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

Abstract

Patellofemoral (PF) osteoarthritis (OA) is a prevalent and clinically important knee OA subgroup. Malalignment may be an important risk factor for PF OA. However, little is known about alignment in PF OA, particularly in an upright, weightbearing environment. Using a vertically‐oriented open‐bore MR scanner, we evaluated 3D knee alignment in 15 PF OA cases and 15 individually matched asymptomatic controls. We imaged one knee per participant while they stood two‐legged at four flexion angles (0°, 15°, 30°, 45°), and also while they stood one‐legged at 30° knee flexion. We calculated 3D patellofemoral and tibiofemoral alignment. Using mixed effects models, four of the five patellofemoral measures differed by group. For key measures, PF OA patellae were 6.6° [95%CI 5.0, 8.2] more laterally tilted, 2.4 mm [1.3, 3.5] more laterally translated, and at least 3.7 mm [0.2, 7.2] more proximally translated compared to controls (more with knees flexed). Alignment did not differ between two‐legged stance and one‐legged stance in either group. Statement of Clinical Significance: Our study demonstrated significant and clinically relevant differences in alignment between PF OA cases and controls in upright standing and squatting positions. Our findings were similar to those in previous studies of PF OA using traditional MR scanners in supine positions, supporting the clinical usefulness of existing methods aimed at identifying individuals who may benefit from interventions designed to correct malalignment. © 2019 The Authors. Journal of Orthopaedic Research ® Published by Wiley Periodicals, Inc. on behalf of the Orthopaedic Research Society. 9999:1–9, 2019.

Outcomes After Deepening Trochleoplasty and Concomitant Realignment in Patients With Severe Trochlear Dysplasia With Chronic Patellofemoral Pain: Results at 2-Year Follow-up

“… 49 , 50 On the other hand, Collins et al 14 found radiographic and MRI-defined PFOA in 20% to 30% of patients aged 26 to 50 years with persistent PFP. Increasing evidence suggests that morphological abnormalities are related to the differences in alignment between patients with PFOA and controls, 30 , 31 , 35 particularly when the features of patella alta, lateral patellar displacement, and increased lateral patellar tilt are present. 52 Although PFJ malalignment appears to induce increased contact pressure and cartilage shear stress, the mechanism by which an increased joint load contributes to PFP is not completely understood.…”

Clinical findings in patellofemoral osteoarthritis compared to individually-matched controls: a pilot study

“…controls [20][21][22] With the exception of hip strength 12 13 no two studies have yet to evaluate the same clinical features (physical exam, strength, ROM, functional performance), and no study has yet reported on a spectrum of clinical features together in one sample, or associations among such features. A more complete clinical picture of patellofemoral OA would inform clinical research aimed ultimately at primary and secondary knee OA prevention and treatment.…”

Has the modern design of Attune total knee replacement improved outcome in patients with isolated patellofemoral arthritis?

“…This criteria for selecting patients provides a focus on a specific type of arthritis. We believe that patients with isolated patellofemoral arthritis have different patellofemoral biomechanics 2 thus should be assessed separately.…”

“…1 The aetiology is unclear but the altered biomechanics at the patellofemoral joint is believed to be the main cause of progressive patellofemoral degeneration and eventually established patellofemoral osteoarthritis. 2 Severe isolated patellofemoral arthritis can be treated with total knee replacement. [3][4][5][6][7][8] Total knee replacement in general gives a good result but some patients continue to suffer from pain, patellofemoral crepitus and reduced range of movements, which limit their function.…”