Faculty Bibliography

Bone is a viscoelastic connective tissue composed primarily of mineral and type I collagen, which interacts with water, affecting its mechanical properties. Therefore, both the level of hydration and the loading rate are expected to influence the measured nanomechanical response of bone. In this study, we investigated the influence of three distinct hydration conditions, peak loads and loading/unloading rates on the elastic modulus and hardness of canine femoral cortical bone via nanoindentation. Sections from three canine femurs from multiple regions of the diaphysis were tested for a total of 670 indentations. All three hydration conditions (dry, moist and fully hydrated tissue) were tested at three different loading profiles (a triangular loading profile with peak loads of 600, 800 and 1000muN at loading/unloading rate of 60, 80 and 100muN/s, respectively; each test was 20s in duration). Significant differences were found for both the elastic modulus and hardness between the dry, moist and fully hydrated conditions (p0.05). However, in both the moist and fully hydrated conditions, the elastic modulus and hardness were significantly different under all loading profiles (with the exception of the moist condition at the 600- and 800-muN peak load). Given these findings, it is critical to perform nanoindentation of bone under fully hydrated conditions to ensure physiologically relevant results. Furthermore, this work found that a 20-s triangular loading/unloading profile was sufficient to capture the viscoelastic behavior of bone in the 600- to 1000-muN peak load range. Lastly, specific peak load values and loading rates need to be selected based on the structural region for which the mechanical properties are to be measured.

OBJECTIVE: This study evaluated the effect of drilling speed on early bone healing in dog tibiae. STUDY DESIGN: Thirty-six implants (4.0-mm diameter x 10-mm length) were placed in the proximal tibiae of 6 beagles with drilling speeds of 100, 500, and 1000 rpm, and insertion torque was recorded. Bone-to-implant contact (BIC) and bone area fraction occupancy (BAFO) were evaluated. RESULTS: Significant increase from 1 to 3 weeks was observed for all groups for BIC, whereas no significant differences between 1 and 3 weeks were detected for the 100- and 500-rpm groups for BAFO (P > .34 and P > .46, respectively). A significant difference from 1 to 3 weeks was observed for the 1000-rpm group (P < .03). The 100- and 500-rpm groups presented significantly higher BAFO than the 1000-rpm group at 1 week (P = .002). CONCLUSIONS: Drilling speed is one of the decisive factors for early osseointegration, and overall, drilling at 1000 rpm seemed to yield the strongest biologic responses.

BACKGROUND: Acellular dermal matrix is a commonly used adjunct in implant-based breast reconstruction. Several investigations have shown increased complications associated with its use. Therefore, the authors' institution placed strict limitations on its use and transitioned to sterile "ready-to-use" acellular dermal matrix. The purpose of this investigation was to compare the infectious complications associated with aseptic versus sterile acellular dermal matrix. METHODS: A prospective study of all patients undergoing immediate implant-based breast reconstruction at a single academic medical center between November of 2010 and October of 2012 was conducted. AlloDerm (Life Cell Corporation, Branchburg, N.J.) was used as the source of acellular dermal matrix. Breasts were divided into three cohorts: total submuscular coverage, aseptic acellular dermal matrix, and sterile, ready-to-use acellular dermal matrix. Breasts were then compared based on demographic information, cancer qualities, and complications. RESULTS: A total of 546 reconstructed breasts met inclusion criteria: 64.3 percent (n = 351) with no acellular dermal matrix, 16.5 percent (n = 90) with aseptic matrix, and 19.2 percent (n = 105) with ready-to-use matrix. When comparing reconstructions with ready-to-use versus aseptic acellular dermal matrix, patients had a decrease in overall infection (8.5 percent versus 20.0 percent; p = 0.0088), major infection (4.7 percent versus 12.2 percent; p = 0.069), and need for explantation (1.9 percent versus 6.6 percent; p = 0.1470). When comparing patients undergoing reconstruction with ready-to-use matrix to total submuscular coverage, patients had similar overall infectious complications (8.5 percent versus 5.7 percent; p = 0.3602). Diabetes mellitus, seroma, mastectomy skin flap necrosis, and aseptic acellular dermal matrix were independent predictors of infectious complications. CONCLUSIONS: Ready-to-use acellular dermal matrix in immediate implant-based breast reconstruction provides a useful adjunct. In addition, it mitigates the risks of infectious complications when compared with aseptic acellular dermal matrix. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, II.

Publisher: Abstract available from the publisher.

INTRODUCTION: Ventral hernia repair (VHR) continues to evolve and now frequently includes some form of component separation (CS) for large defects. To determine the optimal technique for VHR, we evaluated our outcomes before and after we refined and simplified our algorithm for repair. METHODS: One hundred five consecutive patients undergoing VHR for large midline hernias over 9 years were examined. Patients were divided into those operated on after (group 1) and before (group 2) the institution of our simplified algorithm. Our algorithm emphasizes careful patient selection and a stepwise approach including, but not limited to, bilateral CS if appropriate, preservation of large perforators, retrorectus mesh placement as appropriate, linea alba or midline fascial closure, and vertical panniculectomy. Primary outcomes evaluated included wound infection, dehiscence, and hernia recurrence. RESULTS: Seventy-eight (74.3%) patients underwent repair using our algorithm (group 1), whereas 27 (25.7%) underwent repair before utilization of this algorithm (group 2). Ninety-eight (93.3%) underwent CS, whereas 7 (6.7%) underwent another form of VHR. There was no significant difference in patient age or defect size. The mean follow-up period in days for patients in group 1 and group 2 were 184.02 and 526.06, respectively (P < 0.001). Hernia recurrence in group 1 was 2.6% versus 29.6% in group 2 (P < 0.001). The incidence of wound infection in group 1 was 10.3%, whereas that in group 2 was 33.3% (P < 0.001). The rate of wound dehiscence in group 1 was 17.9% versus 25.9% in group 2 (P < 0.001). CONCLUSIONS: Simplifying and unifying our algorithm for VHR, notably with utilization of CS, has yielded improved results. Recurrence and wound healing complications using this approach are favorable compared with published outcomes.

PURPOSE:: Commercial implants differ at macro-, micro-, and nanolevels, which makes it difficult to distinguish their effect on osseointegration. The aim of this study was to evaluate the early integration of 5 commercially available implants (Astra OsseoSpeed, Straumann SLA, Intra-Lock Blossom Ossean, Nobel Active, and OsseoFix) by histomorphometry and nanoindentation. MATERIALS AND METHODS:: Implants were installed in the tibiae of 18 beagle dogs. Samples were retrieved at 1, 3, and 6 weeks (n = 6 for each time point) and were histologically and nanomechanically evaluated. RESULTS:: The results presented that both time (P < 0.01) and implant system and time interaction (P < 0.02) significantly affected the bone-to-implant contact (BIC). At 1 week, the different groups presented statistically different outcomes. No significant changes in BIC were noted thereafter. There were no significant differences in rank elastic modulus (E) or in rank hardness (H) for time (E: P > 0.80; H: P > 0.75) or implant system (E: P > 0.90; H: P > 0.85). CONCLUSIONS:: The effect of different implant designs on osseointegration was evident especially at early stages of bone healing.

BACKGROUND: The purpose of this study was to characterize soft-tissue profile changes following Le Fort III (midface) distraction in growing patients with syndromic craniosynostosis. METHODS: The cohort consisted of 20 syndromic patients who underwent Le Fort III osteotomy with midface advancement using a rigid external distraction device. The mean age at surgery was 5.7 years (range, 3 to 12.5 years). Lateral cephalograms were obtained preoperatively (time 1), after distraction device removal (time 2), and 1 year after distraction (time 3). Ten skeletal hard-tissue and 11 soft-tissue profile landmarks were identified and digitized at time points 1, 2, and 3. The x and y displacement of each landmark was studied to determine the ratios for soft- to hard-tissue change. RESULTS: The horizontal ratio of soft- to hard-tissue change for nasal dorsum to orbitale was 0.73:1 and the soft-tissue tip of nose to the anterior nasal spine was 0.86:1. The horizontal ratio of soft-tissue A point to hard-tissue A point was 0.88:1. The horizontal ratio of the upper lip position to the labial surface of maxillary incisor was 0.88:1. The ratio for nasal tip elevation to the anterior nasal spine advancement was 0.27:1. CONCLUSIONS: The result of this study supported the hypothesis that there exists a linear relationship between soft- and hard-tissue changes in the horizontal direction for the midface landmarks following Le Fort III distraction. However, there was a nonlinear relationship between soft- and hard-tissue changes in the vertical direction. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, IV.