Epidemiology of anterior cruciate ligament reconstruction: trends, readmissions, and subsequent knee surgery.

BACKGROUND: Anterior cruciate ligament reconstruction is widely accepted as the treatment of choice for individuals with functional instability due to anterior cruciate deficiency. There remains little information on the epidemiology of anterior cruciate ligament reconstruction with regard to adverse outcomes such as hospital readmission and subsequent knee surgery. We sought to identify the frequency of anterior cruciate ligament reconstruction, the rates of subsequent operations and readmissions, and potential predictors of these outcomes.

METHODS: The Statewide Planning and Research Cooperative System (SPARCS) database, a census of all hospital admissions and ambulatory surgery in New York State, was used to identify anterior cruciate ligament reconstructions performed between 1997 and 2006. Patients with concomitant pathological conditions of the knee were included. The patients were tracked for hospital readmission within ninety days after the surgery and for subsequent surgery on either knee within one year. The risks of these outcomes were modeled with use of age, sex, comorbidity, hospital and surgeon volume, and inpatient or outpatient surgery as potential risk factors.

RESULTS: We identified 70,547 anterior cruciate ligament reconstructions, with an increase from 6178 in 1997 to 7507 in 2006. Readmission within ninety days after the surgery was infrequent (a 2.3% rate), but subsequent surgery on either knee within one year was much more common (a 6.5% rate). Patients were at increased risk for readmission within ninety days if they were over forty years of age, sicker (e.g., had a preexisting comorbidity), male, and operated on by a lower-volume surgeon. Predictors of subsequent knee surgery included being female, having concomitant knee surgery, and being operated on by a lower-volume surgeon. Predictors of a subsequent anterior cruciate ligament reconstruction included an age of less than forty years, concomitant meniscectomy or other knee surgery, and surgery in a lower-volume hospital.

CONCLUSIONS: The rate of anterior cruciate ligament reconstruction has increased in frequency. Also, while anterior cruciate ligament reconstruction appears to be a safe procedure, the risk of a subsequent operation on either knee is increased among younger patients and those treated by a lower-volume surgeon or at a lower-volume hospital.