Stability changes after cryosurgery in long tubular bones in correlation to histological results: an animal trial

STUDY QUESTION

Pathologic bone fractures in cryosurgery of bone tumors have been described in literature. This study utilizing a sheep model should prove the possible reduction of potential fracture while using a new miniature cryoprobe minimizing tissue damage and providing accurate control of the ablation process. Furthermore, postoperative histological changes should be investigated and the results correlated with the stability trials.

METHODS

In 24 sheep, ablation of the femur and the tibial bone on one side was carried out. Ablation of the right femur was limited to an area of 2 cm(2) with single cortical bone, whereas at the left tibia the whole proximal tibial plateau was included. The other side served as a control entity without cryoablation. After a period of 2, 4, and 6 months postoperative investigation of bending resistance of the femoral bone and of compression resistance of the tibial bone as well as histological findings were done in eight animals each.

RESULTS

After 2 months there was a significant difference (P < 0.05) regarding compression resistance between the treated and the contralateral tibia, whereas the bending resistance in the treated femur was slightly lower than on the contralateral side. After 4 and 6 months the cryo-treated part showed a tendency towards weakness. Histological findings showed bone necrosis with slight beginning repair after 2 months. Four and six months later, bone necrosis still existed with increasing development of woven bone and conversion into lamellar bone.

DISCUSSION

A thorough control of the freezing process and the low iatrogenous weakening of the bone due to placing the probe when modern miniature cryoprobes are used can minimize the risk of pathological postoperative fractures. However, at least 2 months after operation there is histological proof of bone healing with appropriate reduction of bone stability, which should be considered for the clinical application of this new technique.

Magnetresonanztomographie nach Kryoablation langer Röhrenknochen im Tiermodell

PURPOSE

To describe the MR findings following cryoablation of long bones.

MATERIALS AND METHOD

Cryoablation was performed in femoral and tibial bones of 24 sheep under general anesthesia. MRI of the treated and untreated contralateral bones was performed immediately thereafter and at 2, 4 and 6 months after the cryosurgical procedure.

RESULTS

On the MRI performed immediately after cryotherapy, the lesions showed low signal intensities relative to the normal bone marrow on unenhanced T1- and T2-weighted images. At 2, 4 and 6 months after cryoablation, the lesions showed high signal intensities on STIR images, low signal intensities on T1-weighted and heterogeneous enhancement on contrast-enhanced T1-weighted MR images. The femoral lesions decreased in size from 31 +/- 3 mm immediately after the cryotherapy to 13 +/- 4 mm 6 month later and the tibial lesions from 29 +/- 7 mm to 19 +/- 4 mm.

CONCLUSION

MRI shows bone marrow lesions immediately after cryotherapy and can easily monitor healing lesions. MR imaging is suitable for following cryotherapy.

[The minimally invasive unicompartmental knee system "Preservation"First clinical results and analysis of complications]

The Preservation uni knee system is a minimally invasive procedure for implantation of a unicompartmental knee prosthesis. The early results show that the rehabilitation process is quick; the postoperative pain and blood loss is less than after conventional knee arthroplasty. Still there are some pitfalls. The implantation of the tibial mobile-bearing component requires a sound operative technique; otherwise complications will occur. The combination of the available navigation system with the Preservation uni will improve operative accuracy.

Iatrogenic paraplegia in spinal surgery

INTRODUCTION

Paraplegia as a result of a surgical spinal procedure is a rare complication. The risk cannot be precisely quantified due to the lack of current data. The aim of this study was to record a sufficiently large number of major spinal operations, especially extended methods in scoliosis surgery. Hereby, a reliable statement regarding the risk of severe neurological complications with these surgical techniques should be possible. First, a retrospective analysis of patients from a German spine centre (spinal fusion) and a survey of 17 German centres of spinal surgery were conducted for the retrospective acquisition of severe iatrogenic neurological complications.

MATERIALS AND METHODS

The study included 1194 patients who underwent a spinal fusion during the period 1992-2002. The incidents of postoperative paraplegia are described in detail, and case studies done. Possible causes, methods of intraoperative monitoring and options of therapy are discussed according to research in relevant publications. Additionally, severe neurological complications of 3115 spinal operations were recorded in a standardised survey conducted throughout major German spinal centres.

RESULTS

Of the 1194 patients surveyed, 7 (0.59%) experienced a postsurgical complete or incomplete paraplegia. In 3 of the recorded cases, the cause could be identified. The survey of 3115 scoliosis surgeries showed that iatrogenic paraplegia occurred with a frequency of 0.55%. The risks associated with short spinal fusions (0.14%), cervical discectomies (0.07%) and lumbar discectomies (0.03%) are considerably less.

CONCLUSION

Operative treatment of scoliosis with a high degree of correction carries a risk of neurological complications of about 0.5%. Mechanical as well as ischaemic damage to the spinal cord can be detected early by means of consistent intraoperative neuromonitoring.

[Juxta-facet cysts as a differential diagnosis for lumbar neuralgia]

AIM

The aim of the current investigation it was to evaluate the incidence, clinical symptoms and the results of surgical treatment of lumbar juxta-facet cysts.

METHOD

Between January 2002 and July 2003 305 patients underwent decompression of the lumbar spinal canal. In 3.6 % of these (n = 11) juxta-facet cyst were found to be responsible for the complaints and resection of the cyst was performed. All patients underwent standardized clinical examination and pain evaluation by the means of a visual analogue scale in a follow-up of 6.8 month on average.

RESULTS

The average history of lumbar pain was 26 months, that of leg pain 23 weeks, respectively. Radicular symptoms appeared in 7 patients, and 9 of 11 patients complained about spinal claudication. Clinical examination showed a typical pain provocation during reclination of the lumbar spine. However none showed a segmental instability. Preoperative MRI revealed facet cysts with an average diameter of 9 mm (4-18 mm). All of the patients showed signs of degenerative spondylarthritis. Postoperative examination revealed in 8 cases a very good and in 2 cases a good result. One patient complained about persisting sciatica in spite of MR-tomographic demonstration of complete resection of the cyst. The walking-distance improved by least 50 % in 10 cases. Although no spinal fusion was performed, no patient developed a postoperative segmental instability.

CONCLUSION

Juxta-facet cysts represent a not uncommon differential diagnosis in patients with lumbar radiculopathy. In the case of missing signs of segmental instability, resection of the cyst without simultaneous spinal fusion seems to be an appropriate therapy.

Rate of perioperative complications in thermal ablation of bone: an animal trial

INTRODUCTION

While only few data are available yet for radioablation of bone tissue, the occurrence of bone marrow embolisms during cryoablation has been documented. It was the aim of this study to assess perioperative complication rates of thermoablation in animals using state-of-the-art ablation probes.

MATERIALS AND METHODS

Eight adult sheep were placed under general anaesthesia, and using a radioprobe, thermoablation was performed on the medial side of the head of the right tibia. In addition, freezing was performed with miniature cryoprobes on both femurs and the head of the left tibia. Haemodynamic monitoring and determination of blood gases and electrolytes were done intraoperatively. The animals were killed 1 week after surgery, and the ablation sites and lung tissue examined macroscopically and microscopically.

RESULTS

None of the animals showed pathological changes in any of these parameters. Blood gases remained unremarkable throughout the operation. All eight animals showed an average drop in haemoglobin of 0.97 g/100 ml. Two animals showed fresh embolisms in the pulmonary vessels.

CONCLUSION

Experimental thermoablation of bone tissue in large animals failed to show any significant perioperative complications following surgery. The lung embolisms which did occur were not clinically relevant. The use of mini-cryoprobes or radioprobes as alternative or complementary measures for treating pathologically altered bone tissue seems viable and does not involve any undue risks.

[Changes in stability after cryosurgical treatment of long tubular bones. An animal experiment study]

The incidence of spontaneous fractures after cryosurgical treatment is described in the literature. The purpose of this study in the sheep model was to analyze the possibility of minimizing the potential risk of bone failure using a new miniature cryoprobe with minimal tissue traumatism and exact control of the ablation. In each of 24 sheep ablations at the right femur and left tibia were performed by drilling. The ablation at the femur was restricted to an area of 2 cm(2) of only one cortical bone, whereas at the proximal tibia the whole tibial plateau was included. The opposite side, which was treated with analog drillings without cryoablation, served as control. The ultimate bending strength of the femur and the ultimate compression strength of the tibia were examined 2, 4, and 6 months after the operation. After 2 months there was a significant difference ( p<0.05) in the ultimate compression strength between the treated and untreated tibiae, whereas the ultimate bending strength of the treated femora tended to be lower. After 4 and 6 months the side treated with cryosurgery was only marginally weaker than the untreated side. Spontaneous fractures were not observed during the whole experimental period. The good controllability of the freezing procedure and the low iatrogenic weakening of the bone using a modern miniature cryoprobe minimizes the risk of pathological postoperative fractures. After ablation of larger bone sections, the treated extremity should be partially unloaded or managed by osteosynthesis for at least 3 months.

Cryosurgery in long bones with new miniature cryoprobe: an experimental in vivo study of the cryosurgical temperature field in sheep

AIM

The aim of this in vivo study was to determine whether new miniature cryoprobes provide adequate tissue cooling in long bones by measuring the field of temperature under various conditions.

METHODS

Freezings were performed in femoral and tibial bones of 10 sheep under general anaesthesia. Applying one cryoprobe, temperatures of -75 degrees C resp. -51 degrees C could be reached within 0.75 cm resp. 1.00 cm of the probe.

RESULTS

Histological examinations revealed compact bone and marrow necroses along the isotherm in all 10 sheep. Using two cryoprobes simultaneously, a mean temperature decrease to -71 degrees C between the two cryoprobes was achieved thanks to the synergistic freezing effect. Looking at consecutive freezes, it was apparent that with similar cryoprobe end temperatures, the temperature dropped faster if the number of freezing cycles was increased.

CONCLUSION

In conclusion, it was seen that despite its small diameter, the new miniature cryoprobe delivers adequate in vivo tissue cooling in long tubular bones. Employing the synergistic freezing effect by using two or more cryoprobes simultaneously, efficient in vivo freezing of larger bone segments is also possible. Thus, cryosurgery with the new miniature probes can provide a valuable complement to conventional resection of long tubular bones, and offers a viable alternative to surgical treatment of neoplastic diseases of the skeletal system.

[Treatment course in endoprosthetic knee replacement--a systematic insurance cost calculation exemplified by a concrete example]

In view of the planned introduction of the DRG system in Germany, this paper gives the reader a guideline on how to analyse costs and productivity of medical procedures. Total knee replacement was chosen because it is one of the standard operations in orthopedic surgery with existing special calculations for this type of operation. By using the example of a total knee replacement, productivity phases are used and their costs are estimated. With these phases the clinician is able to analyse the efficiency of his department and a benchmarking is possible. Nevertheless, we should not forget that although cost reduction in hospitals is essential the patients' health is the main aim of treatment.

[Development of physical and sports activity in patients before and after implantation of a total knee endoprosthesis. A prospective study of 40 patients]

AIM

The aim of this prospective study was to analyse the development of activities of daily living (ADL) as well as sports activities in patients suffering from osteoarthritis of the knee and undergoing total knee replacement. 40 patients with 42 operated knee joints were included in this study.

METHOD

38 patients (40 knee replacements) recieved a PFC endoprosthesis, 2 patients recieved a GSB endoprosthesis. In 28 cases (71%) we found generalized degenerative joint changes, in 7 cases (17%) a varus deformity and in 2 cases (5%) a valgus deformity. Post-traumatic osteoarthritis was seen in 3 cases (7%). We used the PFC endoprosthesis in patients with stable ligaments, in unstable joints we used the GSB endoprosthesis. Patients were reviewed clinically and radiographically and answered a questionnaire with special reference to ADL (walking, gymnastics, bicycling, homework, swimming, gardening). For evaluation of the results we used the Ranawat & Shine score. Pain was determined with the VAS (visual analogue pain scale).

RESULTS

The activity level increased from preoperatively 62.5% up to 91.5% 2 years postoperatively. This was mainly due to walking and gymnastics. Overall sports activities decreased. There was a high uncertainty regarding activities due to patients' lack of knowledge about possible postoperative load capacity of the new joint. The average score according to Ranawat & Shine increased from preoperative 56.98 to 75.89 points out of 100. Most significantly we found an improvement in the pain rating. There was an improvement of 73% under resting and of 81% under activity conditions.

CONCLUSION

With this prospective study we can demonstrate the benefit for patients undergoing knee replacement surgery with respect to activities of daily living and especially pain reduction.

[Results of shoulder isokinetic testing in volleyball players]

Isokinetic testing of the shoulder joint shows valuable indication to possible functional disorders and muscle imbalance. Concentric testing of several parameters using the Cybex 6000 practice unit was done by professional volleyball players performing external and internal rotation of the dominant and non-dominant shoulder at speeds of 60 degrees/s an 180 degrees/s. Sex-specific significant differences were shown which are comparable to other kind of sports.

[Possibility of sonographic early diagnosis of heterotopic ossifications after total hip-replacement]

AIM

The sonographic early diagnosis of heterotopic ossifications after total hip replacement.

MATERIAL AND METHOD

53 patients were sonographically and radiologically examined after a total hip-replacement. RESULTS. In the sonographic exam,positive findings were shown in 49.1% (n=26) one week, 66% (n=35) three weeks,73.6% (n=39) six weeks and 77.3% (n=41) twelve weeks after surgery. 88.5% of patients showing positive results in the sonographic exam carried out one week after surgery, later on showed positive x-ray findings (p<0.001). Of the three-week positive x-ray findings (n=19), 78.9% had condensations in the sonographic exam (p<0.001).

CONCLUSIONS

Sonographic imaging after hip-replacement seems to be a sensitive and specific method which allows an early diagnosis of ossifications one week after surgery in 2/3 of patients. In this context a therapy concept which helps avoiding the development ossifications would be welcome.

[Autologous chondrocyte transplantation--progress or misleading development in high-tech medicine?]

Autologous chondrocyte transplantation (ACT) is a recently developed procedure for repairing chondral defects of the knee. An analysis of the literature provides no evidence so far for regular regeneration of hyaline cartilage, and no randomized controlled studies are available showing a long-term efficacy. Therefore, controlled randomized studies are urgently needed. At present, ACT cannot be recommended for extended application in clinical practice.

The cryosurgical ablation of bone tissue by means of a new miniature cryoprobe -- evaluation of the probe and adaption of the method to in vitro human bone

Until now, modern miniature cryoprobes have been used successfully for the local destruction of soft-tissue tumors without damaging adjacent healthy tissue. In this study, the methodology of cryoablation was applied to bone, and the freezing effect as well as the cooling capacity of the probe were examined. Freezing was performed by cooling one or two probes, with a diameter of 3.2 mm, to -180 degrees C with liquid nitrogen. The cooling capacity of the probes was determined under optic and thermic control in a homogenous reference gel (gelatin), followed by an in vitro measurement on human bone. The simultaneous use of 2 probes resulted in a synergistic effect which produced an almost spherical expansion of frozen area in the homogenous gelatin. In vitro freezing of human tibiae produced equivalent freezing temperatures, with one or two probes, in comparison to the homogenous gelatin. An adequate tissue cooling of bone matrix can be achieved through the use of one or more miniature cryoprobes so that after in vivo testing, the use of this probe could possibly become an alternative or supplement to the surgical resection of pathologic bone processes.

[Treatment outcome after surgical management of osseous breast carcinoma metastases. Preventive stabilization vs. management after pathological fracture]

AIM OF THE STUDY, METHOD: The advantages of a prophylactic care of fracture-endangered, osseous metastasis of the mammary cancer stand opposite to the perioperative risk and to conservative alternatives. As a pathologic fracture cannot surely be excluded while performing a conservative proceeding, a retrospective trial was set up to compare the results of treatment after a pathologic fracture (n = 35) with those undergoing a prophylactic attendance (n = 44).

RESULTS

The intraoperative, cardio-pulmonary complications were distributed in balance totally amounting to 20.3% (n = 16). Intraoperative complications concerning surgical procedure (n = 3) exclusively occurred within the fracture group. Generally, postoperative complications arose in 20.3% (n = 16) of all cases, in which the patients belonging to the fracture group were increasingly afflicted [28.6% (n = 11/35) vs. 11.4% (n = 5/44); p < 0.02]. While there were no differences between both groups concerning the postoperative, surgery-technical complications, significantly more patients (91.8% [n = 40/44]) of the prophylactic-care group achieved a complete postoperative usability of the operated area than in the fracture-group [74.3% (n = 26/35)] (p < 0.05). The average survival time tended to be longer within the prophylactic-care group [19.3 +/- 15.6 month (prophylactic-care group) vs. 15.0 +/- 16.9 month (fracture group)].

CONCLUSIONS

The prophylactic treatment of fracture endangered, osseous metastasis of the mammary cancer leads to reduction of the general, postoperative complications compared to the patients with a pathologic fracture. Further, those patients have a better chance to recover full mobility after surgery. Considering the long survival time after the incidence of osseous metastasis at the mammary cancer a prophylactic treatment represents the method of first choice compared with the conservative treatment which persistently contains the risk of fracturing.

[Aneurysmal bone cyst of the fourth metacarpal bone--a case report]

Aneurysmal bone cysts of the hand skeleton are rare (only 3 to 4 % of all ABC; Tillmann and v. Torklus 1966 ) and require a differentiated treatment. In the presented case, the fourth metacarpal bone of the right hand was affected (Enneking stage 3). On account of its rapid growth, radical excision was performed and the resected metacarpal bone was replaced by a bicortical iliac crest graft. The bone graft healed in without complications, the functional result is satisfactory. On twelve-month follow-up there were no signs of relapse.

Intraosseous lipoma of the calcaneus

BACKGROUND AND AIMS

Intraosseous lipoma of the calcaneus is thought to be a rare tumour. As most of the articles have been single case reports, we performed a meta-analysis to evaluate diagnostic and therapeutic procedures.

METHODS

Based on 54 cases located at the calcaneus, typical features and treatment were studied.

RESULTS

A predilection was seen for adults between 30 and 60 years of age. Males were affected in two of three cases. The lesions were found incidentally in 33%. Symptomatic cases presented with pain, and some patients showed additional tenderness or swelling. All calcaneal lipomas were located at the base of the neck of the calcaneus (Ward's triangle). Radiological appearance depends on the stage due to evolutionary changes of the tumour. Diagnosis can be established with CT or MRI, as both methods show fat-equivalent densities in the lesion. Pathological fracture has not been reported.

CONCLUSION

Continued observation in asymptomatic cases is a reasonable clinical approach. We propose surgical treatment with curettage and bone grafting only in symptomatic cases.

[Cryosurgical ablation of bone tissue with a newly developed miniature cryoprobe--adaptation of the method for use in bones in vitro and in vivo]

AIM

Up to now, modern miniature cryoprobes have been used successfully for local destruction of soft tissue tumors without damaging adjacent healthy tissue. In this study, the methodology of cryoablation was applied to bone and the freezing effect as well as the cooling capacity of the probe was examined in vivo and in vitro.

METHODS

Freezing was performed by cooling one or two probes, with a diameter of 3.2 mm to -180 degrees C with liquid nitrogen. The cooling capacity of the probes was determined under thermic control by an in vitro measurement on human bone, followed by an in vivo measurement on femoral and tibia bones of a sheep.

RESULTS

The in vitro freezings achieved a sufficient tissue cooling using one or two cryoprobes. The simultaneous use of 2 probes resulted in a synergistic effect between the probes. According to the body heat, the registered temperature curves, during the in vivo freezings, showed a more flat trend. Nevertheless, temperatures below -50 degrees C were achieved at a distance of 1 cm from the probe due to the synergistic effect. Local or systematical intraoperative complications have not been observed.

CONCLUSION

An adequate tissue cooling of bone matrix can be achieved within in vivo freezings through the use of one or more miniature cryoprobes so that the use of this probe could possibly become an alternative or supplement to the surgical resection of pathologic bone processes.

Comparison of iceball diameter and temperature distribution achieved with 3-mm accuprobe cryoprobes in porcine and human liver tissue and human colorectal liver metastases in vitro

We aimed to assess the thermal profile and size of iceballs produced by Accuprobe cryoprobes in fresh porcine and human liver and human colorectal cancer liver metastases in vitro to allow better planning of cryosurgical treatment of liver metastases. Iceballs were produced by a 20-min single freeze cycle using 8-mm cryoprobes in pig liver in a waterbath at 37 degrees C (n = 8) and 3-mm cryoprobes in pig liver (n = 8), human liver (n = 3), and human colorectal cancer liver metastases (n = 8). The iceball diameters and the temperatures at different distances from the cryoprobe were measured. Mean iceball diameters produced by 8-mm cryoprobes in pig liver were 56.3 mm and varied from 38.7 to 39.6 mm for 3-mm cryoprobes in the different tissues used. There was no significant difference in iceball size in the different tissues. The diameter of the zone of -40 degrees C or less was approximately 44 mm using 8-mm cryoprobes in porcine liver and between 27 and 31 mm using 3-mm cryoprobes in the different tissues examined. The results may allow better preoperative planning of the cryosurgical treatment of liver metastases with Accuprobe cryoprobes.

[Cholecystectomy in high risk patients. A comparison between conventional and laparoscopic procedures]

Laparoscopic cholecystectomy offers many advantages, but cardiopulmonary impaired patients may be endangered by the haemodynamic and respiratory effects of the pneumoperitoneum. Between June 1990 and December 1995, laparoscopic cholecystectomies were performed on 19 high-risk patients (ASA IV) and conventional cholecystectomies on 26 patients with the same operative risk (ASA IV). Out of 45 patients, 5 (11.1%) suffered intraoperative cardiopulmonal complications. Three belonged to the group with laparoscopic cholecystectomy (15.8%) and two to the group with open laparotomy (7.7%). General postoperative complications occurred in 15 cases (33.3%), whereby patients of the conventional cholecystectomy group were concerned more often [46.2% (n = 12) versus 15.8% (n = 3), P = 0.03]. The number of days spent in hospital after open cholecystectomy was higher (P = 0.01) (11.6 +/- 5.6 days in the laparotomy group versus 7.6 +/- 5.0 days in the laparoscopy group). The classification as a high-risk patient indicates an elevation of the perioperative rate of complications in laparoscopic and open cholecystectomy, whereby the rate of postoperative complications is lower in the laparoscopic group.

[Laparoscopic cholecystectomy in high risk patients]

As opposed to the advantages of laparoscopic cholecystectomy, patients with cardiopulmonary impairment may be endangered by the haemodynamic and respiratory effects of the pneumoperitoneum. Between June 1990 and December 1995, laparoscopic cholecystectomies were performed in 19 high-risk patients (ASA IV) and 465 patients with a lower operative risk (ASA I-III). Out of 484 patients, 24 (5%) suffered intraoperative cardiopulmonary complications. Three belonged to the high-risk group (15.8%) and 21 to the lower risk groups (4.5%). General postoperative complications occurred in 14 cases (2.9%), whereby patients of the ASA IV group were, again, concerned more often [15.8% (n = 3) of ASA IV versus 2.4% (n = 11) of ASA I-III]. The number of days spent in hospital was 7.6 +/- 4.96 days in the high-risk group versus 4.8 +/- 2.23 days in groups ASA I-III. The evaluation as a high-risk patient indicates an elevation of the perioperative rate of complications in laparoscopic cholecystectomy; however, it is not basically a contraindication for this operative method.

Agglutination of Antigens from Distemper-Infected Dogs and Ferrets by Anticanine-Distemper Immune Sera

Organs and body fluids of dogs and ferrets experimentally infected with the virus of canine distemper contain an antigen that reacts specifically with an antibody present in the serum of immunized and hyperimmunized dogs.

The antibody-antigen reaction is demonstrated by the agglutination of heat-killed suspensions of B. prodigiosus that had been in contact with the organ-extracts or the body-fluids of infected animals.