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Table 3 Assistive PAFOs tested on impaired and elderly subjects

From: Powered ankle-foot orthoses: the effects of the assistance on healthy and impaired users while walking

Ref. Actuation (Pf/Df) Control Weight PAFO Subjects Conditions (n. sessions / repetitions) Walking speed Ul / Bl Portable Outcomes
Awad, 2017 [63] SEA (Pf + Df) P-Bc: Pf assist during stance, Df assist during swing 0.9 kg 8 Str 8P-8U Self-selected Ul no hip hiking circumduction step length Df in swing
Awad, 2017 [64] SEA (Pf + Df) P-Bc: Pf assist during stance, Df assist during swing 0.9 kg 9 Str 8P-8U (2sess, 2 different onset timings) Self-selected Ul no Df in swing propulsion asymmetry metabolic cost
    4.1 kg   P-U    yes Df in swing propulsion asymmetry
Bae, 2015 [26] SEA (Pf* + Df) P-Bc: Pf assist during PO, Df assist during swing 0.9 kg 3 Str baseline: N; training: P (3 to 5 sess); test: P Self-selected Ul no step and stance time symmetry propulsion symmetry circumduction
Bae, 2018 [27] SEA (Pf* + Df) P-Bc: Pf assist during stance, Df assist during swing 0.9 kg 7 Str 8P-8U Self-selected Ul no symmetry body CoM power generation metabolic cost symmetry ankle power generation
Blaya, 2004 [51] SEA (Df) P-Bc: Df assist during LR and swing 2.6 kg 3 H N-A-P Self-selected (1.21m/s (H), 1.15m/s (Dfi)), slow, fast (decreased, increased 25%) / no /
     2 Dfi      Df in swing; Pf in stance; occurrence of foot slap at all speeds; step length and step time asymmetry at slow and self-selected speed
Galle, 2017 [56] PAM (Pf) P-Bc: Pf assist during PO 0.76 kg 8 E 5N-5U-5P(x2 powered conditions) (2 sess) 1.11 m/s Bl no step length metabolic cost
Norris, 2007 [55] PAM (Pf) P-Bc: Pf assist during PO 0.8 kg 9 H N-U-P Self-selected Bl no walking speed; modest reduction metabolic cost
     7 E      no difference in walking speed; modest reduction metabolic cost
Sawicki, 2006 [65] PAM (Pf) + elastic cord (Df) P-btnc: PO assist 1.09 kg 5 iSCI 10/15N-10/15U-10/15P(therapist)-10/15P(patient), 30/50% BWS (2 sess) 0.36, 0.54, 0.72, 0.89 m/s (subjects preferred: 0.56 m/s) Bl no RoM; Pf in stance; bigger improvements in therapist than patients control; in P muscle activity similar to N
Shorter, 2011 [52] BPnA (Pf + Df) P-Bc: Df assist during LR and swing, Pf assist during PO 3.1 kg 3 H 1N-1U-1P(x3 powered conditions) Self-selected Ul yes tibialis anterior activity
     1 Pfi 1.5N-1.5U-1.5P(x3 powered conditions)   Ul + AFO   improved Pf; improved PO phase
Shorter, 2011 [53] BPnA (Pf + Df) P-Bc: Pf assist during PO 3.1 kg 1 Pfi N-U-P Self-selected Ul + AFO yes RoM in Df; symmetry; improved PO phase
   P-Bc: Df assist during LR and swing   1 Dfi      occurrence foot drop; better foot positioning heel strike; symmetry
Takahashi, 2015 [39] PAM (Pf) PMc (impaired soleus & GRF) / 5 Str 5N-5U-5P (x3 powered conditions) 75% of self-selected Ul no impaired soleus activation; trend of decreasing metabolic cost
Yeung, 2017 [54] StA (Pf + Df) P-Bc: Pf assist during LR and PO, Df assist during swing 1 kg 3 Str training: 10U; test: N-U-P / / yes occurrence foot drop; no enhancement PO
  1. The type of actuator, the weight and portability of the device, the protocol and the main outcomes of each study are reported. In some studies the devices were tested also on healthy young users
  2. iSCI, Str, Dfi/Pfi: Incomplete spinal cord injury, stroke and dorsi-/plantar-flexion impaired subjects; E: Elderly subjects; H: Healthy young subjects; SEA: Series elastic actuator; PAM: Pneumatic artificial muscle; BPnA: Bidirectional rotaty pneumatic actuator; StA: Stiff actuator; Pf, Df: Plantarflexion and dorsiflexion; P-Bc: Phase-based controller; P-btnc: push-button controller, PMc: Proportional myoelectric controller; LR: Loading response; PO: Push-off; N, A, U, P: Normal walking, walking with conventional AFO, unpowered and powered walking condition; BWS: Bodyweight support; GRF: Ground reaction force; Ul, Bl: Uni-/bi-lateral PAFO; CoM: Center of mass; the protocol code defines the conditions and the timings in minutes used for each session, e.g. xPyUzN means x minutes of powered walking, y minutes of unpowered walking and z minutes of normal walking. *: the Pf module exerted also hip flexion torques. In the works in which different experiments were performed (for example, different control strategies) the common information between the experiments (for example, same condition) is reported only once