What is hallux valgus/bunion?



What is a bunion?

Hallux valgus is a condition causing a bunion on the foot. Now what is this excrescence made of? How does the condition develop over time? EPITACT® gives you answers for a better understanding of this deformity of the foot and to prevent its appearance or diminish its growth.

 

Definition

Hallux valgus is commonly called ‘bunion’ on the foot, originating from latin. ‘Hallux’ means the big toe of the foot and ‘valgus ‘ indicates the outwards direction. This condition is a deflection of the big toe outwards combined with the inwards deflection (varus ) of the first metatarsal bone. This deformity shows a bony protrusion (front of the first metatarsus) on the inner side of the foot(1).

This slow deflection moves the hallux towards the other toes, which may cause additional deformities. The most commonly known is the claw of the second toe (hammer toe ).

When the first head of the metatarsal bone does not operate properly its function of supporting the first shaft, then a lateral transfer of the weight happens. Metatarsalgia slowly develop on the middle shafts. These plantar pains under the front foot, are coming in addition to the pain from frictions of the bunion against the shoes. Depending on the development stage of the hallux valgus , they may cause additional pain on the plantar area, calluses and hard corn (2).

 

The different stages of a hallux valgus

Like other conditions, hallux valgus keeps on developing if not cured. Its progression shows four stages, according to the size of the deflection between the first metatarsal bone and the big toe. This progression is shown on a medical radiography , or from a visual observation.

The radiographic diagnosis is based on two images:

  • a front image showing the middle metatarsal bones;
  • plus a side image showing the foot section on its inner side.

Visual observation allows to measure the angle of the deflection using the “Manchester scale”, which draws four distinctions of this deflection: zero level, lower level, middle level or severe level(3,4). These four distinctions have an indicative value and may vary according to the authors of the science papers(1,2).

A « normal foot » may show angles of deflection of maximum 10 degrees between the first metatarsus and the first phalange, and for the angle of deflection between the first and the second metatarsus.

Light hallux valgus

A lower level of hallux valgus shows an angle of deflection between the first metatarsal bone and the first phalange (MTP1) of 11 to 20 degrees and an angle of 12 degrees between the first and the second metatarsus (M1M2). At this stage, the pain is caused by frictions between the bunion and the shoe. Inflammation may occur (reddened skin). Wearing a foot bunion protector or toe separators during the day can contribute to reduce the inflection. Then at the lower level there is no or little weight transfer onto the second shaft. The pain feeling is unclearly located and the bone protrusion is still quite invisible. The compression of the medial cutaneous nerve against the shoe can also lead to pain.

Middle level of hallux valgus

Moderate hallux valgus presents an angle MTP1 between 20 and 40 degrees and an angle M1M2 of 15 to 18 degrees. The phalange does not articulate correctly against the metatarsus, it is blocked by the deflection. The lateral weight transfer brings pain under the second metatarsal head, as it is hindered in its usual supporting function. The sesamoid bones (under the metatarsal heads) are dislocated and the intermetatarsal space cannot play its role properly. The sesamoid block, which is directly under pressure, becomes painful. It is the deformity of the articulation that causes pain in the foot sole. The bone protrusion grows and brings painful friction with shoes. Few possibilities exist to reduce this already large protrusion and arthrosis symptoms may appear next to the deflection/protrusion when walking.

Severe hallux valgus

Hallux valgus is defined as severe when the MTP1 angle is larger than 40 degrees and the M1M2 angle is larger than 20 degrees. The big toe is deviated under the second toe as a consequence of its very severe deflection. The articulation is completely flattened, leading to its entire luxation in most critical situations. The deviation of the second toe is so large that the foot sole is now deformed. At this stage, the subluxation or even the complete luxation of the first phalange from the second phalange can be easily identified through manual testing when one can notice a deformity similar to a small step.

The mechanical dysfunction of the forefoot causes other toes to turn into 'claw toes'. Dorsal hard corns appear upon proximal interphalangeal joints and make it really hard to wear tight shoes. Hard corn on the extremities of the toes can also occur.

The progression of a hallux valgus forces the articulations to offset defect pressure holding points in order to maintain an approximate stability. In practical terms, painful repercussions may be felt in the knees or in the lumbar belt. The hallux valgus may be relieved from pain as another articulation would start feeling aching. Then it becomes necessary to examine the whole body to analyse the personal locomotion biomechanical process. As feet make the connection between the body and the ground, its biomechanical function has effects on the other biomechanical chains of the body.

 

Symptoms

The first symptom of hallux valgus is a throbbing ache in the metatarsal articulation. This is often due to the first distortions of the articulation coming into friction with the shoe (reddened and wounded skin). A compression of the medial nerve against a bone, the soft parts of the foot and shoes, could even generate additional pain.

Later, a metatarsalgia combined with the transfer of weight creates additional specific pain zones.  As the second toe is forced to a 'claw' position, it will be hardly bearable in normal shoes and the regular friction causes hard corns on the proximal interphalangeal joint (5). These uncomfortable symptoms encourage the patient to see a medical specialist in search of pain relief, easing of his locomotion function or even just to erase cosmetic inconvenient.

The earlier the condition is managed, the less invasive and radical are the necessary treatments. Preventive solutions contribute to defer the emergence of the hallux valgus and to slow down its development. EPITACT®, specialist for foot care, designed various medical devices (bunion splints, fine silicone protectors…) to prevent frictions, relieve pain and rectify the big toe. Discover EPITACT®’s protectors and correctors for hallux valgus*.

 

*These products are class I medical devices that bear the CE marking under this regulation. Carefully read the instructions before use. Manufacturer: Millet Innovation. 01/2021

 

For more details about this general and simplified approach, here are further sources:

(1)Vanore JV, Christensen JC, Kravitz SR, Schuberth JM, Thomas JL, Weil LS, et al. Diagnosis and treatment of First Metatarsophalangeal Joint Disorders. Section 1: Hallux valgus . The Journal of Foot and Ankle Surgery. Mai 2003; 42(3):11223.

(2)Baudet B. "Traitement de l'hallux valgus " in Thibaut Leemrijse, Jean-Luc Besse, Bernhard Devos Bevernage, Bernard Valtin "Pathologie du pied et de la cheville", Paris, Elsevier Masson. Vol. 1. 2009, p 102-106.

(3)Garrow AP, Papageorgiou A, Silman AJ, Thomas E, Jayson MIV, Macfarlane GJ. The Grading of Hallux Valgus: The Manchester Scale. Journal of the American Podiatric Medical Association. févr 2001; 91(2):74

(4)Menz HB, Munteanu SE. Radiographic validation of the Manchester scale for the classification of hallux valgus deformity. Rheumatology. 1 août 2005;44(8):1061

(5)Curvale G, Rocheweger A, Piclet-Legre B. Hallux valgus . Podologie. 1999; 27-080-A-30: p 6.

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