Dear Doctors: I tripped on a tree root and almost did a face-plant. I landed on my hands with my arms stretched out, and now my right shoulder has started aching. My boyfriend thinks it’s a rotator cuff injury. I’ve only heard of that in baseball players. What is the rotator cuff? What is the treatment?

Dear Reader: Your rotator cuff is the group of muscles and tendons that help anchor the bone of the upper arm, known as the humerus, within the shoulder joint. This is a ball-and-socket joint, the architecture of which allows the arm to have a wide range of motion. Working together, the muscles and connective tissues of the rotator cuff hold the rounded end of the humerus -- that’s the ball -- in place as it moves within the shallow cup of the shoulder blade “socket.” They also contribute to the strength and stability needed to lift and rotate your arm.

Injuries to the rotator cuff can occur in a fall onto an outstretched arm, as happened in your case. This can damage not only the tendons, but also may bruise or tear the muscle. The area can also sustain harm due to repetitive overhead arm motions, which is why the injury is often seen in baseball and tennis players, swimmers and golfers. Professions such as house painting or construction work, and improper technique when lifting heavy weights, also put people at increased risk.

The most common symptom is a dull ache deep within the shoulder joint. This can be accompanied by weakness in the muscles of the arm and a reduced range of motion. Lifting a weight or rotating the arm can intensify discomfort. Pressure on the shoulder, as when sleeping on your side, may be painful. In some cases, damage to the connective tissues in the shoulder joint can create a sensation of friction during motion or cause a popping or crackling sound.

Diagnosis begins with a close examination of the shoulder joint to assess pain and identify areas of weakness or impaired motion. Imaging tests, such as an MRI or an ultrasound, may be recommended.

Treatment depends on the scope of the damage. In minor injuries, the connective tissues may be irritated or inflamed but are not torn or severed. In those cases, the person will be asked to rest and limit activities that involve the affected shoulder.

Nonsteroidal anti-inflammatories (such as ibuprofen) may be used to manage pain and swelling. Stretching and strengthening exercises can be helpful, as can ultrasound therapy and physical therapy. In some cases, corticosteroid injections may be used to manage inflammation. In more serious injuries, the connective tissues become frayed or torn or can completely detach from the bone. Depending on the extent and severity of the damage, surgery may be necessary.

After a fall, and with the onset of your symptoms, it’s a good idea to have your shoulder evaluated by your health care provider. Treatment can improve a rotator cuff injury. But when ignored, it is easy for these types of injuries to worsen.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o UCLA Health Sciences Media Relations, 10960 Wilshire Blvd., Suite 1955, Los Angeles, CA, 90024. Owing to the volume of mail, personal replies cannot be provided.)

Hello, dear readers, and welcome back to our monthly letters column. You have been keeping our inboxes full, so we’ll dive right in.

-- A column that explored the potential benefits of a weighted blanket continues to draw a lot of interest. This led a reader to ask about the guidelines regarding the weight of these blankets. “I know that the recommended weight is 10% of your body weight, but I wonder if it is OK to do more?” she asked. “I currently use two weighted blankets, and lately they don't feel heavy enough.” Weighted blankets contain materials such as tiny beads or pellets to add heft. Research suggests the gentle and constant pressure of these products can aid in relaxation, ease anxiety and improve sleep. You are correct that guidelines for adults suggest a maximum of 10% to 12% of a person’s body weight. Some people, like yourself, do prefer blankets that are on the heavier end of the scale.

When choosing your preferred weight range, be sure your blanket does not hinder movement or breathing in any way, doesn’t cause overheating and can be easily and quickly removed. It is important to note that weighted blankets are not recommended for infants or young children, and they should not be used by anyone with sleep apnea, Type 2 diabetes or any respiratory or circulatory issues.

-- We recently wrote about an intriguing study in which nighttime exposure to a changing palette of scents via a diffuser had a positive effect on cognition and memory. We heard from a reader wanting more information. “Which scent diffusers and essential oils were used in the study?” she asked. Over the course of the six-month study, the diffusers emitted a rotation of seven different scents: rose, orange, eucalyptus, lemon, peppermint, rosemary and lavender. The scents were released at intervals, for a total of two hours throughout the night. The study did not specify the type of diffusers that were used, nor a brand of scent.

-- We heard from a reader who worries that although she puts her infant daughter to sleep on her back, as recommended, the child has begun to flip over. “She is 7 months old and has been doing this for a few weeks. Is there anything we can do to keep her on her back?” she wrote. “I know that’s the position that is safest to prevent SIDS, but we keep finding her on her stomach.” You are correct that placing an infant on their back to sleep greatly reduces the risk of SIDS, or sudden infant death syndrome. The reassuring news is that once your baby is strong enough and coordinated enough to turn over by themselves, their brain has also reached an important developmental milestone. It is now able to alert the infant to breathing problems, which they can correct. Babies begin to be able to roll over by themselves at about 6 or 7 months of age. Your daughter is right on track.

Thank you, as always, for sharing your thoughts, ideas and concerns. We love hearing from you and look forward to your letters.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o UCLA Health Sciences Media Relations, 10960 Wilshire Blvd., Suite 1955, Los Angeles, CA, 90024. Owing to the volume of mail, personal replies cannot be provided.)

Dear Doctors: I heard there will be a saliva test to see who has a high risk of getting prostate cancer. I don’t see how saliva would have anything to do with your prostate gland. How does the test work, and how can I get access to it?

Dear Reader: A test that analyzes bodily fluids is known as a liquid biopsy. The most common are the blood and urine tests many of us are familiar with. Recently, though, thanks to advances in genetic research and medical technology, saliva is being explored as a diagnostic tool. The fluid that we produce by the pint each day and rarely think about is 98% water. However, that remaining 2% turns out to be a trove of valuable information.

Saliva contains proteins, electrolytes, hormones, peptides, free fatty acids, mucus, antibacterial compounds, RNA fragments and nucleic acids that come from throughout the body. Researchers are exploring how these can be used as biomarkers to pinpoint the presence of a disease or condition. Existing saliva tests screen for HIV, Cushing’s disease, hepatitis C and even pregnancy. Salivary analysis can also help diagnose certain oral diseases. Researchers are now exploring saliva as a tool in identifying Huntington’s disease, Parkinson’s disease, Alzheimer’s disease, COVID-19 and a range of cancers.

You are correct that a saliva test that flags a high risk of prostate cancer is under development. Unlike a blood test, a saliva test can be completed at home. The person spits into a specially prepared tube, then mails the sample to a lab for analysis. The prostate cancer test you asked about works by identifying genetic variants that are known to signal a significant risk of developing the disease.

Initial research suggests this saliva test can be more accurate at identifying men who are at high risk of cancer than the prostate-specific antigen blood test. Also known as the PSA test, it measures blood levels of a protein that is produced by cancer cells. However, that protein is also produced by noncancerous cells. Several factors unrelated to cancer can lead to elevated PSA levels. This includes having an enlarged prostate, vigorous exercise, having a urinary tract infection, recent ejaculation, certain medications and being older. As a result, PSA tests can yield false positives, which can lead to unnecessary medical interventions and procedures.

In the most recent clinical trial of the saliva test, researchers analyzed samples from 6,000 men between 55 and 69 years old -- the age at which prostate cancer risk begins to rise. Those who tested positive for the genetic variants repeated the saliva test, and also underwent a PSA blood test. When the results were compared, the saliva test identified a higher proportion of aggressive cancers than the PSA test. It also yielded fewer false positives.

At this time, the test you are asking about is still in the research stage and is not yet in use. However, clinical trial results have been promising, and the hope is the test will become available soon.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o UCLA Health Sciences Media Relations, 10960 Wilshire Blvd., Suite 1955, Los Angeles, CA, 90024. Owing to the volume of mail, personal replies cannot be provided.)