Delay in Primary Anterior Cruciate Ligament Reconstruction Increases Medical Separation Risk in the U.S. Military

OBJECTIVES: Anterior cruciate ligament reconstruction (ACLR) remains one of the most readiness-impairing surgical conditions treated in the US Military. Greater time from the index injury to surgical management (ACLR) unnecessarily prolongs the total time of limited duty. Additionally, prolonged wait times from the index injury to ACLR may increase the patient’s likelihood of sustaining concomitant or secondary intraarticular pathologies (e.g., cartilage and meniscus damage). The optimal timing for surgical reconstruction following ACL injury is debated. The purpose of this study was to determine the impact of prolonged time from injury to surgery on medical separation within five years of primary ACLR. We hypothesized that longer durations from injury to primary ACLR would be associated with greater medical separation risk within five years following surgery. METHODS: We conducted a retrospective database review using data from the Military Health System Data Repository (MDR) of primary ACLR without and with concomitant procedures (meniscus [M] and/or cartilage [C]) performed within Military Treatment Facilities (MTF) from fiscal year 2009 to and/or cartilage [C]) performed within Military Treatment Facilities (MTF) from fiscal year 2009 to 2011. At the time of the ACLR, ADSMs had to be continuously enrolled for two years prior to the surgery with no history of knee surgeries in direct care (i.e., MTFs) or purchased care to ensure a higher likelihood of the index event being a primary ACLR and not an ACLR revision. A total 2,809 active duty service members were included with primary ACLR. The MDR was queried for baseline demographic, military service, and surgical information at the time of ACLR. Duty status at the time of the ACLR and cause of separation up to five years after primary ACLR were abstracted. The time from the index injury diagnosis to the primary ACLR was calculated and grouped as follows: Acute = 0-42 days, Subacute = 43-91 days, Delayed = 92-179 days, Chronic ≥ 180 days. Kaplan-Meier survivability curves were estimated and evaluated with Log-rank. Cox Proportional Hazard Models calculated Hazard Ratios (HR) with 95% confidence intervals (95% CI) to identify time from injury to surgery, demographic, and military status factors that influenced medical separation risk for patients with primary ACLR (ACLR, ACLR+M, ACLR+C, ACLR+M+C). RESULTS: The index surgical events were categorized by isolated ACLR (48%), ACLR+M (42%), ACLR+C (5%), and ACLR+M+C (4%). Overall, the time from diagnosis to ACLR was approximately equivalent across all time categories: Acute (19%), Subacute (31%), Delayed (23%), and Chronic (25%). The probability of medical separation 5 years following primary ACLR (ACLR, ACLR+M, ACLR+C, ACLR+M+C) was highest for the delayed [92-179 days] group (17%) and lowest for the acute [0-42 days] group (12%). Patients in the delayed group were over 51% more likely to medically separate in the 5 years following the primary ACLR than those who were treated within 42 days from injury (acute group). The difference between the acute group and subacute or chronic was not statistically significant. Those in infantry and combat support related military occupation classifications were 27% more likely to medically separate. Service members in the Army were more than 4.5 times more likely to medically separate compared to those in the Air Force. Smoking and BMI over 29 also increased the risk of medical separation within 5 years by 42% and 91%, respectively. The type of injury at the index event (ACLR, ACLR+M, ACLR+C, ACLR+M+C) did not significantly influence the likelihood of medical separation risk. CONCLUSION: Delay in treatment from injury to primary ACLR increases the number of limited duty days, effects medical readiness of ADSM, and military retention rates post ACLR. Specifically, when primary ACLR is delayed 3 to 6 months from injury, ADSM have a 51% increased likelihood of military medical separation risk in the 5 years following the ACLR than if they would have been treated within 41 days of injury. Early recognition of ACL tears as well as availability of surgeons and Operative Rooms (ORs) should be evaluated to determine their contribution to the delay in ACLR in the MHS.