Xavier D. Thompson

Context: Thirty percent of athletes go on to sustain a secondary anterior cruciate ligament (ACL) injury after return to sport. Those that went on to suffer a secondary injury had greater kinesiophobia levels at time of return to sport; however, these relationships have primarily been observed in patients after primary ACL reconstruction (ACLR). The purpose of this study is to compare differences in kinesiophobia 4 to 8 months after an individual’s primary versus secondary ACLR. Methods: This is a secondary analysis of an ongoing point of care study. To create our analytic sample, we identified participants between the ages of 14 and 35 years in the study protocol who provided data after primary and secondary ACLR, were 4 to 8 months status post-ACLR, and reported no concomitant surgical procedures at the time of primary or secondary ACLR that significantly delayed their rehabilitation protocol (e.g., meniscal repair). Demographic and participant characteristics and the Tampa Scale of Kinesiophobia-17 scores were collected after both primary and secondary ACLR. This study is a within-subjects design. Paired t tests were used to compare Tampa Scale of Kinesiophobia-17 scores between the primary and secondary ACLR. Results: Sixteen participants (male = 10, female = 6; height = 172.2 [11.5] cm, weight = 72.2 [20.9] kg) met inclusion criteria for the present study. Participants were 18.2 (3.0) years old and 5.6 (1.0) months since surgery after primary ACLR and 19.0 (1.0) years old and 5.9 (1.0) months since surgery after secondary ACLR. The average score for Tampa Scale of Kinesiophobia-17 was not different ( P = .77) after the primary (32.7 [5.0]) and secondary ACLR (33.1 [5.2]). Conclusion: There were no significant differences in kinesiophobia levels in individuals after their primary and secondary ACLR. Although nonsignificant, there is lack of resolution of kinesiophobia between primary and secondary ACLR.

Background: Prognostic indicators of lack of strength progression or poor self-reported function may alter rehabilitation decision-making following anterior cruciate ligament reconstruction (ACLR). The torque-velocity relationship is a noninvasive measure of muscle function that is altered following ACLR, but its prognostic value has not been explored. Purpose: To compare the torque-velocity relationship of knee extensors (quadriceps) and flexors (hamstrings) between the ACLR and uninvolved limbs and to determine whether the torque-velocity relationship was prognostic of subsequent achievement of satisfactory strength. Study Design: Cohort study; Level of evidence, 3. Methods: Participants following ACLR with bone–patellar tendon–bone or hamstring autografts completed isokinetic knee extension and flexion at 90°/s and 180°/s bilaterally, the International Knee Documentation Committee (IKDC) form, and Knee injury and Osteoarthritis Outcome Score (KOOS) at approximately 5.5 and 8.3 months post-ACLR. The torque-velocity relationship was defined as the difference in torque production across velocities, and relationships were analyzed using 2 × 2 analyses of variance. Binomial logistic regressions were used to determine the association between the torque-velocity relationship, age, sex, and time postsurgery with satisfactory knee extension strength, IKDC, and KOOS at visit 2. Results: This study included 189 participants (22.4 ± 9.3 years; 55.0% female). There were significant increases in the quadriceps torque-velocity relationship from visit 1 (0.22 Nm/kg) to visit 2 (0.34 Nm/kg, P < .001) but no differences in the uninvolved limb ( P = .46) or for the hamstrings ( P = .20). When controlling for sex, age, and graft type, higher visit 1 quadriceps torque-velocity relationships were predictive of a higher likelihood of achieving satisfactory knee extension strength (≥1.23 Nm/kg; odds ratio [OR], 1.05; P = .04). The model was associated with an acceptable IKDC score (≥75.9, P = .01), but the only significant individual predictor was age (OR, 0.94; P < .01). The model was not associated with KOOS Sport score at visit 2 ( P = .24). Conclusion: Quadriceps torque-velocity relationships of the ACLR limbs increased across time but remained less than uninvolved limbs. Hamstrings torque-velocity relationships remained similar between limbs and across time. These findings indicate that the torque-velocity relationship of the quadriceps changed over time and was predictive of future satisfactory strength. Clinical Relevance: Clinicians may use a greater quadriceps torque-velocity relationship as a positive indication of a patient's ability to achieve satisfactory strength later in rehabilitation.

Context : Following ACL reconstruction (ACLR) arthrogenic muscle inhibition limits quadriceps function. Arthrogenic muscle inhibition is characterized via a decreased central activation ratio and a higher active motor threshold. Although previous research has identified reductions in the torque–velocity relationship post-ACLR, our aim was to determine if this relationship is associated with measures of arthrogenic muscle inhibition following ACLR. Design : Cross-sectional. Methods : Nine participants (5 females and 4 males; 175.8 [7.8] cm, 79.4 [14.2] kg, 20.6 [28.8] mo postsurgery) following ACLR and 24 control participants (20 females and 4 males; 167.6 [8.1] cm, 66.9 [13.3] kg) completed isokinetic knee extension at 60, 90, 180, and 270°/s. A superimposed burst was delivered during maximal volitional isometric contraction using a square-wave stimulator to obtain central activation ratio. Transcranial magnetic stimulation was applied to obtain active motor threshold in ACLR involved limbs and control limbs. Correlations between 2-point torque–velocity relationships, central activation ratio, and active motor thresholds were analyzed separately by group with a false discovery rate correction applied. Results : The ACLR central activation ratio was not correlated with the torque–velocity relationship, but the control central activation ratio positively correlated with multiple 2-point torque–velocity relationships ( q < 0.05). The active motor threshold was higher in the ACLR participants (ACLR: 34.8 [7.8], control: 27.5 [9.4]). In the ACLR, the limbs active motor threshold was not correlated with torque–velocity relationships, but the control limb active motor threshold was correlated with T:V _60-0 ( r = .52, P < .001, q = 0.02); T:V _90-0 ( r = .47, P < .002, q = 0.024); T:V _180-0 ( r = .34, P = .04, q = 0.048); T:V _270-0 ( r = .37, P = .03, q = 0.045); and T:V _180-60 ( r = .41, P = .013, q = 0.037). Conclusion : Two-point torque–velocity relationships incorporating isometric contractions were associated with both voluntary activation and corticospinal excitability in healthy participants but not in ACLR limbs.

Context : The landing error scoring system (LESS) was developed to screen healthy individuals for anterior cruciate ligament (ACL) injury risk factors using a jump landing task. The purpose of this study was to evaluate unique landing error components of a modified LESS scoring criteria to determine its clinical utility in patients following ACL reconstruction (ACLR). Design : An observational cross-sectional study design was implemented to determine if each individual error component of the modified LESS provided unique information in an ACLR patient population. Methods : Post-ACLR patients (N = 194 [47.9% female]) completed the LESS 7.91 (1.80) months after surgery. To complete the LESS, patients stood on a 30-cm plyometric box and jumped down to a ground target, at 50% of their height in front of the box, then completed a maximal vertical jump. The LESS was repeated 3 times. Two video cameras positioned 3 m from the landing area at a height of 1 m above the floor (frontal and sagittal) recorded all trials. Video analysis of landing kinematics was performed to determine scores for each error item using the modified LESS. Itemized error scores for each patient were evaluated using an exploratory factor analysis, and factors were retained if eigenvalues were greater than 1. Results : Our exploratory factor analysis yielded 2 factor groupings. The first factor (λ = 1.61) was comprised of 4 biplanar error items (ie, errors that occur in both the frontal and sagittal plane) that evaluated body segment positioning (eg, hip and knee flexion during landing). The second factor (λ = 1.02) was comprised of 2 errors occurring in the frontal plane that evaluated knee valgus and the overall impression of their landing strategy. Conclusions : Reducing the modified LESS errors to 6-items could improve the efficiency and clinical utilization of the LESS in ACLR patients. An abbreviated version of the modified LESS may guide clinicians’ decision making in gauging patients’ readiness to return to play after ACLR.

Context: After completing rehabilitation, patients face a high risk of subsequent injury following anterior cruciate ligament reconstruction. It is important to identify potential barriers to patient success including clinician knowledge. The purpose of this study was to assess clinician knowledge of research related to anterior cruciate ligament reconstruction rehabilitation. Design: This was a survey study using snowball sampling. Methods: Survey development began with the creation of a construct map and contained varying levels of advanced concepts, level I indicating the most basic and level V the most complex. The survey was distributed to advertise to target population. A total of 60 participants (24 athletic trainers, 33 physical therapists, and 3 dual credentialed) completed the study. Results: Overall, participants displayed moderate to high levels of knowledge (79.7%–93.5% correct), apart from the implementation of motor learning principles. Conclusions: Clinician knowledge may not be the primary barrier to patient success, but the implementation of this knowledge should be explored in relation to patient outcomes. Future research should examine a larger cohort to examine differences between clinician types.

Background: Graft selection can influence strength and patient-reported outcomes (PROs) in adults undergoing anterior cruciate ligament reconstruction (ACLR). Yet, there is a lack of high-quality evidence comparing these results in adolescents. Purpose/Hypothesis: The purpose of this study was to determine differences in quadriceps and hamstring strength and PROs between adolescents with bone–patellar tendon–bone (BPTB), quadriceps tendon (QT), and hamstring tendon (HT) autografts. It was hypothesized that patients with QT and BPTB grafts would have greater impairments in knee extension, patients with HT grafts would have greater impairments in knee flexion, but PROs would be similar between graft types. Study Design: Cohort study; Level of evidence, 3. Methods: A total of 522 adolescents (mean age, 16.8 ± 1.8 years; 55% female) completed isokinetic knee strength testing at 60 deg/s, the International Knee Documentation Committee (IKDC) subjective knee form, the pediatric IKDC (Pedi-IKDC) subjective knee form, the Knee injury and Osteoarthritis Outcome Score (KOOS), and the Anterior Cruciate Ligament–Return to Sport after Injury (ACL-RSI) scale at 7.8 ± 1.5 months after ACLR. Weight-normalized strength was compared via linear mixed-effects models, and PROs were compared between graft types with the Kruskal-Wallis test. Results: After controlling for age, sex, time since surgery, and assessment site, patients with BPTB grafts had 10.8% less quadriceps strength in the ACLR limb ( P = .05) than patients with QT grafts and 20.4% less quadriceps strength ( P < .001) than patients with HT grafts, while patients with HT grafts had 9.6% more quadriceps strength ( P = .01) than patients with QT grafts. Patients with BPTB grafts had 3.1% more hamstring strength ( P < .01) than patients with QT grafts and 7.0% more hamstring strength ( P < .001) than patients with HT grafts. Patients with HT grafts had 10.8% less hamstring strength ( P < .01) than patients with QT grafts. Patients with QT grafts had lower IKDC scores (–7.2%; P < .001) than patients with HT grafts and higher KOOS Sports scores (+4.5%; P < .001) than patients with BPTB grafts. Patients with HT grafts had higher IKDC scores (+5.4%; P < .001) and higher KOOS Sports scores (+5.1%; P < .01) than patients with BPTB grafts. There were no differences in ACL-RSI scores ( P = .37). Conclusion: At 6 to 12 months after ACLR, patients with QT or BPTB grafts had worse normalized quadriceps strength but greater hamstring strength than patients with HT grafts. PROs were mixed, with no differences seen in ACL-RSI scores, but patients with HT grafts displayed greater self-reported function and a greater ability to participate in sport.

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.

Background: Evidence as to how patient thigh muscle strength and limb loading (LL) during a squatting task recovers throughout rehabilitation after anterior cruciate ligament reconstruction (ACLR) is lacking. Hypothesis: Patients will improve LL and strength throughout rehabilitation. Changes in LL and strength over time will be positively correlated. Study Design: Prospective cohort study. Level of Evidence: Level 3. Methods: A total of 60 participants (28 male/32 female; age, 22.5 ± 9.35 years) participated in 2 visits post-ACLR, assessing LL and strength. Using an instrumented pressure mat, patients completed 3 sets of 3 repetitions of bodyweight squats. Peak force (N), unilateral cumulative load (%), and quadriceps and hamstring isokinetic peak torque (N·m) were calculated and recorded bilaterally. LL and peak torque were compared over time and between limbs. Results: A significant limb-by-time interaction was observed for LL peak force (N), where patients underloaded the ACLR limb at visit 1 compared with the contralateral limb ( P < 0.01). Patients increased their ACLR LL across visits ( P = 0.04). A limb-by-time interaction for quadriceps peak torque (N·m) was observed where the ACLR limb increased peak torque across visits ( P < 0.01); however, strength deficits persisted at visit 2 ( P < 0.01) when compared with the nonoperative limb. Weak correlations were observed between all change scores metrics ( r , 0.20-0.25). Conclusion: Patients recovering from ACLR exhibited more symmetric loading during a squatting task and improved their lower extremity strength over time. Changes in strength were not related to changes in LL during a squatting task over time. Clinical Relevance: Squatting tasks are safe and easily implemented throughout ACLR recovery. As changes in functional LL and strength recovery are not related, both should be considered in serial postoperative testing for more comprehensive function and strength assessments.