Norbert Lindner

Osteoid Osteoma: CT-guided Percutaneous Radiofrequency Ablation and Follow-up in 47 Patients

PURPOSE To evaluate computed tomography (CT)-guided radiofrequency (RF) ablation as a minimally invasive therapy for osteoid osteoma with regard to technical and clinical success and immediate and delayed complications. MATERIALS AND METHODS Forty-seven patients (age range, 8-41 y; mean age, 19.6 y) with osteoid osteomas (femur, n = 25; tibia, n = 15; pelvis, n = 2; humerus, n = 1; ulna, n = 1; talus, n = 1; calcaneus, n = 1; vertebral body, n = 1) were treated with CT-guided RF ablation in 15 cases after one (n = 10) or two (n = 5) unsuccessful attempts at open surgical resection. Percutaneous therapy was performed with use of general or spinal anesthesia. After localization of the nidus with 1-3-mm CT sections, osseous access was established with either a 2-mm coaxial drill system or an 11-gauge Jamshidi needle. RF ablation was performed at 90 degrees C for a period of 4-5 minutes with use of a rigid RF electrode with a diameter of 1 mm. The procedures were regarded as technically successful if the tip of the RF electrode could be placed within the center of the nidus and could be heated to the desired temperature. Clinical success of treatment was defined as permanent relief of pain and return to normal function without additional treatment. In case of persistence or recurrence of symptoms after RF ablation, treatment was regarded as secondarily successful if permanent relief of symptoms could be achieved in a second procedure. RESULTS All procedures were technically successful. Clinical success was achieved in 94% of patients (44 of 47). Three patients had recurrence of pain 3, 5, and 7 months after treatment, respectively (mean observation interval, 22 mo). All recurrences were treated successfully in a second procedure (secondary success rate, 100%). No immediate or delayed complications were observed. CONCLUSION CT-guided percutaneous RF ablation is a simple, minimally invasive, safe and highly effective technique for treatment of osteoid osteoma.

Percutaneous radiofrequency ablation in osteoid osteoma

We treated 58 patients with osteoid osteoma by CT-guided radiofrequency ablation (RF). In 16 it followed one or two unsuccessful open procedures. It was performed under general anaesthesia in 48, and spinal anaesthesia in ten. The nidus was first located by thin-cut CT (2 to 3 mm) sections. In hard bony areas a 2 mm coaxial drill system was applied. In softer areas an 11-gauge Jamshidi needle was inserted to allow the passage of a 1 mm RF probe into the centre of the nidus. RF ablation was administered at 90 degrees C for a period of four to five minutes. Three patients had recurrence of pain three, five and seven months after treatment, respectively, and a second percutaneous procedure was successful. Thus, the primary rate of success for all patients was 95% and the secondary rate was 100%. One minor complication was encountered. CT-guided RF ablation is a safe, simple and effective method of treatment for osteoid osteoma.

Osteosarcoma of the Pelvis: Experience of the Cooperative Osteosarcoma Study Group

PURPOSE To define patients and tumor characteristics as well as therapy results, patients with pelvic osteosarcoma who were registered in the Cooperative Osteosarcoma Study Group (COSS) were analyzed. PATIENTS AND METHODS Sixty-seven patients with a high-grade pelvic osteosarcoma were eligible for this analysis. Fifteen patients had primary metastases. All patients received chemotherapy according to COSS protocols. Thirty-eight patients underwent limb-sparing surgery, 12 patients underwent hemipelvectomy, and 17 patients did not undergo definitive surgery. Eleven patients received irradiation to the primary tumor site: four postoperatively and seven as the only form of local therapy. RESULTS Local failure occurred in 47 of all 67 patients (70%) and in 31 of 50 patients (62%) who underwent definitive surgery. Five-year overall survival (OS) and progression-free survival rates were 27% and 19%, respectively. Large tumor size (P =.0137), primary metastases (P =.0001), and no or intralesional surgery (P <.0001) were poor prognostic factors. In 30 patients with no or intralesional surgery, 11 patients with radiotherapy had better OS than 19 patients without radiotherapy (P =.0033). Among the variables, primary metastasis, large tumor, no or intralesional surgery, no radiotherapy, existence of primary metastasis (relative risk [RR] = 3.456; P =.0009), surgical margin (intralesional or no surgical excision; RR = 5.619; P <.0001), and no radiotherapy (RR = 4.196; P =.0059) were independent poor prognostic factors. CONCLUSION An operative approach with wide or marginal margins improves local control and OS. If the surgical margin is intralesional or excision is impossible, additional radiotherapy has a positive influence on prognosis.

Soft tissue reconstruction of megaprostheses using a trevira tube

In soft tissue reconstruction of megaprostheses, the reattachment of soft tissue and joint capsules is essential. Sixty-nine megaprostheses were implanted and a trevira tube was applied to support reconstruction of the capsule and soft tissue. In cases of proximal femur replacement (33 patients), total femur replacement (five patients), and proximal humerus replacement (16 patients), the trevira tube allowed for reconstruction of the capsule and refixation of the muscles and helped to minimize dislocation. In cases of proximal tibia replacement (seven patients), arthrodesis of the knee (three patients), total knee replacement (two patients), and distal femur replacement (three patients), the trevira tube allowed for attachment of muscle flaps and extensor apparatus. Dislocation was observed in two of 54 patients who had proximal femur replacements. No dislocation was observed in patients with a total femur endoprosthesis or a proximal humerus endoprosthesis. The trevira tube also was used to attach the gastrocnemius muscle in patients with a proximal tibia endoprosthesis and to reattach the rotator cuff in patients with a proximal humerus prosthesis. There was no significant increase in the rate of infection. The histopathologic findings in six patients showed tissue ingrowth into the tube.

Osteoid osteoma and osteoblastoma of the spine: experiences with 22 patients.

Osteoblastomas and osteoid osteomas of the spine are relatively rare bone-forming tumors. Between 1980 and 1999, nine patients with osteoid osteoma and 13 patients with osteoblastoma had surgery for their tumors. Four tumors were in the cervical spine, six tumors were in thoracic spine, 10 tumors were in the lumbar spine, and two tumors were in the sacrum. The average duration between onset of pain and surgery was 16.6 months in 12 patients treated in the 1980s and 8.6 months in 10 patients treated in the 1990s. Seventeen patients had scoliosis. In nine of 10 patients with magnetic resonance imaging scans, high signal intensity areas in the muscles and bone around the lesion were seen. Two of nine patients with osteoid osteoma and nine of 13 patients with osteoblastoma had neurologic disorders before treatment. All patients had open resection of the lesions. Two patients with osteoid osteoma had relapse because of incomplete resection, necessitating a second excision. In 16 of 17 patients with preoperative spinal deformity, the deformity improved during followup. With development of modern imaging techniques, exact surgical planning may become possible; however, in some cases, intraoperative complete resection of the lesion still is difficult.

Limb salvage and outcome of osteosarcoma : The University of Muenster Experience

One hundred thirty-six patients with non-metastatic high grade osteosarcoma treated from 1978 to 1994 in one institution with a multidisciplinary approach that included intravenous neoadjuvant chemotherapy were studied to evaluate which factors influence the outcome of modern orthopaedic therapy. Anatomic location, tumor volume, surgical margins, complications, and functional outcome were analyzed. Seventy-nine patients had a limb salvage procedure, 21 had a rotationplasty, and 33 had an amputation. Limb salvage consisted of 32 endoprostheses, 39 allograft replacements, six autograft replacements, and two shortening procedures. Three patients died during preoperative chemotherapy treatment. At a mean followup of 43 months, 81 patients continue to be disease free, three are alive after local recurrence, 17 are alive after having metastatic lesions, five are alive with metastatic lesions present, and 30 patients died of their disease. Forty-seven patients had pulmonary metastatic lesions, 14 had osseous metastatic lesions, three had abdominal metastatic lesions, two had lymphatic metastatic lesions, and eight patients had skip metastatic lesions. Prognosis correlated with chemotherapy response, surgical margins, and tumor volume. The minor complication rate for limb salvage was 4% and the major complication rate was 52%. Amputations had a 6% minor complication rate and 34% major complication rate. Rotationplasties had 10% minor and 48% major complication rates. The Musculoskeletal Tumor Society functional evaluation after limb salvage showed that 23 (38%) patients had more than 75% of the maximum functional score, 34 (56%) were from 50% to 75%, and three (5%) less than 50%. Of the rotationplasties, six (67%) were functionally better than 75% and three (33%) were functionally better than from 50% to 75%. In the group of amputations, 13 (56%) were from 50% to 75%, and 10 (44%) less than 50%. The extent of preoperative necrosis, surgical margins, and tumor volume are the most important prognostic factors. The increase in limb salvage procedures and the better long term survival of patients results in a higher rate of immediate and delayed complications. Functional outcome after rotationplasty is superior to limb salvage reconstruction and amputation.

Osteochondroma: MR imaging of tumor-related complications

Abstract. Osteochondromas can be complicated by mechanical irritation, compression or injury of adjacent structures, fracture, malignant transformation, and postoperative recurrence. Magnetic resonance imaging represents the most valuable imaging modality in symptomatic cases, because it can demonstrate typical features of associated soft tissue pathology, which can be differentiated from malignant transformation. Reactive bursae formation presents as an overlying fluid collection with peripheral contrast enhancement. Dislocation, deformation, and signal alterations of adjacent soft tissue structures can be observed in different impingement syndromes caused by osteochondromas. Magnetic resonance imaging provides excellent demonstration of arterial and venous compromise and represents the method of choice in cases with compression of spinal cord, nerve roots, or peripheral nerves, depicting changes in size, position, and signal intensity of the affected neural structures. Malignant transformation as the most worrisome complication occurs in approximately 1 % of solitary and 5–25 % of multiple osteochondromas. Magnetic resonance imaging is the most accurate method in measuring cartilage cap thickness, which represents an important criterion for differentiation of osteochondromas and exostotic (low-grade) chondrosarcomas. Cartilage cap thickness exceeding 2 cm in adults and 3 cm in children should raise the suspicion for malignant transformation. Finally, MR imaging can detect postoperative recurrence by depiction of a recurrent mass presenting typical morphological features of a cartilage-forming lesion.

Reconstruction of the proximal humerus after wide resection of tumours

In 45 patients we assessed the functional results and complications for three different reconstructive procedures after resection of primary tumours of the proximal humerus. An osteoarticular allograft was used in 11, a clavicula pro humero operation in 15 and a tumour prosthesis in 19. The glenoid was resected with the proximal humerus in 25 patients. The axillary nerve was resected in 42 patients. The complication rate was lowest after reconstruction with a tumour prosthesis. The clavicula pro humero operation resulted in the most revisions. Cumulative survival rates for all the reconstructive procedures were similar. At follow-up at two years the functional results for the three reconstructive procedures were the same with a mean functional rating of 79% (Musculoskeletal Tumor Society). Excision of the glenoid had no influence on the functional result. Our findings indicate that the use of a tumour prosthesis is the most reliable limb-salvage procedure for the proximal humerus. The clavicula pro humero is an appropriate procedure if a prosthesis cannot be used.

Genetic imbalances revealed by comparative genomic hybridization in osteosarcomas.

Osteosarcomas are the most frequent bone sarcomas. The molecular chromosomal aberrations in osteosarcomas were analyzed by comparative genomic hybridization (CGH). We studied 47 frozen tumors (41 primary samples, 6 relapses) in osteosarcoma patients registered in the Cooperative Osteosarcoma Study (COSS) protocol. Genomic imbalances were detected in 40 of 41 primary tumors and 6 of 6 relapsed tumors. Gains were more frequent than losses (ratio of 1.3:1). The median number of changes was 16 and 12 in primary and relapsed osteosarcomas, respectively. The median number of aberrations in primary high‐grade osteosarcomas (17.0) was significantly higher than in low‐ or intermediate‐grade osteosarcoma subtypes (3.0) (p = 0.038). The most frequent gains included 8q, 1p21‐p31 and 1q21‐q24, and the most frequent losses were 10q, 5q and 13q. High‐level gains were observed on 8q23‐q24, 17p13 and 1q21‐q24. A gain of 19p (p < 0.001) or loss of 9p (p = 0.027) was more frequent in poor responders than in good responders. Univariate analysis revealed that patients with primary metastases (p = 0.002), poor histologic responses (p = 0.005), high‐level gains of 19p (p = 0.012) or losses of 13q14 (p = 0.042) had significantly lower event‐free survival (EFS), whereas patients with a loss of 5q (p = 0.007) or a loss of 10q21‐22 (p = 0.017) had significantly higher EFS than patients without these aberrations. Multivariate analysis demonstrated that primary metastasis, loss of 13q14 and loss of 5q were independent prognostic factors. The findings of our study seem to be useful for evaluating the prognosis of patients and may finally lead to treatment strategies based on genetic background of osteosarcoma.

Chondrosarcoma of the pelvis

Thirty-one patients with chondrosarcoma of the pelvis were reviewed. The median followup period of the surviving patients was 66 months. Thirteen of 23 tumors after surgery with inadequate margins (57%) and 1 of 8 after surgery with adequate margins (13%) relapsed locally. Four of 10 patients had local recurrence, 2 of 2 patients had metastasis, and 4 of 4 patients who had local recurrence and metastasis died. A cumulative 10-year overall survival of patients with pelvic chondrosarcoma was 54%. Patients who had primary or high grade chondrosarcoma had a poor prognosis. Multivariate analysis (Cox proportional hazard model) showed that tumor type was the most important prognostic factor. Eight patients underwent hindquarter amputation, 6 patients had resection alone, and 17 patients had resection and reconstruction as follows: 3 interpubic arthrodeses, 2 iliosacral arthrodeses, 3 ischiofemoral arthrodeses, 8 hip prostheses (3 prostheses alone and 5 prostheses with allograft), and 1 hip transposition. Failure of reconstruction was attributed to infection in 5 patients, local recurrence of tumor in 5, and local recurrence and fracture of implant in 1 patient.