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Biomedical subjects

R B Hohn

Publications and source records attributed to R B Hohn.

At least 19 recordsLinked to original sources
PubMed1989

Mechanical properties of primate vascularized vs. nonvascularized patellar tendon grafts; changes over time.

Mechanical properties of patellar tendon autografts used to replace the anterior cruciate ligament (ACL) in the cynomolgus monkey were measured at four time periods up to 1 year. The ACL was replaced in each knee with the medial half of the patellar tendon: as a vascularized graft (VG) on one side and as a nonvascularized or free graft (FG) on the other. Postoperative care consisted of 4 weeks of cast immobilization at 30 degrees flexion followed by unrestricted activity in a large cage. Both grafts showed low stiffness and maximum force at 7 weeks (24% and 16% of ACL control values, respectively), increasing to 57% of control ACL stiffness and 39% of control maximum force by 1 year. Corresponding material properties, modulus and maximum stress, also increased over time, but at 1 year were only 34% and 26% of ACL values, respectively. The results indicate that retaining vascularity does not prevent significant reduction in graft properties that occur postoperatively, nor does it accelerate the return in strength and stiffness. Tissue stiffness, which returns earlier than maximum force and joint anteroposterior (AP) force displacement data, should be routinely reported in any healing study. Finally, in studies of this kind, the large variation in the results makes sampling only one or two animals from each time period unreliable.

Animals↗
PubMed1987

Brucella canis osteomyelitis in two dogs with total hip replacements.

Brucella canis was isolated from the cement or bone surrounding a hip prosthesis after total hip replacement was performed for treatment of hip dysplasia in 2 dogs. Lameness or signs of infection were not evident for 9 and 16 months after surgery. Osteomyelitis surrounding the prostheses was detected radiographically only after the lameness developed. The origin of the B canis infection in the 2 dogs was believed to be hematogenous because of the biologic behavior of this organism and because of the duration of excellent limb function after hip replacement. A slide agglutination test for B canis should be performed as a screening test on any canine total hip candidate when the anamnesis and physical examination indicate that the dog may have been exposed to or infected with B canis.

Animals↗
PubMed1986

Distal tibial fractures in dogs and cats.

A total of 43 fractures of the distal tibia in dogs and cats were evaluated for fracture patterns, methods of stabilization, and time to bone union. Fractures of the metaphysis (9.3%), physis (30.9%), epiphysis (2.3%), and malleoli (58.2%) were classified. Open reduction and internal fixation, with combinations of Kirschner wire, orthopedic wire, and bone screws, were the methods of fixation used in the majority of fractures. These relatively simple methods of fixation were applied to all sizes of dogs and cats and resulted in an average bone healing time of 6 weeks.

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PubMed1986

Fractures of the tibial diaphysis in dogs and cats.

One hundred ninety-five fractures of the canine and feline tibial diaphysis were reviewed. Signalment of the animal; cause, location, and description of the fracture; treatment of the fracture, and response of the fracture to treatment were evaluated. Spiral and oblique fracture patterns were the most frequent in both juvenile (animals less than 12 months old) and adult animals (animals more than 12 months old). Comminuted fractures and open fractures were seen more commonly in the adult animal. Closed reduction and external coaptation as a method of repair was used more frequently in juveniles and open reduction and internal fixation was used more frequently in adults. When open reduction and internal fixation was used, pins, wires, and Kirschner Ehmer external splints were used more frequently in juveniles, and plate and screw fixation of the fracture was used more frequently in adults. The time to bone union varied with age of the animal and method of fixation. Healing times increased in adults, and increased as the stability of the fracture fixation increased. Complications included osteomyelitis and nonunions. Nonunions developed in 4.1% of the fractures not lost to follow-up.

Animals↗
PubMed1986

[Replacement of the hip joint in the dog].

Hundreds of total hip replacements in dogs have been performed at the Ohio State University of Veterinary Medicine since August 1976. Dogs with disabling diseases or conditions of the hip are candidates for the THR. The technique provides the dog with a pain free, mechanically sound ball and socket joint. The most commonly encountered complication is dislocation, while the most disastrous complication is infection. Complications can be minimized through adherence to detail during the procedure. By following strict aseptic principles, surgical technique and postoperative care, successful hip function has been achieved in 94.7% of the cases.

Animals↗
PubMed1986

Comparison of porous titanium-surfaced and standard smooth-surfaced bone plates and screws in an unstable fracture model in dogs.

Bilateral midshaft femoral osteotomies were fixed with a 3-mm fracture gap in 6 dogs. In each dog, one femur was fixed with a porous titanium-surfaced bone plate and screws, whereas the opposite femur was fixed with a standard smooth-surfaced bone plate and screws. The mean removal torque for porous titanium-surfaced screws (32.3 kg X cm) was significantly (P less than 0.01) greater than the mean removal torque for standard screws (4.4 kg X cm). Osseous tissue ingrowth into the surface of porous titanium-surfaced screws was verified by histologic examination of the bone-screw interface. Radiographic and histologic examinations of the osteotomy gaps showed accelerated primary gap healing in osteotomies fixed with porous titanium-coated implants, compared with slower callus healing seen in osteotomies fixed with standard smooth-surfaced implants.

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PubMed1985

Ventrolateral approach for repair of sacroiliac fracture-dislocation in the dog and cat.

A ventrolateral approach to the sacroiliac joint is described as an alternative to the dorsolateral approach for the repair of sacroiliac dislocations and sacral wing fractures. The technique described here usually is performed blindly with digital palpation; however, the approach may be extended craniodorsally, allowing direct visualization of the sacroiliac joint. This technique facilitates reduction and stable fixation, with good purchase of the implants in the sacrum, for the repair of sacroiliac fracture-dislocation. This method of repair was used on 20 patients, with good to excellent clinical results.

Animals↗
PubMed1983

Open drainage and delayed autogenous cancellous bone grafting for treatment of chronic osteomyelitis in dogs and cats.

Ten dogs and 1 cat with 12 chronically infected bones were treated surgically by means of saucerization, primary internal or external rigid fixation, and open irrigation drainage. After formation of a healthy granulation bed, autogenous cancellous bone grafting and skin closure were performed. Eleven of 12 bones healed 4 to 7 weeks (mean, 4.8 weeks) after treatment, without recurrence of infection. Eight of 12 chronically infected bones had a polymicrobial infection, with 2 to 6 bacterial species isolated. Gram-negative bacteria were isolated from 7 of the 12 bones, and anaerobic bacteria were isolated twice.

Animals↗
PubMed1983

Effects of tissue antigen matching on the healing of fresh cancellous bone allografts in dogs.

The radiographic and histologic healing patterns of fresh cancellous bone allografts were compared with those of fresh cancellous autografts in dogs. Two groups of allografts were studied: 1 group of littermate pairs with minor histocompatibility mismatches, and 1 group of unrelated pairs with major histocompatibility mismatches. Pairs were chosen on the basis of preoperative serologic typing and mixed lymphocyte cultural assay of lymphocyte-defined compatibility. Generally, grafts with minor mismatches and autografts achieved bony union in 6 weeks with grafted bone serving as a scaffold for new bone formation. Grafts with major mismatches were resorbed and replaced by fibrocartilage. Healing of osteotomy sites grafted with mismatched bone occurred by ingrowth of host periosteal and endosteal new bone.

Animals↗
PubMed1982

Fracture-associated sarcoma in the dog.

Seven fracture-associated sarcomas developed in large-breed dogs after stabilization of comminuted long bone fractures with stainless steel plates and screws. In most cases, the healing pattern of the fractures was disturbed. The mean interval between fracture occurrence and tumor diagnosis was 5.5 years. Radiographically, the sarcomas were typified by smooth-bordered subperiosteal proliferation and soft tissue mineralization. Cortical destruction was variable. Several histologic subtypes of osteosarcoma were seen. Four sarcomas had a marked inflammatory cell component and 5 of the dogs had clinical evidence of chronic infection. These findings were similar to those in 35 previously reported fracture-associated sarcomas, even though many types of fixation devices in addition to plates, as well as no fixation at all, were represented in these cases. Fracture-associated sarcomas most frequently were found to be diaphyseal, and the femur accounted for almost half of the sarcomas reported.

Animals↗
PubMed1976

Osteosarcoma associated with metallic implants. Report of two cases in dogs.

This is a report of two dogs in which osteosarcomas arose in association with metallic orthopedic implants. One neoplasm occurred in the distal humerus of a 12-year-old Doberman Pinscher. A stainless steel intramedullary pin had been implanted in the bone 11 years previously. Upon removal, corrosion of the pin was noted. The second neoplasm arose in the proximal tibia of a 12-year-old Irish Wolfhound. Six years previously, a fracture of the tibia had been repaired with a plate and screws made of the same type stainless steel, type 316L, by the same manufacturer. No corrosion appeared to have occured. Infection had not occured in either animal.

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