Introduction: The revision of a resection arthroplasty of the hip to total hip arthroplasty is a demanding procedure with higher complication rates than those of primary hip arthroplasty.

Aim: To evaluate the outcome of revising resection arthroplasties and thereby assist in deciding which patients would benefit from the procedure.

Methods: We reviewed the experience of an orthopaedic surgeon (WJMB) who performed revisions of resection arthroplasties to total hip arthroplasties for 10 patients from 1990 to 1999. The reason for resection arthroplasty was established or suspected infection in all patients.

Results: The time since the resection arthroplasty ranged from 12 to 36 months, with an average of 14.7 months. The Harris hip scores with the resection arthroplasties ranged from 21 to 44 with an average of 38.3. The follow-up ranged from one to eight years with an average of 4.2 years. Five patients had died from other causes at the time of the study. The Harris hip scores at the latest follow-up ranged from 46 to 89 with an average of 66.

The complications included instability requiring a constrained acetabular liner, an intra-operative femoral fracture requiring a long-stem prosthesis, the breaching of a femoral cortex by a prosthesis requiring a revision and recurrence of infection in a patient who was non-compliant with the prescribed antibiotics.

Conclusions: The revision of a resection arthroplasty to a total hip arthroplasty is a demanding procedure with a high complication rate and prolonged recovery. Revising only those patients with poorly functioning resection arthroplasties optimises the possibility of a positive surgical outcome, being an improvement in pain and function.

Methods: Sixty pseudo-capsular tissues from loose shoulder, hip and knee (20 each) arthroplasties and 30 capsular tissues from primary total joint arthroplasty (TJA) patients (10 each; 12 rheumatoid arthritis [RA], 18 osteo-arthrosis [OA]) were investigated for mRNA and protein expressions of IL-1ß (interleukin-1 b, IL-1Ra (interleukin-1 receptor antagonist), MMP 1 (matrix matalloproteinase-1)-, TIMP 2 (tissue inhibitor of MMPs-2) using in situ hybridisation and immunohistochemistry. Polyethylene and metal debris in the same sections were semi-quantified simultaneously.

Results: IL-1ß mRNA and proteins were expressed in most RA primary and revision tissues and were less expressed in OA primary tissues. In contrast, IL-1Ra mRNA was found in most primary OA tissues and less in RA primary and the revision tissues. The ratio of staining intensities of IL-1ß/IL-1Ra mRNA was higher in revision and primary RA tissues compared with the primary OA tissues. MMP-1 protein expression was correlated with the IL-1ß/IL-1Ra ratio. Polyethylene (PE) debris was found in 56 out of 60 of the revision tissues. Their sizes were different in the hip (mainly small, < 30 mm in diameter), the knee (mainly large, > 300 mm) and the shoulder (all sizes). The expressions of the detected factors were highly correlated with the concentration of the PE debris but with not their sizes.

Conclusions: The high ratio of IL-1ß/IL-1Ra in primary RA and revision tissues and its correlation with MMP-1 expression and PE debris concentration indicated that an over-expression of IL-1ß and/or regulation downwards of IL-1Ra is an important event in inflammatory disorders and the foreign body reaction in TJA. A therapeutic strategy with IL-1Ra, that has been considered in RA treatment may thus contribute to the longevity of prosthesis of a TJA.

Introduction: Proximal bone resorption is a common problem after total hip arthroplasty. This has been attributed to stress shielding and has been reported to be more pronounced for cemented than for uncemented implants.

Aim: To investigate the cortical strain distribution of a new proximal “fit and fill” cementless, titanium, femoral, hip prosthesis based on the SROM design.

Methods: Strain gauges were mounted on five fresh-frozen cadaveric and five saw-bone femora and checked against a template for the prosthesis. The strain gauges were placed at four levels on the anterior, posterior, medial and lateral cortices corresponding to the Gruen zones. Two extra strain gauges were placed on the proximal posteromedial cortex. Loading was applied to the intact and reconstructed femora in the ISO 7206–4 orientation and single legged stance in an MTS servo-hydraulic testing machine. Data were analysed using analysis of variance.

Results: The strain distributions following reconstruction and multi-axis loading (ISO 7206–4 orientation) approximated the strains in an intact femur in the diaphysis. The proximal posteromedial cortical strains were approximately 50% of those of the intact femur.

Conclusions: The strains observed in the proximal femur following reconstruction in the present study are considerably higher than most others reported in the literature. A number of factors may contribute to the high proximal strains observed. This study has illustrated that geometric design and material selection along with surgical technique may allow for greater loading to proximal bone and enhance the long term integrity of this type of implant.

Purpose: To examine the histology of the bone cement interface in a canine total hip model comparing two different cementing techniques.

Methods: Seven adult mongrel dogs underwent staged bilateral total hip replacement, on one side cement was finger packed into the femur, on the opposite side the femoral canal was washed, brushed, distally plugged and pressure injected with cement prior to inserting the femoral component. Sequential flurochrome bone labelling was performed. The dogs were sacrificed up to six months post surgery. Under-calcified sections of the femur were examined by fluorescent microscopy.

Results: Post-operative radiographs showed complete filling of the proximal femur with cement in the pressure injected group, and a relatively thin mantle in the finger packed group. Histology of the finger packed group showed minimal intrusion of cement into the cancellous bed, direct opposition of cement and bone with small areas of fibrous tissue interposition. In the pressure injected group the cement extended to the endosteal cortex, there was no bone necrosis, and the intruded bone underwent remodelling similar to that at the margins.

Conclusions: This study suggests that “third generation” cementing techniques result in greater contact between bone and cement, and may explain the claim that femoral stems in humans inserted using third generation techniques are more durable than those inserted using “first generation” techniques.

Introduction: Spondylolysis is amongst the commonest causes of low back pain in the athletic child. We observed increased uptake in the pedicles of the affected segment and a triangular pattern of uptake in the sagittal projection of tomographic studies of fractures of the pars interarticularis. The hypothesis that these observations were specific for fractures of the pars interarticularis was tested in a variety of spinal disorders.

Methods:. A retrospective study of 25 young athletes with a variety of spinal disorders was undertaken (17males, 8 females; average age 13.5 years [range: nine to16 years]). The patients were referred from a specialised sports clinic. Back pain was present for an average of four months (Range six weeks to 11 months). All children had planar and tomographic scintigraphic bone scans with special reconstruction. The diagnosis was confirmed by radiological studies and/or response to treatment.

Results:. All 15 children with spondylolysis had evidence of increased uptake in the ipsilateral (12/15) or contra-lateral pedicle (3/15). None of the cases of muscle insertion injury, facet joint or disc disease demonstrated this pattern. A triangular shaped pattern of uptake was only seen in the sagittal view of the tomographic studies in patients with fractures of the pars interarticularis.

Conclusion:. We have described two unique features of spondylolysis that add to the confidence with which the scintigraphic diagnosis may be made.

Introduction: Labelled leukocyte scintigraphy has been shown to be a sensitive and specific technique for the detection of pedal osteomyelitis in patients with diabetes mellitus. There has however been little data relating the efficacy of the technique to outcomes.

Aim: To examine the prognostic value of sequential 99m Tc labelled leukocyte scans at diagnosis and after 3–4 weeks of appropriate antibiotic therapy.

Method: Twenty-three patients with proven pedal osteomyelitis or persistent uptake on the sequence of scans were studied.

Results: Five additional episodes of osteomyelitis developed in the group over the period of the study. Eleven patients demonstrated persistent uptake in the sequential scans. Nine progressed to amputation. The remaining two patients were biopsy negative for infection, did not have cutaneous ulceration and were thought to have rapidly progressive arthropathy.

Conclusion: Sequential leukocyte scintigraphy accurately predicted the need for amputation and circumvented ineffective prolonged antibiotic therapy.

Introduction: Hip instability is a complex and challenging problem. In experienced units, up to 4% of patients undergoing total hip arthroplasty will require revision surgery to treat hip instability, with only 60% of these treatments being successful. Many authors reporting results with various constrained systems available have described dislocation rates post implantation of the constrained component of 4% to 29%.

Method: The thirteen patients who underwent placement of a constrained component as a revision procedure in our unit from 1989 to 2000 were reviewed.

Results: The indications for revision surgery included recurrent dislocation in eight and intraoperative instability in five revision hip arthroplasties. No patients were lost to follow up. The average follow-up was 43 months(range 14 to 121). The average age at time of surgery was 73 years(range: 52 to 84 years). No component has been revised. The average hip score after revision surgery was 72(range: 52 to 89). There have been no episodes of dislocation of the constrained arthroplasty. In seven cases the constrained arthroplasty was implanted into a previously placed well fixed shell.

Conclusion: Constrained acetabular components were a highly effective tool in the treatment of hip instability.

Aim: To examine the histology of the bone-cement interface in a canine total hip model comparing two different cementing techniques.

Method: Seven adult mongrel dogs underwent staged bilateral total hip replacement. On one side the cement was packed into the femur with a finger while on the opposite side the femoral canal was washed, brushed, distally plugged and injected with cement under pressure before inserting the femoral component. Sequential fluorochrome bone labelling was performed. The dogs were sacrificed up to six months after the surgery. Undecalcified sections of the femur were examined by fluorescent microscopy.

Results: Post-operative radiographs showed complete filling of the proximal femur with cement in the pressure injected group, and a relatively thin mantle in the finger-packed group. Histology of the finger-packed group showed minimal intrusion of cement into the cancellous bed, direct apposition of cement and bone with small areas of fibrous tissue interposition. In the pressure- injected group the cement extended to the endosteal cortex, there was no bone necrosis, and the intruded bone underwent remodelling similar to that at the margins.

Conclusions: This study suggested that ‘third generation’ cementing techniques result in greater contact between bone and cement, and may explain the claim that femoral stems in humans inserted using third generation techniques are more durable than those inserted using ‘first generation’ techniques.