1,721,075 research outputs found
A case highlighting the influence of knee joint effusion on muscle inhibition and size.
No full textBACKGROUND:
The patient sustained an injury that caused knee joint effusion. The patient had undergone reconstruction of the anterior cruciate ligament on the right knee approximately 8 years before this injury.
INVESTIGATIONS:
The influence of knee joint effusion on the isometric and dynamic torque characteristics, neural drive and muscle size of the knee extensors was analyzed during the first 11 weeks of recovery. Maximum knee extensor torque and electromyographic (EMG) activity were assessed on a weekly basis. MRI scans of the thigh were taken to quantify vastus medialis muscle cross-sectional area.
DIAGNOSIS:
Initial knee joint aspiration resulted in an 85-399% increase in isometric knee extensor torque and a 9-706% increase in vastus lateralis and vastus medialis muscle EMG activity, indicating muscle inhibition due to effusion. The knee extensors were inhibited to a greater extent in the most flexed position than in the more extended knee joint positions. After the initial aspiration, the knee extensor torque-velocity relationship increased by 56-453% with a corresponding increase in EMG activity.
MANAGEMENT:
Repetition of aspiration and instigation of a resistance training program resulted in the injured leg having a torque and muscle size comparable with the contralateral healthy leg 11 weeks after initiation of the rehabilitation program
Human patellar tendon stiffness is restored following graft harvest for anterior cruciate ligament surgery.
No full textMinimising post-operative donor site morbidity is an important consideration when selecting a graft for surgical reconstruction of the torn anterior cruciate ligament (ACL). One of the most common procedures, the bone-patellar tendon-bone (BPTB) graft involves removal of the central third from the tendon. However, it is unknown whether the mechanical properties of the donor site (patellar tendon) recover. The present study investigated the mechanical properties of the human patellar tendon in 12 males (mean+/-S.D. age: 37+/-14 years) who had undergone surgical reconstruction of the ACL using a BPTB graft between 1 and 10 years before the study (operated knee; OP). The uninjured contralateral knee served as a control (CTRL). Patellar tendon mechanical properties were assessed in vivo combining dynamometry with ultrasound imaging. Patellar tendon stiffness was calculated from the gradient of the tendon's force-elongation curve. Tendon stiffness was normalised to the tendon's dimensions to obtain the tendon's Young's modulus. Cross-sectional area (CSA) of OP patellar tendons was larger by 21% than CTRL tendons (P<0.01). Patellar tendon stiffness was not significantly different between OP and CTRL tendons, but the Young's modulus was lower by 24% in OP tendons (P<0.01). A compensatory enlargement of the patellar tendon CSA, presumably due to scar tissue formation, enabled a recovery of tendon stiffness in the OP tendons. The newly formed tendon tissue had inferior properties as indicated by the reduced tendon Young's modulus, but it increased to a level that enabled recovery of tendon stiffness
Accelerator pedal control in diabetes: influence of ankle proprioception and muscle strength
No full textAims
Diabetic peripheral neuropathy (DPN) influences neural sensitivity, nerve conduction velocity, proprioception and muscle strength. The aim of this work was to investigate whether the speed of strength generation (SSG) and/or proprioception function of the plantarflexor muscles in people with diabetes both with and without peripheral neuropathy would affect accelerator pedal control on a driving simulator.
Methods
Fifty-four active drivers, 15 with DPN (DPN, aged 66±6.0yrs), 25 with diabetes but no neuropathy (DM, aged 62±8.7yrs) and 14 controls without diabetes (C, aged 58±10yrs), undertook a maximum isometric muscle test of the plantarflexor muscles and a proprioception test of the right ankle joint using a dynamometer, in addition to a driving task using a driving simulator. We measured SSG (Nm/s), proprioception error values (degrees) and accelerator pedal position (degrees) from these tests, respectively.
Results
The DM and DPN groups showed significantly lower values for SSG with respect to C (DPN: 80.9±58.4; DM: 134.2±89.3; C: 233±135.4 Nm/s; p0.05), and the lowest value of accelerator pedal displacement during the driving test (DPN: 1.8±0.8; DM 3.1±0.6; C: 2.9±0.7 deg; p>0.05) with respect to DM and C groups.
Conclusions
Whilst not affecting people with diabetes without neuropathy, reduced ankle joint proprioception together with a slower production of plantarflexor muscle strength seems to influence accelerator pedal control during a driving simulation task in people DPN
Persisting side-to-side differences in bone mineral content, but not in muscle strength and tendon stiffness after anterior cruciate ligament reconstruction.
No full textTendon stiffness may be involved in limiting peak musculoskeletal forces and thus may constitute an upper limit for bone strength. The patellar tendon bone (PTB) graft, which is harvested from the patellar tendon during surgical reconstruction of the anterior cruciate ligament (ACL), is an ideal scenario to test this hypothesis. Eleven participants were recruited who had undergone surgical reconstruction of the ACL with a PTB graft 1-10 years prior to study inclusion. As previously reported, there was no side-to-side difference in thigh muscle cross-sectional area, in maximum voluntary knee extension torque, or in patellar tendon stiffness, suggesting full recovery of musculature and tendon. However, in the present study bone mineral content (BMC), assessed by peripheral quantitative computed tomography, was lower on the operated side than on the control side in four regions studied (P = 0·0019). Differences were less pronounced in the two sites directly affected by the operation (patella and tibia epiphysis) when compared to the more remote sites. Moreover, significant side-to-side differences were found in BMC in the trabecular compartment in the femoral and tibial epiphysis (P = 0·004 and P = 0·047, respectively) with reductions on the operated side, but increased in the patella (P = 0·00016). Cortical BMC, by contrast, was lower on the operated side at all sites except the tibia epiphysis (P = 0·09). These findings suggest that impaired recovery of BMC following ACL reconstruction is not because of lack of recovery of knee extensor strength or patellar tendon stiffness. The responsible mechanisms still remain to be determined
Patellar tendon adaptation in relation to load-intensity and contraction type.
No full textBACKGROUND:Loading leads to tendon adaptation but the influence of load-intensity and contraction type is unclear. Clinicians need to be aware of the type and intensity of loading required for tendon adaptation when prescribing exercise. The aim of this study was to investigate the influence of contraction type and load-intensity on patellar tendon mechanical properties.
METHOD:
Load intensity was determined using the 1 repetition maximum (RM) on a resistance exercise device at baseline and fortnightly intervals in four randomly allocated groups of healthy, young males: (1) control (no training); (2) concentric (80% of concentric-eccentric 1RM, 4×7-8); (3) standard load eccentric only (80% of concentric-eccentric 1RM, 4×12-15 repetitions) and (4) high load eccentric (80% of eccentric 1RM, 4×7-8 repetitions). Participants exercised three times a week for 12 weeks on a leg extension machine. Knee extension maximum torque, patellar tendon CSA and length were measured with dynamometry and ultrasound imaging. Patellar tendon force, stress and strain were calculated at 25%, 50%, 75% and 100% of maximum torque during isometric knee extension contractions, and stiffness and modulus at torque intervals of 50-75% and 75-100%. Within group and between group differences in CSA, force, elongation, stress, strain, stiffness and modulus were investigated. The same day reliability of patellar tendon measures was established with a subset of eight participants.
RESULTS:
Patellar tendon modulus increased in all exercise groups compared with the control group (p<0.05) at 50-75% of maximal voluntary isometric contraction (MVIC), but only in the high eccentric group compared with the control group at 75-100% of MVIC (p<0.05). The only other group difference in tendon properties was a significantly greater increase in maximum force in the high eccentric compared with the control group (p<0.05). Five repetition maximum increased in all groups but the increase was significantly greater in the high load eccentric compared with the other exercise groups (p<0.05).
CONCLUSION:
Load at different intensity levels and contraction types increased patellar tendon modulus whereas muscle strength seems to respond more to load-intensity. High load eccentric was, however, the only group to have significantly greater increase in force, stiffness and modulus (at the highest torque levels) compared with the control group. The effects and clinical applicability of high load interventions needs to be investigated further
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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