Jonathan D. Keith

Ultrahigh Frequency Ultrasound Imaging of the Hand: A New Diagnostic Tool for Hand Surgery

Background: Ultrasonography is a cost-effective, noninvasive, and expedient imaging modality with numerous clinical applications. Conventional ultrasound uses transducers with frequencies that range from 5 to 12 MHz. However, ultrahigh frequency ultrasound (UHFUS) is capable of producing frequencies up to 70 MHz, which can achieve tissue resolution up to 30 μm. The purpose of our study is to present the capabilities of a novel technology and to describe its possible clinical applications for hand surgery. Methods: The Vevo 2100 (VisualSonics, Toronto, Canada) system was used to perform all ultrasound exams. Four unique linear array transducers were employed. All studies were performed by the authors, who have no formal training in ultrasound techniques, on 5 healthy resident volunteers and 1 clinical patient under institutional review board approval. Results: A series of 10 static images per participant and dynamic, real-time videos were obtained at various locations within the hand and wrist. UHFUS is capable of quickly and reliably imaging larger structures such as foreign bodies, soft tissue masses, and the flexor tendons, and diagnosing an array of pathologies within these structures. In addition, UHFUS can identify much finer structures such as the intimal layer of the arteries in the hand and individual fascicles within the digital nerves to provide data about vessel quality and vascular and neural pathologies. Conclusions: UHFUS is a novel technology that shows multiple advantages over conventional ultrasound for imaging the fine superficial structures of the hand and wrist, and can be deployed by the surgeon at the point of care.

Shift toward Mechanical Isolation of Adipose-derived Stromal Vascular Fraction: Review of Upcoming Techniques

Background: Standard isolation of adipose stromal vascular fraction (SVF) requires the use of collagenase and is considered more than “minimally manipulated” by current good manufacturing practice requirements. Alternatively, nonenzymatic isolation methods have surfaced using physical forces to separate cells from the adipose matrix. The purpose of this study was to review the literature on the use of mechanical isolation protocols and compare the results. The implication for use as a standard procedure in practice is discussed. Methods: A systematic review of the literature was performed on mechanical isolation of SVF with a search of six terms on PubMed and Medline databases. One thousand sixty-six articles were subject to evaluation by predetermined inclusion and exclusion criteria. Results: Two level 2 evidence articles and 7 in vitro studies were selected. SVF was isolated using automated closed systems or by subjecting the lipoaspirate to centrifugation only or by shaking or vortexing followed by centrifugation. Six articles reported isolation in laboratory settings and three inside the operating room. Stromal vascular cells expressed CD34, and CD44, CD73, CD90, and CD105, and differentiated along adipogenic and osteogenic lineages. When compared with enzymatic methods, mechanical isolation required less time but yielded fewer cells. Both case–control studies reported improved volume retention with cell-supplemented fat grafts for breast reconstruction. Conclusions: Mechanical isolation methods are alternatives to circumvent safety issues posed by enzymatic protocols. However, randomized comparative studies with long-term clinical outcomes using mechanically isolated stromal vascular cells are needed to identify their ideal clinical applications.

Abstract QS14: Restoration of Flap Sensation Using Neurotized Anterolateral Thigh Flaps for Lower Extremity Reconstruction

PURPOSE: The purpose of this study is to assess clinical outcomes for utilization of vein grafts and arteriovenous loops in the context of free flap reconstruction. Free tissue transfer in complex oncological and traumatic defects may require extension of the vascular pedicle to reach recipient vessels and complete microvascular anastomosis. This can be accomplished by using vein grafts as a bridging medium. When interposition vein grafts (IVG) are needed for extension of both the arterial and venous conduit, a temporary arteriovenous fistula (AV loop) can be constructed as an intermediary step. These techniques have traditionally been regarded with increased risk of thrombosis and flap failure, but the body of clinically relevant published data lags behind.

Reverse Sural Artery Flap

The reverse sural artery flap is utilized to reconstruct defects in the distal third of the lower leg, ankle, and heel. This flap is based on perforators of the peroneal artery system. The flap consists of superficial and deep fascia, the sural nerve, lesser saphenous vein, and superficial sural artery. A skin island may be demarcated at any point along the distal lateral leg containing the lesser saphenous vein and sural nerve on its central axis. The distal dissection is located 5 cm above the lateral malleolus to preserve the peroneal artery.