Biomedical subjects

R D Oakeshott

Publications and source records attributed to R D Oakeshott.

12 recordsLinked to original sources

PubMed2006

Development rationale for an articular surface replacement: a science-based evolution.

Hip resurfacing has an enduring appeal because of the advantages of bone conservation and maximal joint stability. However, a far from satisfactory experience with earlier resurfacing designs led to its virtual disappearance in the 1980s. The concept was reintroduced in the late 1990s. The current generation of resurfacing devices generally consisted of a large-diameter metal-on-metal articulation, the femoral components being cemented and the acetabular components utilizing various forms of cementless fixation. The encouraging medium-term results, with a follow-up of up to 8 years using the current generation of surface replacement joints, combined with favourable reports related to long-term performance of some metal bearings have led to a rapid increase in the use of such components with these devices. This trend is most marked in younger, more active patients who have expectations of restoration of lifestyle in addition to improved mobility and pain relief and in whom failure with conventional total hip replacement is much higher than previously reported with more sedentary patients. The aim of this paper is, firstly, to highlight a number of areas of improvement and, secondly, to explain how these may be addressed by making modifications to the design of both implants and instrumentation and to the surgical technique. The areas identified for improvement were tissue preservation (thinner components, and reduced steps between sizes), acetabular cup issues (fixation, insertion, and positioning), femoral component issues (design, loading, and cementation), improved bearing surface characteristics, and simplified precise instrumentation with a low-trauma surgical technique.

Arthroplasty, Replacement, Hip↗

PubMed2006

A retrospective comparative study of bilateral total knee replacement staged at a one-week interval.

The clinical results of bilateral total knee replacement staged at a one-week interval during a single hospital admission were compared with bilateral total knee replacements performed under the same anaesthetic and with bilateral total knee replacements performed during two separate admissions. The data were retrospectively reviewed. All operations had been performed by the same surgeon using the same design of prosthesis at a single institution. The operative time and length of stay for the one-week staged group were comparable with those of the separate admission group but longer than for the patients treated under one anaesthetic. There was a low rate of complications and good clinical outcome in all groups at a mean follow-up of four years (1 to 7.2). The group staged at a one-week interval had the least blood loss (p = 0.004). With appropriate patient selection, bilateral total knee replacement performed under a single anaesthetic, or staged at a one-week interval, is a safe and effective method to treat bilateral arthritis of the knee.

Adult↗

PubMed2005

Hip joint range of motion reduction in sports-related chronic groin injury diagnosed as pubic bone stress injury.

Traumatic osteitis pubis is a non-specific entity that relates to chronic groin injury and has recently been described as being akin to a pubic bone stress injury. It is uncertain whether or not reduction of hip joint range of motion occurs in traumatic osteitis pubis. The purpose of this study was to establish whether there is a reduction of hip range of motion in athletes who have chronic groin injury diagnosed as pubic bone stress injury. A case-control study was performed whereby 89 Australian Rules footballers underwent, with clinical history unknown, clinical and MRI examination of the groin region. Clinical criteria (pain with tenderness) and MR-criteria (pubic bone marrow oedema) were used for diagnosis of pubic bone stress injury. End-range internal and external rotation hip motion was measured using a goniometer. Athletes with and without symptoms were compared, as were athletes with current symptoms with athletes who had recovered from their groin pain episode. Chronic groin injury was diagnosed in 47 athletes with 37 having pubic bone stress injury. Thirteen athletes had previous groin injury. A reduction of internal and external hip range of motion was demonstrated in athletes with pubic bone stress injury (p < 0.05) and in athletes who had current symptoms compared to those who had recovered from their groin pain episode (p < 0.05). A reduction in hip range of motion was evident in athletes with chronic groin injury diagnosed as pubic bone stress injury. There may be a role for increasing hip range of motion in rehabilitation.

Athletic Injuries↗

PubMed1996

Human immunodeficiency virus infection of human bone derived cells.

Human immunodeficiency virus infection of a human bone derived cell line was initiated by either cell free virus or with a cell to cell transmission method. The human bone derived cells were examined for 8 weeks, and virus infection was not detected when assessed by microscopy, immunofluorescence, reverse transcriptase activity, or infection of cocultivated human T lymphoid cells susceptible to human immunodeficiency virus. Polymerase chain reaction analysis of human bone derived cells inoculated with the cell to cell infection format showed less than 0.1% infected cells. It is possible that the infected cells detected by polymerase chain reaction were lymphocytes used in the cell to cell infection format. Alternatively, latent infection may have been established in the bone derived cells with no apparent expression of the proviral genome. A large proportion of bone is represented by human bone derived cells, and it is unlikely that bone will contribute to a significant human immunodeficiency virus reservoir in vivo. The blood of bone allograft donors is likely to have a greater virus bioburden than is bone. Methods to sterilize bone should be assessed by their efficacy to inactivate the virus in blood contaminating the graft, and methods to detect human immunodeficiency virus deoxyribonucleic acid in a bone graft may be less sensitive than examining the donor's blood.

Cell Line↗

PubMed1996

HIV infection of human cartilage.

Infection of human cartilage with HIV in vivo has not previously been reported. Specimens of articular cartilage taken at postmortem from ten patients who were HIV-positive were examined. Two had AIDS and eight were believed to have stage-2 disease. The standard polymerase chain reaction (PCR) protocol was modified to allow semiquantitative analysis of the samples. Oligonucleotide primers labelled with 32P gamma-ATP were used to detect a segment of HIV DNA and a control DNA gene segment (HLA genome) to estimate the ratio of infected cells. The 32P-labelled PCR products were separated on acrylamide gels and visualised directly by autoradiography and computer densitometry. Infection of human cartilage in vivo was demonstrated in nine of the ten samples in which the PCR analysis was positive. The other did not react sufficiently to produce detectable radiolabelled PCR product despite repeated DNA digestion and extraction. Cartilage infected with HIV could be a potential source of HIV when used in operations.

Acquired Immunodeficiency Syndrome↗

PubMed1995

Bone allograft banking in South Australia.

The South Australian Bone Bank had expanded to meet an increased demand for allograft bone. During a 5 year period from 1988 to 1992, 2361 allografts were harvested from 2146 living donors and 30 cadaveric donors. The allografts were screened by contemporary banking techniques which include a social history, donor serum tests for HIV-1, HIV-2, hepatitis B and C, syphilis serology, graft microbiology and histology. Grafts were irradiated with 25 kGy. The majority of grafts were used for arthroplasty or spinal surgery and 99 were used for tumour reconstruction. Of the donated grafts 336 were rejected by the bank. One donor was HIV-positive and two had false positive screens. There were seven donors with positive serology for hepatitis B, eight for hepatitis C and nine for syphilis. Twenty-seven grafts had positive cultures. Bone transplantation is the most frequent non-haematogenous allograft in South Australia and probably nationally. The low incidence of infectious viral disease in the donor population combined with an aggressive discard policy has ensured relative safety of the grafts. The frequency of graft rejection was similar to other bone banks but the incidence of HIV was lower.

Acquired Immunodeficiency Syndrome↗

PubMed1994

Sterilization of HIV by gamma irradiation. A bone allograft model.

A human immuno-deficiency virus (HIV) infected bone allograft model has been created using HTLV-IIIB virus in a concentration simulating a massively HIV infected bone allograft donor [HTLV-III is the denomination initially given to the human immuno-deficiency by the american team of Prof. Gallo. It represent the virus HIV 1 of the present international nomenclature]. 5 x 10(4) tissue culture infective doses per ml. of virus were placed within the medullary cavity of bovine femora and tibiae with a radiation dosimeter, and the ends sealed with lead. The bone/virus model was maintained at -70 degrees C while being irradiated with 1 to 4 megarads of gamma irradiation in increments of 0.5 megarads. The study showed that the HTLV-IIIB virus is a relatively radio-resistant organism, a property common to most viruses. The results suggest that HTLV-IIIB can be inactivated in bone infected with a clinically significant viral load, as may be found in donors who are initially negative when screened for HIV. It is recommended that bone allografts which are secondarily sterilized by gamma irradiation receive at least 2.5 megarads. The amount of radiation absorbed by the bone cortex was minimal.

Animals↗

PubMed1993

Revision arthroplasty of the proximal femur using allograft bone.

Revision arthroplasty of the hip may require restoration of bone stock on the femoral side to provide bone support for the new implant and restore anatomy and leg length. Large cortical defects can be reconstructed best with allograft bone because of the quality and quantity of the bone required. In this article, the surgical technique and results of cortical allograft as full circumferential and cortical strut grafts are presented.

Adult↗

PubMed1990

Recurrent osteoid osteoma. Case report with a ten-year asymptomatic interval.

Osteoid osteoma has been accepted as a distinct clinical and pathologic entity for more than 50 years. Surgical curettage will often cure the lesion, although en bloc excision is now the preferred treatment. The development of local recurrence after surgery, although rare, has been well documented after both curettage and en bloc excision. Symptomatic recurrence of an osteoid osteoma was seen ten years after surgical curettage. Its occurrence at the same site as the original lesion is consistent with the concept that it had originated from residual tissue and is in keeping with the concept of osteoid osteoma as a benign tumor.

Bone Neoplasms↗

PubMed1988

A clinical and histologic analysis of failed fresh osteochondral allografts.

Fresh small osteochondral allografts were implanted in 108 patients. A clinical and histologic analysis was undertaken in 18 patients whose grafts failed and were excised. Twelve of these patients had evidence of viable hyaline cartilage despite adverse conditions. If careful attention is given to patient selection, age, appropriate timing for correction of alignment, and meticulous technique associated with graft positioning, size, and thickness, then the incidence of clinical failure should be minimized.

Adolescent↗

PubMed1987

Revision total hip arthroplasty with osseous allograft reconstruction. A clinical and roentgenographic analysis.

One hundred twelve irradiation-sterilized, -70 degrees frozen allografts have been used in 72 patients who were available for follow-up study in a prospective analysis of allograft revision total hip arthroplasty. Clinical objectives were achieved in 85% of patients with a follow-up period ranging from six to 72 months. Based on clinical and roentgenographic analysis, specific recommendations are made to further improve the success rate of revision total hip arthroplasty associated with protrusio, shelf, acetabular, calcar, and large fragment femoral allografts.

Acetabulum↗

PubMedDate not supplied

Radiographic changes in the knee after meniscal transplantation. An experimental study in a sheep model.

Meniscal transplantation has been suggested as an alternative to total meniscectomy, which is now known to lead to long-term osteoarthritic degeneration of the knee joint. To evaluate the success of meniscal transplantation, we divided 28 sheep knees into 4 groups: total meniscectomy, allograft, autograft, and control. After a mean postoperative time of 21.4 months, we radiographed the excised knee joints in a loaded state and graded the radiographs for osteoarthritic changes. The knees with meniscectomies, allografts, and autografts showed significantly more degenerative changes than the control knees. However, there were no statistically significant differences between these three groups. The results of this study suggest that meniscal allograft transplantation does not protect the knee against degenerative changes.

Animals↗