Cervical Spondylosis
Cervical spondylosis involves a constellation of chronic degenerative changes that culminate in narrowing of the spinal canal and neural foramen. Due to natural loss of disc height, facet arthropathy, ligamentum flavum hypertrophy and buckling, osteophyte formation, and occasionally ossification of the posterior longitudinal ligament, there is a gradual reduction of available space for the spinal cord throughout the spinal canal including the cervical spine.
Due to the heterogeneity of degenerative processes causing spondylosis, it is not always clear whether decompressive surgery can be best and most safely accomplished from an anterior approach or a posterior approach. This dilemma has been studied and will be summarized here.
| Author Year
Country |
Methods | Outcomes |
| Luo et al. (2015)
China Meta-Analysis AMSTAR=9 N=10 studies |
Objective: To evaluate the clinical outcomes and complications between anterior and posterior surgical approaches for the intervention of multilevel cervical spondylotic myelopathy (MCSM).
Methods: Comprehensive literature search of English RCTs of participants with CSM caused by multi-segmental spinal stenosis, excluding trauma, tumors, disc herniation, or previous surgery. Data analysis was performed by calculating standardized/weighted mean difference (SMD/WMD) or odds ratio (OR) and 95% confidence intervals (95%CI). Databases: MEDLINE, EMBASE, PubMed, Cochrane. Evidence: Studies were assessed for quality using the Newcastle-Ottawa Scale (NOS, 0-10). Statistical significance was defined as p<0.05.
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1. All studies were high quality: nine with NOS=8 and one with NOS=7.
2. Clinical outcome was assessed using the Japanese Orthopedic Association Scale (JOA). 3. In ten studies (n=467), preoperative JOA score was similar in both groups (WMD=0, 95%CI=-0.5 to 0.5, p>0.05). 4. In four studies (n=268), postoperative JOA score was significantly higher in the anterior group than posterior group (WMD=0.79, 95%CI=0.16 to 1.42, p<0.05). 5. In five studies (n=420), recovery rate was similar in both groups (WMD=2.73, 95%CI=-8.69 to 14.15, p>0.05). 6. In nine studies (n=809), complication rate was significantly higher in the anterior group than posterior group (OR=1.65, 95%CI=1.13 to 2.39, p=0.009). 7. In five studies (n=294), reoperation rate was significantly higher in the anterior group than posterior group (OR=8.67, 95%CI=2.85 to 26.34, p=0.0001). 8. In four studies (n=252), blood loss was significantly higher in the anterior group than posterior group (WMD=-40.25, 95%CI=-76.96 to 3.53, p<0.05). 9. In four studies (n=252), operation time was significantly longer in the anterior group than posterior group (WMD=61.3, 95%CI=52.33 to 70.28, p<0.00001). 10. In three studies (n=192), length of stay was significantly shorter in the anterior group than posterior group (WMD=-1.07, 95%CI=-2.23 to -1.17, p<0.00001). |
| Ghogawala et al. (2011)
USA PCT N=50 |
Population: Mean age: 61.6 yr; Gender: males=32, females=18; Level of injury: cervical.
Intervention: Participants received ventral fusion surgery (n=28) or dorsal fusion surgery (n=22) for cervical spondylotic myelopathy. Outcomes were assessed at baseline, 3 mo, 6 mo, and 12 mo. Outcome Measures: Modified Japanese Orthopedic Association Scale (mJOA); Oswestry Neck Disability Index (NDI); EuroQol-5D (EQ-5D); Short-Form 36-Item Health Survey, Physical Component Summary (SF-36 PCS). |
1. mJOA mean scores significantly increased in the dorsal (+1.94, p=0.0028) and ventral (+2.04, p<0.001) groups from baseline to 12mo.
2. mJOA mean scores were significantly higher in the ventral group than dorsal group at baseline (13.40 versus 11.60, p=0.009), 6 mo (15.31 versus 13.44, p=0.03), and 12 mo (15.44 versus 13.54, p=0.003). 3. NDI mean scores significantly decreased in the ventral group (-18.4, p<0.001) but not in the dorsal group (-5.89, p=0.22) from baseline to 12 mo. 4. NDI mean scores were significantly lower in the ventral group than dorsal group at 12 mo (17.96 versus 30.13, p=0.03); differences at other time points were not significant. 5. EQ-5D mean scores significantly increased in the dorsal (+0.13, p=0.04) and ventral (+0.16, p<0.001) groups from baseline to 12 mo. 6. EQ-5D mean score at 6 mo was significantly higher in the ventral group than dorsal group (0.77 versus 0.59, p=0.04); differences at other time points were not significant. 7. SF-36 PCS mean scores significantly increased in the dorsal (+5.74, p=0.03) and ventral (+9.92, p<0.001) groups from baseline to 12 mo. 8. SF-36 PCS mean score at 6 mo was significantly higher in the ventral group than dorsal group (45.00 versus 38.31, p=0.04); differences at other time points were not significant. |
| Kong et al. (2015)
China Pre-Post N=40 |
Population: Mean age: 57.8 yr; Gender: males=31, females=9; Level of injury: cervical; Mean time since injury: 11.5 mo.
Intervention: Participants received anterior decompressive surgery for proximal-type cervical spondylotic amyotrophy. Outcome Measures: Surgical outcome. |
1. Surgical outcome improvement rate was 75%: 16 participants had excellent outcome, 14 had good outcome, and 10 had fair outcome.
2. Surgical outcome improvement rate in participants with spinal cord compression (n=34) was 71%; disease duration was a significant negative predictor of improvement (p<0.01). 1. Surgical outcome improvement rate in participants with nerve root compression (n=6) was 100%. |
| Liu et al. (2012)
China Case Series N=286 |
Population: Mean age: 54 yr; Gender: males=166, females=120; Level of injury: C2-C5=57, C3-C6=75, C4-C7=135.
Intervention: Participants who received anterior cervical surgery for multilevel cervical spondylotic myelopathy were retrospectively analyzed. Techniques were anterior cervical decompression and fusion (ACDF; n=103), hybrid construct (HC; n=96), and long corpectomy (LC; n=87). Outcome Measures: Japanese Orthopedic Association Scale (JOA); Neck Disability Index (NDI); Short-Form 36-Item Health Survey (SF-36); Complications. |
1. JOA mean scores improved after intervention in the ACDF group (10.2 to 14.8), HC group (11.3 to 13.9), and LC group (10.7 to 14.5).
2. NDI mean scores improved after intervention in the ACDF group (35.6 to 14.7), HC group (34.9 to 14.3), and LC group (35.2 to 16.0). 3. SF-36 mean scores improved after intervention in the ACDF group (33.2 to 58.5), HC group (35.8 to 52.2), and LC group (34.5 to 49.6). 4. Complication rate was 15.53% in the ACDF group, 22.92% in the HC group, and 26.44% in the LC group, and 21.33% overall. |
| Liu et al. (2009)
China Case Control N=28 |
Population: Mean age: 53.5 yr; Gender: males=19, females=9; Level of injury: C3-C6=17, C4-C7=11.
Intervention: Participants who received anterior cervical surgery for multilevel cervical spondylotic myelopathy were retrospectively analyzed. Techniques were hybrid decompression (HD; n=12) and two-level corpectomy (TLC; n=16). Outcome Measures: Japanese Orthopedic Association Scale (JOA); Neck Disability Index (NDI); Segmental lordosis; Graft fusion. |
2. JOA mean scores significantly improved in the HD group (11.2 to 14.3, p<0.05) and TLC group (10.9 to 14.3, p<0.05) after intervention; post-op scores were not significantly different between groups (p=0.964).
3. JOA score improvement rate was not significantly different between the HD and TLC groups (55.8% versus 56.8%, p=0.720). 4. NDI mean scores significantly improved in the HD group (34.3 to 14.9, p<0.05) and TLC group (34.6 to 17.2, p<0.05) after intervention; post-op scores were not significantly different between groups (p=0.053). 5. Segmental lordosis significantly increased in the HD group (3.75 to 10.7, p<0.05) and TLC group (5.06 to 13.0, p<0.05) after intervention; post-op scores were not significantly different between groups (p=0.146). 6. Graft fusion rate was not significantly different between the HD and TLC groups (100% versus 94%, p=0.378). |
Discussion
The optimal method of surgical decompression for cervical spondylosis has been studied using several prospective cohorts and summarized via meta-analysis. In a small non-randomized prospective trial, Ghogawala et al. (2011a) compared ventral to dorsal decompression and found that both groups demonstrated improvements in disease-specific disability (modified Japanese Orthopedic Association scale and Neck Disability Index) and quality of life compared to baseline. Although improvements in each group were similar, ventral decompression resulted in better change in Neck Disability Index and quality of life measures compared to dorsal decompression. This result is difficult to interpret due to worse neurological status at baseline in the dorsal group as well as small sample size.
Among individuals receiving an anterior/ventral approach for multilevel spondylosis, there are several accepted options for reconstruction/stabilization of the spinal column following decompression. These include adjacent discectomies with fusion, multilevel corpectomy with fusion, or a hybrid combination. The outcomes of these, and their complication profiles, have recently been studied. Liu et al. (2009) report a case control study, again with small numbers, suggesting equivalent and satisfactory clinical outcomes between multilevel corpectomy and a hybrid approach. In an analysis of complication rates, Liu et al. (2012b) reported that each of the three anterior approaches showed no difference in neurological or quality of life outcome, despite the multilevel corpectomy group having a higher overall rate of complications, consisting mainly of graft migration, hoarseness, and dysphagia, most of which self-resolved. Among all comers, the approximate rate of surgical complication from anterior decompression was 22%. Also, of note, the more cranially-oriented the construct, the higher rate of postoperative complications, although no differences in neurologic or quality of life outcome were reported.
A similar syndrome to cervical spondylotic myelopathy is cervical spondylotic amytrophy, which describes a pure-motor syndrome thought to be secondary to spondylosis. In this population of individuals, anterior decompression has been described (Kong et al. 2015). In a small series of 40 surgically treated individuals, 75% of individuals experienced an improvement after surgery as defined by manual muscle testing, although it is unclear what threshold constitutes a clinically important difference (Kong et al. 2015).
Finally, Luo et al. (2015b) performed a meta-analysis comparing anterior-vs-posterior surgical decompressive approaches. Ten studies were included and consisted of a mix of non-randomized prospective and retrospective studies. Although the anterior approach shows modest evidence of better neurological function postoperatively, the modified Japanese Orthopedic Association score and overall clinical outcome generally was deemed clinically nonsignificant between the two groups. This may be due to the higher complication in the anterior approach, especially when treating multilevel disease. Otherwise, statistical equivalence was reported in terms of modified Japanese Orthopedic Association score, neurological recovery rate, operative blood loss, and length of hospital stay.
Conclusion
There is level 2 evidence (based on one prospective controlled trial: Ghogawala et al. 2011) that anterior decompression for cervical spondylosis myelopathy may have better neurological recovery, but is also associated with higher complication rates, when compared to posterior decompression. There is no difference in disease-specific disability or quality of life between these two groups.
There is level 3 evidence (based on one case control, one pre-post, and one case series (Liu et al. 2009; Kong et al. 2015; Liu et al. 2012) that many different reconstructive options for anterior decompression have been established; however, they are not discernible in terms of quality of life or clinical outcomes.
