Sex and mechanism of injury influence knee joint loading symmetry during gait 6 months after ACLR

Comparison of Limb Loading Characteristics and Subjective Functional Outcomes Between Sexes After Anterior Cruciate Ligament Reconstruction

CONTEXT

Anterior cruciate ligament reconstruction (ACLR) patients commonly adopt poor movement patterns that potentially place them at an increased risk for reinjury if untreated. Limb loading characteristics during functional tasks can highlight movement compensations.

OBJECTIVE

To examine loading symmetry during a bilateral bodyweight squatting task between sexes, compare loading metrics between limbs and sexes, and describe the relationship between loading metrics and patient-reported outcomes (PROs) after ACLR.

DESIGN

Cross-sectional study.

SETTING

Laboratory.

PATIENTS OR OTHER PARTICIPANTS

One hundred forty-two patients (71 male, 71 female, age = 24.4 ± 11.10 years) with a primary, unilateral, uncomplicated ACLR completed a squatting assessment and PRO measures at approximately 5.2 months post-ACLR.

MAIN OUTCOME MEASURE(S)

Normalized limb loading peak force (N/kg) and unilateral cumulative load (%) were collected bilaterally during the squatting task. Limb symmetry index (%) was calculated for normalized peak force. First, we compared limb loading symmetry (%) between sexes using an independent-samples t test. Second, we assessed differences in limb loading metrics between limbs and sexes via an analysis of covariance. Third, we used Spearman ρ correlations to determine the relationship between limb loading metrics and PROs.

RESULTS

The majority of individuals (91 of 142, 64.1%) offloaded their ACLR limb (ACLR = 6.6 ± 1.56 N/kg, contralateral = 7.3 ± 1.61 N/kg, P < .001). Females significantly offloaded their ACLR limb (ACLR = 6.3 ± 1.38 N/kg, contralateral = 7.2 ± 1.62 N/kg, P < .001) whereas males did not significantly offload their ACLR limb (ACLR = 6.98 ± 1.65 N/kg, contralateral = 7.4 ± 1.60 N/kg, P = .07). Weak relationships were observed (Ρ value range: -.23 to .19) across limb loading metrics and PROs.

CONCLUSIONS

Individuals approximately 5 months after ACLR, on average, offloaded their ACLR limb compared with the contralateral limb. Patients' tendency to offload their weight during a squat was influenced by sex. Relationships between limb loading metrics and PROs indicate patients who load their limbs disproportionately have a lower perception of their capability to complete activities of daily living and lower subjective knee function.

Prolonged quadriceps latency during gait early after anterior cruciate ligament injury predicts radiographic knee osteoarthritis 6-years after anterior cruciate ligament reconstruction

BACKGROUND

The purpose was to explore quadriceps electromechanical function (quadriceps latency) during gait after anterior cruciate ligament injury as a predictor for radiographic knee osteoarthritis 6-years after anterior cruciate ligament reconstruction. Change in latency after preoperative physical therapy was also examined.

METHODS

Quadriceps latency (time between peak knee moment and quadriceps electromyography) was calculated before preoperative physical therapy (2.4 [0.5-7.5] months after anterior cruciate ligament injury) and after preoperative physical therapy in 24 athletes. Participants were dichotomized into osteoarthritis (Kellgren and Lawrence grade ≥ 2) and non-osteoarthritis groups at 6-years. Forward selection logistic regression was performed using z-score normalized quadriceps latency and demographics. A 2 × 2 repeated measure ANOVA was performed for quadriceps latency between groups before and after preoperative physical therapy.

FINDINGS

Quadriceps latency before preoperative physical therapy was the only predictor of 6-year radiographic osteoarthritis (p = 0.014, odds ratio [95% confidence interval] = 5.859 [1.435-23.924]). Time by group interaction was observed for quadriceps latency (p = 0.039, η2p = 0.179). In the osteoarthritis group, latency may reduce after training (before preoperative physical therapy = 115.7 ± 20.6 ms, after preoperative physical therapy = 99.5 ± 24.0 ms, p = 0.082).

INTERPRETATION

Prolonged latency after anterior cruciate ligament injury may predict post-traumatic knee osteoarthritis 6-years after anterior cruciate ligament reconstruction. Latency may shorten with preoperative physical therapy, yet athletes still moved on to develop osteoarthritis. Quadriceps function may need intervention immediately following anterior cruciate ligament injury for prevention of post-traumatic knee osteoarthritis.

Regional healing trajectory of the patellar tendon after bone-patellar tendon-bone autograft harvest for anterior cruciate ligament reconstruction

Graft site morbidities after bone-patellar tendon-bone (BPTB) autograft harvest for anterior cruciate ligament reconstruction (ACLR) negatively impacts rehabilitation. The purpose of this study was to establish tendon structural properties 1-month after BPTB autograft harvest compared to the uninvolved patellar tendon, and subsequently to quantify the healing trajectory of the patellar tendon over the course of rehabilitation. Patellar tendon morphology (ultrasound) and mechanical properties (continuous shear wave elastography) from 3 regions of the tendon (medial, lateral, central) were measured in 34 participants at 1 month, 3-4 months, and 6-9 months after ACLR. Mixed models were used to compare tendon structure between limbs at 1 month, and quantify healing over 3 timepoints. The involved patellar tendon had increased cross-sectional area and thickness in all regions 1-month after ACLR. Thickness reduced uniformly over time. Possible tendon elongation was observed and remained stable over time. Tendon viscosity was uniform across the three regions in the involved limb while the medial region had higher viscosity in the uninvolved limb, and shear modulus was elevated in all three regions at 1 month. Viscosity and shear modulus in only the central region reduced over time. Statement of Clinical Significance: The entire patellar tendon, and not just the central third, is altered after graft harvest. Tendon structure starts to normalize over time, but alterations remain especially in the central third at the time athletes are returning to sport. Early rehabilitation consisting of tendon loading protocols may be necessary to optimize biologic healing at the graft site tendon.

Does fear of re-injury affect the self-perceived level of lower limb functionality among soccer players with ACL reconstruction?: A cross-sectional study

The fear of re-injury may persist after anterior cruciate ligament (ACL) reconstruction (ACLR) in professional soccer players (PSPs) even after a successful return to sport (RTS). This study aimed to determine the extent of this fear of re-injury and the impact of demographic variables and this fear of re-injury on the lower extremity functional scale (LEFS) scores in PSPs who had completed a successful RTS following ACLR. A cross-sectional survey design was used. Sixty-seven PSPs who had successfully RTS after ACLR, completed a demographic information sheet, the Athlete Fear-Avoidance Questionnaire (AFAQ), and the LEFS. The average AFAQ scores indicated low fear (M = 10.2, SD = 6.7), while high LEFS scores were observed (M = 67.1, SD = 12.4). There were significant strong negative correlations between LEFS and body mass index (BMI; rs [65] = -0.501, P = .001) and AFAQ and BMI (rs [65] = -0.378, P = .001). A hierarchical linear regression analysis found AFAQ to be a significant predictor of LEFS (b = -0.92, s.e. = 0.19, P = .001), with a total variance (adjusted R2) of 32.9%. PSPs' fear of re-injury post-ACLR significantly reduced their perceived levels of lower limb functionality. This study highlights the need to further explore and develop strategies to manage PSP fear of re-injury to improve sports-related performance post-ACLR.

Joint and Limb Loading during Gait in Adults with ACL Reconstruction: Comparison between Single-Step and Cumulative Load Metrics

PURPOSE

Individuals with anterior cruciate ligament reconstruction (ACLR) generally exhibit limb underloading behaviors during walking, but most research focuses on per-step comparisons. Cumulative loading metrics offer unique insight into joint loading as magnitude, duration, and total steps are considered, but few studies have evaluated if cumulative loads are altered post-ACLR. Here, we evaluated if underloading behaviors are apparent in ACLR limbs when using cumulative load metrics and how load metrics change in response to walking speed modifications.

METHODS

Treadmill walking biomechanics were evaluated in 21 participants with ACLR at three speeds (self-selected (SS); 120% SS and 80% SS). Cumulative loads per step and per kilometer were calculated using knee flexion and adduction moment (KFM and KAM) and vertical ground reaction force (GRF) impulses. Traditional magnitude metrics for KFM, KAM, and GRF were also calculated.

RESULTS

The ACLR limb displayed smaller KFM and GRF in early and late stances, but larger KFM and GRF during midstance compared with the contralateral limb ( P < 0.01). Only GRF cumulative loads (per step and per kilometer) were reduced in the ACLR limb ( P < 0.01). In response to speed modifications, load magnitudes generally increased with speed. Conversely, cumulative load metrics (per step and per kilometer) decreased at faster speeds and increased at slow speeds ( P < 0.01).

CONCLUSIONS

Patients with ACLR underload their knee in the sagittal plane per step, but cumulatively over the course of many steps/distance, this underloading phenomenon was not apparent. Furthermore, cumulative load increased at slower speeds, opposite to what is identified with traditional single-step metrics. Assessing cumulative load metrics may offer additional insight into how load outcomes may be impacted in injured populations or in response to gait modifications.

Bone-Patellar Tendon-Bone Autograft Harvest Prolongs Extensor Latency during Gait 2 yr after ACLR

PURPOSE

Bone-patellar tendon-bone (BPTB) graft harvest for anterior cruciate ligament reconstruction alters patellar tendon properties, which inflict poor quadriceps neuromuscular function. BPTB autografts are associated with higher rates of posttraumatic osteoarthritis, which in turn is associated with pathological gait. The purpose of this study was to investigate the latency between the time of peak quadriceps activity and the peak knee flexion moment during gait, between those with BPTB grafts ( n = 23) and other graft types (hamstring autograft or allografts, n = 54), 5 ± 2 months and 2 yr (25 ± 3 months) after anterior cruciate ligament reconstruction. We hypothesized that longer latencies would be observed in the BPTB graft group in the involved limb. We expected latencies to shorten over time.

METHODS

Knee moments and quadriceps EMG were collected during gait, and vastus medialis, vastus lateralis, rectus femoris (RF), and quadriceps latencies were calculated. Linear mixed-effects models were used to compare latencies between graft types and over the two time points.

RESULTS

The main effects of graft type were observed for vastus medialis ( P = 0.005) and quadriceps ( P = 0.033) latencies with the BPTB graft group demonstrating longer latencies. No main effects of graft type were observed for vastus lateralis ( P = 0.051) and RF ( P = 0.080) latencies. Main effects of time were observed for RF latency ( P = 0.022).

CONCLUSIONS

Our hypothesis that the BPTB graft group would demonstrate longer extensor latency was supported. Contrary to our second hypothesis, however, latency only improved in RF and regardless of graft type, indicating that neuromuscular deficits associated with BPTB grafts may persist 2 yr after surgery. Persistent deficits may be mediated by changes in the patellar tendon's mechanical properties. Graft-specific rehabilitation may be warranted to address the long-term neuromechanical deficits that are present after BPTB graft harvest.

Males and females have different muscle activity patterns during gait after ACL injury and reconstruction

Kinematic and kinetic changes following anterior cruciate ligament (ACL) rupture and reconstruction (ACLR) have been fundamental to the understanding of mechanical disrupted load as it contributes to the development of posttraumatic osteoarthritis. These analyses overlook the potential contribution of muscle activity as it relates to the joint loading environment. Males and females classified as non-copers present with unique knee kinematics and kinetics after ACL injury. The purpose of this study was to perform sex-specific analyses in these individuals to explore muscle activity timing during gait after ACL rupture. Thirty-nine participants (12 females, 27 males) were enrolled. Muscle activity during gait was evaluated before and after pre-operative physical therapy, and six months after ACLR. Surface electromyography data were evaluated to determine timing (e.g., the time the muscle activity begins ('On') and ends ('Off')) for seven muscles: vastus lateralis and medialis (VL, VM), lateral and medial hamstrings (LH, MH), lateral and medial gastrocnemius (LG, MG), and soleus (SOL). General linear models with generalized estimating equations detected the effects of limb and time for muscle activity timing. Males presented with more limb asymmetries before and after pre-operative PT in the VL On (p < 0.001) and Off (p = 0.007), VM On and Off (p < 0.001), and MH off (p < 0.001), but all limb differences resolved by six months post ACLR. Changes in muscle activity in males were pervasive over time in both limbs. Females presented with no interlimb differences pre-operatively, and only involved limb VL off (p = 0.027) and VM off (p = 0.003) and the LH off in both limbs (p < 0.038) changed over time. Our data indicate that inter-limb differences in muscle activity across time points and changes in muscle activity timing over the course of physical therapy were sex specific. Males presented with more inter-limb differences in muscle activity across time points, and females presented with fewer asymmetries before and after pre-operative physical therapy. These data support that sex-specific adaptations should be taken into consideration when assessing biomechanical changes after ACLR.

Characteristics of return to running programs following an anterior cruciate ligament reconstruction: A scoping review of 64 studies with clinical perspectives

OBJECTIVE

To (1) describe return to running (RTR) programs used during rehabilitation after anterior cruciate ligament reconstruction (ACLR); and (2) provide clinical guidelines for RTR program after ACLR.

DESIGN

Scoping review.

LITERATURE SEARCH

We searched the MEDLINE (Pubmed), EMBASE, Web of Science and PEDro databases.

STUDY SELECTION CRITERIA

We included randomized controlled trial (RCT), cases series, meta-analyses, both scoping and systematic reviews including a rehabilitation program after ACLR with a specific RTR program. A "Running program checklist" (RPC) was elaborated based on the Template for Intervention Description and Replication (TIDieR), and on the Consensus on Exercise Reporting Template (CERT) checklist.

DATA SYNTHESIS

The percentage and number of studies specifying each of the running program checklist items in their RTR program were reported. Number of items reported in each study and specific analysis item-by-item were also proposed.

RESULTS

The "When (2)" item was the most frequently found (92.19%) and, conversely, the "Who (1)" item appeared only in four studies (6.2%). One-third of the studies presented only one item of the RPC, and 48 of the 64 articles discussed less than three items. Two studies described in detail their RTR program by reporting 8 and 9 items out of the 10, respectively. No study presented 10 of the PRC items.

CONCLUSION

There is a serious lack of information concerning RTR program following ACLR in the literature and further studies are needed to establish a program based on the best evidence.

Identifying Gait Pathology after ACL Reconstruction Using Temporal Characteristics of Kinetics and Electromyography

PURPOSE

Asymmetrical gait mechanics after anterior cruciate ligament reconstruction (ACLR) are associated with the development of posttraumatic knee osteoarthritis. Current measures of gait mechanics have focused heavily on peak magnitudes of knee kinematics, kinetics, and joint contact forces but have seldom considered the rate of knee loading, cumulative knee load, or the timing of motor input surrounding peaks. The purpose of this study was to introduce and describe novel metrics of gait using temporal characteristics of kinetics and EMG to identify neuromuscular deficits of the quadriceps in patients after ACLR.

METHODS

Gait mechanics were assessed 6 months (n = 145) and 24 months (n = 116) after ACLR. External knee flexion rate of moment development (RMD) and knee flexion moment impulse (KFMI) leading up to the time of peak knee flexion moment (pKFM), peak RMD between initial contact to pKFM, and cumulative KFMI were calculated. Extensor latencies from the quadriceps, vastus medialis, vastus lateralis, and rectus femoris (time of pKFM - time of peak EMG activity) during the weight acceptance phase of gait were also calculated. Paired-sample t-tests (α = 0.05) were performed between limbs at both time points.

RESULTS

Slower RMD, smaller KFMI, and longer extensor latencies in the involved compared with uninvolved limb were observed across all measures at 6 months (P < 0.005). At 24 months, RMDpeak was slower, and KFMI50ms, KFMI100ms, and KFMItotal were lower in the involved limb (P < 0.003), but no other asymmetries were found.

CONCLUSIONS

Slower RMD, smaller KFMI, and prolonged extensor latencies may characterize neuromuscular deficits underlying aberrant gait mechanics early after ACLR. RMD, KFMI, and extensor latencies during gait should be considered in the future to quantify asymmetrical movement patterns observed after ACLR and as markers of recovery.

Innovative rehabilitative bracing with applied resistance improves walking pattern recovery in the early stages of rehabilitation after ACL reconstruction: a preliminary investigation

BACKGROUND

The use of knee braces early after anterior cruciate ligament (ACL) reconstruction is a controversial issue. The study preliminarily compares the effect of a traditional brace blocked in knee extension and a new functional brace equipped with a spring resistance on walking and strength performance early after ACL reconstruction performed in the acute/subacute stage.

METHODS

14 ACL-reconstructed patients wore either a traditional (Control group: CG, 7 subjects) or a new functional brace (Experimental group: EG 7 subjects) until the 30th post-operative day. All patients were tested before surgery (T0), 15, 30, and 60 days after surgery (T1, T2, and T3, respectively). Knee angular displacement and ground reaction forces (GRF) during the stance phase of the gait cycle were analyzed at each session and, at T3, maximal voluntary isometric contraction (MVIC) for knee flexor/extensor muscles was performed. Limb symmetry indexes (LSI) of GRF and MVIC parameters were calculated.

RESULTS

At T3, EG showed greater peak knee flexion angle of injured limb compared to CG (41 ± 2° vs 32 ± 1°, p < 0.001). During weight acceptance, a significant increase of anteroposterior GRF peak and vertical impulse from T1 to T3 was observed in the injured limb in EG (p < 0.05) but not in CG (p > 0.05). EG showed a greater side-to-side LSI of weight acceptance peak of anteroposterior GRF at T2 (113 ± 23% vs 69 ± 11%, p < 0.05) and T3 (112 ± 23% vs 84 ± 10%, p < 0.05).

CONCLUSIONS

The preliminary findings from this study indicate that the new functional brace did help in improving gait biomechanical pattern in the first two months after ACL reconstruction compared to a traditional brace locked in knee extension.