Does the implant make the difference ? - Prospective comparison of two different proximal femur nails.

The aim of this study was to compare two proximal femur nails with regard to the complication rate and midterm clinical outcome : the InterTAN nail (ITN) versus the third generation gamma nail (GN). 78 patients older than 60 years with an unstable intertrochanteric femoral fracture (AO/OTA 31 A2/A3) were randomised over a 20 month period into either ITN (n = 39) or GN (n = 39). The outcomes of interest were the perioperative implant-related complications and the functional status (Harris Hip Score) at 6 months postoperatively. In 14 of the ITN and in two of the GN procedures the surgeons rated the implant as cumbersome (p = 0.002). Functional outcome and complication rate did not differ between both groups. The mechanical failure correlated with the positioning of the lag screw independent on the used implant. The surgeon's technique (closed reduction, positioning of lag screw) and not implant configuration, is of crucial importance in achieving successful outcome.

[Biomechanical investigation on refixation of tuberosities on shoulder prostheses. Does refixation with different suture materials offer enough stability?]. / Biomechanische Untersuchung zur Refixation der Tuberkula an Frakturschulterendoprothesen. Bietet die Rekonstruktion der Tuberkula mittels unterschiedlicher Nahtmaterialien eine ausreichende Stabilität?

BACKGROUND: Elderly patients suffering from complex, non-reconstructable fractures of the proximal humerus are commonly treated by primary implantation of a shoulder endoprosthesis. One of the most critical factors for success or failure of treatment is still the refixation of the tuberosities. METHOD: Using sheep infraspinatus tendons with attached tuberosities three different suture materials were investigated. For 2 of the suture materials 4 tests were accomplished and 5 tests were carried out for the third suture material. A material testing machine was used to perform cyclic loading tests (20 mm/min, Fmin=50 N, Fmax=100 N, respectively after 50 cycles: Fmax+50 N until failure). RESULTS: The results showed large variations in the average maximum forces (152.4 N for suture 1, 219.9 N for suture 2 and 452.3 N for suture 3). All tests showed a high initial lengthening and caused incision-like defects in the bone or tendon and led to failure and high displacement of the tuberosities. CONCLUSION: Due to these results suture materials have a limited usefulness for refixation of tuberosities as an increased risk of obstruction for bony consolidation can result.

Insulin-mediated cortical activity in the slow frequency range is diminished in obese mice and promotes physical inactivity.

AIMS/HYPOTHESIS: There is evidence from mouse models and humans that alterations in insulin action in the brain are accompanied by an obese phenotype; however, the impact of insulin with regard to behavioural aspects such as locomotion is unknown. METHODS: To address insulin action in the brain with regard to cortical activity in distinct frequency bands and the behavioural consequences, the insulin signalling pathway was followed from the receptor to electrical activity and locomotion. Western blot analysis, electrocorticograms with intracerebroventricular (i.c.v.) application of insulin, and measurements of locomotor activity were performed in lean and obese, as well as Toll-like receptor (TLR) 2/4-deficient, mice. RESULTS: We show that insulin application i.c.v. into lean mice was accompanied by a profound increase in cortical activity in the slow frequency range, while diet-induced obese mice displayed insulin resistance. In parallel, insulin administered i.c.v. increased locomotor activity in lean mice, whereas a phosphatidylinositol-3 (PI3) kinase inhibitor or obesity abolished insulin-mediated locomotion. A potential candidate that links insulin signalling to locomotion is the Kv1.3 channel that is activated by PI3-kinase. Pharmacological inhibition of Kv1.3 channels that bypassed insulin receptor activation promoted activity. Moreover, mice deficient in TLR2/4-dependent signalling displayed an increase in cortical activity in the slow frequency range that was correlated with improved spontaneous and insulin-mediated locomotor activity. CONCLUSIONS/INTERPRETATION: Our data provide functional evidence for a direct effect of insulin on brain activation patterns in the slow frequency bands and locomotor activity in lean mice, while in obese mice, insulin-mediated locomotion is blunted and further aggravates physical inactivity.

[Ski sport. Trend--pattern of injuries--prevention]. / Skisport. Aktuelle Entwicklung--Verletzungsmuster--Prävention.

Skiing is one of the most favoured winter sports, supported by the introduction of carving skis ten years ago. There's a close correlation between the design of the carving ski and a new skiing technique. Only a small number of persons is able to carve correctly. A special fitness program is necessary to be prepared adequately to the skills of carving. As proven by the latest injury statistics, the number of injuries has been declining over the last years. Due to the new skiing technique, injury patterns have changed. The most frequently affected injured region is still the knee joint. Prevention can be done by fitness training, watching instructional ski videos, and usage of well-fitting sports equipment. A new trend is the Telemark-technique, which shows different injury patterns than carving.

Biomechanical strength and failure mechanism of different tubercula refixation methods within the framework of an arthroplasty for shoulder fracture.

BACKGROUND: Tuberosity repair in shoulder fracture prosthesis implantation still remains a challenge often leading to poor functional outcomes, despite a variety of materials and suggested suture patterns. We aimed to evaluate, which forces currently used suture and cerclage materials withstand and to assess whether they are useful with regard to stability of reconstruction of tuberosities and which failure modes they display. MATERIAL AND METHODS: Using sheep infraspinatus tendons with attached tuberosities three different suture materials (suture 1: Ethibond size 2; suture 2: Orthocord size 2; suture 3: Fiberwire size 5) and a 0.8mm titanium cerclage wire were investigated. For each suture material as well as the cerclage wire 6 tests were carried out. A material testing machine was used to perform cyclic loading tests (20mm/min, Fmin=50N, Fmax=100N, respectively after 50 cycles: Fmax+50N until failure). Outcome measures and thus comparison criteria were the maximum holding force, number of cycles reached, total elongation of the system (tendon and suture) and qualitative appraisal and documentation of the mechanism of failure. RESULTS: Overall average maximum forces between the fixation materials differed significantly (P=0.003), especially suture 3 (braided polyethylene coating, non-resorbable polyfile UHMW core) displayed superior results in comparison to the cerclage wire (P=0.016). Although, primary elongation of the cerclage technique was significantly lower compared to the suture materials (P=0.002). All tests showed a high initial lengthening and caused incision-like defects in the bone or tendon and led to failure and huge displacement of the tuberosities. DISCUSSION: Currently used suture and cerclage materials have a limited usefulness for refixation of tuberosities due to an increased risk of obstruction for bony consolidation. LEVEL OF EVIDENCE: Basic science, Biomechanics.

[Injury of the Obturator Internus Muscle--a Rare Differential Diagnosis in a Soccer Player]. / Verletzung des M. obturatorius internus--eine seltene Differenzialdiagnose beim Fußballspieler.

BACKGROUND: Lesions/irritations of the obturator internus muscle (OIM) are rare, several differential diagnoses are possible. PATIENT: This paper describes the case of an OIM injury in a professional football player. RESULTS: On clinical examination, painful internal rotation of the hip joint was an indication for a lesion/irritation of the OIM. MRI was the procedure of choice for imaging. Movement analysis served to detect a functional malposition. CONCLUSION: A short recovery time requires functional treatment as well as the use of orthopaedic aids to correct possible deformities.

A study of the mechanical strength of long bone defects treated with various bone autograft substitutes: an experimental investigation in the rabbit.

This study was designed to determine which of several bone grafting materials would be the most efficacious substitute for autogenous bone graft in the treatment of segmental long bone defects. The experimental model was a 1-cm defect in the rabbit ulna. The control group had nothing implanted in the defect. The six grafts tested were: (a) autogenous iliac crest bone, (b) autogenous cortical bone (ulna), (c) hydroxylapatite, (d) hydroxylapatite-demineralized bone matrix (allograft) composite graft, (e) freeze-dried bone (allograft), and (f) demineralized bone matrix (allograft). At 6 weeks postoperatively, the ulnas were harvested, examined radiographically, and tested mechanically in torsion. The radiographic examination proved to be of little value because some materials were radiodense at the time of implantation. The rates (percentage) of union, torques at failure, and energy to failure values were statistically significantly higher than control for all groups except hydroxylapatite. We concluded that demineralized bone matrix and hydroxylapatite-demineralized bone matrix composite graft compare favorably with cortical replacement (autograft) in mechanical strength and rate of union and therefore may be satisfactory substitutes for bone grafting. Freeze-dried bone did not appear to be as satisfactory because of its low mean energy to failure, but statistical analysis failed to confirm this opinion. Hydroxylapatite graft, when used alone, does not appear to be a suitable material for grafting segmental bone defects.

Olfactory discrimination of individual littermates in rats (Rattus norvegicus).

Adult male rats (Rattus norvegicus) were trained in a Y-maze to discriminate the presence of a littermate from its absence. Transfer of training in subsequent tests indicated that (a) the animals were capable of distinguishing among individuals when relatedness and familiarity were held constant, (b) this ability was not due to training, and (c) their performance was based solely on odor cues. The results are discussed in relation to social behavior in rats.

Differential sensitivity of Japanese macaques (Macaca fuscata) and humans (Homo sapiens) to peak position along a synthetic coo call continuum.

Difference limens (DLs) for changes in the temporal position of a pitch peak along a synthetic early-high to late-high coo continuum were measured in 2 Japanese macaques (Macaca fuscata) and 2 humans (Homo sapiens) in a low-uncertainty, repeating standard discrimination procedure. Lowest DLs (19-32 ms for monkeys; less than 10 ms for humans) occurred near the endpoints of the continuum. Highest DLs (59-73 ms for monkeys; 25-27 ms for humans) occurred near the center of the continuum. DLs for both monkeys and humans corresponded to previously reported measures of temporal resolution. Neither monkeys nor humans exhibited categorical perception of the coo continuum, with a central area of enhanced sensitivity, a result previously reported by May, Moody, and Stebbins (1989) for similar stimuli. We conclude that our subjects discriminated variation in coo peak position by using general psychoacoustic mechanisms related to temporal discrimination.

Absolute auditory thresholds in three Old World monkey species (Cercopithecus aethiops, C. neglectus, Macaca fuscata) and humans (Homo sapiens).

We investigated the absolute auditory sensitivities of three monkey species (Cercopithecus aethiops, C. neglectus, and Macaca fuscata) and humans (Homo sapiens). Results indicated that species-typical variation exists in these primates. Vervets, which have the smallest interaural distance of the species that we tested, exhibited the greatest high-frequency sensitivity. This result is consistent with Masterton, Heffner, and Ravizza's (1969) observations that head size and high-frequency acuity are inversely correlated in mammals. Vervets were also the most sensitive in the middle frequency range. Furthermore, we found that de Brazza's monkeys, though they produce a specialized, low-pitched boom call, did not show the enhanced low-frequency sensitivity that Brown and Waser (1984) showed for blue monkeys (C. mitis), a species with a similar sound. This discrepancy may be related to differences in the acoustics of the respective habitats of these animals or in the way their boom calls are used. The acuity of Japanese monkeys was found to closely resemble that of rhesus macaques (M. mulatta) that were tested in previous studies. Finally, humans tested in the same apparatus exhibited normative sensitivities. These subjects responded more readily to low frequencies than did the monkeys but rapidly became less sensitive in the high ranges.

Cervical traction. A comparison of sitting and supine positions.

Eight students were studied todetermine the position which provided the greatest amount of posterior intervertebral separation during a cervical traction treatment. A standard angle of 45 degrees with traction apparatus set at zero, 14 Kg (30 pounds), and 18 Kg (40 pounds) were used in both sitting and supine positions. Measurements of posterior intervertebral separation taken from lateral roentgenograms of the C4-C7 vertebrae revealed greater separation in the supine positions. The results suggested that the supine position was more beneficial in treatment of the cervical spine with traction. The investigators concluded that the increased separation in the supine position was related to the patient's increased comfort and relaxation.

[Acute and overuse injuries in soccer - what about the evidence level?]. / Verletzungen und Schäden im Fußball - Wie hoch ist die Evidenz?

AIM: Over the last years, several studies on harmful events (h. e.) in soccer have been published. The aim was to develop a ranking of these studies according to their evidence, and to analyse the data with respect to the number of study participants, athletes' status, gender distribution, and genesis of harmful events in soccer. METHODS: Between 1976 and 2011, the data bases MEDLINE, EBMR, and SPOTLIT were scanned by the keywords/combinations: soccer, acute injuries, overuse injuries, training, and match. In doing so, 644 initially potential relevant articles were found. On the basis of the QUORUM standard, 78 potentially relevant articles were filtered out, and an EVIDENCE BASED LEVEL (EBL) was assigned. The results were rated according to importance and shown descriptively, because the heterogeneity of the study inhibited meta-analytical evaluation. RESULTS: 23 % of the publications could be assigned to EBL 2a - 2c, 27 % to EBL 3a and 3b, and 50 % to EBL 4 and 5. The studies comprised altogether 22 294 male and 2375 female athletes; 87 % of the male and 29 % of the female were professional athletes. 7 usable publications with a total of 8011 h. e. in men and 6 publications with 1055 h. e. in women dealt with contact/non-contact genesis of h. e.. 46 % male (72 % female) athletes suffered from h. e. caused by contact events, and 54 % male (28 % female) athletes suffered from h. e. caused by non-contact events. The distribution of acute and overuse injuries was analysed in 9969 h. e. in men (11 publications), and in 624 h. e. in women (5 publications). On average, the number of acute injuries (90 % male, 86 % female) was much higher than that of overuse injuries. The prevalence of h. e. with respect to training or match playing was analysed in 11 studies with 10 078 h. e. in men, and in 4 studies with 546 harmful events in women. 35 % of men's h. e. occurred during training and 65 % during matches, whereas 60 % of the women's h. e. occurred during training and 40 % during matches. CONCLUSION: The number of athletes included in the studies is quite low in relation to the number of active athletes. Studies of professional athletes are over-represented. Independent of gender, there are more acute injuries than overuse injuries, whereas the distribution of harmful events with respect to genesis and occurrence during training and match is gender-specific. The studies' evidence level is quite low in relation to the socio-economic significance of this kind of sport; the studies' evidence is higher for women.

Differential rescue of spatial memory deficits in aged rats by L-type voltage-dependent calcium channel and ryanodine receptor antagonism.

Age-associated memory impairments may result as a consequence of neuroinflammatory induction of intracellular calcium (Ca(+2)) dysregulation. Altered L-type voltage-dependent calcium channel (L-VDCC) and ryanodine receptor (RyR) activity may underlie age-associated learning and memory impairments. Various neuroinflammatory markers are associated with increased activity of both L-VDCCs and RyRs, and increased neuroinflammation is associated with normal aging. In vitro, pharmacological blockade of L-VDCCs and RyRs has been shown to be anti-inflammatory. Here, we examined whether pharmacological blockade of L-VDCCs or RyRs with the drugs nimodipine and dantrolene, respectively, could improve spatial memory and reduce age-associated increases in microglia activation. Dantrolene and nimodipine differentially attenuated age-associated spatial memory deficits but were not anti-inflammatory in vivo. Furthermore, RyR gene expression was inversely correlated with spatial memory, highlighting the central role of Ca(+2) dysregulation in age-associated memory deficits.

Odor cue determinants of urine marking in male rats (Rattus norvegicus).

This study examined the spatial distribution of urine marking by sexually inexperienced male rats under six odor conditions: minimum odor (baseline), conspecific male urine, conspecific female urine, an animal's own urine, male gerbil urine, and amyl acetate. The gerbil urine and amyl acetate conditions were included to test the theory that marking, rather than being elicited by and directed as a display to appropriate conspecifics, occurred to the introduction of any novel or disruptive odor. The subject's own urine was used to test the theory that the animal marked to maintain an optimum level of its own odor in the environment. The results showed that marking was directed predominantly at objects in the environment over which the animal could readily pass. All odor conditions except "own odor" sharply increased marking over baseline levels. Marking decreased with repeated exposure to particular stimuli. The results strongly supported the theory that urine marking, at least in sexually inexperienced male rats, is produced by novel odor stimuli introduced into a familiar environment.

Frequency and intensity discrimination in humans and monkeys.

Frequency and intensity DLs were compared in humans and monkeys using a repeating standard "yes-no" procedure in which subjects reported frequency increments, frequency decrements, intensity increments, or intensity decrements in an ongoing train of 1.0-kHz tone bursts. There was only one experimental condition (intensity increments) in which monkey DLs (1.5-2.0 dB) overlapped those of humans (1.0-1.8 dB). For discrimination of both increments and decrements in frequency, monkey DLs (16-33 Hz) were approximately seven times larger than those of humans (2.4-4.8 Hz), and for discrimination of intensity decrements, monkey DLs (4.4-7.0 dB) were very unstable and larger than those of humans (1.0-1.8 dB). For intensity increment discrimination, humans and monkeys also exhibited similar DLs as SL was varied. However, for frequency increment discrimination, best DLs for humans occurred at a high (50 dB) SL, whereas best DLs for monkeys occurred at a moderate (30 dB) SL. Results are discussed in terms of various neural mechanisms that might be differentially engaged by humans and monkeys in performing these tasks; for example, different amounts of temporal versus rate coding in frequency discrimination, and different mechanisms for monitoring rate decreases in intensity discrimination. The implications of these data for using monkeys as models of human speech sound discrimination are also discussed.