During the AAOS 2019 Annual Meeting, Robert T. Trousdale, MD, professor of orthopaedics at Mayo Clinic in Rochester, Minn., discussed diagnosis, management, treatment, and prevention of iliopsoas impingement after total hip arthroplasty (THA).

The incidence of iliopsoas impingement is about 4.3 percent, Dr. Trousdale said. And despite increased awareness of the problem, it remains commonly missed among THA patients. Patients frequently complain of pain in the groin, which may radiate to the thigh and is not always constant. Hip flexion activities—such as walking up and down stairs and getting in and out of a car—often intensify the pain. It is diagnosed through a physical examination that includes a psoas stretch test.

Several factors—notably pertaining to the anterior acetabular rim—could cause iliopsoas impingement. “If you retrovert the socket, if you lateralize the socket, if you anteriorize the socket,” iliopsoas impingement could occur, he said. “If you lengthen the leg tremendously, then you have psoas tension and pain problems. [If you] increase the patient’s offset dramatically, it’ll stretch the tendon.” Extra large femoral heads also can lead to iliopsoas impingement.

Other possible causes of groin pain must be ruled out, including:

• loose cup
• infection
• back issues
• pelvic issues
• metal issues
• loose stem

The diagnosis can be confirmed with CT-guided scan or ultrasound-guided iliopsoas sheath injection, Dr. Trousdale said, adding it is “very technique-dependent on who does this.”

Once diagnosis is confirmed, patients can be managed operatively or nonoperatively. Nonoperative management may include psoas injections, nonsteroidal anti-inflammatory drugs, and physical therapy. “If that fails and the pain is bad enough, then you have to discuss either tenotomy or cup revision. … There’s really no consensus on those treatment options,” he added. “Previous recommendations are based on small case reports or very small series” with short follow-up, said Dr. Trousdale.

“A few years ago, we looked up a relatively large series of patients that had iliopsoas tendonitis [at our institution],” Dr. Trousdale said. The retrospective review included 49 patients treated between 1996 and 2013; patients were excluded if they had sepsis, revision THA, or metal-on-metal bearing. Twenty patients received nonoperative treatment, and 29 underwent surgery—either acetabular revision (n = 21) or iliopsoas tenotomy (n = 8). The researchers used direct lateral radiographs to measure anterior-inferior acetabular component prominence.

Among the nonoperative patients, about half achieved resolution of groin pain. In the acetabular revision group, among patients with cup prominence ≥ 8 mm (n = 13), 92 percent achieved resolution of groin pain compared to half of patients (n = 4/8) with cup prominence < 8 mm. No complications or repeat revisions took place. “In the tenotomy group, if the cup prominence was more than 8 mm, a third [of patients] got better; if cup prominence was < 8 mm, 100 percent got better [after treatment],” Dr. Trousdale shared.

“What is the surgical decision-making process? If nonoperative [treatment has] failed and the pain is bad enough, evaluate the direct lateral radiograph for acetabular component prominence,” Dr. Trousdale said. “In cases where prominence is ≥ 8 mm, acetabular revision and iliopsoas tenotomy should be considered, and if prominence is < 8 mm, consider iliopsoas tenotomy.

“In conclusion, nonoperative management helps up to 50 percent of the patients that seem to have this problem. Operative treatment seemed to improve the groin pain. If the cup prominence is ≥ 8 mm, you can consider acetabular revision as more of a reliable operation” compared to tenotomy alone, Dr. Trousdale said. “To prevent the problem, don’t place the acetabular component proud … when you do the surgery; make sure it’s down below the bone. Don’t use very large heads, above 40—that’s probably a risk factor. And don’t dramatically increase the offset of your femoral stem.”

Kaitlyn D’Onofrio is the associate editor for AAOS Now. She can be reached at kdonofrio@aaos.org.