Association between sensory function and hop performance and self-reported outcomes in patients with anterior cruciate ligament injury

BACKGROUND In patients with anterior cruciate ligament (ACL) deficiency (ACLD) or reconstruction (ACLR), sensory deficits are commonly assessed as knee kinesthesia using time-consuming laboratory equipment. Portable equipment such as that used for evaluation of vibration sense would be preferable. In contrast to kinesthesia, vibration sense is not well studied in these patients. OBJECTIVES 1) To study the association between kinesthesia and vibration sense to investigate if one sensory measurement can replace the other; and 2) to determine the clinical relevance by investigating associations between the sensory measurements and functional performance and patient-reported outcomes in patients with ACLD or ACLR. METHODS Twenty patients with ACLD and 33 patients with ACLR were assessed with knee kinesthesia, vibration sense, the one-leg hop test for distance, as well as the Knee injury and Osteoarthritis Outcome Score (KOOS) and the Tegner Activity Scale. RESULTS There were no significant correlations between kinesthesia and vibration sense (r= -0.267, p>0.269) or between the sensory measures and hop performance (r= -0.351, p>0.199). In patients with ACLD, worse knee kinesthesia was associated with worse scores on KOOS subscales pain (r= -0.464, p=0.046) and activities of daily living (r= -0.491, p=0.033), and worse vibration sense was associated with worse scores on KOOS subscale quality of life (r= -0.469, p=0.037) and worse knee confidence (item Q3 from subscale quality of life) (rs=0.436, p=0.054). In patients with ACLR, worse vibration sense was associated with worse scores on KOOS subscales pain (r= -0.402, p=0.020) and activities of daily living (r= -0.385, p=0.027). CONCLUSION Kinesthesia and vibration sense cannot be used interchangeably as measures of sensory function in patients with ACLD or ACLR. Both sensory measurements were weakly related to hop performance. Adequate sensory function appears to have importance for perceived function in patients with ACLD or ACLR and may therefore be a factor that needs to be addressed in rehabilitation programs for these patients.