When removing femoral cement in revision hip surgery, creating an anterior femoral cortical window is an attractive alternative to extended trochanteric osteotomy. We describe our experience and evolution of this technique, the clinical and radiological results, and functional outcomes.

Between 2006 and 2021 we used this technique in 22 consecutive cases at Whanganui Hospital, New Zealand. The average age at surgery was 74 years (Range 44 to 89 years). 16 cases were for aseptic loosening: six cases for infection.

The technique has evolved to be more precise and since 2019 the combination of CT imaging and 3-D printing technology has allowed patient-specific (PSI) jigs to be created (6 cases). This technique now facilitates cement removal by potentiating exposure through an optimally sized anterior femoral window.

Bone incorporation of the cortical window and functional outcomes were assessed in 22 cases, using computer tomography and Oxford scores respectively at six months post revision surgery. Of the septic cases, five went onto successful stage two procedures, the other to a Girdlestone procedure.

On average, 80% bony incorporation of the cortical window occurred (range 40 −100%). The average Oxford hip score was 37 (range 22 – 48). Functional outcome (Oxford Hip) scores were available in 11 cases (9 pre-PSI jig and 2 using PSI jig). There were two cases with femoral component subsidence (1 using the PSI jig).

This case series has shown the effectiveness of removing a distal femoral cement mantle using an anterior femoral cortical window, now optimized by using a patient specific jig with subsequent reliable bony integration, and functional outcomes comparable with the mean score for revision hip procedures reported in the New Zealand Joint Registry.

Abstract

Objectives

To study the vascularity and bone metabolism of the femoral head/neck following hip resurfacing arthroplasty, and to use these results to compare the posterior and the trochanteric-flip approaches.

We investigated the blood flow to the femoral head during and after Resurfacing Arthroplasty of the hip.

In a previous study, we recorded the intra-operative blood flow in 12 patients who had a posterior approach to the hip and 12 who had a trochanteric flip approach. Using a LASER Doppler flowmeter, we found a 40% drop in blood flow in the posterior group and an 11% drop in the trochanteric flip group (p<0.001). The aim of this current study was to find out whether the intra-operative fall in blood flow persists during the post-operative period.

We therefore conducted a Single Positron Emission Tomography (SPECT) scan on 14 of the same group of patients. The proximal femur was divided into four regions of interest. These were the mid-shaft, proximal shaft, inter-trochanteric and head-neck regions. The data was analysed for bone activity and comparisons made between the two groups for each region of the femur. We found that the bone activity in the mid-shaft, upper-shaft, and head-neck regions was the same eleven months after the surgery irrespective of the approach to the hip. However there was higher activity in the trochanteric flip group in the inter-trochanteric region.

We conclude that the intra-operative deficit in blood flow to the head-neck region of the hip associated with the posterior approach does not seem to persist in the late post-operative period. We believe the reason for increased bone activity in inter-trochanteric region to be due to the healing of the trochanteric flip osteotomy.

Thirty-five patients were followed prospectively from their referral to the Problem Fracture Service with chronic osteomyelitis of diaphyseal bone between November 1994 and June 1999.

The patients were treated using a closed double-lumen suction irrigation system following reaming and arthroscopic debridement of the intramedullary canal; this is a modified system based on the work of Charles Lautenbach. Results of these procedures were regularly followed up in clinic, and between June and July 2007 the whole cohort was reviewed via postal questionnaire, telephone and case note review.

At a mean follow up of 101 months, 26 were living with no evidence of recurrence, 4 had died of unrelated causes with no evidence of recurrent infection. Four patients had persisting problems with sinus discharge requiring intermittent antibiotic therapy and 1 patient had his limb amputated for recurrent metaplastic change.

These results gave this cohort an 86% clearance of infection, with recurrence in 12%, which is comparable to the Papineau and Belfast techniques with significantly less surgical insult to the patient.

Antibiotic-associated Clostridium difficile diarrhoea may complicate surgery for proximal femoral fracture. We undertook a 4 year case control study to evaluate the effects of a change in antibiotic prophylaxis in our department.

In the period January 2003 to January 2005, patients received three doses of cefuroxime (1.5 g). The new regimen is a single dose of cefuroxime (1.5 g) with gentamicin (240 mg) at induction. Prior to the change in prophylaxis, 912 patients underwent surgery for neck of femur fracture. Following the change, 899 patients underwent surgery over the period March 2005 to March 2007. 38 patients developed C. difficile infection (4.2%) in the initial group, compared with 14 patients (1.6%) in the group following the change in prophylaxis (P=0.009). Patients with C difficile infection also had a statistically significant increase in antibiotic exposure, inpatient stay, morbidity and inpatient mortality.

The main challenges regarding antibiotic selection are failure of prophylaxis, often because of infection with MRSA, and C. difficile-associated diarrhoea as a consequence of antibiotic prophylaxis. Infection with C. difficile is reduced with the new regimen. We advocate the use of the new regimen as an effective alternative to multiple dose cephalosporins for the prevention of C. difficile infection in this group of high risk patients.

Introduction: The national comparative audit in 2007 of blood use in primary elective hip replacement, showed a 25% transfusion rate. Of those 93% received two or more units. Orthopaedic surgeons are large users of blood, so reducing blood use, should save costs and reduce risk from unnecessary donor exposure.

Methods: Over two years 221 consecutive primary total hip replacements were performed, on 84 male and 137 female patients, average age 70 years (42–91yrs). For each the Haematinics cell salvage system was used. Throughout the surgery the cell salvage system was used. At the end of the operation all swabs were washed, the washings were salvaged. Iodine/peroxide contaminated washing and swabs were discarded.

Results: Were we using blood at the level suggested by the comparative audit, 55 patients would have received an average of 2.4 units (132 units total). The actual number of patients transfused was 12, receiving an average of two units (24 units total). This is 108 units less with 43 fewer patients receiving allogenic blood. Using a test of proportions using the Normal distribution then the significance probability is extremely small (SP< 0.001) indicating that this group of patients had a significantly smaller number of transfusions than would be expected compared with the National Average. The transfused patients were older (78.9 vs. 69.8, p< 0.01), had a greater Hb drop (45 g/l vs. 31.2 g/l, p< 0.01), had a lower pre-op Hb (121.3 g/l vs. 138 g/l, p< 0.001), and a greater length of stay (12.8 days vs. 5.8 days, p< 0.05). Gender was not significant.

Discussion: Using the cell salvage system leads to a significant reduction in allogenic blood use. It may not be cost neutral once the use of disposables is factored in, but may represent a useful tool to cost effectively reduce allogenic blood use.

Hip resurfacing preserves proximal femoral bone stock, optimises stress transfer to the proximal femur and offers inherent stability and optimal range of movement. The early results of metal–on-polyethylene resurfacing designs were poor and the resurfacing concept was largely abandoned. Modern metal-on-metal articulations enabled the introduction of a new generation of hip resurfacings with encouraging early results. In 1997 two of the authors developed a hip resurfacing system utilizing a metal-on-metal bearing. Our study reports on the clinical and radiological outcomes of the first 200 hips that were treated with the Durom hip resurfacing at an average follow up of 4.6 years (range 3.5–6).

Between May 2001 and December 2003, 200 consecutive hip resurfacings were performed on 189 patients, using the Durom hybrid metal-on-metal system. The average age of the patients was 50 years (range 22.5 – 72.3) and 119 were male. Patients were seen at 6 weeks and at 3, 6 and 12 months and annually thereafter for clinical and radiological evaluation. Clinical results were evaluated using the Harris Hip Score. A subjective assessment of patient satisfaction was obtained and patient activity was assessed using the UCLA activity score.

No patient was lost to follow up. There were no dislocations and no femoral neck fractures. One femoral component was revised due to aseptic loosening 3.9 years postoperatively. There was one late acute haematogenous infection that was successfully treated elsewhere by debridement and retention of the prosthesis. The mean Harris Hip Score improved significantly from 46.7 preoperatively to 94.4 postoperatively. The mean HHS constituents for pain, function and motion all were significantly improved from the preoperative values of 11.9, 25.7 and 4.2 to 41.8, 43.4 and 4.8 respectively following the resurfacing procedure. The mean UCLA activity score was 7.2 indicating a relatively active patient population and 179 hips were rated as excellent by the patients. No cup was considered radiographically loose. Extensive radiologic changes were observed around the femoral stem in 2.5% of the hips, with migration of the femoral component in one case and stem demarcation in 4 cases. All 5 patients maintained excellent function and had no hip pain. Pelvic osteolysis was observed in 2 cases. Neck remodelling changes were observed in 35 hips (17.5%). Kaplan-Mayer survivorship analysis demonstrated the rate of survival of the resurfacing components to be 99.5% (95% confidence interval 98.5 to 100) with revision for any reason as the endpoint.

Early results with the Durom resurfacing system appear encouraging. Although these should be regarded with caution, modern metal-on-metal hip resurfacing potentially offers the ultimate bone preservation and restoration of function in appropriately selected young patients.

Introduction: Antibiotic-associated Clostridium difficile diarrhoea may complicate surgery for proximal femoral fracture. We sought to determine whether a change in antibiotic policy in our unit influenced rates of infection with C. difficile following hip fracture surgery.

Methods: A 4 year case controlled study. A change in antibiotic prophylaxis was introduced during a 3 month period in 2005. Infection rates with C. difficile were compared for 2 years either side of this period. The initial regimen was one of three doses of cefuroxime (1.5 g). The new regimen is a single dose of cefuroxime (1.5 g) with gentamicin (240 mg) at induction. Infection was defined as diarrhoea with a positive isolate within 30 days of surgery.

Results: Prior to the change in prophylaxis, 912 patients underwent surgery for neck of femur fracture. Following the change, 899 patients underwent surgery over the period March 2005 to March 2007. 38 patients developed C. difficile infection (4.2%) in the initial group, compared with 14 patients (1.6%) in the group following the change in prophylaxis (P=0.009). Patients with C difficile infection also had a statistically significant increase in antibiotic exposure, inpatient stay, morbidity and inpatient mortality.

Discussion: The main challenges regarding antibiotic selection are failure of prophylaxis, often because of infection with MRSA, and C. difficile-associated diarrhoea as a consequence of antibiotic prophylaxis. Infection with C. difficile is reduced with the new regimen. We advocate the use of the new regimen as an effective alternative to multiple dose cephalosporins for the prevention of C. difficile infection in this group of high risk patients.

Aims: The aims of our study were:

to measure the total metal content in cell saver blood recovered during revision hip arthroplasty,

Materials and methods: We analysed the levels of metallic debris and metal ions in cell saver blood in nine patients undergoing revision hip replacement. Using inductively coupled plasma mass spectrometry (ICP-MS), the levels were measured for titanium, aluminium, vanadium, chromium, cobalt, nickel and molybdenum. The metal ion levels were analysed using a dilution technique and the total metal content levels (particulate debris and ions) were analysed with a digestion technique.

Results: Significantly higher levels of metal ions and metal debris were found in the pre-processed blood compared with the processed blood (after centrifuging and washing). The ion levels in the processed blood were not high enough to cause a significant increase in the patients’ immediate post-operative blood ion levels when compared with pre-operative levels.

Discussion: There are markedly elevated levels of metal ions and particulate metal debris in the blood salvaged during revision total hip arthroplasty. The processing of the recovered blood in a commercial “cell saver” significantly reduces the total metal load that is re-infused. Re-infusion of salvaged blood does not result in elevated metal ion levels in the immediate post-operative period.

Metal-on-metal hip resurfacing arthroplasty is a conservative procedure that is becoming an increasingly popular option for young arthritic patients most likely to undergo a secondary procedure in their lifetime. The stability of the acetabular component is of particular concern in these patients who show an increased risk of failure of the cemented acetabular cups in conventional total hip replacements. The purpose of this study was to examine the initial stability of a cementless interference press-fit acetabular cup used in hip resurfacing arthroplasty and implanted into ‘normal’ versus poor quality bone. Also examined was the effect of the press-fit procedure on the contact mechanics at the cup-bone interface and between the cup and femoral head.

A finite element (FE) model of the DUROM resurfacing (Zimmer GmbH) was created and implanted anatomically into the hip joint, which was loaded physiologically through muscle and subtrochanteric forces.

The FE models included: a line-to-line, 1mm and 2mm interference press-fit cup. Also considered were two FE models based on the 1mm press-fit cups, in which the material properties of the cancellous and cortical bone tissues were reduced by 2 and 4 times, to represent a reduction in bone quality as seen with age or disease.

Increasing the cup-bone interference resulted in a sig-nificant reduction in implant micromotion. All the pressfit models showed predicted cup-bone micromotion below 50 micrometers. This would ensure adequate initial stability and encourage secondary fixation through bone in-growth. The predicted acetabular stresses were found to increase with the amount of press-fit, however, there was no suggestion of a fracture. These stresses would further contribute to securing the cup.

Reducing the bone quality showed an increase in the predicted micromotion and increased bone strain. Micromotion was below 50 micrometers, but the predicted compressive bone stresses, necessary for additional implant fixation, was reduced. This implied that poor quality bone would provide unsuitable support medium for the implant. The bearing surface contact mechanics were little affected by the amount of pressfitting.

Purpose: The aims of our study were: (i) to measure the total metal content in cell saver blood recovered during revision hip arthroplasty, (ii) to evaluate the efficacy of centrifuging and washing the recovered blood in reducing the metal content, (iii) to investigate whether transfusion of the salvaged blood resulted in a significant increase in the metal ion levels in the patients’ blood in the immediate post-operative period.

Materials and methods: We analysed the levels of metallic debris and metal ions in cell saver blood in nine patients undergoing revision hip replacement. Using inductively coupled plasma mass spectrometry (ICP-MS), the levels were measured for titanium, aluminium, vanadium, chromium, cobalt, nickel and molybdenum. The metal ion levels were analysed using a dilution technique and the total metal content levels (particulate debris and ions) were analysed with a digestion technique.

Results: Significantly higher levels of metal ions and metal debris were found in the pre-processed blood compared with the processed blood (after centrifuging and washing). The ion levels in the processed blood were not high enough to cause a significant increase in the patients’ immediate post-operative blood ion levels when compared with pre-operative levels.

Conclusion: There are markedly elevated levels of metal ions and particulate metal debris in the blood salvaged during revision total hip arthroplasty. The processing of the recovered blood in a commercial ‘cell saver’ sig-nificantly reduces the total metal load that is re-infused. Re-infusion of salvaged blood does not result in elevated metal ion levels in the immediate post-operative period.

Proximal humeral fractures are common and often occur in osteoporotic bone. Suture fixation utilises the rotator cuff tendons as well as bone providing adequate stability and avoids complications associated with metalwork insertion.

Surgical exposure was via a delto-pectoral approach with minimal dissection of the fracture site. Initially a 2 suture technique was utilized with heavy ethibond sutures passed through drill holes either side of the bicipital groove; however, because of concerns about varus instability the technique now uses a third suture placed laterally acting as a tension band to prevent varus collapse. Patients with Neer 2 and 3 part fractures treated with suture fixation were assessed clinically (using the Constant score) and radiologically at a mean of 27 months post fracture.

To date 24 patients have been studied. The average age of the patients in our series was 70.2. All fractures progressed to union with no cases of radiological avascular necrosis. We had 2 cases of mal-union (-one varus and one valgus-), both with a 2-suture technique. One patient had early loss of fixation; re-exploration was performed with stability conferred by a third lateral suture. Active abduction > 120o was achieved in 9 patients with a mean Constant score of 72 compared to 89 on the un-injured contra-lateral side. We have demonstrated that suture fixation of displaced proximal humeral fractures is an effective alternative to fixation using metalwork. The advantages are that minimal soft tissue stripping of the fracture site is required and the potential problems associated with metalwork insertion into osteoporotic bone are avoided. Following one case of varus mal-union with a 2-suture technique we now routinely use a third suture to act as a lateral tension band.

Private companies now offer risk assessment packages to Trusts. Data are collected using ICD coding and complication rates for individual surgeons are calculated and published. A risk assessment document was recently published at the Royal Gwent Hospital presenting complication rates and misadventures on league tables of specialty and consultants. Serious concerns were raised about the quality of the data. We undertook a study to independently evaluate the accuracy of data used to calculate these complication rates.

Two Orthopaedic Surgeons with the highest published complication rates were studied. The notes of patients who had suffered complications were retrieved and the published complication data was compared with the clinical interpretation of the actual complication. One hundred and fifty reported complications were analyzed.

In most cases data accuracy was woefully inadequate. For example revision procedures were counted as complications for the revision surgeon irrespective of who carried out the primary procedure. The normal work-up of these patients including procedures to investigate the presence of infection are recorded as complications with some patients being recorded as having up to four separate complications. Misadventures published for surgeons included dural tap during epidural anesthesia. The results of this study highlight the potentially devastating consequences of data inaccuracy. Inaccurate published data on complications, used to form league tables for individual surgeons, can be career- jeopardizing. We advocate that consultation with the clinicians involved should always occur before data are published so that these inaccuracies can be picked up and the potentially damming consequences of falsely high complication rates can be avoided.

Finite element analysis was used to examine the initial stability after hip resurfacing and the effect of the procedure on the contact mechanics at the articulating surfaces. Models were created with the components positioned anatomically and loaded physiologically through major muscle forces. Total micromovement of less than 10 μm was predicted for the press-fit acetabular components models, much below the 50 μm limit required to encourage osseointegration. Relatively high compressive acetabular and contact stresses were observed in these models. The press-fit procedure showed a moderate influence on the contact mechanics at the bearing surfaces, but produced marked deformation of the acetabular components. No edge contact was predicted for the acetabular components studied.

It is concluded that the frictional compressive stresses generated by the 1 mm to 2 mm interference-fit acetabular components, together with the minimal micromovement, would provide adequate stability for the implant, at least in the immediate post-operative situation.

Introduction: Hip simulator and clinical retrieval studies have shown that metal-on-metal (MOM) hip implants commonly have biphasic wear. An initial high wear or running-in phase is generally followed by a low wear or steady-state phase. A number of hypotheses have been put forward to explain this biphasic phenomenon, including polishing of the metallic bearing surfaces and increasing conformity between the two articulating surfaces. The purpose of the present study was to compare the wear and lubrication of MOM hip implants between the running-in and steady-state periods.

Materials and Methods: A standard 28mm Metasul^TM MOM bearing (Centerpulse Orthopedics, a Zimmer Company, Winterthur, Switzerland) was investigated. The wear testing was carried out using a 6-station AMTI hip simulator in the presence of 33% bovine serum and 67% Ringer solution (PH 7.2). The bearing surfaces of both the femoral and acetabular components were measured using a coordinate measurement machine at different stages of wear testing. The dimensional changes of the bearing surfaces due to wear were directly incorporated into the elastohydrodynamic lubrication analysis using an in-house developed code.

Results: The initial running-in period occurred during the first 1 million cycles, and little wear was observed subsequently up to 5 millions cycles. The maximum total wear depth was measured to be around 13 μm at 1 million cycles. The predicted average lubricant film thickness between the two articulating surfaces was increased from 0.024μm at the beginning, to 0.09μm at the end of the first 1 million cycles. For a given composite surface roughness of 0.03μm often quoted for the metallic bearing surfaces, such an increase in the lubricant film thickness represents a transition from a mixed to a fluid film lubrication regime.

Discussion: A large improvement in lubrication was predicted as a direct result of the running-in wear of the bearing surfaces. This was mainly due to the increased conformity between the two articulating surfaces and the decreased diametrical clearance. It was particularly noted that the improvement in lubrication after 1 million cycles was so significant that continuous fluid film lubrication was possible, leading to extremely low wear for up to 5 million cycles, and only material fatigue and start-up and stopping for wear measurements could cause a further increase in wear.

It is possible in theory to optimise the geometry of the metallic bearing surfaces, based on the worn components, to minimise the running-in wear. However, such an improvement in lubrication cannot be readily achieved because of difficulties in surgical techniques and position of the components.

Introduction: Laboratory simulator and clinical retrieval studies of metal-on-metal (MOM) total hip replacements have shown that the metallic alloy, the femoral head radius, the clearance between the acetabular cup and femoral head and the cup thickness can influence the contact mechanics, the lubrication and the wear of the articulation. MOM hip resurfacing procedures have received significant attention recently. The purpose of the present study was to compare the contact mechanics between a MOM hip resurfacing implant and a MOM total hip replacement under identical conditions.

Materials and Methods: A 50mm diameter DUROM^TM MOM hip resurfacing prosthesis and a 28mm diameter Metasul^TM MOM bearing system (Centerpulse Orthopedics, a Zimmer Company, Winterthur, Switzerland) were investigated. All implants were manufactured from wrought-forged high carbon cobalt chromium alloy (Pro-tasul 21WF^TM). The diameters of the DUROM^TM femoral head and acetabular cup were 50mm and 50.145mm respectively, and the corresponding wall thickness of the acetabular component was around 4mm. The diameters of the Metasul^TM femoral head and acetabular cup were 28mm and 28.12mm. Three-dimensional finite element models were created to simulate the contact between the bearing surfaces of both the femoral head and the acetabular cup fixed to a three dimensional anatomically positioned pelvic and femoral bone consisting of both cortical (with 1mm thickness) and cancellous regions. The load applied to both models was 3200N.

Results: The maximum contact pressure at the bearing surfaces was found to be around 22MPa for the DUROM^TM and the contact area between the femoral and acetabular components was predicted to be 237mm². For the Metasul^TM bearing under identical conditions, the maximum contact pressure and the contact area predicted were approximately 47MPa and 74mm² respectively.

Discussion: A large reduction in the contact pressure, which should improve overall tribological performances, was noted for the DUROM^TM hip resurfacing prosthesis, as compared with the Metasul^TM bearing. The main reasons for this reduction were the large diameter of the articulation and the small acetabular cup thickness of the DUROM^TM system. In contrast, the Metasul^TM bearing has a smaller head diameter, and relies on a polyethylene backing underneath the metallic cup inlay to reduce the contact pressure at the articulating surfaces.

Since 1977 we did implant all alumina (Al2O3) bearings total hip prostheses. A lot of data were documented concerning tissue reaction, in vivo wear behaviour, fractures, and clinical outcome. Ceramic materials retrieved at revision were analysed. In some cases, wear was as low as a few microns for a 15-year period in use. This is two thousand times less than a regular metal on polyethylene sliding couple. and 100 times less than a metal on metal prosthesis. Fracture mechanism is related to crack propagation into the material. During the first period, the fracture rate was in the range of 2%; it then dropped to less than 0.1 %. Few fractures could not be explained by technical or design mistakes. Clinical outcome: More than 4000 total hips in selected young and /or active patients were implanted. In a recently reported series of consecutive patients operated by P.Boutin during the year 1980, 118 hips in 106 patients were included. Mean age was 62 years. At the twenty-year follow-up evaluation, forty-five patients (fifty-one hips) were still alive and had not been revised, twenty-five patients (twenty-five hips) had undergone revision of either or both components, twenty-seven patients (thirty hips) had died from unrelated causes, and nine patients (twelve hips) were lost to follow-up. The mean Merle d’Aubigné hip score was 16.2 ± 1.8 at the latest follow-up. Survival of the cup at twenty years with revision for any reason as the end-point was 85.6 percent for cementless cups versus 61.2 % for cemented cups, respectively. Survival of the stem at twenty years with revision for any reason as the end-point was 84.9 % for cementless stems versus 87.3% for cemented stems. Wear of the prosthetic components was undetectable on plain radiographs. No fracture of the alumina socket or head was recorded. Another study concerned a more recent design of the socket which consisted in a metal back titanium alloy shell covered with a pure titanium mesh with an alumina liner. The nine year survival rate was 98.4% with revision for aseptic loosening as the end point. Conclusion This alumina on alumina bearing provides interesting results without any physical limitation specially in young and active patients.

Metal-on-metal (MOM) bearings for artificial hip joints have attracted significant attention recently as a way of reducing wear and consequently wear particle induced periprosthetic osteolysis, which is the major cause of failure. One of the most widely used MOM total hip implants is the Metasul system (Zimmer GmbH), in which a thick polyethylene backing is used underneath the metallic inlay. The purpose of this study was to investigate the effect of the polyethylene backing on the transient lubrication under dynamic loading and velocity conditions representative of walking. A 28mm diameter Metasul bearing was analysed, and the predicted lubricant film thickness was compared with that for an all metallic cup. The predicted transient lubricant film thickness in the Metasul system was found to be significantly greater than the corresponding prediction from the all metal cup. Therefore it was concluded that the polyethylene backing may play an important role in the lubrication and overall tribological performance of the Metasul bearing system with a diameter of 28mm.