[Indirect MR-arthrography in the follow up of autologous osteochondral transplantation]

Value of Edema-like Marrow Signal Intensity in Diagnosis of Joint Pain: Radiologists' Perspective

Musculoskeletal pain is a significant contributor to disability. The mechanism and target of the treatment should be optimized by imaging, but currently no accepted gold standard exists to image pain. In addition to end-organ pathology, other mediators also contribute to nociception, such as angiogenesis, axonal extension, immunologic modulation, and central sensitization. Recent research indicates that local inflammation is a significant contributor to pain in the extremities; therefore, we focus here on edema-like marrow signal intensity (ELMSI). We examine both the relevance of ELMSI for pain and novel imaging techniques.

Autologous Osteochondral Transplantation for Osteochondral Lesions of the Talus

BACKGROUND

Autologous osteochondral transplantation (AOT) is used to treat osteochondral lesions (OCLs) of the talus, typically reserved for lesions greater than 150 mm(2). Few studies exist examining the functional and magnetic resonance imaging (MRI) outcomes following this procedure. The purpose of this study was to investigate functional and MRI outcomes, including quantitative T2 mapping following AOT.

METHODS

Eighty-five consecutive patients who underwent AOT were identified. Functional outcomes were assessed pre- and postoperatively using the Foot and Ankle Outcome Score (FAOS). The Magnetic Resonance Observation of Cartilage Repair Tissue (MOCART) score was used to assess cartilage incorporation. Quantitative T2 MRI relaxation time of graft tissue and adjacent normal cartilage values were recorded in a subset of 61 patients. The mean clinical follow-up was 47.2 months, with mean MRI follow-up of 24.8 months.

RESULTS

Mean FAOS improved pre- to postoperatively from 50 to 81 (P < .001). The mean MOCART score was 85.8. Lesion size was negatively correlated with MOCART score (r = -0.36, P = .004). Superficial T2 values in graft tissue were higher than control tissue (42.0 vs 35.8, P < .001). Deep T2 values in graft tissue were similar to the control values (30.9 vs 30.0, P = .305). Functional outcomes were similar in patients irrespective of whether they had previous microfracture or concomitant procedures.

CONCLUSION

AOT was an effective treatment for large OCLs of the talus in the current study. MOCART scoring indicated good structural integrity of the graft. Quantitative T2 mapping suggests that graft tissue may not always mirror native hyaline cartilage. The long-term implications of this are not yet known.

LEVEL OF EVIDENCE

Level IV, case series.

Morphological MRI and T2 mapping of cartilage repair tissue after mosaicplasty with tissue-engineered cartilage in a pig model

The aim of this study was to evaluate the efficacy of mosaicplasty with tissue-engineered cartilage for the treatment of osteochondral defects in a pig model with advanced MR technique. Eight adolescent miniature pigs were used. The right knee underwent mosaicplasty with tissue-engineered cartilage for treatment of focal osteochondral defects, while the left knee was repaired via single mosaicplasty as controls. At 6, 12, 18 and 26 weeks after surgery, repair tissue was evaluated by magnetic resonance imaging (MRI) with the cartilage repair tissue (MOCART) scoring system and T2 mapping. Then, the results of MRI for 26 weeks were compared with findings of macroscopic and histologic studies. The MOCART scores showed that the repaired tissue of the tissue-engineered cartilage group was statistically better than that of controls (P < 0.001). A significant correlation was found between macroscopic and MOCART scores (P < 0.001). Comparable mean T2 values were found between adjacent cartilage and repair tissue in the experimental group (P > 0.05). For zonal T2 value evaluation, there were no significant zonal T2 differences for repair tissue in controls (P > 0.05). For the experimental group, zonal T2 variation was found in repair tissue (P < 0.05). MRI, macroscopy and histology showed better repair results and bony incorporation in mosaicplasty with the tissue-engineered cartilage group than those of the single mosaicplasty group. Mosaicplasty with the tissue-engineered cartilage is a promising approach to repair osteochodndral defects. Morphological MRI and T2 mapping provide a non-invasive method for monitoring the maturation and integration of cartilage repair tissue in vivo.

Imaging of osteochondritis dissecans

Osteochondritis dissecans (OCD) is a localized process that affects the subchondral bone and can progress to the overlying articular cartilage. The cause of this lesion remains elusive. With the vague clinical symptoms and signs of OCD, imaging plays a vital role in making the diagnosis and helping with the prognosis of OCD lesions. This article reviews current imaging modalities for the assessment of OCD including conventional radiography, nuclear medicine, computed tomography (CT), CT arthrography, magnetic resonance (MR) and MR arthrography. The role of imaging in evaluating healing of the OCD and articular congruity after surgical and nonsurgical management is discussed.

We do not have evidence based methods for the treatment of cartilage defects in the knee

PURPOSE

The aim of this study was to perform a systematic review of studies concerning current treatment of chondral defects of the knee.

METHODS

The relevance for evidence based data and for successful surgical treatment of cartilage defects was evaluated. From 56,098 evaluated studies, 133 studies could be further pursued. These supplied data concerning microfracturing, the osteochondral autograft transplantation system (OATS), the autologous chondrocyte implantation (ACI) and the matrix induced chondrocyte implantation (MACI). The modified Coleman Methodical Score (CMS) and the Level of Evidence (LOE) were applied to evaluate the quality.

RESULTS

In these studies, a total of 6,920 patients were reviewed with a median of 32 patients per study and a mean follow-up of 24 months. The mean CMS was 58 of 100 points. No study reached 100 points in the CMS. Three studies reached a level above 90. Ten studies were Level I, five studies reached Level II. Seven studies reached Level III, 111 studies Level IV. MRI scans to verify the clinical data were used by only 72 studies. The means in the modified CMS were for the different procedures as follows: ACI 58 points, MACI 57 points, microfracturing 68 points and OATS 50 points. 24 studies applied the Lysholm Score (LS) for clinical evaluation of cartilage surgery. All operative procedures yielded comparable improvements of the LS (n.s.) meaning that no operative procedure proved superior.

CONCLUSION

As the majority of studies evaluated by this review is insufficient for EBM purposes more coherent studies with LOE of I or II are needed. Co-relating the systems of CMS and LOE and validating the applied scores seems desirable.

Disease-specific clinical problems associated with the subchondral bone

The subchondral bone is involved in a variety of diseases affecting both the articular cartilage and bone. Osteochondral defects in distinct locations and of variable sizes are the final results of different etiologies. These include traumatic osteochondral defects, osteochondritis dissecans, osteonecrosis, and osteoarthritis. Traumatic osteochondral defects are caused by osteochondral fractures, separating an osteochondral fragment that includes articular cartilage and both subchondral and trabecular bone from the joint surface. In osteochondritis dissecans, the disease originates in the subchondral bone and secondarily affects the articular cartilage. Location, stage, size, and depth of osteochondral lesions play a role in the treatment of traumatic osteochondral defects and osteochondritis dissecans. Surgical options include fragment refixation, transplantation of osteochondral autografts, or bone restoration by impacted cancellous bone grafts combined with autologous chondrocyte transplantation. An insufficiency fracture of the subchondral bone may be the initiating factor of what was formerly believed to be a spontaneous osteonecrosis of the knee (SPONK). Recent histopathological studies suggest that each stage of SPONK reflects different types of bone repair reactions following a fracture of the subchondral bone plate. Osteoarthritis is a disease that does affect not only the articular cartilage, but also the subchondral bone. Reconstructive surgical techniques aim at preserving joint function, inducing fibrocartilaginous repair, and at correcting malalignment. This review summarizes the current status of the clinical treatment of traumatic osteochondral defects, osteochondritis dissecans, osteonecrosis, and osteoarthritis as they affect the subchondral bone region and its adjacent structures.

[Osteonecrosis in the postarthroscopic knee]

Osteonecrosis of the knee is a rare complication following arthroscopic surgery. Little is known about its etiology. The most important differential diagnosis is preexisting and undiagnosed early-stage spontaneous osteonecrosis of the knee. Medicolegally, arthroscopic surgery could be wrongly regarded as the primary cause for postarthroscopic osteonecrosis. Orthopedic surgeons need to be aware of the diagnostic pitfalls in differentiating between these entities. We suggest that the descriptive term "osteonecrosis in the postoperative knee" should be used rather than the captious term "postarthroscopic osteonecrosis."

Postarthroscopic osteonecrosis of the knee

Little is known about the etiology of postarthroscopic osteonecrosis of the knee. Its prevalence is probably very low. The most important differential diagnosis is pre-existing and undiagnosed early-stage spontaneous osteonecrosis of the knee. From the medicolegal point of view, orthopaedic surgeons need to be aware of the diagnostic pitfalls in differentiating between postarthroscopic osteonecrosis of the knee and spontaneous osteonecrosis of the knee, and they must understand that both may be unpreventable conditions. The purpose of this report is to review the presumable pathophysiology and the clinical and radiographic features as well as the pitfalls in diagnosing postarthroscopic osteonecrosis of the knee.

MR imaging of osteochondral grafts and autologous chondrocyte implantation

Surgical articular cartilage repair therapies for cartilage defects such as osteochondral autograft transfer, autologous chondrocyte implantation (ACI) or matrix associated autologous chondrocyte transplantation (MACT) are becoming more common. MRI has become the method of choice for non-invasive follow-up of patients after cartilage repair surgery. It should be performed with cartilage sensitive sequences, including fat-suppressed proton density-weighted T2 fast spin-echo (PD/T2-FSE) and three-dimensional gradient-echo (3D GRE) sequences, which provide good signal-to-noise and contrast-to-noise ratios. A thorough magnetic resonance (MR)-based assessment of cartilage repair tissue includes evaluations of defect filling, the surface and structure of repair tissue, the signal intensity of repair tissue and the subchondral bone status. Furthermore, in osteochondral autografts surface congruity, osseous incorporation and the donor site should be assessed. High spatial resolution is mandatory and can be achieved either by using a surface coil with a 1.5-T scanner or with a knee coil at 3 T; it is particularly important for assessing graft morphology and integration. Moreover, MR imaging facilitates assessment of complications including periosteal hypertrophy, delamination, adhesions, surface incongruence and reactive changes such as effusions and synovitis. Ongoing developments include isotropic 3D sequences, for improved morphological analysis, and in vivo biochemical imaging such as dGEMRIC, T2 mapping and diffusion-weighted imaging, which make functional analysis of cartilage possible.

Differenzialdiagnosen des Knochenmarködems am Kniegelenk

Bone marrow edema of the knee joint is a frequent clinical picture in MR diagnostics. It can be accompanied by symptoms and pain in the joint. Diseases that are associated with bone marrow edema can be classified into different groups. Group 1 includes vascular ischemic bone marrow edema with osteonecrosis (synonyms: SONK or Ahlbäck's disease), osteochondrosis dissecans, and bone marrow edema syndrome. Group 2 comprises traumatic or mechanical bone marrow edema. Group 3 encompasses reactive bone marrow edemas such as those occurring in gonarthrosis, postoperative bone marrow edemas, and reactive edemas in tumors or tumor-like diseases. Evidence for bone marrow edema is effectively provided by MRI, but purely morphological MR information is often unspecific so that anamnestic and clinical details are necessary in most cases for definitive disease classification.

The autologous osteochondral transplantation of the knee: clinical results, radiographic findings and histological aspects

INTRODUCTION

The osteochondral transplantation (OCT) is a well accepted treatment option for focal cartilage lesions in the knee joint, whereas the fate of the transplanted cartilage is still unclear and the clinical outcome is variable. The purpose of this study was to evaluate the histological character of autologous transplanted cartilage and to correlate technical aspects and the patients' history with the clinical outcome.

MATERIAL AND METHODS

The OCT was performed in 27 patients (median age of 32 (22-43) years) with a focal chondral lesion at the medial femoral condyle. We investigated the clinical outcome after a median follow-up of 13.5 (5-28) months using the Lysholm-score and the integration of the transplanted plugs using an MRI-scoring system. Biopsy specimens from representative patients (n = 8) were evaluated with histological staining and immunohistochemistry.

RESULTS

The median Lysholm-score was 80 (range 45-98). The wide range of the Lysholm-score in clinical outcome did not show significant differences in: follow-up, concomitant injuries, defect size or genesis. The MRI analysis revealed in all cases a regular osseous integration of the subchondral bone, but a failed chondral integration. The congruency of the plugs to the joint surface was often incorrect, however a correlation between the MRI-score and the clinical outcome could not be shown. Histology of the transplanted cartilage revealed small changes in immunohistochemistry after a relatively short-term follow-up, whereas the cartilage has still the typical hyaline character. Often, the surrounding cartilage consists of fibrous and granulation tissue.

CONCLUSION

The congruency of the joint surface can not be restored to the original status, particularly in larger defects with irregular shapes. However, we did not find any aspects which affected the function of the knee joint following OCT. It can be assumed that remaining lesions at the surrounding cartilage could maintain the inflammatory process and therefore maintain the pain and a low knee function. Further investigations are needed to specify the effects of the OCT on the transplanted cartilage and its influence on the later clinical outcome.

Normal and pathological MR findings in osteochondral autografts with longitudinal follow-up

The purpose of this study was to analyze normal and pathological MR findings in osteochondral autograft transfer systems (OATS) of the knee and ankle in the longitudinal follow-up and in relation to the clinical findings. MR imaging was performed in 55 patients (21 females: 34 males; mean age 34.5+/-12.1 years) after OATS procedures in the knee (n=45) and ankle (n=10). MR sequences were obtained with and without intravenous Gd-DTPA administration within the first year post-operatively, in 30 patients within the second and in 13 patients in the third year. One hundred and five OATS cylinders were implanted. MR findings consistent with osteonecroses were detected in eight cylinders (n=6 in the knee and n=2 in the ankle) in six patients; four out of eight were demonstrated during the first year and four/eight in the second year. Edema around and/or in the cylinders was found in 28/55 of the patients within the first year, five/30 in the second year and in two/13 in the third year. No substantial changes in the cartilage signal intensity or the cartilage-cartilage interface were demonstrated in the longitudinal follow-up within the first three years. Clinical and MR findings were not consistently associated in particular in the patients with osteochondral autograft necroses.

Painful bone marrow edema of the knee: differential diagnosis and therapeutic concepts

Bone marrow edema (BME) is a common finding when patients with knee pain are evaluated by MRI. The typical MRI signal patterns for BME are nonspecific, however. This article categorizes painful BME of the knee joint into three distinct etiologic groups and briefly describes therapeutic approaches for each of the 12 different types of BME.