Consequences
Why your foot becomes deformed with FHL
The foot is the first structure affected by FHL. The bowstring effect of the flexor hallucis longus tendon, heel strike on the outer edge and the collapse of the medial arch generate the most common conditions of the foot: hallux valgus, hallux rigidus and Morton’s neuroma.
The foot, first territory of FHL
The foot is not only the origin of the biomechanical cascade of FHL, it is also its first victim. Three mechanisms converge and generate the most common foot conditions seen in orthopedic consultation.
Three mechanisms involved
FHL desynchronizes the transition moments in pronation–supination, prevents the foot from arching during propulsion by suppressing the windlass mechanism, and locks the subtalar joint through a taut bowstring effect. The implications reach all three anatomical levels of the foot.
The three anatomical areas of the foot
To understand the foot conditions linked to FHL, one must distinguish the three areas that make up the foot. Each reacts differently to the biomechanical imbalance and develops its own conditions.
Forefoot — toes, metatarsals, sesamoids. Midfoot — medial arch, tarsus. Rearfoot — heel, subtalar joint. Three areas, three families of conditions, all linked to the same central biomechanical dysfunction.
Clinical manifestations by area
Each area of the foot develops its own conditions under the effect of FHL. The following overview makes it possible to quickly identify the condition that matches your situation.
Forefoot
Toe involvement
- Hallux valgus (bunion)
- Hallux rigidus
- Transfer metatarsalgia
- Morton’s neuroma
- Sesamoid pain
Midfoot
Collapse of the arch
- Acquired flatfoot with valgus
- Tibialis posterior tendinopathy
- Spring ligament injuries
- Tarsometatarsal osteoarthritis of the first ray
Rearfoot
Heel overload
- Overload heel pain
- FHL tenosynovitis
- Cramps in the adductor hallucis
- Calcaneal valgus
Hallux valgus, the bunion of the foot
Hallux valgus is the best-known deformity of the forefoot. It is a partial dislocation of the first metatarsophalangeal joint. The medial capsule tears, the first metatarsal moves away from the second, and the toe turns toward the second toe. A collapse of the forefoot is always present, and there is often a claw-toe retraction of the second toe.
Various causes are cited as predisposing factors: family predisposition, high-heeled shoes, shoes that are too narrow, a short first metatarsal, excess weight. But FHL is in fact the main factor behind the deformity.
Key data
98% of hallux valgus cases show a positive FHL stretch test on clinical examination, despite the toe deviation already being established. This data from the Centre du pied positions FHL as the primum movens of the deformity.
The combined surgical approach
Considering FHL as a predisposing factor, the proposed surgical treatment combines two procedures. First, a bony realignment of the first metatarsal combined with recentering of the sesamoid sling through release of the lateral structures and medial capsular reconstruction. A correction of the proximal phalanx of the big toe is sometimes added. Second, an endoscopic tenolysis of the flexor hallucis longus is offered systematically to prevent postoperative joint stiffness and limit the risk of recurrence of the deformity.
Why treat FHL as well
Without release of the tendon, the biomechanical imbalance that caused the hallux valgus persists. Bony correction alone carries a higher risk of recurrence. This combined approach partly explains the poor reputation of hallux valgus corrective surgery, which is often followed by recurrence when FHL is not treated.
Hallux rigidus, osteoarthritis of the big toe
After hallux valgus, hallux rigidus is the most common condition of the forefoot. It is a joint deformity caused by osteoarthritis, that is, the loss of cartilage on both sides of the first metatarsophalangeal joint. Often very painful, it is most often accompanied by joint stiffness and bone spurs called osteophytes, which create painful pressure points inside shoes.
Tenolysis in the early stages — In the early stages of osteoarthritis, decompressive surgery such as tenolysis of the flexor hallucis longus may have a role. The bowstring effect of the tendon in FHL leads to increased joint stress and thus constitutes a predisposing factor for osteoarthritis and for the worsening of symptoms.
Limits of conservative treatment
Conservative treatment is rarely indicated for hallux rigidus, because of the pain that tendon-stretching maneuvers can cause. At more advanced stages, other surgical solutions are offered depending on the extent of the osteoarthritic damage.
Morton’s neuroma
Morton’s neuroma clinically corresponds to mechanical pain located preferentially between the third and fourth toes. This pain results from compression of the interdigital nerve located in the web space at the base of the toes. At the outset, a bursitis is frequently found and, in chronic cases, a true neuroma, that is, a fusiform enlargement of the nerve in response to the compression.
The role of FHL — The involvement of FHL in this syndrome is linked to the roll-through of the step on the outer side of the foot. Over time, the tissues atrophy and are no longer able to bear the load, and symptoms appear. Women are more affected than men, and the peak of onset is around fifty years of age.
The early tenolysis option — The treatments usually offered range from injection to excision of the nerve, including foot orthoses and simple nerve decompression. In early cases, a tenolysis of FHL can be offered, with or without a foot orthosis. This treatment recenters the roll-through of the step and reduces the mechanical loads on the painful area.
« When you treat the foot without treating FHL, you treat the symptoms. When you treat FHL, you treat the cause. The difference is measured over time, by the absence of recurrence. »
Dr Jacques Vallotton, Centre Orthopédique d’Ouchy
Key scientific article
An information sheet from the Association Française de Chirurgie du Pied et de la Cheville complements the documentation on Morton’s neuroma.
Article
Morton’s neuroma
Morton’s neuroma or intermetatarsal neuralgia, information sheet from the Association Française de Chirurgie du Pied et de la Cheville (AFCP)
Do you recognize your foot?
Get assessed before surgery
If you have a hallux valgus, a hallux rigidus or recurrent foot pain, the mobility assessment at the Centre du pied makes it possible to objectively document the associated FHL and to guide the most appropriate management.
At a glance
Areas affected
3 anatomical
Condition #1
hallux valgus
HV with FHL
98%
Condition #2
hallux rigidus
Nerve involvement
Morton’s neuroma
Long-term effect
acquired flatfoot
Going further
Other consequences and useful pages
Ankle
The joint immediately downstream, sharing the consequences of the foot’s imbalance.
Surgical treatment
Arthroscopic tenolysis of FHL, a technique combined with hallux valgus corrections.