O. Diedrich

Radiographic characteristics on conventional radiographs after posterior lumbar interbody fusion: Comparative study between radiotranslucent and radiopaque cages

The problem of determining solidity of a fused spinal segment still remains. Our purpose is to evaluate radiographic findings after posterior lumbar interbody fusion (PLIF) with cages and estimate their relative value in judging fusion status. Radiographic follow-up was performed in patients after PLIF with cages of either radiotranslucent or radiopaque material. Conventional radiographs were obtained 6 weeks, 3 and 6 months, and then yearly after surgery for spinal instability for 64 patients. We differentiated between uncertain (increased density within the cage, increase of sclerotic endplates, and posterolateral fusion) and definite (trabecular continuous bone bridging within the implant and periimplant new bone formation with bridging of the intervertebral space) fusion signs. A fusion rate of 51.5% after 12 months, 61.4% after 24 months, 66.7% after 36 months, and 77.8% after 48 months postoperatively was found. We found only a slight, nonsignificant correlation between radiographic fusion and patient-assessed clinical outcome. There is evidence that radiographic fusion criteria occur in a specific chronologic order. The interpretation of fusion status is notably impaired by the use of radiopaque cages. Criteria to standardize the interpretation and evaluation of radiographic findings after PLIF are discussed.

Microvascular response of striated muscle to metal debris: A COMPARATIVE IN VIVO STUDY WITH TITANIUM AND STAINLESS STEEL

Wear products of metal implants are known to induce biological events which may have profound consequences for the microcirculation of skeletal muscle. Using the skinfold chamber model and intravital microscopy we assessed microcirculatory parameters in skeletal muscle after confrontation with titanium and stainless-steel wear debris, comparing the results with those of bulk materials. Implantation of stainless-steel bulk and debris led to a distinct activation of leukocytes combined with a disruption of the microvascular endothelial integrity and massive leukocyte extravasation. While animals with bulk stainless steel showed a tendency to recuperation, stainless-steel wear debris induced such severe inflammation and massive oedema that the microcirculation broke down within 24 hours after implantation. Titanium bulk caused only a transient increase in leukocyte-endothelial cell interaction within the first 120 minutes and no significant change in macromolecular leakage, leukocyte extravasation or venular diameter. Titanium wear debris produced a markedly lower inflammatory reaction than stainless-steel bulk, indicating that a general benefit of bulk versus debris could not be claimed. Depending on its constituents, wear debris is capable of eliciting acute inflammation which may result in endothelial damage and subsequent failure of microperfusion. Our results indicate that not only the bulk properties of orthopaedic implants but also the microcirculatory implications of inevitable wear debris play a pivotal role in determining the biocompatibility of an implant.

Radiographic spinal profile changes induced by cage design after posterior lumbar interbody fusion preliminary report of a study with wedged implants.

Study Design. A prospective comparative radiographic study between two geometrically varying implants utilized in single-level posterior lumbar interbody fusion (PLIF) was performed. Objective. The aim of this study was to determine the influence of 4° wedged cages on postoperative lateral lumbar spinal profile. Summary of Background Data. The biomechanical and clinical importance of realigning the sagittal lumbar profile in surgical management of spinal instabilities is known. Wedged cages are therefore increasingly attaining popularity in PLIF. As yet the significance of wedged implants on postoperative sagittal spinal profile has not been assessed. Methods. Forty patients were randomly assigned to two equal-sized groups. In one group rectangular cages and in the second group cages with a wedged design and an inclination of 4° were implanted. Quantitative assessment of the lumbar spinal profile on standing neutral lateral radiographs was performed before surgery as well as 6 weeks and 12 months after surgery. Results were statistically compared. Results. A significant improvement of lumbar sagittal profile after use of 4° wedged compared with nonwedged cages was not found. The greatest effect on lumbar profile and segmental lordosis was observed in fusion of segment L4–L5 with 4° wedged cages. Conclusions. These results show that normal sagittal alignment after single-level lumbar fusion can be achieved with rectangular and 4° wedged cages. Although results after utilization of 4° wedged cages do not significantly differ, these implants offer the surgeon one more sizing variation with which physiologic lumbar lordosis may be attained. The biomechanical implications of wedged implants on the rigidity of a fused segment remain to be analyzed.

Impact of a nickel‐reduced stainless steel implant on striated muscle microcirculation: A comparative in vivo study

The impairment of skeletal muscle microcirculation by a biomaterial may have profound consequences. With moderately good physical and corrosion characteristics, implant-quality stainless steel is particularly popular in orthopedic surgery. However, due to the presence of a considerable amount of nickel in the alloy, concern has been voiced in respect to local tissue responses. More recently a stainless steel alloy with a significant reduction of nickel has become commercially available. We, therefore, studied in vivo nutritive perfusion and leukocytic response of striated muscle to this nickel-reduced alloy, and compared these results with those of the materials conventional stainless steel and titanium. Using the hamster dorsal skinfold chamber preparation and intravital microscopy, we could demonstrate that reduction of the nickel quantity in a stainless steel implant has a positive effect on local microvascular parameters. Although the implantation of a conventional stainless steel sample led to a distinct and persistent activation of leukocytes combined with disruption of the microvascular endothelial integrity, marked leukocyte extravasation, and considerable venular dilation, animals with a nickel-reduced stainless steel implant showed only a moderate increase of these parameters, with a clear tendency of recuperation. Titanium implants merely caused a transient increase of leukocyte-endothelial cell interaction within the first 120 min, and no significant change in macromolecular leakage, leukocyte extravasation, or venular diameter. Pending biomechanical and corrosion testing, nickel-reduced stainless steel may be a viable alternative to conventional implant-quality stainless steel for biomedical applications. Concerning tolerance by the local vascular system, titanium currently remains unsurpassed.

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.

Magnetic Resonance Imaging Findings of the Lumbar Spine in Elite Horseback Riders: Correlations With Back Pain, Body Mass Index, Trunk/Leg-Length Coefficient, and Riding Discipline

Background Most orthopaedic problems experienced by competitive horseback riders are related to pain in the lower back, hip joint, and hamstring muscles. Riders—especially, show jumpers—are frequently hampered in their performance because of lumbar pain. To date, there has been no research into lumbar disk degeneration in elite competitive riders. Hypothesis Competitive horseback riding accelerates lumbar disk degeneration. Study Design Cross-sectional study; Level of evidence, 3. Methods Fifty-eight elite riders (18 men, 40 women; mean age, 32.4 years) and a control group of 30 nonriding volunteers (17 men, 13 women; mean age, 28.7 years) were evaluated for lumbar disk degeneration, cross-sectional area of paraspinal muscles, spondylolysis, and spondylolisthesis, using magnetic resonance imaging (MRI). The prevalence of disk degeneration between the 2 groups was compared, and the relationship was investigated between low back pain (LBP), riding discipline, body mass index (BMI), trunk/leg-length coefficient, and MRI results. Results Eighty-eight percent of elite riders (n = 51) had a history of LBP, versus 33% of the controls (P < .05). There was no statistical difference for the prevalence of LBP among the different riding disciplines. However, there was a high rate of pathologic T2 signal intensity of the lumbar intervertebral disk among riders—specifically, dressage riders—yet no significant increase when compared with controls. History of LBP symptoms, riding discipline, BMI, and trunk/leg-length ratio had no significant effect on the development of lumbar disk degeneration. Occult fractures of the pars interarticularis and manifest spondylolysis were not seen for any rider. Two controls had spondylolisthesis Meyerding grade 1 not associated with back pain. Conclusion Although riders have a high prevalence of LBP, there is no conclusive MRI evidence to suggest that the cause lies in undue disk degeneration, spondylolysis, spondylolisthesis, or pathologic changes of the paraspinal muscles of the lumbar spine.

Implications of orthopedic fretting corrosion particles on skeletal muscle microcirculation

Particulate corrosion and wear products of metal implants are increasingly becoming topics of interest, due to the cascade of biological and biomechanical events they induce. The impairment of skeletal muscle microcirculation by fretting corrosion particles may have profound consequences. We therefore studied in vivo leukocyte–endothelial cell interaction in skeletal muscle after confrontation with characterized titanium and stainless steel fretting corrosion particles, and compared these results with those of the bulk materials. Using the hamster dorsal skinfold chamber preparation and intravital microscopy, we could demonstrate that stainless steel induces a more pronounced inflammatory answer in contrast to the implant material titanium. However, we were not able to show a general benefit of bulk vs. debris. Overall, the study suggests that not only the bulk properties of orthopaedic implants, but also the microcirculatory implications of inevitable wear debris, may play a role in determining biocompatibility and ultimately longevity of an implant. The skinfold chamber is a feasible and versatile model for observation of the dynamic process of microvascular response after foreign-body implantation, and offers much perspective.© 2001 Kluwer Academic Publishers

Haemophilic arthropathy of the hip in children--prognosis and long-term follow-up.

Summary.  The aim of this study was to report on the long‐term follow‐up of haemophilic children with avascular femoral head necrosis and to determine whether radiographic findings at initial diagnosis have any prognostic value. Seven patients with avascular necrosis of the femoral head were clinically and radiographically observed over a period of 5–50 years. The average age of patients at first diagnosis was 7.1 years. At follow‐up, three of seven patients claimed to have occasional mild pain in the affected hip, four of seven showed loss of range of motion in the hip joint and two of seven patients showed a limp. Only one patient was clinically completely inconspicuous. The radiographically measured caput–collum–diaphysis angle at follow‐up was pathologic in four cases and in one case a lateral subluxation of the femoral head was found. There was marked deformation of the femoral head in three of seven cases and a further two hips showing slight incongruency. Owing to the small patient‐number, a statement concerning the prognostic value of defined radiographic signs cannot be made. As expected, the more ‘risk signs’ radiographically found, the higher the likelihood that patients will suffer arthrosis at a later stage. We propose that a clear distinction between haemophilic arthropathy of the hip and Legg–Calvé–Perthes disease should be made. In cases where radiographic changes are also found in the vicinity of the acetabulum, it is indicative for haemophilic arthropathy.

Das Non-Hodgkin-Lymphom als Differentialdiagnose der Spondylodiszitis

ZusammenfassungEs wird der Fall einer 56jährigen Patientin berichtet, die sich primär mit einer Lumbalgie vorstellte. Sowohl laborchemisch, radiologisch als auch histopathologisch sprach der Befund primär für das Vorliegen einer Spondylodiszitis. Aufgrund der Destruktion des fünften Lendenwirbelkörpers wurde eine dorsoventrale Stabilisierung durchgeführt. In den wiederholt gewonnenen Probeexzisionen fand sich histologisch das Bild einer unspezifischen Entzündung. Erst bei der im Rahmen der Implantatentfernung durchgeführten Biopsie ließ sich histologisch ein hochmalignes Non-Hodgkin-Lymphom nachweisen. Es erfolgte eine Chemotherapie nach dem CHOP-Schema und eine strahlentherapeutische Behandlung. Lymphome der Wirbelsäule sollten besonders bei progredienten Verlaufen als seltene Differentialdiagnose einer Spondylodiszitis berücksichtigt werden.AbstractThis case presents the history of a 56-year-old patient suffering from low back pain for a period of several weaks. The radiological und histopathological examination showed hints for a spondylodiscitis of the fifth lumbar vertebra. Due to a progressive destruction of the fifth vertebra a ventral stabilisation was performed. Again the histological examination showed the characteristics of an unspezific spondylodiscitis. The last biopsy, taken during the explantation of the fixateur interne showed a high malignant lymphoma. A course of chemotherapy was started following the CHOP-Protocol acompanied by radiotherapy. This case demonstrates that meticulous clinical examination as well as advanced radiological techniques can fail in rare differential diagnosis of spondylodiscitis.

Long-term observation and management of resolving infantile idiopathic scoliosis

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.