Outcomes of anterior cruciate ligament reconstruction from 2 to 20 years post-surgery: a mixed-method approach

Background: Rupture of Anterior Cruciate Ligament (ACL) is one of the common injuries during sports worldwide. Repair of the ruptured ligament with reconstruction is considered as a primary treatment option, especially for those persons who want to return to sport. Persons with such injury are considered to be at 10% higher risk of osteoarthritis. Participants present with reduced muscle strength, physical performance and altered gait pattern following surgery. As osteoarthritis is a multifactorial disease, exploring the muscle strength, physical performance, knee laxity and biomechanics along with the participants’ perspectives related to their knee health would provide insights regarding the recovery in participants with anterior cruciate ligament reconstruction (ACLR). Thesis aims: The overall aim of this thesis was to explore medium (2-10 years) and long-term (10- 20 years) outcomes of ACLR in New Zealand. Specific aims were, firstly, to determine medium (2-10 years) and long-term (10-20 years) outcomes of current management of ACLR in terms of muscle strength, physical performance, knee laxity and biomechanical outcomes, with an emphasis on risk factors associated with post-traumatic osteoarthritis. The second aim was to explore the participants’ experiences of the outcomes of their surgery more than 2 years in relation to physical activity, sports, occupation, and quality of life. Thirdly, the relationship between knee moments and participant-related factors such as muscle strength, time since surgery and sex of the participants was explored. Methods: A series of five related studies were conducted to explore the outcomes of ACLR more than 2 years following surgery. A systematic review and meta-analysis (Study 1) reviewed the literature focusing on the knee angles and moments in participants with ACLR compared to the contralateral limb and uninjured Control groups during walking, stair navigation and jogging activities (Study 1). Reviewing the literature related to the muscle strength and physical performance provided support for a cross-sectional study to explore the patient-reported outcomes [comprising Tegner physical activity scale, Knee Injury Osteoarthritis Outcome Scale (KOOS), Confidence during sports Scale, and Short form-12 (SF-12) Health Survey], thigh muscle strength, physical performance and knee laxity in participants with ACLR. Results of the ACLR group were compared to the Control group (Study 2). A qualitative study was conducted to gain deeper insight into the participants’ perspectives related to their knee health, 2-10 years following surgery (Study 3). A cohort of ten participants took part in the face to face semi-structured interviews. The systematic review and meta-analysis (Study 1) provided the methodological insights for the main cross-sectional study (Study 4) regarding the study design, task for analysis and the variables. To explore the knee angles and moments on injured side in participants with ACLR, a cross-sectional study analysed the peak angles and moments in participants with ACLR during stair navigation 2-10 years of following surgery and results were compared to the contralateral limb and the uninjured Control group (Study 4). Results of the systematic review also informed the variables for the next biomechanical study exploring the association of peak flexion and adduction moments with the muscle strength, time since injury and sex of the participants with ACLR. This study involved 35 participants with ACLR from 2 to 20 years following surgery, and biomechanical variables and muscle strength were measured (Study 5). Results: Results of the systematic review and meta-analysis (Study 1) indicated that joint kinematics of ACL reconstructed knees were similar to Control groups during walking and stair navigation within a few months after surgery. The meta-analysis indicated lower pooled external peak flexion moments for people with ACLR compared to controls during walking and stair ascent. Furthermore, inspection of the forest plots indicated potentially increased peak adduction moments over time following ACLR. Results of Study 2 indicated that participants with ACLR had lower quadriceps eccentric quadriceps strength (p=0.004), physical performance (p=0.019), and higher knee laxity (p=0.027) on the injured side compared to the contralateral knee. Participants with ACLR had higher knee-related pain and symptoms (p<0.001), and poor knee function in sports and quality of life domains (p<0.001) on the KOOS scores compared to the uninjured Control group (Study 2). Participants with ACLR indicated lower scores in Confidence during sports scale, indicating the presence of fear of injury. There was no differences in the level of physical activities among both groups (p=0.009). Results of the qualitative study (Study 3) indicated presence of fear of injury, behavioural manifestations of the fear of injury, and low confidence during sports in most of the ten participants. Results of the cross-sectional study (Study 4) indicated lower peak knee flexion angle in participants with ACLR compared to the Control group on the injured side (p=0.022). Participants with ACLR had lower peak flexion moment (p=0.024) and higher extension moment (p=0.027) on the injured side compared to the contralateral knee during stair ascent. There were no significant differences in the adduction moment on the injured side compared to the contralateral knee in participants with ACLR knee compared to the Control group during stair navigation. Further results from the next cross-sectional study (Study 5) indicated significant associations between the knee flexion moment and concentric quadriceps muscle strength (p< 0.001) and sex of the participant (p= 0.026) during stair ascent, while no association was present with the time since surgery. There were no significant associations between the muscle strength, time since surgery and the sex of the participants with knee adduction moments during ascent and descent. Conclusion: Physical impairments persist mid- to long-term in participants with ACLR. Quadriceps eccentric strength, in particular, does not recover fully. Peak knee flexion moments are reduced on the injured side compared to the contralateral side in participants with ACLR. Furthermore, knee flexion moments are associated with the concentric quadriceps strength and sex of the participants during stair ascent. Women seem to have higher knee flexion moment. Therefore, strengthening the thigh muscle groups may help in restoring and optimising moment symmetry. Persisting fear of injury and low confidence levels in sports was described by a sub-group of the participants. Physical and psychological impairments persist in the mid- to long-term following injury and surgery, therefore, optimum measures targeting those impairments depending on the individual requirement are required to improve the surgical and rehabilitative outcomes and decrease the patient burden