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The relationship between hop distance and control in ACLR patients

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Introduction: While anterior cruciate ligament (ACL) injuries account for less than 1% of all injuries in football, there is a significant morbidity associated with them (Ekstrand 2014). Professional footballers, for example, can take approximately 6.5 months before a return to team training following ACL repair (ACLR). In addition, the risk of re-injury is relatively high ranging from 6 to 27% (Shelbourne et al. 2014; Paterno et al. 2010). Following ACLR, rehabilitation specialists test muscular strength, power and movement control to assess rehabilitation progress and to inform return to play (RTP) decision making. Muscular strength is typically assessed using isokinetic testing (Fernandes et al. 2012), while power development can be assessed using a single leg hop for distance (Grindhem et al. 2011). Isokinetic strength and power performance are primary objective markers when assessing readiness to RTP following ACL injury, but the quality of movement control (a more qualitative assesment by the rehabilitator) is often overlooked. This may lead to an over reliance on performance outcome measures when assessing readiness to return to play without proper consideration being given to movement control.

Purpose: To examine the relationship between hop distance and landing control in ALCLR patients for a single leg hop for distance.

Methods: 30 multi directional field sports players 6 months post patellar tendon ACLR were recruited [mean ± SD: age 25.4 ± 2.3 years; height 182.3 ± 4.6cm; mass 80.7 ± 6.0 kg]. The study was approved by the Sport Surgery Clinic Hospital Ethics Committee and participants completed and signed an informed consent form before taking part.

Participants undertook a warm-up which consisted of a 2 minute slow jog, body weight squats, vertical jumps, drop landings and lateral hops. Testing involved three single leg hops for distance on the operated limb. Pariticpants were instructed to bend the free leg behind at a 90 degree angle, undertake a horizontal hop for maximal distance, land and attempt to hold the landing for two seconds.

Each hop movement was captured using high speed video and 3D motion capture cameras (Vicon). Hop distance was obtained from the horizontal distance travelled by a toe marker. The longest hop trial was selected for further analysis.

Movement control on landing was assessed qualitatively using video playback in the sagital and frontal plane. Control was ranked on a scale of zero to five, each participant began with five points and one point was deducted for each of the following : loss of knee, pelvis and trunk control, poor load absorption and inability to maintain balance on landing for greater than two seconds. Participants were grouped into a ‘poor control’ group (0-2 score) and a ‘good control’ group (>3 score).
An independent measures t-test (α = 0.05) was used to examine differences in jump distance between the groups.
Results:
16 individuals were categorised as having poor control and 14 individuals as having good control. There was no significant difference (p = 0.79) in hop distance between the groups (Table 1).

Conclusion:
Our study demonstrated that hop distance (primarily a measure of lower extremity power production), and landing control, are distinct qualities. It is important therefore that rehabilitators evaluate dynamic movement control as a distinct return to play criteria in addition to the more commonly utilised performance outcome measures (e.g hop distance). An over reliance on performance outcomes may result in an athlete returning to sport with deficient movement control and in turn an increased risk of ACL re-injury or contralateral injury (Myer et al 2005, Hewett et al. 2013). The fact that over half of the athletes in this study demonstrated poor movement control on landing six months post ACLR surgery support the findings of Lee et al. (2014) who found that even after successful surgical reconstruction, the function of the knee during dynamic activities can be limited.

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Related: http://doras.dcu.ie/20638/2/Hop_distance_and_control_in_ACLR_patients_April9th.p...
Suggested citation:

. () The relationship between hop distance and control in ACLR patients [Online]. Available from: http://publichealthwell.ie/node/876479 [Accessed: 20th October 2019].

  

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