title: Anatomic single-bundle anterior cruciate ligament reconstruction improves walking economy: hamstrings tendon versus patellar tendon grafts.
abstract: OBJECTIVE
  Anterior cruciate ligament (ACL) injury is associated with a pathologic gait pattern and increased energy cost during locomotion. ACL reconstruction could improve the gait pattern. Hamstrings tendon (HAM) and bone-patellar tendon-bone (BPTB) grafts are usually used for reconstruction. The aim of this study was to compare the efficacy of anatomic ACL reconstruction with HAM and BPTB grafts on improving and normalizing the energy cost and physiologic reserves during flat, uphill, and downhill walking.
  
  
  METHODS
  Twenty male subjects with unilateral ACL injuries were randomly assigned to ACL reconstruction with a HAM (n = 10) or BPTB (n = 10) graft. Ten matched controls were also enrolled. All participants performed three 8-min walking tasks at 0, +10, and -10 % gradients before and 9 months after surgery. Energy cost (oxygen consumption, VO2), heart rate (HR), and ventilation (VE) were measured. Lysholm/IKDC scores were recorded.
  
  
  RESULTS
  Pre-operatively, VO2, HR, and VE were higher in the HAM and BPTB groups than in controls during walking at 0, +10, and -10 % gradients (p < 0.001-0.01). Post-operatively, both HAM and BPTB groups showed reduced VO2, HR, and VE during the three walking tasks (p < 0.001-0.01). Although the post-operative VO2in both surgical groups reached 90-95 % of the normative (control) value during walking, it remained elevated against the value observed in controls (p < 0.001-0.01). The HAM and BPTB groups showed no differences in post-surgical VO2or HR during walking at all three gradients.
  
  
  CONCLUSIONS
  Anatomic ACL reconstruction with either HAM or BPTB graft resulted in similar short-term improvements in energy cost and nearly normalized locomotion economy and cardiorespiratory reserves during flat, uphill, and downhill walking. The improved locomotion economy is an additional benefit of anatomic ACL reconstruction, irrespective of the type of graft used, that the orthopaedic surgeons should consider.
  
  
  METHODS
  II.
authors.affiliation: Division of Sports Medicine, Department of Orthopaedics, Papageorgiou General Hospital, Medical School, Aristotle University of Thessaloniki, Ring Road, 56403, Thessaloniki, Greece.
authors.forename: Efthymios
authors.initials: E
authors.lastname: Iliopoulos
authors.affiliation: Division of Sports Medicine, Department of Orthopaedics, Papageorgiou General Hospital, Medical School, Aristotle University of Thessaloniki, Ring Road, 56403, Thessaloniki, Greece. kyros@med.auth.gr.
authors.forename: Nikiforos
authors.identifier: http://orcid.org/0000-0003-3682-4303
authors.initials: N
authors.lastname: Galanis
authors.affiliation: Department of Physical Education and Sports Science at Serres, Aristotle University of Thessaloniki, Serres, Greece.
authors.forename: Andreas
authors.initials: A
authors.lastname: Zafeiridis
authors.affiliation: Sports Medicine Unit, 2nd Orthopaedic Department, Papageorgiou General Hospital, Thessaloniki, Greece.
authors.forename: Michael
authors.initials: M
authors.lastname: Iosifidis
authors.affiliation: 1st Department of Orthopaedics, Papanikolaou General Hospital, Medical School, Aristotle University of Thessaloniki, Thessaloniki, Greece.
authors.forename: Pericles
authors.initials: P
authors.lastname: Papadopoulos
authors.affiliation: Division of Sports Medicine, Department of Orthopaedics, Papageorgiou General Hospital, Medical School, Aristotle University of Thessaloniki, Ring Road, 56403, Thessaloniki, Greece.
authors.forename: Michael
authors.initials: M
authors.lastname: Potoupnis
authors.affiliation: Department of Sport Medicine and Biology of Exercise, School of Physical Education and Sport Science, University of Athens, Athens, Greece.
authors.forename: Nikolaos
authors.initials: N
authors.lastname: Geladas
authors.affiliation: Department of Physical Education and Sports Science at Serres, Aristotle University of Thessaloniki, Serres, Greece.
authors.forename: Ioannis S
authors.initials: IS
authors.lastname: Vrabas
authors.affiliation: Division of Sports Medicine, Department of Orthopaedics, Papageorgiou General Hospital, Medical School, Aristotle University of Thessaloniki, Ring Road, 56403, Thessaloniki, Greece.
authors.forename: John
authors.initials: J
authors.lastname: Kirkos
mesh_terms: D000328:Adult; D000070598:Anterior Cruciate Ligament Injuries / Q000503:physiopathology / Q000601:surgery*; D059549:Anterior Cruciate Ligament Reconstruction / Q000379:methods*; D050376:Bone-Patellar Tendon-Bone Grafting / Q000379:methods; D004734:Energy Metabolism / Q000502:physiology; D005684:Gait / Q000502:physiology; D000070632:Hamstring Tendons / Q000637:transplantation*; D006801:Humans; D008297:Male; D017847:Patellar Ligament / Q000637:transplantation*; D016896:Treatment Outcome; D016138:Walking / Q000502:physiology*
keywords: ACL; ACL reconstruction; Energy cost; Energy expenditure; Graft choice; Oxygen consumption