Biomechanical Analysis of Single Interference Screw vs Interference Screw With Cortical Button for Flexor Hallucis Longus Transfer

Background: Flexor hallucis longus tendon transfer (FHL) with a cortical button tension slide is an innovative addition that has not been measured against traditional methods. Methods: 12 pairs (n=24) of fresh-frozen cadaveric tibia-to-toe samples were used and randomized to receive one of the operative FHL techniques. Specimens underwent bone density analysis. Biomechanical loading was applied between 20 and 60 N at 1 Hz for 100 cycles. Post–cyclic load to failure occurred at 1.25 mm/s. Cyclic displacement, structural stiffness, and ultimate load were derived from load-displacement curves. Student t tests evaluated significant effects between both FHL techniques. Linear regression analysis assessed interactions between bone density and strength of FHL technique. Results: Average tendon diameter was 5.44±0.46 mm. Average bone density was 1.06±0.08 g/cm2. Addition of a cortical button to FHL transfer did not significantly affect cyclic displacement (0.78±0.52 mm vs 0.87±0.80 mm) or structural stiffness (162.11±43.34 N/mm vs 167.57±49.19 N/mm). Cortical button addition to FHL transfer resulted in significantly increased ultimate load (343.72±68.93 N) compared with interference screw alone (255.62±77.17 N) ( P = .0002). Linear regression analyses did not reveal any significant interactions between bone density and FHL tendon transfer technique. Conclusion: Enhanced strength can be achieved with FHL tendon transfer to calcaneus using an interference screw and cortical button tension slide technique as compared to an interference screw alone. Cortical buttons in the setting of FHL tendon transfer to the calcaneus offers an additional level of support. Clinical Relevance: Operative cases presenting with poor bone quality due to osteoporosis or osteopenia could benefit from cortical button fixation during FHL transfer. Clinical studies are needed to determine if the increased construct stability conferred from the additional use of a flip button results in fewer FHL transfer failures or better clinical outcomes. Level of Evidence: Level V, Controlled Laboratory Study.

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Adjustable-Loop Femoral Cortical Suspensory Fixation for Patellar Tendon Anterior Cruciate Ligament Reconstruction: A Time Zero Biomechanical Comparison With Interference Screw Fixation

The American Journal of Sports Medicine ◽

10.1177/0363546518771365 ◽

2018 ◽

Vol 46 (8) ◽

pp. 1857-1862 ◽

Cited By ~ 3

Author(s):

Dayne T. Mickelson ◽

Thomas Lefebvre ◽

Ken Gall ◽

Jonathan C. Riboh

Keyword(s):

Cruciate Ligament ◽

Bone Grafts ◽

Biomechanical Properties ◽

Interference Screw ◽

Bone Block ◽

Femoral Fixation ◽

Interference Screws ◽

Time Zero ◽

Cortical Button ◽

Cyclic Displacement

Background: Adjustable-loop cortical buttons for femoral fixation of bone-tendon-bone grafts have potential advantages over interference screw fixation; however, these devices have not been benchmarked biomechanically against interference screws. Purpose/Hypothesis: The purpose was to compare the time zero biomechanical properties of commercially available, adjustable-loop cortical button and metallic interference screws for femoral fixation of bone-tendon-bone grafts. It was hypothesized that no significant differences would be found in biomechanical properties between fixation techniques. Study Design: Controlled laboratory study. Methods: Adjustable-loop cortical buttons (n = 8) and metallic interference screws (n = 8) were used to fix matched pairs of human bone-tendon-bone allografts in porcine distal femurs. These constructs were preconditioned (10 N to 50 N at 1 Hz, 10 cycles), subjected to cyclic loading (50 N to 250 N at 1 Hz, 500 cycles), and then pulled to failure at 20 mm/min. Results: The loads to failure (mean ± SD, 700 ± 256 N vs 688 ± 215 N, P = .92) and linear stiffnesses (219 ± 48 N/mm vs 218 ± 49 N/mm, P = .97) for the adjustable-loop cortical button and metallic interference screws, respectively, were not significantly different. Cyclic displacement was higher in the adjustable-loop cortical button group (2.1 ± 0.6 mm vs 1.3 ± 0.4 mm, P = .01). The mechanism of failure was different between groups, with bone block slippage occurring most commonly in the interference screw group (n = 5) and fracture of the bone block through the suture hole occurring most commonly in the adjustable-loop cortical button group (n = 6). Conclusion: Adjustable-loop cortical buttons and interference screws have similar time zero failure loads, although cyclic displacement was higher with the adjustable-loop cortical buttons. The mean difference in displacement was less than 1 mm compared with the interference screw. Clinical Relevance: Adjustable-loop cortical buttons may be an acceptable alternative to an interference screw for femoral fixation of bone-tendon-bone grafts in anterior cruciate ligament reconstruction. The clinical relevance of the observed differences in cyclic displacement is unknown and should be evaluated in future studies.

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A Biomechanical Analysis of Interference Screw Versus Bone Tunnel Fixation of Flexor Hallucis Longus Tendon Transfers to the Calcaneus

The Journal of Foot & Ankle Surgery ◽

10.1053/j.jfas.2017.04.014 ◽

2017 ◽

Vol 56 (4) ◽

pp. 813-816 ◽

Cited By ~ 8

Author(s):

George T. Liu ◽

B. Christian Balldin ◽

Jacob R. Zide ◽

Christopher T. Chen

Keyword(s):

Interference Screw ◽

Bone Tunnel ◽

Biomechanical Analysis ◽

Flexor Hallucis Longus ◽

Tendon Transfers ◽

Longus Tendon

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Interference Screw Fixation for Flexor Hallucis Longus Tendon Transfer for Chronic Achilles Tendonopathy

The Journal of Foot & Ankle Surgery ◽

10.1053/j.jfas.2007.09.001 ◽

2008 ◽

Vol 47 (1) ◽

pp. 69-72 ◽

Cited By ~ 29

Author(s):

William T. DeCarbo ◽

Christopher F. Hyer

Keyword(s):

Tendon Transfer ◽

Screw Fixation ◽

Interference Screw ◽

Flexor Hallucis Longus ◽

Longus Tendon ◽

Interference Screw Fixation

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Chronic insertional achilles tendon ruptures treated by suture anchor repair and augmentation with flexor hallucis longus tendon transfer

International Journal of Research in Orthopaedics ◽

10.18203/issn.2455-4510.intjresorthop20180442 ◽

2018 ◽

Vol 4 (2) ◽

pp. 227 ◽

Cited By ~ 1

Author(s):

Athar Ahemad M. A. ◽

Naser Mohd Abdul ◽

Mushir Ali Syed

Keyword(s):

Achilles Tendon ◽

Tendon Transfer ◽

Suture Anchor ◽

Interference Screw ◽

Flexor Hallucis Longus ◽

Reliable Technique ◽

Good Outcome ◽

Interference Screw Fixation ◽

Tendon Ruptures

Background: Different surgical procedures have been used for treatment of chronic ruptures of the Achilles tendon with varying results. This study assesses the functional outcomes and complications of chronic insertional tears of Achilles tendon.Methods: 10 patients with chronic ruptures of the Achilles tendon were followed for a mean period of 10.3 months. Only ruptures at or near (within 1 cm) insertion were included. They were treated by direct repair of tendon to calcaneum by suture anchor. Flexor hallucis longus (FHL) tendon transfer fixed to calcaneal tunnel with an interference screw was used to augment the repair.Results: Outcome was assessed by AOFAS Ankle-Hindfoot (AHS) score. The mean preoperative score of 41.2 improved to 85.4 at final follow-up out of a total 100 points. We achieved excellent results in 80% and good outcome in 20% cases. No re-ruptures were noted. Conclusions: In insertional chronic ruptures of Achilles tendon, FHL transfer to calcaneum with interference screw fixation and repair of Achilles tendon with suture anchor is a reliable technique with good outcome and is recommended.

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Interference screw fixation of flexor hallucis longus tendon transfer to calcaneus

Foot and Ankle Surgery ◽

10.1016/s1268-7731(03)00044-4 ◽

2003 ◽

Vol 9 (3) ◽

pp. 179-181 ◽

Cited By ~ 3

Author(s):

Raghu Raman ◽

Nicholas J Harris

Keyword(s):

Tendon Transfer ◽

Screw Fixation ◽

Interference Screw ◽

Flexor Hallucis Longus ◽

Longus Tendon ◽

Interference Screw Fixation

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Treatment of chronic injury associated with Achilles insertional tendinopathy using posterior ankle arthroscopy

Scientific Journal of the Foot & Ankle ◽

10.30795/scijfootankle.2018.v12.847 ◽

2018 ◽

Vol 12 (4) ◽

pp. 347-51

Author(s):

Cesar Teixeira Tobias ◽

Rodrigo Gonçalves Pagnano ◽

Thiago Coelho Paim Lima ◽

Mauro Cesar Mattos e Dinato

Keyword(s):

Surgical Treatment ◽

Tendon Transfer ◽

Interference Screw ◽

Flexor Hallucis Longus ◽

Chronic Injury ◽

Level Of Evidence ◽

Calcaneal Tendon ◽

Insertional Tendinopathy ◽

Posterior Ankle Arthroscopy ◽

Chronic Injuries

Ruptures of the calcaneal tendon, when neglected, cause marked disturbance to gait and support at the tip of the foot. Most causes of pain in this region are related to overload injuries. Previous studies have shown that surgical treatment is the best option for chronic injuries. The purpose of this report is to describe a new endoscopic surgical technique used for treatment of chronic injury of the calcaneal tendon by reconstruction with flexor hallucis longus tendon transfer and fixation with an interference screw at the calcaneus in an elderly diabetic patient with signs of Achilles insertional tendinopathy. Level of Evidence V; Therapeutic studies; Expert opinion.

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Comparative Study of Flexor Hallicus Longus Tendon Length through Single Incision or Accessory Plantar Medial Incision: A Cadaver Study

Foot & Ankle Orthopaedics ◽

10.1177/2473011420s00181 ◽

2020 ◽

Vol 5 (4) ◽

pp. 2473011420S0018

Author(s):

Caitlin Curtis Crocker ◽

Eildar Abyar ◽

Sean Young ◽

Fatemah Razaghi ◽

Gerald McGwin ◽

...

Keyword(s):

Single Incision ◽

Plantar Flexion ◽

Cadaver Study ◽

Tendon Graft ◽

Interference Screw ◽

Flexor Hallucis Longus ◽

Tunnel Length ◽

Exact Test ◽

Fresh Frozen ◽

The Mean

Category: Ankle; Hindfoot Introduction/Purpose: Flexor Hallucis Longus (FHL) tendon transfer to the calcaneus is a common adjuvant procedure in the treatment of Achilles pathology. The FHL tendon can be harvested using a posterior incision where the tendon is dissected along its course into the fibroosseous tunnel. Alternatively, the FHL may be harvested through a separate plantar medial incision as it crosses the flexor digitorium longus at the Knot of Henry. This study aims to quantify FHL tendon lengths achieved through the two common approaches utilizing pair matched cadavers. Methods: Seven pair matched fresh-frozen cadaver legs without signs of musculoskeletal abnormalities were used for this assessment. One leg in each pairing underwent a single incision harvest while the contralateral leg underwent an accessory medial plantar harvest. After dissecting the tendon, a calcaneus tunnel was prepared from dorsal to plantar in both calcanei in standard fashion. Two measurements were obtained. The first measurement was taken from the distal aspect of the muscle belly to the distal end of the tendon. The tendon was then pulled through the calcaneus, and the foot was held in tension at 20 degrees of plantar flexion. The second measurement was taken from site where tendon entered the calcaneous to the distal end of the tendon graft. The measurements were analyzed using Wilcoxon Signed Ranks Test and Fischer Exact Test. Results: Using a posterior incision, the mean tendon measurement from calcaneous tunnel to the distal end of the tendon was 4.0 cm. Using an accessory plantar medial incision, the mean tendon measurement from the calcaneous tunnel to the distal end of the tendon was 7.2 cm. The average tunnel length obtained using an accessory medial incision was significantly greater than the length obtained using the single incision approach (p= 0.0003, p=0.0022, and p=0.0016). The accessory plantar medial incision obtained an FHL tendon tunnel length that was an average of 2.9 cm greater than the posterior incision. Conclusion: The single incision approach provided sufficient length to safely anchor the FHL into the calcaneus which suggests that the accessory plantar medial approach is not necessary for routine FHL transfers to the calcaneus with interference screw fixation. However, if additional length is needed for other applications such as posterior tibialis tendon dysfunction or peritoneal tendon tears, the accessory incision does provide an average of 2.9 cm of additional length.

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