Flexor hallucis longus tendon morphology in dancers clinically diagnosed with tendinopathy

PURPOSE

The unique demands of dance technique make dancers more prone to certain pathologies especially of the foot and ankle. Flexor hallucis longus (FHL) tendinopathy, colloquially known as "dancer's tendinopathy," is common in dancers and not well studied. The purpose of this study was to assess if morphological alterations in tendon structure occur as an adaptive response to dance activity by comparing the FHL tendon in dancers to non-dancers, and if pathology further alters tendon morphology in dancers clinically diagnosed with tendinopathy.

METHODS

Three groups of ten participants were recruited (healthy non-dancers, healthy dancers, and dancers with FHL tendinopathy). Ultrasound images of the FHL tendons were analyzed for macromorphology by measuring the tendon thickness. The micromorphology was analyzed by determining the peak spatial frequency radius of the tendon. Our study did find increased tendon proper and composite tendon thickness in dancers with tendinopathy but no difference between asymptomatic dancers and non-dancers.

RESULTS

There was no significant difference in micromorphology found between any of the groups. As expected, dancers with tendinopathy demonstrated increased composite tendon and tendon proper thickness however, there was no evidence of adaptive thickening of the FHL tendon as might be expected for the dance population. There was also no evidence of micromorphological changes in the presence of clinically diagnosed FHL tendinopathy.

CONCLUSION

Because of the limited normative data for this pathology, these results can help improve diagnosis and therefore treatment for dancers to decrease the impact of this injury on their careers.

Implementation of a Comprehensive Anti-Racism Plan in an Academic Physical Therapy Department: An Administrative Case Report

OBJECTIVE

Transforming the University of Southern California health care system requires that institutions and organizations position equity, diversity, inclusion (EDI), and anti-racism as central to their missions. The purpose of this administrative case report was to describe a systematic approach taken by an academic physical therapy department to develop a comprehensive antiracism plan that engages all interested and affected parties and includes processes for sustainable, long-term engagement.

METHODS

Four strategies contributed to organizational change toward anti-racism: Holding Ourselves Accountable; Developing a Plan; Building Consensus; and Providing Education, Support, and Resources. The attitudes of faculty and staff about racism and anti-racist actions were assessed through surveys at the start of the process and after 1 year. Engagement in activities, meetings, and trainings related to EDI and anti-racism was logged for faculty and staff.

RESULTS

From November 2020 through November 2021, several outcomes were achieved, including: making structural organizational changes; updating faculty merit review to include EDI; developing a bias reporting mechanism; establishing faculty development activities, resources, and groups; and implementing structured efforts to recruit a diverse cohort. Within that year, faculty and staff engaged in 99.32 hours of EDI and anti-racism trainings, workshops, and resource groups. Survey data showed persistent high support and commitment to EDI and anti-racism. Faculty and staff reported that they felt more equipped to identify and address individual and institutional racism and they reported risking their reputations to talk about race more often. Confidence in their ability to identify and resolve conflicts related to microaggressions, cultural insensitivity, and bias improved. However, their self-reported ability to identify and address structural racism remained unchanged.

CONCLUSION

By approaching anti-racism as transformative rather than performative, an academic physical therapy department was able to develop and implement a comprehensive anti-racism plan with high support and engagement.

IMPACT

The physical therapy profession has not been immune to racism and health injustice. Organizational change to become anti-racist is imperative for excellence and a necessary challenge to undertake if the physical therapy profession is to transform society and improve the human experience.

Trunk control in and out of an episode of recurrent low back pain in young adults during the Balance-Dexterity Task

We investigated motor control strategies utilized by individuals with recurrent low back pain (rLBP) during active pain and remission periods as well as by back-healthy controls using the Balance-Dexterity Task. Nineteen young adults with rLBP were tested first when they were in pain and then again in symptom remission, and 19 matched controls were also tested. Trunk kinematic coupling and muscle co-activation were examined while participants performed the task by standing on one leg while compressing a spring with a maximum consistent force with the other leg. We found a decreased bilateral external oblique co-activation during the spring condition of the task compared to the stable block condition in people with rLBP compared to back healthy individuals. There was also reduced trunk coupling during the spring condition of the task compared to the stable block condition in both the rLBP active and remission groups, but no group difference between rLBP and back-healthy individuals. When individuals were in active pain, they exhibited more co-activation than when they were in remission, but the co-activation during active pain was not greater than in back-healthy individuals.

Lower Limb Takeoff Mechanics During a Leap in Dancers With and Without Flexor Hallucis Longus Tendinopathy

OBJECTIVE

Altered ground reaction force (GRF) and joint torsional stiffness are associated with various lower extremity injuries, but these have yet to be examined in dancers with flexor hallucis longus (FHL) tendinopathy. Additionally, a simple, field-friendly kinematic correlate to ground contact kinetics would be useful for clinical application. The purpose of this study was to compare lower extremity biomechanics during takeoff of a dance leap (saut de chat) in dancers with and without FHL tendinopathy, and to examine lower limb posture at initial contact as a clinical correlate of injury-related kinetic factors.

METHODS

Motion capture and inverse dynamics were used to analyze saut de chat takeoff performed by 11 uninjured dancers and 8 dancers with FHL tendinopathy. GRF parameters, joint torsional stiffness of the metatarsophalangeal, ankle, and knee joints, and lower extremity posture at initial contact were compared between groups using Welch's t-tests.

RESULTS

Dancers with FHL tendinopathy maintained similar jump height as the uninjured dancers, but exhibited lower peak vertical GRF, longer time to peak force, and less joint torsional stiffness at the metatarsophalangeal, ankle, and knee joints during loading response of the takeoff step. Lower extremity contact angle was smaller and the horizontal distance between center-of-mass and center-of-pressure was greater in dancers with FHL tendinopathy. These two measures of lower limb posture at initial contact were significantly correlated with kinetic factors occurring later in ground contact (R2=0.29-0.51).

CONCLUSION

Dancers with FHL tendinopathy demonstrated altered lower extremity kinetics during takeoff of a leap compared to uninjured dancers, which may contribute to, or be a compensation response to, injury.

Persons in remission from recurrent low back pain alter trunk coupling under dual-task interference during a dynamic balance task

This study investigated effects of cognitive dual-task interference and task prioritization instructions on task performance and trunk control during a dynamic balance task in persons with and without recurrent low back pain (rLBP). First, we tested the hypothesis that those with rLBP rely more on cognitive resources than back-healthy controls, and therefore trunk kinematics would be altered under dual-task interference conditions. Then, we tested participants' ability to modulate task performance in accord with prioritization instructions. Persons with and without rLBP (n = 19/group) performed the Balance-Dexterity Task, which involved single-limb balance while compressing an unstable spring with the other limb, with and without a cognitive task engaging verbal working memory. Trunk coupling was quantified with the coefficient of determination (R²) of an angle-angle plot of thorax-pelvis frontal plane motion. Task performance was quantified using variability of spring compression force and of cognitive task errors. Trunk coupling in the rLBP group was lower than that of the back-healthy control group in the single-task condition (p = 0.024) and increased in the dual-task condition (p = 0.006), abolishing the difference between groups. Significant main effects of task prioritization instruction on performance were observed with no differences between groups, indicating similar performance modulation. Cognitive task error variability decreased with a switch from a single- to dual-task condition, exposing an unexpected facilitation effect. We interpret these findings in the context of movement-specific reinvestment and action-specific perception theories as they pertain to cognitive contributions to posture and how the dual-task interference paradigm may influence those contributions.

Trunk and hip muscle activity during the Balance-Dexterity task in persons with and without recurrent low back pain

Coordination of the trunk and hips is crucial for successful dynamic balance in many activities of daily living. Persons with recurrent low back pain (rLBP), both while symptomatic and during periods of symptom remission, exhibit dysfunctional muscle activation patterns and coordination of these joints. In a novel dynamic balance task where persons in remission from rLBP exhibit dissociated trunk motion, it is unknown how trunk and hip musculature are coordinated. Activation of hip and trunk muscles were acquired from nineteen persons with and without rLBP during the Balance-Dexterity Task, which involves balancing on one limb while compressing an unstable spring with the other. There were no between-group differences in activation amplitude for any muscle groups tested. In back-healthy control participants, hip and trunk muscle activation amplitudes increased proportionally in response to the added instability of the spring (R = 0.837, p < 0.001). Increases in muscle activation amplitudes in the group in remission from rLBP were not proportional (R = 0.113, p = 0.655). Instead, hip muscle activation in this group was associated with task performance, i.e. dexterous control of the spring (R = 0.676, p = 0.002). These findings highlight atypical coordination of hip and trunk musculature potentially related to task demands in persons with rLBP even during remission from pain.

Characterizing the balance-dexterity task as a concurrent bipedal task to investigate trunk control during dynamic balance

The purpose of the study was to characterize the Balance-Dexterity Task as a means to investigate a concurrent bipedal lower-extremity task and trunk control during dynamic balance. The task combines aspects of single-limb balance and the lower-extremity dexterity test by asking participants to stand on one limb while compressing an unstable spring with the contralateral limb to an individualized target force. Nineteen non-disabled participants completed the study, and performance measures for the demands of each limb - balance and dexterous force control - as well as kinematic and electromyographic measures of trunk control were collected. Given five practice trials, participants achieved compression forces ranging from 100 to 139 N (mean 121.2 ± 12.3 N), representing 14.4-23.0% of body weight (mean 18.7 ± 2.4%), which were then presented as target forces during test trials. Dexterous force control coefficient of variation and average magnitude of the center of pressure (COP) resultant velocity were associated such that greater variability in force control was accompanied by greater COP velocity (R = 0.598, p = 0.007). Trunk coupling, quantified as the coefficient of determination (R²) of a frontal plane thorax and pelvis angle-angle plot, varied independently of any measure of balance or dexterous force control. The Balance-Dexterity Task is a continuous, dynamic balance task where bipedal coordination and trunk coupling can be concurrently observed and studied.

Toe Flexor Strength, Flexibility and Function and Flexor Hallucis Longus Tendon Morphology in Dancers and Non-Dancers

Tendinopathy of the flexor hallucis longus (FHL), colloquially referred to as "dancer's tendinitis," is a common condition in dancers and attributed to high demand on this muscle in positions of extreme ankle plantarflexion and metatarsophalangeal (MTP)) flexion and extension. Despite such a high prevalence, there has been little research into preventative or nonsurgical interventions. As a means to identify potential targets for prevention and intervention, this study aimed to characterize toe flexors in dancers by measuring strength, flexibility, function, and FHL tendon morphology. Dancers (n=25) were compared to non-dancers (n=25) in toe flexor isometric strength, first MTP joint range of motion, foot longitudinal arch flexibility, balance ability, endurance during modified heel raises without use of the toes, and FHL tendon thickness, cross-sectional area, and peak spatial frequency. Significant differences were found in functional first MTP joint extension (dancers 101.95°, non-dancers 91.15°, p<0.001), balance ability during single-leg stance on the toes (dancers 11.43 s, non-dancers 5.90 s, p=0.013), and during modified heel raises (dancers 22.20 reps, non-dancers 28.80 reps, p=0.001). Findings indicate that dancers rely on toe flexors more than non-dancers to complete balance and heel raise tasks. Efficacy of using this modified heel raise task with the toes off the edge of a block as a means to train larger plantarflexors and as a nonsurgical intervention should be studied in the future. Improving interventions for FHL tendinopathy will be impactful for dancers, in whom this condition is highly prevalent.

Increasing plantarflexion angle during landing reduces vertical ground reaction forces, loading rates and the hip's contribution to support moment within participants

The ankle joint's role in shock absorption during landing has been researched in many studies, which have found that landing with higher amounts of plantarflexion (PF) results in lower peak vertical ground reaction forces and loading rates. However, there has not yet been a study that compares drop landings within participants along a quantitative continuum of PF angles. Using a custom-written real-time feedback program, participants adjusted their ankles to an instructed PF angle and dropped onto two force platforms. For increasing PF, peak ground reaction force and peak loading rate during weight acceptance decreased significantly. The hip's contribution to peak support moment decreased as PF at initial contact increased up to 30°. The ankle and knee contributions increased over this same continuum of PF angles. There appears to be no optimal PF angle based on peak ground reaction force and loading rate measurements, but there may be an optimum where joint contributions to peak support moment converge and the hip moment's contribution is minimised.

Scapulothoracic and glenohumeral contributions to motion in children with brachial plexus birth palsy

BACKGROUND

Brachial plexus birth palsy occurs in 0.4 to 4.6 of every 1000 live births, with residual shoulder dysfunction in approximately one third of cases. Clinical measures, such as the Mallet classification, provide no insight into the scapulothoracic and glenohumeral contributions to tested global shoulder movements. This study describes the scapulothoracic and glenohumeral components of shoulder motion during the modified Mallet test.

METHODS

Twelve children with Erb's palsy (C5-6) and 8 children with extended Erb's palsy (C5-7) were recruited. The unaffected limbs of 6 subjects were also tested. Locations of markers placed on the thorax, humerus, and scapula were recorded in a neutral position and each of the modified Mallet positions. Scapulothoracic, glenohumeral, and humerothoracic helical displacements and acromion process linear displacements were compared between groups.

RESULTS

The brachial plexus birth palsy groups exhibited significantly smaller glenohumeral displacements in all modified Mallet positions and significantly larger scapulothoracic displacements in the global external rotation and hand to mouth positions. Discriminant function analysis using only humerothoracic variables correctly classified 76.9% of subjects. Discriminant function analysis incorporating scapulothoracic, glenohumeral, and acromion process displacement variables produced accuracy of 92.6%.

CONCLUSIONS

Children with brachial plexus birth palsy demonstrated decreased glenohumeral contributions to achieve every modified Mallet position and increased scapulothoracic contribution in two positions compared with the unaffected group. Different scapulothoracic and glenohumeral strategies were identified between groups. Finally, scapulothoracic and glenohumeral components of shoulder motion are more specific than humerothoracic measures to diagnostic classification.

Does accepting pharmacokinetic recommendations impact hospitalization? A cost-benefit analysis

In a prospective, randomized study, 110 adults receiving aminoglycosides were randomized to follow-up by a clinical pharmacokinetic service (CPS). Of the 110 patients, 35 accepted pharmacokinetic recommendations less than 100% of the time. The two groups were similar in age, sex, height, APACHE II score, and initial creatinine clearance. A cost-to-charge ratio was used to derive direct costs of hospitalization and calculate cost-benefit. Patients whose physicians accepted pharmacokinetic recommendations 100% of the time had shorter hospitalizations (322.67 +/- 270.28 h; CPS less than 100%, 699.54 +/- 806.35; p = 0.001) and febrile periods (50.05 +/- 79.38 h; CPS less than 100%, 120.00 +/- 153.23; p = 0.002). Acceptance of CPS recommendations led to adequate peak levels. Acceptance of CPS recommendations led to lower direct costs ($7,102.56 +/- 9,898.19; CPS less than 100%, $19,629.94 +/- 28,051.89; p less than 0.001). Calculated direct cost of the service was $85/patient.

Right-sided infective endocarditis as a consequence of flow-directed pulmonary-artery catheterization. A clinicopathological study of 55 autopsied patients

We studied 142 consecutively autopsied patients prospectively to determine the frequency and clinical importance of right-sided endocardial lesions in patients who had undergone flow-directed pulmonary-artery catheterization within one month of death. Of the 55 catheterized patients, 29 (53 per cent) had one or more right-sided endocardial lesions: 12 (22 per cent) had subendocardial hemorrhage, 11 (20 per cent) sterile thrombus, 2 (4 per cent) hemorrhage and thrombus, and 4 (7 per cent) infective endocarditis. Of 41 lesions seen in the 29 patients, 23 (56 per cent) were located on the pulmonic valve, 6 (15 per cent) on the tricuspid valve, 6 (15 per cent) in the right atrium, 4 (10 per cent) in the right ventricle, and 2 (5 per cent) in the main pulmonary artery. All four patients with infective endocarditis had had positive antemortem blood cultures while the catheter was in place, but in only one had the diagnosis of endocarditis been suspected clinically. The unusual locations of the infected vegetations (on the pulmonic valve in three and in the right atrium in one) and the similar location of the uninfected lesions suggest that the infective endocarditis was a consequence of catheter-induced endocardial damage with concurrent or subsequent bacteremia. Among the 87 non-catheterized patients, there were two subendocardial hemorrhages and one resolving right atrial thrombus. We conclude that endocardial damage from flow-directed pulmonary-artery catheterization is common and that right-sided infective endocarditis should be suspected in bacteremic catheterized patients.