Patellofemoral morphology and alignment: reference values and dose–response patterns for the relation to MRI features of patellofemoral osteoarthritis

Abstract

Objective We aimed to (i) determine reference values for trochlear morphology and patellofemoral (PF) alignment in adults without MRI-defined PF full thickness cartilage damage or knee pain; and (ii) evaluate dose-response patterns for these measures with prevalent MRI-defined PF structural damage and/or knee pain. Design The Framingham Community Cohort is a population-based sample of ambulatory adults aged ≥50 years. We evaluated six morphology and alignment measures using MRI (n=985), and reported reference values (mean ±2SD) in a subsample without MRI-defined PF full thickness cartilage damage or knee pain (n=563). With restricted cubic spline Poisson regression, we evaluated dose-response patterns of each of the six measures with prevalent MRI-defined PF structural damage or joint pain. Our primary outcome was full thickness cartilage damage. Results For dose-response curves, prevalence ratios increased monotonically for all measures except patellar tilt, which rose with both lateral and medial tilt. Associations were generally strongest in the lateral PF compartment. Prevalence ratios (PR) for the strongest predictors of full thickness cartilage damage reached clinical relevance (PR>1.5) at sulcus angle ≥135.0°; patellar tilt angle at ≤1.0° and ≥15.0°; and bisect offset ≥57.0%. Lateral trochlear inclination achieved PR>1.5 at ≤23.0° for full thickness cartilage damage with pain. Conclusions Sulcus angle, patellar tilt, and bisect offset were most strongly associated with full thickness cartilage damage. Lateral trochlear inclination, patellar tilt and bisect offset had stronger associations with the addition of pain. These findings contribute to better identifying a subset of patients who may benefit from mechanically based interventions.

Alignment differs between patellofemoral osteoarthritis cases and matched controls: An upright 3D MRI study

“…Finally, more research is needed to support the clinical understanding of patellar alignment. For example, there is substantial overlap in patellofemoral alignment measures in those with and without patellofemoral OA or pain, and the risk of having OA or pain rises in a graded manner with increasing alignment values—there is no biologically obvious cut‐point for defining “malalignment” . Moreover, the minimal clinically important difference (MCID) has not yet been established for patellofemoral alignment measures.…”

Evaluating risk factors involved in the alteration of biomechanics in relation to knee osteoarthritis

“…A normal patellar position is a very important element in the biomechanical function and its alteration is associated with the appearance of symptomatology (11). In the literature, patellofemoral osteoarthritis is reported to affect 65% of persons aged over 50 years old (12) and the association of patellofemoral osteoarthritis with an abnormal patellar position is emphasized (13). All the patients included in this study with at least grade 1 according to the Kellgren-Lawrence classification had patellofemoral osteoarthritis in varying degrees; further research is needed on this aspect.…”

“…Patella baja is associated with trauma, ischemia of the patellar ligament or with knee surgery (6). In the context of local anatomical changes, alterations of the biomechanics lead to a reduction in the joint functions, in association with pain and instability, leading to progression of osteoarthritis in the femoral-tibial compartment (7). The knee joint is one of the most frequently affected joints by osteoarthritis, along with the hip joint or interphalangeal joints (8).…”

Association between patellofemoral congruence and patellofemoral chondropathy in patients with anterior knee pain: A T2 mapping knee MRI study

“…[10] The trochlear facet asymmetry was determined by measuring the medial (MT) and lateral (LT) trochlea facet lengths 30 mm above the axial cross-section of the articular line and proportioned to each other. [11] The lateral trochlear inclinations (LTI) were determined by measuring the angle between the posterior femoral condyles and the lateral facet with the Cobb method in the most superior axial MR section. [11] The sulcus angle was determined on the axial MR sequence at the level of the deepest depression of the intercondylar groove by measuring the angle between the ventral articular surfaces of the medial and lateral condyle.…”

“…[11] The lateral trochlear inclinations (LTI) were determined by measuring the angle between the posterior femoral condyles and the lateral facet with the Cobb method in the most superior axial MR section. [11] The sulcus angle was determined on the axial MR sequence at the level of the deepest depression of the intercondylar groove by measuring the angle between the ventral articular surfaces of the medial and lateral condyle. [10] The patellar tilt angle (PTA) was determined by drawing a line along the lateral joint surface of the patella and a line drawn along the posterior condylar line using the Cobb method feature of the picture archiving and communication system (PACS) program.…”