Effects of gracilis tendon harvest on in vivo knee joint kinematics

Abstract

Aims and Objectives: The gracilis tendon is a commonly used autologous tendon graft in orthopedic surgery (e.g. anterior cruciate ligament (ACL), medial patellofemoral ligament (MPFL) or chronic acromioclavicular joint (ACJ) reconstruction) but also for example in anal incontinence surgery for formation of a neosphincter. In previous studies the effects of gracilis tendon harvest were analyzed after ACL rupture, its reconstruction and rehabilitation. However, all of these three incidents influence the outcome. Thus, the purpose of the present study was to evaluate the effect of isolated gracilis tendon harvest from uninjured knees on knee kinematics during daily activities. Materials and Methods: Patients between 18 to 60 years with harvest of their gracilis tendon for reconstruction of the ACJ were included. Exclusion criteria were previous surgeries or injuries of their knees. Knee kinematics were evaluated during gait analysis using an infrared optical motion capture system with 10 cameras (T20 S cameras, Vicon, Oxford, United Kingdom) and reflective skin markers. A set of 59 markers was attached on anatomical landmarks of the patients’ lower extremities, pelvis, spine and shoulders with double-sided tape. The position of these markers was tracked at 120 Hz during the trials. Daily activities such as walking and running were performed. Additionally, kick-backs were performed to analyze maximal active knee flexion an important function of gracilis muscle. To quantify the tibiofemoral motion and reduce soft tissue artifacts, the OSSCA (OCST, SARA, and SCoRE combined approach) technique was used. (Boeth 2013) The D’Agostino&Pearson Test was used to test for a Gaussian distribution. For parametric data the dependent t-test, otherwise the Wilcoxon test was used. Results: Sixteen patients were evaluated. However, four had to be excluded after MRIs showed an accidental harvest of the semitendinosus tendon. The mean age was 43 years [standard deviation (SD) 13 years] and time to follow up was 44 months (SD 25). The affected limb showed an increased abduction of 1,38° (SD 4,05; p=0,31) during walking and 0,65° (SD 5,23; p=0,70) during running, as well as an increased rotational translation of 2,26 mm (SD 3,62; p=0,08) during walking and 1,38 mm (SD 3,27; p=0,21) during running. The mean anterior-posterior translation was larger for the healthy limb with 1,15 mm (SD=5,30; p=0,08) during walking and with 2,43 mm (SD=5,99; p=0,23) during running. A larger mean knee flexion angle was measured for the healthy limb during walking, running and kick-backs (mean difference during walking: 3,05°; SD=7,15; p=0,28; running: 2,39°; SD=7,34; p=0,33; kick-backs: 5,31°; SD=8,59; p=0,10). However, none of these results reached statistical significance. Conclusion: These results show that gracilis tendon harvest in healthy knees does not lead to altered knee kinematics. However, the small size of our cohort should be taken into consideration. These data support the use of the gracilis tendon as autologous graft for reconstructive surgery.