Anterior tibial subluxation in anterior cruciate ligament-deficient knees: quantification using magnetic resonance imaging.
OBJECTIVE
The purpose of this study was to quantify anterior tibial subluxation (ATS) at full extension in patients with anterior cruciate ligament (ACL) deficiency using magnetic resonance imaging (MRI), and to elucidate the relation of ATS to the duration of ACL deficiency and the extent of anterior instability.


METHODS
Retrospective case series study.


METHODS
Ninety-six patients with isolated ACL deficiency and no history of injury in the contralateral knee were studied. We used thick-sliced T1-weighted sagittal MRI to quantify ATS at full extension. To measure ATS, MRIs were loaded into a personal computer, and the contour of the unaffected knee was compared with the affected knee using Photoshop software (Adobe, San Jose, CA). Anterior instability was measured using a KT-1000 arthrometer (MedMetric, Inc, San Diego, CA).


RESULTS
The extent of ATS in 96 ACL-deficient knees was 2.1 +/- 1.3 mm (mean +/- SD) and the range was 0 to 4.6 mm. ATS was correlated positively with the duration of ACL deficiency and the extent of anterior instability.


CONCLUSIONS
In ACL-deficient knees, tibiofemoral kinematics differ from a normal knee without external force. The extent increases with time and is positively correlated with instability.


CONCLUSIONS
In ACL reconstruction for patients with a long history or gross instability, when the location of tibial bone tunnel is determined, tibial reference points are more reliable than femoral reference points because the femur shifts relative to the tibia.
Mishima
Shinji
S
Department of Orthopaedic Surgery, Nagoya University School of Medicine, Nagoya, Japan. mishima@med.nagoya-u.ac.jp
Takahashi
Shigeo
S
Kondo
Seiji
S
Ishiguro
Naoki
N
D000293:Adolescent; D000328:Adult; D016118:Anterior Cruciate Ligament / Q000473:pathology; D000070598:Anterior Cruciate Ligament Injuries; D000886:Anthropometry / Q000379:methods; D001696:Biomechanical Phenomena; D005260:Female; D005269:Femur / Q000473:pathology; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007593:Joint Instability / Q000175:diagnosis / Q000209:etiology; D031221:Knee Dislocation / Q000209:etiology*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D012421:Rupture / Q000473:pathology; D016037:Single-Blind Method; D013977:Tibia / Q000473:pathology*; D013997:Time Factors; D014945:Wound Healing