Quadriceps arthrogenic muscle inhibition: neural mechanisms and treatment perspectives.
OBJECTIVE
Arthritis, surgery, and traumatic injury of the knee joint are associated with long-lasting inability to fully activate the quadriceps muscle, a process known as arthrogenic muscle inhibition (AMI). The goal of this review is to provide a contemporary view of the neural mechanisms responsible for AMI as well as to highlight therapeutic interventions that may help clinicians overcome AMI.


METHODS
An extensive literature search of electronic databases was conducted including AMED, CINAHL, MEDLINE, OVID, SPORTDiscus, and Scopus.


RESULTS
While AMI is ubiquitous across knee joint pathologies, its severity may vary according to the degree of joint damage, time since injury, and knee joint angle. AMI is caused by a change in the discharge of articular sensory receptors due to factors such as swelling, inflammation, joint laxity, and damage to joint afferents. Spinal reflex pathways that likely contribute to AMI include the group I nonreciprocal (Ib) inhibitory pathway, the flexion reflex, and the gamma-loop. Preliminary evidence suggests that supraspinal pathways may also play an important role. Some of the most promising interventions to counter the effects of AMI include cryotherapy, transcutaneous electrical nerve stimulation, and neuromuscular electrical stimulation. Nonsteroidal anti-inflammatory drugs and intra-articular corticosteroids may also be effective when a strong inflammatory component is present with articular pathology.


CONCLUSIONS
AMI remains a significant barrier to effective rehabilitation in patients with arthritis and following knee injury and surgery. Gaining a better understanding of AMI's underlying mechanisms will allow the development of improved therapeutic strategies, enhancing the rehabilitation of patients with knee joint pathology.
Rice
David Andrew
DA
Health and Rehabilitation Research Centre, AUT University, Auckland, New Zealand. david.rice@aut.ac.nz
McNair
Peter John
PJ
D000305:Adrenal Cortex Hormones / Q000627:therapeutic use; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000627:therapeutic use; D001168:Arthritis / Q000150:complications / Q000534:rehabilitation; D017679:Cryotherapy; D004599:Electric Stimulation Therapy; D006801:Humans; D007718:Knee Injuries / Q000150:complications / Q000534:rehabilitation / Q000601:surgery; D018908:Muscle Weakness / Q000503:physiopathology* / Q000628:therapy*; D052097:Quadriceps Muscle / Q000294:innervation* / Q000503:physiopathology*
D000305:Adrenal Cortex Hormones; D000894:Anti-Inflammatory Agents, Non-Steroidal