Immunohistological evaluation of proprioceptive potential of the residual stump of injured anterior cruciate ligaments (ACL)

Abstract

To evaluate proprioceptive potential in residual remnants, tissue harvested from ruptured ACLs in 63 consecutive patients was examined for evidence of residual proprioceptive fibres using H&E, and monoclonal antibodies to S-100 and NFP (neurofilament protein). Histological examination showed good subsynovial and intra-fascicular vascularity with free nerve endings in the majority. Morphologically normal mechanoreceptors (H&E) and proprioceptive fibres (positivity with monoclonal antibody for NFP) were found in 46% and 52.4% of stumps, respectively. A statistically significant correlation between injury duration and persistence of mechanoreceptors and proprioceptive fibres was noted. More fibres were seen where ACL remnant was adherent to PCL. Our study has shown that persistent residual proprioceptive fibres in injured ACLs (especially early cases with PCL adherence) are significant; not shaving ACL remnants may be of potential benefit during ACL reconstruction, as some re-innervation and recovery of proprioceptive potential may be possible, thus improving clinical outcomes.

Fig. 1

Intraligamentous Paccinian-like mechanoreceptors (H&E, high power ×40)

Fig. 2

Intraligamentous fusiform mechanoreceptors (H&E, high power ×40)

Fig. 3

Nerve endings S-100 positive (high power ×40)

Fig. 4

Neurofilament protein (NFP) positive slender axons (high power ×40)