Summary

The present study offers additional evidence that ACL deficient knees develop changes in sagittal plane alignment as demonstrated by static imaging modality parameters and these changes are accentuated with more chronic ACL ruptures.

Abstract

Title:
Chronicity of anterior cruciate ligament rupture influences morphologic changes of the posterior cruciate ligament and its alignment.

Authors:
Mohammed Alaboudi, Muna Mosa, Tamer Sweed, Shahbaz Malik, Surabhi Chaudhary, Tarek Boutefnouchet

Institutions:
University Hospitals Birmingham NHS Foundation Trust
*Worcestershire Acute Hospitals NHS Trust

Background

The buckling phenomenon of the PCL is representative of anterior tibial translation associated with anterior cruciate ligament (ACL) deficient knees. There are three different parameters of PCL morphologic changes. The aim of the present study was to evaluate the morphological changes of the PCL configuration on MRI, in normal and ACL deficient knees. All three parameters have been previously described in the literature but no comparison made in relation to chronicity of ACL rupture. The hypothesis was that all PCL changes worsen with time elapsed from the injury following ACL rupture.

Methods

A retrospective observational analysis was conducted. MRI scans of ACL deficient knees and control were assessed and PCL parameters were measured. All three measurement as previously described in the literature were obtained. Posterior cruciate ligament angle (PCLA), Posterior cruciate ligament inclination angle (PCLIA), Posterior cruciate ligament posterior cortex angle (PCL-PCA). Comparison was performed between three groups: Acute ACL (<60 days), Chronic ACL (>90 days), Intact ACL (control group). Furthermore, MRI scans were assessed to determine the presence or absence of the anterior menisco-femoral ligament (aMFL) of Humphrey.

Results

A total of 52 acute ACLs, 31 Chronic ACLs and 52 Intact controls were included. All groups had similar demographics. PCLA measurements (Mean+/-SD°) were: 135.98+/-10.82, 126.50+/-12.10, and 133.82+/-7.93 for Acute ACLs, Chronic ACLs and Control respectively. PCLIA measurements (Mean+/-SD°) were: 44.31+/-5.68 , 44.50+/-5.41, and 39.03+/-6.18 for Acute ACLs, Chronic ACLs and Control respectively. PCL-PCA (Mean+/-SD°) were: 20.87+/-7.46, 22.16+/-7.5, and 27.12+/-7.84 for Acute ACLs, Chronic ACLs and Control respectively. The difference (∆) between chronic ACLs and control was significant for all three parameters ∆PCLA 7.3° P=0.001, ∆PCLIA 5.4° P=0.0001, ∆PCL-PCA 4.9° P=0.005. The difference between acute ACLs and control was significant for ∆PCLIA 5.2° P<0.0001 and ∆PCL-PCA 6.2° P=0.0001. The difference between acute and chronic ACLs was only significant for ∆PCLA 9.4° P=0.0004. aMFL was present in 65% (n=53) of ACL deficient knees. There was no significant difference in PCL parameters relative to the presence of aMFL on scans.

Conclusions

PCL alignment measurements undergo changes as a result of ACL rupture. These changes become worse with chronicity of ACL injury. The present study offers additional evidence that ACL deficient knees develop changes in sagittal plane alignment as demonstrated by static imaging modality parameters and these changes are accentuated with more chronic ACL ruptures.