Innovative rehabilitative bracing with applied resistance improves walking pattern recovery in the early stages of rehabilitation after ACL reconstruction: a preliminary investigation

Abstract

Background: The use of knee braces early after anterior cruciate ligament (ACL) reconstruction is a controversial issue. The study preliminarily compares the effect of a traditional brace blocked in knee extension and a new functional brace equipped with a spring resistance on walking and strength performance early after ACL reconstruction performed in the acute/subacute stage.

Methods: 14 ACL-reconstructed patients wore either a traditional (Control group: CG, 7 subjects) or a new functional brace (Experimental group: EG 7 subjects) until the 30^th post-operative day. All patients were tested before surgery (T0), 15, 30, and 60 days after surgery (T1, T2, and T3, respectively). Knee angular displacement and ground reaction forces (GRF) during the stance phase of the gait cycle were analyzed at each session and, at T3, maximal voluntary isometric contraction (MVIC) for knee flexor/extensor muscles was performed. Limb symmetry indexes (LSI) of GRF and MVIC parameters were calculated.

Results: At T3, EG showed greater peak knee flexion angle of injured limb compared to CG (41 ± 2° vs 32 ± 1°, p < 0.001). During weight acceptance, a significant increase of anteroposterior GRF peak and vertical impulse from T1 to T3 was observed in the injured limb in EG (p < 0.05) but not in CG (p > 0.05). EG showed a greater side-to-side LSI of weight acceptance peak of anteroposterior GRF at T2 (113 ± 23% vs 69 ± 11%, p < 0.05) and T3 (112 ± 23% vs 84 ± 10%, p < 0.05).

Conclusions: The preliminary findings from this study indicate that the new functional brace did help in improving gait biomechanical pattern in the first two months after ACL reconstruction compared to a traditional brace locked in knee extension.

Keywords: Anterior cruciate ligament; Biomechanics; Brace; Gait; Rehabilitation.

Fig. 1

Representative picture of the two models of brace: traditional brace locked at 0° knee extension (a) and functional brace with resistance to knee flexion and its polycentric spring system (b and c). The picture was taken from the producing company’s website and permission to publish was obtained from the company

Fig. 2

Knee angle, AP GRF and VT GRF of a representative trial. Vertical dotted line indicates the heel contact with the force plate. HC: heel contact; 1^st Peak_AP: positive peak of AP GRF during weight acceptance; 2^nd Peak_AP: negative peak of AP GRF during push-off; Peak_VT: peak of VT GRF after heel contact; Impulse_VT: impulse of VT GRF from heel contact to first peak

Fig. 3

Mean and standard deviation of maximum knee flexion angle and knee flexion angle at heel contact in the healthy and injured leg. ^a Significantly different vs T0, T2 and T3 in both EG and CG (p < 0.05); ^b Significantly different vs T2 in EG (p < 0.05); ^c Significantly different EG vs CG (p < 0.001); ^d Significantly different vs CG (p < 0.05)

Fig. 4

Mean and standard deviation of LSI of Peak_VT, 1^st Peak_AP and 2^nd Peak_AP. Horizontal dotted line indicates optimal limb symmetry index value (100%). ^a Significantly different vs CG (p < 0.05). ^b Significantly different vs T0 (p < 0.05)