Fine Sediment Removal Influences Biogeochemical Processes in a Gravel-bottomed Stream.

The transport and processing of nutrients and organic matter in streams are important functions that influence the condition of watersheds and downstream ecosystems. In this study, we investigated the effects of streambed sediment removal on biogeochemical cycling in Fawn River, a gravel-bottomed river in Indiana, U.S.A. We measured stream metabolism as well as nitrogen (N) and phosphorus (P) retention in both restored and unrestored reaches of Fawn River to examine how sediment removal affected multiple biogeochemical functions at the reach scale. We also assessed the properties of restored and unrestored streambed sediments to elucidate potential mechanisms driving observed reach-scale differences. We found that sediment removal led to lower rates of primary productivity and ecosystem respiration in the restored reach, likely due to macrophyte removal and potentially due to changes to sediment organic matter quality. We found minimal differences in N and P retention, suggesting that these processes are controlled at larger spatial or temporal scales than were examined in this study. Denitrification enzyme activity was lower in sediments from the restored reach compared to the unrestored reach, suggesting that restoration may have decreased N removal. Our results indicate that most near-term changes in biogeochemical function following restoration could be attributed to macrophyte removal, although effects from sediment removal may emerge over longer timescales.

The Effect of Cartilage Injury After Arthroscopic Stabilization for Shoulder Instability.

This study was undertaken to (1) determine the incidence of articular cartilage injuries in patients with instability of the glenohumeral joint, (2) determine whether recurrent dislocations increased the risk of articular damage, and (3) correlate these injuries with postoperative clinical outcomes. A cohort was identified of consecutive patients who underwent diagnostic magnetic resonance imaging and shoulder arthroscopy for glenohumeral instability with documented dislocation or subluxation between 1997 and 2006 at a single institution. Patients with moderate or severe osteoarthritis were excluded. Arthroscopic findings were recorded, including lesion location and Outerbridge grade. The American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form (ASES) was used to assess outcome in 61 patients who were available for follow-up. Outcomes were compared between shoulders with and without articular lesions. A total of 87 shoulders (83 patients) met the inclusion criteria, with 69 (83%) men and 14 (17%) women. Mean age was 26.1 years (range, 18-64 years), and mean follow-up was 36 months (range, 33-39 months). Cartilage injuries were found in 56 shoulders (64%). Previously documented shoulder dislocation requiring closed reduction (P=.046) and the number of discrete dislocations (P=.032) were significant for glenoid injury. A greater number of dislocations was associated with higher-grade lesions of the glenohumeral joint (P<.001). Overall, mean ASES score was 89.6 (range, 37-100). In patients with an articular cartilage lesion, mean ASES score was 90.4 (range, 58-100) compared with 88.1 (range, 37-100) in those without this injury (P=.75). Although clinical outcomes were not significantly affected, further investigation is warranted to establish a relationship between these injuries and longer-term outcomes.

Incidence and Risk Factor Analysis of Symptomatic Venous Thromboembolism After Knee Arthroscopy.

PURPOSE: To (1) determine the incidence of symptomatic venous thromboembolic events (VTEs) after knee arthroscopy and arthroscopy-assisted procedures at a single institution and (2) determine associated risk factors for VTEs in these patients. METHODS: The records of patients who underwent knee arthroscopy at a single institution between 1988 and 2008 were reviewed. Chemoprophylaxis was not routinely used. Confirmed VTEs occurring within 4 weeks after the index arthroscopy procedure were included. A 2:1 matched control group was generated to include patients in whom knee arthroscopy was performed by the same surgeon either on the same day or immediately before each case resulting in a VTE. Preoperative and perioperative data were collected with respect to demographic data, medical history, medications, and surgical and anesthesia data. Univariate and multivariate analyses were performed. RESULTS: During the study period, 12,595 patients underwent knee arthroscopy. Among these patients, 43 cases of VTEs (35 deep venous thromboses [DVTs], 5 pulmonary embolisms [PEs], and 3 DVTs that progressed to PEs) occurred, resulting in an incidence of 0.30% (95% confidence interval [CI], 0.22% to 0.41%) for DVT, 0.06% (95% CI, 0.03% to 0.12%) for PE, and 0.34% (95% CI, 0.25% to 0.46%) for VTEs overall. Factors associated with an elevated risk of symptomatic postoperative VTEs included a history of malignancy (P = .01; odds ratio [OR], 6.3), a history of VTEs (P = .02; OR, 5.2), or the presence of more than 2 classic risk factors for VTEs (P = .01; OR, 13.6). CONCLUSIONS: In this study, symptomatic VTEs were rare and occurred infrequently, with an incidence of 0.34% (95% CI, 0.25% to 0.46%), after knee arthroscopy and arthroscopy-assisted cases in the absence of routine chemoprophylaxis. Patients with a history of VTEs, a history of malignancy, or 2 or more classic risk factors are at increased risk of VTEs after knee arthroscopy, and chemoprophylaxis should be considered in these select patients. LEVEL OF EVIDENCE: Level III, case-control study.

Factors associated with excellent 6-month functional and isokinetic test results following ACL reconstruction.

PURPOSE: To identify patient concomitant injury and surgical characteristics associated with 6-month excellent functional and isokinetic testing results following anterior cruciate ligament (ACL) reconstruction. METHODS: Patients that underwent ACL reconstruction by a single surgeon had isokinetic and functional testing performed with excellent 6-month outcome defined as greater than 85 % in isokinetic strength and 90 % in functional tests (excellent 6-month group vs. delayed 6-month group). Patient concomitant injury and surgical factors were then analysed in univariate and multivariate statistical models to assess which characteristics predicted the excellent 6-month group. RESULTS: The 224 patients included 93 males and 131 females, with median age of 22 (range 12-59) years, body mass index (BMI) of 25.4 (range 17-44), and median Tegner activity score of 6 (range 2-10). Fifty-two patients (23 %) were included in the excellent 6-month group, while 172 patients (77 %) were in the delayed 6-month group. In univariate analysis, favourable factors with the excellent 6-month outcome group were younger age (24 vs. 27; p = 0.01), lower BMI (24.5 vs. 26.2; p = 0.03), and minimal articular cartilage damage (71 vs. 56 %; p = 0.048). In multivariate analysis, a negative effect was observed for patients older than 30 years that had ACL reconstruction with autograft (p = 0.0004). CONCLUSION: Factors significantly associated with excellent 6-month functional and isokinetic test results following ACL reconstruction included younger age, lower BMI, and minimal cartilage degeneration. The use of allograft was associated with improved functional and strength testing after ACL reconstruction in patients over 30 years of age. LEVEL OF EVIDENCE: Prognostic/therapeutic study, Level III.

Periarticular raft constructs and fracture stability in split-depression tibial plateau fractures.

OBJECTIVES: To evaluate relative fracture stability yielded by screws placed above a lateral plate, as well as locking and non-locking screws placed through a plate in a split depression tibia plateau fracture model. METHODS: Cadaver tibia specimens (mean age 74.1 years) were randomised across 3 groups: Groups 1: raft-construct outside the plate, 2: non-locking raft screws through the plate, and 3: locking raft screws through the plate. Displacement of the depressed fragment was recorded with force values from 400N to 1600N in increasing 400N increments. The force required to elicit lateral plateau fragment displacement of 5mm, 10mm, and 15mm was also recorded. RESULTS: None of the mechanical testing results demonstrated statistical significance with p-values of <0.05. Cyclic testing of Groups 1, 2, and 3 at 400N revealed displacements of 0.54mm, 0.64mm, and 0.48mm, respectively. At 800N, displacements were 1.36mm, 1.4mm, and 1.4mm, respectively. At 1200N, displacements were 2.4mm, 1.9mm, and 2.1mm, respectively. At 1600N, displacements were 2.8mm, 2.5mm, and 2mm, respectively. Resistance to displacement data demonstrated the mean force required to displace the fracture 5mm in Groups 1, 2, and 3 were 250N, 330N, and 318N, respectively. For 10mm of displacement, forces required were 394N, 515N, and 556N, respectively. For 15mm of displacement, forces required were 681N, 853N, and 963N, respectively. Compared to combined groups using screws through the plate, Group 1 demonstrated lower displacement ≤800N, but demonstrated greater displacement >800N. Group 2 demonstrated greatest resistance to plateau displacement of 5mm compared to Group 1 or 3, while Group 3 was most resistant to greater displacement. The combined group using screws through the plate (Groups 2+3) was consistently more resistant than Group 1 at all levels of displacement. CONCLUSIONS: Designs utilising screws through the plate trended towards statistically significant improved stability against plateau displacement relative to utilising screws outside the plate. Our study also suggests that there is no significant benefit of locking screws over non-locking screws in this unicondylar tibia plateau fracture model.

Femoral tunnel malposition in ACL revision reconstruction.

The Multicenter Anterior Cruciate Ligament (ACL) Revision Study (MARS) group was formed to study a large cohort of revision ACL reconstruction patients. The purpose of this subset analysis study of the MARS database is to describe specific details of femoral tunnel malposition and subsequent management strategies that surgeons chose in the revision setting. The design of this study is a case series. The multicenter MARS database is compiled from a questionnaire regarding 460 ACL reconstruction revision cases returned by 87 surgeons. This subset analysis described technical aspects and operative findings in specifically those cases in which femoral tunnel malposition was cited as the cause of primary ACL reconstruction failure. Of the 460 revisions included for study, 276 (60%) cases cited a specific "technical cause of failure." Femoral tunnel malposition was cited in 219 (47.6%) of 460 cases. Femoral tunnel malposition was cited as the only cause of failure in 117 cases (25.4%). Surgeons judged the femoral tunnel too vertical in 42 cases (35.9%), too anterior in 35 cases (29.9%), and too vertical and anterior in 31 cases (26.5%). Revision reconstruction involved the drilling of an entirely new femoral tunnel in 91 cases (82.1%). For primary reconstruction, autograft tissue was used in 82 cases (70.1%). For revision reconstruction, autograft tissue was used in 61 cases (52.1%) and allograft tissue in 56 cases (47.9%). Femoral tunnel malposition in primary ACL reconstruction was the most commonly cited reason for graft failure in this cohort. Graft selection is widely variable among surgeons.

Impact of maturational status on the ability of osteoblasts to enhance the hematopoietic function of stem and progenitor cells.

Osteoblasts (OBs) exert a prominent regulatory effect on hematopoietic stem cells (HSCs). We evaluated the difference in hematopoietic expansion and function in response to co-culture with OBs at various stages of development. Murine calvarial OBs were seeded directly (fresh) or cultured for 1, 2, or 3 weeks prior to seeding with 1000 Lin-Sca1 + cKit+ (LSK) cells for 1 week. Significant increases in the following hematopoietic parameters were detected when comparing co-cultures of fresh OBs to co-cultures containing OBs cultured for 1, 2, or 3 weeks: total hematopoietic cell number (up to a 3.4-fold increase), total colony forming unit (CFU) number in LSK progeny (up to an 18.1-fold increase), and percentage of Lin-Sca1+ cells (up to a 31.8-fold increase). Importantly, these studies were corroborated by in vivo reconstitution studies in which LSK cells maintained in fresh OB co-cultures supported a significantly higher level of chimerism than cells maintained in co-cultures containing 3-week OBs. Characterization of OBs cultured for 1, 2, or 3 weeks with real-time PCR and functional mineralization assays showed that OB maturation increased with culture duration but was not affected by the presence of LSK cells in culture. Linear regression analyses of multiple parameters measured in these studies show that fresh, most likely more immature OBs better promote hematopoietic expansion and function than cultured, presumably more mature OBs and suggest that the hematopoiesis-enhancing activity is mediated by cells present in fresh OB cultures de novo.

DMSO regulates osteoclast development in vitro.

Dimethyl sulfoxide (DMSO) is routinely used in the laboratory as a solvent and vehicle for organic molecules. Although it has been used in previous studies involving myeloid cells and macrophages, we are unaware of data demonstrating the effects of DMSO alone on osteoclast development. Recently, we were using DMSO as a vehicle and included a non-vehicle control. Surprisingly, we observed a marked change in osteoclast development, and therefore designed this study to examine the effects of DMSO on osteoclast development. Osteoclasts were generated from two sources: bone marrow macrophages and an osteoclast progenitor cell line. Cells were cultured with DMSO for various durations and at differing concentrations and mature, multinucleated (>3 nuclei) TRAP(+) cells were assessed in terms of cell number, cell surface area, and number of nuclei/cell. Osteoclast surface area increased in 5 µM DMSO to a mean of 156,422 pixels from a mean of 38,510 pixels in control culture, and subsequently decreased in 10 µM DMSO to a mean of 18,994 pixels. With serial addition of DMSO over 5 d, a significant increase in mean surface area, and number of nuclei/cell was also observed, while the opposite was true when DMSO was serially removed from culture. These findings show that DMSO exerts a marked effect on osteoclast differentiation. Since many investigators use DMSO to solubilize compounds for treatment of osteoclasts, caution is warranted as altering DMSO concentrations may have a profound effect on the final data, especially if osteoclast differentiation is being assessed.

Transtibial versus inlay posterior cruciate ligament reconstruction: an evidence-based systematic review.

Optimal surgical technique for posterior cruciate ligament (PCL) reconstruction remains controversial. Authors have reported satisfactory outcomes with both transtibial and inlay techniques. Although biomechanical data has failed to demonstrate a difference between the two, there is little clinical data directly comparing transtibial versus inlay PCL reconstruction. Evidence-based treatment recommendations are therefore lacking. The purpose of this study was to perform an evidence-based systematic review comparing the clinical results of transtibial and inlay PCL reconstruction. A comprehensive search of MEDLINE and the Cochrane databases for all relevant articles published from 1980 to 2010 on the clinical outcomes of transtibial and inlay PCL reconstruction was performed. Inclusion criteria included articles published in (1) English, (2) human subjects, (3) between the years 1980 and 2010, (4) minimum of 24-month follow-up, (5) measures of clinical and functional outcomes, and (6) isolated grade III PCL injuries. Exclusion criteria included (1) technique description only, (2) case reports, (3) multiligament knee injuries, (4) PCL bony avulsion, and (5) revision PCL surgery. Our review identified 26 relevant clinical studies. Twenty articles focused on transtibial PCL reconstruction, 3 articles focused on inlay PCL reconstruction, and 3 articles compared the two techniques. No prospective studies directly compared transtibial PCL reconstruction with inlay PCL reconstruction. Currently, there is a paucity of objective data comparing the outcomes of transtibial versus inlay PCL reconstruction. This systematic review demonstrated satisfactory clinical and functional results for both surgical techniques. Prospective randomized clinical trials are needed to evaluate the best treatment strategy. At the present time, surgeon preference appears to be a reasonable option.

Staged protocol for initial management of the dislocated knee.

PURPOSE: The purpose of this study was (1) to describe a staged protocol for management of the dislocated knee and (2) to describe clinical and functional outcomes for patients who received initial spanning external fixation as part of this protocol. METHOD: Nine knees in 9 patients, consisting of 6 males and 3 females, mean age 30.4 (range 19-44) years with diagnosis or presumption of knee dislocation were treated with a protocol of stabilization with external fixator. Mean follow-up was 24 (range 13-42) months. Indications for spanning external fixation included significant vascular injury, gross instability on examination with failure to maintain joint reduction, open knee dislocation, inability to tolerate mobilization in a brace. The standard protocol involved vascular examination including ankle-brachial index, ligamentous examination (under anesthesia when applicable), stabilization with temporary joint spanning external fixator, thromboprophylaxis, reconstructive knee surgery, and standard rehabilitation. RESULTS: Mean range of motion (ROM) was 97.4° (range 80°-150°, SD 20.75, median 127.5). Median IKDC score was 80 (range 30-95), and mean Lysholm score was 76.7 (range 46-95). Heterotopic ossification (HO) was noted in 4 knees (44%). CONCLUSION: The treatment algorithm utilized in this series for management of the dislocated knee demonstrated satisfactory clinical and functional outcomes. This staged protocol provides a management option for those patients who may be best served with initial spanning joint external fixation. Larger prospective studies are needed to fully understand the merit of staged protocols in this setting.

Prenatal diagnosis and management of intrauterine fracture.

UNLABELLED: Intrauterine fracture is an extremely rare finding, but can occur as the result of maternal trauma, osteogenesis imperfecta (OI), or theoretically other metabolic/structural abnormalities. Increased clinical awareness of the diagnosis and optimal management of these cases can lead to more positive outcomes for the patient and her child. Blunt abdominal trauma late in gestation increases the risk of fetal skull fracture, while a known diagnosis of OI or other abnormalities leading to decreased fetal bone density creates concern for long bone fracture. Biochemical and genetic tests can aid in the prenatal diagnosis of OI, while ultrasound is the best overall imaging modality for identifying fetal fracture of any etiology. When fetal fracture is diagnosed radiologically, specific management is recommended to promote optimal outcomes for mother and fetus, with special consideration given to the mother with OI. With the exception of fetal fractures due to lethal conditions, cesarean delivery is recommended in most cases, especially when fetal or maternal well-being cannot be assured. When a patient presents with risk factors for intrauterine fracture, careful evaluation via thorough history-taking, ultrasonography of the entire fetal skeleton, and laboratory tests should be performed. Heightened awareness of intrauterine fracture allows better postpartum management, whether for simple fracture care or for long-term care of patients with OI or genetic/metabolic abnormalities. TARGET AUDIENCE: Obstetricians & Gynecologist, Family Physicians. LEARNING OBJECTIVES: After completion of this educational activity, the reader will be able to compare x-ray, ultrasound modalities and MRI and their utility in diagnosing fetal fracture. Formulate a differential diagnosis for fetal fracture. Propose a delivery plan for a patient whose fetus has a prenatally diagnosed fetal fracture.

Efficacy of diagnostic magnetic resonance imaging for articular cartilage lesions of the glenohumeral joint in patients with instability.

OBJECTIVE: The purpose of this study was primarily to assess the diagnostic performance of magnetic resonance imaging (MRI) in detecting articular cartilage injuries in patients with glenohumeral instability. A secondary purpose was to assess the diagnostic performance of MRI for detection of Hill-Sachs and Bankart lesions. MATERIALS AND METHODS: A cohort of 87 consecutive patients who underwent diagnostic MRI and shoulder arthroscopy for instability from 1997 to 2006 were identified. Fifty-five patients (63.2%) underwent MRI with intra-articular contrast medium and 32 patients (36.8%) underwent MRI without contrast medium. MR images were reviewed by two radiologists and interpreted by consensus for the presence of articular cartilage lesions (including Hill-Sachs and Bankart lesions), which were then confirmed by reviewing the operative report and images recorded at arthroscopy. RESULTS: Mean patient age was 27.0 ± 10.2 years with a mean clinical and radiographic follow-up of 29 (range 3-72) months. Cartilage injuries were detected arthroscopically in 55 patients (63%). Bankart and Hill-Sachs lesions were identified arthroscopically in 66 patients (75.9%) and 55 patients (63.2%) respectively. The overall sensitivity and specificity for detection of glenohumeral articular cartilage lesions by MRI were 87.2% and 80.6% respectively. The sensitivity and specificity of MRI in detecting Bankart lesions was 98.4% (95% CI 91.9, 99.7) and 95.2% (95% CI 77.3, 99.2) respectively. The sensitivity and specificity of MRI in detecting Hill-Sachs lesions was 96.3% (95% CI 87.6, 98.9%) and 90.6% (95% CI 75.7, 96.9) respectively. No statistically significant difference was found between MRI examinations with and without intra-articular gadolinium (p = 0.89). CONCLUSION: Magnetic resonance imaging demonstrates high sensitivity and specificity for the diagnosis of articular cartilage injuries in patients with glenohumeral instability. MRI with or without intra-articular contrast medium in this study were equally reliable as a non-invasive method for assessment of articular cartilage damage of the glenohumeral joint prior to diagnostic arthroscopy.

Repair versus reconstruction of the fibular collateral ligament and posterolateral corner in the multiligament-injured knee.

BACKGROUND: Treatment of the multiligament-injured knee remains controversial. PURPOSE: To compare clinical and functional outcomes of a consecutive series of multiligament-injured knees that underwent repair of the fibular collateral ligament (FCL) and posterolateral corner (PLC), followed by delayed cruciate ligament reconstructions, with those that had single-stage multiligament reconstruction. STUDY DESIGN: Cohort study; Level of evidence, 3. Methods Patients with multiligament knee injury treated by a single surgeon were identified in our prospective database. Between February 2004 and May 2005, patients underwent repair of medial- and lateral-sided injuries, followed by delayed cruciate ligament reconstructions. Between May 2005 and February 2007, patients underwent single-stage multiligament knee reconstruction. All patients followed a standard rehabilitation protocol. Inclusion criteria were minimum 2-year follow-up and multiligament knee injury including the FCL/PLC. International Knee Documentation Committee subjective and Lysholm scores and objective clinical data were documented. RESULTS: We identified 45 knees (42 patients); 17 knees (14 patients) were excluded, leaving 28 knees (28 patients) in the study. The repair/staged group (10 knees in 10 patients) had a mean follow-up of 34 months (range, 24-49 months). The reconstruction group (18 knees in 18 patients) had a mean follow-up of 28 months (range, 24-41 months). Four of the 10 FCL/PLC repairs (40%) and 1 of the 18 FCL/PLC reconstructions (6%) failed (P = .04). After revision reconstructions, there were no statistically significant differences between mean International Knee Documentation Committee subjective scores (79 vs. 77, P = .92) and mean Lysholm scores (85 vs 88, P = .92). Regression analysis showed no effect on failure based on age, sex, injury mechanism, time to surgery, interval between stages, total number of ligaments injured, or location of tear. CONCLUSION: Our series demonstrated a statistically significant higher rate of failure for repair compared with reconstruction of the FCL/PLC. Reconstruction of the FCL/PLC structures is a more reliable option than repair alone in the setting of a multiligament knee injury.

The effect of lordosis, disc height change, subsidence, and transitional segment on stand-alone anterior lumbar interbody fusion using a nontapered threaded device.

In this study, we retrospectively evaluated 37 consecutive patients who underwent stand-alone anterior lumbar interbody fusion (ALIF); for indications that included degenerative disc disease, concordant pain on discography, disc space collapse of more than 50%, and failure of nonoperative management for at least 4 consecutive months. Patient demographics, procedural data, and prospective Short Form 36 General Health Survey composite scores were collected. Mean follow-up was 24.2 months. In this cohort of patients with degenerative disc disease, there was no loosening or migration of implants. Stand-alone ALIF using a threaded interbody fusion device provided excellent clinical results and return-to-work rates with few complications. Increased lordosis was associated with increased subsidence and less favorable outcome. Patients with a transitional segment displayed relatively smaller increases in lordosis and better outcomes than patients without a transitional segment.