C. N. Kraft

Striated muscle microvascular response to silver implants: A comparative in vivo study with titanium and stainless steel.

Local microvascular perfusion is the primary line of defense of tissue against microorganisms and plays a considerable role in reparative processes. The impairment of the microcirculation by a biomaterial may therefore have profound consequences. Silver is known to have excellent antimicrobial activity and, although regional and systemic toxic effects have been described, silver is regularly discussed as an implant material in bone surgery. Because little is known about the influence of silver implants on the adjacent host tissue microvasculature, we studied in vivo nutritive perfusion and leukocytic response, and compared these results with those of the conventionally used materials titanium and stainless steel. Using the hamster dorsal skinfold chamber preparation and intravital microscopy, the implantation of a commercially pure silver sample led to a distinct and persistent activation of leukocytes combined with a marked disruption of the microvascular endothelial integrity, massive leukocyte extravasation, and considerable venular dilation. Whereas animals with stainless-steel implants showed a moderate increase in these parameters with a tendency to recuperate, titanium implants caused only a transient increase of leukocyte-endothelial cell interaction within the first 120 min and no significant change in macromolecular leakage, leukocyte extravasation and venular diameter. After 3 days, five of six preparations with silver samples showed severe inflammation and massive edema. Thus, the use of silver as an implant material should be critically judged despite its bactericidal properties. The implant material titanium seems to be well tolerated by the local vascular system and currently represents the golden standard.

Pain status of patients with severe haemophilic arthropathy

Patients with severe haemophilia A growing up before the establishment of prophylactic treatment frequently developed significant haemarthropathies. The goal of the following study was to clarify the role of haemarthropathic pain for haemophilic patients. Furthermore, we aimed to determine to what degree daily activities are influenced by the impairment and which therapeutic modalities are used in pain management. Using a questionnaire we consulted 71 haemophiliacs concerning their complaints and how they were treated in 1999 (average age 43 years; range 21–63 years). The pain in the large joints and spine and the effect of specific treatment was estimated by a visual analogue scale. On average, there were four joints with major pain and 0.5 with minor pain. The most frequent sources of pain were the ankle joints (45%), followed by the knee (39%), spine (14%) and elbow (7%). Fifty percent of all patients complained of pain throughout the day if no treatment was applied. In 29% of patients, pain persisted after application of factor VIII (FVIII), while 12% claimed that pain still remained after use of FVIII and painkillers. Restriction in activities of daily life was reported by 89% of the group and 85% reported on an impact of pain on their mood. Patients primarily used FVIII to decrease pain, followed in frequency by use of anti‐inflammatory drugs, orthopaedic footwear, liniments and bandages. Haemophilic patients with haemarthropathy are chronic pain patients. By means of the questionnaire, it is possible to reveal the ‘silent’ sufferers. Sufficient pain treatment is essential so as to increase the patient’s quality of life and avoid inadvertent abnormal postures possibly resulting in increased loading of joints and subsequent bleeding episodes.

Susceptibility to local infection in biological internal fixation

Abstract Resistance to local infection after fracture fixation with plate osteosynthesis may be influenced by the implantation technique. It is known that the extent of the surgical approach to the bone can compromise the local defence capacity. We have investigated susceptibility to infection after a local bacterial challenge in rabbit tibiae using either the open surgical approach for ‘biological’ internal fixation of standard 2.0 dynamic compression plates or the method of minimally invasive plate osteosynthesis (MIPO), a percutaneous, tunnelling insertion technique preserving the integrity of the overlying soft tissue. After the wounds had been closed, various concentrations of Staphylococcus aureus were injected in the direct vicinity of the implants. The infection rate for the open surgical technique was 38.5% and that for the MIPO technique, 25%. This difference is not statistically significant (P > 0.05) suggesting that resistance to local infection associated with the MIPO method is at least equivalent to the open approach for plate osteosynthesis.

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.

Clinical and radiographic scores in haemophilic arthropathies: how well do these correlate to subjective pain status and daily activities?

Summary. Haemophilic patients who reached adulthood before the establishment of prophylactic treatment frequently show multiple and substantial arthropathies. The aim of this study was to determine to what extent haemophiliacs subjective impairment due to arthropathies correlates with objective clinical and radiographic parameters. By means of a questionnaire and a visual analogue scale, we consulted 79 haemophiliacs concerning their joint‐pain status, how these were treated and to what extent their daily activities had been affected. Using a scoring system suggested by the Advisory Committee of the World Federation of Haemophilia, clinical evaluation was performed. Radiographs of 60 patients were assessed by means of the Petterson scale. The results were statistically compared. We found a significant correlation between pain intensity and clinical pathology as well as between pain intensity and radiographic joint damage for both knees and for the right ankle. The number of painful joints correlated well with the number of clinically/radiographically affected joints. The more pronounced the objective damage to joints, the more frequently patients claimed to have constant pain, depressive episodes and a dependency on pain‐relieving medication. The more pronounced the objectively assessed damage to the knee and ankle joint, the higher the likelihood that the patient suffers from severe joint pain and reduction of activity. Treatment of painful symptoms from arthropathies is often insufficient. Scores and questionnaires may help to define the haemophiliacs pain status more clearly, thereby offering a possibility of assessment and long‐term observation.

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.

CRP and leukocyte-count after lumbar spine surgery: fusion vs. nucleotomy

Background Despite the fact that C-reactive protein (CRP) levels and white blood cell (WBC) count are routine blood chemistry parameters for the early assessment of wound infection after surgical procedures, little is known about the natural history of their serum values after major and minimally invasive spinal procedures. Methods Pre- and postoperative CRP serum levels and WBC count in 347 patients were retrospectively assessed after complication-free, single-level open posterior lumbar interlaminar fusion (PLIF) (n = 150) for disc degeneration and spinal stenosis and endoscopically assisted lumbar discectomy (n = 197) for herniated lumbar disc. Confounding variables such as overweight, ASA classification, arterial hypertension, diabetes mellitus, and perioperative antibiotics were recorded to evaluate their influence on the kinetics of CRP values and WBC count postoperatively. Results In both procedures, CRP peaked 2–3 days after surgery. The maximum CRP level was significantly higher after fusion: mean 127 (SD 57) (p < 0.001). A rapid fall in CRP within 4–6 days was observed for both groups, with almost normal values being reached after 14 days. Only BMI > 25 and long duration of surgery were associated with higher peak CRP values. WBC count did not show a typical and therefore interpretable profile. Conclusion CRP is a predictable and responsive serum parameter in postoperative monitoring of inflammatory responses in patients undergoing spine surgery, whereas WBC kinetics is unspecific. We suggest that CRP could be measured on the day before surgery, on day 2 or 3 after surgery, and also between days 4 and 6, to aid in early detection of infectious complications.

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.