Departamento de Cirugía,. Hospital de Clínicas “José de San Martín”,. Av. Córdoba 2351-9° piso,. 1120 Buenos Aires, Argentina. Mailing address: 1 José E.
Crit Rev Neurosurg (1997) 7: 355–359 © Springer-Verlag 1997
Juan José María Mezzadri Roberto Zaninovich Armando Basso
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Do we always need an interbody graft after anterior cervical disc surgery?
Introduction J. J. M. Mezzadri1 · R. Zaninovich A. Basso (½) División de Neurocirugía, Departamento de Cirugía, Hospital de Clínicas “José de San Martín”, Av. Córdoba 2351-9° piso, 1120 Buenos Aires, Argentina Mailing address: José E. Uriburu 1089-7° B, 1114 Buenos Aires, Argentina
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Since the first reports of Robinson and Smith (1955), Dereymaeker and Muller (1956) and Cloward (1958), cervical disk disease has been treated increasingly frequently through an anterior cervical approach. There are several reasons: minimal dissection through natural tissue plains, little damage to normal structures, effective disc excision, few complications and quick recovery. Grafting was considered an essential step in the procedure to promote osteophyte resorption, re-establish foraminal and disc space height and to maintain stability. However, obtention and insertion of a graft produced several complications: pseudoarthrosis, kifosis, aseptic necrosis, discitis, extrusion, hip pain and infection. This led some authors to avoid grafting. During the 1960s the first reports on discectomy without fusion were published [Hirsch C (1960) Acta Orthop Scand 30: 172–186; Hirsch C, et al (1964) J Bone Joint Surg Am 46:1811–1821]. The clinical results were similar to those reported with discectomy and fusion [Cloward RB (1958) J Neurosurg 15:602–617; Dereymaeker A, Muller J (1958) Rev Neurol 99: 597–615; Smith GW, Robinson RA
(1958) J Bone Joint Surg Am 40:617–624]. Discectomy without fusion was further improved by the use of microsurgical techniques [Hankinson HL, Wilson CB (1975) J Neurosurg 43:452–456; Robertson JT (1973) Clin Neurosurg 20: 259–261], and nowadays its use has extended to the treatment of radiculopathy and myelopathy caused either by hard or soft cervical discs [Klaiber S, et al (1992) Acta Neurochir (Wien) 114:36–42; Laus M, et al (1992) Chir Organ Mov 77: 101–109; Selladurai BM (1992) J Neurol Neurosurg Psychiatry 55: 604–608; Hadley MN, Sonntag VK (1993) Neurosurg Clin North Am 4:45–52]. In spite of the fact that it has been used for the last 37 years there is still controversy about it [Sonntag VK, Klara P (1996) Spine 21:1111–1113]. Is fusion necessary to promote spur resorption? The absence of a graft would decrease the foraminal area up to a point in which the root would be compressed? Can discectomy without fusion produce instability? In the selected articles reviewed below, these questions are discussed in an attempt to define the role of the interbody graft.
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[1] Appearances of posterior osteophytes after sound anterior interbody fusion in the cervical spine: a high definition computed myelographic study Neuroradiology (1993) 35:227–228
Information. This is a retrospective study of 78 patients who were re-assessed with high-definition computed tomographic myelography (CTM) because of persistent or recurrent cord or radicular symptoms after cervical spine surgery. The authors paid particular attention to assessing the remodelling of residual osteophytes. Only 38 cases with anterior interbody fusion had preand postoperative CTM for comparison; these cases had definite sound fusions. The mean time between fusion and postoperative CTM was 18.8 months. The authors could not find any case of definite remodelling of all or part of an osteophyte. Analysis. This study could be biased, as the cohort of patients was composed only of those who returned with recurrent or persistent symptoms. Nevertheless, it was clear that anterior interbody fusions reassessed with CTM failed to produce spur resorption. When the aim is to alleviate root or cord compression and improve function, osteophytes must be completely removed.
[2] Changes in the cervical foraminal area after anterior discectomy with and without a graft Neurosurgery (1994) 34:93–96
P=0.0001, respectivelly). In group B there was a median decrease of the foramen on the left and right sides of 0.13 (P=0.0005) and 0.12 (P=0.0005), respectivelly. The magnitude of the change in the foraminal area did not differ significantly between the two groups (P=0.908 left side – P=0.862 right side). Also, there was no statistically significant difference in clinical outcome between the groups (P=1.000). The authors conclude that the comparison between the magnitude of change in the foraminal area and clinical outcome was not significant when both groups were examined; grafting did not support the theory of foraminal patency. Analysis. The authors have shown that the insertion of a graft increases foraminal area, and its absence decreases it in both cases significantly. These findings would favour reports that advocate the use of a graft. However, the comparison between the changes (increase/decrease) and outcome was not significant, showing that the graft was probably unnecessary. The median decrease of the right and left foraminal area was 0.12 cm2 (20%) and 0.13 cm2 (19%), respectively. These values were low and as roots occupy only a third of the foraminal area, probably the decrease produced by the discectomy had no compressive effects.
[3] Anterior cervical discectomy with and without fusion. Results, complications, and long-term follow-up Spine (1994) 19:2343–2347
Information. This is a prospective, non-randomized comparison of the changes in the cervical foraminal area after discectomy with and without a graft. There were 19 patients divided into two groups. After anterior cervical discectomy, patients in group A (7 cases, 12 discectomies, 24 foramina examined) underwent grafting and those in group B (12 cases, 12 discectomies, 24 foramina examined) did not. All patients had plain oblique cervical spine films done with the same technique preand postoperatively. The area (cm2) of the cervical foramen was measured with a two-dimensional digital planimeter. The change in the area of the foramen after discectomy was assessed by the Wilcoxon signed rank test. Comparisons and outcome between both groups were done with the Wilcoxon rank sum tests. In group A there was a median increase of the foramen on the left and right sides of 0.11 (P=0.0005 and
Information. This is a retrospective study of 126 patients consecutively treated for cervical radiculopathy with either simple anterior cervical discectomy (62 cases) or anterior cervical discectomy and fusion (64 cases). The clinical and pathological data were similar in both groups, discectomy was complete and posterior osteophytes were not removed. Fusion was assessed by dynamic cervical radiographs. Short-term outcome was assessed by Odom’s criteria. Long-term evaluation was done by telephone interview. Of the 62 patients without fusion, 4 had complications and 1 required reoperation for persistent pain and kyphosis. The 64 patients with fusion had 16 complications, 15 of which were graft-related: 2 required reoperation (1 for debridement of graft infection and 1 to
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replace a slipped graft). Osseous fusion was present in 60% of the cases with simple discectomy and in 90% of the cases with discectomy and graft. In the short-term follow-up the fusion group had a significantly more rapid resolution of arm (P
