In terms of specific diagnosis for common knee disorders (osteoarthritis, ACL tear, meniscal injury and PFS), the APP's diagnostic ability also yields very high sensitivity and specificity as well as high likelihood ratios confirming his ability to correctly diagnose patients with common knee disorders.
Table 1 shows the demographic and baseline characteristics of the ITT population, without differences between groups and well representative of the common knee osteoarthritis outpatient population: mostly women (63%), mean age approximately 67 years, moderately overweight (average body mass index approximately 28) and with Kellgren and Lawrence radiological grades II and III evenly distributed.
Between 19 and 31% of adolescents report knee pain [ 3, 5, 6] with Patellofemoral Pain (PFP) being one of the most common knee conditions among adolescents with a prevalence of approximately 7% [ 6- 8].
The anterior cruciate ligament (ACL) rupture is one of the most common knee injuries in sports.
Meniscal injury is one of the most common knee joint injuries, which remains an intractable challenge in clinical practice to date.
However, the infrapatellar fat pad is richly innervated by nociceptors [ 50] and is a clinically important source of pain in common knee joint pathologies such as patellofemoral syndrome [ 51], osteoarthritis [ 52] and rheumatoid arthritis [ 53].
Aging and degeneration of the menisci result in tears being a common knee injury; 15% of all sports knee injuries involve the meniscus [ 1].
Medial collateral ligament (MCL) sprain was the most common knee injury (56.6% of the knee injuries) and most of them were grade I injuries (51.2%).
For selected common knee disorders, proportion of agreement was highest for ACL tear diagnoses (100%) and lowest for PFS (86%).
APP diagnostic validity compared to the diagnosis of the orthopaedic surgeons for selected common knee disorders (osteoarthritis, ACL rupture, meniscal injury and PFS) was very high as all sensitivity and specificity scores were over 0.90, except for the PFS diagnostic sensitivity, which was 0.86.
