Validity of a commercially available load cell dynamometer in measuring isometric knee extension torque in patients with knee disorders.

OBJECTIVE: Assess the validity of hand-held dynamometry (HHD) and the Tindeq Progressor (TP) in assessing peak isometric knee extension torque and limb symmetry index (LSI) versus isokinetic dynamometer (IKD). DESIGN: Prospective cross-sectional study. SETTING: Laboratory. PARTICIPANTS: 31 individuals with unilateral knee disorders (21 female; 28.3 ± 11 years). MAIN OUTCOME MEASURES: Peak isometric knee extension torque; Knee extension LSI. RESULTS: Strong to almost perfect (p < 0.001) correlations (Cohen's Kappa k) with IKD were found for both devices for peak torque of the uninvolved limb (HHD [k = 0.84], TP [k = 0.91]) and involved limb (HHD [k = 0.93], TP [k = 0.98]). For LSI, moderate to strong (p < 0.001) correlations with IKD were found for HHD (k = 0.79) and TP (k = 0.89). Mean bias errors were equivalent for determining LSI (HHD = 0.02%; TP = 0.03%). Both HHD and TP were highly sensitive (96.2-100.0%) and specific (100.0%) at the 70% LSI threshold. TP showed higher sensitivity and specificity at the 90% LSI threshold. CONCLUSION: HHD and TP are valid in measuring isometric knee extension torque with the reference standard IKD. TP showed superior validity in identifying LSI. TP also shows greater specificity in identifying the 90% LSI threshold.

Biomechanics of landing in injured and uninjured chickens and the role of meloxicam.

Birds use their legs and wings when transitioning from aerial to ground locomotion during landing. To improve our understanding of the effects of footpad dermatitis (FPD) and keel bone fracture (KBF) upon landing biomechanics in laying hens, we measured ground-reaction forces generated by hens (n = 37) as they landed on force plates (Bertec Corporation, Columbus, OH) from a 30 cm drop or 170 cm jump in a single-blinded placebo-controlled trial using a cross-over design where birds received an anti-inflammatory (meloxicam, 5 mg/kg body mass) or placebo treatment beforehand. We used generalized linear mixed models to test for effects of health status, treatment and their interaction on landing velocity (m/s), maximum resultant force (N), and impulse (force integrated with respect to time [N s]). Birds with FPD and KBF tended to show divergent alterations to their landing biomechanics when landing from a 30 cm drop, with a higher landing velocity and maximum force in KBF compared to FPD birds, potentially indicative of efforts to either reduce the use of their wings or impacts on inflamed footpads. In contrast, at 170 cm jumps fewer differences between birds of different health statuses were observed likely due to laying hens being poor flyers already at their maximum power output. Our results indicate that orthopedic injuries, apart from being welfare issues on their own, may have subtle influences on bird mobility through altered landing biomechanics that should be considered.

Desmoid fibromatosis presenting as lateral hip pain in an outpatient physical therapy clinic: A case report.

CASE DESCRIPTION: A 21-year-old healthy female presented with severe left lateral hip pain beginning suddenly two weeks prior. Physical examination revealed zero degrees of left hip external rotation passive range of motion with a firm end feel and pain severity and irritability out of proportion to an expected musculoskeletal presentation. She was referred to her physician with a recommendation for imaging to determine the source of pain and appropriateness of physical therapy. OUTCOME: Magnetic resonance imaging revealed a foreign mass in her left gluteus medius muscle which biopsy revealed to be a desmoid fibromatosis. CONCLUSION: This case demonstrates a thorough differential diagnostic process leading to medical imaging referral in a patient with a non-musculoskeletal source of pain. Physical therapists must be diligent in their differential diagnostic process to ensure appropriateness of their treatments or the need for referral.

Running Biomechanics in Individuals with Anterior Cruciate Ligament Reconstruction: A Systematic Review.

BACKGROUND: A return to running after anterior cruciate ligament reconstruction (ACL-R) is critical to the clinical success of any cutting and pivoting athlete who wishes to return to sport. Knowledge of specific alterations during running after ACL-R is required to optimise rehabilitation for improving outcomes and long-term disability. OBJECTIVE: The objective of this systematic review was to summarise kinematic, kinetic and muscle activation data during running after ACL-R and the intrinsic factors (e.g. surgical technique and strength asymmetries) affecting running biomechanics. METHODS: MEDLINE, EMBASE, SPORTDiscus and CINAHL databases were searched from inception to 10 December, 2018. The search identified studies comparing kinematic, kinetic or muscle activation data during running between the involved limb and contralateral or control limbs. Studies analysing the effect of intrinsic factors in the ACL-R group were also included. Risk of bias was assessed, qualitative and quantitative analyses performed, and levels of evidence determined. RESULTS: A total of 1993 papers were identified and 25 were included for analysis. Pooled analyses reported a deficit of knee flexion motion and internal knee extension moment, compared with both contralateral or control limbs, during the stance phase of running from 3 months to 5 years after ACL-R (strong evidence). Inconsistent results were found for both peak vertical ground reaction force and impact forces after ACL-R. Patellofemoral and tibiofemoral joint contact forces differed from both contralateral or control limbs up until at least 2.5 years after ACL-R and moderate evidence indicated no difference for muscle activations during moderate speed running. Quadriceps and hamstring strength asymmetries, and knee function, but not surgical techniques, were likely to be associated with both knee kinematics and kinetics during running after ACL-R. CONCLUSION: After ACL-R, knee flexion motion and internal knee extension moment are the most affected variables and are consistently smaller in the injured limb during running when pooling evidence. Clinicians should be aware that these deficits do not appear to resolve with time and, thus, specific clinical interventions may be needed to reduce long-term disability. SYSTEMATIC REVIEW REGISTRATION: Registered in PROSPERO 2017, CRD42017077130.

Clinical Efficacy of Jump Training Augmented With Body Weight Support After ACL Reconstruction: A Randomized Controlled Trial.

BACKGROUND: Limited knee flexion and increased muscle co-contraction during jump landing are believed to diminish outcomes after anterior cruciate ligament (ACL) reconstruction. The efficacy of jump training to improve patients' mechanical and neuromuscular deficits is understudied. HYPOTHESIS: Jump training will improve functional, mechanical, and neuromuscular outcomes and higher repetition training augmented by body weight support will result in better retention of gains. STUDY DESIGN: Randomized controlled trial; Level of evidence, 1. METHODS: Thirty athletes (18 months after surgery) were screened, and 19 with mechanical deficits and limited clinical outcomes were enrolled in the trial. Testing included the International Knee Documentation Committee (IKDC) questionnaire, leg landing mechanics via motion analysis, knee joint effusion using a stroke test, and a surface electromyography-generated co-contraction index during a single-legged landing. Participants were randomly assigned to 1 of 2 groups: jump training with normal body weight (JTBW) and high-repetition jump training with body weight support (JTBWS). Knee effusion grading throughout training was used to assess joint tolerance. Changes in outcomes over time were analyzed with mixed-effects modeling. Immediate outcomes were compared with retention testing at 8 weeks after training by use of 2-way analyses of variance with effects of time and group. RESULTS: Significant effects of time were found during the training phase for all outcome measures, but no effects of group or sex were found. IKDC score (pooled; mean ± SD) increased from 76 ± 12 to 87 ± 8 ( P < .001). Knee flexion during single-legged landing increased from 57° ± 11° to 73° ± 9° ( P < .001). Average co-contraction index decreased from 37 ± 15 to 19 ± 6 ( P < .001). All measures were retained over the retention period in both groups. The relative risk of knee effusion of the JTBW group versus the JTBWS group was 4.2 (95% CI, 2.25-7.71; P < .001). CONCLUSION: Jump training mitigated some risk factors for second injury and osteoarthritis in patients after ACL reconstruction. Training made lasting improvements in physical function measures as well as mechanical and neuromuscular coordination deficits. Higher repetitions used with body weight support did not improve retention but substantially reduced risk for effusion. CLINICAL RELEVANCE: Jump training is an efficacious intervention for athletes with poor outcomes after ACL reconstruction, and training with body weight support lessens the risk for excessive joint stress during practice. Registration: NCT02148172 ( ClinicalTrials.gov identifier).

The Effect of Body Weight Support on Kinetics and Kinematics of a Repetitive Plyometric Task.

Though essential to athletic performance, the ability to land from a jump often remains limited following injury. While recommended, jump training is difficult to include in rehabilitation programs due to high impact forces. Body weight support (BWS) is frequently used in rehabilitation of gait following neurological and orthopedic injury, and may also allow improved rehabilitation of high-impact tasks. There is a differential effect of BWS on walking and running gaits, and the effect of BWS on movements with relatively large vertical displacement is unknown. The current study evaluates the effect of BWS on a replicable single-leg hopping task. We posited that progressive BWS would decrease limb loading while maintaining the joint kinematics of the task. Twenty-eight participants repetitively hopped on and off a box at each of four BWS levels. Peak vertical ground reaction forces decreased by 22.5% between 0% and 30% BWS (P < .001). Average hip, knee, and ankle internal moments decreased by 0.5 N·m/kg each. Slight kinematic changes across BWS levels were clinically insignificant. The high level of task specificity evidenced by consistent kinematics coupled with a similar reduction of internal moment at each joint suggests that BWS may be a useful strategy for rehabilitation of jumping tasks.

HIGH REPETITION JUMP TRAINING COUPLED WITH BODY WEIGHT SUPPORT IN A PATIENT WITH KNEE PAIN AND PRIOR HISTORY OF ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION: A CASE REPORT.

BACKGROUND AND PURPOSE: Patients frequently experience long-term deficits in functional activity following anterior cruciate ligament reconstruction, and commonly present with decreased confidence and poor weight acceptance in the surgical knee. Adaptation of neuromuscular behaviors may be possible through plyometric training. Body weight support decreases intensity of landing sufficiently to allow increased training repetition. The purpose of this case report is to report the outcomes of a subject with a previous history of anterior cruciate ligament (ACL) reconstruction treated with high repetition jump training coupled with body weight support (BWS) as a primary intervention strategy. CASE DESCRIPTION: A 23-year old female, who had right ACL reconstruction seven years prior, presented with anterior knee pain and effusion following initiation of a running program. Following visual assessment of poor mechanics in single leg closed chain activities, landing mechanics were assessed using 3-D motion analysis of single leg landing off a 20 cm box. She then participated in an eight-week plyometric training program using a custom-designed body weight support system. The International Knee Documentation Committee Subjective Knee Form (IKDC) and the ACL-Return to Sport Index (ACL-RSI) were administered at the start and end of treatment as well as at follow-up testing. OUTCOMES: The subject's IKDC and ACL-RSI scores increased with training from 68% and 43% to 90% and 84%, respectively, and were retained at follow-up testing. Peak knee and hip flexion angles during landing increased from 47 ° and 53 ° to 72 ° and 80 ° respectively. Vertical ground reaction forces in landing decreased with training from 3.8 N/kg to 3.2 N/kg. All changes were retained two months following completion of training. DISCUSSION: The subject experienced meaningful changes in overall function. Retention of mechanical changes suggests that her new landing strategy had become a habitual pattern. Success with high volume plyometric training is possible when using BWS. Clinical investigation into the efficacy of body weight support as a training mechanism is needed. LEVEL OF EVIDENCE: Level 4 - Case Report.

Changes in quadriceps and hamstring cocontraction following landing instruction in patients with anterior cruciate ligament reconstruction.

STUDY DESIGN: Pretest/posttest controlled laboratory study. OBJECTIVES: To determine changes in the neuromuscular activation of the quadriceps and hamstrings following instructions aimed at improving knee flexion during a single-limb landing task in persons who have undergone anterior cruciate ligament reconstruction (ACLR). BACKGROUND: Clinicians advise patients who have undergone ACLR to increase knee flexion during landing tasks to improve impact attenuation. Another long-standing construct underlying such instruction involves increasing cocontraction of the hamstrings with the quadriceps to limit anterior shear of the tibia on the femur. The current study examined whether cocontraction of the knee musculature changes following instruction to increase knee flexion during landing. METHODS: Thirty-four physically active subjects with unilateral ACLR participated in a 1-time testing session. The kinetics and kinematics of single-leg landing on the surgical limb were analyzed before and after instruction to increase knee flexion and reduce the impact of landing. Vastus lateralis and biceps femoris activities were analyzed using surface electromyography and normalized to a maximal voluntary isometric contraction (MVIC). Cocontraction indices were integrated over the weight-acceptance phase of landing. RESULTS: Following instruction, peak knee flexion increased (preinstruction mean ± SD, 56° ± 11°; postinstruction, 77° ± 12°; P<.001) and peak vertical ground reaction forces decreased (preinstruction, 3.50 ± 0.42 body mass; postinstruction, 3.06 ± 0.44 body mass; P<.001). Cocontraction also decreased following instruction (preinstruction, 30.88% ± 17.68% MVIC; postinstruction, 23.74% ± 15.39% MVIC; P<.001). The change in cocontraction was correlated with a decrease in hamstring activity (preinstruction, 23.79% ± 12.88% MVIC; postinstruction, 19.72% ± 13.92% MVIC; r = 0.80; P<.001). CONCLUSION: Landing instruction produced both a statistically and clinically significant change in landing mechanics in persons post-ACLR. Conscious improvement of the absorptive power of the surgical limb was marked by decreased hamstring activity and cocontraction during single-limb landing.