Background. Hip arthroscopy is well established as a diagnostic and therapeutic tool in the native hip joint. However, its application in the symptomatic post-hip arthroplasty patient is still being explored. Aims and Methods. We have described the use of hip arthroscopy in symptomatic patients following total hip replacement, resurfacing hip arthroplasty and partial resurfacing hip arthroplasty in 24 patients (study group), and compared it with arthroscopy of the native hip of 24 patients. Results. The diagnostic yield of hip arthroscopy in symptomatic post-arthroplasty patients was 95.8% (23 / 24) and a therapeutic arthroscopic intervention resulted in relief of symptoms in 41.6% (10 / 24) of the patients. It led to revision hip replacement in a further 29.1% (7 / 24). In contrast, hip arthroscopy of the native hip (control group) had a 100% diagnostic yield and an arthroscopic therapeutic intervention was carried out in all the patients resulting in symptomatic relief in 87.5% (21 / 24). The mean operative time in the study group (59.7 mins, SD 21.1) was less than the control group (71 mins, SD 17.1, p < 0.05) but the arthroscopic approach was more difficult. Conclusion. The authors suggest the use of hip arthroscopy in well-investigated symptomatic post-arthroplasty patients with an elusive diagnosis (Fig. 1: Arthroscopic image showing a THR in situ (Furlong, JRI, London, UK) with a ceramic femoral head (yellow arrow), ceramic acetabular liner (white arrow), florid metallosis (red arrow) and corrosion on the femoral neck (green arrow) because of impingement against the margin of the acetabular component.) and also describe the technical modifications necessary with various types of hip arthroplasty

Background. Since the development of modern total hip replacement (THR) more than 50 years ago, thousands of devices have been developed in attempt to improve patient outcomes and prolong implant survival. Modern THR devices are often broadly classified according to their method of fixation; cemented, uncemented or hybrid (typically an uncemented acetabular component with a cemented stem). Due to early failures of THR in young active patients, the concept of hip resurfacing was revisited in the 1990's and numerous prostheses were developed to serve this patient cohort, some with excellent clinical results. Experience with metal-on-metal (MoM) bearing related issues particularly involving the ASR (DePuy Synthes, Warsaw, Indiana) precipitated a fall in the use of hip resurfacing (HR) prostheses in Australia from a peak of 30.2% in 2004 to 4.3% in 2015. The effects of poorly performing prostheses and what is now recognised as suboptimal patient selection are reflected in the AOANJRR cumulative percent revision (CPR) data which demonstrates 13.2% revision at 15 years for all resurfacing hip replacements combined; with 11 different types of hip resurfacing prostheses recorded for patients less than 55 years of age and a primary diagnosis of OA. When this data is restricted to only those prostheses currently used in Australia (BHR; Smith and Nephew, Birmingham, UK & ADEPT; MatOrtho Ltd, Surrey, UK) there is a CPR of 9.5% at 15 years for all patients. Despite these CPR results, recognition is emerging of the important distinction between MoM THR and resurfacing. Furthermore, in light of current consensus for patient selection and the surgical indications for resurfacing, a gender analysis demonstrates a CPR for females of 14.5% at 10 years compared to 3.7% for males. Similar difference for head size >50mm with 6% CPR at 10 years compared to 17.6% for head size <50mm (HR=2.15; 1.76, 2.63; p<0.001). Leading to renewed interest in resurfacing particularly in the young, active male. In addition to registry based CPR data, several studies have concluded that a true difference in mortality rates between HR and other forms of THR exists independent of age, sex or other confounding factors. We hypothesised that a difference in adjusted mortality rates between HR and other forms of THR may also be present in the Australian population. We undertook an ad hoc data report request to the AOANJRR. The data set provided was deidentified for patient, surgeon and institution and included all HR and conventional THR procedures performed for the diagnosis of primary osteoarthritis recorded in the Registry since inception in 1999. We requested mortality and yearly cumulative percent survival (CPS) of patients for primary HR and THR with sub-group analysis by the mode of fixation. There were 12,910 hip resurfacings (79% male) compared to 234,484 conventional THR (46.8% male) over the study period. When adjusted for age and gender over the 15 years of available data, there was a statistically significant difference in cumulative percent survival (CPS) between conventional THR and hip resurfacing (HR 1.66 (1.52, 1.82; p<0.001)) and between cemented THR and hip resurfacing (HR 1.96 (1.78, 2.43; p<0.001)); between uncemented THR and hip resurfacing (HR 1.58 (1.45, 1.73; p<0.001)); and between hybrid THR and hip resurfacing (HR 1.82 (1.66, 1.99; p<0.001)). When adjusted for age, gender and ASA over the 3 years data available, there was no statistically significant difference in CPS between hip resurfacing and any individual fixation type of THR. Discussion. The results demonstrate a statistically significant adjusted survival advantage for hip resurfacing compared to conventional THR and between fixation methods for THR. These findings are consistent with previous studies. While a difference in adjusted mortality rate appears to exist, we are yet to definitively determine the complex interplay of causative factors that may contribute to it

Introduction:. Significant proximal femoral remodeling occurs after total hip arthroplasty (THA), with regions of bone loss, and regions of hypertrophy. This study compared three implants for changes in femoral bone mineral density over 2 years following primary uncemented hip arthroplasty with a conventional stem (THA), a novel femoral neck-sparing short hip stem (NS-THA), and resurfacing hip arthroplasty (RHA). Methods:. Seventy-one patients participated in this non-randomized, prospective study. All patients had a diagnosis of osteoarthritis and underwent primary uncemented hip arthroplasty. Dual Energy XRay Absorptomitry (DXA) scans were performed at preoperative, 3–7 days post-op, 6 weeks, 6 months, one, and two years post-op. Using custom 2 cm zones, 19 zones were observed for percent changes in bone mineral density (BMD). Radiographs and Harris Hip scores were obtained at each visit. Results:. Age, gender, and BMI were found to be statistically different with fewer females and lower age in the RHA group, and a lower age in the NS-THA group. In all three groups, regions that were located proximally were shown to be the most susceptible to bone loss. Combined 2 cm zones 1C/7C, 2A/6A, and 2B/6B showed statistical significance (p < 0.05). Bone loss in the proximal regions was 8–10% lower with the femoral neck-sparing short stem, and least in the RHA group, causing little to no BMD loss in proximal regions. Radiographic outcomes and clinical results including Harris Hip scores were equal between the groups. Conclusion:. Consistent with our hypothesis, it was found that hip arthroplasty with a conventional stem resulted in the highest proximal femoral bone loss, and resurfacing arthroplasty was associated with the least bone loss. The femoral neck-sparing short stem ameliorated the bone loss seen with traditional hip arthroplasty, and approximated the bone preservation seen with hip resurfacing. The short stem neck-sparing device may provide some of the benefits of hip resurfacing, but could potentially have wider indications for use

Background. Correct positioning of the femoral component in resurfacing hip arthroplasty (RHA) is an important factor in successful long-term outcomes. The purpose of computer-assisted navigation (CAS) in resurfacing is to insert the femoral neck guide wire with greater accuracy and to help size the femoral component, thus reducing the risk of notching at the head and neck junction. Several recent studies reported satisfactory precision and accuracy of CAS. However, there is little evidence that CAS is useful in the presence of anatomical deformities of the proximal femur, which is frequently observed in young patients with secondary degenerative joint disease. Aim. The purpose of this in vitro study was to determine the accuracy of an image-free RHA navigation system in the presence of angular deformity of the neck, pistol grip deformity of the head and neck junction and slipped upper femoral epiphysis deformity. Methods. An artificial phantom leg was used. Implant-shaft angles for the guide wire of the femoral component reamer were calculated, in frontal and lateral planes, with the computer navigation system and an electronic caliper combined with micro-CT. Results. With both normal anatomy and angular deformity we found close agreement between the CAS system and our measurement system. There was a consistent disagreement on both planes for the pistol grip deformity. In the presence of the slipped upper femoral epiphysis deformity, close agreement was found only on the frontal plane but calculation of the femoral head size was inaccurate. Conclusion. This is the first study designed to assess the accuracy of a femoral navigation system for RHA in the presence of anatomical deformity of the proximal femoral head and neck segment. Our data suggests CAS technology should not be used to expand the range of utilisation of resurfacing surgery to these cases but rather to improve the surgical outcome in those with suitable anatomy

Background. Hip replacement surgery is an effective treatment, however quantitative outcome does not necessarily delineate the true picture. It is important to triangulate data methods in order to ascertain important contextual factors that may influence patient perception. Aims. The aim of the current study was to explore the patient perception on resurfacing hip arthroplasty (RHA) and mini-hip arthroplasty (MHA) in a unique cohort where each patient has received a resurfacing on one side and a mini-hip on the contralateral side using both quantitative and qualitative measures (Fig. 1). Materials and methods. We identified patients in our Practice database that had undergone RHA on one side and MHA in the opposite hip. All prostheses were implanted by two experienced surgeons using a posterior approach and followed a standard anaesthetic protocol, post-operative care and rehabilitation guidelines. The patients received Cormet 2000 hip resurfacing and MiniHip (Corin®, Ciencester, UK) implants. Data were collected pre-operatively and post-operatively at weeks 6, 12, 26 52 and annually thereafter. The data included demographic details, mHHS (modified Harris Hip Score), patient satisfaction and a qualitative semi-structured interview. Data analysis was done using both quantitative (descriptive statistics, student's t-test) and qualitative (constant comparative method of grounded theory). Results. There were 24 hips in 12 patients with mean age of 63.6 years (range 42,81) and a mean follow-up of 5.3 years (SD 4.2). The mean mHHS in pre-operative and one-year post-operative period for RHA was 50.9 (SD 22.9, range 9,71) and 82.6 (SD 11.2, range 67,91) respectively with a mean improvement of 32.9. The mean mHHS in pre-operative and one-year post-operative period for MHA was 47.83 (SD 14.6, range 20,62) and 83.2 (SD 27.3 range 53,94) respectively with mean improvement of 35.3. There was no significant difference in mHHS in the two groups (p=0.26). However, the qualitative analysis showed that a patient's perception of improvement did not always reflect the validated score improvement such as in mHHS. In 8/24 of arthroplasty cases the mHHS indicated a high return to functionality, however, interview highlighted perception of a reduction in certain aspects such as range of movement and ability to perform at a high-level such as competitive windsurfing (2/24), skiing (6/24) or martial arts (2/24). The results, therefore, suggest that the quantitative data is not sensitive enough to deduce return to function in a specialised subset of patients. The interviews indicate a marginal preference for resurfacing due to improved stability. However, the differential to the satisfaction with the mini hip was not sufficient for the potential metal ion problem to be ignored and therefore mini hip was shown to offer a reasonable bone-conserving alternative. Conclusions. Results indicate the need for more than just a quantitative score to demonstrate satisfaction and that RHA generally offers better results although when the metal ion problem is taken into account the MHA can offer sufficient function and satisfaction as an alternative

Comparisons of blood metal ion levels of cobalt and chromium (CoCr) between metal-on-metal total and resurfacing hip arthroplasties are limited. High levels of CoCr may result in long-term adverse biological effects. We compare metal ions levels between total and resurfacing implants. 70 patients (28 males and 42 females) had a total hip arthroplasty using the Birmingham (Smith & Nephew) modular femoral component and a variety of stems, articulating with the Birmingham resurfacing component. The average age was 65.5 (±6.8) years and an average follow-up of 6.0 (±2.2) years. 170 patients (145 male and 25 female had a Birmingham resurfacing arthroplasty with an average age of 54.7 (±9.9) years and an average follow-up of 5.9 (±3.0) years. CoCr levels were measured. Bivariate correlations and independent samples t-tests were applied to determine similarities and differences within and between groups. Average ion levels in total arthroplasty patients were: Co 114.17 (±94.01) nmol/L (range 2–414); and Cr 75.12 (±68.45) nmol/L (range 10–312). Average levels in hip resurfacing arthroplasty were: Co 55.98 (±79.5) nmol/L (range 7–505); and Cr 70.77 (±87.41) nmol/L (range 5–751). Both total and resurfacing groups showed significant correlations (p<0.01) between Co and Cr levels. A significant difference was observed between the total and resurfacing group Co levels (p<0.0001). No significant difference was shown between group Cr levels (p>0.672). The average total hip replacement CoCr levels were higher than the hip resurfacing levels. While the overall activity level may be higher in the resurfacing group, possibly the incidence of stop/start frequency may be higher in the total hip replacement group. Hip resurfacing arthroplasty average CoCr levels are lower than those of total hip replacement patients. Associations between Co and Cr metal ion levels are shown within each group. Co levels differ significantly between groups where Cr does not. Long-term follow-up of CoCr levels are required

Introduction. Sir John Charnley introduced his concept of low friction arthroplasty— though this did not necessarily mean low wear, as the initial experience with metal on teflon proved. Although other bearing surfaces had been tried in the past, the success of the Charnley THR meant that metal-on-polyethylene became the standard bearing couple for many years. However, concerns regarding the occurrence of peri-prosthetic lysis secondary to wear particles lead to consideration of other bearing surfaces and even to the avoidance of cement (although this has proven to be erroneous). Bearing combinations include polymers, ceramic and metallic materials and are generally categorised as hard/soft or hard/hard. In general, all newer bearing surface combinations have reduced wear but present with their own strengths and weaknesses, some of which are becoming more apparent with time. Bearing surfaces must have the following characteristics: low wear rate, low friction, Biocompatibility and corrosion resistance in synovial fluid. Hard/soft. Femoral head components are generally made of cobalt, chromium alloy, either cast or forged. Both alumina and zirconia ceramics have been used as femoral head materials and the hardness is thought to reduce the incidence of surface damage to the femoral head. The hard femoral heads have been traditionally matched with conventional ultra high molecular weight polyethylene. (UHMWPE) which has been produced by either ram extrusion or compression moulding. Over the past 10 years, most implant companies have moved to highly cross-linked UHMWP which in both laboratory and human RCTs have shown appreciably less wear. Hard/hard bearings – Metal-on-metal (M-O-M). The first generation of metal bearings were based on stainless steel couples but the metal on metal design by. McKee-Farrar was made from CoCrMo alloy with large head diameters. The second generation M-O-M bearing were introduced by Weber using wrought. CoCrMo alloy with low surface roughness and wear rates about 100 to 200 times less than traditional metal/UHMWPE. The re-introduction of resurfacing hip arthroplasty has been made possible by the improvement in metal technology. Concerns however exist with the long term biologic effects of metal ions, the reported incidence of sensitivity reactions to metal and the more demanding techniques required for implantation. Ceramic on Ceramic (C-O-C). Alumina ceramic bearing surfaces are extremely hard, have high wear resistance and reported low concentration of wear particles in peri-prosthetic tissues. Unlike M-O-M there is no ion release. While the reported fracture rate for ceramic couplings is extremely low their proper implantation is important to minimise impingement. There is an incidence of squeaking not seen in other bearing couples and because of the hardness of the bearing, long term concerns with stress shielding of bone remain. Clinical outcomes. Data will be presented from the Australian Orthopaedic. Association National Joint Replacement Registry on clinical outcomes of bearing surfaces. Overall metal on UHMWPE has the least revision of any bearing surface couple used with conventional hip replacement. Future trends. Further research into hard/soft bearings will look at ways to reduce UHMWPE wear without compromise of clinical results based on over 40 years use. Hard-on-hard bearings may focus on combining the best features of both. M-O-M and C-O-C couplings without fracture risk or metal iron release. When deciding which bearing surface is suitable for your patients it must be emphasised that wear reduction is only one of several considerations when taking into account the most appropriate implant

Introduction. Current standard cups of metal on metal resurfacing hip arthroplasty (RHA) have no dome holes and it is very difficult for surgeons to confirm full seating of these cups. This sometimes results in gap formation between the cup and acetabular floor. Although the incidence of initial gaps using modular press-fit cups with dome screw holes has been reported to range from 20 to 35%, few studies have reported the incidence of gap formation with monoblock metal cups and its clinical consequences in RHA. The purpose of this study was to investigate retrospectively the incidence of initial gap formation and whether the initial gap influences the clinical results in RHA. Material and Method. RHA was performed on 166 hips of 146 patients using the Birmingham Hip Resurfacing (BHR) (MMT, UK) between 1998 and 2007. Mean age at operation was 48.7 years (range, 19-85 years). Mean duration of follow-up was 6.9 years (2.0-10.6). Acetabular reaming was performed with the use of hemispherical reamers and the reamer size was increased up to an odd number diameter which provided tight rim fit in the antero-posterior direction. The same size hemispherical provisional cup with dome holes and slits was used to check the cavity for complete seating. If the provisional cup could not be seated on the floor, reaming was repeated with the same reamer to remove the rim bump until full seating was achieved. Acetabular cups of 1mm larger diameter were impacted into the acetabulum by a press-fit technique. After press-fit fixation, the stability of the cups was confirmed with a synchronized movement of the pelvis and the cup inserter by applying a gentle torque. Clinical evaluation was performed using WOMAC at the latest follow-up. Radiographic assessments were performed using radiographs immediately after the surgery, at 3 weeks, 3 months, 1 year, and then annually thereafter. We evaluated the height of the gap between the cup and acetabular surface, cup inclination angle, cup migration and the time to gap filling. To investigate the relationship between the magnitude of the gap and the radiographic results, the patients were divided into two groups according to the height of the initial gap; the cases with a gap of less than 3 mm on the initial radiograph were grouped into a small gap group, the cases with a gap of 3mm or more were grouped into a large gap group. We compared the changes in the height of the gap, in the cup inclination angle and the cup migration between the groups. Results. Gaps were identified in 21 of 166 hips (13%) on the postoperative radiograph. The average height of the gaps was 2.4 mm (0.56-4.5mm). Of the 21 hips with gaps, there was no revision during the follow up period. 12 of the 21 hips were classified into the small gap group, 9 of the 21 hips were classified into the large gap group. In the small gap group, there were no changes of cup inclination angle of more than 3 degrees nor was there cup migration of more than 3mm. On the other hand, in the large gap group, 6 of the 9 hips showed reductions of the cup inclination angle of more than 3 degrees with 3mm or more of migration during the initial 3 months (P<0.05). After 3 months, neither progressive angle change nor migration of the cup were observed. All acetabular components were judged to be bone ingrown at the last follow up. Conclusions. The incidence of initial postoperative gaps (13%) of this series is similar to that of modular cementless cups fixed with press-fit technique. There were no serious clinical consequences of the initial gap during the 6.9 year follow up. However, gaps of 3mm or more led to early migration of the acetabular component and change in inclination angle