Anterior cruciate ligament deficiency reduces walking economy in "copers" and "non-copers".
PURPOSE
Patients with ACL injury requiring surgical treatment (non-copers) demonstrate altered neuromuscular control and gait pattern compared with those returning to their pre-injury activities without surgery (copers). Pathological gait pattern may increase the energy cost of walking. We compared the energy cost of flat, uphill, and downhill walking between ACL-deficient and healthy individuals and between "copers" and "non-copers".


METHODS
Nineteen young males with unilateral ACL injury were allocated into "copers" and "non-copers" according to their ability to return to pre-injury activity without ACL reconstruction. Lysholm and IKDC scales were recorded, and a control group (n = 10) matched for physical characteristics and activity levels was included. All participants performed 8-min walking tasks at 0, +10, and -10 % gradients. Energy cost was assessed by measurement of oxygen consumption (VO2). HR and ventilation (VE), respiratory exchange ratio (RER), and VE/VO2 were also measured.


RESULTS
VO2 and HR were higher in ACL-deficient patients than in controls during walking at 0, +10, and -10 % gradients (p < 0.01-0.05). There were no differences between "copers" and "non-copers" in VO2 and HR for any gradient. No differences were observed in VE, RER, and VE/VO2 among the three groups.


CONCLUSIONS
The walking economy of level, uphill, and downhill walking is reduced in ACL-deficient patients. Despite the improved functional and clinical outcome of "copers", their walking economy appears similar to that of "non-copers" but impaired compared with healthy individuals. The higher energy demand and effort during locomotion in "copers" and "non-copers" has clinical implications for designing safer rehabilitation programmes. The increased energy cost in "copers" may be another parameter to consider when deciding on the most appropriate therapeutic intervention (operative and non-operative), particularly for athletes.


LEVEL OF EVIDENCE
II.
['Iliopoulos|Efthymios|E|', 'Galanis|Nikiforos|N|', 'Iosifidis|Michael|M|', 'Zafeiridis|Andreas|A|', 'Papadopoulos|Pericles|P|', 'Potoupnis|Michael|M|', 'Geladas|Nikolaos|N|', 'Vrabas|Ioannis S|IS|', 'Kirkos|John|J|']
D000328:Adult D016118:Anterior Cruciate Ligament D000070598:Anterior Cruciate Ligament Injuries D059549:Anterior Cruciate Ligament Reconstruction D001265:Athletic Injuries D005684:Gait D006801:Humans D007593:Joint Instability D008297:Male D000068958:Return to Sport D000070857:Walk Test D016138:Walking
ACL Energy cost ACL-deficient ACL reconstruction Oxygen consumption Energy expenditure