Factors predicting knee function in patients with meniscal lesions

The relationships between the magnitude of strength and muscle activation (EMG activity) deficits during maximal isokinetic knee movements and clinical and anthropometric factors (pain, effusion, type of meniscal lesion, degenerative changes, duration of symptoms and age) were studied in a group of 34 patients 5 days (5.3 ± 6.2 days) before arthroscopic meniscectomy. Moderate correlations were found between deficits in the area under the torque-angle curve (work) and the activation level in the agonist muscles during both the extension and flexion tests at 30° s⁻¹ and 180° s⁻¹ suggesting that the decrease in the isokinetic mechanical output is dependent on the reduced muscle activation. The severity of pain during tests was the best predictive clinical factor for the size of the work and EMG deficits but each of the tollowing factors: the presence of knee effusion and thigh atrophy, the type of meniscal lesion and the age of the patients, also had some predictive value for the magnitude of the deficits. In contrast, the duration of symptoms and the presence of osteo-articular degenerative changes were not related to the preoperative isokinetic knee performance. These results suggest that older patients (especially over 45 yr) with bucket-handle meniscal tears, knee effusion, thigh atrophy and severe pain on exertion, are most likely to have poor preoperative knee isokinetic performance. Since the magnitude of the pre- and postoperative knee deficits are correlated, it is important to identify patients at risk preoperatively so that optimal rehabilitation can be instituted.