An apophysis is a type of growth plate where a tendon attaches to a bone. It doesn’t contribute to the linear growth of a bone (those growth plates are called epiphysis) but it is another part of the immature skeleton that can be more vulnerable to injury during periods of growth. After puberty, these separate ossification centres fuse with the main bone.
The reason an apophysis is prone to injury in children and adolescents is because it is a weaker cartilaginous attachment between 2 parts of the bone compared to the strong attachment of the tendon to the bone.
There are 2 main types of injuries that can occur at the apophysis. The less common one is an acute event called an avulsion injury where a sudden traction force is applied to the apophysis, which causes it to pull apart. The other more common type is a slowly building injury commonly termed traction apophysitis caused by traction forces applied by the muscle-tendon unit to the apophysis over time that eventually leads to change at the apophysis, causing it to widen. This traction is sometimes felt as pain to the young athlete but not always. Sometimes an acute avulsion injury can occur after a period of traction apophysitis.
Acute avulsion injury
Apophyseal avulsion injuries are usually felt by the athlete as a sudden onset of pain after a large force is applied to the area during jumping, sprinting, kicking or throwing and they may also feel something pop. These avulsion injuries can occur at any site where a tendon inserts into an apophysis but are most common around the knee, hip and foot in the lower limb and the elbow in the upper limb. If the lower limb is involved the child or adolescent often has a limp afterwards.
Avulsion injuries are best diagnosed with a combination of clinical examination and xray. Most can be treated non-operatively but some lower limb injuries need a short period of non-weight bearing on crutches and occasionally surgery is warranted. As with all injuries related to a growth plate, it is important to get an accurate diagnosis early so that the best course of treatment for the individual injury can be determined before the occurrence of secondary complications.
Traction apophysitis is a common presentation in young athletes as a result of increased traction of the muscle-tendon unit on the apophysis. This is thought to be due to a combination of excessive loading and growth of the bones, possibly leading to less flexibility of the tissues during the growth period. The ossification centres appear and fuse with the main bone at different ages and the apophysis is most vulnerable to traction forces just before it closes. This gives a fairly predictable pattern of involved sites in the body at certain ages and timeframes.
The most common traction apophysitis is known as Osgood-Schlatter disease and affects the insertion of the patella tendon onto the tibia at the bottom of the knee. The next most common is Sever disease, which affects the attachment of the Achilles tendon to the calcaneus (heel bone). Other less common sites include the peroneus brevis tendon to the 5th metatarsal on the outside of the foot (Iselin disease), the top of the patella tendon to the bottom of the patella in the knee (Sinding-Larssen-Johanssen disease), the inside of the elbow where the forearm flexors and pronators attach to the medial epicondyle (little league elbow) and various sites around the hip and pelvis where muscles such as the rectus femoris, sartorius, psoas and hamstrings attach.
A traction apophysitis of the knee where the patella tendon joins the tibia (main shin bone) at the tibial tuberosity.
This is the most common traction apophysitis and occurs in children aged 9 – 14. It occurs 1-2 years earlier on average in girls due to their earlier growth spurt but is 4 times more common in boys compared to girls. It is more common in the active population with 20% of active adolescents experiencing it to some degree compared to only 5% of inactive adolescents.
It most typically occurs in a 13-14 year old boy or an 11-12 year old girl after a recent growth spurt. It causes pain during or after activity at the bottom of the knee and this area can also be swollen and tender to touch. It occurs in both knees in a quarter to one half of the adolescents involved. The pain gradually creeps up on them and sometimes starts as pain only after activity but then progresses to pain during activity that can cause a limp and impair activity. It is usually aggravated by jumping, running, squatting, kneeling and going up stairs or uphill and is relieved by rest.
Osgood-Schlatter disease is usually diagnosed by clinical examination. X-rays or other imaging studies are rarely needed for diagnosis unless there are some atypical findings or a history of a sudden, severe onset of the pain in a previously pain-free joint, which might suggest an avulsion injury.
The condition is benign and self-limiting. The pain usually goes away on its own once the growth plate closes between the age of 14 – 18 years but symptoms can last between 6 – 18 months and wax and wane during this period. Despite it being a very common condition there are no studies to determine the best form of treatment. Complete cessation of activity is not recommended and most adolescents are able to continue some type of activity and tolerate some pain during play provided it goes away completely within 24 hours and they don’t need anti-inflammatories or analgesia to enable them to stay active. An individualised rehabilitation program can help limit the pain and reduce secondary complications as well as addressing any predisposing factors.
A traction apophysitis of the heel where the Achilles tendon inserts into the calcaneus (heel bone) at the back of the foot.
This is the second most common traction apophysitis and occurs in children aged 9 – 13. It occurs 1-2 years earlier on average in girls due to their earlier growth spurt but is 3 times more common in boys compared to girls. Pain due to Sever disease is more common during periods of rapid growth where there is increased metabolic activity at the apophysis. It is more common in sports that involve running or jumping.
Sever disease causes activity related heel pain that seems to have no precipitating cause. 60% of the time it occurs in both heels. The pain may be worse when wearing shoes with thin soles, no heel cushioning or cleats that centre the force of impact on the heel. There might be localised swelling and tenderness of the heel, tight calf muscles, restricted ankle range of motion and pain that gets worse with activity and improves with rest.
It is usually diagnosed by clinical examination. X-rays or other imaging studies are rarely needed for diagnosis unless there are some atypical findings such as pain at night or a history of a sudden, severe onset of the pain.
The condition is benign and self-limiting. The pain usually goes away on its own within 6 to 12 months but can last up to 2 years. It does not usually continue beyond the age of 15 when the growth plate fuses. Activity modification may be needed to control symptoms but complete cessation of activity is not recommended. Running and jumping may need to be limited initially but adolescents can usually continue some type of activity and tolerate some pain provided it goes away completely within 24 hours and they don’t need anti-inflammatories or analgesia to enable them to stay active. Heel raises in shoes sometimes give short-term symptomatic relief. An individualised rehabilitation program focusing on calf stretches and strengthening can help limit the pain and addressing any predisposing factors can help reduce secondary complications.
If your child has joint pain that is limiting their activity, a consultation at Shire Sports Medicine can be beneficial to get an accurate diagnosis, to help guide management and to ensure the prevention of further complications.