Reconstruction of the limb with a massive endoprosthesis after tumour resection is associated with a risk of aseptic loosening. A number of factors influence this risk. These include:
- anatomical site
- length of resection
- muscle resection
- possibly the use of a fixed hinge knee rather than a rotating hinge knee
- the use of a hydroxyapatite collar
The risk of aseptic loosening is likely highest in the distal femur (13.6%) compared with the proximal femur (11%) and pelvis (7%), but in this paper, implants were also revised for other reasons, including deep infection (1).
(1) Endoprosthetic Reconstruction for the Treatment of Musculoskeletal Tumours of the Appendicular Skeleton and Pelvis.Jeys LM, Kulkarni A, Grimer RJ, Carter SR, Tillman R, Abudu A. J Bone Joint Surg Am. 2008; 90: 1265-1271.
Infection remains a major problem after major tumour resection and endoprosthetic reconstruction. Placing a large metal implant into a wound which has typically been open for several hours, in an immunocompromised patient is associated with higher infection rates than for other procedures.
In the paper by Jeys et al. , the overall rate of infection was 11.0%, most frequently with a coagulase negative staphylococcus. The risk varies significantly with anatomical site. For example, because of the limited skin cover, resection of the proximal tibia has traditionally been associated with high infection rates. The routine use of a gastrocnemius pedicled flap to improve soft tissue cover has improved this risk. Reconstruction of the pelvis has also traditionally been associated with a high infection rate (23%) compared with other sites (proximal femur 6.7%, distal femur 10.3%). Other risk factors include the use of radiotherapy, secondary patellar resurfacing, and the use of an extendable implant. Deep infection may require a secondary amputation.
Interestingly, there is evidence that deep infection is associated with improved survival in patients with osteosarcoma, likely through stimulation of the immune system. Jeys et al showed a 10-year survival for patients with osteosarcoma who had a deep infection within the first year post-resection of 84.5% compared to 62.3% in the non-infected group. Improved survival has also been shown in osteosarcoma with the use of Mifamurtide (a synthetic immune stimulant). Read more about Mifamurtide.
Strategies for reducing the rate of infection include:
- screening the patient for infection preoperatively (central lines have the potential to increase the rate of infection)
- repeating the antibiotic dose during long procedures, especially where there has been significant blood loss
- re-draping and re-gowning after tumour resection and before placing the implant
- using silver coated implants
- ensuring the implant is well covered with muscle and fascia as well as skin, given the high risk of wound complications after tumour surgery.
Periprosthetic infection in patients treated for an orthopaedic oncological condition. Jeys LM, Grimer RJ, Carter SR, Tillman RM. J Bone Joint Surg Am. 2005;87: (842-849).
Post operative infection and increased survival in osteosarcoma patients: are they associated? Jeys LM, Grimer RJ, Carter SR, Tillman RM, Abudu A. Ann Surg Oncol. 2007;14(10):2887-95.
The major complications particular to endoprosthetic reconstruction of the limb following tumour resection include:
- aseptic loosening
- implant fracture
These are in addition to other complications associated with major tumour resection, regardless of the kind of reconstruction, which include:
- wound complications
- neurological injury
- vascular injury
Local recurrence of tumour might be considered a failure of local therapy, rather than a complication.