Compensatory mechanisms in basketball players with jumper's knee.

Context: Determining whether there are compensations in those with jumper's knee (JK) might further our understanding of the condition.

Objective: Comparing lower extremity kinematics and jump performance of basketball athletes with JK with those of healthy controls (C).

Design: Repeated-measures control-match design.

Setting: University laboratory.

Participants: 24 male basketball players (12 JK, 12 C) matched by height, weight, position, experience, and frequency of play.

Interventions: Standing counter-movement and running layup jumps.

Main Outcome Measures: Maximum vertical-jump height, footfall landing, and lower extremity sagittal-plane kinematics.

Results: There were no significant group differences (P > .05) in vertical-jump height (JK = 64.3 +/- 8.6 cm, C = 63.0 +/- 9.8 cm) or layup height (JK = 71.3 +/- 11.6 cm, C = 73.3 +/- 11.0 cm). JK subjects landed flat footed (50%) more than controls (8%). JK subjects showed significantly more hip flexion (JK = 105 degrees +/- 24.8 degrees, C = 89.8 degrees +/- 14.1 degrees; P = .039) with decreased hip acceleration during the countermovement (JK = -3039 +/- 1392 degrees /s2, C = -4229 +/- 1765 degrees /s2; P = .040). When landing from the countermovement jump, JK subjects had significantly less knee acceleration (JK = -4960 +/- 1512 degrees/s2, C = -6736 +/- 2009 degrees/s2, P = .023) and in the layup showed significantly less ankle dorsiflexion (JK = 106.5 degrees +/- 9.0 degrees, C = 112.5 degrees +/- 7.7 degrees; P = .048) and hip acceleration (JK = -2841 +/- 1094 degrees/s2, C = -3912 +/- 1575 degrees/s2; P = .033).

Conclusion: Compensatory strategies observed in JK subjects might help maintain performance, because their jump height was similar to that of healthy controls.