July 2015

OSTEOARTHRITIS: Orthotic options for knee OA focus on compliance issues

By Jordana Bieze Foster

New research presented in June at the 2015 ISPO Congress underscored the potential long-term benefits of valgus knee bracing for relief of medial knee osteoarthritis (OA) symptoms when patient compliance is high, while other ISPO presentations explored alternative strategies for orthotic management of OA.

Researchers from Inverclyde Royal Hospital in Greenock, Scotland, analyzed pain and function in 147 patients with medial knee OA who wore a varus-valgus adjustment stress brace with four-point fixation and a closed frame with a polycentric hinge. A retrospective assessment included 86 patients and a mean follow-up of 3.4 years; 61 patients were assessed prospectively, with a mean follow-up of 1.2 years.

Pain levels, measured using a 10-point visual analog scale, significantly improved from 9 to 4 points. Average daily walking distance improved from 150 yards to 900 yards.

Patient compliance with brace use was high; only 13 patients discontinued brace use. Eight patients (six in the retrospective group) underwent total knee replacement and two (both in the retrospective group) underwent high tibial osteotomy (HTO). The two HTO patients had experienced improvement with the brace but were not able to wear it to work, according to S. Walkay, BSc, MRCS, a researcher in the hospital’s department of orthopedics, who presented the findings.

Although few patients discontinued brace wear, most did reduce the extent of weekly wear over time, Walkay said.

“Once they get used to the brace, they can wear it for less time without recurrence of pain,” he said. “At the end of two years, most patients were only wearing the brace two or three days per week.”

A study from Laval, Quebec, Canada, suggests that a different approach to knee OA bracing is also associated with high levels of patient compliance.

In 24 patients with medial knee OA, a distraction-rotation brace was associated with a 14% decrease in the second peak knee adduction moment (KAM), an 8.8% decrease in KAM impulse, and a 42% improvement in pain after three months, according to Danielle Boucher, an orthotist-prosthetist and vice president of ErgoResearch, who presented the findings.

Anecdotally, Boucher said, 75% of the patients were still wearing the brace for six to eight hours per day after 12 months.

A third presentation explored the biomechanics of a third orthotic approach to knee OA that involves no bracing at the knee.

Researchers from the Otto Bock Competence Center in Göttingen, Germany, analyzed the effects of a hinged ankle foot orthosis (AFO) on knee kinematics and kinetics in 10 healthy individuals and 12 patients with unilateral knee OA. The AFO was designed to allow unrestricted sagittal plane ankle motion but featured rigid bridging in the frontal plane to limit eversion range of motion of the subtalar joint, shifting the body’s center of pressure (COP) laterally and decreasing the lever arm between the ground reaction force vector and the knee.

The investigators found that the AFO was associated with a significant decrease in first peak varus moment compared with a neutral shoe condition, from .47 to .36 Nm/kg in the healthy individuals and from .73 to .63 Nm/kg in the OA patients. In the OA patients, AFO use was also associated with a significant improvement in pain during level walking and stair ascent and descent.

Tibial rotation, an indirect marker of subtalar joint eversion, was significantly reduced with AFO use in both groups, and the COP shifted laterally by 9.7 mm in the healthy participants and by 12.5 mm in the OA patients. These values correlate with lever arm reductions of 6.9 and 11 mm.

Because AFOs are more discreet than conventional knee OA braces and are less vulnerable to migration, patients may be more accepting of the distal approach, said Thomas Schmalz, PhD, a research biomechanist with Otto Bock, who presented the findings. He noted, however, that a knee orthosis might be a better choice for patients with knee instability.

Sources:

Walkay S, Munro W, Buchan M. A clinical outcome study of the varus-valgus stress adjustment knee brace in the management of knee osteoarthritis: A district general hospital experience in the West of Scotland. Presented at the International Society of Prosthetics & Orthotics World Congress, Lyon, France, June 2015.

Desroisiers L, Boucher D. Clinical and biomechanical efficiency evaluation of a new distraction/rotation knee brace in the treatment of medial knee osteoarthritis. Presented at the International Society of Prosthetics & Orthotics World Congress, Lyon, France, June 2015.

Schmalz T, Drewitz H, Stocker K. The use of an AFO as an innovative method within the scope of the conservative treatment of osteoarthritis of the knee. Presented at the International Society of Prosthetics & Orthotics World Congress, Lyon, France, June 2015.

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