Characteristics of anterior inferior calcaneal cortex.

BACKGROUND: Minimal invasive surgery of calcaneal fracture provided satisfactory outcomes. In tongue type calcaneal fracture, percutaneous screw usually purchases in anterior inferior calcaneal cortex. However, there was no detail about the cortex of anterior inferior calcaneus so the surface anatomy and cortical thickness of this area were studied. METHODS: 88 calcaneus from embalmed cadavers were enrolled. Anterior part of the inferior cortex was identified. Surface anatomy was examined. Length, anterior and posterior widths were measured. Anterior inferior calcaneal cortex was divided into anterior, middle and posterior segments. The cortical thickness at middle, medial most and lateral most of 3 segments were measured. RESULTS: Anterior inferior calcaneal cortex was a long trapezoidal shape with well-defined borders as a dense and thick cortical bone, convex relief from medial and lateral walls. Mean(SD) length was 33.40(3.46) millimeters (mm). Median(min,max) of anterior and posterior width were 10.50(8.21,19.26) mm and 14.00(10.05,20.42) mm, respectively. Mean(SD) of middle cortical thickness of anterior and middle segment were 3.12(0.76) and 3.72(0.74). Median(min,max) middle cortical thickness of posterior segment was 3.13(1.62,6.51) mm. Whereas, of the medial most were 1.31(0.78,3.11), 1.31(0.90,2.57) and 1.26(0.85,2.61) mm and of the lateral most were 1.17(0.67,2.64), 1.38(0.80,2.55) and 1.31(0.84,2.61) mm, respectively. Inter-intraobserver reliabilities of the measurements were >0.79. The statistical analysis showed the middle cortex is significantly the thickest (P<0.001) and posterior width is significant wider than the anterior (P<0.001). CONCLUSIONS: Anterior inferior calcaneal cortex has special characteristics in term of surface anatomy, width and thickness. For the percutaneous screw insertion from posterosuperior to anterior inferior calcaneus in tongue type calcaneal fracture, we recommend that screw should purchase in middle cortex due to maximal cortical thickness as well as its cortical width could accept 6.5 or 7.0mm screw without screw extrusion.

Prevalence of fractures among Thais with thalassaemia syndromes.

INTRODUCTION: The association of fractures with thalassaemia syndromes is well established. The aim of this study was to determine the prevalence and risk factors for fracture in Thai people with thalassaemia syndromes. METHODS: A retrospective study and a patient interview were conducted in 201 Thai thalassaemia patients who attended the Division of Haematology, Department of Medicine Siriraj Hospital, Thailand. The patient interview questionnaire included sections on demographics, medical, orthopaedic and surgical history, usage of tobacco and alcohol, as well as questions that pertained to fracture. The risk factors for fracture were determined by odds ratio. RESULTS: The prevalence of fracture in Thai people with thalassaemia syndromes was 35.3 percent. Fracture occurred more often in beta thalassaemia patients (44.1 percent) than in alpha thalassaemia patients (16.9 percent). Upper extremity was the most common site of fracture, while falls and motor vehicle accidents were the most common causes of fracture, and cast/splint was the most common choice of treatment. 28 percent of the patients sustained multiple fractures. Among alpha thalassaemia patients, adults sustained fractures more frequently than children and adolescents. In contrast, beta thalassaemia children had a greater rate of fracture than the adults and adolescents. The risk factors for fracture in thalassaemia patients included male gender, beta thalassaemia, splenectomy, transfusion and a low body mass index. CONCLUSION: A high prevalence of fracture is observed among Thais with thalassaemia. The aetiology was found to be multifactorial.

Palmar pressure distribution during push-up exercise.

INTRODUCTION: Doing repetitive push-ups is among the most common exercise for the upper body and shoulder stabiliser muscle strength training. However, adverse effects such as neck pain, back pain, palmar pain and wrist pain have been reported. To date, to our knowledge, palmar pressure when performing push-ups has not been previously reported. We hypothesised that various hand positions during push-ups may provide different palmar pressures. METHODS: Bilateral palmar pressures were recorded in ten individual volunteers. All the subjects were set up for doing push-ups in five positions of the hand. Peak palmar pressure was recorded by Emed pressure platform system (Novel GmBH, Munich, Germany). The palm was divided into the following five anatomic regions, viz. thenar, lunate, hypothenar, metacarpals and fingers. Statistical comparison between the five positions of the hand was analysed using the analysis of variance test. RESULTS: A distribution of the mean peak pressure of the lunate and hypothenar areas were relatively higher than the other areas in both standby and full-elbow flexion positions. At the palmar position 30 cm wider than the shoulder width, the palmar pressure revealed significantly higher peak pressure in the lunate area in the standby and fully-flexed elbow positions (p-value is less than 0.05). At the palmar position 10 cm narrower than the shoulder width, palmar pressure showed significantly higher peak pressure in the hypothenar area only in the fully-flexed elbow position. CONCLUSION: The information regarding palmar pressures while performing push-ups in different hand positions may be used as a guideline for exercise modification, especially in injured athletes.

C-reactive protein, interleukin-6, and tumor necrosis factor-alpha levels in overweight and healthy adults.

This study aimed to 1) compare levels of high sensitivity c-reactive protein (hs-CRP), interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-alpha) between overweight Thais and apparently healthy controls, and 2) investigate the association between serum hs-CRP, IL-6, and TNF-alpha levels and other biochemical parameters. A total of 180 health-conscious adults aged 25-60 years, who resided in Bangkok, participated in this study. No significant difference was found in age and sex between the overweight subjects and controls. Serum levels of hs-CRP, IL-6, TNF-alpha, glucose, lipid profile, body mass index (BMI), waist circumference (WC), hip circumference (HC) and waist hip ratio (WHR) were determined in these volunteers. The mean levels of white blood cells (WBC), uric acid, total cholesterol (TC), triglyceride (TG), and hs-CRP were significantly higher in the overweight subjects than those in the controls, whereas high density lipoprotein-cholesterol (HDL-C) values were significantly higher in the controls than the overweight subjects (p < 0.05). Hs-CRP levels were significantly positively correlated with levels of TG, BMI, WC, HC and WHR. HDL-C levels were significantly negative correlated with hs-CRP levels. In conclusion, the prevalence of elevated serum hs-CRP levels was higher in overweight subjects than controls. However, more data in larger and other population groups are needed to confirm this study.

Stability of subchondral bone defect reconstruction at distal femur: comparison between polymethylmethacrylate alone and steinmann pin reinforcement of polymethylmethacrylate.

Polymethylmethacrylate (PMMA) is often used to fill the large subchondral defects following intralesional curettage of a giant cell tumor of the bone. Many authors have reported the use of Steinmann pins to reinforce the bone cement. However, whether this is of real benefit in improving the stability of the defect is controversial. Thirteen matched pairs of cadaveric distal femurs were obtained and tested in uni-axial compression to determine the strength of this reconstruction. The strength of normal distal femurs was compared with the strength of defective femurs using 5 matched pairs of cadaveric distal femurs. A significant difference between the two groups was demonstrated in the failure load, stiffness, yield point and total energy absorbed to failure (p < 0.05). The second part consisted of eight matched pairs of specimens filled with PMMA alone versus PMMA with Steinmann pin reinforcement. There was no significant difference in failure load, stiffness, yield point and total energy absorbed to failure (p > 0.05). The addition of Steinmann pins did not significantly improve the strength of the subchondral defect reconstruction in uni-axial compression compared with PMMA reconstruction alone.

The clavicular fracture: a biomechanical study of the mechanism of clavicular fracture and modes of the fracture.

A clavicle is an S-shaped long bone whose biomechanical behavior is unlike that of a straight tubular long bone. When a clavicle is under a compression load along the axis, the force produces a middle one-third clavicular fracture. The present study is a biomechanical study to confirm the clinical observations of the mechanism of the fracture and to discover the tension site and compression site of the fracture, using 12 fresh cadaveric clavicles, a universal testing machine and two special grips. One grip was constructed with a contour like a sternoclavicular articulation. The grip was mounted at the medial end of the clavicle. Another grip was constructed with a contour like an acromioclavicular articulation. The grip was mounted at the lateral end of the clavicle. A load was applied to the lateral clavicle like a force transmitting from the weight of the shoulder girdle. A load was also applied to the medial clavicle like a force from the sternocleidomastoid muscle. A compression load was applied along the axis of the testing clavicle through the upper grips by using a universal testing machine. The result found that the average load of the clavicular fracture was 1526.19 N. The fracture occurred at the middle one-third of the clavicle in the region of the curve of the lateral clavicle changing to the curve of the medial clavicle. While primatic cross section of the clavicle at the fracture site determined a tension and a compression site of the fracture, the fracture took the superoanterior aspect of the clavicle as a tension site and posteroinferior aspect as a compression site. The fracture had a ratio of length of the lateral fragment to the total length of the clavicle of 0.49. This study confirmed that a compression load along the axis of the clavicle produces a middle one-third clavicular fracture as in clinical observation and the fracture took the superoanterior aspect of the clavicle as a tension site.

Reconstruction of the pelvic brim and its role in the reduction accuracy of displaced T-shaped acetabular fracture.

Open reduction of the displaced T-shaped acetabular fracture has a problem of accuracy of the fracture reduction. This study was carried out to demonstrate that the reconstruction of the pelvic brim by approaching the pubo-acetabular fragment plays a role in the accuracy of the reduction of displaced T-shaped acetabular fractures. From 1975 to 1990, a retrospective study was carried out of 22 patients who sustained a displaced T-shaped acetabular fracture. The patients were operated on by open reduction and internal fixation of the ischio-acetabular fragment to the posterior column without restoration of the pelvic brim. Radiographs of the pelvis were reviewed. The result showed that there was displacement of the pubo-acetabular fragment including the medial wall in all cases. As the result of this study, a prospective study between 1990 and 1997 was carried out of 15 patients who sustained displaced T-shaped acetabular fractures including 3 cases with medial displacement of the femoral head. The pubo-acetabular fragment was anatomically reduced and fixed to the anterior column of the acetabulumn as the first approach to restore a disrupted pelvic brim. There, patterns of the acetabular fracture were subsequently re-evaluated especially the ischio-acetabular fragment including the position of the femoral head by using an intraoperative portable X-ray technique. The stability of the hip joint was assessed by hip flexion. The intraoperative radiograph appearances of the ischio-acetabular fragment were visually confirmed by a second surgical exposure. The results showed that the intraoperative radiographs gave spontaneous reduction of the ischio-acetabular fragment in all patients except one. There was a reduction of the displaced femoral head into the hip socket in the three patients. The hip joints were stable in all patients. The second surgical exposure showed that there was good spontaneous reduction of the ischio-acetabular fragment to the posterior column by ligamentotaxis in 14 patients. Therefore, it is not necessary to address the ischio-acetabular fragment. In the exceptional case, the ischio-acetabular fragment was displaced as a free bone which could not be reduced by ligamentotaxis. However, reduction and internal fixation of the ischio-acetabular fragment to the posterior column for complete re-application of the hip joint onto the pelvic ring of this case was facilitated. Postoperative 2 year and 5 year follow-up showed that the fracture had healed without heterotrophic ossification or premature osteoarthrosis of the hip joint. The exceptional case had a broken plate at the anterior column of the acetabulum. Hip function was evaluated clinically using Merle D' Aubigne's hip score. All patients had a "very good score". The study showed that reconstruction of the pelvic brim by anatomical reduction and fixation of the pubo-acetabular fragment to the anterior column plays an important role in the accuracy of fracture reduction of a displaced T-shaped acetabular fracture.

Determination of the role of the cancellous bone in generation of screw holding power at metaphysis.

OBJECTIVE: To determine whether cancellous bone at metaphysis plays a significant role in generation of holding power of the cancellous screw. DESIGN: Maximal holding power of the cancellous screw at distal metaphysis of the femur with and without cancellous bone inside was determined by applying a load to push out the screw. BACKGROUND: Generation of screw holding power from the cancellous bone can arise by a mechanism of compression of cancellous bone between screw threads when a screw is inserted by non-tapping technique. Metaphysis has intermediate amount of cancellous and cortical bone when compared with diaphysis and intercondyle of a long bone. METHODS: Eight pairs of fresh cadaveric femurs were used. One femur of a pair was removed of cancellous bone at the distal metaphysis; cancellous bone of the other was preserved. A full thread cancellous screw was inserted into the distal femoral metaphysis. An axial load was applied at the screw tip to push out the screw by using a universal testing machine. RESULT: Mean push-out force of the screw at distal femoral metaphysis without cancellous bone inside was 1824.76 N and stiffness was 746.76 N/mm. Mean push-out force of the screw at distal femoral metaphysis with preservation of cancellous bone was 2015.86 N and stiffiness was 853. 09 N/mm. The statistical analysis of both groups showed no significant differences. CONCLUSIONS: This study confirmed that cancellous bone at metaphysis plays no significant role in generation of holding power of the cancellous screw. RELEVANCE: Because metaphyseal cancellous bone plays no role in generation of screw holding power, only a well-inserted cancellous screw into bone cortices can achieve good screw holding power at metaphysis of a long bone.

Immediate stabilization of unstable pelvic fractures versus delayed stabilization.

To compare the immediate and long term outcome of immediate stabilization of the unstable pelvic fractures to delayed stabilization with simple external fixation, the study was carried out as a paralell trial with 2 year follow-up. There were 112 patients with 69 males and 43 females who had unstable pelvic fractures. They were allocated randomly into 2 groups. In group 1, 40 patients, conventional management was performed while in group 2, 72 patients, reduction and anterior stabilization of pelvic fractures with a simple external fixator were carried out immediately just after the unstable fractures were detected. Blood transfusion, post operative pain, need of reconstructive surgery of the pelvic fractures and late deformities were less in the group 2. Immediate anterior reduction and stabilization of the unstable pelvic fractures gave encouraging results.

Anterior stabilization in the pubic symphysis separation: a mechanical testing.

Four types of commonly used instruments, 1) external fixation, 2) tension wiring, 3) tension band wiring, and 4) single superior plating, for anterior stabilization of the diastasis pubic symphysis were tested for their mechanical properties under single load to failure in cadaveric pelvis by a universal testing machine. Three directions of loading, transverse tension, vertical tension and saggital compression, were used to test each type of instrumentation. Five specimens of each fixation were used for each direction of testing. The strongest instrumentation was single superior plating. Early mobilization can be advocated in the patient after fixation with this instrument. External fixation could resist transverse and saggital compression load at an acceptable level but not the vertical load. Tension band wiring could better resist vertical load than the other directions. Tensions wiring was the weakest instrumentation and early ambulation should be avoided.

The role of the anterior column of the acetabulum on pelvic stability: a biomechanical study.

A study on the effects of the anterior and the posterior column of the acetabulum on pelvic ring stability was carried out by applying a lateral compression force to specially prepared specimens. In group 1, the continuity of the right anterior column was disrupted by removing the acetabulopubic part of the anterior column; the posterior column was left intact in order to measure the strength of the posterior column. In group 2 the continuity of the right posterior column was disrupted by removing the ischioacetabular part of the posterior column leaving the anterior column intact in order to measure strength of the anterior column. The posterior column provided an average maximum strength of 759.43 +/- 229.51 N and the stiffness was 113.19 +/- 22.40 N/nm. The anterior column provided an average maximum strength of 2015.40 +/- 352.31 N and the stiffness was 301.57 +/- 98.67 N/mm. Thus the anterior column provides 2.75 times greater strength to the pelvic ring than the posterior column (P < 0.05). This finding may be important in open reduction and internal fixation of double column acetabular fractures.

The reconstruction twisted wire-screws for internal fixation of two- and three-part fractures of the proximal humerus.

Using the implants for internal fixation of the proximal humeral fractures has several problems which lead to complications and poor results of the fracture treatment. Because there is no suitable implant for internal fixation of the fracture. Therefore, the reconstruction twisted wire was developed in 1990 to improve the results of the fracture treatment. Between 1990 and 1994, the reconstruction twisted wire was used in 31 patients whose ages ranged from 18 to 90 years. Sixteen patients had displaced two-part surgical neck fractures. Fifteen patients had displaced three-part fractures. Postoperative follow-up ranged from two and a half years to five years and one month. All fractures healed. No avascular necrosis of the humeral head was observed at the follow-up. There was temporary subluxation of the shoulder joint in three patients and loosening of the screws in two patients with marked osteoporosis. One had a rupture of wire between the greater tuberosity and the shaft and loosening of the screw at the greater tuberosity and united with 10 degrees varus deformity. According to the functional scale proposed by Hawkins, 28 of the 31 patients achieved a "good" result and 3 patients had a "fair" result.

An aiming device for pin fixation at the iliac crest for external fixation in unstable pelvic fracture.

To improve the accuracy of pinning at the iliac crest during external fixation of the pelvic fracture, an aiming device has been designed. The device consists of 3 parts: a sleeve which accommodates a 5.0 Shanz pin, a handle and guide points. The guide points were designed to grasp the iliac crest to allow proper pin fixation. The device has undergone trials to fix Shanz pins on the iliac crests of 10 cadavers by 10 recently graduated doctors. All pins were fixed in proper position and passed into the bone between the two tables of the iliac crest without penetrating the tables. The device has so far been used in 50 patients who had unstable pelvic fractures. All pins were in the proper positions and there had been no loosening at the time the pins were removed. The use of this aiming device for pinning the iliac crest for external fixation of pelvic fracture has given encouraging results.

The talar body prosthesis.

Arthrodesis or talectomy for the treatment of avascular necrosis of the talus or a severe crush fracture of the body of the talus often produces a disability of the ankle and the foot. Therefore, a prosthesis designed to replace the body of the talus and to preserve the function of the ankle and the foot was developed. The prosthesis has a superior curved surface, and the medial and lateral surfaces are inclined for articulation with the tibia and the fibula. The inferior aspect has a concave curved surface at the posterior aspect of the prosthesis to serve as the posterior facet for articulation with the posterior facet of the calcaneus, and there is a convex curved surface at the anterior aspect of the prosthesis for articulation with the middle facet of the calcaneus. The neck and the head of the talus are preserved to allow insertion of the prosthetic stem into bone. A transmedial malleolar approach is used for insertion of the prosthesis. We inserted the talar body prosthesis in sixteen patients - twelve who had avascular necrosis of the talar body and four who had a severe crush fracture of the talar body - between 1974 and 1990. Three patients who were evaluated five years postoperatively had a satisfactory result, and one patient had failure of the prosthesis at eight months because the diameter of the inferior concave curved surface was too small in the region of the posterior facet and had caused erosion of the posterior facet of the calcaneus. All three patients who were evaluated six to ten years postoperatively had a satisfactory result. All except one of the nine patients who were evaluated eleven to fifteen years postoperatively had a satisfactory result; the exceptional patient had an unsatisfactory result because the prosthetic stem had sunk into the talar neck. This patient had a revision thirteen years after the index operation. We believe that the talar body prosthesis can be used to replace the body of a talus with avascular necrosis or a severe crush fracture, thus maintaining the function of the ankle and the foot for a prolonged period.

Biomechanical aspects of plating osteosynthesis of transverse clavicular fracture with and without inferior cortical defect.

OBJECTIVE: To find out whether superior or anterior plating osteosynthesis of clavicular fractures with and without inferior cortical defect provides more stability. DESIGN: The bearing of maximal bending moment of the osteosyntheses was determined by applying a load from a universal testing machine. BACKGROUND: A plate is recommended for internal fixation of the clavicular fracture. Stability of the osteosynthesis depends on placing of the plate at anterior or superior aspect of the clavicle. Whereas, the pattern of the fracture also influences stability. METHODS: Pairs of fresh cadaveric clavicles were used. The fractures were created at middle clavicle. Both superior and anterior plating fixation of both patterns of the fractures were performed. A compression load was applied at lateral end of the clavicle and maximal bending moment was calculated. RESULTS: For fractures without inferior cortical defect, the superior plating could withstand 12.05 (SD, 1.74) Nm and 8.69 (SD, 1.56) Nm for the anterior plating. For the fractures with inferior cortical defect, the superior plating could withstand 7.87 (SD, 2.58) Nm, but 10.26 (SD, 2.19) Nm for the anterior plating. CONCLUSIONS: The superior plating of the fracture without inferior cortical defect provides more stability against the bending moment than the anterior plating (P = 0.008). Whereas, the anterior plating of the fracture with inferior cortical defect provides more stability (P = 0.025). RELEVANCE: When plating a clavicular fracture without inferior cortical defect is performed, the plate should be placed at superior aspect of the clavicle for achieving more stability of the osteosynthesis against the bending moment. On the other hand, when the fracture has an inferior cortical defect, the plate should be placed at the anterior aspect of the clavicle.