Association of post-traumatic pain and knee joint changes according to magnetic resonance imaging

Background. Chronic post-traumatic pain (CPTР) occurs in 15-50% of patients who have suffered knee joint injury (KJ). Post-traumatic pain is considered as one of the predictors of the development of post-traumatic osteoarthritis (PTOA). Early changes in the knee joint, characteristic of the development of PTOA, can be determined using magnetic resonance imaging (MRI).

Aim – to evaluate the relationship between CPTР and structural changes in the knee joint, which are determined using MRI.

Material and methods. The study group consisted of 98 patients, 48% women and 52% men, aged 39.2 ± 14.7 years, who had suffered a knee joint injury with damage to the anterior cruciate ligament (ACL) and/or meniscus (confirmed by MRI data), and experiencing pain ≥4 points on a numerical rating scale (CRS) of at least one month after the injury. The patients were followed up for 12 months. CPTР was determined with pain persistence for at least 3 months at the level of 4 points on the CRS. Repeated MRI was performed 12 months after inclusion in the study. Changes in the knee joint according to the MRI data were quantified using the WORMS system.

Results. CPTР was detected in 45.9% of patients. According to the initial MRI parameters, the groups of patients with CPTР (n=45) and without CPTP (n=53) significantly differed in cartilage morphology (minimal changes were more often detected in patients without CPTР), the presence of osteophytes, damage to the medial collateral ligament and rupture of the medial meniscus body. Almost all patients in both groups had ligament damage and meniscus rupture (with varying degrees of severity), as well as synovitis; about a third of the examined individuals had signs of bone marrow edema. After 12 months observations between patients with and without CPTР showed a significant difference in MRI parameters such as cartilage morphology, osteophytes of the medial condyle of the femur, damage to the posterior cruciate and medial collateral ligaments, rupture of the body, anterior and posterior horns of the medial meniscus, rupture of the anterior horn of the lateral meniscus, synovitis. Thus, severe cartilage damage (≥2 by WORMS) was noted in 82.1% of patients with CPTР and 43.4% without CPTР (p <0.05), synovitis in 95.6% and 24.5% (p <0.05).

Conclusion. CPTР, which occurs after the knee joint injury, is associated with structural changes in the joint, which can be regarded as an early stage of PTOA.