Growth after extendible endoprosthetic replacement of the distal femur

Incidence and management of secondary deformities after megaendoprosthetic proximal femur replacement in skeletally immature bone sarcoma patients

INTRODUCTION

Megaendoprosthetic reconstruction of bone defects in skeletally immature patients has led to the development of unique complications and secondary deformities not observed in adult patient cohorts. With an increasing number of megaendoprosthetic replacements performed, orthopedic oncologists still gain experience in the incidence and type of secondary deformities caused. In this study, we report the incidence, probable cause and management outcome of two secondary deformities after megaendoprosthetic reconstruction of the proximal femur: hip dysplasia and genu valgum.

MATERIALS AND METHODS

Retrospective analysis of 14 patients who underwent primary and/or repeat reconstruction/surgery with a megaendoprosthetic proximal femur replacement between 2018 and 2022.

RESULTS

Mean patient age was 9.1 years (range 4-17 years). Stress shielding was observed in 71.4%. Hip dislocation was the most frequent complication (50%). While four dislocations occurred without an underlying deformity, secondary hip dysplasia was identified in 58.3% (n = 7/12) of intraarticular resections and reconstructions, leading to dislocation in 71.4% (n = 5/7). A genu valgum deformity was observed in 41.6% (n = 5/12). The incidence of secondary hip dysplasia and concomitant genu valgum was 42.9% (n = 3/7). Triple pelvic osteotomy led to rebound hip dysplasia in two cases (patients aged < 10 years), whereas acetabular socket replacement led to stable hip joints over the course of follow-up. Temporary hemiepiphyseodesis was applied to address secondary genu valgum.

CONCLUSIONS

Patients aged < 10 years were prone to develop secondary hip dysplasia and genu valgum following proximal femur replacement in this study. Management of secondary deformities should depend on remaining skeletal growth. Stress shielding was observed in almost all skeletally immature patients.

Non-invasive massive growing prostheses reduce infection in paediatric cancer patients

PURPOSE

In this study, we asked the question of whether non-invasive (NI) extendible bone tumour implants are as reliable and reduce infection when compared with patients who received a minimally invasive (MI) extendible implant.

METHODS

Forty-two NI extendible bone tumour implants were investigated at a mean follow-up of 22 months (range, 1-87 months) and 63 MI implants at a mean follow-up of 49 months (range, 1-156 months).

RESULTS

Kaplan-Meier analysis showed that the probability of MI implant survival was 58.8% compared with 78.6% in NI patients. No significant difference between these two patient groups was found. Infection was the main reason for failure in the MI implant group where nine (35%) implants were revised. However, only one (11%) NI implant was revised for infection ( p = 0.042). None of the NI implants failed due to aseptic loosening; however, six (23%) MI implants were revised for aseptic loosening of the intramedullary stem. Four (15%) of the failed MI implants were revised due to full extension and five (56%) of failed NI implants were replaced as the implant had been fully extended where the patient still required growth.

CONCLUSION

Where possible, an NI massive prosthesis should be used in this patient group. Our results suggest that MI prostheses should be infrequently used due to the high incidence of infection. Lengthening of NI prostheses is painless, can be carried out in the clinic and is more cost-effective. However, further work is required to increase the amount of growth potential available in these implants.

Limb Salvage Using Non-hinged Endoprosthesis and Staged Correction of Leg-length Discrepancy for Children with Distal Femoral Malignant Tumors

OBJECTIVE

Limb salvage in pediatric patients remains a challenge. We describe a staged strategy. The procedure includes: (i) tumor removal and non-hinged static endoprosthesis reconstruction; (ii) leg length discrepancy (LLD) correction by shoe lift or distraction osteogenesis; and (iii) maturity reconstruction by regular endoprosthesis. The aim of the study was to investigate the results of non-hinged static megaprosthesis reconstruction and staged LLD correction in the treatment of malignant tumors in the distal femur in children.

METHODS

Non-hinged megaprostheses were implanted in 12 pediatric patients with osteosarcoma in the distal femur. The prosthesis consists of a femoral component with constrained condylar knee (CCK) design, and a tibial component with a small-diameter press-fit stem and derotation fins. A posterior stabilizing polyethylene component is fixed on the tibial component. The cases were prospectively followed up with focus on the growth rate of adjacent uninvolved bone in the salvaged limb, joint stability, knee stability, function outcome, length discrepancy, and surgery-related complications.

RESULTS

There were five girls and seven boys included in the study, with an average age at the time of primary surgery of 10.0 years (range, 8-12 years). All the tumors were located in the distal femur. The average follow up was 76.3 months (range, 24-139 months). The Ligament Augmentation and Reconstruction System (LARS) ligament was used in two patients to enhance the soft tissue reattachment and reconstruct medial collateral ligament (MCL). Ten patients were alive at the final follow-up and two had died of lung metastases. Expected LLD was 6.7 cm (range, 3.0-13.2 cm) at initial surgery. At the final follow-up, nine patients reached skeletal maturity and the actual LLD at the femur was 5.3 cm (range, 3.0-10.1 cm), excluding 1 cm correction at initial surgery by endoprosthesis. The proximal tibia physis showed an average of 86.7% (range, 56.5%-100%) growth of the contralateral side. The mean reduction in tibial length was 1.2 cm (range, 0.5-4.7 cm). Six patients received distraction osteogenesis at a mean length of 5.4 cm (range, 3.0-9.1 cm). Range of knee movement was between 85° and 125°, with an average of 102.5°. The Musculoskeletal Tumor Society 93 score of patients alive was 80.6 (range, 60-90).

CONCLUSION

Non-hinged static megaprosthesis followed by LLD correction with shoe lift or staged distraction osteogenesis appears to be an alternative option to treat children with malignant bone tumors around the knee.

Functional and Surgical Outcomes After Endoprosthetic Reconstruction With Expandable Prostheses in Children: A Systematic Review

Treatment of bone sarcomas in children is associated with wide tumor re-section and segmental reconstruction. The optimal surgical approach is still under debate in the literature. During the past decade, the application of expandable prostheses has gained remarkable attention because it improves patients' appearance and allows limb growth preventing leg length discrepancy. A systematic review of the literature was performed to identify studies focusing on the functional and surgical outcomes of the application of expandable endoprostheses. [Orthopedics. 2019; 42(4):184-190.].

[Growing prostheses after sarcoma resection in children and adolescents]

BACKGROUND

Growing prostheses are regarded as a valuable alternative to amputation and rotationplasty for the treatment of primary malignant bone and soft-tissue sarcomas in childhood. During the last three decades different devices have been introduced and technically improved from invasively to non-invasively extendable prostheses.

THE CURRENT SITUATION OF STUDIES

Despite the long period, only 21 peer-reviewed publications could be detected containing relevant numbers and results. In these papers, 590 patients with mean follow-up times of 81.1 months were reported who had been fitted with growing prostheses at the age of 12.6 years. Besides satisfactory functional results (78.3 out of 100 MSTS points) there was a high complication rate of 27.3% infections and 22.4% mechanical failure.

COMPLICATIONS

This increasing risk of infection over a long follow-up period, represents the biggest drawback of this method and, therefore, needs to be discussed extensively with the patients and parents when considering this procedure as an alternative to ablative surgery.

What Happens to the Articular Surface After Curettage for Epiphyseal Chondroblastoma? A Report on Functional Results, Arthritis, and Arthroplasty

BACKGROUND

Chondroblastoma is an uncommon, benign, but locally aggressive bone tumor that occurs in the apophyses or epiphyses of long bones, primarily in young patients. Although some are treated with large resections, aggressive curettage and bone grafting are more commonly performed to preserve the involved joint. Such intralesional resection may result in damage to the growth plate and articular cartilage, which can result in painful arthritis. Prior studies have focused primarily on oncologic outcomes rather than long-term joint status and functional outcomes.

QUESTIONS/PURPOSES

(1) What local complications can be expected after aggressive intralesional curettage of epiphyseal chondroblastoma? (2) What is the joint survival of a joint treated in this way for chondroblastoma? (3) What additional procedures are used in treating symptomatic joint osteoarthritis after treatment of the chondroblastoma? (4) What are the functional outcomes in this group of patients?

METHODS

A retrospective study of our prospectively collected database between 1975 and 2013 was done. We found 64 patients with a diagnosis of chondroblastoma of bone. After applying our selection criteria, 53 patients were involved in this study. We excluded seven patients with tumors initially treated with en bloc resection (five located in the extremities and two in the axial skeleton) and two patients with apophyseal tumors. One patient who underwent nonsurgical treatment and one patient lost to followup were also excluded. The mean age was 18 years (range, 11-39 years); the minimum followup was 2 years with a mean followup 77 months (range, 24-213 months). We analyzed all patients with a diagnosis of epiphyseal chondroblastoma of the limb treated with aggressive curettage and joint preservation surgery. During the period in question, our general indications for curettage were patients with active, painful tumors and those with more aggressive ones that remained intracompartmental, whereas initial wide en bloc resection was indicated in patients who had tumors with an extracompartmental extension breaching the adjacent joint cartilage and massive articular destruction. The tumor location was the distal femur in 14 patients, proximal tibia in 11, proximal humerus in 10, proximal femur in eight, the talus in seven, and elsewhere in the lower extremity in three. Local complications including joint degeneration and tumor recurrence were evaluated. Based on radiographic analysis, secondary osteoarthritis was classified by using the Kellgren-Lawrence grading system from Grade 0 to Grade IV. Patients who underwent joint replacement resulting from advanced symptomatic osteoarthritis were considered to have had joint failure for purposes of survivorship analysis, which was estimated using the Kaplan-Meier method. Functional results were evaluated with the Musculoskeletal Tumor Society functional score by the treating surgeon, who transcribed the results on the digital records every 6 months of followup.

RESULTS

Twenty-two patients (42%) developed 26 local complications. The most common local complication was osteoarthritis in 20 patients (77% [20 of 26 complications]); tumor recurrence was observed in four patients; an intraarticular fracture and superficial infection treated with surgical débridement and antibiotics developed in one patient each. Joint survival was 90% at 5 years (95% confidence interval [CI], 76%-100%) and 74% at 10 years (95% CI, 48%-100%). Proximal femoral tumor location was associated with lower survivorship of the joint than other locations showing a 5-year survival rate of 44% (95% CI, 0%-88%; p = 0.000). Of the 20 patients with osteoarthritis, four were symptomatic enough to undergo joint replacement, all of which were for tumors in the proximal femur. The mean Musculoskeletal Tumor Society functional score was 28 of 30 points (93%).

CONCLUSIONS

Osteoarthritis was a frequent complication of aggressive curettage of epiphyseal chondroblastoma, and tumors located in the proximal femur appeared to be at particular risk of secondary osteoarthritis and prosthetic replacement. Because chondroblastoma is a tumor that disproportionately affects younger patients, the patient and surgeon should be aware that arthroplasty at a young age is a potential outcome for treatment of proximal femoral chondroblastomas.

LEVEL OF EVIDENCE

Level III, therapeutic study. See Instructions for Authors for a complete description of levels of evidence.

Bilateral Total Knee Arthroplasty in a 15 Year Old With Skeletal Dysplasia and Open Physes

There are limited reports of total knee arthroplasty (TKA) in the pediatric population. The use of constrained, stemmed components is particularly unusual in the setting of open physes due to concerns with growth arrest and implant survivorship. The current authors describe a 15-year-old boy with open growth plates and an epiphyseal dysplasia-like condition affecting the knees bilaterally. He had no other significant medical or orthopedic conditions and his genetic workup was negative. He had severe knee pain and a bilateral 40° valgus with severe lateral compartment arthritis. Conservative treatment provided no symptom relief, and the patient had been wheelchair bound for 18 months prior to presentation. Treatment with simultaneous bilateral TKA using cemented, stemmed, and constrained components was undertaken. There were no intraoperative complications, and his final follow-up was at 5.6 years postoperatively. Radiographic evaluation at follow-up showed that components were well placed with no loosening. The patient had pain-free motion and a perfect Knee injury and Osteoarthritis Outcome Score. Based on the review of the literature and the outcomes of this case, the authors believe simultaneous bilateral TKA using cemented, stemmed, and constrained components is a reasonable option for joint reconstruction in the pediatric patient with open physes who also has significant arthritis and deformity not of oncologic origin. [Orthopedics. 2016; 39(3):e549-e552.].

Tibial Growth Disturbance Following Distal Femoral Resection and Expandable Endoprosthetic Reconstruction

BACKGROUND

In growing children, an expandable endoprosthesis is commonly used after distal femoral resection to compensate for loss of the distal femoral physis. Our hypothesis was that such prostheses can affect proximal tibial growth, which would contribute to an overall leg-length discrepancy and cause angular deformity.

METHODS

Twenty-three skeletally immature patients underwent the placement of a distal femoral expandable endoprosthesis between 1994 and 2012. Tibial length, femoral length, and mechanical axis were measured radiographically to determine the growth rate.

RESULTS

No patient had radiographic evidence of injury to the proximal tibial physis at the time of surgery other than insertion of the tibial stem. Fifteen (65%) of the patients experienced less proximal tibial growth in the operative compared with the contralateral limb. In ten (43%) of the patients, the discrepancy progressively worsened, whereas in five (22%) of the patients, the discrepancy stabilized. Seven patients did not develop tibial length discrepancy, and one patient had overgrowth of the tibia. For the ten patients with progressive shortening, the proximal tibial physis grew an average of 4.0 mm less per year in the operative limb. Five (22%) of the patients had ≥ 20 mm of tibial length discrepancy at last follow-up. Three of these patients underwent contralateral tibial epiphysiodesis. Three patients required corrective surgery for angular deformity.

CONCLUSIONS

The tibial growth plate may not resume normal growth after implantation of a distal femoral prosthesis. Physeal bar resection, prosthesis revision, and contralateral tibial epiphysiodesis may be needed to address tibial growth abnormalities.

Temporary hemiarthroplasty with a synthetic device in children with osteosarcoma around the knee as a bridging procedure until skeletal maturity

BACKGROUND

We hypothesized that hemiarthroplasty with a synthetic device in skeletally immature patients with osteosarcoma around the knee would be functional due to high adaptability in the pediatric age group, and may decrease the number of surgeries until limb equalization by preserving the nearby physis.

METHODS

We analyzed the outcomes of 25 hemiarthroplasties (12 distal femur, 13 proximal tibia). Average patient age was 11.8 years. We assessed (1) whether hemiarthroplasty could be considered as a viable option and could preserve growth of the nearby physis, and (2) whether these patients could reach the final goal of adult-type tumor prosthesis implantation within a preplanned number of surgeries.

RESULTS

Three (12%) of 25 hemiarthroplasties showed failure. Average Musculoskeletal Tumor Society functional score of 23 patients was 25.1. Average tibial and femoral shortening for the corresponding reconstruction was 0.3 cm and 0.5 cm, respectively. In terms of number of surgeries for limb equalization, 19 patients (76%) had less, four (16%) had equal, and two (8%) had more surgeries than planned.

CONCLUSIONS

Hemiarthroplasty is a sound option until skeletal maturity, allowing surgeons to choose the appropriate procedure based on the patient's growth status, and may reduce the amount of shortening by preserving nearby physis.

Expandable Total Humeral Replacement in a Child with Osteosarcoma

Case. A right-handed 8-year-old female patient presented with a conventional, high-grade osteosarcoma involving her right humerus; through-shoulder amputation was recommended. After consultation, total humerus resection with expandable, total humeral endoprosthesis reconstruction was performed with a sleeve to encourage soft-tissue ingrowth. At three-year follow-up she has received one lengthening procedure and her functional scores are excellent. Conclusion. Total humeral resection and replacement in the pediatric population are rare and although early reports of expandable total humeral endoprosthesis outcomes demonstrate high failure rates, this patient's success indicates that expandable total humeral replacement is a viable option.

Paley's multiplier method does not accurately predict adult height in children with bone sarcoma

BACKGROUND

The majority of patients with osteosarcoma and Ewing's sarcoma are diagnosed before skeletal maturity. Paley's multiplier is used for height prediction in healthy children, and has been suggested as a method to make growth predictions for children with osteosarcoma and Ewing's sarcoma when considering limb salvage options. To our knowledge, no evaluation of this method in this particular patient group has been performed, but a temporary growth deficit has been observed in children undergoing chemotherapy.

QUESTIONS/PURPOSES

We asked whether (1) Paley's formula reliably predicts growth in children who received polychemotherapy; (2) chemotherapy impairs growth velocity; and (3) final adult height is impaired in these patients.

METHODS

Retrospectively, data for 94 patients with osteosarcoma and Ewing's sarcoma were retrieved from databases of two sarcoma centers. Onset before 14 years of age in girls and 16 years in boys and a minimum followup until 18 years were required (mean, 67 months; range, 31-124 months) criteria. Exclusion criteria were the intake of growth hormones or no chemotherapy. Thirty-three patients (35%) fulfilled all inclusion criteria. Predicted adult heights were compared with actual adult height. The development of a growth deficit was evaluated for 23 children (without chemotherapy for recurrence) using age- and gender-specific standard deviation scores for height (WHO Z-scores).

RESULTS

Height prediction using Paley's method showed a high percentage of false predictions (outside ± 1 SD, 70%; outside ± 2 SD, 61%). On average, the mean total height of the patients was overestimated (2.3 cm). The median absolute error of prediction was 5.0 cm (range, -17 to 8). Patients with osteosarcoma and Ewing's sarcoma showed a significant growth impairment during polychemotherapy. A catchup phase in growth before skeletal maturity was observed in patients with osteosarcoma but not with Ewing's sarcoma.

CONCLUSIONS

Owing to its lack of reliability in this patient group, methods other than Paley's should be evaluated to predict adult height. Although limited by a small number of patients, our study results indicate a decreased adult height in patients with bone sarcoma after chemotherapy.

LEVEL OF EVIDENCE

Level III, therapeutic study. See the Instructions for Authors for complete description of levels of evidence.

Functional outcome of limb salvage surgery with mega-endoprosthetic reconstruction for bone tumors

BACKGROUND

The use of a mega-endoprosthesis has become the method of choice for reconstruction after bone tumors. In this study, we sought to determine the functional outcome and complications associated with mega-endoprosthesis.

METHODS

A retrospective review of the charts of 16 patients who had undergone resection of bone tumors followed by reconstruction with mega-endoprosthesis between 2006 and 2011 was performed. Functional evaluation was based on the Musculoskeletal Tumor Society (MSTS) scoring system. Complications of the procedures were also analyzed.

RESULTS

Eight men and eight women at an average age of 36.7 years were included in the study. The tumor involved lower limb in 14 patients and upper limb in 2 patients. The average MSTS functional score was 72.3 ± 15. Excellent results were achieved in six patients, good in five, moderate and fair in two each and poor in one. Complications occurred in eight patients. Two patients had aseptic loosening of the femoral component of total knee replacement. Flap necrosis occurred in two patients, both of whom required latissimus dorsi free flap for coverage of total knee prosthesis. One patient underwent revision of femoral component subsequent to knee dissociation. Local recurrence of tumor, patellar tendon rupture and foot drop occurred in one patient each.

CONCLUSION

Mega-endoprosthetic reconstruction in limb salvage provides good functional outcome in patients with bone tumors.

Alloplastic reconstruction of the extensor mechanism after resection of tibial sarcoma

Reconstruction of the extensor mechanism is essential for good extremity function after endoprosthetic knee replacement following tumor resection. Only a few biological methods have been able to reliably restore a functional extensor mechanism, but they are often associated with significant complication rates. Reattachment of the patellar tendon to the prosthesis using an alloplastic patellar ligament (Trevira cord) can be an appropriate alternative. In vivo and in vitro studies have already shown that complete fibrous ingrowth in polyethylene chords can be seen after a period of six months. However, until now, no biomechanical study has shown the efficacy of an alloplastic cord and its fixation device in providing sufficient stability and endurance in daily life-activity until newly formed scar tissue can take over this function. In a special test bench developed for this study, different loading regimes were applied to simulate loads during everyday life. Failure loads and failure modes were evaluated. The properties of the cord were compared before and after physiological conditioning. It was shown that rubbing was the mode of failure under dynamic loading. Tensile forces up to 2558 N did not result in material failure. Thus, using an artificial cord together with this fixation device, temporary sufficient stable fixation can be expected.

Expandable endoprosthesis for limb-sparing surgery in children: long-term results

PURPOSE

Most children today with bone sarcomas undergo limb-sparing surgery. When treating children younger than 12 years of age, the result is significant limb length discrepancy (LLD). One of the solutions is the use of an expandable endoprosthesis.

METHODS

A retrospective analysis of 38 skeletally immature patients with bone sarcoma of the lower limb in whom different types of expandable endoprostheses were used from January 1988 to December 2005 were included. All patients were under the age of 14 years. There were 26 osteosarcoma and 12 Ewing's sarcomas. The data collected included the tumor characteristics, the surgical and other treatment modalities, complications and their treatment, and the final LLD and functional results.

RESULTS

Fifty-five percent of the patients survived and had a mean follow-up of 113 months. All survivors reached skeletal maturity at the time of last follow-up. Seventy-one percent of the survivors had satisfactory function and 29% had a poor result. There were three secondary amputations due to local recurrence. Complications were documented in 58% of patients; the most common was infection that was diagnosed 56 times (primary 16% and secondary 84%). A significant correlation was found between function and final LLD (greater than 5 cm = inferior function), the number of complications, and the number of surgical procedures performed other than prosthesis elongation. The younger the patient was at definitive surgery, the shorter the time it took for the prosthesis to fail.

CONCLUSION

In order to improve results, the number of operations must be reduced. This can be achieved by the use of novel non-invasive expandable endoprostheses or biological reconstruction.

Staged lengthening arthroplasty for pediatric osteosarcoma around the knee

BACKGROUND

Orthopaedic oncologists often must address leg-length discrepancy after resection of tumors in growing patients with osteosarcoma. There are various alternatives to address this problem. We describe a three-stage procedure: (1) temporary arthrodesis, (2) lengthening by Ilizarov apparatus, and (3) tumor prosthesis.

QUESTIONS/PURPOSES

We asked (1) to what extent are affected limbs actually lengthened; (2) how many of the patients who undergo a lengthening procedure eventually achieve joint arthroplasty; and (3) can the three-stage procedure give patients a functioning joint with equalization of limb length?

PATIENTS AND METHODS

We reviewed 56 patients (younger than 14 years) with osteosarcoma who had staged lengthening arthroplasty between 1991 and 2004.

RESULTS

Thirty-five of the 56 patients (63%) underwent soft tissue lengthening, and of these 35, 28 (50% of the original group of 56) had implantation of a mobile joint. Three of the 28 prostheses were later removed owing to infection after arthroplasty. The overall average length gained was 7.8 cm (range, 4-14 cm), and 25 (71%) of the 35 patients had a mobile joint at final followup. The average Musculoskeletal Tumor Society functional score was 23.2 (range, 15-28) and limb-length discrepancy at final followup was 2.6 cm (range, 0-6.5 cm). Although most mobile joints had an acceptable ROM (average, 74.2 degrees ; range, 35 degrees -110 degrees ), extension lag was frequent.

CONCLUSIONS

Our approach is one option for skeletally immature patients, especially in situations where an expandable prosthesis is not available. However, this technique requires multiple stages and would be inappropriate for patients who cannot accept prolonged functional deficit owing to a limited lifespan or other reasons.

LEVEL OF EVIDENCE

Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Chondroblastoma of the femoral head: management and outcome

Chondroblastoma of the femoral head presents particular problems in treatment because the tumour is surrounded by articular cartilage on one side and epiphyseal plate on the other. Ten patients underwent treatment for a chondroblastoma involving the proximal femoral capital epiphysis. The patients were aged between eight and 19 years and in four the epiphysis was not yet fused. Five had curettage via a drill hole created up the femoral neck, of whom two developed local recurrence. Five had a direct approach to the chondroblastoma through the femoral neck, and there were no local recurrences in this group. Both patients with local recurrence were under 14 years of age-one was cured by a direct approach through the neck of the femur and the other by lifting a trap door of articular cartilage. Apart from one patient with a temporary leg length discrepancy, there were no other complications. We conclude that a direct approach is likely to lead to the best outcome for this rare condition.

Innovative trident fixation technique for allograft knee arthrodesis for high-grade osteosarcoma around the knee

OBJECTIVE

Reconstruction for osteosarcoma around the knee after wide resection faces the challenge of great bone defect and future limb length discrepancy in the skeletally immature patients. Modern prosthetic reconstruction may provide good results, but the longevity may be of concern and may not be affordable in certain communities. Allograft knee arthrodesis still has its role in light of bone stock preservation and cost-effectiveness.

METHODS

We developed the innovative trident fixation technique utilizing three Steinmann pins to minimize limb length inequality without jeopardizing knee fusion stability. Twelve patients were enrolled. The mean age was 11.5 (10-13) years. Two had high-grade osteosarcoma in proximal tibia and others in distal femur.

RESULTS

Two patients died of oncological disease. The median follow-up of the disease-free 10 patients was 47 (41-60) months. All allograft-host bone junctions healed uneventfully without major complications except one allograft fracture. The average limb length discrepancy was 1.45 (1.0-2.1) cm at latest follow-up.

CONCLUSIONS

This straightforward technique was successful in knee arthrodesis with minimized limb length inequality. Accordingly, in light of bone stock preservation and longevity for the young children, it may be a surgical alternative for malignant bone tumors around the knee.

Bone remodeling around the tibial component of distal femoral expandable endoprosthesis

Radiographs of 33 patients who had an expandable prosthesis inserted after tumor resection in the distal femur were evaluated. We hypothesized that, when a sleeve was present, there was greater stem migration and cortical reaction. The thickness of medial and lateral cortices of the tibia was measured at 6 months and on the last follow-up radiograph. The distance from the edge of the prosthesis to the cortical edge was also compared. When a sleeve was present, there was greater stem migration (P < .001) and a greater increase in lateral cortical thickness (P < .001). There was a higher revision rate when a sleeve was used, but this was not statistically significant. There was no difference in function according to the Toronto Extremity Salvage Score (TESS) between the 2 groups. This is the first study to demonstrate that the presence of a polyethylene sleeve is associated with a tendency for the tibial prosthesis to migrate laterally and cause a greater sclerotic reaction.

Lower limb salvage surgery: modular endoprosthesis in bone tumour treatment

We retrospectively analysed 90 patients who underwent "en bloc" resection and modular endoprosthesis reconstruction in the lower limbs between 1987-2003. After proximal femur resection, reconstruction was performed with a modular endoprosthesis by Howmedica (KFTR, designed by Kotz) and modular revision endoprosthesis by W. Link or Lima-Lto (Revision system, designed by Wagner). The knee joint was reconstructed with a modular endoprosthesis (Howmedica, KFTR designed by Kotz) after distal femur or proximal tibia resection. Malignant bone tumours were present in 58 patients (64.5%), benign tumours in 16 (17.8%), metastases in 8 (8.9%), tumour-like lesions in 4 (4.4 %) and non-tumour-related destruction of the femur in 4 patients (4.4%). High-grade tumours were found in the majority of malignant bone tumours (70.7%). Treatment complications, which occurred in 26 patients, were: local recurrence of the tumour, deep infection, acetabular destruction following hemiarthroplasty, recurrent dislocations of endoprosthesis, periprosthetic fracture and hardware problems. In total, 23 patients (25.6%) died due to tumours. Endoprostheses should be considered as a treatment of choice for bone tumours in the hip and knee joint region. Advances in limb salvage surgery are, and will long continue to be, a great challenge for orthopaedic oncologists of the 21st century.

The use of prostheses in skeletally immature patients

Prosthetic reconstruction in the skeletally immature patient is challenging because of the necessity to cope with expected disruption of limb growth after resection of one or more major growth plates and the high demands placed on implants by young patients. Although prosthetic reconstruction in children is fraught with many problems, it is usually possible to obtain a good functional limb at skeletal maturity. Extendable prostheses are readily acceptable to patients and their parents. The availability of noninvasive extendable prostheses is expected to lead to fewer complications, fewer surgical interventions, and even improved function. This article reviews the indication, evolution, and clinical and functional results of extendable endoprostheses, drawing from experience in the last 30 years of using such prostheses in children.

Surgical options for children with osteosarcoma

Osteosarcoma is the most common solid tumour of childhood. Chemotherapy has substantially improved survival, but surgical resection remains essential for cure. Limb-salvage surgery is now common and can be done for up to 85% of children with osteosarcoma. The main surgical challenge in children is how to reconstruct the limb after removal of the tumour. Knowledge of probable outcomes, risks, and benefits of each surgical option is essential for comparison of reconstruction with amputation, which is still the safest and most suitable option in some children.