Mediolateral three-point bending of the rat midfemur was developed to enable the assessment of the mechanical competence of the elliptic bone cross-section in terms of its widest diameter, the apparent primary direction of bone adaptation to loading.Introduction: Today, the most commonly used method to characterize the biomechanical properties of appendicular long bones is the three-point bending testing of the midfemur in the anteroposterior (AP) direction. However, as the diameter of the elliptic cross-section of femoral diaphysis is widest in the orthogonal mediolateral (ML) direction, the femoral diaphysis should also show the highest resistance to bending along this direction. The objective of this study was thus to introduce and validate a mechanical testing protocol for femoral midshaft along the ML direction. Materials and Methods: To determine the repeatability of the novel testing protocol, 38 pairs of rat femora underwent a comprehensive structural analysis by pQCT followed by ML three-point bending. For comparison of the repeatability, corresponding tests were performed on the femoral neck. To validate the novel testing direction, the left hindlimb of 24 rats was neurectomized for 6 months, whereas the right limb served as an intact control. After excision, one half of these pairs of femora were randomly subjected to three-point bending test in the conventional AP direction and the remaining in the orthogonal ML direction. Results: The precision (CV rms ) of breaking load, stiffness, and energy absorption of the femoral midshaft in the ML direction was 3.8%, 6.6%, and 14.5%, respectively. The corresponding values for femoral neck compression test were 7.6%, 17.9%, and 18.7%, respectively. The loading-induced effect on the femoral midshaft (difference between the neurectomized [nonloaded] and contralateral intact [loaded] femur) was +2.2%, +1.9%, and +2.1% in the AP direction and −18.9%, −17.6%, and −20.3% in the ML direction (p < 0.01 for all comparisons), respectively. Conclusions: Our results show that testing of rat femoral midshaft in the ML direction is a precise and biologically valid method to determine the structural strength of this widely used skeletal site in experimental bone research.

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BackgroundAccording to prevailing understanding, skeletal mechano-responsiveness declines with age and this apparent failure of the mechano-sensory feedback system has been attributed to the gradual bone loss with aging (age-related osteoporosis). The objective of this study was to evaluate whether the capacity of senescent skeleton to respond to increased loading is indeed reduced as compared to young mature skeleton.Methods and Findings108 male and 101 female rats were randomly assigned into Exercise and Control groups. Exercise groups were subjected to treadmill training either at peak bone mass between 47–61 weeks of age (Mature) or at senescence between 75–102 weeks of age (Senescent). After the training intervention, femoral necks and diaphysis were evaluated with peripheral quantitative computed tomography (pQCT) and mechanical testing; the proximal tibia was assessed with microcomputed tomography (μCT). The μCT analysis revealed that the senescent bone tissue was structurally deteriorated compared to the mature bone tissue, confirming the existence of age-related osteoporosis. As regards the mechano-responsiveness, the used loading resulted in only marginal increases in the bones of the mature animals, while significant exercise-induced increases were observed virtually in all bone traits among the senescent rats.ConclusionThe bones of senescent rats displayed a clear ability to respond to an exercise regimen that failed to initiate an adaptive response in mature animals. Thus, our observations suggest that the pathogenesis of age-related osteoporosis is not attributable to impaired mechano-responsiveness of aging skeleton. It also seems that strengthening of even senescent bones is possible – naturally provided that safe and efficient training methods can be developed for the oldest old.

Background Platelet-rich plasma (PRP) and autologous blood are commonly used therapies for lateral epicondylitis, but the evidence from randomized, placebo-controlled trials is conflicting. Thus, it is still unclear if patients benefit from these treatments. Questions/purposes In the setting of a randomized, placebo-controlled trial, we compared PRP, autologous blood, and saline injections in the treatment of lateral epicondylitis with respect to: (1) VAS pain scores, and (2) functional outcomes (DASH score and grip strength) 1 year after treatment. Methods We performed a parallel-group, randomized, controlled participant- and assessor-blinded study including adults with clinically diagnosed lateral epicondylitis. We defined lateral epicondylitis as pain in the lateral humeral epicondyle area exacerbated during resisted wrist extension and epicondyle compression. The participants were recruited from a secondary referral center, after not responding to initial nonoperative treatment. Patients with other concomitant upper-limb symptoms and surgical treatment of the elbow were excluded. Randomization sequence was generated with computer software and concealed from the investigators. We randomized 119 participants to receive an injection of PRP, autologous blood, or saline (1:1:1) in the proximal insertion of the extensor carpi radialis brevis muscle; 40 participants received PRP, 40 received autologous blood, and 39 received a saline injection. To prepare the PRP, we collected venous blood with a syringe kit followed by centrifugation, whereas autologous blood group received unprepared blood injection. Two unblinded investigators gave injections while the participant was unable to see the injection. There was no formal postinjection rehabilitation protocol and the use of NSAIDs was similar between different treatment arms. Follow-up visits were at 4, 8, 12, 26, and 52 weeks after the injection. The primary outcome measure was improvement in pain, measured with VAS scale (without specification as to whether the pain was activity related or at rest; range 0-10; a higher score indicates worse pain; the minimum clinically important difference [MCID] on the 10-cm scale was 1.5 cm), from baseline to 52 weeks. The secondary outcomes were the DASH score (range 0-100; a higher indicates a poorer outcome, and the MCID was 10.2 points) and grip strength. All patients were included in the analyses, and analyses were performed using the intention-to-treat principle. There was no crossover between treatment groups. At 52 weeks, nearly all (95% [38 of 40]) participants in autologous blood group were available for analysis whereas 78% (31 of 40) and 82% (32 of 39) were available in PRP and saline groups. This study was registered at ClinicalTrials.gov and funded by the local hospital district. With 40 patients in each group, we had 80% power to detect a clinically important improvement in pain (1.5 cm on the 10-cm VAS pain scale). Results There were no clinically important differences in the mean VAS pain or DASH scores among the groups at any timepoint. At 52 weeks, the mean difference in the VAS score for pain was -0.2 (95% CI -1.5 to 1.1; p = 0.75) for PRP versus saline and 0.5 (95% CI -0.7 to 1.7; p = 0.40) for autologous blood versus saline. The corresponding mean differences in the DASH score were 0.0 (95% CI -9.2 to 9.2; p > 0.99) and 7.7 (95% CI -1.3 to 16.7; p = 0.09) and those for grip strength were 1.4 kg (95% CI -3.3 to 6.1; p = 0.56) and -0.2 kg (95% CI -5.0 to 4.5; p = 0.92). No complications occurred because of the injections. Conclusions PRP or autologous blood injections did not improve pain or function at 1 year of follow-up in people with lateral epicondylitis compared with those who were given a saline injection. However, because the 95% CIs did not exclude the MCID in VAS scores for autologous blood versus saline at 52 weeks, it is possible that a larger study could identify a between-group difference that we missed, but the effect size of that difference (based on our findings), even if present, is likely still to be small. Until or unless future randomized trials convincingly show a benefit either to PRP or autologous blood injections, we recommend against their use in patients with lateral epicondylitis. Level of Evidence Level II, therapeutic study.

SummaryAlthough micro-computed tomography (micro-CT) has become the gold standard for assessing the 3D structure of trabecular bone, its extension to cortical bone microstructure has been relatively limited. Desktop micro-CT has been employed to assess cortical bone porosity of humans, whereas that of smaller animals, such as mice and rats, has thus far only been imaged using synchrotron-based micro-CT. The goal of this study was to determine if it is possible to visualize and quantify rat cortical porosity using desktop micro-CT. Tibiae (n = 10) from 30-week-old female Sprague-Dawley rats were imaged with micro-CT (3 μm nominal resolution) and sequential ground sections were then prepared. BlandAltman plots were constructed to compare per cent porosity and mean canal diameter from micro-CT (3D) versus histology (2D). The mean difference or bias (histology -micro-CT; ±95% confidence interval) for per cent porosity was found to be −0.15% (±2.57%), which was not significantly different from zero (P = 0.720). Canal diameter had a bias (±95% confidence interval) of −5.73 μm (±4.02 μm) which was found to be significantly different from zero (P < 0.001). The results indicated that cortical porosity in rat bone can indeed be visualized by desktop micro-CT. Quantitative assessment of per cent porosity provided unbiased results, whereas direct analysis of mean canal diameter was overestimated by micro-CT. Thus, although higher resolution, such as that available from synchrotron micro-CT, may ultimately be required for precise geometric measurements, desktop micro-CT -which is far more accessible -is capable of yielding comparable measures of porosity and holds great promise

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Objectives:A lesion in the spinal accessory nerve is typically iatrogenic: related to lymph node biopsy or excision. This injury may cause paralysis of the trapezius muscle and thus result in a characteristic group of symptoms and signs, including depression and winging of the scapula, drooped shoulder, reduced shoulder abduction, and pain. The elements evaluated in this long-term follow-up study include range of shoulder motion, pain, patients’ satisfaction, delay of surgery, surgical procedure, occupational status, functional outcome, and other clinical findings.Methods:We reviewed the medical records of a consecutive 37 patients (11 men and 26 women) having surgery to correct spinal accessory nerve injury. Neurolysis was the procedure in 24 cases, direct nerve repair for 9 patients, and nerve grafting for 4. Time elapsed between the injury and the surgical operation ranged from 2 to 120 months. The patients were interviewed and clinically examined after an average of 10.2 years postoperatively.Results:The mean active range of movement of the shoulder improved at abduction 44° (43%) in neurolysis, 59° (71%) in direct nerve repair, and 30° (22%) in nerve-grafting patients. No or only slight atrophy of the trapezius muscle was observable in 75%, 44%, and 50%, and no or controllable pain was observable in 63%, 56%, and 50%. Restriction of shoulder abduction preceded deterioration of shoulder flexion. Patients’ overall dissatisfaction with the state of their upper extremity was associated with pain, lower strength in shoulder movements, and occupational problems.Conclusion:We recommend avoiding unnecessary delay in the exploration of the spinal accessory nerve, if a neural lesion is suspected.

This study compared the biomechanical behaviour of repairs in the human flexor digitorum profundus tendon in zones I, II and III with repairs of different segments of the porcine flexor tendon of the second digit and the extensor digiti quarti proprius tendon, in order to assess the validity of porcine tendons as models for human flexor tendon repairs. These porcine tendons were selected after comparing their size with the human flexor digitorum profundus tendon. The tendon repairs were done in three segments of each porcine tendon and repairs in the human tendons were done in zones I,II and III. Ten tendons in each group yielded a total of 90 specimens. A modified Kessler repair was done with 3-0 coated braided polyester suture and subjected to uniaxial tensile testing. In human flexor tendons, the ultimate force was higher in zones I and II than in zone III. The porcine flexor digitorum profundus tendon from the second digit and the proximal segment of the extensor digiti quarti proprius tendon behaved similarly to the human flexor tendon in zone III and can be considered as surrogates for the human flexor tendon.