Knee injuries, especially anterior cruciate ligament (ACL) injuries, are frequent in sports such as basketball, handball, soccer, and gymnastics.  Research has found that most ACL are non-contact ACL injuries - these injuries commonly occur while performing cutting movements or landing from a jump rather than direct.  In a video analysis study conducted by Krosshaug et al ACL injuries sustained during basketball games were analyzed using slow motion video.  The video clips revealed that 72% of the injuries did not involve contact with other players at the assumed time of injury.  It was also noted that some of the ACL injuries occurred shortly after foot contact with the ground with the knee near full extension.  This finding supports the notion that improper biomechanics of jumping and landing in basketball are direct contributors to this elevated non-contact injury rate.

This research demonstrates the importance as a coach or athletic trainer to teach and enforce proper jumping and landing biomechanics.  The emphasis on technique may assist individuals in decreasing landing forces and thus reduce the chances of sustaining an injury.  Jumping and landing are core biomechanical movements in basketball.  These skills are used in basically all movements on a basketball court including rebounding, defense, and shooting.  They are considered elementary movements and because of this often times not formally taught to children in gym class.  As suggested in the literature, proper biomechanical movement training could help decrease the risk of ACL injury.

The common errors in basketball biomechanics include the following:

1. Tendency to jump and land in a more upright position.



2. Land with knees extended.



3. Land with knees inward.



Proper biomechanics of jumping and landing involves the explosive biomechanics of jumping upward or outward while using the arms and legs.  Landing involves decelerating softly on balls of feet first, then heels while letting the hips and knees absorb the impact from the jump.  Remember that proper landing requires that the body is not upright nor are knees locked or bent inward.  The knees should be bent in line with the toes of the foot and not cross over the toes.

The following cues should be addressed when teaching or instructing a person to jump:

1. Starting position is similar to a squat.  The weight of the body should be on the balls of the feet with knees bent in the squatting position.  Knees should not pass over toes.

2. Maintain good trunk posture by contracting abdominal and gluteal muscles, but don’t forget the arms, legs, feet and core which are all equally important to jumping success.

3. Chest should extend over the knees, while the body remains balanced.

4. Jump upward or outward by straightening hips and knees while driving arms upward to add to the explosive movement from the core and legs.



When landing the following cues should be enforced:

1. Land on the balls of the feet.  Soften the landing by bending the hips and knees with a toe-to-heel rocking of the foot which decreases ground reactive forces.

2. Bending the knees when landing helps to absorb the forces through the muscles in the leg rather than the tendons and ligaments of the knees.

3. Discourage the inward collapse of knees (knock-kneed landing).

4. Keep the chest over the knees.

Avoid the following actions when landing:

1. Single leg landing.



2. Any excessive side-to-side or forward-to-back rocking of the knees upon landing.



3. Knees collapsing inward upon landing.



Look forward to the next article which will take you through a progression of exercises to improve, correct, and/or enhance jumping and landing biomechanics for the basketball athlete.

Cites:
Boden, BP et al. Etiology and Prevention of Noncontact ACL injury. PhysSportsMed. 2000: 29(4).
Hewett, TE et al. The effect of neuromuscular training on the incidence of knee injury in female athletes: a prospective study. Amer J Sports Med 1999. 27(6) 699-706.
Krosshaug et al. Mechanisms of anterior cruciate ligament injury in basketball: video analysis of 39 cases. Am Journal of Sports Medicine. 2006 Mar;35(7):359-67.
McNair, PJ and Prapavessis, HJ.  Effects of instruction in jumping technique and experience jumping on ground reaction forces. Orthop Sports Phys Ther. 1999 Jun; 29(6):352-6.
Olsen et al. Injury mechanisms for anterior cruciate ligament injuries in team handball: a systematic video analysis.  Am J Sports Med. 2004 Jun;32(4):1002-12.