Introduction

The reconstruction of the knee in growing children considers many options and the chosen solution is often patient (or surgeon) based. Megaprostheses represent a reliable solution but quite expensive in the non-invasive growing version and not free from complications. In an Italian reference center for Bone and Soft tissue sarcomas, following the experience of Rizzoli Institute in Bologna, we performed the reconstruction with a resurfaced allograft for the distal femur or the proximal tibia in selected patients. The aim of the study is to confirm the reliability of this technique and to identify its potential advantages and indications.

Biomechanical interpretations of bone adaptation in biological reconstructions following bone tumors would be crucial for orthopedic oncologists, particularly if based on quantitative observations. This would help to plan for surgical treatments, rehabilitative programs and communication with the patients. In particular, outcomes of the Capanna technique, which combines bone allograft and vascularized fibula autograft, lead to stable and durable reconstructions [1, 2], and different remodeling patterns have been described [3] as a response to mechanical loading. However, there are several events that are not understood and require a biomechanical interpretation, as the evolution patterns can evolve towards conditions that threaten the strength of the reconstruction.

We aimed to (i) analyze the biomechanical adaptation of a femoral reconstruction after Ewing sarcoma, in terms of morphological and densitometric evolution of bone from CT data, internal loads acting on the bone during movement, mechanical competence of the reconstruction, and (ii) relate in-progress bone resorption to the mechanical stimulus induced by different motor activities.

Eight CT datasets of a patient (8 yrs at surgery using the Capanna technique) during 76-month follow-up were available. The evolution of bone morphology, density and moments of inertia was quantified. At the last control, the patient underwent gait analysis (walking, chair rise/sit, stair ascent/descent, squat).

We created a multiscale musculoskeletal and finite element model from CT scans and motion analysis data at the end of follow-up, using state-of-the-art modeling workflows [4, 5], to analyze muscle and joint loads, and to compare the mechanical competence of the reconstructed bone with the contralateral limb, in the current real condition and in a possible revision surgery that removed proximal screws.

Although there were no reconstruction complications and osteo-fusion with intense remodeling between allograft and autograft was shown, there was a progressive decrease in allograft cortical thickness and density. There were strategies of muscle coordination that led to differences in joint loads between limbs more marked in more demanding motor activities, and generally larger in the contralateral limb. The operated femur presented a markedly low ratio of physiological strain due to load-sharing with the metal implant, particularly in the lateral aspect. A possible revision surgery removing the three most proximal screws would help restore a physiological strain configuration, while the safety of the reconstruction would not be threatened.

We suggest that bone resorption is related to load-sharing and to the internal forces exerted during movement, and the mechanical stimulus should be improved by adopting modifications in the surgical treatment and by promoting physical therapy aimed at specific muscle strengthening.

Introduction

Historically, amputation or rotationplasty were the treatment of choice in skeletally immature patients. The introduction of expandable endoprostheses in the late 1980s offered the advantages of limb-salvage and limb length equality at skeletal maturity and a promising alternative with improved cosmetic results and immediate weight bearing.

Purpose

Rotationplasty was first described in 1930 by Borggreve for treatment of limb shortening with knee ankylosis after tuberculosis. In 1948, Van Nes described its use for management of congenital defects of the femur and in the 1980s, Kotz and Salzer reported on patients with malignant bone tumors around the knee treated by rotationplasty as an alternative to above-knee amputation. Currently, rotationplasty is one of the options for surgical management of lower extremity bone sarcomas in skeletally immature patients but alternative limb salvage techniques, such as the use of expandable endoprosthesis, are also available. Despite rather satisfactory functional results have been uniformly associated with rotationplasty, concern still exists about the potential psychological impact of the new body imagerelated to the strange appearance of the rotated limb. Results of rotationplasty for sarcomas of the distal femur over a 20-year period were analyzed, focusing on long-term survival, function, quality of life and mental health.

Aim

The use of megaprostheses for knee reconstruction after distal femur resection in young bone sarcoma patients has become popular since early ′80. The authors reviewed their experience with different distal femur megaprostheses in children.

Introduction: The role of surgery for local control in the multimodal management of Ewing’s sarcoma has substantially increased during the past 20 years. However, selection bias due to location (extremities vs axial skeleton) and relatively non-homogeneous treatment received by patients in multi-institutional trials may limit objective evaluation and comparison of the relative role of surgery and radiation therapy in this setting. Purpose of this study was to review a large series of patients homogeneously treated at a single institution.

Methods: 268 patients with non-metastatic Ewing’s sarcoma of the extremities treated by contemporary multimodal management were reviewed. Chemotherapy was administered according to 4 sequential protocols of adjuvant (1) and neoadjuvant (3) treatment. Local control consisted of surgery in 136 patients, surgery and radiation therapy in 70 patients, and radiation therapy in 60 patients. Two patients underwent only chemotherapy.

Results: The 5-year event-free survival (EFS) and overall survival (OS) were 62 and 69 per cent respectively. The rates of 5-year EFS and local control were significantly lower in patients treated with radiation therapy compared to patients treated by surgery or surgery and radiation therapy (48 vs 66 per cent, p=0.002; 80 vs 94 per cent, p= 0,0001). In group 3 (Radiation Therapy only) there were also 6 secondary malignancies.

Conclusion: Surgery was associated with better survival and local control in this series. In our opinion, surgery should always be considered in the local treatment of Ewing’s sarcoma of the extremities. Postoperative Radiation Therapy must be added in cases of inadequate surgical margins.

In order to investigate the efficacy of free vascularised fibular graft (VFG) after bone intercalary tumour resection in tibia, we present our results with a minimum follow-up of 2 years. From 1988 to 2001, 47 patients affected by high-grade tibial sarcoma in 31 cases (66%), and low-grade diesease in 16 cases (34%) were treated in our department. Average age was 19 years (range 5–60 years), with a male/female ratio of 1.35. The average length of tibial resection was 15 cm, while the average length of the fibular graft was 19 cm. In 11 cases (21%) VFG was assembled alone, while in 36 cases (79%) a massive bone allograft was associated to the fibula. Three patients developed a deep infection, treated by amputation in two cases and by graft removal and an Ilizarov device in one case. Minor complications occurred in 28 cases (55%) (stress fractures, wound slough, osteosynthesis breakage), all healed by minor surgery or conservative treatment. At an average follow-up of 108 months (range 24 to 185 months), four patients had died of disease and three were lost to follow-up. Regarding the overall results, the combined group of fibula plus massive allograft showed to be more effective than the group of fibula alone in terms of early weight bearing (6 versus 12 months), while VFG showed intrinsic efficacy in achieving early bony fusion at the osteotomy lines and hypertrophy of the graft in both groups. Furthermore, using the combined assembly the articular surface could be spared in all the trans-epiphyseal resections, while VFG alone appeared to be electively indicated for infected or irradiated fields.

In conclusion, despite the demanding surgical technique, VFG appears to be a long-lasting and definitive biological reconstruction procedure after intercalary tibial resection.

Bone reconstruction in pediatric oncology always has to face two major problems: the frequent unavailability of small prosthetic tools and the difficulty in finding bone allografts of adequate size.

Aim of this work is to present the research lines in this field, currently active in our institution to improve the planning and the results of reconstructive tumor surgery in children. Starting from patient’s CT data sets, subject-specific 3D models of bone segments can be created and compared with the similar models obtained by the CT analysis of massive allografts stored in the Rizzoli Bone Bank.

In the same time the computer modelling technologies allow the development of three-dimensional environment, where the surgeon can navigate and exploit both artificial (prostheses, metallic plates and screws) or biological tools (bone allografts or autografts).

The presented method has been utilized with success in 10 children (mean age 8, range 4–13) that underwent a skeletal reconstruction of the limbs in the last year (proximal humerus 1, diaphyseal humerus 1, total humerus 1, distal radius 1, proximal femur 3, diaphyseal femur 1, proximal tibia 1, diaphyseal tibia

Aims: Purpose of this study was to evaluate the results of a staged revision technique in the treatment of deep infection after limb salvage surgery for bone tumors and to identify factors possibly affecting the outcome. Methods: A retrospective study of 19 consecutive patients with an infected bone tumor reconstruction treated at our Institution in the period 1986–1997 was undertaken. All the patients underwent staged revision (two stages in 13 cases, three stages in 5, four stages in 1) using one or more antibiotic loaded cement spacers after debridement and partial (10 cases) or complete (9 cases) removal of the original implant. Postoperatively, all the patients received oral or parenteral antibiotics for a minimum of 4 weeks. Delayed reimplantation was performed in 15 cases, average time to reimplantation being 7 months (4–14). A minimum follow up of 3 years was available in all patients. Cultures identiþed S. Epider-midis in 12 cases (63%), S. Aureus in 4 (21%), mixed organisms in 2 (11%), and were negative in 1 case (5%) despite clinical evidence of infection. Results: At a minimum follow-up of 3 years, 13 patients were continuously infection-free (68%) while 6 relapsed (32%). Two of the 6 relapses were cleared by amputation while 4 remained infected. Average functional result of infection-free patients according to the International Society Of Limb Salvage (ISOLS) was 71% (21.2 points), ranging from 60% to 80% (18 to 24 points). Conclusions: Staged revision with antibiotic loaded cement spacer for infected bone tumor reconstruction is a demanding and expensive technique requiring prolonged inability. Overall success rate in this series approaches 70%. Complete removal of the infected implant, microbiology, appropriate antibiotic selection, and negative cultures before reimplantation are crucial.