Abstract
PURPOSE: To investigate influence of an increased posterior tibial slope (PTS) on anterior cruciate ligament (ACL) reconstruction graft failure amongst ethnic Chinese in local subjects. METHODS: A total of number of 477 patients who had primary ACL reconstruction done from January 2008 to December 2021 were retrospectively reviewed. Ethnic Chinese patient graft size >7 mm using Hamstring graft by single bundle technique were included. Patients with age more than 50 years old, known medical comorbidities on graft rupture such as diabetes, renal failure, previous contralateral ACL injury, previous ACL revision surgery, concomitant multi-ligamental injuries, high energy trauma such as road traffic accident, contact sport injury were excluded. Included patient with graft rupture and revision surgery done will be matched and compared with those without graft rupture after primary surgery. PTS of both groups of patients will be measured on their true lateral knee X-Ray before their primary ACL reconstruction. Data of both groups (age, sex ratio, graft size, PTS angle) will be compared through Fisher exact test, t-Test and logistic regression. RESULTS: The incidence rate on ACL revision in our local ethnic Chinese patient was around 4.6 % (22 cases). 25 revision cases were matched with 125 control cases, with no statistically significant difference on sex ratio, age at primary operation, graft size among both groups. PTS of revision patient group had significantly higher PTS angle than control group (95 % confident interval, 10.7° vs 8.6°; P < 0.01). Logistic regression showed PTS as a significant factor affecting graft rupture outcome. Odd ratios of graft rupture due to increased PTS were 2.3 (P < 0.01), with increased risk when PTS ≥11.6° shown in logistic regression. CONCLUSIONS: High PTS (>11.6°) will lead to increased ACL graft rupture risk and revision surgery amongst ethnic Chinese in Hong Kong. Patients with high PTS noted in pre-operative status should have their operation planned carefully and may require additional procedure such as slope-correcting operation and lateral augmentation to reduce risk of graft rupture. LEVEL OF EVIDENCE: Level III, retrospective comparative study.