Evaluation of zoledronate, cytochalasin-D, and desferrioxamine on osseointegration in an intra-medullary femoral implant model.

OBJECTIVE: The rise in primary and revision surgeries utilizing joint replacement implants suggest the need for more reliable means of promoting implant fixation. Zoledronate-(Zol), cytochalasin-D-(cytoD), and desferrioxamine-(DFO) have been shown to enhance mesenchymal stem cell (MSC) differentiation into osteoblasts promoting bone formation. The objective was to determine whether Zol, cytoD, and DFO can improve fixation strength and enhance peri-implant bone volume about intra-medullary femoral implants. METHODS: 48 Sprague-Dawley female rats were randomized into four treatments, saline-control or experimental: Zol-(0.8 µg/µL), cytoD-(0.05 µg/µL), DFO-(0.4 µg/µL). Implants were placed bilaterally in the femoral canals following injection of treatment solution and followed for 28 days. Mechanical push-out testing and micro-CT were our primary evaluations, measuring load to failure and bone volume. Qualitative evaluation included histological assessment. Data was analyzed with a one-way ANOVA with Holm-Sidak mean comparison testing. RESULTS: Significant results included pushout tests showing an increase in maximum energy for Zol (124%) and cytoD (82%); Zol showed an increase in maximum load by 48%; Zol micro-CT showed increase in BV/TV by 35%. CONCLUSIONS: Our findings suggest that locally applied Zol and cytoD enhance implant mechanical stability. Bisphosphonates and actin regulators, like cytoD, might be further investigated as a new strategy for improving osseointegration.

Bone changes after short-term whole body vibration are confined to cancellous bone.

OBJECTIVE: This study assessed femur properties in 80 adult female rats exposed to a range of whole body vibration amplitudes at 45 Hz over five weeks. Our hypothesis was that an optimal amplitude for whole body vibration would be apparent and would result in increased bone strength. METHODS: Animals were treated in five amplitude groups (0 g, 0.15 g, 0.3 g, 0.6 g, and 1.2 g peak), for 15 minutes per day, five days per week, for five weeks. Femur strength was assessed via: (1) three-point bending of the shaft, (2) cantilever bending of the neck, and (3) indentation of distal cancellous bone. Femoral bone mineral density, plasma prostaglandin E2 (PGE2) concentrations, cartilage thickness, and histopathologic properties were measured. RESULTS: Vibration doubled (P=0.039) cancellous bone stiffness in the 0.6 g and 1.2 g groups and induced a 74% increase in PGE2 concentrations (P=0.007). However, femoral densitometry and strength of the neck and shaft were unchanged and the cancellous bone indentation strength did not differ statistically (P=0.084). Cartilage thickness of vibrated groups at the medial condyle did not increase significantly (P=0.142) and the histopathologic grade did not change. There was no definitive optimal vibration amplitude. CONCLUSION: The benefits of vibration therapy over five weeks were confined to cancellous bone.

Some observations on the subfibrillar structure of collagen fibrils as noted during treatment with NKISK and cathepsin G with mechanical agitation.

We observed the structure of collagen fibrils in rat tail tendons after treatment with NKISK and cathepsin G. NKISK is a pentapeptide that has been previously shown to bind fibronectin, while cathepsin G is a serine protease that cleaves fibronectin but not type I collagen. In tendons treated with NKISK, fibrils were seen to extensively dissociate into smaller-diameter subfibrils. These subfibrils were homogeneous in diameter with an average diameter of 26.3 ± 5.8 nm. Similar, although less extensive, dissociation into subfibrils was found in tendons treated with cathepsin G. The average diameter of these subfibrils was 24.8 ± 4.9 nm. The ability of NKISK and cathepsin G to release subfibrils at physiological pH without harsh denaturants may enhance the study of the subfibrillar structure of collagen fibrils.

Locally delivered minocycline microspheres do not impair osseointegration of titanium implants in a rat femur model.

BACKGROUND: The purpose of this study was to determine whether intramedullary administration of extended-release minocycline microspheres would affect osseointegration. METHODS: Twenty-two rats were randomized to minocycline or saline femoral intramedullary injection followed by implantation of titanium alloy rods. Following euthanasia at four-weeks, pushout testing was performed and bone-volume-fraction assessed. RESULTS: Pushout strength was marginally greater in minocycline-treated implants (122.5 ± 39.1 N) compared to saline (96.9 ± 26.1 N) (P = 0.098). No difference was observed in energy to maximum load, mean stiffness, or peri-implant bone-volume-fraction (P > 0.05). CONCLUSIONS: Peri-implant minocycline administration did not impair implant fixation strength or peri-implant bone-volume, supporting its potential utility as an adjunct to intramedullary implants.

Hemorrhage in pelvic fractures does not correlate with fracture length.

BACKGROUND: To analyze whether hematogenous marrow bleeding is the major source of hemorrhage after fractures of the pelvic ring. DESIGN: Retrospective cohort study. SETTING: Academic Level I trauma center. PATIENTS OR PARTICIPANTS: Three hundred seven consecutive pelvic ring injuries from January 1, 2000 to December 31, 2003 were evaluated. After exclusion for age, significant nonpelvic hemorrhage sources, and delayed transfer to this institution, 72 patients remained. MAIN OUTCOME MEASUREMENTS: Pelvic injuries were classified as fractures, fracture dislocations, or pure dislocations. These classifications were correlated to change in hematocrit between assumed preinjury and final hematocrit readings, correcting for blood transfused. RESULTS: The dislocation group had a greater change in hematocrit than the fracture group (2.1%), though not statistically significant. No significant correlations were found between change in hematocrit and length of fracture lines. CONCLUSIONS: Pelvic fracture surfaces may be sources of bleeding in pelvic injuries, but the fact that bleeding is similar in fractures and dislocations indicates fracture surfaces do not constitute the primary source. Based on our analysis one cannot reliably predict pelvic hemorrhage based on A/P radiograph assessments, such as fracture type.

Reconstruction of lateral trochlear defect with radial head autograft.

A novel procedure has been developed to address severe fractures of the lateral trochlea and capitellum when open reduction and internal fixation is not practical and patient factors preclude the use of total elbow arthroplasty. We present 3 patients in whom an ipsilateral radial head autograft was used to reconstruct the lateral trochlea, restoring both function and stability of the elbow.

Deferoxamine-Soaked Suture Improves Angiogenesis and Repair Potential After Acute Injury of the Chicken Achilles Tendon.

BACKGROUND: A major obstacle to the treatment of soft tissue injuries is the hypovascular nature of the tissues. Deferoxamine (DFO) has been shown to stimulate angiogenesis by limiting the degradation of intracellular hypoxia-inducible factor 1-alpha. HYPOTHESIS: DFO-saturated suture would induce angiogenesis and improve the markers of early healing in an Achilles tendon repair model. STUDY DESIGN: Controlled laboratory study. METHODS: Broiler hens were randomly assigned to the control (CTL) group or DFO group (n = 9 per group). The right Achilles tendon was partially transected at its middle third. The defect was surgically repaired using 3-0 Vicryl suture soaked in either sterile water (CTL group) or 324 mM DFO solution (DFO group). All animals were euthanized 2 weeks after the injury, and the tendon was harvested. Half of the tendon was used to evaluate angiogenesis via hemoglobin content and tissue repair via DNA content and proteoglycan (PG) content. The other half of the tendon was sectioned and stained with hematoxylin and eosin, safranin O, and lectin to evaluate vessel density. RESULTS: Hemoglobin content (percentage of wet tissue weight) was significantly increased in the DFO group compared with the CTL group (0.081 ± 0.012 vs 0.063 ± 0.016, respectively; P = .046). DNA content (percentage of wet tissue weight) was also significantly increased in the DFO group compared with the CTL group (0.31 ± 0.05 vs 0.23 ± 0.03, respectively; P = .024). PG content (percentage of wet tissue weight) was significantly decreased in the DFO group compared with the CTL group (0.26 ± 0.02 vs 0.33 ± 0.08, respectively; P = .035). Total chondroid area (number of vessels per mm2 of tissue area evaluated) was significantly decreased in the DFO group compared with the CTL group (17.2 ± 6.6 vs 24.6 ± 5.1, respectively; P = .038). Articular zone vessel density (vessels/mm2) was significantly increased in the DFO group compared with the CTL group (7.1 ± 2.5 vs 2.1 ± 0.9, respectively; P = .026). CONCLUSION: The significant increase in hemoglobin content as well as articular zone vessel density in the DFO group compared with the CTL group is evidence of increased angiogenesis in the fibrocartilaginous region of the tendon exposed to DFO. The DFO group also displayed a significantly greater level of DNA and significantly lower level of PG, suggesting enhanced early healing by fibrous tissue formation. CLINICAL RELEVANCE: Stimulating angiogenesis by DFO-saturated suture may be clinically useful to improve healing of poorly vascularized tissues.

Improved osseointegration with as-built electron beam melted textured implants and improved peri­implant bone volume with whole body vibration.

Transcutaneous osseointegrated prostheses provide stable connections to the skeleton while eliminating skin lesions experienced with socket prosthetics. Additive manufacturing can create custom textured implants capable of interfacing with amputees' residual bones. Our objective was to compare osseointegration of textured surface implants made by electron beam melting (EBM), an additive manufacturing process, to machine threaded implants. Whole body vibration was investigated to accelerate osseointegration. Two cohorts of Sprague-Dawley rats received bilateral, titanium implants (EBM vs. threaded) in their tibiae. One cohort comprising five groups vibrated at 45 Hz: 0.0 (control), 0.15, 0.3, 0.6 or 1.2 g was followed for six weeks. Osseointegration was evaluated through torsional testing and bone volume fraction (BV/TV). A second cohort, divided into two groups (control and 0.6 g), was followed for 24 days and evaluated for resonant frequency, bone-implant contact (BIC) and fluorochrome labeling. The EBM textured implants exhibited significantly improved mechanical stability independent of vibration, highlighting the benefits of using EBM to produce custom textured surfaces. Bone formation on and around the EBM textured implants increased compared to machined implants, as seen by BIC and fluorescence. No difference in torque, BIC or fluorescence among vibration levels was detected. BV/TV significantly increased at 0.6 g compared to control for both implant types.

Locally administered antibiotics for prophylaxis against surgical wound infection. An in vivo study.

BACKGROUND: Currently, the standard for prophylaxis against surgical infection consists of perioperative systemic antibiotics. In this study, we investigated the relative efficacy of various methods of antibiotic delivery for the prevention of surgical wound infections. We hypothesized that sustained release of local antibiotics inside the wound cavity by a drug delivery system would be more effective than systemically administered antibiotics. METHODS: Using a rat model, we inoculated a surgical wound in the quadriceps muscle with 8.0 x 10(5) colony-forming units of Staphylococcus aureus and then administered one of seven types of treatment: no treatment (control), bacitracin irrigation, calcium sulfate flakes, systemic gentamicin, local aqueous gentamicin, local gentamicin-loaded calcium sulfate flakes, and a combination of local gentamicin-loaded calcium sulfate and systemic gentamicin. The seven treatment groups consisted of ten rats each. To further evaluate a trend, the group treated with systemic gentamicin and the one treated with local gentamicin solution were extended to include twenty-five and twenty-seven rats, respectively. At forty-eight hours postoperatively, specimens from the wounds were obtained for quantitative culture. RESULTS: The control group, the group treated with bacitracin irrigation, and the one treated with plain calcium sulfate had very high bacterial counts and high mortality rates while the groups treated with gentamicin had low bacterial counts and a 100% survival rate. Local gentamicin was significantly more effective than systemic gentamicin in reducing bacterial counts. CONCLUSIONS: The gentamicin-loaded calcium sulfate flakes did not result in bacterial counts that were significantly lower than those following systemic administration of gentamicin, which refuted our hypothesis. However, gentamicin solution injected directly into the closed wound did result in levels of bacteria that were significantly lower than those following treatment with the systemic gentamicin.

The effects of common anti-inflammatory drugs on the healing rat patellar tendon.

BACKGROUND: Tendon injuries that occur at the osteotendinous junction are commonly seen in clinical practice and range from acute strain to rupture. Nonsteroidal anti-inflammatory drugs are often prescribed in the treatment of these conditions, but the effect that these agents may have on the healing response at the bone-tendon junction is unclear. HYPOTHESIS: In response to an acute injury at the osteotendinous junction, the healing patellar tendon will have inferior biomechanical properties with administration of anti-inflammatory drugs as compared with acetaminophen and control. STUDY DESIGN: Controlled laboratory study. METHODS: A total of 215 Sprague-Dawley rats underwent transection of the patellar tendon at the inferior pole of the patella, which was subsequently stabilized with a cerclage suture. The animals were then randomized into 7 groups and administered 1 of the following analgesics for 14 days: ibuprofen, acetaminophen, naproxen, piroxicam, celecoxib, valdecoxib, or control. At 14 days, all animals were sacrificed, and the extensor mechanism was isolated and loaded to failure. Biochemical analysis of the repair site tissue was performed. Animal activity throughout the study was monitored using a photoelectric sensor system. RESULTS: The control group demonstrated greater maximum load compared with the celecoxib, valdecoxib, and piroxicam groups (P < .05). The acetaminophen and ibuprofen groups were also significantly stronger than the celecoxib group (P < .05) but not statistically different than the control group. A total of 23 specimens had failure of the cerclage suture with the following distribution: control (0/23), ibuprofen (0/23), acetaminophen (0/24), naproxen (3/24), piroxicam (4/24), celecoxib (6/22), and valdecoxib (10/24). The difference in distribution of the failures was significant (P < .001). CONCLUSIONS: Anti-inflammatory drugs, with the exception of ibuprofen, had a detrimental effect on healing strength at the bone-tendon junction as demonstrated by decreased failure loads and increased failures of the cerclage suture. Acetaminophen had no effect on healing strength. The biomechanical properties paralleled closely with the total collagen content at the injury site, suggesting that these agents may alter healing strength by decreasing collagen content. CLINICAL RELEVANCE: Selective and nonselective cyclooxygenase (COX) inhibitors should be used judiciously in the acute period after injury or surgical repair at the bone-tendon junction.

Use of an independent skeletal distractor in hip arthroscopy.

Distraction of the hip joint plays an important role in hip arthroscopy by improving visualization of and access to intra-articular structures. Distraction is usually performed by use of a standard traction table and foot plate, with the patient in either the supine or lateral position. Between 1996 and 2005 at our institution, we have used an inexpensive, independent, sterile radiolucent skeletal distractor device to perform hip arthroscopy in the lateral position successfully in 156 cases for a variety of indications and procedures. The device consists of a perineal post, a longitudinal distraction beam, and a telescoping distraction carriage fitted with a screw drive for attachment to a distal femoral K-wire. Skeletal traction is applied against the perineal post through the K-wire via the action of the distraction carriage and fine-tuned with the screw drive, affording excellent visualization of intra-articular structures. The use of this device during hip arthroscopy negates the need for a fracture table, enables the surgeon to remain sterile and still manipulate the traction apparatus intraoperatively, and provides for simultaneous hip and knee flexion to relax the sciatic nerve. Its modular design and small size make hip arthroscopy possible in almost all settings, including outpatient operating rooms.

Osseointegration of Coarse and Fine Textured Implants Manufactured by Electron Beam Melting and Direct Metal Laser Sintering.

Osseointegrated implants transfer loads from native bone to a synthetic joint and can also function transdermally to provide a stable connection between the skeleton and the prostheses, eliminating many problems associated with socket prostheses. Additive manufacturing provides a cost-effective means to create patient-specific implants and allows for customized textures for integration with bone and other tissues. Our objective was to compare the osseointegration strength of two primary additive manufacturing methods of producing textured implants: electron beam melting (EBM) (mean Ra = 23 µm) and direct metal laser sintering (DMLS) (mean Ra = 10 µm). Due to spatial resolution, DMLS can produce surfaces with a roughness comparable to EBM. Two cohorts of Sprague-Dawley rats received bilateral, titanium implants in their distal femurs and were followed for 4 weeks. The first-cohort animals received EBM implants transcortically in one femur and a DMLS implant in the contralateral femur. The second cohort received DMLS implants (either fine textured or coarse textured to mimic EBM) in the intramedullary canal of each femur. Osseointegration was evaluated through mechanical testing and micro-computed tomography (bone volume fraction [BV/TV] and bone-implant contact [BIC]). The fixation strength of coarse textured implants provided superior interlocking relative to fine textured implants without affecting BV/TV or BIC in both cohorts. Coarse EBM implants in a transcortical model demonstrated an 85% increase in removal torque relative to the fine DMLS textured implants. The thrust load in the intramedullary model saw a 35% increase from fine to coarse DMLS implants.

Traumatic wound debridement: a comparison of irrigation methods.

OBJECTIVES: To test wound debridement efficacy and soft tissue damage produced by high-pressure pulsatile lavage (HPPL), suction irrigation, and bulb syringe irrigation. DESIGN: Randomized trial in an in vitro model. SETTING: Medical school orthopaedic department. PATIENTS/PARTICIPANTS: No patients were used in this study. INTERVENTION: Beef flank steaks (100-g +/- 10-g) were divided into 8 test groups and incised uniformly. Four test groups were contaminated with 2 g of rock dust and 4 were not. The specimens were then treated as follows: nothing (control), bulb irrigation, suction irrigation, or HPPL. MAIN OUTCOME MEASUREMENTS: Runoff from the irrigation was collected, filtered, lyophilized, and ashed to allow for quantitative determination of organic and inorganic material removed from the wound by each irrigation method. Digital photographs of the tissue samples were subjected to blinded grading on a scale of 1 to 5 to assess macroscopic soft tissue damage. RESULTS: Qualitatively, tissue samples treated with HPPL consistently received worse grades for tissue damage than samples in any other experimental group. Quantitative soft tissue damage analysis revealed that significantly more organic material was removed from samples treated with HPPL (141.3 +/- 58.9 mg) than those treated with bulb syringe (50.7 +/- 28.6 mg) or suction irrigation (108.7 +/- 174.5 mg). Surprisingly, significantly less inorganic contaminant was removed from tissue samples treated with HPPL (1549.6 +/- 77.3 mg) than those treated with bulb syringe (1834.9 +/- 39.1 mg) or suction irrigation (1827 +/- 39.4 mg). CONCLUSIONS: There has been some concern regarding damage produced by HPPL. According to our quantitative soft tissue damage data, tissue treated by HPPL was damaged significantly more than tissue treated with bulb syringe or suction irrigation. Our qualitative tissue damage grade data showed that HPPL treated test groups appeared more damaged than other irrigation groups. Surprisingly, HPPL removed significantly less inorganic contaminant than other debridement methods, and it is proposed that HPPL may drive some contaminants deeper into the tissue rather than removing them. This study seems to support the concept that suction and sharp debridement, as practiced by most surgeons, may remove foreign bodies well without the use of HPPL.

A technique for correction of equinus contracture using a wire fixator and elastic tension.

Equinus contracture often is a complication of trauma, burns, or neurologic deficit. Many patients with contractures secondary to trauma or burns have poor soft tissue, which makes invasive correction a less appealing option. The Ilizarov external fixator has been used as a less invasive attempt to correct equinus contracture. We describe our "dynamic" technique and present a clinical patient series using a variation of the unconstrained Ilizarov technique, which uses elastic bands rather than threaded rods to supply the corrective force.

Hip arthroscopy to remove loose bodies after traumatic dislocation.

OBJECTIVES: This study was designed to review the incidence of arthroscopically detected intra-articular loose bodies found in patients after traumatic hip dislocation or small acetabular wall fracture which would not otherwise be treated without surgery. DESIGN: Retrospective review. SETTING: Level 1 academic trauma center. PATIENTS: Thirty-six patients who sustained traumatic hip injuries and subsequently had 39 hip arthroscopies between November 1997 and January 2004 were reviewed. INTERVENTION: All patients had standard AP pelvis x-rays and CT scans performed. At our institution, patients with hip dislocations or acetabular wall fractures not otherwise requiring surgery are routinely offered hip arthroscopy to remove loose bodies. The radiographs were reviewed to determine incidence of loose bodies or nonconcentric reduction before hip arthroscopy. Chart review provided incidence of loose bodies found during arthroscopy. MAIN OUTCOME MEASUREMENTS: Comparison was made between radiographic data obtained preoperatively and operative findings. RESULTS: Loose bodies were found in the hips of 33 of 36 patients (92%) who were arthroscoped. Loose bodies were found in 7 of 9 cases (78%) in which standard radiographic studies (AP pelvis x-rays and CT scan) found no loose bodies and a concentric reduction. CONCLUSIONS: Loose bodies are routinely present after closed treatment of hip dislocations or wall fractures not otherwise requiring surgery, even when radiographs are negative. Hip arthroscopy may be indicated for loose body removal when open treatment is not otherwise necessary.

Flexible intramedullary nail removal using a broken screw removal set.

The use of flexible titanium intramedullary nails for management of pediatric long bone fractures and some adult fractures has become common. Nail removal after union can be challenging and often requires a larger exposure than nail placement to allow the insertion of grasping devices, such as pliers. A percutaneous technique for the removal of flexible intramedullary nails using extraction bolts from a broken screw removal set is presented. The technique is especially useful when the end of the nail is not prominent and where a hollow reamer from the same set can expose the nail end for the extraction bolt to be used.

Debridement of cancellous bone: a comparison of irrigation methods.

OBJECTIVE: This study tests the bone debridement efficacy and damage to cancellous bone produced by different wound irrigation methods. METHODS: Cancellous bone slices of bovine distal femurs (3 cm x 3 cm) were divided into eight test groups and scored with a saw in a latticed pattern. Four test groups were contaminated with 1.0 g rock dust and four were not. The specimens were then treated as follows: no treatment (control), bulb irrigation, brush-suction irrigation, or high-pressure pulsatile lavage (HPPL). Runoff from the irrigation was collected, filtered, lyophilized, and ashed to allow for quantitative determination of organic and inorganic material removed from the bone by each irrigation method. The bone samples were subjected to blinded grading on two five-point scales to assess: 1) macroscopic tissue damage and 2) amount of contaminant remaining following treatment. RESULTS: Significantly more (P < or = 0.05) mean organic material was removed from samples treated with HPPL (744.8 +/- 120.0 mg) than with bulb syringe (115.2 +/- 11.9 mg) or brush-suction irrigation (95.1 +/- 9.2 mg). Brush-suction irrigation removed statistically significantly more (P < or = 0.05) of the 1.0 g of initial inorganic contaminant (937.7 +/- 6.3 mg) than bulb syringe irrigation (866.2 +/- 30.1 mg), while HPPL (900.2 +/- 19.0 mg) did not. CONCLUSIONS: Past studies have shown HPPL to damage both soft tissue and bone structure. The tissue damage that HPPL produces has been accepted in the past in exchange for its presumed superiority in contaminant removal. In this study, HPPL damaged samples more than other irrigation methods by removing significantly more organic material from them. However, HPPL and bulb syringe removed a statistically similar amount of inorganic contaminant, while brush-suction irrigation removed a significantly greater amount of inorganic contaminant than bulb syringe. It is proposed that HPPL may drive some contaminants deeper into the tissue rather than removing them, rendering HPPL not only more deleterious to bone structure and healing, but also less efficacious at removing contaminant than brush-suction irrigation.

The effect of levodopa or levodopa-carbidopa (sinemet) on fracture healing.

OBJECTIVES: Levodopa (L-dopa) and L-dopa/carbidopa were evaluated to determine their effectiveness in the stimulation of bone healing of fractures at risk for nonunions. METHODS: Forty-two retired breeder female Sprague-Dawley rats were divided into 2 experimental groups and 1 control. Thirty-six rats were evaluated for results. The right femur of each rat was fractured and an intramedullary omega pin was inserted to create a 2 mm bone gap. The rats were administered either 0.2 g/kg/d of L-dopa, 0.2/0.02 g/kg/d L-dopa/carbidopa in their feed, or plain powdered chow (Sham control group). The rats were killed at 5 weeks postsurgery. The femurs were excised, radiographed, and mechanically tested. Bone healing was assessed. Bone stiffness, ultimate load, and energy to failure were determined under 3 point bending using an Instron materials testing system. RESULTS: The femurs of 30% of the Sham rats healed compared with 50% of the L-dopa/carbidopa and 84% of the L-dopa treated femurs. The healed L-dopa rat femurs had significantly greater ultimate load (P = 0.037) and energy to failure (P = 0.004) than the healed Sham rats. There were no significant differences between the L-dopa/carbidopa group and either the Sham or L-dopa group. CONCLUSIONS: These results confirm that L-dopa administration increases the healing in nonunion fractures. The combination of L-dopa/carbidopa did not significantly increase fracture healing.

Evaluation of silver-titanium implants activated by low intensity direct current for orthopedic infection control: An in vitro and in vivo study.

Silver is an alternative antimicrobial of interest for the prophylaxis of prosthetic infections and electrical activation is known to augment its oligodynamic efficacy. In this study, we evaluated the in vitro and in vivo efficacy of a silver (Ag)-titanium (Ti) implant activated by 30 µA direct current compared with three controls - passive Ag-Ti, active Ti-Ti, and passive Ti-Ti. We hypothesized that the experimental group would provide better resistance to pathogenic colonization on the implant. Modified Kirby-Bauer technique was used to evaluate in vitro efficacy of the four groups against five bacteria and one fungus. For in vivo evaluation, forty-eight rats were divided into four groups. The implant was secured in a wound cavity along the posterior margin of the femur. The wound was inoculated with 7.5 × 10(5) CFU of Staphylococcus aureus. Rats were euthanized 14 days postsurgery and quantitative cultures were performed on the implant segments and the wound cavity tissue. In vitro tests showed that the growth of all six pathogens was inhibited around the active Ag anodes of the experimental group. In vivo, none of the four groups were able to prevent wound infection, but the experimental group resulted in reduced colonization. The mean bacterial loads on Ti segments were significantly lower in the implants which also had an Ag segment (p = 0.0007), and this effect was more pronounced with electrical activation (p = 0.0377). The results demonstrate the antimicrobial potential of LIDC-activated Ag-Ti implants. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 104B: 1023-1031, 2016.

Suture plication, thermal shrinkage, and sclerosing agents: effects on rat patellar tendon length and biomechanical strength.

BACKGROUND: Shortening or tightening of dense, collagenous tissues is often desirable in the treatment of laxity. PURPOSE: To compare the effect of stress-protection suture, radiofrequency thermal shrinkage combined with stress-protection suture, and a 5% sodium morrhuate sclerosing injection on the length and biomechanical strength of the rat patellar tendon. HYPOTHESIS: Sclerosing agents will increase tendon mechanical strength. Thermal shrinkage combined with stress-protection suture and stress-protection suture only will cause a short-term decrease in tendon strength. All 3 methods will produce equivalent shortening of the tendon. STUDY DESIGN: Controlled laboratory study. METHODS: Forty-six female retired breeder rats were split into 4 groups, each receiving 1 of the 3 aforementioned treatments plus a control group that received a saline injection. After 4 weeks' survival, the length and biomechanical properties of the patellar tendons were measured and compared to the contralateral untreated tendon. RESULTS: Rats treated with stress-protection suture had shorter tendons. Radiofrequency thermal shrinkage combined with stress-protection suture yielded tendons that were both shorter and stronger than were the untreated contralateral tendons. The sodium morrhuate-injected tendons were stronger whereas the saline-treated tendons were weaker than were their respective untreated contralateral tendons. CONCLUSION: Surgical stress-protection suture without radiofrequency shrinkage is most effective at shortening the length of the rat patellar tendon, whereas radiofrequency thermal shrinkage combined with stress-protection suture as well as sodium morrhuate are effective at increasing the strength of rat patellar tendons. CLINICAL RELEVANCE: Judicious use of thermal shrinkage in combination with stress protection may improve ligament strength and decrease laxity.