The role of variable muscle adaptation to limb lengthening in the development of joint contractures: an experimental study in the goat

Recovery of Abdominal Muscle Thickness and Contractile Function in Women after Childbirth

Abdominal muscles may be both morphologically and functionally affected by pregnancy. Dysfunction of the muscles can lead to persistent postpartum low back pain. The recovery process of the abdominal muscles following childbirth is not well understood. This study aimed to demonstrate the changes in the thickness and contractile function of abdominal muscles during the first six months postpartum. Nine perinatal and 15 nulliparous females participated. The thicknesses and contraction/relaxation thickness ratios of the rectus abdominis (RA), external abdominal oblique (EO), internal abdominal oblique (IO), and transverse abdominis (TrA) were measured using ultrasound images from 36–39 weeks’ gestation until six months postpartum. The RA, IO, and TrA muscles were thinner in perinatal females than controls at 36–39 weeks of gestation (4.8 vs. 9.47 mm (RA), 5.45 vs. 7.73 mm (IO), 2.56 vs. 3.38 mm (TrA), respectively). The thinner IO muscle persisted for six months after delivery. The decreased TrA thickness ratio persisted until four months post-delivery. Abdominal muscle thickness and contractile function decreased in the postpartum period. Therefore, abdominal muscle exercises might help prevent postpartum symptoms; however, because deterioration of muscle function is significant in the first four months, careful attention should be paid to exercise intensity. The study limitation was a relatively small sample size, thus future studies should involve more participants.

Volumetric muscle loss disrupts length-dependent architectural and functional characteristics of skeletal muscle

Purpose/Aim: Skeletal muscle architecture is a primary determinant of function. Volumetric muscle loss (VML) injury is destructive; however, the impact on muscle architecture is uncharacterized. Methods: Architectural and functional effects of VML were assessed in rat tibialis anterior (TA) muscle model 4 weeks post-injury. Results: VML caused a 31% and 33% reduction in muscle weight (p < 0.001) and fiber length (p = 0.002), respectively, culminating a 34% reduction of fiber to muscle length ratio (FL:ML; p < 0.001). Fiber pennation angle (+14%; p = 0.150) and physiological cross-sectional area (PCSA; -12%; p = 0.220) were unchanged. VML injury reduced peak isometric force (P_o) by 36% (p < 0.001), specific force (sP_o = P_o/PCSA) by 41% (vs. P_o, p > 0.999), and force per gram muscle weight (P_o/mw) by 18% (vs. P_o, p < 0.001). VML injury increased the length at which P_o was produced (L_o) by 8% (p = 0.009), and reduced functional excursion by 35% (p = 0.035). Conclusion: The architectural changes after VML injury preserved PCSA, and therefore preserved "potential" maximal force-producing capacity. At most, only half the P_o deficit was due directly to the cumulative effect of horizontal and longitudinal tissue loss. Highlighting the impact of longitudinal muscle loss, VML injury reduced fiber length, and FL:ML and grossly disrupted length-dependent functional properties. These findings raise the importance of augmenting length-dependent muscle properties to optimize functional recovery after VML injury.

Functional recovery of daily living and sports activities after cosmetic bilateral tibia lengthening

PURPOSE

The aims of this study were to evaluate the recovery of physical function and to investigate whether there are factors that adversely affect functional recovery after cosmetic bilateral lengthening of the tibia.

METHODS

One hundred twenty-five healthy individuals who had undergone bilateral cosmetic tibia lengthening by the lengthening and then nail (LATN) method, lengthening over intramedullary nail (LON) method or intramedullary skeletal kinetic distractor (ISKD) were included in the study. Functional outcomes were evaluated using the Sports Activity Rating Scale (SARS), International Knee Documentation Committee (IKDC) Subjective Knee Form and patient self-reported ability scores.

RESULTS

SARS and IKDC scores decreased at post-operative one year and improved significantly at post-operative two years. SARS and IKDC scores recovered similarly to pre-operative levels. Average patient self-reported ability scores at post-operative two years were 94.6 and 89.9 for daily living and light sports, respectively. However, the average score for moderate-to-strenuous sports was 68.1 and 39 patients (31.2%) recorded below average score for the moderate-to-strenuous sports.

CONCLUSIONS

Patients who had undergone bilateral cosmetic tibial lengthening may expect almost full recovery of daily and light sports activities at post-operativetwo years. However, several patients may feel some limitation in moderate-to-strenuous sports activities.

[Effectiveness of transverse tibial bone transport in treatment of diabetic foot ulcer]

Objective

To evaluate the effectiveness of transverse tibial bone transport in treatment of diabetic foot ulcer.

Methods

Between June 2014 and December 2017, 17 patients with diabetic foot ulcer were treated. There were 11 males and 6 females, with a median age of 57 years (range, 46-72 years). The duration of diabetes was 2.4-32.0 years (mean, 16.0 years). According to the Wagner grading criteria, 7 cases were rated as grade 2, 8 cases as grade 3, and 2 cases as grade 4. The CT angiography (CTA) showed the arterial occlusion or stenosis of varying degrees below knee joint. All cases were treated with transverse tibial bone transport. Bone transport started at 3 to 5 days after placing external fixator and lasted 14 days (1 mm per day), and then reverse transport started. The total transport time was 28-30 days.

Results

All 17 patients were followed up 5-12 months (mean, 8.5 months). During transportation, 4 cases had screw orifice infection, and 3 cases had liquefaction and seepage. And other 15 cases ulcers healed and the healing time was 35-72 days (mean, 48 days). There were significant differences in visual analogue scale (VAS) scores, skin temperature, ankle brachial index (ABI) between before and after ulcer healed ( P<0.05). The CTA showed that the collateral circulation was established. The foot ulcer of 2 cases (Wagener grade 3 in 1 case and grade 4 in 1 case) still progressed after treatment, and amputation was performed.

Conclusion

Transverse tibial bone transports has good effectiveness for diabetic foot ulcer.

Comprehensive Review of Adipose Stem Cells and Their Implication in Distraction Osteogenesis and Bone Regeneration

Bone is one of the most dynamic tissues in the human body that can heal following injury without leaving a scar. However, in instances of extensive bone loss, this intrinsic capacity of bone to heal may not be sufficient and external intervention becomes necessary. Several techniques are available to address this problem, including autogenous bone grafts and allografts. However, all these techniques have their own limitations. An alternative method is the technique of distraction osteogenesis, where gradual and controlled distraction of two bony segments after osteotomy leads to induction of new bone formation. Although distraction osteogenesis usually gives satisfactory results, its major limitation is the prolonged duration of time required before the external fixator is removed, which may lead to numerous complications. Numerous methods to accelerate bone formation in the context of distraction osteogenesis have been reported. A viable alternative to autogenous bone grafts for a source of osteogenic cells is mesenchymal stem cells from bone marrow. However, there are certain problems with bone marrow aspirate. Hence, scientists have investigated other sources for mesenchymal stem cells, specifically adipose tissue, which has been shown to be an excellent source of mesenchymal stem cells. In this paper, the potential use of adipose stem cells to stimulate bone formation is discussed.

Use it or lose it: multiscale skeletal muscle adaptation to mechanical stimuli

Skeletal muscle undergoes continuous turnover to adapt to changes in its mechanical environment. Overload increases muscle mass, whereas underload decreases muscle mass. These changes are correlated with, and enabled by, structural alterations across the molecular, subcellular, cellular, tissue, and organ scales. Despite extensive research on muscle adaptation at the individual scales, the interaction of the underlying mechanisms across the scales remains poorly understood. Here, we present a thorough review and a broad classification of multiscale muscle adaptation in response to a variety of mechanical stimuli. From this classification, we suggest that a mathematical model for skeletal muscle adaptation should include the four major stimuli, overstretch, understretch, overload, and underload, and the five key players in skeletal muscle adaptation, myosin heavy chain isoform, serial sarcomere number, parallel sarcomere number, pennation angle, and extracellular matrix composition. Including this information in multiscale computational models of muscle will shape our understanding of the interacting mechanisms of skeletal muscle adaptation across the scales. Ultimately, this will allow us to rationalize the design of exercise and rehabilitation programs, and improve the long-term success of interventional treatment in musculoskeletal disease.