Stephen I. Esses

Complications associated with the technique of pedicle screw fixation. A selected survey of ABS members.

A limited survey analysis of 617 surgical cases in which pedicle screw implants were used was undertaken to ascertain the incidence and variety of associated complications. The different implant systems used included variable spinal plating (n = 249), Edwards (n = 143), and AO fixateur interne (n = 101). The most common intraoperative problem was unrecognized screw misplacement (5.2%). Fracturing of the pedicle during screw insertion and iatrogenic cerebrospinal fluid leak occurred in 4.2% of cases. The postoperative deep infection rate was 4.2%. Transient neuropraxia occurred in 2.4% of cases, and permanent nerve root injury occurred in 2.3% of cases. Previously unreported injury to nerve roots occurred late in the postoperative course in three cases. Screw breakage occurred in 2.9% of cases. All other complications had an incidence of less than 2%. The authors conclude that pedicle screw placement may be associated with significant intraoperative and postoperative complications. This information is of value to surgeons using pedicle implant systems as well as to their patients. Repeat surgery is associated with greater numbers of complications.

Anterior cervical fusion : Outcome analysis of patients fused with and without anterior cervical plates

The purpose of this study was to assess the role of the anterior cervical plate in the treatment of cervical spondylosis. Forty-three patients surgically treated for cervical spondylosis were reviewed. The technique for discectomy and fusion was the same for both groups (Smith-Robinson with autologous iliac crest bone graft). Group I consisted of 25 consecutive patients treated with anterior cervical discectomy, autograft fusion, and anterior cervical plate fixation (Morscher titanium hollow screw plate system). Group II consisted of 18 consecutive patients treated without plate fixation. The overall clinical results in this study were not improved with the use of anterior cervical plate fixation (Fishers exact test, p > 0.05). The fusion rate of one-level cervical fusions was not improved with anterior cervical plate fixation (Fishers exact test, p > 0.05). The overall graft complication rate (pseudoarthrosis plus delayed union plus graft collapse) in multilevel fusions was decreased with anterior cervical plate fixation (Fishers exact test, p < 0.01). The cost effectiveness and risk versus benefit of anterior cervical plate fixation in the surgical treatment of cervical spondylosis require further investigation.

Changes in segmental intervertebral motion adjacent to cervical arthrodesis : a prospective study

Study Design. Prospective, observational. Objectives. Quantify the changes in intervertebral motion adjacent to cervical arthrodesis over time. Summary of Background Data. One of the frequently acknowledged sequelae following anterior cervical fusion is the development of adjacent segment disease. It has been argued that a spine fusion transfers stress to adjacent levels and results in increased compensatory motion. However, there are conflicting reports as to whether this actually occurs, and most of these are in vitro or retrospective clinical studies. Methods. Patients undergoing anterior cervical discectomy and fusion underwent a preoperative dynamic fluoroscopic study, followed by imaging at regular intervals after surgery. Imaging data were analyzed by a validated software system. Relative motion between adjacent vertebrae was then calculated, and changes in motion cephalad to the fusion followed over time. Results. Twenty-one patients were analyzed. Mean follow-up was 13 months (10–22 months). Intervertebral motion adjacent to the fusion changed by more than 4° in 4 of the 21 patients. However, on average, there was no difference between preoperative and postoperative motion for shear, flexion–extension, or vertical displacement at the anterior or posterior disc space. Conclusions. Although there was some individual variation, at a mean of 13 months following surgery, there was no significant change in the average junctional intervertebral motion. If fusion is going to affect adjacent motion, it appears that this does not consistently occur in the first 1 to 2 years following surgery. Additionally, there was no observable relationship between motion and development of degenerative changes during this time.

Coccygodynia: evaluation and management.

Abstract Coccygodynia is pain in the region of the coccyx. In most cases, abnormal mobility is seen on dynamic standing and seated radiographs, although the cause of pain is unknown in other patients. Bone scans and magnetic resonance imaging may show inflammation and edema, but neither technique is as accurate as dynamic radiography. Treatment for patients with severe pain should begin with injection of local anesthetic and corticosteroid into the painful segment. Coccygeal massage and stretching of the levator ani muscle can help. Coccygectomy is done only when nonsurgical treatment fails, which is infrequent. Coccygectomy usually is successful in carefully selected patients, with the best results in those with radiographically demonstrated abnormalities of coccygeal mobility.

Kinematic evaluation of lumbar fusion techniques.

Study Design Eight human cadaveric lumbosacral spines were biomechanically and kinematically tested in torsion and compression‐flexion. They were retested after simulated posterolateral fusion, anterior lumbar interbody fusion, and circumferential fusion. Objectives To analyze stiffness and motion in the anterior and posterior columns of the index and contiguous spinal motion units of anterior, posterolateral, and circumferential fusions. Summary of Background Data Previous biomechanical studies have not incorporated analysis of motion with six degrees of freedom, consideration of contiguous levels, and comparisons of anterior and posterior column motion. Methods Eight human cadaveric lumbosacral spines were biomechanically tested in compression‐flexion and torsion using an advanced biplanar radiography technique. Each specimen underwent either a simulated posterolateral fusion or anterior fusion followed by a circumferential fusion. Motion and stiffness at the level of the fusion and at contiguous levels were analyzed independently in the anterior and posterior columns of the spine. Results At the level of fusion, the simulated posterolateral and anterior fusions prevented more motion in torsion compared with compression‐flexion. With all specimens, it was shown that circumferential fusions were stiffer than the intact specimen. Our comparison of motion in the anterior and posterior columns found no significant differences within the columns of a single vertebral motion segment. Compared with posterolateral fusions, anterior fusions were found to have the greatest effect in increasing motion at contiguous levels. The effect of circumferential fusions on adjacent level kinematics was not significantly greater than that of anterior fusions. Conclusion There are major biomechanical differences between different fusion techniques. This information should be considered in patients undergoing lumbar spinal fusion.

Late infection of spinal instrumentation by hematogenous seeding.

Six cases of late spinal infection following instrumentation are described. In all cases, there was a delay of at least 10 months between surgery and the clinical development of sepsis. In 5 of the 6 cases, a distant focus of infection could be identified. Two patients had active intravenous drug usage, two patients were paraplegic with neurogenic bladders, and one patient had an episode of pyelonephritis secondary to renal calculi two months prior to presentation. In no instance was there any preceding breakdown of overlying skin. This previously unreported phenomenon is an extremely rare but major complication of spinal surgery.

Repair of pars interarticularis defect. The prognostic value of pars infiltration.

Ten patients with symptomatic spondylolysis or Grade I spondylolisthesis were treated with the Buck method. At follow-up, nine patients were graded as successful. All patients fused. Pain relief, level of function, and likelihood of return to work were higher in patients preoperatively selected by lidocaine infiltration of the pars defect. Pars infiltration gives an accurate prediction of successful outcome following pars repair.

Screw fixation of odontoid fractures and nonunions.

Surgical treatment of odontoid fractures has usually been carried out by C1–2 arthrodesis rather than by fracture fixation. An alternative treatment of compression screw fixation was used to treat selected acute odontoid fractures and nonunions. Ten patients were operated on. A variety of lag-screw types were used to compress and secure the fracture. Screw placement was considered excellent in five cases; in four, the screw tip protruded through the posterosuperior cortex of the dens by 1–3 mm. One patient died as a result of multiple injuries 2 days after surgery. In all other cases, including four cases of odontoid pseudarthroses, the fractures achieved solid union. It was concluded that screw fixation can be used for the successful treatment of selected odontoid fractures and nonunions.

A biomechanical study of odontoid fractures and fracture fixation.

The purpose of this study was to measure the stability of the odontoid process after fracture and subsequent screw fixation. To accomplish this, we mechanically reproduced Type II and Type III odontoid fractures on isolated C2 vertebrae by varying the direction of load. These fractures were subsequently stabilized with a single 3.5 mm screw and retested for multidirectional stability and load to failure. Reduced and instrumented specimens were found to have a stiffness equivalent to one half of that of the unfractured odontoid. Load to failure was also slightly less than one half of the original fracture force (average 160 ib). Screw failure was by a cut-out mechanism in all Type III fractures and by bending of the screw in all Type III fractures. Our findings, in conjunction with the existing literature, strongly suggest that Type III fractures result from extension forces, whereas Type II fractures result from lateral or oblique loading forces. Single screw fixation of an odontoid fracture will provide stability equal to approximately one half that of the unfractured bone.

The value of facet joint blocks in patient selection for lumbar fusion

The purpose of this study was to ascertain the correlation between diagnostic facet blocks and treatment outcome, both surgical and nonsurgical. One hundred twenty-six patients who had previously undergone diagnostic facet injections were reviewed. Eighty-two had subsequently undergone lumbar arthrodesis. The rest were treated with a variety of nonoperative modalities. Statistical analysis of accumulated data failed to show any significant correlation between the results of facet blocks and outcome of operative arthrodesis. In addition, statistical analysis failed to show any significant correlation between the facet block results and the outcome of nonoperative treatment. The authors concluded that lumbar facet joint injections cannot be used to determine appropriate patient treatment because they are not predictive of either surgical of nonsurgical success.