Award-winning paper outlines “a promising procedure”

The most commonly performed surgical procedures for ankle osteoarthritis (OA) are ankle fusion and joint replacement, but distraction, although controversial, has many advocates.

Distraction—the mechanical separation of the opposing articular cartilage surfaces—has been demonstrated in some studies to achieve significant improvement in pain, function, and clinical condition in as many as 73 percent of patients. The procedure is not commonly used, however, because clinical experience and outcomes are not well reported in the literature and because of concern about adverse effects.

According to Annunziato Amendola, MD, coauthor of a paper on the subject that won the 2010 Roger A. Mann Award at the American Orthopaedic Foot & Ankle Society (AOFAS) 2010 annual meeting, “It’s not an easy procedure for the surgeon or the patient.” For the patient, fixation involves wearing an appliance for 2 to 3 months after surgery; in addition, the procedure is “work-intensive” for the surgeon.

But unlike either fusion or joint replacement, the decision to use distraction does not “burn any bridges that would preclude more definitive treatment if eventually necessary.”

Dr. Amendola conducted a prospective, randomized controlled trial to compare outcomes of patients with advanced ankle OA who were treated surgically with anterior osteophyte removal and either fixed ankle distraction or ankle distraction permitting motion.

His coworkers on the study, “Prospective Randomized Controlled Trial of Motion vs. Fixed Distraction in Treatment of Ankle Osteoarthritis,” were Steve Hillis, PhD; Mary P. Stolley, RN; and Charles L. Saltzman, MD.

Theoretically better
Joint motion is “an essential adjunction in the biological restoration of articular cartilage from injury,” said Dr. Amendola. His study team hypothesized that allowing motion during distraction would result in significant improvements in outcome compared with distraction without motion.

Half of the 36 patients in the study group underwent distraction with motion; the remaining half had distraction without motion. All patients had advanced ankle OA (Fig. 1), were age 60 years or younger, and were able to maintain extremity non–weight-bearing using ambulatory aids. All had been treated unsuccessfully for more than a year, including 3 months of continuous treatment with nonsteroidal anti-inflammatory drugs and 3 months of unloading treatment. Patients with serious comorbidities, contralateral OA, or significant hindfoot or tibial mal-alignment were excluded.

The two groups were similar in age, sex distribution, and body mass index.

All procedures were performed by one of two attending surgeons using the same technique. A tourniquet was not used for the surgery, and patients were supine. An arthroscopic ankle joint lavage with removal of any extra-articular anterior bony osteophytes was performed, using standard anterior portals. If the anterior osteophytes were too large to remove arthroscopically, they were removed by open means through an extension of the arthroscopic portals. No intra-articular joint débridement was done.

In patients allocated to distraction without motion, the distraction rods were placed without hinges. In patients allocated to distraction with motion, the distraction rods were placed with hinges (Fig. 2), and with a posterior rod that was disconnected at the time of motion therapy.

Because the procedure is performed with no tissue dissection and small incisions (less than 1 cm), it was typically done on a short-stay inpatient admission or outpatient basis. Patients wore the frame for 3 months and progressed to full weight bearing without boot immobilization at 6 months.

Outcomes were measured using the overall Ankle Osteoarthritis Scale (AOS) score, the pain and disability AOS subscale scores, and the Physical Component Scale (PCS) of the Medical Outcomes Study 36-item short-form health survey (SF-36), version 2. Patients were evaluated at 1 week, 6 months, 12 months, and 24 months after fixator removal and maximal dorsiflexion and plantar flexion lateral radiographs were taken (Fig. 3).

Results favor motion
At the 2-year follow-up, intent-to-treat analysis revealed that both groups had improved significantly (p < 0.02). However, the motion-distraction group did significantly better than the fixed-distraction group at 26, 52, and 104 weeks after frame removal (p < 0.05 at each time point). At 104 weeks, the motion group had an overall mean AOS improvement of 56.6 percent, whereas the fixed group had a 29.7 percent improvement (p < 0.01). Range of motion did not significantly change in either group.

Caution warranted
Dr. Amendola acknowledged that “adverse effects are significant” with the distraction procedure and its relatively prolonged period of convalescence. His study group included 43 episodes of pin tract infections (19 patients), and two patients received antibiotics for 6 weeks for suspected acute osteomyelitis. All reported infections resolved.

Dr. Amendola recommended that both physician and patient embark on the course of ankle distraction with a realistic attitude. “This is not a procedure to be done for patients or by surgeons who want a ‘quick fix,’” he said. “We advise patients who are considering this treatment that they may not see the benefits of the procedure until a year after surgery. Compared with fusion or joint replacement, that is a relatively long time to wait for a treatment benefit. Whether the total time of distraction can be shortened is unknown.”

For the appropriate patient, however, distraction, especially with motion allowed, may be the best approach. “I think both methods of distraction improve outcomes,” said Dr. Amendola. “Adding motion seems to double the response to the treatment. We would recommend using motion as part of the protocol.”

Disclosure information: Dr. Amendola—Arthrosurface, Arthrex; Dr. Saltzman—Elsevier, Tornier, TotalChart, Twin Star Medical, United Cerebral Palsy Research and Education Fund, Zimmer. Dr. Hillis and Ms. Stolley reported no conflicts.

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

Bottom line

• Distraction is performed rather infrequently but may have advantages over other treatment methods (fusion or replacement) for ankle OA.
• Performance of distraction does not preclude other definitive treatments in the future.
• In this small, prospective, randomized, controlled trial, patients who underwent distraction with motion had significantly better outcomes than those who had distraction without motion.
• Disadvantages to the procedure include a long convalescence time and a relatively high rate of adverse events, especially pin-site infections.