Biceps Femoris Compensates for Semitendinosus After Anterior Cruciate Ligament Reconstruction With a Hamstring Autograft: A Muscle Functional Magnetic Resonance Imaging Study in Male Soccer Players

Abstract

Background: Rates of reinjury, return to play (RTP) at the preinjury level, and hamstring strain injuries in male soccer players after anterior cruciate ligament reconstruction (ACLR) remain unsatisfactory, due to multifactorial causes. Recent insights on intramuscular hamstring coordination revealed the semitendinosus (ST) to be of crucial importance for hamstring functioning, especially during heavy eccentric hamstring loading. Scientific evidence on the consequences of ST tendon harvest for ACLR is scarce and inconsistent. This study intended to investigate the repercussions of ST harvest for ACLR on hamstring muscle function. Hypothesis: Harvest of the ST tendon for ACLR was expected to have a significant influence on hamstring muscle activation patterns during eccentric exercises, evaluated at RTP in a population of male soccer athletes. Study Design: Controlled laboratory study. Methods: A total of 30 male soccer players with a history of ACLR who were cleared for RTP and 30 healthy controls were allocated to this study during the 2018-2019 soccer season. The influence of ACLR on hamstring muscle activation patterns was assessed by comparing the change in T2 relaxation times [ΔT2 (%) = [Formula: see text]] of the hamstring muscle tissue before and after an eccentric hamstring loading task between athletes with and without a recent history of ACLR through use of muscle functional magnetic resonance imaging, induced by an eccentric hamstring loading task between scans. Results: Significantly higher exercise-related activity was observed in the biceps femoris (BF) of athletes after ACLR compared with uninjured control athletes (13.92% vs 8.48%; P = .003), whereas the ST had significantly lower activity (19.97% vs 25.32%; P = .049). Significant differences were also established in a within-group comparison of the operated versus the contralateral leg in the ACLR group (operated vs nonoperated leg: 14.54% vs 11.63% for BF [ P = .000], 17.31% vs 22.37% for ST [ P = .000], and 15.64% vs 13.54% for semimembranosus [SM] [ P = .014]). Neither the muscle activity of SM and gracilis muscles nor total posterior thigh muscle activity (sum of exercise-related ΔT2 of the BF, ST, and SM muscles) presented any differences in individuals who had undergone ACLR with an ST tendon autograft compared with healthy controls. Conclusion: These findings indicate that ACLR with a ST tendon autograft might notably influence the function of the hamstring muscles and, in particular, their hierarchic dimensions under fatiguing loading circumstances, with increases in relative BF activity contribution and decreases in relative ST activity after ACLR. This between-group difference in hamstring muscle activation pattern suggests that the BF partly compensates for deficient ST function in eccentric loading. These alterations might have implications for athletic performance and injury risk and should probably be considered in rehabilitation and hamstring injury prevention after ACLR with a ST tendon autograft.

Angle‐specific analysis of knee strength deficits after ACL reconstruction with patellar and hamstring tendon autografts

“…Baumgart, Welling, Hoppe, Freiwald, and Gokeler 21 used phase‐specific SPM analysis over a reduced knee range of motion in 38 team sports athletes with hamstring graft ACL reconstructions, finding that the largest difference in knee flexion torque between operated and non‐operated limbs occurred at >75° knee flexion. The results from our study would suggest that these finding are graft‐specific and cannot be extrapolated to BPTB grafts, which have significantly less inter‐limb asymmetry (10% vs. 17%), improved torque throughout range and maximal asymmetry at a 38 more‐extended knee angle than HT grafts. Significant differences in knee angles at the point of greatest knee flexion asymmetry were observed between graft types (Figure 4).…”

“…It can be postulated that the difference observed at higher knee flexion angles are due to the impairment that occurs when the semitendinosus and gracilis tendons are harvested for HT grafts. There is evidence of individualized levels of tendon regeneration and an over development of bicep femoris hypertrophy, with patients with reduced or no regeneration demonstrating the highest levels of knee flexor strength deficit 38,39 . Furthermore, angle‐specific knee flexor deficits at 70° and 90° have been demonstrated in athletes with reduced semitendinosus cross sectional area 40 .…”

“…There is evidence of individualized levels of tendon regeneration and an over development of bicep femoris hypertrophy, with patients with reduced or no regeneration demonstrating the highest levels of knee flexor strength deficit. 38,39 Furthermore, angle-specific knee flexor deficits at 70° and 90° have been demonstrated in athletes with reduced semitendinosus cross sectional area. 40 This would support why the largest inter limb deficits are observed at deeper knee flexion angles as the bicep femoris is in a mechanically disadvantaged position and thus has reduced force production whilst decreased hypertrophy and cross sectional area of the semitendinosus muscle mean that strength in this knee flexion angle is reduced.…”

Shape differences in the semitendinosus following tendon harvesting for anterior cruciate ligament reconstruction

“…Nonuniform changes in muscle shape, which we have identified to occur in this study, may also contribute to altered coordination and load sharing amongst synergist knee flexors (e.g., hamstrings). Consistent with this notion, Tampere et al 29 found male soccer players who returned to sport following ST ACLR had relatively greater biceps femoris and relatively less ST activity during a fatiguing leg curl test compared to uninjured controls. Previous observations in healthy uninjured soccer players suggested reduced reliance on ST associated with reduced knee flexor strength‐endurance 29 and a significantly greater risk of hamstring strain injury in the subsequent 18 months 29,30 .…”

“…Consistent with this notion, Tampere et al 29 found male soccer players who returned to sport following ST ACLR had relatively greater biceps femoris and relatively less ST activity during a fatiguing leg curl test compared to uninjured controls. Previous observations in healthy uninjured soccer players suggested reduced reliance on ST associated with reduced knee flexor strength‐endurance 29 and a significantly greater risk of hamstring strain injury in the subsequent 18 months 29,30 . Furthermore, patients who receive a semitendinosus autograft ACLR are at ~2.5 times greater risk of ipsilateral ACL reinjury compared to other ACLR autograft choices 31–33 .…”