Skyline patellofemoral radiographs can only exclude late stage degenerative changes

Nuffield Orthopaedic Centre NIHR Biomedical Research Unit, Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, United Kingdom.
The Knee (Impact Factor: 1.94). 11/2009; 18(1):21-3. DOI: 10.1016/j.knee.2009.10.008
Source: PubMed


Accurate preoperative assessment of the patellofemoral joint is especially important in compartment specific knee arthritis. This study aims to show the actual intraoperative grade of patellofemoral cartilage damage that may be reliably detected or excluded by preoperative standard radiographic views. 100 consecutive knees awaiting arthroplasty underwent preoperative lateral and skyline radiographs and were scored using the Ahlback score. Intraoperative cartilage damage was assessed using the Collins score. The sensitivity and specificity were calculated for each grade of cartilage damage. Preoperative anterior knee pain and function were assessed and correlated to the degree of cartilage damage. The lateral radiograph shows poor sensitivity for all grades of disease (0.05-0.23). The skyline shows good sensitivity for grade 4 (large full thickness) damage (0.90) but decreases substantially for grades 1-3 (0.19-0.46). Significantly more people with skyline radiograph joint space narrowing complained of anterior knee pain than those with a normal radiograph (p<0.001). There was only a poor correlation between preoperative anterior pain and intraoperative patellofemoral cartilage damage (r=0.24). The lateral radiograph cannot exclude even large areas of full thickness cartilage damage whereas a normal skyline radiograph can reliably exclude significant (grade 4) patellofemoral disease and should be used in addition to the lateral view.

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    • "In the latter, a significantly worse outcome was reported in the literature [9] [10] and a total knee arthroplasty (TKA) might be the preferred treatment option [10]. McDonnell et al. [13] reported that preoperative skyline radiographs can only detect advanced retropatellar arthritis with reference to intraoperative findings but the study did not analyze the medial and lateral patellar cartilage separately. Based on the current literature, the clinical value of skyline radiographs and magnetic resonance imaging (MRI) in the preoperative assessment of the patellofemoral joint is not clearly understood. "
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    ABSTRACT: Background: Lateral patellar arthritis has been associated with poor outcomes in unicompartmental knee arthroplasty. The current study correlates intraoperative findings with MRI imaging, skyline radiographs and the presence of anterior knee pain. Methods: In 92 consecutive knees with varus arthritis, the patellofemoral compartment was assessed during surgery, on skyline radiographs and on MRI. Anterior knee pain was recorded on a visual-analog-scale. Intraoperative assessment was based on the Outerbridge grading scale. Skyline radiographs were evaluated according to the Ahlback grading scale; MRIs were assessed according to a modified Outerbridge grading scale. Results: There was an excellent correlation (r(s)=0.833; p<0.001) in the cartilage assessment of the lateral patellar facet between MRI and surgery. A good correlation (r(s)=0.664; p<0.001) was seen between Ahlback Grades and macroscopic Outerbridge Grades of the lateral patella. Ahlback Grades and MRI modified Outerbridge Grades showed a good correlation (r(s)=0.643; p<0.001) for the lateral patella. Twelve percent of knees (seven out of 60) with Ahlback Grade 0 or 1 and mild to moderate anterior knee pain had a macroscopic Outerbridge Grade of 3 on the lateral patella. None of these 60 knees had a full-thickness cartilage defect on MRI. Conclusion: Normal skyline radiographs in patients with mild to moderate anterior knee pain can rule out full-thickness cartilage defects of the lateral patellar facet as observed during surgery and on MRI. The MRI allows for the most accurate assessment of the patellofemoral joint and is warranted in all patients with radiographic abnormalities or severe anterior knee pain.
    The Knee 05/2014; 21(5). DOI:10.1016/j.knee.2014.05.005 · 1.94 Impact Factor
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    ABSTRACT: Lateral unicondylar knee arthroplasty (UKA) has been utilized as a treatment for isolated lateral tibiofemoral osteoarthritis (OA) since the first description of UKA in the 1970s. To date, there remains some controversy on UKA procedures. As indications for lateral UKA are usually rare, surgeon experience seems to be the key factor for a successful intervention. Better understanding of biomechanics of the knee joint, recent developments in prosthesis design, surgical techniques and indications may add to improved outcomes of lateral UKA. Alternatives that are applied to treat lateral tibiofemoral OA include arthroscopic interventions, osteotomies and total knee arthroplasty (TKA). In comparison with TKA, potential advantages of UKA include a minimally or less invasive approach, less bone resection, preservation of the cruciate ligaments, preservation of the medial tibiofemoral and the patellofemoral compartments, shorter rehabilitation, and physiological knee kinematics. This review aims to summarize the current concepts of implant designs as well as indications and contraindications for lateral UKA. The literature will be presented and discussed as well as results and realistic expectations on both the surgeon's and the patient's side. Alternative treatments and future concepts for lateral UKA will be presented.
    Archives of Orthopaedic and Trauma Surgery 12/2010; 130(12):1539-48. DOI:10.1007/s00402-010-1137-9 · 1.60 Impact Factor
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    ABSTRACT: To assess the intraobserver, interobserver, and test-retest reproducibility of minimum joint space width (mJSW) measurement of medial and lateral patellofemoral joints on standing "skyline" radiographs and to compare the mJSW of the patellofemoral joint to the mean cartilage thickness calculated by quantitative magnetic resonance imaging (qMRI). A couple of standing "skyline" radiographs of the patellofemoral joints and MRI of 55 knees of 28 volunteers (18 females, ten males, mean age, 48.5 ± 16.2 years) were obtained on the same day. The mJSW of the patellofemoral joint was manually measured and Kellgren and Lawrence grade (KLG) was independently assessed by two observers. The mJSW was compared to the mean cartilage thickness of patellofemoral joint calculated by qMRI. mJSW of the medial and lateral patellofemoral joint showed an excellent intraobserver agreement (interclass correlation (ICC) = 0.94 and 0.96), interobserver agreement (ICC = 0.90 and 0.95) and test-retest agreement (ICC = 0.92 and 0.96). The mJSW measured on radiographs was correlated to mean cartilage thickness calculated by qMRI (r = 0.71, p < 0.0001 for the medial PFJ and r = 0.81, p < 0.0001 for the lateral PFJ). However, there was a lack of concordance between radiographs and qMRI for extreme values of joint width and KLG. Radiographs yielded higher joint space measures than qMRI in knees with a normal joint space, while qMRI yielded higher joint space measures than radiographs in knees with joint space narrowing and higher KLG. Standing "skyline" radiographs are a reproducible tool for measuring the mJSW of the patellofemoral joint. The mJSW of the patellofemoral joint on radiographs are correlated with, but not concordant with, qMRI measurements.
    Skeletal Radiology 08/2013; 42(11). DOI:10.1007/s00256-013-1701-9 · 1.51 Impact Factor
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