Architectural changes of the biceps femoris after concentric or eccentric training

Purpose To determine i) the architectural adaptations of the biceps femoris long head (BFlf) following concentric or eccentric strength training interventions; ii) the time course of adaptation during training and detraining. Methods Participants in this randomized controlled trial (control [n=28], concentric training group [n=14], eccentric training group [n=14], males) completed a 4-week control period, followed by 6 weeks of either concentric- or eccentric-only knee flexor training on an isokinetic dynamometer and finished with 28 days of detraining. Architectural characteristics of BFlf were assessed at rest and during graded isometric contractions utilizing two-dimensional ultrasonography at 28 days pre-baseline, baseline, days 14, 21 and 42 of the intervention and then again following 28 days of detraining. Results BFlf fascicle length was significantly longer in the eccentric training group (p<0.05, d range: 2.65 to 2.98) and shorter in the concentric training group (p<0.05, d range: -1.62 to -0.96) after 42 days of training compared to baseline at all isometric contraction intensities. Following the 28-day detraining period, BFlf fascicle length was significantly reduced in the eccentric training group at all contraction intensities compared to the end of the intervention (p<0.05, d range: -1.73 to -1.55). There was no significant change in fascicle length of the concentric training group following the detraining period. Conclusions These results provide evidence that short term resistance training can lead to architectural alterations in the BFlf. In addition, the eccentric training-induced lengthening of BFlf fascicle length was reversed and returned to baseline values following 28 days of detraining. The contraction mode specific adaptations in this study may have implications for injury prevention and rehabilitation.

Biceps femoris architecture and strength in athletes with a prior ACL reconstruction

Purpose To determine if limbs with a history of anterior cruciate ligament (ACL) injury reconstructed from the semitendinosus (ST) display different biceps femoris long head (BFlh) architecture and eccentric strength, assessed during the Nordic hamstring exercise, compared to the contralateral uninjured limb. Methods The architectural characteristics of the BFlh were assessed at rest and at 25% of a maximal voluntary isometric contraction (MVIC) in the control (n=52) and previous ACL injury group (n=15) using two-dimensional ultrasonography. Eccentric knee-flexor strength was assessed during the Nordic hamstring exercise. Results Fascicle length was shorter (p=0.001; d range: 0.90 to 1.31) and pennation angle (p range: 0.001 to 0.006: d range: 0.87 to 0.93) was greater in the BFlh of the ACL injured limb when compared to the contralateral uninjured limb at rest and during 25% of MVIC. Eccentric strength was significantly lower in the ACL injured limb than the contralateral uninjured limb (-13.7%; -42.9N; 95% CI = -78.7 to -7.2; p=0.021; d=0.51). Fascicle length, MVIC and eccentric strength were not different between the left and right limb in the control group. Conclusions Limbs with a history of ACL injury reconstructed from the ST have shorter fascicles and greater pennation angles in the BFlh compared to the contralateral uninjured side. Eccentric strength during the Nordic hamstring exercise of the ACL injured limb is significantly lower than the contralateral side. These findings have implications for ACL rehabilitation and hamstring injury prevention practices which should consider altered architectural characteristics.

Tendinopathy alters ultrasound transmission in the patellar tendon during squatting

Measurement of loading patterns of the patellar tendon during activity is important in understanding tendon injury. We used transmission-mode ultrasonography to investigate patellar tendon loading during squatting in adults with and without tendinopathy. It was hypothesized that axial ultrasonic velocity, a surrogate measure of the elastic modulus of tendon, would be lower in tendinopathy. Ultrasound velocity was measured in both patellar tendons of adults with unilateral patellar tendinopathy (n=9) and in healthy controls (n=16) during a bilateral squat manoeuvre. Sagittal knee movement was measured simultaneously with an electrogoniometer. Statistical comparisons between healthy and injured tendons were made using 2–way mixed–design ANOVAs. Axial ultrasound velocity in both symptomatic and asymptomatic patellar tendons in tendinopathy was approximately 15% higher than in healthy tendons at the commencement (F1,23=5.2, P<.05) and completion (F1,23=4.5, P<.05) of the squat. While peak velocity was ≈5% higher during both flexion (F1,23=5.4, P<.05) and extension (F1,23=5.3, P<.05) phases, there was no significant between–group difference at the mid–point of the movement. There were no significant differences in the rate and magnitude of knee movement between groups. Although further research is required, these findings suggest enhanced baseline muscle activity in patellar tendinopathy and highlight fresh avenues for its clinical management.

Impaired physical function associated with childhood obesity: How should we intervene?

- Background This study examined relationships between adiposity, physical functioning and physical activity. - Methods Obese (N=107) and healthy-weight (N=132) children aged 10-13 years underwent assessments of percent body fat (%BF, dual energy X-ray absorptiometry), knee extensor strength (KE, isokinetic dynamometry), cardiorespiratory fitness (CRF, peak oxygen uptake by cycle ergometry), physical health-related quality of life (HRQOL), worst pain intensity and walking capacity [six-minute walk (6MWT)]. Structural equation modelling was used to assess relationships between variables. - Results Moderate relationships were observed between %BF and 6MWT, KE strength corrected for mass and CRF relative to mass (r -.36 to -.69, P≤.007). Weak relationships were found between: %BF and physical HRQOL (r -.27, P=.008); CRF relative to mass and physical HRQOL (r -.24, P=.003); physical activity and 6MWT (r .17, P=.004). Squared multiple correlations showed that 29.6% variance in physical HRQOL was explained by %BF, pain and CRF relative to mass, while 28% variance in 6MWT was explained by %BF and physical activity. - Conclusions It appears that children with a higher body fat percentage have poorer KE strength, CRF and overall physical functioning. Reducing percent fat appears to be the best target to improve functioning. However, a combined approach to intervention, targeting reductions in body fat percentage, pain and improvements in physical activity and CRF may assist physical functioning.

Morphology-based interslice interpolation on manual segmentations of joint bones and muscles in MRI

This paper presents a validation study on the application of a novel interslice interpolation technique for musculoskeletal structure segmentation of articulated joints and muscles on human magnetic resonance imaging data. The interpolation technique is based on morphological shape-based interpolation combined with intensity based voxel classification. Shape-based interpolation in the absence of the original intensity image has been investigated intensively. However, in some applications of medical image analysis, the intensity image of the slice to be interpolated is available. For example, when manual segmentation is conducted on selected slices, the segmentation on those unselected slices can be obtained by interpolation. We proposed a two- step interpolation method to utilize both the shape information in the manual segmentation and local intensity information in the image. The method was tested on segmentations of knee, hip and shoulder joint bones and hamstring muscles. The results were compared with two existing interpolation methods. Based on the calculated Dice similarity coefficient and normalized error rate, the proposed method outperformed the other two methods.

Hip power analysis in individuals with transfemoral amputation: A different strategy different from stabilisation during gait stance

Introduction and Objectives Joint moments and joint powers during gait are widely used to determine the effects of rehabilitation programs as well as prosthetic fitting. Following the definition of power (dot product of joint moment and joint angular velocity) it has been previously proposed to analyse the 3D angle between both vectors, αMw. Basically, joint power is maximised when both vectors are parallel and cancelled when both vectors are orthogonal. In other words, αMw < 60° reveals a propulsion configuration (more than 50% of the moment contribute to positive power) while αMw > 120° reveals a resistance configuration (more than 50% of the moment contribute to negative power). A stabilisation configuration (less than 50% of the moment contribute to power) corresponds to 60° < αMw < 120°. Previous studies demonstrated that hip joints of able-bodied adults (AB) are mainly in a stabilisation configuration (αMw about 90°) during the stance phase of gait. [1, 2] Individuals with transfemoral amputation (TFA) need to maximise joint power at the hip while controlling the prosthetic knee during stance. Therefore, we tested the hypothesis that TFAs should adopt a strategy that is different from a continuous stabilisation. The objective of this study was to compute joint power and αMw for TFA and to compare them with AB. Methods Three trials of walking at self-selected speed were analysed for 8 TFAs (7 males and 1 female, 46±10 years old, 1.78±0.08 m 82±13 kg) and 8 ABs (males, 25±3 years old, 1.75±0.04, m 67±6 kg). The joint moments are computed from a motion analysis system (Qualisys, Goteborg, Sweden) and a multi-axial transducer (JR3, Woodland, USA) mounted above the prosthetic knee for TFAs and from a motion analysis system (Motion Analysis, Santa Rosa, USA) and force plates (Bertec, Columbus, USA) for ABs. The TFAs were fitted with an OPRA (Integrum, AB, Gothengurg, Sweden) osseointegrated implant system and their prosthetic designs include pneumatic, hydraulic and microprocessor knees. Previous studies showed that the inverse dynamics computed from the multi-axial transducer is the proper method considering the absorption at the foot and resistance at the knee. Results The peak of positive power at loading response (H1) was earlier and lower for TFA compared to AB. Although the joint power is lower, the 3D angle between joint moment and joint angular velocity, αMw, reveals an obvious propulsion configuration (mean αMw about 20°) for TFA compared to a stabilisation configuration (mean αMw about 70°) for AB. The peaks of negative power at midstance (H2) and of positive power at preswing / initial swing (H3) occurred later, lower and longer for TFA compared to AB. Again, the joint powers are lower for TFA but, in this case, αMw is almost comparable (with a time lag), demonstrating a stabilisation (almost a resistance for TFA, mean αMw about 120°) and a propulsion configuration, respectively. The swing phase is not analysed in the present study. Conclusion The analysis of hip joint power may indicate that TFAs demonstrated less propulsion and resistance than ABs during the stance phase of gait. This is true from a quantitative point of view. On the contrary, the 3D angle between joint moment and joint angular velocity, αMw, reveals that TFAs have a remarkable propulsion strategy at loading response and almost a resistance strategy at midstance while ABs adopted a stabilisation strategy. The propulsion configuration, with αMw close to 0°, seems to aim at maximising the positive joint power. The configuration close to resistance, with αMw far from 180°, might aim at unlocking the prosthetic knee before swing while minimising the negative power. This analysis of both joint power and 3D angle between the joint moment and the joint angular velocity provides complementary insights into the gait strategies of TFA that can be used to support evidence-based rehabilitation and fitting of prosthetic components.

Dislocation after total hip replacement: there is no such thing as a safe zone for socket placement with the posterior approach

Introduction Malorientation of the socket contributes to instability after hip arthroplasty but the optimal orientation of the cup in relation to the pelvis has not been unequivocally described. Large radiological studies are few and problems occur with film standardisation, measurement methodology used and alternative definitions of describing acetabular orientation. Methods A cohort of 1,578 patients from a single institution is studied where all patient data was collected prospectively. Risk factors for patients undergoing surgery are analysed. Radiological data was compared between a series of non-dislocating hips and dislocating cases matched 2:1 by operation type, age and diagnosis. Results The overall dislocation rate for all 1,578 cases was 3.23% but the rate varied according to the type of surgery performed. The rate in uncomplicated primary cases was 2.4% which increased to 9.3% for second stage implantation for a two stage procedure for infection. There was no significant difference in the variability of the dislocating and non-dislocating groups for either inclination (p = 0.393) or anteversion (p = 0.661). Conclusions A “safe zone” for socket orientation to avoid dislocation could not be defined. The cause of dislocation is multifactorial, re-establishing the anatomic centre of rotation, balancing soft tissues and avoidance of impingement around the hip are important considerations.

Lower limb amputation in Northern Netherlands: Unchanged incidence from 1991-1992 to 2003-2004

Background Investigating population changes gives insight into effectiveness and need for prevention and rehabilitation services. Incidence rates of amputation are highly varied, making it difficult to meaningfully compare rates between studies and regions or to compare changes over time. Study Design Historical cohort study of transtibial amputation, knee disarticulation, and transfemoral amputations resulting from vascular disease or infection, with/without diabetes, in 2003-2004, in the three Northern provinces of the Netherlands. Objectives To report the incidence of first transtibial amputation, knee disarticulation, or transfemoral amputation in 2003-2004 and the characteristics of this population, and to compare these outcomes to an earlier reported cohort from 1991 to 1992. Methods Population-based incidence rates were calculated per 100,000 person-years and compared across the two cohorts. Results Incidence of amputation was 8.8 (all age groups) and 23.6 (≥45 years) per 100,000 person-years. This was unchanged from the earlier study of 1991-1992. The relative risk of amputation was 12 times greater for people with diabetes than for people without diabetes. Conclusions Investigation is needed into reasons for the unchanged incidence with respect to the provision of services from a range of disciplines, including vascular surgery, diabetes care, and multidisciplinary foot clinics. Clinical relevance This study shows an unchanged incidence of amputation over time and a high risk of amputation related to diabetes. Given the increased prevalence of diabetes and population aging, both of which present an increase in the population at risk of amputation, finding methods for reducing the rate of amputation is of importance.

IWGDF guidance on the prevention of foot ulcers in at-risk patients with diabetes

Recommendations - 1 To identify a person with diabetes at risk for foot ulceration, examine the feet annually to seek evidence for signs or symptoms of peripheral neuropathy and peripheral artery disease. (GRADE strength of recommendation: strong; Quality of evidence: low) - 2 In a person with diabetes who has peripheral neuropathy, screen for a history of foot ulceration or lower-extremity amputation, peripheral artery disease, foot deformity, pre-ulcerative signs on the foot, poor foot hygiene and ill-fitting or inadequate footwear. (Strong; Low) - 3 Treat any pre-ulcerative sign on the foot of a patient with diabetes. This includes removing callus, protecting blisters and draining when necessary, treating ingrown or thickened toe nails, treating haemorrhage when necessary and prescribing antifungal treatment for fungal infections. (Strong; Low) - 4 To protect their feet, instruct an at-risk patient with diabetes not to walk barefoot, in socks only, or in thin-soled standard slippers, whether at home or when outside. (Strong; Low) - 5 Instruct an at-risk patient with diabetes to daily inspect their feet and the inside of their shoes, daily wash their feet (with careful drying particularly between the toes), avoid using chemical agents or plasters to remove callus or corns, use emollients to lubricate dry skin and cut toe nails straight across. (Weak; Low) - 6 Instruct an at-risk patient with diabetes to wear properly fitting footwear to prevent a first foot ulcer, either plantar or non-plantar, or a recurrent non-plantar foot ulcer. When a foot deformity or a pre-ulcerative sign is present, consider prescribing therapeutic shoes, custom-made insoles or toe orthosis. (Strong; Low) - 7 To prevent a recurrent plantar foot ulcer in an at-risk patient with diabetes, prescribe therapeutic footwear that has a demonstrated plantar pressure-relieving effect during walking (i.e. 30% relief compared with plantar pressure in standard of care therapeutic footwear) and encourage the patient to wear this footwear. (Strong; Moderate) - 8 To prevent a first foot ulcer in an at-risk patient with diabetes, provide education aimed at improving foot care knowledge and behaviour, as well as encouraging the patient to adhere to this foot care advice. (Weak; Low) - 9 To prevent a recurrent foot ulcer in an at-risk patient with diabetes, provide integrated foot care, which includes professional foot treatment, adequate footwear and education. This should be repeated or re-evaluated once every 1 to 3 months as necessary. (Strong; Low) - 10 Instruct a high-risk patient with diabetes to monitor foot skin temperature at home to prevent a first or recurrent plantar foot ulcer. This aims at identifying the early signs of inflammation, followed by action taken by the patient and care provider to resolve the cause of inflammation. (Weak; Moderate) - 11 Consider digital flexor tenotomy to prevent a toe ulcer when conservative treatment fails in a high-risk patient with diabetes, hammertoes and either a pre-ulcerative sign or an ulcer on the distal toe. (Weak; Low) - 12 Consider Achilles tendon lengthening, joint arthroplasty, single or pan metatarsal head resection, or osteotomy to prevent a recurrent foot ulcer when conservative treatment fails in a high-risk patient with diabetes and a plantar forefoot ulcer. (Weak; Low) - 13 Do not use a nerve decompression procedure in an effort to prevent a foot ulcer in an at-risk patient with diabetes, in preference to accepted standards of good quality care. (Weak; Low)

HR-MAS NMR spectroscopy shows regional metabolite variation in bovine articular cartilage

Mechanical stress is an important external factor effecting the development and maintenance of articular cartilage. The metabolite profile of diseased cartilage has been well studied but there is limited information about the variation in metabolite profile of healthy cartilage. With the importance of load in maintaining healthy cartilage, regional differences in metabolite profile associated with differences in load may provide information on how load contributes to the maintenance of healthy cartilage. HR-MAS NMR spectroscopy allows the assessment of tissue samples without modification and was used for assessing the difference in metabolic profile between the load bearing and non-load bearing regions of the bovine articular cartilage. In this preliminary study, we examined cartilage from tibia and femur of four knee joints. Sixteen pairs of 1D-NOESY spectra were acquired. Principle component analysis (PCA) identified chemical shifts responsible for variance. SBASE (AMIX) and the Human Metabolome Database were used in conjunction with previous reported cartilage data for identifying metabolites associated with the PCA results. The major contributors to load-related differences in metabolite profile were N-acetyl groups, lactate and phosphocholine peaks. Integrals of these regions were further analysed using a Student's t-test. In load bearing cartilage regions. N-acetyl groups and phosphocholine were found at significantly higher concentration (p < 0.05 and p < 0.005, respectively) in both femur and tibia, while lactate was reduced in load bearing cartilage (p < 0.005). The results of this pilot HR-MAS NMR study demonstrate its ability to provide useful metabolite information for healthy cartilage.

Feature - No pain, no gain: Pleasure and suffering in technologies of leidenschaft

Training for bodybuilding competition is clearly a serious business that inflicts serious demands on the competitor. Not only did Francis commit time and money to compete, but he also arguably put winning before his physical well-being—enduring pain and suffering from his injury. Bodybuilding may seem like an extreme example, but it is not the only activity in which people suffer in pursuit of their goals. Boxers fight each other in the ring; soccer players risk knee and ankle injuries, sometimes playing despite being hurt; and mountaineers risk their lives in dangerous climbs. In the arts there are many examples of people suffering to achieve their goals: Beethoven kept composing, conducting, and performing despite his hearing loss; van Gogh grappled with depression but kept painting, finding fame only posthumously; and Mozart lived the final years of his life impoverished but still composing. These examples show that many great achievements come at a price: severe suffering...

Partial foot amputations may not always be worth the risk of complications

To the Editor: Dillon and colleagues present a challenging perspective on the evidence comparing partial foot amputation (PFA) and below-knee amputation (BKA) outcomes.1,2 Australia's diabetes-related major amputation rates have only recently reduced to international levels3 and we fear that any oversimplistic perspectives may be detrimental to these improved rates and, importantly, to our patients. Thus, we believe these articles1,2 should be read cognisant of some important points...

Impact of exercise selection on hamstring muscle activation

Objective: To determine the extent to which different strength training exercises selectively activate the commonly injured biceps femoris long head (BFLH) muscle. Methods: This two-part observational study recruited 24 recreationally active males. Part 1 explored the amplitudes and the ratios of lateral to medial hamstring (BF/MH) normalised electromyography (nEMG) during the concentric and eccentric phases of 10 common strength training exercises. Part 2 used functional magnetic resonance imaging (fMRI) to determine the spatial patterns of hamstring activation during two exercises which i) most selectively, and ii) least selectively activated the BF in part 1. Results: Eccentrically, the largest BF/MH nEMG ratio was observed in the 45° hip extension exercise and the lowest was observed in the Nordic hamstring (NHE) and bent-knee bridge exercises. Concentrically, the highest BF/MH nEMG ratio was observed during the lunge and 45° hip extension and the lowest was observed for the leg curl and bent-knee bridge. fMRI revealed a greater BFLH to semitendinosus activation ratio in the 45° hip extension than the NHE (p<0.001). The T2 increase after hip extension for BFLH, semitendinosus and semimembranosus muscles were greater than that for BFSH (p<0.001). During the NHE, the T2 increase was greater for the semitendinosus than for the other hamstrings (p≤0.002). Conclusion: This investigation highlights the non-uniformity of hamstring activation patterns in different tasks and suggests that hip extension exercise more selectively activates the BFLH while the NHE preferentially recruits the semitendinosus. These findings have implications for strength training interventions aimed at preventing hamstring injury.