Lower medial hamstring activity after ACL reconstruction during running: a cross-sectional study

Limb dominance influences landing mechanics and neuromuscular control during drop vertical jump in patients with ACL reconstruction

Objectives

The purpose of this study was to compare the interlimb biomechanical differences in patients who had undergone anterior cruciate ligament reconstruction (ACLR) in either dominant (ACLR-D) or nondominant (ACLR-ND) limbs and healthy controls (CON) during drop vertical jump (DVJ) task. To investigate whether the dominant or nondominant limb influences the risk of re-injury in ACLR patients.

Methods

Thirty-three ACLR patients were divided into ACLR-D and ACLR-ND groups according to whether the surgical limb was dominant or nondominant. Seventeen healthy individuals were selected as the CON group. Three-dimensional kinematic data, ground reaction force (GRF) data, and surface electromyographic (EMG) data from the bilateral lower limbs of all participants were collected during the DVJ task. Two-way repeated-measures ANOVAs (limb × group) were performed on the variables of interest to examine the main effects of limb (dominant vs. nondominant) and group (ACLR-D, ACLR-ND, and CON), as well as the interaction between limb and group.

Results

The nonsurgical limbs of ACLR group had significantly greater knee valgus angles, knee extension and valgus moments, peak posterior GRF (PPGRF), and peak vertical GRF (PVGRF) compared to the surgical limbs. The nonsurgical limbs of ACLR-ND patients demonstrated significantly greater knee extension and valgus moments, greater PPGRF and PVGRF, and reduced muscle activity in the vastus medialis and vastus lateralis compared to the CON group. The ACLR patients had reduced muscle activity in the quadriceps of the surgical limb and the hamstrings of the bilateral limbs compared to controls.

Conclusion

The nonsurgical limbs of ACLR patients may suffer an increased risk of ACL injury due to altered landing mechanics and neuromuscular control strategies compared to the surgical limbs. Additionally, limb dominance influences movement patterns and neuromuscular control during DVJ task, the nonsurgical limbs of the ACLR-ND might be at higher risk of ACL injury compared to the ACLR-D group.

Changes in passive hamstring stiffness after primary anterior cruciate ligament reconstruction: A prospective study with comparison of healthy controls

BACKGROUND

The mechanical properties of knee flexors muscles contribute to reducing anterior cruciate ligament loading. This case-control study evaluated the passive knee flexors stiffness after primary anterior cruciate ligament reconstruction with comparison of healthy controls.

METHODS

After anterior cruciate ligament reconstruction, 88 participants (24.5 [8.6] years, 56,8% males) had two isokinetic tests at 4 and 8 postoperative months with measurement of the passive resistive torque of knee flexors and extensors/flexors strength. In the control group, 44 participants (24.5 [4.3] years, 56,8% males) had one visit with the same procedures. Passive knee flexors stiffness was calculated as the slope of the passive torque-angle curve on the last 10° of knee extension (Nm/°). We investigated the impact of timing and type of surgery (autograft and combined meniscus repair) and persistent knee extension deficits on knee flexors stiffness.

FINDINGS

At 4 and 8 postoperative months, passive knee flexors stiffness was lower on the operated limb than on the non-operated limb (P < 0.001) but both limbs had significant lower values than controls (P < 0.001). Stiffness was positively correlated with knee flexors strength (P < 0.010), and knee flexors stiffness at 4 months was lower in individuals who underwent surgery <6 months from injury (P = 0.040). Knee extension deficit or the type of surgery did not have a significant influence on knee flexors stiffness.

INTERPRETATION

Similarly to neuromuscular factors that are traditionally altered after anterior cruciate ligament reconstruction, evaluating passive knee flexors stiffness changes over time could provide supplementary insights into postoperative muscle recovery.

Neuromuscular activity of the lower-extremities during running, landing and changing-of-direction movements in individuals with anterior cruciate ligament reconstruction: a review of electromyographic studies

PURPOSE

Running, jumping/landing and cutting/change of direction (CoD) are critical components of return to sport (RTS) following anterior cruciate ligament reconstruction (ACLR), however the electromyographic (EMG) activity patterns of the operated leg during the execution of these tasks are not clear.

METHODS

A systematic review was conducted to retrieve EMG studies during running, jumping/landing and cutting/(CoD) in ACLR patients. MEDLINE, PubMed, SPORTDiscus and Web of Science databases were searched from 2000 to May, 2022 using a combination of keywords and their variations: "anterior cruciate ligament reconstruction" OR "ACLR", "electromyography" OR "EMG", "running", "jumping" OR "landing", "cutting" OR "change-of-direction" OR "CoD". The search identified studies comparing EMG data during running, landing and cutting/(CoD) between the involved limb and contralateral or control limbs. Risk of bias was assessed and quantitative analyses using effect sizes were performed.

RESULTS

Thirty two studies met the inclusion criteria. Seventy five percent (24/32) of the studies reported altered EMG activity pattern of the ACLR leg during running, jumping/landing and cutting/(CoD) when compared with either the healthy control leg or the contra-lateral leg. Twelve studies showed decreased, delayed or earlier onset and delayed peak in quadriceps EMG activity with small to large effect sizes and 9 studies showed increased, delayed or earlier onset and delayed peak in hamstrings EMG activity with small to large effect sizes. Four studies showed a "hamstrings-dominant" strategy i.e. decreased quadriceps coupled with increased hamstrings EMG activity in both running and jumping/landing irrespective of graft type. One study reported that on the grounds of decreased quadriceps activity, lower hamstrings EMG activity was predictive of ipsilateral re-injury in ACLR patients.

CONCLUSION

This systematic review of Level III evidence showed that the ACLR leg displays decreased quadriceps or increased hamstrings EMG activity or both despite RTS. Simultaneous decreased quadriceps and increased hamstrings EMG activity was shown for both running and jumping/landing. From a clinical perspective this "hamstrings dominant" strategy can serve as a protective mechanism against graft re-injury.

LEVEL OF EVIDENCE

III.

Harvesting a second graft from the extensor mechanism for revision ACL reconstruction does not delay return of quadriceps function

PURPOSE

The purpose of this study was to evaluate whether harvesting a second graft from the ipsilateral extensor mechanism adversely affects clinical outcomes in revision anterior cruciate ligament (ACL) reconstruction.

METHODS

A retrospective review of 34 patients undergoing revision anterior cruciate ligament (ACL) reconstruction with either quadriceps tendon (QT) autograft or bone-tendon-bone (BTB) autograft was conducted. Patients with two grafts (BTB+QT) from the extensor mechanism were matched based on age, laterality, and sex to patients who had primary reconstruction with hamstring (HS) autograft followed by revision with either BTB or QT autograft (HS+QT/BTB). Return of quadriceps function was assessed with time to return to jogging in a standardized rehab protocol or time to regain 80% quadriceps strength. Secondary outcomes included International Knee Documentation Committee (IKDC) and Marx scores at 12-month follow-up and return to sport.

RESULTS

There were no significant differences in return to jogging or 80% quadriceps strength (HS 149.5 ± 38.2 days, BTB+QT 131.7 ± 40.1 days, n.s.), number able to return to sport (HS 62%, BTB+QT 93%, n.s.), months to return to sport (HS 10.6 ± 1.4, BTB+QT 10.5 ± 2.3, n.s.), return to pre-injury level of competition (HS 62%, BTB+QT 73%, n.s.), or IKDC (HS 77.2 ± 16.4, BTB+QT 74.8 ± 23.9, n.s.) and Marx scores (HS 9.2 ± 5.3, BTB+QT 8.0 ± 3.7, n.s.) at one-year follow-up.

CONCLUSION

The main finding of the present study was that outcomes for patients who underwent revision ACL reconstruction with a second extensor mechanism autograft were comparable to those seen for patients who underwent revision ACL reconstruction with extensor mechanism autograft after primary ACL reconstruction with hamstring autograft. By better understanding the consequences of harvesting a second graft from the extensor mechanism, surgeons can better decide what graft to use in revision ACL reconstruction.

LEVEL OF EVIDENCE

Level III.

Semitendinosus muscle morphology in relation to surface electrode placement in anterior cruciate ligament reconstructed and contralateral legs

The semitendinosus tendon is commonly harvested as graft tissue for anterior cruciate ligament reconstruction (ACLR). Although the semitendinosus tendon can regenerate following harvesting, ACLR results in substantial reductions in semitendinosus muscle size and length, potentially complicating electrode placement for electromyography. The purpose of this study was to assess whether the most commonly used electrode placement [recommended by the "Surface Electromyography for Non-Invasive Assessment of Muscles" (SENIAM) project] is appropriate for measuring semitendinosus electromyograms after ACLR. In nine participants (unilateral ACLR with a semitendinosus graft), B-mode ultrasonography was used to bilaterally determine (i) the semitendinosus muscle-tendon junction position and the state of tendon regeneration (latter for the ACLR leg only) and (ii) the anatomical cross-sectional area (ACSA) of the semitendinosus muscle at the SENIAM-recommended electrode placement site at rest and during isometric maximal voluntary contraction (MVC) at two knee joint angles. Depending on the contraction state and joint angle, the semitendinosus muscle had retracted past the recommended placement site in 33-78% of ACLR legs, but not in any contralateral legs. The ACSA of semitendinosus was smaller both at rest and MVC in the ACLR compared to contralateral leg. The ACSA for both legs decreased at MVC compared to rest and at deep compared to shallow knee flexion angles, likely due to sliding of the muscle under the skin. These results suggest SENIAM guidelines are likely unsuitable for recording surface electromyograms from the semitendinosus muscle after tendon harvesting for ACLR as the muscle of interest may not be within the electrode detection volume.