Associations Among Quadriceps Strength and Rate-of-Torque Development 6 Weeks Post Anterior Cruciate Ligament Reconstruction and Future Hop and Vertical Jump Performance: A Prospective Cohort Study

Context: To quantify quadriceps weakness after anterior cruciate ligament reconstruction (ACLR), researchers have often analyzed only peak torque. However, analyzing other characteristics of the waveform, such as the rate of torque development (RTD), time to peak torque (TTP), and central activation ratio (CAR), can lend insight into the underlying neuromuscular factors that regulate torque development. Objective: To determine if interlimb neuromuscular asymmetry was present in patients with ACLR at the time of clearance to return to activity. Design: Cross-sectional study. Setting: Laboratory. Patients or Other Participants: A total of 10 individuals serving as controls (6 men, 4 women; age = 23.50 ± 3.44 years, height = 1.73 ± 0.09 m, mass = 71.79 ± 9.91 kg) and 67 patients with ACLR (43 men, 24 women; age = 21.34 ± 5.73 years, height = 1.74 ± 0.11 m, mass = 77.85 ± 16.03 kg, time postsurgery = 7.52 ± 1.36 months) participated. Main Outcome Measure(s): Isokinetic (60°/s) and isometric quadriceps strength were measured. Peak torque, TTP, and RTD were calculated across isometric and isokinetic trials, and CAR was calculated from the isometric trials via the superimposed burst. Repeated-measures analyses of variance were used to compare limbs in the ACLR and control groups. Results: No between-limbs differences were detected in the control group (P > .05). In the ACLR group, the involved limb demonstrated a longer TTP for isokinetic strength (P = .04; Cohen d effect size [ES] = 0.18; 95% confidence interval [CI] = −0.16, 0.52), lower RTD for isometric (P < .001; Cohen d ES = 0.73; 95% CI = 0.38, 1.08) and isokinetic (P < .001; Cohen d ES = 0.84; 95% CI = 0.49, 1.19) strength, lower CAR (P < .001; Cohen d ES = 0.37; 95% CI = 0.03, 0.71), and lower peak torque for isometric (P < .001; Cohen d ES = 1.28; 95% CI = 0.91, 1.65) and isokinetic (P < .001; Cohen d ES = 1.15; 95% CI = 0.78, 1.52) strength. Conclusions: Interlimb asymmetries at return to activity after ACLR appeared to be regulated by several underlying neuromuscular factors. We theorize that interlimb asymmetries in isometric and isokinetic quadriceps strength were associated with changes in muscle architecture. Reduced CAR, TTP, and RTD were also present, indicating a loss of motor-unit recruitment or decrease in firing rate.

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STRONGER THAN EVER! ADOLESCENT ATHLETES SHOW STRENGTH GAINS WITHIN THE UNINJURED LEG AFTER ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION

Orthopaedic Journal of Sports Medicine ◽

10.1177/2325967121s00050 ◽

2021 ◽

Vol 9 (7_suppl3) ◽

pp. 2325967121S0005

Author(s):

Elliot Greenberg ◽

Joshua Bram ◽

Theodore Ganley

Keyword(s):

Anterior Cruciate Ligament ◽

Anterior Cruciate Ligament Reconstruction ◽

Ligament Reconstruction ◽

Cruciate Ligament ◽

Cohort Analysis ◽

Peak Torque ◽

Quadriceps Strength ◽

Strength Assessment ◽

Cruciate Ligament Reconstruction ◽

Anterior Cruciate

Background: The restoration of quadriceps strength after anterior cruciate ligament reconstruction (ACLR) is critical to restore optimal patient function and reduce the incidence of secondary ACL injury. Strength is typically quantified during return to sport assessments, by comparing the strength in the involved limb to that of the uninvolved limb. A limb symmetry index (LSI) is calculated and used to determine if any residual strength deficits persist. Recent evidence demonstrates that the uninvolved limb may lose strength during ACLR recovery and suggests that pre-operative uninvolved limb strength values may offer a better representation and more stringent indicator of strength recovery after ACLR. However, this body of literature is limited and no studies have specifically evaluated this occurrence within youth athletes. Purpose: To evaluate the change in strength in the uninvolved limb from pre-operative to 6 months post-ACLR, and assess the effect of pre-operative strength comparison on 6-month post-op LSI. Methods: A retrospective cohort analysis of pediatric patients (≤18 years) undergoing primary ACLR from 1/2018-1/2020 without concomitant multi-ligamentous reconstruction was conducted. Isokinetic peak torque values for the uninvolved and involved quadriceps were extracted at pre-operative (uninvolved only) and 6 months post-operative. Strength changes were analyzed using paired-samples t-test. Results: Complete data was available for a total of 17 subjects (mean age 15.1±1.7, 53% female). Pre-operative strength assessment was performed a mean of 11.5 days (range 1-26) prior to surgery. The mean 6-month post-operative assessment occurred at 177 days (range 127-246). The uninvolved limb was significantly stronger (p<0.001) at 6 months compared to preoperatively, with a mean improvement of 12.1ft/lbs (95%CI 18.3 – 7.2) with a change from 82.4ft/lbs to 95.1 ft/lbs. The LSI was calculated using both pre-operative and 6-month post-operative uninvolved limb values and demonstrated substantially lower LSI values when using concurrent 6-month data (LSIpre 91.3% vs LSI6M 76.9%). Conclusions: Among this sample, the uninvolved limb got stronger during post-ACLR recovery and comparison to concurrently assessed strength values led to a more stringent determination of LSI. Differences in rehabilitation programming, adolescent physiology, and pre-injury training patterns may explain why these results differ than those found in older cohorts.

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Factors affecting quadriceps strength recovery after anterior cruciate ligament reconstruction with hamstring autografts in athletes

Knee Surgery Sports Traumatology Arthroscopy ◽

10.1007/s00167-016-4296-6 ◽

2016 ◽

Vol 25 (10) ◽

pp. 3213-3219 ◽

Cited By ~ 18

Author(s):

Yuya Ueda ◽

Takehiko Matsushita ◽

Daisuke Araki ◽

Akihiro Kida ◽

Kohei Takiguchi ◽

...

Keyword(s):

Anterior Cruciate Ligament ◽

Anterior Cruciate Ligament Reconstruction ◽

Ligament Reconstruction ◽

Cruciate Ligament ◽

Quadriceps Strength ◽

Factors Affecting ◽

Cruciate Ligament Reconstruction ◽

Strength Recovery ◽

Anterior Cruciate

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The hybrid anterior cruciate ligament reconstruction surgical technique does permit an accelerated early functional recovery and return to sport.

Orthopaedic Journal of Sports Medicine ◽

10.1177/2325967117s00177 ◽

2017 ◽

Vol 5 (5_suppl5) ◽

pp. 2325967117S0017

Author(s):

Peter Annear ◽

Ebert Jay

Keyword(s):

Anterior Cruciate Ligament ◽

Ligament Reconstruction ◽

Cruciate Ligament ◽

Return To Sport ◽

Quadriceps Strength ◽

Hamstring Graft ◽

Cruciate Ligament Reconstruction ◽

Hop Tests ◽

Anterior Cruciate ◽

Tegner Score

Objectives: A major reason for undergoing anterior cruciate ligament reconstruction (ACLR) for patients is to return to high demand activity and sport. Published literature supports a return to sport (RTS) at 6-12 months, though the recovery of lower limb strength and functional symmetry is critical and is linked with a patient’s ability to RTS, as well as reducing the incidence of secondary re-tear. This study aimed to compare clinical outcomes and RTS between patients undergoing ACLR utilizing a hamstring graft and those undergoing a hybrid technique which augments the hamstring graft with a synthetic LARS ligament. Methods: A non-randomized study design was used to compare clinical outcomes at 10-12 months post-surgery, in 82 patients undergoing conventional ACLR via a hamstring graft (HG) and 35 patients undergoing a hybrid hamstring/LARS graft (HLG). All patients were assessed using a range of patient-reported outcome (PRO) scores (IKDC, KOOS, Cinncinati, Lysholm, SF-36, Tegner, Noyes, Global Rating of Change – GRC). Limb symmetry indices (LSIs) presenting the operated limb as a percentage of the unaffected limb were calculated for several strength/functional assessments (peak isokinetic quadriceps and hamstring strength, the single, triple and triple crossover hop for distance, and the 6 m timed hop). Results: There were no group differences (p>0.05) in patient demographics and the majority of PROs. The HLG group perceived themselves to be significantly ‘more recovered’ (p=0.046) on the GRC scale (HLG = 3.2, HG = 2.2), and also reported a significantly greater (p=0.004) Tegner score (HLG = 7.2, HG = 5.9). For the HG group, 62% of patients had returned to Noyes Level 1 or 2 activities, versus 80% of the HLG group. For the Tegner score, 57% of patients reported a score >6, versus 77% of the HLG group. There were no significant differences (p>0.05) in LSIs between groups for the strength and functional hop tests. However, the HLG group demonstrated a mean LSI above 90% for all four hop tests, while all four were below 90% in the HG group. Both groups demonstrated mean hamstring strength LSIs above 90%, while the quadriceps strength LSI was 81.9% and 85.8% for the HG and HLG groups, respectively. Conclusion: Patients in the HLG group perceived themselves to be more recovered, and had returned to a higher level of activity/sport, compared with the HG group. While not significant, the HLG group did demonstrate more favorable functional hop and quadriceps strength LSIs, which has been linked with the ability to RTS and the incidence of ACL re-tear. A larger patient cohort and follow-up is required to observe long-term outcomes.

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