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Biomedical subjects

H U Cameron

Publications and source records attributed to H U Cameron.

At least 73 records · Page 4Linked to original sources
PubMed1990

Acetabular revision with a bipolar prosthesis.

In using bipolar prostheses for selected acetabular revision two groups were identified, those with an intact ring with thin flexible walls and those requiring massive allografting. In the intact ring group (15 cases), the largest possible bipolar head was used with minimal grafting. These have uniformly been trouble-free with acetabular reconstitution with minimal to no migration. In the massive allograft group (22 cases), the results have not been so spectacular, with only 55% good or excellent results. This is not necessarily a function of the acetabulum, since many of the femurs in this group also required allografting. No major migration has occurred, but the follow-up period is less than three years, and some migration is probably to be anticipated. It is concluded that, in these two situations, use of a bipolar prosthesis is a simple technique for dealing, at least in the short term, with a very difficult problem.

Acetabulum↗
PubMed1990

Hinged total knee replacement: indications and results.

Twenty-seven hinged (Guepar II) knee replacements were performed on 26 patients with a follow-up of 1 to 7 years (mean 3 years). Indications for the procedure were bone loss (nine cases) nonunion of tibial or femoral fractures (four), anteroposterior instability (five), mediolateral instability (eight) and recurvatum instability (one). Results were good or excellent in 66.6%. Two patients required revision and there were three other implant-related complications. All press-fit stems were radiolucent to some extent and some radiolucency was present close to the knee in all revisions of stem components. No radiolucency was present in revisions of non-stem cemented components. Although the introduction of variable stem length, semi-constrained knees has reduced the need for implants such as the Guepar II prosthesis, the results, especially in terms of radiolucency, are surprisingly good. The authors conclude that a hinged knee remains of value in desperate situations.

Aged↗
PubMed1989

Difficult implant retrieval: a case report.

Artificial joint prostheses can be expected to fail eventually. The author describes the case of a woman whose cemented knee-joint hinge prosthesis failed and required revision. This prosthesis was designed so that the stem became thinner as it approached the bearing surfaces. As a result the implant could not be removed from the cement and the cement could not be removed without severe destruction of surrounding bone. Although this prosthesis is no longer being used, there may be patients having this implant who will require revision in the future. This paper warns surgeons that its removal will be extremely difficult and appropriate plans should be made preoperatively. The author concludes that no stemmed implant should be cemented in place if it cannot readily be removed from the cement.

Aged↗
PubMed1989

Tips of the trade #15. Removal of hardware prior to total hip replacement.

Since the introduction of metals into orthopaedic surgery over a hundred years ago, patients often present with a wide variety of hardware in their bones. Normally this is of little significance, but if the hardware is in the proximal femur and the hip is arthritic, then the metal must be removed before hip replacement can commence. This paper presents a series of guidelines to be used in such cases.

Bone Plates↗
PubMed1989

An examination of factors contributing to failure of bipolar prostheses.

Preoperative factors that may lead to poor results in bipolar prostheses were examined in 34 patients with aseptic failures of their prostheses. Nineteen cases were revised for acetabular pain, seven for failure of the bearing insert, seven for a loose stem, and one for dislocation. The single significant factor that predicted a poor outcome was the angle of the sourcil of the acetabular roof. The group with acetabular pain had an average sourcil angle of 15.6 degrees compared with 5 degrees in those that failed for other reasons.

Adult↗
PubMed1989

Total knee replacement in Paget's disease.

Due to rapid bone turnover in Paget's disease, loosening of artificial joints might be expected to be a problem, especially if they are of the tissue ingrowth type. Two patients with Paget's disease, who had had knee replacement with this type of prosthesis and have been followed for two years, have both done well to date. It appears that ingrowth-type implants can be used in the presence of Paget's disease. Paget's disease, which was first described in 1877, is characterized by a rapid turnover of bone. The cause of Paget's disease has yet to be determined. The common sites attacked, at least in a Canadian population, are the pelvis (45.4%), vertebrae (22%), femur (10%), tibiae (3.6%), and patellae (0.2%). Paget's occasionally gives rise to arthritic changes in a joint adjacent to the lesion, although the precise mechanism is uncertain. Disturbance of the subchondral bone due to hyperemia and overload due to increasing deformity have been cited as possible reasons. There was and is concern that joint replacement with cemented components would result in rapid loosening due to increased bone turnover. However, it has yet to prove a major problem. So far no reports have appeared in the literature on the effects of Paget's disease on knee replacement, specifically the effects of the porous tissue ingrowth type components that are now in common use. Two patients with Paget's disease around the knee who had had a knee replacement of this type are presented, with over two years of follow-up.

Aged↗
PubMed1988

Design rationale in early clinical trials with a hemispherical threaded acetabular component.

Ninety-eight cases of a titanium hemispherical screw cup were followed for 1-3 years (average, 2 years). To differentiate stem problems from acetabular problems, as and because the early results of the cemented stem are well known, the authors studied only those uncemented screw cups with a cemented stem. Of five cases with acetabular pain, one was definitely loose and two were probably loose and require revision. With increasing experience, the selection criteria for the use of an uncemented screw cup have become increasingly rigid; today, the loose cases would probably be handled with a bipolar implant. In most cases initial radiolucency decreased with time, and on clinical radiographs the vast majority showed no radiolucency. The overall Harris rating was 91% (excellent). The early results for this component are quite promising, but further longitudinal studies are required.

Adult↗
PubMed1988

Potential complications of total knee replacement following tibial osteotomy.

Ligament balancing in total knee replacement allows the correction of virtually any intra-articular deformity and the use of a semi-constrained knee. The capacity for overcorrection to balance extra-articular deformities is, however, quite limited. The authors found this to be true in a case requiring tibial osteotomy after total knee replacement. Eventually, the patient required a long-stem hinge prosthesis. After this case, the authors have preferred to correct extra-articular bony deformities of more than 15 degrees prior to total knee replacement.

Humans↗
PubMed1988

Hip surgery in aortofemoral bypass patients.

Hip surgery in the presence of an aortofemoral bypass graft is dangerous. The use of an anterior spike retractor and the position of the leg in extreme adduction and rotation pose a potential threat to the graft. If hip surgery is necessary, a large trochanteric osteotomy should be performed to avoid both of these dangers.

Aorta, Abdominal↗
PubMed1988

A comparison of unicompartmental knee replacement with total knee replacement.

The knees of 20 patients with a unicompartmental arthroplasty on one s ide and a total replacement on the other were compared at follow-ups of over two years. Length of hospitalization was slightly less with the unicompartmental knees and recovery was faster. By one year, however, there was essentially no difference between the unicompartmental knees and the total replacements in spite of the fact that the former had a better range of movement. This suggests that flexion beyond 105 degrees is not of great significance to elderly people living in the West. It also suggests that, as the posterior cruciate was resected or lengthened in the majority of the total knee replacements, the presence or absence of this ligament does not affect the activities of daily living. Complications both early and late were more frequent with a unicompartmental knee, possibly implicating inferior patient selection, instrumentation, and implant design.

Activities of Daily Living↗
PubMed1988

Results of bone grafting of tibial defects in uncemented total knee replacements.

Bony defects of the articular surface are frequently encountered in total knee replacement. As an alternative to excising more tibia and using a thicker tibial component, autogenous bone grafts have been used to fill these defects. The authors have analysed 43 cases in which bone grafts were used in conjunction with an uncemented tibial component. The follow-up was 2 to 7 years. The results in these cases were compared with those in a similar group using uncemented components in which bone grafting was not required. There were 15 central grafts and 28 edge grafts. All the edge grafts and seven large central grafts were fixed with screws. If the graft size was more than 1 cm2, patients were not permitted to bear weight for 4 to 6 weeks. In the others, weight bearing was allowed immediately. All grafts united, most within 6 months, and substantial collapse was not observed. Notable sinking of the tibial component occurred in one late case, in which a rotatory subluxation developed due to patellar dislocation. Collapse of the graft in a recent case, however, suggests that when large grafts are used, a heavy central stem should be used on the tibial component.

Aged↗
PubMed1988

Clinical results with an uncemented plastic tibial component in unicompartmental knee replacement.

To determine the role of unicompartmental knee replacement in knee arthroplasty and, in particular, the design and function of the ICLH (Finsbury Prosthetics Ltd., London, UK) knee prosthesis, the authors report their experience with 18 patients (15 women and 3 men, mean age 73 years), who underwent unicompartmental knee replacement with this prosthesis. The prosthesis failed in five (27.8%) cases, but in the remainder the results were good to excellent over a follow-up extending to 6 years (mean 4.5 years). The main problem with the ICLH prosthesis is the linear wear of the plastic of the tibial component, caused by a sharp radius at the edge of the femoral component. This leads to fracture and breakdown of the tibial portion. Because the short-term results are good but the long-term results are poor, the authors suggest that the ICLH unicompartmental knee prosthesis should be reserved for use in patients whose life expectancy is short.

Aged↗
PubMed1988

Patella baja complicating total knee arthroplasty. A report of two cases.

Severe noniatrogenic patella baja is a rare condition. Two cases were seen accompanying severe osteoarthritis of the knee. In both cases, following total knee arthroplasty the patella failed to make contact with the femoral component. The tibial tubercle had to be shifted proximally 2 cm to restore the normal joint mechanics. In one case, dislocation of the patella to gain access to the knee could be achieved only with osteotomy of the tibial tubercle. The technique of tibial tubercle elevation adopted was to raise a long bone flap. This allowed the tibial tubercle to be moved proximally and anchored securely.

Aged↗
PubMed1987

Osteochondral disruption of the second metatarsal: a variant of Freiberg's infraction?

A case of Freiberg's Infraction of the second metatarsal is presented. The metatarsal head was resected and its pathology proved very informative. Necrotic bone was not found, but a shearing type of separation was identified at the level of "tidewater mark" in the articular cartilage and was the major observation. This suggested the possibility that in adults Freiberg's Infraction rather than true avascular necrosis may be in fact the result of a shearing-compression type of injury occurring at the interface between mineralized and nonmineralized articular cartilage (tidewater mark). An anatomical examination of metatarsophalangeal joints in cadavers showed that during walking at the "toe off" position, the toes dorsiflex to force the metatarsal head into plantar flexion. The proximal phalanges ride dorsally over the metatarsal heads producing a shearing force that would support our interpretation of the observations made in the case presented.

Ankle Injuries↗
PubMed1987

Complications of wire mesh in acetabular reconstruction.

Stainless steel wire mesh has been used for many years to reinforce acetabular cement. A case has been seen in which considerable corrosion and disintegration of the mesh were noted, with gross metallosis of the surrounding tissues. It is postulated that galvanic corrosion occurred between the stainless steel mesh and the cobalt chrome femoral prosthesis.

Acetabulum↗
PubMed1987

Major acetabulum reconstruction using autograft bone in cemented hip arthroplasty.

Acetabular wall deficiency is a relatively common problem in prosthetic hip arthroplasty. The authors have reviewed the results of acetabular reconstruction using autogenous bone grafts, either iliac wing or femoral head, in 49 cases in which a cemented acetabular component was employed. Thirty-one were primary cases, 15 revisions, and 3 ankylosed hips. The roof only was deficient in 20, the anterior wall in five, and the posterior wall in one. Fourteen had combined deficiencies and nine had total acetabular deficiency. Follow up ranged from three to eight years. The results have been reasonable with no graft absorption and no early acetabular component loosening. Failure of the femoral side in one case of total acetabular reconstruction at four years led to revision. The bone grafts were found to be united and had re-established a normal blood supply. It is concluded that autogenous bone grafting of the acetabulum is a reasonable procedure.

Acetabulum↗