The anterior cruciate ligament (ACL) is the tissue connecting the thigh bone to the shin bone. A sprain or tear most often occurs to young athletes who participate in sports like soccer, football, and basketball. Surgery may be required if treatments such as physical therapy are not effective.

Twisting the ankle joint can cause a break in one of the three bones that make up the ankle. In children and teens, this ankle fracture can damage the growth plates at the end of each leg bone, which can have long-term effects. It is important to see a doctor quickly.

This condition is usually a serious, long-term injury that limits how the ankle moves. It is caused by overusing the ankle joint or by a sudden injury. Surgery may be necessary if pain or symptoms do not stop after other treatments have been tried. 

Arthrogryposis results when a joint is fixed in one position due to two or more joint deformities such as muscles and nerves around the joint being absent. Treatment may include physical therapy, occupational therapy and corrective surgery. 

This growth disorder of the shin bone (tibia) occurs when one or both of the lower legs bow outward. Blount's disease slowly gets worse. While braces make work for some patients, in some cases, surgery will be needed. If treatment provides a good position for the leg, a child should resume normal activity after the correction.

Bowlegs, or legs that curve outwardly, are part of normal growth for most children until the age of 3. The condition will usually improve on its own; children whose bowlegs do not get better at that age should see a doctor for X-rays and possible treatment.

Brittle bone disease, also known as osteogenesis imperfecta, is an inherited disorder in which the bones break easily. OI is caused by a gene mutation that affects the body’s production of collagen, not by too little calcium or poor nutrition. Despite the challenges of managing OI, most people lead productive lives. A cure does not exist at this time. 

A spiral fracture of the tibia means that the calcified, hard portion of the bone is fractured but the periosteum (the outer sheath of vascular connective tissue) is intact. Most of these fractures are treated by placing the child in a walking boot. These fractures will not cause any long-term limitations on physical activities or sports.

Buckle fractures occur to the radius, ulna or both and will heal faster than a than a typical fracture. A cast is not usually necessary, and treatment is typically a removable wrist brace. Buckle fractures do not put a patient at higher risk for another fracture in the future.

Cerebral palsy is a group of disorders caused by abnormal brain development or damage to the  developing brain that affects one’s ability to control their muscles. Patients with CP will have a varying degree of problems with movement and posture; many also have related conditions that include intellectual disability, seizures, and spine or joint problems. No cure is available yet, but treatment can improve the lives of those who have the condition. It is important to begin a treatment program as early as possible to develop a plan to help the child reach his or her full potential.

The clavicle (collarbone) is one of the most fractured bones in the body, usually when a child falls directly onto the shoulder. Unlike other fractures, a clavicle fracture does not need to be lined up perfectly to heal well, and most clavicle fractures heal within several weeks with the use of a sling or a shoulder immobilizer. 

Clinodactyly is an abnormal appearance of a finger, most commonly the little finger. The joint closest to the nail bed is angulated toward the ring finger. This minor congenital defect does not get worse with age. In severe cases, treatment may be necessary. Clinodactyly can be associated with many syndromes including Down syndrome. 

Clubfoot is a deformity of the bones and joints in newborns in which the foot is stiff and points downward, the toes turn inward, and the soles of the feet face each other. The first approach to treating a clubfoot is casting the foot for several months. Surgery may be necessary. Children without a syndrome or neurological cause for their clubfeet will be able to walk, even if the clubfeet are not corrected.

Congenital limb defects occur when all or a portion of the limb fails to form normally. These defects include complete absence of the limb, failure of part of the limb to separate and duplication. Treatment may include prosthetics, orthotics, surgery and/or rehabilitation to provide the child with a limb that has proper function and appearance. 

Developmental dysplasia (dislocation) of the hip occurs when the hip joint has not formed to normal depth. The ball of the thigh bone will be loose in the shallow hip socket and may dislocate easily. After treatment is complete, most children can resume normal activities.

A dislocation occurs when extreme force is put on a ligament, allowing the ends of two connected bones to separate. Dislocations are uncommon in younger children because their growth plates are weaker than the muscles or tendons; instead, children in this age group are more prone to a fracture.

Elbow fractures happen either in the upper arm bone and the lower arm bone near the elbow. Depending on the severity of the fracture, treatment can be either casting or surgery. Fractures of the lower arm bone  will require weekly X-rays to monitor the amount of displacement and may require surgery. After treatment, movement of the elbow is encouraged.

Ewing sarcoma is a rare type of cancer that occurs primarily in the bones of the pelvis, ribs, legs, chest and arms. The tumors can also spread elsewhere in the body. Most cases occur from age 10 to 20 years old. As with any cancer, prognosis and long-term survival vary greatly from child to child. Recent research about the genetics of Ewing sarcoma formation has led to improvements in diagnosing the disease.

With this condition, the hip bones have not formed normally during childhood, which in turn causes the hip bones to rub against each other and damage the joint. Nonsurgical treatment includes changes in activity levels, medications and physical therapy. Surgery may also be an option if these treatments don't relieve the pain.

See In-toeing. 

All babies are born with flat feet and develop arches around age 7. No special shoes or braces are needed, but shoes should be supportive and must fit properly. Older children with painful flat feet may need to see a primary care physician. 

Arm fractures in children and young athletes involve the upper arm, shoulder, elbow and forearm. Broken bones, or fractures, are quite common and can happen during play or while  participating in sports. Broken bones in children heal at different rates depending on the child’s age and what type of fracture occurred. 

A ganglion cyst is a benign mass that generally seen as a lump around/near a joint or tendon. Smaller cysts, however, may be present underneath the skin surface. Ganglion cysts usually increase and decrease in size. Because they tend to resolve on their own and are typically painless, surgery is usually not needed. 

Growth plates are areas of growing tissue near the end of the long bones. As the weakest parts of the developing bones, injuries to them have the potential to disrupt the bone’s normal growth. When young people finish growing, the growth plates close and are replaced by solid bone. Most growth plate fractures do not cause any lasting problems. When one limb ends up shorter than the other, additional surgery may be required.

A hip arthroscopy is a procedure performed by an orthopedic surgeon to identify or treat a potential hip disorder. Even though a hip arthroscopy might be less invasive than an open hip surgery, careful follow-up and physical therapy after surgery are required. 

In-toeing occurs when the bones in the lower leg are turned inward (internal tibial torsion) or when the bone in the upper leg is turned inward (femoral anteversion). Commonly called pigeon toes, both types may correct themselves. 

Out-toeing (femoral retroversion) results when the thigh bone twists backwards. Children with out-toeing should be evaluated for hip problems, but most will get better as they get older.

Knock knees is a normal condition in which a child's knees are closer together than the ankles. This should correct itself by age 6. This is a normal variation for children that does not require correction. It will not cause long-term problems.

Kyphosis is a curvature of part of the spine that causes a rounding of the back. It can develop at any age. Treatment may include bracing or, in more severe cases, surgery. However, many patients do well without treatment. Others benefit from physical therapy or exercise. 

No one’s legs are perfectly symmetrical, and a difference of up to 2 centimeters in adults is typical. If a child’s leg lengths are unequal, it may be normal or could be due to conditions such as bone growth disturbances, hip dislocation, neuromuscular diseases and congenital abnormality. After examination, a doctor will recommend the appropriate treatment.

A spine affected by lumbar lordosis has a curvature of the vertebrae in the lower back area. More rarely, children develop cervical lordosis in which there is an inward curve of the neck. The goal of treatment is to stop the progression of the curve and minimize deformity. Lordosis will require frequent examinations by the child's doctor to monitor the curve over time.

The meniscus is one of two c-shaped pieces of cartilage in each knee that help the knee absorb shock. They can tear when the knee is twisted or injured in a fall. Meniscal tears are more uncommon in children than they are in adults and teens, unless the meniscus is abnormal from birth. Children with small tears in an otherwise normal meniscus may heal with a month or more of rest. 

Metatarsus adductus is a common foot deformity in which the front half of the foot turns inward. Babies born with metatarsus adductus rarely need treatment as they grow. They may, however, be at increased risk for developmental dysplasia of the hip, a condition of the hip joint in which the top of the thigh slips in and out of its socket.

Muscular dystrophy is a genetic disorder affecting young males that weakens muscles over time. Many different types of muscular dystrophies occur, each with different levels of muscle weakness and different ages of onset. Each results in worsening neurologic dysfunction. Muscular dystrophy has no cure, but early treatment and rehabilitation may help an individual with muscular dystrophy get the services and treatments needed to lead a full life. 

Nursemaid’s elbow is a common condition in children younger than age 4. It occurs when the radius bone in the forearm becomes partially detached from the ligament holding it to the elbow. Once the elbow has sustained this type of injury, it is more likely to recur. Most children outgrow the tendency for nursemaid's elbow by the age of 5.

Osgood-Schlatter disease is an overuse condition or injury of the knee caused by constant pulling of the patellar tendon below the knee. It affects growing children and adolescents, particularly athletes. Treatment may include medication, activity restrictions and physical therapy. Osgood-Schlatter disease often resolves with time, and surgery is rarely required.

Osteochondritis dissecans causes a small segment of bone in the ankle to die, usually due to a combination of poor blood supply, constant ankle movement and many ankle injuries. In younger patients, the cracked or fractured bone and cartilage is more likely to heal on its own. In older children and young adults, OCD has a lower chance of healing without treatment or surgery.

Osteomyelitis is an inflammatory reaction in a bone caused by a very serious infection that has likely moved to the bone from another part of the body. Osteomyelitis needs treatment immediately; go to the emergency room if you suspect your child has such an infection. 

The most common type of bone cancer among children, adolescents and young adults, osteosarcoma usually occurs at the ends of the long bones of the arms, legs and pelvis near the growth plates. However, osteosarcoma cancer cells can also metastasize to other areas of the body, most commonly to the lungs. As with any cancer, prognosis and long-term survival can vary greatly from child to child. Prompt medical attention and aggressive therapy are important for the best prognosis, along with continuous follow-up care.

Patellar instability occurs when the kneecap (also called the patella) does not slide centrally within its natural groove in the femur. Those at risk for these kinds of injuries include active teenagers and young adults ages 14-20 who participate in contact sports. Sometimes the patella moves back in place by itself. Patients with significant pain or recurrent dislocation may require surgery.

Scoliosis is one of the spinal deformities in which the spine becomes curved or twisted and can cause uneven shoulders, breathing difficulties, back pain, and a humpback or swayback appearance. If left untreated, these conditions can get worse over time. Patients with scoliosis and other conditions receive specialized evaluation, treatment and care in Texas Children’s Scoliosis & Spinal Deformity Program

A dislocated shoulder occurs when the humeral head comes partially or completely out of place from the glenoid (a shallow socket bone). The younger the athlete, the more likely that the shoulder could move out of place again. Severe pain stops almost immediately once the shoulder joint is put back in place. 

Sports with overhead arm motions put large amounts of stress on the shoulder, which can lead to injury. Children should not continue to play sports if they have pain in their shoulders or elbow joints to keep any damage from getting worse. It is best to let the shoulder completely heal before getting back to forceful overhead arm movements. 

A shoulder separation is common in young athletes and generally happens with a direct impact to the shoulder. Known medically as an acromioclaviclar (AC) joint sprain, it means the ligaments that attach the collarbone to the top of the shoulder blade have been injured. Recovery with a mild shoulder separation may take a few weeks. 

Slipped capital femoral epiphysis (SCFE) is the slippage of femoral head (ball of the thigh bone) off the neck of the femur though the growth plate. Treatment will begin immediately, most commonly with surgery. Most patients who are successfully treated for SCFE do very well although some children may be at risk to develop hip arthritis later in life. 

Spina bifida is characterized by the incomplete development of closure of the back over the spine and spinal cord with varying degrees of severity. In most cases, spina bifida is diagnosed prenatally. The Texas Children's Fetal Center performs some in utero procedures on spina bifida patients. Surgery to close the newborn's spinal opening is generally performed within 24 hours after birth to minimize the risk of infection and to preserve existing function in the spinal cord. The long-term effects of spina bifida depend on the severity of the defect. 

Spondylolisthesis is when the vertebra can start to shift out of place if a stress fracture weakens the bone so much that it is unable to maintain its proper position. Spondylolisthesis is one of the most common causes of lower back pain in adolescent athletes.

Symbrachydactyly is a very rare congenital condition in which the fingers are not formed properly before birth, likely due to a lack of blood flow to the tissue. Treatment may include corrective surgeries, occupational therapy and protheses. Patients often have mild limitations in daily activities depending on the extent of the disease.

Thumb hypoplasia is an abnormally small, poorly developed thumb, which can be caused by muscles or bones being absent or abnormal. (An absent thumb is known as thumb aplasia.) Physical therapy may improve function; reconstructive surgery – sometimes performed more than once – will be beneficial for some cases. 

See In-toeing.

Any of the bones in the toes can be broken. They will usually be swollen and bruised. Treatment is usually buddy-taping the injured toe to the toe next to it. Toe fractures usually heal within 4-6 weeks. 

A turned and tilted head and neck that cause the baby to hold its head to one side are characteristics of muscular torticollis. The condition improves during the first year of life in the majority of cases. It may improve faster if the baby gets physical therapy to stretch the neck muscles.