Knee extension and flexion muscle power after anterior cruciate ligament reconstruction with patellar tendon graft or hamstring tendons graft: A cross-sectional comparison 3 years post surgery

Department of Orthopedics, Clinical Sciences Lund, Lund University, Lund University Hospital, Lund 221 85, Sweden.
Knee Surgery Sports Traumatology Arthroscopy (Impact Factor: 2.84). 11/2008; 17(2):162-9. DOI: 10.1007/s00167-008-0645-4
Source: PubMed

ABSTRACT Hamstring muscles play a major role in knee-joint stabilization after anterior cruciate ligament (ACL) injury. Weakness of the knee extensors after ACL reconstruction with patellar tendon (PT) graft, and in the knee flexors after reconstruction with hamstring tendons (HT) graft has been observed up to 2 years post surgery, but not later. In these studies, isokinetic muscle torque was used. However, muscle power has been suggested to be a more sensitive and sport-specific measures of strength. The aim was to study quadriceps and hamstring muscle power in patients with ACL injury treated with surgical reconstruction with PT or HT grafts at a mean of 3 years after surgery. Twenty subjects with PT and 16 subjects with HT grafts (mean age at follow up 30 years, range 20-39, 25% women), who were all included in a prospective study and followed the same goal-based rehabilitation protocol for at least 4 months, were assessed with reliable, valid, and responsive tests of quadriceps and hamstring muscle power at 3 years (SD 0.9, range 2-5) after surgery. The mean difference between legs (injured minus uninjured), the hamstring to quadriceps (H:Q, hamstring divided by quadriceps) ratio, and the limb symmetry index (LSI, injured leg divided by uninjured and multiplied by 100) value, were used for comparisons between the groups (analysis of variance). The mean difference between the injured and uninjured legs was greater in the HT than in the PT group for knee flexion power (-21.3 vs. 7.7 W, p = 0.001). Patients with HT graft had lower H:Q ratio in the injured leg than the patients with PT graft (0.63 vs. 0.77, p = 0.012). They also had lower LSI for knee flexion power than those in the PT group (88 vs. 106%, p < 0.001). No differences were found between the groups for knee extension power. The lower hamstring muscle power, and the lower hamstring to quadriceps ratio in the HT graft group than in the PT graft group 3 years (range 2-5) after ACL reconstruction, reflect imbalance of knee muscles after reconstruction with HT graft that may have a negative effect on dynamic knee-joint stabilization.

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    • "The KOOS survey has been validated [24] and contains five separate subscales; (i) Pain, (ii) Other Symptoms, (iii) Function in daily living (ADL), (iv) Function in Sport and Recreation (Sport/Rec), and (v) joint related Quality of Life (QOL) [22] [23]. Sport/Rec and QOL were the only KOOS subscales that were analyzed in the present study, since these two subscales are most dominantly affected by ACL-injury [17] [25] and also are the subscales most frequently studied in the research setting [16] [17]. Prior to testing patients performed a standardized warm-up program consisting of two repetitions of 10 toe rises, 10 bilateral squats, 10 unilateral squats (for each leg) and two to three submaximal vertical jumps (Countermovement jumps: CMJ). "
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    ABSTRACT: An abstract is unavailable. This article is available as HTML full text and PDF.
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