Effects of Daily Treatment with Parathyroid Hormone onBone Microarchitecture and Turnover in Patients with

Osteoporosis: A Paired Biopsy Study*

DAVID W. DEMPSTER,1,2 FELICIA COSMAN,3,4 ETAH S. KURLAND,4 HUA ZHOU,1 JERI NIEVES,3,5

LILLIAN WOELFERT,3 ELIZABETH SHANE,4 KATARINA PLAVETIC ,1 RALPH MULLER,6

JOHN BILEZIKIAN,4,7 and ROBERT LINDSAY3,4

ABSTRACT

We examined paired iliac crest bone biopsy specimens from patients with osteoporosis before and aftertreatment with daily injections of 400 U of recombinant, human parathyroid hormone 1-34 [PTH(1–34)]. Twogroups of patients were studied. The first group was comprised of 8 men with an average age 49 years. Theywere treated with PTH for 18 months. The second group was comprised of 8 postmenopausal women with anaverage age 54 years. They were treated with PTH for 36 months. The women had been and were maintainedon hormone replacement therapy for the duration of PTH treatment. Patients were supplemented to obtainan average daily intake of 1500 mg of elemental calcium and 100 IU of vitamin D. The biopsy specimens weresubjected to routine histomorphometric analysis and microcomputed tomography (CT). Cancellous bone areawas maintained in both groups. Cortical width was maintained in men and significantly increased in women.There was no increase in cortical porosity. There was a significant increase in the width of bone packets onthe inner aspect of the cortex in both men and women. This was accompanied by a significant decrease ineroded perimeter on this surface in both groups. Micro-CT confirmed the foregoing changes and, in addition,revealed an increase in connectivity density, a three dimensional (3D) measure of trabecular connectivity inthe majority of patients. These findings indicate that daily PTH treatment exerts anabolic action on corticalbone in patients with osteoporosis and also can improve cancellous bone microarchitecture. The resultsprovide a structural basis for the recent demonstration that PTH treatment reduces the incidence ofosteoporosis-related fractures. (J Bone Miner Res 2001;16:1846–1853)

Key words: parathyroid hormone, osteoporosis, bone microarchitecture, human

INTRODUCTION

THE ANABOLIC action of parathyroid hormone (PTH) onthe mammalian skeleton was first appreciated in the late

1920s and early 1930s.(1,2) However, it took until the mid-

70s before the first clinical trials were conducted in bothmen and women with osteoporosis.(3–5) The 1990s sawfurther clinical trials of PTH alone and in combination withvarious antiresorptive treatments such as estrogen andcalcitonin.(6–9) Combined PTH and estrogen also was usedto treat glucocorticoid-induced osteoporosis.(10) Recently, asmall clinical trial(11) and a large multicenter trial(12) haveconfirmed the antifracture efficacy originally indicated in1997.(7)

*Presented in part at the VIIIth Congress of the InternationalSociety of Bone Morphometry, Scottsdale, Arizona, 1999, and atthe 22nd annual meeting of The American Society for Bone andMineral Research, Toronto, 2000.

1Regional Bone Center, Helen Hayes Hospital, New York State Department of Health, West Haverstraw, New York, USA.2Department of Pathology, College of Physicians and Surgeons of Columbia University, New York, New York, USA.3Clinical Research Center, Helen Hayes Hospital, New York State Department of Health, West Haverstraw, New York, USA.4Department of Medicine, College of Physicians and Surgeons of Columbia University, New York, New York, USA.5School of Public Health, College of Physicians and Surgeons of Columbia University, New York, New York, USA.6Orthopedic Biomechanics Laboratory, Harvard Medical School, and Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA.7Department of Pharmacology, College of Physicians and Surgeons of Columbia University, New York, New York, USA.

JOURNAL OF BONE AND MINERAL RESEARCHVolume 16, Number 10, 2001© 2001 American Society for Bone and Mineral Research

1846

Few clinical studies have used bone biopsy as an end-point; indeed, there have only been three studies in whichpaired biopsy specimens before and after PTH treatmenthave been analyzed.(4,13,14) These investigations yieldedvariable results in terms of the cancellous bone response.The first two studies(4,13) showed a significant increase incancellous bone volume but the latest study(14) did not.Furthermore, cortical bone variables were assessed only inone of the studies(14) and there have been no investigationsin which the three-dimensional (3D) structure of bone hasbeen assessed.

Therefore, the aim of this study was to perform both 2Dand 3D morphometric analysis of cancellous and corticalbone structure in paired biopsy specimens from patientswith osteoporosis treated with PTH.

MATERIALS AND METHODS

This study was approved by the Institutional ReviewBoards of Helen Hayes Hospital and Columbia-PresbyterianMedical Center. All subjects gave informed consent. Pairedbiopsy specimens before and after treatment were obtainedfrom two groups of patients. The first was a group of 8postmenopausal women with osteoporosis (average age, 54years) who were treated with 400 U/day of PTH(1–34) for36 months. These women had been and were maintained onhormone replacement therapy for the duration of the study.The characteristics of these patients have been providedelsewhere.(7) The second group consisted of 8 eugonadalmen with idiopathic osteoporosis (average age, 49 years)who were treated with the same regimen of PTH for 18months. The characteristics of these patients have beendescribed previously in full.(15,16)All patients were supple-mented, if necessary, to achieve a daily intake of 1500 mgof elemental calcium and 400 IU of vitamin D. Bone min-eral density (BMD) of the lumbar spine was measured bydual-energy X-ray absorptiometry as previously de-scribed.(7,15)

Before biopsy all patients were double-labeled with tet-racycline in a 3:12:3 day sequence. For the first biopsy,tetracycline hydrochloride was used to produce the firstlabel, and demethylchlortetracycline was used to producethe second label. The labels produced by each tetracyclinediffer in color under UV light. For the second biopsy, theorder of tetracyclines was reversed to aid distinction be-tween the two sets of labels. The biopsy specimens wereobtained, processed, and subjected to histomorphometricanalysis as previously described in detail from ourlaboratory.(17–21)All variables were expressed according tothe recommendations of the ASBMR nomenclature com-mittee.(22) The observer was blinded as to whether thebiopsy specimens were pre- or posttreatment, except fordynamic variables in which blinding was not possible. In-dices of bone structure were evaluated using Goldner-stained, 7-mm-thick sections. Before the measurements, thecancellous space was demarcated by well-established crite-ria.(23) Cancellous bone area, as a percentage of total can-cellous tissue area, trabecular number, trabecular width, andtrabecular separation, were derived from automated mea-

surement (Optomax V AMS system; Optomax, Inc., Hollis,NH, USA) of bone area and perimeter at 313 magnificationand defined as previously described.(22)

All static indices of remodeling activity were measuredon 7-mm-thick sections stained with Goldner’s trichrome.Unstained sections (20mm thick) were used to measuredynamic indices of bone formation. Perimeter indices wereexpressed as percentages of total trabecular perimeter andwere measured by the point counting method at 1253magnification. Mineral apposition rate was calculated fromthe semiautomated measurement of interlabel distance (Op-tomax VIDS V) and the interval in days between the twolabels. Bone formation rate was calculated according to thestandard formula(22) using the double- plus one-half of thesingle-labeled surface as the mineralizing perimeter and wasexpressed in cubic micrometers per square micrometer perday. Wall width of all completed trabecular and endocorti-cal bone packets in three to four sections per biopsy spec-imen was measured semiautomatically (VIDS IV; Op-tomax) at four equidistant points along the length of eachpacket at 1603 magnification.

After histomorphometric analysis, the embedded sampleswere analyzed by high-resolution microcomputed tomogra-phy (micro-CT) using amCT20 system (Scanco Medical,Bassersdorf, Switzerland) with a spatial resolution of 28mm. Eight pairs of biopsy specimens from the men wereavailable for micro-CT analysis; six pairs were available forthe women. The variables and method of analysis are de-scribed in full by Hildebrand et al.(24) The analytical methodused has advantages over previous techniques in that it doesnot make the assumptions of an underlying fixed plate orrod model of trabecular structure. Bone surface (BS) areawas calculated using the marching cubes method to trian-gulate the surface of the mineralized bone phase.(25) Bonevolume was calculated using tetrahedrons corresponding tothe enclosed volume of the triangulated surface.(26) Totalvolume (TV) was the volume of the sample that was exam-ined. To compare samples of varying size, normalized in-dices, BV/TV and BS/TV, were used. Trabecular thicknesswas determined by filling maximal spheres into the structurewith distance transformation(27) and then calculating theaverage thickness of all bone voxels. Trabecular separationwas calculated by the same procedure except the voxelsrepresenting nonbone tissue were filled with maximalspheres. Trabecular number was calculated as the inverse ofthe mean distance between the midaxes of the trabeculae.Connectivity density expresses the number of connectionsper cubic millimeter and was derived from the Euler num-ber(28) as follows: ConnD5 (1 2 Euler number)/TV. TheEuler number (x) is fundamental to all determinations ofconnectivity. In cancellous bone, it is defined as follows(29):x5b0 2 b1 1 b2, whereb0 is the number of bone particles(traditionally assumed to be 1);b1 is the connectivity, thatis, the maximum number of connections that must be brokento split the structure into two parts; andb2 is the number ofmarrow cavities fully surrounded by bone. Cortical thick-ness was expressed as the average thickness of the 3Dcortex using the same method as that for trabecular thick-ness. The cortical margins were defined by a semiautomatic

1847PTH IMPROVES HUMAN BONE MICROARCHITECTURE

contouring algorithm that locates the most probable edge ofthe inner and outer cortical surfaces.

Statistical analysis

Data are expressed as mean6 SEM for men and womenseparately. The significance of differences between meanvalues for variables before and after PTH treatment wasassessed using a pairedt-test. Regression analysis was per-formed using the method of least squares. All data analysiswas performed using PsiPlot (Polysoftware International,Pearl River, NY, USA) and Microsoft Excel Data Analysissoftware (Microsoft Corp., Redmond, WA, USA).

RESULTS

BMD and bone histomorphometry

Values for lumbar spine BMD and histomorphometricvariables before and after PTH treatment are given in Table1. The patients displayed an anabolic response to PTHtreatment as evidenced by a significant increase in lumbarspine BMD in both men and women. After PTH treatment,there was a trend toward an increase in eroded perimeter inboth men and women and in bone formation rate in women(Table 1). Cancellous bone area was maintained in womenand there was almost a significant increase in men (p 50.07). Consistent with the changes in cancellous bone area,

the wall width of trabecular packets was maintained inwomen and was significantly increased in men. Corticalwidth was slightly increased in men and was significantly(p , 0.02) increased in women. Cortical porosity wasunchanged.

Micro-CT

Analysis of cancellous bone structure in 3D by micro-CTrevealed maintenance of cancellous bone volume in womenand a trend toward an increase in men (Table 2). Theindividual responses are shown in Fig. 1. There also was astrong trend toward an increase in connectivity density, a3D index of trabecular connectivity, in both men andwomen (Table 2). Although there was some heterogeneityin individual responses, 75% of the men and 66% of thewomen showed maintenance or improvement, by 12–253%in connectivity density (Fig. 1).

Consistent with the results from the 2D analysis, corticalthickness was slightly increased in men and was signifi-cantly (p , 0.01) increased in women (Table 2). Althoughcortical thickness was maintained or improved (.15%) in 6of the 8 men, 2 men showed a decrease; however, all of thewomen showed an increase (Fig. 1). Figure 2 shows imagesof bone structure from 1 woman and 1 man before and afterPTH treatment. Note the improvement in trabecular archi-

TABLE 1. BMD AND BONE HISTOMORPHOMETRYVARIABLES IN PATIENTS BEFORE AND AFTER PTH TREATMENT

Men Women

Before After Before After

BMD L2–L4 (g/cm2) 0.7576 0.021 0.8316 0.053* 0.7246 0.023 0.8106 0.025‡

Cancellous bone area (%) 13.656 1.78 17.736 0.99 14.016 1.96 13.346 2.05Cancellous wall width (mm) 35.486 1.75 39.256 1.94† 37.766 1.01 38.666 1.47Cortical width (mm) 7226 48 8186 60 6326 95 9516 130†

Cortical porosity (%) 7.706 1.07 7.886 1.29 7.216 1.43 6.396 0.89Trabecular number (per mm) 1.336 0.12 1.566 0.08 1.326 0.18 1.196 0.16Trabecular separation (mm) 7166 106 5296 26 7316 101 8136 113Trabecular thickness (mm) 1046 11 1196 8 1066 5 1146 10Eroded perimeter (%) 3.816 0.34 5.696 1.33 4.696 0.70 5.696 1.50Bone formation rate (mm2/mm per day) 0.0476 0.01 0.0466 0.01 0.0456 0.01 0.0586 0.02

*p , 0.05, †p , 0.02, and‡p , 0.001 fordifference between before and after by pairedt-test.

TABLE 2. STRUCTURAL VARIABLES OBTAINED BY MICRO-CT IN PATIENTS BEFORE AND AFTER PTH TREATMENT

Men Women

Before After Before After

Cancellous bone volume (%) 22.546 2.47 26.036 0.74 21.286 3.52 22.396 3.09Trabecular number (per mm) 1.256 0.06 1.336 0.06 1.336 0.10 1.316 0.13Trabecular separation (mm) 7636 39 7136 34 7316 57 7486 73Trabecular thickness (mm) 1966 15 2086 9 1796 9 1976 13Connectivity density (per mm) 3.606 0.39 4.356 0.37 3.286 0.69 4.646 0.81Cortical thickness (mm) 6126 60 6436 37 4206 104 7716 113*

*p , 0.01 for difference between before and after by pairedt-test.

1848 DEMPSTER ET AL.

tecture and increase in cortical thickness after PTH treat-ment.

Subperiosteal and endocortical surfaces

To investigate the mechanism underlying the anaboliceffect on cortical bone, we analyzed dynamic indices ofbone formation on the subperiosteal (outer) and endocorti-cal (inner) surfaces as well as the eroded perimeter and wallwidth of bone packets on the endocortical surface. The lattermeasurement could not be performed on the periostealsurface because packets could not be identified reliably atthat site. There were no significant changes in dynamicindices of bone formation on either the subperiosteal or theendocortical surface (data not shown). However, on theendocortical surface there was a significant increase in wallwidth of the packets and a significant decrease in erodedperimeter (Figs. 3 and 4).

DISCUSSION

This study has provided two novel observations regardingthe mechanism of action of daily PTH treatment in patients

with osteoporosis. First, we obtained evidence that PTHexerts anabolic action on human cortical bone with noincrease in cortical porosity. Second, we observed an in-crease in 3D trabecular connectivity in the majority ofpatients.

For many years it has been held that the anabolic actionof PTH occurs predominantly in cancellous bone and therestill is a concern that PTH treatment may have a deleteriouseffect on cortical bone.(30) On the contrary, this study indi-cates that PTH has an anabolic effect on human corticalbone, at least in the axial skeleton. Indeed, we observed agreater anabolic effect on cortical bone than on cancellousbone. An increase in cortical thickness would be predictedto contribute substantially to bone strength,(31–33) even atskeletal sites such as the vertebra where cancellous bonetraditionally has been thought to play the dominant role indetermining strength.

The anabolic action on cortical bone is consistent withprevious studies in animals, including rats,(34–36)rabbits,(37)

and dogs.(38) In animals, PTH stimulates bone formation onboth the periosteal and the endosteal surfaces.(34–38) In thisstudy we obtained evidence for an anabolic effect on theendosteal surface, where we observed an increase in thepacket wall width. Greater PTH-induced stimulation ofbone formation on the endosteal than the periosteal surfaceof the cortex has been observed in some animal stud-ies.(36,39,40)Our finding that PTH exerts anabolic action onthe endosteal surface of cortical bone in humans also isconsistent with a recent preliminary report by Cann et al.(41)

who used 3D quantitative CT in vivo to examine envelope-specific responses to PTH in the femur.

The positive effect of increased endocortical wall widthon cortical thickness may have been enhanced by a reduc-tion in resorption on that surface because we observed amarked decrease in eroded perimeter. This is a surprisingobservation because we might have expected PTH to in-crease the eroded perimeter secondary to an increase inactivation frequency. This is what is seen in cancellousbone.(4,14) However, there are some data in the literature tosupport our observation. In aged rats, osteoclast perimeteron the endocortical surface of the vertebral body was nor-mal during PTH administration and increased dramaticallyafter PTH withdrawal.(36) In adult beagles, Zhang et al.(42)

noted that PTH treatment increased the number of cortex tonode trabecular struts, most likely because of reduced re-sorption on the endocortical surface.

We observed an increase in endocortical wall width inboth the men and the women, but a statistically significantincrease in cortical thickness was seen only in the women.There are several plausible explanations for this. First, thewomen were treated twice as long as the men. It is possiblethat with longer treatment the increase in endocortical wallwidth would result in an increase in cortical width. Bonedensity measurements indicated that men in whom PTHtreatment was continued after 18 months continued to gainbone mass at the hip.(43) Second, the women were treatedwith a combination of PTH and estrogen and there may beadditive effects of the two agents. Previously, this has beenindicated in animal studies and there are some data tosuggest it also may be true in humans.(44)

FIG. 1. Percentage changes in three variables of iliac bone structureafter PTH treatment. All variables were measured by micro-CT.

1849PTH IMPROVES HUMAN BONE MICROARCHITECTURE

With the use of micro-CT, we observed an increase in theconnectivity density of cancellous bone in the majority ofpatients after PTH treatment. The contribution of this 3Dindex of trabecular connectivity to bone strength is, as yet,unclear. There are few data available for humans and almostnone in patients with osteoporosis. As far as we are aware,this is the first study in which 3D connectivity has been

measured before and after treatment of patients with osteo-porosis. Based on measurements of normal cancellous bone,Kabel et al.(45) concluded that connectivity density contrib-uted little to its mechanical properties but conceded that thismay not be the case in disease states. Inclusion of connec-tivity density with bone volume in a regression analysissignificantly improved the prediction of vertebral bone

FIG. 2. (A) Paired biopsy spec-imens from a 64-year-old womanand (B) a 47-year-old man beforeand after treatment with PTH. Allbiopsy specimens are shown atthe same magnification. In thewoman, cortical thickness in-creased from 320 to 420mm aftertreatment and connectivity den-sity increased from 2.9 to 4.6/mm3. In the man, cortical thick-ness increased from 600 to 700mm after treatment and connec-tivity density increased from 2.1to 3.8/mm3.

FIG. 3. Wall width of (A) packets and (B)eroded perimeter on the endocortical surface be-fore and after PTH treatment.

1850 DEMPSTER ET AL.

strength.(46) Moreover, Kinney and Ladd(47) concluded thatrecovery of mechanical function in patients with osteopo-rosis is dependent on preservation or restoration of trabec-ular connectivity. Increases in trabecular connectivity afterPTH treatmenthave been shown previously in ani-mals,(48,49)and also patientswith mild primary hyperpara-thyroidism display greater trabecular connectivity than age-and sex-matched controls.(19,50,51)

The mechanism underlying the increase in connectivitydensity in this study is unclear. There were modest improve-ments in trabecular number in men and in trabecular thick-ness in both men and women. Therefore, it is possible thattrabecular elements that were separated by short distancesbecame connected or reconnected. Another possibility is anincrease in trabecular perforation(52) or intratrabecular tun-neling, which would result in an increase in the number ofconnections in 3D space. Intratrabecular tunneling has beenreported previously in monkeys treated with daily PTHinjections.(53)

Cancellous bone area and volume were not significantlyincreased after PTH treatment. This is consistent with the

most recent paired biopsy study(14) but differs from earlierstudies(4,13) in which a substantial increase in cancellousbone area was observed. The current observation and that ofHodsman et al.(14) also seem inconsistent with the estab-lished increments in spinal BMD. A likely explanation is thehigh intraindividual variability in cancellous bone area atthe iliac crest,(54) which makes it difficult to show statisti-cally significant differences with small sample sizes. How-ever, it also should be noted that several studies in intact,large animals (dogs and rabbits) have not shown increasesin cancellous bone area in the iliac crest and lumbar spineafter PTH treatment.(37,38,41) In one of the studies, an in-crease in cortical bone area occurred in the absence of anincrease in cancellous bone area.(37) It also is possible thatpart of the increase in spinal BMD in humans treated withPTH is caused by an increase in the thickness of the corticalshell. Cosman et al.(55) previously reported that in patientswith osteoporosis, cortical width in the bone biopsy speci-men was the best predictor of spinal BMD.

In conclusion, this paired biopsy study indicates that dailytreatment with PTH exerts anabolic action on both cortical

FIG. 4. A bone packet on the endocortex of a52-year-old man (A) before treatment and (B)after treatment. The section in panel B happensto be stained more intensely than that in panel Aand therefore appears darker. The dashed linesdemarcate the reversal lines. The packet in theposttreatment biopsy specimen is more thantwice as wide as that in the pretreatment biopsyspecimen. Measurement of all packets revealedan average increase in wall width of 58% in thispatient (original magnification313).

1851PTH IMPROVES HUMAN BONE MICROARCHITECTURE

and cancellous bone in the human iliac crest. Cortical po-rosity was unchanged and there was an increase in 3Dtrabecular connectivity in most patients. Although limitedby the small sample size, the data suggest that PTH is notonly capable of increasing bone mass in patients with os-teoporosis but also of correcting the microarchitectural de-fects in cortical and cancellous bone that increase skeletalfragility. If confirmed in larger studies, these findings wouldprovide an explanation at a structural level for the recentdemonstration that PTH treatment for only 18 months re-duces the incidence of spine and nonspine fractures inpatients with osteoporosis.(12)

ACKNOWLEDGMENTS

We thank Rhoˆne-Poulenc (now Aventis Pharma, Bridge-water, NJ, USA) for supplying synthetic PTH(1–34). Thiswork was supported by the National Institutes of Health(NIH) grants AR 39191, DK 42892, and DK 4631, the Foodand Drug and Administration (FDA) grant FD-R001024,and Biomeasure Inc. (Milford, MA, USA).

REFERENCES

1. Bauer W, Aub JC, Albright F 1929 Studies of calcium phos-phorus metabolism. V. A study of the bone trabeculae as areadily available reserve supply of calcium. J Exp Med49:145–162.

2. Selye H 1932 On the stimulation of new bone formation withparathyroid extract and irradiated ergosterol. Endocrinology16:547.

3. Reeve J, Tregear GW, Parsons JA 1976 Preliminary trial oflow doses of human parathyroid 1-34 peptide in treatment ofosteoporosis. Clin Endocrinol (Oxf)21:469.

4. Reeve J, Meunier PJ, Parsons JA, Bernat M, Bijvoet OLM,Courpron P, Edouard C, Lenerman L, Neer RM, Renier JC,Slovik D, Vismans FJFE, Potts JT 1980 Anabolic effect of humanparathyroid hormone fragment on trabecular bone in involutionalosteoporosis: A multicentre trial. BMJ280:1340–1344.

5. Slovik DM, Rosenthal DI, Doppelt S, Potts JTJ, Daly MA,Campbell JA, Neer RM 1986 Restoration of spinal bone inosteoporotic men by treatment with human parathyroid hor-mone (1-84) and 1,25 dihydroxyvitamin D. J Bone Miner Res1:377.

6. Finkelstein J, JS, Klibanski A, Schaefer EH, Hornstein MD,Schiff I, Neer RM 1994 Parathyroid hormone for the preven-tion of bone loss induced by estrogen deficiency. N Engl J Med331:1618.

7. Lindsay R, Nieves J, Formica C, Henneman E, Woelfert L,Shen V, Dempster D, Cosman F 1997 Randomized controlledstudy of effect of parathyroid hormone on vertebral-bone massand fracture incidence among postmenopausal women on oes-trogen with osteoporosis. Lancet350:550–555.

8. Hodsman AB, Fraher LJ, Watson PH, Ostbye T, Stitt LW,Adachi JD, Taves DH, Drost D 1997 A randomized controlledtrial to compare the efficacy of cyclical parathyroid hormoneversus cyclical parathyroid hormone and sequential calcitoninto improve bone mass in post-menopausal women with osteo-porosis. J Clin Endocrinol Metab82:620.

9. Roe EB, Sanchez SD, del Puerto A, Bachetti P, Cann CE,Arnaud CD 1999 Parathyroid hormone 1-34 (hPTH 1-34) andestrogen produce dramatic bone density increases in post-menopausal osteoporosis—results from a placebo-controlledrandomized trial. J Bone Miner Res14:S1;S137 (abstract).

10. Lane NE, Sanchez S, Modin GW, Genant HK, Ini E, ArnaudCD 1998 Parathyroid hormone can reverse corticosteroid-induced osteoporosis. Results of a randomized controlled clin-ical trial. J Clin Invest102:1627–1633.

11. Cosman F, Nieves J, Formica C, Woelfert L, Shen V, LindsayR 2000 Parathyroid hormone in combination with estrogendramatically reduces vertebral fracture risk. Osteopor Int11(Suppl 2):S176 (abstract).

12. Neer RM, Arnaud CD, Zanchetta JR, Prince R, Gaich G,Reginster J-Y, Hodsman AB, Eriksen EF, Ish-Shalom, GenantHK, Wang O, Mitlak BH 2001 Effect of parathyroid hormone(1-34) on fractures and bone mineral density in postmeno-pausal women with osteoporosis. N Engl J Med344:1434–1441.

13. Bradbeer JN, Arlot ME, Meunier PJ, Reeve J 1992 Treatmentof osteoporosis with parathyroid peptide (h-PTH 1-34) andoestrogen: Increase in volumetric density of iliac cancellousbone may depend on reduced trabecular spacing as well asincreased thickness of packets of newly formed bone. ClinEndocrinol (Oxf)37:282–289.

14. Hodsman AB, Kisiel M, Adachi JD, Fraher LJ, Watson PH2000 Histomorphometric evidence of increased bone turnoverwithout change in cortical thickness or porosity after 2 years ofcyclical hPTH(1-34) therapy in women with severe osteopo-rosis Bone27:311–318.

15. Kurland ES, Rosen CJ, Cosman F, McMahon D, Chan F,Shane E, Lindsay R, Dempster D, Bilezikian JP 1997 Insulin-like growth factor-I in men with idiopathic osteoporosis. J ClinEndocrinol Metab82:2799–2805.

16. Kurland ES, Cosman F, McMahon DJ, Rosen CJ, Lindsay R,Bilezikian JP 2000 Parathyroid hormone as a therapy foridiopathic osteoporosis in men: Effects on bone mineral den-sity and bone markers. J Clin Endocrinol Metab85:3069–3076.

17. Dempster DW, Shane ES 1995 Bone quantification and dy-namics of bone turnover by histomorphometric analysis. In:Becker KL (ed.) Principles and Practice of Endocrinology andMetabolism, 2nd ed. JB Lippincott Co., Philadelphia, PA,USA, pp. 491–498.

18. Parisien M, Silverberg SJ, Shane E, De La Cruz L, Lindsay R,Bilezikian J, Dempster DW 1990 The histomorphometry ofbone in primary hyperparathyroidism: Preservation of cancel-lous bone structure. J Clin Endocrinol Metab70:930–938.

19. Parisien M, Cosman F, Mellish RWE, Schnitzer M, Nieves J,Silverberg SJ, Shane E, Kimmel D, Recker RR, Bilezikian JP,Dempster DW 1995 Bone structure in postmenopausal hyper-parathyroid, osteoporotic and normal women. J Bone MinerRes10:1393–1399.

20. Parisien MP, Cosman F, Morgan D, Schnitzer M, Liang X,Nieves J, Forese L, Luckey M, Meier D, Shen V, Lindsay R,Dempster DW 1997 Histomorphometric assessment of bonemass, structure, and remodeling: A comparison betweenhealthy black and white premenopausal women. J Bone MinerRes12:948–957.

21. Dempster DW, Parisien M, Silverberg SJ, Liang X-G,Schnitzer M, Shen V, Shane E, Kimmel DB, Recker R, Lind-say R, Bilezikian JP 1999 On the mechanism of cancellousbone preservation in postmenopausal women with mild pri-mary hyperparathyroidism. J Clin Endocrinol Metab84:1562–1566.

22. Parfitt AM, Drezner HK, Glorieux FH, Kanis JA, Malluche H,Meunier PJ, Ott SM, Recker RR 1987 Bone histomorphom-etry: Standardization of nomenclature, symbols, and units.J Bone Miner Res2:595–610.

23. Courpron P, Meunier PJ, Bressot C, Giroux JM 1976 Amountof bone in iliac crest biopsy: Significance of the trabecularbone volume. Its values in normal and in pathological condi-tions. In: Meunier PJ (ed.) Proceedings of Bone Histomor-

1852 DEMPSTER ET AL.

phometry. Second International Workshop, Lyon. Societe de laNouvelle Imprimerie Fournie, Toulouse, pp. 39–53.

24. Hildebrand T, Laib A, Mu¨ller R, Dequeker J, Ru¨egsegger P1999 Direct three-dimensional morphometric analysis of hu-man cancellous bone: Microstructural data from spine, femur,iliac crest and calcaneous. J Bone Miner Res14:1167–1174.

25. Lorensen WE, Cline HE 1987 Marching cubes: A high reso-lution 3D surface construction algorithm. Comput Graph21:163–169.

26. Guilak F 1994 Volume and surface area of viable chondro-cytes in situ using geometric modelling of serial confocalsections. J Microsc173:245–256.

27. Hildebrand T, Ru¨egsegger P 1997 A new method for themodel independent assessment of thickness in three-dimensional images. J Microsc185:67–75.

28. Odgaard A, Gundersen HJ 1993 Quantification of connectivityin cancellous bone, with special emphasis on 3-D reconstruc-tions. Bone14:173–182.

29. Odgaard A 1997 Three dimensional methods for quantificationof cancellous bone architecture. Bone20:315–328.

30. Horwitz M, Stewart A, Greenspan SL 2000 Editorial: Sequentialparathyroid hormone/alendronate therapy for osteoporosis—robbing Peter to pay Paul? J Clin Endocrinol Metab85:2127–2128.

31. Vesterby A, Mosekilde L, Gundersen HJG, Melsen F,Mosekilde L, Holme K, Sorenesen S 1991 Biologically mean-ingful determinants of the in vitro strength of lumbar verte-brae. Bone12:219–224.

32. Ritzel H, Amling M, Posl M, Hahn M, Delling G 1997 Thethickness of human vertebral cortical bone and its changes inaging and osteoporosis: A histomorphometric analysis of thecomplete spinal column from thirty-seven autopsy specimens.J Bone Miner Res12:89–95.

33. Oleksik A, Ott SM, Vedi S, Bravenboer N, Compston J, LipsP 2000 Bone structure in patients with low bone mineraldensity with or without vertebral fractures. J Bone Miner Res15:1368–1375.

34. Oxlund H, Ejersted C, Andreassen T, Torring O, Nilsson MHL1993 Parathyroid hormone (1-34) and (1-84) stimulate corticalbone formation both from periosteum and endosteum. CalcifTissue Int53:394–399.

35. Wronski TJ, Yen C-F 1994 Anabolic effects of parathyroid hor-mone on cortical bone in ovariectomized rats. Bone15:51–58.

36. Ejersted C, Oxlund H, Eriksen EF, Andreassen TT 1998 With-drawal of parathyroid hormone treatment causes rapid resorp-tion of newly formed vertebral cancellous and endocorticalbone in old rats. Bone23:43–52.

37. Hirano T, Burr DB, Turner CH, Sato M, Cain RL, Hock JM 1999Anabolic effects of human biosynthetic parathyroid fragment(1-34), LY333334, on remodeling and mechanical properties ofcortical bone in rabbits. J Bone Miner Res14:536–545.

38. Boyce RW, Paddock CL, Franks AF, Jankowsky ML, EriksenEF 1996 Effects of intermittent hPTH(1-34) alone and incombination with 1,25(OH)2D3 or risedronate on endostealbone remodeling in canine cancellous and cortical bone.J Bone Miner Res11:600–613.

39. Cain RL, Zeng QQ, Rowley ER, Cole HW, Bryant H, Sato M,Ma YL 2000 PTH augments similar cortical bone in ratsregardless of ovarian status—a histomorphometric analysisJ Bone Miner Res 15:S1;S441 (abstract).

40. Mohan S, Kutilek S, Zhang C, Shen HG, Kodama Y,Srivistava AK, Wergedal JE, Beamer WG, Baylink DJ 2000Comparison of bone formation responses to parathyroid hor-mone (1-34), (1-31), and (2-34) in mice. Bone27:471–478.

41. Cann CE, Roe EB, Sanchez SD, Arnaud CD 1999 PTH effectsin the femur: Envelope-specific responses by 3D-QCT in post-menopausal women. J Bone Miner Res 14:S1;S137 (abstract).

42. Zhang L, Takahashi HE, Inoue J, Tanizawa T, Endo N,Yamamoto N, Hori M 1997 Effects of intermittent adminis-

tration of low dose human PTH (1-34) on cancellous andcortical bone of lumbar vertebral bodies in adult beagles. Bone21:501–506.

43. Kurland ES, Cosman F, Rosen CJ, Lindsay R, Bilezikian JP2000 Parathyroid hormone (PTH 1-34) as a treatment foridiopathic osteoporosis in men: Changes in bone mineral den-sity, bone markers, and optimal duration of therapy. J BoneMiner Res 15:S1;S230 (abstract).

44. Cosman F, Lindsay R 1998 Is parathyroid hormone a thera-peutic option for osteoporosis? A review of the clinical evi-dence. Calcif Tissue Int62:475–480.

45. Kabel J, Odgaard A, van Rietbergen B, Huiskes R 1999Connectivity and the elastic properties of cancellous bone.Bone24:115–120.

46. Borah B, Dufresne TE, Cockman MD, Gross GL, Sod EW,Myers WR, Combs KS, Higgins RE, Pierce SA, Stevens ML2000 Evaluation of changes in trabecular bone architecture andmechanical properties of minipig vertebrae by three-dimensional magnetic resonance microimaging and finite ele-ment modeling. J Bone Miner Res15:1786–1797.

47. Kinney JH, Ladd AJC 1998 The relationship between three-dimensional connectivity and the elastic properties of trabec-ular bone. J Bone Miner Res13:839–845.

48. Shen V, Dempster DW, Birchman R, Xu R, Lindsay R 1993Loss of cancellous bone mass and connectivity in ovariecto-mized rats can be restored by combined treatment with para-thyroid hormone and estradiol. J Clin Invest91:2479–2487.

49. Sato M, Zeng GQ, Turner CH 1997 Biosynthetic humanparathyroid hormone (1-34) effects on bone quality in agedovariectomized rats. Endocrinology138:4330–4337.

50. Parisien MV, Mellish RWE, Silverberg SJ, Shane E, LindsayR, Bilezikian JP, Dempster DW 1992 Maintenance of cancel-lous bone connectivity in primary hyperparathyroidism: Tra-becular strut analysis. J Bone Miner Res7:913–919.

51. Vogel M, Hahn M, Delling G 1995 Trabecular structure inpatients with primary hyperparathyroidism. Virchows Arch426:127–134.

52. Boyce RW, Wronski TJ, Ebert DC, Stevens ML, Paddock CL,Youngs TA, Gundersen HJG 1995 Direct stereological esti-mation of three-dimensional connectivity in rat vertebrae: Ef-fects of estrogen, etidronate and risedronate following ovari-ectomy. Bone16:209–213.

53. Jerome CP, Burr DB, Van Bibber T, Brommage R 2001Treatment with human parathyroid hormone (1-34) for 18months increases cancellous bone volume and improves tra-becular architecture in ovariectomized cynomolgus monkeys(Macaca fascicularis). Bone28:150–159.

54. Parisien MV, McMahon D, Pushparaj N, Dempster DW 1988Trabecular architecture in iliac crest bone biopsies: Intra-individual variability in structural parameters and changeswith age. Bone9:289–295.

55. Cosman F, Schnitzer MB, McCann PD, Parisien MV, Demp-ster DW, Lindsay R 1992 Relationships between quantitativehistological measurements and non-invasive assessments ofbone mass. Bone13:237–242.

Address reprint requests to:David W. Dempster, Ph.D.

Regional Bone CenterHelen Hayes Hospital

Route 9 WestWest Haverstraw, NY 10993, USA

Received in original form January 10, 2001; in revised form April9, 2001; accepted April 18, 2001.

1853PTH IMPROVES HUMAN BONE MICROARCHITECTURE