Archives of Orthopaedic and Trauma Surgery

, Volume 139, Issue 2, pp 155–166 | Cite as

Non-operative treatment of unicompartmental osteoarthritis of the knee: a prospective randomized trial with two different braces—ankle–foot orthosis versus knee unloader brace

  • Wolf PetersenEmail author
  • Andree Ellermann
  • Jörg Henning
  • Stefan Nehrer
  • Ingo Volker Rembitzki
  • Jürgen Fritz
  • Christoph Becher
  • Alfio Albasini
  • Wolfgang Zinser
  • Volker Laute
  • Klaus Ruhnau
  • Hartmut Stinus
  • Christian Liebau
Orthopaedic Surgery



The use of an unloader brace is a non-surgical treatment option for patients with medial osteoarthritis (OA). However, many patients do not adhere to brace treatment, because of skin irritation due to the pads at the level of the joint space and bad fit. A new concept to unload the medial compartment of the knee is a foot ankle brace with a lever arm pressing the thigh in valgus. The aim of this prospective randomized trial was to examine the outcomes of patients with medial OA after treatment with a conventional knee unloader brace (Unloader One®) and the new foot ankle orthosis (Agilium FreeStep®).


For this multicenter trial, 160 patients (> 35 years) with medial OA were randomly allocated to treatment with a conventional knee unloader brace (Unloader One®) or treatment with the new knee OA ankle brace (Agilium FreeStep®). The primary outcome measure was pain (numerical analog scale) at baseline (T0), 8 weeks (T1), and 6 months (T2). Secondary outcome measures were knee function (Knee Injury and Osteoarthritis Outcome Score, KOOS), side effects, additional interventions, and compliance.


In both groups, walking pain improved between T0 and T1 and also between T0 and T2 without a significant group difference. For pain at sports, both groups showed a significant improvement between T0 and T2 without a significant group difference. The KOOS subscales symptoms, pain, activity, sport, and quality of life increased significantly in both treatment groups without any significant group differences at T 0, T1, and T2. There was also no significant group difference in additional interventions and weekly or daily brace use. In the Agilium FreeStep® group (23.5%), significantly less patients reported bruises in contrast to the Unloader One® group (66.7%).


The results of this clinical trial show that the foot ankle brace is as effective as a conventional knee unloader brace for the treatment of medial knee OA with regard to clinical outcome. The rate of side effects such as bruises was significantly lower in the Agilium FreeStep® group.

Trial registration

DRKS00009215, 13.8.2015.


Knee pain Varus malalignment Varus deformity Biomechanics Non-surgical OA interventions Biomechanical interventions 



Funding was provided by Otto Bock Health Care.


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Copyright information

© Springer-Verlag GmbH Germany, part of Springer Nature 2018

Authors and Affiliations

  • Wolf Petersen
    • 1
    Email author
  • Andree Ellermann
    • 2
  • Jörg Henning
    • 3
  • Stefan Nehrer
    • 4
  • Ingo Volker Rembitzki
    • 5
  • Jürgen Fritz
    • 6
  • Christoph Becher
    • 7
  • Alfio Albasini
    • 8
  • Wolfgang Zinser
    • 9
  • Volker Laute
    • 10
  • Klaus Ruhnau
    • 11
  • Hartmut Stinus
    • 12
  • Christian Liebau
    • 13
  1. 1.Klinik für Orthopädie und UnfallchirurgieMartin Luther KrankenhausBerlinGermany
  2. 2.Arcus SportklinikPforzheimGermany
  3. 3.Krankenhaus Lahnhöhe, Zentr. für konserv. OrthopädieLahnsteinGermany
  4. 4.Donau Universität KremsKremsAustria
  5. 5.Deutsche Sporthochschule KölnCologneGermany
  6. 6.Orthopädisch Chirurgisches Centrum TübingenTübingenGermany
  7. 7.Orthopädische Klinik der MH HannoverHannover-KleefeldGermany
  8. 8.FISIOTERAPIA Albasini and MüllerBellinzonaSwitzerland
  9. 9.St. Vinzenz Hospital-DinslakenDinslakenGermany
  10. 10.Gelenk und WirbelsäulenzentrumBerlinGermany
  11. 11.Gemeinschaftspraxis Rosenthal and SchubertBochumGermany
  12. 12.Orthopaedicum NortheimNortheimGermany
  13. 13.Asklepios Harzklinik Fritz-König-StiftBad HarzburgGermany

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