Grade III Distal Medial Collateral Ligament Tear Missed by Magnetic Resonance Imaging: A Report of Two Cases.

Medial collateral ligament (MCL) injuries are the most common knee ligament injuries. Magnetic resonance imaging (MRI) is the investigation of choice for detecting such injuries. We report two cases of acute grade 3 MCL tears in young adults in which the injury was suspected clinically and was later confirmed by surgical exploration. However, the MRI failed to pick up the exact nature of injury. This report signifies the importance of an appropriate clinical examination for MCL injuries and stresses that decision-making for treatment should be based on the clinical examination rather than the MRI.

Normalized STEAM-based diffusion tensor imaging provides a robust assessment of muscle tears in football players: preliminary results of a new approach to evaluate muscle injuries.

OBJECTIVES: To assess acute muscle tears in professional football players by diffusion tensor imaging (DTI) and evaluate the impact of normalization of data. METHODS: Eight football players with acute lower limb muscle tears were examined. DTI metrics of the injured muscle and corresponding healthy contralateral muscle and of ROIs drawn in muscle tears (ROItear) in the corresponding healthy contralateral muscle (ROIhc_t) in a healthy area ipsilateral to the injury (ROIhi) and in a corresponding contralateral area (ROIhc_i) were compared. The same comparison was performed for ratios of the injured (ROItear/ROIhi) and contralateral sides (ROIhc_t/ROIhc_i). ANOVA, Bonferroni-corrected post-hoc and Student's t-tests were used. RESULTS: Analyses of the entire muscle did not show any differences (p>0.05 each) except for axial diffusivity (AD; p=0.048). ROItear showed higher mean diffusivity (MD) and AD than ROIhc_t (p<0.05). Fractional anisotropy (FA) was lower in ROItear than in ROIhi and ROIhc_t (p<0.05). Radial diffusivity (RD) was higher in ROItear than in any other ROI (p<0.05). Ratios revealed higher MD and RD and lower FA and reduced number and length of fibre tracts on the injured side (p<0.05 each). CONCLUSIONS: DTI allowed a robust assessment of muscle tears in athletes especially after normalization to healthy muscle tissue. KEY POINTS: • STEAM-based DTI allows the investigation of muscle tears affecting professional football players. • Fractional anisotropy and mean diffusivity differ between injured and healthy muscle areas. • Only normalized data show differences of fibre tracking metrics in muscle tears. • The normalization of DTI-metrics enables a more robust characterization of muscle tears.

Weighted Mean of Signal Intensity for Unbiased Fiber Tracking of Skeletal Muscles: Development of a New Method and Comparison With Other Correction Techniques.

OBJECTIVES: The aim of this study was to investigate the origin of random image artifacts in stimulated echo acquisition mode diffusion tensor imaging (STEAM-DTI), assess the role of averaging, develop an automated artifact postprocessing correction method using weighted mean of signal intensities (WMSIs), and compare it with other correction techniques. MATERIALS AND METHODS: Institutional review board approval and written informed consent were obtained. The right calf and thigh of 10 volunteers were scanned on a 3 T magnetic resonance imaging scanner using a STEAM-DTI sequence.Artifacts (ie, signal loss) in STEAM-based DTI, presumably caused by involuntary muscle contractions, were investigated in volunteers and ex vivo (ie, human cadaver calf and turkey leg using the same DTI parameters as for the volunteers). An automated postprocessing artifact correction method based on the WMSI was developed and compared with previous approaches (ie, iteratively reweighted linear least squares and informed robust estimation of tensors by outlier rejection [iRESTORE]). Diffusion tensor imaging and fiber tracking metrics, using different averages and artifact corrections, were compared for region of interest- and mask-based analyses. One-way repeated measures analysis of variance with Greenhouse-Geisser correction and Bonferroni post hoc tests were used to evaluate differences among all tested conditions. Qualitative assessment (ie, images quality) for native and corrected images was performed using the paired t test. RESULTS: Randomly localized and shaped artifacts affected all volunteer data sets. Artifact burden during voluntary muscle contractions increased on average from 23.1% to 77.5% but were absent ex vivo. Diffusion tensor imaging metrics (mean diffusivity, fractional anisotropy, radial diffusivity, and axial diffusivity) had a heterogeneous behavior, but in the range reported by literature. Fiber track metrics (number, length, and volume) significantly improved in both calves and thighs after artifact correction in region of interest- and mask-based analyses (P < 0.05 each). Iteratively reweighted linear least squares and iRESTORE showed equivalent results, but WMSI was faster than iRESTORE. Muscle delineation and artifact load significantly improved after correction (P < 0.05 each). CONCLUSIONS: Weighted mean of signal intensity correction significantly improved STEAM-based quantitative DTI analyses and fiber tracking of lower-limb muscles, providing a robust tool for musculoskeletal applications.

Fast Early Recovery After Transabdominal Preperitoneal Repair in Athletes with Sportsman's Groin: A Prospective Clinical Cohort Study.

BACKGROUND: Current literature on chronic groin pain suggests that laparoscopic mesh repair on athletes enables a faster recovery and subsequent return to unrestricted athletic activities. The aim of this study was to evaluate the role of transabdominal preperitoneal (TAPP) mesh repair in athletes resistant to conservative therapy. METHODS: A multidisciplinary approach with tailored physiotherapy. Thirty-nine professional athletes with chronic groin pain were referred to surgery at a single clinic. A full assessment was carried out on each, including medical history, physical examination, dynamic ultrasound, and pelvic magnetic resonance imaging. TAPP repair was performed using a polypropylene mesh and fibrin glue fixation on 30 athletes who had exhibited typical symptoms, shown resistance to conservative therapy, not benefited from accompanying physiotherapy, and had ceased training in the 3 to 6 months prior. The outcome measures were early postoperative recovery of 6 weeks and full resumption of athletic activities. RESULTS: Mean duration of symptoms from onset to surgical repair was 7 months. Conservative treatment had improved symptoms temporarily or to some extent in 7 athletes, while 2 ceased competing altogether. Twenty-three athletes exhibited unilateral and 16 bilateral groin pain. Laparoscopy confirmed posterior wall deficiency in 24 and true inguinal hernia in 6 athletes. Mild scrotal hematoma occurred in 2 athletes postoperatively; all were discharged within 24 hours of surgery. Twenty-one (70%) returned to sports activities after 6 weeks of convalescence. Persistent mild pain was experienced by 5 athletes postoperatively for up to 1 year, yet did not interfere with normal daily activity. Twenty-five participants (85%) reported full satisfaction with the procedure 1 year after treatment; all returned to the same or even higher level of athletic performance. CONCLUSION: The study confirms that the endoscopic placement of retropubic mesh is an efficient, safe, and minimally invasive treatment that enables fast early recovery.

Three-dimensional magnetic resonance observation of cartilage repair tissue (MOCART) score assessed with an isotropic three-dimensional true fast imaging with steady-state precession sequence at 3.0 Tesla.

INTRODUCTION: Cartilage defects are common pathologies and surgical cartilage repair shows promising results. In its postoperative evaluation, the magnetic resonance observation of cartilage repair tissue (MOCART) score, using different variables to describe the constitution of the cartilage repair tissue and the surrounding structures, is widely used. High-field magnetic resonance imaging (MRI) and 3-dimensional (3D) isotropic sequences may combine ideal preconditions to enhance the diagnostic performance of cartilage imaging.Aim of this study was to introduce an improved 3D MOCART score using the possibilities of an isotropic 3D true fast imaging with steady-state precession (True-FISP) sequence in the postoperative evaluation of patients after matrix-associated autologous chondrocyte transplantation (MACT) as well as to compare the results to the conventional 2D MOCART score using standard MR sequences. MATERIAL AND METHODS: The study had approval by the local ethics commission. One hundred consecutive MR scans in 60 patients at standard follow-up intervals of 1, 3, 6, 12, 24, and 60 months after MACT of the knee joint were prospectively included. The mean follow-up interval of this cross-sectional evaluation was 21.4 +/- 20.6 months; the mean age of the patients was 35.8 +/- 9.4 years. MRI was performed at a 3.0 Tesla unit. All variables of the standard 2D MOCART score where part of the new 3D MOCART score. Furthermore, additional variables and options were included with the aims to use the capabilities of isotropic MRI, to include the results of recent studies, and to adapt to the needs of patients and physician in a clinical routine examination. A proton-density turbo spin-echo sequence, a T2-weighted dual fast spin-echo (dual-FSE) sequence, and a T1-weighted turbo inversion recovery magnitude (TIRM) sequence were used to assess the standard 2D MOCART score; an isotropic 3D-TrueFISP sequence was prepared to evaluate the new 3D MOCART score. All 9 variables of the 2D MOCART score were compared with the corresponding variables obtained by the 3D MOCART score using the Pearson correlation coefficient; additionally the subjective quality and possible artifacts of the MR sequences were analyzed. RESULTS: The correlation between the standard 2D MOCART score and the new 3D MOCART showed for the 8 variables "defect fill," "cartilage interface," "surface," "adhesions," "structure," "signal intensity," "subchondral lamina," and "effusion"-a highly significant (P < 0.001) correlation with a Pearson coefficient between 0.566 and 0.932. The variable "bone marrow edema" correlated significantly (P < 0.05; Pearson coefficient: 0.257). The subjective quality of the 3 standard MR sequences was comparable to the isotropic 3D-TrueFISP sequence. Artifacts were more frequently visible within the 3D-TrueFISP sequence. CONCLUSION: In the clinical routine follow-up after cartilage repair, the 3D MOCART score, assessed by only 1 high-resolution isotropic MR sequence, provides comparable information than the standard 2D MOCART score. Hence, the new 3D MOCART score has the potential to combine the information of the standard 2D MOCART score with the possible advantages of isotropic 3D MRI at high-field. A clear limitation of the 3D-TrueFISP sequence was the high number of artifacts. Future studies have to prove the clinical benefits of a 3D MOCART score.

Magnetic resonance imaging for diagnosis and assessment of cartilage defect repairs.

Clinical magnetic resonance imaging (MRI) is the method of choice for the non-invasive evaluation of articular cartilage defects and the follow-up of cartilage repair procedures. The use of cartilage-sensitive sequences and a high spatial-resolution technique enables the evaluation of cartilage morphology even in the early stages of disease, as well as assessment of cartilage repair. Sequences that offer high contrast between articular cartilage and adjacent structures, such as the fat-suppressed, 3-dimensional, spoiled gradient-echo sequence and the fast spin-echo sequence, are accurate and reliable for evaluating intrachondral lesions and surface defects of articular cartilage. These sequences can also be performed together in reasonable examination times. In addition to morphology, new MRI techniques provide insight into the biochemical composition of articular cartilage and cartilage repair tissue. These techniques enable the diagnosis of early cartilage degeneration and help to monitor the effect and outcome of various surgical and non-surgical cartilage repair therapies.

Computer-assisted surgery of cartilage defects in the knee: comparison of rigid-body fixation techniques in a human cadaver study.

This experimental cadaver study assessed computer navigation for the arthroscopic measurement of full-thickness cartilage defects in the knee joint. Cartilage defects were measured during arthroscopy using three cartilage defect-managing modules to compare fixed (invasive) and noninvasive rigid-body fixations. The comparison of all three systems tested revealed a difference between the noninvasive and the fixed rigid-body fixation, with a mean value of 0.07 mm for the width, 0.15 mm for the height, and 0.17 mm for the surface area of the cartilage defect (P > .05). Every point of the cartilage defect was attainable with the pointer tip. The force applied to the instrument during the defect palpation to keep the leg stable during the navigation process was acceptable. In conclusion, the cartilage defect-managing module allows the precise measurement of full-thickness cartilage defects in the knee joint during arthroscopy and that the module can be used with noninvasive rigid-body fixation.

The functional outcome of total tears of the anterior cruciate ligament (ACL) in the skeletally immature patient.

Tears of the anterior cruciate ligament (ACL) in the skeletally immature patient are becoming more prevalent. The aim of this study was to describe the functional outcome and to evaluate the best management of total tears of the ACL in skeletally immature patient. Twenty consecutive, skeletally immature patients with a clinically evident rupture of the anterior cruciate ligament were followed up for a mean of 5.4 years. The mean age at the time of injury was 13.9 years old. The study group consisted of 13 girls and 7 boys, who were treated either conservatively, by ACL reconstruction, by primary repair or by delayed ACL reconstruction after skeletal maturity had been reached. Clinical outcomes were measured using the International Knee Documentation Committee Scoring System (IKDC) and the Knee Injury and Osteoarthritis Outcome Scoring System (KOOS). The radiological evaluation was performed using Jaeger and Wirth's criteria, and instrumented laxity testing was carried out with a Rolimeter. Five of the eight patients treated conservatively showed poor function of the knee, and this resulted in instability. Concerning the patients treated by primary repair, delayed ACL reconstruction or arthroscopic debridement, we also found none of the results to be satisfactory (seven of eight patients). The patients that were treated by a reconstruction had the best results. This was confirmed by clinical examination (Lachmann grade 1), by the IKDC (grade B) and by the KOOS with the best quality of life and no giving-way attacks. The level of evidence was therapeutic level III.

Cartilage repair: generations of autologous chondrocyte transplantation.

Articular cartilage in adults has a limited capacity for self-repair after a substantial injury. Surgical therapeutic efforts to treat cartilage defects have focused on delivering new cells capable of chondrogenesis into the lesions. Autologous chondrocyte transplantation (ACT) is an advanced cell-based orthobiologic technology used for the treatment of chondral defects of the knee that has been in clinical use since 1987 and has been performed on 12,000 patients internationally. With ACT, good to excellent clinical results are seen in isolated post-traumatic lesions of the knee joint in the younger patient, with the formation of hyaline or hyaline-like repair tissue. In the classic ACT technique, chondrocytes are isolated from small slices of cartilage harvested arthroscopically from a minor weight-bearing area of the injured knee. The extracellular matrix is removed by enzymatic digestion, and the cells are then expanded in monolayer culture. Once a sufficient number of cells has been obtained, the chondrocytes are implanted into the cartilage defect, using a periosteal patch over the defect as a method of cell containment. The major complications are periosteal hypertrophy, delamination of the transplant, arthrofibrosis and transplant failure. Further improvements in tissue engineering have contributed to the next generation of ACT techniques, where cells are combined with resorbable biomaterials, as in matrix-associated autologous chondrocyte transplantation (MACT). These biomaterials secure the cells in the defect area and enhance their proliferation and differentiation.

The removal of a dislocated femoral interference screw through a posteromedial portal.

The intra-articular migration of a femoral interference screw is a rare complication after anterior cruciate ligament (ACL) reconstruction in the knee. Only a few reports of cases have been published within the last few years and different approaches toward this complication have been described. We report the case of a 23-year-old female patient who was admitted with knee pain after undergoing an ACL reconstruction 4 years previously. After the clinical examination, a knee radiograph in 2 planes revealed a dislocated femoral interference screw lying in the popliteal fossa. During arthroscopy, the interference screw was retrieved through an additional posteromedial portal to avoid an arthrotomy. The causes for intra-articular screw migration are multiple and most cases were reported in the early postoperative period. The arthroscopic removal of a screw is recommended because of the lower morbidity.

Early postoperative adherence of matrix-induced autologous chondrocyte implantation for the treatment of full-thickness cartilage defects of the femoral condyle.

Matrix-induced autologous chondrocyte implantation (MACI) is a tissue-engineering technique for the treatment of full-thickness articular cartilage defects and requires the use of a three-dimensional collagen type I-III membrane seeded with cultured autologous chondrocytes. The cell-scaffold construct is implanted in the debrided cartilage defect and fixed only with fibrin glue, with no periosteal cover or further surgical fixation. In a clinical pilot study, the MACI technique was used for the treatment of full-thickness, weight-bearing chondral defects of the femoral condyle in 16 patients. All patients were followed prospectively and the early postoperative attachment rate, 34.7 days (range: 22-47) after the scaffold implantation, was determined. With the use of high-resolution magnetic resonance imaging (MRI), the transplant was graded as completely attached, partially attached, or detached. In 14 of 16 patients (87.5%), a completely-attached graft was found, and the cartilage defect site was totally covered by the implanted scaffold and repair tissue. In one patient (6.25%), a partial attachment occurred with partial filling of the chondral defect. A complete detachment of the graft was found in one patient (6.25%), which resulted in an empty defect site with exposure of the subchondral bone. Interobserver variability for the MRI grading of the transplants showed substantial agreement (kappa=0.775) and perfect agreement (kappa(w)=0.99). In conclusion, the implantation and fixation of a cell-scaffold construct in a deep cartilage defect of the femoral condyle with fibrin glue and with no further surgical fixation leads to a high attachment rate 34.7 days after the implantation, as determined with high resolution MRI.

Definition of pertinent parameters for the evaluation of articular cartilage repair tissue with high-resolution magnetic resonance imaging.

To evaluate articular cartilage repair tissue after biological cartilage repair, we propose a new technique of non-invasive, high-resolution magnetic resonance imaging (MRI) and define a new classification system. For the definition of pertinent variables the repair tissue of 45 patients treated with three different techniques for cartilage repair (microfracture, autologous osteochondral transplantation, and autologous chondrocyte transplantation) was analyzed 6 and 12 months after the procedure. High-resolution imaging was obtained with a surface phased array coil placed over the knee compartment of interest and adapted sequences were used on a 1 T MRI scanner. The analysis of the repair tissue included the definition and rating of nine pertinent variables: the degree of filling of the defect, the integration to the border zone, the description of the surface and structure, the signal intensity, the status of the subchondral lamina and subchondral bone, the appearance of adhesions and the presence of synovitis. High-resolution MRI, using a surface phased array coil and specific sequences, can be used on every standard 1 or 1.5 T MRI scanner according to the in-house standard protocols for knee imaging in patients who have had cartilage repair procedures without substantially prolonging the total imaging time. The new classification and grading system allows a subtle description and suitable assessment of the articular cartilage repair tissue.

Urinary tract infections beyond the early post-transplant period in pediatric renal graft recipients.

BACKGROUND: Urinary tract infection is a frequent bacterial complication after renal transplantation in adults and children, however there are only very limited data on children beyond the early post-transplant period. In this study we investigated urinary tract infections in pediatric outpatients who had received transplants more than six months previously. Incidence, risk factors and impact on short-term graft function were analyzed. METHODS: 47 children who had received a total of 58 allografts were analyzed between 1997 and 2000. At the time of analysis they had had their transplants for an average of 3.5 years (range 0.5-9.4). Urinary tract infection was defined as the presence of both significant bacteriuria (> 10(5) CFU/ml) and symptoms. RESULTS: Of the 47 patients, 15 (32%) had from 1 to 7 urinary tract infections each. In total 35 infections were recorded. Median age at urinary tract infection was 5.5 years (range 1.8-24.2). Gender, donor source, immunosuppression and underlying disease (urologic vs non-urologic) did not influence the incidence of urinary tract infection. Creatinine but not C-reactive protein rose significantly during the infection. CONCLUSIONS: Our data suggest that urinary tract infection remains a frequent but mostly benign complication in the pediatric transplant population, even beyond the early post-transplant period. More extended studies are needed to assess the long-term effects on graft function.