Flexor Digitorum Longus Tendoscopy: An Overview of Surgical Approaches and Application

  • Raymond Peter Lee
  • Tun Hing Lui


The flexor digitorum longus (FDL) muscle is originated from the mid-third posterior tibial shaft. It runs distally and forms a tendon toward the distal tibia [1]. The FDL tendon can be divided into three zones [2]. The FDL tendon travels to the tibialis posterior (TP) tendon and crosses it posteromedially at the posteromedial aspect of the lower leg forming the chiasma crurale. Both tendons have a sheath below the chiasma but not above it [3]. It runs along the base of the TP tendon at the posterior of the medial malleolus. It travels under the flexor retinaculum between the TP tendon and the tibial neurovascular bundle before it enters the sole. From the musculotendinous junction to 1 cm proximal to the navicular insertion of the TP tendon forms the zone 1 of the FDL tendon. The TP and zone 1 FDL tendons have separate fibrous tendon sheaths that are adjacent to each other, and the tendons are separated by a thin fibrous septum [4].


  1. 1.
    Netter FH, Dalley AF. Atlas of human anatomy. 2nd ed. New York: Elsevier; 1997.Google Scholar
  2. 2.
    Lui TH. Flexor digitorum longus endoscopy. J Foot Ankle Surg. 2012;51:690–2.CrossRefGoogle Scholar
  3. 3.
    Buck FM, Gheno R, Nico MAC, Trudell DJ, Resnick D. Chiasma crurale: intersection of the tibialis posterior and flexor digitorum longus tendons above the ankle. Magnetic resonance imaginganatomic correlation in cadavers. Skelet Radiol. 2010;39:565–73.CrossRefGoogle Scholar
  4. 4.
    Fernandes R, Aguiar R, Trudell D, Resnick D. Tendons in the plantar aspect of the foot: MR imaging and anatomic correlation in cadavers. Skelet Radiol. 2007;36:115–22.CrossRefGoogle Scholar
  5. 5.
    Lui TH, Chow HT. Role of toe flexor tendoscopy in management of an unusual cause of metatarsalgia. Knee Surg Sports Traumatol Arthrosc. 2006;14:654–8.CrossRefGoogle Scholar
  6. 6.
    Tiwari V, Ansari T, Mittal S, Sharma P, Nalwa A. Giant cell tumour of tendon sheath with simultaneous two tendon involvement of the foot treated with excision of the tumour and reconstruction of the flexor retinaculum using tibialis posterior tendon in a paediatric patient: a rare case report. Foot Ankle Surg. 2015;21:e60–3.CrossRefGoogle Scholar
  7. 7.
    Panchbhavi VK, Yang J, Vallurapalli S. Surgical anatomy for a new minimally invasive approach to harvest the flexor digitorum longus tendon: a cadaver study. Foot Ankle Surg. 2008;14:16–20.CrossRefGoogle Scholar
  8. 8.
    Schon LC, Reed MA. Disorders of the nerves. In: Coughlin MJ, Saltzman CL, Anderson RB, editors. Mann’s surgery of the foot and ankle. 9th ed. Philadelphia: W.B. Saunders/Elsevier; 2014. p. 669.Google Scholar
  9. 9.
    Lui TH, Chow FYH. “Intersection syndrome” of the foot: treated by endoscopic release of master knot of Henry. Knee Surg Sports Traumatol Arthrosc. 2011;19:850–2.CrossRefGoogle Scholar
  10. 10.
    Lui TH. Endoscopic release of master knot of Henry. Arthrosc Tech. 2015;23(4):e847–50.CrossRefGoogle Scholar
  11. 11.
    Lui TH. Endoscopic assisted posterior tibial tendon reconstruction for stage 2 posterior tibial tendon insufficiency. Knee Surg Sports Traumatol Arthrosc. 2007;15:1228–34.CrossRefGoogle Scholar
  12. 12.
    van Dijk CN, Kort N, Scholten PE. Tendoscopy of the posterior tibial tendon. Arthroscopy. 1997;13:692–8.CrossRefGoogle Scholar
  13. 13.
    Lui TH. Flexor hallucis longus tendoscopy: a technical note. Knee Surg Sports Traumatol Arthrosc. 2009;17:107–10.CrossRefGoogle Scholar
  14. 14.
    Lui TH. Endoscopic resection of the tarsal tunnel ganglion. Arthrosc Tech. 2016;5:e1173–7.CrossRefGoogle Scholar

Copyright information

© Springer Nature Singapore Pte Ltd. 2019

Authors and Affiliations

  • Raymond Peter Lee
    • 1
  • Tun Hing Lui
    • 3
    • 2
    • 4
    • 5
  1. 1.Department of Orthopaedics and TraumatologyPrince of Wales HospitalHong KongChina
  2. 2.Department of Orthopaedics and TraumatologyNorth District HospitalHong KongChina
  3. 3.Department of OrthopaedicsSouthern Medical UniversityGuangzhouChina
  4. 4.Institute of Biomedicine and Biotechnology, Shenzhen Institute of Advanced Technology—Chinese Academy of ScienceShenzhenChina
  5. 5.Department of Orthopaedics and TraumatologyChinese University of Hong KongHong KongChina

Personalised recommendations