Hip Injuries in the Overhead Athlete: The Effect of FAI on Throwing and Swinging

Hip Injuries in the Overhead Athlete:The Effect of FAI on Throwing and Swinging ICL 211: Sports Hip Injuries Wednesday, February 16th, 2011 Bryan T. Kelly, MD Co-Director Center for Hip Pain and Preservation

Bryan T. Kelly, MD Hospital for Special Surgery Disclosure: I DO NOT have a financial interest in any commercial products or service presented in this lecture AND DO NOT INTEND to discuss off label or investigational use of products or services.

Types of financial relationships and the companies with whom I have relationships are as follows: Pivot Medical, Inc.: Consultant A2 Surgical: Consultant Smith & Nephew: Educational Consultant

Introduction • Overhead activities are similar in that the athlete uses torque generated from the feet, hips, and trunk to develop high velocity movements in the upper extremity: • Throwing a baseball • Throwing a football • Shooting a lacrosse ball • Hitting a tennis ball • Hitting a baseball

Hip rotation is a critical component of the movement pattern. Hip loaded pelvis usually rotates over fixed femur creating anterior and medial forces with rotary moments

Is the hip an athletic joint?

Kinematics and Kinetics of hip injuries in athletes Hip loaded pelvis usually rotates over fixed femur creating anterior and medial forces with rotary moments Neuromuscular Research Laboratory University of Pittsburgh

Is the hip an athletic joint? Neuromuscular Research Laboratory University of Pittsburgh More than just hip flexor strains and groin pulls…

LABRAL TEARS • Combine these forces with mechanical impingement…

Phases of the overhead athlete include: • Establishing forward momentum (shuffle step or “crow hop”) • Wind up (rotating the upper torso away from the target) • Striding (lead leg steps toward the target) • Both lower extremities into hip abduction and external rotation • Ground Contact • Lead leg accepts weight to act as a fulcrum

Phases of the overhead athlete include: • Early Acceleration • Pelvis rotates forward in relation to the lead leg. • Late Acceleration • Increase flexion, internal rotation, and adduction of the lead hip • Extension, external rotation, and abduction of the back hip • Follow-through • Distribution of body weight advances onto the lead leg

Mechanics of Overhead Sport • The pattern outlined above will vary depending on the overhead sport and the specific activity within the sport. For example when throwing a baseball, a fielder will have different mechanics than a pitcher. However the movement patterns in overhead sports are similar enough, whether it is baseball, football, lacrosse, or tennis, to consider how the biomechanics could lead to labral-chondral injuries

Femoroacetabular Impingement - Overcoverage Misfit:A common developmental or congenital non spherical femoral head leads to early cartilage wear due to abnormal mechanical stressSquare peg in a round hole….

The two main classifications of FAI are cam and pincer type impingement. Normal Pincer Combination Cam • Femoral Impingement (Cam - 9%) • Acetabular Impingement (Pincer - 5%) • Combined (86%) • Associate labral injury (?100 %) • Beck et al, JBJS-B, 2005

Pincer Impingement Can it be managed arthroscopically?

Chondral Injury - Pincer ContreCoup Injury FH Lever Out Post Head CM & Post Labral Pathology 31% Post-Inf Acet Cartil Rough 62% Post-Inf FH Cartilage Damage Beck et al., 2005; LOE - III Video Courtesy of Marc Safran

Cam Video Courtesy of Marc Safran

Labral Tears - CAM Video Courtesy of Marc Safran

Cam impingement = loss of femoral-head neck offset • Anterior / Anterolateral • Superior / Superolateral • Posterior • Inferior • Any combination (circumferential loss of the femoral head-neck offset)

The labrum will be susceptible to injury when compressed by the cam deformity. The specific location of injury will depend upon the location of the deformity and the direction the hip is moved. Cam deformities are most often found at the anterior-superior head-neck junction.

Biomechanically, a cam deformity at the anterior-superior femoral head-neck junction will compress the anterior-superior labrum during hip internal rotation with flexion and adduction. • Head-neck deformities that are located superiorly can cause superior labral lesions with hip abduction. • Posterior head-neck deformities can cause posterior-superior labral lesions with hip external rotation in extension.

Inferior-medial cam lesion will impinge the anterior labrum during straight plane flexion. Since cam deformities may not be isolated to one specific location, a combination of movements may result in the greatest approximation of the cam deformity with the acetabulum and labrum causing labral-chondral damage across multiple regions.

Rotational Deformity • In addition to cam and pincer type FAI, mechanical impingement may be caused by rotational deformities of the femur in the transverse plane.

Instability • Excessive repetitive forceful hip rotation can contribute to focal rotational instability. The most common injury pattern is repetitive forceful hip external rotation beyond the limit of normal motion leading to iliofemoral ligament laxity.

MECHANICS OF OVERHEAD SPORTS • Overhead throwing and swinging sports may increase the potential for labral tears associated with FAI and instability. • The axial and torsional forces under loading may further predispose overhead athletes to traumatic labral pathology. The positional requirements and movement patterns for the athlete involved in overhead sports incorporate movements that could cause the boney deformities associated with FAI to abut the labrum leading to injury.

MECHANICS OF OVERHEAD SPORTS • Additionally, these movement patterns require excessive rotation that could lead to rotational instability. During different phases of an overhead activity the labrum and capsuloligamentous structures will be at risk for injury.

MECHANICS OF OVERHEAD SPORTS • Wind-Up: open-chain adduction-internal rotation to abduction-external rotation through an arc of flexion toward the intended target. • The athlete is at a potential risk for labral impingement during this motion, especially in the presence of an anterior-superior cam deformity, excessive acetabular retroversion, femoral retroversion, global acetabular overcoverage, and superior focal acetabular overcoverage.

Wind-Up • The “wind-up” phase with the lead leg moving through open-chain adduction-internal rotation to abduction-external rotation through an arc of flexion.

MECHANICS OF OVERHEAD SPORTS • Striding: abduction and external rotation will occur in both the lead and back hips. • The potential for injury with this movement pattern include posterior-superior impingement in both hips. The risk factors for this type of impingement include posterior-superior cam, excessive acetabular anteversion, excessive femoral anteversion, global overcoverage, and superior focal acetabular over coverage. Striding forward is critical to developing forward momentum.

Striding • Striding forward requires abduction and external rotation occurring in both the lead and back hips.

MECHANICS OF OVERHEAD SPORTS • Acceleration: pelvis rotates forward in relation to the lead leg. • As the pelvis rotates forward the lead hip will move into internal rotation and adduction with trunk and hip flexion occurring as the movement progresses forward. Hip flexion, internal rotation, and adduction will put individual at risk for anterior-superior impingement as the head-neck junction approximates the anterior-superior rim of the acetabulum. As noted above the risk factors for this injury include anterior -superior cam, excessive acetabular retroversion, femoral retroversion, global overcoverage, and superior focal acetabular over coverage.

Acceleration • Acceleration phase of throwing with lead hip moving into internal rotation and adduction and the back hip continuing into external rotation, abduction, and extension.

MECHANICS OF OVERHEAD SPORTS • Follow-through phase: the distribution of body weight is moved predominantly onto the lead or non-dominant side with increases in flexion, internal rotation, and adduction. • As the lead leg the hip moves into internal rotation, flexion, and adduction, there is greater risk for anterior-superior impingement as mentioned previously. Additionally, sports that require excessive hip internal rotation may be at risk for posterior rotation instability when the risk factors of a shallow acetabulum, excessive acetabular retroversion, and femoral retroversion are present.

MECHANICS OF OVERHEAD SPORTS • The follow-through phase with increasing in flexion, internal rotation, and adduction on the lead or non-dominant side.

MECHANICS OF OVERHEAD SPORTS • Excessive hip internal rotation, seen with shooting a lacrosse ball, may increase the risk for posterior rotation instability as well as anterior-superior impingement.

Compensatory Injuries Up the Kinetic Chain • While deformities such as FAI and laxity can be linked to intra-articular hip problems, the abnormal mechanics caused by these deformities may lead to abnormal movement patterns in the torso and upper extremity. • Although upper extremity injuries are more common than hip injuries, pathological stress on the torso, shoulder, and elbow may be a result of poor hip mechanics in overhead activities.

Compensatory Injuries Up the Kinetic Chain • The importance of generating forward momentum by the lower extremity in throwing has been documented. If the optimal stride distance and lead leg foot placement does not occur because of decreased strength, restricted range of motion, pain, and/or apprehension in the lead or back hip, an overhead athlete will not be able to properly generate torque form pelvis and lower extremity.

Compensatory Injuries Up the Kinetic Chain • Hip pathology can be associated with decreased hip abductor strength and if the muscles around the hip are not functioning properly, there may be increase stress on shoulder and elbow. • A loss of normal hip motion may also require compensations that lead to pathology in the torso and upper extremity. Decreased internal rotation range of motion in the lead hip was linked to low back problems in athletes participating in tennis.

Compensatory Injuries Up the Kinetic Chain • A study in athletes playing baseball found that hip rotation range of motion was less in back leg in those with history of shoulder pathology. A loss of internal rotation could limit the ability of the hip to absorb stress during follow-through. This may put greater stress on the shoulder. The link between hip pathology, changes in movement pattern, and injury risk in the torso, shoulder, and elbow will require further study.

Conclusion • While overhead sports are commonly linked with injuries of the upper extremity, there has become a greater awareness of injuries to the hip. Many of the common movements associated with throwing a baseball, throwing a football, shooting a lacrosse ball, and hitting a tennis ball place high demands on the hip and put the overhead athlete at risk for injury. Particularly labral-chondral lesions related to FAI and rotational instability.

Compensatory Injuries Up the Kinetic Chain • A study in athletes playing baseball found that hip rotation range of motion was less in back leg in those with history of shoulder pathology. A loss of internal rotation could limit the ability of the hip to absorb stress during follow-through. This may put greater stress on the shoulder. The link between hip pathology, changes in movement pattern, and injury risk in the torso, shoulder, and elbow will require further study.

Thank You

Hip Injuries in the Overhead Athlete: The Effect of FAI on Throwing and Swinging