There has been a renewed interest in surface replacement arthroplasty over the last decade, with the hope and expectation that this procedure would provide an advantage over conventional total hip arthroplasty, especially in the young, active patient. More specifically, the promises of surface replacement arthroplasty have been: 1) preservation of bone stock so that future revisions would be easier, 2) potential to be minimally invasive in their approach, 3) better functional outcomes because of the stability associated with a larger femoral head with potential associated proprioceptive advantages, and 4) improved survivorship. Unfortunately, these promises have not been realised. Surface replacement arthroplasty does maintain more initial bone stock on the femur, but also tends to remove more bone initially on the acetabular side. Long term, it is the loss of acetabular bone stock that is more problematic from a reconstructive perspective. Further, the “simple” revision afforded in surface replacement arthroplasty has led to reports of inferior clinical outcomes, especially with respect to subjective complaints of pain. Surface replacement arthroplasty is more invasive than conventional total hip arthroplasty as the femoral head is maintained and the window to the acetabulum is subsequently partially blocked. This is exacerbated by the fact that many of these patients are young active males. There is no compelling evidence that surface replacement arthroplasty offers improved functional outcomes over conventional total hip arthroplasty, particularly when considering gait and proprioception. Some studies have in fact shown inferior outcomes. The concept of the larger femoral head in surface replacement arthroplasty providing increased range of motion and subsequent better function is flawed as it is the head-to-neck ratio that appears to be a more important determinant of outcome in this sense. Total hip arthroplasty generally has a more favorable ratio. Surface replacement arthroplasty has inferior survivorship to conventional total hip arthroplasty, even when accounting for the younger age of this patient cohort. This finding is consistent across multiple national joint replacement registries. The outcomes and survivorship are particularly poor in females, with many authors now advocating that the procedure be reserved for males. Surface replacement arthroplasty has introduced several new problems and mechanisms of failures, most concerning of which is the formation of pseudotumors in some patients. It is unclear as to who is at risk for this significant complication, and the ability to diagnose and treat this disorder is difficult and still in evolution. Likely associated is the significant elevation of metal ions in the serum and urine of some surface replacement arthroplasty patients. Neck fractures and loss of bone stock around the femoral implant have also been noted as problematic for these devices. Some of these problems have led to specific surface replacement arthroplasty systems being recalled. Finally, surface replacement arthroplasties are premium products with associated increased costs, which, frankly, are not justified

Surface replacement of the hip was established in the 1970's as a bone preserving alternative to total hip replacement. However, problems with femoral neck fracture, osteolysis, and component loosening led to early failures and an abandonment of the procedure. The modern generation of hip resurfacing, however, has improved upon past results with new implant designs and materials. Better surgical guides and a short femoral stem allows for more accurate placement of the implants. A metal-on-metal articulation creates a larger diameter bearing and avoids polyethylene wear debris. Also paramount in the recent successes of surface replacement are refinements in surgical techniques, leading to more accurate component positioning, avoidance of neck notching, and an appreciation of the femoral head blood supply. The mid-term results of these newer hip resurfacing devices, coupled with appropriate patient selection and good surgical technique, have been encouraging. Although more recently surface replacement has come under fire because of the metal-on-metal articulation, the Australian National Joint Registry finds that a certain group of patients has greater survivorship with resurfacing than with total hip replacement. Therefore, the presenter feels that surface replacement arthroplasty is still a viable option in this subgroup of patients. Additionally, the benefits of surface replacement include the preservation of bone, a lower dislocation rate, and potentially a higher activity level

Surface replacement of the hip has become established as an alternative treatment to total hip replacement in the younger, active, male patient. By the very nature of preserving the femoral head and neck, there may be failures due to femoral neck fracture and femoral component loosening. Additionally, revisions of hip resurfacing for acetabular loosening may be necessary. Other scientific papers have described problems that may arise as a result of the metal-on-metal bearing either due to excess metal production or an immunologic-mediated reaction to the metal debris. Grammatopolous et al. describe poor results of revisions of surface replacements due to massive tissue destruction at the time of revision surgery, persistent pain, and swelling. In my experience with hip resurfacing, this complication is extremely rare. In my series of 925 resurfacings with a minimum of 2 year follow up, 12 revisions (1.3%) have been performed. Of these revisions, only 3 (0.3%) were for complications related to the metal-on-metal bearing; 2 for edge-loading and excess metal production, and 1 for metal hypersensitivity. None of the revision cases have had abductor destruction, or nerve/vascular involvement. Reconstruction of the joint was carried out with standard and revision components; post-operative function of these patients has been comparable to that of a primary total hip replacement. With careful monitoring of the post-operative resurfacing patient, problems can be identified early and surface replacement conversion can be performed with excellent results

The classic Hill-Sachs lesion is a compression or impression fracture of the humeral head in occurrence with anterior glenohumeral instability. The true incidence is unknown but clearly increases with recurrent instability episodes. Recent peer-reviewed literature has highlighted the importance of addressing “significant” humeral and glenoid bone defects in the management of glenohumeral instability. Quantification of the “significance” of a Hill-Sachs lesion with regard to location, size, and depth in relation to the glenoid has helped guide indications for surgical management. Options for managing Hill-Sachs lesions include both humeral-sided techniques (soft tissue, bone, and/or prosthetic techniques) and also glenoid-sided techniques (bone transfers to increase glenoid width). The majority of significant acute or chronic Hill-Sachs lesions can be effectively managed without prosthetic replacement. Is a prosthetic surface replacement ever indicated for the management of Hill-Sachs lesions? The peer-reviewed literature is sparse with the outcomes of this treatment, and significant consideration must be given to both the age of the patient and the need for such management when other effective non-prosthetic options exist. In a patient with more than half of the humeral head involved after instability episodes (perhaps seizure or polytrauma patients), metallic surface replacement arthroplasty may be an option that could require less involved post-operative care while restoring range of motion and stability

Total hip arthroplasty (THA) is among the most successful interventions in all of medicine and has recently been termed “The Operation of the Century”. Charnley originally stated that “Objectives must be reasonable. Neither surgeons nor engineers will ever make an artificial hip joint that will last 30 years and at some time in this period enable the patient to play football.” and he defined an appropriate patient as generally being over 65 years of age. Hip rating scales developed during this time were consistent with this approach and only required relief of pain and return to normal activities of daily living to achieve a perfect score. Since this time, however, hip arthroplasty has been applied to high numbers of younger, more active individuals and patient expectations have increased. One recent study showed that in spite of a good hip score, only 43% of patients had all of their expectations completely fulfilled following THA. The current generation metal-metal hip surface replacement arthroplasty (SRA) has been suggested as an alternative to standard THA which may offer advantages to patients including retention of more native bone, less stress shielding, less thigh pain due to absence of a stem, less limb length discrepancy, and a higher activity level. A recent technology review by the AAOS determined that currently available literature was inadequate to verify any of these suggested potential benefits. The potential complications associated with SRA have been well documented recently. The indications are narrower, the implant is more expensive, the technique is more demanding and less forgiving, and the results are both highly product and surgeon specific. Unless a clinical advantage in the level of function of SRA over THA can be demonstrated, continued enthusiasm for this technique is hard to justify. To generate data on the level of function of younger more active arthroplasty patients, a national multicenter survey was conducted by an independent university medical interviewing center with a long track record of conducting state and federal medical surveys. All patients were under 60, high demand (pre-morbid UCLA score > 6) and had received a cementless stem with an advanced bearing surface or an SRA at one of five major total joint centers throughout the country. The detailed questionnaire quantified symptoms and function related to employment, recreation, and sexual function. Patients with SRA had a higher incidence of noises emanating from the hip than other bearing surfaces although this was transient and asymptomatic. SRA patients were much more likely to have less thigh pain than THA, less likely to limp, less likely to perceive a limb length difference, more likely to run for exercise, and more likely to run longer distances. In another study of over 400 THA and SRA patients at two major academic centers, patients completed pain drawings that revealed an equivalent incidence of groin pain between THA and SRA, but an incidence of thigh pain in THA that was three times higher than in SRA in young active patients. While some or most of the observed advantages of SRA over THA may be attributable to some degree of selection bias, the inescapable conclusion is that SRA patients are demonstrating clinical advantages that warrants continued utilization and investigation of this procedure

Total hip arthroplasty is among the most successful interventions in all of medicine and has recently been termed “The Operation of the Century”. Charnley originally stated that “Objectives must be reasonable. Neither surgeons nor engineers will ever make an artificial hip joint that will last 30 years and at some time in this period enable the patient to play football.” and he defined appropriate patient as generally being over 65 years of age. Hip rating scales developed during this time were consistent with this approach and only required relief of pain and return to normal activities of daily living to achieve a perfect score. Since this time, however, hip arthroplasty has been applied to high numbers of younger, more active individuals and patient expectations have increased. One recent study showed that in spite of a good hip score, only 43% of patients had all of their expectations completely fulfilled following THA. The current generation metal-metal hip surface replacement arthroplasty (SRA) has been suggested as an alternative to standard THA which may offer advantages to patients including retention of more native bone, less stress shielding, less thigh pain due to absence of a stem, less limb length discrepancy, and a higher activity level. A recent technology review by the AAOS determined that currently available literature was inadequate to verify any of these suggested potential benefits. The potential complications associated with SRA have been well documented recently. The indications are narrower, the implant is more expensive, the technique is more demanding and less forgiving, and the results are both highly product and surgeon specific. Unless a clinical advantage in the level of function of SRA over THA can be demonstrated, continued enthusiasm for this technique is hard to justify. To generate data on the level of function of younger more active arthroplasty patients, a national multicenter survey was conducted by an independent university medical interviewing center with a long track record of conducting state and federal medical surveys. All patients were under 60, high demand (pre-morbid UCLA score > 6) and had received a cementless stem with an advanced bearing surface or an SRA at one of five major total joint centers throughout the country. The detailed questionnaire quantified symptoms and function related to employment, recreation, and sexual function. Patients with SRA had a higher incidence of noises emanating from the hip than other bearing surfaces although this was transient and asymptomatic. SRA patients were much more likely to have less thigh pain than THA, less likely to limp, less likely to perceive a limb length difference, more likely to run for exercise, and more likely to run longer distances. In another study of over 400 THA and SRA patients at two major academic centers, patients completed pain drawings that revealed an equivalent incidence of groin pain between THA and SRA, but an incidence of thigh pain in THA that was three times higher than in SRA in young active patients. While some or most of the observed advantages of SRA over THA may be attributable to some degree of selection bias, the inescapable conclusion is that SRA patients are demonstrating clinical advantages that warrants continued utilisation and investigation of this procedure

Hill-Sachs and reverse Hill-Sachs lesions come in different shapes and sizes, and their effect on “glenoid track” can vary. Small Hill-Sachs lesions that do not engage can be successfully treated with a Bankart repair alone done arthroscopically or open. Moderate, engaging, Hill-Sachs lesions can be treated either with the addition of remplissage to an arthroscopic Bankart or by adding the triple blocking effect of the Bristow-Latarjet procedure. Surface replacements vary in size from the small hemi-cap type of procedure to an entire humeral head replacement (HHR). These devices can be used as opposed to allograft replacement when the risk of post-reconstruction arthritis is high with the aforementioned more conventional treatment techniques. When 45% or more of the humeral head is involved with the lesion, or Outerbridge stage III and IV changes prevail, a HHR is preferred. An oval shaped HHR is the author's preference, and the long diameter can be used to provide coverage anteriorly or posteriorly and is particularly useful in large Hill-Sachs lesions associated with epilepsy

Metal-metal surface replacement (MoMSRA) is increasingly used in the young. Systemic metal ion release and its effects cause concern. Do metal ions cross the placenta in pregnant women with potential mutagenic effects? The hypothesis is that metal ions pass freely through the placenta and there is no difference in maternal and cord metal levels. This is a controlled cross-sectional study of women with MoMSRA. (n=25, mean age 32years, implantation 60months, 3 bilateral). The control group were 24 subjects with no metallic implant and not receiving cobalt/chromium supplements, mean age 31years. No patient was known to have renal failure. Whole blood specimens were obtained before delivery/ fluid-infusion and Cord blood specimens immediately after delivery. Cobalt and chromium were detectable in all specimens in both cohorts. In the control group, the difference between maternal and cord levels was only 5 to 7% indicating free passage. Study group cord levels were significantly lower than maternal cobalt, p<0.05 and chromium p<0.0001 thus rejecting the null hypothesis. The differences between maternal and cord metal ions in the controls indicate that normally the placenta allows an almost free passage of metal ions. The relative levels of metal ions in the maternal and cord blood in the study group reveal that the placenta exerts a modulatory effect on metal transfer

The Hill-Sachs lesion is a bony defect of the humeral head that occurs in association with anterior instability of the glenohumeral joint. Hill-Sachs lesions are common, with an incidence approaching nearly 100% in the setting of recurrent anterior glenohumeral instability. However, the indications for surgical management are very limited, with less than 10% of anterior instability patients considered for treatment of the Hill-Sachs lesion. Of utmost importance is addressing bone loss on the anterior-inferior glenoid, which is highly successful at preventing recurrence of instability even with humeral bone loss. In the rare situation where the Hill-Sachs lesion may continue to engage the glenoid, surgical management is indicated. Surgical strategies are variable, including debridement, arthroscopic remplissage, allograft transplantation, surface replacement, and arthroplasty. Given that the population with these defects is typically comprised of young and athletic patients, biologic solutions are most likely to be associated with decades of sustainable joint preservation, function, and stability. The first priority is maximizing the treatment of anterior instability on the glenoid side. Then, small lesions of less than 10% are ignored without consequence. Lesions involving 10–20% of the humeral head are treated with arthroscopic remplissage (defect filled with repair of capsule and infraspinatus). Lesions greater than 20% that extend beyond the glenoid tract are managed with fresh osteochondral allografts to biologically restore the humeral head. Lesions great than 40% are most commonly associated with advanced arthritis and deformity of the humeral articular surface and are therefore treated with a humeral head replacement. This treatment algorithm maximises our ability to stabilise and preserve the glenohumeral joint

It has been proposed that a major advantage of surface replacement is that it is easy to revise and that the outcome of such revisions is good. This seems logical as the femoral head can easily be removed, the acetabular component can be cut out and a primary hip replacement can be inserted. Indeed a number of studies have shown good outcome following revision, particularly for femoral neck fracture. When we initially reviewed the results of our revisions we found that the operations were straight forward and the results were good provided the reasons for revision were neck fractures, loosening, infection and causes other than soft tissue reactions. When the reason for revision was soft tissue reaction, otherwise known as pseudotumour, the outcome was unsatisfactory with poor hip scores, and high rates of complications, revisions and recurrences. These were generally a manifestation of the soft tissue damage caused by the pseudotumours. We therefor recommended that early revisions should be considered with soft tissue reaction. By undertaking revisions earlier we have found that the results have improved but there are still cases with poor outcomes

Introduction. Studies of metal-on-metal (MoM) hip resurfacing arthroplasty (HRA) have reported high complication and failure rates due to elevated metal ion levels. These rates were shown to be especially high for the Articular Surface Replacement (ASR) HRA, possibly due to its unique design. Associations between metal ion concentrations and various biological and mechanical factors have been reported. Component positioning as measured by acetabular inclination has been shown to be of especially strong consequence in metal ion production in ASR HRA patients, but few studies have evaluated acetabular anteversion as an independent variable. The primary objective of this study was to evaluate the associations between component orientation, quantified by acetabular inclination and anteversion, and blood metal ions. Secondly, we sought to report whether conventional safe zones apply to MoM HRA implants or if these implants require their own positioning standards. Methods. We conducted a multi-center, prospective study of 512 unilateral ASR HRA patients enrolled from September 2012 to June 2015. At time of enrollment our patients were a mean of 7 (3–11.5) years from surgery. The mean age at surgery was 56 years and 24% were female. All subjects had complete demographic and surgical information and blood metal ions. In addition, each patient had valid AP pelvis and shoot-though lateral radiographs read by 5 validated readers measuring acetabular abduction and anteversion, and femoral offset. A multivariate logistic regression was used with high cobalt or chromium (greater than or equal to 7ppb) as the dependent variable. The independent variables were: female gender, UCLA activity score, age at surgery, femoral head size, time from surgery, femoral offset, acetabular abduction, and acetabular anteversion. Results. The average acetabular inclination angle was found to be 44.7° (20.6°–64.5°), and the average anteversion angle was 24° (0.2°–55.3°) (Figure 1). After controlling for the possible confounding variables, the factors contributing to elevated metal ions (≥ 7 ppb) were found to be time from surgery (OR = 1.29, p = 0.011), high abduction angle (– 55°) (OR = 4.40, p = 0.001), low anteversion angle (0°–10°) (OR = 3.82, p = 0.001), and female gender (OR = 3.45, p = 0.001). Discussion and Conclusion. We found that blood metal ion levels are affected by both acetabular inclination and anteversion (Figure 2). Furthermore, we observed that there was a high degree of variation in the positioning of these implants, and we conclude that those with high inclination and/or low anteversion angle should be most vigilantly monitored

Cementless surface replacement arthroplasty (CSRA) is an established treatment for glenohumeral osteoarthritis. Few studies however, evaluate its role in cuff tear arthopathy. The purpose of this study is to compare the outcomes of CSRA for both glenohumeral osteoarthritis and cuff tear arthopathy. 42 CSRA with the Mark IV Copeland prosthesis were performed for glenohumeral osteoarthritis (n=21) or cuff tear arthopathy (n=21). Patients were assessed with Oxford and Constant scores, patient satisfaction, range of motion and radiologically with plain radiographs. Mean follow-up and age was 5.2 years and 74 years in both groups. Functional outcomes were significantly higher in OA compared with CTA with OSS improving from 18 to 37.5 and 15 to 26 in both groups respectively. Forward flexion improved from 60° to 126° and 42° to 74° in both groups. Three patients in the CTA group had a deficient subscapularis tendon, two of whom dislocated anteriorly. Humeral head resurfacing arthroplasty is a viable treatment option for glenohumeral osteoarthritis. In patients with CTA, functional gains are limited. We suggest CSRA should be considered in low demand patients where pain is the primary problem. Caution should be taken in patients with a deficient subscapularis due to the high risk of dislocation

The Hill-Sachs lesion is a bony defect of the humeral head that occurs in association with anterior instability of the glenohumeral joint. Hill-Sachs lesions are common, with an incidence approaching nearly 100% in the setting of recurrent anterior glenohumeral instability. However, the indications for surgical management are very limited, with less than 10% of anterior instability patients considered for treatment of the Hill-Sachs lesion. Of utmost importance is addressing bone loss on the anterior-inferior glenoid, which is highly successful at preventing recurrence of instability even with humeral bone loss. In the rare situation where the Hill-Sachs lesion may continue to engage the glenoid, surgical management is indicated. Surgical strategies are variable, including debridement, arthroscopic remplissage, allograft transplantation, surface replacement, and arthroplasty. Given that the population with these defects is typically comprised of young and athletic patients, biologic solutions are most likely to be associated with decades of sustainable joint preservation, function, and stability. The first priority is maximising the treatment of anterior instability on the glenoid side. Then, small lesions of less than 10% are ignored without consequence. Lesions involving 10–20% of the humeral head are treated with arthroscopic remplissage (defect filled with repair of capsule and infraspinatus). Lesions greater than 20% that extend beyond the glenoid tract are managed with fresh osteochondral allografts to biologically restore the humeral head. Lesions great than 40% are most commonly associated with advanced arthritis and deformity of the humeral articular surface and are therefore treated with a humeral head replacement. This treatment algorithm maximises our ability to stabilise and preserve the glenohumeral joint

Total hip arthroplasty is among the most successful interventions in all of medicine and has recently been termed “The Operation of the Century”. Charnley originally stated that “Objectives must be reasonable. Neither surgeons nor engineers will ever make an artificial hip joint that will last 30 years and at some time in this period enable the patient to play football.” and he defined the appropriate patient as generally being over 65 years of age. Hip rating scales developed during this time were consistent with this approach and only required relief of pain and return to normal activities of daily living to achieve a perfect score. Since this time, however, hip arthroplasty has been applied to high numbers of younger, more active individuals and patient expectations have increased. One recent study showed that in spite of a good hip score, only 43% of patients had all of their expectations completely fulfilled following THA. The current generation of metal-metal hip surface replacement arthroplasty (SRA) has been suggested as an alternative to standard THA which may offer advantages to patients including retention of more native bone, less stress shielding, less thigh pain due to absence of a stem, less limb length discrepancy, and a higher activity level. A recent technology review by the AAOS determined that currently available literature was inadequate to verify any of these suggested potential benefits. The potential complications associated with SRA have been well documented recently. The indications are narrower, the implant is more expensive, the technique is more demanding and less forgiving, and the results are both highly product and surgeon specific. Unless a clinical advantage in the level of function of SRA over THA can be demonstrated, continued enthusiasm for this technique is hard to justify. To generate data on the level of function of younger more active arthroplasty patients, a national multicentre survey was conducted by an independent university medical interviewing centre with a long track record of conducting state and federal medical surveys. All patients were under 60, high demand (pre-morbid UCLA score > 6) and had received a cementless stem with an advanced bearing surface or an SRA at one of five major total joint centres throughout the country. The detailed questionnaire quantified symptoms and function related to employment, recreation, and sexual function. Patients with SRA had a higher incidence of noises emanating from the hip than other bearing surfaces although this was transient and asymptomatic. SRA patients were much more likely to have less thigh pain than THA, less likely to limp, less likely to perceive a limb length difference, more likely to run for exercise, and more likely to run longer distances. While some or most of the observed advantages of SRA over THA may be attributable to some degree of selection bias, the inescapable conclusion is that SRA patients are demonstrating clinical advantages that warrants continued utilisation and investigation of this procedure

Introduction. A metal ion study was undertaken in patients who had received an articular surface replacement. The design of these components is optimised in line with lubrication theory and produces low levels of wear in hip joint simulators. Methods. Patients were recruited in four centres. Whole blood samples were analysed for metal ion levels using high resolution ICP-MS (inductively coupled plasma mass spectrophotometry). A total of 75 patients was enrolled into the study and 65 and 47 patients were assessed after 12 and 24 months implantation respectively. Results are included irrespective of clinical outcome. Results. The 12 and 24 month median ion levels were 1.4 μg/l and 1.6 μg/l respectively for chromium and 1.5(μg/l and 1.6 μg/l respectively for cobalt. The pre-operative levels were 0.38(μg/l and 0.34(μg/l for chromium and cobalt respectively. Twenty-seven percent of patients had a pre-operative chromium level that was higher than the 24 month median level. Similarly the value for cobalt was seven percent. However close examination of the data shows that it is skewed by 6 outliers with cobalt or chromium levels greater than 10(μg/l after 24 months implantation. This appears to be related to acetabular component placement. Patients with acetabular components implanted at a high inclination angle (>55deg) are more likely to have elevated metal ion levels compared with a standard angle (<55deg). In the 24 month group two patients (both outliers) have been revised. Furthermore, the high metal ion levels at 24 months could be predicted by intermediate levels after 12 months. Conversely those levels below 10ug/l had already stabilised after 12 months in vivo. Conclusion. Large diameter metal-on-metal bearing with optimised tolerances can produce very low blood metal ion levels. However, in line with other studies, mal-positioning of components may lead to significantly elevated levels of wear and hence blood metal ions

Introduction. While fixation on the acetabular side in resurfacing implants has been uncemented, the femoral component is usually cemented. The most common causes for early revision in hip resurfacing are femoral head and or neck fractures and aseptic loosening of the femoral component. Later failures appear to be more related to adverse soft-tissue reactions due to metal wear. Little is known about the effect of cementing techniques on the clinical outcome in hip resurfacing, since retrieval analysis of failed hip resurfacing show large variations. Two cementing techniques have dominated. The indirect low viscosity (LV) technique as for the Birmingham Hip resurfacing (BHR) system and the direct high viscosity (HV) technique as for the Articular Surface replacement (ASR) system. The ASR was withdrawn from the market in 2010 due to inferior short and midterm clinical outcome. This study presents an in vitro experiment on the cement mantle parameters and penetration into ASR resurfaced femoral heads comparing both techniques. Methods. Five sets of paried frozen cadavar femura (3 male, 2 female) were used in the study. The study was approved by ethics committee. Plastic ASR replicas (DePuy, Leeds, UK), femoral head size 47Ø were used. The LV technique was used for the right femora (Group A, fig. 1 and 3) while the HV technigue was used for the left femora (Group B. Fig 2 and 4). The speciments were cut into quadrants. An initiial visual, qualitative evaluation was followed by CT analysis of cement mantle thickness and cement penetration into bone. Results. No significant differences were seen between the four quadrants within each group. The LV technigue resulted in greater cement penetration and increased cement mantle under the top proximally. The HV technique showed less penetration and lower cement mantle. See figures 1–4. Discussion. The aim was to analyze the effect of the cementing techniques used in hip resurfacing practice. The ASR implant was chosen to improve understanding of whether the implant may have been sensitive to cementing techniques and whether an analysis of cementing with the recommended HV technique may assist in explaning the high incidence of short-term ASR revisions due to fractures. Findings for the HV technigue would indicate a superior technique according to consensus in conventional arthropalsty However, this contradicts clinical evidence on resurfacing, where LV cementation has been shown tho be superior. The superficial intergration in the HV technigue may result in only a superficial integration and subsequently suboptimal fixation to bone. To view tables/figures, please contact authors directly

Hip resurfacing presents advantages and disadvantages compared to total hip arthroplasty. Dislocation and leg length discrepancy, common complaints with total hips, are unusual following resurfacing. Bone stock in the proximal femur is retained, and revision options on the femoral side of a resurfacing are much better.

Concerns persist regarding adverse tissue reactions to metal debris.

Conflicting data abounds regarding ultimate hip function, patient satisfaction, durability, etc. Yet all of these would be rendered irrelevant if resurfacing carried with it greater life expectancy. We would not speak of survivorship of the implant, but survival of the patient. Instead of quality of life, let us preserve life itself.

Beginning in 2010, the UK Registry reported improved mortality rates at 90 days and five years after hip resurfacing compared with total hip replacement. This persisted after multivariate analysis for several covariables, including age, gender, health status, type of device, provider, and country. Recently, the 2016 Australian Registry Mortality Supplement showed similar results, corrected for age and gender.

Analysis of UK data by the designing surgeons of the Birmingham device, and an independent group of Oxford statisticians confirmed the lower mortality rate in patients treated with resurfacing vs. total hip replacement. Possible reasons for these differences include greater post-operative activity, longer stride length, less fat and marrow embolism, or perhaps more internet-savvy, health-conscious patients seeking out a resurfacing procedure.

Mid-term data from the US is now starting to come in, and mortality benefits are being confirmed in a series of patients from a large, academic center. Should there be a confirmed mortality advantage of resurfacing over total hip replacement, more surgeons and patients would be interested in this procedure, and new materials and techniques may follow.

Hip resurfacing using metal-on-metal bearings has a number of purported advantages over traditional total hip replacement in the young, active patient. Males in particular can benefit from the bone preservation, stability, and higher activity levels seen with this procedure. As more is learned about the factors affecting long-term outcome of hip resurfacing, component position has emerged as one major predictor of success.

Given a well-selected patient, and a well-designed device, acetabular positioning is perhaps the most important determinant of long-term survivorship in hip resurfacing. One feature of resurfacing socket design which has not been widely disseminated is the sub-hemispheric arc of the bearing surface. While the outer circumference of the socket represents a complete hemisphere, and radiographic evaluation may assume that the apparent socket angle is satisfactory, the actual bearing is less than a hemisphere, so that the true abduction of the bearing is considerably more vertical. This important fact leads to excessive bearing inclination, edge loading, and all that follows, including runaway wear, metallosis, ALVAL, and pseudotumors.

Inadequate socket anteversion can expose the psoas tendon to abrasion and tendonitis. Too much acetabular anteversion, especially when combined with increased femoral neck anteversion, can result in an overall decrease in bearing contact area, and excessive wear.

Femoral component positioning is critical in the prevention of femoral neck fractures, which are a chief cause of early failure. Varus placement increases the tensile stresses on the superior femoral neck. Excessive valgus threatens notching. Both increase femoral neck fractures.

Sufficient malposition will ultimately result in edge loading. Edge wear is incompatible with fluid film lubrication, the key to longevity of these bearings.

Introduction

Complication and revision rates have shown to be high for all metal-on-metal (MoM) bearings, especially for the ASR Hip System (ASR hip resurfacing arthroplasty (HRA) and ASR XL total hip arthroplasty (THA)). This prompted the global recall of the ASR Hip System in 2010. Many studies have previously explored the association between female gender and revision surgery MoM HRA implants; yet less research has been dedicated to exploring this relationship in MoM THA.

The first purpose of this study was to assess the associations between gender and implant survival, as well as adverse local tissue reaction (ALTR), in patients with MoM THA. Secondly, we sought to report the differences between genders in metal ion levels and patient reported outcome measures (PROMs) in patients with MoM THA.

Resurfacing arthroplasty of the hip enjoyed a resurgence of enthusiasm. A recent article has documented that the media played a significant role in its popularity, making claims that were not substantiated in scientific literature. Proponents of resurfacing arthroplasty state that it is bone conserving, provides greater stability, enhances range of motion, leads to a more normal gait, facilitates increased activity levels, decreases risk of dislocation, decreases the risk of leg length discrepancy and find that it is easier to insert in the face of deformity or retained hardware. The naysayers state that it is a more difficult operative procedure associated with a higher learning curve. They note that there are few patients who meet the selection criteria and there is an increased risk of fracture of the femoral neck. Finally, there is concern over metal ion toxicity and adverse tissue reaction. Furthermore, as we explore the literature, several studies have observed that resurfacing requires a bigger cup and results in a significantly higher volume of normal bone reamed from the acetabulum. Other studies note decreased range of motion with resurfacing compared with total hip arthroplasty (THA) secondary to an unfavourable head to neck ratio resulting in increased impingement. While resurfacing is purported to enhance functional outcomes, one randomized trial of 48 patients, 24 each resurfacing and large head THA, compared with 14 healthy control subjects found no difference in gait speed and postural balance evaluations, functional test, and clinical data at 3, 6 and 12 months post-operative. In another study comparing 337 resurfacings with 266 ceramic-on-ceramic THA, at 24 months there was no difference in Harris hip score, pain score or function score, but a statistically greater improved Harris hip range of motion score in THA. In a large meta-analysis study comparing 3269 hip resurfacings (3002 patients) with average follow-up of 3.9 years to 5907 cementless THA (5907 patients) with average follow-up of 8.4 years, the observed rate of femoral revision due to mechanical failure was 2.6% for resurfacing versus 1.3% for THA, yielding annualized rates of 0.67% and 0.15% respectively. An analysis of hip resurfacing data from national joint registries found that hip resurfacing demonstrates an overall increased failure rate compared with THA, except in males younger than 65 years old having a diagnosis of primary osteoarthritis and except with head diameters larger than 50 mm, which may be especially relevant as a contraindication for use of the procedure in female patients.