Biomechanical effects of gamma irradiation on fresh frozen allografts in vivo.

The effect of gamma irradiation on the mechanical properties of allograft in a rabbit model was examined. Tibial allografts were tested in torsion to failure to determine maximum torque and maximum stress. Statistically significant degradation in the torsional strength of irradiated tibias vs controls was demonstrated. Femoral allografts were orthotopically implanted into experimental rabbits and secured with an intramedullary pin. Rates of incorporation and failure patterns were significantly altered by irradiation. These data suggest that sterilization of fresh-frozen allografts with 2.5 Mrad or greater severely degrades the ability of the graft to resist torsion. The rate of incorporation of fresh-frozen allografts also may be dramatically decreased as a result of irradiation.

Appropriate use of magnetic resonance imaging of the spine and extremities.

The incidence of inappropriate use of magnetic resonance imaging (MRI) by nonsurgeon physicians for evaluation of musculoskeletal disorders is high when assessed using treatment-oriented criteria in a university medical center. The charts of 71 patients who underwent 90 MRIs of the spine or extremity revealed an inappropriateness rate of 22%. The rate of inappropriateness was higher in the outpatient setting and varied little according to the anatomic region studied. The indications for surgical treatment and the benefits of diagnostic studies such as MRI for disorders of the musculoskeletal system must be thoroughly understood to justify the expense.

Effects of rapid pulsed CO2 laser beam on cortical bone in vivo.

Twenty rabbit femurs were used to study the effect of CO2 laser on cortical bone. Sixteen femurs were treated with 20 watts, 3 mm defocused beam, 2 KHZ spike pulse mode CO2 laser for 10 seconds through a circular window in the metaphysis. In four control femurs, the inner cortex was exposed without laser treatment. The animals were killed at 4 and 6 weeks and the specimens studied histologically. All laser-treated specimens showed thermal changes. Three histological zones were observed. A superficial zone of inner cortex close to the beam consisted mainly of carbonization or carbon ash during resorption. An intermediate zone consisted of bone necrosis and healing with associated areas of new bone formation. The deep zone of outer cortex had normal bone with no cellular damage. No such changes were observed in the control specimens. The CO2 laser can be used to generate a controlled zone of tissue ablation, which may make it a potentially useful tool for tumor margin cauterization.

The immunology of bone and cartilage transplantation.

Bone tissue was one of the earliest human transplanted tissues, yet little is known about its transplant biology. For many years, bone and cartilage tissues were though to be immunoprivileged tissues because of the absence of acute rejection phenomenon. Advances in the understanding of transplant immunology of vascularized tissue grafts (kidney, heart, liver, etc) have led to a renewed interest in the immunobiology of bone and cartilage allograft transplantation. Since prosthetic materials used in orthopedic reconstructive surgery have a limited lifespan, there is great interest in the transplantation of bone and cartilage tissue. The first half of the article discusses transplant terminology, basic principles of immunology, and experimental studies on the immunogenicity of bone and cartilage tissue. The second half of the article discusses how allotransplanted bone and cartilage behaves in human transplants, storage and preservation techniques, and future directions in bone and cartilage transplantation.

Roentgenographic evaluation of lumbar spine flexion-extension in asymptomatic individuals.

An experimental clinical study of angulatory and translational lumbar spine intervertebral motion was performed using flexion-extension radiographs obtained in the lateral plane. These "bending" films were obtained from 59 asymptomatic individuals undergoing routine pre-employment examination. Results indicate that there is 7 to 14 degrees of angulatory motion present in the lumbar spine but a large range of values exist so that norms of angulatory motion cannot be more precisely defined. There are 2 to 3 mm of translational motion present in the lumbar spine at each intervertebral level. Twenty percent of this study's asymptomatic subjects had 4 mm or more translational motion at the L4-5 interspace and at least 10% had 3 mm or greater motion at all levels except L5-S1. These results challenge conclusions based on earlier studies and call into question the use of lumbar flexion-extension bending films as a primary determinant of lumbar segmental stability.

Clinical and radiological evaluation of lumbosacral motion below fusion levels in idiopathic scoliosis.

The purpose of this study was to evaluate the unfused segments of the lumbar spine in patients who had Harrington instrumentation and fusion for idiopathic scoliosis. Forty-eight patients, with an average follow-up of 11 years, were evaluated. The translational motion in the unfused segments below the instrumented levels was measured, using lateral flexion and extension radiographs of the lumbar spine. This motion was compared with values obtained from an earlier study of asymptomatic nonscoliotic individuals. The amount of disc space narrowing, retrolisthesis, length and level of the fusion, and the presence of traction spurs also were recorded. The incidence of low-back pain was highest in those patients fused to L4 (62%). Individuals instrumented and fused to L3 or L4 had significantly more translational motion in the adjacent lower interspace when compared with the control group (P = 0.05 and P = 0.001, respectively). Increased translational motion correlated with the presence of low-back pain in patients fused to L4. Retrolisthesis occurred in 81% of patients instrumented to L4, in 40% of those fused to L3, and was not found in patients fused to high levels. Its presence was strongly associated with low-back pain. There was no relationship between low-back pain and traction spurs, length of the fusion mass, lumbar lordosis, or width of the disc space in the unfused lower levels. The authors conclude that retrolisthesis and increased translational motion are important factors in determining low-back pain following surgery for idiopathic scoliosis. Instrumentation to L4 should be avoided if possible.

Histologic and electrophysiologic changes following subepineurial hematoma induction in rat sciatic nerve.

The sciatic nerves of 34 rats were used to study the effects of intraneural, extrafascicular hematoma, exclusive of any other trauma. Electrodiagnostic, histologic, and electron microscopic techniques were used. The amount of nerve fiber damage was assessed using computerized planimetry. The effects of hematoma evacuation were also investigated. Changes consistent with partial denervation, such as prolongation of insertion activity and distal latency, and the presence of positive waves and fibrillations, were present in the blood-injected but not in the control groups. Degenerative nerve fiber changes localized to the area of hematoma were present in the blood-injected group and were significantly higher than those in the control group. Although there was a difference in the amount of nerve damage between the blood-injected and the hematoma-evacuated group (less damage), this difference was not statistically significant. These findings suggest that intraneural extrafascicular hematoma produces electrophysiologic and histologic evidence of axonal degeneration affecting nerve fibers in the vicinity of the hematoma. Early evacuation of the intraneural hematoma appears to slightly reduce the deleterious effects of the lesion.

Update on external fixators in the treatment of wrist fractures.

Fifty fractures of the distal radius in 49 patients were treated by either a Roger Anderson device or a Hoffman C-series external fixator. The radiographic and clinical results were evaluated for comparison of the use of the two fixators. The follow-up period for the entire group averaged 15.9 months. For 12 patients personally examined and 12 returning a questionnaire, the follow-up period averaged 27.7 months. The Hoffman fixator and Roger Anderson device gave predictably good results in the treatment of comminuted intra-articular fractures of the distal radius when used in the active age group. Neither was found to yield superior functional results over the other, although the Hoffman fixator had a more rigid configuration. Serious complications may result from the use of external fixators, but these can be minimized by proper technique and care.

Both bone fractures of the forearm: a review of surgical variables associated with union.

A review of 54 patients with both bone fractures of the forearm was undertaken in order to determine the relationship of various fixation devices to the treatment success rate. Three major types of fixation were utilized: conventional plates, compression plates and intramedullary rods.Only one patient had primary bone grafting, regardless of the degree of comminution. Eleven patients had delayed bone grafting an average of five months post injury. There was one non-union. Nineteen patients had open reduction delayed from one to three weeks and all healed primarily.All fractures which were anatomically reduced healed primarily, regardless of the type of fixation. The highest incidence of anatomic reduction (74%) was achieved with compression plate fixation. Conventional plate fixation was accompanied by the lowest incidence of anatomic reduction.

Ochronotic arthropathy and lysosomes: a clinical and electron microscopic study.

In order to understand better the time dependency of the arthritic manifestations of ochronosis, as well as its relationship with lysosomal activities, we sampled a small series of various arthropathies (11 joints). The joint fluid, serum, and urine lysosomal activity levels were measured. The lysosomal enzyme level was elevated in patients with acutely symptomatic, chronically involved ochronotic joints. The enzyme activity level in the other joints (chronically involved) was less. Postulated clinical manifestations of increased levels of intraarticular lysozymes seem to apply to ochronosis as well. Further studies with larger series of patients are warranted.

The Roger Anderson device in the treatment of fractures of the distal end of the radius.

One of the more common as well as difficult fractures to manage is the extension compression fracture of the distal end of the radius. In the physiologically younger patient we believe that every effort should be made to preserve the integrity of the radiocarpal joint and maintain motion of the hand. We have used the technique described by Anderson and O'Neil to treat comminuted, displaced fractures of the distal end of the radius in twenty-five patients from April 1972 through April 1978. Twenty-one of these patients were available for follow-up examination at an average of nineteen months (range, six to forty months) following injury. There were sixteen satisfactory and five unsatisfactory functional results, and three complications. This form of external fixation should be avoided in the older, obese, and osteoporotic patient as well as in the unreliable and uncooperative patient. If these guidelines are followed, we believe that the Roger Anderson device provides satisfactory immobilization and functional results in the treatment of comminuted fractures of the distal end of the radius in the physiologically younger patient, who may be expected to place heavy demands on the wrist.

Coagulolysis assay in the detection of deep vein thrombosis in the orthopedic patient. A preliminary report.

The recently developed coagulolysis assay was utilized in conjuction with fibrinogen uptake scanning to monitor 91 of 111 consecutive orthopedic patients scheduled for hip surgery or total knee replacement. Sixteen patients had abnormal coagulolysis assays and positive scans. Venography was performed in 15 of these patients, and deep vein thrombosis was documented in 12. Five patients developed pulmonary emboli, including one with negative venogram. Thus, over 80% of the patients in which both the coagulolysis assay and the fibrinogen scan were abnormal had additional documentation of deep vein thrombosis. In 41 patients, the coagulolysis assay was negative. Venograms were not routinely performed in this group. However, 3 patients developed pulmonary emboli indicating that deep vein thrombosis developed in this group. Only one patient had a normal coagulolysis with a positive fibrinogen scan. Venography documented a deep vein thrombosis. Thirty-three patients who had normal coagulolysis assays and negative fibrinogen scans also had no evidence of deep vein thrombosis or pulmonary embolism. The coagulolysis assay appears to be a safe, noninvasive study for the detection of deep vein thrombosis. There was only a one per cent false-negative incidence.

Metatarsophalangeal joint fusion of the great toe.

Forty-eight metatarsophalangeal fusions of the great toe were performed for a variety of disorders and followed an average of 28 months. Over 80% of the results were graded as excellent or good. The single most important factor in achieving an excellent result was a solid bony fusion. The degree of valgus or extension in which the f oint was fused did not seem to be critical to the functional result. There was no clinically detectable alteration in gait with arthrodesis of the metatarsophalangeal joint of the great toe.

Management of open fractures of the tibial shaft.

In a retrospective study of 98 open fractures of the tibial shaft, the end result was found to be most closely correlated with the severity of the initial injury. Comparison of six different forms of treatment (external immobilization, external immobilization with early weight bearing, pins and plaster immobilization, intramedullary fixation, multiple screw fixation and plate and screw fixation) did not indicate a superiority of any one method of management.