Elsevier

Gait & Posture

Volume 41, Issue 1, January 2015, Pages 81-85
Gait & Posture

Altered gait biomechanics and increased knee-specific impairments in patients with coexisting tibiofemoral and patellofemoral osteoarthritis

https://doi.org/10.1016/j.gaitpost.2014.08.014Get rights and content

Highlights

  • Gait analysis was completed in 106 patients with knee osteoarthritis (OA).

  • Severe patellofemoral (PF) OA was associated with reduced knee shock absorption.

  • Severity of PFOA was also associated with higher single-leg stance knee joint loads.

  • Altered gait was related to quadriceps weakness and limited knee extension motion.

Abstract

Coexisting patellofemoral osteoarthritis (PFOA) is a common finding in patients with tibiofemoral osteoarthritis (TFOA). The purpose of this study was to elucidate whether severity of coexisting PFOA in patients with TFOA is correlated with altered sagittal-plane gait biomechanics and greater knee-specific impairments. One hundred and six patients with radiographic TFOA were stratified into three groups of no PFOA, mild PFOA, and severe PFOA. All patients completed instrumented gait analysis, quantitative quadriceps strength testing and knee range of motion assessment. Compared to patients with no PFOA, those with severe PFOA exhibited reduced loading-response knee flexion excursions (p = 0.002) and increased peak single-leg stance external knee flexion moments (p < 0.05). The severe PFOA group also demonstrated lower quadriceps strength compared to the no PFOA and mild PFOA groups (p < 0.001). Regression analysis further revealed that quadriceps strength and knee extension range of motion were independently associated with altered sagittal-plane knee biomechanics during gait (p < 0.03). Reduced loading response knee flexion excursion during gait may be an attempt to decrease patellofemoral joint loading by patients with severe PFOA but it may increase impact loading of their arthritic tibiofemoral joint. Additionally, the greater external knee flexion moments observed during the single-leg stance phase of gait can lead to an overall increase in patellofemoral joint loading and symptoms in patients with more severe PFOA. Given the association between knee-specific impairments and altered gait biomechanics in our study, addressing quadriceps muscle weakness and limited knee extension range of motion may be indicated in patients with TFOA and severe coexisting PFOA.

Introduction

Osteoarthritis (OA) impacts approximately 27 million adults in the United States, with the knee as one of the most commonly affected joints with 50% lifetime risk of developing symptoms [1], [2]. Although the majority of the mechanistic, prognostic and intervention studies of knee OA have focused on the disease of the tibiofemoral (TF) joint, the patellofemoral (PF) joint appears to be the most prevalent site of pathology, with 40–69% of adults with complaints of chronic knee pain having isolated or combined radiographic evidence of PFOA [3], [4]. Additionally, PFOA has been found to be independently associated with quadriceps muscle weakness, limited knee range of motion, increased pain, as well as significant functional limitations and disability [5], [6], [7]. Despite its high prevalence and clinical implications, PFOA remains an understudied aspect of chronic knee pain and an area in need of continued research.

It has been recently speculated that chronic PF pain in younger patients may be a precursor to PFOA later in life [8], [9]. Chronic PF pain in middle-aged adults has also been associated with radiographic signs of PFOA [4]. Given the plausible mechanistic link between chronic PF pain and PFOA, it stands to reason that biomechanical examination of gait patterns in patients with PF pain may provide valuable information regarding potential deviations and compensations adopted by patients with PFOA. To this end, a recent gait study revealed no differences in frontal or transverse plane gait biomechanics between individuals with mild to moderate PFOA and an age-matched control group, despite previous evidence of such alterations in younger patients with PF pain [10]. The authors suggested that normal gait may not be demanding enough to cause frontal or transverse plane gait deviation in this patient population. However, whether patients with PFOA exhibit deviations in the sagittal-plane, where the gait demands are the greatest, was not examined and has yet to be determined.

It has been previously proposed that the PF discomfort associated with high sagittal-plane demands of the gait cycle during level and ramped walking can result in compensation strategies geared toward reducing PF joint loading and pain in young patients with PF pain [11], [12], [13], [14]. As compressive forces of the PF joint are the vector summation of the quadriceps and patellar ligament forces, the high sagittal-plane external knee flexion moments during the loading response phase of gait, which increase the force production requirements of the quadriceps, have been linked with large PF joint compressive forces [15]. Therefore, it has been hypothesized that patients with PF pain often limit their loading response knee flexion excursion as an attempt to reduce pain by limiting the external knee flexion moments and compressive loading of the PF joint [11], [12]. Although such compensatory strategy is a logical approach to decrease PF joint compression and pain, it also reduces the normal active shock absorption of the knee and may lead to deleterious impulse loading and degenerative changes of the TF joint [13], [16].

It also stands to reason that potential sagittal-plane gait deviations in patients with coexisting PFOA and TFOA may exist due to the previously reported increases in severity of knee-specific impairments such as quadriceps muscle weakness and limited knee extension range of motion [6]. For example, reduced knee flexion excursions during the loading response phase of gait have been previously reported in patients with significant quadriceps weakness following anterior cruciate ligament reconstruction and total knee arthroplasty as a strategy to limit the demands placed on weak quadriceps [17], [18]. Similar reductions in knee flexion excursion could be expected in patients with coexisting PFOA and TFOA due to their previously reported quadriceps muscle weakness [6]. Limited loading response knee flexion excursion during gait may also be caused by greater knee flexion angles at heel contact due to reduced knee extension range of motion and the patients’ inability to fully extend their knees [19]. Limited knee extension range of motion can also lead to increased knee flexion angles and greater knee flexion moments during the single-leg stance phase of gait when the knee should be fully extended to reduce the need for quadriceps muscle activity. As a flexed knee joint during the single-leg stance phase of gait creates an external flexion moment about the knee and requires increased quadriceps force to provide lower limb stability, limitations of knee extension range of motion will likely lead to an overall increase in patellofemoral joint loading during this phase of gait.

The purpose of this study was to elucidate whether severity of coexisting PFOA in patients with TFOA is associated with altered sagittal-plane gait biomechanics and increased knee-specific impairments. It was hypothesized that compared to patients with no PFOA, those with increased severity of PFOA will demonstrate decreased loading response knee flexion excursions and increased single-leg stance peak external knee flexion moments. It was also hypothesized that the alterations in knee joint biomechanics during gait will be associated with quadriceps muscle weakness and limited knee extension range of motion.

Section snippets

Subjects

Biomechanical data from a subsample of 106 participants recruited as part of a randomized clinical trial of exercise therapy for knee OA [20] were utilized in this study. Individuals were included in the current study if they met the 1986 American College of Rheumatology clinical criteria for knee OA [21] and had primarily medial compartment disease of grade II or greater on the Kellgren and Lawrence (KL) radiographic disease severity scale [22]. All data reported in this study were collected

Results

Patients with severe PFOA had significantly greater body weight (p = 0.04) and BMI (p = 0.01) compared to the no PFOA group (Table 1). The severe PFOA group also had the highest proportion of patients with grade IV TFOA, while the mild PFOA group had the highest proportion of patients with grade III TFOA, and the no PFOA group had the highest proportion of patients with grade II TFOA (Table 1; p = 0.03). Additionally, severe PFOA was associated with lower quadriceps strength compared to no PFOA and

Discussion

The hypothesis that patients with TFOA and more severe coexisting PFOA exhibit reduced loading response knee flexion angles compared to those with less severe PFOA was supported by the data and is consistent with previous findings in younger patients with PF pain [11], [12]. Given that greater loading response knee flexion angles have been associated with higher PF joint compressive forces [15], the observed reduction in knee flexion angle may be a compensatory strategy to limit the deleterious

Role of the funding source

The funding sources had no role in the study design, data collection, analysis or writing of this manuscript.
Conflicts of interest statement

No authors had any financial or personal relationships with other people or organizations that could have influenced this study.

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  • Cited by (0)

    The project described was supported by the National Institutes of Health through Grant Numbers 1-R01-AR048760 and K12 HD055931 and the Pittsburgh Claude D. Pepper Older Americans Independence Center through Grant number P30 AG024827.

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