Effects of Remnant Tissue Preservation on Graft Remodeling of Autologous Hamstring Tendon after Anatomic Double-Bundle Anterior Cruciate Ligament Reconstruction
Author(s):
Iwasaki K. (Japan)
,
Iwasaki K. (Japan)
Affiliations:
Kondo E.
,
Kondo E.
Affiliations:
Onodera Jun
,
Onodera Jun
Affiliations:
Ebata T.
,
Ebata T.
Affiliations:
Shiota J.
,
Shiota J.
Affiliations:
Yagi T.
,
Yagi T.
Affiliations:
Yasuda K.
,
Yasuda K.
Affiliations:
Iwasaki N.
Iwasaki N.
Affiliations:
ESSKA Academy. Iwasaki K. 05/09/18; 209510; P07-186 Topic: Sports Related Injuries
Koji Iwasaki
Koji Iwasaki
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Abstract
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Objectives: Remnant preservation in ACL reconstruction (ACLR) has been expected to have several potential advantages to improve postoperative knee stability, such as enhanced graft coverage, accelerated cell repopulation and revascularization, although these points are arguable. Recently, we reported that preservation of the remnant tissue in ACLR enhanced cell proliferation, revascularization, and regeneration of proprioceptive organs in the ACL graft using Sheep model. However, there is controversy regarding the efficacy of remnant preservation on graft healing in ACLR. The objective of this study was to assess the effects of remnant tissue preservation on graft remodeling of autologous hamstring tendon after anatomic double-bundle (DB) ACLR using MRI analysis.

Methods: A total of 89 patients who underwent the anatomic DB ACLR were unrolled in this study. Based on the Crain classification of ACL remnant tissue, 56 patients underwent the remnant-preserving procedure (Group P) and the remaining 33 patients underwent the remnant-resecting procedure (Group R). The patients were examined at 1 year after surgery. MRI analysis assessed the followings: 1) Signal intensity (SI) ratio of AM and PL bundle, which was calculated as the ratio of absolute SI of each bundle to the SI of the patella tendon. 2) High signal-intensity legion (HSL) between grafted tendon and bone tunnel in AM and PL bundle at 10 mm deep from joint aperture in T2WI. Additionally, we evaluated the degree of initial graft coverage by remnant tissue using an original scoring system (Total 0-9 points). Statistical analyses consisted of Mann-Whitney U test, and Fisher's exact test.

Results: There was no significant difference in anterior laxity between Groups P (mean; 1.3 mm) and R (1.6 mm). SI ratio of AM bundle was significantly lower than that of PL bundle in the both groups (p<0.0006 and p=0.0025, respectively). Regarding initial graft coverage, coverage score of AM bundle was significantly correlated to SI ratio (p=0.042, r=-0.23). In comparison of SI ratio with Groups P and R, there was no significant difference between the 2 groups. However, there was a trend that SI ratio of each bundle in Group P was lower than that in Group R. There was no significant difference in HSL between the both groups.

Conclusions: High-intensity MR signals of graft mid-substance and high signal-intensity legion between grafted tendon and bone tunnel were shown to be correlated with maturation and tendon-to-bone integration, respectively. These two factors showed a trend toward better in remnant-preservation group than in remnant-resection group. In addition, better initial graft coverage by remnant tissue made graft signal intensity lower. These results indicated that remnant tissue might improve graft maturation. In conclusion, this MRI study suggested that remnant tissue preservation may improve graft remodeling of autologous hamstring tendon after anatomic DB ACLR.

Keywords:
ACL, Remnant, MRI
Objectives: Remnant preservation in ACL reconstruction (ACLR) has been expected to have several potential advantages to improve postoperative knee stability, such as enhanced graft coverage, accelerated cell repopulation and revascularization, although these points are arguable. Recently, we reported that preservation of the remnant tissue in ACLR enhanced cell proliferation, revascularization, and regeneration of proprioceptive organs in the ACL graft using Sheep model. However, there is controversy regarding the efficacy of remnant preservation on graft healing in ACLR. The objective of this study was to assess the effects of remnant tissue preservation on graft remodeling of autologous hamstring tendon after anatomic double-bundle (DB) ACLR using MRI analysis.

Methods: A total of 89 patients who underwent the anatomic DB ACLR were unrolled in this study. Based on the Crain classification of ACL remnant tissue, 56 patients underwent the remnant-preserving procedure (Group P) and the remaining 33 patients underwent the remnant-resecting procedure (Group R). The patients were examined at 1 year after surgery. MRI analysis assessed the followings: 1) Signal intensity (SI) ratio of AM and PL bundle, which was calculated as the ratio of absolute SI of each bundle to the SI of the patella tendon. 2) High signal-intensity legion (HSL) between grafted tendon and bone tunnel in AM and PL bundle at 10 mm deep from joint aperture in T2WI. Additionally, we evaluated the degree of initial graft coverage by remnant tissue using an original scoring system (Total 0-9 points). Statistical analyses consisted of Mann-Whitney U test, and Fisher's exact test.

Results: There was no significant difference in anterior laxity between Groups P (mean; 1.3 mm) and R (1.6 mm). SI ratio of AM bundle was significantly lower than that of PL bundle in the both groups (p<0.0006 and p=0.0025, respectively). Regarding initial graft coverage, coverage score of AM bundle was significantly correlated to SI ratio (p=0.042, r=-0.23). In comparison of SI ratio with Groups P and R, there was no significant difference between the 2 groups. However, there was a trend that SI ratio of each bundle in Group P was lower than that in Group R. There was no significant difference in HSL between the both groups.

Conclusions: High-intensity MR signals of graft mid-substance and high signal-intensity legion between grafted tendon and bone tunnel were shown to be correlated with maturation and tendon-to-bone integration, respectively. These two factors showed a trend toward better in remnant-preservation group than in remnant-resection group. In addition, better initial graft coverage by remnant tissue made graft signal intensity lower. These results indicated that remnant tissue might improve graft maturation. In conclusion, this MRI study suggested that remnant tissue preservation may improve graft remodeling of autologous hamstring tendon after anatomic DB ACLR.

Keywords:
ACL, Remnant, MRI
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