Musculoskeletal surgery in eighteenth century America.

Surgeons in America in the eighteenth century treated wounds, fractures, dislocations, and gunshot injuries of the skeletal structures and also contended with osteomyelitis and tuberculosis of bones and joints. In meeting this challenge, they proved innovative, adaptive and courageous, and developed principles of surgery, some of which still are in use today.

Tibial nonunion treated with direct current, capacitive coupling, or bone graft.

Two hundred seventy-one tibial nonunions of average duration of 23.5 months (range, 9-69 months) were treated with direct current (167 patients), capacitive coupled electrical stimulation (56 patients), or bone graft surgery (48 patients). Logistic regression analysis was used to compare heal rates among the 3 treatment methods, to identify risk factors adversely affecting the heal rate, and to predict the probability of successful healing of a nonunion of any given risk profile treated with each of the 3 forms of therapy. Seven risk factors were identified: duration of nonunion, prior bone graft surgery, prior electrical treatment, open fracture, osteomyelitis, comminuted or oblique fracture, and atrophic nonunion. When no risk factors were present, there were no significant differences among the 3 treatment methods. As progressively more risk factors were present, the predicted heal rates decreased significantly regardless of the treatment method. Some differences among the treatment groups did appear in the heal rates: bone graft surgery yielded a worse heal rate when there was a previous bone graft failure, and capacitive coupling had a worse heal rate in the presence of an atrophic nonunion.

A prospective assessment of nutritional status and complications in patients with fractures of the hip.

A group of 40 consecutive patients with hip fractures were studied and confirmed to have a high incidence of protein-calorie malnutrition. The prospective nutritional assessment performed for this study included: serum albumin, serum transferrin, anthropometric measurements, skin testing for delayed hypersensitivity, total lymphocyte count, and a 24-h urine collection for metabolic and nitrogen balance determinations. At 3 months after their hip fracture, 37.5% returned to their premorbid ambulatory status; 42.5% sustained a decrement in their ambulatory status or independence; 12.5% died; 7.5% were lost to follow-up. Of the nutritional parameters studied, albumin was significantly associated with mortality (p = 0.004). Considering those patients with an albumin less than 3.0, a mortality rate of 70% was observed in follow-up (maximum of 11 months), compared with a mortality rate of 18% in patients with an albumin greater than or equal to 3.0. It is concluded that the serum albumin has value as a nutritional index without specialized nutritional parameters, and that a more aggressive approach to nutritional support is needed for the hypoalbuminemic patient with a hip fracture, particularly for those with a serum albumin below 3.0.

The effects of demineralized bone matrix and direct current on an "in vivo" culture of bone marrow cells.

Bone marrow cells (BMCs) from rabbit femora and tibiae were grown in diffusion chambers implanted in rabbit muscle. At 42 days 80% of the BMC chambers exhibited cartilage formation within them. Demineralized bone matrix added to the marrow cell suspension in the chamber accelerated the appearance and increased the number of chambers with cartilage. Mineralization of the cartilage also occurred earlier in the chambers with bone matrix. In a second experiment, a 5-microA direct current cathode in the bone marrow chamber increased the number of chambers containing cartilage from 50 to 80% at day 25. Mineralization also occurred earlier in the chambers with direct current.

Bipolar femoral endoprosthesis: a study correlating component movement with clinical outcome.

Fifty-five bipolar femoral hemiarthroplasties performed between January 1979 and February 1986 were reviewed to correlate component movement with clinical outcome. Fourteen of these patients were examined clinically using the Harris Hip Score and radiographically by the method of Drinker and Murray to determine the per cent of total motion in abduction present at the inner bearing surface. The average followup was 19.7 months. The data demonstrate that the clinical result is related to inner bearing motion. The inner bearing motion is significantly decreased by weight bearing and may be influenced by the size of the femoral component.

Changes in bioelectric potentials on bone associated with direct current stimulation of osteogenesis.

This study was designed to determine whether changes occur in the bioelectric potentials on bone during and after bone stimulation with a 20-microA direct current (DC) and whether the variations in bioelectric potentials are related to the variations in bone formation. The bioelectric potentials were recorded at different times on the rabbit distal tibial surface, during (current-on state) and after (current-off state) DC stimulation with a cathode implanted within the medullary canal. The new bone formed at the end of the experiment was quantitated and related to the bioelectric potentials recorded at current-on and current-off states, respectively. Direct current stimulation resulted in electronegative potential spike centered on the cathode tip while current was applied. After electrical stimulation was turned off, the residual potentials at the end of the experiment did not significantly differ from the initial values. Conversely, the time sequence of the changes was significantly different from the control to the experimental group. The variations in the induced potentials at current-on state were significantly related to the variations in bone formation. This study suggests the existence of a relationship among bioelectric potentials, DC stimulation, and osteogenesis.

Temporal course of bone formation in response to constant direct current stimulation.

Reactive, post-traumatic bone formation in response to intramedullary insertion of a polytetrafluorethylene-coated, 28 gauge stainless steel wire was compared with the sequential bone formation seen in response to an identical intramedullary stainless steel cathode delivering 20 microA constant direct current. Animals were studied at days 1, 2, 3, 4, 5, 7, 9, 11, 14, 17, and 21 after wire insertion. Point count analysis revealed progressive bone formation beginning as early as day 3 on the constant direct current-stimulated side, progressing steadily through day 21. Control tibia, however, began to show bone formation on day 5 with peaking at day 9 and subsequent bone resorption. The osteogenic response at the 20 microA cathode was statistically elevated above that seen at the control on days 11, 17, and 21.

Electrical osteogenesis by low direct current.

A constant direct current cathode was employed in the medullary canal of the rabbit tibia to investigate electrical osteogenesis at low current levels. Currents of 0.015 or 0.075 microA were delivered to the bone and the biological response was compared with contralateral controls receiving 20 microA. This investigation was performed to determine if electrical osteogenesis occurs at current levels below the previously studied range of 1-100 microA with stainless steel electrodes. New bone formed by 0.015 microA cathodes was statistically comparable with that found around inactive cathodes from an earlier pertinent study. The osteogenic response to 0.075 microA cathodes was significantly elevated above that to inactive ones, thus substantiating electrical osteogenesis for currents below 1 microA. However, it is evident that this does not demonstrate a further stimulatory range but that currents near 0.075 microA probably approach the lower significant limit for electrically induced bone growth with stainless steel electrodes.

Electrically induced osteogenesis: relationship between charge, current density, and the amount of bone formed: introduction of a new cathode concept.

A study was performed exploring the relationship between charge, current density, and the amount of new bone formed in the medullary canal of the intact rabbit tibia. The results indicate that the amount of bone formed in the vicinity of a cathode is directly related to both current density and charge. Utilizing stainless steel cathodes delivering a constant current of 20 muamps, the optimum current density was found to be 1.06 X 10(3) muamps/mm2 and the optimum charge, 36.29 coulombs. The amount of bone formed with pulsed current approached that formed with constant current only as the total charge delivered by the pulsed current approached that delivered by the constant current. Based on these findings, a new cathode is designed with eight active ports evenly distributed along its length and providing two and one-half times the amount of bone formed by a conventional cathode. This cathode is now in the early stages of clinical evaluation in patients with acquired nonunion.

A multicenter study of the treatment of non-union with constant direct current.

A clinical study was initiated at the University of Pennsylvania in 1970 to evaluate the use of constant direct current in treating acquired non-union. In 1977 the study was expanded to include twelve participating investigators throughout the United States. The results indicate that, given proper electrical parameters and proper cast immobilization, a rate of bone union comparable to that seen with bone-graft surgery was achieved. Experience dictated that four cathodes, each delivering twenty microamperes of constant direct current for twelve weeks, were required to heal a non-union of a long bone. Of 178 non-union in 175 patients treated with adequate electricity in the University of Pennsylvania series, 149 (83.7 per cent) achieved solid bone union. Patients with a history of osteomyelitis had a healing rate of 74.4 per cent. The presence of previously inserted metallic fixation devices did not affect the end-result healing rate. Of eighty non-unions in seventy-nine patients treated with electricity in the participating investigators' series, fifty-eight (72.5 per cent) achieved solid bone union. Review of the non-unions treated unsuccessfully with constant direct current suggested that inadequate electricity, the presence of synovial pseudarthrosis or infection, and dislodgment of the electrodes are causes for failure with the procedure. Complications of the electrical treatment were minor and there was no deep infection resulting from this procedure in patients without previous osteomyelitis. We concluded that the practicing orthopaedic surgeon utilizing constant direct current to treat non-union should, by adhering to proper fracture management and by following the biophysical principles described herein, be able to achieve a rate of union comparable to that of bone-graft surgery, with a lower associated risk.

Treatment of nonunion with constant direct current.

Laboratory experiments show the following relationships between electricity and bone: (1) stressed bone exhibits electronegativity in areas of compression, (2) living, nonstressed bone exhibits electronegativity in areas of bone growth and healing, and (3) the application of low magnitude direct current to bone induces osteogenesis at the negative electrode or cathode. Based on the above principles, a clinical study was performed in which 10-20 microamperes of constant direct current was used in treating nonunion in 57 patients. The results suggest that specific electrical parameters are required for successful osteogenic stimulation in patients. When these electrical parameters are met, a successful healing rate of 70 per cent can be achieved in treating nonunion with direct current. As experience is gained with this new technique in the treatment of nonunion, the results should improve even further. Basic studies exploring the mechanism(s) whereby electricity induces osteogenesis are opening new vistas into our understanding of bone growth and repair. The extension of these basic studies has far-reaching clinical implications.

A study of radiographic variations of the hip joint.

Anteroposterior radiographs of the pelvis were studied in 920 patients free of hip joint diseases. The average joint space was between 3 and 4 mm in width. Narrowing of the superior joint space was seen in 13 percent of the hips and may represent the earliest finding in osteoarthritis. It was noted as early as the second and third decade in some patients. Other changes noted were narrowing of the lateral joint space, uniform narrowing of the space, an irregular joint space and tilting of the femoral head on the neck.

Direct-current stimulation of non-union and congenital pseudarthrosis. Exploration of its clinical application.

Based on the response of bone to electrical current in previous studies, an exploratory clinical study of the effect of electrical current on non-union and congenital pseudarthrosis was performed. Constant direct current of ten to twenty microamperes was applied to twenty-four non-unions and five congenital pseudarthroses. Complete union occurred in fifteen non-unions and in one congenital pseudarthrosis. A single cathode delivering ten microamperes seemed sufficient to heal non-union in small bones, but multiple cathodes each delivering twenty microamperes appeared to be required to heal non-union in the tibia and femur. As the technique was refined, the percentage of successes increased. While these preliminary results appear promising, further laboratory and clinical experiments are required to define the true role of electrical stimulation in clinical practice.

Cathodic oxygen consumption and electrically induced osteogenesis.

Small amounts of electric current stimulate bone formation in the region of a cathode. The purpose of this experiment is to compare changes in oxygen and hydroxyl ion concentration that occur at the cathode at current levels known to be capable of inducing osteogenesis (10-20 muamps) with those changes that occur at current levels known to be toxic to bone (100 muamps). An oxygen consumption chamber containing an oxygen electrode is fitted with two stainless steel electrodes which are connected to a constant current source. At the cathode, with a current of 100 muamps, oxygen is consumed at nearly stoichiometric rates. At higher current (100 muamps) levels, cathodic oxygen consumption gives way to hydrogen evolution. Cathodic hydroxyl ion production is directly proportional to current. It is concluded from these in vitro experiments that at 10-20 muamps the oxygen tension in the vicinity of the cathode is lowered and the pH is moderately increased. At 100 muamps the oxygen tension is not lowered, but the pH is increased dramatically. If these same changes occur in the vicinity of a cathode in vivo, then lowering the local tissue oxygen tension and raising the local pH may be mechanisms operative in electrically induced bone formation.