We investigated the clinical outcome of internal
fixation for pathological fracture of the femur after primary excision of
a soft-tissue sarcoma that had been treated with adjuvant radiotherapy. A review of our database identified 22 radiation-induced fractures
of the femur in 22 patients (seven men, 15 women). We noted the
mechanism of injury, fracture pattern and any complications after
internal fixation, including nonunion, hardware failure, secondary
fracture or deep infection. The mean age of the patients at primary excision of the tumour
was 58.3 years (39 to 86). The mean time from primary excision to
fracture was 73.2 months (2 to 195). The mean follow-up after fracture
fixation was 65.9 months (12 to 205). Complications occurred in
19 patients (86%). Nonunion developed in 18 patients (82%), of whom
11 had a radiological nonunion at 12 months, five a nonunion and
hardware failure and two an infected nonunion. One patient developed
a second radiation-associated fracture of the femur after internal
fixation and union of the initial fracture. A total of 13 patients
(59%) underwent 24 revision operations. Internal fixation of a pathological fracture of the femur after
radiotherapy for a soft-tissue sarcoma has an extremely high rate
of complication and requires specialist attention. Cite this article:
Previously, we showed that case-specific non-linear
finite element (FE) models are better at predicting the load to failure
of metastatic femora than experienced clinicians. In this study
we improved our FE modelling and increased the number of femora
and characteristics of the lesions. We retested the robustness of
the FE predictions and assessed why clinicians have difficulty in
estimating the load to failure of metastatic femora. A total of
20 femora with and without artificial metastases were mechanically
loaded until failure. These experiments were simulated using case-specific
FE models. Six clinicians ranked the femora on load to failure and
reported their ranking strategies. The experimental load to failure
for intact and metastatic femora was well predicted by the FE models (R2 =
0.90 and R2 = 0.93, respectively). Ranking metastatic
femora on load to failure was well performed by the FE models (τ =
0.87), but not by the clinicians (0.11 <
τ <
0.42). Both the
FE models and the clinicians allowed for the characteristics of
the lesions, but only the FE models incorporated the initial bone
strength, which is essential for accurately predicting the risk
of fracture. Accurate prediction of the risk of fracture should
be made possible for clinicians by further developing FE models.
We report positive and negative factors associated with the most commonly-used methods of reconstruction after pathological fracture of the proximal femur. The study was based on 142 patients treated surgically for 146 metastatic lesions between 1996 and 2003. The local rate of failure was 10.3% (15 of 146). Of 37 operations involving osteosynthetic devices, six failed (16.2%) compared with nine (8.3%) in 109 operations involving endoprostheses. Of nine cases of prosthetic failure, four were due to periprosthetic fractures and three to recurrent dislocation. In the osteosynthesis group, three (13.6%) of 22 reconstruction nails failed. The two-year risk of re-operation after any type of osteosynthesis was 0.35 compared with 0.18 after any type of endoprosthetic reconstruction (p = 0.07). Endoprosthetic reconstructions are preferable to the use of reconstruction nails and other osteosynthetic devices for the treatment of metastatic lesions in the proximal third of the femur.
