25. Osnes, EK., Lofthus, CM., Meyer, HE., Falch, JA., Nordsletten, L., Cappelen, I. and Kristiansen, IS. Consequences of hip fracture on activities of daily life and residential needs. Osteoporos Int. 2004; 15: 567-574.
26. Panula, J., Pihlajamaki, H., Mattila, VM., Jaatinen, P., Vahlberg, T., Aarnio, P. and Kivela, SL. Mortality and cause of death in hip fracture patients aged 65 or older: a population-based study. BMC Musculoskelet Disord. 2011;12:105. 3118151. 10.1186/1471-2474-12-105.
27. Parker, MJ. and Gurusamy, K. Internal fixation versus arthroplasty for intracapsular proximal femoral fractures in adults. Cochrane Database Syst Rev. 2006; 4: CD001708.
28. Parker, MJ., Gurusamy, KS. and Azegami, S. Arthroplasties (with and without bone cement) for proximal femoral fractures in adults. Cochrane Database Syst Rev. 2010; 6: CD001706.
29. Parker, MJ., Khan, RJ., Crawford, J. and Pryor, GA. Hemiarthroplasty versus internal fixation for displaced intracapsular hip fractures in the elderly. A randomised trial of 455 patients. J Bone Joint Surg Br. 2002; 84: 1150-1155. 10.1302/0301-620X.84B8.13522
30. Parker, MJ., Pryor, G. and Gurusamy, K. Hemiarthroplasty versus internal fixation for displaced intracapsular hip fractures: a long-term follow-up of a randomised trial. Injury. 2010; 41: 370-373. 10.1016/j.injury.2009.10.003
31. Pawaskar, SS., Ingham, E., Fisher, J. and Jin, Z. Fluid load support and contact mechanics of hemiarthroplasty in the natural hip joint. Med Eng Phys. 2011; 33: 96-105. 10.1016/j.medengphy.2010.09.009
32. Pellegrini, VD, Jr, Heiges, BA., Bixler, B., Lehman, EB. and Davis, CM, III, Minimum ten-year results of primary bipolar hip arthroplasty for degenerative arthritis of the hip. J Bone Joint Surg Am. 2006; 88: 1817-1825. 10.2106/JBJS.01879.pp
33. Rogmark, C., Carlsson, A., Johnell, O. and Sernbo, I. A prospective randomised trial of internal fixation versus arthroplasty for displaced fractures of the neck of the femur. Functional outcome for 450 patients at two years. J Bone Joint Surg Br. 2002; 84: 183-188. 10.1302/0301-620X.84B2.11923
34. Rogmark, C. and Johnell, O. Primary arthroplasty is better than internal fixation of displaced femoral neck fractures: a meta-analysis of 14 randomized studies with 2,289 patients. Acta Orthop. 2006; 77: 359-367. 10.1080/17453670610046262
35. Shi, N., Foley, K., Lenhart, G. and Badamgarav, E. Direct healthcare costs of hip, vertebral, and non-hip, non-vertebral fractures. Bone. 2009; 45: 1084-1090. 10.1016/j.bone.2009.07.086
36. Stoen, RO., Nordsletten, L., Meyer, HE., Frihagen, JF., Falch, JS. and Lofthus, CM. Hip fracture incidence is decreasing in the high incidence area of Oslo. Norway. Osteoporos Int. 2012; 23: 2527-2534. 10.1007/s00198-011-1888-3
37. Tidermark, J., Bergstrom, G., Svensson, O., Tornkvist, H. and Ponzer, S. Responsiveness of the EuroQol (EQ 5-D) and the SF-36 in elderly patients with displaced femoral neck fractures. Qual Life Res. 2003; 12: 1069-1079. 10.1023/A:1026193812514
38. Tsumura, H., Torisu, T., Kaku, N. and Higashi, T. Five- to fifteen-year clinical results and the radiographic evaluation of acetabular changes after bipolar hip arthroplasty for femoral head osteonecrosis. J Arthroplasty. 2005; 20: 892-897. 10.1016/j.arth.2004.11.010
39. Bekerom, MP., Hilverdink, EF., Sierevelt, IN., Reuling, EM., Schnater, JM., Bonke, H., Goslings, JC., Dijk, CN. and Raaymakers, EL. A comparison of hemiarthroplasty with total hip replacement for displaced intracapsular fracture of the femoral neck: a randomised controlled multicentre trial in patients aged 70 years and over. J Bone Joint Surg Br. 2010; 92: 1422-1428. 10.1302/0301-620X.92B10.24899
40. Waaler Bjornelv, GM., Frihagen, F., Madsen, JE., Nordsletten, L. and Aas, E. Hemiarthroplasty compared to internal fixation with percutaneous cannulated screws as treatment of displaced femoral neck fractures in the elderly: cost-utility analysis performed alongside a randomized, controlled trial. Osteoporos Int. 2012; 23: 1711-1719. 10.1007/s00198-011-1772-1
© 2014 Lippincott Williams & Wilkins LWW