We retrospectively reviewed 56 skeletally immature patients (boys younger than 14 years, girls younger than 12 years) with osteosarcoma treated with the three-stage approach between 1991 and 2004. During this time, we treated a total of 74 patients (boys younger than 14 years, girls younger than 12 years) for osteosarcoma around the knee. Of the 74 patients, nine underwent wide resection and prosthesis reconstruction, four had amputation, two had rotationplasties, and three had hemiarthroplasties at the knee. We performed hemiarthroplasty to retain the unaffected opposing joint cartilage (in case of distal femoral osteosarcoma, we saved the proximal tibia cartilage). For the remaining 56 patients, we planned staged lengthening arthroplasty. There were 33 boys and 23 girls with an average age of 10.5 years (range, 6.9–13.9 years) at the time of tumor resection. Staging included radiographs of the lesion, a bone scan, MRI of the lesion, and CT of the chest. All patients had Stage IIB tumors according to the Musculoskeletal Tumor Society (MSTS) classification [11
]. All underwent preoperative chemotherapy, surgery, and postoperative chemotherapy and were followed as described previously [16
]. Thirty-five of the 56 (63%) patients underwent the second-stage soft tissue lengthening (Table ). The remaining 21 patients did not have the lengthening procedure for the following reasons: 10 patients (18%) died of disease (average interval from index operation to death, 25 months; range 9–54 months), three underwent amputation owing to local recurrence at 9, 12, and 16 months postoperatively, two refused additional intervention, two were lost to followup, and four patients with a discrepancy less than 3 cm at maturity had implantation of a modular prosthesis. Tumor locations in the 35 patients who underwent soft tissue lengthening were the distal femur (28 patients) and the proximal tibia (seven patients). The average followup after tumor resection for all patients was 138 months (range, 9–213 months). This study was approved by our institutional research review board.
Demographic data for 35 patients requiring soft tissue lengthening
At the time of the initial tumor resection (first stage), we performed a TRA using multiple Ender nails and a bone cement spacer, which had enough stability to allow the patient to bear weight a few days after surgery (Fig. A–B) [6
]. We performed the second-stage lengthening procedure for patients who met the following criteria: (1) relapse free for at least 2 years from tumor resection and (2) shortening greater than 4 cm. The average time from tumor resection to first lengthening was 34 months (range, 24–58 months). To correct limb shortening, soft tissue lengthening without bone transport was performed using an Ilizarov apparatus (Fig. C). This procedure can be summarized as follows: (1) removal of the Ender nails-bone cement composite to facilitate lengthening, insert the Ilizarov wires and pins, and perform extensive scarectomy; (2) filling of the defect with bone cement spacer in fully distracted position to maintain space for a subsequent megaprosthesis; and (3) application of the Ilizarov apparatus under the guidance of an image intensifier. Seven days after the procedure, distraction was started at a rate of 0.25 mm four times a day [3
]. We used this distraction rate because no serious complications were reported for this method [3
]. After lengthening, patients with expected growth greater than another 4 cm were switched to TRA for the following reasons: (1) to minimize neurovascular complications, we planned to lengthen the limb 5 to 6 cm in procedure [3
], and (2) it is difficult for patients to carry limb-length inequality greater than 4 cm with nonoperative methods until skeletal maturity. Seventeen of 35 patients with initial TRA underwent two or more of the same procedures after lengthening. Eleven of 17 patients with multiple lengthenings finally achieved the final stage of a mobile joint.
Fig. 1A–D Patient 33 was a 12-year-old boy with a diagnosis of metaphyseal osteosarcoma. (A) The lateral and (B) AP radiographs were taken after TRA using multiple Ender nails and bone cement. (C) This AP radiograph was taken after the soft tissue lengthening procedure (more ...)
Patients who had reached skeletal maturity had a static adult prosthesis implanted (Fig. D). After the conversion to a mobile joint, the average angle of the flexion contracture and additional flexion were 1.4° (range, 0°–15°) and 75.6° (range, 40°–110°). The mean extension lag was 32.4° (range, 5°–80°). Our seemingly complicated procedure enabled us to use a stepwise approach in pediatric patients with osteosarcoma. Within 2 years after tumor resection, we focus on complete treatment of the cancer. After that, we concentrate on functional restoration with equalization of limb length.
For patients who underwent TRA (first stage) or soft tissue lengthening (second stage), we permitted walking with support within 2 weeks of surgery. Partial or complete weightbearing was encouraged according to the patient’s condition. Patients with tumor prostheses (third stage) started continuous passive motion (CPM) after the drains were removed. Active movement began after patients had gained 60° flexion, and they were allowed partial weightbearing. Thereafter, patients were discharged when they were able to transfer independently (approximately 3 weeks after surgery). Before discharge, they were instructed on ROM and strengthening exercises (30 minutes each, three times per day) and were recommended to visit the local clinic for supervision. Eight weeks postoperatively the patients returned for functional assessment and radiographic evaluation. Patients were allowed to wean from use of walking assists as tolerated thereafter.
All patients were checked every month during postoperative chemotherapy with conventional radiographs of the chest and the primary lesion. After completion of chemotherapy, patients were followed for 2 years with monthly radiographs of the chest and the operated limb. Thereafter, the same protocol was repeated twice yearly up to the fifth year and annually after that time.
After the 8-week visit we followed patients twice yearly for followup of the surgery. At each visit we determined MSTS scores [10
]. We made the following assessments of limb lengths: measurement of spine-malleolar distance, wood block test, and teleroentgenograms showing the entire legs in one film. Final limb-length discrepancy, knee ROM, and extension lag were analyzed separately. We collected age, gender, site involved, heights at index operation and maturity, surgical procedures (the number of lengthening procedures and the total length gained), complications, and outcome information from the patients’ records.
All radiographs were reviewed by one radiologist (JYY) and two of the authors (SYL, DGJ). Using AP and lateral views of the entire extremity and scanograms, we evaluated (1) limb-length discrepancy and the amount of length gained, (2) limb-length inequality at skeletal maturity, and (3) presence of aseptic loosening. The radiographic interpretation of loosening was categorized into three grades: definite loosening, probable loosening, and possible loosening.
A major complication was defined as one that necessitated removal of hardware as a revision procedure. A minor complication was defined as problems other than the ones described above that necessitated additional surgical procedures or nonoperative management.