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Patellofemoral joint osteoarthritis: An individualised pathomechanical approach to management

https://doi.org/10.1016/j.berh.2014.01.006Get rights and content

Abstract

Patellofemoral joint integrity is maintained by an optimal interaction of passive, dynamic and structural restraints. Disruption of these mechanics can lead to structural joint damage and subsequent patellofemoral osteoarthritis, which is a prevalent and disabling condition with few effective conservative management strategies. Due to the influential role of biomechanics in this disease, targeting the specific pathomechanics exhibited by an individual is logical to improve their likelihood of a positive treatment outcome. This review summarises the effect of different pathomechanical factors on the presence and progression of patellofemoral osteoarthritis. It then presents a synthesis of mechanical effect of treatment strategies specifically addressing these pathomechanics. Identifying the pathomechanics and clinical characteristics of individuals with patellofemoral osteoarthritis that respond to treatment may assist in the development of individualised treatment strategies that alleviate symptoms and slow structural damage.

Introduction

It is increasingly acknowledged that osteoarthritis (OA) is a complex and multidimensional disease. OA has the fastest growing prevalence of all musculoskeletal diseases and of these conditions was recently found to attract the greatest indirect health costs in terms of years of healthy life lost due to disease and disability adjusted life years [1]. Of the weight-bearing joints, the knee is the most commonly affected by OA [2] and is characterised by joint space narrowing, loss of articular cartilage, osteophyte formation, subchondral bone cysts and synovitis. While the majority of prognostic and intervention studies have focused on the medial tibiofemoral (TF) joint, OA of the patellofemoral (PF) joint, either in isolation or combined with TF OA, is reported to be more prevalent [3]. This is concerning as PF OA is a significant source of knee pain and disability ∗[4], [5].

Older age, female gender, high body mass index and previous anterior cruciate ligament injury are risk factors of both PF and TF OA ∗[6], [7]. However, PF OA has unique clinical characteristics that differentiate it from TF OA, such as difficulty descending stairs and pain on compression of the PF joint [6] (Fig. 1). It is also independently associated with lower self-perceived functional scores [8]. This unique disease burden could be due to the unique mechanics of the PF joint. Unlike the TF joint, the PF joint is not loaded during level walking. Rather, the PF joint reaction forces gradually increase up to 90° of knee flexion and can reach up to 8 times body weight depending on the type of activity (i.e. stair climbing, squatting etc.) [9]. During loaded activities, the PF joint shows maximal contact area and maximal cartilage thickness between 20° and 90° of knee flexion, where the compressive loads are highest [10]. This balance is dependent on optimal interaction of passive, dynamic and structural restraints [11] and can be easily disturbed, resulting in structural joint damage [12]. Thus, PF OA is largely biomechanically mediated and it seems logical that the specific biomechanical factors that are disrupted in a particular individual need to be addressed when designing a treatment strategy.

Designing treatment strategies that are individualised to target patients' specific pathomechanics follows current recommendations for the management of PF OA ∗[4], [13]. Due to the diversity of knee OA with respect to aetiology, clinical and radiographic presentation, one-size-fits-all treatment approaches are suboptimal. Rather, tailoring management to the individual is preferred in order to maximise the likelihood of achieving a positive outcome. A novel approach to tailored management, gaining interest in low back pain research (another prevalent musculoskeletal disorder [1]), is a model of stratified care or subgrouping. Stratified care phenotypes patients based on clusters of signs and symptoms in order to direct clinical decision making towards the most effective management strategies [14]. This approach was recently found to result in greater health benefits than standard-of-care [15].

Patient phenotyping is increasingly encouraged in OA literature [16], ∗[17]. Pathoanatomical phenotyping based on the presence and magnitude of osteophytes, joint space narrowing or cartilage damage [16] facilitates a common language and standardisation between investigators. However, its utility in treatment design is limited due to a disconnect between the pathoanatomical feature and movement impairment or treatment response [18]. In contrast, Eyles et al. [17] reviewed literature that used a prognostic approach to determine particular clinical features exhibited by individuals with hip and knee OA that were predictive of positive outcomes in response to different conservative therapies. The three features with moderate evidence of association with positive outcomes were the absence of depressive symptoms, signs of inflammation and knee alignment. This highlights the importance of person-level and systemic characteristics in the management of any type of OA. While the lack of strong predictive value of mechanical characteristics in this review was surprising, most clinical trials regard patients with knee OA as a homogenous group and this could potentially mask phenotype-specific effects. Hinman and Crossley [4] have previously called for PF OA to be treated as a specific subgroup of knee OA due to unique PF biomechanical function, its prevalence of structural damage and considerable association with pain and disability. With increasing research into PF OA, a synthesis of PF OA pathomechanics and their potential treatments is timely in order to inform clinicians tailoring treatment to individuals for greater effectiveness. Principles of these treatments are likely to be beneficial for other forms of OA, particularly those at weight bearing joints.

This narrative review will summarise the available evidence regarding the pathomechanics of PF OA that have been associated with disease presence, severity and poor prognosis. We will also discuss pathomechanics based on findings from patellofemoral pain syndrome (PFPS) literature, as there is increasing evidence that it may be related to the development of PF OA [19], [20]. Finally, we will describe the effect of specific treatment strategies specifically addressing these pathomechanics and their clinical efficacy in the context of OA-related pain and function. The literature presented in this review was sourced through literature searches up to November 2013 using Medline, PubMed, Scopus and Cinahl electronic databases limited to English-language human-based studies. Relevant reference lists were also searched and authors with multiple publications in the field were contacted for non-Pubmed indexed abstracts.

Section snippets

Framework of contributors to patellofemoral OA

The pathomechanical issue most commonly cited with the presence and progression of PF OA is abnormal PF joint stress (Fig. 2). This abnormality can be due to either excessive magnitude of stress and/or aberrant dispersion of forces. Such abnormalities can contribute to disease progression by disrupting the balance between breakdown and repair of joint tissues [21]. Higher PF joint stress has also been correlated with reduced functional scores on the Knee Osteoarthritis Outcome Survey (KOOS) [22]

Pathomechanical-based targeted treatment strategies for patellofemoral OA

Over recent years, the number of conservative management options for individuals with PF OA has greatly increased. Of these, some aim to reduce the load on the joint in a holistic manner, such as weight-loss and activity modification. There is strong evidence that these treatments reduce the magnitude and frequency of load through all compartments of the knee [64], ∗[65]. Other treatments, such as tape, braces, footwear, gait modifications and strengthening programs, have a more targeted

Future research opportunities

The balance of research pertaining to PF OA suggests that altered mechanics are indicators of a poor prognosis. Due to the lack of correlation between patella malalignment and pain in individuals with PF OA [30], targeting specific PF pathomechanics that increase the odds of PF OA progression, such as shallow trochlear groove or lateral patella tilt, may not be the optimal treatment option. Rather, identifying the PF OA pathomechanics and clinical characteristics in individuals that respond

Conclusion

No system of patient care should be considered as static and there is a need to incorporate new evidence into existing systems. Over recent years many insights have been gained regarding the specific mechanical characteristics that increase the risk of the presence and progression of PF OA. Effective treatment strategies are also becoming evident but, as made evident by this review, there is a gap between efficacy of treatment options and an understanding of their mechanism. This is potentially

Conflicts of interest

The authors declare no conflicts of interest.

References (109)

  • K.M. Crossley et al.

    Altered hip muscle forces during gait in people with patellofemoral osteoarthritis

    Osteoarthr Cartil

    (2012)
  • D.J. Hunter et al.

    Patella malalignment, pain and patellofemoral progression: the Health ABC Study

    Osteoarthr Cartil

    (2007)
  • H.F. Hart et al.

    Quadriceps volumes are reduced in people with patellofemoral joint osteoarthritis

    Osteoarthr Cartil

    (2012)
  • M.B. Pohl et al.

    Gait biomechanics and hip muscular strength in patients with patellofemoral osteoarthritis

    Gait Posture

    (2013)
  • J.J. Elias et al.

    Hamstrings loading contributes to lateral patellofemoral malalignment and elevated cartilage pressures: an in vitro study

    Clin Biomech

    (2011)
  • E.F. Whyte et al.

    The influence of reduced hamstring length on patellofemoral joint stress during squatting in healthy male adults

    Gait Posture

    (2010)
  • S.R. Ward et al.

    The influence of patella alta on patellofemoral joint stress during normal and fast walking

    Clin Biomech

    (2004)
  • J.H. Brechter et al.

    Patellofemoral joint stress during stair ascent and descent in persons with and without patellofemoral pain

    Gait Posture

    (2002)
  • N. Sakai et al.

    The effects of tibial rotation on patellar position

    Knee

    (1994)
  • M.B. Pohl et al.

    Changes in foot and shank coupling due to alterations in foot strike pattern during running

    Clin Biomech

    (2008)
  • S.M. Cowan et al.

    Delayed onset of electromyographic activity of vastus medialis obliquus relative to vastus lateralis in subjects with patellofemoral pain syndrome

    Arch Phys Med Rehabil

    (2001)
  • J. Aaboe et al.

    Effects of an intensive weight loss program on knee joint loading in obese adults with knee osteoarthritis

    Osteoarthr Cartil

    (2011)
  • K.L. Bennell et al.

    A review of the clinical evidence for exercise in osteoarthritis of the hip and knee

    J Sci Med Sport

    (2011)
  • B.L. Wise et al.

    Psychological factors and their relation to osteoarthritis pain

    Osteoarthr Cartil

    (2010)
  • K.L. Bennell et al.

    Hip strengthening reduces symptoms but not knee load in people with medial knee osteoarthritis and varus malalignment: a randomised controlled trial

    Osteoarthr Cartil

    (2010)
  • E.J. McWalter et al.

    The effect of a patellar brace on three-dimensional patellar kinematics in patients with lateral patellofemoral osteoarthritis

    Osteoarthr Cartil

    (2011)
  • D.J. Hunter et al.

    A randomized trial of patellofemoral bracing for treatment of patellofemoral osteoarthritis

    Osteoarthr Cartil

    (2011)
  • K.L. Bennell et al.

    Relationship of knee joint proprioception to pain and disability in individuals with knee osteoarthritis

    J Orthop Res

    (2003)
  • J.H.L. Keet et al.

    The effect of medial patellar taping on pain, strength and neuromuscular recruitment in subjects with and without patellofemoral pain

    Physiotherapy

    (2007)
  • E.A. Christou

    Patellar taping increases vastus medialis oblique activity in the presence of patellofemoral pain

    J Electromyogr Kinesiol

    (2004)
  • J.C. Erhart et al.

    A variable-stiffness shoe lowers the knee adduction moment in subjects with symptoms of medial compartment knee osteoarthritis

    J Biomech

    (2008)
  • C.O. Kean et al.

    Modified walking shoes for knee osteoarthritis: mechanisms for reductions in the knee adduction moment

    (2013)
  • T.R. Jenkyn et al.

    An analysis of the mechanisms for reducing the knee adduction moment during walking using a variable stiffness shoe in subjects with knee osteoarthritis

    J Biomech

    (2011)
  • A problem worth solving

    (2013)
  • R.C. Lawrence et al.

    Estimates of the prevalence of arthritis and selected musculoskeletal disorders in the United States

    Arthritis Rheum

    (1998)
  • R.C. Duncan

    Prevalence of radiographic osteoarthritis – it all depends on your point of view

    Rheumatology

    (2006)
  • R.S. Hinman et al.

    Patellofemoral joint osteoarthritis: an important subgroup of knee osteoarthritis

    Rheumatology

    (2007)
  • G. Peat et al.

    Clinical features of symptomatic patellofemoral joint osteoarthritis

    Arthritis Res Ther

    (2012)
  • A.G. Culvenor et al.

    Is patellofemoral joint osteoarthritis an under-recognised outcome of anterior cruciate ligament reconstruction? A narrative literature review

    Br J Sports Med

    (2012)
  • S. Farrokhi et al.

    Association of severity of coexisting patellofemoral disease with increased impairments and functional limitations in patients with knee osteoarthritis

    Arthritis Care Res

    (2013)
  • S. Elahi et al.

    The association between varus-valgus alignment and patellofemoral osteoarthritis

    Arthritis Rheum

    (2000)
  • T. Luyckx et al.

    Is there a biomechanical explanation for anterior knee pain in patients with patella alta?

    J Bone Joint Surg Br

    (2009)
  • J. Goodfellow et al.

    Patello-femoral joint mechanics and pathology. 2. Chondromalacia patellae

    J Bone Joint Surg Br

    (1976)
  • K.M. Crossley et al.

    Targeted physiotherapy for patellofemoral joint osteoarthritis: a protocol for a randomised, single-blind controlled trial

    BMC Musculoskelet Disord

    (2008)
  • J.C. Hill et al.

    A primary care back pain screening tool: identifying patient subgroups for initial treatment

    Arthritis Rheum

    (2008)
  • P.M. Ludewig et al.

    What's in a name? Using movement system diagnoses versus pathoanatomic diagnoses

    J Orthop Sports Phys Ther

    (2013)
  • M.J. Thomas et al.

    Anterior knee pain in younger adults as a precursor to subsequent patellofemoral osteoarthritis: a systematic review

    BMC Musculoskelet Disord

    (2010)
  • S. Farrokhi et al.

    A biomechanical perspective on physical therapy management of knee osteoarthritis

    J Orthop Sports Phys Ther

    (2013)
  • L.A. Fok et al.

    Patellofemoral joint loading during stair ambulation in people with patellofemoral osteoarthritis

    Arthritis Rheum

    (2013)
  • R.P. Csintalan et al.

    Gender differences in patellofemoral joint biomechanics

    Clin Orthop Relat Res

    (2002)
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