Megaprosthesis versus Condyle-sparing intercalary allograft: distal femoral sarcoma

Abstract

Although functionally appealing in preserving the native knee, the condyle-sparing intercalary allograft of the distal femur may be associated with a higher risk of tumor recurrence and endoprosthetic replacement for malignant distal femoral bone tumors. We therefore compared the risk of local tumor recurrence between patients in these two types of reconstruction groups. We retrospectively reviewed 85 patients (mean age, 22 years; range, 4-82 years), 38 (45%) of whom had a condyle-sparing allograft and 47 (55%) of whom had endoprostheses. The minimum followup for both groups was 2 years (mean, 7 years; range, 2-19 years). Local recurrences occurred in 11% (five of 47) of the patients having implants versus 18% (seven of 38) of the patients having allografts. Using time to local recurrence as an end point, the Kaplan-Meier survivorship of the implant group was similar to that of the condyle-sparing allograft group at 2, 5, and 10 years (93% versus 87% at 2 years, 87% versus 81% at 5 years, and 87% versus 81% at 10 years, respectively). The condyle-sparing allograft procedure offers the potential advantage of retaining the native knee in a young patient population while incurring no greater risk of local recurrence as those offered the endoprosthetic procedure.

Level of evidence: Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Fig. 1

This flow chart represents our inclusion criteria for this study as well as describes the types of revision procedures patients underwent.

Fig. 2

An anteroposterior (AP) radiograph demonstrates a 1-cm step cut at the distal and proximal osseous graft junctions of the allograft and secured with an antegrade intramedullary nail. Note the retrograde crossing screws placed in the medial and lateral condyle to provide distal condyle fixation in addition to fixation provided by the femoral rod.

Fig. 3

An anteroposterior (AP) radiograph shows the retrograde crossing screws placed in the medial and lateral condyle, the “condyle-sparing” approach in addition to the fixation provided by the intramedullary nail with a distal interlocking screw. There is nonunion of bone at the proximal junction.

Fig. 4

The Kaplan-Meier survival curve demonstrating similar time to local recurrence between the implant group and the condyle-sparing (CS) allograft group at 2, 5, and 10 years: 93% versus 89% at 2 years, 87% versus 81% at 5 years, and 87% versus 81% at 10 years, respectively.

Fig. 5

The Kaplan-Meier overall survivorship (end point was date of death or date of last followup) showing similar survival of the implant group versus the condyle-sparing (CS) allograft group: 94% versus 95% at 2 years, 75% versus 86% at 5 years, and 72% versus 72% at 10 years, respectively.

Fig. 6

The Kaplan-Meier survivorship showing similar survival of the surgical reconstruction using revision as an end point for the allograft versus implant groups: 92% versus 76% at 2 years, 70% versus 64% at 5 years, and 53% versus 36% at 10 years, respectively.