May 01, 2010
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Study finds unloader brace significantly benefits osteoarthritis of the knee

Investigators also find that education aids in brace use compliance.

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A prospective cohort study found that patients with osteoarthritis, who have high expectations of improving their ability to participate in recreational sports, had improvement in their disability when using an unloader brace.

“Patients maintained or improved their activity level and saw reduction in pain and anti-inflammatory medications,” said co-investigator Karen K. Briggs, MPH, director of clinical research at the Steadman Philippon Research Institute in Vail, Colo. Her comments came during the 2010 Annual Meeting of the American Academy of Orthopaedic Surgeons in New Orleans.

For the study, 47 patients, 17 women and 29 men, with a mean age of 61 years were fitted with a unloader braces [Unloader One, Ossur]; 14 patients with a lateral unloader and 32 with a medial unloader.

Karen K. Briggs, MPH
Karen K. Briggs

High expectations

“Previous studies have shown that unloader braces resulted in improvement in disability due to osteoarthritis,” Briggs told Orthopedics Today. “However, few studies have looked at active patients with osteoarthritis seeking to improve function and activity level. In our study, we showed that patients can improve their activity and their function with an unloader brace — in a population who had high expectations regarding activity.”

The study found similar improvement in both types of braces. The larger medial group, though, had increased disability prior to brace use and more improvement.

“But the smaller the medial joint space, the more disability in the medial group,” Briggs said. The lateral group showed increased disability in patients with more varus alignment.

All patients completed the Western Ontario and McMaster Universities (WOMAC) Osteoarthritis Index prior to brace use, then at 6-week and 6-month follow-up. The medial group had a higher pre-brace total WOMAC (34 vs. 23). Pre-brace pain was also greater in the medial group (8 vs. 5).

Improved WOMAC

The mean medial joint space for the medial group was 2.4 mm, compared to a mean lateral joint space of 4.2 mm for the lateral group.

“It was interesting that for the medial group, the pre-brace WOMAC score correlated with medial joint space,” Briggs said. “The less medial joint space, the more disability. The lateral group disability did not correlate with joint space loss, however, the joint space was measured on AP radiographs which does not assess loss of joint space in the posterior portion of the lateral compartment.”

There was also a 26% deviation from neutral alignment in the medial group and 19% in the lateral group. “For the lateral group, pre-brace WOMAC correlated with deviation from neutral alignment,” Briggs said. “More research is needed to determine the difference between patient disability in the varus and valgus knee.”

At 6 months, improvement in WOMAC was 12 points for the medial group and 9 points in the lateral group, “for close to a 50% improvement in disability,” she said.

QOL scores

Patients also had expectations of improvement in quality of life. This was measured using the SF-12. “The physical component of the SF-12 showed significant improvement at 6 weeks and 6 months,” Briggs said. “As expected, the mental component did not change.”

Overall, patients were satisfied with their treatment. “We feel it is important to document all these measures,” Briggs said. “If patient expectations can be met, then patients will be more satisfied with their treatment.”

Briggs also noted that the study had a high level of continued brace use. “It is our opinion that the low drop-out rate is due to patient education and proper fitting of the brace initially,” she said. — by Bob Kronemyer

References:
  • Briggs KK, Matheny LM, Steadman, JR, et al. Use of an unloader brace for medial or lateral compartment osteoarthritis of the knee. Paper 638. Presented at the 2010 Annual Meeting of the American Academy of Orthopaedic Surgeons. March 9-13. New Orleans.

  • Karen K. Briggs, MPH, director of clinical research, Steadman Philippon Research Institute, 181 W. Meadow Drive, Suite 1000, Vail, CO 81657; 970-479-5783; e-mail:Karen.briggs@sprivail.org.
  • The study was funded by Ossur America. Dr. Richard Steadman is a consultant for Ossur America.

Perspective

The study shows that patient education, and compliance makes the use of an unloader brace successful for the treatment of medial and lateral knee osteoarthritis. In it, the more the medial joint space narrowing, the more the pre-brace disability. The results showed that the unloader brace had a 50% improvement in disability.

There is no question that to make the use of unloader brace successful several criteria must be met. The patient must be very motivated to use a brace and this may be improved by patient education. Not every patient is convinced that they want to wear a brace for all activities. Many patients would rather have an operation than use a brace. Therefore there is probably some selection bias in any brace study. The oher criteria that are important are the size of the thigh, and medial pseudo-laxity. It is very difficult to fit a brace to a conical thigh. The lean active patient is much more likely to continue with brace use. I have found that the patient who has medial pseudo-laxity compared to a fixed varus knee will respond better to unloader bracing.

Finally, the company that supplied the brace supported this study.

Thus there are several selection bias that are evident in this study by Briggs, which should be recognized, but do not reduce the significance of the findings.

– Donald H. Johnson, MD, FRCSC
Sports Medicine Clinic
Carleton University
Ottawa, Ontario