Risto Ojala

Oulu University Hospital, Uleoborg, Oulu, Finland

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Publications (53)122.81 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: To investigate the association of quantitative magnetic resonance imaging (qMRI) parameters with arthroscopic grading of cartilage degeneration. Arthroscopy of the knee is considered to be the gold standard of osteoarthritis diagnostics; however, it is operator-dependent and limited to the evaluation of the articular surface. qMRI provides information on the quality of articular cartilage and its changes even at early stages of a disease.
    Knee surgery, sports traumatology, arthroscopy : official journal of the ESSKA. 09/2014;
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    ABSTRACT: The purpose of this article was to analyze the long-term radiologic results after distal chevron osteotomy for hallux valgus treatment and to determine the preoperative radiographic factors correlating with radiological recurrence of the deformity.
    Foot & Ankle International 09/2014; · 1.47 Impact Factor
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    ABSTRACT: No operative technique for hallux valgus has been introduced in which the first metatarsophalangeal joint is not touched. We report the first tarsometatarsal joint derotational arthrodesis in which we mimic the function of the peroneus longus tendon without involving the first metatarsophalangeal joint, allowing function of the windlass mechanism without interference. We treated 66 patients (62 women and 4 men) with 84 flexible hallux valgus feet using our new operative technique. Preoperative and postoperative follow-up weightbearing radiographs were evaluated. Most patients had a pronation type foot (78%) preoperatively, and mean correction in hallux valgus and intermetatarsal angle was 20° and 9°, respectively (p < .001). The LaPorta classification showed a median change of 2.5 U (p < .001). We have described a new operative technique for flexible hallux valgus. The first tarsometatarsal joint derotational arthrodesis showed notable correction angles in hallux valgus, although the first metatarsophalangeal joint was left intact.
    The Journal of foot and ankle surgery: official publication of the American College of Foot and Ankle Surgeons 11/2013;
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    ABSTRACT: The purpose of this study was to evaluate the diagnostic performance of magnetic resonance imaging (MRI) guided musculoskeletal biopsy and the value of fine needle aspiration biopsy (FNAB) when combined with histologic biopsy. A total of 172 biopsies were performed under MRI guidance, 170 were histologic biopsies. In 112 cases, a fine needle aspiration biopsy was also performed. In two cases, a stand-alone FNAB was performed. The diagnostic performance was evaluated retrospectively by comparing the histopathologic and cytologic diagnosis with the current or final diagnosis after at least one year of clinical and imaging follow-up. A 0.23T open MRI scanner with an interventional stereotactic guidance system was used. The overall diagnostic accuracy of MRI guided biopsy was 0.95, sensitivity 0.91, specificity 0.98, positive predictive value (ppv) 0.97 and negative predictive value (npv) 0.93. The diagnostic accuracy of trephine biopsy alone was 0.93, sensitivity 0.89, specificity 0.98, ppv 0.97 and npv 0.91 and accuracy for FNAB alone was 0.85, sensitivity 0.80, specificity 0.90, ppv 0.89 and npv 0.82. MRI guidance is a feasible and accurate tool in percutaneous musculoskeletal biopsies. Fine needle biopsy is a useful low-cost supplement to histologic biopsy.
    European journal of radiology 09/2013; · 2.65 Impact Factor
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    ABSTRACT: Osteoarthritis and osteoporosis often coexist in postmenopausal women. The simultaneous effect of bone-favorable high-impact training on these diseases is not well understood and is a topic of controversy. We evaluated the effects of high-impact exercise on bone mineral content (BMC) and the estimated biochemical composition of knee cartilage in postmenopausal women with mild knee osteoarthritis. Eighty women aged 50-66 years with mild knee osteoarthritis were randomly assigned to undergo supervised progressive exercise 3 times a week for 12 months (n = 40) or to a non-intervention control group (n = 40). BMC of the femoral neck, trochanter and lumbar spine was measured by dual-energy X-ray absorptiometry (DXA). The biochemical composition of cartilage was estimated using delayed gadolinium-enhanced MRI of cartilage (dGEMRIC), sensitive to cartilage glycosaminoglycan content, and T2 mapping that is sensitive to the properties of the collagen network. In addition, clinically important symptoms and as physical performance related risk factors of falling; dynamic balance, maximal isometric knee extension and flexion forces, leg power and cardiorespiratory fitness were evaluated. Thirty-six trainees and 40 controls completed the study. The mean gain in femoral neck BMC in the exercise group was 0.6% (95% CI: -0.2 to 1.4) and the mean loss in the control group was -1.2% (95% CI: -2.1 to -0.4). The baseline, body mass and body mass change adjusted BMC change between the groups was significant (P = 0.005), while no changes occurred in the biochemical composition of the cartilage, as investigated by MRI. Balance, muscle force and cardiorespiratory fitness improved significantly more (3-11%) in the exercise group than in the control group. Progressively implemented high-impact training, which increased bone mass, did not affect the biochemical composition of cartilage and may be feasible in the prevention of osteoporosis and physical performance related risk factors of falling in postmenopausal women.
    Journal of bone and mineral research: the official journal of the American Society for Bone and Mineral Research 06/2013; · 6.04 Impact Factor
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    ABSTRACT: OBJECTIVE: To compare delayed gadolinium-enhanced MRI of cartilage (dGEMRIC) and delayed quantitative CT arthrography (dQCTA) to each other, and their association to arthroscopy. Additionally, the relationship between dGEMRIC with intravenous (dGEMRIC(IV)) and intra-articular contrast agent administration (dGEMRIC(IA)) was determined. DESIGN: Eleven patients with knee pain were scanned at 3 Tesla MRI and 64-slice CT before arthroscopy. dQCTA was performed at 5 and 45 minutes after intra-articular injection of ioxaglate. Both dGEMRIC(IV) and dGEMRIC(IA) were performed at 90 minutes after gadopentetate injection. dGEMRIC indices and change in relaxation rates (ΔR(1)) were separately calculated for dGEMRIC(IV) and dGEMRIC(IA). dGEMRIC and dQCTA parameters were calculated for predetermined sites at the knee joint that were ICRS graded in arthroscopy. RESULTS: dQCTA normalized with the contrast agent concentration in synovial fluid and dGEMRIC(IV) correlated significantly, whereas dGEMRIC(IA) correlated with the normalized dQCTA only when dGEMRIC(IA) was also normalized with the contrast agent concentration in synovial fluid. Correlation was strongest between normalized dQCTA at 45 minutes and ΔR(1,IV) (r(s)=0.72 [95% CI 0.56 - 0.83], n=49, p<0.01) and ΔR(1,IA) normalized with ΔR(1) in synovial fluid (r(s)=0.70 [0.53 - 0.82], n=52, p<0.01). Neither dGEMRIC nor dQCTA correlated with arthroscopic grading. dGEMRIC(IV) and non-normalized dGEMRIC(IA) were not related while ΔR(1,IV) correlated with normalized ΔR(1,IA) (r(s)=0.52 [0.28 - 0.70], n=50, p<0.01). CONCLUSIONS: This study suggests that dQCTA is in best agreement with dGEMRIC(IV) at 45 minutes after CT contrast agent injection. dQCTA and dGEMRIC were not related to arthroscopy, probably because the remaining cartilage is analysed in dGEMRIC and dQCTA, whereas in arthroscopy the absence of cartilage defines the grading. The findings indicate the importance to take into account the contrast agent concentration in synovial fluid in dQCTA and dGEMRIC(IA).
    Osteoarthritis and Cartilage 12/2012; · 4.26 Impact Factor
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    ABSTRACT: OBJECTIVE: The purpose of this study was to evaluate the feasibility, the initial accuracy, and the effects of the MR-guided neurolytic celiac plexus ablation as a method to treat cancer-induced chronic abdominal pain. METHODS: Thirteen celiac plexus ablations were performed for 12 patients. A 0.23-T open MRI scanner with optical navigation was used for procedural guidance. As an adjunct to the MR-guided needle positioning, the needle location was confirmed with saline injection and consequent MR imaging (STIR sequence). The spread of the ablative injection material (alcohol-lidocaine mix) was observed by repeating this sequence after the therapeutic injection. Pain scores from seven patients (eight ablations) were used to assess the therapy effect. RESULTS: MR guidance allowed adequate needle positioning and visualization of injection material in all cases. The rest pain scores significantly decreased from 4 (median) at baseline to 1 (median) at 2 weeks (p < 0.05). Average and worst pain experienced during the past week were significantly lower at the 2-week time point compared with the baseline (p < 0.05). However, the intervention did not result in reduction of opioid use at 2 weeks. CONCLUSIONS: MR guidance is an accurate and safe method for celiac plexus ablation with positive therapeutic effect.
    CardioVascular and Interventional Radiology 05/2012; · 2.09 Impact Factor
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    ABSTRACT: The aim of this study was to perform prospective, randomized comparison of two surgical techniques (fixation versus no fixation) and two postoperative regimens (soft cast versus elastic band) to determine if the head fragment displaces more or less with either technique. One hundred consecutive patients were included in the study. The osteotomy was fixed with an absorbable pin in 50 cases and no fixation in the other 50. Half of each group used a soft cast for 6 weeks postoperatively and half had a traditional elastic bandage. Weightbearing radiographs at 6 weeks, 6 months, 1 year, and mean of 7.9 years were evaluated. A larger shift was found when fixation was used 3.9 (SD, 0.8) mm at 6 weeks versus 3.1 (SD, 0.9) mm in the no fixation group (p < 0.001). The two bandage types had no significant effect to the mean shift. Correction of the mean hallux valgus angle was worse overall when preoperative angles were over 30 degrees (p < 0.001). There was a statistically higher shift in the fixation group, but the clinical significance of 0.7 mm difference and the type of postoperative bandaging did not influence outcome is questionable. The risk for recurrence of hallux valgus was higher when preoperative angles were over 30 degrees.
    Foot & Ankle International 05/2012; 33(5):420-3. · 1.47 Impact Factor
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    ABSTRACT: Collagen fibrils of articular cartilage have specific depth-dependent orientations and the fibrils bend in the cartilage surface to exhibit split-lines. Fibrillation of superficial collagen takes place in osteoarthritis. We aimed to investigate the effect of superficial collagen fibril patterns and collagen fibrillation of cartilage on stresses and strains within a knee joint. A 3D finite element model of a knee joint with cartilage and menisci was constructed based on magnetic resonance imaging. The fibril-reinforced poroviscoelastic material properties with depth-dependent collagen orientations and split-line patterns were included in the model. The effects of joint loading on stresses and strains in cartilage with various split-line patterns and medial collagen fibrillation were simulated under axial impact loading of 1000 N. In the model, the collagen fibrils resisted strains along the split-line directions. This increased also stresses along the split-lines. On the contrary, contact and pore pressures were not affected by split-line patterns. Simulated medial osteoarthritis increased tissue strains in both medial and lateral femoral condyles, and contact and pore pressures in the lateral femoral condyle. This study highlights the importance of the collagen fibril organization, especially that indicated by split-line patterns, for the weight-bearing properties of articular cartilage. Osteoarthritic changes of cartilage in the medial femoral condyle created a possible failure point in the lateral femoral condyle. This study provides further evidence on the importance of the collagen fibril organization for the optimal function of articular cartilage.
    Journal of biomechanics 11/2011; 45(3):579-87. · 2.66 Impact Factor
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    ABSTRACT: Magnetic resonance imaging (MRI) is promising tool for image-guided therapy. In musculoskeletal setting, image-guided therapy is used to direct diagnostic and therapeutic procedures and to steer patient management. Studies have demonstrated that MRI-guided interventions involving bone, soft tissue, joints, and intervertebral disks are safe and in selected indications can be the preferred action to manage clinical situation. Often, these procedures are technically similar to those performed in other modalities (computed tomography, fluoroscopy) for bone and soft tissue lesions. However, the procedural perception to the operator can be very different to other modalities because of the vastly increased data.Magnetic resonance imaging guidance is particularly advantageous should the lesion not be visible by other modalities, for selective lesion targeting, intra-articular locations, cyst aspiration, and locations adjacent to surgical hardware. Palliative tumor-related pain management such as ablation therapy forms a subset of procedures that are frequently performed under MRI. Another suitable entity for MRI guidance are the therapeutic percutaneous osseous or joint-related benign or reactive conditions such as osteoid osteoma, epiphyseal bone bridging, osteochondritis dissecans, bone cysts, localized bone necrosis, and posttraumatic lesions. In this article, we will describe in detail the technical aspects of performing MRI-guided therapeutic musculoskeletal procedures as well as the clinical indications.
    Topics in magnetic resonance imaging: TMRI 08/2011; 22(4):171-7.
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    ABSTRACT: The purpose of this study was to evaluate the feasibility of a new method for osteochondritis dissecans (OCD) treatment. Ten OCD lesions of the knee unresponsive to conservative management were treated with MRI-guided percutaneous retrograde drilling to reduce symptoms and promote ossification of the lesion. All lesions were located in distal femoral condyles. Only stable OCD lesions were included (preprocedural MRI grade I or II). Five lesions were of juvenile type and five lesions were of adult type OCD. All the patients had severe limitation of activity due to the OCD-related pain. By using a 0.23 T open MRI scanner and spinal anesthesia, percutaneous retrograde drilling of the OCD lesions was performed (3 mm cylindrical drill, one to three channels). Optical tracking and MRI imaging were used to guide instruments during the procedure. Mean postprocedural clinical follow-up time was 3 years. Eight patients had a post-procedural follow-up MRI within 1 year. All the OCD lesions were located and drilled using the 0.23 T open MRI scanner without procedural complications. All the patients had pain relief, mean visual analog score (VAS) declined from 6 to 2. Follow-up MRI showed ossification in all lesions. Eight patients could return to normal physical activity with no or minor effect on function (Hughston score 3-4). Treatment failed in two cases where the continuation of symptoms led to arthroscopy and transchondral fixation. CONLUSION: MR-guided retrograde OCD lesion drilling is an accurate, feasible, and effective cartilage-sparing techique in OCD management.
    Skeletal Radiology 02/2011; 40(6):765-70. · 1.74 Impact Factor
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    ABSTRACT: The use of image-guided thermoablative methods in liver tumor treatment has expanded rapidly due to encouraging results and advanced imaging. However, little is known about the treatment-induced tissue response and effects on imaging findings during the subacute post procedural period. To study the development of subacute ablation zone volume with magnetic resonance imaging (MRI) after laser-mediated liver tumor thermal therapy. In all, 16 laser ablations were performed on 16 liver tumors resulting in 16 ablation zones in 11 consecutive patients. A low-field 0.23 T C-arm MRI scanner was used for imaging and procedural guidance. Repeated dynamic contrast-enhanced T1, contrast-enhanced T1 FSE, and T2 FSE studies of liver were performed at 0 and 72 h after the procedure. Ablation zone volumes were registered from the acquired image data. MRI scans showed a significant increase of ablation volume in all imaging sequences obtained at 72 h after the initial therapy. After laser ablation, there is a progressive perfusion decrease in the ablation site leading to an increase in the ablation volume. Post procedural baseline MRI at 72 h from the treatment provides more precise information about the ablation result than can be obtained with immediate post procedural MRI.
    Acta Radiologica 06/2010; 51(5):505-11. · 1.33 Impact Factor
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    ABSTRACT: It is unclear whether osteoarthritis (OA) of the knee is seen better in standing flexion position radiographs than in the standing extended view. We assessed the value of standing flexion views. We retrospectively evaluated 1,090 radiographs of 545 consecutive knees with non-traumatic knee pain, comparing standing fixed flexion view (FFV) and standing extended view (SEV). OA was classified according to the Kellgren-Lawrence (KL) radiographic grading scale and joint space widths were measured. Medial joint space width was lower on average in the FFV, with the greatest difference in KL II knees. Medial full-thickness loss of cartilage was also seen more often in the FFVs of knees with moderate OA (KL II-III) than in the SEVs (6% vs. 19%). Using FFV, there is no need to measure the exact knee flexion angle to use fluoroscopy. In earlier studies, the FFV has been found to be reproducible and easy to use in clinical practice. We recommend using flexion views when deciding the appropriate type of intervention in patients with OA. Full-thickness loss of cartilage in particular is better seen in the flexion view, which may be helpful if planning unicompartmental knee arthroplasty.
    Acta Orthopaedica 06/2010; 81(3):344-6. · 2.74 Impact Factor
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    ABSTRACT: The number of detected small renal cell carcinomas (RCCs) has been rising, largely due to advances in imaging. Open surgical resection is the standard management of small RCCs; however, imaging-guided percutaneous ablative therapies have emerged as a minimally invasive treatment alternative, especially for patients who are poor candidates for surgery. To evaluate the initial clinical experience of magnetic resonance imaging (MRI)-guided percutaneous laser ablation of small RCCs. Eight patients with 10 tumors were treated with percutaneous MRI-guided laser ablation. All tumors (diameter range 1.5-3.8 cm, mean 2.7 cm) were biopsy-proven RCCs. By using a 0.23 T open MRI system and general anesthesia in patients, one to four (mean 2.6) laser fibers were placed and the tumors were ablated under near real-time MRI control by observing the signal void caused by the temperature change in the heated tissue. The treatment was considered successful if the tumor showed no contrast enhancement at follow-up imaging. All except one tumor were successfully ablated in one session. The first patient treated showed enhancing residual tumor in post-procedural MRI; she has thus far declined retreatment. One complication, a myocardial infarction, occurred; all other patients tolerated the procedure well. No local recurrence was discovered during the follow-up (range 12-30 months, mean 20 months). In this small group of patients with relatively short follow-up period, MRI-guided percutaneous laser ablation proved to be a promising treatment option for small RCCs.
    Acta Radiologica 05/2010; 51(4):467-72. · 1.33 Impact Factor
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    ABSTRACT: To assess the normal topographical variation of T2 relaxation time of articular cartilage in different compartments of the knee joint and at different tissue depths in young healthy adults. Twenty asymptomatic young adult volunteers (age range, 21-27 years; mean age, 22.5 years), were studied at 1.5T. Both axial and sagittal multi-slice multi-echo spin echo measurements were performed to determine the T2 relaxation time of cartilage in the femoral, tibial and patellar compartments. The cartilage surfaces were divided into 24 segments and each segment was divided into deep and superficial regions-of-interest (ROIs) of equal thickness. The reproducibility for ROI analysis was assessed for five patients by determining the interclass correlation coefficient (ICC) and the root-mean-square coefficient of variation (CV(RMS)). Cartilage T2 was significantly dependent on joint topography, compartment and tissue depth. For all joint surfaces, superficial T2 values were systematically higher as compared to deep tissue. The data showed a trend toward higher T2 values at the load bearing area of the femoral condyles. The interobserver error varied significantly among different locations and showed mostly good reproducibility with mean ICC of 0.70 and a CV(RMS) of 5.0%. The normal variation in cartilage T2 within a joint is significant and should be acknowledged when pathology-related T2 changes are investigated. The knowledge on normal variation can be used for power and sample size calculations in further studies, and the T2 values as control data in future patient studies.
    Osteoarthritis and Cartilage 06/2009; 17(12):1570-5. · 4.26 Impact Factor
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    ABSTRACT: The purpose of this study was to investigate the day-to-day reproducibility of the delayed gadolinium-enhanced MRI of cartilage (dGEMRIC) measurement at different knee joint surfaces in healthy subjects at 1.5 Tesla (T). The dGEMRIC experiment was repeated for 10 asymptomatic volunteers three times with an average interval of 5 days between scans. The measurement was performed from a single sagittal slice through the center of the lateral femoral condyle and from the center of the patella in the axial plane. Cartilage was manually segmented into superficial, deep and full-thickness regions of interests (ROIs) at different topographical locations of the femur, tibia and patella. The reproducibility was evaluated separately for each ROI as well as for the entire bulk cartilage in the slice of each joint surface. The reproducibility at various ROIs expressed by root-mean-square average coefficient of variation (CV(RMS)) ranged between 4.7-12.9%. Thirty out of thirty-three ROIs showed a CV(RMS) less than 10%. Intraclass correlation coefficient (ICC) ranged between 0.45 and 0.98. The CV(RMS) and ICC for bulk dGEMRIC were 4.2% and 0.95 for femur, 5.5% and 0.87 for tibia, and 4.8% and 0.97 for patella. The dGEMRIC technique showed good day-to-day reproducibility, on the average 8% for small deep or superficial segments, 7% for full-thickness ROIs and 5% for bulk ROIs covering all visible cartilage in a single joint surface. We conclude that dGEMRIC imaging at field strength 1.5 T can be used as a reliable instrument for the assessment of articular cartilage when staff has been carefully trained.
    Osteoarthritis and Cartilage 01/2009; 17(5):559-64. · 4.26 Impact Factor
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    ABSTRACT: The purpose of this study was to assess the feasibility and safety of magnetic resonance imaging (MRI)-guided PCN in an open-configuration low-field MRI system. Eight patients were prospectively enrolled in the study. The degree of the dilatation of the renal collecting system varied from minimal to severe. All procedures were performed solely under MRI guidance with a 0.23-T open configuration C-arm-shaped MRI system with interventional optical tracking. In each case, PCN was performed with a MRI-compatible drainage kit using the Seldinger technique. Seven out of eight nephrostomies were successfully performed under MRI guidance. All PCN procedures in dilated renal collection systems were successful; however, nephrostomy catheter could not be placed in a nondilated system. The mean time needed for the MRI-guided PCN was 26 min. No major complications occurred during the procedure or follow-up. MRI-guided PCN in dilated renal collection system is feasible and safe. The presented technique has limitations that necessitate further technical developments before the procedure can be applied to nondilated kidneys and recommended for routine clinical use.
    European Radiology 12/2008; 19(5):1296-301. · 4.34 Impact Factor
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    ABSTRACT: A decreased supply of nutrition to the intervertebral disc can lead to disc degeneration. Nutrient supply can be simulated in vivo by measuring gadolinium enhancement of the disc. We aimed to study the changes associated with disc degeneration that may have effect on the nutrition of the disc, i.e. lumbar artery narrowing, Modic changes, endplate defects, and apparent diffusion coefficient (ADC) in nucleus pulposus. Twenty male volunteers underwent a lumbar spine examination at 1.5 T for anatomical imaging, diffusion weighted imaging, magnetic resonance angiography, and for T1 relaxation time quantification of contrast enhancement of intervertebral disc. Enhancement of the disc increased with degeneration. Disc space narrowing associated strongly with the enhancement (Pearson's correlation coefficient 0.46, P < 0.001). The enhancement rate in discs adjacent to Modic type 2 changes was 24%, adjacent to type 1/2 changes 58%, and 13% in the absence of Modic changes. Discs adjacent to endplate defects enhanced 32% compared to 10% of normal endplates. Lumbar artery narrowing or ADC in the disc were not associated with the enhancement. Increased enhancement of a degenerated disc is associated mostly with disc space narrowing and with the presence of degenerative endplate changes and endplate defects.
    MAGMA Magnetic Resonance Materials in Physics Biology and Medicine 10/2008; 22(2):101-9. · 1.86 Impact Factor
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    ABSTRACT: Growth plate or physeal cartilage trauma may result in delayed or immediate failure of growth due to bone bridge formation at the insult site. With computed tomography (CT) and magnetic resonance imaging (MRI), the role of imaging has expanded from diagnosis to treatment planning and therapy guidance. To describe a technique for MR-guided growth plate bone bridge resection and to evaluate feasibility of the procedure. Three consecutive patients with growth plate bone bridges were treated surgically under MR guidance. All bridges were detected with prior MRI and radiographs. All patients were referred to procedure due to growth plate bridge associated growth anomaly and pertaining clinical symptoms. The effect of the treatment was evaluated after 48 months with a clinical follow-up. All bridges were successfully detected, marked, and removed under MRI guidance. All patients had relief from their symptoms. Two patients had lasting results from the operation with no further operative treatment needed or scheduled at 48 months from primary treatment. There was one clinical failure, with the patient requiring repeated osteotomies. We have successfully implemented a novel therapy for growth plate bridge resection.
    Acta Radiologica 08/2008; 49(6):668-72. · 1.33 Impact Factor

Publication Stats

593 Citations
122.81 Total Impact Points

Institutions

  • 1999–2014
    • Oulu University Hospital
      • • Department of Surgery
      • • Department of Radiology
      • • Department of Physical Medicine and Rehabilitation
      Uleoborg, Oulu, Finland
  • 2012
    • Helsinki University Central Hospital
      Helsinki, Southern Finland Province, Finland
  • 2005–2006
    • Brigham and Women's Hospital
      • Department of Radiology
      Boston, MA, United States
    • University of Oulu
      Uleoborg, Oulu, Finland