Clinical significance of variations in the interconnections between flexor digitorum longus and flexor hallucis longus in the region of the knot of Henry

Abstract

Tendon transfer of the flexor digitorum longus tendon (FDLT) or the flexor hallucis longus tendon (FHLT) into the tibialis posterior tendon is carried out in patients with tibialis posterior dysfunction. FDLT and FHLT are connected in the region of the knot of Henry. The present study has investigated the anatomical variations of this tendinous interconnection. The results could be used to determine which of the two tendons should be transected proximal to the region of the knot of Henry in the surgical treatment of tibialis posterior dysfunction. In over two-thirds of cadaver specimens investigated, tension applied solely to FHLT resulted in flexion of all digits and the hallux. On the basis of these results, we propose that identification of the tendon to be transected should be decided at the time of surgery depending on the anatomical pattern. Based on the evidence provided by 16 cadaveric dissections, transection of FDLT proximal to the region of the knot of Henry for the repair of tibialis posterior dysfunction would result in retention of function of the hallux and lesser digits in the majority of cases.

The Tendinous Slip of the Flexor Digitorum Longus for the Great Toe: An Anatomic Variation

“…The interconnection between the FHL and the FDL tendons have been usually classified into four types [1][2][3][4]16]; Type I, tendinous slip from the FHL to FDL tendon in 41.7~97%; Type II, tendinous slip from the FHL to FDL and an additional slip from the FDL to FHL (crossed connection) in 1~41.7%; Type III, tendinous slip from the FDL to FHL in 0~30%; and Type IV, no connection between the FHL and FDL in 0~16.7%. The case of the present study corresponded to type II.…”

“…There have been several reports regarding various connections between the flexor digitorum longus (FDL) and the flexor hallucis longus (FHL) tendons in the foot [1][2][3][4].…”

Anatomical Variations of the Flexor Hallucis Longus and Flexor Digitorum Longus in the Chiasma Plantare

“…The tendinous connections were classified using a modified classification system ( Figure 2). 23 Type I described a proximal to distal connection of the FHL to the FDL, type II a proximal to distal connection of the FDL to the FHL, type III a crossed connection, and type IV no connection between the tendons. A subdivision was introduced categorizing the connection to the lesser toes: (a) corresponding to an insertion in the second toe, (b) to the second and third, (c) to the second to fourth and (d) to all lesser toes.…”

Disorders of the Flexor Hallucis Longus and Os Trigonum

“…The tendon then runs underneath the intersesamoid ligament and inserts at the plantar surface of the distal phalanx of the great toe. 45,46 The blood supply to the FHL arises from the posterior tibial and medial plantar arteries, whereas the tibial nerve provides innervation to the muscle. 37 The primary function of the FHL is as an active plantarflexor at the first metatarsophalangeal (MTP) and hallux interphalangeal joints and as the primary restraint to passive dorsiflexion at the first MTP joint.…”