Changes in clinical symptoms and functional disability in patients with coexisting patellofemoral and tibiofemoral osteoarthritis: a 1-year prospective cohort study

Hirotaka Iijima,Masakazu Hiraoka,Takuya Isho,Tomoki Aoyama,Hiroshi Kuroki,Eishi Kaneda,Kazuyuki Miyanobu,Yuko Yamamoto,Shuichi Matsuda,Naoto Fukutani,Masashi Jinnouchi

doi:10.1186/s12891-017-1486-4

Abstract

BackgroundThis 1-year prospective cohort study aimed to compare the changes in clinical symptoms and functional disability between patients with coexisting patellofemoral (PF) and tibiofemoral (TF) osteoarthritis (OA) and those with isolated TFOA.MethodsSeventy-two patients with medial knee OA were enrolled. Knee pain and functional disability were assessed at baseline and at 1-year follow-up using the Japanese Knee Osteoarthritis Measure (JKOM) and a visual analog scale (VAS). We performed two-way analysis of covariance for the clinical outcome variables to examine, time (baseline and follow-up), group (coexisting PFOA and isolated TFOA), and time-group interaction effects. Furthermore, we conducted post-hoc exploratory analysis to address the possibility that dividing patients according to location of PFOA (i.e., isolated lateral, isolated medial, and mixed [bilateral]) may identify a distinct subgroup with different changes in clinical outcomes at 1-year follow-up.ResultsWe detected group effects only in scores of the JKOM pain subscale (P = 0.012) and VAS (P = 0.033), adjusted for age, sex, and body mass index. Patients with coexisting PFOA have stable moderate level knee pain and functional disability throughout the year which is significantly worse than that in those with isolated TFOA. Post-hoc subgroup analysis demonstrated that change of knee pain likely varied with location of PFOA. Patients with isolated lateral PFOA had mild/moderate level knee pain, and their VAS scores were likely to improve, whereas those with mixed PFOA exhibited stable to worsening moderate/severe knee pain.ConclusionsAlthough we did not detect differences in changes in clinical symptoms and functional disability between patients with coexisting PFOA and those with isolated TFOA, our findings indicate that patients with coexisting PFOA had worse clinical symptoms and functional disability than those with isolated TFOA. The results of the exploratory analysis suggested that patients with coexisting PFOA might have heterogeneous clinical outcomes, and presence of mixed PFOA might be an indicator of severe clinical knee OA.

Highlights

This 1-year prospective cohort study aimed to compare the changes in clinical symptoms and functional disability between patients with coexisting patellofemoral (PF) and tibiofemoral (TF) osteoarthritis (OA) and those with isolated TFOA
Lateral knee OA was defined as a knee having a K/L grade ≥2, along with lateral joint space narrowing (JSN) > medial JSN, and lateral osteophytes > medial osteophytes, using an Osteoarthritis Research Society International (OARSI) atlas [27] according to previously described methods [28, 29]
Baseline characteristics were compared between completers and non-completers (Table 1), and no significant differences were found between the two groups in demographic characteristics, OA disease severity, location of PFOA, patellar alignment, knee pain intensity, and functional disability

Summary

Introduction

This 1-year prospective cohort study aimed to compare the changes in clinical symptoms and functional disability between patients with coexisting patellofemoral (PF) and tibiofemoral (TF) osteoarthritis (OA) and those with isolated TFOA. There is a possibility that the pool of patients with knee OA comprises a number of subgroups with distinct trajectories of pain and functional disability, not all of which are progressive Since identifying these homogenous subgroups would provide information about clinical prognosis and facilitate targeted treatment, this topic has become a recent focus of epidemiologic and clinical studies of knee OA [6, 7]. Recent studies demonstrated that patients with coexisting PFOA and TFOA were more likely to have pain and functional disability as well as knee-specific impairments such as quadriceps weakness and restricted range of motion of the knee joint than those with isolated TFOA did [11,12,13,14]. Patients with coexisting PFOA are known to have altered gait biomechanics with more frequent single-leg stance external knee flexion moments [14], which elevates compressive stresses of the PF [18] and TF [19] joints and increases the risk of progression of clinical and radiographic OA

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Discussion

Conclusion