1995 Albert Trillat Young Investigator's Award Winner:

The Strain Behavior of the Anterior Cruciate Ligament During Bicycling:
An in vivo Study

Braden C. Fleming, Ph.D., Bruce D. Beynnon, Ph.D.,
Per A. Renstrom, M.D., Ph.D., Glenn D. Peura, M.S.,
Claude E. Nichols, Ph.D., Robert J. Johnson, M.D.
McClure Musculoskeletal Research Center
Dept. of Orthopaedics & Rehabilitation
University of Vermont
Burlington, Vermont, USA

Stationary bicycling is thought to be a safe rehabilitation exercise following ACL injury or reconstruction. However, the strains on the ACL or ACL graft during bicycling have not been measured. The objective of this investigation was to measure ACL strain values during bicycling, in vivo, and to determine the effect of power and cadence on the peak ACL strain values.

Eight patients who were candidates for arthroscopic meniscectomy under local anesthesia participated in the study. The Differential Variable Reluctance Transducer (DVRT; Microstain Inc., Burlington, VT) was used to measure ACL strain. The DVRT was inserted and the experiment was performed following the routine surgical procedure. Six different bicycle riding conditions, which spanned the values typically used for ACL rehabilitation, were evaluated; three power levels (75, 125 and 175 Watts) each performed at two cadences (60 and 90 rpms).

No significant differences in peak ACL strain values were found due to changes in power level or cadence. Thus, it was possible to pool the strain values across the riding conditions. The mean peak strain ACL value was 1.7%, a value that was relatively low as compared to the other rehabilitation activities that we previously tested. As a benchmark for the ACL strain value during bicycling, the mean peak strain value produced during a Lachman test (with a 150 N anterior shear load and the knee at 30 degrees of flexion) was 3.5% for these eight patients.

This study suggests that knee rehablitation programs may be designed to include this selection of power and cadence levels without significantly changing ACL strain values. As a rehabilitation activity following ACL injury or reconstruction, stationary bicycling permits the patient to increase muscle activity by increasing the power level or decreasing the cadence without subjecting the ACL to higher strain values.

Albert Trillat Young Investigator's Award Information
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