Introduction

Rotational or axial alignment is an important concept in total knee surgery. Malrotation of the femoral component can lead to patellofemoral maltracking, pain and stiffness. In reconstruction surgery of the knee, achievement of correct rotation is even more difficult because of the lack of anatomical landmarks. The linea aspera is often the only remaining landmark, but its reliability is questionable.

Introduction

Systemic metal ion monitoring (Co;Cr) has proven to be a useful screening tool for implant performance to detect failure at an early stage in metal-on-metal hip arthroplasty. Several clinical studies have reported elevated metal ion levels after total knee arthroplasty (TKA), with fairly high levels associated with rotating hinge knees (RHK) and megaprostheses¹. In a knee simulator study, Kretzer², demonstrated volumetric wear and corrosion of metallic surfaces. However, prospective in vivo data are scarce, resulting in a lack of knowledge of how levels evolve over time. The goal of this study was to measure serum Co and Cr levels in several types TKA patients prospectively, evaluate the evolution in time and investigate whether elevated levels could be used as an indicator for implant failure.

Systemic metal ion monitoring (Co;Cr) has proven to be a useful screening tool for implant performance to detect failure at an early stage in metal-on-metal hip arthroplasty. Several clinical studies have reported elevated metal ion levels after total knee arthroplasty (TKA), with fairly high levels associated with rotating hinge knees (RHK) and megaprostheses¹. In a knee simulator study, Kretzer², demonstrated volumetric wear and corrosion of metallic surfaces. However, prospective in vivo data are scarce, resulting in a lack of knowledge of how levels evolve over time. The goal of this study was to measure serum Co and Cr levels in several types TKA patients prospectively, evaluate the evolution in time and investigate whether elevated levels could be used as an indicator for implant failure.

The study was conducted at Ghent University hospital. 130 patients undergoing knee arthroplasty were included in the study, 35 patients were lost due to logistic problems. 95 patients with 124 knee prostheses had received either a TKA (primary or revision) (69 in 55 patients), a unicompartimental knee arthroplasty (7 UKA), a RHK (revision −7 in 6 patients) or a megaprosthesis (malignant bone tumours − 28 in 27 patients). The TKA, UKA and RHK groups were followed prospectively, with serum Co and Cr ions measured preoperatively, at 3,6 and 12 months postoperatively. In patients with a megaprosthesis, metal ions were measured at follow-up (cross-sectional study design).

In primary knees, we did not observe an increase in serum metal ion levels at 3, 6 or 12 months. Two patients with a hip arthroplasty had elevated preTKA Co and Cr levels. There was no difference between unilateral and bilateral knee prostheses. In the revision group, elevated pre-revision levels were found in 2 failures for implant loosening. In both cases, ion levels decreased postoperatively. In revisions with a standard TKA, there was no significant increase in metal ions compared to primary knee arthroplasty. RHK were associated with a significant increase in Co levels even at short-term (3–12 months). The megaprosthesis group had the highest metal ion levels and showed a significant increase in Co and Cr with time in patients followed prospectively. With the current data, we could not demonstrate a correlation between metal ion levels, size of the implant or length of time in situ.

In primary knee arthroplasty with a standard TKA or UKA, metal ion levels were not elevated till one year postoperatively. This suggests a different mechanism of metal ion release in comparison to metal-on-metal hip arthroplasties. In two cases of revision for implant loosening, pre-revision levels were elevated, possibly associated with component wear, and decreased after revision. With RHK, slightly elevated ion levels were found prospectively. Megaprostheses had significantly elevated Co and Cr levels, due to corrosion of large metallic surfaces and/or wear of components which were not perfectly aligned during difficult reconstruction after tumour resection. Further research is needed to assess the clinical relevance of metal ion levels in knee arthroplasty.

Limb salvage is the gold standard to treat sarcoma patients, but bone stock should be retained for the future, as many of these patients are young and active.

For this observational clinical study, 107 patients that presented with 108 malignant or locally aggressive benign bone tumours were treated by wide en-bloc resection of the affected bone, extracorporeal irradiation with 300 Gy to eradicate the tumour, and reimplantation of the bone as an orthotopic autograft. The irradiated bone was rigidly fixed to the remaining bone with classical intramedullary or extramedullary osteosynthesis material. We made a subdivision between intercalary, composite and osteoarticular grafts. The pelvis was considered a third separate entity, as it was considered both an intercalary and an osteoarticular graft when the acetabulum was involved.

The incidence of local recurrence with the use of an orthotopic autograft comprised the primary endpoint of this study. Secondary endpoints: preservation of bone stock with graft healing and evaluation of factors that determine preservation.

No local recurrences could be detected in the irradiated grafts. One local recurrence was detected in the surrounding soft tissue. At 5 years follow-up, graft healing occurred in 64% of cases, providing stable and lasting reconstruction. Eleven percent of the grafts had to be removed due to several incidents, but none could be proven significant. All patient subgroups displayed comparable results. Early infection appeared to be a significant determinant for the development of pseudarthrosis. Pelvic reconstructions showed a worse outcome. According to the results, guidelines for indications and surgical guidelines, such as rigid fixation and bridging of the graft, are proposed for using this technique. In general sarcoma resection, extracorporeal irradiation, and reimplantation provides a stable and lasting reconstruction with preservation of bone stock.

Detection of local recurrence after sarcoma resection can be impaired by metal implants locally, or by the patient ‘s general condition. Metal implants cause severe distortion and scattering of either MRI or CT data acquisition. Therefore the detection of local recurrences in proximity of heavy metal implants such as prostheses or osteosynthesis material can be difficult. Patient related conditions, e.g. renal insufficiency, allergy, claustrophobia, may completely prohibit the use of contrast media or even a scan itself.

Ultrasound provides several advantages, and can be used for different indications in sarcoma patients. Patient related conditions prove no obstacle for this technique. Currently our indications are local follow-up after soft-tissue sarcoma resection and evaluation of regional lymph nodes, detection of local recurrence of bone sarcoma in proximity of metal implants, and amputation stump evaluation.

We describe a patient study population of 103 patients. Seventeen had only diagnostic and staging ultrasound, four had an evaluation of their amputation stump, 24 were followed after resection of a soft-tissue sarcoma, and 58 were followed by this method after sarcoma resection and implantation of metallic implants. Evaluation modalities are described according to the indications.

Results: We have detected nine local recurrences, and four patients with suspect lymph nodes had a biopsy of which half showed malignant tumour cells. Infection and inflammation around metallic implants can be evaluated, the technique also allowing placement of drains in infected seromas in irradiated regions. It should be emphasised that reliable results can only be achieved if a baseline ultrasound is performed, followed by subsequent studies at regular intervals.

Purpose: The purpose of this study was to analyse results of the inverted shoulder prosthesis (Grammont Delta III prosthesis) for surgical treatment of malignant tumours of the upper portion of the humerus in twelve patients.

Material and methods: Twelve patients were treated in two centres (six patients each). There were five women and seven men, mean age 51 years (34–69). Seven had a primary tumour and five had a unique secondary tumour. All tumours were implanted after Malawer I resection (IA four case and IB two cases), with an autologous bone graft using resected irradiated bone. All resections were wide as needed for healthy margins. Resection extended to the lower fourth of the humerus in four cases, to between the lower fourth and third in six cases and to the upper third or less in two cases. Ten patients were reviewed at a mean follow-up of 22 months (7–60) to assess clinical function (Constant score) and radiographic results. Two patients with a unique secondary tumour died within the six months following surgery due to progression of the primary tumour.

Results: The mean Constant score was 58.75 (30–81.1). Weighted for age and gender, the result was 70.3% (32.6–82). Five sedentary patients were able to resume their former activities (1/2). Radiographically, there were two resorptions of the autograft, two glenoid lucent lines that did not progress, four notches in the column, and three Sneppen 1 calcifications. Mechanically, there were no prosthesis dislocations in patients whose resection extended to the lower fourth of the humerus, four dislocations in the one-fourth one-third group (2/6) and two dislocation in the upper group (2/2).

Discussion, conclusion: Functional and radiographic outcome after anatomic prosthesis implantation for surgical treatment of malignant tumours of the upper portion of the humerus was directly related to the status of the rotator cuff. The Grammont Delta III inverted prosthesis provided satisfactory functional and radiographic results in this indication after Malawer I resection, irrespective of the rotator cuff sacrifice. The risk of prosthesis instability appeared to be related to the extent of the humeral resection required for cancerological cure. For patients who undergo resection of one third or more of the humerus, muscle plasty should be associated.