Tips offered for diagnosis, FAI, PAO

Preserving the hip joint to delay arthroplasty has become more common, and several surgical procedures have demonstrated pain relief and improved function. A panel of surgeons shared their perspectives and expertise on hip joint preservation at the 2011 AAOS Annual Meeting in San Diego.

It starts with the diagnosis
Successful treatment depends on an accurate diagnosis, but little consensus exists on how to conduct an examination, said Bryan T. Kelly, MD, of the Hospital for Special Surgery. Noting that the origin of hip pain can be difficult to identify, he said the clinician must first distinguish between intra- and extra-articular pain (Table 1).

The history should note the mechanism and duration of pain; aggravating activities; clicking, catching, and locking; previous surgery; and physical therapy. Passive range of motion in the standard hip categories should be checked.

“Internal rotation at 90 degrees of flexion tells us a lot—not only about the mechanics of the joint but also about its functional capacity,” Dr. Kelly said. “Most activities, whether for athletics or activities of daily living, require a certain degree of rotation. Without that, the joint will sustain a direct impaction injury, or some kind of secondary compensatory problem will develop.”

The impingement test is used to identify areas of contact or motion-induced conflict between the anterior aspect of the hip and the socket; this occurs with flexion, adduction, and internal rotation. But impingement also occurs in other sites, and straight flexion is probably the second most common provocative position for pain.

The exam should also test for trochanteric pain, instability, posterior impingement, strength, and palpation pain, as well as measure the peritrochanteric space.

The comprehensive examination looks at five points for the five body positions of standing, sitting, supine, lateral, and prone. For example, the standing examination incorporates general stature, gait, spinal and pelvic alignment, and the Trendelenburg test; the supine examination includes passive range of motion, strength, pain with palpation, groin injury, and special tests. Similar measures are taken for the sitting, lateral, and prone positions. Diagnostic tests should be ordered as appropriate.

“The location and quality of the pain should correspond to the mechanics of the joint and primary and secondary injury patterns,” Dr. Kelly said. “If they do, then correcting the mechanical problem and addressing the subsequent injuries should lead to a good outcome.”

FAI tips
Michael Leunig, MD, reviewed the primary considerations in surgical dislocation to treat femoroacetabular impingement (FAI) and strategies to avoid or manage common complications.

Surgical dislocation, which was introduced around 1990, enables the performance of safe intracapsular procedures within the hip and the identification of FAI. Although less invasive approaches such as arthroscopy have partially replaced surgical dislocation, this open procedure remains useful for addressing complex deformities, Dr. Leunig said.

He identified the following absolute indications for surgical dislocation:

• global overcoverage
• severe retroversion
• posterolateral cam FAI (which cannot be reached by an anterior approach)
• a combined intra- and extra-articular impingement (because an intracapsular procedure is not sufficient)
• the need for intra-articular procedures

Relative indications that may be managed with less invasive techniques include anterior-superior cam deformities, laxity, and mild osteoarthritis. Contraindications include inability to identify the presence of an anatomic deformity, nonmechanical disease, and high-grade osteoarthritis.

During surgery, “respecting the medial femoral circumflex artery (MFCA) is key to a safe dislocation procedure,” said Dr. Leunig, because this artery is the primary source of vascularity to the femoral head. He noted that the obturator externus muscle protects the MFCA from overstretching. “So as long as this muscle is intact, problems with perfusion will not occur.”

He also provided some strategies for dealing with potential problems encountered during hip surgery (Table 2).

About 6 percent of patients will have adhesions. Dr. Leunig recommended starting continuous passive motion shortly after surgery, no later than the day after, to prevent adhesions from developing. Arthroscopy may be necessary if decreased range of motion is present.

PAO pointers
Periacetabular osteotomy (PAO) can be used to manage acetabular dysplasia, but the procedure is relatively complex, with the potential for major complications and treatment failures, which have been the source of some criticism.

John C. Clohisy, MD, said that PAO has gone through a “learning curve experience.” In a 2009 review of 600 PAO cases, the major complication rate varied from 6 to 36 percent. A more recent analysis, however, found a complication rate of 3 percent, and all the complications were treated and resolved without long-term disability or morbidity. “From the learning curve perspective, the PAO is quite safe,” Dr. Clohisy said.

Indications for PAO include a healthy, well-conditioned patient younger than 40 years, with symptomatic acetabular dysplasia, a congruent joint that has “healthy” articular cartilage without major joint degeneration, and good hip range of motion.

Potential negative predictive factors include body mass index greater than 30, age older than 40 years, certain comorbidities, previous reconstructive surgery, suboptimal congruity, articular cartilage or labral disease, and severe or chronic symptoms or poor hip function.

Surgeon training is an important factor. “I think it is very helpful to have a surgeon mentor or a cosurgeon when you first perform PAO,” Dr. Clohisy said. Cadaver work is also instructive, as is an adequate case volume and familiarity with the potential technical problems of the operation.

Postoperative pain management is multimodal, with epidural administration the first night. Prophylactic antibiotics are used for 24 hours, and Dr. Clohisy uses a wound drain for 1 to 2 days. Toe-touch weight bearing begins on postoperative day one. Continuous passive motion seems to be effective for pain and stiffness. Flexion beyond 90 degrees is not permitted. Aspirin and pneumatic stockings at day one serve for deep vein thrombosis prophylaxis. Full weight bearing begins at 1 month, with progression, and the target for full activity in young patients is 4 months.

Other presenters included Young-Jo Kim, MD, PhD, who detailed common pitfalls in hip imaging, and Christopher M. Larson, MD, who provided an overview on how to avoid or treat complications in arthroscopic procedures.

Disclosure information: Dr. Kelly—Pivot Medical, A-2 Surgical; Dr. Leunig—Smith & Nephew, Pivot Medical; Dr. Clohisy—Biomet, Wright Medical Technology, Zimmer; Dr. Kim—Siemens Health Care, Johnson & Johnson, Procter & Gamble; Dr. Larson—Smith & Nephew, A2 Surgical.

Terry Stanton is the senior science writer for AAOS Now. He can be reached at tstanton@aaos.org