Paediatric bone sarcomas are a dual challenge for orthopaedic surgeons in terms of tumour resection and reconstruction, as it is important to minimize functional and growth problems without compromising survival rates. Cañadell’s technique consists of a Type I epiphysiolysis performed using continuous distraction by an external fixator prior to resection. It was designed to achieve a safe margin due to the ability of the physeal cartilage to be a barrier to tumour spread in some situations, avoiding the need for articular reconstruction, and preserving the growth capacity most of the times. Despite initial doubts raised in the scientific community, this technique is now widely used in many countries for the treatment of metaphyseal paediatric bone sarcomas. This annotation highlights the importance of Cañadell’s work and reviews the experience of applying it to bone sarcoma patients over the last 40 years. Cite this article: Bone Joint J 2023;105-B(1):11–16

Aims. Socioeconomic and racial disparities have been recognized as impacting the care of patients with cancer, however there are a lack of data examining the impact of these disparities on patients with bone sarcoma. The purpose of this study was to examine socioeconomic and racial disparities that impact the oncological outcomes of patients with bone sarcoma. Methods. We reviewed 4,739 patients diagnosed with primary bone sarcomas from the Surveillance, Epidemiology and End Results (SEER) registry between 2007 and 2015. We examined the impact of race and insurance status associated with the presence of metastatic disease at diagnosis, treatment outcome, and overall survival (OS). Results. Patients with Medicaid (odds ratio (OR) 1.41; 95% confidence interval (CI) 1.15 to 1.72) and uninsured patients (OR 1.90; 95% CI 1.26 to 2.86) had higher risks of metastatic disease at diagnosis compared to patients with health insurance. Compared to White patients, Black (OR 0.63, 95% CI 0.47 to 0.85) and Asian/Pacific Islander (OR 0.65, 95% CI 0.46 to 0.91) were less likely to undergo surgery. In addition, Black patients were less likely to receive chemotherapy (OR 0.67, 95% CI 0.49 to 0.91) compared to White patients. In patients with chondrosarcoma, those with Medicaid had worse OS compared to patients with insurance (hazard ratio (HR) 1.65, 95% CI 1.06 to 2.56). Conclusion. In patients with a bone sarcoma, the cancer stage at diagnosis varied based on insurance status, and racial disparities were identified in treatment. Further studies are needed to identify modifiable factors which can mitigate socioeconomic and racial disparities found in patients with bone sarcomas. Cite this article: Bone Joint Res 2022;11(5):278–291

Aims. Surgical limb sparing for knee-bearing paediatric bone sarcoma is considered to have a clinically significant influence on postoperative function due to complications and leg-length discrepancies. However, researchers have not fully evaluated the long-term postoperative functional outcomes. Therefore, in this study, we aimed to elucidate the risk factors and long-term functional prognosis associated with paediatric limb-sparing surgery. Methods. We reviewed 40 patients aged under 14 years who underwent limb-sparing surgery for knee bone sarcoma (15 cases in the proximal tibia and 25 in the distal femur) between January 2000 and December 2013, and were followed up for a minimum of five years. A total of 35 patients underwent reconstruction using artificial materials, and five underwent biological reconstruction. We evaluated the patients’ postoperative complications, survival rate of reconstruction material, and limb, limb function, and leg-length discrepancy at the final follow-up, as well as the risk factors for each. Results. Complications were observed in 55% (22/40) of patients. The limb survival and reconstruction material rates at five and ten years were 95% and 91%, and 88% and 66%, respectively. Infection was the only risk factor in both survivals (p < 0.001, p = 0.019). In the 35 patients with limb preservation, the median International Society of Limb Salvage (ISOLS) score at the final follow-up was 80 (47% to 97%). Younger age (p = 0.027) and complications (p = 0.005) were poor prognostic factors. A negative correlation was found between age and leg-length discrepancy (R = −0.426; p = 0.011). The ISOLS scores were significantly lower in patients with a leg-length discrepancy of more than 5 cm (p = 0.005). Conclusion. Young age and complications were linked to an unfavourable functional prognosis. Leg-length correction was insufficient, especially in very young children, resulting in decreased function of the affected limb. Limb-sparing surgery for these children remains a considerable challenge. Cite this article: Bone Jt Open 2024;5(10):868–878

Aims. The aim of this study was to report the results of custom-made endoprostheses with extracortical plates plus or minus a short, intramedullary stem aimed at preserving the physis after resection of bone sarcomas in children. Patients and Methods. Between 2007 and 2017, 18 children aged less than 16 years old who underwent resection of bone sarcomas, leaving ≤ 5 cm of bone from the physis, and reconstruction with a custom-made endoprosthesis were reviewed. Median follow-up was 67 months (interquartile range 45 to 91). The tumours were located in the femur in 11 patients, proximal humerus in six, and proximal tibia in one. Results. The five-year overall survival rate was 78%. No patient developed local recurrence. The five-year implant survival rate was 79%. In all, 11 patients (61%) developed a complication. Seven patients (39%) required further surgery to treat the complications. Implant failures occurred in three patients (17%) including one patient with aseptic loosening and two patients with implant or periprosthetic fracture. The preserved physis continued to grow at mean 3.3 cm (0 to 14). The mean Musculoskeletal Society score was 88% (67% to 97%). Conclusion. Custom-made endoprostheses that aim to preserve the physis are a safe and effective option for preserving physeal growth, limb length, and joint function with an acceptable rate of complications. Cite this article: Bone Joint J 2019;101-B:1144–1150

Aims. The purpose of this study was to report the long-term results of extendable endoprostheses of the humerus in children after the resection of a bone sarcoma. Methods. A total of 35 consecutive patients treated with extendable endoprosthetic replacement of the humerus in children were included. There were 17 boys and 18 girls in the series with a median age at the time of initial surgery of nine years (interquartile range (IQR) 7 to 11). Results. The median follow-up time was 10.6 years (IQR 3.9 to 20.4). The overall implant survival at ten years was 75%. Complications occurred in 13 patients (37%). Subluxation at the proximal humerus occurred in 19 patients (54%) but only six (17%) were symptomatic. Subluxation was seen more commonly in children under the age of nine years (86%) than in those aged nine years or more (33%) (p = 0.002). Implant failure occurred in nine patients (26%): the most common cause was aseptic loosening (four patients, 11%). Lengthening of the implant was carried out in 23 patients (66%). At final follow up, three patients had a limb that was shortened by 5 cm or more. The mean Musculoskeletal Tumor Society (MSTS) functional score was 79% (73% to 90%). Conclusion. Extendable endoprosthetic replacement is a reliable method of reconstructing humerus after excision of a bone sarcoma. Children who are less than nine years old have a high risk of subluxation. Cite this article: Bone Joint J 2020;102-B(1):64–71

Aims. Treatment of high-grade limb bone sarcoma that invades a joint requires en bloc extra-articular excision. MRI can demonstrate joint invasion but is frequently inconclusive, and its predictive value is unknown. We evaluated the diagnostic accuracy of direct and indirect radiological signs of intra-articular tumour extension and the performance characteristics of MRI findings of intra-articular tumour extension. Methods. We performed a retrospective case-control study of patients who underwent extra-articular excision for sarcoma of the knee, hip, or shoulder from 1 June 2000 to 1 November 2020. Radiologists blinded to the pathology results evaluated preoperative MRI for three direct signs of joint invasion (capsular disruption, cortical breach, cartilage invasion) and indirect signs (e.g. joint effusion, synovial thickening). The discriminatory ability of MRI to detect intra-articular tumour extension was determined by receiver operating characteristic analysis. Results. Overall, 49 patients underwent extra-articular excision. The area under the curve (AUC) ranged from 0.65 to 0.76 for direct signs of joint invasion, and was 0.83 for all three combined. In all, 26 patients had only one to two direct signs of invasion, representing an equivocal result. In these patients, the AUC was 0.63 for joint effusion and 0.85 for synovial thickening. When direct signs and synovial thickening were combined, the AUC was 0.89. Conclusion. MRI provides excellent discrimination for determining intra-articular tumour extension when multiple direct signs of invasion are present. When MRI results are equivocal, assessment of synovial thickening increases MRI’s discriminatory ability to predict intra-articular joint extension. These results should be interpreted in the context of the study’s limitations. The inclusion of only extra-articular excisions enriched the sample for true positive cases. Direct signs likely varied with tumour histology and location. A larger, prospective study of periarticular bone sarcomas with spatial correlation of histological and radiological findings is needed to validate these results before their adoption in clinical practice. Cite this article: Bone Jt Open 2024;5(10):944–952

We identified eight patients of 2900 with a primary malignant bone tumour who had coexisting neurofibromatosis type 1. This was a much higher incidence than would be expected by chance. The patients had a mean age of 22.4 years (9 to 54): five were male. Two patients subsequently developed a second bone sarcoma, one of which was radiation induced. Four of the primary tumours were osteosarcomas, four were spindle-cell sarcomas and one a Ewing’s sarcoma. All the patients were treated with chemotherapy and surgery: six of the eight appear to be cured. This study suggests a possible relationship between neurofibromatosis type 1 and the development of a bone sarcoma, the increased risk being estimated at eight times that of the normal population. We recommend that further research into this possible link should be considered

We aimed to identify the incidence, outcome and prognostic factors associated with spindle cell sarcomas of bone (SCSB). We studied 196 patients with a primary non-metastatic tumour treated with the intent to cure. The results were compared with those of osteosarcoma patients treated at our hospital during the same period. The overall incidence of SCSB was 7.8% of all patients with a primary bone sarcoma. The five- and ten-year survival rates were 67.0% and 60.0%, respectively, which were better than those of patients with osteosarcoma treated over the same period. All histological subtypes had similar outcomes. On univariate analysis, factors that were significantly associated with decreased survival were age > 40 years, size > 8 cm, the presence of a pathological fracture, amputation, involved margins and a poor response to pre-operative chemotherapy. Multivariate analyses showed that age > 65 years, amputation and involved margins were all statistically significant prognostic factors. Involved margins and poor response to pre-operative chemotherapy were associated with an increased risk of local recurrence. SCSB has a better prognosis than osteosarcoma when matched for age. Most prognostic factors for osteosarcoma also seem to apply to SCSB. Patients with SCSB should be treated in the same way as patients of the same age with osteosarcoma

Aim. To estimate the risk of bone malignancy arising in premalignant conditions. Methods. There are quite a number of possible premalignant conditions with considerable uncertainty about the actual risk of a bone sarcoma developing. The incidence of these malignant conditions was identified from a prospective database containing 3000 primary bone sarcomas. Results. 178 of the 3000 patients with newly diagnosed bone sarcomas had a pre-exiting condition which in all probability led to the sarcoma. These included 50 with previous radiotherapy treatment and 47 with Paget's disease. 31 patients developed malignancy in HME, 8 with neurofibromatosis and 7 each with Ollier's disease and retinoblastoma. There were 4 malignancies in patients with Mafucci's syndrome, 3 in patients with fibrous dysplasia, 3 in patients with synovial chondromatosis and 2 in patients with Rothmund-Thomson syndrome. Given that the incidence of bone sarcomas is 9/million population per year, our 3000 patients represent 333 million population years. When the incidence of a condition is known in the population this allows an estimation of the risk of malignancy compared with the normal population. Retinoblastoma for instance is known to arise in 1 in 16000 births. The 7 malignancies we saw thus represents a risk to individuals with retinoblastoma of 336/million/yr - a figure 37 times the risk of the normal population. Approximate figures of risk have been calculated for other entities. Conclusion. Data from a supra-regional register allows an approximate estimate of the increased risk of bone tumours in premalignant conditions

Navigation-assisted surgery has been reported to enhance resection accuracy in bone sarcoma surgery. Patient-specific instruments (PSIs) have been proposed as a simpler alternative with fewer setup facilities. We investigated the use of 3D surgical planning and PSI in realising computer planning of complex resections in bone sarcoma patients with regards to surgical accuracy, problems, and early clinical results. We retrospectively studied twelve patients with bone sarcoma treated surgically by PSIs with 3D planning. The procedure was planned using engineering software. The resection accuracy was accessed by comparing CT images of tumour specimens with the planned in seven patients. Mean age was 30.9 (9 – 64). Mean follow-up was 3.1 year (0.5 – 5.3). 31 planes of bone resections were successfully performed using the technique and were considered accurate. The mean time required for placing PSIs was 5.7 minutes (1 – 10) and performing bone osteotomies with the assistance of PSIs was 4.7 minutes (2 – 7). The mean maximum deviation error was 1.7mm (0.5 – 4.4). One PSI was broken during bone resection, and one patient needed re-resection using the same PSI. One pelvic patient died of local recurrence and lung metastases six months postoperatively. One patient developed a soft tissue local recurrence and lung metastasis at 20 months after surgery. The mean MSTS functional score was 27.9 (21 – 30). There were no complications related to 3D planning and PSIs. In selected patients, 3D surgical planning and PSIs replicate complex bone resections and reconstructions in bone sarcoma surgery. Comparative studies with conventional or navigation- assisted resections are required

Aim: To estimate the risk of bone malignancy arising in premalignant conditions. Methods: There are quite a number of possible premalignant conditions with considerable uncertainty about the actual risk of a bone sarcoma developing. The incidence of these malignant conditions was identified from a prospective database containing 3000 primary bone sarcomas. Results: 178 of the 3000 patients with newly diagnosed bone sarcomas had a pre-exiting condition which in all probability led to the sarcoma. These included 50 with previous radiotherapy treatment and 47 with Paget’s disease. 31 patients developed malignancy in HME, 8 with neurofibromatosis and 7 each with Ollier’s disease and retinoblastoma. There were 4 malignancies in patients with Mafucci’s syndrome, 3 in patients with fibrous dysplasia, 3 in patients with synovial chondromatosis and 2 in patients with Rothmund-Thomson syndrome. Given that the incidence of bone sarcomas is 9/million population per year, our 3000 patients represent 333 million population years. When the incidence of a condition is known in the population this allows an estimation of the risk of malignancy compared with the normal population. Retinoblastoma for instance is known to arise in 1 in 16000 births. The 7 malignancies we saw thus represents a risk to individuals with retinoblastoma of 336/million/yr – a figure 37 times the risk of the normal population. Approximate figures of risk have been calculated for other entities. Conclusion: Data from a supra-regional register allows an approximate estimate of the increased risk of bone tumours in premalignant conditions

The October 2024 Oncology Roundup. 360. looks at: Composite reconstruction: is it the answer for pelvic resections?; Can the cartilaginous thickness determine the risk of malignancy in pelvic cartilaginous tumours, and how accurate is the preoperative biopsy of these tumours?; Incidence and survival outcomes of patients with high-grade appendicular bone sarcoma and isolated regional lymph node metastasis; Improved metastatic-free survival after systematic re-excision following complete macroscopic unplanned excision of limb or trunk soft-tissue sarcoma; UK guidelines for the management of soft-tissue sarcomas; Current management of desmoid tumours: a review

Bone sarcomas are rare cancers and orthopaedic surgeons come across them infrequently, sometimes unexpectedly during surgical procedures. We investigated the outcomes of patients who underwent a surgical procedure where sarcomas were found unexpectedly and were subsequently referred to our unit for treatment. We identified 95 patients (44 intra-lesional excisions, 35 fracture fixations, 16 joint replacements) with mean age of 48 years (11 to 83); 60% were males (n = 57). Local recurrence arose in 40% who underwent limb salvage surgery versus 12% who had an amputation. Despite achieving local control, overall survival was worse for patients treated with amputation rather than limb salvage (54% vs 75% five-year survival). Factors that negatively influenced survival were invasive primary surgery (fracture fixation, joint replacement), a delay of greater than two months until referral to our oncology service, and high-grade tumours. Survival in these circumstances depends mostly on factors that are determined prior to definitive treatment by a tertiary orthopaedic oncology unit. Limb salvage in this group of patients is associated with a higher rate of inadequate marginal surgery and, consequently, higher local recurrence rates than amputation, but should still be attempted whenever possible, as local control is not the primary determinant of survival. . Cite this article: Bone Joint J 2014;96-B:665–72

Objectives: To investigate whether components of MSTS-87 (Pain, ROM, Strength, Stability, Deformity, Acceptance and Function) correlate with function as measured by TESS following endoprosthetic replacement (EPR) for patients with bone sarcoma. Methods: 255 patients with extremity bone sarcoma treated by resection & EPR were identified from a prospective database. From this group we investigated 111 patients with primary bone sarcoma with > 2 years follow up, evaluated by both MSTS-87 & TESS, no local recurrence, metastasis or major complication for at least 2 years prior to the follow-up. Upper extremity patients were excluded due to small numbers. We examined the influence of patient demographics and tumour characteristics on functional outcome scores. Correlation between MSTS-87 & TESS was performed using linear regression analysis. Results: Age, gender, tumour size, anatomical site, chemotherapy treatment and presence of pathological fracture did not significantly correlate with TESS. Linear regression analysis of MSTS-87 individual criteria and total score revealed that only pain, ROM and function helped explain the TESS score (p < 0.05) while strength, stability, deformity & acceptance had no significant effect on overall functional outcome. Conclusions: Of the seven MSTS-87 variables, only pain, ROM and function significantly correlate with overall functional outcome as measured by TESS following EPR for bone sarcoma. This suggests that patients with decreased strength, stability, deformity and acceptance as defined by MSTS-87 scores, may still adapt well with good overall functional outcomes

Purpose: Prosthetic arthroplasty is the most common method of reconstruction of segmental bone defects following resection of bone sarcomas about the knee. The purpose of this study was to determine the survivorship of the reconstructions in short- and long-term follow-up. Methods: A retrospective study was performed on all patients diagnosed with a bone sarcoma between 1984 and 1995 who were treated with a limb-sparing osteoarticular resection and rotating hinge prosthetic knee arthroplasty. Prosthetic survival was calculated with endpoints of analysis based on any event, any prosthesis-related event and aseptic loosening of the prosthesis, which led to prosthetic revision, removal or limb amputation. Results: A total of 154 reconstructions were performed involving the distal femur (n=111) and proximal tibia (n=43). The median resection length was 155 mm (105–250mm) for the distal femur and 117 mm (85–150 mm) for the proximal tibia. All implants were fixed with polymethylmethacrylate cement. Early complications (within one year postoperatively) developed in fewer than 2 % of patients. Aseptic loosening accounted for the majority of events resulting in prosthetic failures (distal femur = 17 [median failure 34 mos]; proximal tibia = 10 [median failure 100 mos]). Polyethylene bushing wear was observed in seven patients (median time to replacement = 156 months). Conclusion: The early outcome of prosthetic arthroplasty was extremely favorable supporting this method of reconstruction following excision of high-grade bone sarcomas about the knee. Long-term survival of these prostheses is suboptimal and can be anticipated to be poor for the proximal tibia. Aseptic loosening continues to be the primary cause of prosthetic failure about the knee

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. Method. Clinico-radiographic evolution in a consecutive series of 113 children, that had implanted below age 15 (range 6-14) a distal femur megaprosthesis in the period 1984-2007, was analized. A modular implant was used in 97 cases with uncemented femoral stem (three different models along the period). The implant presented fixed-hinge joint in 78 cases while rotating-hinge knee was utilized in 19 cases. In 39 cases the fixed-hinge joint had a tibial component with a polished stem to allow the residual growth of proximal tibia; in two cases a mechanically extendable prosthesis was used. A custom-made noninvasive extendable prosthesis with cemented femoral stem and smooth uncemented tibial stem was used in 15 cases since 2002. Radiological and functional results were analysed and a statistical comparison of implant outcome according different stems was obtained. Results. At a 74 months follow-up (29-294), 72 patients are alive; but 43 of them (60%) had further surgery related to primary implant. Surgical revision rate was 88% (39% for mechanical failure) in long survivors treated before 1995 and 50% (14% with mechanical failure) in more recent cases (p< 0.05). Three long survivors progressed in time to total femur megaprostheses. Five out the 15 cases treated by custom made expandable prostheses were revised before completion of skeletal growth because of implant failure. Conclusion. In limb-salvage for bone sarcoma, megaprostheses are the preferred method to reconstruct distal femur in growing children, but a durable reconstruction is not easy to be achieved. The use of new devices specially addressed to younger patients deserves a serious scientific survey by musculoskeletal oncology community

Our centre has used a specially designed custom-made endoprostheses with curved stems to reconstruct femoral defects in patients with residual short proximal femur after excision of primary bone sarcoma over the last 18 years. Two designs of endoprostheses with curved intramedullary stems were used: the rhinohorn stem type and the bifid stem type. We report the safety, survival and functional outcome of this form of reconstruction. Twenty six patients who had these special endoprosthesis reconstruction were studied. The median age was 16 years (range 7 to 60 years). Prostheses with rhino horn stems were used in 15 patients and bifid-stem in 1 1 patients. Twenty patients had the prostheses inserted as a primary procedure after excision of primary bone sarcoma, and in six patients the prostheses were inserted after revision surgery of failed distal femur endoprostheses. Seventeen patients (65%) were alive and free of disease at a median follow-up of 98 months (12 to 203 months) and nine patients had died of metastatic disease. Local recurrence developed in two patients (1 0%) out of the 20 patients. Surgical complications occurred in five patients (191/o). Deep infections occurred in two patients (8%) requiring revision surgery in one patient. Prosthetic failure, occurred in nine patients (35%). The cumulative survival of prostheses was 69% at five years and 43% at 10 years. Musculoskeletal Tumour Society mean functional score was 83% (53% to 97%). In conclusion, preservation of a short segment of the proximal femur and the use of endoprostheses with curved stems for reconstruction of the femur is technically possible. There is an increased risk of fracture of the prostheses decreasing the survival rate. Functional outcome of patients with this form of reconstruction is not significantly different from the functional outcome of patients who have proximal femur or total femur endoprosthetic reconstruction. This operation is particularly desirable in skeletally immature patients and allows normal development of the acetabulum

Objectives. To assess the affects of a delay in diagnosis on the survival rates of Bone Sarcoma (BS) using size and symptom duration as measures of delay. Methods. All patients diagnosed with a Primary BS from 1970 to 2005 were included. Demographic data concerning age, sex, diagnosis and tumour site were recorded. The data were collected retrospectively from a prospective database, with 2573 patients included. Symptom duration is defined as the length of time the patient was experiencing symptoms for until the date of diagnosis. Survival analysis was performed using Kaplan-Meier curves and Cox Regression was carried out to identify variables affecting outcome. Results. 2489 patients with Primary BS that matched out inclusion and exclusion criteria were identified. Osteosarcoma (40.4%), Chondrosarcoma (20.6%) and Ewing's Sarcoma (17.6%) were the most common diagnoses, with a median size of 10cm at presentation. Overall 5 year survival was 61.2%, extremity sited tumours carried a statistically significant better prognosis compared to axial tumours (5yr survival 63.2% vs. 53.3%) and patients with axial tumours had significantly longer symptom duration (Mann-Whitney U test p = 0.000 31 and 12 weeks). Overall analysis of all BS diagnoses showed lengthier duration of symptoms was associated with a better outcome (Hazard Ratio = 0.998, p = 0.000), which suggests that 1 extra week of symptoms confers an increased survival of 0.2%. Larger tumour size was associated with a poorer survival rate (p=0.000 to 3 sig. fig, Hazard Ratio 1.059 respectively) which suggests that for every 1cm increase in size there is a decreased survival of 5.9%. Conclusions. Although many factors have been associated with survival, the limited literature concerning symptom interval and outcome is varied. This large study has shown that regardless of diagnosis, overall, shorter symptom duration and a large tumour size are associated with a poorer prognosis

Nowadays 80% of patients with bone sarcomas can benefit from limb salvage. Their disease-free life expectancy is not jeopardised by conservative surgery as long as safe margins are obtained. For this reason, the oncological result relies on the accuracy of pre-operative and per-operative surgical measurements. Pre-operative evaluation of tumours is now quite accurate with digital margins (computed tomography, MNR, digital angiography). However, surgeons are still using centimeters or conventional radiographs with their own technical limitations for per-operative evaluation. A more accurate technique is needed. The system is composed of three components: 1) a color, graphic computer workstation with software to calculate and present the location of the surgical instrument on a three-dimensional, reconstructed bone image, 2) a complete set of hand-held instruments containing infrared emitters, 3) an infrared receiver linked to the work station. This measuring system enables determination of the position and incidence of a surgical instrument in real time during surgery, with an accuracy of less than one mm. The system requires four steps: 1) recording data with C.T., N.M.R. or angiography, 2) creating a three-dimensional image displayed on the computer screen for preoperative simulation of a virtual operation, 3) recording the very important anatomical points of the patient and optimal incidences of the surgical instruments, 4) preoperative location of surgical instruments and control of their location on bone. This system is very useful for resection of bone tumours when the conventional location is uncertain (innonimate bone, rib), when very sharp accuracy is needed to preserve the growth plate of the distal femur in young children, and to avoid medullary damage in a spinal tumour. The frameless stereotactic device is also very accurate in the reconstructive phase of limb salvage. After an internal hemipelvectomy, the device permits localisation of the acetabular prosthesis in the precise location before resection. In our practice, the accuracy of the video guiding system is always within two mm as compared to conventional measurements usually between one or two cm for long bones and three to five cm for innominate bone. The use of a video guidance system is very beneficial for limb salvage surgery for pelvic bone tumours