Muscle fiber atrophy in the quadriceps in knee-joint disorders

Abstract

In order to determine whether there is a different susceptibility of muscle fiber types in the m. vastus lateralis (VL) in knee-joint disorders, histochemical studies were performed on 112 cases. Anterior cruciate ligament (ACL) injuries affected 51 patients; ACL injuries associated with meniscus (ACL + M) injuries affected 29. Twenty-five patients had sustained meniscus injuries and seven had injuries of the collateral ligaments (CL). Fifty-two were athletic and 60 were not. On each biopsy, fiber-type distribution was obtained and the degree of atrophy of each fiber type was estimated from two parameters, the mean diameter and the percentage of atrophied fibers. The distribution of type-1 fibers averaged 38.0% +/- 12.0%. There were no significant differences among disorders in the distribution of type-1 fibers. Both parameters of fiber atrophy revealed a difference in susceptibility between type-1 and type-2 fibers. Atrophy of type-1 fibers was found only in ACL and ACL + M injuries. Type-2 fibers were atrophied in all four disorders. Atrophy of type-2 fibers could be a nonspecific change due to the inactivity of the VL, but type-1 fiber atrophy may relate specifically to the condition of ACL insufficiency.

Chronic disuse and skeletal muscle structure in older adults: sex-specific differences and relationships to contractile function

“…Differences between results might also be explained by the fact that OA participants and controls in the current study are older, and it is generally believed that MHC II fibers are more sensitive to deterioration with age (17). In support of our results, other reports suggest greater atrophy of MHC II fibers with chronic disuse associated with OA (45,50,56,58). However, the histochemical technique (i.e., myosin ATPase staining) used in these prior studies does not permit delineation of pure or hybrid fiber subtypes.…”

“…Our study is also the first to consider the modifying effects of sex on fiber size in response to muscle disuse (45,50,56,58). In MHC IIAX fibers, we observed pronounced atrophy in OA men (Fig.…”

The effect of protein and carbohydrate supplementation on strength training outcome of rehabilitation in ACL patients

“…Hence, our subject group seemed to have been exposed to some degree of atrophy at least of the FT fibers $20%, a phenomenon described earlier to appear in knee-injured patients. 52 Similarly, we found a mean number distribution for all included subjects at ST: 55 AE 3%, FTa 27 AE 2%, and FTx: 18 AE 2% corresponding to values reported for untrained individuals. 32,53 We have a group of patients in the present study who, based on their history of physical activity level, appeared quite as expected; no change, however, appeared in MFA for the whole group following 12 weeks of resistance exercise training.…”

Unilateral chronic insufficiency of anterior cruciate ligament decreases bone mineral content and lean mass of the injured lower extremity

“…Therefore, quadriceps muscles may be predominantly affected by disuse and immobilization than hamstrings muscles. Previous studies have shown that chronic ACL injury affects predominantly quadriceps muscles compared with hamstrings muscles (2,5,17,18), and that it particularly affects the vastus medialis muscles within quadriceps muscles (18). Weakness and atrophy of the quadriceps muscles on the injured side, as shown in the present study, may have been due to selective muscle atrophy of the vastus medialis muscle.…”