Allograft Anterior Cruciate Ligament Reconstruction Fails at a Greater Rate in Patients Younger Than 34 Years

Abstract

Purpose: To characterize the secondary anterior cruciate ligament (ACL) injury rates after primary allograft anterior cruciate ligament reconstruction (ACLR) and to identify the age cut-score at which the risk of allograft failure decreases.

Methods: All patients who underwent primary ACLR within a single orthopaedic department between January 2005 and April 2020 were contacted at a minimum of 2 years post-ACLR to complete a survey regarding complications experienced post-surgery, activity level, and perceptions of knee health. Patients were excluded for incidence of previous ACLR (ipsilateral or contralateral) and/or age younger than 14 years. Relative proportions were calculated, binary regression analysis was performed, and receiver operating characteristic analysis was used to identify the threshold age for maximal sensitivity and specificity to predict high risk of allograft failure, defined as undergoing revision ACLR.

Results: Of the 939 surveys completed, 398 patients underwent primary allograft ACLR (mean age 39.5 years; range 16.0-66.1 years; 54.3% female). The secondary ACL injury rate was 11.6% (5.8% ipsilateral revision ACLR, 5.8% contralateral ACL injury). Male and female patients had similar revision (5.5% male, 6.0% female, P = .82) and contralateral ACL injury rates (6.6% male, 5.1% female, P = .52). Receiver operating characteristic analysis indicated that age ≤34 years was threshold for differentiating high risk of allograft failure (area under the curve 0.65, 95% confidence interval 0.55-0.76; P = .014). Patients aged ≤34 years had a greater secondary injury rate than patients >34 years (20.4% (10.2% revision ACLR, 10.2% contralateral ACL injury) versus 6.9% (3.5% revision ACLR, 3.5% contralateral ACL injury; P < .001). Binary regression analysis demonstrated that decreasing age was associated with increased risk of graft failure (χ² = 7.9, P = .02.).

Conclusions: Allograft ACLR showed similar failure rates between sexes but displayed suboptimal graft failure outcomes in younger and active patients. By age 34 years, the increased revision risk for younger patients diminished.

Level of evidence: Level IV, therapeutic case series.

Fig 1

Flowchart for patient inclusion/exclusion. The number of patients contacted and included/excluded based on survey completion and exclusion criteria is detailed. (ACLR, anterior cruciate ligament reconstruction; CPT, Current Procedural Terminology.)

Fig 2

ROC curve. ROC curve used to determine the cut-score age with maximum sensitivity and specificity (maximum Youden’s J value). (ROC, receiver operating characteristic.)

Fig 3

Secondary ACL injury rates by sex and age. Secondary ACL injury rates calculated for each sex and age group by dividing the sum of the number of revision ACLR surgeries and CL ACL injuries by the total number of ACLR surgeries within each group. Patients who had a previous ipsilateral or contralateral ACL surgery were excluded. (ACL, anterior cruciate ligament; ACLR, anterior cruciate ligament reconstruction; CL, contralateral.)

Fig 4

Allograft preinjury activity level breakdown. Proportions of patients who self-classified as competitive athlete, recreational athlete, heavy manual labor job, light manual labor job, active lifestyle, somewhat active, or sedentary were calculated for each age group.