Subluxation of the patella: evaluation of patellar articular cartilage with MR imaging

Magnetic resonance imaging is able to detect patellofemoral focal cartilage injuries: a systematic review with meta-analysis

PURPOSE

The purpose of this study was to analyze the diagnostic accuracy of magnetic resonance imaging (MRI) to detect and grade the severity of patellofemoral (PF) cartilage injuries.

METHODS

A systematic review was conducted on PubMed, EMBASE and Cochrane Library databases (up to July 1st 2022) to search for studies that reported the diagnostic accuracy of MRI to detect and grade PF cartilage injuries as compared to diagnostic arthroscopy. Risk of bias was judged using the QUADAS-2 tool. Quantitative syntheses were performed to calculate the diagnostic accuracy metric-sensitivity, specificity, positive likelihood (LR+) and negative likelihood (LR-) ratios, diagnostic odds ratio (DOR)-and presented as median with 25% and 75% percentiles. The summary receiver operating characteristic (SROC) curves were also calculated. Diagnostic accuracy metrics were calculated for all PF cartilage injuries and then sub-grouped by patellar and trochlear lesions. Diagnostic accuracy was also calculated according to the grading of cartilage injuries.

RESULTS

Forty-five studies were included for qualitative analyses and forty studies were included for quantitative synthesis. A total of 3534 participants with a weighted mean age of 38.1 years were included. Diagnostic accuracy was generally high: sensitivity (0.8, 0.6-1.0), specificity (0.9, 0.8-1.0), LR+ (6.4, 3.1-15.3), LR- (0.3, 0.2-0.4) and DOR (21.3, 9.9-121.1). The area under the curve (AUC) of the SROC was 0.9. The diagnostic accuracy was slightly higher for patellar (sensitivity 0.8, specificity 0.8, LR+ 5.3, LR- 0.2, DOR 28.8) than for trochlear lesions (sensitivity 0.7, specificity 0.9, LR+ 5.5, LR- 0.4, DOR 14.3). The sensitivity was generally higher when grading advanced (vs. early or intermediate) cartilage injuries of the patella.

CONCLUSION

The MRI is able to diagnose PF cartilage injuries with reasonably high diagnostic accuracy (as compared to arthroscopy). Clinicians can rely on MRI to reliably diagnose PF cartilage injuries (with some limitations) which will play an important role in deciding for surgical or non-operative treatment.

LEVEL OF EVIDENCE

Level III.

Congenital dislocation of the patella - clinical case

Congenital patellar dislocation is a rare condition in which the patella is permanently dislocated and cannot be reduced manually. The patella develops normally as a sesamoid bone of the femur. This congenital dislocation results from failure of the internal rotation of the myotome that forms the femur, quadriceps muscle and extensor apparatus. It usually manifests immediately after birth, although in some rare cases, the diagnosis may be delayed until adolescence or adulthood. Early diagnosis is important, thereby allowing surgical correction and avoiding late sequelae, including early degenerative changes in the knee. A case of permanent dislocation of the patella is presented here, in a female child aged seven years.

The clinical utility and diagnostic performance of magnetic resonance imaging for identification of early and advanced knee osteoarthritis: a systematic review

BACKGROUND

Current diagnostic strategies for detection of structural articular cartilage abnormalities, the earliest structural signs of osteoarthritis, often do not capture the condition until it is too far advanced for the most potential benefit of noninvasive interventions.

PURPOSE

To systematically review the literature relative to the following questions: (1) Is magnetic resonance imaging (MRI) a valid, sensitive, specific, accurate, and reliable instrument to identify knee articular cartilage abnormalities compared with arthroscopy? (2) Is MRI a sensitive tool that can be utilized to identify early cartilage degeneration?

STUDY DESIGN

Systematic review.

METHODS

A systematic search was performed in November 2010 using PubMed MEDLINE (from 1966), CINAHL (from 1982), SPORTDiscus (from 1985), SCOPUS (from 1996), and EMBASE (from 1974) databases.

RESULTS

Fourteen level I and 13 level II studies were identified that met inclusion criteria and provided information related to diagnostic performance of MRI compared with arthroscopic evaluation. The diagnostic performance of MRI demonstrated a large range of sensitivities, specificities, and accuracies. The sensitivity for identifying articular cartilage abnormalities in the knee joint was reported between 26% and 96%. Specificity and accuracy were reported between 50% and 100% and between 49% and 94%, respectively. The sensitivity, specificity, and accuracy for identifying early osteoarthritis were reported between 0% and 86%, 48% and 95%, and 5% and 94%, respectively. As a result of inconsistencies between imaging techniques and methodological shortcomings of many of the studies, a meta-analysis was not performed, and it was difficult to fully synthesize the information to state firm conclusions about the diagnostic performance of MRI.

CONCLUSION

There is evidence in some MRI protocols that MRI is a relatively valid, sensitive, specific, accurate, and reliable clinical tool for identifying articular cartilage degeneration. Because of heterogeneity of MRI sequences, it is not possible to make definitive conclusions regarding its global clinical utility for guiding diagnosis and treatment strategies.

CLINICAL RELEVANCE

Traumatic sports injuries to the knee may be significant precursor events to early onset of posttraumatic osteoarthritis. Magnetic resonance imaging may aid in early identification of structural injuries to articular cartilage as evidenced by articular cartilage degeneration grading.

Bone bruise in acute traumatic patellar dislocation: volumetric magnetic resonance imaging analysis with follow-up mean of 12 months

OBJECTIVE

The aim of the study was to assess volumetric analysis of bone bruises in acute primary traumatic patellar dislocation by magnetic resonance imaging (MRI) and resolving resolution of bruises in follow-up MRI.

MATERIALS AND METHODS

MRI was performed in 23 cases. A follow-up examination was done at a mean of 12 months after dislocation. Volumes of patellar and femur bruises for every patient were evaluated separately by two musculoskeletal radiologists, and mean values of the bruises were assessed. Other MRI findings were evaluated, together with agreement by consensus. Bone bruise volumes were compared with other MR findings.

RESULTS

In the acute study 100% of patients showed bruising of the lateral femoral condyle and 96% bruising of the patella. The bruise was located at the medial femoral condyle in 30% and at the patellar median ridge in 74% of patients. The median volume of the femoral bruise was 25,831 mm(3) and of the patellar bruise 2,832 mm(3). At the follow-up study 22% of patients showed bruising of the lateral femoral condyle and 39% bruising of the patella, the median volumes of the bruises being 5,062 mm(3) and 1,380 mm(3), respectively. Larger patellar bruise volume correlated with larger femur bruise volume in the acute (r = 0.389, P = 0.074) and the follow-up (r = 1.000, P < 0.01) studies. Other MRI findings did not correlate significantly with bone bruise volumes.

CONCLUSION

Bone bruising is the commonest finding in cases of acute patellar dislocation, being seen even 1 year after trauma and indicating significant bone trabecular injury in the patellofemoral joint. A large bruise volume may be associated with subsequent chondral lesion progression at the patella. We concluded that the measurement of bone bruise volume in patients with acute patellar dislocation is a reproducible method but requires further studies to evaluate its clinical use.

Overuse injuries of the knee

Overuse injuries are a common cause of morbidity in athletes. They occur after repetitive microtrauma, abnormal joint alignment, and poor training technique without appropriate time to heal. Overuse injuries are frequent in the knee joint because of the numerous attachment sites for lower limb musculature and tendons surrounding the joint. MR imaging is regarded as the noninvasive technique of choice for detection of internal derangements of the knee. This article describes the characteristic findings on MR of the common overuse injuries in the knee, including patellar tendinopathy, iliotibial band syndrome, cartilage disorders, medial plica syndrome, and bursitis.

[Imaging examinations of the patellofemoral joint]

Lesions in the patellofemoral region can be caused by trauma, chronic overloading, and especially regarding cartilage alterations by normal aging or pathologic processes. Very commonly these lesions lead to early arthrosis. An accurate clinical evaluation in all these patients is recommended. The combination of clinical information and radiological examinations should end up with an exact diagnosis.As part of the radiological evaluation of complaints of the patellofemoral region MR imaging is of special value since this method allows direct visualization of all intra- and extra-articular structures and their alterations, ultimately aiding in planning sufficient therapy. Moreover, is it possible to exclude pathology by MR imaging, which helps to prevent useless treatment and surgical procedures.

Arthroscopic estimation of the extent of chondropathy

INTRODUCTION

Arthroscopy has been used to evaluate articular cartilage (AC) pathology in osteoarthritis (OA) for outcome measurement and validation of non-invasive imaging. However, many fundamental aspects of arthroscopic assessment remain un-validated.

OBJECTIVES

This study evaluated arthroscopic estimates of extent of chondropathy.

METHODS

Serial arthroscopic assessments were performed in a group of 15 sheep before and after bilateral stifle medial meniscectomy (MMx). Post-mortem assessments were performed in un-MMx sheep and 4 and 16 weeks post-MMx. Arthroscopic assessments of the extent of each grade of chondropathy were compared with a non-arthroscopic hybrid assessment that incorporated biomechanical, thickness and macroscopic assessments.

RESULTS

Arthroscopy evaluated only 36% of AC and missed significant pathological changes, softening and chondro-osteophyte, occurring in peripheral regions. The patterns of change in arthroscopic assessments were similar to those of the non-arthroscopic assessment but there was a very strong tendency to over-estimate the extent of softened AC after MMx. In spite of these limitations arthroscopic assessments were responsive to change. Estimates of the extent of normal and softened AC were most responsive to change over time followed by estimates of superficial and deep fibrillation. Arthroscopy was as an excellent discriminator between normal and OA. Assessments of chondro-osteophyte and exposed bone were not responsive to change.

CONCLUSIONS

Arthroscopic estimates of extent of chondropathy are prone to substantial error. While experience and training may reduce these errors other approaches may more effectively improve performance.

Increase in bone marrow lesions associated with cartilage loss: A longitudinal magnetic resonance imaging study of knee osteoarthritis

OBJECTIVE

Although bone marrow lesions (BMLs) are powerful predictors of joint space loss as visualized on radiographs, the natural history of these lesions, their relationship to cartilage loss, and the association between change in these lesions and cartilage loss are unknown. These questions were tested using longitudinal magnetic resonance imaging (MRI) data in a natural history study of symptomatic knee osteoarthritis (OA).

METHODS

MRI of the knee was performed at baseline, 15 months, and 30 months in 217 patients with primary knee OA (122 men, 95 women; mean +/- SD age 66.4 +/- 9.4 years). To assess mechanical alignment, long-limb films were obtained at 15 months. Subchondral bone marrow abnormalities, graded in the medial and lateral tibiofemoral joints, were defined as poorly marginated areas of increased signal intensity in the marrow on fat-suppressed, T2-weighted images. Cartilage morphologic features in the medial and lateral tibiofemoral joints were scored at all time points using a semiquantitative scale. For each of the medial and lateral compartments, generalized estimating equations were used to evaluate the longitudinal relationship of tibiofemoral BMLs to the tibiofemoral cartilage score, with adjustment for malalignment.

RESULTS

Fifty-seven percent of knees had BMLs at baseline, of which 99% remained the same or increased in size at followup. Knee compartments with a higher baseline BML score had greater cartilage loss. An increase in BMLs was strongly associated with further worsening of the cartilage score. Enlarging or new BMLs occurred mostly in malaligned limbs, on the side of the malalignment (e.g., new medial BMLs in varus-aligned knees). The association of BML change with medial tibiofemoral cartilage loss was not significant after adjusting for alignment.

CONCLUSION

Lesions of the bone marrow are unlikely to resolve and often get larger over time. Compared with BMLs that stay the same, enlarging BMLs are strongly associated with more cartilage loss. Furthermore, any change in BML is mediated by limb alignment.

Congenital dislocation of the patella

OBJECTIVE

Our objective was to present the imaging findings for congenital dislocation of the patella, an uncommon condition with variable clinical manifestations in patients of different ages.

CONCLUSION

Sonography can clearly illustrate the presence and location of the laterally displaced patella and the anatomy of adjacent joint structures. The high resolution for soft-tissue, cartilaginous, and bony structures of the immature skeleton makes sonography a valuable tool in the management of congenital dislocation of the patella. Conventional radiography is a simple method for diagnosis once ossification of the patella has commenced and for postoperative follow-up. MRI allows visualization of fine anatomic details and relationships between the involved structures of the extensor mechanism and is the technique of choice for preoperative planning.

A critical appraisal of quantitative arthroscopy as an outcome measure in osteoarthritis of the knee

BACKGROUND AND OBJECTIVES

To review the performance of arthroscopic assessment of articular cartilage damage in osteoarthritis.

METHODS

The literature was reviewed for publications containing data regarding validity and reliability of arthroscopic systems of cartilage evaluation in knee osteoarthritis.

RESULTS

Fifty-two distinct measurement systems were identified in 60 publications. There were 30 simple severity-scoring systems, 3 global visual analogue scale systems, and 19 composite systems. No systems consisted solely of measurements of lesion size or site, although 13 systems used either or both of these for the calculation of composite scores. Only 6 publications (10%) undertook any reliability evaluation and these generally used inappropriate methods of statistical analysis. Thirty-five publications (58%) evaluated validity. Construct validity was tested using several constructs (clinical in 2, magnetic resonance imaging in 10, radiographs in 10, or other arthroscopic assessments in 5 publications). Criterion validity was ascertained by using several methods including cartilage histology, histochemistry, or biomechanics in 10 publications. Responsiveness was determined in 1 publication.

DISCUSSION

Many publications evaluated composite systems but only a few evaluated fundamental aspects of arthroscopic measurement. Conceptually, composite scoring systems have the best validity; however, at present, there is only enough evidence to support the use of simple chondropathy severity scores and there are little data on the responsiveness of these methods. A proposed program for comprehensive evaluation and development of valid and responsive arthroscopic assessments of articular cartilage is outlined.

MR imaging of patellar dislocation and relocation

Patellar dislocation and relocation (PDR) typically occurs suddenly after trauma or torsional stress on the extensor mechanism. Clinical evaluation after patellar dislocation/relocation usually reveals a swollen knee that is difficult to examine. Radiographs may show hemathroses and a minority of patients will have a chip fracture of the patella. Magnetic resonance (MR) imaging features seen with PDR include disruption or sprain of the medial retinaculum, lateral patellar tilt or subluxation, lateral femoral condylar and medical patellar osseous contusions, osteochondral injury, damage to Hoffa's fat pad, and joint effusion. Up to one third of patients will also show concomitant injury to the major ligaments of the knee or menisci. Without repair of the primary injury, redislocation occurs in greater than one half of patients. Consequently, surgical correction is often advocated. This article reviews the factors predisposing to PDR, the activities associated with PDR, the clinical, radiographic, and MR imaging features of PDR, and (briefly) therapy for this injury.

Patellofemoral malalignment

Anterior knee pain represents one of the most common musculoskeletal complaints of adolescents. It is a disorder in which there is broad clinical experience and yet it represents a difficult and frustrating entity for the athlete to endure and for the physician to treat. An appropriate clinical examination and selected diagnostic studies can define the diagnosis and the introduction of conservative therapy usually will correct the problem. Occasionally, surgical intervention is required, and debate remains as to the optimal techniques that should be used.

MR evaluation of mediopatellar plica

PURPOSE

Evaluation of the usefulness of MR imaging for diagnosing mediopatellar plica (MP) of the knee joint.

MATERIAL AND METHODS

We prospectively examined MR images of 40 knee joints in 30 patients with symptoms. The pulse sequences were SE T1-weighted images (600/26 ms), T2-weighted images (1800/70), and FLASH images (320/15/flip angle 90 degrees). When a low-intensity band was found above the medial condyle of the femur on T1-weighted and T2-weighted MR images, we defined it as MP. We compared these MR findings with arthroscopic findings, including the SAKAKIBARA classification of MP.

RESULTS

In 29 of the 40 knee joints in which MP was arthroscopically found, 27 were correctly diagnosed as having MP on MR. In the remaining 11 without MP, 9 were correctly diagnosed by MR.

CONCLUSION

MR images are useful not only for detecting MP but also for evaluating its extension. Our results suggest that MR imaging is useful as a screening method for detecting MP before arthroscopy.

Comparison between magnetic resonance imaging and arthroscopy in the diagnosis of patellar cartilage lesions: a prospective study

A blind and prospective study was conducted to assess the accuracy of magnetic resonance imaging (MRI) for diagnosing patellar cartilage lesions. Thirty-three consecutive patients undergoing knee arthroscopy were examined by MRI prior to surgery. Imaging was performed in the axial plane on a 1.5-Tesla unit with spin-echo and gradient-echo T1 and T2 sequences. The MRI and arthroscopic data were compared using a four-grade classification and a patellar map which divided the patellar surface into four quadrants. The overall sensitivity of MRI was 84.7% and the specificity 97.2%. The same pit-fall led to two MRI false positives. A perfect correlation of grading was obtained in 76.5%. When discordance was found, the tendency with MRI was commonly to underestimate the grade of the lesions. The MRI accuracy was high in this study in spite of a high rate of low-grade lesions which are difficult to assess. Related criteria for cartilage assessment with MRI and arthroscopy are suggested for further studies.

The morphology of articular cartilage assessed by magnetic resonance imaging (MRI). Reproducibility and anatomical correlation

Quantitative assessment of cartilage volume and thickness in a formalin-alcohol fixed specimen of a human patella was conducted with magnetic resonance imaging (MRI), as it is still unclear whether the morphology of normal and damaged cartilage can be accurately demonstrated with this technique. MR imaging was carried out at 1.0 T (section thickness 2 mm, in-plane-resolution 0.39-0.58 mm) with the following pulse sequences: 1) T1-weighted spin-echo, 2) 3D-MPRAGE, 3) 3D-FISP, 4) 3D-MTC-FISP, 5) 3D-DESS, 6) 3D-FLASH. Following imaging, the patella was sectioned perpendicular to the articular surface at intervals of 2 mm with a diamond band-saw. The volume of its cartilage was determined from the anatomical sections and the MR images, using a Vidas IPS 10 image analysing system (Kontron). Measurements were carried out with and without the low-signal layer in the transitional zone between the articular cartilage and the subchondral bone. If the low-signal layer was included, the volume was overestimated with MRI by 16 to 19%. Without the low-signal layer the volumes were less than those determined from the anatomical sections: T1-SE-18.2%, MPRAGE -22.6%, FISP -17.1%, MTC-FISP -9.5%, DESS -9.3% and FLASH -6.1%. The coefficient of variation for a 6-fold determination of the volume amounted to between 6.2% (T1-SE) and 2.6% (FLASH). The FLASH sequence allowed the most valid and reproducible assessment of the cartilage morphology. The remaining difference from the real volume of the cartilage may be due to the fact that the calcified zone of the cartilage is not delineated by MRI.

The diagnostic value and limitation of magnetic resonance imaging on chondral lesions in the knee joint

Chondral lesions of the knee joint, which have been detected via arthrotomy or arthroscopy, were examined prospectively and retrospectively through a review of previously obtained magnetic resonance images (MRIs). The study group was composed of 34 men and 29 women whose average age was 24.6 years. Of these 63 patients, there were 72 articular cartilage lesions in 65 knees. On retrospective analysis, the sensitivity of MRI, which was defined as a true positive reading for softening, fragmentation, erosion, and/or a full-thickness loss of cartilage, was 14.3%, 57.3%, 75.0%, and 100%, respectively. Although the sensitivity to early changes of chondral lesions was low, indicating the limitation of MRI at the present stage, it has been demonstrated that MRI can delineate intracartilaginous changes associated with softening and thickening of cartilage that cannot be detected even with arthroscopy. Therefore, it may be worthwhile to perform an MRI as well as arthroscopy to clarify the pathogenesis of internal derangement of the knee.