Temperature changes during cortical bone drilling with a newly designed step drill and an internally cooled drill.

PURPOSE: Bone drilling causes an increase in bone temperature, and a temperature above 47°C is critical because it causes thermal bone necrosis. Thermal osteonecrosis is common with the drill diameter of ≥4.5 mm without cooling. The aim of this study was to determine the increase of bone temperature during drilling using newly contructed two-step and internally cooled drills. METHODS: An experiment was set up according to a central composite design. An internally cooled drill (3.4 mm and 4.5 mm) and a two-step drill (2.5/3.4 and 3.4/4.5 mm) were used in combination with feed rates of (0.02, 0.04, 0.10, 0.16 and 0.18 mm/rev) and cutting speeds (1.18, 10.68, 33.61, 56.55 and 66.05 m/min) with and without cooling with water of 24°C. Bone temperatures were measured with thermocouples. Drilling was performed on pig diaphyses with a three-axis mini milling machine. RESULTS: Bone temperatures in all combinations of parameters with internal cooling were below the critical 47°C (p=0.05). The highest temperatures were detected using a 4.5-mm drill (40.5°C). A statistically significant effect other than cooling was found with the drill diameter and feed. A drill diameter of 3.4 mm with internal cooling developed a maximum temperature of 38.5°C and without cooling 46.3°C. For the same conditions a drill with diameter of 4.5 mm reached temperatures of 40.5°C and 55.7°C, respectively. The effect of feed rate is inversely proportional to the increase in bone temperature. With the feed rate 0.16 mm/rev, temperature was below critical even using the 4.5-mm drill (46.4°C, p=0.05). Using the 3.4-mm drill all temperatures were below critical (46.2°C, p=0.05). The two-step drill compared to a standard drill with the same diameter did not show statistical differences in maximum bone temperatures for all combinations of parameters (p=0.05). CONCLUSIONS: A two-step drill does not have any advantages over a standard twist drill of the same diameter. An internally cooled drill causes a significantly smaller increase of bone temperature during drilling with water of 24°C. An internally cooled drill is currently the 'ideal' drill for traumatology/orthopaedics because it produces the smallest increase in bone drilling temperature. If internal cooling is used the regulation of other drilling parameters is of no importance.

[Results of treatment of tibial fractures in children]. / Rezultati lijecenja prijeloma potkoljenice u djece.

Diaphyseal fractures of both lower leg bones are the most common fractures of lower extremities, and account for about 15% of all fractures of long bones in children. These fractures are usully unstabilae, difficult to reposition, and retention of the fragments, and the process of their treatment is not fully compliant. The paper analyzes the late results of treating 234 children with tibial fractures, depending on the method of treatment (surgical and conservative method). Twenty-three children had open fractures (9.8%). Nonsurgical method was used in the treatment of 194 children, and surgical in 40 children. The most frequent surgical method was closed reposition of the fragments, and percutaneous elastic stable intramedullary nailing with titanium wires. The success of the treatment was measured: residual angular deformities and difference in length between treated and healthy leg. Secondary displacement of fragments after primary conservative treatment was found in 32 children. Angular deformities of the treated tibia was seen in 80 children, 68 (35.0%) treated conservatively and 12 (30.0%) surgically. In 131 (67.5%) conservatively treated and 29 (72.5%) surgically treated children there were no differences in the length of sick and healthy leg. Results of treatment in our children confirmed that there were no statistically significant differences in late effects depending on treatment methods.

[Results of treatment of displaced supracondylar fractures in children]. / Rezultati lijecenja suprakondilarnih prijeloma humerusa s pomakom ulomaka u djece.

Supracondylar fractures of humerus are the most common fractures in children. The management of severely displaced, unstable fractures of the humerus in children continues to be controversial. We undertook a retrospective study of 48 children with displaced supracondylar fractures (8 were treated with plaster and 40 with cross percutaneous Kirschner wire pinning). Only three children were treated with open reduction and percutaneous cross-pin fixation. Clinical outcome was evaluated by loss of elbow motion and change of carrying angle. According to Flynn s criteria, results were good or excellent in 93.7% patients. The cubitus varus is the most frequent long-term complication (16.7%). Closed reduction with percutaneous pin fixation is believed to represent a safe, reliable, and efficient method of managing displaced supracondylar fractures.

Determination of spatial distribution of increase in bone temperature during drilling by infrared thermography: preliminary report.

INTRODUCTION: During the drilling of the bone, the temperature could increase above 47 degrees C and cause irreversible osteonecrosis. The spatial distribution of increase in bone temperature could only be presumed using several thermocouples around the drilling site. The aim of this study was to use infrared thermographic camera for determination of spatial distribution of increase in bone temperature during drilling. MATERIALS AND METHODS: One combination of drill parameters was used (drill diameter 4.5 mm; drill speed 1,820 rpm; feed-rate 84 mm/min; drill point angle 100 degrees) without external irrigation on room temperature of 26 degrees C. The increase in bone temperature during drilling was analyzed with infrared thermographic camera in two perpendicular planes. Thermographic pictures were taken before drilling, during drilling with measurement of maximal temperature values and after extraction of the drill from the bone. RESULTS: The thermographic picture shows that the increase in bone temperature has irregular shape with maximal increase along cortical bone, which is the most compact component of the bone. The width of this area with the temperature above critical level is three times broader than the width of cortical bone. From the front, the distribution of increase in bone temperature follows the form of the cortical bone (segment of a ring), which is the most compact part and causes the highest resistance to drilling and subsequent friction. CONCLUSIONS: Thermography showed that increase in bone temperature spreads through cortical bone, which is the most compact and dense part, and generates highest frictional heat during drilling. The medullar cavity, because of its gelatinous structure, contributes only to thermal dissipation.

Application of a novel bone osteotomy plate leads to reduction in heat-induced bone tissue necrosis in sheep.

Previous studies have shown substantial effect thermal damage can have on new bone formation following osteotomy. In this study we evaluated the extent of thermal damage which occurs in four different methods of osteotomy and the effects it can have on bone healing. We further wanted to test whether a special osteotomy plate we constructed can lead to diminished heat generation during osteotomy and enhanced bone healing. The four methods evaluated included osteotomy performed by chisel, a newly constructed osteotomy plate, Gigly and oscillating saw. Twelve adult sheep underwent osteotomy performed on both tibiae. Bone fragments were stabilized using a fixation plate. Callus size was assessed using standard radiographs. Densitometry and histological evaluation were performed at 8 weeks following osteotomy. Temperature measurements were performed both in vivo during the operation, and ex vivo on explanted tibiae. The defects healed without complications and showed typical course of secondary fracture healing with callus ingrowth into the osteotomy gap. Radiographic examination of bone healing showed a tendency towards more callus formation in bones osteotomized using Gigly and oscillating saw, but this difference lacked significance. Use of Gigly and oscillating saw elicited much higher temperatures at the bone cortex surface, which subsequently lead to slightly impaired bone healing according to histological analysis. BMD was equal among all bones. In conclusion, the time required for complete healing of the defect differed depended greatly on the instruments used. The newly constructed osteotomy plate showed best results based on histological findings of capillary and osteoblast density.

Treatment of war injuries of the shoulder with external fixators.

In this retrospective study, 18 patients with war injuries of the shoulder were reviewed to evaluate the technical problems associated with external fixation and to analyze the incidence of infection and late functional results. The average patient age was 28.5 years. All patients were male. Thirteen patients had explosive wounds, whereas five wounds were caused by gunshot missiles. All injuries were extensive in terms of bone and soft tissue defects. Six patients presented with complex injuries involving neurovascular structures. Sixteen patients were treated with external fixation. Application of the proximal pins of the external fixator through the humeral head was possible in eight patients, the scapula served as the site of proximal fixation in four patients, only the clavicle was available for placement of pins in two patients, and both the scapula and the clavicle had to be pinned to achieve proximal stabilization in two patients. In two patients, fixation was not possible and early amputation was performed. Infection was eventually eradicated in all patients, allowing for adequate soft tissue coverage of the wounds. Analysis of functional results at an average of 6 years after the injury showed a considerable degree of functional deficit in most patients.

Thermal changes during healing of distal radius fractures-Preliminary findings.

INTRODUCTION: The bone healing process is very complex. In simple terms, bone healing comprises three basic steps, the inflammation phase, the repair phase and the remodelling phase. The increase in blood flow around the fracture during the healing process increases the temperature of the surrounding tissue. Infrared thermography is a method of measuring body temperature that can detect temperature changes during bone healing. Studies on the application of thermography in traumatology are scarce, and there are no studies of thermal changes during normal bone healing. The authors have tried to determine the dynamics of thermal changes during bone healing. MATERIAL AND METHODS: The Flir ThermaCam B2 (FLIR Systems, Inc., Oregon, USA) was used for all measurements. Thermographic recordings were made one, three, five, 11 and 23 weeks after fracture. The contralateral, healthy, forearm was used for comparison. RESULTS: A total of 25 patients of mean age 65.9±10.4 years (range 50-80 years) with fracture of the distal radius were examined in this study. The mean temperature difference between healthy and fractured distal forearm one week after fracture was 1.20±0.48°C, three weeks after fracture was 1.42±0.54°C, five weeks after fracture was 1.04±0.53°C, 11 weeks after fracture was 0.50±0.30°C, and 23 weeks after fracture was 0.22±0.25°C. CONCLUSION: Preliminary findings during this research showed significant temperature changes during healing of distal radius fractures. Infrared thermography is a simple and reliable method in clinical practice that could be used as a good follow-up method in traumatology, but further investigations on more patients are needed.

Reducing damage to the periosteal capillary network caused by internal fixation plating: An experimental study.

BACKGROUND: The importance of the periosteum in fracture healing is well-known. Preserving periosteal vascularisation is essential during internal plate fixation of fractures. METHODS: This was an experimental randomised, controlled animal study on nine sheep. Standard dynamic compression plate (DCP) and four different newly designed reefed plates, with different plate-bone contact surface areas and different reef directions, were fixated on to the tibia or radius. After two weeks the plates were removed and the underlying periosteum was analysed. Blood vessels were marked by immunohistochemical staining (CD31 and CD34), microphotographs were taken and blood vessels counted to calculate blood vessel density. RESULTS: Median blood vessel density beneath the standard plate was significantly lower than in the intact periosteum (18.0 vs 27.7mm(3)/cm(3)). Blood vessel density in the periosteum beneath plates with reefs was significantly increased compared with the intact periosteum, and was highest beneath the plate with the lowest bone-plate contact area and crosswise reefs (51.5mm(3)/cm(3)), followed by plates with transverse, oblique and longitudinal reefs, respectively. The direction of the reefs did not have much influence on the periosteal capillary network. Lower contact surface area seems to be the main factor that increases blood vessel density beneath the plates. CONCLUSIONS: The results show that plates with lower contact surface area stimulate angiogenesis in the underlying periosteum, which results in much higher blood vessel density compared with standard DCP. A randomised clinical trial is needed to prove the clinical relevance of these findings.

Implementing the Surgical Apgar Score in patients with trauma hip fracture.

BACKGROUND: Trauma hip fractures in elderly patients are associated with high postoperative long-term morbidity and mortality and premature death. The high mortality in these patients can be explained by various factors, including the fracture itself; the preoperative poor condition and comorbidities of these patients; the influence of stressors, such as surgery and type of anaesthesia, on the patient's condition; and the postoperative development of major complications, such as cardiac failure, pulmonary embolism, pneumonia, deep venous thrombosis and acute renal failure. Thus, the Surgical Apgar Score (SAS) could be a valuable tool for objective risk stratification of patients immediately after surgery, and to enable patients with higher risk to receive postoperative ICU care and good management both during and after the hospital stay. METHODS: The SAS was calculated retrospectively from the handwritten anaesthesia records of 43 trauma hip fracture patients treated operatively in the University Hospital Centre Zagreb over a 1-year period. The primary endpoints were the 30-days major postoperative complications and mortality, length of the ICU and hospital stay, and 6-months major complications development. Statistical analysis was applied to compare SAS with the patients' perioperative variables. RESULTS: A SAS≤4 in the trauma hip fracture patients was a significant predictor for the 30-days major postoperative complications with 80% specificity (95% CI: 0.587-0.864, p=0.0111). However, the SAS was not significant in the prediction of 30-days mortality (95% CI: 0.468-0.771, p=0.2238) and 6-months mortality (95% CI: 0.497-0.795, p=0.3997) as primary endpoints in the hip fracture surgery patients. CONCLUSION: The SAS shows how intraoperative events affect postoperative outcomes. Calculating the SAS in the operating theatre provides immediate, reliable, real-time feedback information about patient postoperative risk. The results of this study indicate that all trauma hip fracture patients with SAS≤4 should go to the ICU postoperatively and should be under intensive surveillance both during the hospital stay and after hospital discharge.

Quality of life in osteoporotic patients with hip fracture and without fracture.

The aim of this study was to analyse the quality of life in osteoporotic patients with hip fracture and those without fractures. The study included postmenopausal women, 35 with hip fracture and 33 without fractures. The control group included 44 age-matched healthy women. Osteoporosis Quality of Life Questionnaire was used to assess the health-related quality of life (HRQL). Patients with hip fracture had significantly lower scores in symptoms, physical function and leisure (P < 0.05), than patients without fractures. Both groups of patients had significantly lower scores than controls in all domains except Leisure. Analysing several health and social factors that could influence HRQL, we found that bone mass in spine and femoral neck significantly correlated with HRQL. Since patients with osteoporosis usually have no symptoms before fracture, early diagnosis and the treatment of the disease are of key importance to the quality of life in these patients.

Operative management of unstable ankle fractures in the elderly: our institutional experience.

Ankle fractures represent an exceptionally common injury within the elderly population. The total incidence of ankle fractures has been reported to be up to 184 fractures per 100,000 persons per year, of which 20 to 30 percent occur in the elderly. This study reports the results of operative management of ankle fractures in the elderly, with regard to functional outcome and complication rates. This was a retrospective, non-randomized observational study. Subjects were identified from a trauma registry kept in our Department and were tested for eligibility. Patients were then categorized into two groups according to their age: Group A included all patients less than 65 years of age and Group B included all patients over the age of 65. The outcome was measured using the AOFAS Ankle-Hindfoot score and a Linear analog scale. A total of 120 consecutive patients fulfilled the eligibility criteria and were included in our study (60 patients in each group). We detected statistically significant difference between the LAS score of the two groups (p=0.02), the alignment between the two groups (p=0.04) and the AOFAS score versus LAS score in Group B (p=0.03). Two patients from Group B had wound dehiscence, but finally their wounds healed uneventfully. We didn't observe any serious complications such as skin necrosis, deep infection, osteomyelitis and failure of metalwork. Our study suggests that the operative management of Weber B2 and B3 injuries can result in a favorable outcome. It is however of great importance that there are no delays in treatment, that the reduction is anatomical, that the fracture fixation is satisfactory and that the rehabilitation is commenced early.

Intraoperative measurement of bone electrical potential: a piece in the puzzle of understanding fracture healing.

INTRODUCTION: Bone electrical potentials change with the force applied. Also, fracture alters the bone electrical potential, so it becomes more electronegative. These potentials have an important role in fracture healing, bone growth and remodelling. Literature data on the influence of fracture operative treatment on bone electrical potentials, and possible consequences of this influence, are sparse. The objective of this study was to establish a method of intraoperative bone potential measurement, and to try to find a correlation between electrical potential and fracture type, osteosynthesis method and prognosis. PATIENTS AND METHODS: 52 patients with a pertrochanteric fracture were included in the study. Bone electrical potentials were measured intraoperatively using a thin Kirschner wire introduced through bone cortex at the selected point and pointed to opposite cortex, not penetrating it. Kirschner wires were connected using clamps to multimeter (YF-78 Multimeter) device. Neutral electrode (inductive rubber) was placed behind ipsilateral gluteus. RESULTS: Near the fracture site potentials of -199 up to -267 mV were recorded. Mean measured potential of bone plate after fixation was -240 mV. Bone potentials correlated with the subtype of fracture and early mobilisation of patients. CONCLUSIONS: Bone potentials, caused by fracture, can be measured intraoperatively; the operative procedure appears to influence their generation. Measured potentials depend on the fracture type, and could be correlated with prognosis.

Mathematical approximation of fibular malleolus curvature.

While there are several manuscripts describing the articular surfaces of the ankle joint and the fibula itself, there is no study describing the outer surface and the degree of curvature of the fibular malleolus. This paper aims to approximate the sagital curvature of the outer surface of the lateral malleolus mathematically. Such data would facilitate the design of the anatomic plate that can be used for the ostheosynthesis of the fibular malleolus fracture. 30 males who were examined in the emergency department due to ankle sprains, where they underwent a standard anteroposterior x-ray of the ankle in the neutral position were recruited. The radiographs which revealed no bony injury were digitized and statistically processed. A mathematical function for each separate fibula was obtained through the processing of the digitized x-rays. When all the functions were applied to one graph, common traits of all fibulas were noted. The mean value of all functions was obtained and it corresponds to the polynomial function of degree 6. Mathematical approximation of the curvature is a simple and reliable method that can be applied to other ellipsoid human bone structures besides the ankle, thus being a valuable method in anthropometric, radiological and virtual geometric calculations.

Cortical bone drilling and thermal osteonecrosis.

BACKGROUND: Bone drilling is a common step in operative fracture treatment and reconstructive surgery. During drilling elevated bone temperature is generated. Temperatures above 47°C cause thermal osteonecrosis which contributes to screw loosening and subsequently implant failures and refractures. METHODS: The current literature on bone drilling and thermal osteonecrosis is reviewed. The methodologies involved in the experimental and clinical studies are described and compared. FINDINGS: Areas which require further investigation are highlighted and the potential use of more precise experimental setup and future technologies are addressed. INTERPRETATION: Important drill and drilling parameters that could cause increase in bone temperature and hence thermal osteonecrosis are reviewed and discussed: drilling speed, drill feed rate, cooling, drill diameter, drill point angle, drill material and wearing, drilling depth, pre-drilling, drill geometry and bone cortical thickness. Experimental methods of temperature measurement during bone drilling are defined and thermal osteonecrosis is discussed with its pathophysiology, significance in bone surgery and methods for its minimization.

Thermal osteonecrosis and bone drilling parameters revisited.

INTRODUCTION: During the drilling of the bone, the temperature could increase above 47 degrees C and cause irreversible osteonecrosis. The result is weakened contact of implants with bone and possible loss of rigid fixation. The aim of this study was to find an optimal condition where the increase in bone temperature during bone drilling process would be minimal. MATERIALS AND METHODS: Influence of different drill parameters was evaluated on the increase of bone temperature. Drill diameters were 2.5, 3.2 and 4.5 mm; drill speed 188, 462, 1,140 and 1,820 rpm; feed-rate 24, 56, 84 and 196 mm/min; drill point angle 80 degrees , 100 degrees and 120 degrees and external irrigation with water of 26 degrees C. RESULTS: Combinations of drill speed and drill diameter with the use of external irrigation produced temperatures far below critical. Without external irrigation, temperature values for the same combination of parameters ranged 31.4-55.5 degrees C. Temperatures above critical were recorded using 4.5 mm drill with higher drill speeds (1,140 and 1,820 rpm). There was no statistical significance of different drill point angles on the increase or decrease of bone temperature. The higher the feed-rate the lower the increase of bone temperature. CONCLUSIONS: The external irrigation is the most important cooling factor. With all combinations of parameters used, external irrigation maintained the bone temperature below 47 degrees C. The increase in drill diameter and drill speed caused increase in bone temperature. The changes in drill point angle did not show significant influence in the increase of the bone temperature. With the increase in feed-rate, increase in bone temperature is lower.

The periosteum. Part 1: Anatomy, histology and molecular biology.

The periosteum is a thin layer of connective tissue that covers the outer surface of a bone in all places except at joints (which are protected by articular cartilage). As opposed to bone itself, it has nociceptive nerve endings, making it very sensitive to manipulation. It also provides nourishment in the form of blood supply to the bone. The periosteum is connected to the bone by strong collagenous fibres called Sharpey's fibres, which extend to the outer circumferential and interstitial lamellae of bone. The periosteum consists of an outer "fibrous layer" and inner "cambium layer". The fibrous layer contains fibroblasts while the cambium layer contains progenitor cells which develop into osteoblasts that are responsible for increasing bone width. After a bone fracture the progenitor cells develop into osteoblasts and chondroblasts which are essential to the healing process. This review discusses the anatomy, histology and molecular biology of the periosteum in detail.

The value of cholinesterase activity after Kasai operation.

Cholinesterase (ChE) is an enzyme synthesized in the liver. The aim of this study was to determine the value of ChE as an index of liver function. We measured the ChE activity as well as the values of bilirubin, alkaline phosphatase, gamma-glutamyl transpeptidase, aminotransferases and albumin before and 7 days after Kasai operation in 25 infants with biliary atresia. The increased activity of ChE in plasma after Kasai operation was accompanied by a decrease of other measured values ( P<0.0001), except for albumin. We can conclude that the increase of ChE activity together with the decrease of bilirubin, alkaline phosphatase and gamma-glutamyl transpeptidase show early improvement of liver function after Kasai operation. ChE activity can be used to assess liver function in terms of synthesis.