Anti-gravity treadmills are effective in reducing knee forces

Authors

  • Shantanu Patil,

    1. Shiley Center for Orthopaedic Research and Education at Scripps Clinic, 11025 North Torrey Pines Road, Suite 200, La Jolla, California 92037
    Search for more papers by this author
  • Nikolai Steklov,

    1. Shiley Center for Orthopaedic Research and Education at Scripps Clinic, 11025 North Torrey Pines Road, Suite 200, La Jolla, California 92037
    Search for more papers by this author
  • William D. Bugbee,

    1. Scripps Clinic, 10666 North Torrey Pines Road, MS116, La Jolla, California 92037
    Search for more papers by this author
  • Timothy Goldberg,

    1. Scripps Memorial Hospital Encinitas, 435 Santa Fe Dr. ENC 32, Encinitas, California 92024
    Search for more papers by this author
  • Clifford W. Colwell Jr.,

    1. Shiley Center for Orthopaedic Research and Education at Scripps Clinic, 11025 North Torrey Pines Road, Suite 200, La Jolla, California 92037
    Search for more papers by this author
  • Darryl D. D'Lima

    Corresponding author
    1. Shiley Center for Orthopaedic Research and Education at Scripps Clinic, 11025 North Torrey Pines Road, Suite 200, La Jolla, California 92037
    • Shiley Center for Orthopaedic Research and Education at Scripps Clinic, 11025 North Torrey Pines Road, Suite 200, La Jolla, California 92037. T: 858-332-0166; F: 858-332-0669
    Search for more papers by this author

Abstract

Lower body positive pressure (LBPP) treadmills permit significant unweighting of patients and have the potential to enhance recovery following lower limb surgery. We determined the efficacy of an LBPP treadmill in reducing knee forces in vivo. Subjects, implanted with custom electronic tibial prostheses to measure forces in the knee, were tested on a treadmill housed within a LBPP chamber. Tibiofemoral forces were monitored at treadmill speeds from 1.5 mph (0.67 m/s) to 4.5 mph (2.01 m/s), treadmill incline from −10° to +10°, and four treadmill chamber pressure settings adjusted to decrease net treadmill reaction force from 100% to 25% of the subject's body weight (BW). The peak axial tibiofemoral force ranged from 5.1 times BW at a treadmill speed of 4.5 mph (2.01 m/s) and a pressure setting of 100% BW to 0.8 times BW at 1.5 mph (0.67 m/s) and a pressure setting of 25% BW. Peak knee forces were significantly correlated with walking speed and treadmill reaction force (R2 = 0.77, p = 0.04). The LBPP treadmill might be an effective tool in the rehabilitation of patients following lower-extremity surgery. The strong correlation between tibiofemoral force and walking speed and treadmill reaction forces allows for more precisely achieving the target knee forces desired during early rehabilitation. © 2012 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 31: 672–679, 2013

Ancillary