TO THE EDITOR:
I read with interest "Posterior Decompression and Stabilization for Spinal Metastases. Analysis of Sixty-seven Consecutive Patients" (79-A: 514-522, April 1997), by Bauer.
My colleagues and I reviewed a similar number of patients (seventy) who had an operation to treat spinal metastases2. Partly because our study commenced earlier, a wider variety of treatment methods were used for our patients. Eighteen of our patients had posterior instrumentation with Hartshill or Luque rectangles and sublaminar wires.
It is always difficult to compare studies by different authors, particularly when the conventional method of presenting data has not been followed. In the report by Bauer, the data in Table II are not presented in a standard Frankel grid. Nevertheless, as far as can be determined, there does not seem to be a great difference between the two approaches. I do not mean to dismiss the value of posterior instrumentation with pedicle screws; indeed, some of our patients2 were managed with this approach. However, I am concerned that the implied conclusion, that fixation with pedicle screws represents the only valid method of posterior instrumentation for vertebral metastases, is not supported by the literature.
S. J. Krikler, Ph.D., F.R.C.S.(Orth): Department of Orthopaedic Surgery, Coventry and Warwickshire Hospital, Coventry CV1 4FH, England
Dr. Bauer replies:
The study by Krikler et al. did not include seventy patients who had a metastasis as sixteen patients had a primary bone tumor2. The immediate postoperative changes in neurological function in my patients were noted in the text, and I thought that a table would have been superfluous. Instead, I chose to present the data regarding neurological function during follow-up (Table II). The results regarding neurological function do appear to be similar in these two studies. It is not meaningful to compare survival because survival is mostly dependent on the site of the primary tumor and the extent of the metastatic disease1. In my study, the most common primary lesion was carcinoma of the prostate. In the study by Krikler et al., the most common primary lesion was myeloma, which is associated with a more favorable prognosis.
I definitely agree with Dr. Krikler that pedicle screw fixation is not the only valid method of stabilization for patients who have a metastatic lesion involving the spine. I did not intend to advocate this method of fixation, which is associated with important risks such as damage to dural structures and loosening of the implant. I prefer to use hooks in most patients, and I use pedicle screws only in the middle and caudad regions of the lumbar spine. In my practice, fewer than 20 per cent of patients who are managed operatively for cancer have a lesion in that area.
Henrik C. F. Bauer, M.D., Ph.D.: Oncology Service, Department of Orthopedics, Karolinska Hospital, S-171 76 Stockholm, Sweden