Metatarsus Adductus: The Basics

Metatarsus Adductus: The Basics

A few points to remember:

• Metatarsus adductus deformity is a forefoot which is adducted in the transverse plane with the apex of the deformity at LisFranc’s (tarso-metatarsal) joint. The fifth metatarsal base will be prominent and the lateral border of the foot which is convex in shape . The medial foot border is concave with a deep vertical skin crease located at the first metatarso cuneiform joint level. The hallux (great toe) may be widely separated from the second digit and the lesser digits will usually be adducted at their bases (se below). ln some cases the abductor hallucis tendon may be palpably taut just proximal to its insertion into the inferomedial aspect of the proximal phalanx (1)
• To measure the deviation of the metatarsals, the midline of the foot correspondingto bisecting the heel is used as a reference. This is the line that divides the heel pad into equal parts and, when extended, runs through the second toe or the second web space. In mild deformities, the midline of the foot runs through the third toe. In moderate adductus deformities, it falls between the third and fourth toes. In severe deformities the line is lateral to the third web space.(2)
• If detected early, stretching is a common and effective treatment for mild and some moderate cases. The heel is steadied with one hand while the forefoot is abducted in relation to the hind foot. This is done for 5 reps, 5-7 times per day. (2)
• 85% will resolve spontaneously, is caused by intrauterine position, is flexible & resolves spontaneously in more than 90 % of children. (3)
• Though often used interchangeably, the term "metatarsus adductus" is usually reserved for milder cases, where the forefoot is adducted on the hindfoot at the tarso-metatarsal articulation. Metatarsus varus is often reserved for conditions where the matatrsals are actually curved AND the forefoot is adducted on the hindfoot. (4) The term "Metatarsus primus varus" is reserved for feet which have the same neutral or valgus hindfoot and varus forefoot but, in addition, increased divergence of the first and second metatarsals. (5)
• It is interesting to note that along with forefoot adductus, hip dysplasia and internal tibial torsion are common (6) and this patient has the latter
• Gait abnormalities seen with this deformity include a decreased progression angle, in toed gait, excessive supination of the feet with low gear push off from the lesser metatarsals. 

1.  Bleck E: Metatarsus adductus: classification and relationship to outcomes of treatment. J Pediatric Orthop 3:2-9,1983.

2. Bohne W. Metatarsus adductus. Bulletin of the New York Academy of Medicine. 1987;63(9):835-838.  link to FREE full text: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1629274/

3. http://www.wheelessonline.com/ortho/metatarsus_adductus

4. Peabody, C.W. and Muro, F.: Congenital metatarsus varus. J. Bone Joint Surg. 15:171-89, 1933.

5. Truslow, W.: Metatarsus primus varus or hallux valgus? J. Bone Joint Surg.23:98-108, 1925.

6. Jacobs J: Metatarsus varus and hip dysplasia. C/inO rth o p 16:203-212, 1960

additional references:

Kane R. Metatarsus varus. Bulletin of the New York Academy of Medicine. 1987;63(9):828-834. link to FREE full text: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1629282/

Wynne-Davies R, Littlejohn A, Gormley J. Aetiology and interrelationship of some common skeletal deformities. (Talipes equinovarus and calcaneovalgus, metatarsus varus, congenital dislocation of the hip, and infantile idiopathic scoliosis). Journal of Medical Genetics. 1982;19(5):321-328. link to FREE full text: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1048914/

 Every foot has a story. 

 This is not your typical “in this person has internal tibial torsion, yada yada yada” post.  This post poses a question and the question is “Why does this gentleman have a forefoot adductus?”

The first two pictures show me fully internally rotating the patients left leg. You will note that he does not go past zero degrees and he has femoral retroversion. He also has bilateral internal tibial torsion, which is visible in most of the pictures. The next two pictures show me fully internally rotating his right leg, with limited motion, as well and internal tibial torsion, which is worse on this ® side

 The large middle picture shows him rest. Note the bilateral external rotation of the legs. This is most likely to create some internal rotation, because thatis a position of comfort for him (ie he is creating some “relief” and internal rotation, by externally rotating the lower extremity)

 The next three pictures show his anatomically short left leg. Yes there is a large tibial and small femoral component. 

 The final picture (from above) shows his forefoot adductus. Note that how, if you were to bisect the calcaneus and draw a line coming forward, the toes fall medial to a line that would normally be between the second and third metatarsal’s. This is more evident on the right side.  Note the separation of the big toe from the others, right side greater than left. 

Metatarsus adductus deformity is a forefoot which is adducted in the transverse plane with the apex of the deformity at LisFranc’s (tarso-metatarsal) joint. The fifth metatarsal base will be prominent and the lateral border of the foot convex in shape . The medial foot border is concave with a deep vertical skin crease located at the first metatarso cuneiform joint level. The hallux (great toe) may be widely separated from the second digit and the lesser digits will usually be adducted at their bases. ln some cases the abductor hallucis tendon may be palpably taut just proximal to its insertion into the inferomedial aspect of the proximal phalanx (1)

Gait abnormalities seen with this deformity include a decreased progression angle, in toed gait, excessive supination of the feet with low gear push off from the lesser metatarsals. 

 It is interesting to note that along with forefoot adductus, hip dysplasia and internal tibial torsion are common (2) and this patient has some degree of both. 

 His forefoot adductus is developmental and due to the lack of range of motion and lack of internal rotation of the lower extremities, due to the femoral retrotorsion and internal tibial torsion.  If he didn’t adduct the foot he would have to change weight-bearing over his stance phase extremity to propel himself forward. Try internally rotating your foot and standing on one leg and then externally rotating. See what I mean? With the internal rotation it moves your center of gravity over your hip without nearly as much lateral displacement as would be necessary as with external rotation. Try it again with external rotation of the foot; do you see how you are more likely displace the hip further to that side OR lean to that side rather than shift your hip? So, his adductus is out of necessity.

Interesting case! When you have a person with internal torsion and limited hip internal rotation, with an adducted foot, think of forefoot adductus!

1.  Bleck E: Metatarsus adductus: classification and relationship to outcomes of treatment. J Pediatric Orthop 3:2-9,1983.

2. Jacobs J: Metatarsus varus and hip dysplasia. C/inO rth o p 16:203-212, 1960

What kind of shoe do you put this foot in?

Look carefully at these dogs. Notice anything peculiar? Look at the forefoot to rearfoot relationship. What do you see?

Normally, we should be able to draw a line from the center of the heel and it should pass between the 2nd and 3rd metatarsal heads. If the line passes through or outside the 3rd metatarsal heads, you have a condition called metatarsus adductus. It occurs from fetal positioning in utero. In children (18 mos to 4 years) it can often be corrected by wearing the shoes on the opposite feet (yes, you read that correctly)

We usually try and distinguish whether the adductus is occurring at the tarsal/ metatrsal articulation or the transverse tarsal joint.

OK, so now what?

Think of the unique biomechanics that happen here. Adduction (along with plantar flexion and inversion) are components of supination. So, the adduction component makes for  a more rigid foot (notice the arch structure in the pedograph). We are not saying this foot does not pronate, only that it pronates less.

Total amount of pronation will be determined by several factors,

• including body weight

• available rear foot motion

• available forefoot motion

• knee angulation (ie genu valgus or varus)

• available internal rotation of the hips (how much ante or retroversion/torsion is present)

• strength of abdominals, particularly the external obliques

• tibial torsion

This individual had

·       markedly increased valgus angle (14 degrees)

·       moderate external tibial torsion

·       femoral antetorsion

this, along with their body weight, explains the rear foot pronation seen on the pedograph.

So, what type of shoe? You should pick a shoe that:

·       does not exaggerate the deformity (ie. a shoe that does not have an excessively curved last)

·       a shoe that does not work (too much) against the deformity (ie. an extremely straight lasted shoe)

·       In this case, a shoe with some motion control features (to assist in controlling some of the increased rear foot motion. This may be something as simple as a dual density midsole

·       a shoe that, upon gait analysis, works to provide the best biomechanics for the circumstances.

As you can see, when it comes to shoe fit and prescription, there are no had and fast rules. You need to examine the individual and have all the facts.

If you are a little lost, or want to know more, you should take our National Shoe Fit Program. Maybe you even should consider getting Level 1 certified by taking the International Foot and Gait Education Council exam. Need more details? Email us at: thegaitguys@gmail.com