Immunohistochemical study of mechanoreceptors in the tibial remnant of the ruptured anterior cruciate ligament in human knees

Abstract

This study was performed to identify the mechanoreceptors in the tibial remnants of ruptured human anterior cruciate ligaments (ACL) by immunohistochemical staining. Thirty-six specimens of tibial ACL remnants were obtained from patients with ACL ruptures during arthroscopic ACL reconstruction. As control, two normal ACL specimens were taken from healthy knee amputated at thigh level due to trauma. The specimen was serially sectioned at 40 mum. In control group, the average number of sections per specimen was 132, and a total of 264 slices were available. In remnant group, the average number of sections per specimen was 90, and a total of 3,251 slices were available. Immunohistochemical staining was performed to detect the neural element of mechanoreceptors. Histologic examinations were performed under a light microscope and interpreted by a pathologist. Nineteen (8 Ruffini, 11 Golgi) mechanoreceptors were identified in the two normal ACLs, which were evenly distributed at both tibial and femoral attachments. In the remnant group, mechanoreceptors were observed in 12 out of 36 cases (33%), and a total of 17 (6 Ruffini and 11 Golgi) mechanoreceptors observed. No significant differences in the harvest volume, number of sections, age, or time between injury to surgery was observed between the 12 mechanoreceptor-present and the 24 mechanoreceptor-absent ones. The presence of mechanoreceptor at the tibial remnants of torn ACLs was verified. The immunohistochemical staining methodology proved useful, but requires further refinement. Although the mechanoreceptors were detected relatively less frequently than expected, the authors consider that it does not negate the necessity of remnant-preserving ACL reconstruction.

Therapeutic Advantage in Selective Ligament Augmentation for Partial Tears of the Anterior Cruciate Ligament

“…**P \ .01 (n = 6 in each group). 10,27. Immunofluorescent staining for neurofilament demonstrated an enhancement of proprioceptive recovery in animals treated with ACL augmentation in contrast to that observed in the reconstruction group (Figure 5, A and B).…”

Innervation of Partially Inserted Human Tendons Used to Reconstruct Anterior Cruciate Ligament

“…Thus to preserve or to ensure the innervation of the reconstructed ACL should be a main scope of ACR reconstructive surgery [4][5][6]. Sensory innervation is absent from reconstructed ACL [7,21]while innervation has been demonstrated in grafts inserted in ACL remnants [17][18][19][20].…”

“…Nevertheless, this hypothesis is still not supported by clinical findings [15]. In patients with cruciate-retaining total knee arthroplasty mechanoreceptors are present 5 to 12 years later [16], and residual remnants of ruptured ACL contain morphologically normal mechanoreceptors and proprioceptive fibbers evenly distributed at both tibial and femoral attachments in one third of the cases [17][18][19][20]. Conversely, other researchers reported the absence of mechanoreceptors in biopsy samples of ACL after reconstruction with Achilles allografts (1 to 10 years), and absence of sensory function after ACL re-construction, presumably because the ACL grafts were not reinnervated [7,21].…”

Anatomic Single-Bundle Anterior Cruciate Ligament Reconstruction With Remnant Preservation Using Outside-In Technique

“…The presence of mechanoreceptors in the ACL has led several authors to suppose that these receptors influence motor function and, conversely, that their loss leads to dysfunction. 5 A study has reported that knee proprioception, rather than clinically satisfactory mechanical restoration, is more closely related to both the REMNANT PRESERVATION e333 functional outcome and patient satisfaction after ACL reconstruction. 6 Preservation of the ACL remnant as a biological sleeve for the graft is an important issue from the viewpoints of acceleration of revascularization and ligamentization, preservation of the proprioceptive nerve fibers, enhancement of the biological environment for healing, and maintenance of the anchor point at the native tibial attachment, in addition to yielding a lower incidence of tibial bone tunnel enlargement.…”