Pelvic avulsion fracture

OVERVIEW

What is an avulsion fracture of the pelvis?

An avulsion fracture of the pelvis is a special type of fracture, often caused by sports injuries. It occurs when a strong muscle contraction tears away part or all of the bony protrusion connected to the tendon.

Are pelvic avulsion fractures common?

Pelvic avulsion fractures are relatively rare. Most cases occur during sports activities, accounting for 4% of all pelvic fractures and only 1.4% of fractures in young athletes. Due to their low incidence, they are often misdiagnosed as muscle or tendon tears or tendonitis ^[1].

What are the symptoms of a pelvic avulsion fracture?

Pelvic avulsion fractures include fractures of the anterior superior iliac spine (ASIS), anterior inferior iliac spine (AIIS), and ischial tuberosity.

ASIS and AIIS avulsion fractures: Due to their close proximity, the symptoms are similar. Both can cause pain, tenderness, and swelling in the front of the hip and groin on the affected side, with bruising appearing days later. Severe displacement may lead to lateral femoral cutaneous nerve entrapment syndrome, manifesting as sensory impairment on the outer thigh. Examination may reveal abnormal movement of the fracture fragment, crepitus, and pain during hip flexion and knee extension.
Ischial tuberosity avulsion fracture: Sudden pain in the buttocks and swelling near the upper thigh after injury, making walking difficult. Sitting is more painful than standing, with limited knee extension and hip flexion. Examination may detect abnormal movement of the fracture fragment, crepitus, and increased pain at the ischial tuberosity (upper thigh) when resisting knee flexion.

CAUSES

How Does a Pelvic Avulsion Fracture Occur?

Pelvic avulsion fractures primarily involve the following risk factors ^[2]:

Age: Adolescents are prone to avulsion fractures. The ossification centers of the pelvic apophyses appear during puberty, and during this period, the epiphyses are weak in resisting muscle stress, making avulsion fractures more likely to occur.
High-intensity sports: Activities such as sprinting, long jump, and hurdling require explosive muscle contractions in the thighs. When sudden traction forces act on the apophyses, avulsion fractures are more likely to occur.
Inadequate warm-up before exercise: Insufficient warm-up can lead to poor muscle flexibility and joint mobility during exercise, increasing the risk of injury.
Poor mastery of specialized movements or unrefined techniques.

Who Is Most Susceptible to Pelvic Avulsion Fractures?

They commonly occur in adolescent male athletes (average age of onset is 14.4 years, with males being more affected ^[3]). High-intensity sports such as sprinting, hurdling, long jump, soccer, and basketball are frequently associated with these injuries.

Due to the fragility of adolescent bones, when muscles exert strong force, they can pull the bony prominences away from the pelvis, resulting in an avulsion fracture.

EVALUATION

How to Diagnose Pelvic Avulsion Fracture?

In older children or adolescents who experience sudden severe pelvic pain during intense physical activity, especially sprinting, doctors may observe hip swelling and significant localized tenderness during physical examination. Even if the patient can walk independently with or without a limp, the possibility of a pelvic avulsion fracture should still be considered ^[4].

Is Imaging Necessary for Pelvic Avulsion Fracture?

Yes.

Anteroposterior and oblique pelvic X-rays can confirm the diagnosis, while pelvic CT and three-dimensional imaging can determine the size of the bone fragment, the direction of displacement, and the extent of injury, aiding in treatment planning.

PREVENTION

Which department should I visit for a pelvic avulsion fracture?

Sports medicine, rehabilitation medicine, or orthopedics department in a hospital;
Sports medicine clinics or rehabilitation centers.

How is a pelvic avulsion fracture treated?

The treatment method depends on the degree of avulsion, the patient's age, and their athletic demands.

For younger patients with bone fragment displacement ≤ 2 cm, conservative treatment is the first choice. Most avulsion fractures can be successfully treated conservatively, with minimal impact on function after healing and no need for surgery. However, conservative treatment requires a long period of bed rest and delayed functional exercise, which may affect appearance.
For bone fragment displacement > 2 cm, conservative treatment may lead to nonunion or re-avulsion, causing inconvenience in daily life. Therefore, surgical treatment is recommended for patients with displacement > 2 cm. Surgery is the preferred option for competitive athletes and patients with significant fragment displacement, typically performed 5–7 days after the injury.

Can I apply ice for a pelvic avulsion fracture?

Yes.

Ice should be applied immediately after the injury. For the first two to three days, ice can be used whenever pain is felt to reduce pain and inflammation caused by muscle strain.

Method: Place an ice pack (plastic bag) with an ice-water mixture on the affected area, with a thin cloth between the ice and skin to prevent frostbite. Apply ice for 15–20 minutes at a time, every 2 hours, 4–5 times a day.

Does a pelvic avulsion fracture require a cast?

It depends.

Follow your doctor's advice. Generally, if the bone fragment displacement is less than 1 cm, a cast is not needed. If the displacement is 1–2 cm, a cast may be required ^[5].

Do I need crutches for a pelvic avulsion fracture?

Yes.

Weight-bearing must be restricted until the fracture heals. Patients should use underarm crutches for walking. Premature or excessive weight-bearing may cause displacement or nonunion of the fracture. Follow your doctor's instructions strictly and progress gradually: non-weight-bearing with two crutches → partial weight-bearing with two crutches → partial weight-bearing with one crutch → no crutches. Initially, walking with crutches should be limited to 5–10 minutes, 1–3 times a day, gradually increasing duration and frequency. Walking exercises include:

Non-weight-bearing walking with two crutches
Partial weight-bearing walking with two crutches
Partial weight-bearing walking with one crutch

How long until I can walk normally after a pelvic avulsion fracture?

Generally, patients can walk without crutches 5–6 weeks after the injury.

As per medical advice, weight-bearing is usually prohibited for 3–4 weeks. During this time, the affected leg must not bear weight, and a wheelchair or crutches are needed for mobility.

After cast removal or when weight-bearing is allowed, partial weight-bearing with crutches can begin. Based on clinical symptoms and fracture healing, patients can gradually transition to full weight-bearing, usually achieving normal walking within 5–6 weeks ^[5].

How to perform rehabilitation exercises for a pelvic avulsion fracture?

Rehabilitation exercises are crucial for fracture healing and functional recovery. With a doctor's approval, active training can typically begin 3–4 weeks post-injury to gradually restore hip joint mobility and leg strength ^[6]. Recommended home exercises include (individualized guidance from a physiotherapist is advised):

Range-of-motion exercises (can also serve as daily flexibility training post-recovery):

Iliopsoas stretch
Quadriceps stretch
Hamstring stretch
Adductor stretch
Tensor fasciae latae stretch
Gluteus maximus stretch

Strength-building exercises include:

Glute bridge
Clamshell
Seated knee extension
Prone hamstring curl
Squats
Crab walk

DIET & LIFESTYLE

How to Adjust Crutches for Pelvic Avulsion Fracture?

Crutches can limit weight-bearing and assist with walking, but improper height adjustment or incorrect usage may compress nerves under the armpit, causing damage. The patient should stand with both upper limbs relaxed at the sides, elbows bent at 20–25 degrees, and adjust the crutch's armpit rest and handle height in this position. The height adjustment method is as follows:

Armpit Rest: Place the crutch tip 15 cm in front and 15 cm to the side of the foot, leaving 2–3 finger widths (about 5 cm) between the armpit rest and the armpit.
Handle: Adjust to the height of the radial styloid (approximately at the wrist).

What Precautions Should Be Taken During Casting for Pelvic Avulsion Fracture?

The cast must not get wet. During bathing, use waterproof plastic film to cover and seal it, keeping the cast as far away from the shower area as possible. If water enters, dry it immediately with a cold blow dryer.

Seek medical attention if any of the following occurs: swollen, tingling, or numb toes; pale or purple skin; loose or detached cast; or skin ulcers under the cast.

During casting, unfixed body parts should remain active. Toes on the affected side must be exercised to prevent joint stiffness and muscle atrophy.

Is Bed Rest Necessary for Pelvic Avulsion Fracture?

Yes, bed rest is required.

Once diagnosed with a pelvic avulsion fracture, whether treated conservatively or surgically, the patient must rest in bed for a period. Since the pelvis bears weight, any weight-bearing activities (walking, running, jumping) can hinder healing.

PREVENTION

What are the preventive measures for avulsion fractures?

Scientifically plan training programs in a progressive manner. Adolescents should master movement techniques thoroughly and correct improper postures promptly during sports activities.

Enhancing lower limb muscle flexibility (refer to rehabilitation training methods for pelvic avulsion fractures) and eccentric strength training can reduce the risk of avulsion fractures. Here are some exercises to improve lower limb movement patterns and eccentric strength:

Single-leg lunge squat
Single-leg squat
Nordic hamstring curl

Proper warm-up before exercise is essential. In addition to traditional cardio preparations like running or cycling, include dynamic stretching, muscle activation, and sport-specific movement drills. Here are some warm-up exercises to improve hip mobility and enhance hip/core stability:

World's greatest stretch
Lateral lunge
Monster walk