Non-fusion instrumentation of the lumbar spine with a hinged pedicle screw rod system: an in vitro experiment.

In advanced stages of degenerative disease of the lumbar spine instrumented spondylodesis is still the golden standard treatment. However, in recent years dynamic stabilisation devices are being implanted to treat the segmental instability due to iatrogenic decompression or segmental degeneration. The purpose of the present study was to investigate the stabilising effect of a classical pedicle screw/rod combination, with a moveable hinge joint connection between the screw and rod allowing one degree of freedom (cosmicMIA). Six human lumbar spines (L2-5) were loaded in a spine tester with pure moments of +/-7.5 Nm in lateral bending, flexion/extension and axial rotation. The range of motion (ROM) and the neutral zone were determined for the following states: (1) intact, (2) monosegmental dynamic instrumentation (L4-5), (3) bisegmental dynamic instrumentation (L3-5), (4) bisegmental decompression (L3-5), (5) bisegmental dynamic instrumentation (L3-5) and (6) bisegmental rigid instrumentation (L3-5). Compared to the intact, with monosegmental instrumentation (2) the ROM of the treated segment was reduced to 47, 40 and 77% in lateral bending, flexion/extension and axial rotation, respectively. Bisegmental dynamic instrumentation (3) further reduced the ROM in L4-5 compared to monosegmental instrumentation to 25% (lateral bending), 28% (flexion/extension) and 57% (axial rotation). Bisegmental surgical decompression (4) caused an increase in ROM in both segments (L3-4 and L4-5) to approximately 125% and approximately 135% and 187-234% in lateral bending, flexion/extension and axial rotation, respectively. Compared to the intact state, bisegmental dynamic instrumentation after surgical decompression reduced the ROM of the two-bridged segments to 29-35% in lateral bending and 33-38% in flexion/extension. In axial rotation, the ROM was in the range of the intact specimen (87-117%). A rigid instrumentation (6) further reduced the ROM of the two-bridged segments to 20-30, 23-27 and 50-68% in lateral bending, flexion/extension and axial rotation, respectively. The results of the present study showed that compared to the intact specimen the investigated hinged dynamic stabilisation device reduced the ROM after bisegmental decompression in lateral bending and flexion/extension. Following bisegmental decompression and the thereby caused large rotational instability the device is capable of restoring the motion in axial rotation back to values in the range of the intact motion segments.

[Post-traumatic osteoarthritis of the knee: special indication for navigated TKA]. / Posttraumatische Gonarthrose: Spezifische Indikation für die navigierte Knietotalendoprothese.

Different studies confirmed the increased radiological implantation accuracy for computer-assisted total knee replacements. There was no study stating a significant influence of the navigation technique for total knee arthroplasties on the early clinical outcomes. In these two case reports we try to show special indications for a navigated total knee replacement to utilize the benefits of a navigation system as efficiently as possible.Case 1 had a femoral neck fracture 3 years ago and was treated with a long femoral gamma nail. The hardware was still retained. Case 2 had a fracture of the femoral diaphysis 31 years ago and showed an extra-articular deformity in the frontal and sagittal planes. Both patients developed osteoarthritis of the ipsilateral knee and were implanted with a total knee prosthesis using a navigation system.In both cases the prosthesis components showed perfect radiological alignment. The clinical outcomes at the 3-month follow-up were very satisfying. In case 1 the femoral nail did not have to be removed, thus decreasing surgery duration by 40-60 min.In both cases, the impossibility of using a femoral intramedullary alignment rod could be compensated for by the navigation system.

Transfusion of autologous blood from reinfusion systems in total knee arthroplasty.

After total knee arthroplasty (TKA) the technique of wound management is not standardised. In this prospective study the efficacy of autologous blood reinfusion from the wound was investigated. One hundred patients (100 TKAs) were enrolled in this sequential cohort study. In one-half of the operations, a reinfusion system with suction and in the other half one wound drain without suction were used. Blood loss, transfusion requirements, range of motion, Insall scores and the incidence of complications were studied. The use of a reinfusion system did not decrease the homologous transfusion requirements. The blood loss in the group with a suction drainage system was significantly higher. Our experiences since May 2002 with one drain without suction in 787 consecutive TKAs confirm all findings of the current study.

Two-year outcomes of computed tomography-based and computed tomography free navigation for total knee arthroplasties.

UNLABELLED: Optimal component position in all planes and well-balanced soft tissues facilitate a good clinical outcome and long-term survival after total knee arthroplasties. We investigated the accuracy of implantation of navigated total knee arthroplasties at 3 months followup and the influence on the clinical outcome at 2 years followup. Forty-four patients (44 procedures) were enrolled in our prospective study. One half of the surgeries were performed using a computed tomography-based navigation system, and half were performed with imageless navigation. Outcomes were based on the Insall knee score parameters, anterior knee pain, patient satisfaction, feeling of instability, and step test. The radiographic parameters were the mechanical axis, tibial slope, lateral distal femoral angle, and medial proximal tibial angle. The radiographic measurements were similar in both groups (patients within +/- 3 degrees inaccuracy range in computed tomography-based/imageless groups; mechanical axis 86%/81%, tibial slope 95%/91%, lateral distal femoral angle 95%/91%, medial proximal tibial angle 91%/95%). The imageless system provided equal radiographic results, but we found improved ligament balancing in the computed tomography free group. The computed tomography-based approach has a good pre-operative planning procedure, but is more expensive and time consuming. LEVEL OF EVIDENCE: Therapeutic Study, Level II. See the Guidelines for Authors for a complete description of levels of evidence.

[CT-based and CT-free navigation in total knee arthroplasty--a prospective comparative study with respects to clinical and radiological results]. / CT-basierte und CT-freie Navigation in der Knieendoprothetik -- eine prospektive Vergleichsstudie unter klinischem und radiologischem Aspekt.

AIM: Optimal component position in all planes and well-balanced soft tissues are factors for clinical outcome and survival time after total knee arthroplasty (TKA). With regard to clinical and radiological parameters, a comparative study between CT-based and CT-free navigation techniques was performed. METHOD: In this prospective study 44 patients (44 surgeries) were enrolled. One half of the surgeries were performed using a CT-based navigation system (group A), the other half using a CT-free system (group B). Pre-operatively and three months post-operatively the patients were physically examined (Insall score, step test, anterior knee pain, subjective feeling of instability and patient satisfaction) and limb alignment was measured by radiographs (mechanical axis, tibial slope, lateral distal femur angle [LDFA], medial proximal tibia angle [MPTA]). The tolerable inaccuracy range for all radiological measurements was +/- 3 degrees. RESULTS: The radiological measurements showed a high accuracy but no significant differences (patients within tolerable range group A/B: mechanical axis 85.7/81.0 %, tibial slope 95.2/90.5 %, LDFA 100/95.2 %, MPTA 90.5/95.2 %). For physical parameters we found a better ligament balancing in group B. CONCLUSION: The CT-based module has an optimal planning procedure but costs more. The CT-free system provides equal radiological results and the availability of a useful ligament balancing module.

[Relevance of wound drainage in total knee arthroplasty--a prospective comparative study]. / Die Bedeutung der Wunddrainage in der Knieendoprothetik--eine prospektive Vergleichsstudie.

AIM: The benefits of postoperative wound drainage in patients with total knee arthroplasty (TKA) with regards to mobilisation and wound healing were studied. We wanted to determine the efficacy of an autologous blood retransfusion system. METHOD: 150 patients with TKA were divided into three groups of 50 patients: A) three wound drainages with an autotransfusion system and suction; B) no wound drainage; C) one intraarticular wound drainage without suction. Hemoglobin values, blood transfusion requirements, blood loss, postoperative range of motion, Insall knee score and rate of complications were observed and recorded. All patients were operated without tourniquets for lower blood loss. RESULTS: In the group of patients with wound drainage and a retransfusion system the requirement of postoperative additional blood transfusion was not significantly less than in the group without wound drainage. Group A had the highest blood loss of all. The group without wound drainage had more hematomas and wound healing complications. Best results were observed within the group with one intraarticular drainage without suction. The rate of complications was not increased and the blood transfusion requirements were the lowest. CONCLUSION: This study shows that total knee replacement involving one intraarticular wound drainage without suction attains the best results.

[Hyperparathyroidism -- a differential diagnosis of cystic bone tumors]. / Hyperparathyreodismus-eine Differentialdiagnose zystischer Knochentumoren.

Clinical manifestations of primary hyperparathyroidism include neuromuscular, intestinal, and osseous symptoms with osteolytic lesions of the bone and pathological fractures. In most cases a primary adenoma of the parathyroid gland leads to an increased production of the parathormone with subsequent osteoclastic bone catabolism. Surgical treatment entails removal of the parathyroid adenoma. We present a female patient and the possible diagnostic and differential diagnostic difficulties encountered in interdisciplinary management.

Long-term observation and management of resolving infantile idiopathic scoliosis a 25-year follow-up.

Of 42 patients with resolving infantile idiopathic scoliosis, 34 were followed up for more than 25 years. Twenty had been primarily treated in a plaster bed and 14 by physiotherapy. The mean angle of the curve at presentation was 17 degrees and at follow-up it was 5 degrees. No patient had significant progression of the scoliosis during the growth spurt. When adults few had back pain or an increased disability score and there was no interference with work or social activities. The rib-vertebra angle difference proved to be an essential radiological sign when distinguishing resolving from progressive infantile idiopathic scoliosis. There was no advantage of plaster over physiotherapy with regard to either the time to resolution or the functional outcome. Treatment of resolving infantile idiopathic scoliosis in a plaster bed is therefore now outdated.

[Sports and physical load bearing capacity after spondylodesis in patients with Scheuermann kyphosis]. / Sport und körperliche Belastbarkeit nach Aufrichtungsspondylodese bei Patienten mit Scheuermann-Kyphose.

In this investigation it was examined which is the effect of an extensive spondylodesis by patients with Scheuermann's kyphosis on their sport activity and their physical load capacity. Between 1983 and 1990, 10 patients with severe kyphosis secondary to Scheuermann's disease underwent surgical correction and spinal fusion. In 1997 all 10 patients were clinically and radiologically examined and interviewed at an average follow-up of 9.6 years. At the time of follow-up one patient was active in top sports, seven patients in normal sport, two patients were members in a sports-club and one patient was not interested in sport. Eight patients went in for sports regulary. Mostly the patients were active in gymnastics, cycling and swimming. At follow-up almost all patients found that their physical load capacity and the behaviour in relation to back pain were better than before operation. Half of the patients were exposed to a middle physical load in the daily life. The presented study shows that patients after extensive spondylodesis for Scheuermann's kyphosis and clear reduction of pain are not automatically limited in the daily life, both for sport and professional activity. However, generalized recommendations for the physical load capacity of the operated patient cannot be given, and an individualized decision must be taken for each case.

The stability of bone screws in the os sacrum.

A variety of points of insertion and implantation techniques are recommended for inserting screws into the os sacrum. On the basis of 16 complete human sacrum specimens the following axial pull-out tests were performed: 1. Insertion of convergent measuring screws, 6.0 mm and 7.0 mm in outside diameter respectively, into the body of vertebra S1 using a monocortical and bicortical technique respectively with perforation of the ventral cortex. 2. Insertion of divergent screws into the ala sacralis at the level of S1 with 6-mm and 7 mm screws respectively, using a monocortical technique without perforation of the ventral cortex. 3. Insertion of convergent 6-mm screws into the body of vertebra S2 using a monocortical and bicortical technique respectively with perforation of the ventral cortex. The highest axial pull-out force was reached using convergent 6-mm screws inserted into the body of vertebra S1 using the bicortical technique with perforation of the ventral cortex (2392.4 N). The use of a 7.0-mm screw in the same implantation technique did not result in higher pull-out forces (2274.7 N). The monocortical technique reached a pull-out force of 1657.53 N with a 6-mm screw and 1505.64 N with a 7-mm screw. Convergent insertion of 6-mm screws into the body of S2 resulted in pull-out forces of 537.02 N using a bicortical and only 297.71 N using a monocortical technique. Divergent insertion of screws into the ala sacralis reached a maximal pull-out force of 495.47 N using 6-mm screws and 449.79 N using 7-mm screws. These data resulted from a monocortical implantation technique without perforation of the ventral cortex of the ala sacralis. The results of the present biomechanical study show that convergent bicortical implantation in the body of S1 is the most stable technique for screw fixation in the sacrum. The use of 7-mm rather than 6-mm screws did not lead to increased primary stability. Anatomic studies have shown that a safe area exists in the region of the ventral promontory, so this implantation technique appears to be unobjectionable.

[Long-term follow-up in patients with idiopathic scoliosis]. / Langzeitverläufe bei Patienten mit idiopathischer Skoliose.

The study concludes the results of the clinical and radiological follow-up of 51 patients with idiopathic scoliosis after 20-36 years (mean of 24.5 years). The aim of the study was to find out which parameters can give an answer at the beginning about the expectable prognosis of the scoliosis. Most of all rotation of the apex vertebra, the skeletal maturity and the curve pattern of the scoliosis are a precise factor for prognosis. The term "scoliosis in babies" should be left, because these benign spontaneously resolving type of scoliosis can appear in the second age, too. To separate them from the infantile scoliosis, which often has a bad natural history the term "oblique position scoliosis" should be used instead of scoliosis in babies.

[Biomechanical prerequisites for examining the stability of osteosynthesis procedures of the spine]. / Biomechanische Voraussetzungen zur Stabilitätsuntersuchung von Osteosyntheseverfahren an der Wirbelsäule.

Basic reflections on biomechanical tests of spinal implants are reviewed. Four different pedicle screw systems are compared during loading in extension, flexion, side-bending, and rotation. The thoracolumbar and the lumbar spine were tested. Stability against rotation forces was lowest in all systems. Because of this, a cross-connector is recommended in highly unstable situations. All tests were done in cadaver spines with normal bone mineral density (measured before the tests). The first series of tests was done without destroying the cadavers. A second series was done with maximal load until the implants or the bony bed of the screws failed. The results show that rigid implants more often led to pedicle fractures. An unstable screw rod interface led to implant failure. Cadaver tests can provide answers about the primary stability characteristic only. Fatigue tests are not possible in cadaver spines because they become autolytic before enough cycles can be applied.

[Stability of pedicle screws. 2: Maximum pullout force with reference to bone density]. / Stabilität von Pedikelschrauben. Teil 2: Maximale Auszugskräfte unter Berücksichtigung der Knochendichte.

Maximum pullout strength of pedicle screws in osteoporotic cadaver spines are tested. Bone mineral density was measured before by two noninvasive methods (QCT, DRA). Pullout direction was axial to screw axis. 210 N to 920 N were reached from D1-S1. There is a high correlation between bone mineral density and pullout strength (r = 0, 8-0.9). Augmentation of osteoporotic pedicles with bone cement increases screw stability nearly to that one of non-osteoporotic spines.

[Stability of pedicle screws. 1: Maximum pullout force in healthy bony spine trunks with reference to drilling technique]. / Stabilität von Pedikelschrauben. Teil 1: Maximale Auszugskräfte bei knochengesunden Stammwirbelsäulen unter Berücksichtigung der Bohrtechnik.

Pullout direction was axial and oblique to screw axis. Two different techniques of preparing the screw bed are matched: 1) 3.2 mm AO drill and 6.0 mm screws for D7-S1 and 4.5 mm screws for D11-D6, 2) resection of cancellous bone of the pedicle tube and 6.0 mm, 7.0 mm, 8.0 mm screws, which were inserted after measuring each level. With the better technique 1 (saving the cancellous bone) 620N-161N were reached from D1-S1, even if bigger screws could be used with technique 2.

[Sports capacity of patients with scoliosis]. / Sportliche Belastbarkeit von Patienten mit Skoliose.

The burden of sport of patients with scoliosis depends on the age, the expected progredience of the deformity and the attained deformation. In children and teenagers treated with an orthesis, total prohibition is not appropriate. All kinds of sport not involving any risk of injury to the participant or the patient wearing an orthesis can be practised. The orthesis may be removed only during swimming. For patients with a fused spine the number of the remaining lumbar moving segments and the deformity are essential for the exercise load. If there are less than three free lumbar segments all kinds of sport with axial and rotationary burdens are not to be recommended. If the spinal bending is more than 50 degrees (Cobb) the limitation of the cardiopulmonary ability is even more severe.

[Post-traumatic recurrent hip joint dislocation]. / Posttraumatische rezidivierende Hüftgelenkluxation.

Recurrent post-traumatic dislocation of the hip joint without an accompanying fracture is very rare. Delayed reduction and a too short immobilization periods seems to favor redislocation. One case is presented together with a discussion of the operative therapy and the intraoperative pathological-anatomical findings with respect to the literature.

[A case with complicated disorder of the occipito-cervical junction]. / Ein Fall mit komplexer okzipitozervikaler Ubergangsstörung.

Only very few complete aplasias of the posterior atlas arch have been described. Aplasia combines with assimilation of the anterior atlas arch and a basilar impression is an even rarer variant of this developmental anomaly in the occipitocervical region. The clinical symptoms in the case described were limited to persistent nuchal pain and severely limited function of the cervical spine.

[Nuclear magnetic resonance tomography in destructive changes of the spine]. / Die Kernspintomographie bei destruktiven Veränderungen der Wirbelsäule.

Correct treatment of destructive lesions in the vertebral column requires exact radiological evaluation with the traditional techniques of plain films, computed tomography and radionuclide scanning. With the development of magnetic resonance imaging the possibility of visualizing pathological changes of the bone marrow became apparent. To prove the value of MRJ in detecting destructive lesions of the spine 29 patients were investigated using plain radiographs, computertomographies, radionuclide scanning and MRJ. The findings were correlated to the intraoperative aspect of the lesion and the results of the histological investigation in 18 cases. MRJ showed to be a very sensitive manner of detecting bone marrow changes of different kind. Indeed characteristic changes in signal intensity were not to be observed in pathological lesions of inflammatory or tumorous genesis. So the distinction is based on morphological criterias.