ABSTRACT
Objective To investigate effects of pressure and tail suspension on the growth of rat skeletal muscles by establishing the tail-suspended rat model and pressure-induced rat model, respectively. Methods Thirty-six male Sprague-Dawley rats were randomly divided into three groups: the control-group (CON), the tail-suspended group (SUS), the pressure group (PRE), and each group was undergoing two stages (7, 14 d) for observation. At the end of the experiment, the muscle wet weight/body weight (Mww/Bw), muscle fiber cross-sectional area (MFCSA), muscle fiber diameter (MFD) of soleus and extensor digitorum longus (EDL) and the IGF-1 concentration were measured, respectively. Results For both the SUS group and PRE group with 7d, their Mww/Bw, MFCSA and MFD of soleus were significantly reduced (P<0.05) as compared to the CON group, which were reduced by 23.52%, 14.26%, 13.47% in PRE group, respectively , while these indexes in SUS group were reduced by 23.52%, 33.07%, 25.09%, respectively. Meanwhile, the decrease of Mww/Bw, MFCSA and MFD in PRE group with 14d was reduced by 20.51%, -10.49%, -5.73%, respectively, which was less than that in PRE group with 7d. However, the decrease of Mww/Bw in SUS group with 14d reached 46.15%, showing significantly higher than that of the SUS group with 7d. For the IGF-1 concentration and EDL changes, no remarkable differences were found among the CON, PRE and SUS groups. Conclusions The impact of pressure on the process of soleus growth is different from that of the suspension (disuse). During the early stage of pressure application, the deep tissue injury mainly with inflammatory responses can be found in the muscle. When the muscle cells adapt to the pressure environment, they may produce a functional adaptation to growth. Therefore, such effect of socket pressure on skeletal muscle should be considered in clinic for prosthetic socket design or rehabilitation training, which will help protect the muscle tissues.
ABSTRACT
Muscle atrophy of the stumps after lower limb amputation has always been a crucial factor resulted in inefficient clinical rehabilitation and athletic recovery for the amputated patients. Therefore, understanding the initiating and developing mechanism of muscle atrophy is very important for the improvement of amputation，restoration training and prosthetic design，which is also widely concerned in the prosthetic rehabilitation field. This paper will review the advances of residual limb muscle atrophy researches on the approaches and models，the mechanical properties of the residual limb，the micro pathologic characteristics as well as the prevention strategies of muscle atrophy in recent years. It can be concluded that further researches are needed to study the special physiologic and mechanical environment in residual limb, which affected the growth of muscle cells as well as the dynamic balance of the muscle protein synthesis and decomposition before completely understanding the mechanism of residual limb muscle atrophy and definitely clarifying its real cause.