The sound of a baby’s shoulder popping or clicking when being picked up can cause immediate alarm for any parent. This audible phenomenon is surprisingly common, yet it understandably raises concerns about potential injury or underlying weakness. While often harmless, these noises exist on a spectrum that ranges from a completely normal physiological occurrence to a sign of a minor structural issue. Understanding the difference between a benign joint sound and a symptom requiring medical attention is essential for a child’s well-being.
Why Infant Joints Make Benign Sounds
The most frequent reason for joint noise is entirely non-pathological, meaning it is not caused by disease or injury. Babies naturally possess a high degree of joint laxity, which refers to the looseness of the ligaments and soft tissues surrounding the joint. This flexibility is due to the presence of more elastin and less mature collagen in their connective tissues, allowing tendons to briefly glide over bony prominences during movement, creating a clicking sound.
Another common cause is a process known as joint cavitation, which involves the release of gas within the joint space. Synovial fluid, the body’s natural joint lubricant, contains dissolved gases like oxygen and nitrogen. When the joint surfaces are quickly separated, such as during a sudden movement or stretch, a temporary vacuum forms, causing these dissolved gases to rapidly come out of solution. This rapid formation of a gas cavity creates the distinct popping sound.
These benign sounds are typically painless and do not cause the infant any distress. The joint noise often decreases as the child grows, as their ligaments tighten and their musculature develops to better stabilize the joints. If the pop is an isolated event and your baby remains calm, it is likely a normal mechanical occurrence.
Potential Injuries Associated with Shoulder Popping
When the popping sound is accompanied by signs of pain, it can indicate a specific structural problem in the shoulder or collarbone area. The most common injury associated with an audible pop during handling is a clavicle fracture, or broken collarbone. This injury is frequently sustained during a difficult birth, such as a shoulder dystocia delivery, and may not be immediately diagnosed.
A fracture that occurred at birth can sometimes present later as a click or pop when the baby is lifted under the arms, which puts pressure on the collarbone. Furthermore, as the bone begins to heal, a firm, bony lump, called a callus, forms at the fracture site. This callus can sometimes be felt or heard clicking as the arm moves.
Another potential cause, though less frequent in infants than in older children, is shoulder subluxation—a partial dislocation of the upper arm bone (humerus) from the shoulder socket. This can happen if an infant is forcefully pulled or lifted by a single arm, causing the head of the humerus to momentarily slip out and then pop back into position.
Recognizing Symptoms That Require Medical Attention
If the popping sound is linked to an underlying injury, the baby will exhibit specific signs of discomfort and limited function. The most telling symptom is sustained crying or fussiness immediately following the sound, especially if pain is evident when you attempt to move the affected arm. A baby with a painful shoulder injury will often refuse to move the arm, holding it still against their body, a phenomenon known as pseudoparalysis.
Parents should carefully inspect the area around the collarbone and shoulder for visual signs of trauma. This includes noticeable swelling, bruising, or a deformity where the bone appears uneven or the shoulder looks lower than the other.
In rare cases, a birth-related clavicle fracture can be associated with a brachial plexus injury, a collection of nerves that controls the arm. If injured, this may cause the entire arm to hang limp and unresponsive. These observable symptoms are red flags that require prompt medical consultation to confirm a diagnosis with imaging, such as an X-ray.
Techniques for Safe Infant Handling
Preventing unnecessary strain on your baby’s joints begins with employing proper lifting and carrying techniques. When picking up your infant, always ensure you are supporting both their head and neck, as their neck muscles are weak and their head is disproportionately large.
The safest way to lift a small infant is by using both hands: placing one hand under the baby’s bottom and the other supporting their neck and upper back. Avoid lifting an infant by pulling on their hands, wrists, or armpits alone, as this puts direct, shearing stress on the shoulder and elbow joints.
Keep the baby close to your body’s center of gravity when lifting to minimize sudden joint distraction forces. When lifting from a low surface, such as a crib or the floor, bend at your knees and hips using a squatting or lunging motion, rather than bending at the waist.