Flexor Hallucis Longus (FHL) Tenosynovitis Secondary to Posterior Ankle Hardware
In short
Identify and rehabilitate flexor hallucis longus tenosynovitis and hallux saltans caused by posterior malleolar hardware friction post-ORIF.
In this guide (4 sections)
Open reduction and internal fixation of complex trimalleolar fractures frequently requires direct surgical access to the posterior malleolus through a posterolateral or posteromedial approach. To anatomically reduce the Volkmann fragment and secure it with a posterior buttress plate or anteroposterior lag screws, the flexor hallucis longus (FHL) muscle belly and tendon must be mobilized and retracted. In the months following surgery, patients can develop chronic, debilitating flexor hallucis longus tenosynovitis or pseudo-hallux saltans (trigger big toe). This condition arises when prominent posterior plate edges, protruding screw tips, or dense fibrotic surgical adhesions mechanically impinge upon the FHL tendon within its fibro-osseous tunnel behind the talus and sustentaculum tali. Early recognition and targeted soft tissue rehabilitation are essential to restore smooth tendon excursion and prevent permanent tendon degeneration.
Managing Indian Floor Sitting, Barefoot Walking, and Stair Descent
In Indian daily life, flexor hallucis longus dysfunction interferes with numerous common functional postures. The FHL tendon is responsible for forceful plantarflexion of the great toe, playing an essential role in stabilizing the medial longitudinal arch during push-off and floor activities. In Indian homes, sitting cross-legged (sukhasana) or kneeling for domestic prayers requires the great toe to bend into extreme passive positions; a tethered FHL tendon causes sharp, pulling pain deep behind the medial and posterior ankle. Walking barefoot across smooth marble floors or climbing down steep residential staircases demands controlled eccentric dorsiflexion of the big toe as the trailing foot rolls forward. When the tendon is inflamed and restricted by surgical hardware, this rollover phase triggers sharp retromalleolar pain, causing patients to limp on the outside of the foot.
Fibro-Osseous Tunnel Anatomy, Mechanical Hardware Friction, and Hallux Saltans
The anatomical course of the flexor hallucis longus tendon renders it uniquely vulnerable to post-operative mechanical irritation. The FHL originates from the posterior fibular shaft and interosseous membrane, descending obliquely across the posterior distal tibia to enter a narrow fibro-osseous tunnel bounded by the medial and lateral talar tubercles. It then wraps beneath the sustentaculum tali of the calcaneus before coursing into the sole of the foot to insert onto the distal phalanx of the great toe. When a posterior malleolar plate is contoured with slight prominence, or when lag screws project even one to two millimeters beyond the posterior tibial cortex, the FHL tendon rubs directly against the metallic ridges during every step. Repetitive friction induces chronic tenosynovitis, nodular collagen thickening, and stenosing tenovaginitis, producing painful mechanical clicking or catching (hallux saltans) as the nodule struggles through the fibrous tunnel.
Clinical Assessment: FHL Stretch Test, Soft Tissue Mobilization, and Gliding Drills
Physiotherapists confirm FHL tenosynovitis using specific clinical diagnostic maneuvers. The pathognomonic test is the 'FHL Stretch Test': the clinician passively extends the patient's great toe while holding the ankle in full dorsiflexion, tensioning the tendon fully; localized sharp pain and mechanical resistance behind the medial malleolus confirm tenosynovitis. Palpating the tendon posteromedially while actively flexing and extending the big toe frequently reveals palpable crepitus or snapping. Rehabilitation focuses on restoring differential soft tissue gliding. The clinician applies deep transverse friction massage along the posterolateral and posteromedial scar lines while the patient actively wiggles the great toe. Progressive active-assisted tendon gliding drills, stretching in seated positions with the knee flexed to slacken the gastrocnemius, and temporary footwear modifications with a stiff forefoot rocker sole minimize terminal toe extension strain.
Seated Active-Assisted Flexor Hallucis Longus Gliding Drill
Objective: Promote smooth longitudinal excursion of the FHL tendon through its posterior fibro-osseous tunnel
- 1Sit comfortably in a chair with your recovering foot resting on your opposite knee, giving you easy manual access to your foot.
- 2With one hand, grasp your big toe and gently pull it upward toward your shin into maximum comfortable extension.
- 3While holding the toe extended, use your other hand to gently bend your entire ankle downward into mild plantarflexion.
- 4Now reverse the motion: slowly pull your ankle upward into gentle dorsiflexion while allowing your big toe to curl naturally downward.
- 5Alternate between these two positions in a smooth, rhythmic seesaw motion for two minutes, feeling the deep tendon glide behind your ankle bone.
| Clinical Evaluation Feature | Physical Presentation & Test | Anatomical Location of Irritation | Targeted Therapeutic Intervention |
|---|---|---|---|
| FHL Stretch Test (Positive) | Pain behind ankle during combined ankle/toe dorsiflexion | Posterior talar fibro-osseous groove behind joint line | Active tendon gliding drills; soft tissue release |
| Hallux Saltans (Trigger Big Toe) | Mechanical catching, clicking, or locking of great toe | Nodular thickening encountering posterior buttress plate | Phonophoresis with anti-inflammatory gel; ultrasound |
| Terminal Push-Off Pain | Sharp retromalleolar pain during late stance gait | Sustentaculum tali groove; screw tip prominence | Rocker-sole footwear modification; orthopaedic review |
If a patient experiencing severe posterior pain and FHL clicking suddenly develops complete inability to actively flex the interphalangeal joint of the great toe, acute mechanical rupture of the flexor hallucis longus tendon has occurred. Complete tendon rupture requires immediate non-weight-bearing immobilization and urgent orthopaedic evaluation for surgical exploration and tendon repair.
Frequently Asked Questions
Why does my big toe click and hurt behind my ankle after my trimalleolar surgery?
The tendon that bends your big toe (flexor hallucis longus) passes directly behind your ankle, right next to where your surgeon placed the plate and screws to fix your posterior fracture. If the tendon rubs against the metal hardware or healing scar tissue, it becomes swollen and clicks like a trigger finger. Targeted tendon-gliding exercises and physiotherapy will help it slide smoothly again.
Do I need a doctor referral to rehabilitate an ankle fracture on BookPhysio.in?
BookPhysio.in does not require a doctor referral. Under the National Commission for Allied and Healthcare Professions (NCAHP) Act 2021, patients across India enjoy direct access to autonomous registered physiotherapists. Through BookPhysio.in, you connect directly with verified clinicians and pay per session with transparent fees, completely free from advance package commitments, commission markups, or platform subscription charges.
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