fractures, luxation of hip arthroplasties and pelvic fractures, pressure sores and .... Hiift-Fraktur-Bandage zur Verhinderung von Oberschenkelhals- briichen bei ...
25 Hip Protectors J. B. Lauritzen and W. C. Hayes
Introduction Hip protectors used in prevention of hip fractures have been available in clinical practice for only a few years. Based on several recent clinical and biomechanical studies hip protection has been recommended by the European Commission in their 'Report on Osteoporosis in the European Community - Action for Prevention 1998': "Any bone will break if the force is strong enough, but reducing the impact of the force may prevent fracture. Hip protectors have been developed to reduce the impact of trauma and protect the bone when a fall occurs from a standing position. Studies have demonstrated the protective value of protectors worn by vulnerable older women and men who have already sustained a fracture, particularly those in nursing homes." The following conditions have been considered important for a fall to cause hip fracture, impact near the hip, protective reflexes, local soft tissue energy absorption and bone strength [1]. More than 90% of hip fractures are related to direct impact on the hip [1-3], although only one-fourth of impacts to the hip in the elderly lead to a hip fracture [4]. Rarely does a hip fracture occur without direct trauma [5-7]. Moreover, falls directly on the hip raises the odds ratio for a hip fracture about 20-fold [8].
Occurrence of falls and hip fracture For people living in the community the annual rate of falls is 28-35% among those older than 65 years of age [9-11], and 32-42% of subjects older than 75 years sustain at least one fall a year [12,13]. Among nursing home residents the occurrence of falls is 1.5 falls per resident per year, and more than 80% of nursing home residents experience at least one fall per year [4]. Most falls do not cause major injuries [14], but the risk of injuries after falls in the elderly is very high [15]. The annual incidence offalls on the hip among nursing home residents is 36 per 100 falls among women and 16 falls per 100 among men [4]. For cases of impact to the hip, the risk of fracture is 0.25 and 0.33 in women and men in nursing homes [4]. 353
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J. B. Lauritzen and W. C. Hayes
The incidence of hip fracture among nursing home residents is 6.8 and 5.3 per 100 per year among women and men respectively [4]. The incidence among frequent fallers is about 14%. The risk of hip fracture among recurrent fallers treated for fall-related trauma in the emergency room is 41 % within the next year. Orthopedic inpatients older than 75 years of age have an annual risk of hip fracture of 4.1 %, while those with dementia have a 6.5% risk. Those admitted due to fall have a risk of 5.6%, and those admitted with hip fracture a risk of an additional hip fracture of 4.7%. For those with a tendency to fall, the risk of a hip fracture is 6.6% per year and for those with visual impairment the risk is 6.2% per year [16].
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Force and Energy in Falls on the Hip A fall from standing height is associated with a potential energy that may be sufficient to produce hip fracture even in young, healthy subjects [17,18]. For 82 patients who sustained a hip fracture, the potential energy has been estimated to be 442 joules (J) [8]. However, this estimate may be too high based on data from unprotected falls performed by a stunt woman on a force platform. In this case the energy was only 113 1, corresponding to an effective load acting on the hip of 35% of the body weight [19], and a force of 3.5 kN. These results suggest that susceptible subjects are far more likely to suffer a hip fracture in case of impact to the hip.
Protective Responses Elderly subjects experience far more trauma compared with young subjects. Reduced reaction time and degraded coordination are related to risk of fractures [20]. Many patients with hip fractures are admitted from nursing homes, and this group is characterized by disturbances in their neuromuscular functions [21].
Energy Absorption Energy absorption in soft tissue may be a more important factor than bone strength in relation to hip fractures [17,22]. Experimental studies have shown that energy absorption in soft tissue may account for up to 75% of the energy available in a fall [23]. This may partially explain why being overweight protects against hip fractures. Women with a hip fracture weigh on average 5 kg less than controls [24,25]. In addition, women with a hip fracture seem to possess less soft tissue covering their hips compared with controls, even after adjustment for body mass index [25]. It has been suggested that body mass index is a surrogate for measuring the thickness of trochanteric soft tissue thickness [26]. In one study about 42% of registered falls sustained within the home occurred in the bathroom [27]. However, impact attenuation of floor coverings has only a minor effect on the peak force from falls, even when one compares terrazzo with a carpet floor covering [28].
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Bone Strength
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The fracture threshold in the hip has been studied in cadavers and the results may differ according to set-up and loading velocity. The loading angle to the neck seems important [29]. Depending on density the breaking strength in elderly- cadaveric bone ranges from 1000 N to 6000 N, with coefficients of determinations (r) between bone strength and density ranging from 0.7 to 0.9 [17,30]. Bone strength can thus be estimated from bone mineral density [30]. However, bone density on its own is not a good clinical predictor of a later hip fracture as indicated by the major overlap in bone density among elderly fallers between hip fracture patients and controls [31]. In fact, the impact direction and impact site may be stronger predictors of hip fracture risk than femoral bone density [32], whereas the potential energy available and the body mass index provide about the same level of predictability as density.
Hip Padding Systems Various hip padding systems have emerged. There may be an energy shunting type (horse-shoe) [33] including the crash helmet type [34,35], an energy absorptive type[36-38] and an airbag type [39]. Laboratory experiments have suggested that some of the energy absorptive protectors may be insufficient to prevent hip fractures [40-42].
Clinical Studies Nursing Homes The effect of external hip protectors has been tested in four randomized controlled trials in nursing homes (Table 25.1), and two nonrandomized observational studies [36,43] (Table 25.2). The randomized studies showed a reduction in the rate of hip fractures between 0.0 to 0.44 [4,37,44,45] with a pooled average of 0.34. The two largest randomized trials resulted in a reduction in risk during an 11 month period in nursing homes to 0.44 [4] and 0.34 [44]. The two largest studies were based on intention to treat analysis, and when one consider treatment received, i.e., effect of protector when in the use, then the protective effect is high.
Home Dwellers Trials with hip protectors among elderly subjects living at home are rare, although some compliance studies have been performed. In the Hvidovre study [46] the number of hip fractures avoided during an open intervention study among all elderly (> 75 years) orthopaedic patients was recorded in the intervention hospital (n = 1006) and compared with a control hospital (n = 678). The follow-up was l-1Y'2years. Skewness in confounders between intervention group and controls was
J. B. Lauritzen and W. C. Hayes
358 Table 25.4
Compliance rate with hip protectors in two large clinical studies
Lauritzen et al. [4] Ekman et al. [44]
Late compliance
Comments
24% 44%
Rate of users in registered fails, 11 months Registered user rate, 11 months
of the elderly who use protectors spending more time outdoors [50]. Even though compliance may not reach 100%, the overall compliance of hip protectors has been high compared with other medical preventive modalities, and a 40% long-term compliance has been documented after 2 years (K. Hinds0, personal communication 1998). Primary acceptance and late compliance are important issues for the hip protection systems to work efficiently, and information and instructions including late follow-up may be necessary.
Cost-Effectiveness/Cost Savings Hip protectors are cost-saving among frail elderly subjects in the community or in nursing homes [51]. The cost-saving ratio may be about 1 : 3 for nursing home residents. For elderly home dwellers with risk factors for hip fracture the cost-saving ratio may be 1 : 7. The ratio describes the relationship between costs spent for the intervention and money saved due to hip fractures avoided. Providing all Danish women older than 70 years of age and men over 80 years with hip protectors has been estimated to be cost-saving [51]. For clinical reasons, however, preventive efforts should focus on frail elderly subjects with a risk of falling and osteoporosis. Besides the Municipality of Copenhagen, seven other municipalities in Denmark offer hip protectors to nursing home residents and frail elderly subjects with a propensity to fall. In Norway the health care system reimburses nursing home residents for the cost of hip protectors in one central municipality.
Discussion Randomized clinical trials have shown a high efficacy of hip protectors among nursing home residents. The same has been shown for frail elderly home dwellers with visual impairment who were introduced to hip protectors when admitted to an orthopaedic department. Hip fracture has occurred even when wearing hip protectors, and the protectors have been said to induce hip fracture [52] due to the undergarment with hip protectors, which was placed at knee level and subsequently initiated the fall. Even though a hip fracture may occur in spite of the use of hip protectors, i.e., an indirect trauma or spontaneous fracture, it is a less frequent occurrence than would have been anticipated. The benefit of hip protectors in relation to the prevention of periprosthetic hip fractures, luxation of hip arthroplasties and pelvic fractures, pressure sores and chronic bursitis is yet to be outlined and studied further.
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Conclusion Current evidence suggests that hip protectors are of benefit among nursing home residents and some frail elderly home dwellers. Thus, it seems realistic to expect a reduction in the occurrence of hip fractures by 15-25% when a systematic intervention among the frail elderly in nursing homes, hospitals and community is initiated.
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References
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Cummings SR, Nevitt MC. A hypothesis: the causes of hip fractures. J Gerontol 1989; 44:MI07-Ml11. Lauritzen JB, et al. Protection against hip fractures by energy absorption. Dan Med Bull 1998;39:91-93. Hayes WC, et al. Relative risk of fall severity, body habitus and bone density in hip fracture among the elderly. Trans Orthop Res Soc 1991; 16: 70. Lauritzen JB, Petersen MM, et al. Effect of external hip protectors on hip fractures. Lancet 1993;341:11-13. Freeman MAR, et al. The role of fatigue in the pathogenesis of senile femoral neck fractures. J Bone Joint Surg Br 1974;56:698-702. Sloan J, et al. Fractures neck of the femur: causes of the fall? Injury 1981;12:210212.
7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22
Smith LD. Hip fractures: the role of muscular contraction or intrinsic forces in the causation of fractures of the femoral neck. J Bone Joint Surg Br 1953;35:367-383. Hayes WC, et al. Impact near the hip dominates fracture risk in elderly nursing home residents who fall. Calcif Tissue Int 1993;52:192-198. Campbell AJ, et al. Falls in old age: a study of frequency and related clinical factors. Age Ageing 1981;10:264-270. Prudham D EJ. Factors associated with falls in the elderly: a community study. Age Aging 1981;10:141-146. Blake AJ, et al. Falls by the elderly people at home: prevalence and associated factors. Age Ageing 1988;17:365-372. Tinetti ME, et al. Risk factors for falls among elderly persons living in the community. N Engl J Med 1988;319:1701-1707. Downton JH, et al. Prevalence, characteristics and factors associated with falls among the elderly living at home. Age Clin Exp Res 1991;3:219-228. Berry G, et al. Detrimental incidents, including falls, in an elderly institutional population. J Am Geriatr Soc 1981;29:322-324. Kiel DP. Falls. RIMed 1991;74:75-79. Hinds0 K, Lauritzen JB. Risk of subsequent hip fracture in elderly orthopaedic patients. Osteoporos Int 1998;8:18 Lotz JC, et al. The use of quantitative computed tomography to estimate risk of fracture from falls. J Bone Joint Surg AM 1990;72:689-700. Robinovitch SN, et al. Prediction of femoral impact forces in falls on the hip. ASME Biomech Eng 1991;113:336-374. Askegaard V, et al. Load on the hip in a stiff sideways fall. Eur J Exp Musculoskel Res 1995;4:111-116. Adelsberg A, Pitman M, Alexander H. Lower extremity fractures: relationship to reaction time and coordination time. Arch Phys Med Rehabil 1989;79:737-739. Stott S, et al. A prospective study of hip fracture patients. N Z Med J 1980;91:165-169. Lauritzen JB, McNair P, et al. Risk factors for hip fractures. A review. Dan Med Bull 1993;40:479-485.
J. B. Lauritzen and W. C. Hayes
360 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39
Lauritzen IB, et al. Estimate of hip fracture thresh(')ld adjusted for energy absorption in soft tissue. I Nucl Med 1994;21(Suppl):S48. Elsasser U, et al. Deficit of trabecular and cortical bone in women with fracture of the femoral neck. Clin Sci 1980;59:393-395. Lauritzen IB, et al. Body fat distribution and hip fractures. Acta Orthop Scand 1992; 63(Suppl):89. Maitland LA, et al. Read my hips: measuring trochanteric soft tissue thickness. Calcif Tissue Int 1993;52:85-89. DeVito CA, et al. Fall injuries among the elderly: community based surveillance. I Am Geriatr Soc 1988;36:1029-1035. Maki BE, et al. Impact attenuation of floor coverings in simulated falling accidents. Appl Ergon 1990;21:107-114. Pinella TP, et al. Impact direction from a fall influences the failure load of the proximal femur as much as age-related bone loss. Calcif Tissue Int 1996;58:231-235. Courtney AC, et al. Age related reductions in the strength of the femur tested in fall loading configuration. I Bone Ioint Surg AM 1995;77:387-395. Cummings SR, et al. Risk factors for hip fracture in white women. N Engl I Med 1995; 332:767-773. Greenspan SL, et al. Fall severity and bone mineral density as risk factors for hip fracture in ambulatory elderly. lAMA 1994;271:128-133. Hayes WC, et al. Bone fracture prevention garment and method. Washington, DC: US Patent and Trademark Office 1992. Lauritzen IB, et al. Impacts in patients with hip fractures and in vitro study of the padding effect: introduction of a hip protector. Acta Orthop Scand 1990;61(Suppl): 239. Parkkari I, et al. Energy-shunting external hip protector attenuates the peak femoral impact force below the fracture threshold. An in vitro bimechanical study under typical falling conditions of the elderly. I Bone Miner Res 1995;10:1437-1442. Wortberg WE. Hiift-Fraktur-Bandage zur Verhinderung von Oberschenkelhalsbriichen bei alteren Menschen. Der Oberschenkelhalsbruch, ein biomechanisches Problem. Z Gerontol 1988;21:173. Heikinheimo R, et al. To fall but not to break: safety pants. Proceeding of the 13th Triennial Congress of the International Ergonomics Association, Tampere, Finland, 1997: 576-578. Sellberg MS, et al. The development of a passive protective device for the elderly to prevent hip fractures from accidental falls. Adv Bioe 1992;22:505-508. Charpentier PI. A hip protector based on airbag technology. Bone 1996;18(Suppl): 117S.
40 41 42 43 44 45 46 47
Hayes WC, et al. Energy shunting hip padding system reduces femoral impact force from a simulated fall to below fracture threshold. Proceedings of the third injury prevention through biomechanics CDC symposium, 1993. Robinovitch SN, et al. Energy shunting hip padding system attenuates femoral impact force in a simulated fall. I Biomech Eng 1995;117:409-413. Parkkari I, et al. Force attenuation properties of various trochanteric padding materials under typical falling conditions of the elderly. I Bone Miner Res 1994;9: 1391-1396. Parkkari I. Hip fractures in the elderly. Epidemiology, injury mechanisms, and prevention with an external hip protector. Acta Universitatis Tamperensis 1997;550: 1-85. Ekman A, et al. External hip protectors to prevent osteoporotic hip fractures. Lancet 1997;350:563-564. Harada A, et al. Hip fracture prevention trial using hip protector in Iapanese elderly. Osteoporos Int 1998;8:121. Hinds0 K, et al. Intervention study with hip protectors. Osteoporos Int 1998;8:119. Hinds0 K, Lauritzen lB. Behavioral attitude towards hip protectors in elderly orthopedic patients. Osteoporos Int 1998;8:119.
Hip Protectors
48 49 50 51 52
361
Villar T, et al. Trochanteric hip protectors in the institutionalised elderly: a compliance study. Osteoporos Int 1996;6(Suppl):111. Ross J-E, et al. Compliance by elderly in wearing hip joint protectors. In: Third international conference on injury prevention and control, Melbourne, 1996:no.298:73. Hinds0 K, Lauritzen JB. Effect of hip protectors on fear offalling. Osteoporos Int 1998; 8:119. Lauritzen JB, Hinds0 K, Singh G. Cost-effectiveness and external hip protectors. Osteoporos Int 1997;6:130. Cameron I, et al. External hip protectors. [letter]. J Am Gerontol Soc 1997;45:1158.
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Karl Obrant (Ed)
Management of Fractures in Severely Osteoporotic Bone Orthopedic and Pharmacologic Strategies
,
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Springer
Karl Obrant, Professor of Orthopaedics Head of the Department of Medicine, Surgery and Orthopaedics Malmo University Hospital S-205 02 Malmo Sweden
ISBN 1-85233-220-4 Springer-Verlag London Berlin Heidelberg British Library Cataloguing in Publication Data Management of fractures in severely osteoporotic bone: orthopaedic and pharmacologic strategies 1. Osteoporosis 2. Fractures - Treatment 1. Obrant, Karl 616.7'16 ISBN 1852332204 Library of Congress Cataloging-in-Publication Data Management of fractures in severely osteoporotic bone: orthopaedic and pharmacologic strategies/Karl Obrant (ed). p.; cm. Includes bibliographical references and index. ISBN 1-85233-220-4 (alk. paper) 1. Fractures. 2. Osteoporosis - Complications. 1. Obrant, Karl, 1948[DNLM: 1. Fractures - surgery. 2. Fractures - etiology. 3. Fractures - prevention & control. 4. Osteoporosis - complications. 5. Osteoporosis - drug therapy. WE 175 M266 2000 RD10l.M28 2000 617.1'5 - dc21 99-053907 Apart from any fair dealing for the purposes of research or private study, or criticism or review, as permitted under the Copyright, Designs and Patents Act 1988, this publication may only be reproduced, stored or transmitted, in any form or by any means, with the prior permission in writing of the publishers, or in the case of repro graphic reproduction in accordance with the terms of licences issued by the Copyright Licensing Agency. Enquiries concerning reproduction outside those terms should be sent to the publishers. © Springer-Verlag London Limited 2000 Printed in Great Britain
The use of registered names, trademarks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant laws and regulations and therefore free for general use. Product liability: The publisher can give no guarantee for information about drug dosage and application thereof contained in this book. In every individual case the respective user must check its accuracy by consulting other pharmaceutical literature. Typeset by Florence Production Ltd, Stoodleigh, Devon Printed and bound at The Cromwell Press, Trowbridge, Wiltshire, England 28/3830-543210 Printed on acid-free paper SPIN 10745424
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