Shawn Ryan's friends know the combination: Lie him down on his back and move his arm up slowly toward his head until his shoulder falls back into place.
"It's a quick shock every time - and it hurts," said Ryan, 24, whose right shoulder would dislocate so often many of his buddies learned what to do. "But by now, I'm used to the pain."
The Perkasie native had his first shoulder-stabilization surgery in 2011 after he was injured playing lacrosse. No sooner was he cleared to go back to sports in 2012, he went out for flag football on Temple University's club team.
In his first game, he hit the ground and felt a familiar pain in his shoulder.
Since then, Ryan estimates he's had 50 dislocations, requiring four emergency room visits just last year.
His case is extreme, but G. Russell Huffman, who directs the shoulder and elbow fellowship program at Penn Medicine, says chronic shoulder dislocation happens more often than you might think.
The shoulder is the most flexible joint in the body. Like the hip, it's a ball-and-socket arrangement. But unlike the load-bearing hip, the shoulder socket is so shallow the head of the upper-arm bone barely sits in it, making it about as stable under stress as a golf ball on a tee.
The joint can be dislocated toward the front or the back. Problems typically occur during a traumatic event such as a fall or a direct blow to the shoulder.
And once you dislocate a shoulder, you're likely to do it again if you don't heal properly.
"For the first seven weeks after a dislocation, I tell patients to keep their hands in a position where they can see them at all times," Huffman said. "This creates a safe zone so they're not in a vulnerable position to dislocate again."
If there's no bone loss detected after the initial dislocation, a minimally invasive procedure to repair the labrum, the rim of cartilage that lines and reinforces the joint, is often successful. It's the procedure Ryan had in 2011.
"But he's dislocated his shoulder many times since the first arthroscopic repair and a common reason for the failure of that surgery is unrecognized bone loss," Huffman said. "If there's bone missing in the socket, you can see failure rates as high as 20 to 25 percent."
Every time the shoulder dislocates, there likely is some bone loss. Going back to the golf analogy, Huffman said, "If you remove part of the tee, it's almost impossible to keep the ball on it; that's what we call glenoid bone deficiency."
So Ryan needed what's known as a Latarjet procedure to reconstruct the lost bone. It was scheduled in early 2015, during his senior year at Temple.
But shortly before his surgery, he was diagnosed with stage four acute lymphoblastic leukemia, a cancer of the bone marrow. The cancer didn't contribute to the bone loss, Huffman said.
However, cancer treatment meant the shoulder procedure had to be postponed. For the next eight months, Ryan received chemotherapy up to four times a week.
"Every round of cancer treatment can result in a drop in the blood counts that would help in the healing process and help to prevent infection," said Selina M. Luger, director of the Leukemia Program in the Abramson Cancer Center and Ryan's oncologist.
When his treatments were dialed back to once a month, he was ready for surgery to stabilize his shoulder in late February.
"At this point, Shawn's blood counts are at a safe enough level to have the procedure and we can also time the procedure so that he can continue his leukemia therapy without interruption," Luger said.
Huffman performs about 20 Latarjet procedures a year, most commonly on younger patients who have had multiple dislocations or a failed surgery. The surgery stops the shoulder from dislocating for nearly 95 percent of patients, the surgeon said.
The procedure takes a section of the patient's own bone to create a "block" to prevent future dislocation. Huffman uses a piece of bone from the coracoid process, at the edge of the shoulder blade. The other common place to harvest bone from is the hip. But staying in the shoulder area meant just one incision, and less risk of infection for Ryan, Huffman said.
Huffman made a five-centimeter incision over the front part of the shoulder and used retractors to expose the coracoid process.
With a small saw, he cut away two to three centimeters of bone, carefully leaving it attached via the conjoint tendon, so the bone's blood supply was maintained.
Two holes were drilled into the bone piece for screws to fit into later. Next, Huffman worked to access the shoulder socket.
Using scissors to split the muscle that runs across the front of the shoulder, Huffman made the socket visible. The bone piece and tendon were passed a few inches from their original location, through the muscle. Two metal screws set it in place on the front rim of the socket, called the glenoid.
"By placing the coracoid process directly on the glenoid, we're able to do bone-to-bone healing, which is the most reliable and fastest way to heal," Huffman said.
The result is a soft tissue "sling" formed by the conjoint tendon and the subscapularis tendon and anchored by the "bone block" formed by the coracoid process to stabilize the shoulder.
Typically, Huffman would close then.
But in this case, he needed to repair damage to Ryan's shoulder caused by the repeated dislocations. Because the humeral head is fairly soft, it can acquire a fracture called a Hills-Sachs lesion in the course of slipping out of the socket.
"A good analogy would be a Styrofoam ball that gets thrown into something hard and the indentation stays there," Huffman said.
The surgeon took some of the surrounding tissue of the rotator cuff and stitched it into the indentation, preventing that area from damaging the cartilage of the shoulder socket.
Ryan will be in a sling for the first four to eight weeks but he started to stretch his shoulder - gently - the day after the surgery.
After eight weeks, he'll be able to return to some light lifting, and, by three months, patients are generally cleared to go back to their previous activities, including impact sports.
"As long as the bone has healed in a good position and he has all of his motion back, he's cleared," Huffman said.
The hardest part of the rehabilitation process for patients who suffer from chronic dislocation is finding the confidence to put their arm behind their head without having to worry about something going wrong.
For Ryan, his next big goal has nothing to do with sports or shoulders. Instead, he is looking for ways to help other patients diagnosed with leukemia.
"I got my psychology degree at Temple and a lot of my doctors told me I should use it to help others in my situation," he said. "So now I'm trying to join a yearlong volunteer program for kids with cancer at Children's Hospital of Philadelphia."