Introduction: Pre-operative templating helps the operating surgeon to accurately choose optimal implant size. In the past analog images have been templated with the help of acetate templates. With the introduction of Picture Archive and Communications Systems (PACS) digital software is now available. We would like to present preliminary results of an ongoing prospective study investigating the accuracy of digital templating compared to actual implant size in primary hip arthroplasty.

Methodology: The senior author pre-operatively templated implant size using the TraumaCad (Orthocrat limited, Israel). Images were saved and displayed using the web based PACS system RADIN (RADIN 3.2, SoHard AG, Germany). All patients undergoing primary hip replacement surgery were included in the study. Patients with significant collpase of the acetabulum or femoral head needing additional reconstruction were excluded. Hips were templated using radiographs calibrated against a spherical metal ball. For each hip, an AP pelvis view was used. Acetabular implants used were either Trident PSL or Exeter contemporary cup (Stryker). Femoral stem was Exeter (Stryker). Predicted implant sizes were documented. Operation was performed by the senior author or under his supervision using the posterior approach. Postoperatively, the predicted implant size was compared to the implanted components.

Results: 18 consecutive primary total hip arthroplasties were templated. The differences between digital and actual sizes were plotted against their mean in Bland- Altman plot. The 95% confidence interval of the differences between digital and actual sizes were ± 4mm (±2 sizes) for acetabluar cup, ±1 mm (± ½ size) for femoral stem and ± 6mm (±1 size) for offset. All postoperative films showed good fit of components and there were no intraoperative or postoperative fractures.

Discussion: Our data indicate that digital templating is reliable in predicting actual implant sizes for total hip arthroplasty. We hope to present a larger series in the meeting.

Introduction: The possibility of occult hip fracture in older patients after a fall is a common problem. The value of various clinical signs to determine which patients require further investigation has not been reported.

Methodology: MRI register was hand searched to identify all patients who had MRI scan between July 2000–June 2006 for suspected occult hip fracture. 64 patients were identified. 33 patients had occult proximal femoral fractures. 27 patients had no fracture.

Results: More patients with fracture were living in their own home (20/26), were independent for daily living (20/26) and were not independently mobile(19/26) compared to patients without a fracture (14/22, 11/22 and 6/22 respectively). 7 patients with fracture and 2 patients without fracture were able to weight bear. 13 patients with fracture and 10 patients without fracture had unrestricted straight leg raise ability. 7 patients with fracture and 16 patients without fracture had no pain on axial loading. The value of individual tests was evaluated using Fisher exact and chi square analysis; with Bonferroni correction for multiple comparisons (10 tests) p< 0.005 was deemed significant. Pain on axial loading of the limb and pre-fracture patient mobility were both associated with the presence of a fracture (p< 0.005).

Discussion: These data indicate that although patients who were independently mobile before the fall and who do not have pain on axial compression of the limb are less likely to have a fracture, these signs alone or in combination will not exclude a fracture. Other widely used signs (eg ability to straight leg raise) appear of little predictive value. On the basis of our data, we believe it is essential to have a policy of MRI scanning of patients with severe hip pain but normal x rays after a fall as it does not seem possible to clinically exclude a fracture.

Introduction: Rapidly destructive arthrosis of the hip (RDHD) is a rare and incompletely understood disorder with scarce literature about variations in natural history within a population. A series of cases from North Wales with rapid progressive joint destruction and extensive subchondral bone loss in the femoral head and acetabulum are presented.

Methods: A retrospective review of patients with a clinical profile and serial radiographs suggestive of a rapidly progressive hip disease was undertaken. This revealed 15 patients who met our criteria for RDHD. A retrospective analysis of clinical and radiographic records was performed. Radiographic findings mimicked those of other disorders such as septic arthritis, rheumatoid and seronegative arthritis, primary osteonecrosis with secondary osteoarthritis, or neuropathic osteoarthropathy, but none of the patients had clinical, pathologic, or laboratory evidence of these entities.

Results: Rapid progression of hip pain and disability was a consistent clinical feature. The average duration of symptoms was 1.4 years. Radiographs obtained at various intervals before surgery (average 14 months) in 15 patients documented rapid hip destruction, involvement being unilateral in 10 cases. All patients underwent total hip arthroplasty, and osteoarthritis was confirmed at pathologic examination. Histology of femoral heads failed to show the findings typical of primary osteonecrosis & no evidence of sepsis.

Discussion: The authors postulate that these cases represent an uncommon subset of osteoarthritis and regular review, both clinically and radiologically, are required to assess speed of progression and prevent rapid loss of bone stock without the surgeon being aware. These cases are unsuitable for being placed on long waiting list due to technical difficulties in delayed surgery and compromised outcome following surgery. The decisions about the need for surgery and the selection of cases should be made purely on clinical grounds and not on their rank in the waiting lists.(295)