Traumatic injuries of knee and hip

Transcription

1 Traumatic injuries of knee and hip Martin W. Korn, MD The United States secretary of transportation recently announced that highway deaths had risen from the previously announced 56,000 for 1969 to a new high of 62,000 for This represented an increase of 13 per cent in death by auto over the 1968 figure of 55,000 - or slightly more than 1,000 deaths each week. Between 1959 and 1969 we killed 515,000 and injured many times this number of people on our highways. This represents an almost incalculable loss in productivity, earnings, medical costs, and human potential. Martin W. Korn, MD, is an orthopedic surgeon, Strong Memorial and Rochester General Hospi- tal, Rochester, NY. He was educated at Cornell University. Ithaca, NY, and has teaching experience as clinical assistant professor of orthopedic surgery, University of Rochester. Dr. Korn is a member of the American Medical Association, and the American Association of Automotive Medicine: and holds fellowship in the American Academy of Orthopedic Surgeons and the American College of Surgeons. This article was adapted from his presentation at a 1970 Regional Institute on Operafing Room Nursing in Rochester. In front-end auto collisions, frontseat occupants without restraining seat belts are thrown forward, impacting the dash board, windshield, pillar or steering column. In the classic situation the seated occupant has had knees and hips flexed in the sitting position. When thrown forward his knee impacts and the force is transmitted proximally a 1 on g the femur to the flexed hip joint. This common mechanism of injury can produce singly, or in combination, a number of orthopedic problems, including posterior dislocation (Fig 1) or fracture dislocation of the hip joint Fig I 56 A0 R N Journal

2 Fig 2 (Fig 2); subcapital and intertrochanteric hip fracture; femoral shaft fracture; patellar fracture; and posterior knee dislocation. These can be open or closed injuries and may involve associated nerve and vascular compromise. The initial collision of the auto with an obstacle takes only a small frac- Fig 3 tion of a second to occur. The second collision of unrestrained occupant with the interior of the auto occupies only another fraction of a second. Yet, as we know only too well, the occupant has been transformed in an instant into an accident victim and thereby becomes our patient. Working together we do our best to keep the misfortune of an instant becoming a permanent disability. Now let's consider some of the injuries in more detail, starting at the hip and progressing distally: The thrust on the flexed hip at the time of impact can drive it posteriorally out of the acetabulum with or without a fracture of the posterior wall of the acetabulum, producing a posterior hip joint dislocation. Clinically the patient is in great pain. Any hip motion is exquisitely painful. The femur is flexed, adducted, and internally rotated, and the diagnosis can' be suspected before the confirming x-ray is obtained. It is important to promptly reduce the dislocation, since the longer the femoral head remains dislocated the greater the chance of developing avascular necrosis of the femoral head. (Fig 3). The sciatic nerve lies against the posterior surface of the flexed hip joint and is in danger of being injured by the posteriorlydriven femoral head. Fractures of the posterior wall of the acetabulum commonly occur with the dislocation and are produced by the same mechanism. When the fracture fragment is sufficiently large, it must be reduced and fixed internally with a screw to restore the stability of the joint. When the blood supply of the femoral head is sufficiently compromised May

3 by the dislocation, avascular necrosis of the femoral head occurs. Overlying articular cartilage may also die, although it is usually quite resistant since it receives most of its nutrition from the synovial fluid of the hip joint. Degenerative changes of osteoarthritis occur secondarily (Fig 41, often associated with development of may involve young people as well. Rather higher energy levels are required to fracture a young person's hip, and so in these cases there are often associated major injuries which may delay, or even prevent the timely reduction and internal fixation of the hip fracture. Bone grafting and/or corrective osteotomy can be done at a later date, if needed. Fig 4 58 AORN Journal

4 capital, transcervical, and base of neck. Because they may be associated with injury to the blood vessels supplying the femoral head, avascular necrosis of the femoral head may be associated with them. This was more common in the past when less secure internal fixation of these fractures was used. The small proximal fragment is sometimes difficult to nail securely and delayed or nonunion may also occur. Therefore, good reduction and rigid internal fixation are necessary to minimize the incidence of poor fracture union or avascular necrosis of the femoral head in femoral neck, or intracapsular fractures. The extracapsular hip fractures include the trochanteric fractures: intertrochanteric and subtrochanteric. These have a good blood supply and, Fig 6 once reduced and securely pinned, usually heal quite well. The problems here are found with the unstable trochanteric fractures for which such technics as displacement osteotomy and high angle nails are used. Let s go to the region of the knee joint. Fractures just above the widened femoral condyles and therefore called supracondylar femoral fractures (Fig 6, 71, may interfere with the quadriceps mechanism. Since the quadriceps muscle and its attachments comprise the primary mechanism providing secure knee extension, they are essential when rising to a standing position. They are considered one of the antigravity muscle systems. Fig 7 May f971 59

5 The proximal fracture fragment may penetrate the quadriceps tendon; or angulation may alter the line of quadriceps pull; adhesions may form between the fracture and the quadiceps, especially if the area has been severely traumatized as with open fractures, or if healing has been delayed and the beginning of active knee motion is thus delayed. The supra-patellar pouch of the knee joint may also be violated with resulting adhesions and restriction of knee motion. Treatment of these fractures is usually by closed traction although open reduction and internal fixation is sometimes indicated. The patella, or kneecap, is formed within the tendon of the quadriceps muscle where it passes over the front of the knee joint. Therefore, it is an integral part of the quadriceps mechanism and significant damage to it prevents adequate quadriceps function. The direct blow of the flexed knee against the auto dashboard or steering column has been a common cause of patellar fractures. With displacement of the fragments (Fig 8), continuity of the quadriceps mechanism is lost. The treatment is necessarily directed first at restoring continuity of the quadriceps mechanism and second at preserving a significant amount of the patella if that is possible. We can retain a fragment compromising 50% or more of the pa- tella. Smaller fragments are usually excised and the tendon reattached to the remaining larger fragment. The results of treatment are usually good although patello-femoral osteoarthritis may develop in later years. Fig 8 Posterior knee dislocation is a rather rare occurrence which can produce great problems. The most urgent and serious of these is severe compromise of the popliteal artery which lies immediately behind the knee joint and is tethered in this POsition by its branches and the distal take off of the anterior tibia1 artery. n 60 AORN Journal