Abstract Discussion - Kinematic and Kinetic Analysis of Three Tennis ServeTypes Using a Markerless System

PRESENTED AT THE 2011 ANNUAL STMS CONGRESS

Geoffrey D. Abrams MD1, Alison L. Sheets PhD4, Stefano Corazza PhD2, Alex H. Sox-Harris PhD5, |Thomas P. Andriacchi PhD1,2,3, Marc R. Safran MD1

1Stanford University, Department of Orthopedic Surgery, Stanford CA

2Stanford University, Department of Mechanical Engineering, Stanford CA

3Bone and Joint Center, VA Palo Alto Health Care System, Palo Alto, CA

4Ohio State University, Department of Mechanical and Aerospace Engineering, Columbus, OH

5Center for Health Care Evaluation, VA Palo Alto Health Care System, Palo Alto, CA

Corresponding Author

Marc R. Safran, MD

Running Title: Biomechanical evaluation of three serve types

Disclosures: No outside funding was received for this investigation

Abstract

Purpose: The tennis serve is commonly associated with musculoskeletal injury. We sought to evaluate the mechanics of the back, shoulder, elbow, and wrist during the flat, kick, and slice serves using a markerless system. We hypothesized that joints which show larger angles and/or velocities experience greater forces and torques. We further hypothesized that the elbow and wrist experience higher forces and torques during flat serves versus the kick and slice serves.

Methods: Seven NCAA Division I male tennis players performed three successful flat, kick, and slice serves. Serves were recorded using an eight camera markerless system. Laser scanning was utilized to accurately collect body dimensions and data was computed using inverse kinematic methods.

Results: The kick serve had a higher force magnitude at the back than the flat and slice (2974N vs. 2138N vs. 2568N; p < 0.05) as well as larger posteriorly directed shoulder forces (1370 N vs. 809 N vs. 741 N; p < 0.03). The slice demonstrated a lower magnitude of torque at the elbow (71.1 vs. 87.0 vs. 89.3 N-m; p = 0.13) and wrist (20.9 vs. 33.5 vs. 27.9 N-m; p < 0.09) compared to the flat and kick serves.

Conclusion: The kick serves may place higher stresses on the back and shoulder, potentially increasing the risk of injury. The slice serve has the lowest forces and torques at the elbow and wrist, suggesting the least risk of injury to these joints with this serve. This information may have injury prevention and rehabilitation implications.

Key Words: biomechanics, flat, kick, slice, injury