New advances in bone research.

An edited summary of an Interdepartmental Conference arranged by the Department of Medicine, UCLA School of Medicine, Los Angeles. William M. Pardridge, MD, Associate Professor of Medicine, is Director of Conferences.

Results of interlocking wire trochanteric reattachment and technique refinements to prevent complications following total hip arthroplasty.

In 3.2% of 712 procedures performed in 668 hips after May 1, 1976, separation and migration of the trochanteric fragment occurred after total hip arthroplasty (THA) through a transtrochanteric approach and an interlocking cruciate two-wire technique of reattachment. Of these hips, 23 trochanters showed separation, and in eight the Trendelenburg test was positive.

Flow characteristics of acrylic bone cements.

Flow properties of Simplex, Zimmer Regular, Zimmer LVC, and Sulfix bone cements were measured as functions of time between two and five minutes after mixing. The mass flowrates measured for Zimmer Regular and Simplex were quite similar in the temperature range of 20.0 degrees -23.

Bovine paratuberculosis: an update.

Paratuberculosis is enzootic in the Great Lakes region and northeast US, causing severe economic losses. Sheep, pigs and deer can serve as intermediate hosts. Diagnosis is difficult and there is no entirely satisfactory serodiagnostic test.

Measurement of knee stiffness and laxity in patients with documented absence of the anterior cruciate ligament.

Thirty-five patients with documented absence of the anterior cruciate ligament were tested on the University of California, Los Angeles, instrumented clinical knee-testing apparatus and we measured the response curves for the following testing modes: anterior-posterior force versus displacement at full extension and at 20 and 90 degrees of flexion; varus-valgus moment versus angulation at full extension and 20 degrees of flexion; and tibial torque versus rotation at 20 degrees of flexion. Absolute values of stiffness and laxity and right-left differences for these injured knees were compared with identical quantities measured previously for a control population of forty-nine normal subjects with no history of treatment for injury to the knee. For both the uninjured knees and the knees without an anterior cruciate ligament, at 20 and 90 degrees of flexion the anterior-posterior laxity was greatest at approximately 15 degrees of external rotation of the foot.

Treatment of primary osteoarthritis of the hip. A comparison of total joint and surface replacement arthroplasty.

Of 285 total hip arthroplasties (260 patients) performed for primary osteoarthritis during a six-year period, 135 were resurfaced using a Tharies prosthesis (total hip articular replacement with internal eccentric shells) and 150 were treated with the Trapezoidal-28 total hip replacement. From each of these two groups 100 hips (ninety-one patients in the Tharies group and eighty-six in the Trapezoidal-28 group) that had been followed for two to seven years were evaluated at the time of follow-up in accordance with a predetermined protocol. The patients were younger in the Tharies than in the Trapezoidal-28 group (average ages, fifty-eight and sixty-six years), included more men (sixty compared with thirty-five), and were more active postoperatively.

Total hip replacement in the previously septic hip.

Total hip replacement was performed in either one or two stages in thirty-three hips with active sepsis. The sepsis had followed hemiarthroplasty in six hips, open reduction with internal fixation of a fracture in eight, cup arthroplasty in one, and total hip replacement in eight hips within six years prior to the second total hip replacement. Ten additional patients had total hip replacement following destruction of the hip joint by hematogenous sepsis in nine and by infection following a shrapnel wound in one.

Infection after total joint arthroplasty from distal extremity sepsis.

At the UCLA Medical Center in three patients treated for hematogenous infection after total joint arthroplasty, the source was apparently an infection in the extremities at a site distal to the joint arthroplasty. In a 72-year-old woman with rheumatoid arthritis infection developed in the right hip after total hip arthroplasty following a Staphylococcus aureus infection at the site of a left metatarsophalangeal arthroplasty. In a 64-year-old man with osteoarthritis the staphylococcal infection that developed after right total hip arthroplasty was seeded from a pyarthrosis of the right knee.

Clinical, clinicopathologic, and pathologic alterations in acute monensin toxicosis in cattle.

Twenty beef calves weighing approximately 180 kg were allotted to 3 groups. In group A, 6 calves were given 25 mg of mycelial monensin/kg of body weight orally and were evaluated at 1, 2, and 4 days for clinical, ECG, clinicopathologic, and pathologic alterations. In group B, 7 calves were given a single dose of monensin (40 mg/kg) and 5 were given a 2nd 40 mg/kg dose on day 7; calves were evaluated at days 1, 2, 4, 7, 8, 9, and 11.

Bony ingrowth fixation of newly designed acetabular components in a canine model.

Implantation of a newly designed acetabular component with a porous coating has resulted in superior fixation when compared with acrylic cementation in the short term. Experiments in dogs demonstrate rapid ingrowth within the porous layers, resulting in rigid fixation of the acetabular components despite defects in the prepared bony bed. Acute infection prevents bony ingrowth and causes loosening.

Radiographic techniques for consistent visualization of total hip arthroplasties.

Using a chariot as a patient support system, it becomes possible to obtain consistent radiographic visualization of the hip. The chariot radiographs also allow for a more precise evaluation of the hip at follow-up visits. In most cases subsequent radiographs can be superimposed, differentiating between patient posture and biomechanical characteristics.

Frictional torque in surface and conventional hip replacement.

Unlabelled: The frictional torque of the Trapezoidal-28 total hip replacement and the Tharies SR-3 and SR-5 surface replacements were measured in the University of California at Los Angeles hip-joint simulator in calf serum. Loads of as much as 890 newtons were applied while the femoral component oscillated through a 60-degree arc at forty cycles per minute. Frictional torque, as measured by a ring transducer at a fixed distance from the center of rotation, was seen to diminish as the thickness of the polyethylene increased and was found to be relatively proportional to the diameter of the femoral component.

Revision surgery for failed surface arthroplasty of the hip.

In 17 cases of revision surgery performed for failed surface arthroplasty of the hip at UCLA medical center, the minimum follow-up period was six months (average, 22 months). Causes of failure included aseptic loosening (15), sepsis (1), and unexplained pain (1). High-risk groups include those with deficiencies of bone stock, congenital dysplasia, coxa vara, and osteonecrosis.

Revision of aseptic loose total hip arthroplasties.

Sixty-six patients were revised for aseptic loosening of their conventional hip arthroplasties; follow-up periods ranged from one to nine years. In comparing them with an overall conventional arthroplasty series, there was a higher failure rate with dysplasia and post-traumatic patients, and a lower incidence in osteoarthritic and rheumatoid patients. The average time to revision was four years.

The pathology of failed total joint arthroplasty.

In 94 cases of failed total hip and knee joint arthroplasties, acute and chronic inflammation, acrylic, metal, and polyethylene debris, and histiocytic reaction were assessed in a 0, 1+, 2+, 3+ semiquantitative manner. Chronic inflammation of 2+ to 3+ was not particularly useful in separating a reaction to wear debris from infection. At the time of frozen section, 2+ to 3+ acute inflammation (greater than 5 PMNs per high power field) was used with excellent follow-up bacteriologic correlation to delay replacement of the failed prosthesis until the infection was controlled.

Identification of hip surface arthroplasty failures with TcSC/TcmDP radionuclide imaging.

The roentgenographic identification of femoral component loosening after hip surface arthroplasty is often impossible because the metallic femoral component obscures the bone-cement interface. The use of combined technetium sulfur colloid and technetium methylene diphosphonate radionuclide imaging has been especially useful in the diagnosis of loosening. In 40 patients, follow-up combined TcSC and TcmDP scans at an average of three, nine, and 27 months postoperation revealed significant differences in the isotope uptakes in patients who had loose prostheses compared with those without complications.