Study of human radius construction systematics: evaluation by DXA in dry bone.

This study has been undertaken in order to describe the bone mass distribution of the dry human radius via dual x-ray absorptiometry (DXA) with a Norland XR-800 densitometer machine. A sample of 39 dry radius bones was used. Two projections were made: antero-posterior and lateral, and five regions of interest were selected. The bone densities and the bone mineral contents of the various regions of the radius in the two projections were compared using Student's t tests for paired samples, with statistically significant differences being found in all of the values, except in the proximal extremity (P Ext). The area of greatest bone mineral content (BMC) was the medial diaphysis (M Diaph), followed by the distal extremity (D Ext), with the lowest value being found in the proximal extremity (P Ext). As for bone mineral density (BMD), a great symmetry is observed if we take the mean point of the longitudinal axis as a reference, with it being distributed from highest to lowest from the central part to the extremities. A correlation study of the BMD and BMC values between the segments themselves and with the total, in both positions, provides us with a high correlation (p ≤ 0.01), with the highest correlation value being found for the proximal diaphysis (P Diaph) region, indicating the heterogeneous nature of the distribution of the radius bone mass. Bone densitometry via DXA is useful in order to establish an overview of the structural construction of the human radius.

Finite element analysis of the femoral diaphysis of fresh-frozen cadavers with computed tomography and mechanical testing.

BACKGROUND: The purpose of this study was to validate a diaphyseal femoral fracture model using a finite element analysis (FEA) with mechanical testing in fresh-frozen cadavers. METHODS: We used 18 intact femora (9 right and 9 left) from 9 fresh-frozen cadavers. Specimens were obtained from 5 males and 4 females with a mean age of 85.6 years. We compared a computed tomography (CT)-based FEA model to diaphyseal femoral fracture loads and stiffness obtained by three-point bending. Four material characteristic conversion equations (the Keyak, Carter, and Keller equations plus Keller's equation for the vertebra) with different shell thicknesses (0.3, 0.4, and 0.5 mm) were compared with the mechanical testing. RESULTS: The average fracture load was 4582.8 N and the mean stiffness was 942.0 N/mm from actual mechanical testing. FEA prediction using Keller's equation for the vertebra with a 0.4-mm shell thickness showed the best correlations with the fracture load (R2 = 0.76) and stiffness (R2 = 0.54). Shell thicknesses of 0.3 and 0.5 mm in Keller's equation for the vertebra also showed a strong correlation with fracture load (R2 = 0.66 for both) and stiffness (R2 = 0.50 and 0.52, respectively). There were no significant correlations with the other equations. CONCLUSION: We validated femoral diaphyseal fracture loads and stiffness using an FEA in a cadaveric study.

Longitudinal Effects of Single Hindlimb Radiation Therapy on Bone Strength and Morphology at Local and Contralateral Sites.

Radiation therapy (RTx) is associated with increased risk for late-onset fragility fractures in bone tissue underlying the radiation field. Bone tissue outside the RTx field is often selected as a "normal" comparator tissue in clinical assessment of fragility fracture risk, but the robustness of this comparison is limited by an incomplete understanding of the systemic effects of local radiotherapy. In this study, a mouse model of limited field irradiation was used to quantify longitudinal changes in local (irradiated) and systemic (non-irradiated) femurs with respect to bone density, morphology, and strength. BALB/cJ mice aged 12 weeks underwent unilateral hindlimb irradiation (4 × 5 Gy) or a sham procedure. Femurs were collected at endpoints of 4 days before treatment and at 0, 1, 2, 4, 8, 12, and 26 weeks post-treatment. Irradiated (RTx), Contralateral (non-RTx), and Sham (non-RTx) femurs were imaged by micro-computed tomography and mechanically tested in three-point bending. In both the RTx and Contralateral non-RTx groups, the longer-term (12- to 26-week) outcomes included trabecular resorption, loss of diaphyseal cortical bone, and decreased bending strength. Contralateral femurs generally followed an intermediate response compared with RTx femurs. Change also varied by anatomic compartment; post-RTx loss of trabecular bone was more profound in the metaphyseal than the epiphyseal compartment, and cortical bone thickness decreased at the mid-diaphysis but increased at the metaphysis. These data demonstrate that changes in bone quantity, density, and architecture occur both locally and systemically after limited field irradiation and vary by anatomic compartment. Furthermore, the severity and persistence of systemic bone damage after limited field irradiation suggest selection of control tissues for assessment of fracture risk or changes in bone density after radiotherapy may be challenging. © 2017 American Society for Bone and Mineral Research.

Head-shaft angle changes during internal and external shoulder rotations: 2-D angulation in 3-D space.

INTRODUCTION: Restoration of native head-shaft angle (HSA) is critical for treatment of proximal humerus fracture. However, HSA has not been properly investigated according to the humeral rotation. This study was designed to analyze the relationship between the humeral rotation and the HSA at 1° increments, and clarify its serial changing pattern according to the humeral rotation. HYPOTHESIS: The angulation of HSA would be undervalued when the humerus is being rotated externally and it would be overvalued when it is being rotated internally. MATERIALS AND METHODS: Eight dried cadaveric normal humeri were CT scanned. They were analyzed using computer-aided design with a standardized neutral position. HSA was the angle between the humeral shaft axis (SA) and the humeral head axis (HA). SA and HA were the best-fit lines through center of all the best-fitting circles in every cross section along the humeral shaft and within the humeral head, respectively. Each 3D model was rotated 30° internally and 45° externally relatives to the SA at 1° increments with the camera was fixed at antero-posterior view of neutral position. Angulation of HSA in every rotational degree was documented as ratio relatives to the angulation of HSA in neutral position. RESULTS: The average HSA at neutral position was 133±1.93°. HSA was underestimated by 8±1.9% and it was overestimated by 20±5.1% at the maximum external rotation (ER) and internal rotation (IR), respectively. HSA was underestimated by 1% in every 5.8° of ER and overestimated by 1% in every 1.5° of IR. Rotational misalignments within 10° of IR and 18° of ER could be tolerated (P>.05). CONCLUSIONS: HSA was underestimated at ER and was overestimated at IR. This information could be useful for surgeons in restoring the native HSA for treatment of proximal humerus fracture. TYPE OF STUDY: Basic research study.

Displaced femoral shaft fractures treated by antegrade nailing with the assistance of an intramedullary reduction device.

PURPOSE: This study aims to assess the outcomes of displaced femoral shaft fractures (DFSFs) treated by antegrade nailing with the assistance of a newly invented intramedullary (IM) reduction device. METHODS: From December 2012 to August 2013, 43 adult patients with unilateral DFSFs, including 31 males and 12 females, were enrolled into this study. During the operation, the device was used to adjust the direction of guide wire to insert it into the medullary cavity of distal femur and used as a "joystick" to align the femoral shaft fractures before the insertion of IM nail. The operative time and fluoroscopy time were recorded. Follow-up was conducted to assess the fracture union and functional recovery of the affected limbs. RESULTS: The IM reduction device was used intra-operatively to advance the guide wire into the distal femoral medullary cavity successfully in all 43 cases, with a single attempt in 37 cases and two or three attempts in six cases. The average operative time and fluoroscopy time were 58.3 minutes (40-85 minutes) and 9.2 seconds (4.1-21.8 seconds), respectively. All fractures healed well on an average of 5.4 months post-operatively. No limb-length discrepancy or observable malalignment was noted at the follow ups. CONCLUSIONS: The IM reduction device can facilitate the insertion of a guide wire into the distal femoral medullary cavity in a closed and controllable manner, be used as a "joystick" to align the femoral shaft fracture, and subsequently facilitate IM nail insertion in the proper position.

Effects of local insulin delivery on subperiosteal angiogenesis and mineralized tissue formation during fracture healing.

Local insulin delivery has been shown to improve osseous healing in diabetic animals. The purpose of this study was to quantify the effects of local intramedullary delivery of saline or Ultralente insulin (UL) on various fracture healing parameters using an in vivo non-diabetic BB Wistar rat model. Quantitation of local insulin levels showed a rapid release of insulin from the fractured femora, demonstrating complete release at 2 days. RT-PCR analysis revealed that the expression of early osteogenic markers (Col1α2, osteopontin) was significantly enhanced with UL treatment when compared with saline controls (p < 0.05). Significant differences in VEGF + cells and vascularity were evident between the treatment and control groups at day 7 (p < 0.05). At day 21, histomorphometric analysis demonstrated a significant increase in percent mineralized tissue in the UL-treated animals compared with controls (p < 0.05), particularly within the subperiosteal region of the fracture callus. Mechanical testing at 4 weeks showed significantly greater mechanical strength for UL-treated animals (p < 0.05), but healing in control animals caught up at 6 weeks post-fracture. These results suggest that the primary osteogenic effect of UL during the early stages of fracture healing (1-3 weeks) is through an increase in osteogenic gene expression, subperiosteal angiogenesis, and mineralized tissue formation.

Effect of Epimedium pubescen flavonoid on bone mineral density and biomechanical properties of femoral distal end and femoral diaphysis of passively smoking male rats.

BACKGROUND: Based on a rat model of human relatively high exposure to cigarette smoke, this study aimed to estimate whether Epimedium pubescen flavonoid (EPF) may prevent a smoke-induced decrease in bone mineral density (BMD) and weakening of the biomechanical properties of bone. METHODS: Fifty male Wistar rats were randomized into five groups: controls, passively smoking groups and passively smoking rats administered EPF at three dosage levels (75, 150 or 300 mg/kg/day) in drinking water for 4 months. A rat model of passive cigarette smoking was prepared by breeding male rats in a cigarette-smoking box for 4 months. Bone metabolic makers, BMD and biomechanical properties of the femoral distal end and femoral diaphysis were examined. RESULTS: Exposure to cigarette smoke decreased the BMD, affected bone turnover (inhibited bone formation and stimulated its resorption) and weakened the biomechanical properties of the femur at its distal end and diaphysis. EPF supplementation during cigarette smoke exposure prevented the decrease in BMD, accelerated bone turnover and weakened the biomechanical properties of bone. CONCLUSION: Our data suggest that EPF supplementation can prevent the adverse effects of smoke exposure on BMD and biomechanical properties by inhibiting bone turnover and preventing bone resorption, and in this way it can decrease the risk of bone fractures.

Effects of extensive circumferential periosteal stripping on the microstructure and mechanical properties of the murine femoral cortex.

Extensive periosteal stripping (PS) is a risk factor for post-radiation pathologic fracture following surgery for extremity soft tissue tumors. The purpose of this study was to determine the effects of PS on bone structure and mechanical properties. Thirty-one skeletally mature mice underwent PS, with circumferential removal of periosteum from an 8-mm segment of the mid-diaphysis of the left femur. Thirty-one control mice underwent sham surgery in which the femur was isolated without manipulation of the periosteum. At 2, 6, 12, or 26 weeks following surgery, the left femora were examined by micro-CT to quantify cortical thickness (CtTh), cross-sectional area (CSA), bone volume (BV), and polar moment of inertia (PMI). Three-point mechanical bend testing was performed and peak load, stiffness, and energy to failure were determined. PS resulted in significantly decreased CtTh, CSA, BV, and PMI at all time points. Peak load, stiffness, and energy to failure were significantly reduced at 2, 6, and 12 weeks. There were no significant differences in mechanical properties at 26 weeks. In this mouse model, extensive circumferential PS resulted in sustained changes in bone structure that were still evident after 6 months, accompanied by reductions in bone strength that persisted for at least 3 months.

Growth potential of different zones of the growth plate-an experimental study in rabbits.

Despite clinical efforts to treat growth disturbances only little is known about the growth potential of the different zones of the growth plate. The aim of this study was to investigate the growth potential of different zones of the growth plate. A total of 20 New Zealand White rabbits were used for this experiment. The right and left ulna of each animal were used resulting in a total of 40 ulnae. Animals were assigned into five groups. In groups I and II resection of the metaphyseal (n = 12) or the epiphyseal (n = 6) segment of the growth plate was performed. In group III resection of the growth plate and re-implantation was performed (n = 6). In group IV the growth plate was resected and re-implanted after a 180° rotation (n = 6). Animals in group V served as controls. Histologic and radiologic examinations were performed to evaluate the growth process at 1, 2, 4, and 12 weeks following surgery. In group I, III, and IV temporary growth disturbance which was compensated within a short time was observed. Resection of the epiphyseal part resulted in growth arrest of the distal ulna in combination with normal growth of the radius which led to and valgus deformity of the limb. The results of this study indicate the importance of the reserve zone for the functioning of the growth plate.

Influence of locking bolt location on the mechanical properties of an interlocking nail in the canine femur.

OBJECTIVE: To determine whether the fatigue properties of an interlocking nail (ILN) construct are influenced by metaphyseal or diaphyseal location of the locking bolt. STUDY DESIGN: Ex vivo mechanical investigation. SAMPLE POPULATION: Adult canine femora (n = 19 pairs). METHODS: Femora were implanted with a 6-mm diameter ILN. In 1 femur, the ILN was locked with a 2.7 mm bolt placed in the diaphysis; the ILN in the contralateral femur was locked with a bolt placed in the metaphysis. Constructs were tested to failure in axial loading (9 pairs) or torsion (10 pairs), with failure defined as displacement > 2 mm or a total of 500,000 cycles for axial loading, and rotation > 45° for torsional loading. Outcome measures included initial construct stiffness, number of cycles to failure, peak load, and peak torque. After testing, microradiography and histology were used to determine the location and nature of construct failure. RESULTS: Metaphyseal bolts failed at higher axial loads than diaphyseal bolts (P = .03), with bolt failure because of bending at the nail-bolt interface. All of the metaphyseal bolt constructs survived torsional testing whereas 9 of 10 diaphyseal bolt constructs failed catastrophically because of spiral fracture through the adjacent cortical bone. CONCLUSIONS: Placement of a locking bolt in metaphyseal bone extends fatigue life under axial loading and decreases the incidence of catastrophic failure under torsional loading.

Influence of long-term postmenopausal hormone-replacement therapy on estimated structural bone strength: a study in discordant monozygotic twins.

Although postmenopausal hormone-replacement therapy (HRT) is known to prevent fractures, knowledge on the influence of long-term HRT on bone strength and its determinants other than areal bone mineral density is scarce. This study used a genetically controlled design with 24 monozygotic female twin pairs aged 54 to 72 years in which one cotwin was using HRT (mean duration 8 years) and the other had never used HRT. Estimated bone strength, cross-sectional area, volumetric bone mineral density, bone mineral mass, and cross-sectional density and mass distributions were assessed in the tibial shaft, distal tibia, and distal radius with peripheral computed tomography (pQCT). In the tibial shaft, HRT users had 9% [95% confidence interval (CI) 3%-15%] higher estimated bending strength than their nonusing cotwins. Larger cortical area and higher cortical bone mineral density accounted for this difference. The cortex was larger in the HRT users in the endocortical region. In the distal tibia, estimated compressive strength was 24% (95% CI 9%-40%) higher and in the distal radius 26% (95% CI 11%-41%) higher in the HRT users than in their nonusing cotwins owing to higher volumetric bone mineral density. No difference between users and nonusers was observed in total bone cross-sectional area in any measured bone site. The added mineral mass in the HRT users was distributed evenly within and between bone sites. In postmenopausal women, long-term HRT preserves estimated bone strength systemically by preventing bone mineral loss similarly in body weight-loaded and non-weight-loaded bone.

Drilled hole defects in mouse femur as models of intramembranous cortical and cancellous bone regeneration.

In order to identify pertinent models of cortical and cancellous bone regeneration, we compared the kinetics and patterns of bone healing in mouse femur using two defect protocols. The first protocol consisted of a 0.9-mm-diameter through-and-through cortical hole drilled in the mid-diaphysis. The second protocol was a 0.9-mm-diameter, 1-mm-deep perforation in the distal epimetaphyseal region, which destroyed part of the growth plate and cancellous bone. Bone healing was analyzed by ex vivo micro-computerized X-ray tomography and histology. In the diaphysis, the cortical gap was bridged with woven bone within 2 weeks. This newly formed bone was rapidly remodeled into compact cortical bone, which showed characteristic parameters of intact cortex 4 weeks after surgery. In the epimetaphysis, bone formation was initiated at the deepest region of the defect and spread slowly toward the cortical gap. In this position, newly formed bone quickly adopted the characteristics of trabecular bone, whereas a thin compact wall was formed at its external border, which reached the density of intact cortical bone but failed to bridge the cortical gap even 13 weeks after surgery. This comparative study indicates that the diaphyseal defect is a model of cortical bone healing and that the epimetaphyseal defect is a model of cancellous bone repair. These models enable experimental genetics studies to investigate the cellular and molecular mechanisms of spontaneous cortical and cancellous bone repair and may be useful for pharmacological studies.

Influence of bone-derived matrices on generation of bone in an ectopic rat model.

Most bone regeneration experimental models that test bone-derived matrices take place in conjunction with the native bone. Here, we compared the relative effectiveness of bone matrix components on bone-marrow-directed osteogenesis in an ectopic model. Cortical bone cylinders consisted of diaphysis of DA rat femurs. They were either demineralized (DBM), deproteinized (HABM), or nontreated (MBM). Fresh bone marrow was placed into cylinders and implanted at subcutaneous thoracic sites of 2-month-old DA rats. At designated times the cylinders were surgically removed from the animals. Microradiographs of DBM and histology of DBM and MBM cylinders demonstrated progressive increase in mineralized bone volume and its trabecular configuration. Bone filled the inner volume of DBM and MBM cylinders within 4 weeks, while in HABM cylinders mostly granulation tissue developed. In the DBM cylinders cartilage deposited within 10 days, while in the MBM cylinders bone was directly deposited. As early as day 3 after marrow transplantation, marrow cells interacting with DBM increased significantly the genes that express the cartilage and the bone phenotype. In conclusion, organic components of bone are needed for marrow-directed osteogenesis.

[Peculiarities of repair osteogenesis during the transverse traction of the longitudinal diaphysis fragment under the conditions of intraosseus vessel preservation].

The application of technique for obtaining the tibial fragment (split) with a preserved vascular network of the nutrient artery and its branches, that participate in the blood supply of this bone area, permits to detect significant osteogenetic potential of both endosteum and undifferentiated bone marrow cells. Under these conditions it was possible to increase the bone thickness 2 to 3 times in short time. The regeneration process in this case is characterized by a rapid course and formation of large massive of cancellous bone. The results of this study suggest that an adequate blood supply, stable fixation of bone using Ilizarov apparatus and the chosen rate of split displacement create the favorable conditions for the active osteogenesis.

Predicting the strength of femoral shafts with and without metastatic lesions.

To evaluate a potential tool for assessing the risk of a pathologic fracture of the femoral shaft, we examined whether fracture loads computed by our computed tomography scan-based finite element models are predictive of measured fracture loads. We also evaluated whether the precision of the computed fracture loads for shafts with metastases is altered if models are generated using mechanical property-density relationships for bone without metastases. We investigated whether femoral shafts with a hemispheric defect and shafts with metastases have qualitatively similar structural behavior. Using identical four-point bending loading conditions, we computed and measured fracture loads of femoral shafts with and without metastases and with a burred hemispheric defect to simulate a tumor. Finite element model fracture loads were strongly predictive of the measured fracture loads (range, 0.92-0.98) even when the models of bones with metastases used mechanical property relationships for bone without metastases. Specimens with hemispheric defects behaved structurally differently than specimens with metastases, indicating that these defects do not accurately simulate the effects of metastases. Results of our study show that these computed tomography scan-based finite element models can be used to estimate the strength of femoral shafts with and without metastases. These models may be useful for assessing the risk of pathologic fractures of femoral shafts.

Correlation of bone mineral density with strength and microstructural parameters of cortical bone in vitro.

The aim of this study was to evaluate the influence of microstructural parameters, such as porosity and osteon dimensions, on strength. Therefore, the predictive value of bone mineral density (BMD) measured by quantitative computed tomography (QCT) for intracortical porosity and other microstructural parameters, as well as for strength of cortical bone biopsies, was investigated. Femoral cortical bone specimens from the middiaphysis of 23 patients were harvested during total hip replacement while drilling a hole (dia. 4.5 mm) for the relief of the intramedullary pressure. In vitro structural parameters assessed in histological sections as well as BMD determined by quantitative computed tomography were correlated with yield stress, and elastic modulus assessed by a compression test of the same specimens. Significant correlations were found between BMD and all mechanical parameters (elastic modulus: r = 0.69, p < 0.005; yield stress: r = 0.64, p < 0.005). Significant correlations between most structural parameters assessed by histology and yield stress were discovered. Structural parameters related to pore dimensions revealed higher correlation coefficients with yield stress (r = -0.69 for average pore diameter and r = -0.62 for fraction of porous structures, p < 0.005) than parameters related to osteons (r = 0.60 for osteon density and average osteonal area, p < 0.005), whereas elastic modulus was predicted equally well by both types of parameters. Significant correlations were found between BMD and parameters related to porous structures (r = 0.85 for porosity, 0.80 for average pore area, and r = 0.79 for average pore diameter in polynomial regression, p < 0.005). Histologically assessed porosity correlated significantly with parameters describing porous structures and haversian canal dimensions. Our results indicate a relevance of osteon density and fraction of osteonal structures for the mechanical parameters of cortical bone. We consider the measurement of BMD by quantitative computed tomography to be helpful for the estimation of bone strength as well as for the prediction of intracortical porosity and parameters related to porous structures of cortical bone.

[Mineral density of the femoral diaphysis after hip prosthesis implantation]. / Mineral'noe nasyshchenie diafiza bedrennoi kosti posle éndoprotezirovaniia tazobedrennogo sustava.

The aseptic instability of endoprostheses, which occurs after their good operation, is a severe complication. All developed countries study this problem from different points of view. This paper presents the data of up to 5-year follow-ups of the mineral saturation of the microstructures of the hip bone diaphysis during endoprosthesis. The paper has been the only to be performed by latest techniques in the former Soviet Union. It is of great interest for researchers who are engaged in searching materials for endoprostheses, for their designers. It is also useful for surgeons in solving the problems how to raise patients after surgery and in giving further recommendations.

In vitro pullout strength of screws inserted in adult equine third metacarpal bone after overdrilling a 4.5-mm threaded insertion hole.

OBJECTIVE: To determine and compare the in vitro pullout strength of 5.5-mm cortical versus 6.5-mm cancellous bone screws inserted in the diaphysis and metaphysis of adult equine third metacarpal (MCIII) bones, in threaded 4.5-mm cortical bone screw insertion holes that were then overdrilled with a 4.5-mm drill bit to provide information relevant to the selection of a replacement screw if a 4.5-mm cortical screw is stripped. STUDY DESIGN: In vitro pullout tests of 5.5-mm cortical and 6.5-mm cancellous screws in equine MCIII bones. SAMPLE POPULATION: Two independent cadaver studies each consisting of 14 adult equine MCIII bones. METHODS: Two 4.5-mm cortical screws were placed either in the middiaphysis (study 1) or distal metaphysis (study 2) of MCIII bones. The holes were then overdrilled with a 4.5-mm drill bit and had either a 5.5-mm cortical or a 6.5-mm cancellous screw inserted; screw pullout tests were performed at a rate of 0.04 mm/second until screw or bone failure occurred. RESULTS: In diaphyseal bone, the screws failed in all tests. Tensile breaking strength for 5.5-mm cortical screws (997.5 +/- 49.3 kg) and 6.5-mm cancellous screws (931.6 +/- 19.5 kg) was not significantly different. In metaphyseal bone, the bone failed in all tests. The holding power for 6.5-mm cancellous screws (39.1 +/- 4.9 kg/mm) was significantly greater than 5.5-mm cortical screws (23.5 +/- 3.5 kg/mm) in the metaphysis. There was no difference in the tensile breaking strength of screws in the diaphysis between proximal and distal screw holes; however, the holding power was significantly greater in the distal, compared with the proximal, metaphyseal holes. CONCLUSIONS: Although tensile breaking strength was not different between 5.5-mm cortical and 6.5-mm cancellous screws in middiaphyseal cortical bone, holding power of 6.5-mm cancellous screws was greater than 5.5-mm cortical screws in metaphyseal bone of adult horses. CLINICAL RELEVANCE: If a 4.5-mm cortical bone screw strips in MCIII diaphyseal bone of adult horses, either a 5.5-mm cortical or 6.5-mm cancellous screw, however, would have equivalent pullout strengths. A 6.5-mm cancellous screw, however, would provide greater holding power than a 5.5-mm cortical screw in metaphyseal bone.

Effect of cisplatin chemotherapy on extracortical tissue formation in canine diaphyseal segmental replacement.

The reconstruction of large bone and joint defects after the resection of malignant tumors remains a major challenge. Chemotherapy has significantly lowered the risk of metastasic disease, but complications associated with reconstructive techniques continue to result in late morbidity. In the present study, biomechanical torsion testing, gait analysis, and histomorphometric and scanning electron microscopic evaluations of 24 dogs were used to examine the effects of preoperative and postoperative administration of cisplatin on the biologic fixation of a porous-coated segmental replacement prosthesis. The chemotherapy consisted of four cycles of cisplatin administered at a dosage of 75 mg/m2 preoperatively or postoperatively. The healing was enhanced by use of an autogenous corticocancellous bone graft. The graft was placed evenly around the prosthesis and the adjacent femoral cortex. Mechanical analyses of torsional stiffness, yield strength, and maximum strength revealed no statistically significant differences between the groups at 12 weeks. Such lack of difference was mainly due to the penetration of highly organized fibrous tissue into the porous surface; this provided strong fixation of the implant to bone even in the absence of bone ingrowth. Although bone ingrowth into the prostheses was not affected, electron microscopic, histomorphometric, and radiologic analyses showed a clear difference in the formation of new bone around the prosthesis. Preoperative chemotherapy did not alter the formation of new bone, but specimens from animals treated postoperatively with cisplatin showed significantly less bone graft resorption and less new bone formation. Hence, the effect of cisplatin administration caused only a temporary delay, not a permanent effect, on extracortical capsule formation. The formation of extracortical bone and soft tissue might prevent debris-incised osteolysis and, therefore, prevent late complications by forming a tight capsule around the bone-prosthetic interface.