The incidence of graft failure after revision anterior cruciate ligament (ACL) reconstruction is three to four times greater than that of primary ACL reconstruction. There are large number of reports about the risk factor of failure after primary ACL reconstruction, but only paucity of data is available about the revision surgery. The purpose of this study was to comprehensively evaluate the risk factors of failure after the revision ACL reconstruction.
Study design: Retrospective cohort study
Forty-six patients (mean age: 20.1 years, 18 males/ 28 females) who underwent revision ACL reconstruction at our hospital and could be followed for at least one year were retrospectively examined. Patients with postoperative infection or insufficient demographic and radiographic data were excluded. Subjects were allocated into two groups: Group F, graft failure; Group N, without graft failure. Several factors were chosen for the analysis , which were age at primary surgery, gender, preoperative Tegner activity scale, duration from graft injury to revision surgery, concomitant meniscus injury, concomitant chondral injury, hyperextended knee, preoperative pivot shift test grade, preoperative KT 2000 side-to-side difference, preoperative space for the ACL (sACL) on one-leg standing plain radiograph, medial and lateral posterior tibial slope (PTS) on CT, preoperative anterior tibial translation on both CT and MRI. Univariate analysis of each factor between two groups were conducted at first, followed by multivariate analysis using significant risk factors from univariate analysis. Receiver operating characteristic (ROC) analysis on preoperative sACL was also performed. Fisher’s exact test and Mann-Whitney U test were used for univariate analysis, and logistic regression analysis was used for multivariate analysis. Statistical significance was set at p<0.05.
Graft failure was observed in six of forty-six patients (13.0%). After univariate analysis, significant differences were noted in hyper extended knee (Group F: 83%, Group N: 15%, p=0.0018) and preoperative sACL(mm) (Group F: 7.2±3.4, Group N: 13.4±4.7, p=0.0042). No differences were observed between two groups in rest of the selected factors. The logistic regression analysis, using hyper extended knee and preoperative sACL as independent variables, revealed that both factors were associated with graft failure (hyper extended knee: p=0.029, OR: 24.3, 95% CI: 1.4-429.4; sACL: p=0.04, OR: 0.58, 95% CI: 0.35-0.98). After ROC analysis of preoperative sACL, a cutoff value of 6.9mm was the optimal threshold for differentiating between the two groups (sensitivity 67%, specificity 97%).
Patients with hyper extended knee or small sACL before the ACL revision reconstruction are predisposed to graft failure, and may require meticulous surgical planning, including graft choice and necessity for additional procedures, and careful postoperative rehabilitation.