Medically reviewed by Dr. Tom Biernacki, DPM
Board-certified podiatric surgeon | Balance Foot & Ankle, Howell & Bloomfield Township, MI
Last reviewed: May 2026
Most patients underestimate how much the post-operative phase determines FDL Transfer for Flat Foot: What the Involves and outcomes — not the surgery itself. Our podiatric surgeons identify the single recovery variable that separates patients who return to full activity on schedule from those who experience setbacks. Call (810) 206-1402 — expert podiatric care across Michigan.
Flexor digitorum longus (FDL) tendon transfer is the dynamic component of adult flatfoot reconstruction, supplementing the failed posterior tibial tendon (PTT). Because the PTT cannot be repaired when chronically degenerated, the FDL — which lies immediately adjacent in the same tendon sheath — is transferred to the navicular to restore medial arch dynamic support. It is performed as part of a comprehensive flatfoot reconstruction, not in isolation.
FDL Transfer as Part of Flatfoot Reconstruction
| Procedure Component | Purpose | Indication |
|---|---|---|
| FDL tendon transfer to navicular | Replaces failed PTT dynamic function | Stage II PTTD with PTT degeneration |
| Medializing calcaneal osteotomy | Realigns heel valgus; reduces stress on transferred tendon | Heel valgus over 10 degrees |
| Spring ligament repair/reconstruction | Restores static medial arch support | Spring ligament attenuation or rupture |
| Cotton osteotomy (medial cuneiform plantarflexion) | Corrects medial column elevation; restores arch height | Forefoot supinatus or medial column insufficiency |
| Lateral column lengthening | Corrects forefoot abduction and talonavicular uncoverage | Stage IIB with significant abduction |
Recovery Timeline After FDL Transfer + Calcaneal Osteotomy
| Phase | Duration | Weight-Bearing Status | Key Activities |
|---|---|---|---|
| Cast immobilization | 0-6 weeks | NWB; no inversion or eversion | Elevation; calf and hip exercises; wound checks |
| Boot + protected WB | Weeks 6-10 | Progressive FWB in boot | Pool walking; stationary cycling; gentle ROM |
| Boot to shoe transition | Weeks 10-14 | FWB in supportive shoe + custom orthotic | PT: strengthening, balance, gait retraining |
| Strengthening / functional | Months 4-9 | Full; low-impact exercise | Calf raises; single-leg balance; walking program |
| Return to full activity | 9-12 months | Full | Running, cutting sports after strength milestones met |
FDL transfer outcomes are excellent when patient selection and bony alignment correction are appropriate — 85-90% report good to excellent results at 5-year follow-up. Loss of lesser toe flexion from FDL harvest is minimal in most patients. At Balance Foot & Ankle in Howell and Bloomfield Township, we perform comprehensive flatfoot reconstruction with individualized protocols. Call (810) 206-1402.
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Doctor Answer
What is a flexor digitorum longus tendon transfer?
Flexor digitorum longus (FDL) tendon transfer is a key component of stage 2 flatfoot reconstruction, supplementing the failed posterior tibial tendon with the adjacent FDL tendon. The FDL is rerouted through the navicular bone to restore medial arch support. It is combined with calcaneal osteotomy for best results. Recovery involves non-weight-bearing for 8-12 weeks, then gradual loading. The FDL transfer restores active arch function that orthotics alone cannot provide.
Dr. Tom Biernacki, DPM is a board-certified foot & ankle surgeon (ABFAS & ABPM) at Balance Foot & Ankle Specialists in Southeast Michigan. With over a decade of clinical experience, he specializes in heel pain, bunions, diabetic foot care, sports injuries, and minimally invasive surgery. Dr. Biernacki is a member of the APMA and ACFAS, and his patient education content on MichiganFootDoctors.com and YouTube has made him one of the most-followed foot & ankle educators on YouTube.