Foot & Ankle International - July 2018 - 863

863

Marsland et al
FHL tendons but with smaller pilot holes of 3.9 and 4.5 mm
diameters. In that study, pullout forces were approximately
170 and 75 N for 7-mm and 5-mm diameter screws, respectively.24 Similarly, in 2 separate studies, FHL transfer to the
calcaneus had loads to failure of 172 N and 170 N with 5.5mm and 7-mm diameter screws, respectively.3,9 The greater
pullout strengths we report are likely to be related to the
large diameter of the TP tendon. Furthermore, we also used
a whipstitch, proven to increase pullout strength.23
For smaller diameter tendon transfers in the foot that are
less than 5 mm (such as FDL or split anterior tibialis tendons), the drill hole is often oversized to accommodate a
larger screw.12 The advantage of using a whole tendon
transfer rather than split tendon is that oversizing of the
pilot hole is not necessary. We drilled the tunnel to match
the TP tendon, which has been shown to increase pullout
strength.35 In all but 2 specimens, the bone tunnel was 6.5
mm or less. In the 2 specimens that required 7-mm holes,
the pullout strengths were 513 and 485 N. We found no difference in loads to failure comparing 5.5- to 6.0-mm pilot
tunnels (504 N) vs 6.5- to 7-mm tunnels (493 N). For consistency, we chose to use the same diameter screw for all
specimens. Although screw diameter seems to be less
important compared with the tendon to tunnel diameter
ratio, it is possible that use of a larger diameter screw in our
own study may have affected the pullout strength.8,21,27 One
must also consider the risk of using a large-diameter screw
in a relatively small bone in the foot, which could lead to
damage to the tendon graft or fracture.

Conclusion

Limitations

References

Several limitations exist inherent to an in vitro cadaveric
study. We were not able to simulate the effects of tendon
remodeling or tendon-bone interface healing, which usually
occur within the first 6 weeks.25 Our findings therefore are
only relevant to the early postoperative period before this
process has occurred. We did not measure bone mineral
density prior to testing. The mean age of the specimens used
was relatively young, which represents the typical population receiving tendon transfers for foot drop. Other studies
have used elderly osteoporotic specimens.9,24 Although we
conducted a priori power analysis based on load to failure,
post hoc analysis using mean tendon displacement during
cyclic testing showed that the power was 0.14 and that 194
specimens in each group would be required to show a significant difference between techniques. The current study
only compared 2 techniques for anterior transfer of the TP.
We chose transfer to the lateral side of the foot as would be
required in a foot drop, which included peroneal tendon
weakness. Our findings cannot necessarily be applied to
other sites of tendon transfer such as the cuneiforms or techniques using smaller diameter tendons, including split TP
tendon transfer.

The current study supports early postoperative active dorsiflexion and early protected partial weightbearing. For anterior transfer of the TP tendon, ISF and PW techniques were
comparable with relatively small displacements during cyclic
loading and similar loads to failure. The variability of displacement, however, was greater in the PW group, suggesting it may offer less reliable fixation. The potential benefits
of early rehabilitation include improved patient satisfaction,
reduced stiffness, and reduced risk of VTE and need for
chemical prophylaxis. We recommend future clinical trials to
determine the functional outcomes of early rehabilitation vs
cast immobilization after TP tendon transfer.
Acknowledgments
We thank Arthrex Ltd for contributing implant materials to the
study and the Fortius Clinic for funding for the ankle specimens.
The Instron machine was donated by Arthritis Research UK.

Declaration of Conflicting Interests
The author(s) declared the following potential conflicts of interest
with respect to the research, authorship, and/or publication of this
article: The authors report other from Arthrex, other from Fortius
Clinic, other from Arthritis Research UK during the conduct of the
study. ICMJE forms for all authors are available online.

Funding
The author(s) received no financial support for the research,
authorship, and/or publication of this article.

1. Aronow MS. Foot drop correction: by active dorsiflexion or
tenodesis effect? Commentary on an article by T. Dreher, MD,
et al.: "Tibialis posterior tendon transfer corrects the foot drop
component of cavovarus foot deformity in Charcot-MarieTooth disease." J Bone Joint Surg Am. 2014;19;96(6):e50.
2. Arthrex Bio-tenodesis Screw System. https://www.arthrex.com/
foot-ankle/biotenodesis-screw-system. Accessed November 28,
2017.
3. Cohn JM, Sabonghy EP, Godlewski CA, et al. Tendon fixation in flexor hallucis longus transfer: a biomechanical study
comparing a traditional technique versus biobasorbable interference screw fixation. Tech Foot Ankle Surg. 2005;4(4):
214-221.
4. Coleridge SD, Amis AA. A comparison of five tibial-fixation systems in hamstring-graft anterior cruciate ligament
reconstruction. Knee Surg Sports Traumatol Arthrosc.
2004;12:391-397.
5. Davies MB, Saxby TS. Case report: nonabsorbable interference screw fixation for tendon transfers in the foot and ankle.
Foot Ankle Int. 2006;27(12):1154-1155.
6. Delp SL, Anderson FC, Arnold AS, et al. OpenSim: opensource software to create and analyze dynamic simulations
of movement. IEEE Trans Biomed Eng. 2007;54(11):19401950.


https://www.arthrex.com/foot-ankle/biotenodesis-screw-system https://www.arthrex.com/foot-ankle/biotenodesis-screw-system

Table of Contents for the Digital Edition of Foot & Ankle International - July 2018

Contents
Foot & Ankle International - July 2018 - Intro
Foot & Ankle International - July 2018 - Cover1
Foot & Ankle International - July 2018 - Cover2
Foot & Ankle International - July 2018 - i
Foot & Ankle International - July 2018 - ii
Foot & Ankle International - July 2018 - Contents
Foot & Ankle International - July 2018 - iv
Foot & Ankle International - July 2018 - v
Foot & Ankle International - July 2018 - vi
Foot & Ankle International - July 2018 - vii
Foot & Ankle International - July 2018 - viii
Foot & Ankle International - July 2018 - 1A
Foot & Ankle International - July 2018 - 1B
Foot & Ankle International - July 2018 - ix
Foot & Ankle International - July 2018 - x
Foot & Ankle International - July 2018 - xi
Foot & Ankle International - July 2018 - xii
Foot & Ankle International - July 2018 - 2A
Foot & Ankle International - July 2018 - 2B
Foot & Ankle International - July 2018 - xiii
Foot & Ankle International - July 2018 - xiv
Foot & Ankle International - July 2018 - xv
Foot & Ankle International - July 2018 - xvi
Foot & Ankle International - July 2018 - xvii
Foot & Ankle International - July 2018 - xviii
Foot & Ankle International - July 2018 - xix
Foot & Ankle International - July 2018 - xx
Foot & Ankle International - July 2018 - xxi
Foot & Ankle International - July 2018 - xxii
Foot & Ankle International - July 2018 - xxiii
Foot & Ankle International - July 2018 - xxiv
Foot & Ankle International - July 2018 - xxv
Foot & Ankle International - July 2018 - xxvi
Foot & Ankle International - July 2018 - 3A
Foot & Ankle International - July 2018 - 3B
Foot & Ankle International - July 2018 - 763
Foot & Ankle International - July 2018 - 764
Foot & Ankle International - July 2018 - 765
Foot & Ankle International - July 2018 - 766
Foot & Ankle International - July 2018 - 767
Foot & Ankle International - July 2018 - 768
Foot & Ankle International - July 2018 - 769
Foot & Ankle International - July 2018 - 770
Foot & Ankle International - July 2018 - 771
Foot & Ankle International - July 2018 - 772
Foot & Ankle International - July 2018 - 773
Foot & Ankle International - July 2018 - 774
Foot & Ankle International - July 2018 - 775
Foot & Ankle International - July 2018 - 776
Foot & Ankle International - July 2018 - 777
Foot & Ankle International - July 2018 - 778
Foot & Ankle International - July 2018 - 779
Foot & Ankle International - July 2018 - 780
Foot & Ankle International - July 2018 - 781
Foot & Ankle International - July 2018 - 782
Foot & Ankle International - July 2018 - 783
Foot & Ankle International - July 2018 - 784
Foot & Ankle International - July 2018 - 785
Foot & Ankle International - July 2018 - 786
Foot & Ankle International - July 2018 - 787
Foot & Ankle International - July 2018 - 788
Foot & Ankle International - July 2018 - 789
Foot & Ankle International - July 2018 - 790
Foot & Ankle International - July 2018 - 791
Foot & Ankle International - July 2018 - 792
Foot & Ankle International - July 2018 - 793
Foot & Ankle International - July 2018 - 794
Foot & Ankle International - July 2018 - 795
Foot & Ankle International - July 2018 - 796
Foot & Ankle International - July 2018 - 797
Foot & Ankle International - July 2018 - 798
Foot & Ankle International - July 2018 - 799
Foot & Ankle International - July 2018 - 800
Foot & Ankle International - July 2018 - 801
Foot & Ankle International - July 2018 - 802
Foot & Ankle International - July 2018 - 803
Foot & Ankle International - July 2018 - 804
Foot & Ankle International - July 2018 - 805
Foot & Ankle International - July 2018 - 806
Foot & Ankle International - July 2018 - 807
Foot & Ankle International - July 2018 - 808
Foot & Ankle International - July 2018 - 809
Foot & Ankle International - July 2018 - 810
Foot & Ankle International - July 2018 - 811
Foot & Ankle International - July 2018 - 812
Foot & Ankle International - July 2018 - 813
Foot & Ankle International - July 2018 - 814
Foot & Ankle International - July 2018 - 815
Foot & Ankle International - July 2018 - 816
Foot & Ankle International - July 2018 - 817
Foot & Ankle International - July 2018 - 818
Foot & Ankle International - July 2018 - 819
Foot & Ankle International - July 2018 - 820
Foot & Ankle International - July 2018 - 821
Foot & Ankle International - July 2018 - 822
Foot & Ankle International - July 2018 - 823
Foot & Ankle International - July 2018 - 824
Foot & Ankle International - July 2018 - 825
Foot & Ankle International - July 2018 - 826
Foot & Ankle International - July 2018 - 827
Foot & Ankle International - July 2018 - 828
Foot & Ankle International - July 2018 - 829
Foot & Ankle International - July 2018 - 830
Foot & Ankle International - July 2018 - 831
Foot & Ankle International - July 2018 - 832
Foot & Ankle International - July 2018 - 833
Foot & Ankle International - July 2018 - 834
Foot & Ankle International - July 2018 - 835
Foot & Ankle International - July 2018 - 836
Foot & Ankle International - July 2018 - 837
Foot & Ankle International - July 2018 - 838
Foot & Ankle International - July 2018 - 839
Foot & Ankle International - July 2018 - 840
Foot & Ankle International - July 2018 - 841
Foot & Ankle International - July 2018 - 842
Foot & Ankle International - July 2018 - 843
Foot & Ankle International - July 2018 - 844
Foot & Ankle International - July 2018 - 845
Foot & Ankle International - July 2018 - 846
Foot & Ankle International - July 2018 - 847
Foot & Ankle International - July 2018 - 848
Foot & Ankle International - July 2018 - 849
Foot & Ankle International - July 2018 - 850
Foot & Ankle International - July 2018 - 851
Foot & Ankle International - July 2018 - 852
Foot & Ankle International - July 2018 - 853
Foot & Ankle International - July 2018 - 854
Foot & Ankle International - July 2018 - 855
Foot & Ankle International - July 2018 - 856
Foot & Ankle International - July 2018 - 857
Foot & Ankle International - July 2018 - 858
Foot & Ankle International - July 2018 - 859
Foot & Ankle International - July 2018 - 860
Foot & Ankle International - July 2018 - 861
Foot & Ankle International - July 2018 - 862
Foot & Ankle International - July 2018 - 863
Foot & Ankle International - July 2018 - 864
Foot & Ankle International - July 2018 - 865
Foot & Ankle International - July 2018 - 866
Foot & Ankle International - July 2018 - 867
Foot & Ankle International - July 2018 - 868
Foot & Ankle International - July 2018 - 869
Foot & Ankle International - July 2018 - 870
Foot & Ankle International - July 2018 - 871
Foot & Ankle International - July 2018 - 872
Foot & Ankle International - July 2018 - 873
Foot & Ankle International - July 2018 - 874
Foot & Ankle International - July 2018 - 875
Foot & Ankle International - July 2018 - 876
Foot & Ankle International - July 2018 - 877
Foot & Ankle International - July 2018 - 878
Foot & Ankle International - July 2018 - 879
Foot & Ankle International - July 2018 - 880
Foot & Ankle International - July 2018 - 881
Foot & Ankle International - July 2018 - 882
Foot & Ankle International - July 2018 - 883
Foot & Ankle International - July 2018 - 884
Foot & Ankle International - July 2018 - Cover3
Foot & Ankle International - July 2018 - Cover4
https://www.nxtbook.com/nxtbooks/sage/hospitalpharmacy_december2020
https://www.nxtbook.com/nxtbooks/sage/psychologicalscience_demo
https://www.nxtbook.com/nxtbooks/sage/hospitalpharmacy_october2020
https://www.nxtbook.com/nxtbooks/sage/fai_202009
https://www.nxtbook.com/nxtbooks/sage/hospitalpharmacy_august2020
https://www.nxtbook.com/nxtbooks/sage/hospitalpharmacy_june2020
https://www.nxtbook.com/nxtbooks/sage/hospitalpharmacy_april2020
https://www.nxtbook.com/nxtbooks/sage/hospitalpharmacy_february2020
https://www.nxtbook.com/nxtbooks/sage/hospitalpharmacy_december2019
https://www.nxtbook.com/nxtbooks/sage/hospitalpharmacy_october2019
https://www.nxtbook.com/nxtbooks/sage/fai_201909
https://www.nxtbook.com/nxtbooks/sage/hospitalpharmacy_july2019
https://www.nxtbook.com/nxtbooks/sage/hospitalpharmacy_june2019
https://www.nxtbook.com/nxtbooks/sage/canadianpharmacistsjournal_05062019
https://www.nxtbook.com/nxtbooks/sage/hospitalpharmacy_april2019
https://www.nxtbook.com/nxtbooks/sage/sri_supplement_201903
https://www.nxtbook.com/nxtbooks/sage/hospitalpharmacy_february2019
https://www.nxtbook.com/nxtbooks/sage/hospitalpharmacy_december2018
https://www.nxtbook.com/nxtbooks/sage/tec_20180810
https://www.nxtbook.com/nxtbooks/sage/hospitalpharmacy_october2018
https://www.nxtbook.com/nxtbooks/sage/hospitalpharmacy_julyaugust2018
https://www.nxtbook.com/nxtbooks/sage/fai_201807
https://www.nxtbook.com/nxtbooks/sage/hospitalpharmacy_june2018
https://www.nxtbook.com/nxtbooks/sage/hospitalpharmacy_april2018
https://www.nxtbook.com/nxtbooks/sage/sri_supplement_201803
https://www.nxtbook.com/nxtbooks/sage/slas_discovery_201712
https://www.nxtbook.com/nxtbooks/sage/hospitalpharmacy_february2018
https://www.nxtbook.com/nxtbooks/sage/hospitalpharmacy_december2017
https://www.nxtbook.com/nxtbooks/sage/hospitalpharmacy_november2017
https://www.nxtbook.com/nxtbooks/sage/hospitalpharmacy_october2017
https://www.nxtbook.com/nxtbooks/sage/hospitalpharmacy_september2017
https://www.nxtbook.com/nxtbooks/sage/hospitalpharmacy_julyaugust2017
https://www.nxtbook.com/nxtbooks/sage/fai_supplement_201709
https://www.nxtbook.com/nxtbooks/sage/hospitalpharmacy_june2017
https://www.nxtbook.com/nxtbooks/sage/hospitalpharmacy_may2017
https://www.nxtbook.com/nxtbooks/sage/fai_201706
https://www.nxtbook.com/nxtbooks/sage/fai_201607
https://www.nxtbookmedia.com