Role of corpectomy in cervical spondylosis

Preventing Construct Subsidence Following Cervical Corpectomy: The Bump-stop Technique

Cervical corpectomy is a viable technique for the treatment of multilevel cervical spine pathology. Despite multiple advances in both surgical technique and implant technology, the rate of construct subsidence can range from 6% for single-level procedures to 71% for multilevel procedures. In this technical note, we describe a novel technique, the bump-stop technique, for cervical corpectomy. The technique positions the superior and inferior screw holes such that the vertebral bodies bisect them. This allows for fixation in the dense cortical bone of the endplate while providing a buttress to corpectomy cage subsidence. We then discuss a retrospective case review of 24 consecutive patients, who were treated using this approach, demonstrating a lower than previously reported cage subsidence rate.

[PEEK cage fusion after anterior cervical corpectomy : Clinical and radiological results in patients with spondylotic myelopathy]

BACKGROUND

Anterior cervical corpectomy and fusion (ACCF) has become a standard procedure for patients with spondylotic myelopathy due to multisegmental stenosis of the cervical canal. In addition to the fusion technique using autogenous bone grafts and titanium implants, synthetic polyetheretherketone (PEEK) cages have been used increasingly during the last years. However, limited evidence on the clinical and radiological results of PEEK cages for ACCF exists in the literature. The study presented here is the largest series to date reporting clinical and radiological outcome as well as complication rates after one to three-level ACCF using PEEK cages augmented by an anterior plate-screw osteosynthesis.

MATERIALS AND METHODS

Retrospective study on 101 patients after stand-alone PEEK cage-ACCF with a minimum follow-up of 6 months. The number of hardware failures and implant-related surgical revisions were determined. The rate of subsidence and fusion and the course of lordotic alignment were analysed. The neck disability index (NDI) and the European myelopathy score (EMS) were assessed.

RESULTS

Screw complications were detected in 8/101 cases and 3 cases of cage dislocation occurred, resulting in an overall implant related revision rate of 2.9 % (all revision cases showed cage dislocation). The rate of cage subsidence >3 mm was 12 % and solid fusion was achieved in 82 % of the patients. NDI, EMS and lordotic alignment improved significantly.

CONCLUSIONS

PEEK cages are a safe and effective alternative to titanium cages or autogenous bone graft for ACCF. Further randomized evaluation of different fusion techniques in ACCF is still necessary.

Long-term results after cervical anterior fusion using an autologous bone graft (Williams-Isu method)

OBJECTIVE

Cervical anterior fusion with autologous bone grafts (Williams-Isu method) is a modified, accepted method to treat spinal degenerative disease. Here we report minimum 10-year outcomes.

METHODS

Of 101 patients we treated by cervical anterior fusion using the Williams-Isu method, 50 patients were followed up for a mean of 177 months. Among the 51 patients lost to long-term follow-up 12 were contacted by telephone; they reported their condition as good and none required reoperation. We evaluated their clinical outcomes on the Japan Orthopedic Association (JOA) score and assessed radiologic findings.

RESULTS

The average JOA score was 12.5 preoperatively, 15.9 at 2 years after surgery (recovery rate 74.9%), and 15.5 at final follow-up (recovery rate 67.0%). All 5 reoperated patients were treated on the level adjacent to the original lesion. Radiographically, cervical alignment changed from 12.5° to 9.0°, the fused segment angle changed from 5.4° to -0.6°. Although worsening of the fused segment angle did not affect the clinical results, it did affect postoperative cervical sagittal alignment. Cervical alignment and range of motion (ROM) were not different between reoperated (group I) and nonreoperated patients (group II). Fused segment angle worsening was milder than expected in group I.

CONCLUSIONS

The long-term results after the Williams-Isu method were good. The fused segment angle loss of approximately 6° did not affect long-term outcomes although it did affect sagittal cervical alignment. Postoperative worsening of the fused segment angle and hyper ROM changes in the adjacent level were not related to the need for reoperation in our study.

Adjacent segment degenerative disease: is it due to disease progression or a fusion-associated phenomenon? Comparison between segments adjacent to the fused and non-fused segments

INTRODUCTION

The purpose of this study was to determine whether fusion causes adjacent segment degeneration or whether degeneration is due to disease progression.

MATERIALS AND METHODS

Eighty-seven patients that had undergone single level anterior cervical decompression and fusions with at least 5 years of follow-up were enrolled in this retrospective study. Segments adjacent to fusion levels (above or below) were allocated to group A, and all others were allocated to group B. Radiographic evaluations of adjacent level changes included assessments of; disc degenerative changes, anterior ossification formation, and segmental instability. The developments of new clinical symptoms were also evaluated.

RESULTS

In group A, adjacent segment degenerative change developed in 28 segments (16%) and two cases (2%) developed new clinical symptoms. In group B, adjacent segment degenerative change developed in 10 segments (3%), and two cases (0.7%) also developed new clinical symptoms. Additional operations were performed in one patient in each group.

CONCLUSION

Although, fusion per se can accelerate the severity of adjacent level degeneration, no significant difference was observed between adjacent and non-adjacent segments in terms of the incidence of symptomatic disease. The authors conclude that adjacent segment disease is more a result of the natural history of cervical spondylosis than the presence of fusion.

Detailed study of graft sinking and worsening of the fused segment angle in patients with cervical disease treated with the Williams-Isu method

Detailed changes involved in the worsening of the fused segment angle were assessed after application of the Williams-Isu method using autologous bone grafts from cervical vertebral bodies in 30 patients with cervical disease treated by single-level anterior fusion. The mean follow-up duration was 25.4 months. The fused segment angle was measured on serial radiographs. Whole cervical spine alignment changed from 12.8° to 9.9°. The alignment of the fused segment worsened by mean 3.3°. To elucidate the characteristics of worsening of the fused segment, the 30 patients were divided into 2 groups: Group I (n = 20) without and Group II (n = 10) with postoperative worsening of the fused segment. The loss in the fused segment angle was significantly greater in Group II (8.0°) than Group I (0.9°). Preoperative range of motion and disc height were significantly greater in Group II than Group I. Worsening of the fused segment angle occurred within 1 month in Group I, whereas stabilization was observed after 3 months in Group II. Graft subsidence was primarily posterior and inferior. Our results indicate that the preoperative range of motion and disc height of the fused segment must be considered to prevent worsening in that segment after anterior fusion. Such detailed information is useful for the selection and postoperative monitoring of patients eligible for treatment by the Williams-Isu method.

VERTEBRAL BODY REPLACEMENT SYSTEMS WITH EXPANDABLE CAGES IN THE TREATMENT OF VARIOUS SPINAL PATHOLOGIES

OBJECTIVE

Vertebral body reconstruction after corpectomy has become a common surgical procedure. The authors describe a prospectively followed case series of patients treated with expandable cages for various indications.

METHODS

Sixty patients underwent single or multilevel corpectomy for degenerative stenosis (13 patients), herniated disc (7 patients), deformity (14 patients), traumatic fracture (3 patients), infection (1 patient), or tumor (22 patients). Six different expandable vertebral body systems were used in the cervical spine (41 patients), thoracic spine (15 patients), and lumbar spine (4 patients). All patients were evaluated clinically and radiographically.

RESULTS

Thirty-nine patients underwent single-level corpectomy, 18 patients underwent two-level corpectomy, and 3 patients underwent three-level corpectomy. Anterior reconstruction alone was performed in 30 patients; circumferential reconstruction was performed in 30 patients, 9 of whom underwent reconstruction through a posterior approach only. At the time of the final follow-up examination (mean, 9 mo), the Nurick grade improved significantly. Ninety-five percent of the patients maintained or improved their Frankel score and 67% had good clinical results. The regional angulation was corrected significantly (4.0 ± 9.0 degrees, P = 0.002), and the segment height increased significantly (3.5 ± 8.0 mm, P = 0.002). Bony fusion was achieved in 93% of the cases. Subsidence was documented in nearly half of the patients (1.4 ± 2.0 mm) and was reduced after circumferential fusion (0.9 ± 1.9 mm, P = 0.08). Eighteen patients (30%) had complications and 12 patients (20%) underwent revision surgery.

CONCLUSION

Expandable vertebral body replacement systems can provide solid anterior column constructs with restoration of height and sagittal alignment. Favorable clinical outcome was shown in most patients, although the complication and reoperation rates are rather high.

Adjacent segment disease after fusion for cervical spondylosis; myth or reality?

Cervical spondylosis is a common cause of radiculopathy and myelopathy, often treated by discectomy and interbody fusion. However, there has been a recent vogue for the use of artificial disc prostheses to decrease the risk of accelerated degenerative disease at adjacent levels. The short-term results of artificial disc replacements have been encouraging, but the long-term justification for using this new technology hinges on whether the incidence of adjacent segment disease decreases. It will also be necessary to demonstrate that movement at the operated levels is maintained and the incidence of device failure is low. We review the radiological, biomechanical and clinical evidence for adjacent segment disease, and the rationale for using artificial cervical disc replacements. There is presently insufficient evidence to justify the widespread use of artificial disc replacements in the treatment of cervical spondylosis, but neither is there sufficient evidence to criticize their use. Present evidence suggests that adjacent segment disease is partly due to the natural history of spondylotic disease and partly due to cervical fusion. Randomized trials are required to ascertain whether the incidence of adjacent segment disease changes with the use of artificial disc replacements in the long term. Indications for the use of artificial discs are presently unclear, but disc replacements might be recommended for 'young' patients who require an anterior cervical discectomy, with good ranges of neck movements, and an awareness of the satisfactory short-term results, but lack of long-term outcome data, preferably within the limits of a clinical trial.

Cervical corpectomy with preserved posterior vertebral wall for cervical spondylotic myelopathy: a randomized control clinical study

STUDY DESIGN

Cervical corpectomy with preserved posterior vertebral wall (CPW) had been performed by the senior author (Y.W.) since 1999. A prospective study had been conducted to evaluate the efficacy of CPW since 2001.

OBJECTIVE

To validate the clinical outcome of CPW against conventional corpectomy (CC).

SUMMARY OF BACKGROUND DATA

Anterior surgical managements of cervical spondylotic myelopathy (CSM) include discectomy and corpectomy. Both have significant disadvantages, including low fusion rates and residual symptoms. A procedure incorporating multilevel discectomy, corpectomy with preserved posterior vertebral wall, autograft and plating was described. By keeping the posterior vertebral wall (PW), infringement of the vein plexus and spinal canal was avoided and more fusion site was available.

METHODS

From March 2001 to March 2004, 178 cases of CSM were randomized to undergo CPW (n = 89) or CC (n = 89). Arthrodesis was done with autogenous iliac bone graft or titanium cage supplemented with anterior self-lock plates in both groups. Operation time, blood loss, days of hospitalization, the numbers and types of complications, and preoperative and postoperative JOA scores were recorded. Fusion rate, segmental lordosis, and disc height were assessed by roentgenography. Three-dimensional reconstructions of CT scan were used to confirm fusion evidence.

RESULTS

Average operation time and blood loss decreased significantly in the CPW group (98.06 +/- 19.42 minutes, and 131.69 +/- 62.41 mL) as compared with those in the CC group (108.45 +/- 22.35 minutes, and 181.57 +/- 82.10 mL) (P < 0.05). There were 2 cases of epidural bleeding and 1 case of CSF leak in the CC group. Other complications were minor. JOA improvement scores were similar in both groups. Roentgenograms showed that the fusion rate was 100% at 6 months postoperatively in both groups. CT scans showed that PW fused with grafts and bone dust in cages. Improvement in segmental lordosis and disc height was similar in both groups.

CONCLUSION

CPW is a feasible procedure for anterior decompression and fusion, with safety, complete decompression, and high fusion rate, as long as indicative patients are selected.

Comparison of multisegment anterior cervical fixation using bone strut graft versus a titanium rod and buttress prosthesis: analysis of outcome with long-term follow-up and interview by independent physician

STUDY DESIGN

A retrospective study of 73 consecutive patients who underwent cervical corpectomy and anterior strut fixation over 3 or more disc levels between July 1989 and May 1999.

OBJECTIVE

To compare the efficacy of cervical spine fixation by autologous strut graft from iliac crest or fibula versus a titanium prosthesis without bone graft.

SUMMARY OF BACKGROUND DATA

Strut grafting after multilevel anterior cervical corpectomy remains a challenging procedure, with published dislocation rates from 0% to 71%, and nonunion from 0% to 54%. This paper describes a quicker and easier alternative to the use of a bone strut, imparting a very high degree of immediate spinal stability, and osseous integration equivalent to bone fusion.

METHODS

Thirty-eight bone-graft operations and 38 titanium prosthesis operations were performed on 73 patients between July 24, 1989 and May 20, 1999. Average follow-up was 53.2 months (range 19.8-134).

RESULTS

The group of patients who received the prosthesis was significantly older than the bone-grafted group and required significantly more segments excised, but operation times were significantly shorter than for the bone strut operation. The titanium prosthesis had a lower incidence of dislodgement in the early postoperative period (1/38 vs. 4/38 for bone struts) but a higher rate of late reoperation (4/38 vs. 1/38 for bone struts). The SF-36 scores in the domain of Physical Function (only) were significantly higher in the bone-grafted group (P = 0.016, Mann Whitney), consistent with the difference in mean ages of the 2 groups. The groups were indistinguishable by Odom criteria, patient verdict, pain scores, analgesic intake, length of hospital stay, radiologic fusion rate, and residual symptoms.

CONCLUSION

A titanium rod and buttress prosthesis may be a faster and easier alternative to conventional iliac crest/fibula autograft after multisegmental cervical vertebral corpectomy.

Changes in cervical spine curvature after uninstrumented one- and two-level corpectomy in patients with spondylotic myelopathy

OBJECTIVE

We studied changes in the cervical spine curvature in patients with cervical spondylotic myelopathy who underwent one- or two-level central corpectomy and iliac bone grafting without the use of instrumentation.

METHODS

Curvature of the fused segment and of the whole cervical spine was evaluated on preoperative and follow-up x-rays in 93 patients (30 underwent one-level corpectomy, and 63 underwent two-level corpectomy). In 59 patients, the changes in the cervical spine curvature were studied using one follow-up x-ray; in the other 34 patients, the changes were studied on x-rays obtained at two or more follow-up visits. The sagittal alignment of the fused segment was categorized as lordotic (>+5 degrees), straight (+5 to -5 degrees) or kyphotic (>-5 degrees). The whole spine curvature also was recorded as lordotic, straight, or kyphotic.

RESULTS

At a mean follow-up of 22.2 months (range, 6-71 mo), there was a mean change of -10.4 degrees in the segmental curvature (P < 0.001). The fused segment sagittal alignment also worsened (lordotic angles becoming straight or kyphotic and straight angles becoming kyphotic) in 44 patients (47%)(P < 0.001). However, serial studies in 34 patients (mean first and last follow-ups, 11.9 and 30.8 mo, respectively) did not demonstrate significant worsening of the kyphotic angle or the sagittal alignment over time (P = 0.9). Whole spine curvature worsened in 33 (35%) of the 93 patients (P < 0.001); serial studies did not reveal a significant change (P = 0.9). Patients improved in their functional status from a preoperative mean Nurick grade of 2.9 (range, 1-5) to a follow-up mean Nurick grade of 1.5 (range, 0-4) (P < 0.001). Patients with a kyphotic change in their whole spine curvature (n = 33) and those without such change (n = 60) had a similar functional outcome (mean change in Nurick grade, 1.5 and 1.4, respectively).

CONCLUSION

Cervical spine curvature tended to undergo a kyphotic change at the fused segment in 47% of patients and a kyphotic change of the whole spine curvature in 35% of patients who underwent one- or two-level uninstrumented central corpectomy. This kyphotic change in the cervical spine, which stabilizes within 1 year after surgery, is not progressive, and it does not affect neurological outcome in these patients.