The anterior cruciate ligament (ACL) serves to stabilise the knee complex and prevent intra-articular knee structures from sustaining damage during multiaxial, high impact movement. An ACL rupture most commonly occurs in adolescents and young adults taking part in competitive sports and causes substantial disruption to the knee joint. Anterior cruciate ligament reconstruction (ACLR) is the most common treatment offered to ACL-ruptured individuals worldwide. Individuals undergoing this surgery often have high expectations that rarely match surgical outcomes. Return to sport rates are low, re-injury fears are widespread and many individuals develop knee osteoarthritis within ten years of ACLR. This mismatch between expectations and actual outcomes has great potential to impact longer-term quality of life (QOL). The primary aims of this thesis were to: (i) generate a detailed picture of longer-term QOL following ACLR, and (ii) identify factors related to longer-term QOL in people with knee pain, symptoms or functional limitations following ACLR.
The first study in this thesis is a systematic review that revealed impaired knee-related QOL at 5 to 20 years after ACLR. However, it became evident that research into factors impacting upon QOL in this population was scarce. The systematic review found that having a subsequent knee injury, an additional knee surgery after ACLR, and developing severe radiographic osteoarthritis were associated with worse QOL outcomes. The second study in this thesis is a systematic review that investigated QOL more than five years after ACL rupture in individuals who remained ACL-deficient (did not undergo ACLR) and compared QOL between ACL-deficient and ACL-reconstructed groups. This systematic review found that ACL-deficient individuals reported comparable QOL outcomes to those who underwent ACLR 5 to 25 years previously. All studies that reported QOL after ACLR included asymptomatic participants without knee difficulties, which may underestimate the degree of QOL impairment experienced by people with ongoing knee difficulties.
The third study in this thesis used a cross-sectional design to describe QOL outcomes in 162 individuals with knee pain, symptoms or functional limitations 5 to 20 years following ACLR. It showed that individuals who did not return to sport after ACLR reported poorer knee-related and health-related QOL, compared to people who returned to pre-injury levels of sport. Higher body mass index (BMI) and subsequent surgery were also related to worse QOL after ACLR. This was the first study to show that return to sport was associated with QOL impairment more than five years after ACLR. However, quantitative assessment of QOL may overlook important considerations with regard to an individual’s life priorities, expectations, values and concerns.
To provide a detailed understanding of QOL following ACLR, qualitative interviews were performed with 17 individuals with knee difficulties 5 to 20 years following ACLR. This was the first qualitative study to explore QOL following ACLR. In these individuals, maintaining a physically active lifestyle was a critical feature of a satisfactory QOL and individuals with a strong preference for competitive sport who did not enjoy recreational exercise appeared to be at risk of experiencing prolonged periods of poor QOL. Fear of re-injury and lifestyle modifications following ACLR were also strong determinants of QOL. Furthermore, exploring personal perspectives of QOL following ACLR provided unique insights into the trajectory of QOL over time that had not been addressed in previous ACLR studies. This allowed identification of key points of transition, where intervention to facilitate positive lifestyle modifications could be most beneficial.
The high rates of early knee osteoarthritis after ACLR are alarming considering the young, active population in which ACLR is most prevalent. The impact of living with symptomatic radiographic osteoarthritis on the QOL of ACL-reconstructed individuals is poorly understood. The fifth study in this thesis explored the relationship between radiographic osteoarthritis and QOL, psychological factors, participant characteristics, work limitations, return to sport and knee symptoms in 81 ACL-reconstructed individuals with knee difficulties. This study found five factors that were strongly associated with increased odds of having radiographic knee osteoarthritis: knee-related QOL impairment, dissatisfaction with knee function, having an ACLR more than six months after ACL injury (compared to less than six months), a non-contact mechanism of ACL rupture and receiving at least one additional surgery since ACLR.
In summary, this thesis identified key factors associated with longer-term QOL impairment in people with knee difficulties after ACLR. However, not all individuals with persistent knee symptoms and difficulties after ACLR were dissatisfied with their current knee function. Achieving satisfactory knee-related QOL appears achievable for some individuals irrespective of the presence of knee pain, osteoarthritis and reduced participation in high-level activities. By identifying specific factors related to unsatisfactory QOL following ACLR, this research has provided valuable information that may facilitate a greater clinical and research focus on improving longer-term QOL following ACLR.