Research supports allowing motion during distraction to treat ankle osteoarthritis

Following ankle debridement, patients who had distraction with allowed motion improved more dramatically than a non-motion group.

Issue: September 2010

Distraction to treat ankle osteoarthritis proved most beneficial through 2 years post-treatment when some ankle motion was permitted rather than when the ankle remained fixed throughout distraction, based on findings of a prospective randomized study presented at the 2010 Summer Meeting of the American Orthopaedic Foot and Ankle Society.

Annunziato “Ned” Amendola, MD, director of sports medicine at the University of Iowa, Iowa City, Iowa, who presented the study, and co-investigators theorized the better results with distraction that they saw in those randomized to the ankle motion group may relate to bone density changes seen on CT scans, an area he said they are still investigating.

“Distraction arthroplasty for end-stage osteoarthritis does look promising. It is not an easy treatment for both the surgeon and the patient and it is work intensive. There seems to be improved results with both motion and non-motion distraction,” said Amendola, whose paper won the American Orthopaedic Foot and Ankle Society’s (AOFAS) 2010 Roger A. Mann Award.

Annunziato “Ned” Amendola, MD, was the recipient of the Roger A. Mann Award at the 2010 Summer Meeting of the American Orthopaedic Foot and Ankle Society for his paper “Prospective randomized controlled trial of motion vs. fixed distraction in treatment of ankle osteoarthritis.”

Image: AOFAS

Arthroscopic or mini-open debridement

For the investigation, the researchers enrolled 40 patients younger than age 60 years with advanced ankle arthritis, all of whom failed 1 year of nonoperative treatment. Patients were randomized to ankle distraction with or without ankle motion. In each group, 18 patients with similar demographics completed the study.

“We hypothesized for this study that the distraction with motion would result in significant improvement in outcome compared to distraction without motion,” Amendola said, noting they used the Ankle Osteoarthritis Scale (AOS) as the primary and the SF-36 and its physical component subscale as the secondary outcome measures.

He and co-investigator AOFAS Immediate Past President Charles L. Saltzman, MD, performed arthroscopic or mini-open procedures to debride the patients’ ankles and remove anterior osteophytes. They applied a hinged distractor in the motion group and a non-hinged distractor in the non-motion group, achieving 5 mm acute distraction in all cases. The motion group, whose rehabilitation began 1 week postoperatively, received a posterior rod that could be disconnected to permit range of motion exercises.

Adverse events

Outcomes were assessed at 1, 26, 52 and 104 months after the distractor frames were removed, which occurred at 3 postoperative months. Both groups improved significantly by the 104-month follow-up compared to their pretreatment assessments,.

Amendola noted that 6, 12 and 24 months after frame removal, “there was a significant difference in the outcomes scores between the two groups at the three time points.” Similar improvements and differences in disability were seen in the groups at the same follow-up, he said.

“The total AOS has also shown a significant difference, with the motion group doing much better than the non-motion group. The summary of the treatment showed that using the AOS as the primary outcome measure at 2 years, the motion group had almost double the improvement of the non-motion group. So adding motion was beneficial,” Amendola said.

Despite adverse events including 43 pin tract infections, post-distraction numbness in eight patients and one deep venous thrombosis, “We would recommend using motion as part of the distraction protocol,” Amendola said. – by Susan M. Rapp

Reference:

Amendola A, Hillis S, Stolley MP and Saltzman CL. Prospective randomized controlled trial of motion vs. fixed distraction in treatment of ankle osteoarthritis. Presented at the 2010 Summer Meeting of the American Orthopaedic Foot and Ankle Society. July 8-10. National Harbor, Md.

Annunziato Amendola, MD,can be reached at UI Sports Medicine, University of Iowa, Iowa City, IA; 319-356-4230; e-mail: Ned-amendola@uiowa.edu.

The authors of this study should be commended for their efforts to further the evidence base regarding the treatment of ankle arthritis with distraction. There has been limited documentation of the effectiveness of distraction and the related question of the role of motion in patients undergoing distraction. The authors investigate these critical issues by performing a randomized controlled trial comparing fixed distraction to a technique combining distraction with motion. Their results indicate improved patient functional outcomes in the distraction technique that permitted motion.

The long-term follow-up in this study to 104 months provides particularly valuable evidence regarding the use of distraction for the treatment of ankle osteoarthritis. Further trials that include random allocation of patients to groups treated nonoperatively will also be helpful to clarify the effectiveness and indications of ankle distraction.

– Nelson SooHoo, MD
Department of Orthopaedic Surgery
University of California at Los Angeles

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