The cement-bone bond is weaker than cement-cement bond in cement-in-cement revision arthroplasty. A comparative biomechanical study

This study compares the strength of the native bone-cement bond and the old-new cement bond under cyclic loading, using third generation cementing technique, rasping and contamination of the surface of the old cement with biological tissue. The possible advantages of additional drilling of the cement surface is also taken into account. Femoral heads from 21 patients who underwent a total hip arthroplasty performed for hip arthritis were used to prepare bone-cement samples. The following groups of samples were prepared. A bone—cement sample and a composite sample of a 6 weeks old cement part attached to new cement were tested 24 hours after preparation to avoid bone decay. Additionally, a uniform cement sample was prepared as control (6 weeks polymerization time) and 2 groups of cement-cement samples with and without anchoring drill hole on its surface, where the old cement polymerized for 6 weeks before preparing composite samples and then another 6 weeks after preparation. The uniaxial cyclic tension-compression tests were carried out using the Zwick-Roell Z020 testing machine. The uniform cement sample had the highest ultimate force of all specimens (n = 15; R_m = 3149 N). The composite cement sample (n = 15; R_m = 902 N) had higher ultimate force as the bone-cement sample (n = 31; R_m = 284 N; p <0.001). There were no significant differences between composite samples with 24 hours (n = 15; R_m = 902 N) and 6 weeks polymerization periods (n = 22; R_m = 890 N; p = 0.93). The composite cement samples with drill hole (n = 16; R_m = 607 N) were weaker than those without it (n = 22; R_m = 890 N; p < 0.001). This study shows that the bond between the old and new cement was stronger than the bond between cement and bone. This suggests that it is better to leave the cement that is not loosened from the bone and perform cement in cement revision, than compromising bone stock by removal of the old cement with the resulting weaker cement-bone interface. The results support performing cement-in-cement revision arthroplasty The drill holes in the old cement mantle decrease cement binding strength and are not recommended in this type of surgery.

Drill holes decrease cancellous bone strength: A comparative study of 33 paired osteoporotic human and 9 paired artificial bone samples

This study was designed to compare compressive strength of cancellous bone retrieved from the femoral head in a specimen with and without guide wire hole, with comparison to synthetic bone samples. Femoral heads retrieved from 33 patients who sustained femoral neck fractures and underwent hip arthroplasty were cut into cuboids leaving two matching samples from the same femoral head. Similar samples were prepared from synthetic femurs. One of the matching samples was chosen at random and was drilled with a guide wire for cancellous screws. The uniaxial compression tests of bone blocks were carried out using the Zwick-Roell Z020 strength testing machine. The mean loss of sample cross section area due to drilling was 24%. The force at failure in drilled specimens was significantly smaller by 18% in human (median: 26%) and by 25% in synthetic bone (median 27%). The strength of human specimens was almost 2 times greater, and their stiffness nearly 4 times greater than in synthetic samples. The study shows that the weakening of the bone after drilling is roughly proportional to the loss of sample cross section area. The percentage decrease in strength was similar in human and artificial bone, but human samples were stronger and stiffer. The comparison shows that forces measured in biomechanical studies on artificial bone cannot be directly attributed to humans, but the relative differences in mechanical properties of synthetic samples after some damage may be accurate and resemble that of human bones.

Cadaveric biomechanical testing of torque - to - failure magnitude of Bilateral Apical Vertebral Derotation maneuver in the thoracic spine

It remains unclear what is the real safe limit of torque magnitude during Bilateral Apical Vertebral Derotation (BAVD) in thoracic curve correction. Up to author's knowledge there is no study except this one, to reproduce in-vivo real measurements and intraoperative conditions during BAVD maneuver. The objective of this study was to evaluate the torsional strength of the instrumented thoracic spine under axial rotation moment as well as to define safety limits under BAVD corrective maneuver in scoliosis surgery. 10 fresh, full-length, young and intact human cadavers were tested. After proper assembly of the apparatus, the torque was applied through its apical part, simulating thoracic curve derotation. During each experiment the torque magnitude and angular range of derotation were evaluated. For more accurate analysis after every experiment the examined section of the spine was resected from the cadaver and evaluated morphologically and with a CT scan. The average torque to failure during BAVD simulation was 73,3 ± 5,49Nm. The average angle of BAVD to failure was 44,5 ± 8,16°. The majority of failures were in apical area. There was no significant difference between the fracture occurrence of left or right side of lateral wall of the pedicle. There was no spinal canal breach and/or medial wall failure in any specimen. The safety limits of thoracic spine and efficacy of BAVD for axial plane correction in the treatment of Adolescent Idiopathic Scoliosis (AIS) were established. It provided qualitative and quantitative information essential for the spinal derotation under safe loading limits.

Transient Monoplegia as a Result of Unilateral Femoral Artery Ischemia Detected by Multimodal Intraoperative Neuromonitoring in Posterior Scoliosis Surgery: A Case Report

This is to report a case of 16-year-old girl with transient right lower limb monoplegia as a result of femoral artery ischemia detected by multimodal intraoperative spinal cord neuromonitoring (MISNM) during posterior correction surgery of adolescent idiopathic scoliosis.A patient with a marfanoid body habitus and LENKE IA type scoliosis with the right thoracic curve of 48° of Cobb angle was admitted for posterior spinal fusion from Th6 to L2. After selective pedicle screws instrumentation and corrective maneuvers motor evoked potentials (MEP) began to decrease with no concomitant changes in somato-sensory evoked potentials recordings.The instrumentation was released first partially than completely with rod removal but the patient demonstrated constantly increasing serious neurological motor deficit of the whole right lower limb. Every technical cause of the MEP changes was eliminated and during the wake-up test the right foot was found to be pale and cold with no popliteal and dorsalis pedis pulses palpable. The patient was repositioned and the pelvic pad was placed more cranially. Instantly, the pulse and color returned to the patient's foot. Following MEP recordings showed gradual return of motor function up to the baseline at the end of the surgery, whereas somato-sensory evoked potentials were within normal range through the whole procedure.This case emphasizes the importance of the proper pelvic pad positioning during the complex spine surgeries performed in prone position of the patient. A few cases of neurological complications have been described which were the result of vascular occlusion after prolonged pressure in the inguinal area during posterior scoliosis surgery when the patient was in prone position. If incorrectly interpreted, they would have a significant impact on the course of scoliosis surgery.

Operative treatment of isthmic spondylolisthesis with posterior stabilization and ALIF. Cages versus autogenous bone grafts

In the following study the use of cages and autogenous bone grafts were compared in the operative treatment of isthmic spondylolisthesis with the posterior stabilization and Anterior Lumbosacral Interbody Fusion (ALIF). 55 patients were divided into two groups. Autogenous bone grafts were used in the first group (34 patients) and titanium interbody implants (cages) in the second group (21 patients). The mean follow up period in the first group was 8.6 years and 3.4 years in the second group. The radiological outcome was based upon the evaluation of the degree of spondylolisthesis, the angle of the lumbar lordosis, the height of the interbody space and intervertebral foramen and the evaluation of the spinal fusion. The objective clinical outcome assessment was based on Oswestry Disability Index. Subjective clinical evaluation was performed with the use of Visual Analog Pain Score (VAS) and the two questions concerning the evaluation of success of the operative treatment and a possible agreement to the following operation if necessary. The use of autogenous bone grafts alone in ALIF was related to the significant loss of achieved segmental spine anatomy restoration. The implantation of the cages prevented the loss of slippage correction, permanently reconstructed the anatomical conditions in the area of the operated spinal segment.

Secondary scoliosis after thoracotomy in patients with aortic coarctation and patent ductus arteriosus

The aim of this study was to determine the influence of lateral thoracotomy on the development of scoliosis in subjects undergoing repair of coarctation of the aorta (CoAo) and patent ductus arteriosus (PDA). A group of 133 patients with CoAo and PDA was evaluated. Forty-five patients with CoAo and 38 with PDA were operated on using lateral thoracotomy (operative group) while 12 patients with CoAo and 31 with PDA were treated using balloon dilatation and stent or coil implantation (non-operative group). Clinical examination and the evaluation of spinal roentgenograms were performed. Among the operated patients 46.6% of those with CoAo and 39.5% of those with PDA had clinical scoliosis. In the non-operated patients scoliosis was present in only 16.6% of those with CoAo and 12.9% of those with PDA. Scoliosis ranged between 10° and 42° and it was mild in the majority of cases. In 90.4% of the operated scoliotic patients with CoAo and 73.3% of those with PDA the curve was thoracic and in 47.6% of the CoAo group and 53,3% of the PDA group the curve was left sided. All curves were right sided in non-operated subjects. Scoliosis in the operated group was higher in males than in females (63.3% versus 60% in CoAo and 68.2% versus 37.5% in PDA). The prevalence of scoliosis after thoracotomy was significantly higher than after non-surgical methods of treatment of both CoAo and PDA as well as in the general population. The rate of single thoracic and the rate of left thoracic curves in patients after thoracotomy is higher than in patients treated non-surgically or in idiopathic scoliosis. The rate of scoliosis after thoracotomy is higher in males than females especially following thoracotomy for PDA.

Intraoperative Neurophysiologic Monitoring (INM) in scoliosis surgery

Even among skilled spinal deformity surgeons, neurologic deficits are inherent potential complications of spine surgery. The aim was to assess the meaning of changes and to evaluate the critical rates of Somatosensory Evoked Potentials (SEP) and Motor Evoked Potentials (MEP) for Neurologic Deficit (ND) occurrence associated with scoliosis surgery. A Group of 30 patients with idiopathic scoliosis treated surgically by posterior correction and stabilisation were included. Patients were matched by age, sex, aetiology, Cobb angle, and surgical criteria. Data on three planar scoliosis correction and concomitant (INM) alarms were compared. Radiographic assessment was performed from radiographs taken before surgery and just after it. The (INM) was performed with the use of ISSIS (Inomed) in every patients the same fashion. The average thoracic curve correction was 69.7% and lumbar 69.8%. The average preoperative Apical Vertebral Rotation was 23.5° for thoracic and 27.9° for lumbar curves and postoperatively 10.9° and 14.3° respectively. There was a significant variability of SEP during surgery with only 7 (23%) patients with stable SEP. 15(50%) patients had a decrease of SEP below 50% and 8(27%) had severe decrease of SEP below 50% what caused us to stop surgery or to decrease correction of curves. There was a MEP decrease in 11(37%) patients and in 6 (20%) directly after correction up to 50% of normal value. In 5 of 30 (17%) patients there was a significant decrease of MEP below 50% and we immediately released the implant. The SEP decrease up to 50% without any MEP change did not influenced the outcome. There was no correlation between flexibility and correction of the curve and SEP and MEP decrease. The safe level for MEP was not determined but its meaning for the outcome was more important than SEP value. The need of (INM) during scoliosis surgery to avoid (ND) was confirmed.

The effectiveness of percutaneous vertebroplasty in the treatment of different aetiology Vertebral Body Fractures

Percutaneous Vertebroplasty (PV) has gained widespread popularity in the treatment of Vertebral Body Fractures (VBFs). The procedure involves the injection of polymethylmethacrylate (PMMA) cement into the fractured vertebral body via a needle that is placed percutaneously using either a transpedicular or extrapedicular approach. Health Related Quality of Life (HRQoL) evaluation is a widespread method of measure of the disease severity and the outcome of the treatment. The subjective feeling of pain in VBFs is crucial for the HRQoL. The aim of the study was to determine the effectiveness of percutaneous vertebroplasty in the treatment of VBFs. A group of 187 patients with VBFs of different etiology resulting from osteoporosis, trauma or tumors were treated with PV in Pomeranian Center of Traumatology in Gdansk from 2010 to 2011. The effectiveness of the treatment was evaluated with Visual Analog Scale (VAS), Hospital Anxiety and Depression Scale (HADS-M), Rolland Morris Scale (RMS), 36-Item Short Form Health Survey (SF-36) and Oswestry Disability Index (ODI) questionnaires administered before and one month after surgery. PV decreased significantly VAS score, depression and anxiety level, what improved significantly HRQoL in patients with VBFs.

Scoliosis in patients with aortic coarctation and patent ductus arteriosus: does standard posterolateral thoracotomy play a role in the development of the lateral curve of the spine?

The aim of this study was to determine the influence of lateral thoracotomy on the development of scoliosis in subjects undergoing repair of coarctation of the aorta (CoA) and patent ductus arteriosus (PDA). A group of 133 patients with CoA and PDA was evaluated. Forty-five patients with CoA and 38 with PDA underwent surgery using standard posterolateral thoracotomy (operative group), whereas 12 patients with CoA and 31 with PDA were treated using balloon dilatation and stent or coil implantation (nonoperative group). A spinal examination, together with the evaluation of chest and spinal roentgenograms, was conducted. Among the operated patients, 62% of those with CoA and 55% of those with PDA had clinical scoliosis. In the nonoperated patients, scoliosis was present in only 25% of those with CoA and 16% of those with PDA. Scoliosis ranged between 10 degrees and 42 degrees . In 89% of the operated patients with CoA and 76% of those with PDA the curve was thoracic; in 46% of the CoA group and 57% of the PDA group the curve was left-sided. All curves were right-sided in nonoperated subjects. Scoliosis in the operated group was higher in male than in female subjects (63% vs. 60% in CoA and 86% vs. 37% in PDA). The prevalence of scoliosis after standard posterolateral thoracotomy was significantly higher than after nonsurgical treatment methods in the CoA and PDA groups as well as in the general population. The rate of single thoracic and the rate of left-sided thoracic curves in patients after thoracotomy is higher than in nonoperated patients or in those with idiopathic scoliosis. The rate of scoliosis after thoracotomy is higher in male than female patients, especially after thoracotomy for PDA.