Contralateral limb deficit seven months after ACL-reconstruction: an analysis of single-leg hop tests

Impaired Symmetry in Single-Leg Vertical Jump and Drop Jump Performance 7 Months After ACL Reconstruction

Background

Anterior cruciate ligament reconstruction (ACLR) continues to be associated with a variable rate of return to sports and a concerning rate of further anterior cruciate ligament injury. Persistent functional deficits may explain these results and support the need to keep exploring lower limb functional indexes, especially during vertical jumping. This would help improve rehabilitation through the return-to-sports continuum and improve postoperative outcomes.

Hypothesis

Vertical jumping performance indexes are impaired among patients 7 months after ACLR.

Study Design

Cross-sectional study; Level of evidence, 3.

Methods

A total of 202 patients who underwent ACLR and 50 healthy participants performed single-leg vertical jump (SLVJ) and single-leg drop jump (SLDJ) testing. Jump height (H) as well as reactive strength index (RSI) were assessed and the limb symmetry index (LSI) of each parameter was compared between both groups. Vertical jumping indexes were also compared between healthy participants and the injured and contralateral legs of ACLR patients. Frequency analysis (chi-square test) of participants exhibiting an LSI >90% for each parameter was calculated in both groups. The level of association between SLVJ-H, SLDJ-H, and SLDJ-RSI was evaluated using the Pearson coefficient (r).

Results

At 6.6 ± 0.7 months (mean ± SD) postoperatively, participants after ACLR exhibited poorer LSI than the control group for all parameters (79.1 ± 14.8 vs 93.9 ± 4.5, 77.3 ± 14.6 vs 93.4 ± 5.2, and 71.9 ± 17.4 vs 93.4 ± 3.8; all P < .001; for the SLVJ-H, SLDJ-H, and SLDJ-RSI, respectively). Vertical jumping performance was lower on both injured and contralateral legs compared with healthy participants (all P < .001). Only 27%, 25%, and 16% of the ACLR patients exhibited an LSI >90% for the SLVJ-H, SLDJ-H, and SLDJ-RSI, respectively, in comparison with 80%, 72%, and 86% in the control group. Moderate correlations were observed between SLDJ-H and SLVJ-H (r = 0.494; P < .001) as well as between SLDJ-RSI and SLVJ-H (r = 0.488; P < .001) in the ACLR group.

Conclusion

Vertical jumping indexes (both symmetry and absolute values) were highly impaired 7 months after ACLR. Deficits were more marked for reactive strength ability. Clinicians should focus on restoring vertical jumping abilities to improve functional performance after ACLR.

The effect of anterior cruciate ligament reconstruction and RAMP lesion repair on psychological status

BACKGROUND

There are few studies examining anterior cruciate ligament reconstruction (ACLR) and RAMP lesion repair. However, no studies have investigated the level of functional performance and psychological state after ACLR and all-inside RAMP lesion repair.

HYPOTHESIS/PURPOSE

The aim of this study is to determine the effect of ACLR and RAMP lesion repair on psychological status. ACLR and meniscal RAMP lesion repair were hypothesized to be associated with better psychological outcomes.

STUDY DESIGN

This is a cohort study.

METHODS

Patients who underwent ACLR with semitendinosus and gracilis autografts by a single surgeon were determined retrospectively. Fifteen patients who underwent ACLR and all-inside meniscus RAMP lesion repair (ACLR-RR) and 15 patients who underwent isolated ACLR were compared. Patients were evaluated by a physiotherapist at least 9 months after surgery. The primary outcome measure was anterior cruciate ligament-return to sports after injury (ACL-RSI), and the psychological status of the patients was examined. Secondary outcomes were visual analog scale (VAS), Tegner activity score, Lysholm knee score, single hop tests, and limb symmetry index (LSI). While pain intensity at rest and during movement was evaluated with VAS, functional performance level was evaluated with the Tegner activity score, the Lysholm knee score, single hop tests, and limb symmetry index (LSI).

RESULTS

A significant difference was found in the ACL-RSI values in the ACLR-RR group compared to the isolated ACLR group (p = 0.02). The results of the groups in VAS scores at rest and during movement, Tegner activity levels, and Lysholm knee scores, in the intact and operated leg single hop tests (single leg hop, cross hop, triple hop, and six-meter hop test), and the LSI values in the single leg hop tests showed no significant difference.

CONCLUSIONS

This study revealed different psychological outcomes and similar functional levels for ACLR and all-inside meniscus RAMP repair compared with isolated ACLR. It was observed that the psychological status of patients with RAMP lesions should also be evaluated.

Injury Pathology in Young Gymnasts: A Retrospective Analysis

Gymnastics has a history of high injury incidence rates. However, little is known about the injury pathology in young gymnasts. The purpose of this study was to fill gaps in the literature by providing insight into the injury pathology in gymnasts aged 6 to 17 years. This study was retrospective in design, where injury data were collected using a Qualtrics questionnaire and distributed via social media. The findings revealed that the most common injury site was the lower limb (60.5%), in particular, the ankle/foot (49%) and knee (27%). Overuse injuries and sprains were most prevalent among the lower limb (25% and 18.4%, respectively), and gymnasts seemed to have a tendency to train through injury with modifications to training. In conclusion, lower limb joint sprain and overuse injuries accounted for the majority of injuries in youth gymnasts. These injuries were more frequently reported in girls in the years associated with peak height velocity and beyond.

Push-Off Dynamics Reveal Task-Independent Alterations in Athletes Returning to Sport after ACL Reconstruction

PURPOSE

Athletes with an anterior cruciate ligament (ACL) reconstruction (ACLR) show persisting biomechanical and neuromuscular landing alterations. So far, most research focused on the landing phase of dynamic tasks where most ACL injuries occur. This study will assess whether these landing alterations are also present in the propulsion phase, in an attempt to identify generalized movement alterations.

METHODS

Twenty-one athletes with ACLR (cleared by their surgeon and/or physiotherapist for return-to-sport) and twenty-one controls performed five single-leg hop tasks. Propulsion kinematics, kinetics, and muscle activations were compared between legs and between groups.

RESULTS

Increased hamstrings activation was found during propulsion when comparing the ACLR limb with both the uninjured limb and the controls. In addition, decreased internal knee extension moments were found in the ACLR limb compared with the uninjured limb.

CONCLUSIONS

Athletes with ACLR show task-independent alterations that unload the knee during the propulsion phase of single-leg hopping tasks. If longitudinal data deem these alterations to be maladaptive, more emphasis must be placed on their normalization during the propulsion phase, assuming beneficial carryover effects into the landing phase. Normalizing these patterns during rehabilitation may potentially reduce the risk of long-term complications such as reinjuries and posttraumatic osteoarthritis.

Dorsiflexion and Hop Biomechanics Associate with Greater Talar Cartilage Deformation in Those with Chronic Ankle Instability

PURPOSE

This study aimed to identify associations between dorsiflexion range of motion (DFROM), functional hop test performance, and hopping biomechanics with the magnitude of talar cartilage deformation after a standardized hopping protocol in individuals with and without chronic ankle instability (CAI).

METHODS

Thirty CAI and 30 healthy individuals participated. Ankle DFROM was assessed using the weight-bearing lunge test. Four different functional hop tests were assessed. Three-dimensional kinematics and kinetics were sampled during a 60-cm single-leg hop. We calculated cartilage deformation after a dynamic loading protocol consisting of sixty 60-cm single-leg forward hops by assessing the change in average thickness for the overall, medial, and lateral talar cartilage. Linear regressions examined the associations between cartilage deformation magnitude and DFROM, functional hop tests, and hop biomechanical variables after accounting for body weight and time since the initial ankle sprain.

RESULTS

In CAI group, lesser static DFROM (ΔR2 = 0.22) and smaller peak ankle dorsiflexion angle (ΔR2 = 0.17) was associated with greater medial deformation. Greater peak vertical ground reaction force (vGRF) (ΔR2 = 0.26-0.28) was associated with greater medial and overall deformation. Greater vGRF loading rate (ΔR2 = 0.23-0.35) was associated with greater lateral and overall deformation. Greater side hop test times (ΔR2 = 0.31-0.36) and ankle plantarflexion at initial contact (ΔR2 = 0.23-0.38) were associated with greater medial, lateral, and overall deformation. In the control group, lesser side hop test times (ΔR2 = 0.14), greater crossover hop distances (ΔR2 = 0.14), and greater single-hop distances (ΔR2 = 0.21) were associated with greater overall deformation.

CONCLUSIONS

Our results indicate that lesser static DFROM, poorer functional hop test performance, and hop biomechanics associate with greater talar cartilage deformation after a dynamic loading protocol in those with CAI. These factors may represent targets for therapeutic interventions within this population to slow ankle posttraumatic osteoarthritis progression.

Symmetry in Triple Hop Distance Hides Asymmetries in Knee Function After ACL Reconstruction in Athletes at Return to Sports

BACKGROUND

After anterior cruciate ligament reconstruction (ACLR), a battery of strength and hop tests is frequently used to determine the readiness of an athlete to successfully return to sports. However, the anterior cruciate ligament reinjury rate remains alarmingly high.

PURPOSE

To evaluate the lower limb function of athletes after ACLR at the time when they had been cleared to return to sports (RTS). We aimed to evaluate if passing discharge criteria ensures restoration of normal lower limb biomechanics in terms of kinematics, kinetics, work, and percentage work contribution during a triple hop for distance.

STUDY DESIGN

Controlled laboratory study.

METHODS

Integrated 3-dimensional motion analysis was performed in 24 male athletes after ACLR when cleared to RTS and 23 healthy male controls during the triple-hop test. The criteria for RTS were (1) clearance by the surgeon and the physical therapist, (2) completion of a sports-specific on-field rehabilitation program, and (3) limb symmetry index >90% after quadriceps strength and hop battery tests. Lower limb and trunk kinematics, as well as knee joint moments and work, were calculated. Between-limb differences (within athletes after ACLR) and between-group differences (between ACLR and control groups) were evaluated using mixed linear models.

RESULTS

Although achieving 97% limb symmetry in distance hopped and displaying almost 80% symmetry for knee work absorption in the second rebound and third landing, the ACLR cohorts demonstrated only 51% and 66% limb symmetry for knee work generation in the first and second rebound phases, respectively. During both work generation phases of the triple hop, the relative contribution of the involved knee was significantly smaller, with a prominent compensation from the hip joint (P < .001, for all phases) as compared with the uninvolved limb and the controls. In addition, patients deployed a whole body compensatory strategy to account for the between-limb differences in knee function, mainly at the hip, pelvis, and trunk.

CONCLUSION

Symmetry in the triple hop for distance masked important deficits in the knee joint work. These differences were more prominent during work generation (concentric-propulsive) than work absorption (eccentric-landing).

CLINICAL RELEVANCE

Symmetry in hop distance during the triple hop test masked significant asymmetries in knee function after ACLR and might not be the appropriate outcome to use as a discharge criterion. Differences between limbs in athletes after ACLR were more prominent during the power generation than the absorption phase.

The Non-injured Leg Can Be Used as a Reference for the Injured Leg in Single-legged Hop Tests

BACKGROUND

Single-legged hop tests are frequently used in substantiating return to sport decisions following lower extremity injury. Evidence for using the non-injured leg as a reference for the injured leg in the return to sport decision-making at the criterion-based point of return to sport following lower extremity injury is lacking.

PURPOSE

To compare absolute values in single-legged hop tests between the non-injured leg of athletes returning to high-impact sports after lower extremity injury and the matched leg of healthy athletes.

STUDY DESIGN

Cross-sectional study.

METHODS

One hundred and sixty-nine athletes returning to high-impact sports after lower extremity injury and 169 matched healthy athletes executed five single-legged hop tests. Differences between athletes returning to high-impact sports after lower extremity injury and matched healthy athletes on five single-legged hop tests were analyzed using paired t-tests.

RESULTS

There were no statistically significant differences between the non-injured leg of athletes returning to sport and the matched leg of healthy athletes. Effect sizes ranged from 0.05 to 0.14 indicating negligible effects.

CONCLUSION

Clinicians can use the non-injured leg as a reference for the injured leg in single-legged hop tests for deciding on return to high-impact sports after lower extremity injuries.

LEVEL OF EVIDENCE

3b.

Female Adolescent Soccer Players Utilize Different Neuromuscular Strategies Between Limbs During the Propulsion Phase of a Lateral Vertical Jump

BACKGROUND

Multiplanar dynamic stability is an important unilateral function in soccer performance but has been scarcely examined in female soccer players. The lateral vertical jump task assesses unilateral functional performance, and energy generation contribution examines how each joint (hip, knee, ankle) contributes to the vertical component of the vertical jump phase to measure inter- and intra-limb differences.

PURPOSE

To examine dominant versus non-dominant limb performance using energy generation contribution of the hip, knee, and ankle during the vertical jump component of the lateral vertical jump.

STUDY DESIGN

Cross-sectional observational study.

METHODS

Seventeen healthy, adolescent female soccer players (age 13.4±1.7 years; height 160.6±6.0 cm; mass 53.1±8.2 kg) participated. Quadriceps strength was measured via isokinetic dynamometry. Energy generation contribution (measured from maximal knee flexion to toe off) and vertical jump height were measured during the vertical component of the lateral vertical jump.

RESULTS

There was no significant difference between limbs for quadriceps strength (p=0.64), jump height (p=0.59), or ankle energy generation contribution (p=0.38). Energy generation contribution was significantly greater in the dominant hip (dominant 29.7±8.6%, non-dominant 18.4±6.3%, p<0.001) and non-dominant knee (dominant 22.8±6.8%, non-dominant 36.2±8.5%, p<0.001).

CONCLUSION

High demand on coordination and motor control during the lateral vertical jump and inherent limb dominance may explain different intra-limb strategies for task performance despite jump height symmetry. Non-dominant affinity for stability and dominant compensatory performance may neutralize potential asymmetries. Implications for symmetry in observable outcomes such as jump height must consider underlying internal asymmetries.

LEVELS OF EVIDENCE

3B.

CLINICAL RELEVANCE

Symmetrical findings on functional tasks have underlying internal asymmetries observed here in female adolescent soccer players. The lateral vertical jump may highlight these internal asymmetries (hip- versus knee-dominant movement strategies) due to the high coordinative demand to perform the task. Clinicians should be cognizant of underlying, potentially inherent, asymmetries even when observing functional symmetry in a task.

WHAT IS KNOWN ABOUT THE SUBJECT

Female adolescent soccer players are a high-risk cohort for sustaining anterior cruciate ligament injuries. Limb dominance may play a role in the performance of functional tasks, and limb dominance in soccer players is quite specialized: the dominant limb is the preferred kicking limb, while the non-dominant limb is the preferred stabilizing limb (plant leg). Functional performance in female soccer players has been studied in kicking, dribbling, sprinting, change of direction, and jumping - however, these tasks were measured independent of limb dominance. It remains to be seen how unilateral functional tasks may be affected by limb dominance in female adolescent soccer players.

WHAT THIS STUDY ADDS TO EXISTING KNOWLEDGE

This study provides data on functional performance relative to limb dominance in female adolescent soccer players, and captures the lateral vertical jump task in both inter- and intra-limb measures. This highlights that intra-limb strategies to perform a coordinated motor task may be different between limbs, herein attributed to limb dominance. Even if gross motor outputs between limbs are symmetrical (i.e. jump height), the underlying movement strategies to achieve that output may be different (hip- versus knee-dominant movement strategies). These findings are important to research on functional performance measures related to attaining between-limb symmetry, as measures of energy generation contribution open the door for a more thorough understanding of joint-by-joint intra-limb contributions during a functional task.

Joint movement variability during landing in patients with anterior cruciate ligament reconstruction

BACKGROUND

Rapid knee valgus and knee internal rotation motions in the initial phase of landing are the known mechanisms for anterior cruciate ligament injury, and many studies have been investigated on knee joint peak angle during landing. However, the variability in joint movement during landing has not been fully investigated. This study aimed to compare the coefficient of variation of lower extremity range of motion in patients with anterior cruciate ligament reconstruction and healthy subjects during landing.

METHODS

In this cross-sectional study, 54 patients with anterior cruciate ligament reconstruction and 44 healthy subjects were enrolled. All participants underwent six trials of single-leg hop landing for maximum safe horizontal distance. The kinematic variables were the coefficient of variation during two discrete (0.05 after initial contact and maximum knee flexion) time points for selected three-dimensional hip and knee joint range of motion. Comparisons were performed between the two groups.

RESULTS

Compared with healthy subjects, patients with anterior cruciate ligament reconstruction had greater the coefficient of variation in hip internal/external rotation range of motion (patients with anterior cruciate ligament reconstruction had 41.9%, healthy subjects had 25.5%; P=0.0018; effect size: 0.32) and knee internal/external rotation range of motion (patients with anterior cruciate ligament reconstruction had 68.4%; healthy subjects had 48.1%; P=0.0014; effect size: 0.32) for periods that spanned 0.05 s from the initial contact.

CONCLUSIONS

Patients with anterior cruciate ligament reconstruction could be disadvantageous in ability to control and adapt hip and knee joint rotations when controlling landings.

Hop Performance After Return to Sport in Anterior Cruciate Ligament-Reconstructed Gaelic Football and Hurling Athletes

PURPOSE

Anterior cruciate ligament (ACL) injuries are among the most severe injuries in the Gaelic Athletic Association. Hop tests measure functional performance after ACL reconstruction as they replicate the key requirements for a match situation. However, research examining functional recovery of ACL-reconstructed Gaelic athletes is lacking. The objective of this study is to determine if athletes restore normal hop symmetry after ACL reconstruction and to examine if bilateral deficiencies persist in hop performance following return to sport.

METHODS

A cross-sectional design was used to evaluate hop performance of 30 ACL-reconstructed Gaelic athletes who had returned to competition and 30 uninjured controls in a battery of hop tests including a single, 6-m, triple, and triple-crossover hop test.

RESULTS

In each test, the mean symmetry score of the ACL reconstruction group was above the cutoff for normal performance of 90% adopted by this study (98%, 99%, 97%, and 99% for the single, 6-m, triple, and triple-crossover hop, respectively). No significant differences in absolute hop scores emerged between involved and control limbs, with the exception of the single-hop test where healthy dominant limbs hopped significantly further than ACL-reconstructed dominant limbs (P = .02). No significant deficits were identified on the noninvolved side.

CONCLUSIONS

The majority of ACL-reconstructed Gaelic athletes demonstrate normal levels of hop symmetry after returning to competition. Suboptimal hop performance can persist on the involved side compared with control limbs. Targeted rehabilitation may be warranted after returning to competition to restore performance to levels of healthy uninjured athletes.

The single-leg vertical hop provides unique asymmetry information in individuals after anterior cruciate ligament reconstruction

BACKGROUND

Traditional testing to identify asymmetries after anterior cruciate ligament reconstruction include four similar horizontal hopping tests. The purpose of this study was to determine whether a single-leg vertical hopping test can identify performance and biomechanical asymmetries, and whether performance asymmetries provide unique information compared to traditional tests.

METHODS

Twelve women with history of anterior cruciate ligament reconstruction [age: 21.1 years (SD 3.2), height: 165.8 cm (SD 6.0), mass: 68.3 kg (SD 8.8)] completed traditional horizontal hop testing. Participants also performed a single-leg vertical hop for maximal height while instrumented for three-dimensional motion analysis. Paired t-tests were performed to identify side-to-side differences in performance variables and Spearman's rank correlations were performed of limb symmetry indices to identify whether the single-leg vertical hop test provides unique information. Repeated measures MANOVAs were performed to identify single-leg vertical hop biomechanical asymmetries.

FINDINGS

Participants exhibited significant side-to-side performance differences during the single-leg vertical hop [mean difference = 0.02 m (SD 0.03), P = .04]. Only weak to moderate relationships were identified between limb symmetry indices of the single-leg vertical hop and other horizontal hopping tests. The vertical hop elicited significant asymmetries of joint kinematics (P = .04) and angular impulse (P = .04). Specifically, the involved limb showed lower peak ankle dorsiflexion (P = .004) and knee abduction (P = .02) angles, lower sagittal plane impulse at the knee (P = .02) and greater sagittal plane impulse at the hip (P = .03).

INTERPRETATION

The single-leg vertical hop can identify performance and biomechanical asymmetries in individuals after anterior cruciate ligament reconstruction, potentially providing complementary information to standard horizontal hopping tests.

Individual hop analysis and reactive strength ratios provide better discrimination of ACL reconstructed limb deficits than triple hop for distance scores in athletes returning to sport

BACKGROUND

The triple hop for distance test commonly uses a limb symmetry index (LSI) 'pass' threshold of >90% for total hop distance following anterior cruciate ligament reconstruction (ACLR). However, understanding the manner in which athletes generate and dissipate forces during consecutive hops within the test may provide greater insight into residual limb deficits. The aim of the study was to examine reactive strength ratios (RSR) of individual hops during a triple hop test in a cohort of ACLR patients at discharge prior to return-to-sport.

METHODS

Twenty male athletes (24.6 ± 4.2 years; height 175.3 ± 10.2 cm; mass 73.6 ± 14.5 kg) completed the test on both non-operated and operated limbs. Total distance hopped, contact times, flight times and RSR were collected for each hop using a floor-level optical measurement system.

RESULTS

Significant, small to moderate between-limb differences (p < 0.05; d = 0.45-0.72) were shown for triple hop distance, flight time and RSR for each hop, with lower performance consistently displayed in the operated limb. Large, significant differences in RSR were evident between hops one and two on the operated limb (p < 0.05; d = 0.97). Despite 80% of participants achieving >90% LSI for total hop distance, less than 50% of participants reached the >90% LSI threshold for RSR.

CONCLUSIONS

Standardised LSI 'pass' thresholds (>90% LSI) for triple hop distance may mask residual deficits in reactive strength performance of operated limbs; therefore, more detailed analyses of individual hop performance may be warranted to enhance return to sport criteria following ACLR.

No Difference in Functional Outcomes When Lateral Extra-Articular Tenodesis Is Added to Anterior Cruciate Ligament Reconstruction in Young Active Patients: The Stability Study

PURPOSE

To assess the functional outcomes of patients included in the Stability Study randomized controlled trial comparing anterior cruciate ligament reconstruction (ACLR) alone with ACLR with lateral extra-articular tenodesis (LET) at 6, 12, and 24 months postoperatively.

METHODS

Six hundred eighteen patients undergoing ACLR, all under the age of 25 years either returning to contact pivoting sport or displaying signs of high-grade rotatory laxity or generalized ligamentous laxity, were randomly assigned to receive ACLR alone or ACLR plus LET. A total of 356 of these patients were randomized at centers participating in the functional assessments. Our primary outcome was Limb Symmetry Index, calculated using a series of 4-hop tests at 6, 12, and 24 months postoperatively. Secondary outcome measures included pain, patient-reported function, and isokinetic strength testing.

RESULTS

We found no statistically significant difference in the proportion of patients either unwilling or unfit to complete the hop testing in the ACLR alone or ACLR with LET group at 6 months (40 vs 40 respectively; P = 1.00), 12 months (25 vs 27; P = .76), and 24 months (21 vs 23; P = .87). Of those who completed hop testing, there were no statistically significant differences between groups in Limb Symmetry Index at 6, 12, or 24 months. Self-reported function (Lower Extremity Functional Score) significantly favored the ACLR alone group at 3 (P = .01) and 6 months (P = .02) postoperative but was similar by 12 months postoperative. Pain scores (P4) also showed a statistically significant difference in favor of the ACL alone group, but this also resolved by 6 months. Quadriceps peak torque (P = .03) and average power (P = .01) were also significantly different in favor of the ACLR alone group at 6 months postoperative; however, these were similar between groups by 12 months postoperative (P = .11 and P = .32, respectively).

CONCLUSIONS

The addition of a LET to ACLR results in slightly increased pain, a mild reduction in quadriceps strength, and reduced subjective functional recovery up to 6 months postoperatively. However, these differences do not have any impact on objective function as measured by hop test limb symmetry index.

LEVEL OF EVIDENCE

I, Randomized Controlled Trial.

Quadriceps and Hamstring Strength Symmetry After Anterior Cruciate Ligament Reconstruction: A Prospective Study

OBJECTIVES

To evaluate change in involved and uninvolved quadriceps and hamstring strength and limb symmetry indices (LSI) in regular intervals over the first 6 months following anterior cruciate ligament reconstruction (ACLR).

DESIGN

Prospective cohort study.

PARTICIPANTS

Thirty-eight male participants (mean age: 24.2 [6.4] y, mean body mass index: 23.6 [4.2] kg/m2), who underwent ACLR were included.

MAIN OUTCOME MEASURES

Isometric strength testing of the quadriceps and hamstring muscles was performed at 1, 2, 3, and 6 months after ACLR. Quadriceps and hamstring peak torques for each limb and LSI were calculated. Repeated-measures analysis of covariance and paired t tests were used to evaluate changes in strength over time and between limbs, respectively.

RESULTS

Quadriceps and hamstring peak torques of the involved limb consistently increased between each time point from 1 to 6 months (P < .001 and P = .01, respectively), whereas the uninvolved limb values did not change after ACLR (P > .05). In addition, uninvolved limb peak torque values were higher than involved limb values at each time point after ACLR for both the quadriceps and hamstrings (all P < .01). At 6 months after ACLR, 28.9% of participants demonstrated LSI greater than 90% for quadriceps strength, 36.8% demonstrated LSI greater than 90% for hamstring strength, and 15.8% of participants demonstrated greater than 90% LSI for both quadriceps and hamstring strength.

CONCLUSIONS

Participants demonstrated a consistent increase in quadriceps and hamstring strength of the involved limb, with no notable change in uninvolved limb strength over the 6 months after ACLR. However, at 6 months after ACLR, only approximately 16% of participants demonstrated both quadriceps and hamstring strength LSI greater than 90%, the typically recommended cutoff value for return to sport.

The Efficacy of Lower-Limb Screening Tests in Predicting PlayerLoad Within a Professional Soccer Academy

CONTEXT

Training exposure has been associated with injury epidemiology in elite youth soccer, where lower-limb musculoskeletal screening is commonly used to highlight injury risk. However, there has been little consideration of the relationship between lower-limb screening and the loading response to soccer activities.

OBJECTIVE

To quantify the efficacy of using screening tests to predict the loading elicited in soccer-specific activities and to develop a hierarchical ordering of musculoskeletal screening tests to identify test redundancy and inform practice.

DESIGN

Correlational.

SETTING

Professional soccer club academy.

PARTICIPANTS

A total of 21 elite male soccer players aged 15.7 (0.9) years.

INTERVENTION

Players completed a battery of 5 screening tests (knee to wall, hip internal rotation, adductor squeeze, single-leg hop, and anterior reach) and a 25-minute standardized soccer session with a Global Positioning System unit placed at C7 to collect multiplanar PlayerLoad data.

MAIN OUTCOME MEASURES

Baseline data on each screening test, along with uniaxial PlayerLoad in the mediolateral, anteroposterior, and vertical planes.

RESULTS

Stepwise hierarchical modeling of the screening tests revealed that dominant leg knee-to-wall distance was the most prevalent and powerful predictor of multiplanar PlayerLoad, accounting for up to 42% of variation in uniaxial loading. The adductor squeeze test was the least powerful predictor of PlayerLoad. Of note, one player who incurred a knee injury within 3 weeks of testing had shown a 20% reduction in knee-to-wall distance compared with peers, and elicited 23% greater PlayerLoad, supporting the hierarchical model.

CONCLUSIONS

There was some evidence of redundancy in the screening battery, with implications for clinical choice. Hierarchical ordering and a concurrent case study highlight dominant leg knee-to-wall distance as the primary predictor of multiaxial loading in soccer. This has implications for the design and interpretation of screening data in elite youth soccer.

Countermovement Jump and Isokinetic Dynamometry as Measures of Rehabilitation Status After Anterior Cruciate Ligament Reconstruction

CONTEXT

  Despite an increase in the literature, few definitive guidelines are available to determine when an athlete has been fully rehabilitated after anterior cruciate ligament reconstruction (ACLR).

OBJECTIVE

  To examine countermovement jump and isokinetic dynamometry measures to (1) identify which measures can best distinguish between ACLR and control participants and (2) provide normative values for identified measures in young adult male multidirectional field-sport athletes.

DESIGN

  Cross-sectional study.

SETTING

  Orthopaedic hospital.

PATIENTS OR OTHER PARTICIPANTS

  Young adult male multidirectional field-sport athletes (n = 118) who had undergone unilateral patellar-tendon graft ACLR at least 6 months earlier and healthy male participants (n = 44) with no previous knee injury.

INTERVENTION(S)

  Single-legged countermovement jump (SL CMJ).

MAIN OUTCOME MEASURE(S)

  Three-dimensional biomechanical analysis of the SL CMJ and mean peak concentric knee-extension and -flexion torque using isokinetic dynamometry (ISO) were compared in the 2 groups. A stepwise logistic regression was carried out to identify the best predictors of ACLR- or control-group membership (SL CMJ height, limb symmetry index, peak power, joint power contribution, ISO peak torque, limb symmetry index variables).

RESULTS

  The control group differed strongly from the ACLR group in isokinetic knee-extension peak torque (d = -1.33), SL CMJ performance (d > 0.4), and limb symmetry measures in both ISO and jump outcomes (d > 1.1). The combination of measures from both ISO and SL CMJ identified group membership with an accuracy of 89%.

CONCLUSIONS

  Rehabilitation of ACLR patients may be complete when they achieve isokinetic knee-extension peak torque of 260% (±40%) body mass, SL CMJ performance of >17 cm (±4 cm), and reach-limb symmetry measures of >90% in both strength and jump outcomes. The outcomes in the control group can inform return-to-play criteria for young adult male multidirectional field-sport athletes after ACLR.

Hip external rotation strength predicts hop performance after anterior cruciate ligament reconstruction

PURPOSE

Quadriceps strength and single-leg hop performance are commonly evaluated prior to return to sport after anterior cruciate ligament reconstruction (ACLR). However, few studies have documented potential hip strength deficits after ACLR, or ascertained the relative contribution of quadriceps and hip strength to hop performance.

METHODS

Patients cleared for return to sports drills after ACLR were compared to a control group. Participants' peak isometric knee extension, hip abduction, hip extension, and hip external rotation (HER) strength were measured. Participants also performed single-leg hops, timed hops, triple hops, and crossover hops. Between-limb comparisons for the ACLR to control limb and the non-operative limb were made using independent two-sample and paired sample t tests. Pearson's correlations and stepwise multiple linear regression were used to determine the relationships and predictive ability of limb strength, graft type, sex, and limb dominance to hop performance.

RESULTS

Sixty-five subjects, 20 ACLR [11F, age 22.8 (15-45) years, 8.3 ± 2 months post-op, mass 70.47 ± 12.95 kg, height 1.71 ± 0.08 m, Tegner 5.5 (3-9)] and 45 controls [22F, age 25.8 (15-45) years, mass 74.0 ± 15.2 kg, height 1.74 ± 0.1 m, Tegner 6 (3-7)], were tested. Knee extension (4.4 ± 1.5 vs 5.4 ± 1.8 N/kg, p = 0.02), HER (1.4 ± 0.4 vs 1.7 ± 0.5 N/kg, p = 0.04), single-leg hop (146 ± 37 vs 182 ± 38% limb length, p < 0.01), triple hop (417 ± 106 vs 519 ± 102% limb length, p < 0.01), timed hop (3.3 ± 2.0 vs 2.3 ± 0.6 s, p < 0.01), and crossover hop (364 ± 107 vs 446 ± 123% limb length, p = 0.01) were significantly impaired in the operative versus control subject limbs. Similar deficits existed between the operative and non-operative limbs. Knee extension and HER strength were significantly correlated with each of the hop tests, but only HER significantly predicted hop performance.

CONCLUSIONS

After ACLR, patients have persistent HER strength, knee extension strength, and hop test deficits in the operative limb compared to the control and non-operative limbs, even after starting sport-specific drills. Importantly, HER strength independently predicted hop performance. Based on these findings, to resolve between-limb deficits in strength and hop performance clinicians should include HER strengthening exercises in post-operative rehabilitation.

LEVEL OF EVIDENCE

Prognostic Study, Level II.

Altered lower extremity joint mechanics occur during the star excursion balance test and single leg hop after ACL-reconstruction in a collegiate athlete

The effects of ACL-reconstruction on lower extremity joint mechanics during performance of the Star Excursion Balance Test (SEBT) and Single Leg Hop (SLH) are limited. The purpose of this study was to determine if altered lower extremity mechanics occur during the SEBT and SLH after ACL-reconstruction. One female Division I collegiate athlete performed the SEBT and SLH tasks, bilaterally, both before ACL injury and 27 months after ACL-reconstruction. Maximal reach, hop distances, lower extremity joint kinematics and moments were compared between both time points. Musculoskeletal simulations were used to assess muscle force production during the SEBT and SLH at both time points. Compared to the pre-injury time point, SEBT reach distances were similar in both limbs after ACL-reconstruction except for the max anterior reach distance in the ipsilateral limb. The athlete demonstrated similar hop distances, bilaterally, after ACL-reconstruction compared to the pre-injury time point. Despite normal functional performance during the SEBT and SLH, the athlete exhibited altered lower extremity joint mechanics during both of these tasks. These results suggest that measuring the maximal reach and hop distances for these tasks, in combination with an analysis of the lower extremity joint mechanics that occur after ACL-reconstruction, may help clinicians and researchers to better understand the effects of ACL-reconstruction on the neuromuscular system during the SEBT and SLH.

Explosive movement in the older men: analysis and comparative study of vertical jump

BACKGROUND

Loss of power has been demonstrated to have severe functional consequences to perform physical daily living tasks in old age.

PURPOSE

This study aimed to assess how moment and velocity were affected for each joint of the lower limbs during squat jumping for older men in comparison with young adults.

METHODS

Twenty-one healthy older men (74.5 ± 4.6 years) and 22 young men (21.8 ± 2.8 years) performed maximal squat jumps. Inverse dynamics procedure was used to compute the net joint power, moment and velocity produced at the hip, knee and ankle joints.

RESULTS AND DISCUSSION

Vertical jump height of the elderly was 64 % lower than the young adults. The maximal power of the body mass center (P _max^bmc ) was 57 % lower in the older population. For the instant at P _max^bmc , the vertical ground reaction force and the vertical velocity of the body mass center were 26 % and 35 % less in the older adults than in the young adults, respectively (p < 0.05; ES = -1.64 for vertical ground reaction force; p < 0.05; ES = -1.10). A lower value of the hip (-60 %), knee (-72 %) and ankle (-68 %) joint powers was observed in older adults. This was explained by both lower values of joint moments (-64, -57 and -61 % for the hip, knee and ankle, respectively) and angular velocities (-59, -49 and -52 % for the hip, knee and ankle, respectively).

CONCLUSION

This study showed a lower joint power when performing vertical jump. This smaller power resulted from both a lower moment and angular velocity produced at each joint.

A critical analysis of limb symmetry indices of hop tests in athletes after anterior cruciate ligament reconstruction: A case control study

BACKGROUND

Hop tests are frequently used to determine return to sports (RTS) after anterior cruciate ligament reconstruction (ACLR). Given that bilateral deficits are present after ACLR, this may result in a falsely high limb symmetry index (LSI), since LSI is calculated as a ratio between the values of the limbs.

HYPOTHESIS

Athletes after ACLR would achieve LSI>90% for the hop test. Secondly, athletes after ACLR demonstrate decreased jump distance on the single hop for distance (SLH) and triple leg hop for distance (TLH) and decreased number of hops for the side hop (SH) for both involved and uninvolved limbs compared to normative data of sex, age and type of sports matched healthy athletes.

MATERIALS AND METHODS

Fifty-two patients (38 males mean age 23.9±3.5years; 14 females mean age 21.7±3.5 years) who had undergone an ACLR participated in this study. Patients performed the 3 hop tests at a mean time of 7 months after ACLR. Hop distance, number of side hops and LSI were compared with normative data of 188 healthy athletes.

RESULTS

The differences between the involved limb and the uninvolved limb were significant in all hop tests (SLH P=0.003, TLH P=0.003, SH P=0.018). For females, only significant between limb differences were found in the SLH (P=0.049). For both the SLH and the TLH, significant differences were found between the involved limb and the normative data (males; SLH P<0.001, TLH P<0.001; females; SLH P<0.001, TLH P=0.006) and between the uninvolved limb and the normative data for both males and females (males; SLH P<0.001, TLH P<0.001; females; SLH P=0.003, TLH P=0.038). For the SH, only significant differences were found between the involved limb and the normative values in males (P=0.033).

CONCLUSION

Athletes who have undergone an ACLR demonstrate bilateral deficits on hop tests in comparison to age and sex matched normative data of healthy controls. Using the LSI may underestimate performance deficits and should therefore be analyzed with caution when used as a criterion for RTS after ACLR.

LEVEL OF EVIDENCE

III, case control study.

Young Athletes After Anterior Cruciate Ligament Reconstruction With Single-Leg Landing Asymmetries at the Time of Return to Sport Demonstrate Decreased Knee Function 2 Years Later

BACKGROUND

Previous work shows that young athletes after anterior cruciate ligament reconstruction (ACLR) demonstrate single-leg (SL) landing movement asymmetries at the time of return to sport (RTS); however, the effect of movement asymmetries on longitudinal knee-related function after ACLR has not been examined. Hypothesis/Purpose: The purpose of this study was to examine the effect of SL drop-landing movement symmetry at the time of RTS on knee-related function 2 years later in young athletes after ACLR. The first hypothesis was that young athletes who demonstrated SL drop-landing asymmetries at RTS would demonstrate decreased knee function 2 years later compared with those who demonstrated symmetric SL drop-landing mechanics. The second hypothesis was that SL drop-landing movement symmetry at RTS would be associated with knee functional recovery 2 years later.

STUDY DESIGN

Cohort study; Level of evidence, 2.

METHODS

This study included 48 young athletes who had undergone ACLR and were assessed at the time of RTS (77% female; mean [±SD] age at RTS, 17.6 ± 2.6 years) and followed for 2 years after RTS. Three sagittal-plane landing variables of interest were calculated using 3-dimensional motion analysis during an SL drop-landing task at the time of RTS: knee flexion excursion, peak internal knee extension moment, and peak trunk flexion. The limb symmetry index (LSI) was calculated for each landing variable using the following: LSI = (involved/uninvolved) × 100%. The LSI was used to divide the cohort into symmetric (SYM) and asymmetric (ASYM) groups for each landing variable: knee flexion excursion (SYM: LSI ≥ 90% [n = 23]; ASYM: LSI < 85% [n = 18]), peak internal knee extension moment (SYM: LSI ≥ 90% [n = 19]; ASYM: LSI < 85% [n = 22]), and peak trunk flexion (SYM: LSI ≤ 105% [n = 25]; ASYM: LSI > 115% [n = 19]). At 2 years after RTS, knee-related function was evaluated using the Knee Injury and Osteoarthritis Outcome Score (KOOS), International Knee Documentation Committee (IKDC) subjective knee form, and performance on SL hop tests. Functional recovery was defined based on literature cutoffs for knee-related functional measures. Differences in 2-year function were compared between the symmetry groups using Mann-Whitney U tests because of nonnormality. Logistic regression was used to determine if landing symmetry at the time of RTS would be associated with 2-year knee functional recovery after RTS.

RESULTS

The ASYM knee flexion excursion group demonstrated decreased function at 2 years after RTS compared with the SYM group on the KOOS-Pain (ASYM: 93.0 ± 8.2; SYM: 98.4 ± 3.0; P = .008) and the KOOS-Quality of Life (ASYM: 81.6 ± 16.1; SYM: 94.1 ± 9.7; P = .008). Knee flexion excursion was associated with knee functional recovery on the KOOS-Pain and the KOOS-Quality of Life ( P = .033 and P = .012, respectively) at 2 years after RTS, after controlling for the quadriceps strength LSI and graft type.

CONCLUSION

Young athletes after ACLR with asymmetries in knee kinematics at the time of RTS reported decreased self-reported function 2 years later; however, the clinical importance of these differences needs to be further understood.

How does functionality proceed in ACL reconstructed subjects? Proceeding of functional performance from pre- to six months post-ACL reconstruction

This is the first study examining functionality of subjects with anterior cruciate ligament (ACL) tears and a subsequent reconstruction comprehensively by multiple test sessions from pre- to six months post-reconstruction. The purpose was to evaluate if a generally applied rehabilitation program restores functionality to levels of healthy controls. Subjects with unilateral tears of the ACL were compared to matched healthy controls throughout the rehabilitation. 20 recreational athletes were tested: T₁ (preoperative), 6 weeks after tear; T₂, 6 weeks, T₃, 3 months, T₄, 6 months post-reconstruction. At all test sessions, subjects self-evaluated their activity level with the Tegner activity score and their knee state with the Knee Injury and Osteoarthritis Outcome Score. Passive range of motion during knee flexion and extension and leg circumference were measured as functional clinical tests. Bilateral countermovement jumps, one-leg jumps for distance and isometric force tests in knee flexion and extension with 90° and 110° knee angle were conducted as functional performance tests. For determination of functionality, leg symmetry indices (LSIs) were calculated by dividing values of the injured by the uninjured leg. In the ACL group most LSIs decreased from T₁ to T₂, and increased from T₂ and T₃ to T₄. LSIs of ACL subjects remained lower than LSIs of healthy controls at 6 months post-reconstruction in nearly all parameters. Self-evaluation of ACL subjects showed, additionally, that activity level was lower than the pre-injury level at 6 months post-reconstruction. Low LSIs and low self-evaluation indicate that knee joint functionality is not completely restored at 6 months post-reconstruction. The study shows that multiple comprehensive testing throughout the rehabilitation gives detailed images of the functional state. Therefore, the functional state of ACL reconstructed individuals should be evaluated comprehensively and continuously throughout the rehabilitation to detect persisting deficiencies detailed and adapt rehabilitation programs individually depending on the functionality.