Biomechanical Head-to-Head Comparison of 2 Sutures and the Giftbox vs Bunnell Techniques for Midsubstance Achilles Tendon Ruptures

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1 Biomechanical Head-to-Head Comparison of 2 Sutures and the Giftbox vs Bunnell Techniques for Midsubstance Achilles Tendon Ruptures Rufus Van Dyke MD, Roman Trimba MD, Greg Gould BS, Sejul Chaudary BS, Jessica Lee MD, Richard Laughlin MD Wright State Orthopaedics, Sports Medicine & Rehabilitation

2 Conflicts to Disclose Biomechanical Head-to-Head Comparison of 2 Sutures and the Giftbox vs Bunnell Techniques for Midsubstance Achilles Tendon Ruptures Presenter: Rufus Van Dyke MD The following authors have conflicts to disclose: Rufus Van Dyke MD Role: Principle Investigator My disclosure is in the final AOFAS mobile app. Received materials at no cost for specimen fixation from Arthrex, LCC. No other forms of compensation were received in the conduction of this analysis

3 Introduction Midsubstance Achilles tendon repairs commonly have issues with overlengthening and wound healing. Previous studies have aimed to minimize these complications, testing many combinations of different surgical techniques and suture types. Thus far results have been inconclusive. Our study compares two non-absorbable braided sutures headto-head, employing a recently introduced stitch, the Giftboxmodified Krackow. Secondly, we also test the Giftbox head-to-head against another more established stitch, the Bunnell.

4 Methods: Trial 1 Fiberwire vs. Ultrabraid 10 pairs of fresh frozen cadaver gastrocnemius/achilles/calcanei were harvested and the Achilles transected with a scalpel 4 cm proximal to its insertion. Each left Achilles was randomized to receive #2 Ultrabraid or #2 Fiberwire for a Giftbox modified Krackow repair. All Achilles also received an epitendonous repair with 3-0 polypropylene suture to appose the tendon ends. After a single surgeon performed all 20 repairs, the calcanei were mounted onto an EnduraTec test frame with the Achilles placed at a 30 angle to simulate the physiologic stress of early heel rise. After preconditioning the tendon at 10 N, cyclic loading was then performed from 10 to 100 N at 2 Hz for 1000 cycles in a sinusoidal waveform. Calipers were used to measure any gapping between the tendon ends after 500 and 1000 cycles. Any specimen that exhibited over 5 mm of gapping was considered a gapping failure and immediately removed from any further testing. All remaining specimens underwent load-to-failure testing at a rate of 0.2 mm/sec. A clinical failure point was recorded with any slippage of the construct and maximum load to failure recorded at the point of catastrophic failure.

5 Trial 2: Giftbox vs Bunnell 10 pairs of fresh frozen cadaver gastrocnemius/achilles/calcanei were harvested and an incision was made 4 cm proximal to the Achilles insertion on the calcaneus. Each left Achilles was randomized to receive a Giftboxmodified Krackow or Bunnell repair. #2 Fiberwire was used to for all repairs. All Achilles also received an epitendonous repair with 3-0 polypropylene suture to appose the tendon ends. After the same single surgeon performed all 20 repairs, the testing set up and procedure was the same as in trial 1. 2 specimens showed over 5 mm of tendon gapping after 1000 cycles. Those specimens along with the contralateral specimen were not included in loadto-failure testing. All remaining specimens underwent load-to-failure testing at a rate of 0.2 mm/sec, noting when the gap between the tendon ends reached 5 mm and finally the maximum load at catastrophic failure. Giftbox (left) and Bunnell Specimens loaded on the EnduraTec machine. The core sutures have been dyed black for visual contrast.

6 Trial 1 Results No gapping failures occurred during cyclic loading Fiberwire withstood significantly higher loads than Ultrabraid before clinical load-to-failure was reached (361 N vs 239 N) No significant difference in maximum load-to-failure Trial 1 Fiberwire Ultrabraid P - value Number of Specimens Mean Clinical Load-to-Failure (N) 361 +/ / Mean Max Load to Failure (N) 415 +/ / Mean Linear Displacement after 1000 cycles (mm) / /

7 Trial 2 Results Two gapping failures were observed during cyclic loading, both from the Bunnell group. Two other specimens in the Bunnell group recorded tendon gapping over 2 mm. Trial 2 - Cyclic Loading Giftbox Bunnell P - Value Number of Specimens 9 9 Failed Specimens During Cyclic Loading 0 2 Specimens with gapping over 2 mm 0 4 Mean Linear Displacement after 1000 cycles (mm) Mean clinical load-to-failures were 353 N for Giftbox and 285 N for Bunnell. Trial 2 - Load to Failure Giftbox Bunnell P - Value Number of Specimens 7 7 Mean Clinical Load-to-Failure (N) 353 +/ / Mean Max Load-to-Failure (N) 361 +/ / Bone failures occurred at the mounting Steinman pin during cyclic loading in both calcanei from a single cadaver. These specimen were removed from the study without data inclusion.

8 Results: Trial 1 vs. Trial 2 The was no significant difference between the clinical load-to-failure values when comparing the two Giftbox + Fiberwire groups in Trials 1 and 2. Fiberwire + Giftbox: Trial 1 vs Trial 2 Trial 1 Trial 2 Total Samples 10 7 Mean Clinical Load to Failure (N) Standard Deviation Unpaired Student T-test 0.9 Cadaver Demographics Trial 1 Trial 2 Total Sample Size 10 9 Mean Age (P = 0.98) Age Rage Males 5 5 Females 5 4 The average age of the cadavers was 73.9 years. The distribution of males and females was comparable. There were no significant differences between the cadavers used in each of the two groups

9 Discussion: Fiberwire vs. Ultrabraid Achilles tendons repaired with the Giftbox technique and #2 Fiberwire suture exhibited superior biomechanical characteristics with significantly higher clinical load failure as well as linear displacement (stiffness), in comparison to repairs performed using Ultrabraid (p = 0.005). Linear displacement was less with Fiberwire; however, it did not reach statistical significance (p = 0.20 and p = 0.33). These results are likely due to material and structural differences between the two sutures. Ultrabraid seemed to pull through tissues more easily, potentially leading to the lower observed clinical load-to-failure values. Maximum load-to-failure did not appear to be clinically relevant. We observed that it typically occurred well after the knot slid through the tissue and many times after over 1 cm of gapping had occurred.

10 Discussion: Giftbox vs. Bunnell The two instances of gapping failures during cyclic load with the Bunnell technique were likely due to the non-locking nature of the stitch and having only 2 of the core sutures crossing the repair site vs. the 4 sutures of the Giftbox. The Bunnell does not loop through the tendon as many times or lock. Therefore, the Bunnell may not grasp the tendon as well and force is not distributed as evenly throughout the construct. Removing the gapping failures before load-to-failure testing likely decreased the difference between the load-to-failure values for the Giftbox and Bunnell because the repairs that gapped during cyclic loading would likely have registered lower clinical load-to-failure values than their Giftbox counterparts that survived cyclic loading. Giftbox-modified Krackow Given our observations of gapping during cyclic loading and current postoperative rehab protocols that allow early weight bearing, future testing should use a more intensive and extended cyclic loading model. Single displacement driven load-to-failure testing does not reflect the repetitive nature of rehab and did not adequately capture the biomechanical differences noted with cyclic loading in this study. This is especially true for maximum load-to-failure, as many of the values we obtained were recorded when tendon ends were gapped over 1 cm. Bunnell

11 Conclusion The Giftbox-modified Krackow outperformed the Bunnell in a head-tohead biomechanical comparison, behaving as a stiffer construct during cyclic loading. There was also a trend toward higher clinical load-to-failure values, but it was not statistically significant. Fiberwire suture is associated with significantly stronger Achilles tendon repairs than Ultrabraid in biomechanically tested cadaver tendons. This study s experimental design produced consistent results Giftbox + Fiberwire repairs from Trial 1 and Trial 2 behaved almost identically under biomechanical testing. More head-to-head comparisons of fixation combinations in human specimens are needed to determine a single, optimal repair construct. Maximum load-to-failure values appeared to lack clinical relevance.

12 References 1. Gebauer M, Beil FT, Beckmann J, et al. Mechanical evaluation of different techniques for Achilles tendon repair. Arch Orthop Trauma Surg. 2007;127(9): Soroceanu A, Sidhwa F, Aarabi S, Kaufman A, Glazebrook M. Surgical versus nonsurgical treatment of acute Achilles tendon rupture: a meta-analysis of randomized trials. J Bone Joint Surg Am. 2012;94(23): Maquirriain J. Achilles tendon rupture: avoiding tendon lengthening during surgical repair and rehabilitation. Yale J Biol Med. 2011;84(3): Lee SJ, Goldsmith S, Nicholas SJ, Mchugh M, Kremenic I, Ben-avi S. Optimizing Achilles tendon repair: effect of epitendinous suture augmentation on the strength of achilles tendon repairs. Foot Ankle Int. 2008;29(4): Hong Y, Hermida L, White KL, Parks BG, Camire LM, Guyton C. Core weave versus Krackow technique for Achilles tendon repair: a biomechanical study. Foot Ankle Int. 2010;31(12): Sadoghi P, Rosso C, Valderrabano V, Leithner A, Vavken P. Initial Achilles tendon repair strength--synthesized biomechanical data from 196 cadaver repairs. Int Orthop. 2012;36(9): Cash MP, Sherrill JM, Waitayawinyu T, et al. Evaluation of Fiberloop Sutures in Locking and Nonlocking Tendon Repair. Annals of Plastic Surgery. June 2012; 68(6): Haimovici L, Papafragkou S, Lee W et al. The Impact of Fiberwire, Fiberloop, and Locking Suture Configuration on Flexor Tendon Repairs. Annals of Plastic Surgery. October 2012; 69(4): Deramo DM, White KL, Parks BG, Hinton RY. Krackow Locking Stitch Versus Nonlocking Premanufactured Loop Stitch for Soft-Tissue Fixation: A Biomechanical Study. Arthroscopy: The Journal of Arthroscopic and Related Surgery. May 2008; 24(5): White KL, Camire LM, Parks BG, Corey WS, Hinton RY. Krackow Locking Stitch Versus Locking Premanufactured Loop Stitch for Soft Tissue Fixation: A Biomechanical Study. Arthroscopy: The Journal of Arthroscopic and Related Surgery. December 2010; 26(12): Leppilahti J, Puranen J, Orava S. Incidence of Achilles tendon rupture. Acta Orthop Scand. 1996;67(3): Gwynne-Jones DP, Sims M, Handcock D. Epidemiology and Outcomes of Acute Achilles Tendon Rupture with Operative or Nonoperative treatment using an identical Functional Bracing Protocol. Foot and Ankle International. April 2011; 32(4): Jallageas R, Bordes J, Daviet JC, Mabit C, Coste C. Evaluation of surgical treatment for ruptured Achilles tendon in 31 athletes. Orthopedics and Traumatology, Surgery and Research. September 2013; 99(5): Raikin SM, Garras DN, Krapchev PV. Achilles Tendon Injuries in a United States Population. Foot and Ankle International. April 2013; 34(4): Silfverskiöld KL, Andersson CH. Two new methods of tendon repair: an in vitro evaluation of tensile strength and gap formation. J Hand Surg Am. 1993;18(1): Saltzman CL, Tearse DS. Achilles tendon injuries. J Am Acad Orthop Surg. 1998;6(5): Labib SA, Rolf R, Dacus R, Hutton WC. The "Giftbox" repair of the Achilles tendon: a modification of the Krackow technique. Foot Ankle Int. 2009;30(5):410-4.