Does posterior tibial slope influence knee functionality in the anterior cruciate ligament-deficient and anterior cruciate ligament-reconstructed knee?
OBJECTIVE
The purpose of this study was to investigate the relation between knee functionality and posterior tibial slope in anterior cruciate ligament (ACL)-deficient and ACL-reconstructed patients.


METHODS
Patients with isolated ACL injuries on the surgical waiting list and patients who underwent ACL reconstruction with bone-patellar tendon-bone grafts between 18 and 24 months after surgery were recruited from the orthopaedic sports injury clinic. The study included 44 ACL-deficient patients (range 16-49) with a mean age of 26.4 years and 24 ACL-reconstructed patients with a mean age of 27.2 years (range, 25 to 49 years). Posterior tibial slope was measured on a digitalized lateral radiograph by use of the posterior tibial cortex as a reference. The Cincinnati scoring system was used to assess knee functionality.


RESULTS
The posterior tibial slope averaged 6.10° ± 3.57° (range, 0° to 17°) in the ACL-deficient group and 7.20° ± 4.49° (range, 0° to 17°) in the ACL-reconstructed group. An anterior tibial slope was not measured in any of the participants. The mean Cincinnati score was 62.0 ± 14.5 (range, 36 to 84) in the ACL-deficient patients and 89.3 ± 9.5 (range, 61 to 100) in the ACL-reconstructed patients. There was a moderate but nonsignificant correlation (r = 0.47) between knee functionality and slope in the ACL-deficient patients. When we divided posterior tibial slope into intervals of 0° to 4° (mean score, 58.4), 5° to 9° (mean score, 59.6), and greater than 10° (mean score, 75.4), a strong significant correlation (r = 0.91, P = .01) was observed between knee functionality and slope. There was a weak but nonsignificant correlation (r = 0.24) between knee functionality and slope in the ACL-reconstructed patients. When we divided posterior tibial slope into intervals of 0° to 4° (mean score, 78.2), 5° to 9° (mean score, 86.1), and greater than 10° (mean score, 89.4), a strong and significant correlation (r = 0.96, P = .0001) was observed between knee functionality and slope.


CONCLUSIONS
The results of this study suggest that ACL-deficient and ACL-reconstructed patients with higher posterior tibial slope have more functional knees.


METHODS
Level IV, therapeutic case series.
Hohmann
Erik
E
Department of Orthopaedic Surgery, Clinical Medical School, University of Queensland, Rockhampton, QLD 4700, Australia. ehohmann@optusnet.com.au
Bryant
Adam
A
Reaburn
Peter
P
Tetsworth
Kevin
K
D000293:Adolescent; D000328:Adult; D016118:Anterior Cruciate Ligament / Q000601:surgery*; D000070598:Anterior Cruciate Ligament Injuries; D001182:Arthroscopy / Q000009:adverse effects / Q000379:methods*; D017760:Bone Malalignment / Q000000981:diagnostic imaging* / Q000503:physiopathology; D050376:Bone-Patellar Tendon-Bone Grafting / Q000009:adverse effects / Q000379:methods; D015331:Cohort Studies; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007593:Joint Instability / Q000503:physiopathology / Q000517:prevention & control*; D007718:Knee Injuries / Q000000981:diagnostic imaging / Q000601:surgery; D008297:Male; D008875:Middle Aged; D011859:Radiography; D016059:Range of Motion, Articular / Q000502:physiology; D019651:Plastic Surgery Procedures / Q000009:adverse effects / Q000379:methods*; D020127:Recovery of Function; D018570:Risk Assessment; D013977:Tibia; D016896:Treatment Outcome; D055815:Young Adult