Radiographic assessment of patellofemoral osteoarthritis

Primary Total Knee Arthroplasty: Correlation between Preoperative Radiographic Severity of Arthritis and Postoperative Patient Satisfaction

Predicting postoperative outcomes following total knee arthroplasty (TKA) is important for patient selection. This study focuses on patient-reported outcomes and satisfaction in relation to preoperative radiographic arthritis severity. A retrospective chart review of 420 TKAs was performed. Patient satisfaction was determined using a structured telephone survey with questions focused on degree of satisfaction whether they would have surgery again and their ability to kneel. The radiographic severity of the arthritis of the tibiofemoral joint was graded by a musculoskeletal radiologist using the Kellgren-Lawrence grading scale. The patellofemoral compartment was graded using the scale described by Jones et al. Those grouped as severe arthritis had an overall satisfaction rate of 96% (76% fully satisfied and 20% partially satisfied) compared with 82% of the time (64% fully satisfied and 18% partially satisfied) if their arthritis was mild. Postoperatively 51% of TKA patients were able to kneel. Univariate logistic regression showed an association between higher rates of satisfaction and male gender (p = 0.053), severity of preoperative radiographic arthritis (p = 0.034) those who would have surgery again (p ≤ 0.0001) and those able to kneel (p = 0.005). Patients should be informed preoperatively that if their arthritis is only mild radiographically, their outcomes are less predictable. There should also be a discussion surrounding kneeling and activities patients do, which may require kneeling, as many are unable to kneel postoperatively. The Level of Evidence for the study is III.

Clinical value of weight-bearing CT and radiographs for detecting patellofemoral cartilage visualized by MRI in the MOST study

OBJECTIVE

The patellofemoral joint is frequently affected by osteoarthritis (PFOA) and is incompletely imaged on radiographs (XR). Weight-Bearing CT (WBCT) could offer advantages for visualization. This study determined the sensitivity, specificity, and accuracy of axial WBCT and lateral XR for detection of PFOA features in comparison with cartilage damage on MRI.

DESIGN

A convenience sample of 60 right knees from the MOST cohort were analyzed. WBCT and XR were read for OARSI JSN score and MRI for MOAKS cartilage score by two experienced musculoskeletal radiologists blinded to participant. Using MOAKS scoring on MRI (referent standard), the sensitivity, specificity and accuracy of patellofemoral OARSI JSN scores based on WBCT and XR were compared.

RESULTS

The mean ± SD age and BMI for the participants included (66.7% women) were 67.6 ± 9.8 years and 30.0 ± 5.3 kg/m² respectively. WBCT demonstrated significantly greater sensitivity (0.85-0.97 on WBCT vs 0.47-0.57 on XR) and accuracy (0.85-0.92 on WBCT vs 0.48-0.57 on XR) for all parameters except lateral full-thickness cartilage loss (McNemar's test p-values all <0.001). There was moderate-to-strong and low-to-moderate agreement between PFOA findings on WBCT and XR, respectively, and semi-quantitative scores of PF cartilage on MRI. Inter-rater reliability for XR JSN [weighted kappa = 0.83 (0.64, 1.0)], WBCT JSN [kappa = 0.60 (0.48, 0.72)] and MRI MOAKS-CM [kappa = 0.70 (0.61, 0.79)] readings were good.

CONCLUSION

WBCT demonstrates significantly greater sensitivity and accuracy than radiographs for identification of PFOA. Given the same Relative Radiation Level as XR and improved visualization, WBCT holds promise to improve understanding of the weight-bearing patellofemoral joint.

Scoring Osteoarthritis Reliably in Large Joints and the Spine Using Whole-Body CT: OsteoArthritis Computed Tomography-Score (OACT-Score)

A standardized method to assess structural osteoarthritis (OA) burden thorough the body lacks from literature. Such a method can be valuable in developing personalized treatments for OA. We developed a reliable scoring system to evaluate OA in large joints and the spine-the OsteoArthritis Computed Tomography (OACT) score, using a convenience sample of 197 whole-body low-dose non-contrast CTs. An atlas, containing example images as reference points for training and scoring, are presented. Each joint was graded between 0-3. The total OA burden was calculated by summing scores of individual joints. Intra- and inter-observer reliability was tested 25 randomly selected scans (N = 600 joints). Intra-observer reliability and inter-observer reliability between three observers was assessed using intraclass correlation coefficient (ICC) and square-weighted kappa statistics. The square-weighted kappa for intra-observer reliability for OACT-score at joint-level ranged from 0.79 to 0.95; the ICC for the total OA grade was 0.97 (95%-CI, 0.94 to 0.99). Square-weighted kappa for interobserver reliability ranged from 0.48 to 0.95; the ICC for the total OA grade was 0.95 (95%-CI, 0.90 to 0.98). The OACT score, a new reproducible CT-based grading system reflecting OA burden in large joints and the spine, has a satisfactory reproducibility. The atlas can be used for research purposes, training, educational purposes and systemic grading of OA on CT-scans.

High prevalence of patellofemoral osteoarthritis in China: a multi-center population-based osteoarthritis study

BACKGROUND

To describe the prevalence and risk factors of patellofemoral osteoarthritis (PFOA) among Chinese residents.

METHODS

A multi-center population-based osteoarthritis study was conducted in 2014. Residents aged ≥ 50 years old were recruited using a cluster sampling method. Subjects completed a home interview and physical examination and had skyline view of radiographs at patellofemoral (PF) joints. Radiographs were read by two trained musculoskeletal researchers, and discordance of a subject's PFOA status between two readers was adjudicated with a third musculoskeletal researcher present. Radiographic OA at PF joint was defined if osteophytes (OST) score was ≥ 2 or if joint space narrowing (JSN) score was ≥ 2 with concurrent grade 1 OST in the PF joint.

RESULTS

Of 3446 subjects (63.0% women) included in this analysis, the prevalence of radiographic PFOA was 23.9% (20.5% men vs. 25.8% women). Prevalence of lateral radiographic OA was higher than medial radiographic OA at PF joint. Grades of both osteophytes and joint space narrowing in the lateral patellofemoral compartment were higher than those in the medial patellofemoral compartment (all P values < 0.001). Women, older age, higher BMI, and fewer years of education were significantly associated with higher prevalence of radiographic PFOA, osteophytes, and joint space narrowing.

CONCLUSION

Prevalence of radiographic PFOA was high among Chinese population. Key Points • The multi-center population-based osteoarthritis study shows the prevalence of radiographic PFOA was high among Chinese population. • Older age, female gender, obesity, and few years of education were associated with a high risk of PFOA. • Prevalence of lateral radiographic OA was higher than medial radiographic OA at PF joint.

The effects of knee meniscectomy on the development of osteoarthritis in the patellofemoral joint 40 years following meniscectomy

Most knee osteoarthritis and meniscectomy studies focus on osteoarthritis in the tibiofemoral joint and ignore the patellofemoral joint. This study aims to assess the long-term effects of total meniscectomy on the patellofemoral joint. To our knowledge, this is the only study of osteoarthritis in the patellofemoral joint following meniscectomy that extends to a 40-year follow-up period. Twenty-two patients with osteoarthritis were evaluated at a mean of 40 years post-meniscectomy using standardised weight-bearing radiographs of the operated and non-operated knees. Patellofemoral joint osteoarthritis was diagnosed by the presence of osteophytes and joint space narrowing to less than 5 mm. Kellgren and Lawrence scores were calculated from the radiographs. Patellofemoral joint osteoarthritis and tibiofemoral joint osteoarthritis were correlated with International Knee Documentation Committee scores and range of movement measurements. A significant difference was observed between the operated and non-operated knees in terms of patellofemoral joint osteophyte formation. There was a significant difference in tibiofemoral joint Kellgren and Lawrence scores, International Knee Documentation Committee scores and range of movement measurements between knees with lateral facet patellofemoral joint space of < 5 mm and > 5 mm. This study shows an association between open total meniscectomy and patellofemoral joint osteoarthritis at 40 years following surgery. There was also an association between patellofemoral joint space narrowing in the lateral facet and tibiofemoral joint osteoarthritis. Possible causes include altered biomechanical loading patterns following meniscectomy as well as global processes within the knee.

[Influence of lateral retinacular release on anterior knee pain following total knee arthroplasty]

Objective

To investigate the effect of lateral retinacular release on the clinical outcomes after total knee arthroplasty (TKA) without resurfacing of the patella.

Methods

A prospective randomized controlled study was performed on 132 patients with unilateral degenerative knee arthritis undergoing TKA bewteen October 2012 and October 2014, who met the selection criteria. During TKA, lateral retinacular release was used in 66 cases (trial group) and was not used in 66 cases (control group). Two patients were excluded from the study due to missing the follow-up in trial group. Four patients were excluded from the study due to lateral retinacular release in control group. Finally, 64 patients and 62 patients were included in the trial group and in the control group. There was no significant difference in gender, age, body mass index, side, disease duration, preoperative patellar morphology, grading of patellofemoral arthritis, grade of patellar cartilage degeneration, patellar malposition, patellar maltracking, patellar score, and Knee Society Score (KSS) between 2 groups ( P>0.05). The operation time, postoperative drainage volume, hospitalization time, postoperative complications, and patient satisfaction were recorded. Postoperative anterior knee pain was assessed by visual analogue scale (VAS), and the knee joint function was evaluated by KSS score and patellar score. The femoral angle, tibial angle, femoral flexion angle, and tibial posterior slope angle were measured on the X-ray film for postoperative prosthetic alignment. The postoperative patellar tracking and patellar position, as well as the presence of osteolysis, prosthesis loosening, patellar fracture and patellar necrosis were observed.

Results

All patients were followed up for 24 months. There was no significant difference in operation time, postoperative drainage volume, hospitalization time, and patient satisfaction between 2 groups ( P>0.05). The incidence of anterior knee pain in the trial group was better than that in the control group ( P=0.033). KSS score and patellar score were significantly improved in both groups at 24 months after operation when compared with preoperative scores ( P<0.05), but no significant difference was found between 2 groups ( P>0.05). Complications included hematoma (2 cases in the trial group, and 1 case in the control group), mild wound dehiscence (2 cases in each group respectively), skin-edge necrosis (1 case in the trial group), and superficial wound infection (1 case in each group respectively), which were cured by conservative treatment. No patellar necrosis, patella fracture, or knee lateral pain occurred in 2 groups. There was no significant difference in complication rate between groups ( P=0.392). Satisfactory implant alignment was observed in both groups during follow-up. There was no significant difference in femoral angle, tibial angle, femoral flexion angle, and tibial posterior slope angle between 2 groups ( P>0.05). No radiolucent line at the bone-implant interface was seen around the tibial components and femoral components in both groups. The patellar maltracking was observed in 3 patients of the trial group and 5 patients of the control group, showing no significant difference ( P=0.488). However, the incidence of patellar malposition in the trial group (18.8%) was significantly lower than that in the control group (35.5%) ( χ²=0.173, P=0.034).

Conclusion

Lateral retinacular release during primary TKA without resurfacing of the patella can reduce postoperative knee pain without increasing complications.

Safety and Efficacy of 6.2 mm Patellar Button in Resurfacing Less than 20 mm Thin Patella: A Matched Pair Analysis

Purpose

Restoring the native patellar thickness after patellar resurfacing provides optimal function of the knee after arthroplasty and minimises complications related to the patellofemoral articulation. The aim of this study was to assess the usefulness of a thin patellar button (6.2 mm) in patients with a patella thickness of less than 20 mm during total knee arthroplasty.

Materials and Methods

This is a retrospective case control study. A total of 54 female patients with an intraoperative patellar thickness of <20 mm, resurfaced with a patellar button of 6.2 mm in thickness were identified (group 1). They were matched with 54 patients with a patellar thickness of 20–23 mm, resurfaced with a patellar button of 8 mm (group 2), based on age, sex, body mass index, and deformity. A clinical and radiological evaluation was done at a minimum 2-year follow-up.

Results

The preoperative mean patellar thickness was 18.94±1.07 mm and was restored to 19.06±0.79 mm in group 1, as compared to 21.63±0.99 mm and 21.72±0.99 mm in group 2. The mean postoperative range of motion was 122.22°±9.25° in group 1 and 123.52°±8.72° in group 2 (p=0.13). No patellar bone or button related complications were observed in any patient in either group.

Conclusions

The 6.2 mm thin patella is useful to restore the native thickness in patients with a patellar thickness of less than 20 mm without risk of button fracture, loosening or overstuffing.

The prevalence of radiographic and MRI-defined patellofemoral osteoarthritis and structural pathology: a systematic review and meta-analysis

BACKGROUND

Patellofemoral osteoarthritis (PF OA) is more prevalent than previously thought and contributes to patient's suffering from knee OA. Synthesis of prevalence data can provide estimates of the burden of PF OA.

OBJECTIVE

This study aims to conduct a systematic review and meta-analysis on the prevalence of PF OA and structural damage based on radiography and MRI studies in different populations.

METHODS

We searched six electronic databases and reference lists of relevant cross-sectional and observational studies reporting the prevalence of PF OA. Two independent reviewers appraised methodological quality. Where possible, data were pooled using the following categories: radiography and MRI studies.

RESULTS

Eighty-five studies that reported the prevalence of patellofemoral OA and structural damage were included in this systematic review. Meta-analysis revealed a high prevalence of radiographic PF OA in knee pain or symptomatic knee OA (43%), radiographic knee OA or at risk of developing OA (48%) and radiographic and symptomatic knee OA (57%) cohorts. The MRI-defined structural PF damage in knee pain or symptomatic population was 32% and 52% based on bone marrow lesion and cartilage defect, respectively.

CONCLUSION

One half of people with knee pain or radiographic OA have patellofemoral involvement. Prevalence of MRI findings was high in symptomatic and asymptomatic population. These pooled data and the variability found can provide evidence for future research addressing risk factors and treatments for PF OA.

TRIAL REGISTRATION NUMBER

PROSPERO systematic review protocol (CRD42016035649).

EULAR recommendations for the use of imaging in the clinical management of peripheral joint osteoarthritis

The increased information provided by modern imaging has led to its more extensive use. Our aim was to develop evidence-based recommendations for the use of imaging in the clinical management of the most common arthropathy, osteoarthritis (OA). A task force (including rheumatologists, radiologists, methodologists, primary care doctors and patients) from nine countries defined 10 questions on the role of imaging in OA to support a systematic literature review (SLR). Joints of interest were the knee, hip, hand and foot; imaging modalities included conventional radiography (CR), MRI, ultrasonography, CT and nuclear medicine. PubMed and EMBASE were searched. The evidence was presented to the task force who subsequently developed the recommendations. The strength of agreement for each recommendation was assessed. 17 011 references were identified from which 390 studies were included in the SLR. Seven recommendations were produced, covering the lack of need for diagnostic imaging in patients with typical symptoms; the role of imaging in differential diagnosis; the lack of benefit in monitoring when no therapeutic modification is related, though consideration is required when unexpected clinical deterioration occurs; CR as the first-choice imaging modality; consideration of how to correctly acquire images and the role of imaging in guiding local injections. Recommendations for future research were also developed based on gaps in evidence, such as the use of imaging in identifying therapeutic targets, and demonstrating the added value of imaging. These evidence-based recommendations and related research agenda provide the basis for sensible use of imaging in routine clinical assessment of people with OA.

Patellar position in weight-bearing radiographs compared with non-weight-bearing: significance for the detection of osteoarthritis

Background Diagnosis and treatment of patellofemoral disorders including osteoarthritis are currently often based on imaging and clinical assessment with patients in the supine position. Purpose To evaluate differences in patellar position in the trochlear groove and to assess the detection of medial and lateral patellofemoral (PF) osteoarthritis (OA) on axial radiographs in supine and standing positions, respectively. Material and Methods Thirty-five women and 23 men (mean age, 56 years; age range, 18-87 years) referred for routine radiographic examinations of the knees were included. Axial radiographs of the PF joint in both supine non-weight-bearing and standing weight-bearing position in 30° knee flexion were obtained of 111 knees. Measurements performed on the radiographs: patellar tilt, patellar displacement, joint space width, and grade of OA according to Ahlbäck. Results From supine to standing position the patella moved medially and medial joint space width and lateral patellar tilt angle decreased ( P < 0.0001 for the three measured parameters). In the standing position, medial PF OA was observed in 19 knees compared to three knees in the supine position. Fourteen knees had lateral PF OA with almost unchanged grade of OA irrespective of position. Conclusion In weight-bearing positions, the patella is positioned medially in the trochlear groove compared to supine non-weight-bearing positions. Therefore, this study suggests that the common occurrence of medial PF OA can generally not be detected on axial radiographs in supine non-weight-bearing positions and confirms the importance of imaging the PF joint in standing weight-bearing positions.

The prevalence of patellofemoral osteoarthritis: a systematic review and meta-analysis

OBJECTIVE

To determine the prevalence of radiographic patellofemoral osteoarthritis (OA) from population- and symptom-based cohorts and to evaluate if knee pain, physical function and quality of life (QOL) differ between people with isolated patellofemoral OA, isolated tibiofemoral OA and combined patellofemoral and tibiofemoral OA.

METHOD

Terms associated with "patellofemoral OA", "prevalence" and "clinical features" were used to search Medline, EMBASE, CINAHL, SCOPUS, AMED and Web of Science databases with no language restriction' from inception to August 2014. Two independent reviewers screened papers for eligibility. Studies were included if they reported prevalence of compartmental patterns of radiographic knee OA in population- or symptom-based cohorts. Studies were excluded if they evaluated a targeted sample (e.g., occupation-specific participants) or repeated already reported data from the same cohorts. Point prevalence estimates of patellofemoral OA were extracted from eligible studies, pooled and quantitatively analysed. A critical appraisal tool was used to evaluate methodological quality.

RESULTS

The search yielded 1891 records. The inclusion criteria were met by 32 studies. The crude prevalence of patellofemoral OA was 25% in the population-based cohorts (aged >20 years) and 39% in the symptom-based cohorts (aged >30 years). Eight studies reported knee pain, physical function and QOL in people with different compartmental disease; however no significant differences were found.

CONCLUSION

These findings confirm the substantial prevalence of patellofemoral OA, demonstrating the need to specifically consider the patellofemoral joint in knee OA research and clinical settings.

Epidemiological characteristics of patellofemoral osteoarthritis in elderly Koreans and its symptomatic contribution in knee osteoarthritis

BACKGROUND

Many studies have reported the prevalence of knee osteoarthritis (OA) but have invariably focused on the tibiofemoral (TF) joint and overlooked the patellofemoral (PF) joint. Accordingly, little epidemiological information is available regarding the PF OA. The purpose of the current study was to document the epidemiological characteristics of PF OA in elderly Koreans.

METHODS

Radiographic assessment was performed for 681 elderly (≥65 years old) Koreans recruited from a community, and symptom severity was evaluated using Western Ontario and McMaster Universities Index (WOMAC) and Short Form-36 (SF-36) scales. Prevalence of different categories of knee OA (isolated PF OA, isolated TF OA and combined PF and TF OA) was calculated. The symptoms of isolated PF OA group and non-OA group were compared.

RESULTS

The overall prevalence of OA was 22.0% in the PF compartment and 34.1% in the TF compartment. The prevalence of isolated PF OA, isolated TF OA, and combined PF and TF OA was 3.8%, 17.8%, and 19.2%, respectively. Female sex, aging, and obesity were not associated with isolated PF OA. No significant differences were found in any clinical outcome scales between the isolated PF and non-OA groups.

CONCLUSION

This study documents that OA in the PF joint is common in elderly Koreans, but isolated PF OA is rare. Demographic risk factors are not associated with isolated PF OA, suggesting that isolated PF OA may have a different pathophysiology from other types of knee OA. Our study also indicates that the presence of isolated PF OA should not be construed to be responsible for clinical symptoms.

Radiographic grading of the patellofemoral joint is more accurate in skyline compared to lateral views

BACKGROUND

The patellofemoral joint is perhaps the most commonly involved compartment in knee osteoarthritis (OA). Radiographic studies are routinely ordered and are seen as the first-line investigations for patellofemoral osteoarthritis (PFOA). The Kellgren-Lawrence (K&L) grading scale is often used to quantify the severity of radiographic OA. In this study, we aim to determine the correlation of the K&L grading scale on both the skyline and lateral views with arthroscopic visualization of articular cartilage damage.

METHODS

All patients with clinical and radiographic features of PFOA who underwent knee arthroscopy by a single surgeon from 2006 to 2010 in our institution were reviewed. The study group consisted of 66 patients with PFOA. All patients had skyline and lateral radiographs of the knee taken before surgery. All patients had arthroscopic evidence of PFOA. Blinded investigators graded the radiographs according to the K&L grading scale. At arthroscopy, the patellofemoral joint was graded according to the Outerbridge classification. Correlation and statistical analysis of the radiographic and arthroscopic grade was carried out.

RESULTS

The general trend shows that the higher the radiographic K&L grading, the greater the severity of articular cartilage degeneration on arthroscopy. However, an increasing K&L grade accounts for only 39.7% and 28.4% of the variation of severity of arthroscopically-determined articular cartilage degeneration on skyline and lateral views respectively. Interestingly, on both views, better correlation with arthroscopic findings was seen in early (K&L grades 1 and 2) PFOA. Skyline views were superior to lateral views in terms of specificity, PPV, NPV and accuracy in predicting early OA.

CONCLUSIONS

Skyline radiographs are more accurate than lateral radiographs in prediction of severity of PFOA.

The diagnostic performance of anterior knee pain and activity-related pain in identifying knees with structural damage in the patellofemoral joint: the Multicenter Osteoarthritis Study

OBJECTIVE

To determine the diagnostic test performance of location of pain and activity-related pain in identifying knees with patellofemoral joint (PFJ) structural damage.

METHODS

The Multicenter Osteoarthritis Study is a US National Institutes of Health-funded cohort study of older adults with or at risk of knee osteoarthritis. Subjects identified painful areas around the knee on a knee pain map and the Western Ontario and McMaster Universities Osteoarthritis Index was used to assess pain with stairs and walking on level ground. Cartilage damage and bone marrow lesions were assessed from knee magnetic resonance imaging. We determined the sensitivity, specificity, positive and negative predictive values for presence of anterior knee pain (AKP), pain with stairs, absence of pain while walking on level ground, and combinations of tests in discriminating knees with isolated PFJ structural damage from those with isolated tibiofemoral joint (TFJ) or no structural damage. Knees with mixed PFJ/TFJ damage were removed from our analyses because of the inability to determine which compartment was causing pain.

RESULTS

There were 407 knees that met our inclusion criteria. "Any" AKP had a sensitivity of 60% and specificity of 53%; and if AKP was the only area of pain, the sensitivity dropped to 27% but specificity rose to 81%. Absence of moderate pain with walking on level ground had the greatest sensitivity (93%) but poor specificity (13%). The combination of "isolated" AKP and moderate pain with stairs had poor sensitivity (9%) but the greatest specificity (97%) of strategies tested.

CONCLUSION

Commonly used questions purported to identify knees with PFJ structural damage do not identify this condition with great accuracy.

Less anterior knee pain with a routine lateral release in total knee arthroplasty without patellar resurfacing: a prospective, randomized study

PURPOSE

Anterior knee pain is a major cause of complaint in total knee arthroplasty (TKA) without patellar resurfacing. The concept of improved patellar tracking and decreased retropatellar contact pressure for lateral retinacular release theoretically suggests that patients with lateral retinacular release in TKA would achieve a lower incidence of anterior knee pain when compared without lateral retinacular release. We sought to determine (1) whether those patients who received a routine lateral retinacular release in TKA would attain lower incidence of anterior knee pain as compared to patients who received TKA without lateral retinacular release and (2) whether lateral retinacular release would increase the lateral retinacular release-related complications.

METHODS

A total of 148 patients who underwent TKA with the use of the Gemini MK II mobile bearing were randomized to receive either routine lateral retinacular release (intervention group) or not (control group). Patients were assessed by the visual analogue scale for anterior knee pain, the Knee Society clinical scoring system of knee score and function score, and patellar score for clinical function. Patients' satisfaction and lateral retinacular release-related complications were also evaluated.

RESULTS

The overall incidence of anterior knee pain in the intervention group at 18 months follow-up was 5.6%, while that of the control group was 20.6% (p = 0.009). No statistical difference was detected between the two groups in terms of lateral retinacular release-related complications (n.s.), patients' satisfaction (n.s.), knee score (n.s.), function score (n.s.), and patellar score (n.s.) at 18 months follow-up.

CONCLUSION

The present study suggests that routine lateral retinacular release can reduce anterior knee pain and does not increase lateral retinacular release-related complications, in TKA with the use of the Gemini MK II mobile bearing without patellar resurfacing.

LEVEL OF EVIDENCE

Therapeutic, Level I.

Pre-radiographic osteoarthritic changes are highly prevalent in the medial patella and medial posterior femur in older persons: Framingham OA study

OBJECTIVE

To determine which subregions of the knee joint have a high prevalence of pre-radiographic osteoarthritic changes, i.e., cartilage damage and osteophytes that can only be detected by magnetic resonance imaging (MRI), in radiographically normal knees.

METHODS

Institutional Review Board approval and written informed consent from all participants was obtained. Data was collected from a community cohort in Framingham, MA, involving people aged 50-79. Participants underwent weight-bearing posteroanterior and lateral knee radiography with the fixed-flexion protocol, and 1.5 T MRI. Knees without radiographic osteoarthritis (Kellgren Lawrence grade 0 for the tibiofemoral joint and absence of any osteophytes or joint space narrowing in the patellofemoral joint) were included. The knee joint was divided into 14 subregions for cartilage and 16 subregions for osteophytes, and prevalence and severity of cartilage damage (grade 0-6) and osteophytes (grade 0-7) were semiquantitatively assessed using the Whole Organ Magnetic Resonance Imaging Score (WORMS).

RESULTS

The mean age of 696 participants was 62.3 ± 8.4 years, and the mean body mass index was 27.9 ± 5.1 kg/m2. Women comprised 55.2% of the study sample (384/696). Prevalence of cartilage damage (grade ≥2) was 47.7% (332/696) in the medial patellar and 29.9% (208/696) in patellar lateral (PL) subregions, and 24.0% (167/696) in femoral medial anterior (FMA) and 26.5% (184/696) in femoral medial central (FMC) subregions. Prevalence of osteophytes (grade ≥2) was highest at 60.8% (423/696) in the medial femoral posterior subregion, followed by 34.0% (237/696) in PL and 24.6% (171/696) in patellar medial (PM) subregions. For all other subregions, prevalence of these lesions was lower than the aforementioned percentages.

CONCLUSION

MRI-detected cartilage damage and osteophytes are highly prevalent in the medial patellofemoral and medial posterior tibiofemoral joints in radiographically normal knees in persons aged 50-79.

Minimum joint space width (mJSW) of patellofemoral joint on standing "skyline" radiographs: test-retest reproducibility and comparison with quantitative magnetic resonance imaging (qMRI)

OBJECTIVE

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).

MATERIALS AND METHODS

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.

RESULTS

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.

CONCLUSIONS

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.

Reliability of the jones patellofemoral osteoarthritis score for radiological assessment of patellofemoral degenerative changes: comparing a physiotherapist to doctors

PURPOSE

Radiological measurement scores are used by orthopaedic physiotherapists in triage and surveillance of patients with degenerative changes of the tibiofemoral and patellofemoral joints. The purpose of this study was to estimate the intra- and inter-observer reliability of a radiological measurement score to assess patellofemoral joint osteoarthritis, the Jones Patellofemoral Osteoarthritis Score (JPOS), with an orthopaedic physiotherapist and three grades of junior surgeons/doctors.

METHODS

A total of 390 skyline X-rays of the patellofemoral joint were reviewed on 2 occasions, 4 weeks apart, by an orthopaedic physiotherapist, 2 orthopaedic surgeons, and an orthopaedic doctor. Intra- and inter-observer reliability of the JPOS was calculated using a weighted kappa analysis.

RESULTS

The results indicated that while there was good overall intra-observer agreement for this measurement score for all assessors, inter-observer reliability was generally poor between the orthopaedic physiotherapist and the orthopaedic surgeons/doctor.

CONCLUSION

Our findings call into question the use of the JPOS by orthopaedic physiotherapists working in triage or orthopaedic surveillance programmes with other orthopaedic clinicians.

Pre-operative patellofemoral degenerative changes do not affect the outcome after medial Oxford unicompartmental knee replacement: a report from an independent centre

There has been debate about the role of unicompartmental knee replacement in the presence of radiologically identifiable degenerative changes of the patellofemoral joint. We studied 195 knees in 163 patients in whom an Oxford unicompartmental knee replacement had been performed for medial osteoarthritis between January 2004 and July 2007. The mean age of the patients was 66 years (51 to 93). The degree of degenerative change of the patellofemoral joint was assessed using Jones' criteria. Functional outcome was assessed at a mean of 3.4 years (2 to 7) post-operatively, using the Oxford knee score and the Short-form 12 score. Degenerative changes of the patellofemoral joint were seen pre-operatively in 125 knees (64%) on the skyline radiographs. There was no statistically significant difference in the Oxford knee or Short-form 12 scores between those patients who had patellofemoral osteoarthritis pre-operatively and those who did not (p = 0.22 and 0.54, respectively). These results support the opinion expressed at the designer's hospital that degenerative changes of the patellofemoral joint in isolation should not be considered to be a contraindication to medial Oxford unicompartmental knee replacement.

Radiographic assessment of the femorotibial joint of the CCLT rabbit experimental model of osteoarthritis

Background

The purposes of the study were to determine the relevance and validity of in vivo non-invasive radiographic assessment of the CCLT (Cranial Cruciate Ligament Transection) rabbit model of osteoarthritis (OA) and to estimate the pertinence, reliability and reproducibility of a radiographic OA (ROA) grading scale and associated radiographic atlas.

Methods

In vivo non-invasive extended non weight-bearing radiography of the rabbit femorotibial joint was standardized. Two hundred and fifty radiographs from control and CCLT rabbits up to five months after surgery were reviewed by three readers. They subsequently constructed an original semi-quantitative grading scale as well as an illustrative atlas of individual ROA feature for the medial compartment. To measure agreements, five readers independently scored the same radiographic sample using this atlas and three of them performed a second reading. To evaluate the pertinence of the ROA grading scale, ROA results were compared with gross examination in forty operated and ten control rabbits.

Results

Radiographic osteophytes of medial femoral condyles and medial tibial condyles were scored on a four point scale and dichotomously for osteophytes of medial fabella. Medial joint space width was scored as normal, reduced or absent. Each ROA features was well correlated with gross examination (p < 0.001). ICCs of each ROA features demonstrated excellent agreement between readers and within reading. Global ROA score gave the highest ICCs value for between (ICC 0.93; CI 0.90-0.96) and within (ICC ranged from 0.94 to 0.96) observer agreements. Among all individual ROA features, medial joint space width scoring gave the highest overall reliability and reproducibility and was correlated with both meniscal and cartilage macroscopic lesions (r_s = 0.68 and r_s = 0.58, p < 0.001 respectively). Radiographic osteophytes of the medial femoral condyle gave the lowest agreements while being well correlated with the macroscopic osteophytes (r_s = 0.64, p < 0.001).

Conclusion

Non-invasive in vivo radiography of the rabbit femorotibial joint is feasible, relevant and allows a reproducible grading of experimentally induced OA lesion. The radiographic grading scale and atlas presented could be used as a template for in vivo non invasive grading of ROA in preclinical studies and could allow future comparisons between studies.

Radiographic features predictive of patellar maltracking during total knee arthroplasty

Despite improvements in component design and surgical technique, some patients still require lateral retinacular release during TKA to improve patella tracking. We studied 148 fixed-bearing TKAs to identify parameters in pre-operative knee radiographs that would predict intraoperative patellar maltracking. Digital radiographs and software were used to measure coronal alignment, distal femoral valgus angle, proximal tibia varus angle, patellar tilt, patellar shift, Insall-Salvati ratio, and patellar component placement and alignment. Patellar tracking was assessed after all components had been cemented, using both no-touch and modified "towel clip" techniques. The only radiographic parameter independently associated with maltracking was patellar shift. The median pre-operative patellar lateral shift in patients who had maltracking was 4.1 mm compared to 0.0 mm in those who did not. Patients who had a patellar shift of more than 3.0 mm had a high likelihood of maltracking, with estimated positive and negative predictive values of 78 and 95%, respectively. Pre-operative patellar shift may thus be clinically relevant for identifying osteoarthritic patients who have a higher likelihood for patellar maltracking during TKA. Variations in the intrinsic risk for maltracking within patient study populations may account for the widely differing reported rates of patellar maltracking, and our data suggest that information on pre-operative patellar shift may be helpful in stratifying these sample populations.

Partial lateral patellar facetectomy for treatment of arthritis due to lateral patellar compression syndrome

PURPOSE

The purpose of this study was to investigate the intermediate-term results of a retrospective clinical trial designed to establish the value of lateral retinaculum release of the patella in conjunction with partial lateral patella facetectomy in patients with stage III or stage IV patellofemoral arthritis.

METHODS

Between October 1992 and January 2005, all patients undergoing arthroscopy, lateral patellar retinaculum release, and lateral patella facetectomy were evaluated. In total, 66 knees in 63 patients (89%) were available for evaluation at a mean of 60 months after the index surgery. Evaluations consisted of preoperative and postoperative questionnaires, physical examinations, and radiographs. The main outcome measure was the Kujala patellofemoral score.

RESULTS

For those patients not undergoing total knee arthroplasty before evaluation, the mean Kujala score was 45.6 preoperatively and 72.0 postoperatively (P < .001); subjectively, 56% of patients were very satisfied, 32% satisfied and would repeat the procedure, 5% were indifferent, and 7% were dissatisfied and would not repeat the procedure. Including all patients who underwent total knee arthroplasty before evaluation and those who would not repeat the procedure or were indifferent, our accumulative failure rate was 17%. Correlations of several measures with the Kujala score, as well as subgroup comparisons of several measures between patients who were satisfied and those who were not satisfied with their reconstructions, were performed. However, all of these failed to achieve statistical significance after adjustment for multiple comparisons and so are not reported in this report.

CONCLUSIONS

Lateral patella retinaculum release and partial lateral patella facetectomy for end-stage patellofemoral disease provides up to 5 years of symptomatic relief in over 80% of carefully selected patients who do not have significant arthritis (grade IV) in the medial or lateral knee compartments. Significant lateral facet patellofemoral arthritis (grade IV) even in association with medial facet and femoral sulcus involvement is not a contraindication to this surgical approach.

LEVEL OF EVIDENCE

Level IV, therapeutic case series.

Atlas of individual radiographic features in osteoarthritis, revised

OBJECTIVE

Develop a radiographic atlas of osteoarthritis (OA) to be used as a template and guide for grading radiographs of osteoarthritic lesions of the hand, hip and knee.

METHOD

The 1995 atlas was reviewed for the images most useful for clinical trials. Replacement images were selected from the Stanford University Radiology Department Picture Archive and Communications System by reviewing consecutive radiographs obtained from patients. Selected images were downloaded without patient identification information. Images were organized by hand, hip and knee. They were reviewed for findings of OA and images grouped into image files by individual findings and degree of change. Both investigators individually selected the most promising images. Final images were selected by consensus. Original electronic images were then cropped and placed in sequence.

RESULTS

Individual radiographic features (e.g., osteophytes, joint space narrowing) were recorded for hand (distal interphalangeal joint, proximal interphalangeal joint, trapeziometacarpal joint), hip (acetabular, femoral) and knee (medial compartment, lateral compartment, tibial, femoral); they were also sequenced for normal, 1+, 2+, and 3+ change. Images were made available in print and electronic formats.

CONCLUSION

An updated atlas of radiographic images was produced to assist in grading individual radiographic features of the hand, hip and knee for clinicians and for use in clinical trials.

Correlation between radiographic findings of osteoarthritis and arthroscopic findings of articular cartilage degeneration within the patellofemoral joint

OBJECTIVES

To correlate radiographic findings of osteoarthritis on axial knee radiographs with arthroscopic findings of articular cartilage degeneration within the patellofemoral joint in patients with chronic knee pain.

SUBJECTS AND METHODS

The study group consisted of 104 patients with osteoarthritis of the patellofemoral joint and 30 patients of similar age with no osteoarthritis of the patellofemoral joint. All patients in the study group had an axial radiograph of the knee performed prior to arthroscopic knee surgery. At the time of arthroscopy, each articular surface of the patellofemoral joint was graded using the Noyes classification system. Two radiologists retrospectively reviewed the knee radiographs to determine the presence of marginal osteophytes, joint-space narrowing, subchondral sclerosis, and subchondral cysts. The sensitivity and specificity of the various radiographic features of osteoarthritis for the detection of articular cartilage degeneration within the patellofemoral joint were determined.

RESULTS

The sensitivity of marginal osteophytes, joint-space narrowing, subchondral sclerosis, and subchondral cysts for the detection of articular cartilage degeneration within the patellofemoral joint was 73%, 37%, 4%, and 0% respectively. The specificity of marginal osteophytes, joint-space narrowing, subchondral sclerosis, and subchondral cysts for the detection of articular cartilage degeneration within the patellofemoral joint was 67%, 90%, 100%, and 100% respectively.

CONCLUSION

Marginal osteophytes were the most sensitive radiographic feature for the detection of articular cartilage degeneration within the patellofemoral joint. Joint-space narrowing, subchondral sclerosis, and subchondral cysts were insensitive radiographic features of osteoarthritis, and rarely occurred in the absence of associated osteophyte formation.

Prevalence, patterns, and risk factors of knee osteoarthritis in Thai monks

BACKGROUND

Patterns and risk factors of knee osteoarthritis in Asian countries where most people have habitual knee bending activities remain unclear. The objective of this study was to evaluate the prevalence, patterns, and risk factors of knee osteoarthritis in Thai monks.

METHODS

The study was a cross-sectional survey of monks who lived in temples in southern Thailand. Investigations included history, physical examination, and radiographic evaluation including weight-bearing antero-posterior, lateral, and skyline views.

RESULTS

There were 261 monks from 85 temples included in this study. The overall prevalence of radiographic knee osteoarthritis was 59.4%, with 29.6% having symptomatic radiographic knee osteoarthritis. The patterns of involvement were isolated tibiofemoral compartment (7.7%), isolated patellofemoral compartment (18.8%), and combined (32.9%). Obesity (OR 5.6, 95% CI; 1.6-19.8), age equal to or more than 60 years (OR 3.0, 95% CI; 1.5-6.0), and age at ordainment equal to or more than 46 years (OR 2.2, 95% CI; 1.1-4.6) were associated with risk of developing radiographic knee osteoarthritis. Obesity (OR 17.9, 95% CI; 2.4-132.1) and current smoking (OR 7.7, 95% CI; 2.4-24.3) were associated with symptomatic radiographic knee osteoarthritis. Severity of involvement was associated with obesity (OR 12.0, 95% CI; 2.3-60.9), older age (OR 3.8, 95% CI; 1.3-5.1), and older age at ordainment (OR 2.8, 95% CI; 1.3-6.1).

CONCLUSIONS

The prevalence of radiographic knee osteoarthritis with patellofemoral involvement in Thai monks is high and is more common among the elderly, those who were older at ordainment, and obese subgroups. Each pattern of knee osteoarthritis might have a different pathomechanism in the development of osteoarthritis.

The knee skyline radiograph: its usefulness in the diagnosis of patello-femoral osteoarthritis

The aim of this study was to determine the usefulness of the skyline radiograph in the diagnosis of patellofemoral osteoarthritis. Additionally, we wanted to assess the usefulness of patello-femoral crepitus as a clinical sign of this condition. Seventy-seven patients scheduled to undergo knee surgery had standard antero-posterior, lateral and skyline X-rays of their affected knee. The presence of clinical patello-femoral crepitus was also documented preoperatively. At the operation, their patellofemoral joints were graded into two groups according to the presence or absence of osteoarthritis. The lateral and skyline view X-rays as well as patello-femoral crepitus were compared individually against the operative findings. The skyline view had a sensitivity of 79% and a specificity of 80%. The lateral view had a sensitivity of 82% and specificity of 65%. Patello-femoral crepitus as a sign had a sensitivity of 89% and a specificity of 82%. There was no statistically significant difference between the two radiological views in terms of sensitivity and specificity in the diagnosis of patellofemoral osteoarthritis. Hence, we cannot recommend the skyline view as a routine radiological investigation in all cases of suspected patellofemoral osteoarthritis.

Evidence-based practice in the utilization of knee radiographs--a survey of all members of the British Orthopaedic Association

There has been a debate amongst orthopaedic surgeons about which plain radiographs are required in common knee conditions and this is a 5-year review assessing the influence of recent publications on the use of radiographs. A postal survey of all members of the British Orthopaedic Association was performed. The response rate was 60% (990/1,650). There was a broad agreement on the use of anteroposterior and lateral radiographs. The use of the posteroanterior (PA) weight-bearing radiograph has increased from 82 to 86%. The use of skyline view for suspected arthritis and after knee replacement has increased from 23 to 41%. There is still disparity amongst orthopaedic surgeons regarding the knee flexion angle for skyline and weight-bearing views. After review of the literature we recommend that a single skyline view in 30 degrees flexion is adequate and should be a standard investigation in knee disorders. We also stress the importance of weight-bearing PA radiograph in 30 degrees knee flexion for adequate assessment in all patients with suspected arthritis.

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

OBJECTIVES

Knee pain and disability in older people may occur in the apparent absence of radiographic osteoarthritis. However, the view chosen to define radiographic osteoarthritis may be critical. We have investigated the prevalence and compartmental distribution of radiographic osteoarthritis in people with knee pain using different combinations of three separate radiographic views.

METHODS

We performed a population-based study of 819 adults aged 50 yr and over with knee pain (part of the Clinical Assessment Study - Knee [CAS(K)]). Three radiographic views were obtained: weight-bearing posteroanterior (PA) semiflexed/metatarsophalangeal view; supine skyline; and supine lateral.

RESULTS

Complete data for all three views were available on 777 subjects. The distribution of compartmental radiographic osteoarthritis was 314 (40%) combined tibiofemoral/patellofemoral, 186 (24%) isolated patellofemoral, 31 (4%) isolated tibiofemoral and 246 (32%) normal. Hence, the overall prevalence of radiographic osteoarthritis was 531/777 (68.3%) in this symptomatic population. Using a PA view alone (reflecting tibiofemoral osteoarthritis only) would identify 56.7% of the 531, whilst the addition of a skyline or lateral view increased this to 87.0%. When using both skyline and lateral views in addition to the PA view, 98.7% cases of radiographic osteoarthritis were identified. In addition to prevalence, compartmental distribution altered markedly when different combinations of views were used.

CONCLUSIONS

Multiple views detect more radiographic osteoarthritis than single views alone. When different combinations of views are used, the prevalence and compartmental distribution of osteoarthritis changes and this may alter the accepted relationship, or lack of it, between symptoms and radiographic change.

Patellofemoral osteoarthritis coexistent with tibiofemoral osteoarthritis in a meniscectomy population

OBJECTIVES

To evaluate the frequency of patellofemoral osteoarthritis and its relevance to symptoms and function in a meniscectomy population.

METHODS

317 patients with no cruciate ligament injury were evaluated (mean (SD) age, 54 (11) years). They had undergone meniscal resection 15 to 22 years earlier (follow up rate 70%). Standing tibiofemoral and skyline patellofemoral radiographs were graded according to the OARSI atlas. The Knee Injury and Osteoarthritis Outcome Score (KOOS) was used to quantify symptoms and function. Controls were 68 unoperated subjects identified from national population records.

RESULTS

Patellofemoral osteoarthritis (isolated or coexisting with tibiofemoral osteoarthritis) was present in 66 of 317 index knees (21%) and 21 of 263 unoperated contralateral knees (8%, p<0.001). In 57/66 (86%) of these index knees, tibiofemoral osteoarthritis was present (mixed osteoarthritis). In a model adjusted for age, sex, and body mass index, the odds ratio for patellofemoral osteoarthritis (alone or in combination with tibiofemoral osteoarthritis) was 2.6 (95% confidence interval, 1.1 to 6.6) after medial meniscectomy and 5.3 (1.9 to 15.0) after lateral meniscectomy, using controls as the reference. Individuals with a mixed knee osteoarthritis pattern had more symptoms, lower function in sports and recreation, and worse knee related quality of life than subjects with isolated tibiofemoral osteoarthritis.

CONCLUSIONS

Mixed patellofemoral and tibiofemoral osteoarthritis is common in a meniscectomy population. Patellofemoral osteoarthritis is a contributing cause of knee symptoms and reduced knee related quality of life and is relevant to the management of knee complaints of this group of patients.

Osteoarthritis: symptoms, signs and source of pain

Osteoarthritis is the most common form of arthritis. The condition is characterised by loss or failure of the functional and/or biochemical integrity of the joint. The clinical symptoms include joint stiffness, pain and dysfunction, but the principal problem for the majority of patients is the pain. Although there are no pain receptors in the cartilage, the origin of the pain is thought to be due to stimulation of the A delta mechanoreceptors and the C polymodal nerve endings in the synovium and surrounding tissues. However, some of the pain experienced in and around the joints is referred pain or sympathetic efferent pain. In addition, there is a poor correlation of clinical symptoms with radiological or imaging appearance. This lack of correlation of clinical evaluation and imaging makes attempts at treatment difficult and compromises attempts to design studies and to evaluate the outcome of osteoarthritis in clinical trials.

Radiographic evaluation of osteoarthritis

Osteoarthritis is the most widespread form of arthritis in the United States. Classically, osteoarthritis has been grouped into primary and secondary types. Primary or idiopathic osteoarthritis is believed to be a sequela of altered biomechanical stresses across joints in susceptible individuals. Secondary osteoarthritis is a consequence of underlying cartilage damage, such as from preceding inflammatory arthritis, metabolic abnormality, or injury. The radiographic hallmark of osteoarthritis is asymmetric loss of cartilage space. Osteophytosis bony eburnation, subchondral cysts, and eventual subluxation follow. Osteoporosis and erosions are not usual features of this disease.

Provoked anterior knee pain in medial osteoarthritis of the knee

The incidence and the causes of provoked anterior knee pain in medial osteoarthritis (OA) of the knee were investigated clinically and radiographically. A retrospective study was performed in 179 primary osteoarthritic knees of 129 patients. Provocative tests were conducted on the patellofemoral (PF) joint to induce retropatellar crepitation, grating pain, tenderness around the patella, and pain on deviating the patella. The femorotibial angle (FTA) was measured on standing anteroposterior radiographs as a parameter of limb alignment. The widths of the medial and lateral joint space of the PF joint were measured on skyline views of standing or 30, 60 or 90 degrees knee flexion. The angle of flexion contracture was measured on lateral radiographs of knees with maximum extension. The lateral shift and tilt of the patella were measured on standing skyline views. Retropatellar crepitation was found in 70% of knees, while provoked anterior knee pain was observed in 35-45% of knees with medial OA of the knee. Standing FTA was significantly greater in knees with tenderness around the patella and pain on deviating the patella than in those without these symptoms (P<0.05). The angle of flexion contracture was significantly greater in knees with provoked symptoms in the PF joint than in those without symptoms (P<0.05). The degree of lateral shift was greater in knees with provoked symptoms (P<0.05). Flexion contracture and varus deformity of the knee with lateralization of the patella may be factors aggravating provoked PF symptoms in medial OA of the knee. The radiographic assessment in this series failed to show a significant relationship between the width of the PF joint space and the incidence of provoked PF symptoms.

Distribution of MR-detected cartilage defects of the patellofemoral joint in chronic knee pain

OBJECTIVES

The aim of the study was to detect cartilage defects and determine the center of these defects in MR imaging of the patellofemoral joint (PFJ) in middle-aged people with chronic knee pain.

DESIGN

In the format of a prospective study of early osteoarthritis (OA), this cross-sectional study of the signal knee (the most painful one at inclusion in the study in 1990) in 59 individuals, 30 women and 29 men (aged 41-58 years, mean 50 years) with chronic knee pain, with or without radiographically determined knee OA, was examined using MR imaging on a 1.0 T imager. Cartilage defects and the center of these defects in the PFJ were recorded.

RESULTS

Cartilage defects were found more often in the patella (40 knees) than in the femoral trochlea (23 knees) (P<0.001) and were unevenly distributed in the patella (P<0.001), with most cartilage defects in the mid-patella.

CONCLUSIONS

Since cartilage defects occur more commonly in the mid-patella, radiographs obtained with a knee flexion of approximately 45 degrees may be more accurate to show cartilage defects of early OA of the PFJ than views with another knee flexion.

The radiologic prevalence of patellofemoral osteoarthritis

The radiographs of 206 knees from 174 consecutive patients were reported blinded regarding joint space narrowing. Minimum joint space was measured using a millimeter ruler on weightbearing posteroanterior and skyline patellofemoral radiographs. Lateral radiographs were reported solely in terms of presence or absence of patellofemoral arthritis. The results showed objective joint space narrowing to less than 3 mm in the patellofemoral compartment of 32.7% of men and 36.1% of women older than 60 years. This high prevalence of patellofemoral disease in men has not been documented before. Arthritic changes occurred in the patellofemoral compartment in isolation in 13.6% of women and 15.4% of men older than 60 years. The lateral radiograph had poor results for detection of patellofemoral osteoarthritis with a sensitivity of 66% and specificity of 83%. The positive predictive value of an abnormal lateral radiograph was 52%. If requests for skyline radiographs had been confined to patients with abnormal patellofemoral joints as assessed on lateral films then 28 normal joints would have been imaged and 14 abnormal joints would have been missed. Osteoarthritis is more common in the patellofemoral joints of men and women than previously documented and only can be properly assessed using a skyline radiograph.

Long-term outcome after tibial shaft fracture: is malunion important?

BACKGROUND

Fractures of the shaft of the tibia often heal with some angulation. Although there is biomechanical evidence that such angulation alters load transmission through the joints of the lower limb, it is not clear whether it can eventually lead to osteoarthritis.

METHODS

One hundred and sixty-four individuals who had sustained a tibial shaft fracture were assessed in a research clinic thirty to forty-three years after the injury. The subjects were evaluated with regard to self-reported lower limb joint pain, stiffness, and disability (assessed with the Western Ontario and McMaster Universities [WOMAC] osteoarthritis questionnaire); clinical signs of osteoarthritis; and radiographic evidence of osteophytes and joint-space narrowing in the knees, ankles, and subtalar joints.

RESULTS

Twenty-two (15%) of the 151 subjects who reported no other knee injury reported at least moderate knee pain, and eight (6%) of the 145 subjects who reported no other ankle injury reported at least moderate ankle pain. Seventeen (13%) of the 135 subjects who reported no other knee or ankle injury reported at least moderate disability. The ipsilateral side demonstrated a higher prevalence than the contralateral side in terms of pain with passive ankle movement (nineteen versus nine subjects, p = 0.02), pain with passive subtalar movement (fifteen versus four subjects, p = 0.01), and radiographic signs of ankle joint space narrowing (twelve subjects versus one subject, p = 0.0055). Knee osteoarthritis was frequently bilateral. Forty-seven fractures (29%) healed with coronal angulation of > or = 5 degrees. Apart from an association between shortening of > or = 10 mm and self-reported knee pain (p = 0.016), there were no significant univariate associations between these malunions and the development of osteoarthritis. Seventeen (15%) of 114 eligible subjects had overall malalignment of the lower limb, defined as a hip-knee-ankle angle outside the normal range of 6.25 degrees of varus to 4.75 degrees of valgus. This malalignment was due to the fracture malunion in nine subjects and predated the fracture in eight. In limbs with varus or valgus malalignment, there was an excess of subtalar stiffness (p = 0.04) and a nonsignificant trend toward more frequent knee pain. In limbs with varus malalignment, there was a nonsignificant trend toward more frequent radiographic evidence of osteoarthritis in the medial compartment of the knee joint. Most of the subjects in whom osteoarthritis was observed had normal overall alignment of the lower limb.

CONCLUSIONS

The thirty-year outcome after a tibial shaft fracture is usually good, although mild osteoarthritis is common. Fracture malunion is not the cause of the higher prevalence of symptomatic ankle and subtalar osteoarthritis on the side of the fracture. Although varus malalignment of the lower limb occurs occasionally and may cause osteoarthritis in the medial compartment of the knee, other factors are more important in causing osteoarthritis after a tibial shaft fracture.

Changes in the canine femoropatellar joint space in the postsurgical, cruciate-deficient stifle joint

In this study, we investigate the factors that influence changes in articular cartilage thickness in naturally occurring osteoarthritis of the canine stifle joint. Fifty-eight dogs with QA secondary to cranial cruciate ligament deficiency were examined radiographically at 0, 7, and 13 months using 90 degree flexed mediolateral radiographs of both stifle joints. The femoropatellar joint space widths were measured using a computer-assisted video image analysis system. The femoropatellar joint space widths were found to be significantly increased in index joints as compared to contralateral joints. In addition, there was a significant increase in femoropatellar joint space (FPJS) width over the course of the study, particularly between entry and 7 months. Factors that might influence the degree of femoropatellar joint space increase (bodyweight, age, sex, disease duration, radiographic score) were investigated using regression analysis. Body weight at baseline showed a moderate to strong relationship with change in FPJS between 0 and 7 months (Pearson's partial correlation r = 0.417, p = .006). This relationship was less strong for change in femoropatellar joint space between 7 and 13 months (r = 0.324, p = .036).

Detecting radiographic knee osteoarthritis: what combination of views is optimal?

OBJECTIVE

The failure to image the patellofemoral joint or the posterior knee compartment when evaluating persons for knee osteoarthritis may result in missed cases. While the skyline view has been recommended due to more reproducible assessment of the patellofemoral joint space, the lateral view may be easier to acquire and provides different information. We evaluated the sensitivity of different combinations of X-ray views (anteroposterior and lateral; anteroposterior and skyline; all three views) in 377 persons with knee symptoms who had all three views available and had a definite osteophyte on at least one view.

RESULTS

Of the different views, skylines had to be excluded most often because the image of the patellofemoral joint was technically unsatisfactory. In the remaining knees, adding either a lateral or a skyline view to an anteroposterior view yielded roughly equal and high sensitivity (94-97%) when compared with the gold standard of a positive X-ray on any of the three views.

CONCLUSION

As long as at least an anteroposterior view and one image of the patellofemoral joint is obtained (either skyline or lateral), few cases with radiographic disease will be missed. For clinical or epidemiological studies the lateral view may be easier to acquire with high quality than the skyline view.

Saw tooth patello--femoral arthritis

Four patients with an unusual form of patello-femoral arthritis are described. The characteristic feature of the condition is an erosive 'saw tooth' pattern characteristically seen on both sides of the joint. Radiologically, this pattern is best seen on the skyline view. The other principal features are a lamellar-like pattern on slightly oblique lateral views, a smooth supra patellar erosion of the femur seen on the lateral view and cortical ridging of the lateral femoral condyle seen 'en face' on the AP projection. A possible mechanism to account for the radiological features is proposed. Anbarasu, A., Loughran, C. F. (2000). Clinical Radiology55, 767-769.

Development of a logically devised line drawing atlas for grading of knee osteoarthritis

OBJECTIVES

To (a) develop an atlas of line drawings for the assessment and grading of narrowing and osteophyte (that is, changes of osteoarthritis) on knee radiographs, and (b) compare the performance of this atlas with that of the standard Osteoarthritis Research Society (OARS) photographic atlas of radiographs.

METHODS

Normal joint space widths (grade 0) for the medial and lateral tibiofemoral and medial and lateral patellofemoral compartments were obtained from a previous community study. Grades 1-3 narrowing in each compartment was calculated separately for men and women, grade 3 being bone on bone, grades 1 and 2 being two thirds and one third the value of grade 0. Maximum osteophyte size (grade 3) for each of eight sites was determined from 715 bilateral knee x ray films obtained in a knee osteoarthritis (OA) hospital clinic; grades 1-2 were calculated as two thirds and one third reductions in the area of grade 3. Drawings for narrowing and osteophyte were presented separately. 50 sets of bilateral knee x ray radiographs (standing, extended anteroposterior; flexed skyline) showing a spectrum of OA grades were scored by three observers, twice using the OARS atlas and twice using the drawn atlas.

RESULTS

Intraobserver and interobserver reproducibility was similar and generally good with both atlases, though varied according to site. All three observers preferred the line drawing atlas for ease and convenience of use. Higher scores for patellofemoral narrowing and lower scores for osteophyte, especially medial femoral osteophyte, were seen using the line drawing atlas, showing that the two atlases are not equivalent instruments.

CONCLUSION

A logically derived line drawing atlas for grading of narrowing and osteophyte at the knee has been produced. The atlas showed comparable reproducibility with the OARS atlas, but was discordant in several aspects of grading. Such a system has several theoretical and practical advantages and should be considered for use in knee OA studies.

Radiographic assessment of symptomatic knee osteoarthritis in the community: definitions and normal joint space

OBJECTIVE

To evaluate radiographic features of osteoarthritis (OA) to determine which is more closely associated with knee pain and hence might be used as a radiographic definition of OA in the community. To evaluate joint space width in normal subjects.

METHODS

452 subjects from a case-control community study of knee pain (294 women, 158 men, mean age 62 years, range 40-80) underwent AP standing and midflexion skyline radiographs. Joint space width, measured by metered calliper to 0.1 mm, and graded individual features of OA (osteophyte 0-3, narrowing 0-3, sclerosis 0-1, cysts 0-1) were assessed in all three compartments independently by two observers who were blind to clinical status. Subjects were categorised as having knee pain by a positive response to both parts of the question "Have you ever had pain in or around the knee on most days for at least a month? If so, have you experienced any pain during the last year?"

RESULTS

Intraobserver reproducibility for joint space width measurements was to within +/- 0.4 mm (95% CI for limits of agreement); kappa values for grading were > 0.7. One hundred and twenty five subjects were without knee pain or osteophyte. In these radiographically normal knees, mean joint space width varied according to sex but did not decrease with age. A definition based on the presence of osteophyte > or = grade 1 in any compartment was more efficient at predicting pain than definitions based on either measurement or grading of joint space; there was no clear threshold of joint space loss at which the likelihood of pain substantially increased. The presence of osteophyte at the patellofemoral joint (PFJ) was more sensitive but less specific than at the tibiofemoral joint (TFJ); the addition of PFJ assessment improved sensitivity from 38.1% to 62.3% with a reduction in specificity from 82.7% to 58.7% for the presence of knee pain.

CONCLUSION

Among men and women in the community, osteophyte is the radiographic feature that associates best with knee pain. Radiographic assessment of both TFJ and PFJ should be included in all community studies. Joint space loss is not a feature of asymptomatic aging, and there is not a biological cut off for joint space width below which the likelihood of knee pain markedly increases.

Correlation between radiographically diagnosed osteophytes and magnetic resonance detected cartilage defects in the patellofemoral joint

OBJECTIVE

To assess the correlation between radiographically diagnosed osteophytes in the axial and lateral view of the patellofemoral joint (PFJ) and (1) magnetic resonance (MR) detected cartilage defects in the same joint and (2) knee pain.

METHODS

Fifty-seven people with chronic knee pain, (aged 41-58 years, mean 50 years) were examined with axial and lateral radiograms when standing of the right and the left PFJ. The presence and grade of osteophytes was assessed. On the same day, a MR examination was performed of the signal knee with proton density and T2 weighted turbo spin-echo sequences in the sagittal and axial view on a 1.0 T imager. Cartilage defects in the PFJ were noted. The subjects were questioned for current knee pain for each knee.

RESULTS

Osteophytes at the PFJ had a specificity varying between 59 and 100% and a positive predictive value between 74 and 100% for MR detected cartilage defects. The corresponding values for osteophytes at the lateral aspect of the femoral trochlea were both 100%. In PFJ with narrowing (< 5 mm) osteophytes had a sensitivity and a positive predictive value of 90 and 95% respectively for MR detected cartilage defects, while in PFJ with non-narrowing (> or = 5 mm) the corresponding values were 75 and 65% and the specificity was 50%. A correlation (p < 0.05) between osteophytes at the inferior pole of the patella and knee pain was found.

CONCLUSIONS

Osteophytes at the PFJ are associated with MR detected cartilage defects in the same joint. The relation was strong for osteophytes at the lateral femoral trochlea and in the PFJ with narrowing (< 5 mm), but weak in the PFJ with non-narrowing (> or = 5 mm).

Assessing progression of patellofemoral osteoarthritis: a comparison between two radiographic methods

OBJECTIVE

To compare two plain radiographic methods for sensitivity to detect progression of patellofemoral osteoarthritis.

METHODS

Two sets of paired skyline and lateral knee radiographs from 54 hospital referred patients (108 knees) with knee osteoarthritis were taken an average of 31 months apart (range 12-40). Films were examined separately in random order by a single observer blind to patient identity and time order. Minimum joint space was measured by metered caliper; individual features of osteoarthritis were graded 0-3 using an atlas.

RESULTS

Intraobserver reproducibility assessed on 40 knees was to within +/- 0.5 mm for skyline lateral facet and +/- 0.7 mm for medial facet and lateral views. On the lateral view measured joint space decreased in 51% of knees but increased in 43%, with overall no significant mean group change with time (-0.2 mm, 95% confidence interval, 0.1 to -0.5). By contrast on the skyline view joint space decreased in at least one facet in 71% of knees, with significant decrease in mean joint space for both lateral facets (-0.4 mm, 95% CI, -0.2 to -0.6) and medial facets (-0.5 mm, 95% CI, -0.1 to -0.8).

CONCLUSIONS

It is possible to detect significant joint space loss with time on the skyline view that is not apparent on the lateral view. The skyline view should be the method of choice to detect progression of patellofemoral osteoarthritis.