Patients with patellofemoral pain exhibit elevated bone metabolic activity at the patellofemoral joint

Department of Radiology, Stanford University, Stanford, California, USA.
Journal of Orthopaedic Research (Impact Factor: 2.99). 02/2012; 30(2):209-13. DOI: 10.1002/jor.21523
Source: PubMed


Patellofemoral pain is characterized by pain behind the kneecap and is often thought to be due to high stress at the patellofemoral joint. While we cannot measure bone stress in vivo, we can visualize bone metabolic activity using (18) F NaF PET/CT, which may be related to bone stress. Our goals were to use (18) F NaF PET/CT to evaluate whether subjects with patellofemoral pain exhibit elevated bone metabolic activity and to determine whether bone metabolic activity correlates with pain intensity. We examined 20 subjects diagnosed with patellofemoral pain. All subjects received an (18) F NaF PET/CT scan of their knees. Uptake of (18) F NaF in the patella and trochlea was quantified by computing the standardized uptake value and normalizing by the background tracer uptake in bone. We detected increased tracer uptake in 85% of the painful knees examined. We found that the painful knees exhibited increased tracer uptake compared to the pain-free knees of four subjects with unilateral pain (P = 0.0006). We also found a correlation between increasing tracer uptake and increasing pain intensity (r(2)  = 0.55; P = 0.0005). The implication of these results is that patellofemoral pain may be related to bone metabolic activity at the patellofemoral joint.

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    • "Depending on factors such as running speed, foot strike pattern and step length, the PFJ experiences peak contact forces between 4-10 body weights (Kernozek et al., 2015; Lenhart et al., 2014; Willson et al., 2015). The repetitive application of elevated forces to the patellar articular cartilage at a high rate of loading is thought to contribute to PFP by increasing patellar interosseous pressure and subchondral bone metabolic activity (Draper et al., 2012; Ho et al., 2013). Altered lower extremity mechanics such as increased hip adduction excursion (Barton et al., 2009) and increased hip and knee abduction angular impulse (Stefanyshyn et al., 2006; Willson and Davis, 2009) have also been observed among runners with PFP and hypothesized to contribute to the etiology or exacerbation of PFJ symptoms. "
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    ABSTRACT: Patellofemoral joint pain (PFP) is a common running-related injury that is more prevalent in females and thought to be associated with altered running mechanics. Changes in running mechanics have been observed following an exhaustive run but have not been analyzed relative to the sex bias for PFP. The purpose of this study was to test if females demonstrate unique changes in running mechanics associated with PFP following an exhaustive run. For this study, 18 females and 17 males ran to volitional exhaustion. Peak PFJ contact force and stress, PFJ contact force and stress loading rates, hip adduction excursion, and hip and knee joint frontal plane angular impulse were analyzed between females and males using separate 2 factor ANOVAs (2 (male/female)×2 (before/after exhaustion)). We observed similar changes in running mechanics among males and females over the course of the exhaustive run. Specifically, greater peak PFJ contact force loading rate (5%, P=.01), PFJ stress loading rate (5%, P<.01), hip adduction excursion (1.3°, P<.01), hip abduction angular impulse (4%, P<.01), knee abduction angular impulse (5%, P=.03), average vertical ground reaction force loading rate (10%, P<.01) and step length (2.1cm, P=.001) were observed during exhausted running. These small changes in suspected PFP pathomechanical factors may increase a runner׳s propensity for PFP. However, unique changes in female running mechanics due to exhaustion do not appear to contribute to the sex bias for PFP.
    Journal of Biomechanics 10/2015; DOI:10.1016/j.jbiomech.2015.10.021 · 2.75 Impact Factor
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    • "It has been reported that individuals with PFP exhibit greater patellofemoral joint stress during weight-bearing activities when compared to painfree controls (Farrokhi, Keyak, & Powers, 2011; Heino Brechter & Powers, 2002). Chronic overloading of the patellofemoral joint is thought to result in pathological changes in the subchondral bone, including bone microfracture (Imhof, Breitenseher , Kainberger, Rand, & Trattnig, 1999; Radin & Rose, 1986), increased subchondral bone metabolic activity (Draper et al., 2011; Dye, 2005; Naslund, Odenbring, Naslund, & Lundeberg, 2005), and elevated bone water content (Li et al., 2008). "
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    ABSTRACT: Abstract Although increased bone water content resulting from repetitive patellofemoral joint loading has been suggested to be a possible mechanism underlying patellofemoral pain (PFP), there is little data to support this mechanism. The purpose of the current study was to determine whether running results in increases in patella water content and pain and whether 48 hours of rest reduces patella water content and pain to pre-running levels. Ten female runners with a diagnosis of PFP (mean age 25.1 years) participated. Patella water content was quantified using a chemical-shift-encoded water-fat magnetic resonance imaging (MRI) protocol. The visual analog scale (VAS) was used to quantify subjects' pain levels. MRI and pain data were obtained prior to running, immediately following a 40-minute running session, and 48 hours post-running. Pain and patella water content were compared among the 3 time points using one-way ANOVA's with repeated measures. Immediately post-running, persons with PFP reported significant increases in pain and exhibited elevated patella water content. Pain and patella water content decreased to pre-running levels following 48 hours of rest. Our findings suggest that transient changes in patella water content associated with running may, in part, contribute to patellofemoral symptoms.
    11/2013; 14(6). DOI:10.1080/17461391.2013.862872
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    • "Draper et al. [25] have demonstrated by real-time MRI that a knee brace which applies a medially directed force on the patella can reduce the lateralization of the patella and tilt in women with PFPS significantly better than a bandage. Powers et al. [56] analysed an orthosis which applied a medially directed force on the patella in PFPS patients. "
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    ABSTRACT: The patellofemoral pain syndrome (PFPS) is a possible cause for anterior knee pain, which predominantly affects young female patients without any structural changes such as increased Q-angle or significant chondral damage. This literature review has shown that PFPS development is probably multifactorial with various functional disorders of the lower extremity. Biomechanical studies described patellar maltracking and dynamic valgus in PFPS patients (functional malalignment). Causes for the dynamic valgus may be decreased strength of the hip abductors or abnormal rear-foot eversion with pes pronatus valgus. PFPS is further associated with vastus medialis/vastus lateralis dysbalance, hamstring tightness or iliotibial tract tightness. The literature provides evidence for a multimodal non-operative therapy concept with short-term use of NSAIDs, short-term use of a medially directed tape and exercise programmes with the inclusion of the lower extremity, and hip and trunk muscles. There is also evidence for the use of patellar braces and foot orthosis. A randomized controlled trial has shown that arthroscopy is not the treatment of choice for treatment of PFPS without any structural changes. Patients with anterior knee pain have to be examined carefully with regard to functional causes for a PFPS. The treatment of PFPS patients is non-operative and should address the functional causes. Level of evidence V.
    Knee Surgery Sports Traumatology Arthroscopy 11/2013; 22(10). DOI:10.1007/s00167-013-2759-6 · 3.05 Impact Factor
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