The reported incidence of constriction ring syndrome varies from 1/1200 and 1/15000 live births. The prevalence is equally in male and female.

Fetomaternal factors like prematurity, maternal illnes, low birth weight and maternal drug exposure are predisposing factors for the constriction ring syndrome.

No positive relationship between CRS and genetic inheritance has been reported.

The exact cause of the condition is unknown. In some cases, close family members may share this condition. In other cases, no other related persons have this condition. The scientific name for the condition is syndactyly, although this term covers both webbed fingers and webbed toes. Syndactyly occurs when apoptosis or programmed cell death during gestation is absent or incomplete. Webbed toes occur most commonly in the following circumstances:

- Syndactyly or Familial Syndactyly

- Down syndrome

It is also associated with a number of rare conditions, notably:

- Aarskog–Scott syndrome

- Acrocallosal syndrome

- Apert's syndrome

- Bardet-Biedl syndrome

- Carpenter syndrome

- Cornelia de Lange syndrome

- Edwards syndrome

- Jackson–Weiss syndrome

- Fetal hydantoin syndrome

- Miller syndrome

- Pfeiffer syndrome

- Smith-Lemli-Opitz syndrome

- Timothy syndrome

- Ectodermal Dysplasia

- Klippel-Feil Syndrome

Webbed toes in humans are a purely cosmetic condition. This condition does not impair the ability to perform any activity, including walking, running, or swimming. Depending on the severity and structure of the webbing, there can be some minor consequences.

People with more severe webbed toes may have a slight disadvantage for activities that benefit from prehensile toes, due to the toes being unable to split or move laterally. Although not scientifically proven, some believe that this condition can possibly allow for a slight advantage, specifically, in athletics. Considering your big toe is a main source for balance, having your second and third toe webbed could virtually be seen as having two big toes. Thus, allowing for better balance in athletics such as running or dance.

Psychological stress may arise from the fear of negative reactions to this condition from people who do not have webbed toes, particularly in severe cases where the nails are stuck visibly close together. Many people with webbed toes can physically feel the toes touching under the fused skin, which can cause psychological discomfort. This is due to the nerves of each toe fully developing and independent muscles working. In other cases where the toes are partially webbed, the webbing holds the separate tips of the toes against one another and prevents the muscles from spreading the toes apart, causing the toes and sometimes nails to press together.

However a disadvantage would be a difficulty in wearing flip-flops or other such footwear in warm countries. People with webbed toes may be unable to wear Toe socks or Vibram FiveFingers shoes. Difficulty navigating rough terrain barefoot, such as rocks at a beach is also common. In some cases the toes grow at different lengths causing the toes to buckle or bend and many people with severe webbed toes experience cramping in these toes due to the muscles and ligaments being strained.

Wearing shoes to protect barefoot trauma has shown decrease in incidence in ainhum. Congenital pseudoainhum cannot be prevented and can lead to serious birth defects.

Surgical correction is recommended when a constriction ring results in a limb contour deformity, with or without lymphedema.

Ainhum is an acquired and progressive condition, and thus differs from congenital annular constrictions. Ainhum has been much confused with similar constrictions caused by other diseases such as leprosy, diabetic gangrene, syringomyelia, scleroderma or Vohwinkel syndrome. In this case, it is called pseudo-ainhum, treatable with minor surgery or intralesional corticosteroids, as with ainhum. It has even been seen in psoriasis or it is acquired by the wrapping toes, penis or nipple with hairs, threads or fibers. Oral retinoids, such as tretinoin, and antifibrotic agents like tranilast have been tested for pseudo-ainhum. Impending amputation in Vohwinkel syndrome can sometimes be aborted by therapy with oral etretinate. It is rarely seen in the United States but often discussed in the international medical literature.

Minor degrees of curvature are common. Reports of incidence vary between 1% and 19.5%.

Severe congenital onychogryphosis affecting all twenty nailbeds has been recorded in two families who exhibit the dominant allele for a certain gene. Congenital onychogryphosis of the fifth toe (the little toe) is fairly common, but asymptomatic and seldom brought to the attention of medical professionals. Rather, it is brought to the attention of manicurists who routinely file the clawed toenail flat.

Some recommend avulsion of the nail plate with surgical destruction of the nail matrix with phenol or the carbon dioxide laser, if the blood supply is good.

Symbrachydactyly is a congenital abnormality, characterized by limb anomalies consisting of brachydactyly, cutaneous syndactyly and global hypoplasia of the hand or foot. In many cases, bones will be missing from the fingers and some fingers or toes may be missing altogether. The ends of the hand may have "nubbins"—small stumps where the finger would have developed, which may have tiny residual nails.

Symbrachydactyly has been reported to appear without other combined limb anomalies and usually in one arm in 1 in 30,000 births to 1 in 40,000 births.

The cause of symbrachydactyly is unknown. One possible cause might be an interruption of the blood supply to the developing arm at four to six weeks of pregnancy. There is no link to anything the mother did or did not do during pregnancy. There is also no increased risk of having another child with the same condition or that the child will pass the condition on to his or her children.

In most cases, children born with symbrachydactyly are able to adapt to their physical limitations and experience a fully functional life with no treatment. Most children with this condition can use their hands well enough to do all the usual things children do. Possible treatment includes surgery or a routine of regularly stretching the fingers.

Approximately 4% of the general population have an elongated styloid process, and of these about 4% give rise to the symptoms of Eagle syndrome. Therefore, the incidence of stylohyoid syndrome may be about 0.16%.

Patients with this syndrome tend to be between 30 and 50 years of age but it has been recorded in teenagers and in patients > 75 years old. It is more common in women, with a male:female ratio ~ 1:2.

Due to a developmental arrest there is an abnormal alignment of the joint surfaces at either interphalangeal joint causing angulation in the plane of the palm. The finger may be slightly bent or have a very prominent bend.

Most children with symbrachydactyly have excellent function in daily activities. Due to the length of their arm, they do not qualify for most artificial limbs. However, some adaptive prosthetics and equipment for sports and leisure activities may be helpful when the child is older. Children who demonstrate some functional movement in their remaining fingers and within the palm are evaluated for possible surgery such as toe transfers.

Malalignment of the nail plate is a congenital malalignment of the nail of the great toe, and is often misdiagnosed although it is a common condition.

The accessory nail of the fifth toe is a physical trait of the small toe, where a minuscule "sixth toenail" is present in the outer corner of the nail situated on the smallest toe. It is commonly perceived to be especially prevalent amongst Han Chinese;.

There are two less common types of McGillivray syndromes are: Metopic synostosis (trigonocephaly). The metopic suture runs from your baby's nose to the sagittal suture. Premature fusion gives the scalp a triangular appearance. Another one is Lambdoid synostosis (posterior plagiocephaly). This rare form of craniosynostosis involves the lambdoid suture, which runs across the skull near the back of the head. It may cause flattening of your baby's head on the affected side. A misshapen head doesn't always indicate craniosynostosis. For example, if the back of your baby's head appears flattened, it could be the result of birth trauma or your baby's spending too much time on his or her back. This condition is sometimes treated with a custom-fit helmet that helps mold your baby's head back into a normal position.

Morton's Toe is a minority variant of foot shape. Its recorded prevalence varies in different populations, with estimates from 2.95% to 22%.

Training of the feet, utilizing foot gymnastics and going barefoot on varying terrain, can facilitate the formation of arches during childhood, with a developed arch occurring for most by the age of four to six years. Ligament laxity is also among the factors known to be associated with flat feet. One medical study in India with a large sample size of children who had grown up wearing shoes and others going barefoot found that the longitudinal arches of the bare-footers were generally strongest and highest as a group, and that flat feet were less common in children who had grown up wearing sandals or slippers than among those who had worn closed-toe shoes. Focusing on the influence of footwear on the prevalence of pes planus, the cross-sectional study performed on children noted that wearing shoes throughout early childhood can be detrimental to the development of a normal or a high medial longitudinal arch. The vulnerability for flat foot among shoe-wearing children increases if the child has an associated ligament laxity condition. The results of the study suggest that children be encouraged to play barefooted on various surfaces of terrain and that slippers and sandals are less harmful compared to closed-toe shoes. It appeared that closed-toe shoes greatly inhibited the development of the arch of the foot more so than slippers or sandals. This conclusion may be a result of the notion that intrinsic muscle activity of the arch is required to prevent slippers and sandals from falling off the child’s foot.

The major treatment is surgery for most babies. The type of surgery which they would undergo differs from age and strength they have. The main reason of doing the surgery is to alleviate pressure on the brain, and create a space for brain developing and growing. It would improve infant’s appearance.

The first one is Traditional surgery. During surgery, they make an incision in the baby's scalp and cranial bones, and reshape the portion of the skull. Sometimes plates and screws, often made of material that is absorbed over time, are used to hold the bones in place. Surgery, which is performed during general anesthesia, usually takes hours.

After surgery, your baby remains in the hospital for at least three days. Some children may require a second surgery later because, the craniosynostosis recurs. Also, children with facial deformities often require future surgeries to reshape their faces.

Another one is Endoscopic surgery. This less invasive form of surgery isn't an option for everyone. But in certain cases, the surgeon may use a lighted tube (endoscope) inserted through one or two small scalp incisions over the affected suture. The surgeon then opens the suture to enable your baby's brain to grow normally. Endoscopic surgery usually takes about an hour, causes less swelling and blood loss, and shortens the hospital stay, often to one day after surgery.

Flat feet can also develop as an adult ("adult acquired flatfoot") due to injury, illness, unusual or prolonged stress to the foot, faulty biomechanics, or as part of the normal aging process. This is most common in women over 40 years of age. Known risk factors include obesity, hypertension and diabetes. Flat feet can also occur in pregnant women as a result of temporary changes, due to increased elastin (elasticity) during pregnancy. However, if developed by adulthood, flat feet generally remain flat permanently.

If a youth or adult appears flatfooted while standing in a full weight bearing position, but an arch appears when the person plantarflexes, or pulls the toes back with the rest of the foot flat on the floor, this condition is called flexible flatfoot. This is not a true collapsed arch, as the medial longitudinal arch is still present and the windlass mechanism still operates; this presentation is actually due to excessive pronation of the foot (rolling inwards), although the term 'flat foot' is still applicable as it is a somewhat generic term. Muscular training of the feet is helpful and will often result in increased arch height regardless of age.

The most common digit to become ingrown is the big toe, but ingrowth can occur on any nail. Ingrown nails can be avoided by cutting nails straight across; not along a curve, not too short and no shorter than the flesh around it. Footwear that is too small or too narrow, or with too shallow of a "toe box", will exacerbate any underlying problem with a toenail. Sharp square corners may be uncomfortable and cause snagging on socks. Proper cutting leaves the leading edge of the nail free of the flesh, precluding it from growing into the toe. Filing of the corner is reasonable. Some nails require cutting of the corners far back to remove edges that dig into the flesh; this is often done as a partial wedge resection by a podiatrist. Ingrown toe nails can be caused by injury, commonly blunt trauma in which the flesh is pressed against the nail causing a small cut that swells. Injury to the nail can cause it to grow abnormally, making it wider or thicker than normal, or even bulged or crooked.

The trait can be observed on either one or both feet, where there is a separation of the toenail situated on the smallest toe. The separated part of the nail forms a smaller "sixth toenail" on the corner of the larger, or "main" section of the toenail, on the outermost side of the foot, which protrudes outwards from the corner of the larger nail. The additional "nail" can be cut with a nail clipper, just like any other nail.

In humans, excessive forces caused by sudden bending upwards of the big toe, high heels, or a stumble can contribute to sesamoiditis. Once the sesamoid bone is injured it can be very difficult to cure, because every time you walk you put additional pressure on the sesamoid bone. Treatment in humans consists of anti-inflammatory medication, cortisone injections, strapping to immobilize the big toe, and orthotics with special accommodations to keep pressure off the affected bone.

In horses, sesamoiditis is generally caused by excess stress on the fetlock joint. Conformation that promotes sesamoiditis include long pasterns, or horses with long toes and low heels.

Three main support groups of this syndrome are the ASGA in Australia, The Association for Children with Genetic Disorders in Poland, and the Association of People of Genetic Disorders in Greece.

Affected breeds include the Shire, Clydesdale, Belgian, Gypsy cob, and Friesian. Signs are usually only seen in horses older than two years. Both sexes are affected.