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|TOPIC OF THE ISSUE: EDITORIAL
|Year : 2012 | Volume
| Issue : 2 | Page : 198-199
Comparative study of two laminoplasty techniques: A missed opportunity
Department of Neurological Sciences, Christian Medical College, Vellore, India
|Date of Submission||12-Sep-2011|
|Date of Decision||04-Oct-2011|
|Date of Acceptance||07-Nov-2011|
|Date of Web Publication||19-May-2012|
Department of Neurological Sciences, Christian Medical College Hospital, Vellore-632 004
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Rajshekhar V. Comparative study of two laminoplasty techniques: A missed opportunity. Neurol India 2012;60:198-9
Wang et al,  report on a comparative study of two cervical laminoplasty techniques, the traditional Hirabayashi "open door" technique (Group A) and a instrumented technique using "centerpiece" titanium plates (Group B), in patients with cervical spondylotic myelopathy. The main difference in the two techniques is that in the instrumented technique an implant ("centerpiece") is used to ensure that cervical canal widening is maintained (the "door" is kept open). This was a cohort study involving 50 patients with alternate patients being allocated to the traditional or instrumented surgery arms. Following surgery, the authors found a significant improvement in the functional status [measured using the Japanese Orthopedic Association (JOA) score] of the patients in both groups. The improvement in the JOA scores was similar in the two groups. Thus both surgical techniques are equally effective in achieving decompression of the cord.
There were, however, significant differences in other outcome parameters that the authors studied. Notably, patients in Group B (instrumented group) had better neck pain outcomes, better quality of life outcomes (measured using Short Form 36) and better maintenance of cervical spine lordosis after surgery. The authors were unable to clearly explain the differences in the neck pain outcomes in the two groups. They speculated that the suturing of the laminae on to the articular capsules of the facet joints, loss of lordosis and prolonged immobilization could be the possible reasons for the worse neck pain outcome in Group A patients. Patients in Group A were prescribed the collar for 6 weeks whereas those in Group B were asked to wear the collar for 2 weeks only. It is conceivable that prolonged collar use led to a wasting and weakness of the cervical paraspinal muscles which manifested in the form of increased neck pain. In all probability this is the likely cause for the worse neck pain outcome in Group A patients. The authors also could not convincingly explain the differences in the quality of life outcomes and maintenance of the cervical lordosis. It is possible that the loss of cervical lordosis was also related to the prolonged immobilization of the neck in Group A patients with consequent paraspinal muscle weakness and wasting. Therefore, the neck pain and sagittal alignment outcome in patients undergoing the traditional non-instrumented laminoplasty can probably be improved with a reduction in the duration of neck immobilization after surgery.
When comparing subjective outcome variables such as pain and quality of life in studies comparing a traditional technique with a "new" technique, one must guard against unintended biases on the part of the patient and the surgeon especially when the "new" technique involves expensive equipment such as implants. Benzel  gives one plausible explanation for bias toward better subjective outcome reporting by patients who undergo a "new" surgical technique in randomized trials. Patients enter randomized studies hoping to be allotted to the "new" and expensive technique arm of the study. Consequently, those allotted to the traditional technique (control arm) are usually disappointed and this might be reflected in their relatively poorer perception of the outcome (pain, quality of life). This could explain the dissonance between the objective and subjective outcomes in comparative studies of surgical techniques. Such dissonance is seen in this study also where the objective outcome (JOA scores) were comparable between the two groups whereas the subjective outcomes (neck pain, quality of life scores) were better in the "new" instrumented technique group. This is not to suggest that the entire difference in the subjective outcomes was due to the aforementioned bias but it could also be a factor.
The most noteworthy difference between the two groups was the rate of re-operation for recurrence of the cervical cord compression. Three patients, all in Group A, required an anterior decompression surgery for recurrent symptoms of cord compression. While this outcome could reflect an improper technique in performing the traditional surgery, to my mind, this is the most significant outcome difference favoring the instrumented technique. Surprisingly, the authors have not highlighted this difference in the Abstract or in the Discussion parts of their article.
Although the authors are to be congratulated for performing a good prospective cohort study with standardized outcome variables, they missed an opportunity to perform a more robust study, namely a randomized study, which would have provided a higher level of evidence. The allocation of patients was "pseudo-randomized", no sample size calculations were performed prior to the study and the follow-up duration was relatively short (mean 21.5 months for Group A and 18.2 months for Group B). All these deficiencies in their study lead to a dilution of the strength of their findings.
| » References|| |
|1.||Wang L, Song Y, Liu L, Liu H, Kong Q, Li T, et al. Clinical outcomes of two different types of open-door laminoplasties for cervical compressive myelopathy: A prospective study. Neurol India 2012;60: 210-6. |
|2.||Benzel EC. Cervical disc arthroplasty compared with allograft fusion. J Neurosurg Spine 2007;6:197. |