Advances in Biomaterials, 8

Implant Materials in Biofimction Proceedings of the Seventh European Conference on Biomaterials, Amsterdam, The Netherlands, September 8 -11 ,1987

edited by

C . de Putter 1 , G.L. de Lange 2 , Κ. de Groot 3

1 Department of Oral Implantology, 2 Department of Oral Biology, 3 Department of Biomaterials, Academic Centre for Dentistry Amsterdam (ACTA), Free University, Amsterdam, The Netherlands

and

A.J.C. Lee Department of Engineering Science, University of Exeter, Exeter, England

E L S E V I E R Amsterdam — Oxford — New York — Tokyo 1988

IX

Contents

Series Foreword V

Preface VII

Keynote lectures

Regulation in the field of biomaterials in the Federal Republic of Germany E. Tschöpe 1

Consensus and definitions in biomaterials D.F.Williams 11

Biomechanical requirements on ligament prostheses L. Claes, L. Dürselen , 17

Section 1. Biocompatibility testing »

Biocompatibility of Estane® and PBT/HPOE (45/55) segmented polyether polyester copolymer during infection D. Bakker, C.A. van Blitterswijk, S.C. Hesseling, W. Th. Daems, J J . Grote 25

Surface modification of synthetic polymer materials for medical use: addition of fibrinolytic and antibacterial activities S. Watanabe, O. Ike, T. Nakamura, Y. Shimizu, Y. Tamada, Y. Ikada 31

Leukocytes at the tissue-implant interface L.M. Bjursten, A.S. Eriksson, R. Olsson, P. Thomsen, L.E. Ericson 37

Accumulation of trace elements by macrophages during degradation of biomaterials. An electron microscopical and X-ray microanalytical study H.K. Koerten, C.A. van Blitterswijk, J.J. Grote, W.Th. Daems 43

Biomaterial/tissue interface characteristics of four elastomers D. Bakker, C.A. van Blitterswijk, S.C. Hesseling, W.Th. Daems, J.J. Grote 49

Quantitative in vitro measurements of three cellular properties involved at tissue/material interface. Standardisation of the technique M.F. Sigot-Luizard, J.L. Duval, M. Letort, M. Sigot 55

Reconstruction of the abdominal wall with processed sheep dermal collagen — an experimental study in dogs A.C. van der Wal, N.J.Μ. Out, Α. van den Hooff, P.J. Klopper 61

Section 2. Biomaterial-hard tissue interactions

Histologie reactions to different hydroxyapatite granules S. Jänicke, W. Wagner, U. Wahlmänn 67

Collagenous and non-collagenous bone proteins in rats and rabbits at the bone-implant interface of bone-bonding and non-bonding glass-ceramics R. W. Kinne, H.-J. Schmitz, U. Gross 73

Tissue response to a bioactive glass-metal interface E. Schepers, Μ. De Clercq, P. Ducheyne 79

Removal forces for osseointegrated titanium implants C. Johansson, M. Jacobsson, T. Albrektsson 87

Reconstruction of the external ear canal and middle ear with hydroxyapatite implants H.W. Lutgert, C.A. van Blitterswijk, J.J. Grote 93

Morphometric and histologic evaluation of enosseal implanted carbon fibre reinforced polysulfone U.W. Wahlmann, W. Wagner 99

Relation between physico-chemical solubility and biodegradability of calcium phosphates F. C.M. Driessens, R.M.H. Verbeeck 105

χ

Section 3. Orthopaedics

A new design of ligament prosthesis for anterior cruciate ligament replacement J. Leandri, Ph. Dahhan, 0. Tarragano, M. Cerol, P. Rev, D. Geiger 113

Aramid fibers and bone interactions in anterior cruciate ligament repair in dogs N. Passuti, G. Daculsi, M. Vigneron, J.C. Le Nihouannen, C. Cistac 119

Material properties of human cruciate ligaments in total knee arthroplasty Th. Mittlmeier, G. Wasmer, G.O. Hofmann, F.-W. Hagena, M. Bergmann, A. Walter 125

Experimental biomechanics of the femoropatellar joint after implantation of different knee joint endoprostheses G.O. Hofmann, F.-W. Hagena, J.S. Zimmermann 131

Pathomechanical aspects of failed total knee arthroplasties F. -W. Hagena, G.O. Hofmann, J.S. Zimmermann 137

On the geometrical shape of artificial hip joint bearings with articulation of identical materials A. Walter, F. Böhmer 143

Influence of assemblage geometry and fracture type on stability of monolateral external fixation B. Dreithaler, H.H. Schauwecker, Μ. Schmargon, R. Wilk 149

Ceramic prosthesis in reintervention for "aseptic" loosening G. Gualtieri, I. Gualtieri, S. Gagliardi, M. Hendriks 155

Porous polysulfone coated femoral stems A.J. Gavens, N.B. Beals, M.F. DeMane, J.A. Davidson, J.R. Roberson, I. Heyligers, M. Miller, M. Spector 159

Bioglaze coating of metallic femoral prosthetic stems: fatigue test A. Moroni, R. Mongiorgi, M. Marcacci, A. Krajewski, A. Ravaglioli 165

Investigation of the neo-synovia at knee prostheses A. Walter, F.-W. Hagena, G.-O. Hofmann 171

The clinical use of plastic plates for osteosynthesis in human fractures A.J. Tonino 177

Section 4. Biomaterials and complement activation

Molecular mechanism of complement activation on polymer surfaces: contact activation of reconstituted first component (C1) of classical pathway M. Niinobe, T. Matsuda, H. Twata 181

Effects of the hydrophobic-hydrophilic nature of the polymer surfaces on the complement activation S. Yoshikawa, H. Fukumura, Y. Akagaki, S.-Y. Inai 187

Comparative study of proteins adsorbed on dialysis membranes, complement and platelets activation V. Panichi, A.M. Bianchi, L. Casarosa, R. Cominotto, M. Parrini, G. Grazi, C. Cirami, R. Palla 193

New polymethylmethacrylate-polyurethane (PMMA-PU) membranes for hemodialysis applications G. Soldani, M. Palla, G. Barini, P. Giusti, G. Levita, A.M. Bianchi, V. Panichi, R. Palla 201

Section 5. Biological performance of Ca-phosphates

In vitro interactions between calcium phosphate biomaterials and human fibroblastic cell. I. Comparative extra and intracellular evolution of 4 synthetic calcium phosphates I. Orly, M. Gregoire, J. Menanteau, I. Jans, J.C. Heughebaert, B. Kerebel 211

In vitro interactions between calcium phosphate biomaterials and human fibroblastic cell. II. Incidences on the behavior of cultured gingival cells M. Gregoire, I. Orly, J. Menanteau, M. Heughebaert, B. Kerebel 215

XI

Biological performance of hydroxyapatite as otologic biomaterial: An evaluation of clinical applied hydroxyapatite C.A. van Blitterswijk, J.J. Grote, H.W. Lutgert, H.K. Koerten 221

Histologic evaluation of ceramo-osseous regeneration complexes in human bone following hydroxyapatite ceramic implantation J.F. Osborn 227

High resolution lattice imaging of hydroxyapatite R. Hodgskinson, W. Bonfield 233

pH, HA, TCP and Bioactivity B.J. Fellows, H.J. Oel 239

Section 6, Biological performance of poly-L-lactide

In vivo and in vitro degradation of poly(L-lactide) used for fracture fixation R.R.M. Bos, F.R. Rozema, G. Boering, J.W. Leenslag, A.J. Pennings, A.B. Verwey 245

Absorbable bone-plates and screws for the fixation of malar fractures F.R. Rozema, R.R.M. Bos, G. Boering, J.W. Leenslag, A.J. Pennings, A.B. Verwey 251

Release and degradation characteristics and antitumor effect of adriamycin-containing poly-L-lactic acid microspheres 0. Ike, S. Watanabe, T. Nakamura, R. Wada, S.-H. Hyon, S. Hitomi, Y. Ikada, Y. Shimizu... 257

Macrophage activation for antitumor function by a muramyl dipeptide derivative encapsulated in polyactide microspheres Y. Tabata, Y. Ikada 263

Section 7. Soft tissue-biomaterial interactions

Cellular synthesis performance in different collagen extraction mediums J. Dohrenbusch, Μ. Kern, Τ. Otterbach, Β. Klosterhalfen, Α. Valencia 269

Surface energy considerations in the adsorption of proteins to metals D.F. Williams, R.L Williams 275

Tissue compatibility from different high cross-linked colagen sponges after subcutaneous implantation in mice H.A. Richter, J. Buchenroth, S. Handt, N. Maurin, Ch. Mittermayer 279

Wound healing phenomena around permanent percutaneous implants in guinea pigs and rabbits J. A. Jansen, Κ. de Groot 285

Destruction of erytrocytes under sinusoidally fluctuating shear rate S. Hashimoto, A. Ishihara, T. Sasada 291

Modification of polyetherurethane for endothelial cell seeding W. Breuers, D. Klee, Η. Höcker, C. Mittermayer 297

Section 8. Biomaterial evaluation

Constitution of oxides on titanium alloys for surgical implants P.-A. Mäusli, J.P. Simpson, G. Burri, S.G. Steinemann 305

Microchardness, Young's modulus and mineral content in bone and a bone analogue G.P. Evans, J.C. Behiri, W. Bonfield 311

Monomeric reactive centres in polymeric prosthetic materials A. Bertoluzza, P. Filippetti, P. Monti, M.R. Tosi, R. Caramazza, M. Cellini 317

A computerisation programme for handling data on the biocompatibility of implant materials C. Zolezzi, A. Casanova, S. Stea, L. Pratelli, G. Ciapetti, A. Pizzoferrato 323

Mucin pellicles protect hydroxyapatite against decalcification A.V. Nieuw Amerongen, C.H. Oderkerk, E.C.I. Veerman, K. de Groot 327

XII

Immunochemical identification of proteins adsorbed onto hydroxyapatite after in vivo and in vitro incubation with serum and plasma E.C.I. Veerman, R.J.F. Suppers, C.P.A.T. Klein, K. de Groot, A.V. Nieuw Amerongen 331

Comparison of in vivo and in vitro protein adsorption patterns to bone substitutes E. C.I. Veerman, R.J.F. Suppers, C.P.A.T. Klein, K. de Groot, A.V. Nieuw Amerongen 337

Ultrastructural evaluation of different biomaterial phagocytoses by macrophages S. Guizzardi, G. Ciapetti, C. Tarabusi, S. Stea, A. Ruggeri, R. Riva, A. Pizzoferrato 343

Evaluation of adhesion capability of conjunctival Staphylococcus aureus on polymeric materials C. Arciola, P. Versura, G. Ciapetti, P. Monti, A. Pizzoferrato, R. Caramazza 349

Oxygen permeability through hydrogel membranes L. Nicodemo, F. Bellucci, C. Migliaresi, R. Le Rose, C. Carfagna, S. Nappi 355

The biocompatibility of intraocular-lens-haptics made of polypropylene and polymethylmethacrylate 361

Model for dynamic construction of isoelastic tubular prosthesis at the example of the trachea H.H. Schauwecker, J. Gerlach, H. Planck, E.S. Bücherl 371

The in vitro aging of polymers R. Mathys Jr., H. Weigum, P. Herzig, F. Bigolin 377

The corrosion fatigue properties of surgical implants in a living body M. Morita, H. Hayashi, T. Sasada, Y. Tsukamoto, M. Yamamoto 381

A study of the foaming ceramization process in the synthesis of porous phosphate glass-ceramics for bone implants F. Pernot, A. Kadom Rashid 387

Influence of silicone co-block on performance of polyetherurethane biomaterials R.J. Zdrahala, D.E. Spielvogel, D.D. Solomon 393

Section 9. Biocompatibility and biofunctionality of cardiovascular prothesis

The effects of lipid diet on long term patency rate of degradable polyurethane vascular prosthesis in pigs G. Galletti, S. Leonardi, G. Ussia, F. Farruggia, A. Salerno, S. Gogolewksi 399

Processed dermal sheep collagen (PDSC) as a small diameter vascular graft J.J.G. Bannenberg, A.C. van der Wal, P.J. Klopper 405

Bio-mechanical design of novel elastomeric vascular adhesive: significance of compliance matching T. Matsuda, T. Yamaguchi, K. Hayashi, T. Itoh, H. Iwata, N. Nakajima 411

Early stages of dystrophic calcification in bioprosthesis cardiac valves: experimental animal model G. Noera, C. Massini, G. Fattori, A. Incerti Medici, A.M. Gatti 417

Section 10. Biomechanics of bone

Osteoarthrosis and the mechanical behaviour of trabecular bone in the human femoral head K.E. Tanner, D.J. Sharp, C. Doyle, R.R.H. Coombs, W. Bonfield 423

An investigation into the transmission of shock through the vertebral column M. Müller-Gerbl, 0. Ennemoser, R. Putz 429

Elastic and anelastic microstrain measurement in human cortical bone M. Dabestani, W. Bonfield 435

Compressive behavior and water distribution of human lumbar vertebral disc by MRI T. Ushida, T. Tateishi, K. Honma. Y. Shirasaki, K. Hyodo 441

Contribution of mechanical factors to the pathogenesis of osteochondritis dissecans in the knee joint T. Nambu, E. Schneider, W. Bandi, S.M. Perren 447

Stabilization of distal radius fractures — biomechanical testing of K-wire- and polydioxanon-(PDS)-pins C. Krettek, R. Hoffmann, N. Haas 453

XIII

Section 11. Biomaterials in oro-facial surgery

Hydroxylapatite implants in periodontal bone defects in dogs G. L. de Lange, E.H. Burger, C. de Putter, Κ. de Groot 457

Loading permucosal dental implants of hydroxylapatite with orthodontic forces C. de Putter, G.L. de Lange, W. Hickory, K. de Groot, B. Prahl-Andersen 465

Submucosal dental implants of hydroxylapatite under fixed arid removable bridges F.L.J.A. de Wijs, J.A. van den Wijngaard, G.L. de Lange, Κ. de Groot, C. de Putter 471

The application of hydroxylapatite in endodontics W. van Welsenes, G.L. de Lange 477

Healing of the gingiva following installment of Biotes® implants in beagle dogs H. J.Y, van Drie, W. Beertsen, A. Grevers 485

Section 12, Controlled release

Preparation and properties of novel self-regulating membrane H. Iwata, T. Matsuda 491

Microencapsulation of islets in novel polyion-complex membranes and its evaluation as bioartificial pancreas H. Iwata, T. Matsuda, H. Amemiya, H. Takano, T. Akutsu 497

Author Index 503 Subject Index 506

Implant Materials in Biofunction, 429 edited by C. de Putter, G.L. de Lange, Κ. de Groot and A.J.C. Lee, Advances in Biomaterials, Volume 8, Elsevier Science Publishers B.V., Amsterdam, 1988 — Printed in The Netherlands

AN INVESTIGATION INTO THE TRANSMISSION OF SHOCK THROUGH THE VERTEBRAL COLUMN

M.MUELLER-GERBL 1,0.ENNEMOSER 2 and R.PUTZ 1

1 A n a t o m i s c h e s I n s t i t u t , L e h r s t u h l 1 1 1 , A l b e r t s t r . 1 7 f D-7800 F r e i b u r g 2 I n s t i t u t für M e d i z i n i s c h e P h y s i k , M ü l l e r s t r . 4 4 , A-6020 I n n s b r u c k

ABSTRACT

S i x f r e s h s p e c i m e n s from t h e lumbar v e r t e b r a e u/ere e x a m i n e d under m e c h a n i c a l s t r e s s ( a blow a p p l i e d t o t h e un d e r s u r f a c e o f t h e low­e s t v e r t e b r a w i t h or w i t h o u t l o a d i n g o f t h e s p e c i m e n from a b o v e ) . To d e t e r m i n e t h e r e l a t i v e i m p o r t a n c e of t h e t r a b e c u l a r bone and i t s c o n t a i n e d marrow a s ^ h o c k - a b s o r b e r s 1 i n t h e s p i n a l column, the s p e c i m e n s were e x a m i n e d a f t e r r e m o v a l of spongy bone and marrow and s u b s e q u e n t f i l l i n g w i t h P a l a c o s . I t h a s been d e m o n s t r a t e d t h a t b o t h bone and marrow a r e n e c e s s a r y f o r e f f i c i e n t damping, e s p e c i a l l y i n t h e h i g h e r f r e q u e n y r a n g e , a l t h o u g h t h e i r i m p o r t a n c e d e p e n d s on t h e f r e q u e n c y i n d e c i b e l s o f t h e t r a n s m i t t e d s h o c k . The i n t e r v e r t e b r a l d i s c s a r e i m p o r t a n t when b l o w s a p p l i e d t o t h e column a r e l i g h t , and t h e n o r m a l k y p h o s e s and l o r d o s e s a l s o p l a y a p a r t i n t h e a b s o r p t i o n of s h o c k .

INTRODUCTION

I n t h e c o u r s e of e v e r y d a y l i f e t h e v e r t e b r a l column i s

s u b j e c t e d t o a l a r g e number of bl o w s w h i c h i t can o n l y s u s t a i n

w i t h o u t damage f o r any l e n g t h o f t i m e i f i t s s h o c k - a b s o r b i n g

mechanism i s f u n c t i o n i n g s a t i s f a c t o r i l y . T h i s c a p a c i t y f o r s h o c k

a b s o r p t i o n and s h o c k t r a n s m i s s i o n i s s t i l l o n l y i m p e r f e c t l y

u n d e r s t o o d . I t i s q u i t e u n c e r t a i n , f o r i n s t a n c e , what t h e

r e s p e c t i v e r o l e s o f t h e i n t e r v e r t e b r a l d i s c and t h e v e r t e b r a l body

i t s e l f may be.

Our p r e v i o u s i n v e s t i g a t i o n s ( r e f . 1 ) on s e v e r a l v o l u n t e e r s have

e s t a b l i s h e d t h a t an e s s e n t i a l component o f t h i s mechanism i s

p r o v i d e d by t h e n a t u r a l c u r v e s o f t h e column. W h i t e and P a n j a b i

( r e f . 2 ) have a l s o e x p r e s s e d t h e o p i n i o n t h a t i t s n o r m a l

a n a t o m i c a l l o r d o s e s and k y p h o s e s a c t t o some e x t e n t a s s h o c k -

a b s o r b e r s .

N e v e r t h e l e s s , t h e s u p p o r t g i v e n by t h e s e c u r v e s i s , by i t s e l f ,

i n s u f f i c i e n t t o a c c o u n t f o r i t s c a p a c i t y t o a b s o r b s h o c k s w i t h o u t

430

b e i n g damaged. A c c o r d i n g to I n o u e ( r e f . 3 ) , t h e i n t e r v e r t e b r a l

d i s c s a c t a s s h o c k - a b s o r b e r s by a s s i m i l a t i n g c o m p r e s s i o n f o r c e s

a p p l i e d to t h e v e r t e b r a l column. T h i s s h o c k - a b s o r b i n g c a p a c i t y of

t h e d i s c i s , i n p a r t , d e p e n d e n t on t h e f a c t t h a t t h e a n u l u s f i b r o -

s u s c a n expand or b u l g e o u t w a r d s i n r e s p o n s e t o t h e ou t w a r d

t h r u s t of t h e n u c l e u s p u l p o s u s when i t i s under p r e s s u r e from i t s

n e i g h b o u r i n g v e r t e b r a e ( r e f , 2 ) . I n o u e m a i n t a i n s , h owever, t h a t

t h e c a r t i l a g i n o u s e n d - p l a t e s p l a y an i m p o r t a n t p a r t t o o .

T r a b e c u l a r bone i s a l s o s u p p o s e d t o c o n t r i b u t e t o w a r d s t h e

a b s o r p t i o n o f i m p a c t s ( r e f . 4 ) , and i t s f u n c t i o n i s c o n s i d e r e d t o

be g r e a t l y e n h a n c e d by t h e p r e s e n c e o f bone-marrow ( r e f . 5 ) .

uJe a r e h e r e c o n s i d e r i n g t h e q u e s t i o n : what p a r t does t h e v e r ­

t e b r a l body, i n c l u d i n g i t s c o n t a i n e d marrow, p l a y i n t h e

a b s o r p t i o n of s h o c k ?

MATERIAL

liie u s e d s i x f r e s h s p e c i m e n s from t h e i n t a c t lumbar column,

b e i n g c a r e f u l t o c h e c k t h a t t h e r e was n o t h i n g i n t h e h i s t o r y of

any of them t o s u g g e s t p a t h o l o g i c a l c h a n g e . B e f o r e we began, we

o b t a i n e d AP and l a t e r a l x - r a y s of e a c h s p e c i m e n . The age of t h e

s u b j e c t s ( f o u r male and two f e m a l e ) l a y between 15 and 66 y e a r s .

E a c h s e c t i o n of t h e column c o n s i s t e d o f 2 t o 5 "Bewegungssegmente"

(JUNGHANNS 1 " l o c o m o t i o n s e g m e n t " ) ( T a b l e 1 ) .

TABLE 1

S p e c i m e n Age Sex Number of s e g m e n t s

No.1 60 y e a r s male 4 No.2 65 y e a r s f e m a l e 5 No.3 66 y e a r s f e m a l e 2 No.4 57 y e a r s male 3 No.5 15 y e a r s male 2 No.6 45 y e a r s male 2

METHODS

A ma c h i n e h a s been c o n s t r u c t e d w h i c h makes i t p o s s i b l e t o

s u b m i t s e g m e n t s of t h e v e r t e b r a l column t o v a r i o u s d e g r e e s of

l o a d i n g from above ( F i g . 1 ) . I t i s a l s o p o s s i b l e w i t h t h i s machine

to a p p l y s h o c k s of d i f f e r e n t s t r e n g t h s ( 2 - 6 f g f ) t o t h e l o w e s t

v e r t e b r a from u n d e r n e a t h . I n o r d e r t o me a s u r e t h e f o r c e of t h e

s h o c k , we s c r e w e d a c c e l e r o m e t e r s ( I C P A c c e l e r o m e t e r ; PCB Model No.

303 A l l - P i e z o - t r o n i c s - r a n g e : + 10 t o - 10 g) t o t h e s p i n e s

o f t h e l o w e s t and h i g h e s t v e r t e b r a e . The d a t a c o l l e c t e d were t h e n

t r a n s m i t t e d t h r o u g h an A D - c o n v e r t e r d i r e c t l y i n t o a PC f o r f u r t h e r

431

c o m p u t a t i o n . The d i s t o r t i o n of t h e i n t e r v e r t e b r a l d i s c s was

m e a s u r e d w i t h s t r a i n g auges (HBM DMD 2 0 ) s t i t c h e d t o them i n a

h o r i z o n t a l p o s i t i o n , and t h e v a l u e s of t h e s i g n a l s r e g i s t e r e d w i t h

a y t - w r i t e r .

F i g u r e 1 : D i a g r a m m a t i c r e p r e s e n t a t i o n of t h e a p p a r a t u s u s e d f o r

t h e e x p e r i m e n t

I n o r d e r t o c a l c u l a t e t h e f r e q u e n c y - d e p e n d e n c e of t h e s h o c k

a t t e n u a t i o n , a d i s c r e t e F o u r i e r t r a n s f o r m was u s e d t o o b t a i n t h e

f r e q u e n c y s p e c t r u m of t h e a c c e l e r a t i o n v a l u e s . S i n c e t h e maximum

F o u r i e r c o e f f i c i e n t s l a y i n t h e f r e q u e n c y r a n g e of 100 - 200 Hz,

s t e p s a t i n t e r v a l s of 5 Hz from 5 t o 250 Hz were more c l o s e l y

i n v e s t i g a t e d . I f one d i v i d e s t h e v a l u e o f t h e F o u r i e r a m p l i t u d e

m e a s u r e d by t h e h i g h e r r e c o r d i n g p o s i t i o n w i t h t h a t m e a s u r e d by

t h e l o w e r , a v a l u e f o r t h e s o - c a l l e d " f r e q u e n c y r e s p o n s e f u n c t i o n "

i s o b t a i n e d . The v a l u e of t h i s f u n c t i o n - w h i c h i s measured i n

d e c i b e l s - p r o v i d e s i n f o r m a t i o n a b o u t t h e r e l a t i v e d e p e n d e n c y o f

t h e s h o c k - a b s o r b i n g c a p a c i t y on t h e f r e q u e n c y . N e g a t i v e d e c i b e l

v a l u e s s i g n i f y e f f i c i e n t s h o c k - a b s o r p t i o n . P e a k s w i t h p o s i t i v e

d e c i b e l v a l u e s i n d i c a t e r e s o n a n c e p o i n t s , w h i c h means t h a t a t t h i s

f r e q u e n c y t h e s h o c k i s i n c r e a s e d .

432

RESULTS

The a b i l i t y o f t h e s p e c i m e n s t o a b s o r b s h o c k d e t e r i o r a t e s i f

t h e e x p e r i m e n t i s c o n t i n u e d f o r t o o l o n g ( F i g . 2 . ) · W i t h i n 35

m i n u t e s of l o a d i n g t h e s p e c i m e n w i t h 20 kg t h e g r e a t e r p a r t of t h e

f r e q u e n c y r e s p o n s e f u n c t i o n r e m a i n s i n t h e n e g a t i v e r a n g e ; i n

o t h e r w o r d s , s h o c k - a b s o r p t i o n i s e f f i c i e n t . I f , h o w e v e r , a s t h e

e x p e r i m e n t i s c o n t i n u e d , t h e f r e q u e n c y r e s p o n s e f u n c t i o n b e g i n s t o

s h i f t i n t o t h e p o s i t i v e r a n g e , t h e c a p a c i t y f o r s h o c k - a b s o r p t i o n

becomes l e s s and l e s s .

12

OD -6 3 -12

υ 12

Ml

=-12

-6

-12

AFTER 135 MIN

SPINE NR.: 2

AFTER 120 MIN

SPINE NR.: 2

AFTER 35 MIN

50 100 150

FREQUENCY

200

(Hz)

250

12

6

0

ω -6

ο Μ

6 ÜJ w ο ο

6 ÜJ

-12

ÜJ 12 α

0

-6

-12

FILLED WITH PALAKOS

SPINE NR.: 5

WITHOUT CANCELLOUS BONE

SPINE NR.

BEFORE PREPARATION

50 100 150

FREQUENCY

200

(Hz)

250

F i g . 2 F i g . 3

F i g u r e 2 : F r e q u e n c y r e s p o n s e f u n c t i o n and i t s d e p e n d e n c e on

t h e d u r a t i o n o f t h e e x p e r i m e n t .

F i g u r e 3 : F r e q u e n c y r e s p o n s e f u n c t i o n i n t h e i n t a c t s p e c i m e n ( l o ­

wer c u r v e ) a f t e r r e m o v a l o f t h e spo n g y bone and marrow ( m i d d l e

c u r v e ) and t h e i r r e p l a c e m e n t w i t h P a l a c o s ( u p p e r c u r v e ) i n s p e c i m e n

No.5

433

I n o r d e r t o a s s e s s t h e p a r t p l a y e d by t h e v / e r t e b r a l b o d i e s i n

a b s o r b i n g s h o c k , we removed t h e t r a b e c u l a r bone from t h e m i d d l e

v e r t e b r a and f i l l e d i t up w i t h m e t h y l m e t h a c r y l a t e ( P a l a c o s ) i n

s p e c i m e n s No.5 and 6. F i g . 3 shows t h e b e h a v i o u r of s p e c i m e n No.5

a t a l l s t a g e s o f t h e p r o c e d u r e : w h i l e s t i l l u n t o u c h e d , a f t e r t h e

r e m o v a l o f t h e s p o n g i o s a and f o l l o w i n g i t s r e p l a c e m e n t w i t h

P a l a c o s . A f t e r t h e s p o n g i o s a had been t a k e n away from t h e m i d d l e

v e r t e b r a t h e f r e q u e n c y r e s p o n s e f u n c t i o n showed f e w e r p e a k s . I f

t h e f r e q u e n c y ( a b s c i s s a ) i s above 100 Hz, t h e c o r r e s p o n d i n g

d e c i b e l v a l u e ( o r d i n a t e ) i s l o w e r t h a n w i t h t h e i n t a c t s p e c i m e n .

I n c o n t r a s t t o t h i s , w i t h f r e q u e n c i e s below 100 Hz, t h e d e c i b e l

v a l u e r i s e s 1 . 7 - f o l d , w h i c h c o r r e s p o n d s t o a d e t e r i o r a t i o n i n t h e

damping e f f e c t . A f t e r we had f i l l e d t h e v e r t e b r a l body w i t h

P a l a c o s , t h e f r e q u e n c y r e s p o n s e f u n c t i o n ( p a r t i c u l a r l y i n t h e

h i g h e r f r e q u e n c y r a n g e ) showed a 3 . 3 - f o l d i n c r e a s e , w h e r e a s o n l y a

1 . 4 - f o l d i n c r e a s e was f o u n d i n t h e l o w e r r a n g e . S p e c i m e n No.6

r e s p o n d e d i n t h e same way.

The more u n i f o r m t h e c u r v e o f t h e a c c e l e r a t i o n v a l u e s , t h e more

c o n t r a d i c t o r y d i d t h e m e a s u r e m e n t s p r o d u c e d by t h e s t r a i n g a uges

become. A r h y t h m i c a l o s c i l l a t i o n was f ound i n a l l c a s e s . E n t i r e l y

a g a i n s t o u r e x p e c t a t i o n s , t h e i n i t i a l r e s p o n s e was one of c o n t r a c ­

t i o n . U/ith o n l y one s p e c i m e n d i d t h e o s c i l l a t i o n of t h e i n t e r v e r ­

t e b r a l d i s c b e g i n w i t h e x p a n s i o n .

D I S C U S S I O N

The d e t e r i o r a t i o n o f damping e f f i c i e n c y o b s e r v e d i n t h e

v e r t e b r a l c o l u m n a s t h e s t r e s s a p p l i e d t o i t c o n t i n u e s , i s

p r o b a b l y due t o t h e e x p u l s i o n of f l u i d from t h e i n t e r v e r t e b r a l

d i s c i n t o t h e s u r r o u n d i n g t i s s u e s . L o n g e r i n t e r v a l s between t h e

b l o w s a l l o w s u f f i c i e n t t i m e f o r t h i s f l u i d t o be r e p l a c e d .

The e f f e c t o f r e m o v i n g t h e s p o n g i o s a from t h e v e r t e b r a l body

and r e p l a c i n g i t w i t h P a l a c o s c l e a r l y d e m o n s t r a t e s t h e

c o n t r i b u t i o n o f t h e t r a b e c u l a r bone and i t s c o n t a i n e d marrow t o

t h e damping c a p a c i t y o f t h e w h o l e column, t h e d e g r e e of w h i c h i s ,

h o w e v e r , f r e q u e n c y - d e p e n d e n t . I t i s more i m p o r t a n t i n t h e h i g h e r

f r e q u e n c y r a n g e t h a n i n t h e l o w e r .

The s u p p o r t c o n t r i b u t e d t o s h o c k - a b s o r p t i o n by t h e d i s c s comes

t o t h e f o r e when t h e b l o w s a r e weak. With a f r e q u e n c y of more t h a n

100 Hz - t h a t i s t o s a y , f o l l o w i n g s t r o n g e r b l o w s - t h e s i g n i f i ­

c a n c e o f t h e s p o n g i o s a / m a r r o w s y s t e m i n c r e a s e s . J u d g i n g from t h e

434

damping c u r v e s o b t a i n e d , t h e i n s i d e of t h e v e r t e b r a l body i s an

i m p o r t a n t component of t h e damping s y s t e m .

liie have h e r e an e x p e r i m e n t a l c o n f i r m a t i o n of t h e v i e w s

e x p r e s s e d by P a t w a r d h a n and h i s c o - w o r k e r s (1 9 8 5 ) on t h e r o l e of

spongy bone; and our r e s u l t s a l s o a g r e e w i t h t h e f i n d i n g s of Hayes

e t a l . ( 1 9 7 6 ) , who a t t r i b u t e d a s i m i l a r f u n c t i o n t o t h e bone-

marrow ·

T h i s means t h a t a l l t h e e l e m e n t s of J u n g h a n n s 1 " l o c o m o t i o n

s e gment", i n c l u d i n g b oth v e r t e b r a l b o d i e s , a r e n e c e s s a r y f o r t h e

damping s y s t e m of t h e s p i n a l column t o be f u l l y e f f e c t i v e ; and

o n l y when a l l p a r t s a r e i n t a c t and f u n c t i o n i n g p r o p e r l y c a n b l o w s

be e f f e c t i v e l y t a k e n up and r e n d e r e d i n n o c u o u s .

E f f i c i e n t l y t r a i n e d back m u s c l e s a r e a l s o , of c o u r s e , p r e s u p ­

p o s e d . They s h o u l d be i n a p o s i t i o n t o c o n t r o l t h e f l e x i o n of t h e

whole column i n an o p t i m a l manner ( r e f . 1 ) .

The p a r a d o x o f t h e r h y t h m i c a l o s c i l l a t i o n of t h e i n t e r v e r t e b r a l

d i s c , w h i c h i n i t i a l l y shows e i t h e r c o m p r e s s i o n or e x p a n s i o n , i s

p r o b a b l y bound up w i t h t h e d i f f e r e n t d i r e c t i o n and p u l l of t h e

f i b r e s of t h e a n u l u s f i b r o s u s . V e r y l i k e l y i t s t e x t u r e - t h e

l a y o u t o f t h e f i b r o u s l a m e l l a e - i s r e s p o n s i b l e .

REFERENCES :

1 P u t z , R., E n n e m o s e r , 0. » K ü n s t l e , M . (1981 ) : Zum D ä m p f u n g s v e r h a l t e n d e r W i r b e l s ä u l e . V e r h . A n a t . G e s . 7 5 , 2 5 1

2 W h i t e , A . A . , P a n j a b i f M . M . ( 1 9 7 8 ) : C l i n i c a l b i o m e c h a n i c s of t h e s p i n e , 2-17. P h i l a d e l p h i a : J . B . L i p p i n c o t t Co.

3 I n o u e , H . ( 1 9 8 1 ) : T h r e e - d i m e n s i o n a l a r c h i t e c t u r e of lumbar i n t e r v e r t e b r a l d i s c s . S p i n e 6,139-146

4 P a t w a r d h a n , A . , V a n d e r b y , R . , K n i g h t , G . W . , G o g a n , W . J . , L e v i n e , P . D . ( 1 9 8 5 ) : B i o m e c h a n i c s of t h e s p i n e , 1 3 9 - 1 5 0 , i n : A t l a s of O r t h o t i c s , S t . L o u i s : The C.V.Mosby Company

5 H a y e s , W . C . , C a r t e r , D . R . ( 1 9 7 6 ) : The e f f e c t o f marrow e n e r g y ab­s o r p t i o n of t r a b e c u l a r bone. P r e s e n t e d a t t h e 22nd A n n u a l M e e t i n g o f t h e O r t h o p a e d i c R e s e a r c h S o c i e t y , New O r l e a n s

6 K r ä m e r , J . ( 1 9 7 3 ) : B i o m e c h a n i s c h e V e r ä n d e r u n g e n im l u m b a l e n Bewegungssegment, d i e W i r b e l s ä u l e i n F o r s c h u n g und P r a x i s 58, H i p p o k r a t e s S t u t t g a r t