Induction of somatosensory evoked potentials by mechanical stimulation in reconstructed anterior cruciate ligaments

Abstract

W e have determined whether somatosensory evoked potentials (SEPs) were detectable after direct mechanical stimulation of normal, injured and reconstructed anterior cruciate ligaments (ACLs) during arthroscopy. We investigated the position sense of the knee before and after reconstruction, and correlated the SEP with instability.Reproducible SEPs were detected in all 19 normal ACLs and in 36 of 38 ACLs reconstructed during a period of 13 months. Of the 45 injured ACLs, reproducible SEPs were detected in 26. The mean difference in anterior displacement in the SEP-positive group of the injured ACL group was significantly lower than that in the SEP-negative group. In the reconstructed group, the postoperative position sense was significantly better than the preoperative position sense. Our results indicate not only that sensory reinnervation occurs in the reconstructed ACL, but also that the response to mechanical loads can be restored, and is strongly related to improvement in position sense. Very little information is available regarding the sensory role of the anterior cruciate ligament (ACL). Although the mechanical contribution of the ligament is well documented, recent information suggests that it may have an important sensory role in initiating protective reflexes to control surrounding muscle tone through the 1a-musclespindle to the afferent-nerve system. [1][2][3][4] Many studies have shown the existence of several types of mechanoreceptor in human and animal ACLs.5-8 Whether these mechanoreceptors and their associated functions are restored after reconstruction of the ACL is uncertain. 1,5 Our aim therefore was to determine whether regenerated nerve fibres and mechanoreceptors in the reconstructed ACL could respond to mechanical loads applied to the ligament and to test for afferent impulses and somatosensory evoked potentials (SEPs), which would indicate functional restoration of axons and mechanoreceptors. Patients and MethodsWe enrolled 110 patients (110 knees) with intact posterior cruciate ligaments (PCL), but with knee injuries, into the study. Their mean age was 31 years (9 to 66). All gave consent and the protocol was approved by the Ethical Board of our institution. In four knees, mechanical stimulation of the intact PCL produced no cortical SE, because of technical defects and these individuals were excluded leaving 106 knees (106 patients, 49 men and 57 women) for analysis.The patients were placed into one of three groups. Group I comprised 21 men and 24 women of mean age 29.8 years with an injury to their ACL, who had been diagnosed with anterior instability before arthroscopy. They underwent an arthroscopically-assisted reconstruction of the ligament. In this group the ACL had been ruptured, but remnants were observed bridging the femur and tibia. These attachment sites were not anatomical and the bridging tissue was flimsy. Knees in which the remnant of the ACL was attached to the PCL were excluded from group I, since the mechanical stimulation of the remnant through its attachment could ind...

Factors Affecting Return to Sport After Anterior Cruciate Ligament Reconstruction

“…Furthermore, other factors such as proprioception and neuromuscular control have also been cited to influence the outcome (Solomonow et al 1987;Huston 1994, 2000;Adachi et al 2002;Ochi et al 2002). In general, a progressive neuromuscular control rehabilitation program should be made to minimize the risk of injury and to promote a greater chance of successful return to competition (Lephart et al 1997;Friden et al 2001;Georgoulis et al 2001;Risberg et al 2001;Beynnon et al 2002).…”

Consequences of Complete ACL Ruptures

“…Ochi et al [ 128 ] tested 45 knees with ACL remnants intact to both the tibia and femur for somatosensory-evoked potentials (SEPs) and JPS. Mechanical stimulation of the ACL remnants elicited SEPs in 58 % of the knees, indicating preserved mechanoreceptors.…”

Temporal change of joint position sense after posterior cruciate ligament reconstruction using multi-stranded hamstring tendons

“…In clinical studies, Ochi et al [22,23] found detectable somatosensory evoked potential in the reconstructed ACL with autologous hamstring tendons by electrical and mechanical stimulations, suggesting that sensory innervation can occur in the reconstructed ACL. In 2000, Iwasa et al [14] investigated the postoperative improvement of the proprioceptive function in the knee with ACL reconstruction, indicating the regeneration of mechanoreceptors in the reconstructed ACL.…”