Changes of Fixation Strength by Rod - Contouring of Compact Cotrel - Dubousset Instrumentation / 대한정형외과학회잡지

One of various decompression methods in treatment of spinal stenosis is the indirect instrumental decompression. Theoretically, the distraction of the disc space can widen the intervertebral foramen of the stenotic segment and even increase the canal diameter by distracting the posterior annulus as well as reduce the extent of decompressive laminectomy site. The indirect instrumental decompression, however, was not guaranteed to maintain the restored discal height because of the loss of fixation strength between rod and screw, viscoelasticity of vertebra itself, bone density, type of screw and rod, and operative technique. As well the magnitude of the stresses on the instrumentation particularly at the rod-screw interface may depend on rod-contouring in order to make mormal sagittal curvature of the lumbar spines. Therefore, the aim of this experimental study was to evaluate the effect of different rod-contour on the axial sliding strength in Compact Cotrel-Dubousset (CCD) instrumentation. Axial sliding strength was tested by Universal Test Machine (Instron). Test was performed for 3 groups of different rodcontouring on the biomechanical axial strength: straight rod (no contour), 10 and 20 contouring rod. The length of contact surface between rod and screw was measured with Fuji pressure sensitive film. The study was performed using 6.5 mm open body screws and 7 mm rods of CCD instrumentation. Axial sliding strength of straight rod was 2518.6N, 1871.8N in 10 and 1528.8N in 20 contouring rod. The length of contact surface between rod and screw significantly decreased according to degree of rod contouring; 9.88mm in straight rod, 9.08mm in 10 and 8.57mm in 20 contouring rod. There was a statistically significant linear correlation (R=0.96) between failure load and length of contact surface. Therefore, this study has shown that excessive contour of the rod in order to make normal sagittal curvature of the lumbar spine using CCD instrumentation cannot provide sufficient axial sliding strength. That may be a cause of loss of restored disc space height after surgery.

The Surgical Treatment of Osteoporotic Vertebral Collapse Caused by Minor Trauma / 대한정형외과학회잡지

With an aging population, osteoporotic vertebral collapse is an increasingly common condition. This compression fractures has been considered a benign entity, quite responsive to conservative treatment. In a rare patients, however, a major neurologic complication and painful kyphosis despite conservative treatment can develop. Therefore, the purpose of this present study is to analyze the surgical results of 14 patients with severe back pain, an increasing kyphosis and neurologic deficits caused hy osteoporotic vertebral collapse following minor trauma, who were treated surgically. Presenting signs and symptoms included severe back pain with progression of kyphosis in 6 patients and increasing neural deficit in 8 patients. Of 14 patients, eight patients had an intravertebral cleft sign (vacuum sign). Indications for surgery included increasing kyphotic deformity, intractable pain, or increasing neurologic deficit. There was no correlation between intravertebral cleft sign and neurologic deficit. However, patients who had intravertebral cleft sign had not well respond to conservative treatment. As treatments, combined anterior and posterior fusion in 8, anterior fusion in 4, posterior instrumentation, and wide decompressive laminectomry in one patient, respectively, were carried out. The final correction of the deformity averaged 0.3 degrees. Therefore. correction of kyphosis was not favorably maintained because of variable surgical methods, and sinking of graft bone or instrumentation into the osteoporotic vertebral bodies. However, pain was reduced significantly in all patients. In addition neurological symptoms improved in 7 patients. One patient underwent reoperation with nnterior inierbody tusion together with anterior instrument because of an increasing kyphosis, neurologic. iymptoms and scvcre hack pain following wide decompressive laminectomy. There was no complication relatecl to instruments. The authors strongly helieved that surgical intervention has highly satisfactory results in patients who have intravertehral cleft sign with persistent back pain despite conservative treatment, and proressive or persistent neurologic deficits following osteoporotic vertebral collapse.

Comparison between Screw Fixation and Tension Band Wiring for the Treatment of Medial Malleolar Fractures / 대한정형외과학회잡지

In the treatment of malleolar fracture, anatomical reduction and rigid internal fixation are essential to prevent the complications such as infection, malunion or nonunion, traumatic arthritis, skin necrosis and joint contracture. But it is often difficult to obtain rigid fixation for medial malleolar fracture because of its comminution or thin cortex with osteoporosis. Generally, two operative methods are available for medial malleolar fracture, which are malleolar lag screw fixation and tension band wiring. The purpose of this paper is to analyze which operative method is better for anatomical reduction and rigid fixation and has less postoperative complications for medial malleolar fractures. From March 1992 through March 1995, 88 patients had undergone surgical intervention for medial malleolar fractures. The patients were divided into 2 groups according to operative method for medial malleolar fracture. For one group, malleolar lag screw together with or without a K-wire was used in 48 patients, and for the other group, tension band wiring was used in 40 patients. The average follow-up periods were 14 months in screw fixation group and 13 months in tension band wiring group. The average union time were 15.4 weeks (8-17 weeks) in screw fixation group and 12.2 weeks (6-15 weeks) in tension band wiring group. 27 cases (56%) showed excellent result in screw fixation group and 30 cases (75%) in tension band wiring group. In the patient over 50 years old, 2 (15%) in 13 cases showed excellent result of screw fixation group, while 5 (45%) in 11 cases of tension band wiring group. We concluded that tension band wiring is a better method for medial malleolar fracture to obtain early union and to prevent postoperative complications, especially in the elderly patient.