Anterior cruciate ligament injuries : studies on the adverse events and long-term outcomes

Abstract

The overall aims of this thesis were to identify the main adverse events after anterior cruciate ligament (ACL) injuries, to study the clinical presentation and the consequences of the adverse event (post-operative septic arthritis), and to report the long-term outcomes of patients who underwent acute anterior cruciate ligament reconstruction (ACLR) and those who underwent delayed ACLR.

Study I investigated the reasons behind compensation claims filed to the patient insurance company (Löf) by patients with ACL injuries from 2005 to 2014. A total of 530 eligible claims were identified. 352 claims (66%) were accepted and 178 rejected. The most common reasons for accepted claims included post-operative septic arthritis, followed by suboptimal surgery and delays in diagnosis and treatment.

Study II examined patient-reported outcomes and the 5-year risk of revision surgery for patients who suffered from septic arthritis after ACLR. Patients found in the Swedish National Knee Ligament Register (SNKLR) with a primary ACLR using a hamstring or patellar tendon (n=23,075) were included from 2006 to 2013. 268 patients with septic arthritis were found by linking data from SNKLR with data from the Swedish national board of health and welfare. The results showed that patients with septic arthritis had worse scores of Knee injury and Osteoarthritis Outcome Score (KOOS) and the European Quality of life Five Dimensions index (EQ-5D) at all follow-up occasions. Additionally, the 5-year risk of revision was almost twice as high for the septic arthritis patients.

Study III, a subgroup analysis was performed for 158 patients with septic arthritis identified in Study I. The aim was to describe the clinical characteristics of the common infectious agents that cause septic arthritis following ACLR, in order to provide better understanding of their impact on the clinical presentation of the disease, with the objective of improving the diagnostic process. Coagulase-negative Staphylococci were responsible for the majority of the infections (60%), followed by Staphylococcus aureus and Cutibacterium acnes. Patients infected with Staphylococcus aureus had the highest CRP levels, and the shortest duration from the time of ACLR to the first irrigation and debridement operation.

Study IV analyzed the long-term outcomes of acute ACLR and delayed ACLR. 70 patients were randomized between 2006 and 2013 into two groups: acute ACLR within 8 days after injury and delayed ACLR after normalized range of motion (ROM) within 6-10 weeks after injury. 53 patients (out of 70) participated in a long-term follow-up with an average of 13 years after surgery. Satisfactory knee function was observed in both groups. No differences between the groups were found in terms of ROM, anterior knee laxity or isokinetic knee strength tests. KOOS pain and symptoms scores were worse (p=0.019, 0.008) for patients in the delayed group. 13 patients (30%) showed signs of OA in the index knee, compared to 4 patients (9%) in the contralateral knee. 10 patients (48%) in the delayed group showed signs of OA, compared to 3 patients (13%) in the acute group.

In conclusion, the most common reasons for accepted compensation claims after ACL injuries are post-operative septic arthritis, suboptimal surgery and delays in diagnosis and treatment. Patients with septic arthritis have poorer PROMs and higher 5-year risk of revision ACLR. Variations were observed in the clinical presentation of septic arthritis after ACLR depending on the causative infectious agent, with low-virulent agents being responsible for the majority of the infections. ACLR performed within 10 weeks after injury results in satisfactory long-term clinical and patient-reported outcomes but with an increased risk for osteoarthritis compared to the contralateral knee.