Patellofemoral pain in young adults Tissue homeostasis, soft tissue flexibility, and treatment

Patellofemoral pain (PFP) is a prevalent knee condition with multimodal exercise therapy being the cornerstone of conservative treatment strategies, though long-term outcomes remain suboptimal. This thesis investigates PFP through the lens of the "homeostasis model," hypothesizing that impaired patellar hemodynamics due to vascular insufficiency contributes to the condition. Near-Infrared Spectroscopy (NIRS), a non-invasive optical method, was employed to assess patellar bone hemodynamics, marking its first application in PFP research.
Chapter 2 established the reliability of a NIRS protocol for "Prolonged Sitting" and "Stair Descent" in PFP patients and controls, with moderate-to-excellent intraclass correlation coefficients (ICCs). Chapter 3 revealed that PFP patients exhibited reduced changes in (de-)oxygenated hemoglobin concentrations, suggesting impaired patellar hemodynamics. Future studies should target patients experiencing pain during prolonged sitting (PDPS), as Chapter 4 found PDPS affects 73% of PFP patients and correlates with lower functional scores.
Chapter 5 introduced the decline step-down test (DSDT) to assess pain-free knee flexion, demonstrating strong reliability and correlation with patient-related outcome measures. Chapter 6 validated a new lower limb range of motion (LLROM) test, showing reduced flexibility in PFP patients linked to impaired knee function. Chapter 7 evaluated short-term LLROM-targeted interventions, showing moderate efficacy in reducing pain and disability.
The multidisciplinary guideline (Chapter 8) recommends tailored quadriceps- and hip-focused exercises for 6–12 weeks. The thesis concludes that this treatment strategy should be supported by interventions targeting LLROM deficits. Comprehensive re-assessments incorporating DSDT and LLROM testing are advocated to optimize treatment and monitor progress.