Fixing Fractures – Part Two
If used for permanent fixation pins and wires are usually chosen if very little load is going through the fracture site or they are adding to the stability of a plate or an external fixator. Typical uses for wires or pins are to fix finger fractures, hand fractures, shoulder fractures and wrists. K-wires are often used to assist with the fixation in fractures of the patella, elbow and ankle. A device known as an image intensifier is often used to insert the device under x-ray guidance, allowing insertion of the pin or wire through the skin without operation.
Steinmann pins, being larger and which can be threaded are mostly used for applying skeletal traction to a fracture of the long bones. They are passed through a bone and a stirrup device attached to a weight provides the traction to keep the bone in alignment until a sufficient amount of healing occurs. This technique has largely been superseded by the use of more advanced techniques of internal fixation which means that long term traction, with its many negative side effects due to the patient being kept in bed for weeks or months, is rarely required.
Screws
Using bone screws is a basic technique of modern orthopaedic and trauma management, used either on their own or as part of another implant technique. Screws can be self tapping or need tapping beforehand. The force needed to pull a screw out of the bone is affected by various factors and the main determining factor is the density of the bone into which it is inserted. The total area of contact between the bone and the threads is also important and self tapping screws are typically used. Screws are inserted clockwise either straight in or along a path already drilled and once the screw head hits the cortical bone it generates tension with screws typically inserted at a force equivalent to 80 percent of the force which would strip them.
Bone is an active and dynamic body organ and can adapt to the stresses formed by the application of the screws, allowing a gradual reduction in fixation force with time. However, the fracture is usually healed before the fixation is likely to loosen. The two main kinds of screws available are cancellous and cortical bone screws, the denser bone of the cortex being fixed with cortical screws and the more honeycomb bone of the bone ends fixed with cancellous screws. The surface areas of contact between thread and bone are greater in cancellous screws, allowing cancellous screws to achieve purchase in less dense bone.
Pre-drilling or tapping is not generally needed in cancellous bone due to its porosity and ease of insertion. Lack of tapping is often better as the insertion of the screw compresses the bone and may increase the local density of the bone, making the screw purchase more secure. Positional screws are used to attach an implant device such as a plate to the bone by compressing between the bone and the plate. Typical insertion involves drilling a pilot hole with a matching bit for the screw size and an appropriate thread tap is used unless self tapping screws are to be inserted.
The lag technique uses small screws called lag screws to fix and compress across the line of a fracture, applying compression forces to maintain stability and alignment of long bones or reduction of fractures inside joints. The highest level of stability and compression is delivered by applying the screw directly across the fracture site. The rotation and bending forces which occur during normal post operative rehabilitation require additional stabilisation than lag screws, mostly using external fixators or plates.
Cannulated screws are another type of fixation, inserted over a guide wire which has already been inserted under x-ray control, allowing the initial wire fixation to be precisely completed by the final fixation. They can be used in a percutaneous way, without open operation, such as with hip fracture pinning. Cannulated screws can also be used in operations with limited open technique to minimise the size of the operation and the consequent soft tissue damage. Modern designs both drill and tap themselves on insertion and these hollow design screws are much more expensive than non-cannulated versions.
Related posts:
- Physiotherapy Management of Respiratory Conditions A large proportion of the workload of an acute hospital is the management and treatment of respiratory diseases, especially in the winter when people start catching colds and flu. Examples of the diagnoses which present are bronchitis, bronchiectasis, cystic fibrosis, asthma, hyperventilation and chronic obstructive pulmonary disease. Physiotherapists receive comprehensive respiratory training in their undergraduate and early postgraduate years so they can assess and treat a wide spectrum of presenting conditions. Respiratory assessment skills need careful teaching and regular practice under supervision, often made more difficult by the acutely sick patient status, and the physio has an important role in managing these sick patients....
- Beginning Running The weather in the northern hemisphere is beginning to warm up and spring turns people's minds to thoughts of fitness and sport. They look out their running shoes from the back of the wardrobe and get out on the road. After all, it's easy to do, it doesn't cost anything and you can't go wrong, can you? However, spring is just the time when all of us, having got lazy and overweight over the winter, overdo things and suffer injuries. Physiotherapists all over the country brace themselves for the surge in strains and sprains which occur at this time of year as our unprepared bodies are put through stresses which are too much for them. The commonest injuries tend to be foot pains, back pain and knee pain....
- Physiotherapy for Spinal Cord Injury High velocity accidents and sporting incidents carry a risk of causing a spinal cord injury (SCI), a serious but uncommon condition which can also be caused by ischaemia, infections or tumours. Younger people are the biggest group likely to suffer this injury due to their risky pursuits but it can occur in someone of any age, road accidents accounting for the greatest proportion. Due to the complex nature of the condition a multi-disciplinary approach is essential, involving several health care professionals, to facilitate the highest degree of independence in the patient. Paraplegia and quadriplegia are the terms used for the resulting conditions....
- Spinal Cord Injuries and Physiotherapy Spinal cord injuries (SCI) are one of the most serious consequences of high speed accidents or sporting activities, a rare but devastating injury which can also occur after infections, tumours or ischaemic damage. The largest risk group are younger people due to their propensity to perform risky activities but a person of any age can suffer from SCI. Car and motorcycle accidents account for the highest proportion of injuries and due to the complicated picture after this injury a multi-disciplinary team of professionals is vital to ensure the patient reaches the highest level of independence for their particular condition. The terms quadriplegia and paraplegia are used to describe the resulting disability....
- The Neck ” Part Two Irritability of inflamed or injured facet joints is high in terms of easily and quickly flaring up into pain when subject to unusual stresses, but then later can react badly even to normal stresses. The typical symptoms are local tenderness and aching throughout the neck, across the shoulder blades, over the neck/shoulder area and upper arms. All this pain can cause the muscles to go into spasm which compounds the problem by facet joint compression with consequent enhancement of the pain and joint forces. Some patients have severe neck muscle spasm which presents as tight, hard muscles....
Written by Robert Bonello on September 2nd, 2009 with
no comments.
Read more articles on Back Pain.
- [+] Digg: Feature this article
- [+] Del.icio.us: Bookmark this article
- [+] Furl: Bookmark this article