Lapidus arthrodesis in combination with arthrodesis of the first metatarsophalangeal joint-biomechanical cadaver study comparing two methods of fixation.

AIMS: To assess the results of a biomechanical test of cadaveric specimens, comparing 2 methods of fixation of modified Lapidus arthrodesis in combination with arthrodesis of the first metatarsophalangeal joint. METHODS: A total of 12 cadaveric specimens were used in the test. Arthrodesis of the first MTP joint was in all patients fixed with a Variable Angle LCP 1st MTP Fusion Plate 2.4/2.7. Two methods of fixation of the Lapidus arthrodesis were compared, i.e. fixation with two screws in the PS (plate-screw) version versus fixation with X-Locking Plate 2.4/2.7 in the PP (plate-plate) version. Measurements were obtained with the use of a testing machine ZWICK Z 020-TND with an optical device Mercury RT for measuring deformities. Each specimen was subjected to 3 loading options, a. displacement 5 mm, the support is placed under the proximal phalanx, b. displacement 5 mm, the support is placed under the first metatarsal head and c. load to failure, the support is placed under the first metatarsal head. RESULTS: In all specimens the PS construct showed a statistically considerably higher stiffness than the PP construct. In all specimens treated with the PP construct the load to failure was lower than in the PS construct. For loading mode a., at a significance level of 0.05 (P<0.05), the P-value was 0.036, for mode b. the P-value was 0.007 and for loading mode c. the P-value was 0.006. In addition, age-related decrease in stiffness of the specimen was proved at a significance level of 5% (P=0.004). CONCLUSION: In all the three loading modes, the PS (plate-screw) construct showed a statistically higher stiffness than the PP (plate-plate) construct.

Percutaneous versus open pedicle screw fixation for treatment of type A thoracolumbar fractures.

BACKGROUND: The purpose of this study was to evaluate the effectiveness between percutaneous and open pedicle screw fixation without fusion for treating type A3 and A4 thoracolumbar fractures. Traumatic thoracolumbar burst fracture is a common pathology without a consensus on the best treatment approach. Percutaneous pedicle screw fixation (PPSF) systems have been recently introduced in the treatment of spinal fractures to reduce the adverse effects associated with the conventional open approaches, such as iatrogenic muscle denervation and pain. METHODS: A prospective analysis was made to evaluate consecutive 46 patients with type A3 and A4 thoracolumbar fractures. Patients were divided into a percutaneous pedicle screw fixation group (PPSF) and an open pedicle screw fixation group (OPSF). The mean age of patients in PPSF group (12 men, 11 woman) was 49.9 years and in OPSF group (10 men, 13 women) 52.2 years. For the purpose of evaluation, the radiological assessment of the bisegmental Cobb angle, the loss of correction, the volume of blood loss, operation time, cumulative radiation time and dose were recorded and compared. RESULTS: All patients were followed up for 12 months. There were no significant differences between OPSF and PPSF in the Cobb angle preoperative and postoperative angle and the loss of bisegmental correction. In PPSF group, the mean preoperative Cobb angle was 10.9° and improved by 4.5° postoperatively, and in OPSF group the preoperative angle was 12.1° and postoperatively improved by 3.8°. Significant differences between OPSF and PPSF were found in the mean cumulative radiation time, radiation dose and operation time. PPSF group also had a significantly lower perioperative blood loss. CONCLUSIONS: Both open and percutaneous short-segment pedicle fixation were safe and effective methods to treat thoracolumbar burst fractures. Percutaneous fixation without fusion seems to be suitable for type A3 and A4 fractures.

Minimally invasive thoracoscopic approach to thoracolumbar junction fractures.

AIMS: A retrospective analysis of patients with thoracolumbar junction fractures who underwent video-assisted thoracoscopic surgery via a minimally invasive approach (minithoracotomy) for reconstruction of the anterior spinal column. METHODS: Between 2002 and 2014, a total of 176 patients were treated by this technique. The patients received either posterior stabilization and, at the second stage, the minimally invasive technique via an anterior approach, or the minimally invasive anterior procedure alone. RESULTS: In the anterior procedure, the average operative time was 90 min. (50 to 130 min). Bony fusion without complications was achieved in all patients within a year of surgery. The loss of correction after the anterior procedure with an allograft or titanium cage was up to 2 degrees at two years follow-up. CONCLUSION: The minimally invasive approach (minithoracotomy up to 6-7 cm) combined with thoracoscopy is an alternative to an exclusively endoscopic technique enabling us to provide safe surgical treatment of the anterior spinal column.

Biomechanical Testing of Spinal Segment Fixed by Arcofix System on the Swine Spine.

STUDY DESIGN: An in vitro biomechanical study. PURPOSE: To evaluate the mechanical properties of the spinal segment in the intact, injured, and stabilized state after fixation by an Arcofix implant. OVERVIEW OF LITERATURE: Several types of thoracolumbar spine injury necessitates anterior instrumentation. The Arcofix plate represents the latest generation of angular stablity systems. The biomechanical properties of these implants have not been sufficiently studied yet. METHODS: A total of ten porcine specimens (levels Th12-L3) were prepared. The tests were performed for intact, injured, and implanted specimens. In each state, the specimen was subjected to a tension load of a prescribed force, and subsequently, twisted by a given angle. The force load was 200 N. The torsion load had a deformation character, i.e., the control variable was the twisting angle and the measured variable was the moment of a couple. The amplitude of the load alternating cycle was 3°. Another parameter that was evaluated was the area of the hysteresis loop. The area corresponds to the deformation energy which is dissipated during the cycle. RESULTS: A statistically significant difference was found between the intact and injured states as well as between the injured and implanted specimens. The statistical evaluation also showed a statistically different value of the hysteresis loop area. In the case of instability, the area decreased to 33% of the physiological value. For the implanted sample, the area increased to 170% of the physiological value. CONCLUSIONS: The Arcofix implant with its parameters appears to be suitable and sufficiently stable for the treatment of the anterior column of the spine.

Biomechanical testing of spinal segment fixed by thoracolumbar spine locking plate on the swine lumbar spine.

BACKGROUND: The aim of the experiment was to compare the mechanical properties of intact spinal segment with impaired intervertebral disc and impaired intervertebral disc fixed by TSLP (Thoracolumbar Spine Locking Plate). METHODS AND RESULTS: Spinal specimens were taken from domestic swine. A total of 8 test mechanical states (intact, impaired and fixed) were modeled and the mechanical properties, expressed by the value of moment of couple necessary to twist the specimen at tensile force F = 200 N and the value of moments necessary for extension straining, were determined. The study was based on in vitro biomechanical testing of the TSLP plate used to stabilize the front thoracolumbar column of spinal segments taken from a pig. The plate was used for monosegmental fixation. The disc was cut by scalpel to simulate the Type A injury to front spinal column. In each state (intact, impaired or fixed), specimens were subjected to a tension load of prescribed force and, then, twisted by a given angle. Subsequently, extension load of intact, impaired and impaired & fixed segment was measured. Statistical evaluation verified the hypothesis of the different behavior of intact, impaired and fixed specimens - both for tension & torsion load and extension load. The analyses did not indicate different mechanical behavior of intact and fixed specimens. In other words, monosegmental fixation of both impaired and intact specimens by TSLP Synthes implant will lead to similar mechanical behavior of these specimens. Further, we found that intact and fixed specimens show non-symmetric behavior at positive and negative twisting angles. This was not observed for impaired specimens. CONCLUSION: Several stabilization systems were developed to stabilize the front thoracolumbar spinal column. Surgery of the anterior column of injured spine should restore the correct position of the spine, ensure decompression of vertebral canal when neural structures are compressed, and stabilize the spine to allow immediate loading and mobilization of the patient. The aim of this study was to compare mechanical properties of intact spinal segment, impaired spinal segment and impaired spinal segment stabilized by TSLP Synthes implant. The problems were solved by experimental modeling using a testing machine that simulated loads for several mechanical states of the spinal segment. Favorable mechanical properties of TSLP Synthes fixator were demonstrated. The experimental results will be used for subsequent computational modeling of the spinal segment in all experimentally solved states.

Complete burst fracture of the fifth lumbar vertebra treated by posterior surgery using expandable cage.

STUDY DESIGN: This report characterises a 25 year old male patient with a complete burst fracture of the fifth lumbar vertebra with dislocation. He was treated by posterior surgery with transpedicular instrumentation and an expandable cage from the posterior approach. OBJECTIVES: Burst fractures of the fifth lumbar vertebra are extremely rare. Patients with positive neurological findings should be treated by the posterior approach. This surgery consists of reduction, decompression, transpedicular stabilisation and fusion. MATERIALS AND METHODS: The young man in our report was treated by posterior surgery only. It consisted of laminectomy, suture of the thecal sac tear, discectomies and subtotal removal of the fifth lumbar vertebra. Repositioning was carried out simultaneously with support using Synex TM Synthes USA telescopic cage and SOCON TM Aesculap Germany transpedicular fixator. RESULTS: The patient suffered neither wound complications nor instrumentation failure. He is currently able to walk with the help of peroneal bands but without crutches. CONCLUSIONS: Treatment of fractures of the fifth lumbar vertebra depends on fracture type and neurological findings. Conservative management of this condition is appropriate provided there is no neurological damage and canal stenosis and deformity is minimal. Surgical treatment of burst lumbar fractures with neurological deficit is strongly recommended. The optimum treatment remains debatable.

Outcomes after conventional versus computer-navigated anterior cruciate ligament reconstruction.

PURPOSE: The purpose of this prospective randomized study was to assess biomechanical, radiographic, and functional results after single-bundle anterior cruciate ligament (ACL) reconstruction by use of a navigation system. METHODS: ACL reconstruction was performed by use of the OrthoPilot navigation system (B. Braun-Aesculap, Tuttlingen, Germany) in 40 patients (group 1); and in another 40 patients, surgery was done by the standard manual targeting technique (group 2). The anterior laxity was measured with a KT-1000 arthrometer (MEDmetric, San Diego, CA). Femoral and tibial tunnel position was evaluated radiologically according to the method described by Bernard and Hertel and by Harner et al., respectively. The questionnaire-based Lysholm and International Knee Documentation Committee scales were included to compare the functional state in both groups. RESULTS: The knees in group 1 were as stable as those in group 2 during the arthrometer testing, with a lower value of dispersion. The postoperative Lysholm and International Knee Documentation Committee scores had the same value in both groups. Statistical differences existed with regard to anterior-posterior femoral tunnel placement when the navigated and standard techniques were compared; in the navigated group, more exact results were found. No significant complications were observed. CONCLUSIONS: The only difference that we found between the navigated and standard groups was in radiographic tunnel position measurement. The computer-assisted navigation technique in our study resulted in more accurate tunnel placement in the femur (but not the tibia) than the traditional arthroscopic technique. However, the performed standard radiographic measurements are of limited precision in principle. Functional scales and stability tests gave similar results in both groups. LEVEL OF EVIDENCE: Level I, therapeutic study.

Mosaicplasty for the treatment of femoral head defect after incorrect resorbable screw insertion.

Articular cartilage lesions and osteochondral defects remain a difficult problem for the patient and physician. A variety of procedures and treatments have been proposed to lessen symptoms and restore the articular surface. The knee joint has been the focus of the vast majority of these cartilage restoration procedures. Osteochondral defects of the proximal femur are significantly less common, and their management remains poorly defined. This article reports the case of a young man with a deep osteochondral defect of the femoral head caused by penetrated resorbable screw after internal fixation of a displaced large single fragment of the posterior acetabular rim and subsequent treatment using mosaicplasty.