title: Altered biomechanical strategies and medio-lateral control of the knee represent incomplete recovery of individuals with injury during single leg hop.
abstract: Anterior cruciate ligament (ACL) injury can result in failure to return to pre-injury activity levels and future osteoarthritis predisposition. Single leg hop is used in late rehabilitation to evaluate recovery and inform treatment but biomechanical understanding of this activity is insufficient. This study investigated single leg hop for distance aiming to evaluate if ACL patients had recovered: (1) landing strategies and (2) medio-lateral knee control. We hypothesized that patients with reconstructive surgery (ACLR) would have more similar landing strategies and knee control to healthy controls than patients treated conservatively (ACLD). 16 ACLD and 23 ACLR subjects were compared to 20 healthy controls (CONT). Kinematic and ground reaction force data were collected while subjects hopped their maximum distance. The main output parameters were hop distance, peak knee flexor angles and extensor moments and Fluency (a measure introduced to represent medio-lateral knee control). Statistical differences between ACL and control groups were analyzed using a general linear model univariate analysis, with COM velocity prior to landing as covariate. Hop distance was the smallest for ACLD and largest for CONT (p<0.001; ACLD 57.1±14.1; ACLR 75.1±17.8; CONT 77.7±14.07% height). ACLR used a similar kinematic strategy to CONT, but had a reduced peak knee extensor moment (p<0.001; ACLD 0.32±0.14; ACLR 0.31±0.16; CONT 0.42±0.13 BW.height). Fluency was reduced in both ACLD and ACLR (p=0.006; ACLD 0.13±0.34; ACLR 0.14±0.34; CONT 0.17±0.41s). Clinical practice uses hopping distance to evaluate ACL patients' recovery. This study demonstrated that aspects such as movement strategies and knee control need to be evaluated.
authors.affiliation: School of Healthcare Sciences, Cardiff University, Cardiff CF14 4XN, UK; Arthritis Research UK Biomechanics and Bioengineering Centre, Division School of Healthcare Sciences, Cardiff University, Cardiff CF14 4XN, UK. Electronic address: RoosPE@Cardiff.ac.uk.
authors.forename: Paulien E
authors.initials: PE
authors.lastname: Roos
authors.affiliation: School of Healthcare Sciences, Cardiff University, Cardiff CF14 4XN, UK; Arthritis Research UK Biomechanics and Bioengineering Centre, Division School of Healthcare Sciences, Cardiff University, Cardiff CF14 4XN, UK; Cardiff and Vale University Health Board, Cardiff, UK.
authors.forename: Kate
authors.initials: K
authors.lastname: Button
authors.affiliation: School of Healthcare Sciences, Cardiff University, Cardiff CF14 4XN, UK; Arthritis Research UK Biomechanics and Bioengineering Centre, Division School of Healthcare Sciences, Cardiff University, Cardiff CF14 4XN, UK.
authors.forename: Valerie
authors.initials: V
authors.lastname: Sparkes
authors.affiliation: School of Healthcare Sciences, Cardiff University, Cardiff CF14 4XN, UK; Arthritis Research UK Biomechanics and Bioengineering Centre, Division School of Healthcare Sciences, Cardiff University, Cardiff CF14 4XN, UK.
authors.forename: Robert W M
authors.initials: RW
authors.lastname: van Deursen
mesh_terms: D000328:Adult; D000368:Aged; D016118:Anterior Cruciate Ligament / Q000503:physiopathology* / Q000601:surgery; D000070598:Anterior Cruciate Ligament Injuries; D001696:Biomechanical Phenomena / Q000502:physiology; D004185:Disability Evaluation; D005260:Female; D006801:Humans; D027582:Humulus; D007718:Knee Injuries / Q000503:physiopathology* / Q000534:rehabilitation* / Q000601:surgery; D007719:Knee Joint / Q000503:physiopathology / Q000601:surgery; D007866:Leg; D008297:Male; D008954:Models, Biological; D009068:Movement / Q000502:physiology; D020370:Osteoarthritis, Knee / Q000517:prevention & control; D026741:Physical Therapy Modalities; D019651:Plastic Surgery Procedures / Q000534:rehabilitation*; D020127:Recovery of Function / Q000502:physiology; D055815:Young Adult
keywords: Anterior cruciate ligament; Biomechanics; Knee; Rehabilitation; Single leg hop