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.

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.

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.

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.

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.

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.

Local Injection of Aminoglycosides for Prophylaxis Against Infection in Open Fractures.

BACKGROUND: The purpose of this study was to determine the efficacy of local wound cavity injections of aqueous aminoglycosides (gentamicin and tobramycin), in conjunction with systemic antibiotics, to lower the prevalence of infection in patients with open fractures. METHODS: Three hundred and fifty-one open fractures were identified by Current Procedural Terminology codes 11011 and 11012. Data on patient demographic characteristics, injury characteristics, infection, and fracture union were obtained from the electronic medical records. Patients in the control group (183 fractures) received systemic antibiotics only. Patients in the intervention group (168 fractures) received, in addition to systemic antibiotics, a locally administered aminoglycoside (2 mg/mL) at the time of the index surgical procedure. At the discretion of the attending surgeon, some wounds also received postoperative irrigations of aqueous aminoglycoside (n = 34). For wounds that could not be closed and wounds that received postoperative irrigations, negative pressure dressings were used. RESULTS: The deep and superficial infection rate in the control group was 19.7% (thirty-six of 183 fractures), but it was significantly lower (p = 0.010) in the intervention group at 9.5% (sixteen of 168 fractures). When comparing only the deep infections, the infection rate in the control group was 14.2% (twenty-six of 183 fractures) compared with 6.0% (ten of 168 fractures) in the intervention group (p = 0.011). After multivariate analysis to adjust for possible confounding factors, the administration of local antibiotics was found to be an independent predictor of lower infection rates in both deep and superficial infections (odds ratio, 2.6 [95% confidence interval, 1.2 to 5.6]; p = 0.015) and deep infections only (odds ratio, 3.0 [95% confidence interval, 1.1 to 8.5]; p = 0.034). The use of local antibiotics did not have an impact on nonunion rate (p = 0.881), with a type-I error rate of α = 0.05 and 0.8 power. CONCLUSIONS: This study suggests that local aqueous aminoglycoside administration as an adjunct to systemic antibiotics may be effective in lowering infection rates in open fractures; further research with higher-level research designs are needed.

Low-Magnitude, High-Frequency Vibration Fails to Accelerate Ligament Healing but Stimulates Collagen Synthesis in the Achilles Tendon.

BACKGROUND: Low-magnitude, high-frequency vibration accelerates fracture and wound healing and prevents disuse atrophy in musculoskeletal tissues. PURPOSE: To investigate the role of low-magnitude, high-frequency vibration as a treatment to accelerate healing of an acute ligament injury and to examine gene expression in the intact Achilles tendon of the injured limb after low-magnitude, high-frequency vibration. STUDY DESIGN: Controlled laboratory study. METHODS: Complete surgical transection of the medial collateral ligament (MCL) was performed in 32 Sprague-Dawley rats, divided into control and low-magnitude, high-frequency vibration groups. Low-magnitude, high-frequency vibration started on postoperative day 2, and rats received vibration for 30 minutes a day for 12 days. All rats were sacrificed 2 weeks after the operation, and their intact and injured MCLs were biomechanically tested or used for histological analysis. Intact Achilles tendons from the injured limb were evaluated for differences in gene expression. RESULTS: Mechanical testing revealed no differences in the ultimate tensile load or the structural stiffness between the control and vibration groups for either the injured or intact MCL. Vibration exposure increased gene expression of collagen 1 alpha (3-fold), interleukin 6 (7-fold), cyclooxygenase 2 (5-fold), and bone morphogenetic protein 12 (4-fold) in the intact Achilles tendon when compared with control tendons (P < .05). CONCLUSION: While no differences were observed in the mechanical or histological properties of the fully transected MCL after low-magnitude, high-frequency vibration treatment, significant enhancements in gene expression were observed in the intact Achilles tendon. These included collagen, several inflammatory cytokines, and growth factors critical for tendons. CLINICAL RELEVANCE: As low-magnitude, high-frequency vibration had no negative effects on ligament healing, vibration therapy may be a useful tool to accelerate healing of other tissues (bone) in multitrauma injuries without inhibiting ligament healing. Additionally, the enhanced gene expression in response to low-magnitude, high-frequency vibration in the intact Achilles tendon suggests the need to further study its potential to accelerate tendon healing in partial injury or repair models.

An evaluation of prophylactic treatments to prevent post traumatic joint stiffness.

Arthrofibrosis is a major obstacle to restoring joint function after trauma. The objective of this study was to evaluate montelukast, forskolin, and triamcinolone as possible means of prophylaxis against the formation of arthrofibrosis. Forty-eight rats underwent surgical knee trauma with post-operative immobilization in full flexion. The treatment groups were: control (CTL), oral montelukast (3.75 mg/kg/day) (MLK), intra-articular forskolin injections (0.6 mg/kg) (FSK), and intra-articular triamcinolone injections (0.68 mg/kg) (STR). Rats were sacrificed after 14 days and femorotibial contracture angles were measured with the posterior capsule intact and with the posterior capsule cut. A 0.015Nm extension moment was applied to the knee. All treatment groups had significant reductions in contracture angle compared to the control. Mean contractures with the posterior capsule intact were 32°(CTL), 20° (MLK), 22° (FSK), and 7° (STR). Contractures with the posterior capsule cut were 28° (CTL), 19° (MLK), 20° (FSK), and 5° (STR). The STR group was significantly better than FSK and MLK. Triamcinolone injections provided dramatic reductions in stiffness. Both forskolin and montelukast provided significant, though lesser, reductions in stiffness. While the triamcinolone contracture angles were significantly better, the novel treatments of forskolin and montelukast provided encouraging results and should be studied further.

Evaluating effects of deferoxamine in a rat tibia critical bone defect model.

OBJECTIVES: Evaluate the use of deferoxamine in a calcium sulfate carrier to promote fracture healing in a critical bone defect model. METHODS: 43 female retired breeders were divided randomly into Control, Carrier, DFO and BMP groups and appropriate agents placed at the osteotomy site. RESULTS: There was a significant difference in the mean gap between groups Control vs DFO and Control vs BMP. A higher mean number of cortices were bridged in the DFO group as compared to the Control group. CONCLUSIONS: Our study demonstrated that DFO helped reduce the gap in this critical tibia defect.

Transcortical screw fixation of the olecranon shows equivalent strength and improved stability compared with tension band fixation.

OBJECTIVES: Currently, the standard for 21-B3.1 olecranon fracture fixation is the tension band wire construct described by the AO foundation. Although this technique effectively repairs displaced olecranon fractures and osteotomies, it is associated with a high rate of secondary surgery for implant removal due to hardware "back out," prominence, and discomfort. The senior author of this study has used transcortical screw fixation for olecranon fractures and osteotomies to avoid hardware discomfort but has been unable to find literature documenting the strength of this method. Accordingly, we compared the strength and stability of transcortical screw fixation with tension band fixation of simple transverse olecranon fractures under cyclical loading. METHODS: Eighteen fourth-generation synthetic biomechanical testing ulnas underwent a transverse olecranon osteotomy and were repaired by tension banding or screw fixation. Two 4.0 mm partially threaded screws inserted across the fracture gap into the anterior cortex of the ulna achieved screw fixation. Ulnas were tested in 2 ways as follows: (1) cyclic loading that simulated pushing up from a chair; and (2) single cycle loading to failure. Fracture displacement was recorded using a transducer that was placed on the posterior surface of the ulna. RESULTS: Differences between screw fixation and tension banding in the peak displacement during cyclic loading and single cycle load to failure were not significant. Screw fixation did show significantly less "trough" displacement (resting position between cycles) during cyclic loading indicating less plastic deformation. CONCLUSIONS: In a synthetic bone model of simple transverse olecranon fractures, screw fixation provided equivalent strength and less plastic deformation as compared with tension banding.

Varying whole body vibration amplitude differentially affects tendon and ligament structural and material properties.

Whole Body Vibration (WBV) is becoming increasingly popular for helping to maintain bone mass and strengthening muscle. Vibration regimens optimized for bone maintenance often operate at hypogravity levels (<1G) and regimens for muscle strengthening often employ hypergravity (>1G) vibrations. The effect of vibratory loads on tendon and ligament properties is unclear though excessive vibrations may be injurious. Our objective was to evaluate how tendon gene expression and the mechanical/histological properties of tendon and ligament were affected in response to WBV in the following groups: no vibration, low vibration (0.3G peak-to-peak), and high vibration (2G peak-to-peak). Rats were vibrated for 20 min a day, 5 days a week, for 5 weeks. Upon sacrifice, the medial collateral ligament (MCL), patellar tendon (PT), and the Achilles Tendon (AT) were isolated with insertion sites intact. All tissues were tensile tested to determine structural and material properties or used for histology. Patellar tendon was also subjected to quantitative RT-PCR to evaluate expression of anabolic and catabolic genes. No differences in biomechanical data between the control and the low vibration groups were found. There was evidence of significant weakness in the MCL with high vibration, but no significant effect on the PT or AT. Histology of the MCL and PT showed a hypercellular tissue response and some fiber disorganization with high vibration. High vibration caused an increase in collagen expression and a trend for an increase in IGF-1 expression suggesting a potential anabolic response to prevent tendon overuse injury.

An evaluation of carrier agents for desferoxamine, an up-regulator of vascular endothelial growth factor.

Avascularity and hypoxia result in avascular necrosis and play a negative role in fracture healing. The FDA-approved iron chelating agent, desferoxamine (DFO) in a liquid form, has been shown to induce angiogenesis and improve fracture healing through upregulation of the vascular endothelial growth factor. We were concerned that local injection of DFO would either fail to adequately deliver sufficient drug to the desired site or lead to undesired delivery to adjacent sites. Therefore, a sustained release delivery system was desirable to direct DFO to the intended site. Calcium sulfate pellets, collagen sponges, and demineralized cortical bone matrix were all evaluated as potentially controlled release systems for DFO using a fetal mouse metatarsal angiogenesis assay. Angiogenesis was analyzed using a vascularity grading scale, by measuring the mean vessel length of the 5 longest vessels, and by counting the mean number of vessels per metatarsal. Although there was some evidence of angiogenesis with all three carriers, DFO loaded CaSO4 pellets increased vascularity grading, the mean length of the five longest vessels, and the mean number of vessels, all by statistically significant margins versus the control. These results suggest that CaSO4 pellets could be used as a viable, nontoxic, controlled release system for DFO in clinical situations where increased angiogenesis and bone growth are desirable.

Biomechanical effects of steroid injections used to treat pyogenic flexor tenosynovitis.

BACKGROUND: A recent study from our laboratory has demonstrated improved range of motion in the toes of broiler chickens afflicted with pyogenic flexor tenosynovitis when treated with local antibiotic and corticosteroid injections, without surgical drainage. However, the use of corticosteroids as an adjunct treatment raised peer concern, as steroids are thought to have deleterious effects on tendon strength. The purpose of this study was to compare the tensile strength of the aforementioned steroid treated tendons, to a group of tendons administered with the current standard treatment: systemic antibiotics, surgical drainage and no corticosteroids. METHODS: Twenty-three tendons' structural and material properties were investigated (fifteen receiving the standard treatment, eight receiving the steroid treatment). The measurements from each group were interpreted via Student's unpaired t-test and a post-hoc power analysis. RESULTS: The steroid treated tendons did demonstrate a trend toward decreased mechanical properties when compared with the standard treatment group, but the results were not statistically significant. CONCLUSIONS: Treatment of septic tenosynovitis with local corticosteroid and local antibiotic injections resulted in better digital motion, without a significant loss of tendon strength, over a twenty-eight day recovery period.

Anteroposterior thickening of the femoral neck with aging decreases the "offset" in men.

BACKGROUND: The contour of the femoral head-neck junction has been shown to have an effect on femoroacetabular impingement (FAI), which can lead to early osteoarthritis of the hip. This study uses computed tomography (CT) to investigate changes in the femoral head, femoral neck, and joint space with aging. HYPOTHESIS: The ratio of the diameter of the femoral head to the diameter of the femoral neck would decrease with increasing age, thus diminishing the "offset" of the femoral neck and being a possible mechanism for cam-type FAI and resultant osteoarthritis. STUDY DESIGN: Cross-sectional study; Level of evidence, 3. METHODS: There were 20 male and 20 female patients from each decade, aged 20 to 80 years, who received pelvic and abdominal CT scans. In the axial plane, the femoral head and neck were measured from anterior to posterior, and the joint space was measured anteromedially. The ratio of the diameter of the femoral head to the diameter of the femoral neck was calculated, and patients with radiographic signs of osteoarthritis were noted. Regression analysis was performed to examine the significance of the relationships between these variables, age, and osteoarthritis. RESULTS: Male and female patients showed significant increases in femoral head diameter and femoral neck diameter as well as decreases in joint space width with increasing age. Male patients showed a decrease in the femoral head-neck ratio (relative neck thickening) of 0.0053 per year (P < .0001) or an average 18% decrease from age 20 to 80 years, while female patients did not show a significant relationship (P = .29). Male patients with signs of osteoarthritis had a smaller femoral head-neck ratio (P < .0001) than those without, while female patients did not (P = .25). Male and female patients with signs of osteoarthritis had a larger femoral head and femoral neck and a more narrow joint space width than those without. CONCLUSION: Our results suggest that, as men age, they develop a relatively thicker femoral neck that could result in increasing cam impingement, which contributes to the known higher prevalence of osteoarthritis in men. This does not seem to be the case in women, as their femoral neck does not appear to grow as quickly.

A technical trick which reduces the need for stab incisions when using bone tenaculums for fracture reduction.

During the reduction of fractures using a bone tenaculum, rather than making a stab incision, a frequently successful strategy can be to place a folded operative towel placed between the patient's skin and the head of the tenaculum. Using this technique, the surgeon can decrease scarring and potential stab wound complications. When the angle is too steep for the towel to allow the tenaculum to remain stable during the reduction, the surgeon can use the towel as a safe means of trial and error to determine the necessary alignment of the tenaculum to achieve reduction and consequently the best location at which to make the stab incision for the tine of the tenaculum.

Modified Ollier transtrochanteric approach for the treatment of acetabular fractures.

The purpose of this retrospective clinical study was to evaluate the rates of wound and neurologic complications and clinically significant heterotopic ossification, Brooker stage 3 and 4, with the modified Ollier transtrochanteric approach for the treatment of acetabular fractures. The study group comprised 94 consecutive patients (95 acetabuli) who had unstable acetabular fractures requiring surgical fixation. All patients were treated with open reduction internal fixation via the Ollier approach by a single surgeon (L.E.D.). Demographic and clinical information regarding rates of wound and neurologic complications and remaining articular stepoff at fixation was obtained from a chart review. The degree of heterotopic ossification was graded from standard anteroposterior pelvis radiographs according to the Brooker classification. Six (6%) patients underwent reoperation for infection; however, only 3 (3%) of these patients had deep infections. Three (3%) patients had iatrogenic sciatic nerve injuries; only 1 patient had persistent sensory changes at final follow-up. Thirteen (18%) of the 73 patients with radiographs available for review at a minimum of 3-month follow-up had Brooker grade III heterotopic ossification and 1 (1%) patient had grade IV. Five (5%) patients underwent excision of heterotopic ossification. Fourteen (17%) of 81 patients had no radiographic union of the greater trochanteric osteotomy, but none of these patients required further surgery. The complication rates of the Ollier approach in this study compare favorably with alternative surgical approaches reported in large series. We believe this approach provides excellent exposure without increasing the risk of complications.

Effect of prostaglandin E2 injection on the structural properties of the rat patellar tendon.

BACKGROUND: Increased tendon production of the inflammatory mediator prostaglandin E2 (PGE2) has been suggested to be a potential etiologic agent in the development of tendinopathy. Repeated injection of PGE2 into tendon has been proposed as a potential animal model for studying treatments for tendinopathy. In contrast, nonsteroidal anti-inflammatory drugs (NSAIDs) which inhibit PGE2 production and are commonly prescribed in treating tendinopathy have been shown to impair the healing of tendon after acute injury in animal models. The contradictory literature suggests the need to better define the functional effects of PGE2 on tendon. Our objective was to characterize the effects of PGE2 injection on the biomechanical and biochemical properties of tendon and the activity of the animals. Our hypothesis was that weekly PGE2 injection to the rat patellar tendon would lead to inferior biomechanical properties. METHODS: Forty rats were divided equally into four groups. Three groups were followed for 4 weeks with the following peritendinous injection procedures: No injection (control), 4 weekly injections of saline (saline), 4 weekly injections of 800 ng PGE2 (PGE2-4 wks). The fourth group received 4 weekly injections of 800 ng PGE2 initially and was followed for a total of 8 weeks. All animals were injected bilaterally. The main outcome measurements included: the structural and material properties of the patellar tendon under tensile loading to failure, tendon collagen content, and weekly animal activity scores. RESULTS: The ultimate load of PGE2-4 wks tendons at 4 weeks was significantly greater than control or saline group tendons. The stiffness and elastic modulus of the PGE2 injected tendons at 8 weeks was significantly greater than the control or saline tendons. No differences in animal activity, collagen content, or mean fibril diameter were observed between groups. CONCLUSIONS: Four weekly peritendinous injections of PGE2 to the rat patellar tendon were not found to be an effective model of clinical tendinopathy. In contrast, improved structural and material properties of the patellar tendon were found after PGE2 injection. While PGE2 has been thought to have a contributory role in the development of tendinopathy and anti-inflammatory medications remain a common treatment, our results suggest a positive role of PGE2 in tendon remodeling in some circumstances.

Relationship between width of greater trochanters and width of iliac wings in tronchanteric bursitis.

Trochanteric bursitis is a common disorder that is characterized by inflammation of the bursa, superficial to the greater trochanter of the femur, leading to pain in the lateral hip, and often occurs because of acute trauma or repetitive friction involving the iliotibial band, the greater trochanter, and the bursa. In the study reported here, we hypothesized that the increased incidence of bursitis may be the result of the increased prominence of the trochanter in relation to the wings of the iliac crest. Distances between the outermost edges of trochanters and iliac wings were measured in 202 patients from the University of North Carolina Health Care System-101 without a known diagnosis and 101 with a clinical diagnosis of trochanteric bursitis. To determine significance, t tests for nonpaired data were used. Mean (SD) difference between trochanter and iliac wing widths was 28 (20) mm in the group diagnosed with trochanteric bursitis and 17 (18) mm in the control group. The difference between the groups in this regard was significant (P<.00005). In addition, mean (SD) ratio of trochanter widths to iliac wing widths was 1.09 (.06) in the bursitis group and 1.05 (.06) in the control group. The difference between these groups was significant (P<.0005) in this regard as well. Having trochanters wider in relation to iliac wings was associated with the diagnosis of trochanteric bursitis.