ReviewIsolated patellofemoral osteoarthritis
Introduction
Several recent reports of results of patellofemoral arthroplasty suggest that the surgical treatment of isolated patellofemoral arthritis remains controversial [1], [2], [3], [4]. In patients with degenerative arthritis of the knee, about half have arthritis in the patellofemoral joint. McAlindon et al. [5] have reported in a community survey in the UK of asymptomatic 240 knees that 19% of men and 34% of women over 55 years old have radiographic changes of osteoarthritis isolated to the patellofemoral joint. In a population of 174 (206 knees) over 60 year-olds presenting to secondary care with knee pain 18.5% of men and 17.1% of women had isolated patellofemoral osteoarthritis [6]. With the increasing popularity for unicompartmental knee replacement it is important to consider the patellofemoral joint as a separate entity to the tibiofemoral joint [4], [7].
Section snippets
Anatomy
The patellofemoral joint includes the entire extensor mechanism of the knee, namely the quadriceps tendon, patella and patellar ligament. The patella is a sesamoid bone that acts as a marker for the alignment of the whole extensor mechanism. The trochlear groove and an arch of articular cartilage around the intercondylar notch make up the femoral side of the joint. The patella only articulates with the tibia at the tibial spines. It is also worth realising that intercondylar notch osteophytes
Extensor mechanism malalignment
In the presence of normal patellofemoral anatomy later degenerative change is unlikely [10]. A retrospective review of patients presenting with patellofemoral arthritis showed a higher rate of previous adolescent anterior knee pain than patients presenting with medial tibiofemoral arthritis [11].
Abnormalities of the alignment of the extensor mechanism are well known and are described by analysis of radiographic images. As a screening measure the sulcus angle of greater than 140° is a useful
Clinical presentation of patellofemoral osteoarthritis
Iwano et al. [19] reviewed 66 patients with patellofemoral osteoarthritis of whom 42 were bilateral and 61 were women. The mean age was 63 years (range 36 to 84 years). The study group was 108 knees of which 64 had isolated patellofemoral osteoarthritis. The other 44 knees had tibiofemoral osteoarthritis as well. They looked at seven clinical features:
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Pain on grinding the patella (the patella being moved both medio-laterally and infero-superiorly)
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Crepitation on grinding the patella
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Crepitation
Imaging the patellofemoral joint for osteoarthritis
Although isolated patellofemoral osteoarthritis is common, many rheumatologists and orthopaedic surgeons in the United Kingdom do not routinely ask for a tangential patella, or skyline view. The lateral X-ray of the knee is unreliable in assessing the degree and pattern of patellofemoral osteoarthritis. This can be classified anatomically as, medial, lateral or global according to its site (Fig. 2), as well as by the amount of joint space narrowing. Merchant et al. [21] staged the severity of
Conservative
In the majority of cases standard conservative measures will control the symptoms of pain from patellofemoral arthritis; building up the quadriceps muscle and losing weight. However there is no standardised method of treatment and there has been no validation of any particular technique [22].
Operative
Outcomes from operations for isolated patellofemoral arthritis are difficult to find. Most papers review an operation, and include isolated PFOA amongst a number of other diagnoses. Therefore the true
Conclusions
The evidence base for managing isolated patellofemoral osteoarthritis lags behind that for the tibiofemoral joint. All treatments are based on uncontrolled observational case series, typically retrospectively reviewed, often mixed in with other diagnoses. Fortunately the majority of patients with isolated patellofemoral degenerative changes are not symptomatic and do not need treatment. Those who are symptomatic rarely need surgical intervention, just advice to lose weight and build up
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Cited by (36)
Miscellaneous Complex Pathological Conditions of the Knee
2020, Evidence-Based Management of Complex Knee Injuries: Restoring the Anatomy to Achieve Best OutcomesArthroscopic Patellar Lateral Facetectomy
2017, Arthroscopy TechniquesCitation Excerpt :However, these procedures are more invasive and are associated with more complications.14 Patellar lateral facetectomy is described in the literature as a safe procedure to treat isolated PFOA, and it does not affect a potential patellar replacement, if needed.15 Marten and De Rycke16 reported good-to-moderate results in 90% of 20 patients in a prospective case series, with a mean follow-up of 2 years.
Patellofemoral joint arthroplasty
2017, Orthopaedics and TraumaCitation Excerpt :Similar to tibiofemoral OA, conservative management is the essence of the initial treatment of PFOA. The majority of patients with isolated PFOA can be managed conservatively, with weight loss and quadriceps strengthening exercises being the mainstay of treatment,8 whilst patellar taping and patellar bracing also have the potential to also alleviate symptoms.9 Understanding the recruitment of core muscles and the role of hamstring-quadriceps balance is vital in the non-operative management of PFOA.