Factors affecting retention of estradiol-17 beta silicone rubber implants in ears of steers

A series of trials were conducted to identify the factors causing loss of estradiol-17 beta (E2-beta) silicone rubber implants from the ears of cattle and to evaluate methods of reducing this loss. Surface application of cattle feces to the ears before implanting resulted in an increase in loss of implants compared with the loss from dry, clean ears (30.6 vs 8.6%; P less than .05). Washing ears with a povidone-iodine antiseptic solution before implanting or treating implant sites with an antibiotic after implanting reduced (P less than .05) implant loss when ears were coated with the fecal slurry. Coating silicone rubber implants with .5 to 2 mg of oxytetracycline hydrochloride (OTC) reduced (P less than .0001) implant loss from 39.8 to 13.8% when ears were coated with fecal slurry. When silicone rubber implants with a 1.5-mg coating of OTC were implanted in cattle before submerging in a dipping vat, implant loss was reduced from 6.2 to 2.7%. In studies designed to evaluate mechanical factors affecting implant loss, implants that were placed in the middle of the ear in tight skin moved .79 cm toward the insertion site during a 14-d period after administration compared with 2.82 cm when placed in the base of the ear. When placed in the middle of the ear in tight skin, only 2 of 399 (.5%) implants were lost from steers submerged in a dipping vat immediately following implantation compared with 42 of 394 (10.7%) when placed in the base of the ear (P less than .0001).(ABSTRACT TRUNCATED AT 250 WORDS)     

Does surface anodisation of titanium implants change osseointegration and make their extraction from bone any easier?

OBJECTIVES: Titanium implants have a tendency for high bone-implant bonding, and, in comparison to stainless steel implants are more difficult to remove. The current study was carried out to evaluate, i) the release strength of three selected anodized titanium surfaces with increased nanohardness and low roughness, and ii) bone-implant bonding in vivo. These modified surfaces were intended to give improved anchorage while facilitating easier removal of temporary implants. MATERIAL AND METHODS: The new surfaces were referenced to a stainless steel implant and a standard titanium implant surface (TiMAX). In a sheep limb model, healing period was 3 months. Bone-implant bonding was evaluated either biomechanically or histologically. RESULTS: The new surface anodized screws demonstrated similar or slightly higher bone-implant-contact (BIC) and torque release forces than the titanium reference. The BIC of the stainless steel implants was significant lower than two of the anodized surfaces (p = 0.04), but differences between stainless steel and all titanium implants in torque release forces were not significant (p = 0.06). CONCLUSION: The new anodized titanium surfaces showed good bone-implant bonding despite a smooth surface and increased nanohardness. However, they failed to facilitate implant removal at 3 months.     

Mechanical testing of 3.5 mm locking and non-locking bone plates

Locking plate technologies are being developed in order to provide the surgeon with advantages over previous bone plate systems (both locking and non-locking). Locking plate systems possess inherent biological advantages in fracture fixation by preserving the periosteal blood supply, serving as internal fixators. It is important to consider the strength of each orthopaedic implant as an important selection criterion while utilizing the reported advantages of locking plate systems to prevent catastrophic fracture failure. Mechanical testing of orthopaedic implants is a common method used to provide a surgeon with insight on mechanical capabilities, as well as to form a standardized method of plate comparison. The purpose of this study was to demonstrate and to quantify observed differences in the bending strength between the LCP (Limited Contact Plate), LC-DCP, 3.5 mm Broad LC-DCP (Limited Contact Dynamic Compression Plate), and SOP (String of Pearls) orthopaedic bone plates. The study design followed the ASTM standard test method for static bending properties of metallic bone plates, which is designed to measure mechanical properties of bone plates subjected to bending, the most common loading encountered in vivo. Single cycle four point bending was performed on each orthopaedic implant. The area moment of inertia, bending stiffness, bending strength, and bending structural stiffness were calculated for each implant. The results of this study demonstrated significant differences (p<0.001) in bending strength and stiffness between the four orthopaedic implants (3.5 Broad LC-DCP>SOP>LCP=LC-DCP). The 3.5 mm LCP should be expected to provide in vivo strength and stiffness similar to a comparable LC-DCP. The SOP should provide strength and stiffness that is greater than a comparable LC-DCP but less than a 3.5 mm Broad LC-DCP.     

Principles of long bone fracture management.

The fixation of fractures in which one of the following primary devices is used: IM pins, bone plates, external skeletal fixators, can benefit from the additional application of any number of secondary devices. The secondary devices include cerclage, hemicerclage, or interfragmentary wires, skewer-pins, screws, and external skeletal fixators. These are indicated to facilitate the repair and eliminate the forces acting on the fracture site. A complete understanding of all the methods of fixation facilitates the selection of the proper implant or combination of implants. This information must be combined with the knowledge of how each device is most appropriately used depending on both the fracture type and fracture location. Taking into consideration all of these factors helps ensure that fracture healing occurs in the shortest possible time with the fewest complications. The ultimate goal of obtaining a full return to function may thereby be achieved.     

Complications of fractures repaired with plates and screws

The complications associated with bone plates and screws often are related to undersized or oversized implant selection, improper number of implants, inadequate or improper screw fixation, malpositioned plates or screws, poor plate contouring, and failure to use cancellous bone grafts when a gap is present at the fracture site. A thorough understanding of the principles of plate and screw application helps to avoid most problems. The surgeon must use an implant that will stabilize the fracture adequately during the healing process. The patient's activity levels must not exceed the mechanical limits of the implant. Methods to promote bone healing, such as using cancellous bone grafts when a deficit is present, help to protect the implant from fatiguing before the fracture is healed. Proper positioning and contouring of the implants are important to the successful application of plates and screws. It must be realized that even if all of these things are done, some complications still will occur. When that happens, the complication should be dealt within a manner that will allow the objectives of fracture treatment (a healed bone and normal limb function) to be achieved.     

Prosthetic Coxofemoral Joint Replacement in the Goose (Anser Sp.): II. Histologic and Mechanical Interface Evaluations

The interfacial tissue-implant healing reactions have been investigated in the goose to evaluate its suitability as an animal model for joint replacement implant studies. After various implantation periods, geese with one coxofemoral replacement hemiarthroplasty were evaluated for their gait performance and then sacrificed. The implantation sites and femora with implants were subjected to histologic studies, and the interfacial shear strength between the bone and implant was measured. The results were compared with findings reported in the literature on dog and man. Direct bone apposition was found in two geese with a firmly fixed implant. A connective tissue capsule surrounded those seven implant stems that were found to sit loosely in the femoral canal. Whereas the histologic findings were comparable to findings in dog and man, the interfacial shear stress was somewhat lower in the goose. Because of the histopathologically comparable findings of interfacial healing, the goose appears to present a suitable model to study bone implant tissue reactions. Further studies are necessary to determine seasonal-, age-, and sex-related bone tissue differences in the goose.     

Biomechanical characteristics of an implant used to secure semitendinosus-gracilis tendon grafts in a canine model of extra-articular anterior cruciate ligament reconstruction

Objective— To compare initial femoral fixation properties of a new implant, Graftgrab (GG), with 2 established methods of extra-articular femoral graft fixation, spiked washers (SW) and bone staples (ST).
Study Design— Experimental in vitro cohort study.
Methods— Canine semitendinosus–gracilis tendon grafts were passed through bone tunnels and fixed to the lateral surface of femoral condyles with spiked washers, bone staples, or new implant prototypes. The fixations were tested to failure with a single-cycle load at a rate of 50 mm/min. Failure and yield strength, stiffness, energy, and elongation were determined from load–displacement curves and failure modes were recorded.
Results— The graft failed midsubstance in 4 SW, 4 ST, and 1 GG fixations. In 3 SW, 3 ST, and 1 GG specimens, the graft slipped from the fixation. The graft ruptured at the clip (3) and the intra-articular (2) surface of the bone tunnel in the remaining GG specimens. There were no significant differences between fixation groups in femoral tunnel length, femoral width, or the mechanical properties evaluated.
Conclusions— The initial in vitro mechanical properties of the new fixation implant are comparable with those of spiked washers and bone staples.
Clinical Relevance— The initial mechanical performance of the new implant tested in this study was similar to those of comparable, established implants. The new implant is novel and may be useful for human anterior and veterinary cranial cruciate ligament graft reconstruction fixation.     

Reproductive performance of early postpartum Holstein cows where oestrus was synchronised following chronic GnRH agonist treatment

OBJECTIVE: The objectives of this study were: to compare the recovery of follicular development in early postpartum cows that had been treated for 7, 14 or 21 d with implants containing the GnRH agonist deslorelin; to evaluate the effectiveness of human chorionic gonadotrophin (hCG) for the induction of ovulation when a follicle was at least 10 mm in diameter following implant removal; and to compare final pregnancy rates for treated cows and untreated contemporaries. PROCEDURE: Within 3 d of calving Holstein cows were allocated to receive a single subcutaneous deslorelin implant to be left in place for either 7, 14 or 21 d, or to remain untreated as controls. Every deslorelin treated cow was monitored twice weekly for 35 d to determine the interval from implant removal to resumption of ovulation using serial transrectal ultrasonography and plasma progesterone assay. An injection of 1000 IU hCG was given to induce ovulation when a follicle of at least 10 mm diameter was first observed. Oestrous cycles of every cow were synchronised to facilitate artificial insemination (Al) at the start of the seasonally concentrated Al program and resynchronised for three rounds. Pregnancy testing was performed by ultrasonography 13 weeks after the first round of Al. RESULTS: Deslorelin implants inhibited ovulation for at least 10 d after they were removed. Ovarian follicles were smaller for the group that had implants for 21 d at the time of implant removal. Eighteen cows selected for treatment with hCG ovulated and formed multiple corpora lutea within 7 d. There was no effect of treatment duration on final pregnancy rates. After three rounds of AI the pooled final pregnancy rate for every cow that had received a deslorelin implant was similar to the rest of the herd (67% versus 63%; Deslorelin versus Herd, P > 0.1).The interval from start date of the AI program to conception was also unaffected by treatment (9.6 +/- 3.0 versus 14.8 +/- 1.7 d; Deslorelin versus Herd; P > 0.1). CONCLUSION: No significant effect was detected on the interval from implant removal to first ovulation by altering the duration of deslorelin treatment. Treatment with hCG when a follicle at least 10 mm in diameter was present induced ovulation in most cases. Although no significant improvement in fertility was found, a larger field trial using this model for induced anoestrous is necessary before any effect on fertility could confidently be stated.     

Fixation to the canine bone of artificial implant with new surface structure

Screw and laser (SL) column by making screw threads and forming small holes using laser irradiation on the base metal and conventional beads coating (BC) columns were embedded into the shaft of canine femurs, and compared the implant fixation to the host bone. The interfacial strength in SL columns was almost equivalent as BC columns, and bone-column contact rate was higher than BC columns significantly at twelve weeks after implantation. The newly devised SL surface had almost equivalent bone fixation strength comparable to the conventional BC surface. Also, this surface should provide a useful porous surface for use in artificial joints since there is no risk of surface structure detachment.     

Femoral bone adaptation to unstable long-term cemented total hip arthroplasty in dogs

OBJECTIVE: To evaluate femoral adaptation after unstable long-term cemented total hip arthroplasty (cTHA) in dogs. STUDY DESIGN: Clinical study. ANIMALS: Four dogs. METHODS: Paired femurs were examined from client-owned dogs that were donated to a retrieval program after death from causes unrelated to their cTHA. Mean (+/-SEM) dog age was 10.0+/-1.5 years and implant duration was 6.0+/-1.4 years. Implanted femurs had radiographic changes associated with implant loosening and gross mechanical instability at femur retrieval. Femurs were evaluated at 3 levels relative to implant length. Cortical area and medullary area were measured at each level, and cortical porosity was assessed at each level in 4 quadrants and in 3 regions. Implanted femurs were compared with the contralateral non-implanted femurs. RESULTS: Cortical area and cortical porosity were increased at all levels in femurs with unstable implants. Implanted femurs had increased porosity in all quadrants and regions at the proximal 2 levels, and increased porosity in only the cranial quadrant and mid-cortical area at the distal level, when compared with contralateral non-implanted femurs. Corresponding medullary areas were not different. CONCLUSIONS: Significant histomorphometric changes occur in femurs after unstable cTHA. The patterns of periosteal bone formation and endosteal bone resorption support mechanisms of stress shielding and wear debris-mediated osteolysis as factors that may contribute to femoral adaptation and implant loosening. CLINICAL RELEVANCE: Despite popularity and excellent return to function with cTHA, aseptic loosening remains a serious long-term complication. Substantial net bone loss and unfavorable environment with unstable cTHA may make revision surgery less successful.     

Implantation of canine umbilical cord blood-derived mesenchymal stem cells mixed with beta-tricalcium phosphate enhances osteogenesis in bone defect model dogs

This study was performed to evaluate the osteogenic effect of allogenic canine umbilical cord blood-derived mesenchymal stem cells (UCB-MSCs) mixed with beta-tricalcium phosphate (β-TCP) in orthotopic implantation. Seven hundred milligrams of β-TCP mixed with 1 × 10⁶ UCB-MSCs diluted with 0.5 ml of saline (group CM) and mixed with the same volume of saline as control (group C) were implanted into a 1.5 cm diaphyseal defect and wrapped with PLGC membrane in the radius of Beagle dogs. Radiographs of the antebrachium were made after surgery. The implants were harvested 12 weeks after implantation and specimens were stained with H&E, toluidine blue and Villanueva-Goldner stains for histological examination and histomorphometric analysis of new bone formation. Additionally, UCB-MSCs were applied to a dog with non-union fracture. Radiographically, continuity between implant and host bone was evident at only one of six interfaces in group C by 12 weeks, but in three of six interfaces in group CM. Radiolucency was found only near the bone end in group C at 12 weeks after implantation, but in the entire graft in group CM. Histologically, bone formation was observed around β-TCP in longitudinal sections of implant in both groups. Histomorphometric analysis revealed significantly increased new bone formation in group CM at 12 weeks after implantation (p < 0.05). When applied to the non-union fracture, fracture healing was identified by 6 weeks after injection of UCB-MSCs. The present study indicates that a mixture of UCB-MSCs and β-TCP is a promising osteogenic material for repairing bone defects.     

Effect of pre- and postweaning zeranol implant on steer calf performance

One hundred ninety-five steer calves were assigned to five zeranol implant treatment (trial 1). Treatments were no implants (0000), two implants during the finishing period (00XX), three implants during growing and finishing periods (0XXX), one implant at 1 to 2 mo of age during the suckling period and two during the finishing period (X0XX) or four implants (XXXX). The growing period implant was administered at weaning. Weaning weights (211 vs 208 kg) of implanted and nonimplanted suckling calves were not different (P greater than .05). Calves implanted at weaning, before shipment to the feedlot, had greater (P less than .05) weight loss in shipment than nonimplanted calves. In the feedlot, finishing-period daily gains of steers implanted in the growing and finishing period (0XXX) were greater (P less than .05) than gains of steers that had received a suckling period implant (X0XX and XXXX). Nonimplanted steer gains were less (P less than .05) than gains of steers from the other four treatment groups. Postweaning daily gains and final weights were 1.18 and 517 (0000), 1.26 and 533 (00XX), 1.32 and 551 (0XXX), 1.26 and 540 (X0XX) and 1.25 and 533 kg (XXXX), respectively. Gains and final weights of nonimplanted steers were less (P less than .05) than gains of steers implanted only in the feedlot growing and finishing periods (0XXX). In a second trial, 82 steers were assigned either to a 0XXX or XXXX implant scheme. Weaning weights were 11 kg greater (P less than .05) for the implanted steers.(ABSTRACT TRUNCATED AT 250 WORDS)     

Surgical Management of Proximal Splint Bone Fractures in the Horse

Fractures of Metacarpal and Metatarsal II and IV (the splint bones) were treated in 283 horses over an 11 year period. In 21 cases the proximal portion of the fractured bone was stabilized with metallic implants. One or more cortical bone screws were used in 11 horses, and bone plates were applied in 11 horses. One horse received both treatments. Complications of screw fixation included bone failure, implant failure, radiographic lucency around the screws, and proliferative new bone at the ostectomy site. Only two of the horses treated with screw fixation returned to their intended use. Complications of plate fixation included partial fixation failure (backing out of screws), wound drainage, and proliferative bony response around the plate. Six of the 11 horses treated by plate fixation returned to their intended use. The authors recommend consideration of plate fixation techniques for repair of fractures in the proximal third of the splint bone.     

Comparing the osteogenic potential of canine mesenchymal stem cells derived from adipose tissues, bone marrow, umbilical cord blood, and Wharton's jelly for treating bone defects

Alternative sources of mesenchymal stem cells (MSCs) for replacing bone marrow (BM) have been extensively investigated in the field of bone tissue engineering. The purpose of this study was to compare the osteogenic potential of canine MSCs derived from adipose tissue (AT), BM, umbilical cord blood (UCB), and Wharton''s jelly (WJ) using in vitro culture techniques and in vivo orthotopic implantation assays. After canine MSCs were isolated from various tissues, the proliferation and osteogenic potential along with vascular endothelial growth factor (VEGF) production were measured and compared in vitro. For the in vivo assay, MSCs derived from each type of tissue were mixed with β-tricalcium phosphate and implanted into segmental bone defects in dogs. Among the different types of MSCs, AT-MSCs had a higher proliferation potential and BM-MSCs produced the most VEGF. AT-MSCs and UCB-MSCs showed greater in vitro osteogenic potential compared to the other cells. Radiographic and histological analyses showed that all tested MSCs had similar osteogenic capacities, and the level of new bone formation was much higher with implants containing MSCs than cell-free implants. These results indicate that AT-MSCs, UCB-MSCs, and WJ-MSCs can potentially be used in place of BM-MSCs for clinical bone engineering procedures.     

Expressions of vascular endothelial growth factor and basic fibroblast growth factor in tumors induced by two different cloned cell lines established from transplantable rat malignant fibrous histiocytoma

In order to establish base-line data on angiogenic factors in development of mesenchymal tumors, expressions of vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) in implanted MT-8 and MT-9 tumors, both derived from a transplantable malignant fibrous histiocytoma (MFH) in the F344 rat, were investigated by immunohistochemistry and Western blotting method. MT-8 and MT-9 tumors were developed in syngeneic rats by implant of a tumor tissue fragment. MT-8 tumors were examined on post-implantation (PI) days 3, 6, 9 and 17, and MT-9 tumors were on PI days 9, 14, 17 and 23. The growth of MT-8 tumors was faster than that of MT-9 tumors. Histologically, MT-8 tumors were features of undifferentiated sarcomas, whereas MT-9 tumors exhibited a typical storiform growth pattern of MFH. Immunohistochemically, all cells constituting MT-8 and MT-9 tumors reacted with antibodies to VEGF and bFGF, indicating production of these factors by mesenchymal neoplastic cells. However, there were no marked differences in these immunoreactions between tumors examined. Thus, the bands obtained in the Western blotting methods were densitometrically scanned. The expression levels of VEGF and bFGF gradually increased PI day 3 to 9 in MT-8 tumors and PI day 9 to 17 in MT-9 tumors. On last examination day, the levels of bFGF in both tumors and of VEGF in MT-9 tumors decreased, but the VEGF expression level in MT-8 tumors was still increased. These findings indicated that VEGF and bFGF may contribute cooperatively to angiogenesis in an early growth of mesenchymal tumor development.     

Effects of deslorelin acetate implants in horses: single implants in stallions and steroid-treated geldings and multiple implants in mares

Three experiments were performed to test the following hypotheses: 1) stallions and/or progesterone-estradiol-treated geldings could serve as models for the effects of a single implant of the GnRH analog, deslorelin acetate, on LH and FSH secretion by mares; and 2) multiple implants of deslorelin acetate could be used as a means of inducing ovarian atrophy in mares for future study of the mechanisms involved in the atrophy observed in some mares after a single implant. In Exp. 1, nine light horse stallions received either a single deslorelin implant (n = 5) or a sham injection (n = 4) on d 0. In Exp. 2, 12 geldings received daily injections of progesterone on d -20 through -4, followed by twice-daily injections of estradiol on d -2 to 0. On the morning of d 0, geldings received either a single deslorelin implant (n = 6) or a sham injection (n = 6). Daily injections of progesterone were resumed on d 2 through 15. In Exp. 1, plasma LH and FSH were elevated (P < 0.05) in the treatment group relative to controls at 4, 8, and 12 h after implant insertion. In the treated stallions, FSH was decreased (P < 0.05) on d 3 to 13, and LH was decreased on d 6 to 13. In Exp. 2, plasma LH and FSH were elevated (P < 0.05) at 4,8, and 12 h after deslorelin implant insertion. Plasma LH was suppressed (P < 0.05) below controls on d 2 to 7, 9, and 11 to 15; plasma FSH was suppressed (P < 0.05) on d 4 to 15. In Exp. 3, 21 mares were used to determine whether multiple doses of deslorelin would cause ovarian atrophy. Mares received one of three treatments: 1) sham injections; 2) three implants on the first day; or 3) one implant per day for 3 d (n = 7 per group). Treatment with multiple implants increased (P < 0.05) the interovulatory interval by 14.8 d and suppressed (P < 0.01) LH and FSH concentrations for approximately 25 d; no mare exhibited ovarian atrophy. In conclusion, after an initial short-term increase in LH and FSH secretion, deslorelin implants caused long-term suppression of both gonadotropins in stallions as well as in geldings treated with progesterone and estradiol to mimic the estrous cycle. It is likely that either of these models may be useful for further study of this suppression in horses. Although multiple implants in mares suppressed gonadotropin secretion longer than a single implant, the lack of ovarian atrophy indicates that the atrophy observed after a single implant in previous experiments was likely due to the susceptibility of individual mares.     

Assessment of stiffness and strength of 4 different implants available for equine fracture treatment: a study on a 20 degrees oblique long-bone fracture model using a bone substitute

OBJECTIVE: To compare the mechanical properties of 4 stabilization methods for equine long-bone fractures: dynamic compression plate (DCP), limited contact-DCPlate (LC-DCP), locking compression plate (LCP), and the clamp-rod internal fixator (CRIF--formerly VetFix). STUDY DESIGN: In vitro mechanical study. SAMPLE POPULATION: Bone substitute material (24 tubes) was cut at 20 degrees to the long axis of the tube to simulate an oblique mid-shaft fracture. METHODS: Tubes were divided into 4 groups (n=6) and double plated in an orthogonal configuration, with 1 screw of 1 implant being inserted in lag fashion through the "fracture". Thus, the groups were: (1) 2 DCP implants (4.5, broad, 10 holes); (2) 2 LC-DCP implants (5.5, broad, 10 holes); (3) 2 LCP implants (4.5/5.0, broad, 10 holes) and 4 head locking screws/plate; and (4) 2 CRIF (4.5/5.0) and 10 clamps in alternating position left and right of the rod. All constructs were tested in 4-point bending with a quasi-static load until failure. The implant with the interfragmentary screw was always positioned on the tension side of the construct. Force, displacement, and angular displacement at the "fracture" line were determined. Construct stiffness under low and high loads, yield strength, ultimate strength, and maximum angular displacement were determined. RESULTS: None of the implants failed; the strength of the bone substitute was the limiting factor. At low loads, no differences in stiffness were found among groups, but LCP constructs were stiffer than other constructs under high loads (P=.004). Ultimate strength was lowest in the LCP group (P=.01), whereas yield strength was highest for LCP constructs (409 N m, P=.004). CRIF had the lowest yield strength (117 N m, P=.004); no differences in yield strength (250 N m) were found between DCP and LC-DCP constructs. Differences were found for maximum angular displacement at the "fracture" line, between groups: LPC相似文献   

Orthogonal view analysis for evaluating the femoral component position of total hip implants in dogs using postoperative radiographs

OBJECTIVE: To show the ability to obtain repeatable, accurate, quantitative data to assess the position of the femoral component of canine total hip implants using postoperative radiographs. STUDY DESIGN: Cadaveric study and clinical trial. ANIMALS: Five cadaveric canine femurs and 4 patients. METHODS: Femoral implants were placed into 5 cadaveric canine femurs in predetermined locations. Orthogonal radiographs were taken of each femur at 10 degrees intervals as they were moved through a natural range of hip motion. An assessment of implant position was made with each set of radiographs and analyzed to observe significant inconsistencies in the values obtained when the femur was repositioned. Three investigators positioned and radiographed the hips of 4 client-owned dogs that had total hip arthroplasty (THA). Each investigator obtained a set of orthogonal radiographic views from which implant position was measured. The measurements obtained from each investigator's set of radiographs were statistically analyzed to evaluate for interobserver differences. RESULTS: The methods described indicate that consistent data regarding femoral implant placement can be obtained from postoperative radiographs of THA patients. Under most circumstances, change in position of the femur did not significantly affect femoral implant measurements. There were no significant differences noted among values obtained by different investigators. CONCLUSIONS: Measurements based on the femoral and implant axes obtained from orthogonal radiographic views of the femur provide a means for obtaining accurate and consistent quantitative data regarding femoral implant position using postoperative radiographs of canine THA patients. CLINICAL RELEVANCE: Acquisition of quantitative information about femoral implant position using postoperative radiographs will facilitate development of a readily available data source. This information, attainable in a clinical setting, may help identify elements of implant position that are important in determining the clinical outcome of THA in dogs.     

A one-piece ocular drainage implant for glaucoma surgery: a preliminary report.

A one-piece silicone filtration implant for glaucoma surgery was evaluated in 18 normotensive rabbits. During the follow-up period of 60 days the function of the implant and the effect of the implant on intraocular pressure (IOP) and local reaction in operated eyes were examined. Mean IOP in operated eyes during the whole follow-up period stayed in a level that was statistically significantly (p < 0.001) lower than the preoperative starting value. Despite of a slight inflammatory reaction in the immediate postoperative period the implants were well tolerated. No marked foreign body reaction were noted around the implants in histological sections. In 3 eyes the implants had to be removed due to complications caused by surgical technique.     

Effects of implant regimens (trenbolone acetate-estradiol administered alone or in combination with zeranol) and vitamin D3 on fresh beef color and quality

In the first oftwo experiments, 123 calf-fed steers were used over a 2-yr period to evaluate the effects of trenbolone acetate (TBA)-based implants administered alone or in combination with zeranol implants on fresh beef muscle quality, color, and physiological maturity of the carcass. Implant treatments decreased (P < 0.05) a* values (d 0 and d 3 of retail display) and b* values (d 0, d 1, and d 3 of retail display) after 14 d of aging. Carcasses from cattle initially implanted with Revalor-S and reimplanted with Revalor-S on d 60 of the finishing period showed increased lean and bone maturity scores and ash content of the 9th to 11th thoracic buttons and Warner-Bratzler shear force values (WBS) compared to those initially implanted with Ralgro and subsequently reimplanted with Revalor-S or control cattle. In addition, implants decreased (P < 0.05) marbling, percentage of the carcasses grading Choice, and kidney, pelvic, and heart fat (KPH). Implant treatments increased (P < 0.05) ADG, hot carcass weights, and longissimus muscle (LM) area. In the second experiment over a 2-yr period, 166 steers fed as yearlings were allotted to one of two implant treatments and one of two vitamin D3 preharvest supplementation treatments. Implanted steers had heavier (P < 0.05) final body weights and higher (P < 0.05) ADG, less (P < 0.05) KPH fat, and larger (P < 0.05) LM. Also, implanted steers had more (P < 0.05) advanced bone maturity scores, higher (P < 0.05) ash content of the 9th to 11th thoracic buttons, and higher (P < 0.05) WBS values on 5-d postmortem loin steaks. Vitamin D3 feeding decreased (P < 0.05) final live weight, ADG (P < 0.05), and LM (P < 0.05), but did not significantly improve WBS values. In Experiment 2, neither implant treatment nor vitamin D3 supplementation had significant effects on L*, a*, or b* values of muscles in steaks before or during simulated retail display.