Mustafa K. Hameed, Arkan Bader Hassen, Firas Tariq Ismaeel. Dept. of surgery, College of medicine, Tikrit University.

Transcription

1 The effect of head injury on callus formation in fractures of tubular bones. Mustafa K. Hameed, Arkan Bader Hassen, Firas Tariq Ismaeel. Dept. of surgery, College of medicine, Tikrit University. Abstract A study conducted in a 2 years period ( ) in Tikrit Teaching Hospital aiming to find the effect of head injury on radiological evidence of callus formation. The study included 53 patients with head injury and fractures, compared to 30 control patients with fractures without head injury. The study depends on the ratio between the callus diameter to that of the bone, to quantify callus mass. We focused on the femoral, tibial, and humeral fractures for the ease of measuring callus formation. The radiological evidence of callus started in head injured group started earlier, and became more florid than the control group. With radiological resemblance to heterotopic ossification, rather than a normally looking callus. The study reveals that the patients with severe head injuries have abundant callus formed, compared to the lesser degree of head injury. And that patients with fractures have more callus formation; when associated with head injury. Key words: callus, fracture, head injury, heterotopic ossification. Introduction Orthopaedic aphorism teaches that fractures of long bones, when associated with head injuries, frequently heal with excessive callus and at a faster rate than normal. The evidence, however, is flimsy and based on small series of patients treated in different ways and never with an adequate control series (1). The aphorism remains unsubstantiated and, indeed, Garland failed to confirm increased callus formation or more rapid healing of fractures of the tibia and femur in patients with head injuries. These series, however, had no controls, nor did they quantify the callus. Many theories have been considered but none was confirmed. (2, 3) The suggestion, based on limited histology, that the excessive callus in braininjured patients is in fact a form of ectopic ossification is useful. The evidence that injury to the brain and spinal cord predisposes to the formation of bone in the soft tissues, supports that on fracture healing and is far more convincing. Although the healing of fractures and the formation of bone in ectopic sites may differ clinically, both must depend on the activity of osteogenic cells. (4) Both skeletal and extraskeletal osteogenesis depend on the presence of bone-forming cells, the osteoblasts. Normal fracture repair probably depends on the presence of osteoblasts already present at the fracture site. Heterotopic ossification, and probably excessive callus, will result from induction of additional mesenchymal cells into the osteogenic pathway. Of the cells potentially capable of forming bone some will do so without an inducing agent; such cells within the bone marrow stromal system have been termed (determinedosteoprogenitor cells), whilst others require an inducer (inducible osteo-progenitor cells). The former cells are not usually migratory, but the latter can be found at distant as well as local sites and are presumed to migrate and circulate through the body. If it is right, that there is a population of potentially inducible osteo-progenitor cells, it is important to know their inducers. (4, 5) Most recent work has been concerned with identifying local inducers already present in bone. In tissue culture such osteoinductive factors lead to the production of cartilage in vitro, an important step in osteogenesis; and in vivo a bone morphogenic protein (BMP), whose exact structure is unknown, can be demonstrated by the implantation of acid-demineralised bone matrix into responsive sites.(6) If such an inducer (or inducers) exists it may act locally or through the bloodstream to be effective at distant sites and produce both excessive callus and soft tissue ossification. (4) Early biochemical measurements on the plasma and the fracture haematoma site Tikrit Medical Journal 2008; 14(1):

2 (at operation and derived from local drainage samples) in brain-injured adults and children and in adults without brain injury were inconclusive. (7) Recent series suggested a major role for interleukin-6 (IL-6); and its soluble receptors (sil-6r) in the altered callus formation in patients with head injury. (8) Nuclear magnetic imaging technique was used in an animal experimental study to show the increase in the ph media of the fracture area as callus deposited. Since patients with head injuries may develop a respiratory alkalosis due to hyperventilation, it has been suggested that this contributes to the formation of callus and also to its mineralization. (9) Head injury can be associated with marked endocrine changes but there is no evidence to relate them to abnormal osteogenesis. Interestingly fracture healing in the somatomedin-deficient Snell dwarf mouse is normal. Although it should be possible to detect and measure circulating bone inducers with the in vitro systems available, no observations have yet been recorded. (4) The Aim of the study is to recognize the effect of head injury on the time needed for callus formation, to identify the relation between head injury and the radiological mass of callus, and to identify the relation between the severity of head injury and the radiological mass of callus. Patients and Methods During a two years period between October 2005 and October 2007, 366 patients with significant head injury were admitted to Tikrit Teaching Hospital, 53 of these patients had head injury and fractures of the limbs. The severity of head injury was rated in the first 24 hours according to Glascow coma scale, in which less than 7 was considered as severe, 7-14 as moderate, and 15 as mild. There were 47 males and six females with an age range selected purposefully from years so that the healing process is to some extent similar. Blast injuries were the commonest cause of injury. 32 patients had multiple fractures. The fractures were treated according to its displacement; site; and associated injury either conservatively or surgically. The head injuries were also treated conservatively by observation but 10 patients had referred to a neurosurgical center (Mousil city) for further management. The patients were followed by serial radiographs to assess the healing process. The factors assessed in the study were the fracture healing, the time to clinical and radiological union, and the mass of the callus. The fracture healing response was calculated by the simplest possible method which allowed reproducibility. The healing mass is frequently fusiform, though often irregular and eccentric, resembling no mathematically defined shape, however the largest diameter of even the most amorphous tube like structure is substantially the most important determinant of volume in the absence of massive variation in length. A numerical value for fracture healing response was therefore calculated as follows: (Fracture healing response = A/B) Were A is the largest diameter of the healing mass (callus) measured from serial radiograph, and B is the bone diameter at or adjacent to the fracture site on the same radiograph. (10) The numerical value obtained was used to compare the patients who had head injury and fractures at the tibia, femur, and humerus. With group of 30 control matches for age and sex who had similar fracture pattern but no head injury. The results were analyzed statistically to find their significance according to P value. Results The distribution of the cases according to the site of fracture is shown in table (1) and the distribution of head injury group according to the severity of head injury is shown in table (2). The present study reveals that callus formation start earlier in the patients with head injury in comparism to those without head injury. Table (3) show that 18.8% of patients, with fracture femur and head injury, had radiological evidence of callus formation in the first 4 weeks, while none of the control group with fracture femur had callus formation in the same period. The same results was in the patients with fracture tibia and patients with humeral fracture 29.4% 128 Tikrit Medical Journal 2008; 14(1):

3 and 44.4% respectively in the head injury group show radiological evidence of callus in the first 4 weeks, compared to 11.1% and 25% respectively in the control group as shown in table 4 and 5 respectively. Table 6 and fig. 1 reveals that patients with head injury had more callus mass measured radiologically according to A/B ratio. The mean of this ratio for the femur, tibia, and humerus were 1.7, 1.37, and 1.79 respectively in patients with head injury, compared to 1.52, 1.16, and 1.58 respectively in the control group. This study demonstrates an obvious increment in the mean of A/B ratio, with the increased severity of head injury, as shown in fig. 1. The more severe cases of head injury, the more florid callus formation. Discussion The present study agrees with previous finding(11), which stated that the appearance of callus radiologically is enhanced in patients with head injury, and that there is some kind of influence on ossification is exerted by the nervous system (tables 3,4,5). This result was statistically significant (P value < 0.05). But other authors prefer to describe this enhancement in the healing process as a sort of heterotopic ossification, rather than a normal callus formation.(12) The results shown were statistically significant, revealing the effect of head injury, on increasing the mass of callus formation (fig.2 & 3). Previous results agree with this finding, however, which explained this by the resemblance of the nature of myositis ossificance, and callus formed in patients with head injury, in that it tends to be mature at its periphery. In the contrary, a normal callus will be more mature in its center, rather than the periphery. (13) The increased callus mass; in patients with more severe head injury demonstrated in table fig. 1; were statistically significant. This might be due to neural factors or local biochemical factors. Other authors deny this relation to head injury, and refer this enhancement in the ossification to long term ventilation used in patients with head injury, especially severe injuries, which will lead to over oxygenation and changes in the acid base balance, forming an environment in favor of ossification and callus formation. (4, 6) The present study concludes, that patients with severe head injuries had abundant callus formation, than that in patients without head injury. References 1- Calandriello B. Callus formation in severe brain injuries. Bull Hosp ft Dis Orthop Inst 1999;25: Garland DE, Toder L. Fractures of the tibial diaphysis in adults with head injuries. Clin Orthopl980;l50:l Garland DE, Rothi B, Waters RL. Femoral fractures in head-injured adults.clinorthop 1982;166: Spencer R.F. the effect of head injury on fracture healing a quantitative assessment. J. of bone and joint surgery 1987; 69-B, (4): Solomonn L., Warwick D.J., Nayagam S., Apley's system of orthopaedics and fractures. 8th ed. Arnold. London;2001: Pape H.C. et al, Heterotopic Ossifications in Patients After Severe Blunt Trauma With and Without Head Trauma. J. of Orthopaedic Trauma. May (4): Perkins R, Skirving AP. Callus formation and the rate of healing of femoral fractures in patients with head injuries. J Bone & Joint Surg. [Br]l987;69-B: Beeton CA, Chatfield D, Brooks RA, Rushton N. circulating levels of interleukin-6 and its soluble receptor in patients with head injury and fractures. J. of bone and joint surgery, August (2). 9- Stone MH, Newman RJ, Muklierjee SK. Accelerated fracture union in association with severe head injury. J Bone Joint Surg [Br] 1987; 69-B: Sutton D. textbook of radiology and imaging, 7th edition. Churchill livingstone. London; 2003: Sevitt S. Bone repair and fracture healing in man. Edinburgh etc: Churchill Livingstone; 1998: Garland DE, Miller G. Fractures and dislocations about the hip in head-injured adults. Clin. Orthop. 1984;186: Heffner RR. Muscle pathology, 3rd ed. Churchill Livingstone. New York; 1994: Tikrit Medical Journal 2008; 14(1):

4 Table (1): the distribution of the cases according to the site of injury. Site of fracture No. No. Femur Tibia 17 9 Humerus 9 4 Others 11 7 Total Table (2): the distribution of cases with head injury according to severity. Severity Cases No. Mild 28 Moderate 18 Severe 7 Total 35 Table (3): the first time for appearance of radiological evidence of callus, for femoral fractures Total Table 4: the first time for appearance of radiological evidence of callus, for tibial fractures Total Table 5: the first time for appearance of radiological evidence of callus, for humerus fractures Total Tikrit Medical Journal 2008; 14(1):

5 Table 6: The callus mass in head injury group, compared to control group, (the mean of A/B ratio). Fracture site Mean of A/B ratio Control Femur Tibia Humerus Overall mean Mean of A/B ratio Mild Moderate Severe Overall mean Severity of head injury Fig (1): the severity of head injury and callus mass (the mean ratio of A/B) fig.2: callus mass in a patient have fractured without head injury. fig.3: callus mass in a patient have fractured with head injury. Tikrit Medical Journal 2008; 14(1):