Changes in mean trabecular orientation in the medial condyle of the proximal tibia in osteoarthritis

In osteoarthritis of the knee, degenerative changes occur in the articular cartilage and underlying subchondral bone, particularly of the medial tibial condyle. Cancellous bone sclerosis that accompanies osteoarthritis is not only the result of an increase in bone volume fraction but also a change in trabecular structure. In a comparison with agematched controls (n=4), osteoarthritis (n=11) demonstrated a significant (P0.05) increase in bone volume fraction and trabecular thickness. Overal trabecular orientation in the osteoarthritic group was more vertical or perpendicular to the articular surface than the control group (P0.05) especially in the trabeculae of the cancellous bone layer closest to the articular surface. These alterations in trabecular bone structure could have significant consequences for the mechanical properties of osteoarthritic bone.     

Cortical and trabecular bone adaptation to incremental load magnitudes using the mouse tibial axial compression loading model

The mouse tibial axial compression loading model has recently been described to allow simultaneous exploration of cortical and trabecular bone adaptation within the same loaded element. However, the model frequently induces cortical woven bone formation and has produced inconsistent results with regards to trabecular bone adaptation. The aim of this study was to investigate bone adaptation to incremental load magnitudes using the mouse tibial axial compression loading model, with the ultimate goal of revealing a load that simultaneously induced lamellar cortical and trabecular bone adaptation. Adult (16 weeks old) female C57BL/6 mice were randomly divided into three load magnitude groups (5, 7 and 9 N), and had their right tibia axially loaded using a continuous 2-Hz haversine waveform for 360 cycles/day, 3 days/week for 4 consecutive weeks. In vivo peripheral quantitative computed tomography was used to longitudinally assess midshaft tibia cortical bone adaptation, while ex vivo micro-computed tomography and histomorphometry were used to assess both midshaft tibia cortical and proximal tibia trabecular bone adaptation. A dose response to loading magnitude was observed within cortical bone, with increasing load magnitude inducing increasing levels of lamellar cortical bone adaptation within the upper two thirds of the tibial diaphysis. Greatest cortical bone adaptation was observed at the midshaft where there was a 42% increase in estimated mechanical properties (polar moment of inertia) in the highest (9 N) load group. A dose response to load magnitude was not clearly evident within trabecular bone, with only the highest load (9 N) being able to induce measureable adaptation (31% increase in trabecular bone volume fraction at the proximal tibia). The ultimate finding was that a load of 9 N (engendering a tensile strain of 1833 με on medial surface of the midshaft tibia) was able to simultaneously induce measurable lamellar cortical and trabecular bone adaptation when using the mouse tibial axial compression loading model in 16 week old female C57BL/6 mice. This finding will help plan future studies aimed at exploring simultaneous lamellar cortical and trabecular bone adaptation within the same loaded element.     

A decreased subchondral trabecular bone tissue elastic modulus is associated with pre-arthritic cartilage damage.

In osteoarthritis, one postulate is that changes in the mechanical properties of the subchondral bone layer result in cartilage damage. The goal of this study was to examine changes in subchondral trabecular bone properties at the calcified tissue level in the early stages of cartilage damage. Finite element models were constructed from microCT scans of trabectilar bone from the proximal tibia of donors with mild cartilage damage and from normal donors. In the donors with cartilage damage, macroscopic damage was present only in the medial compartment. The effective tissue elastic moduli were determined using a combination of finite element models and mechanical testing. The bone tissue modulus was reduced by 60% in the medial condyle of the cases with cartilage damage compared to the control specimens. Neither the presence of cartilage damage nor the anatomic site (medial vs. lateral) affected the elastic modulus at the apparent level. The volume fraction of trabecular bone was higher in the medial compartment compared to the lateral compartment of tibiae with cartilage damage (but not the controls), suggesting that mechanical properties were preserved in part at the apparent level by an increase in the bone volume fraction. It seems likely that the normal equilibrium between cartilage properties, bone tissue properties and bone volume fraction is disrupted early in the development of osteoarthritis.     

Trabecular bone strain changes associated with subchondral bone defects of the tibial plateau

OBJECTIVE: To measure trabecular bone strain changes resulting from three increasing subchondral bone defects in the medial tibial plateau. DESIGN: Cadaveric biomechanical model. SETTING: Contact radiographs were made from coronal sections of human cadaveric proximal tibia under no load and loaded to 400 newtons (N). Digital images made from contact radiographs of unloaded specimens were compared to corresponding digital images of loaded specimens using in-house software that detects trabecular deformation and measure trabecular bone strain. INTERVENTION: Ten specimens were loaded intact and with three increasing circular subchondral bone defects and centered under the subchondral plates in the medial tibial plateau that were 10%, 20%, and 30% of the coronal width of the medial plateau. MAIN OUTCOME MEASURE: Maximum shear strain and minimum principal strain were measured at approximately 2,600 discrete points in the trabecular bone in the medial tibial plateau. RESULTS: Trabecular strain increased most dramatically as defects increased from the medium (20%) to the large (30%) defect. The regions of greatest strain elevation were between the physeal scar and joint line near the medial cortex. Small (10%) and medium (20%) defects resulted in modest strain elevations. CONCLUSIONS: Subchondral defects cause size-dependent elevations in trabecular bone strain in the medial tibial plateau. A size threshold may exist, above which the trabecular bone is subjected to rapidly increasing deformation under load.     

Indentation stiffness of the cancellous bone in the distal human tibia

Total ankle arthroplasties tend to fail mainly on the tibial side. Fifteen fresh amputation specimens were used for assessment of the stiffness of the cancellous bone in the distal tibia. Because all current ankle replacements sacrifice the subchondral bone plate, the change in stiffness of cancellous bone was studied in transverse sections taken proximal to the subchondral plate of the ankle. The articular cartilage was removed from the tibial plafond, and serial 1-cm sections were taken, radiographed, and tested in compression on an Instron 1125 Universal Testing machine with the use of a 4-mm-diameter indentor. In the distal tibia, it was found that subchondral bone has an elastic modulus on the order of 300-450 MPa; removal of the subchondral bone plate reveals bone with a compressive resistance that is 30%-50% lower than with the bone plate intact; there is virtually no resistance to compression in the trabecular bone at a distance of more than 3 cm proximal to the subchondral bone plate; and stiffness characteristics in the distal tibia parallel the radiographic appearance of the trabeculae. The strongest cancellous bone in the region of the distal tibia is that near the subchondral bone plate. This material should be preserved, if possible, in the surgery for total ankle implants.     

Late changes in bone mineral density of the proximal tibia following total or partial medial meniscectomy: A randomized study

The adaptive bone remodeling in the proximal tibia following medial meniscectomy was measured quantitatively by dual photon absorptiometry. Thirty-three patients who had undergone a meniscectomy (randomized to either total [n = 19] or partial [n = 14] meniscectomy) performed by open joint surgery approximately 12 years earlier were included in the study. Bone mineral density was measured in the previously injured legs and in the healthy contralateral legs in areas located medially and laterally in the cortical bone of the subchondral plates and below in the trabecular bone of the medial and lateral tibial condyles. The distribution of bone mineral within the proximal tibia showed a characteristic and significant pattern. In the trabecular bone of the healthy contralateral knees, bone mineral density was 15% higher in the medial tibial condyles compared with the values laterally: a total or partial meniscectomy increased this difference to 25%. With regard to the cortical bone of the subchondral plates, the bone mineral density in the healthy knees was 24.8–29.4% higher medially than laterally, whereas after total and partial meniscectomy the differences were, respectively, 37.7 and 41.4%. No significant differences in the distribution of bone mineral density, at either cortical or trabecular measuring sites, were found between totally and partially meniscectomized knees.     

Trabecular bone strain changes associated with cartilage defects in the proximal and distal tibia.

Intraarticular fractures with cartilage defects can lead to post-traumatic arthritis (PTA). The purpose of this study was to determine how cartilage defects affect load transmission through subchondral trabecular bone in human cadaveric knees and ankles to further understand the pathomechanics of PTA. We created full-thickness cartilage defects in the meniscectomized proximal tibia and distal tibia and measured changes in trabecular bone strain using Texture Correlation. Texture Correlation compares high quality digital images made from contact radiographs of unloaded samples to images of the same sample under load to measure trabecular bone strain. Cartilage defects caused trabecular bone strain to decrease in the proximal tibia and increase in the distal tibia. The column of bone directly beneath the defect in the tibial plateau had the most significant reduction in strain. In the distal tibia, strain near the jointline and in the anterior third had the most significant increases in strain. The distal tibia had greater strain changes with small defects. The clinical course of intraarticular fractures of the proximal and distal tibia are markedly different. We postulate that disturbances in load transmission through the subchondral bone caused by cartilage defects may be important mechanical determinants of PTA.     

Evaluation of orthogonal mechanical properties and density of human trabecular bone from the major metaphyseal regions with materials testing and computed tomography

We evaluated the orthogonal mechanical properties of human trabecular bone from the major metaphyseal regions with materials testing and quantitative computed tomography (CT). The proximal tibia, distal femur, proximal femur, distal radius, and proximal humerus from fresh cadaver specimens between the ages of 55 and 70 years were excised and prepared for experimentation. The bones were embedded and scanned at 1 or 1.5 mm intervals on a Technicare HPS 1440 and GE 9800 CT scanner. After scanning, the bones were sectioned, producing 8-mm cubes of trabecular bone which were mechanically tested in uniaxial compression at a strain rate of 1%. The testing sequence consisted of preyield tests in two of the three orthogonal directions and failure in the third. After testing, the cubes were evaluated for apparent density and ash weight. The results of the study show that the strength and stiffness of trabecular bone varies significantly within metaphyseal regions and from metaphysis to metaphysis. The power and significance of relationships between density and modulus varied as a function of metaphyseal location. Both linear and nonlinear models were significant, suggesting that trabecular deformation occurs in response to both axial and bending loads. Finally, the need for architectural measures of trabecular bone to predict mechanical properties is emphasized.     

The Subchondral Bone of the Proximal Tibial Epiphysis in Osteoarthritis of the Knee

The trabecular bone of the proximal end of the tibia was assessed as an endoprosthesis-bearing structure. The mass and mineral content as well as the activity of subchondral trabecular bone were determined in osteoarthritic knees with varus or valgus deformity.

Bone specimens were taken from the lateral condyle, the medial condyle, and centrally from the intercondylar area of seven varus and four valgus knees. The percentage volume of trabecular bone was determined by histomorphometry. On an additional nine knees, five with varus and four with valgus deformity, as well as ten knees from a normal autopsy material, photon absorptiometric determination of the mineral content of the same areas was performed. On average, the loaded condyle had twice the percentage volume of trabecular bone, and accordingly twice the mineral content, of the unloaded condyle. It was remarkable that the mineral content of the latter was of the same order as the condyles of the normal material.     

Trabecular Bone Score at the Distal Femur and Proximal Tibia in Individuals With Spinal Cord Injury

Rapid declines in bone mineral density (BMD) at the knee after spinal cord injury (SCI) are associated with an increased risk of fracture. Evaluation of bone quality using the trabecular bone score (TBS) may provide a complimentary measure to BMD assessment to examine bone health and fracture risk after SCI. The purpose of this study was to assess bone mineral density (BMD) and trabecular bone score (TBS) at the knee in individuals with and without SCI. Nine individuals with complete SCI (mean time since SCI 2.9?±?3.8?yr) and 9 non-SCI controls received dual-energy X-ray absorptiometry scans of the right knee using the lumbar spine protocol. BMD and TBS were quantified at epiphyseal, metaphyseal, diaphyseal, and total bone regions of the distal femur and proximal tibia. Individuals with SCI illustrated significantly lower total BMD at the distal femur (23%; p?=?0.029) and proximal tibia (19%; p?=?0.02) when compared with non-SCI controls. Despite these marked differences in BMD from both locations, significant differences in total TBS were observed at the distal femur only (6%; p?=?0.023). The observed differences in total BMD and TBS could be attributed to reductions in epiphyseal rather than metaphyseal or diaphysis measurements. The relationship between TBS and duration of SCI was well explained by a logarithmic trend at the distal femoral epiphysis (r²?=?0.54, p?=?0.025). The logarithmic trend would predict that after 3?yr of SCI, TBS would be approximately 6% lower than the non-SCI controls. Further evaluation is needed to determine if TBS measures at the knee provide important information about bone quality that is not captured by traditional BMD.     

Bilateral symmetrical cysts in the upper tibiae in a skeletally mature patient: might they be simple bone cysts?

A 55-year-old Japanese woman presented with right knee pain of 1-month duration. Radiological studies revealed bilateral mild osteoarthritic changes in the medial knee joint compartment and symmetrical cysts in the upper tibial metaphyses, extending to the epiphyses. Intraosseous ganglion was considered the most probable diagnosis. However, intraoperatively, serous fluid-filled cavities were recognized; these were curetted and filled with hydroxyapatite granules. Histopathological examination of the cyst wall revealed thin fibrous tissue formed of collagen fibers without a lining cell layer, with scattered lymphocytes, histiocytes, irregular masses of fibrin-like material, and periosteal osteocartilagenous callus formation; a picture compatible with simple bone cysts. Bilateral symmetrical cysts of the upper tibial metaphyses extending to the epiphyses are extremely rare. A literature review revealed that the age incidence, and bony locations of multiple and epiphyseal simple bone cysts are atypical in relation to the classic metaphyseal simple bone cysts. Also, multiple and epiphyseal simple bone cysts have a better prognosis than the classic metaphyseal ones. Four clinicoanatomic varieties of simple bone cysts are recognized; classic metaphyseal, nontubular, epiphyseal, and multiple.     

Properties of growing trabecular ovine bone. Part II: architectural and mechanical properties

We aimed to highlight the relationship between age and the architectural properties of trabecular bone, to outline the patterns in which the variations in these properties take place, and to investigate the influence of the architecture on the mechanical properties of trabecular bone in growing animals. We studied 30 lambs in three age groups and 20 sheep in two age groups. Cubes of subchondral bone were cut from the proximal tibia according to a standardised protocol. They were serially sectioned and their architectural properties were determined. Similar cubes were obtained from the identical anatomical position of the contralateral tibia and their compressive mechanical properties measured. The values obtained from the skeletally immature and mature individuals were compared. Multiple regression analyses were performed between the architectural and the mechanical properties. The bone volume fraction, the mean trabecular volume, the architectural and the mechanical anisotropy, the elastic modulus, the bone strength, the energy absorption to failure, and the elastic energy correlated positively with increasing age whereas the connectivity density, the bone surface density, the ultimate strain, the absorption of viscoelastic energy and the relative loss of energy correlated inversely. The values of all variables were significantly different in the skeletally mature and immature groups. We determined the patterns in which the variations took place. The bone volume fraction of the trabecular bone tissue was found to be the major predictor of its compressive mechanical properties. Together with the mean trabecular volume and the bone surface density, it explained 81% of the variations in the compressive elastic modulus of specimens obtained from the contralateral tibiae.     

Properties of growing trabecular ovine bone. Part I: mechanical and physical properties

Our aim was to determine the relationship between age and the mechanical and physical properties of trabecular bone, to describe the patterns in which the variations in these properties take place, and to investigate the influence of the physical properties on the mechanical characteristics of trabecular bone during growth. We used 30 lambs in three age groups and 20 sheep in two age groups. Cubes of subchondral bone were cut from the proximal tibia according to a standardised protocol. We performed non-destructive compression tests of the specimens in three orthogonal directions and compression tests to failure in the axial direction. The physical properties of the specimens were also determined. The data were correlated with age and compared in skeletally immature and mature animals. Multiple regression analyses were performed between the mechanical and the physical properties. Age correlated positively with elastic modulus, bone strength, energy absorption to failure, elastic energy, mechanical anisotropy ratio, tissue density, apparent density, apparent ash density, and bone mineral content, and inversely with ultimate strain, viscoelastic energy absorption, relative energy loss, the collagen content of bone and the percentage porosity. The values of all variables were significantly different in the skeletally mature and immature groups. The apparent density of trabecular bone tissue was found to be the major predictor of its compressive mechanical properties. Together with the content of bone muscle and bone collagen, the apparent density could explain 84% of the variation in the elastic modulus, whereas only a small portion of the variation in ultimate strain could be explained by the variation in apparent density.     

Pulsed electromagnetic fields reduce knee osteoarthritic lesion progression in the aged Dunkin Hartley guinea pig.

An experimental in vivo study was performed to test if the effect of Pulsed Electromagnetic Fields (PEMFs) on chondrocyte metabolism and adenosine A2a agonist activity could have a chondroprotective effect on the knee of Dunkin Hartley guinea-pigs of 12 months with spontaneously developed osteoarthritis (OA). After a pilot study, 10 animals were randomly divided into two groups: PEMF-treated group (6 h/day for 3 months) and Sham-treated group. Microradiography and histomorphometry were performed on the entire articular surface of knee joints used in evaluating chondropathy severity, cartilage thickness (CT), cartilage surface Fibrillation Index (FI), subchondral bone plate thickness (SBT) and histomorphometric characteristics of trabecular epiphyseal bone. The PEMF-treated animals showed a significant reduction of chondropathy progression in all knee examined areas (p<0.05). CT was significantly higher (p<0.001) in the medial tibia plateaus of the PEMF-treated group when compared to the Sham-treated group. The highest value of FI was observed in the medial tibia plateau of the Sham-treated group (p<0.05). Significant lower values were observed in SBT of PEMF-treated group in comparison to Sham-treated group in all knee examined areas (p<0.05). The present study results show that PEMFs preserve the morphology of articular cartilage and slower the progression of OA lesions in the knee of aged osteoarthritic guinea pigs. The chondroprotective effect of PEMFs was demonstrated not only in the medial tibial plateau but also on the entire articular surface of the knee.     

Histopathological features of unilateral stapling in animal experiments

Summary Blount stapling of the proximal medial tibial growth was performed in 10-week-old domestic pigs. A total of 37 animals for up to 17 weeks were followed up. The histological evaluation showed a different reaction of the growth plate in the medial (stapled), central and lateral area. Up to 6 days after stapling the morphological features were characterized by deviations of the cell column from the axial alignment. Herniations of mature chondrocytes as well as isles of epiphyseal cartilage splintered into the adjacent metaphyseal cancellous bone were seen. From the 10th to the 11th postoperative day on there was a decline in the number of distal hypertrophic and degenerating cartilage cells due to impaired proliferation. Cell atrophy due to disturbed maturation or cell degeneration was evident. Local clusters of chondrocytes with loss of columnar arrangement indicated impaired chondrogenesis. Twenty-eight days after the operation coarses structures and changed alignment of cancellous bone characterized the morphological picture. The postoperative follow-up showed epiphyseal plates bounded by mature bone blocks or even a distinct sheet of horizontally oriented bone plates on the metaphyseal side. Many metaphyseal findings, such as augmented hypertrophic cells in the early postoperative period, or platelike limitations of the epiphyseal plate complete the morphological picture.Supported by the Deutsche Forschungsgemeinschaft     

Trabecular bone strain changes resulting from partial and complete meniscectomy

Previous studies have documented how partial and complete meniscectomy affect articular contact pressure, but changes in load transfer through the complete osteochondral structure of the proximal tibia after partial and complete meniscectomy are not well known. The current study measured trabecular bone strain changes in the medial tibial plateau resulting from partial and complete medial meniscectomy. Midcoronal sections were prepared from knees from cadavers. High quality digital images, made from contact radiographs of loaded samples, were compared with digital images of unloaded samples using in-house software to measure trabecular bone strain. Measurements were made on specimens with an intact medial meniscus, after removal of the inner (2/3) of the meniscus, and after complete meniscectomy. Partial meniscectomy caused minimal increases in trabecular bone strain throughout the proximal tibia. However specimens with complete meniscectomy had significant trabecular bone strain increases. Many patients sustaining meniscus tears are young, therefore, it is important to understand mechanical changes associated with partial meniscectomy. The data suggest partial meniscectomy causes little change in load transfer through the proximal tibia, supporting partial meniscectomy as a good surgical option for patients with meniscus tears.     

The Subchondral Bone of the Proximal Tibial Epiphysis in Osteoarthritis of the Knee

The trabecular bone of the proximal end of the tibia was assessed as an endoprosthesis-bearing structure. The mass and mineral content as well as the activity of subchondral trabecular bone were determined in osteoarthritic knees with varus or valgus deformity.

Bone specimens were taken from the lateral condyle, the medial condyle, and centrally from the intercondylar area of seven varus and four valgus knees. The percentage volume of trabecular bone was determined by histomorphometry. On an additional nine knees, five with varus and four with valgus deformity, as well as ten knees from a normal autopsy material, photon absorptiometric determination of the mineral content of the same areas was performed. On average, the loaded condyle had twice the percentage volume of trabecular bone, and accordingly twice the mineral content, of the unloaded condyle. It was remarkable that the mineral content of the latter was of the same order as the condyles of the normal material.     

Bone mineral and stiffness loss at the distal femur and proximal tibia in acute spinal cord injury

Summary

Computed tomography and finite element modeling were used to assess bone mineral and stiffness loss at the knee following acute spinal cord injury (SCI). Marked bone mineral loss was observed from a combination of trabecular and endocortical resorption. Reductions in stiffness were 2-fold greater than reductions in integral bone mineral.

Introduction

SCI is associated with a rapid loss of bone mineral and an increased rate of fragility fracture. The large majority of these fractures occur around regions of the knee. Our purpose was to quantify changes to bone mineral, geometry, strength indices, and stiffness at the distal femur and proximal tibia in acute SCI.

Methods

Quantitative computed tomography (QCT) and patient-specific finite element analysis were performed on 13 subjects with acute SCI at serial time points separated by a mean of 3.5 months (range 2.6–4.8 months). Changes in bone mineral content (BMC) and volumetric bone mineral density (vBMD) were quantified for integral, trabecular, and cortical bone at epiphyseal, metaphyseal, and diaphyseal regions of the distal femur and proximal tibia. Changes in bone volumes, cross-sectional areas, strength indices and stiffness were also determined.

Results

Bone mineral loss was similar in magnitude at the distal femur and proximal tibia. Reductions were most pronounced at epiphyseal regions, ranging from 3.0 % to 3.6 % per month for integral BMC (p?<?0.001) and from 2.8 % to 3.4 % per month (p?<?0.001) for integral vBMC. Trabecular BMC decreased by 3.1–4.4 %/month (p?<?0.001) and trabecular vBMD by 2.7–4.7 %/month (p?<?0.001). A 3.8–5.4 %/month reduction was observed for cortical BMC (p?<?0.001); the reduction in cortical vBMD was noticeably lower (0.6–0.8 %/month; p?≤?0.01). The cortical bone loss occurred primarily through endosteal resorption, and reductions in strength indices and stiffness were some 2-fold greater than reductions in integral bone mineral.

Conclusions

These findings highlight the need for therapeutic interventions targeting both trabecular and endocortical bone mineral preservation in acute SCI.     

Treatment for painful bone marrow edema by open wedge tibial osteotomy

We evaluated the results of patients who had undergone medial open wedge proximal tibial osteotomy, with painful bone marrow edema in the medial tibial plateau. The study included 21 patients who had presented with knee pain and whose MRIs showed bone marrow edema in medial plateau. The degree of osteoarthritis was evaluated radiologically according to the Kellgren–Lawrence criteria; 6 cases were Grade 1, 11 cases were Grade 2, and 3 cases were Grade 3. Preoperative varus angle was a mean of 2.19° (0–4). The bone marrow edema was classified according to the width of the lesions extending into the joint surface subchondral area on MRI T2 sequences. Open wedge osteotomy was performed in all patients. The postoperative results were evaluated by X-ray, MRI, and WOMAC (Western Ontario and McMaster Universities) knee scores. The preoperative 2.19° varus angle was evaluated postoperatively as valgus 6.57° (4–8°) (p < 0.05). The postoperative WOMAC knee scores revealed a significant decrease in pain (p < 0.05). In conclusion, we are of the opinion that medial open wedge proximal tibial osteotomy is an effective treatment in patients who have painful bone marrow edema in medial tibia plateau.     

Effects of long-term estrogen replacement therapy on bone turnover in periarticular tibial osteophytes in surgically postmenopausal cynomolgus monkeys

The aims of the present study were to assess the effects of long-term estrogen replacement therapy (ERT) on size and indices of bone turnover in periarticular osteophytes in ovariectomized cynomolgus monkeys and to compare dynamic indices of bone turnover in osteophyte bone with those of subchondral bone (SCB) and epiphyseal/metaphyseal cancellous (EMC) bone. One hundred sixty-five adult female cynomolgus macaques were bilaterally ovariectomized and randomly divided into three age- and weight-matched treatment groups for a 36-month treatment period. Group 1 (OVX control) received no treatment, Group 2 (SPE) received soy phytoestrogens, and Group 3 (ERT) received conjugated equine estrogens in the diet; all monkeys were labeled with calcein before necropsy. A midcoronal, plastic-embedded section of the right proximal tibia from 20 randomly selected animals per treatment group was examined histologically. Forty-nine of the sections (OVX control, n = 16; SPE, n = 16; ERT, n = 17) contained lateral abaxial osteophytes, and static and dynamic histomorphometry measurements were taken from osteophyte bone, SCB from the lateral tibial plateau, and EMC bone. Data were analyzed using the ANOVA and Kruskal–Wallis test, correlation and regression methods, and the Friedman and Wilcoxon signed rank test. There was no significant effect of long-term ERT on osteophyte area or on any static or dynamic histomorphometry parameters. The bone volume, trabecular number, and trabecular thickness in osteophyte bone were considerably higher than in EMC bone; whereas, trabecular separation was considerably lower in osteophyte bone. In all three treatment groups, BS/BV was significantly lower in osteophyte bone vs. EMC bone and significantly higher in osteophyte bone vs. lateral SCB. We conclude that osteophyte area and static and dynamic histomorphometry parameters within periarticular tibial osteophytes in ovariectomized cynomolgus monkeys are not significantly influenced by long-term ERT, but that site differences in static and dynamic bone histomorphometry parameters exist, particularly between EMC and osteophyte bone.