The main objective was to examine countermovement jump (CMJ) measures to identify which parameters can best distinguish between ACLR and control participants. The secondary objective was to determine whether performance alterations between operated and non-operated limb exist during vertical two-legged activities after ACLR
This study included 67 patients with hamstring graft and no contact injury at 6 postoperative months (203.5 days ± 32.2) and 47 healthy athletes (25,2 ± 6,6 years old, Marx score = 11,4 ± 2,2, Tegner score = 6,85 ± 1,7) with no knee injury history. Two groups were formed, an ACLR group (n=67) and a control group (n=47).
The participant's height (cm), mass (kg), age and sport activity level and operated limb were recorded before the start of the tests. Before the jump tests, participants performed a standardized warm-up that consisted of 5 minutes on a bicycle, 5 two-legged squats and 2 submaximal CMJ. Participants were instructed to stand on two legs on the force platforms. With their hands on their hip, they were asked to perform a CMJ, jumping as high as possible without upper limb movement. It is requested to carry out 3 tests and to keep the best performance for the analysis, while landing on the force plate.
The evaluation of CMJ by force plate was performed to calculate limb symmetry index (LSI) for vertical ground reaction force (vGRF), maximal power (MP) and eccentric rate force development (RFDe) during landing. First analysis compared LSI vGRF, LSI MP and LSI RFDe between both groups during CMJ. Secondary analysis compared vGRF, MP and RFDe between operated/non-operated limb in the ACLR group and dominant/non-dominant limb in the control group
At 6 months after ACLR, CMJ measures in the ACLR group were significantly reduced compared to the control group for LSI vGRF (85.9% ± 9.6 vs 94.6% ± 5.3, p 0,001, respectively), LSI MP (84.8% ± 8.4 vs 95.6% ± 4.1, p 0,001, respectively) and LSI RFDe (68.0% ± 23.1 vs 76.7% ± 17.2, p 0,001, respectively). Secondary analysis showed no significant result in control group between dominant/non-dominant limb. ACLR group showed significant results between operated / non-operated limb for vGRF (9.4 N.kg-1± 0.1 vs 10.8 N.kg-1± 0.13, p 0,001, respectively), MP (17.7 W.kg-1± 4.0 vs 20.3 W.kg-1± 4.1, p 0,001, respectively) and RFDe (825.2 N.s-1± 62.0 vs 1200.5 N.s-1± 87.8, p 0,01, respectively).
The results indicate significant torque, power, landing deficits and performance alterations on the non-operated limb during CMJ.
Landing and deceleration performance should be better considered at time to return to sport after ACLR. Double legged assessment should be considered in return to sport decision making after ACLR.
return to sport
deceleration
