Weight discrimination after anterior cruciate ligament injury: a pilot study.
OBJECTIVE
To determine whether the ability to discriminate weights remained accurate after anterior cruciate ligament (ACL) injury.


METHODS
Descriptive case series.


METHODS
Outpatient physical therapy.


METHODS
Convenience sample of 10 participants with unilateral ACL injuries (age, 27.1+/-8.2 y) and 8 healthy controls (age, 22.6+/-2.8 y).


METHODS
Not applicable.


METHODS
Weber fractions, expressed as percentage differences from the standard weight (3.00 kg) that could be reliably detected (75% correct level), were derived from each leg to provide an index of proprioceptive acuity for weight discrimination. Subjective ratings of knee function (Activities of Daily Living Scale of the Knee Outcome Survey) and measurements of quadriceps strength (peak isometric torque).


RESULTS
The ACL group exhibited a reduced acuity to detect differences in weight on the injured, as compared with the uninjured, side as reflected in the increase in Weber fractions (mean, 6.7%+/-2.3% vs 4.8%+/-1.1%, respectively; P = .043). No such difference in acuity between legs was detected in healthy controls (mean right and left, 5.4%+/-1.4% vs 5.7%+/-1.3%, respectively, P = .99).


CONCLUSIONS
Proprioceptive acuity for weight discrimination was significantly reduced after an ACL injury, possibly reflecting deficits in the ability to properly calibrate force signals generated while muscles are actively contracting, as a result of a loss in ligamentous sensory innervation.
School of Rehabilitation Sciences, Faculty of Health Sciences, University of Ottawa, Ontario, Canada.
Martin E
ME
Héroux
François
F
Tremblay
D000203:Activities of Daily Living; D000328:Adult; D016118:Anterior Cruciate Ligament / Q000503:physiopathology*; D000070598:Anterior Cruciate Ligament Injuries; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D007717:Knee / Q000503:physiopathology; D008297:Male; D018482:Muscle, Skeletal / Q000503:physiopathology; D010865:Pilot Projects; D011434:Proprioception / Q000502:physiology; D014891:Weight Lifting / Q000502:physiology; D014892:Weight Perception / Q000502:physiology*