Injuries are the major cause of morbidity in young adults in Finland (Koskinen, 2005;
Haikonen & Lounamaa, 2010). Sports injuries are the most common type of injury and young men in particular are a clear high-risk subgroup (Heiskanen, Sirén, et al., 2004;
Parkkari, Kannus, et al., 2004; Haikonen & Lounamaa, 2010). Knee injuries comprise a significant portion of all sport and leisure time injuries (Haikonen & Lounamaa, 2010;
Majewski, et al., 2006; Parkkari, et al., 2004). Knee injuries are a major cause of pain and disability in individuals and they are also a public health concern due to the costs associated with health care, work disability, and incapacitation. Population-based studies of the incidence and risk factors of knee injuries in young adult populations, however, are sparse. This information is essential because health differences during young adulthood may predict greater differences in health at an older age. Young adulthood is a critical age to target intervention programs because health habits are usually stabilising during that age period (Koskinen, 2005). Preventive strategies for knee injuries can only be utilised if their risk factors are known.
Valid diagnostics of knee injuries are critical for choosing the appropriate treatment methods and avoiding unnecessary treatments. Knee injury diagnostics are based on obtaining an accurate history and physical examination. Imaging modalities such as MRI can be performed when the diagnosis remains unclear after examination by a physician and analysis of plain radiographs. MRI became clinically available in the 1980s (Rappeport, et al., 1996), and is frequently used for diagnosing knee pathologies. Today, MRI of the knee joint is routine practice for the detection of trauma-related lesions, and is considered a sensitive and specific diagnostic method for evaluating meniscus and ligament injuries (Crawford, et al., 2007; Fischer, et al., 1991; Mackenzie, et al., 1996;
Oei, et al., 2003; Rappeport, et al., 1996). Lower diagnostic validity is reported, however, when only acute knee injuries are included in the study (Lundberg, et al., 1996). Whether this is due to properties associated with acutely injured knees, such as haemarthrosis or catabolic processes of the meniscal tissue, or to varying methodologies and populations between studies, however, is unclear. There are no studies comparing the diagnostic validity of MRI for fresh and old meniscal lesions in an equivalent population with similar imaging methods.
Most previous studies of the diagnostic value of MRI for chondral lesions have focused on older populations in which the prevalence of osteoarthritis is high (Bredella,
et al., 1999; Disler, et al., 1996; Felson, 1988; Handelberg, et al., 1990; Hodler, et al., 1992;
Potter, et al., 1998; Recht, et al., 1993; Riel, et al., 1999). MRI sensitivity varies widely between these studies (0%–100%) (Handelberg, et al., 1990; Munk, et al., 1998; Spiers, et al., 1993) and continues to be challenging (Figueroa, et al., 2007; von Engelhardt, et al., 2007). It remains unclear whether fresh traumatic chondral lesions of the knee in young adults can be diagnosed preoperatively by the routine MRI protocols used for overall knee examination.
AKP is one of the most common knee complaints in young adults. The pathophysiology behind AKP is poorly known and controversial. Patellar chondral lesions (chondromalacia patellae, CMP) was previously thought to be the reason for AKP, but this has been called into question because not all patients with AKP have patellar chondral lesions (Leslie & Bentley, 1978). According to the recently proposed tissue homeostasis theory, increased loading of the patellofemoral joint leads to a loss of tissue homeostasis in the surrounding innervated tissues, which causes the pain. Only in the most severe cases is loss of tissue homeostasis characterized by macrostructural damage such as chondral lesions (Dye, 2005). The widely accepted patellofemoral malalignment (PFM) theory is complementary to the tissue homeostasis theory. Patellofemoral malalignment may cause increased loading to the patellofemoral joint, which leads to a loss of tissue homeostasis (Sanchis-Alfonso, Vicente, 2011).
Further, the association between clinical symptoms and arthroscopic findings in AKP is not clear. Whether MRI can confirm possible patellar chondral lesions as an underlying cause of AKP is also uncertain, even if cartilage-specific sequences such as axial T1-weighted three-dimensional (3D) spoiled gradient echo (SPGR) is included in the routine knee evaluation protocol (Disler, et al., 1996; Gagliardi, et al., 1994; von Engelhardt, et al., 2007).
A reliable diagnosis of possible articular cartilage lesions as well as many other knee pathologies can be reached by arthroscopy, which allows for a direct view of the patellofemoral joint (Casscells, 1971; Figueroa, et al., 2007). Arthroscopic examination and treatment of the knee, however, also has some potential disadvantages. Because the arthroscopy procedure is invasive, it may lead to work disability, pain, and stress for the patient, and it is also associated with risks related to anaesthesia and surgery.
Furthermore, unnecessary arthroscopies consume already-limited health care resources.
In cases in which no surgically treatable lesion is found, arthroscopy can be considered an unnecessary diagnostic method and should be avoided. Valid preoperative diagnostics of chondral lesions are especially important in the young adult population. Within the last two decades, new treatment methods for chondral lesions, such as autologous chondrocyte implantation, have evolved and their results are generally moderate to good with a follow-up of a few years (Brittberg, et al., 1994; Gomoll, et al., 2010; Peterson, et al., 2002). These methods are especially useful for young adults with traumatic chondral lesions (Gomoll, et al., 2010; Kiviranta & Vasara, 2004; Peterson, et al., 2002; Vasara, et al., 2006). These
advanced surgical procedures are available at only a few hospitals in Finland (Vasara, et al., 2006). Valid, noninvasive diagnostic methods for deep symptomatic chondral lesions could help to choose the appropriate cartilage repair procedure.