Purpose: Radiostereometric Analysis (RSA) is used to measure migration and inducible displacement (ID) of orthopedic implant devices to allow early prediction of implant failure (eg. Aseptic loosening). Total Ankle Arthroplasty (TAA) is used for the treatment of end-stage ankle arthritis. First generation TAA implant have meet with widespread failures while some second generation TAA implants are showing improved results. In this study RSA is used to evaluate the biomechanical properties of a new third generation TAA implant in an attempt to set a standard for the biomechanical evaluation on TAA implants in-vivo.

Method: Patients undergoing TAA were enrolled consecutively (n=12; 7 males; mean age=59 years; mean BMI=29) and had 8 markers (0.08mm) inserted in both the tibia and talus during surgery. Standing, weight-bearing RSA exams were performed at 3 and 6 months and compared to concurrent supine exams to determine component ID.

Results: For tibial components: at six months the components had translated posteriorly (0.3mm±0.5) and proximally (0.5mm±0.2), tilted into varus (0.5°±1.3), and tilted posteriorly (0.4°±0.8). The magnitudes of ID for the tibial components were moderate (mean < 0.2mm and 0.5°, standard deviation < 0.3mm and 2.2° in each direction). For talar components: at six months the components had translated distally (0.28mm±0.35), rotated internally (0.21°±1.32) and tilted posteriorly (0.15°±0.90). There was varus/valgus tilt measured in the talar components but there was no consistent direction of migration (0.03°±1.4). At six months the magnitudes of ID for the talar components were small (mean < 0.1mm and 0.25°, standard deviation < 0.2mm and 0.6° in each direction).

Conclusion: An RSA methodology has been established to predict stability.

Introduction

Cemented hemiarthroplasty for neck of femur fractures has been advocated over uncemented hemiarthroplasty due to better post-operative recovery and patient satisfaction. However, studies have shown adverse effects of bone cement on the cardio-respiratory system which may lead to higher morbidity and mortality. Therefore, in some institutes, the use of an uncemented prosthesis has been adopted for patients with a high number of co-morbidities. The aim was to compare early mortality rates for cemented vs. uncemented hemiarthroplasties.

Hip and knee replacements are common and successful surgeries in orthopaedics. One of the known complications is fat embolism. Cemented implants used in arthroplasty allow good implant fixation and excellent long term results. However this has been associated with an increased incidence of fat embolism. This experimental animal study compared the amount of fat embolism following three different surgeries in 30 Sprague Dawley rats. These surgeries simulated hip replacement procedures and included a control surgery, an un-cemented implant and a cemented implant. These animals were then sacrificed at 24 hours. All the lungs were fixed in formalin and then stained using Osmium Tetroxide. The amount of fat was then counted using a light microscope at 40x power. Both the uncemented implant group (p < 0.001) and the cemented implant groups (p < 0.003) had significantly higher fat emboli from the surgical control group. There were also a significantly higher number of emboli (p < 0.05) in the cemented implant group compared to the uncemented implant group. We conclude that fat embolism occurs in both the un-cemented and cemented hip replacement. The amount of emboli created by un-cemented hip replacement is less than the cemented hip replacement. The cement itself does not cause the complication of fat embolism. It is the high intramedullary pressure associated with the insertion of the implant, and the cementing process, that contributes to fat embolism. Devices or surgery that minimise this rise in pressure could reduce the amount of fat embolism

Objective: To develop in-vitro experiments that measure the strain distributions at the bone-implant and bone-cement interface of the acetabular region under physiological loading conditions for cemented and cementless sockets. Experimental model: Four hemi-pelvic specimens of saw bones were used. Following careful placement of six protected precision strain gauges, two specimens were prepared to receive a cemented polyethylene cup (Depuy Charnley Elite 53/28). Another two specimens were prepared and implanted with un-cemented Duraloc 58/28 cups. Press-fit technique was validated by torque measurements. Background: Symptoms associated with prosthetic migration result from osteoclast induced bone resorption at the interface adjacent to bone. We aim to develop a new and more accurate method of measuring strains at this critical interface. Methods: To simulate quasi-static loading, selected variables of hip joint force relative to the cup during normal walking was used for quasi-static tests on an Instron 1603 testing machine. The magnitude and orientation of the principal strains (maximum and minimum) were calculated based on the readings of strains from a 32 channel digital acquisition system. Results: The magnitude and distribution of acetabular trabecular bone strains are dependent on the type of cup material (un-cemented/cemented) implanted. At the position of maximum load, the maximum principal strain in the un-cemented specimens was 14.4 times higher than that for the cemented specimens (T-value = −96.40, P-value = 0.007). The highest recorded tensile strains in these specimens were localised to the acetabular rim of the posterior-superior quadrant. For the cemented specimens, the maximum principal strains are highest in the dorsal acetabulum, at a location that approximates to the centre of rotation of the replaced hip joint. Shear strains in the posterior-superior quadrant of both cementless and cemented acetabuli surpass the maximum principal strains. Conclusion: In both cemented and un-cemented specimens, the maximum shear and principal strains magnitude show similar spatial and statistical distribution. As indicators of local failure prospect within the acetabulum, these strains suggest that the posterior-superior quadrant is the most likely site for load-induced micro-fractures, in both cemented and cementless acetabuli

Principles of bone preservation and restoration of biomechanical alignment should be followed during revision total hip arthroplasty (THA). Where possible, conservative femoral revision techniques and even reconstructive de-escalation involving using primary stems should be considered. This study aims to investigate the outcome of patients who have undergone conservative femoral revision THA in our Institution. We retrospectively identified patients from our Institution's revision arthroplasty database who had cemented, or un-cemented primary stems implanted during revision THA of a previous stemmed femoral implant. Our primary outcome measure was all-cause re-revision THA with a secondary outcome measure of improvement in Oxford hip score (OHS). Radiographic evidence of stem loosening and post-op complications were recorded. Between 02/12/2014 to 12/12/2019, there were 226 patients identified with a mean follow up of 2 years (1–5 years). The majority of cases were represented by Paprosky type 1 (63%) and type 2 (25%) femoral defects. There were 45 patients (20%) who underwent impaction bone grafting (IBG) and 43 patients (19%) who had a cement in cement (CinC) femoral revision and cemented primary stem in 137 (60%), 1 uncemented stem with no IBG or CinC revision. Kaplan Meier survival for all-cause re-revision THA was 93.7% (95% CI: 88.3 – 100) at 3 years. The reasons for re-revision included 4 periprosthetic fractures, 4 dislocations, 1 deep infection, 1 loosening of femoral component and 1 loosening of acetabular component. Pre- and post-operative OHS scores were available in 137 hips (60%) with a mean improvement of 13. Radiographic review revealed 7% of cases with evidence of loosening in 1 or more Gruen zones. Our early results support the use of conservative femoral revision THA techniques where appropriate, with low complication and re-revision rates. Revisions using primary femoral components, where appropriate, should be considered in surgical planning to avoid unnecessary reconstructive escalation

The use of fourth generation ceramic as an orthopaedic biomaterial has proved to be a very efficient and has gained popularity for primary hip surgery in the last 8–10 years. Cumulative percentage probability of revision after 7 years for un-cemented CoC is 3.09% and for hybrid CoC is 2.00%, this compares favourably with traditional metal-on-UHMWPE un-cemented at 3.05% and hybrid at 2.35% (12th Annual Report - NJR, 2015). Such ceramic-on-ceramic hip prostheses are being implanted in ever younger, more active patients, and yet very few long-term large cohort retrieval studies are yet to be carried out due to the survivorship of the implants. It has been seen in previous studies that levels of wear in ceramic-on-ceramic bearing surface can be of the order of 0.2 mm. 3. /million cycles (Al-Hajjar, Fisher, Tipper, Williams, & Jennings, 2013). This is incredibly low when compared to studies that characterize wear in other bearing surface combinations. It has also been reported that an unusual stripe pattern of wear can occur in some in-vivo retrieved cups (Macdonald & Bankes, 2014) and it has further been postulated that this is caused by cup edge loading (Walter, Insley, Walter, & Tuke, 2004). The combined measurement challenge of stripe wear occurring at the edge of a low-wear ceramic-on-ceramic device is considerable, a solution to which is presented here. Current literature on wear measurement of such cases has been confined to in-vitro simulator studies and use of gravimetric measurement which by definition has limitations due to the lack of spacial characterisation. This paper details a novel method for measuring edge-wear in CoC acetabular liners. The method has been employed in an in-vitro study where it has been benchmarked against gravimetric measurements. These liners were measured on a CMM to determine the volume of material loss. The measurements were conducted as a blinded post-wear study akin to measurement of retrieved components. The most challenging part of this novel method was to create a reference geometry that replicates the free form edge surface of the ‘unworn’ cup using the residual post-wear surface. This was especially challenging due to the uncontrolled geometry at the cup edge and intersection of geometric features at this point. To achieve this, the geometry surrounding the wear patch was used to create a localized reference feature that minimised the effect of global form errors caused by hand polishing in the edge area. Furthermore, the reference geometry is compared with the measured surface to determine the linear penetration and volumetric wear loss. Result of this novel method can be seen in Fig 1. The findings have been compared to gravimetric results and a bar graph comparing two results can be seen in Fig 2. Overall the accuracy of the method for this cohort was 0.03–0.2 mm. 3. when compared to gravimetric reference measurements. This compares very favourably with previously published wear measurement methods and gives confidence in the ability to measure such small measurement volumes over complex geometry

In 1823 J. White excised the head. In 1887 a German surgeon replaced the head with ivory. Interposition arthroplasties were common after WW1. Short-stemmed head replacing prosthesis were developed after WW2. Moores and Thompson designed a more stable intramedullary stem. Acetabular erosion was troublesome—and so replacing both surfaces started in the late 1950s using Teflon cup and metal femur. Unfortunately, these quickly became loose due to wear or sepsis. In 1960, Charnley used a polyethylene cup and stainless-steel femur and fixed both with dental cement. This ‘low friction arthroplast’ became a routine procedure after 1961. In the 1970s there were many ‘Charnley look-alike’ prosthesis with similar problems of poly-wear, granulomas and cysts causing bone loss, loosening, breakages and infection. Resurfacing with two thin shells was developed to reduce the foreign material, the bone resection and the cement used. Unfortunately, neck fractures, avascular necrosis and excessive wear of the poly shell were common. Despite operating theatres with laminar flow of sterile air, space suits and improved cementing techniques, the same problems occurred. To avoid poly and cement, Mittelmayer developed a ceramic screw cup, which did not require cement. Although some screws migrated, they did not wear. Because the un-cemented metal stem remained fixed solid to the femur, un-cemented metal cups and stems were developed. To avoid the poly-wear, ceramic liners became popular. To provide the active patients with a stable joint that requires no restriction in physical activity, a large head in a large cup is desirable. Unfortunately, the large metal-on-metal resurfacing prosthesis produce metal wear ions and nanoparticles which can form hypersensitivities, cysts and pseudotumours. Computer assisted navigation to ensure correct positioning of the prosthetic components is obviously useful for surgeons that use incisions too small to see enough to be certain of the cups position. Presently, articular cartilage research is progressing rapidly and by 2020 most arthritic hip joints will be arthroscopically debrided and resurfaced by an injection of genetically engineered articular cartilage stem cells

When inserting a femoral stem, surgeons make use of many visual and tactile cues to be sure that the implant is correctly sized and well-seated. One such cue is the change of pitch that can be heard when the final femoral broach is inserted. This is known to be important, but has not been widely studied. We set out to analyse the sounds produced during femoral broaching and implant fixation, and to discover whether the absence of these sounds could predict a poor fixation. We recorded the sound of femoral broaching and definitive implant insertion, for twenty un-cemented Corail total hip replacements. Procedures were performed by the same surgeon, in the same theatre. The recordings were visualised using audio editing software, and a Fast Fourier Transform was used to identify the dominant audio frequencies. In 19 of the 20 cases, the final strikes of the final femoral broach displayed a distinctive pattern, with the most prominent frequencies being harmonics (multiples of a fundamental frequency) which had a wavelength directly related to the length of the femoral canal. This contrasts with initial strikes, where multiple unrelated frequencies were present. Postoperative radiographs were examined by two surgeons independently, to assess implant sizing and positioning. The one case, in which the harmonic pattern was not observed, was found on radiographs to be an undersized, varus malpositioned implant. We demonstrate that a characteristic frequency pattern is present when impacting cancellous bone with a well-sized and well-placed femoral broach. When the pattern was absent, the broach and implant were undersized and malpositioned. We hypothesise that this pattern arises when broach and femur are vibrating as one, indicating adequate contact with, and compression of, cancellous bone

Modular un-cemented acetabular components are used in over 50% of UK hip replacements. Mal-seating of hard liners has been reported as a cause of failure which may be a result of errors in assembly, but also could be affected by deformation of the acetabular shell on insertion. Little information exists on in vivo shell deformation. Previous work has confirmed the importance of shell diameter and thickness upon shell behaviour, but mostly using single measurements in models or cold cadavers. Exploration of deformation and its relaxation over the first twenty minutes after implantation of eight generic metal cups at body temperature. Using a previously validated cadaveric model at controlled physiological temperature with standardised surgical technique, we tested the null hypothesis that there was no consistency for time dependent or directional change in deformation for a standard metal shell inserted under controlled conditions into the hip joint. Eight custom made titanium alloy (TiAl6V4) cups were implanted into 4 cadavers (8 hips). Time dependent cup deformation was determined using the previously validated ATOS Triple Scan III (ATOS) optical measurement system. The pattern of change in the shape of the surgically implanted cup was measured at 3 time points after insertion. We found consistency for quantitative and directional deformation of the shells. There was consistency for relaxation of the deformation with time. Immediate mean change in cup radius was 104μm (sd 32, range 67–153) relaxing to mean 96 μm (sd 32, range 63–150) after 10 minutes and mean 92 μm (sd 28, range 66–138) after 20 minutes. This work shows the time dependent deformation and relaxation of acetabular titanium shells and may aid determining the optimal time for insertion of the inner liner at surgery

Press-fit fixation of uncemented acetabular components is increasingly being used for total hip replacement (THR) surgery. This study was aimed to analyse the survival of an established, un-cemented flexible metal backed cup with non-highly cross-linked polyethylene in primary and simple revision THR. We assessed the outcome of 1703 consecutive cementless elastic acetabular cups (Atlas, FH France) with non-highly cross-linked polyethylene (GUR1030) in total hip replacement surgery. There were 1582 patients (513 males and 1079 females) with mean age of 74 years (36–97 years). Seventeen senior operating surgeons accounted for 88.5% of cases from a single arthroplasty unit. Survival analysis was calculated using the Kaplan Meier Estimator. At 184 months post surgery the survivorship was 92.4% (95% CI 88.3–94.7) with cup revision for any cause as an endpoint. Three patients died within first month of surgery and 268 patients (17.13%) died due to unrelated causes. Overall, 59 patients had revisions (3.5%), Thirty eight patients (2.3%) were due to acetabular causes such as: aseptic loosening in 6 patients (0.35%); hip instability in 13 patients (0.76%); and deep infection in 11 patients (0.64%). We believe the cementless elastic acetabular cup on in total hip replacement is tolerant of technique and patient variation and continues to give excellent long-term results and its continued widespread use can be recommended

Objectives. Implant loosening is the most common reason for revision of total or partial knee replacement, but the patient complains of pain-not a loose implant. It would be a useful diagnostic tool to interrogate the implant to ascertain whether it remains well fixed or not, thus either confirming or eliminating this mode of failure. For such technology to be adopted by manufacturers, it must be extremely low cost and simple to build into an implant. We aim to develop a sensor that meets these requirements and, when embedded in an implant, can provide information on its fixation to the underlying bone. We have previously proven that, through impedance analysis of passive piezoelectric sensors, it is possible for such sensors to determine the cured state of cement with good correlation (0.7) to a surgeon's judgement (Darton et al, 2014). In this study we now look at how the impedance trances of the sensors can be interpreted to distinguish between tibial trays that are securely cemented in sawbone blocks and those with no cement in loose fitting sawbone blocks. Method. Small piezoelectric sensors (12 mm diameter, 0.6 mm thickness) were attached using ethyl cyanoacrylate to the top of a small metal tibial tray analogue and wired to an Impedance Analyzer (AEA Technology Inc). The sensor was swept with an alternating current between 100KHz and 400KHz. Three readings were taken using a custom-built code in MATLAB and an average impedance trace was calculated. A pre-calibrated servo-mechanical testing machine (Instron) was used to carry out a pull-out test of the tray from the sawbone block. The force required to completely disengage the tray was recorded. The same tibial tray was then cemented to the same sawbone block using PMMA. Once cured, the same impedance readings were taken before a pull out test was performed on the cemented case. This was repeated on 6 different sawbone blocks. The impedance plots were differentiated to exaggerate the jagged nature of the impedance trace, representative of multiple modes of vibration following which the mean of their differential values was calculated. The average pull out force for cemented trays was approximately 20 times greater than the un-cemented. Results. Qualitatively, the graph in Figure 1 shows a distinct difference between mean differentiated impedance values for cemented and uncemented trays. This is quantified with paired t-tests that suggest a significant difference between the two bond situations (P«0.01). Conclusion. Our sensors show a clear difference between trays fixed securely in place and those poorly fixed. Further work is being carried out to measure the breakdown in the mechanical interlock under simulated physiological loading. A distinct advantage of this method is that it only requires the impedance of the sensor to be determined; hence the circuitry is simply the sensor attached to a coil, the impedance characteristics of which can be interrogated through established induction methods. This technology has the potential to be extremely cheap, easy to implement and compact

Introduction: Lateral insufficiency fractures following total hip replacements have been reported with the femoral stems positioned in varus, together with osteopenia of the lateral femoral cortex. Any abnormal alignment of the lower limbs, such as genu valgum, will alter the load distribution across the femoral cortices, and repetitive loading during walking will predispose the bones to stress fractures at any stress riser point, such as the tip of a femoral component. Bilateral femoral stress fractures post total hip replacements have not been previously described. Materials and Methods: We present a 55 yr old lady, diagnosed with juvenile idiopathic arthritis aged 5 years, and had undergone bilateral total hip replacements at the age of 29 and 30 years and bilateral knee replacements aged 37 and 42 years. The right hip required revision of the cup 15 years later. The knees were in valgus and the left knee was extremely stiff flexing to just 5 degrees. She presented to us as an emergency with bilateral thigh pain with plain radiographs confirming bilateral peri-prosthetic fractures of the femur at the tip of well fixed femoral components. There had been no history of injury and her hips were functioning well up to this time. Results: The patient required revision of both hips to long stem un-cemented components, bypassing the fractures, and revision of both knees to stemed seni-constrained implants, thereby correcting the alignment of both lower limbs. Both fractures healed and the patient is currently pain free and mobile with walking aids. Discussion: Surgeons must remain aware that when implants are in situ, abnormal alignments will lead to abnormal forces, and stress fractures are likely to occur at any stress riser around the implant. Avoiding mal-alignment will avoid this complication. Bilateral peri-prosthetic stress fractures following total hip replacements have not been previously reported

Aim: To review the study size and requirements of studies looking at factors affecting outcome following total hip arthroplasty. Background: The orthopaedic literature is full of claims that new products out-perform older ones, cemented and un-cemented components are equal, cementing grades and mantles are all important and that component orientation is vital to longevity. We are also aware of patients who have performed well despite having numerous adverse features to their joint replacements. We have searched the available literature for factors that have been implicated in the survival of hip replacements. We have used these to determine the likely study sizes required to provide meaningful data. Method: We identified over 50 variables that have been implicated in the survival of hip replacements. Assuming all of them to be of equal relevance the study size required for multivariate analysis to be possible would be in excess of 50000. Some of these variables are less likely to be of great significance and this number could potentially be reduced to 25–30000. Discussion: Because total hip replacement has a greater than 90% success rate at 10 years in nearly all series this makes the numbers required for multivariate analysis much larger. Individual factors affecting survival will be difficult to identify unless large series are considered. Conclusion: The only way to reduce the numbers required for meaningful studies is to increase the matching of as many variables as possible to ensure that investigators conclusions are valid in the majority of small series orthopaedic studies. The use of Joint Registers is likely to be the only way of obtaining the volume of data required to detect individual factors affecting survival. Care will still need to be taken interpreting this data as there are still numerous variables which are not accounted for in the Joint Register

Conversion of failed femoral components of total hip resurfacing to conventional hip replacement is reportedly a straightforward procedure. There is little published to qualify this and what is available suffers from small study numbers and various combinations pre and post-operative implants. Between 1997 and 2002, the Oswestry Outcome Centre prospectively collected data on 5000 Birmingham Hip Resurfacings (BHRs) performed by 141 surgeons, at 87 hospitals. To date 4526 have survived, 135 died and 165 are lost to follow-up. 174 have been revised, of which 60 were failures of the femoral component. We reviewed modes of failure and post-revision clinical outcomes in this sub-group. Isolated femoral component failure accounted for 60 hips (1.2%). 28 femoral neck fractures, 14 femoral head collapses, 13 femoral component loosenings, 3 avascular necroses (AVN), 1 femoral loosening followed by fracture and 1 dislocation. Mean time to revision surgery was 2.6 years (1.8 years for neck fracture; 3.4 years femoral loosening, head collapse and AVN). All acetabular components were left in situ. At revision surgery 25 cemented, 25 uncemented and 10 unknown femoral prostheses were used with 56 BHR modular heads, 2 custom-made Exeter heads and 2 Thrust Plate heads. 47 patients completed outcome scores post-revision surgery. Median modified Harris Hip Score was 82 (IQ range=63–93) and Merle d’Aubigne score was 14 (IQ= 9.5–15) at a mean follow up of 3.9 years post-revision. The 4526 surviving resurfacings had a median hip score of 96 (IQ=87–100) p≤4.558x10-8 and median Merle score of 17 (IQ=14–18) p≤1.827x10-7. Mean 7.0 years follow up. There was no difference in outcomes between cemented and un-cemented revision components nor were there differences between fractured neck of femur and femoral loosening, head collapse or AVN. Following revision of the femoral component to a conventional hip replacement, function is significantly worse than surviving resurfacings

One of the most common early complications after hemiarthroplasty is dislocation, with an incidence of 2 to 4%. After dislocation the mortality and morbidity are significantly increased to in excess of 50%. It has been claimed that a bipolar hemiarthroplasty has a lower risk of dislocation than a unipolar implant. In addition it has been suggested that patients with either Parkinson’s disease or a previous stroke are at increased risk of dislocation. We investigated these claims by performing a comprehensive literature search of articles published in the last 40 years and data obtained from our own hip fracture database. From the literature review, 133 reports involving 21,872 patients were retrieved. A further 1235 hip fractures treated by hemiarthroplasty were recorded from our database. 791 (3.4%) dislocations were recorded. Dislocation rate for unipolar prosthesis was higher than bipolar prosthesis (3.9% versus 2.5%). Dislocation rate for posterior surgical approach was higher than for anterior approach (5.1% versus 2.4%). Dislocation rate for cemented prosthesis was 3.6% versus 2.3% in un-cemented prosthesis. However, the effect of the type of implant becomes non-significant on adjusting for the use of cement and surgical approach. The incidence of open reduction after dislocation was increased with bipolar implants. Patients with Parkinson’s disease showed a highly statistically significant increase in dislocation rate (8.7% to 3.4%). The dislocation rate with respect to ipsilateral hemiplegia was 1.6%. This study indicates there is no difference in the dislocation rate between a unipolar and bipolar prosthesis but if a bipolar prosthesis dislocates, there is an increased risk of failure to reduce the prosthesis by closed means. Patients with Parkinson’s disease are at an increased risk of dislocation but this is not the case for those with a hemiplegia. To minimise the risk of dislocation of a hemiarthroplasty, particularly in those patients with Parkinson’s disease, a unipolar hemiarthroplasty inserted via an antero-lateral approach is recommended

Introduction. Melorheostosis is a rare bone dysplasia characterized by its classic radiographic appearance resembling dripping candle wax. The condition was originally described by Leri and Joanny in 1922. Its etiology is not fully known and treatment in most instances has been symptomatic. There are nearly 350 reported cases on melorheostosis, joint replacement has been successfully attempted in the shoulder and knee joint. We describe a case of severe melorheostosis affecting the left hip causing secondary osteo-arthritis, which was treated with a total hip replacement (THR). To the best of our knowledge this is the first reported case of its kind in the World literature. Case history. A 52-year-old male of Indian origin with known melorheostosis of the left leg for over 30 years, presented with symptoms suggestive of severe osteo-arthritis of the left hip. Previously he had been treated for melorheostosis of the knee joint (fig 1a & 1b) with excisions and decompression of the medial femoral condyle. His left hip became more painful over the last few years. He had a fixed flexion deformity of 20° of the hip, severe muscle wasting and the affected leg was 3 cm longer than the right leg. Radiographs (fig 2a & 2b) confirmed the presence of sclerotic new bone in the acetabulum eroding the femoral head. He had the classical dripping candle wax appearance along the medial border of the neck and shaft of the femur. He underwent a THR using a Corail-Pinnacle un-cemented prosthesis using ceramic on polyethylene bearing surfaces (fig 3a & 3b). Post operatively he made a quick recovery and there was a marked improvement in his symptoms and functional outcome scores at 6 weeks. Discussion. Melorheostosis has an incidence of 0.9 in one million and affects men and women equally. It can affect any site in the body, however lower limbs are more commonly affected. It classically presents on only one side of the cortex of long bones. It is common in synovial joints and crosses the joint line in 35% cases. Its etiology is unknown and it is a benign condition but there are 3 reported cases in literature associated with malignancy. Chronic pain and deformity from melorheostosis can be severely debilitating for patients. Its management in most cases is conservative. Surgical intervention is advocated in chronic debilitating symptoms. Successful resection of these lesions can translate into near complete resolution of the symptoms. A Total hip replacement can be used to treat severe melorheostosis of the hip joint with complete relief of symptoms and achieving a good functional outcome in the short term

Rising health costs have seen increased emphasis on cost containment. Outpatient follow-up after total joint arthroplasty is one such accumulating cost. Enthusiastic recent media interest in failing implants and unacceptable waiting lists adds further interest to the area. We wished to determine the current post-operative follow-up practices and views of New Zealand Orthopaedic Surgeons. A postal survey was sent to all New Zealand Orthopaedic Surgeons. The response rate was 83% (131/158). There was wide variation in routine practice and beliefs. For cemented THJRs, 13% of surgeons routinely saw their patients for less than one year, 38% followed their patients for less than five years and 53% continued to see patients indefinitely. Follow-up for uncemented/hybrid prostheses was higher: 8% for < one year, 29% for < 5 years and 59% indefinitely. A system of periodically re-calling patients for x-rays without necessarily seeing them is used by 20% of surgeons. The most frequent reasons given for follow-up were the detection of osteolysis, wear, loosening and patient symptoms. Similar figures for total and uni-compartmental knee replacements were reported. Almost a third of surgeons reported that they were unable to follow-up their patients as they would like to because of resource limitations within the public health sector. 44% believed that future changes in medico-legal expectations will necessitate longer follow-up of patients. This survey demonstrates wide variation in practice. Higher follow-up rates for un-cemented/hybrid prostheses may reflect uncertainty about the long-term results. There is concern amongst surgeons that their ability to follow-up patients within the public health-care sector is constrained by cost. Periodic questionnaire and x-ray assessment was suggested by many as a possible alternative for long-term follow-up of selected patients. Few surgeons are however presently using such a system. We propose a standard of care

Aims

The Exeter V40 cemented polished tapered stem system has demonstrated excellent long-term outcomes. This paper presents a systematic review of the existing literature and reports on a large case series comparing implant fractures between the Exeter V40 series; 125 mm and conventional length stem systems.