American Association for Hand Surgery | 2015 Annual Meeting 1
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Oral Presentation Abstracts 1. Side-to-side vs. Pulvertaft Extensor Tendon Repair; Biomechanical Study Michael Rivlin, Amir Reza Kachooei, MD, Ali Hosseini, PhD, Kyle Eberlin, MD, Nikola Zivaljevic, MD, Guoan Li, PhD and Chaitanya S. Mudgal, MD Department of Orthopaedics, Massachusetts General Hospital, Harvard University, Boston, MA Introduction: Extensor tendons can be coapted using a weave suture technique to provide tensile strength and repair surface overlap. Pulvertaft (PT) weave is the standard method of extensor tendon repair. However, recently, Brown and colleagues described a side-to-side (STS) tendon repair technique (one weave). This method may compare in speed of repair, while simpler, potentially less bulky and without the need specialized equipment while not compromising repair strengths and tensile properties. We hypothesize that STS is more practical than PT with matching biomechanical characteristics. Materials and Methods: In a biomechanical study on 6 cadaver arms, we harvested 30 extensor tendons including four extensor digitorum communis (EDC) and one extensor indicis proprius (EIP). Three hand surgical fellows with similar backgrounds of training under the same conditions and precise standardized technique performed timed repairs (5 PT and 5 STS per surgeon). Following the repairs, the tendons were passed through a custom made graft sizing guide to determine bulk and the results were expressed as a repaired vs. native diameter ratio. The specimens were then tested for ultimate strength and fatigue properties (Instron Inc., Norwood, MA). Failure type and mechanical properties were recorded and compared to the native tendon portion. Results: The STS technique demonstrated comparable time to repair (average tendon repair STS: 8.16 min vs. PT: 7.38 min ; P=0.14). The average peak force to failure was 93 N for the STS and 51 N for PT group (P<0.001). Relative strength ratio (repair strength compared to native tendon strength) was 35.2% for the STS and 22.1% for the PT group (P=0.19). In the side-to-side group all failures occurred due to tissue failure; however, in the Pulvertaft technique suture failures occurred in 3 tendons prior to tissue failure. The mean bulk ratio of the repaired site vs. native tendon was +31% and +34% more for the STS and PT groups respectively (P=0.78). Furthermore, the bulk of the repaired site for the STS and PT groups was 4.2 and 4.9 mm respectively (P=0.098). Conclusion: Side-to-side repair technique showed superior biomechanical properties while demonstrating comparable repair bulk and speed of tendon coaptation compared to the Pulvertaft weave. AMERICAN ASSOCIATION FOR HAND SURGERY | 2015 ANNUAL MEETING 1 2. Does Barbed Suture Repair Negate the Benefits of Peripheral Repair in Porcine Flexor Tendon? Alan Sull, MD; Serkan Inceoglu, PhD; Montri Wongworawat, MD Orthopaedic Surgery, Loma Linda University Medical Center, Loma Linda, CA Introduction: Recent advances in suture materials and geometry have fueled interest in application of barbed sutures for flexor tendon repair. Theoretically, barbed suture tenorrhaphy offers benefits in better load distribution along the entire suture length, smoother gliding under pulleys with decreased cross-sectional area under load, and improved tendon blood flow by reduction of constricting forces. Studies have compared barbed suture to conventional non-barbed suture repair of flexor tendons, with varying suture patterns, loading properties, and tendon models. Some controversy exists on whether barbed tendon repair would benefit from supplementation by a circumferential stitch. Only one study to date has reported tensile strength of barbed suture repair in flexor tendons with additional peripheral repair, but findings were limited by an unconventional model resulting in substantially higher failure loads than previously published. The purpose of this study is to determine whether peripheral repair increases gap resistance in both conventional and barbed suture core repairs, to study if peripheral repair increases ultimate tensile strength, and to examine differences in failure sequence. Materials and Methods: Porcine flexor tendons were harvested and assigned randomly into 4 groups (3-0 PDS or 3-0 V- loc 180 core with or without peripheral 5-0 Vicryl repair). Core repairs were performed using a modified 4-strand cruciate repair with 10 mm suture purchase and 4 mm cross-locks. Knotless repair was done using barbed suture, while a buried 6- throw square knot was done using conventional suture. An servohydraulic tester was used for biomechanical testing of linear 2 mm gap resistance and maximum tensile strength. Results: The loads at 2 mm gap formation were 22.6 ± 3.8 N and 25.1 ± 4.0 N for conventional and barbed suture repairs respectively, while repairs with additional peripheral suture measured 61.7 ± 5.0 N and 76.4 ± 21.1 N. No significant difference was found between core suture types in gap resistance. No difference was found in maximum load to core suture failure among all groups. A statistically significant difference was found in maximum load to peripheral repair failure, which measured 57.8 ± 12.2 N in conventional repairs and 74.2 ± 20.4 N in barbed core repairs. Conclusions: The addition of peripheral repair enhanced 2 mm gap resistance but not maximum core tensile strength in both conventional and barbed flexor tendon repairs. There may be a greater synergistic effect of peripheral repair with barbed over conventional core repairs. Barbed suture core repairs present a viable alternative to conventional repairs. AMERICAN ASSOCIATION FOR HAND SURGERY | 2015 ANNUAL MEETING 2 3. Anatomy of the Flexor Digitorum Profundus Insertion Kyle J. Chepla, MD; Robert J. Goitz; John R. Fowler, MD Orthopaedic Surgery, University of Pittsburgh Medical Center, Pittsburgh, PA Introduction: Treatment of zone I flexor digitorum profundus (FDP) injuries requires reattachment of the tendon to the distal phalanx. Previous studies have evaluated the biomechanical strength of various repair techniques; however, none have described the anatomy of the FDP insertion or the proper location of an anatomic repair. We believe that correct placement of the tendon is essential to better restore native biomechanics and may improve clinical outcomes. Methods: The FDP insertion to the index, middle, ring and little fingers were dissected in ten fresh-frozen cadavers. The FDP tendon was bluntly dissected off the volar plate, which was elevated from proximal to distal, before the distal phalanx was disarticulated. The distal phalanx was then inked and the FDP was sharply dissected off the bone (Figure 1). The insertion length, width, and distance from the joint of the insertion were measured and then the insertion surface area and centroid of the FDP insertion were calculated. Results: The average insertion length and width were 6.2 mm (range 5.1-7.0) and 7.9 mm (range 6.9-8.4) respectively. The average surface area of the distal phalanx occupied by the FDP tendon, for all fingers, was 20.1% (range 15.0-26.5) (Table 1). The average distance from the most proximal insertion to the joint surface was 1.2 mm (range 0.4-2.1) with the intervening space occupied by the volar plate insertion, and the calculated distance of the centroid of the FDP insertion from the DIP joint was 3.6 mm (range 2.5-5.1) or approximately 20% of the phalangeal length (Tables 2 and 3). Conclusions: The percentage of the distal phalanx occupied by the insertion of the FDP tendon into the distal phalanx, the distance of the most proximal FDP insertion from the joint, and the distance from the joint to the centroid of the insertion are fairly consistent in all fingers and not gender specific. Furthermore, the shape of the FDP insertion, widest proximally and tapering distally, was consistent amongst specimens. The findings of this study will allow for proper positioning of the FDP repair on the distal phalanx independent of the technique chosen. It remains to be seen whether this will restore the native biomechanics of the finger and improve patient outcomes. AMERICAN ASSOCIATION FOR HAND SURGERY | 2015 ANNUAL MEETING 3 AMERICAN ASSOCIATION FOR HAND SURGERY | 2015 ANNUAL MEETING 4 4. Relative Motion Flexion Splinting for Flexor Tendon Repairs: Proof of Concept Bryan Chung, MD, PhD1; Vishal Thanik, MD2; David T.W. Chiu, MD3 1Plastic Surgery/ Hand Program, University of Toronto, Toronto, ON, Canada; 2Institute of Reconstructive Plastic Surgery, New York University Medical Center, New York, NY; 3Plastic Surgery, NYU Langone Medical Center, New York, NY Purpose: Early active motion protocols after flexor tendon repair have resulted in a better range of motion and decrease in flexion contractures, but still involve long periods of immobilization with interspersed sessions of motion, and activities of daily living are usually significantly impaired. The principle of relative motion in extensor tendon repairs has allowed patients to regain a higher degree of hand function, while protecting the repair. The purpose of this study was to determine if the principle of relative motion could be a feasible method to protect a flexor tendon repair. Methods: Four fresh frozen cadaver arms were used in this study. The flexor digitorum profundus (FDP) tendons of the middle fingers were dissected in the palm (zone 3) distally, while the muscles of the FDP and extensor digitorum communis were dissected proximally in the forearm. Each arm was mounted on a testing apparatus with the wrist in 30 degrees of extension, and the MCP joints blocked to 70- 80 degrees. A minimum of 11N was used to cyclically load the FDP and EDC tendons to maximum allowable flexion and extension for 25 cycles. Measurements of elongation of the tendons were obtained through the use of differential variable reluctance transducers (Lord Microstrain, Williston, VT). Following intact tendon testing, a tenotomy was made in the FDP tendon of the middle finger in zone 3 and immediately repaired with a single 6-0 nylon suture.