The viability of the femoral head after resurfacing hip arthroplasty in humans.

Histologic examination of 72 femoral heads retrieved at revision of resurfacing arthroplasties was performed to determine the possible role of generalized osteonecrosis caused by avascular necrosis (AVN) in early loosening of the femoral components. The degree of loosening at the femoral bone-cement interface was correlated with the histologic appearance of the femoral heads. None of the ten femoral heads with solid femoral components and only one of the 15 heads with slight loosening showed evidence of generalized osteonecrosis. The one case might have been attributable to AVN after the resurfacing procedure. In the remaining femoral heads with marked loosening of the femoral component, necrosis of bone was uncommon. When present, it was attributed to loosening. Thickening of bone trabeculae, a fibrovascular marrow, and superficial necrosis of bone of the femoral head are not evidence of generalized AVN caused by the resurfacing arthroplasty procedure, but are the result of remodeling changes and subsequent loosening.

Peripheral wear of Wagner resurfacing hip arthroplasty acetabular components.

One hundred nine Wagner resurfacing arthroplasty acetabular components retrieved at revision surgery were examined for type, depth, and extent of wear at the periphery of the components. Ninety-two components were found to have evidence of peripheral wear caused by impingement of the femoral neck on the edge of the component. The thickness of the wall loss due to this impingement wear was found to be less the farther that measurements were taken from the edge of the component. Thus, when those components with any evidence of impingement wear were analyzed, it was found that significantly fewer components had evidence of impingement at depths of 3 mm and 5 mm in from the edge of the component. It is suggested that future designs of resurfacing hip arthroplasty acetabular components should be at least 3 mm and possibly 5 mm less than a hemisphere. This is likely to lead to less impingement on the femoral neck and therefore less cause for mechanical loosening and less production of wear debris.

Pseudo-abscess of the psoas bursa in failed double-cup arthroplasty of the hip.

Seven psoas bursae filled with purulent fluid and inspissated debris were revealed at revision operations for failed resurfacing hip arthroplasties, an incidence of 5.8% in such revisions. Histological and microbiological investigations demonstrated that the psoas bursa collections resulted from the tissue response to polyethylene wear debris. None was due to infection.

Resurfacing hip arthroplasty. Classification of loosening and the role of prosthesis wear particles.

Operative grading of loosening and histologic examination of the periprosthetic tissues and the femoral and acetabular bone-cement interfaces were undertaken in 72 revised resurfacing hip arthroplasties. By correlating the degree of macroscopic and microscopic loosening at the bone-cement interface, a classification of the stages of loosening at the bone-cement interface was devised. Examination of the femoral bone-cement interface of solidly fixed prosthesis components has demonstrated the presence of polyethylene wear particles and a macrophage response at the interface prior to loosening. This suggests that wear particles may migrate along bone-cement interfaces that are both macroscopically and microscopically solid, and emphasizes the important role of wear particles in prosthesis loosening.

Wagner resurfacing hip arthroplasty. The results of one hundred consecutive arthroplasties after eight to ten years.

In a prospective study of 100 consecutive Wagner resurfacing hip arthroplasties in ninety-three patients, the outcomes for all hips were determined for an eight to ten-year follow-up period. By survivorship analysis, the rate of survival of the arthroplasty was calculated to be 70 per cent at five years, but only 40 per cent at eight years. The major cause of failure was aseptic loosening of the acetabular or femoral component, or both. Fracture of the neck of the femur occurred in three hips. Although the medium-term results (at fifty-six to eighty-three months) were better than those in most comparable studies of resurfacing arthroplasty, the poor long-term results (at ninety-one to 118 months) show that meaningful studies of new prosthetic designs must continue for at least eight years, and, if at all possible, must include 100 per cent follow-up. The survival curve for the resurfacing arthroplasties in this study can serve as the basis for comparison of the early, medium, and long-term results of future designs of resurfacing hip prostheses.

Fractures and fractures-dislocations of the lumbar spine. A retrospective study of 70 patients.

A retrospective study was undertaken to analyse and compare the results of Harrington instrumentation with postural reduction and nursing in patients with fractures and fracture-dislocations of the lumbar spine. Thirty patients were treated by postural reduction and nursing, and 38 underwent early surgical reduction and internal fixation with Harrington instrumentation, together with a posterior fusion in three patients and an anterior fusion at the level of the fracture in another two patients. External splintage was used in only one patient in the series. At an average follow up of 5.9 years, bony deformity quantified by angulation, displacement and the vertebral wedge index was greater in the conservative group than in the group treated surgically. No significant difference was observed in comparing the rates of neurological recovery in the two groups. At follow up, patients with no symptoms had less severe bony deformity. Loss of fixation of Harrington instrumentation occurred in 46% of patients treated by this method. The incidence of other complications was not significantly different in the two groups. Despite the unacceptably high rate of local complications, Harrington instrumentation achieved better correction of bony deformity than postural reduction and nursing, prevented progression of deformity and decreased the incidence of symptoms at follow up. This study indicates that in these injuries bony deformity can be satisfactorily corrected by early Harrington instrumentation alone, without spinal fusion and bracing, provided an exacting surgical technique is employed.

Osteoid osteoma transforming to aggressive (low grade malignant) osteoblastoma: a case report and literature review.

The authors report a case of a typical osteoid osteoma which recurred soon after initial surgery and underwent rapid growth. The tumour eventually showed features of aggressive behaviour with local metastasis. The findings are compared with those of seven previously described benign osteoblastic tumours which showed subsequent aggressive behaviour.