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.

Metal-on-metal (MoM) hip resurfacing was developed in the 1990s by surgeons in Birmingham, UK, as a surgical solution to the problem of osteoarthritis in younger, more active patients. Early results were promising and the procedure gained in popularity. However, adverse reports of soft-tissue reaction and failure started to appear from 2008 onwards. Surgeons may be asked to write medico-legal reports on the surgical aspects of an individual case for claimant lawyers or in defence for the NHSLA or indemnity insurers. The purpose of this article is to cover some of the aspects of the operation that may be considered in such medico-legal reports.

Deficiency of the abductor mechanism is a well-recognised cause of pain and limping after total hip replacement (THR). This can be found incidentally at the time of surgery, or it may arise as a result of damage to the superior gluteal nerve intra-operatively, or after surgery owing to mechanical failure of the abductor muscle repair or its detachment from the greater trochanter. The incidence of abductor failure has been reported as high as 20% in some studies. The management of this condition remains a dilemma for the treating surgeon. We review the current state of knowledge concerning post-THR abductor deficiency, including the aetiology, diagnosis and management, and the outcomes of surgery for this condition.

Cite this article: Bone Joint J 2013;95-B:343–7.

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.

We have examined 26 retrieved, failed titanium-alloy femoral stems. The clinical details, radiological appearances and the histology of the surrounding soft tissues in each patient were also investigated.

The stems were predominantly of the flanged design and had a characteristic pattern of wear. A review of the radiographs showed a series of changes, progressive with time. The first was lateral debonding with subsidence of the stem. This was followed by calcar resorption and fragmentation or fracture of the cement. Finally, osteolysis was seen, starting with a radiolucency at the cement-bone interface and progressing to endosteal cavitation.

Three histological appearances were noted: granulomatous, necrobiotic and necrotic. We suggest that an unknown factor, possibly related to the design of the stem, caused it to move early. After this, micromovement at the cement-stem interface led to the generation of particulate debris and fracture of the cement. A soft-tissue reaction to the debris resulted in osteolysis and failure of fixation of the prostheses.

The results are reported of an audit of allografts collected in the first 18 months of the Leicester Bone Bank. We retrieved 161 femoral heads at primary arthroplasty of which 103 were implanted into 59 patients. There were deep infections in two recipients and wound infections in five. In two of these cases, culture of the femoral head at implantation was positive but the organisms grown were not those which caused the clinical infection. We retrieved 22 large allografts from six cadavers. Four of these were contaminated at retrieval and required irradiation for sterilisation. There has been one clinical infection in the nine large allografts implanted so far. We recommend that all bone banks undertake prospective audit to ensure that high standards are maintained and wastage minimised.