Infected mega-endoprostheses are difficult to treat with systemic antibiotics due to encapsulation of the implant by fibrous tissue, formation of biofilms and antibiotic resistant bacteria. Modifying the implant surface by incorporating a bactericidal agent may reduce infection. Infection rates are typically in the range of 8% to 30%. This study describes a novel process method of “stitching-in” ionic silver into the implant surface, in vitro testing and its early clinical usage.

A novel process has been developed to “stitch in” ionic silver into the upper surface of titanium alloy (Ti6Al4V). The process produces a modification by anodisation of the titanium alloy in dilute phosphoric acid, followed by absorption of silver from an aqueous solution. The engineered surface modification is therefore integral with the substrate and loaded with silver by an ion exchange reaction. Using this technique the maximum inventory of silver for typical a mega-prosthesis is 6mg and this is greater than 300 times lower than the No Observable Adverse Affects Level (NOAEL). Scanning electron microscopy revealed that the silver was concentrated in pits and forming reservoirs of ionic silver exposed to the body tissues.

Laboratory-based studies focusing on the safety and efficacy of silver as a bactericidal agent have included investigation into cytotoxicity using fibroblast and osteoblast cell lines, the impact of silver in reducing corrosion and laboratory testing to establish if the modified surface has an effect on the wear and mechanical characteristics. A range of fatigue, static, tensile pull off tests were performed. The silver elution profiles for both silver loaded and HA coated over a silver loaded surface have been examined. Histological studies were also performed to examine the impact of the silver on osseointegration.

The in vitro results confirm that silver is an effective antimicrobial agent. The mechanical characterization studies have identified that the surface treatment has no or minimal impact on the implant surface. Early results of the elution studies are encouraging showing that the HA coating of a silver loaded surface does not “seal” in the silver.

To date (May 10) 147 silver treated mega-prostheses have been implanted since March 2006. The majority of implants were distal femoral (29%), proximal tibial (23%) or hemiplevic (10%). The most common indication was revision of a failed limb salvage reconstruction (58%), with the dominant cause of failure being infection. The next most common indication was bone tumour (31%) and the large majority were used in the high risk skeletal locations of the tibia (44%) and the pelvis (27%). Early clinical results are encouraging indicating a significant reduction in the incidence of infection.

Three implants have been retrieved. An analysis of a proximal humeral replacement that had been in situ for 6 mths identified that there was 10-20% remaining on the implant surface.

This novel process of “stitching-in” silver appears to be a safe and effective surface treatment in helping to control infections of mega-prostheses. This technology has the potential to be transferred to other arthroplasty joints.

Pigmented villonodular synovitis is a monoarticular proliferative process most commonly involving the synovium of the knee joint. There is considerable debate with regards to diagnosis and effective treatment.

We present our experience of managing PVNS of the knee joint over a 12 year period. Twenty-eight patients were reviewed. MRI was used to establish recurrence in symptomatic patients rather than routine screening and to identify posterior disease prior to surgery.

Eight patients had localised disease and were all treated with open synovectomy and excision of the lesion, with no evidence of recurrence. Twenty patients had diffuse disease, eight treated arthroscopically and twelve with open total synovectomy. Nineteen patients (95%) had recurrence on MRI, however, only five (25%) had evidence of clinical recurrence.

There were no significant complications following arthroscopic synovectomy. Open synovectomy, in contrast, was associated with three wound infections and two thrombo-embolisms. Three patients had Complex regional pain syndrome.

We believe diffuse disease should be treated with arthroscopic synovectomy which is associated with minimal morbidity and can be repeated to maintain disease control. Radiotherapy is helpful in very aggressive cases. TKR was used when there was associated articular erosion.

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.

Solitary plasmacytomas in the appendicular skeleton are rare monoclonal expansions of plasmacytoid cells. They are two main hazards; local destruction of bone with resultant loss of function and possible fracture, and progression to Myeloma.

Between February 1988 and July 2005 seven patients (4 male, 3 female) were treated for solitary plasmacytoma with surgical resection and endoprosthetic reconstruction. The median age was 46.7 (35-75). The site was: distal humerus (2), proximal humerus (2) proximal femur (2) proximal tibia (1). Three patients had sustained a pathological fracture. Five patients had received pre-operative radiotherapy and three received post-operative radiotherapy. Mean follow-up is 8.6 years. Two cases became infected at 2 and 5 years post-operatively and have had revisions of their endoprosthesis. Both remain functional at 18 and 15 years. No patient has suffered a local recurrence. Two patients have progressed to multiple Myeloma but no patients have died. Literature review shows that the progression of solitary bone plasmacytoma to Myeloma is around 53% despite radiotherapy, in an average period of 2-4 years. With resection and endoprosthetic reconstruction, the progression in this series has been 28% despite an average follow up of 8.6 years.

Although the numbers are small, due to the rarity of the condition, surgical resection and endoprosthetic reconstruction reduces disease progression than radiotherapy alone. This produces far superior results compared to the intramedullary nailing of the long bones for this condition. Endoprosthetic reconstruction after resection should be given consideration in cases of solitary plasmacytoma of the appendicular skeleton when there is extensive bone destruction present. The optimal timing of local radiotherapy to be combined with surgery is still to be established.

Objective

Sarcomas are a rare group of tumours, which pose numerous problems regarding correct diagnosis and appropriate management. This study aimed to examine whether symptom duration and tumour size at diagnosis have changed over time, using size and symptom duration as methods of comparison.

Between 1966 and 2001, 1254 patients underwent excision of a bone tumour with endoprosthetic replacement. All patients who had radiotherapy were identified. Their clinical details were retrieved from their records.

A total of 63 patients (5%) had received adjunctive radiotherapy, 29 pre-operatively and 34 post-operatively. The mean post-operative Musculoskeletal Tumor Society scores of irradiated patients were significantly lower (log-rank test, p = 0.009). The infection rate in the group who had not been irradiated was 9.8% (117 of 1191), compared with 20.7% (6 of 29) in those who had pre-operative radiotherapy and 35.3% (12 of 34) in those who radiotherapy post-operatively. The infection-free survival rate at ten years was 85.5% for patients without radiotherapy, 74.1% for those who had pre-operative radiotherapy and 44.8% for those who had post-operative radiotherapy (log-rank test, p < 0.001). The ten-year limb salvage rate was 89% for those who did not have radiotherapy and 76% for those who did (log-rank test, p = 0.02).

Radiotherapy increased the risk of revision (log-rank test, p = 0.015). A total of ten amputations were necessary to control infection, of which nine were successful. Radiotherapy may be necessary for the treatment of a bone sarcoma but increases the risk of deep infection for which amputation may be the only solution.

We performed a retrospective review of 98 patients with malignant tumours of the periacetabular region, treated by resection and endoprosthetic reconstruction between 1971 and 2005 at the Royal National Orthopaedic Hospital, Stanmore and The Royal Orthopaedic Hospital, Birmingham.

The mean age of the patients was 43.6 years (10 to 76). 53 patients (54%) were male. The age distribution demonstrated peaks in the 2nd and 6th decades. The mean follow up was 65 months (2 to 405. The overall 10-year survival rate was 56% (determined by the Kaplan-Meier method).

54 patients (58.1%) had one or more complications. Infection was the most common (30%) with the majority occurring in the first 2 years. Dislocation occurred in 19 (20%) of our patients all in the first year following surgery. All were recurrent with a mean of 2.9 (2 to 6) episodes. Operations performed before 1994 were associated with a dislocation rate of 40.5% and after 1996 the rate was only 3.9% (p < 0.001).

Function was assessed according the Toronto Extremity Salvage Sore (TESS). The overall TESS was 59.4. In patients that had a major complication the TESS was 37.1 but in the group that did not the TESS was 70.3 (p < 0.001).

Men experienced higher rates of death, infection and revision than women (p < 0.05). The local recurrence rate was 31% with high grade tumours associated with higher recurrence rates (p < 0.05). Tumour resection in the ilium is associated with higher rates of infection than tumours located in the periacetabular region alone (p < 0.05).

This method of reconstruction is still associated with high complication rates. Function is good if a major complication can be avoided. The lower dislocation rate more recently is probably the result of improved surgical technique and the use of larger femoral heads.

We have investigated whether improvements in design have altered the outcome for patients undergoing endoprosthetic replacement of the distal femur following tumour resection.

Survival of the implant and ‘servicing’ procedures have been documented using a prospective database and review of the implant design records and case records. A total of 335 patients underwent a distal femoral replacement with 162 having a fixed hinge design and 173 a rotating hinge with most of the latter group having a hydroxyapatite collar at the bone prosthesis junction. The median age of the patients was 24 years (range 13-82 yrs). With a minimum follow up of 5 years and a maximum of 30 years, 192 patients remain alive with a median follow-up of 11 years. The risk of revision for any reason was 17% at 5 years, 34% at 10 years and 58% at 20 years. One in ten patients developed an infection and 42% of these patients eventually required an amputation. Aseptic loosening was the most common reason for revision in the fixed hinge knees whilst infection and stem fracture were the most common reason in the rotating hinges. The risk of revision for aseptic loosening in the fixed hinges was 32% at ten years compared with nil for the rotating hinge knees with a hydroxyapatite collar. The overall risk of revision for any reason was halved by use of the rotating hinge, and for patients older than 40 years at time of implant.

EPRs are the treatment of choice following resection of tumours. These have been used for 39 years in our institution. There has been concern regarding the long term survival of endoprosthesis; this study investigates the fate of the reconstruction.

Current guidelines suggest that most lumps less than 5cm in size will not be malignant. We reviewed our experiences of small lumps at the Royal Orthopaedic Hospital, Birmingham, in order to try and identify factors associated with malignancy. All referrals to our clinic were included and data on size, symptoms, depth and diagnosis were analysed. We identified 325 patients, with 57 (17.5%) malignant and 268 (82.5%) benign lumps. Size >3cm was the most accurate predictor of malignancy (35.8% malignant vs 9.9% <3cm). 23.6% of lumps reported as increasing size were found to be malignant, compared to 8.6% of those that were not. Pain was found to be a poor predictor of malignancy, with only 15.5% of painful lumps found to be malignant and 18.9% of painless lumps found to be malignant. ‘Size >3cm’ has a sensitivity of 73.6% and a specificity of 56.3%, ‘Depth’ has a sensitivity of 73.6% and a specificity of 30.2%, ‘Increasing in Size’ a sensitivity of 71.4% and a specificity of 56.7% and ‘Pain’ a sensitivity of 33.3% and a specificity of 57.1%. If a lump has none of the above features then one can be 89.5% certain that it is not malignant. If it has 1 feature there is a 16.1% chance of its becoming malignant, 2 features a 58% chance, 3 features an 87% chance and if a lump has all 4 features there is a 93.5% chance of its being found to be malignant.

The main limitation with this study is that the data set is skewed because all lumps referred to the Oncology Department are by their nature suspicious. This study identifies those factors which suggest malignancy in small lumps and provides the basis for carrying out a large, community-based study on all lumps, to identify features associated with malignancy.

Chondroblastomas arise in the epiphyseal area of bones. In the femoral head this can cause considerable difficulty in obtaining access as the epiphysis is entirely intra-articular.

We have reviewed management and outcome of 10 patients with chondroblastoma of the femoral head to identify outcome and complications. The mean age was 14 years and all presented with pain (frequently in the knee) and a limp. All were diagnosed on plain Xray and MRI. Five younger children were treated by curettage by a lateral approach up the femoral neck (to try and minimise damage to the epiphysis) and five by a direct approach through the joint.

Two of the five patients with a lateral approach developed local recurrence whilst none of the direct approaches did. Both local recurrences were cured with a direct curettage. One patient developed overlengthening of the leg by 1cm but there was no case of growth arrest or osteoarthritis.

We recommend a direct approach to the lesion whenever possible to give the best chance of cure with a low risk of complications.

Introduction

Despite the advances in adjuvant chemotherapy and surgical techniques, the diagnosis of a bone tumour still carries with it a significant risk of mortality. This study investigates factors affecting survival, in patients treated for malignant tumours of bone using Endoprosthetic replacement (EPR).

Soft tissue sarcomas (STS) arising in the adductor compartment of the thigh are frequently large before clinical detection, posing particular challenges with surgical resection and associated with a high risk of wound complications. This study compares oncological and functional outcomes and complications following treatment of adductor compartment soft tissue sarcomas from three international centres with different treatment philosophies.

184 patients with new primary, non-metastatic, deep STS in the adductor compartment diagnosed between 1990 and 2001 were identified from the centres' local databases. The Toronto Extremity Salvage Score (TESS) was used to assess function in patients.

There were 94 male and 90 female patients, with ages ranging from 13 to 88 years (median age 57 years). The period of follow-up ranged from 1 to 162 months. The overall survival was 65% at 5 years and related to grade and size of the tumour. There was no difference in overall survival or systemic relapse between the three centres. There was however a significant difference in local control (28% LR in centre 1 compared to 10% in centre 2 and 5% in centre 3, which appeared to be principally related to the use of radiotherapy and surgical margins.)

66 patients (36%) from the three centres developed wound complications post-operatively and it was shown to be associated with high grade and large tumours (>10cm).

Functional scores averaged 78% but were significantly worse for patients with wound complications or high-grade tumours; however, they were not affected by timing of radiotherapy or use of prophylactic free muscle flaps.

Propionibacteria are organisms of low virulence, although they do cause deep periprosthetic infections. The aim of this study was to show that Propionibacteria do not always cause a significant rise in ESR and CRP.

Between May 2001 and May 2004, we identified 77 patients with prosthetic joint replacements colonised with Propionibacteria, 47 males and 30 females. There were 47 hip joint replacements, 27 knee joint replacements, 2 endoprosthetic replacements of the femur and 1 shoulder joint replacement. We retrieved successfully the medical records of 66 patients in order to identify the number of patients treated for an infected prosthetic joint arthroplasty. The pre-operative values of ESR and CRP were recorded. For the purposes of this study, an ESR rate of 30mm/hr or higher and a CRP level of 10mg/lt or higher were considered to be suggestive of infection and were deemed a positive result.

All of the 77 patients had both ESR and CRP measured pre-operatively. In only 16 (21%) both ESR and CRP were higher than 30mm/hr and 10mg/l respectively. In 33 patients (43%) with prosthetic joint replacements colonised with Propionibacteria, the pre-operative values of ESR and CRP were normal. 23 patients were treated for an infected prosthetic joint arthroplasty. In 7 (30%) of those patients both ESR and CRP were normal.

This suggests that normal pre-operative values of ESR and CRP in suspected failed prosthetic joint replacements might not exclude infection, if the causative organism is of low virulence such as Propionibacteria.

Fifty-six patients with stage II-B osteosarcoma around the knee were followed-up for a minimum of 92 months. The percentage of tumour cells expressing VEGF/MMP-9 was assessed using immunohistochemistry. The relationship between VEGF/MMP-9 expression and survival was assessed using Kaplan-Meier and Cox regression models. Patients with tumours expressing VEGF in >25% of their cells had shorter overall (p=0.019) and disease-free survival (p=0.009). Patients with tumours expressing MMP-9 had shorter overall (p=0.0042) and disease-free survival (p=0.0004). There was an association between VEGF and MMP-9 expression (p=0.021). The negative effects of VEGF/MMP-9 expression on survival were independent of traditional prognostic factors.

Aim

To identify patient, tumour or treatment factors that influence outcome in patients with radiation induced sarcoma of bone.

Dedifferentiated chondrosarcoma is a rare but highly malignant manifestation that can occasionally arise in patients with cartilage tumours. There remains uncertainty as to the best treatment for this condition and in particular whether chemotherapy may have a role in improving prognosis.

Members of EMSOS were invited to contribute data on patients, tumours, treatment and outcomes of patients with dedifferentiated chondrosarcoma.

Eight centres contributed data on 317 patients from 7 countries. The mean age was 59 (range 15 to 89) and the most common site was the femur (46%) followed by the pelvis (28%). 25% of patients presented with a pathological fracture and the most common high grade component identified was MFH. 23% had metastases at diagnosis and these patients had a median survival of 5 months. 30% of patients received chemotherapy, with 47% under 60 having chemotherapy compared with 10% over 60. One third of this group had neoadjuvant chemotherapy and the rest had adjuvant reatment. 88% had surgery with limb salvage in 80% of this group. The overall survival was 38% at 2 years and 24% at 5 years but in patients without metastases at diagnosis these figures were 44% and 28% respectively. Poor prognostic factors for survival were: metastases at diagnosis, amputation or no operation, local recurrence, age over 60 and pathological fracture at presentation. We were unable to identify any group in whom chemotherapy appeared to have a survival benefit.

Dedifferentiated chondrosarcoma carries a dismal prognosis. Although 30% of patients received chemotherapy in this study we were not able to prove that it improved survival. Early diagnosis and complete surgical excision still offer the best prognosis for this condition.

Primary malignant bone tumours frequently arise in children close to the knee, hip or shoulder. Resection of the tumour will often require excision of the epiphysis and frequently one side of the involved joint. In these children an extendable endoprosthesis is usually required to allow for maintenance of limb length equality.

We have used 180 extendable endoprostheses in 176 children since 1975. The indication for use of an extendable prosthesis was if there was more than 30mm of growth remaining in the resected bone. The age of the patients ranged from 2 to 15 and 99 were boys. The sites of the endoprostheses used were: distal femur in 91, proximal tibia in 42, proximal femur in 11, total femur in 6 and proximal or total humerus in 26. 131 of the operations were for osteosarcoma and 34 for Ewing's.

Five types of lengthening mechanism have been used. Two designs used a worm screw gear, one type used a C collar, one type a ball bearing mechanism and the latest uses a non invasive lengthening system whereby a motor inside the prosthesis is activated by an electromagnetic field.

Of the 176 patients, 59 have died and of the remainder, 89 have reached skeletal maturity. 19 patients had an amputation, 11 due to local recurrence and 8 due to infection. The risk of infection was 19% in surviving patients. Most of the skeletally mature had equal leg lengths. The average number of operations was 11 but ranged between 2 and 29. Most operations were for lengthening but younger children always needed revisions of the prosthesis. Functional scores were 77%.

Extendable endoprostheses are demanding both for the patient and the surgeon. The high complication rate should be decreased by non invasive lengthening prostheses.

All patients referred to our unit with previously untreated metastatic renal cancer were included in this review. We investigated likely prognostic factors including age, sex, site, synchronous or metachronous metastasis, stage of the disease and the type of treatment received.

From 1976 until 2004, a total of 198 patients were treated by our unit for renal metastases. 15 patients were excluded because they were referred after failure of previous treatment or only had advice. 96 patients were already known to have renal metastasis with their diagnosis having been made between 0.2 and 17 years from the diagnosis of primary cancer (mean 4 years). 33 patients presented to us with a pathological fracture and were found to have renal cancer. A total of 54 patients had multiple metastases and 129 had a solitary metastasis. The cumulative survival from the time of diagnosis of the bone metastasis is 70 percent at 1 year, 40% at 3 years and 18% at 5 years. In patients with a solitary metastasis, the overall survival was 74% at 1 year and 45% at 3 years, whereas in patients with multiple metastases it was 55% at 1 year and 22% at 3 years. (p=0.02) In patients with a solitary metastasis treated by excision of the metastasis, the survival at 1 year was 86% as compared to 38% for those that were treated with just a local procedure. Cox multivariate analysis shows that survival was better in those with solitary metachronus metastasis who underwent a radical procedure.