Bone remodelling in the pores and around load bearing transchondral isoelastic porous-coated glassy carbon implants: experimental study in rabbits

Cylinders of porous-coated glassy carbon were implanted into drill holes made through the articular surface of the medial condyle of both tibiae of ten rabbits for six and 12 weeks. Bone ingrowth and remodelling was examined by radiographic, histologic, oxytetracycline-fluorescence and microradiographic methods. Bone ingrowth into pores and load bearing implants was seen by all examination methods. Bone ingrowth occurred earlier when the pores were facing cancellous bone than cortical bone. Appositional bone formation occurred on the trabeculae a few millimetres from the interface during the early phase of remodelling at six weeks. At 12 weeks resorptive remodelling had occurred both in the surroundings and in those pores that face cancellous bone, whereas the amount of bone still increased in the pores facing cortical bone. In its porous-coated form glassy carbon functions well as a frame for ingrowing bone and it shows good osteoconductivity. Its mechanical properties are suitable for functioning as a structural bone substitute in places where the loads are mainly compressive. The difference between findings at six and 12 weeks indicated physiologic stress distribution and the adverse effects of stiff materials on bone remodelling were avoided by using this isoelastic material.

Shear strength of loaded porous-glassy-carbon/bone interface--an experimental study on rabbits

The aim of the study was to measure the shear strength of bone/porous-glassy-carbon interface in rabbit. Glassy carbon pellets were implanted into drill holes made through the medial articular surface of the proximal tibia of 15 rabbits. Shear strengths grew statistically significantly from 1 to 6 weeks and reached a maximum of 4.6 MN/m2. Microscopical examination of the sheared surfaces revealed that at 1 and 2 weeks the shearing occurred through the tissue surrounding the implant, and at 3, 6 and 12 weeks through the porous coating of the implant. To diminish the fragility of the porous coating, its porosity should be adjusted to 40%. Results of shear strength studies on current implant materials are reviewed.

Fluid resuscitation of hypotensive emergency patients with and without an algorithm

Seventy-seven consecutive hypotensive (mean arterial pressure (MAP) less than 80 mmHg) surgical emergency patients were resuscitated according to either physicians' individual orders (38 patients) or an algorithm (39 patients). The shock was mainly caused by accidental injuries or acute gastrointestinal bleeding. The patients of the algorithm group were given more plasma expanders than the patients of the control group, while the total amount of fluids administered was similar in both groups. The primary goal of the resuscitation (MAP greater than 80 mmHg) was reached within 30 min in three cases in the control group and in seven cases in the algorithm group. The treatment times at the emergency department and the intensive care unit were similar for the groups. The number of severe and moderate pulmonary disturbances was the same, but mild disturbances were significantly more common in the control group. Renal failure was somewhat more common in the control group and the renal function disturbances were significantly more severe among the control patients. The results suggest that the physicians in some extent altered their practices in fluid resuscitation when the algorithm was put to use, and that this change, perhaps, produced the somewhat better outcome of the patients. The authors recommend the algorithm to be used as a basis of shock treatment and particularly in those emergency departments where the resuscitation of hypotensive patients is performed by junior or inexperienced physicians.

Chondromalacia patellae. Results of operative treatment

The series consisted of 26 patients operated on in 1972-1978 for chondromalacia patellae. The patients were followed up an average of 4.6 years after the operation. The operation involved one knee in 21 patients, both knees in 5. The primary operation was carried out for lesions of the articular cartilage of the patella alone in 18 cases (in 6 of these a second operation was necessary) and for a biomechanical disturbance of the patellofemoral joint in 13 cases. Degenerative changes of the patellar cartilage were observed at anatomo-pathological examination in 29 of 31 knees. On average, the patients' symptoms were alleviated after the operation, but comparison of different types of operation showed a statistically significant improvement only after operations that modified the biomechanics. The results confirm the view that symptoms originating in the patellofemoral joint often are due to biomechanical disturbances of this joint and the extensor system of the knee, and that the removal of injured cartilage alone is not sufficient.

Bone growth into glassy carbon implants. A rabbit experiment

This study was designed to evaluate the growth of bone into porous glassy carbon cylinders. Porous carbon cylinders were implanted in 30 rabbits intra-articularly in the metaphysis of the femur opposite from the patella. The rabbits were sacrificed up to 24 weeks after the operation. The bone samples were examined by histologic, fluorochrome and microradiographic methods. The amount of bone ingrowth was measured histomorphometrically. Fluorochrome uptake was seen in the implant pores, which indicated new bone growth originating from surrounding bone. After 3 weeks, microradiographs revealed new bone formation in the pores and with time the bone spicules became more dense. The amount of bone tissue in the pores grew and reached a maximum at 12 weeks, when 45 per cent of the total pore volume was incorporated with bone tissue. No adverse tissue responses were observed.

A prospective comparative study on serum acid phosphatases in the diagnostics of prostatic cancer

The diagnostic efficacy of two prostatic tumor markers, S-AP and S-PAP, was compared in a prospective clinical series consisting of 101 BPH- and 39 PCa-patients. As a predictor of prostatic cancer the specificity of S-AP (greater than or equal to 12 U/1) and S-PAP-RIA (greater than or equal to 4 micrograms/1) was 0.97 and 0.96, and the sensitivity 0.21 and 0.41, respectively. The S-PAP-RIA value of over 8 micrograms/1 always predicted an inoperable prostatic cancer (T4 or M1). The authors conclude that neither of these enzymes is suitable for the screening of early prostatic cancer, but the S-PAP-RIA might be a good predictor of inoperability of advanced prostatic cancer.

Myelographic versus clinical diagnostics in lumbar disc disease

The series consisted of 200 patients on whom lumbar myelography was performed for sciatica. After myelography, a disc operation was carried out on 95 patients. The episode of sciatica was the first for 90 patients. Objective neurologic signs were present in 185 patients, while 15 had only subjective symptoms. Definite or possible disc herniation was revealed by myelography in 66%. Most positive findings were located at the L4-L5 interspace. The clinical diagnostic accuracy rate was assessed from the patients' histories. As confirmed by operation, the accuracy of the clinical diagnostics was 52%, and the accuracy rate of myelography was 90%. The rate of false positive findings in myelography was 4%, that of false negative findings 6%. When the clinical or myelographic diagnosis was definitive, a disc herniation or protrusion was always found at operation. Almost one fourth of the clinically diagnosed definite herniations were not treated surgically because myelography proved negative. One fifth of those patients in whom myelography revealed an unequivocal disc herniation were not operated on because these patients had clinically improved before being admitted to myelography. The results of this study justify the following conclusions: the clinical level diagnostics of a disc herniation is rather unreliable, and myelography is therefore always indicated before operation; myelography should only be performed in those cases in which there is a clear clinical indication for surgery; myelography ought to be performed within 1 week; an unequivocal positive finding in myelography predicts a good operative result.

Tinidazole prophylaxis in appendicectomies. A controlled study of single-dose versus 3-day therapy

The 588 consecutive patients who were operated on on suspicion of appendicitis were randomized into three groups: the control group (no prophylaxis); the single-dose group (preoperatively 500 mg of tinidazole intravenously); and the 3-day group (in addition to the former, a 3-day tinidazole treatment). To discover any postoperative infectious complications, the patients' follow-up study was extended for at least 1 month. Such complications emerged in 12% of the patients in the control group, in 7% of those in the single-dose group, and in 5% of those in the 3-day group. A statistically significant difference in the incidence of infectious complications was established between the control group and the prophylaxis groups. The 3-day tinidazole treatment, as compared with the single-dose prophylaxis, did not further improve the outcome. On the basis of these results the authors recommend that all patients subjected to an appendicectomy be given an intravenous tinidazole prophylaxis.

Concentrations of metronidazole and tinidazole in abdominal tissues after a single intravenous infusion and repetitive oral administration

Concentrations of metronidazole and tinidazole in serum and abdominal tissues were determined after a single 500-mg intravenous infusion or after a 5-day oral dosage of 500 mg three times daily in groups of 10 patients each. In the patients who got the single infusions, the concentrations in tissues (except fat) reached almost the serum levels 10 min after the infusion. At 24 h, the tinidazole concentrations in serum averaged 3.2 micrograms/ml and those of metronidazole 1.3 micrograms/ml. In the patients who got the 5-day oral dosages, the steady-state levels of tinidazole in both serum and tissues were twice as high as those of metronidazole.

Importance of anatomical reduction for subjective recovery after ankle fracture

237 patients with ankle fractures treated during 1977 were evaluated with the object of studying the treatment results and the factors influencing the results. About one half of the patients were treated conservatively and the other half operatively. The type of treatment was determined by the type of injury; hence the milder injuries were usually treated conservatively and the more severe cases operatively. A good radiological primary result was obtained in 82 per cent of the malleoli with operative treatment and in 34 per cent with conservative treatment. The evaluation of the end-result was based on a questionnaire study made 1.5-2.5 years after the accident. All those employed before their injuries had returned to their previous occupations. 27 per cent of the patients responded that they had recovered completely. The subjective end-result was found to correlate with the radiological result at the end of the treatment, but not with the type of injury, the type of treatment, or the patient's age.

Serum and tissue tinidazole concentrations after intravenous infusion

Before appendectomy 36 adult patients were given an intravenous infusion of 500 mg of tinidazole. In the operation tissue samples were taken (blood, base of appendix vermiformis, muscle, fat) either 10, 20, 30, 60, or 120 min after cessation of infusion. The tinidazole concentrations were determined by liquid chromatography. The weight-standardized tinidazole concentrations in the serum, muscle tissue and appendix in all specimens were higher than the minimal inhibitory concentration (2 micrograms/g) of Bacteroides fragilis. The tinidazole concentrations of adipose tissue exceeded the limit of 1 microgram/g in all samples. The concentrations were high already in the 10-min patient group. The authors consider a tinidazole infusion started half an hour before the operation at a dose of 10 mg/kg of the patient's body weight to be a reliable procedure if the objective is to acquire a sufficient tissue concentration of tinidazole (2 micrograms/g) to prevent infection complications caused by anaerobic bacteria.

Head injuries and skull radiography: clinical factors predicting a fracture

Five hundred and ninety-eight cases were studied where the patients had been subjected to skull radiography because of a head injury. Concussion had been established in 231 patients and a more severe brain injury in 8. Forty-nine patients (8.2 per cent) had skull fractures. The relative frequency of fractures was the highest among those aged between 40 and 59 years (16 per cent). From among 16 variables, either clinical or pertaining to the history, 4 had clearly sustained a fracture of the skull, the statistically significant features being amnesia, unconsciousness for over 30 minutes, a wound and subcutaneous haematoma in the scalp and a reduced level of consciousness. On the basis of these signs the patients could be divided into two groups which differed in the frequency of skull fractures by a factor of five. The skull fracture was not observed to have influenced the patient's care or recovery, particularly if the patient had a concurrent brain injury. Based on the results, the indications for skull radiography in patients with head injuries can be identified and this can reduce the need for X-ray examinations to one-half and still reveal 80 per cent of skull fractures.

Cost-benefit analysis of posterior fusion of the lumbosacral spine

In this study the cost-benefit ratio of posterior fusion of the lumbosacral spine was assessed. The calculations were based on 118 operated patients, followed up for an average of 4.8 years. Costs were calculated using the average costs of treatment at central hospitals, visits to the outpatient department and travelling. The costs for one patient exceeded on average 5,569 US dollars. The economic benefits derived from the operations were estimated by the work output of those 36 patients who postoperatively returned to their previous or a corresponding occupation. The postoperative work output was estimated using the coefficients for known causes of retirement (emigration, mortality, disability). The benefits of one lumbosacral fusion amounted on average to 16,075 US dollars. Fusion of the lumbosacral spine prove to be profitable at a cost-benefit ratio of 1 : 2.9. If the selection of patients for operation could be made so as to guarantee that working capacity is restored by operative treatment, the cost-benefit ratio might be improved to 1 : 9.5. It is emphasized that cost-benefit analyses of surgical procedures are important from the standpoint of principles of treatment and priority of operations. This study deals with economic aspects only. The medical aspects of the present material have been presented in two previous papers.

Posterior fusion of the lumbosacral spine. Evaluation of the operative results and the factors influencing them

The operative results of 79 patients subjected to posterior fusion of the lumbosacral spine were evaluated on the basis of a follow-up examination performed on average 5.4 years after operation. A method of evaluation was developed which measured the patients' subjective improvement and working capacity. The method proved appropriate for clinical use and gave a more correct picture of the operative result than methods relying on the patients' own opinion or the radiographic assessment as the only criterion. Sixty per cent of the patients were subjectively improved, 40 per cent had returned to their previous or a corresponding occupation and 24 per cent had a good operative result, assessed by the method applied. A statistical analysis was performed in order to find the factors influencing the operative results. Age over 40 years, heavy or moderately heavy preoperative work and over 6 months' preoperative disability had a statistically significant, unfavourable effect on the results. In the case of labourers in heavy occupations, working capacity was seldom restored to a degree sufficient for return to their previous work. The operative technique proved reliable with 91 per cent successful fusions, assessed from functional radiographs. Successful fusion did not imply a good operative result, although it did so more often than non-fusion. On the basis of this study, operative fusion of the lumbosacral spine seems to be of relatively little value in the treatment of patients suffering from low back pain, and factors other than purely medical or surgical have a considerable influence on the operative results.

Cloward's anterior fusion in the treatment of cervical spinal traumatic injury and degeneration

The aim of this study was to evaluate the long-term results of Cloward's anterior interbody fusion of the cervical spine and to identify the factors influencing them. The series consisted of 29 patients operated on in 1968--75. The indication for operation was in 12 cases intensive radicular symptoms, not responding to conservative treatment, in connection with considerable degeneration of the corresponding spinal segment only, and in 17 cases instability of the cervical spine caused by traumatic injury followed by dislocation and radicular or medullary symptoms enhancing in spite of conservative treatment by skull traction or collar. Twenty-five patients (86%) attended follow-up after an average time lapse of 6.5 years from operation. The operative result was evaluated considering objective neurological improvement, subjective improvement, present symptoms and working capacity. The operative result was at least fair in 7/11 in the degeneration group and in 12/14 in the traumatic injury group. All fusions were radiologically successful. Adequate correction of a primary flexion deformity of more than 15 degrees was not achieved. Age over 35 years and motor defect preoperatively proved to be statistically significant prognostic factors for a poor operative result in the traumatic injury group. Preoperative sick-leaves and a duration of preoperative symptoms exceeding six months proved to be prognostic factors for a poor result in the degeneration group. In spite of the relatively good clinical results obtained, this study does not justify any conclusions concerning the value of Cloward's procedure compared to other methods of treatment, since no control material was available.

Lumbosacral fusion by standing h-graft technique

Fusion of the lumbosacral spine was carried out on 44 patients. A modification of the standing H-graft technique was used in 41 of the patients. The operative diagnosis was degeneration of the lumbosacral spine in nearly two-thirds of the cases and spondylolisthesis in about one-third. Operations for low back or sciatic pain had previously been performed on 17 patients. The duration of postoperative bed rest ranged from one to six weeks; a lumbosacral corset was used at least for six weeks postoperatively. The average stay in hospital was 52 days. Complications occurred in five cases. The operative results of 40 patients were evaluated on the basis of a follow-up examination performed on average 3.6 years after operation. Nearly half the patients with radiologically successful fusions had a good subjective improvement and about one-fourth had returned to their previous or corresponding occupations. The operative result was at least fair in about half the patients, assessed by a measure of the patients' subjective improvement and working capacity. In the non-fusion group (six cases) the operative results were exclusively poor. Age over 40 years, long-standing preoperative disability and previous back operations proved prognostic factors for poor results. Assessed from functional radiographs, 63% of two-segment fusions and 95% of one-segment fusions were successful. The operative technique appeared simple and suitable for fusions of one spinal segment, but the value of the lumbosacral fusion in the treatment of low back pain seemed doubtful because of the great proportion of poor clinical results even following technically successful fusions.