Biomedical subjects

J M Kabo

Publications and source records attributed to J M Kabo.

At least 37 records · Page 2Linked to original sources

PubMed1995

Biomechanics of two types of bone-tendon-bone graft for ACL reconstruction.

We measured the initial fixation strength of a new graft, bone-hamstring-bone (BHB), for reconstruction of the anterior cruciate ligament (ACL) in 79 porcine knees and compared it with that of the normal porcine ACL and of the bone-patellar tendon-bone (BPB) graft. All specimens were subjected to ultimate load to failure and cyclic loading tests to assess the amount of graft slippage. The ultimate load to failure for the intact ACL was 1266 +/- 250 N, for the BPB graft 663 +/- 192 N and for the BHB graft 354 +/- 92 N (p < 0.01). After cycling to 235 N (the maximum load for all groups without failure) the average residual displacements after removal of the load for the ACL, BPB and BHB grafts were 0.031 +/- 0.013 cm, 0.078 +/- 0.033 cm, and 0.322 +/- 0.222 cm, respectively (p < 0.01). For the BHB graft the load to failure was less and the amount of graft slippage was more than for the BPB graft. Neither form of reconstruction was as strong as the intact ACL.

Animals↗

PubMed1994

151 endoprosthetic reconstructions for patients with primary tumors involving bone.

As part of the UCLA limb salvage program, 151 patients received 151 endoprostheses for primary tumors involving bone. Follow-up of all patients was to death (56), revision (21), or a minimum two years for the 74 additional survivors (range: 24-114 months; mean: 52 months). Endoprosthetic replacements were of the distal femur (81), proximal femur (19), proximal humerus (13), proximal tibia (11), scapula (11), total femur (8), total humerus (4), intercalary prostheses (2), and one each of the distal humerus and the pelvis. There were three soft tissue sarcomas, five benign bone lesions, and 143 primary malignant tumors of bone. MSTS function was good-excellent in 78%. There were 64 local complications in 55 patients (36%). Mechanical failure occurred in 24 patients (15.9%), local recurrence occurred in ten (6.6%), minor wound healing problems in nine (5.9%), and infection in eight (5.3%). Few systemic complications were reported. Function appeared to be location dependent. All of the 29 patients with benign or low grade malignant tumors (parosteal, IA, IB) have survived. Of the 116 patients with stage IIA and IIB disease, 59% survived three years, and a Kaplan-Meier analysis projects that 56% are expected to survive at five years. Only 17 (11%) of these 151 endoprostheses have been revised; an additional four (3%) eventually came to amputation. The Kaplan-Meier analysis revealed that 91% of the prostheses survived three years and 83% survived five years. The Cox Proportional Hazards model revealed that for patients with stage IIA and IIB disease, the risk of death is four times the risk of the need for revision at five years. Although endoprosthetic reconstructions have their own unique complications, they have proven durable in this series of patients. Local problems usually can be managed without amputation, and patient satisfaction is high.

Bone Neoplasms↗

PubMed1994

The effects of diuretics on posttraumatic joint stiffness and limb swelling in a rabbit periarticular fracture model.

Periarticular long bone fractures usually result in soft-tissue swelling because of edema and hemorrhage, as well as progressive, often permanent joint stiffness. The authors evaluated the effects of chlorothiazide, a commonly used diuretic, and acetazolamide, a weaker diuretic with a different mechanism of action, on joint stiffness and swelling using an established rabbit hindlimb model. Bilateral distal tibial fractures were produced in 30 adolescent New Zealand white rabbits. Twelve rabbits served as age-matched controls and received no treatment, 11 were treated with chlorothiazide, and seven were treated with acetazolamide, each for five days at doses adjusted for body weight but equivalent to human dosing. Eleven limbs were excluded from study because of fracture angulation in excess of 10 degrees. The mean stiffness ratios, comparing preoperative stiffness with stiffness at the end of the three-week study period, for diuretic-treated rabbits were significantly less than those in the control rabbits; there was no difference between the two treated groups. The total swelling and time to peak swelling did not differ among the three groups; however, peak swelling was least in the chlorothiazide group, the strong diuretic, when compared with the control and acetazolamide groups. The marked effect of diuretics on joint stiffness and their minimal effect on limb swelling were unexpected results and, taken in conjunction with previous treatment modalities tested in this model, indicate a complex, still poorly understood sequence of events leading to joint stiffness after periarticular injury.

Acetazolamide↗

PubMed1994

Hydroxyapatite-coated distal femoral replacements. Preliminary results.

A custom-designed, hydroxyapatite-coated distal femoral replacement was developed and implanted in five individuals at the authors' hospital. The indications for this type of prosthesis were a multiply failed cemented endoprosthesis in two individuals; a revision of an infected, previously cemented endoprosthesis in another; a primary low-grade sarcoma in a fourth, and a stage III giant cell tumor in the final individual. Mean follow-up time was 3.3 years (range, 2.9-3.5 years). The functional results, based on the Musculoskeletal Tumor Society (MSTS) criteria, were excellent in one patient (20%) and good in four patients (80%). Musculoskeletal Tumor Society functional scores ranged from 25 to 35 (mean, 29.8). No patient had thigh pain. All the femoral components appeared well fixed on radiographic evaluation. These preliminary results indicate that a hydroxyapatite-coated distal femoral replacement may represent a viable alternative to a cemented endoprosthesis for aggressive benign lesions and low-grade sarcomas requiring resection. In addition, it appears to be a viable solution for failed cemented endoprostheses in individuals who have survived their disease.

Adolescent↗

PubMed1994

The effect of experimental hemarthrosis on joint stiffness and synovial histology in a rabbit model.

The effect of a single injection of unpreserved blood on joint stiffness and on synovial and cartilage histomorphology in the ankle joints of rabbits was determined at ten and 28 days after injection. The same volume of saline was placed in the contralateral ankle for comparison. After ten days, the hemarthrosis ankle was stiffer than the control ankle (p < 0.027), whereas at 28 days there was no statistical difference in stiffness between the hemarthrosis and control ankles, regardless of whether the limbs had been immobilized. Also after ten days, the hemarthrosis ankles had varying amounts of clotted blood, darkened articular cartilage, hypertrophic synovium with reactive blood vessels, and macrophages containing heme. The gross and histologic appearance of the saline ankles was normal. After 28 days, there were no differences in gross or microscopic appearance between the two ankles of the caged or immobilized rabbits. All ankles exhibited retreating inflammatory response in the synovium and mild synovial thickening. Acute hemarthrosis, unassociated with fracture or discernible joint injury, caused only transient changes in joint stiffness and synovial histology. These results indicate that the presence of blood in an otherwise grossly uninjured joint should not lead to ultimate compromise in cartilage integrity or joint function. Therapeutic arthrocentesis for acute posttraumatic hemarthrosis does not appear to be necessary for the prevention of permanent problems.

Animals↗

PubMed1993

Optoelectronic evaluation of trunk deformity in scoliosis.

In this study, truncal deformity in patients with scoliosis was evaluated by circumferential scanning using an optoelectronic device (Optronic Torsograph, Anima Corp., Tokyo, Japan). This device generates cross-sectional skin surface topography at 10 axial levels to provide a three-dimensional representation of truncal shape. Ninety-three patients with suspected idiopathic scoliosis were evaluated with conventional Cobb measurements, and their parameters were computed using the device's measurements. The geometric cross-sectional indexes correlated poorly with the Cobb angle and were highly variable during repeated measurements. The optoelectronic device's angle, a measure of centroid curvature, correlated highly with the Cobb angle for primary spinal curves. The highest correlation was observed in thoracolumbar curves. This optoelectronic device has clinical relevance as a method for further scoliosis screening and monitoring the progression of spinal curvature in a patient.

Adolescent↗

PubMed1993

Effects of antihistamines on joint stiffness and bone healing after periarticular fracture.

In an effort to blunt the inflammatory response following injury, we studied the effects of antihistamines on joint stiffness and bone healing after periarticular fracture. The hind limbs of 37 New Zealand white rabbits were instrumented with intramedullary Steinmann pins to allow immobilization after creating a distal tibia fracture. After periarticular ankle fracture, the rabbits were divided into groups to receive chlorpheniramine, low-dose terfenadine, high-dose terfenadine, or no antihistamine. Antihistamine was administered for the first 5 days after fracture. At 3 weeks after fracture, the rabbits treated with antihistamines showed a significant reduction in joint stiffness compared to control animals. To determine if antihistamine also retarded bone healing, an additional 12 New Zealand white rabbits underwent bilateral drilling of the midshaft of the femur with a 2.5 mm Steinmann pin. Six animals received oral terfenadine, and six served as controls. After 5 weeks of cage activity, the animals treated with the antihistamine showed a significant decrease in energy to failure of the femurs on torsional testing. Qualitative microscopic examination revealed less mature callus at the site of the femoral cortical defect in those animals treated with the terfenadine. Antihistamine may have heretofore unconsidered benefits in preventing post-traumatic joint stiffness but may slow healing of associated bony injuries.

Animals↗

PubMed1993

In vivo wear of polyethylene acetabular components.

Polyethylene acetabular cups retrieved at revision surgery were measured by a shadowgraph technique to determine linear wear, and the values were compared with those obtained from radiographs. There was a close correlation between them, although the radiographic measurements slightly underestimated the true wear. Average linear wear rates for surface-replacement components were much greater than those for conventional prostheses with femoral heads up to 32 mm in diameter. Volumetric wear, calculated using a new formula, was found to be less than previously reported in vivo, and similar in magnitude to the results of experimental wear tests in vitro. The volumetric wear rates were greatest for the surface-replacement components and, for conventional components, were found to increase in a linear manner with component diameter.

Acetabulum↗

PubMed1993

Expandable endoprosthetic reconstruction of the skeletally immature after malignant bone tumor resection.

The mainstay of local control of primary bone malignancies in the skeletally immature has been amputation or, in selected cases, rotationplasty. The development of expandable endoprostheses has permitted an alternative approach for local control in the growing child. Between January 1985 and December 1987, 12 skeletally immature patients with primary malignant bone tumors were treated with extremity reconstruction with cemented custom-expandable endoprostheses after wide resection of their lesions. All patients were observed until death (four) or revision (two) with a minimum two-year follow-up period for the survivors (average, 3.1 years). Seven patients have undergone a total of 11 expansions and one patient was lengthened with a revision-expandable prosthesis. Four patients have not needed expansion. Eight patients have had a total of ten complications. Seven of the ten complications (70%) were prosthesis related and associated with failure of the expansion mechanism. The Musculoskeletal Tumor Society (MSTS) overall rating was good to excellent in seven patients (58%), fair in three (25%), and poor in two (17%). In five distal femoral arthroplasties and one total femoral arthroplasty where the tibial bearing component was cemented through the physis, tibial and epiphyseal growth was observed to be normal and equal to the nonoperative side. This suggests that partial central epiphyseal and physeal ablation does not cause physeal arrest. Although the high rate of expansion mechanism failure necessitates redesign, preliminary results suggest that expandable endoprostheses do offer an alternative to amputation and rotationplasty as a means of local control and extremity reconstruction in children with primary malignant bone tumors.

Adolescent↗

PubMed1993

Passive motion: the dose effects on joint stiffness, muscle mass, bone density, and regional swelling. A study in an experimental model following intra-articular injury.

We studied the effects of passive motion on joint stiffness, muscle mass, bone density, and regional swelling after an intra-articular injury. Instrumentation was applied to the hindlimbs of thirty adolescent New Zealand White rabbits to allow either passive motion or immobilization of the ankle. The knee was immobilized by the locking together of Steinmann pins that had been placed within the medullary canals of the tibia and femur. An intra-articular injury was produced by drilling of the tibial pin through the ankle joint into the talus and subsequent withdrawal of the pin from the ankle joint. The rabbits were divided into five groups, and they received four, eight, twelve, sixteen, or twenty-four hours of passive motion each day during the three-week period of study. One ankle of each rabbit was moved through an arc of 90 to 170 degrees of dorsiflexion at one cycle per minute, while the contralateral ankle was immobilized in 100 degrees of dorsiflexion with an aluminum splint, which was fixed to the aluminum block that was used to stabilize the knee joint. We found that sixteen and twenty-four hours of passive motion prevented stiffness of the joint. Passive motion for shorter periods was ineffective, even harmful, and resulted in stiffness ratios that were as much as four times higher than those of the control limbs (those treated with immobilization). Swelling of the limb decreased only in the group that received twenty-four hours of passive motion. Muscle mass increased by an average of 13 per cent (range, 4 to 34 per cent), in comparison with that of the immobilized limbs in every group that was treated with passive motion. Bone density was maintained only in the limbs in which the ankle became stiff (ankles that had been treated with passive motion for twelve hours or less). An inverse relationship was noted between the duration of passive motion and the radiographic density of the distal tibial metaphysis; this relationship was statistically significant (p < 0.01). The limbs treated for twelve, eight, or four hours each day showed progressively greater bone density in comparison with those treated with immobilization or with sixteen or twenty-four hours of passive motion.

Animals↗

PubMed1993

Computer graphic analysis of endosteal expansion after total hip arthroplasty.

Femoral endosteal expansion is known to occur naturally with aging and may contribute to femoral component loosening after cemented total hip arthroplasty (THA). Previous roentgenographic models used to quantify femoral expansion have used a limited number of measurements at arbitrary axial sites in one roentgenographic view. A computer graphic model is introduced, which uses standard anteroposterior (AP) and lateral roentgenograms to reconstruct a three-dimensional model of the femur between the lesser trochanter and the distal end of a cemented prosthesis. The model was used retrospectively to calculate endosteal and periosteal surface area and volume at the time of surgery and at follow-up examination for 22 patients who had been treated with hip arthroplasty (average, 9.3-year follow-up observation). Endosteal surface area and volume were found to increase an average of 3.1 cm2 and 1.7 cm3, respectively. Periosteal dimensions did not change significantly. Overall endosteal expansion occurs in the vicinity of the implanted prosthesis. The extremely low interobserver variability indicates that this model provides a reliable method of following surface area and volume changes around a cemented hip prosthesis.

Aged↗

PubMed1993

The influence of conformity and constraint on translational forces and frictional torque in total shoulder arthroplasty.

Glenoid loosening in total shoulder arthroplasty (TSA) may result from translational forces and frictional torque generated at the articular surfaces and transmitted to the fixation interface. The effect of glenohumeral articular design on the magnitude of these translational forces and frictional torques has not been evaluated previously. Seven different glenohumeral designs were evaluated on a specially designed fixture integrated with a materials test system. The degree of conformity and constraint in the glenohumeral designs directly affected the forces generated during translation and rotation of the humeral head. Maximum translational forces occurred close to the midline in the more conforming design. The less conforming designs generated lower translational forces and frictional torques. Because frictional torque and translational forces at the glenohumeral articulation may contribute to glenohumeral loosening, the use of less conforming and less constrained designs is advocated where possible to reduce the potential for mechanical loosening of the glenoid component.

Biomechanical Phenomena↗

PubMed1992

Intra-articular corticosteroid reduces joint stiffness after an experimental periarticular fracture.

Early care after surgery or trauma to the extremities often includes a period of immobilization. The resultant joint stiffness may require extensive rehabilitation and may permanently limit function of the limb. Posttraumatic joint stiffness is particularly vexing in the small joints. In an experimental model, we tested the effects of intra-articular corticosteroid injections on stiffness in a joint at risk of posttraumatic joint stiffness. Triamcinolone was injected into ankle joints of rabbits after distal tibial fractures. Three weeks after injury, joint stiffness increased 34% in ankles injected with the steroid. Stiffness in ankles injected with saline solution and in ankles treated with no injection increased 133% and 224%, respectively. Limb swelling and tibial torsional strength to failure were not significantly affected by either of the treatments.

Animals↗

PubMed1992

Biomechanical effects of a new point configuration and a modified cross-sectional configuration in Kirschner-wire fixation.

Kirschner-type wires (K-wires) comprising three different point configurations and two cross-sectional shaft configurations were drilled into bone to determine the insertional force required and the holding power achieved with each type. Round K-wires with either a diamond point or a high rake-angle trocar point were compared with each other and with C-wires, which have a rounded square cross section and a short diamond point. The K-wires performed superiorly to C-wires with respect to bone penetration. The K-wires demonstrated about twice as much holding power as the C-wires. No significant differences in performance were detected between the diamond-tipped and trocar-tipped K-wires with respect to either insertion or pull-out. For all three wire-tip combinations, insertion was facilitated by faster drill speed, but holding strength was superior with slower speed. For ease of insertion, even at oblique angles, and for maximum holding strength, the high-rake angle, trocar-tipped K wire is best.

Animals↗

PubMed1992

Biomechanical comparisons of unidirectional and bidirectional Kirschner-wire insertion.

Peak axial loads on entry and peak pull-out loads were measured for Kirschner-wires (K-wire) inserted into canine metacarpals. The wires were placed using a standard, unidirectional drill and using an oscillating, bidirectional drill that reversed spin direction every 120 degrees. Seven trocar-tip wires were compared with seven diamond-tip wires using each drilling method. The trocar-tip wires demonstrated equal peak axial loads on entry when drilled at comparable speeds unidirectionally and bidirectionally. Pull-out load of the trocar tip after bidirectional insertion was less than that for unidirectional insertion but was still in the clinically useful range. The diamond-tip wire exhibited higher peak axial load on entry and lower peak pull-out load when drilled bidirectionally. Bidirectional insertion of a trocar-tip K-wire offers fixation characteristics comparable with those with unidirectional insertion and will potentially reduce the risk of soft-tissue damage associated with winding-up and avulsion of vital structures on the spinning shaft of a unidirectional driver.

Animals↗

PubMed1992

Continued growth of the proximal part of the tibia after prosthetic reconstruction of the skeletally immature knee. Estimation of the minimum growth force in vivo in humans.

We studied five skeletally immature patients who had a cemented endoprosthetic replacement involving the proximal part of the tibia because of a malignant tumor. In each patient, the cement-column fractured, allowing additional physeal growth. With plain radiographs and scanograms, we determined the cross-sectional areas of the physes, the cement-mantle, and the tibial component. Using the known tensile strength of polymethylmethacrylate cement, we then calculated the minimum force that the growth plates must have overcome to fracture the cement. This averaged 584 newtons per square centimeter. This observation of continued tibial growth after partial physeal ablation with a cemented prosthesis in skeletally immature patients presented a unique opportunity to estimate the force generated in the human physis during growth.

Biomechanical Phenomena↗

PubMed1992

Acetabular reconstruction with a threaded prosthesis for failed total hip arthroplasty.

The MEC-Ring threaded acetabular component was used in 35 patients for revision of failed cemented hip arthroplasties, and 32 have been observed for two to four years (mean, 2.5 years). With only a short-term follow-up period, 44% of patients have already required revision for failure of the MEC-Ring acetabular component. Patients with especially poor acetabular bone stock that had had structural bone graft had a significantly higher rate of failure. The authors developed a technique of supine oblique roentgenograms that allowed better visualization of the component-bone interface. Eighty-six percent of patients had radiolucencies, and 67% of these were progressive. The presence of progressive radiolucencies, component migration, or both was associated with a higher failure rate. Progressive radiolucencies were also associated with a worse pain score in patients whose arthroplasties have not failed. The MEC-Ring threaded component is not recommended for revision hip arthroplasty, especially in cases with poor acetabular bone stock.

Acetabulum↗

PubMed1992

The mechanism of loosening of cemented acetabular components in total hip arthroplasty. Analysis of specimens retrieved at autopsy.

Late aseptic loosening of cemented acetabular components is governed by the progressive, three-dimensional resorption of the bone immediately adjacent to the cement mantle. This process begins circumferentially at the intraarticular margin and progresses toward the dome of the implant. Evidence of bone resorption at the cement-bone interface was present even in the most well-fixed implants before the appearance of lucent lines on standard roentgenographic views. The mechanical stability of the implant was determined by the three-dimensional extent of bone resorption and membrane formation at the cement-bone interface. The leading edge of the membrane is a transition zone from regions of membrane interposition between the cement and the bone to regions of intimate cement-bone contact. Histologic analysis revealed that progressive bone resorption is fueled by small particles of high density polyethylene (HDP) migrating along the cement-bone interface and bone resorption occurs as a result of the macrophage inflammatory response to the particulate HDP. Evidence in support of a mechanical basis for failure of fixation was lacking. The mechanism of late aseptic loosening of a cemented acetabular component is therefore biologic in nature, not mechanical. This is exactly opposite to the mechanism of loosening on the femoral side of a cemented total hip replacement, which is mechanical in nature.

Acetabulum↗