Asymmetric C7 pedicle subtraction osteotomy for correction of rigid cervical coronal imbalance secondary to post-traumatic heterotopic ossification: a case report, description of a novel surgical technique, and literature review

Unilateral spacer distraction of the subaxial cervical facet joint for the treatment of fixed coronal malalignment of the craniovertebral junction

Introduction:

The standard treatment for a fixed coronal malalignment of the craniovertebral junction is an anterior and/or posterior column osteotomy (PCO) plus instrumentation. However, the procedure is very challenging, carrying an inherently high risk of complications even in experienced hands. This case series demonstrates the usefulness of an alternative treatment that adds a unilateral spacer distraction (USD) to the subaxial cervical facet joint to promote coronal realignment and fusion.

Materials and Methods:

A single-center retrospective study of the patients with fixed coronal malalignment of the craniovertebral junction caused by different etiologies treated with USD in the concavity side with PCO in the convexity side of the subaxial cervical spine. Demographic characteristics and radiological parameters were collected with special emphasis on clinical and radiological measurements of coronal alignment of the cervical spine.

Results:

From 2012 to 2019, four patients were treated with USD of the subaxial cervical spine complementing an asymmetrical PCO at the same level. The causes of coronal imbalance were congenital, tuberculosis, posttraumatic, and ankylosing spondylitis. The level of USD was C2–C3 in three patients and C3–C4 in one patient. A substantial coronal realignment was achieved in all four. One patient had an iatrogenic vertebral artery injury during the dissection and facet distraction and developed Wallenberg's syndrome with partial recovery.

Conclusions:

USD of the concave side with unilateral PCO of the convexity side in the subaxial cervical spine is a promising alternative treatment for fixed coronal malalignment of the craniovertebral junction from different causes.

C7 extension crosswise osteotomy: a novel osteotomy for correction of chin-on-chest deformity in a patient with ankylosing spondylitis

Extension crosswise osteotomy at C7 (C7 ECO) was developed for the correction of forward gaze in patients with chin-on-chest deformity due to ankylosing spondylitis. A modification of cervicothoracic extension osteoclasis (C/T EO), C7 ECO replaces osteoclasis of the anterior column with a crosswise cut of the C7 vertebral body to eliminate the risks of unintended dislocation of the cervical spine. C7 ECO also eliminates the risks of C7 and T1 pedicle subtraction osteotomies (C/T PSOs), in which a posteriorly based wedge excision may lead to stretching injuries of the lower cervical roots and/or failure to achieve the exact angle of excision required for an optimal correction. Furthermore, opening the osteotomy anteriorly, as in the authors' method, instead of closing it posteriorly, as in PSO, eliminates the risks related to shortening of the posterior column, such as buckling of the dura, kinking of the spinal cord, and stretching of the lower cervical nerve roots. Here, the authors report the use of C7 ECO for the surgical treatment of a 69-year-old man with severe compromise of his forward gaze due to chin-on-chest deformity in the course of ankylosing spondylitis. After uneventful correction surgery, the patient regained the ability to see objects, namely faces of people, at the level of his head while standing and to perform work tasks at a desk.

Asymmetrical pedicle subtraction osteotomy for correction of concurrent sagittal-coronal imbalance in adult spinal deformity: a comparative analysis

OBJECTIVE

Rigid multiplanar thoracolumbar adult spinal deformity (ASD) cases are challenging and many require a 3-column osteotomy (3CO), specifically asymmetrical pedicle subtraction osteotomy (APSO). The outcomes and additional risks of performing APSO for the correction of concurrent sagittal-coronal deformity have yet to be adequately studied.

METHODS

The authors performed a retrospective review of all ASD patients who underwent 3CO during the period from 2006 to 2019. All cases involved either isolated sagittal deformity (patients underwent standard PSO) or concurrent sagittal-coronal deformity (coronal vertical axis [CVA] ≥ 4.0 cm; patients underwent APSO). Perioperative and 2-year follow-up outcomes were compared between patients with isolated sagittal imbalance who underwent PSO and those with concurrent sagittal-coronal imbalance who underwent APSO.

RESULTS

A total of 390 patients were included: 338 who underwent PSO and 52 who underwent APSO. The mean patient age was 64.6 years, and 65.1% of patients were female. APSO patients required significantly more fusions with upper instrumented vertebrae (UIV) in the upper thoracic spine (63.5% vs 43.3%, p = 0.007). Radiographically, APSO patients had greater deformity with more severe preoperative sagittal and coronal imbalance: sagittal vertical axis (SVA) 13.0 versus 10.7 cm (p = 0.042) and CVA 6.1 versus 1.2 cm (p < 0.001). In APSO cases, significant correction and normalization were achieved (SVA 13.0-3.1 cm, CVA 6.1-2.0 cm, lumbar lordosis [LL] 26.3°-49.4°, pelvic tilt [PT] 38.0°-20.4°, and scoliosis 25.0°-10.4°, p < 0.001). The overall perioperative complication rate was 34.9%. There were no significant differences between PSO and APSO patients in rates of complications (overall 33.7% vs 42.3%, p = 0.227; neurological 5.9% vs 3.9%, p = 0.547; medical 20.7% vs 25.0%, p = 0.482; and surgical 6.5% vs 11.5%, p = 0.191, respectively). However, the APSO group required significantly longer stays in the ICU (3.1 vs 2.3 days, p = 0.047) and hospital (10.8 vs 8.3 days, p = 0.002). At the 2-year follow-up, there were no significant differences in mechanical complications, including proximal junctional kyphosis (p = 0.352), pseudarthrosis (p = 0.980), rod fracture (p = 0.852), and reoperation (p = 0.600).

CONCLUSIONS

ASD patients with significant coronal imbalance often have severe concurrent sagittal deformity. APSO is a powerful and effective technique to achieve multiplanar correction without higher risk of morbidity and complications compared with PSO for sagittal imbalance. However, APSO is associated with slightly longer ICU and hospital stays.

Comparison of perioperative complications following posterior column osteotomy versus posterior-based 3-column osteotomy for correction of rigid cervicothoracic deformity: a single-surgeon series of 95 consecutive cases

OBJECTIVE

The correction of severe cervicothoracic sagittal deformities can be very challenging and can be associated with significant morbidity. Often, soft-tissue releases and osteotomies are warranted to achieve the desired correction. There is a paucity of studies that examine the difference in morbidity and complication profiles for Smith-Petersen osteotomy (SPO) versus 3-column osteotomy (3CO) for cervical deformity correction.

METHODS

A retrospective comparison of complication profiles between posterior-based SPO (Ames grade 2 SPO) and 3CO (Ames grade 5 opening wedge osteotomy and Ames grade 6 closing wedge osteotomy) was performed by examining a single-surgeon experience from 2011 to 2018. Patients of interest were individuals who had a cervical sagittal vertical axis (cSVA) > 4 cm and/or cervical kyphosis > 20° and who underwent corrective surgery for cervical deformity. Multivariate analysis was utilized.

RESULTS

A total of 95 patients were included: 49 who underwent 3CO and 46 who underwent SPO. Twelve of the SPO patients underwent an anterior release procedure. The patients' mean age was 63.2 years, and 60.0% of the patients were female. All preoperative radiographic parameters showed significant correction postoperatively: cSVA (6.2 cm vs 4.5 cm [preoperative vs postoperative values], p < 0.001), cervical lordosis (6.8° [kyphosis] vs -7.5°, p < 0.001), and T1 slope (40.9° and 35.2°, p = 0.026). The overall complication rate was 37.9%, and postoperative neurological deficits were seen in 16.8% of patients. The surgical and medical complication rates were 17.9% and 23.2%, respectively. Overall, complication rates were higher in patients who underwent 3CO compared to those who underwent SPO, but this was not statistically significant (total complication rate 42.9% vs 32.6%, p = 0.304; surgical complication rate 18.4% vs 10.9%, p = 0.303; and new neurological deficit rate 20.4% vs 13.0%, p = 0.338). Medical complication rates were similar between the two groups (22.4% [3CO] vs 23.9% [SPO], p = 0.866). Independent risk factors for surgical complications included male sex (OR 10.88, p = 0.014), cSVA > 8 cm (OR 10.36, p = 0.037), and kyphosis > 20° (OR 9.48, p = 0.005). Combined anterior-posterior surgery was independently associated with higher odds of medical complications (OR 10.30, p = 0.011), and preoperative kyphosis > 20° was an independent risk factor for neurological deficits (OR 2.08, p = 0.011).

CONCLUSIONS

There was no significant difference in complication rates between 3CO and SPO for cervicothoracic deformity correction, but absolute surgical and neurological complication rates for 3CO were higher. A preoperative cSVA > 8 cm was a risk factor for surgical complications, and kyphosis > 20° was a risk factor for both surgical and neurological complications. Additional studies are warranted on this topic.

Transdiscal C7 Pedicle Subtraction Osteotomy With a Strut Graft and the Correction of Sagittal and Coronal Imbalance of the Cervical Spine

BACKGROUND

Cervical spine deformity negatively affects patients' quality of life. Pedicle subtraction osteotomy (PSO) has reported to correct cervical deformity but it is challenging and carries a significant risk of morbidity.

OBJECTIVE

To report transdiscal C7 PSO with a strut graft for the correction of sagittal and coronal imbalance in patients with fixed cervical deformity.

METHODS

After standard exposure, the spine was instrumented from C2 to T3. T1 subtotal laminectomy, and C6 to C7 total laminectomies were necessary for C7 PSO. Osteotomy was initiated with removal of C6-7 and C7-T1 facet joints to isolate C7 pedicles and identify bilateral C7/C8 roots. Bilateral C7 pediculectomies and transdiscal PSO were performed. A rectangular strut allograft was then inserted into the PSO site. The location of the strut graft was used as a fulcrum of sagittal and coronal correction. The head fixator was released and the head was extended under intraoperative neuromonitoring, and then detailed sagittal and coronal balances were controlled by compressing or distracting between the pedicle screws above and below the osteotomy.

RESULTS

This technique was applied in 2 patients with fixed subaxial cervical deformities. Transdiscal PSO could add more amount of correction and provide the additional fusion surface. The strut graft prevented sagittal translation, foraminal narrowing, and excessive focal cord kinking during PSO. Both patients showed radiologic and clinical improvements after surgery, and no neurovascular complication occurred after the surgery.

CONCLUSION

Transdiscal C7 PSO with a strut graft placement provided a safe way of correcting sagittal and coronal imbalance simultaneously and reduced neurological complication by preventing sagittal translation, foraminal narrowing and spinal cord kinking.

Asymmetric Pedicle Subtraction Osteotomy for Adult Spinal Deformity with Coronal Imbalance: Complications, Radiographic and Surgical Outcomes

BACKGROUND

Asymmetric pedicle subtraction osteotomy (APSO) can be utilized for adult spinal deformity (ASD) with fixed coronal plane imbalance. There are few reports investigating outcomes following APSO and no series that include multiple revision cases.

OBJECTIVE

To detail our surgical technique and experience with APSO.

METHODS

All thoracolumbar ASD cases with a component of fixed, coronal plane deformity who underwent APSO from 2004 to 2016 at one institution were retrospectively reviewed. Preoperative and latest follow-up radiographic parameters and data on surgical outcomes and complications were obtained.

RESULTS

Fourteen patients underwent APSO with mean follow-up of 37-mo. Ten (71.4%) were revision cases. APSO involved a mean 12-levels (range 7-25) and were associated with 3.0 L blood loss (range 1.2-4.5) and 457-min of operative time (range 283-540). Surgical complications were observed in 64.3%, including durotomy (35.7%), pleural injury (14.3%), persistent neurologic deficit (14.3%), rod fracture (7.1%), and painful iliac bolt requiring removal (7.1%). Medical complications were observed in 14.3%, comprising urosepsis and 2 cases of pneumonia. Two 90-d readmissions (14.3%) and 5 reoperations (4 patients, 28.6%) occurred. Mean thoracolumbar curve and coronal vertical axis improved from 31.5 to 16.4 degrees and 7.8 to 2.9 cm, respectively. PI-LL mismatch, mean sagittal vertical axis, and pelvic tilt improved from 40.0 to 27.9-degrees, 10.7 to 3.5-cm, and 34.4 to 28.3-degrees, respectively.

CONCLUSION

The APSO, in both a revision and non-revision ASD population, provides excellent restoration of coronal balance-in addition to sagittal and pelvic parameters. Employment of APSO must be balanced with the associated surgical complication rate (64.3%).

Characteristics of deformity surgery in patients with severe and rigid cervical kyphosis (CK): results of the CSRS-Europe multi-centre study project

INTRODUCTION AND PURPOSE

Little information exists on surgical characteristics, complications and outcomes with corrective surgery for rigid cervical kyphosis (CK). To collate the experience of international experts, the CSRS-Europe initiated an international multi-centre retrospective study.

METHODS

Included were patients at all ages with rigid CK. Surgical and patient specific characteristics, complications and outcomes were studied. Radiographic assessment included global and regional sagittal parameters. Cervical sagittal balance was stratified according to the CSRS-Europe classification of sagittal cervical balance (types A-D).

RESULTS

Eighty-eight patients with average age of 58 years were included. CK etiology was ankylosing spondlitis (n = 34), iatrogenic (n = 25), degenerative (n = 9), syndromatic (n = 6), neuromuscular (n = 4), traumatic (n = 5), and RA (n = 5). Blood loss averaged 957 ml and the osteotomy grade 4.CK-correction and blood loss increased with osteotomy grade (r = 0.4/0.6, p < .01). Patients with different preop sagittal balance types had different approaches, preop deformity parameters and postop alignment changes (e.g. C7-slope, C2-7 SVA, translation). Correction of the regional kyphosis angle (RKA) was average 34° (p < .01). CK-correction was increased in patients with osteoporosis and osteoporotic vertebrae (POV, p = .006). 22% of patients experienced a major long-term complication and 14% needed revision surgery. Patients with complications had larger preop RKA (p = .01), RKA-change (p = .005), and postop increase in distal junctional kyphosis angle (p = .02). The POV-Group more often experienced postop complications (p < .0001) and revision surgery (p = .02). Patients with revision surgery had a larger RKA-change (p = .003) and postop translation (p = .04). 21% of patients had a postop segmental motor deficit and the risk was elevated in the POV-Group (p = .001).

CONCLUSIONS

Preop patient specific, radiographic and surgical variables had a significant bearing on alignment changes, outcomes and complication occurrence in the treatment of rigid CK.

Anterior cervical osteotomy: operative technique

PURPOSE

Correction of rigid cervical deformities often requires osteotomies to realign the spine. Cervical pedicle subtraction osteotomy can be technically challenging due to the presence of cervical nerve roots and usually can only be performed at C7 or T1 due to the presence of vertebral arteries. In contrast, anterior cervical osteotomy can be performed throughout the cervical spine and is a safe and effective method for correction of both sagittal and coronal cervical deformities. We describe the anterior cervical osteotomy technique with a review of the pertinent literature.

METHODS

A step-by-step technical guide for anterior cervical osteotomy is provided with a focus on surgical nuances and complication avoidance. Two illustrative cases of fixed sagittal and coronal deformities are included to demonstrate the substantial amount of deformity correction achievable using the anterior cervical osteotomy technique.

RESULTS

Both patients in the illustrative cases had successful clinical and radiographic outcome following deformity correction utilizing the anterior cervical osteotomy technique.

CONCLUSION

Anterior cervical osteotomy is a safe and effective technique for correction of rigid cervical deformities. Spine surgeons should be familiar with this technique to optimize clinical outcome in patients undergoing cervical deformity correction.