Running Biomechanics Before Injury and 1 Year After Anterior Cruciate Ligament Reconstruction in Division I Collegiate Athletes

Abstract

Background: Preinjury running biomechanics are an ideal comparator for quantifying recovery after anterior cruciate ligament (ACL) reconstruction (ACLR), allowing for assessments within the surgical and nonsurgical limbs. However, availability of preinjury running biomechanics is rare and has been reported in case studies only. Purpose/Hypothesis: The purpose of this study was to determine if running biomechanics return to preinjury levels within the first year after ACLR among collegiate athletes. We hypothesized that (1) surgical knee biomechanics would be significantly reduced shortly after ACLR and would not return to preinjury levels by 12 months and (2) nonsurgical limb mechanics would change significantly from preinjury. Study Design: Cohort study; Level of evidence, 2. Methods: Thirteen Division I collegiate athletes were identified between 2015 and 2020 (6 female; mean ± SD age, 20.7 ± 1.3 years old) who had whole body kinematics and ground-reaction forces recorded during treadmill running (3.7 ± 0.6 m/s) before sustaining an ACL injury. Running analyses were repeated at 4, 6, 8, and 12 months (4M, 6M, 8M, 12M) after ACLR. Linear mixed effects models were used to assess differences in running biomechanics between post-ACLR time points and preinjury within each limb, reported as Tukey-adjusted P values. Results: When compared with preinjury, the surgical limb displayed significant deficits at all postoperative assessments ( P values <.01; values reported as least squares mean difference [SE]): peak knee flexion angle (4M, 13.2° [1.4°]; 6M, 9.9° [1.4°]; 8M, 9.8° [1.4°]; 12M, 9.0° [1.5°]), peak knee extensor moment (N·m/kg; 4M, 1.32 [0.13]; 6M, 1.04 [0.13]; 8M, 1.04 [0.13]; 12M, 0.87 [0.15]; 38%-57% deficit), and rate of knee extensor moment (N·m/kg/s; 4M, 22.7 [2.4]; 6M, 17.9 [2.3]; 8M, 17.5 [2.4]; 12M, 16.1 [2.6]; 33%-46% deficit). No changes for these variables from preinjury ( P values >.88) were identified in the nonsurgical limb. Conclusion: After ACLR, surgical limb knee running biomechanics were not restored to the preinjury state by 12M, while nonsurgical limb mechanics remained unchanged as compared with preinjury. Collegiate athletes after ACLR demonstrate substantial deficits in running mechanics as compared with preinjury that persist beyond the typical return-to-sport time frame. The nonsurgical knee appears to be a valid reference for recovery of the surgical knee mechanics during running, owing to the lack of change within the nonsurgical limb.

Changes in Bone Mineral Density of the Femur and Tibia Before Injury to 2 Years After Anterior Cruciate Ligament Reconstruction in Division I Collegiate Athletes

“…16 In weightbearing bones, the strain threshold and disuse-related bone loss tend to be greatest distally, where locomotor forces tend to be highest. 9,13,16 Therefore, differences in BMD observed across sites could be caused, in part, by altered movement mechanics such as reduced knee flexion angles and extensor moments during walking, 8,11,43 running, 22,36 jumping, 24,25 and change of direction tasks, 31 as well as reduced quadriceps strength. 28 Site-specific loss in BMD is multifactorial, likely being influenced by the initial injury, subsequent surgical procedure, local inflammation, period of immobilization, and disuse of the involved lower extremity.…”

Relevant Strength Parameters to Allow Return to Running after Primary Anterior Cruciate Ligament Reconstruction with Hamstring Tendon Autograft

“…Strength deficit may persist for more than 6 months after ACLR, whereas no clinical signs of inflammation, such as pain, swelling, heat, and edema, can be found. A recent and unique study compared the running biomechanics of athletes before an ACL injury and after ACLR [ 29 ]. A deficit of the peak knee flexion angle and knee extensor moment in the operated limb persisted 12 months after ACLR [ 29 ].…”

“…A recent and unique study compared the running biomechanics of athletes before an ACL injury and after ACLR [ 29 ]. A deficit of the peak knee flexion angle and knee extensor moment in the operated limb persisted 12 months after ACLR [ 29 ]. A maximal knee extensor deficit (−57%) was detected 4 months after an ACLR when paradoxically a majority of athletes had already returned to running [ 14 ].…”

“…A maximal knee extensor deficit (−57%) was detected 4 months after an ACLR when paradoxically a majority of athletes had already returned to running [ 14 ]. The kinematic and strength deficits reported on the operated limb led to altered gait patterns and compensations between limbs while walking, running, or squatting [ 29 , 30 , 31 , 32 ]. In addition, the symmetry of the gait pattern and quadriceps strength proved to be associated with a return to sport [ 33 , 34 ], highlighting the importance of evaluating limb symmetry indexes 4 months after ACLR.…”

Knee Strength Assessment and Clinical Evaluation Could Predict Return to Running after Anterior Cruciate Ligament Reconstruction Using Patellar Tendon Procedure

“…From the third month after surgery, running may be possible if a certain degree of symmetrical movement is possible [ 16 , 17 ]. Indeed, quadriceps and hamstring strengths are associated with knee kinematics and kinetics during running [ 18 , 19 , 20 , 21 , 22 ]. Significant correlations were found between isokinetic quadriceps strength and knee extension moment during running [ 20 , 23 ].…”