The purposes of this study was 1) to assess the plantar flexion and dorsiflexion peak
torques (PT) of the ankles at 30, 90 and 240° · s-1 in 101 patients (86 men, 15 women) who> had been operated on for unilateral, complete
closed Achilles tendon (AT) rupture at Oulu University Hospital, Oulu, Finland, in
the period 1987 - 1992, 2) to determine whether comparison between the legs shows
any impairment, 3) to study whether the weakness is speed-dependent, 4) to determine
at what angular displacement of the ankle the weakness is manifested, 5) to study
how the results correlate with age, type of operation and follow-up time. The Lido
Multi-joint II dynamometer was used for the measurements. There was no significant
dorsiflexion weakness detectable upon comparison between the legs, but the mean relative
peak torque deficits in the injured limb were 8.4, 9.0 and 3.0 % at 30, 90 and 240°
· s-1 respectively for the men and 15.0, 16.6 and 6.4 % for the women. The mean percentage
torque differences were significantly greater in the women at all the test speeds
(p < 0.05). The difference in PT was significantly greater at the two low test speeds
(30 and 90° · s-1) than at the high speed (240° · s-1, p < 0.001). The weakness was manifested at an angular displacement of 80-120 degrees,
where the average peak work (PW) difference between the two legs was significant in
both sexes (p<0.05). The patient's age (21 -63), true type of operation (Lindholm
or Silfverskiöld technique) and the follow-up time (0.7 - 6.7 years) did not significantly
affect the results. In conclusion, an AT rupture implied an average 3.0 to 116.6 %
impairment in isokinetic plantar flexion muscle strength. The impairment was greater
in the women, was manifested at an angular displacement of 80-120 degrees, and was
greater at low test speeds. Age, type of operation and follow-up time did not account
for the PT differences between the patients.
Key words
Achilles tendon rupture - peak torque - peak torque angle - peak work
