John Y. Kwon

Comparison of brush and biopsy sampling methods of the ileal pouch for assessment of mucosa-associated microbiota of human subjects

BackgroundMucosal biopsy is the most common sampling technique used to assess microbial communities associated with the intestinal mucosa. Biopsies disrupt the epithelium and can be associated with complications such as bleeding. Biopsies sample a limited area of the mucosa, which can lead to potential sampling bias. In contrast to the mucosal biopsy, the mucosal brush technique is less invasive and provides greater mucosal coverage, and if it can provide equivalent microbial community data, it would be preferable to mucosal biopsies.ResultsWe compared microbial samples collected from the intestinal mucosa using either a cytology brush or mucosal biopsy forceps. We collected paired samples from patients with ulcerative colitis (UC) who had previously undergone colectomy and ileal pouch anal anastomosis (IPAA), and profiled the microbial communities of the samples by sequencing V4-V6 or V4-V5 16S rRNA-encoding gene amplicons. Comparisons of 177 taxa in 16 brush-biopsy sample pairs had a mean R2 of 0.94. We found no taxa that varied significantly between the brush and biopsy samples after adjusting for multiple comparisons (false discovery rate ≤0.05). We also tested the reproducibility of DNA amplification and sequencing in 25 replicate pairs and found negligible variation (mean R2 = 0.99). A qPCR analysis of the two methods showed that the relative yields of bacterial DNA to human DNA were several-fold higher in the brush samples than in the biopsies.ConclusionsMucosal brushing is preferred to mucosal biopsy for sampling the epithelial-associated microbiota. Although both techniques provide similar assessments of the microbial community composition, the brush sampling method has relatively more bacterial to host DNA, covers a larger surface area, and is less traumatic to the epithelium than the mucosal biopsy.

Shoulder motion, strength, and functional outcomes in children with established malunion of the clavicle.

Background: Recent investigations of displaced clavicle fractures in adults have demonstrated a higher prevalence of nonunion, symptomatic malunion, diminished functional outcome, and decreased strength with nonoperative treatment. Although these data have led to increased surgical management of displaced fractures, little published information is available regarding the consequences of malunion in the pediatric population. The purpose of this investigation was to assess pain, functional outcome, range of motion, and strength in children with displaced clavicle fractures treated nonoperatively. Methods: Clinical evaluation of 16 patients with mid-diaphyseal clavicle fractures and >2 cm of initial displacement was performed; all had undergone nonoperative treatment and went on to radiographic malunion. The mean age at the time of injury was 12.2±3.3 years. Pain, aesthetic appearance, and satisfaction with treatment were rated by patients on a visual analog scale (VAS) (range 0 to 10 with 10 indicating the worst score). Patient-based outcomes were assessed with the Disabilities of the Arm, Shoulder, and Hand (DASH) questionnaire and the Pediatric Outcomes Data Collection Instrument (PODCI). Bilateral shoulder motion was measured by a physical therapist. Isokinetic strength testing of the bilateral shoulders was performed with a Biodex dynometer. Range of motion and strength were analyzed with a multivariable regression, controlling for hand dominance. The mean follow-up was 27.2 months after injury. Results: All displaced fractures treated nonoperatively achieved union. Overall, there was reduced forward flexion and abduction on the injured side compared with the contralateral sides of 7.3 and 6.5 degrees, respectively, adjusted for hand dominance (P<0.05). Biodex testing did not detect any significant difference in abduction or adduction torque or power between affected and unaffected shoulders. The mean VAS score for pain was 1.6, with 4 patients reporting pain ≥to 3. The mean VAS scores for satisfaction with aesthetic appearance was 2.7, with 4 patients reporting scores >5. The mean VAS scores for satisfaction with treatment was 2.0, with only 1 patient scoring >5. The mean DASH score was 4.9±7.5, with 3 patients scoring ≥10. The mean scores on the DASH sports and performing arts module was 1.9±4.2, with only 1 patient scoring ≥10. The mean global PODCI score was 94.5±6.0. The mean PODCI scores for upper extremity function, sports, and pain were 97.9±5.5, 95.4±5.3, and 84.6±20.5, respectively. Only 1 patient was symptomatic enough to require corrective osteotomy. Conclusions: Skeletally immature patients with established clavicle fracture malunions do not develop clinically meaningful loss of shoulder motion or abduction/adduction strength. Routine surgical fixation for displaced, nonsegmental clavicle fractures may not be justified based upon concerns regarding shoulder motion and strength alone. Further investigation is required to determine the risk factors and causes of pain and functional compromise in the minority of pediatric patients with symptomatic malunions. Level of Evidence: Level IV.

Role of Preoperative Computed Tomography Scans in Operative Planning for Malleolar Ankle Fractures

Background: There remains no consensus regarding the role of computed tomography (CT) scans in preoperative planning for malleolar ankle fractures. The aim of this study was to determine the role of preoperative CT scans on operative planning in these fractures. Methods: A retrospective analysis was performed on 100 consecutive patients treated at our institution for malleolar ankle fractures (AO type 44) with both preoperative radiographs and CT scans. Six study participants reviewed available radiographs and formulated an operative (or nonoperative) plan including positioning, operative approach, and fixation. Participants then analyzed CT scans of the same fractures, deciding whether (and how) they would alter operative strategy. Characteristics of fractures and radiographs were correlated with changes in operative strategy. Results: Operative strategy was notably changed in 24% of cases after CT review, with strong intraclass correlation (0.733). Common changes included alterations in medial malleolar (21%) or posterior malleolar (15%) fixation and fixation of an occult anterolateral plafond fracture (9%). Notable predictors of changes in operative strategy included trimalleolar over unimalleolar fractures (29% vs 10% rate of change), preoperative dislocation over no dislocation (31% vs 20%), the presence of only radiographs with overlying plaster versus fractures with at least 1 set of radiographs without plaster (25% vs 14%), and suprasyndesmotic versus trans- and infra-syndesmotic fractures (40% vs 20% and 4%, respectively). Conclusions: CT scans may be useful adjuncts in preoperative planning for malleolar ankle fractures, most notably in fracture dislocations, cases in which all available radiographs are obscured by plaster, trimalleolar fractures, and suprasyndesmotic fractures. Level of Evidence: Level III, retrospective comparative study.

Peroneal Tendon Displacement Accompanying Intra-articular Calcaneal Fractures

BACKGROUND Peroneal tendon displacement (subluxation or dislocation) accompanying an intra-articular calcaneal fracture is often undetected and under-treated. The goals of this study were to determine (1) the prevalence of peroneal tendon displacement accompanying intra-articular calcaneal fractures, (2) the association of tendon displacement with fracture classifications, (3) the association of tendon displacement with heel width, and (4) the rate of missed diagnosis of the tendon displacement on radiographs and computed tomography (CT) scans and the resulting treatment rate. METHODS A retrospective radiographic review of all calcaneal fractures presenting at three institutions from June 30, 2006, to June 30, 2011, was performed. CT imaging of 421 intra-articular calcaneal fractures involving the posterior facet was available for review. The prevalence of peroneal tendon displacement was noted and its associations with fracture classification and heel width were evaluated. RESULTS Peroneal tendon displacement was identified in 118 (28.0%) of the 421 calcaneal fracture cases. The presence of tendon displacement was significantly associated with joint-depression fractures compared with tongue-type fractures (p < 0.001). Only twelve (10.2%) of the 118 cases of peroneal tendon displacement had been identified in the radiology reports. Although sixty-five (55.1%) of the fractures with tendon displacement had been treated with internal fixation, the tendon displacement was treated surgically in only seven (10.8%) of these cases. CONCLUSIONS Analysis of CT images showed a 28% prevalence of peroneal tendon displacement accompanying intra-articular calcaneal fractures. Surgeons and radiologists are encouraged to consider this association.

Expression of neurotrophins and the low-affinity NGF receptor in septal and hippocampal reaggregate cultures: local physiologic effects of NGF synthesized in the septal region

Nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF) and neurotrophin-3 (NT-3) are members of a family of trophic factors designated the neurotrophins, each of which can bind to the low-affinity NGF receptor (LNGFR). To investigate the mechanisms that regulate the expression of the neurotrophins and the LNGFR in the developing brain, we grew cells from the embryonic mouse septum and hippocampus in reaggregating cell culture and compared neurotrophin and LNGFR expression in developing reaggregates with that seen in the developing septum and hippocampus in situ. NGF, BDNF, NT-3 and LNGFR were each expressed in septal and hippocampal reaggregates as well as the native septum and hippocampus. Additionally, the temporal expression profiles observed in reaggregates were generally similar to those seen in the respective brain regions in situ. In order to determine whether NGF can modulate neurotrophin or LNGFR expression, reaggregates were cultured in the continual presence of either exogenous NGF or anti-NGF antibodies. NGF-treated septal cultures expressed twice the level of LNGFR mRNA as was seen in untreated septal cultures; on the other hand, septal cultures grown in the presence of anti-NGF antibodies, to neutralize endogenously synthesized NGF, displayed a 3-fold decrease in LNGFR mRNA expression compared to untreated cultures. No effects of NGF or anti-NGF were observed on LNGFR expression in hippocampal reaggregates, or on neurotrophin mRNA expression in either reaggregate type. These results suggest that regulatory mechanisms intrinsic to the septal and hippocampal regions control neurotrophin and LNGFR expression. NGF is likely to be one of these regulatory cues since it acts locally in septal reaggregates to control the developmental expression of LNGFR mRNA. The possible roles of locally synthesized NGF and other neurotrophins in the development of septal neurons are discussed.

A novel methodology for the study of injury mechanism: ankle fracture analysis using injury videos posted on YouTube.com

Purpose: An inherent deficiency in the understanding of the biomechanics of fractures is the reliance on cadaveric or other nonphysiological injury models resulting from the prohibitive ethical and practical considerations of conducting injury studies in live participants. We describe a novel methodology for studying injury mechanisms using in vivo injury videos obtained from Youtube.com demonstrating injuries as they occur in real time and correlating them with the resulting injury radiographs. Methods: Over 1000 video clips of potential ankle fractures were assessed for clear visualization of the mechanism of injury, including the foot position and deforming force. Candidate videos were selected if the mechanism of injury was classifiable by those described by Lauge-Hansen and there appeared to be a significant mechanism to likely cause fracture. X-rays were then requested from the individuals posting the video clips. Videos and x-rays were reviewed and classified using the Lauge-Hansen system in a blinded manner. The deforming mechanism in the video clips was classified as supination external rotation, supination adduction (SAD), pronation external rotation (PER), or pronation abduction. X-ray fracture patterns were similarly classified. Results: Two hundred forty videos were selected and individuals posting the videos were contacted. Of 96 initial positive responses, we collected 15 videos with their corresponding radiographs. Eight had SAD-deforming trauma and seven had PER-deforming trauma as appreciated in the videos. There were 12 true ankle fractures. All five fractures judged by video to be SAD injuries resulted in a corresponding SAD pattern radiographic ankle fractures. Of the seven fractures judged by video to be PER injuries, only two resulted in PER pattern radiographic ankle fractures. Five PER injuries resulted in supination external rotation ankle fracture patterns. Conclusion: Our series shows that when in vivo injury videos are matched to their corresponding x-rays, the Lauge-Hansen system is only 58% overall accurate in predicting fracture patterns from deforming injury mechanism as pertaining to SAD and PER injury mechanisms. All SAD injuries correlated but only 29% of PER injuries resulted in a PER fracture pattern. This study illustrates the ethical and practical difficulties of using public access Internet YouTube videos for the study of injury dynamics. The current case series illustrates the methods potential and may lead to future research analyzing the validity of the Lauge-Hansen classification system as applied to in vivo injuries.

Effect of Delay to Definitive Surgical Fixation on Wound Complications in the Treatment of Closed, Intra-articular Calcaneus Fractures.

Background: There are conflicting data regarding the benefits of delaying operative fixation of calcaneus fractures to decrease wound complication rates. The purpose of this study was to examine the effect of delaying fixation on wound complication rates as well as to identify other risk factors. Methods: A retrospective review at 4 institutions, including 24 surgeons, identified 405 closed, operatively treated, intra-articular calcaneus fractures. We compared fractures with and without wound complications with regards to patient demographics, medical risk factors, fracture severity, time to fixation, operative approach, primary subtalar arthrodesis, and surgeon experience. Results: Wound complications were observed in 21% (87/405) of fractures, of which 33% (29/87) required operative intervention. Male sex (P = .032), smoking (P = .028), and the extensile lateral approach (P < .001) were associated with higher complication rates. Fractures treated with an extensile lateral approach had an overall wound complication rate of 32.1%, while those treated with a sinus tarsi or percutaneous approach had an overall wound complication rate of 8.3% (odds ratio [OR], 5.3; 95% confidence interval [CI], 2.9-9.5; P < .001). Among patients treated with an extensile lateral approach, delayed operative fixation did not decrease wound complication rates despite comparable fracture severity across time points. In contrast, among fractures treated with less invasive approaches, delayed fixation beyond 2 weeks resulted in a significantly increased wound complication rate of 15.2% as compared to a wound complication rate of only 2.1% among fractures treated within a week of injury (OR, 3.2; 95% CI, 1.3-9.5; P = .01). This was observed despite similar fracture severity across time points. Primary subtalar arthrodesis did not impact complication rates. A higher wound complication rate among senior surgeons was likely secondary to their predilection for the extensile lateral approach. Conclusion: Delaying definitive fixation of closed, intra-articular calcaneus fractures did not decrease wound complication rates when using the extensile lateral approach, and we found an increased wound complication rate when using less invasive approaches. Level of Evidence: Level III, observational study.

Management of the Flexible Flat Foot in the Child: A Focus on the Use of Osteotomies for Correction

Pes planus, commonly referred as flat foot, is a combination of foot and ankle deformities. When faced with this deformity in children, the treating surgeon should use a systematic method for evaluation to distinguish normal variation from true pathology, as well as conditions that have a benign natural history versus those that may lead to significant disability if left untreated. Certain deformities will inevitably worsen and therefore require surgery. Common sense clearly supports the indication for a simple procedure, such as an arthroereisis or an osteotomy, performed in the young child as opposed to an arthrodesis in older adolescence or adulthood as the foot becomes more rigid. Such approaches and other issues are discussed in this article.

Correlation of AO and Lauge-Hansen Classification Systems for Ankle Fractures to the Mechanism of Injury

Background: Our aim was to assess whether the Lauge-Hansen (LH) and the Muller AO classification systems for ankle fractures radiographically correlate with in vivo injuries based on observed mechanism of injury. Methods: Videos of potential study candidates were reviewed on YouTube.com. Individuals were recruited for participation if the video could be classified by injury mechanism with a high likelihood of sustaining an ankle fracture. Corresponding injury radiographs were obtained. Injury mechanism was classified using the LH system as supination/external rotation (SER), supination/adduction (SAD), pronation/external rotation (PER), or pronation/abduction (PAB). Corresponding radiographs were classified by the LH system and the AO system. Results: Thirty injury videos with their corresponding radiographs were collected. Of the video clips reviewed, 16 had SAD mechanisms and 14 had PER mechanisms. There were 26 ankle fractures, 3 nonfractures, and 1 subtalar dislocation. Twelve fractures with SAD mechanisms had corresponding SAD fracture patterns. Five PER mechanisms had PER fracture patterns. Eight PER mechanisms had SER fracture patterns and 1 had SAD fracture pattern. When the AO classification was used, all 12 SAD type injuries had a 44A type fracture, whereas the 14 PER injuries resulted in nine 44B fractures, two 44C fractures, and three 43A fractures. Conclusion: When injury video clips of ankle fractures were matched to their corresponding radiographs, the LH system was 65% (17/26) consistent in predicting fracture patterns from the deforming injury mechanism. When the AO classification system was used, consistency was 81% (21/26). The AO classification, despite its development as a purely radiographic system, correlated with in vivo injuries, as based on observed mechanism of injury, more closely than did the LH system. Level of Evidence: Level IV, case series.

Relative Strengths of the Calf Muscles Based on MRI Volume Measurements

Background: In 1985, Silver et al. published a cadaver study which determined the relative order of strength of the muscles in the calf. Muscle strength, which is proportional to volume, was obtained by dissecting out the individual muscles, weighing them, and then multiplying by the specific gravity. No similar studies have been performed using in vivo measurements of muscle volume. Methods: Ten normal subjects underwent 3-Tesla MRIs of both lower extremities using non-fat-saturated T2 SPACE sequences. The volume for each muscle was determined by tracing the muscle contour on sequential axial images and then interpolating the volume using imaging software. Results: The results from this study differ from Silvers original article. The lateral head of the gastrocnemius was found to be stronger than the tibialis anterior muscle. The FHL and EDL muscles were both stronger than the peroneus longus. There was no significant difference in strength between the peroneus longus and brevis muscles. Conclusion: This revised order of muscle strengths in the calf based on in vivo MRI findings may assist surgeons in determining the optimal tendons to transfer in order to address muscle weakness and deformity.