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

ABSTRACT 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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Available from: Garry Gold, Sep 26, 2015
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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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    • "Repetitive exposure to this elevated PFJS during running may result in pain due to increased subchondral bone metabolic activity (Draper et al., 2012) or elevated patellar water content (Ho et al., 2013). If increased PFJS is associated with PFP, it follows from these studies that interventions to reduce PFJS during running may benefit both prevention and treatment efforts. "
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    ABSTRACT: Background Patellofemoral pain is common among runners and is frequently attributed to increased patellofemoral joint stress. The purpose of our study was to examine the effects of changing step length during running on patellofemoral joint stress per step and stress per mile in females with and without patellofemoral pain. Methods Ten female runners with patellofemoral pain and 13 healthy female runners performed running trials at 3.7 m/s in three conditions: preferred step length, at least + 10% step length, and at least -10% step length. Knee flexion angles and internal knee extension moments served as inputs for a biomechanical model to estimate patellofemoral joint stress per step. We also estimated total patellofemoral joint stress per mile based on the number of steps necessary to run a mile during each condition. Findings Patellofemoral joint stress per step increased 31% in the long step length condition (P < .001) and decreased 22.2% in the short step length condition (P < .001). Despite the inverse relationship between step length and number of steps required to run a mile, patellofemoral joint stress per mile increased 14% in the long step length condition (P < .001) and decreased 7.5% in the short step length condition (P < .001). Interpretation These results suggest a direct relationship between step length and patellofemoral joint loads. Total stress per mile experienced at the patellofemoral joint decreased with a short step length despite the greater number of steps necessary to cover this distance. These findings may have relevance with respect to both prevention and treatment of patellofemoral joint pain.
    Clinical biomechanics (Bristol, Avon) 01/2013; 29(3). DOI:10.1016/j.clinbiomech.2013.12.016 · 1.97 Impact Factor
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