Faculty Bibliography

Ear mesenchymal stem cells (EMSCs) represent a readily accessible population of stem-like cells that are adherent, clonogenic, and have the ability to self-renew. Previously, we have demonstrated that they can be induced to differentiate into adipocyte, osteocyte, chondrocyte, and myocyte lineages. The purpose of the current study was to characterize the growth kinetics of the cells and to determine their ability to form colonies of fibroblasts, adipocytes, osteocytes, and chondrocytes. In addition, the immunophenotypes of freshly isolated and culture-expanded cells were evaluated. From 1 g of tissue, we were able to isolate an average of 7.8 x 10(6) cells exhibiting a cell cycle length of approximately 2-3 days. Colony-forming unit (CFU) assays indicated high proliferation potential, and confirmed previously observed multipotentiality of the cells. Fluorescence-activated cell sorting (FACS) showed that EMSCs were negative for hematopoietic markers (CD4, CD45), proving that they did not derive from circulating hematopoietic cells. The FACS analyses also showed high expression of stem cell antigen-1 (Sca-1) with only a minor population of cells expressing CD117, thus identifying Sca-1 as the more robust stem cell biomarker. Additionally, flow cytometry data revealed that the expression patterns of hematopoietic, stromal, and stem cell markers were maintained in the passaged EMSCs, consistent with the persistence of an undifferentiated state. This study indicates that EMSCs provide an alternative model for in vitro analyses of adult mesenchymal stem cells (MSCs). Further studies will be necessary to determine their utility for tissue engineering and regenerative medical applications.

BACKGROUND: Management of severe traumatic lower extremity injuries remains a considerable challenge. Free tissue transfer is now a standard part of reconstruction for Gustilo IIIB and IIIC injuries. There is limited information on arterial injury patterns in this population. We undertook a review of our experience to gain insight on vascular injury patterns and surgical outcomes. STUDY DESIGN: A 26-year retrospective analysis was performed of all lower extremity Gustilo IIIB and IIIC injuries requiring microvascular reconstruction at New York University Medical Center. Patient demographics, Gustilo classification, angiographic findings (conventional/computed tomographic angiography/magnetic resonance angiography), recipient vessels, elapsed time from injury, flap choices, and outcomes were examined. RESULTS: Two hundred twenty-two free flaps on 191 patients were performed from September 1982 until March 2008. There were 151 males and 40 females ranging in age from 4 to 83 years (median age 33 years). Patients sustained either Gustilo IIIB (170 patients) or IIIC (21 patients) open fractures. One hundred fifty-four patients had angiograms (78.2% IIIB, 100% IIIC). Sixty-six (42.9%) had normal 3-vessel runoff and 88 (57.1%) were abnormal. Sixty-one patients (31.9%) had anterior tibial injuries, 17 patients (8.9%) had posterior tibial injuries, and 30 (15.7%) had peroneal injuries. Sixty-three complications occurred (11 early thrombosis, 33 requiring secondary procedures, and 10 requiring amputation). CONCLUSIONS: Angiography of severe lower extremity injuries requiring free flap reconstruction usually revealed arterial injury and is generally indicated. In our experience, the anterior tibial artery is most commonly injured and the posterior tibial artery is most likely to be spared and used as a recipient

BACKGROUND: Atypical claudication is a relatively uncommon problem within the general population. However, suspicion for the diagnosis is raised when young and athletic patients present with symptoms of claudication during exercise. The most common causes of atypical claudication are anatomical variants, including popliteal artery entrapment syndrome and tarsal tunnel syndrome. These variants result in impaired arterial flow and nerve compression, respectively. In this report, we present a seminal case of dorsalis pedis artery entrapment by the extensor hallucis brevis tendon during active dorsiflexion of the foot. METHODS: The patient was a 42-year-old male without significant past medical history, who presented with claudication in both feet upon active dorsiflexion. He underwent dynamic arterial duplex studies that first revealed normal flow in the neutral position and then revealed complete cessation of flow in both duplex and Doppler modes on dorsiflexion of the foot. He also underwent dynamic magnetic resonance angiography of bilateral lower extremities that revealed an incomplete pedal arch with early termination of the posterior tibial artery on static images and termination of the dorsalis pedis artery at notching on the dorsum of the foot during dorsiflexion. The patient was taken to the operating room for bilateral dorsalis pedis artery exploration. During exploration, the patient was found to have entrapment of the dorsalis pedis artery by the extensor hallucis brevis (EHB) tendon. This was documented by both direct visualization and intraoperative cessation of Doppler signal on dorsiflexion. Since the EHB tendon provides only secondary function to the extensor hallucis longus (EHL) tendon, the EHB was transected near its insertion and transposed directly to the EHL tendon. This allowed for normal extensor function of the great toe and restored triphasic Doppler signals during dorsiflexion. CONCLUSION: Dorsalis pedis arterial entrapment is a novel cause of atypical claudication. It is extremely uncommon as patients must have both abnormal anatomy and an incomplete pedal arch to display symptoms. Similar to other entrapment syndromes, if identified before permanent arterial scarring, the treatment does not require a bypass procedure. Removal of the tendon along with transposition will allow cessation of symptoms without impaired dorsiflexion of the great toe

AlloDerm has been used as a tissue supplement in conjunction with the pectoralis major muscle to provide full coverage over an implant in breast reconstruction. While this method of reconstruction has shown promising results there is little known on the relationship of AlloDerm size and potential immediate expansion volume. A retrospective chart review was completed evaluating all tissue expander or primary implant reconstructions using AlloDerm. Data recorded included: The type/size of implant/expander, dimensions of the AlloDerm used, initial fill volume, number of expansions and time period of expansion. Statistical analysis was completed with a linear regression model. AlloDerm was used on 49 patients (72 reconstructions). Thirty-four patients (50 reconstructions) underwent reconstruction with a tissue expander and 15 patients (22 reconstructions) underwent a single stage reconstruction with a permanent implant. The tissue expander volume filled (cc) could be predicted by 5 x surface area of AlloDerm (cm(2)) - 12 (R(2) = 0.62) and 80 x height of AlloDerm (cm) - 15 (R(2) = 0.59). The tissue expanders could be filled to an average of 75% of total size and required three to four injections in the postoperative period to reach full expansion. Obviously, a requirement for maximal implant expansion is an appropriate skin sparing mastectomy. There is a mathematical relationship between fill volume and surface area as well as height of AlloDerm used in breast reconstruction. This analysis provides a guideline for immediate implant expansion to surgeons using AlloDerm in reconstructive breast surgery

BACKGROUND: In posttraumatic brachial plexus palsy, shoulder stabilization is of utmost importance before reanimation of the distal upper extremity. The aim of this study was to present the authors' experience with axillary nerve reconstruction in 148 patients with posttraumatic plexopathy. Functional outcomes were assessed and correlated with the following factors: severity score, denervation time, and donor nerve used. METHODS: The medical records of 176 patients who underwent axillary nerve reconstruction performed by a single surgeon between 1978 and 2006 were reviewed. The results were analyzed in 148 patients who had adequate follow-up (>24 months). Nerve reconstruction was performed using 94 intraplexus donor nerves and 55 extraplexus donor nerves; axillary-to-axillary repair was performed in 13 patients, and 15 patients had microneurolysis. One hundred forty patients had interposition nerve grafts. A total of 135 patients had concomitant neurotization of the suprascapular nerve. RESULTS: Results were good or excellent in 45.95 percent of patients. The intraplexus donors yielded significantly better shoulder function than the extraplexus donors. The length of the nerve graft had a direct influence on deltoid recovery. Patients with a severity score higher than 10 attained significantly better results than patients with multiple root avulsions. Surgery earlier than 4 months yielded significantly better functional outcomes than delayed operation of more than 8 months. CONCLUSIONS: Early primary axillary nerve reconstruction offers rewarding glenohumeral joint stability and an acceptable range of shoulder function. Concomitant neurotization of the suprascapular nerve yielded improved outcomes in shoulder abduction and external rotation

The positive results of the performance of zirconia for orthopedics devices have led the dental community to explore possible esthetical and mechanical outcomes using this material. However, questions regarding long-term results have opened strong and controversial discussions regarding the utilization of zirconia as a substitute for alloys for restorations and implants. This narrative review presents the current knowledge on zirconia utilized for dental restorations, oral implant components, and zirconia oral implants, and also addresses laboratory tests and developments, clinical performance, and possible future trends of this material for dental healthcare.