Background

Total hip arthroplasty (THA) is increasingly used for active patients with displaced intracapsular hip fractures. Dislocation rates in this cohort remain high postoperatively compared to elective practice, yet it remains unclear which patients are most at risk. The aim of this study was to determine the dislocation rate for these patients and to evaluate the contributing patient and surgeon factors.

Purpose of study: With the increasing demand for arthroplasty surgery, it is important to maintain a high quality of care. We describe a clinical governance framework for monitoring radiological outcome following total hip arthroplasty.

Methods: We completed a two-year prospective study (January 2006 to December 2007 inclusive) of all total hip arthroplasty operations. This included 1,143 procedures, the majority of which were undertaken by three Consultant Surgeons and four independent middle grade surgeons. The three Consultant Hip Surgeons assessed component position on post-operative weight-bearing anteroposterior pelvic/hip radiographs on a weekly basis. They were blinded to both the patient and surgeon details, and used our own simple grading system. Weighted Kappa variance showed substantial interobserver (kappa = 0.60) and intraobserver reliability (kappa = 0.92). Our system comprised of only three ordinal scores, which were ‘good’ (score of 1), ‘acceptable’ (score of 2) and ‘poor’ (score of 3).

Results: We provided individual surgeons with their results on a six-monthly basis. The average score for all the surgeons was ‘good’. The scores of the independent middle-grade surgeons were analysed by the Consultants, and feedback was provided in the form of formal advice and supervised surgery sessions. Repeat analysis of their radiological scores showed significant improvements for certain individual surgeons (Pearson-Chi Square p value 0.006)

Conclusions: Clinical governance is an important facet of excellence in medical practice. Our system allows continued prospective assessment of radiological outcome following total hip arthroplasty. By utilising such systems and ensuring an atmosphere of clinical excellence, we are able to employ more surgeons and undertake an increased workload, whilst maintaining high standards. This assessment tool can also be used to appraise trainees during their progression.

Variability in femoral head preparation and high cement pressures may be associated with failure to seat femoral components during hip resurfacing. Furthermore, excessive pressures may lead to over penetration of bone by cement with resulting necrosis of the underlying bone. We designed an experimental model to test the hypothesis that partial-length pressure-relief slots made longitudinally in the proximal bone of the femoral head, without extending to the head neck junction, would allow controlled leakage of cement during initial insertion of a femoral head resurfacing component, but would then become sealed during final insertion to prevent excessive loss of cement while still allowing accurate seating of the component.

Thirty-one resurfacing femoral components were cemented onto foam femoral head models. The clearance between foam model and implant was measured to determine the minimum space available for cement. Eleven components were inserted using hand pressure alone, 20 were hammered. Pressure relief slots were prepared in 10 femoral heads. The slots, 4mm deep grooves, were made in the proximal bone only, without extending to the head-neck junction. Cement pressure inside the component was measured during insertion. Implants were sectioned after implantation in order to determine whether they had been fully seated or not. The clinical relevance of the measures taken was tested by measuring the diameter of prepared femoral heads during 20 hip resurfacing operations in order to determine the extent of variability in intra-operative femoral head preparation.

Mean intraoperative clearance between bone and implant was −0.19mm (0.11 to −0.93mm). Mean clearance between foam model and implant was −0.30mm (0.35 to −0.94mm). Full seating was obtained in 22/31 components. Of those not fully seated, all had clearance less than −0.74mm. Full seating with a clearance of less than −0.35mm was only possible when pressure relief slots had been made in the femur. The use of a pressure relief slot longer than half the femoral head length allowed full seating in 9/9 cases, compared to 13/22 without. Cement pressure obtained with a hand pressure technique was less than half that observed with hammering (20.8vs56.0psi, p=0.0009) but was not associated with failure to seat the implant if a slot was used.

Variability of the actual diameter of the femoral head prepared may be associated with difficulty in fully seating resurfacing components. The same degree of variability in the space available for cement was observed in both intra-operative and test specimens. The use of a pressure-relief slot allows full seating of resurfacing implants with hand pressure alone, thereby halving cement pressure, in an experimental model, even when clearance between implant and bone is less than optimal.

Introduction: It is well known that the integrity of the bone cement interface is crucial for the long-term survival of a primary total hip arthroplasty (THR). Revision THR with impaction bone grafting has recently offered a solution to gross bone loss due to osteolysis. As graft becomes incorporated, clearly the bone graft/ cement interface is as crucial as the equivalent interface in primary THR. Our aim was to examine factors that inßuence this interface. Method: The study was designed to mimic clinical practice. Fresh femoral heads were harvested from primary THR. These were morcelised into large and small particles. These were characterised. The bone was impacted into a purpose built jig with measured force. Cement was pressurised onto the dried surface of the impacted bone after measured mixing times. Cement pressurisation was measured. The cement/graft specimen was extracted and transected with a band saw. Cement penetration was measured with digital image analysis. Results: Large fragment size was 29 mm², and small was 7.1mm². Light impaction was 2.2 Atm. Medium and heavy were 2.6 Atm. and 3.2 Atm. respectively. Cement penetration was inversely proportional to impaction force. Cement mixing time also signiþcantly affected cement penetration. Particle size had no effect. Conclusion: Allograft should be adequately but not excessively impacted, to allow good cement incursion. Cement should be introduced and pressurised perhaps as early as two minutes. Fragment size does not affect cement penetration.

Objective: To assess the early results of the TC3 total knee prosthesis, a modular system with stems and augments, in difficult primary and revision knee arthroplasties.

Method: 13 index procedures were undertaken for gross varus or valgus deformities with severe ligamentous incompetence and/or major bone defects. 18 procedures were revision arthroplasties, 7 being undertaken for sepsis.

29 knees underwent full clinical and radiological review, using the Hospital for Special Surgery Score (HSS) and the Knee Society Score.

One patient was interviewed by phone with recent radiological follow-up. One patient died of unrelated causes.

Results: All patients were very pleased with the outcome of surgery. The mean pre-operative alignment for primary arthroplastles was 280 of varus and 320 valgus. The mean post-operative alignment was 70 valgus. The mean post-operative HSS was 72.4 for primary procedures and 72.7 for revision surgery. The mean Knee Society Knee Score was 77.9 for primary and 75.1 for revision surgery, and the mean function score was 60.8 for primary and 49.4 for revision surgery. The latter reflects the elderly age, multiple joint involvement and constitutional status (including rheumatoid arthritis) of many of these patients.

Conclusion: The TC3 knee system affords an excellent modular option to compensate for bone defects and ligamentous incompetence, achieving restoration of the joint line and satisfactory function in a very disabled group of patients.