The role of reduction in operative treatment of spondylolytic spondylolisthesis.

Isthmic spondylolisthesis is a frequently encountered spinal disorder (3-5% of the population). The latest developments in spondylo-implantology have increased interest in operative treatment of slip. The reduction of slip, however, remains controversial and is broadly discussed. On the basis of the literature, the paper presents current views on benefits and risks associated with reduction. Moreover, stabilization methods are discussed and a modified reduction procedure is presented. Spondylolisthesis reduction effectively relieves clinical complaints, and reconstitutes physiological spinal load bearing and spino-pelvic balance. Stabilization eliminates segmental instability and improves conditions for spondylodesis. Currently, one-segmental interbody stabilization with transpedicular fixation is a recommended method. Broad and complete decompression of neural elements and its control during the reduction procedure is recommended in order to avoid neurological complications. Reduction of spondylolytic spondylolisthesis seems to be a safe and effective method provided that a meticulous operative technique is followed.

Operative treatment of hangman's fractures of C2. Posterior direct pars screw repair or anterior plate-cage stabilization?

BACKGROUND AND PURPOSE: Feasibility study and evaluation of complications of two different C1-C2 motion-sparing surgical methods for hangman's fracture of C2. MATERIAL AND METHODS: From 2001 till 2005, seventeen patients were operated on because of unstable type II (according to Effendi) hangman's fractures. The patients were treated either with transoral C2-C3 discectomy with plate-cage stabilization or with posterior direct pars screw repair. The plate-cage group (n=9) comprised patients with a mean age of 34 years, and the average follow-up was 42 months. The screw repair group (n=8) included patients with a mean age of 27 years, and the average follow-up was 28 months. X-rays and computed tomography of the spine were performed before the surgery. X-rays were also performed 2 or 3 days after the surgery, during the 6th week after the surgery as well as at 3, 6, 12, and 24 months thereafter. Fusion and stability of C2 were confirmed on flexion-extension X-rays 6 months after the surgery. RESULTS: In all patients C1-C2 motion was preserved and bone fusion with good cervical spine alignment was achieved. In the plate-cage group, an extension of the head that is needed to reduce flexion types of fracture can cause technical difficulties with the correct plate-cage installation because of interference of the jaw and tongue in the operative field. One patient of the group experienced a chronic infection which was resolved by plate-cage removal. Patients in the screw repair group healed uneventfully without complications. CONCLUSIONS: Anterior transoral plate-cage stabilization is indicated for type II fracture with extension displacement and posterior direct pars screw repair for flexion displacement. Nevertheless, posterior direct pars screw repair seems to be safer, cheaper and more technically feasible.

The process of subsidence after cervical stabilizations by cage alone, cage with plate and plate-cage. A biomechanical comparative study.

BACKGROUND AND PURPOSE: Clinical observations show that subsidence of cervical interbody implants takes place in the early postoperative period. Additional plating or use of a plate-cage is thought to be helpful to avoid excessive subsidence. We performed a biomechanical comparative study to assess the process of subsidence after the use of three different cervical stabilization methods. MATERIAL AND METHODS: Porcine cervical specimens after anterior discectomy were stabilized by a cage alone (n=6), cage with plate (n=6) and a plate-cage (n=6), and were exposed to 21 000 cycles of 20-200 N cyclic axial loads with frequency of 2.5 Hz. Size of subsidence was continually calculated by the software of the testing machine. One-way ANOVA test was applied for statistical evaluation. RESULTS: The test revealed two phases in the course of subsidence: an initial phase and a final one. In the initial phase rapid increase of subsidence occurred. Velocity and size of subsidence in this phase differed significantly between the stabilizing systems. The fastest and biggest subsidence occurred in the case of the cage alone, less subsidence was noted for the cage with plate and the least for the plate-cage. The final phase of the subsidence was markedly slower and longer. Velocity and size in this phase were the biggest for the cage alone. The differences between the cage with plate and the plate-cage in that phase were not significant. CONCLUSIONS: The study shows that subsidence occurs in two phases irrespective of the type of cervical stabilization and this finding confirms similar clinical observations. Additional plating can be helpful in controlling the course of subsidence.

Cervical spine stabilization by plate-cage. Clinical evaluation.

BACKGROUND AND PURPOSE: Cervical plate-cages have recently been introduced to clinical practice. Clinical and radiographic results of D-Fun-CE plate-cage stabilization were studied. MATERIAL AND METHODS: 34 patients were treated surgically with the mean follow-up of 25 months. All cases were divided into 3 groups. Group 1 (n = 15) included posttraumatic cases after one-level discectomies, group 2 (n = 14) included patients with disc degenerative changes after one-level discectomies, and group 3 (n = 9) encompassed patients after two- and three-level discectomies. In the clinical evaluation ASIA scale, Odom's criteria and VAS scale were used. General and local cervical lordoses were assessed by Jackson's method. Subsidence was determined by modified Tye's method. Statistical significance of differences was assessed by Wilcoxon and Mann-Whitney tests. RESULTS: At follow-up, 14 patients (93%) from group 1 improved at least by one degree on the ASIA scale. In Odom's criteria, 79% of patients in group 2 gained very good results, 14% good, and 7% satisfactory; but in group 3 only 56% of patients achieved very good, 22% good, and 22% satisfactory results. On the VAS scale, pain decreased from a mean of 6 to 1.4 after surgery and to 1.3 at follow-up. Overall averaged general cervical lordosis increased from 9.8 degrees before surgery to 19 degrees after surgery and to 19.2 degrees at follow-up. Local cervical lordosis changed from a mean of -2 degrees , to 9.8 degrees and 9.4 degrees , respectively. Subsidence in group 1 averaged 1.2 mm; in group 2, 0.6 mm; and in group 3, 2.4 mm. CONCLUSIONS: The results indicate good stabilization properties of the D-Fun-CE plate-cage. All patients achieved spondylodesis, which is especially beneficial for multilevel cases. Subsidence was noted in the majority of operated cases (76.7% of patients) but its size increased together with the number of fused levels.

[Complications of a transpedicular stabilization of thoraco-lumbar burst fractures]. / Powiklania stabilizacji transpedikularnej wybuchowych zlaman odcinka piersiowo-ledzwiowego kregoslupa.

Complications of transpedicular stabilizations of thoraco-lumbar burst fractures are presented on the basis of literature review and own experiences. Unstable thoraco-lumbar burst fractures create the most difficult biomechanical conditions for a stabilizer. A literature review was done to estimate the effectiveness of vertebral body height restoration and its maintenance, the effectiveness of transpedicular grafting, the fusion rate and the implant-related complications rate. Transpedicular stabilization systems demonstrate a marked stiffness in all directions which is greater than in the case of other posterior stabilization systems. During the postero-lateral spondylodesis the transpedicular stabilizer is gradually unburdened but it is still loaded even after the completion of the bone fusion. A support of the anterior spinal column markedly diminishes the loads of the stabilizer and improves the segmental stability. Long-term follow-up studies of transpedicularly stabilized burst fractures reveal a deterioration of primarily good corrections. In some cases the correction returns to the level from before the operation in spite of transpedicular bone grafting. The implant-related complications rate (screw or rod breakages and a loss of interconnections) reaches up to 28 % of cases. In order to improve the anterior column stability and limit late kyphotization, as well as avoid implant-related complications, some authors additionally recommend performing a posterior interbody fusion (PLIF) or an anterior corpectomy with stabilization. Posterior transpedicular stabilization of thoraco-lumbar burst fractures does not provide a complete stabilization of the anterior spinal column, which results in a recurrence of spine kyphotization and implant-related complications. In selected cases, the application of an additional anterior column support markedly relieves the transpedicular fixator and reduces the pseudoarthrosis rate, late kyphotization and implant-related complications simultaneously.

[Importance of early operative decompression of spinal cord after cervical spine injuries]. / Znaczenie wczesnego operacyjnego odbarczenia rdzenia kregowego po urazach szyjnego odcinka kregoslupa.

BACKGROUND AND PURPOSE: There is no standard timing of the spinal cord decompression. Experimental animal models and clinical investigations on Methylprednisolone (NASCIS-2 and -3) indicate that the time up to 8 hours is the optimal therapeutic window for the early spinal cord decompression. We accepted this time window in our practice. A retrospective clinical evaluation of the early (up to 8 hours) operative decompression of the injured cervical spinal cord was undertaken. MATERIAL AND METHODS: The early operative decompression (range of 2-8 hours) of the cervical spinal cord was done in 32 patients (82% of operated cervical spinal cord injured patients). The neurologic clinical status of patients was assessed according to the ASIA impairment scale. In neurological terms 7 patients were completely and 25 incompletely impaired. Cervical spine injuries included 26 fractures and fracture-dislocations and the rest (6 cases) involved dislocations and disc ruptures. The mean patient age was 31.2 years (range of 16-69) and the average follow-up time was 13 months (range of 6-24). Methylprednisolone standard treatment was applied in all patients on admission to hospital. After diagnostic examinations patients were qualified and immediately operated. We performed 25 corpectomies, 6 discectomies and 1 decompressive laminectomy with stabilization in all cases. RESULTS: The final assessment covers 29 patients because 3 (9.4%) of them died during 4-6 weeks after operation. One patient has not improved and still had A degree but 28 remaining patients (94.5%) have improved neurologically at follow-up. 69% of them recovered by one degree and 27.6% by two degrees on the ASIA scale. In the early postoperative stage during their hospital stay 47% of patients had one degree improvement. CONCLUSIONS: The early cervical spinal cord decompression creates optimal conditions for the neurological recovery. Encouraging results presented in the paper indicate the purposefulness of the decompression performed as fast as possible and indicate the necessity to make emergency services more efficient in order to shorten delivery time to specialized spine centers.

[Subsidence and its effects on the anterior plate stabilization in the course of cervical interbody spondylodesis. Part II. Clinical evaluation. Study design]. / Osiadanie i jego wplyw na uklad stabilizacji plytkowej przedniej w przebiegu spondylodezy miedzytrzonowej kregoslupa szyjnego. Czesc 2: Ocena kliniczna.

STUDY DESIGN: Subsidence is a common phenomenon in the process of interbody fusion. The paper presents a retrospective clinical and radiological evaluation of subsidence in a group of 23 patients after cervical corpectomy with mesh cage and plate stabilization. Subsidence magnitude and its impact on the stabilizing system and on the clinical and radiological outcome were estimated. MATERIAL AND METHOD: The mesh cage and cervical plate stabilization was preformed after one- (20 cases) or two-level (3 cases) corpectomy. The patients' mean age was 35 years (age range 18-72); 9 patients were aged over 50. Indications to corpectomy were: neurological impairment due to burst body fractures in 14 cases, multilevel spondylosis in 5, and OPLL in 2 patients. One patient had a kidney cancer metastasis. The mean follow-up period was 17 months (range 12-28 mo.). The patients' clinical status was evaluated using the ASIA scale in the post-traumatic group, and the Odom criteria in spondylotic cases. In all the cases pain severity was estimated by the VAS scale. Magnitude of subsidence was measured on consecutive lateral x-rays during the follow-up. Bone fusion was confirmed after 3 months in lateral flexion-extension x-rays. Changes in the local and general cervical lordosis were evaluated during the follow-up. RESULTS: A 72-year-old patient died after 6 weeks due to causes unrelated to the surgery. In all the remaining patients bone fusion was attained. There were no cases of the clinical status deterioration during the follow-up. Subsidence of over 1 mm was found in 19 patients (86.4%). The mean value of subsidence was 2.2 mm, but in a group of older patients (aged over 50) it amounted to 2.8 mm. In 4 cases (18.1%) with hardware complications, i.e. a screw breakage or slipping, the mean subsidence magnitude was 4.3 mm. Local and general cervical lordosis were maintained during the follow-up period, even in the group with excessive subsidence. The screw breakage site was invariably the round hole of the plate. CONCLUSIONS: The subsidence phenomenon is seen in a majority of fused patients. Nevertheless, clinical and radiological results of the surgery are good. An excessive subsidence may result from hardware complications. In newly designed plates subsidence should be taken into account.

[Subsidence and its effect on the anterior plate stabilization in the course of cervical spondylodesis. Part I: definition and review of literature]. / Osiadanie i jego wplyw na uklad stabilizacji plytkowej przedniej w przebiegu spondylodezy miedzytrzonowej kregoslupa szyjnego. Czesc 1: Definicja i przeglad pismiennictwa.

A definition of subsidence in terms of spinal biomechanics is presented in the paper. Subsidence is defined as sinking of a body with a higher elasticity modulus (e.g. graft, cage, spacer) in a body characterized by a lower elasticity modulus (e.g. vertebral body), resulting in 3D changes of the spinal geometry. Magnitude of subsidence is directly proportional to the load pressure and to the difference between the elasticity modules, but inversely proportional to the area of the graft-bed interface. Both biological and mechanical qualities of the graft-bed interface are important for the subsidence process. Any excessive subsidence decreases the interbody space and produces both local and general kyphotization of the spine. This may cause destabilization of the screw-plate and/or screw-bone interfaces (e.g. pulling-out, altered angulation or breakage of the screws). A method is proposed of radiological estimating the absolute magnitude of subsidence, based on the real known length of the implanted stabilizer (e.g. plate). Clinical examples of an excessive subsidence and its impact on the stabilizing plate system are presented. Subsidence is inherent in the interbody fusion process. Endplate preservation and a dynamic modification of cervical plates may enables us to control subsidence and reduce the number of complications.