By Tom Keppeler, Shoulder1 Staff
In the mid-1990s, scientists in Sweden developed a procedure to restore the cartilage in worn-out knees. The procedure, known as autologous chondrocyte implantation (ACI), allows a surgeon to harvest cartilage cells from a patient's body (tissue from a patient's own body is known as "autologous," and "condrocytes" are cartilage cells), grow them in a lab, and then implant them inside the patient's knee to provide the cushion and fluidity that only the body's own cartilage can provide. Since its inception, more than 4,000 patients have undergone the procedure, saving their knees from further degeneration and an inevitable total joint replacement.
Now, scientists are trying to treat patients with similar problems in their shoulders with this revolutionary treatment. By adapting the procedure to the shoulder joint, they hope, they can restore the cartilage that surrounds the joint, decreasing pain and increasing mobility.
The procedure consists of four steps. First, the patient is examined to ensure that they are a prime candidate for ACI: someone with a tear in their articular cartilage, which surrounds the joint, who does not plan to be overly athletic after the operation. Next, the patient undergoes an arthroscopic procedure to remove a raisin-sized chunk of cartilage from his or her knee. The cartilage is then shipped to a laboratory, where it is cultured and replicates many times over, producing millions of smooth, healthy cartilage cells. Between 10 and 60 days after the original harvesting, the surgeon covers the tear in the cartilage with periosteum, the dense membrane that covers bones. The new cells are then injected under the periosteum patch to eventually grow together with the existing cartilage in the joint.
Dr. Stephen Brenneke, an orthopedic surgeon for Providence Health System in Portland, Oregon, performed the fourth shoulder ACI in mid-October, and says the patient, a woman in her 30s who had undergone four previous operations on her shoulder, is recovering well. "We took her sutures out today," Brenneke told Shoulder1 in an interview October 25. "She says the pain that she had pre-operatively is mostly gone." Dr. Lars Petersen, the Swedish scientist who popularized ACI worldwide, oversaw the procedure. Guidance from Petersen, who has performed upwards of 700 ACI procedures since 1996, ensured the success of the operation, Brenneke says.
Scientists have great strides to make before ACI, which is marketed by Genzyme Biosurgery as Carticel, hits the mainstream of shoulder repair. Repairing the cartilage in shoulders presents a greater degree of difficulty than in the knee, because the cartilage is thinner, and harder to attach the periosteum to. "It was a little more tedious [than in a knee] to get the needle through the cartilage and to hold," Brenneke says. "Cartilage is almost like Jell-O. Imagine stitching into Jell-O and getting it to hold, it's a little bit tricky."
Once tested and approved both by clinical studies and the Food and Drug Administration, the procedure may offer little hope for patients with lesions, or tears, in the cartilage of their shoulders. If the indications for knee Carticel are applied to shoulders, patients must have otherwise healthy cartilage. Current science only allows for a total joint replacement for these patients.
Should Carticel be approved for use in shoulders, Brenneke says, that will change. "I don't think I would ever be as foolish as to say that these patients are going to go back and lead a rigorous, demanding life with that joint," Brenneke said. However, the procedure may skirt the bulkiness of a joint replacement and restore some of the quality of life they enjoyed prior to their affliction.
Brenneke says that he would gladly perform another shoulder ACI, should he come across a patient with a similar pathology. The procedure, which has also recently been performed on ankles, may provide one more weapon in the fight against creaky, painful shoulders.