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Significance of the internal locking mechanism for loop security enhancement in the arthroscopic knot.

PURPOSE: Secure tissue fixation of an arthroscopic knot depends on the security of the initial loop and additional locking half-hitches. The purpose of this report is to evaluate the loop and knot security relative to the internal locking mechanism of arthroscopic slip knot. TYPE OF STUDY: This is an experimental study designed for knot and loop security on a material testing system. The measurements were carried out in a blinded fashion in which the tester was not aware of the type of knot being tested. METHODS: Five configurations of arthroscopic knots (overhand throw, Duncan loop, Revo knot, Tennessee slider, and SMC knot) were created around a 5-mm diameter metal bar using a No. 2 braided suture. For each knot configuration, 10 knots were tested for displacement at cyclic loading, load to clinical failure (3-mm displacement), ultimate failure load, and mode of failure on the servo-hydraulic material testing system (MTS 858 MiniBionix test system; MTS, Minneapolis, MN). A 1-way analysis of variance was used to determine the statistical difference in displacement at cyclic loading, load to clinical failure, and ultimate failure load between each knot configuration. RESULTS: In the cyclic loading test, the average displacement of all knots was clinically insignificant, with the average being less than 0.24 mm. The overhand throw had the worst characteristic in the load to failure test. The other 4 knots had an optimal load to failure. The SMC knot, which has an internal locking mechanism, had good loop and knot security in the load to clinical failure and ultimate failure load (P <.05). The SMC and the Revo knots failed by knot breakage (material failure) whereas the other knots failed by knot slippage (loop failure). CONCLUSIONS: The internal locking mechanism flips the post strand to convert the loop strand into a new post strand while rerouting the original post strand around a new post. An arthroscopic knot with an internal locking mechanism can enhance loop security.

Analysis of Variance↗

Internal impingement in the etiology of rotator cuff tendinosis revisited.

PURPOSE: The theory of internal impingement holds that, in overhead athletes, repeated contact between the undersurface of the rotator cuff and the posterosuperior glenoid rim leads to articular-sided partial-thickness rotator cuff tears and superior labral lesions. However, we have noted this same constellation of lesions in our general patient population. These recreational athletic patients do not routinely assume the position of extreme abduction and external rotation, and thus are unlikely to experience significant internal impingement forces. The goal of this study was to document the prevalence of superior labral lesions in patients being treated for partial-thickness undersurface rotator cuff tears. TYPE OF STUDY: Retrospective case series. METHODS: We retrospectively reviewed the records of 75 shoulders arthroscopically treated for partial-thickness articular-sided rotator cuff tears. With the exception of one professional tennis player, no patients were playing sports at a professional or major college level. No professional or collegiate throwing athletes were included. The prevalence of these lesions and their association with recreational athletics was noted. RESULTS: We found that 55 of 75 (73.3%) shoulders with articular-sided partial-thickness rotator cuff tears also had superior labral lesions. A statistically significant increased prevalence of superior labral lesions in the dominant shoulder was seen (P =.03). In addition, our patients who engaged in overhand throwing had significantly fewer superior labral lesions in the dominant shoulders than did nonthrowers (P =.017). CONCLUSIONS: The "kissing lesions" of undersurface rotator cuff tears and posterosuperior labral damage may be explained by mechanisms other than "internal impingement."

Adolescent↗

Arthroscopic acromioplasty: a 6- to 10-year follow-up.

Arthroscopic acromioplasty has become a common procedure for the treatment of chronic impingement syndrome. Short-term studies have consistently shown good results; however, long-term data have not previously been reported in the literature. Of 102 consecutive patients undergoing arthroscopic acromioplasty at our institution from 1984 to 1988, 82 patients (83 shoulders) were available for evaluation. The patients were reviewed after a mean of 8 years, 5 months from their original surgery. There were 16 failures (19%) with unsatisfactory results following surgery; 13 patients (15%) required further surgery to relieve persistent pain. Thirty-three percent of all patients previously involved in sports were unable to return to overhead and throwing sports due to pain and lack of power with throwing. Overall, 81% of patients in our series had good to excellent results after 6 to 10 years. To optimize the indications for the procedure, other causes of impingement, such as occult instability and degenerative joint disease, should be ruled out. Throwers may have difficulty returning to their sport at the same level of intensity, and should be addressed independently.

Acromion↗

Prism adaptation in normal aging: slower adaptation rate and larger aftereffect.

The effect of aging on prism adaptation, a motor learning paradigm, was evaluated. Different measures were obtained from a task consisting of throwing clay balls to a target in front of the subjects before, during, and after wearing prisms that deviate the visual field by several degrees. When performing the task without wearing the prisms, the aged subjects showed a larger hit variance, whereas the young subjects hit closer to the target. When donning the prisms, the aged group adapted more slowly than the controls, although after throwing all the balls both groups showed the same adaptation levels. After removing the prisms, the aged group showed a larger aftereffect. These findings suggest that the aftereffect requires the involvement of non-cognitive and cognitive processes and indicate that both adaptation and aftereffect are influenced by aging.

Adaptation, Physiological↗

Normal kinematics of the unconstrained glenohumeral joint under coupled moment loads.

The glenohumeral joint presents difficult experimental challenges, large ranges of motion, coupled motions, and multi-planar motions. Many biomechanical tests performed on the glenohumeral joint constrain it or provide conditions that might not be reproducible within and among specimens or treatments. The goal of this study was to determine a means to test the glenohumeral joint in vitro with coupled moments applied to the unconstrained humerus and recording its "6 degrees of freedom" motion relative to the glenoid. This procedure was achieved with the development of a new testing apparatus. Kinematics were described in abduction-adduction, flexion-extension, and abduction, extension, and external rotation, simulating the cocked phase of throwing. The advantage of the techniques was that only the glenohumeral capsule and articular surface contact control the motion of the humerus in response to the applied loading pattern. Also, the motions were unconstrained by the loading apparatus, allowing coupling of rotations and translations and multiplanar motions. Rotations were found to be coupled with translations. For adduction-abduction and flexion-extension, the humeral head was found to translate first in 1 direction, opposite the direction of increasing rotation, at low moments. Then, with increasing moment and angle of rotation, translations changed direction and moved with the primary motion. This occurrence indicates the existence of a region of joint laxity or neutral zone. Rotations were found to be coupled during motion to the cocked position of throwing, as the humerus adducted with extension from full abduction and then adducted further and extends with external rotation. Changes in these motion patterns with pathologic conditions may provide useful information about the nature of shoulder dysfunction and provide insight into appropriate means of repair.

Adult↗

Fundamental movement skills--how do primary school children perform? The 'Move it Groove it' program in rural Australia.

Child Fundamental Movement Skills (FMS) underpin active lifestyles yet little is known of their distribution and mastery. 'Move it Groove it' project rated proficiency of primary school children (n = 1045, 18 schools) in skills of balance, throw, catch, sprint, hop, kick, side gallop and jump. Rating categories were 'mastery', 'near mastery' or 'poor' (ie mastered all, all but one, or less of the five to six components of an FMS). Less than half of all child tests were rated at mastery (21.3%) or near mastery (25.7%) level. In grade three, 75.4% of children achieved mastery or near mastery (MNM) in static balance but less than half did so for any other FMS. In grade four, 59.0% achieved MNM in the side gallop and 56.0% in the catch but less than half did so for any other FMS. Although the highest percent mastery for both genders was for the balance, the skills best performed thereafter by boys (throw and kick) rated poorest for girls. Conversely the hop and side gallop which rated, after balance, as the skills best mastered by girls, were among the more poorly performed skills for boys. The low prevalence of FMS mastery found in this survey suggests that there may be great potential to improve fundamental movement skills of primary aged children in many parts of rural Australia. Even if the aim were for children to achieve near mastery levels, the improvement could be substantial in every skill category. Where appropriate, gender differences in mastery might easily be addressed by tailored physical education programs and modification of social and physical environments.

Child↗

Calibration of human locomotion and models of perceptual-motor organization.

People coordinate the force and direction of skilled actions with target locations and adjust the calibrations to compensate for changing circumstances. Are the adjustments globally organized (adjusting a particular action to fit a particular circumstance would generalize to all actions in the same circumstance); anatomically specific (every effector is adjusted independently of others); of functional (adjustments would generalize to all actions serving the same goal and generating the same perceptible consequences)? Across 10 experiments, changes in the calibration of walking, throwing, and turning-in-place were induced, and generalization of changes in calibration to functionally related and unrelated actions were tested. The experiments demonstrate that humans rapidly adjust the calibration of their walking, turning, and throwing to changing circumstances, and a functional model of perceptual-motor organization is suggested.

Adult↗

Role of feedback in the development and maintenance of complex skill.

Three experiments examined the role of various sources of feedback in the development and maintenance of a complex ballistic skill, dart throwing, using extended practice. Even a brief delay of visual feedback initially affected accuracy and consistency adversely, though with practice performance gradually recovered. A total absence of visual feedback impelled subjects to use subtle cues such as crude auditory localization. When these cues were available, accuracy suffered to the same extent as with delayed visual feedback, but consistency in this case was unaffected. When all external feedback was removed, with subjects throwing in the dark at a luminous dot without hearing the dart land, consistency remained unimpaired, but accuracy suffered. However, on returning to full visual feedback both accuracy and consistency were found to have improved when compared to a control group. The independence of accuracy and consistency is discussed in terms of fixed and variable parameters of the skill. The effect of delayed visual feedback is attributed to the failure to integrate visual information with the fading proprioceptive trace. Central importance is attached to improvement in compentence when no external feedback is available, and possible underlying mechanisms for this improvement are described.

Auditory Perception↗

Familiarity and the rarity of deception: two theories and their relevance to play between dogs (Canis familiaris) and humans (Homo sapiens).

One theory of the relation between familiarity and the frequency of deception predicts that familiarity leads to the rarity of deception and another, that familiarity increases deception. We examined which theory applied to play by comparing familiar and unfamiliar partners during play between dogs (Canis familiaris) and humans (Homo sapiens). Deceptions by humans were based on directionality of movement and petting the dog and on the projects show object and throw object, which are specialized for play. Likewise, deceptions by dogs were based on directionality of movement and the project retrieve object (an analogue to show object). Deceptions based on directionality and petting were rare among familiars (and unfamiliars), whereas those based on show object, throw object, and retrieve object were more frequent. The findings suggest that, in play at least, deception may occur frequently.

Adolescent↗

Facilitating word combination in language-impaired children through discourse structure.

The influence of an adult-child discourse structure on the production of early word combinations was examined in language-impaired children. The subjects were 10 children (2:8-3:4) at the single-word utterance level. Eight of the children were engaged in 10 experimental sessions utilizing vertical structures (e.g., Adult: "Who's this?" Child: "Daddy." Adult: "What's Daddy throwing?" Child: "Ball." Adult: "Yeah, Daddy's throwing the ball."), while the remaining children, serving as controls, were engaged in an alternate activity. Examination of pretest and posttest data as well as session data revealed a substantial increase in the number of multiword productions for most of the children in the experimental group but not for the children serving as controls. These findings indicate that vertical structures have a facilitating effect on the multiword productions of language-impaired children comparable to that found in an identical procedure with normally developing children. The use of a naturally occurring adult-child discourse structure as an intervention procedure is discussed.

Child Language↗

The effect of knotting method on the structural properties of large diameter nonabsorbable monofilament sutures.

OBJECTIVE: To evaluate the effect of knotting method on the mechanical properties of large diameter nonabsorbable monofilament suture materials. STUDY DESIGN: In vitro mechanical evaluation. METHODS: A conventional square knot was compared with the surgeon's knot, sliding half-hitch, and clamped square knot. Knotted suture loops were created in a uniform manner and acutely tensioned to failure (20 mm/min loading rate; n = 20 per knot type for each material). Stiffness, yield, and failure characteristics of USP #2 nylon, #2 polybutester, #2 polypropylene, 27 kg test monofilament nylon fishing line, and 27 kg nylon leader material were evaluated. RESULTS: Compared with a conventional square knot, a surgeon's knot decreased stiffness for #2 polypropylene, 27 kg fishing line, and 27 kg leader (P < .05). A sliding half-hitch weakened all materials except 27 kg leader (P < .05). Clamping the first throw of a square knot increased the stiffness of 27 kg leader loops (P < .05). CONCLUSIONS: Based on clinically relevant parameters (stiffness and yield), knotting method had no effect on #2 nylon and #2 polybutester. The surgeon's knot is not recommended for #2 polypropylene and 27 kg fishing line and leader material. A sliding half-hitch decreased the yield of leader material. Clamping the first throw of a square knot had no adverse effects on acute properties of tested materials; it increased the stiffness for leader material. CLINICAL RELEVANCE: Knotting method does influence the structural properties of suture materials and should be considered when tying knots under tension.

Animal Population Groups↗

Neurologic injuries in baseball players.

In baseball pitchers, injuries to the throwing arm are common due to the extreme stresses placed on the elbow and shoulder joints. These result in peripheral nerve syndromes including ulnar neuropathy at the elbow and suprascapular neuropathy at the shoulder. Recurrent trauma to the axillary artery causing aneurysm and thrombus formation may lead to distal ischemia and stroke. Careful evaluation is required to identify musculoskeletal, neurologic, and vascular causes of upper extremity symptoms in the throwing athlete.

Adult↗

[Prospective proprioceptive and coordinative training for injury reduction in elite female soccer].

PURPOSE: Does a prospective proprioceptive-coordinative additional training intervention in elite female soccer changes frequency and pattern of injuries? MATERIALS AND METHODS: 24 female soccer players of the German first division team of FC Bayern München were thoroughly supervised during the season 2003/04 regarding injuries resulting in an absence from at least one scheduled training session or game. During the winter break an additional proprioceptive-coordinative training program was initiated, which was performed on a regular basis during the second half of the season. Furthermore, we evaluated jump&reach, throwing power, coordinative skills, and flexibility. RESULTS: All evaluated fitness results increased significantly during the season after the training intervention, such as jump&reach 44 +/- 4 cm vs. 38 +/- 10 cm (p < 0.05), coordinative power left and right leg, respectively (71 +/- 44 s vs. 45 +/- 37 s, 80 +/- 41 s vs. 50 +/- 32 s, both p < 0.05), flexibility left and right hip (89 +/- 8 degrees vs. 78 +/- 13 degrees and 88 +/- 9 degrees vs. 79 +/- 10 degrees, p < 0.05). Comparing the 1st to the 2nd half of the season, 25 vs. 26 injuries after foulplay and 69 vs. 52 without contact occur (p < 0.05). Muscle injuries resulting in game or training absence were significantly reduced by 400% (12 vs. 3, p < 0.05). In the 1st half of the season, 2 anterior cruciate ruptures (ACL) occur vs. none in the 2nd half after the training intervention. CONCLUSION: An additional proprioceptive-coordinative training intervention increases coordinative abilities, jump power, throwing power, and flexibility during a half season. After initiation of the proprioceptive-coordinative training the incidence of muscle injuries resulting in an absence of at least one game or practice session was reduced significantly by 400 %. Regarding the reduced incidence of ACL injuries after proprioceptive-coordinative training in female elite soccer players, further studies have to be performed to elucidate the value of this training intervention.

Adult↗

[Instability and impingement of the shoulder of the high performance athlete in overhead stress].

The present prospective study was performed on 89 competitive sportsmen (league players of handball, basketball, volleyball and water polo). The evaluation was based on information obtained from a review of training methods, a standardised anamnestic, physical and sonographic examination directed at pain, function, flexibility and all signs of impingement and instability of the shoulder counted in a score. The incidence of shoulder pain, which handicapped during training and play within the last 6 months was for water polo 60%, handball 40%, volleyball 25% and basketball 3.5%. Analysing these problems we found severe problems predominantly in handball, fewer in water polo or volleyball. According to data obtained from sports with throwing activity we found a high incidence of shoulder disorders. Using basketball players as a control group with less throwing activity our results would suggest that this mechanism seems to be the most important. The high incidence of severe disorders in handball players is additionally caused by traumatic injuries. Ultrasonography shows predominantly incomplete tears of the deep surface of the supraspinatus tendon near to the insertion with exception of the basketball players. Only in 5 shoulders (2.8%) we found the coincidence of clear signs of instability and subacromial pathology. The term "instability impingement" has not proved to be very helpful and has turned out to be far too diffuse to establish a diagnosis.

Acromioclavicular Joint↗

Stress fractures of the olecranon in javelin throwers.

Between the years 1977 and 1984, four javelin throwers with a stress fracture of the olecranon were seen and treated. In one patient, acute painful dislocation of the fracture occurred during a competitive throw. Two patients had stress fracture of the tip. The fracture treated conservatively healed in 18 months. The patient treated by excision of the tip was able to throw after 2 months. Two patients had slightly oblique, more distally located stress fractures, which were treated with a tension band and 2 Kirschner wires. The fractures healed in 4 months. One of the patients had a refracture 11 months after the primary operation. It was successfully treated with a compression screw and two bone pegs. Because of the high risk of delayed union and nonunion, stress fractures of the olecranon should be treated operatively in javelin throwers.

Adult↗

Lipoprotein and lipid profiles of elite athletes in Olympic sports.

The aim of this work was to obtain an insight into the influence exerted upon plasma lipid parameters by high quality physical training in different specialties of nine Olympic sports. We compared the concentrations of serum cholesterol (TC), total lipids (TL), triglycerides (TG), HDL, LDL, VLDL, and % distribution of HDL, LDL, and VLDL of elite athletes (n = 127, age = 22.0 +/- 3.2 yrs) participating in regular training for over 3 years (2-4 h/day), separated into 11 groups of athletic specialties, with those obtained from a group of selected sedentary controls (n = 26, age = 25.3 +/- 4.5 yrs). We also compared the lipoprotein ratio factor (RF) values TC/HDL and LDL/HDL. The athletic disciplines examined were football, basketball, volleyball, boxing, wrestling, judo, sailing, skiing (slalom), track (two groups), and throwing-jumping. Football, volleyball, judo, SD and LD running, and the total sum of athletes had significantly higher HDL than the controls. Football, basketball, volleyball and all the disciplines taken together showed significantly lower LDL. Boxing, judo, and LD running had significantly lower VLDL and volleyball, SD, and LD running significantly lower %VLDL. Volleyball had significantly lower TL, boxing and volleyball lower TC, while judo, boxing, SD and LD running had lower TG. Sailing had significantly lower %HDL and higher %LDL and TL than the controls; wrestling, skiing, and throwing-jumping did not differ. In all the athletes taken together, VO2 max or relative body weight, with respect to HDL and TC/HDL, were found to be slightly correlated (r = 0.30, P less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

A modification of the relocation test: arthroscopic findings associated with a positive test.

Thirteen overhand-throwing athletes who failed at least 3 months of physical therapy while restricted from throwing and who demonstrated a positive modified relocation test at 90 degrees, 110 degrees, and/or 120 degrees were clinically and arthroscopically examined. On arthroscopic examination, all patients demonstrated articular surface pathology. Eleven patients had fraying of the undersurface of the rotator cuff, and 10 patients had fraying of the posterosuperior labrum. With 90 degrees shoulder abduction, 8 patients had rotator cuff contact with the posterosuperior labrum. When the shoulder was abducted to 110 degrees, all patients demonstrated such contact. At 120 degrees of abduction, 12 patients revealed contact. The presence or absence of pain during the modified relocation test correlated with the presence or absence of cuff contact with the posterosuperior labrum 79% of the time. Six patients had a positive modified relocation test at all levels of abduction. These patients included 2 with SLAP lesions, 1 with a Bankart lesion, and 1 with a complete tear of the rotator cuff.

Adult↗

The physical and physiological workload of refuse collectors.

In order to secure a safer and healthy work situation, the heavy physical loads imposed on 23 refuse collectors (aged 26-54) working in the city of Haarlem, in The Netherlands, were studied in a series of three experiments between 1984 and 1987. The aims were respectively (1) to study the load for workers collecting dustbins or polythene bags; (2) to introduce changes to reduce the load to avoid exceeding the overload criteria by individual refuse collectors; and (3) to investigate the effects of interventions to improve the efficiency of refuse collecting. The maximal isometric lifting force (Fmax) and the maximal aerobic power (VO2max) of 23 refuse collectors were measured in the laboratory. Fmax was measured with an isometric dynamometer pulling with one arm from the floor; the mean value was 912 (+/- 127)N. VO2max was measured running on a treadmill; the mean value was 43.3 (+/- 0.8)ml O2 per kg body mass per min. The physical load on the oxygen transport system was measured through work analysis and by a continuous registration of the heart rate over three working days. Criteria for overload were set at a mean external load of 20% Fmax and a mean energy expenditure of 30% VO2max and an energy expenditure of 50% VO2max or more for a maximum of 60 min per day. Replacement of dustbins by polythene bags resulted in a 70% increase in the total amount of refuse collected, an increase in throwing frequency, but a lower mean load per throw, and no significant differences in the mean heart rate over the working day. When polythene bags were used the mean values did not exceed the overload criteria, but 39% of the individual collectors did have a workload that was too high with respect to one of the criteria. In the last experiment the collectors were advised to reduce their work load by (a) lifting no more than two bags at a time; (b) reducing their walking pace; and (c) taking more breaks. Although compliance with the recommendations was good, and the weight lifted and the walking speed decreased, the physiological load remained the same. This may have been caused by a 15% increase in the total amount of refuse that had to be collected at that time.

Adult↗