The early series recommended reconstruction by side-to-side anastomosis of the tibialis posterior to FHL or FDL (Jahss 1975). Other authors recommended excision of the abnormal tendon and bridging of this gap, or of a rupture, by transferring the FDL into the navicular (Johnson 1989). Initial enthusiasm for this method reduced as it was realised that the arch was not generally recreated, the medial pain tended to recur and other lesions such as deltoid and spring ligament tears were not dealt with.
Gazdag and Cracchiolo (1997) reported 22 patients who had reconstruction of the tibialis posterior, mostly with FDL transfer, and most also had spring ligament reconstructions. 70% had good pain relief but all had residual deformity.
The tendon is usually harvested by extending the medial incision (for tibialis posterior exposure) or performing a short plantar medial incision centred on the knot of Henry. Panchbhavi (2008, 2009) described a plantar minimally-invasive technique for harvesting the tendon at its point of division into tendons for the individual toes. The FDL division lies midway between the back of the heel and the base of the second toe and about 3.7 cm medial to the lateral border of the foot (about 2/3 of the way from the lateral to the medial border. In a cadaver study, FDL could be harvested through a short incision at this site with no damage to the neurovascular structures, although in 11 feet a connection to FHL need to be divided. No clinical results of this technique have been published.
O'Sullivan et al (2005) described the tendon anastomoses at the knot of Henry in 16 cadaver feet. Eleven had fibres running from FHL to FDL, 2 had fibres from FDL to FHL and 3 had fibres running both ways. Thus 11/16 (69%) would retain active lesser toe flexion after simple division of FDL because of the anastomoses, while 5/16 (31%) would require suture of the FDL stump to FHL. The anatomy should be inspected in each patient and the FDL stump suture to FHL when necessary.
Several other authors have described in vitro models of flatfoot deformity and reconstructive procedures (Deland et al 1992, Thordarson et al 1995, Kitaoka et al 1997, 1998) but, while interesting, these have not translated into clinical results. It began to be realised that symptomatic improvement required measures to improve the biomechanics of the foot. FDL (or FHL) transfers are now generally performed in conjunction with realignment procedures such as posterior medial displacement calcaneal osteotomy or lateral column lengthening, and the results of combined procedures are discussed on those pages.
DiDomenico (2011) described a series of combined osteotomies specifically avoiding tendon transfer, with results equivalent to other series. Perhaps FDL transfer is not needed after all.