The radiographic analysis of over 5000 metal on metal (MoM) hips using Ein Bild Roentgen Analyse (EBRA) software have been recently published in an attempt to determine the influence of cup orientation on bearing function. The validation of this software relies one study, conducted in a phantom pelvis without a femoral head in situ. Three dimensional computed tomographic (3D-CT) has been shown to be more accurate for hip and knee arthroplasty than plain radiographs for measurements of component orientation and position. The accuracy of
This study aimed to compare the early clinical results and stem subsidence between three consecutive series of revision hip replacement cases with femoral impaction bone grafting to evaluate the effects of developments in technique. In the original series 1 (n=23), bone graft was irradiated at 25kG. I n series 2 (n=12) non-irradiated double washed graft and long stems were used as required. In series 3 (n=21) modular tamps were used. Sensitive radiographic analysis techniques,
Femoral head diameters in THA have been increasing due to good long-term outcomes of 1st generation HXLP cups. Furthermore, some 2nd generation HXLP cups allow 36mm or larger heads. However, larger femoral head diameters increase the frictional torque and may lead to early cup migration and loosening. And there is a concern that larger head diameters and reduced liner thickness may increase polyethylene wear. In this study, we compared early acetabular component migration and wear rates between a group of larger heads using a 2nd generation HXLP and a group smaller heads using a 1st generation HXLP. The larger head group comprising 30 hips underwent THA between February 2010 and March 2011 with the use of a sequentially cross-linked polyethylene liner (X3). 30 patients were included in this study (30 women). Their mean age was 59.3years; mean weight was 53.6kg. Trident HA-coated cementless cups were used and the sizes ranged from 46mm to 56mm (mean 50.5mm). The head diameters were 36mm in 23hips, 40mm in 5 hips, and 44mm in 2hips. All X3 liners were 5.9mm or less in thickness. A control group was selected from a previous case series that had undergo THA between July 2007 and January 2008 using a 1st generation HXLP liner (Crossfire) by matching age and sex. Therefore 30 patients were included in this study (30 women) too. Their mean age was 60.0 years; mean weight was 55.5kg. The same Trident cups were used and the sizes ranged from 46mm to 56mm (mean 49.5mm). The head diameters were 26mm in 19hips and 32mm in 11hips. The liner thicknesses were 7.8mm or more. All hips had standardized anteroposterior pelvic digital radiographs performed postoperatively and cup migration was measured on digital radiographs at the immediate postoperative period and two year using EBRA-CUP software. We analyzed horizontal and vertical cup migration distance and the difference in cup anteversion and inclination angle at two years. Additionally, total head penetrarion and polyethylene liner volumetric wear rates were measured using a computer-assited method with PolyWear software. The larger head group revealed an average of 0.48mm of horizontal migration, 0.75mm of vertical migration, 0.19degree of inclination change, and 1.26 degrees of anteversion change. The control group showed an average of 0.63mm of horizontal migration, 0.36mm of vertical migration, 0.07 degree of inclination change, and 0.88 degree of anteversion change. Based on the EBRA-CUP measurements, there were no cases of significant early loosening which was indicated by more than 1mm of migration, more than 2.5 degree of inclination change, or more than 3.3 degree of anteversion change. The liner penetration rates were 0.388±0.192mm/yr in the large head group and 0.362±0.178mm/yr in the control group. The difference was not significant (p=0.64.) The volumetric wear rates were 42.8±27.9mm⁁3/yr in the large head group and 42.0±33.0mm⁁3/yr in the control group. Again, the difference was not significant (p=0.94). No significant early cup migration or increased wear rate were detected in THA with the sequentially cross-linked polyethylene liner and 36mm or large heads at two years.
Background. Migration analysis after total joint arthroplasty are performed using
Introduction. Acetabular component positioning, offset, combined anteversion, leg length, and soft tissue envelope around the hip plays an important role in hip function and durability. In this paper we will focus on acetabular positioning of the cup. Technique. The axis of the pelvis is identified intra-operatively as a line drawn from the highest point of the iliac crest to the middle of the greater trochanter. Prior to reaming the acetabulum, an undersized trial acetabular component is placed parallel and inside the transverse ligament, inside the anterior column and projecting posterior to the axis of the pelvis. This direction is marked and the subsequent reaming and final component placement is performed in the same direction. The lateral opening is judged based on the 45-degree angle from the tear drop to the lateral margin of the acetabulum on anteroposterior pelvic radiographs. The final anteversion of the cup is adjusted based on increased or decreased lumbar lordosis and combined anteversion. Methods. Anteroposterior pelvic radiographs of 100 consecutive patients undergoing posterior THR between September 2010 and March 2011 with this method were evaluated for cup inclination angle and anteversion using
Introduction: Acetabular component positioning, offset, combined anteversion, leg length, and soft tissue envelope around the hip plays an important role in hip function and durability. In this paper we will focus on acetabular positioning of the cup. Technique: The axis of the pelvis is identified intra-operatively as a line drawn from the highest point of the iliac crest to the middle of the greater trochanter. Prior to reaming the acetabulum, an undersized trial acetabular component is placed parallel and inside the transverse ligament, inside the anterior column and projecting posterior to the axis of the pelvis. This direction is marked and the subsequent reaming and final component placement is performed in the same direction. The lateral opening is judged based on 45-degree angle from the tear drop to the lateral margin of the acetabulum on anteroposterior pelvic radiographs. The final anteversion of the cup is adjusted based on increase or decrease of lumbar lordosis and combined anteversion. Methods: Anteroposterior pelvic radiographs of 100 consecutive patients undergoing posterior THR between September 2010 and March 2011 with this method were evaluated for cup inclination angle and anteversion using
Introduction. Cup positioning in total hip arthroplasty (THA) is an important variable for short and long term durability of any hip implant. This novel method utilises internal and external bony landmarks, and the transverse acetabular ligament for positioning the acetabular component. Methods. The cup is placed parallel and superior to the transverse ligament and inside the anterior wall notch of the true acetabulum, and then adjusted for femoral version and pelvic tilt, fixed obliquity, and transverse rotational deformity based on weight bearing pre-operative radiographs. Seventy consecutive THRs (68 patients) were performed using the above technique. The cup radiographic and functional anteversion and abduction angle were measured on post-operative weight bearing pelvic radiographs using
Introduction. Total hip arthroplasty (THR) with non-cemented or hybrid fixation remains one of the most successful procedures performed today. The aim of this study was to assess the safety and efficacy of a hydroxyapatite (HA) coated, hemispherical cup. Material and Methods. Between 2003 and 2007, 223 THAs (210 patients) with peripheral self-locking (PSL) cup and highly cross-linked polyethylene (Crossfire, Stryker, Mahwah, NJ) with minimum 5 years clinical and radiographic follow-up (5–9 years) were analyzed. The mean age was 62.5 years ± 10.8 (range, 32.7 – 86.3) at the time of surgery and the predominant preoperative diagnoses was osteoarthritis (97.8%). 72% were solid cups without screw augmentation and 28% were multi-hole with screw. Clinical analysis included Hospital for Special Surgery (HSS) hip scores at latest follow-up. Detail radiographic analysis was carried out on anteroposterior and false profile views for evidence of osseointegration in all Charnley's zones. Osseointegration was assessed based on presence of Stress Induced Reactive Cancellous Bone (SIRCaB) with trabecular bone hypertrophy 5–15mm extending from the cup, and absence of radiolucency or demarcation.
Introduction. All current methods of cup placement use anterior pelvic plane (APP) as the reference. However, the majority of studies investigating the measurement of anteversion (AV) and abduction angles (AA) are inaccurate since the effect of pelvic tilt and obliquity are not considered. The aim of this study was to describe a reproducible, novel technique for functional cup positioning using internal and external bony landmarks and the transverse acetabular ligament (TAL). Methods. The pelvic obliquity and tilt are measured on the pre-operative weight bearing AP and lateral pelvic radiographs. Intra-operatively, the highest point of the iliac crest is identified and a line is drawn to the middle of the greater trochanter with knee flexed to 90 degrees and leg thigh horizontal to the floor, parallel to the APP. The cup is placed parallel to the TAL and inside the anterior acetabular wall notch, and then is adjusted for the femoral anteversion, pelvic tilt and obliquity. The angle between the drawn line and the cup handle is the operative anteversion. 78 consecutive total hip replacements (76 patients) were performed using this technique. The functional cup orientation was measured on post-operative weight bearing pelvic radiographs using
Background. Reasons for revision of metal-on-metal hip resurfacing arthroplasty (MoMHRA) have evolved with improving surgical experience and techniques. Early revisions were often due to fracture of the femoral neck while later revisions are associated with loosening and/or adverse local tissue reactions (ALTR) to wear debris. In some studies, revisions of MoMHRA with ALTR have been complicated by an increased risk of rerevision and poor outcome. The purpose of this study was to investigate the causes of failure and to identify factors that improve outcome following revision of a failed HRA. Methods. From 2001 to May 2015, 180 consecutive HRA revisions were performed in 172 patients. Ninety-nine primary surgeries were done at a HRA specialist centre (99/4211, revision rate: 2.4%), 81 elsewhere. Eight different HRA designs were revised mainly in females (60%). Components’ orientation was measured from radiographs using
Introduction. The purpose of this study was to evaluate the in vivo migration patterns of a polished femoral component cemented line-to-line using
Introduction. Squeaking is a potential problem of all hard on hard bearings yet it has been less frequently reported in metal-on-metal hips. We compared a cohort of 11 squeaking metal-on-metal hip resurfacings to individually matched controls, assessing cup inclination and anteversion between the groups to look for any differences. Methods. We retrospectively reviewed the patient records of 332 patients (387 hip resurfacings) who underwent hip resurfacing between December 1999 and Dec 2012. 11 hips in 11 patients were reported to squeak postoperatively. Each of these patients, except one, were matched by age, sex, BMI and implant to 3 controls. The final patient only had one control due to his high BMI. The latest post-operative radiographs of the squeaking group and controls were analysed using
Introduction. Total hip arthroplasty (THR) is one of the most successful procedures performed today. Uncemented acetabular components have by and large replaced cemented cups. As such, optimal fixation, bony ingrowth with longevity, and safety is highly demanded. In this study, we look at the safety and efficacy of the Stryker® Trident PSL™ acetabular component based on radiographic and clinical analysis. Materials and Methods. We looked at 860 consecutive patients between 2003 and 2007. Of these, 231 consecutive patients had a minimum 5 year follow up. All cases were for degenerative joint disease (DJD), except 2 for dysplasia, 1 for avascular necrosis (AVN), 1 femoral neck nonunion. Average Hospital for Special Surgery (HSS) hip scores at final follow up were recorded. Radiographic analysis included classification based on Delee and Charnley's zones 1–3. Osseointegration was assessed based on presence of SIRCAB (stress induced reactive cortical hypertrophy of bone), demarcation around the implant, stress shielding, presence of radial trabeculae, absence of radiolucency, type of bearing, presence of preoperative protrusion, violation of Kohler's line.
Introduction. Total hip prostheses which use a ceramic head within a metal liner are a relatively recent innovation. As such, survivorship rates from independent centres alongside explant analysis are rare. The early clinical experience with this novel ceramic-on-metal (CoM) bearing couple is reported alongside explant analysis of failed devices. Methods and materials. All CoM hips implanted between 2008 and 2009 at a single hospital by a single surgeon were reviewed. Radiographs were analysed using
Introduction. Acetabular fixation is one of the major factors affecting long-term longevity and durability of total hip arthroplasty (THA). Limited data exist regarding mid-term performance of modern non-cemented rim-fit cups with HA coating. The aim of this study was to assess the minimum 5 year clinical and radiographic performance of PSL cups. Therefore we retrospectively analyzed results of this component in patients that had adequate followup from a prospective institutional database. Materials and Methods. A retrospective analysis of a prospective database was performed to identify patients that underwent non-cemented THA between 2003 and 2007. 223 primary THA (210 patients) were performed by single surgeon via posterolaeral approach using a grit-blasted, HA coated rim-fit design and highly cross-linked polyethylene and were followed with minimum 5 years. The mean age was 62.5 years ± 10.8. The majority of the stems were non-cemented (87%) and the majority of the femoral heads were metal (75%), 22- or 28-mm diameter. 72% of the cups were solid and 28% were multi-hole. Clinical assessment included the Hospital for Special Surgery (HSS) hip score [18] at final follow-up, and Kaplan-Meier survivorship. All patients received pre- and post-operative anteroposterior (AP) weight bearing pelvis radiograph as well as a false profile view of the hip. Cup positioning was analyzed using the
Background:. Numerous studies have reported the importance of acetabular component positioning in decreasing dislocation rates, the risk of liner fractures, and bearing surface wear in total hip arthroplasty (THA). The goal of improving acetabular component positioning has led to the development of computer-assisted surgical (CAS) techniques, and several studies have demonstrated improved results when compared to conventional, freehand methods. Recently, a computed tomography (CT)-based robotic surgery system has been developed (MAKO™ Robotic Arm Interactive Orthopaedic System, MAKO Surgical Corp., Fort Lauderdale, FLA, USA), with promising improvements in component alignment and surgical precision. The purpose of this study was to compare the accuracy in predicting the postoperative acetabular component position between the MAKO™ robotic navigation system and an imageless, CAS system (AchieveCAS, Smith and Nephew Inc., Memphis, TN, USA). Materials and Methods:. 30 THAs performed using the robotic navigation system (robotic cohort) were available for review, and compared to the most recent 30 THAs performed using the imageless, CAS system (CAS cohort). The final, intraoperative reading for acetabular abduction and anteversion provided by each navigation system was recorded following each THA. Einsel-Bild-Roentgen analysis was used to measure the acetabular component abduction and anteversion based on anteroposterior pelvis radiographs obtained at each patient's first, postoperative visit (Figure 1). Two observers, blinded to the treatment arms, independently measured all the acetabular components, and the results were assessed for inter-observer reliability. Comparing the difference between the final, intraoperative reading for both acetabular abduction and anteversion, and the radiographic alignment calculated using
It has been suggested that metal ion levels are indicative of in vivo bearing performance of metal-on-metal hip replacements. A cobalt or Chromium level of 7μg/L or higher is proposed to be indicative of a bearing malfunction and the need for clinical intervention. Component design, size, acetabular orientation, patient gender and activity level have been suggested as factors leading to accelerated wear and elevated metal ions. The contact patch to rim (CPR) distance is a calculation that describes the distance from the point where a theoretical joint reaction force intersects the cup to the acetabular rim for a patient in standing position, dependent on the coverage, size, and orientation of the acetabular component. It has been suggested that CPR distance determines the hip joint susceptibility to edge loading, and the risk for increased wear and high ion levels (Langton et al JBJS Br 91: 2009). This study examined the effects of patient activity, gender, and CPR distance on serum metal ion concentrations in a series of patients treated with one type of metal on metal hip resurfacing arthroplasty (MMHRA) performed by one surgeon. 182 patients (73 females and 109 males)with a unilateral Conserve Plus (WMT, TN USA) MMHRA and had who had provided blood for metal ion analysis data from December 2000 to June 2011 were retrospectively studied. Only measurements made more than 12 months after surgery were included in order to exclude hips that had yet to reach steady-state wear. For patients with multiple draws, the most recent qualifying draw was used. Activity level was assessed by the UCLA activity score. The mean age was 51.5 years (20.0 to 77.5 years). The mean follow-up time for the last blood draw was 70 months (range, 12 to 165). Serum cobalt (CoS) and chromium (CrS) levels were analyzed using inductively coupled plasma mass spectrometry in a specialized trace element lab. Using acetabular abduction and anteversion measured by
Introduction. Tribological studies have described a characteristic wear pattern of metal-on-metal hip resurfacings (MoMHRAs) with a run-in period followed by a ‘bedding-in’ phase minimising wear or by an increasing wear patch with edge loading. The use of metal ions as surrogate markers of in-vivo wear is now recommended as a screening tool for the performance of MoMHRAs. The aims of this retrospective, single-surgeon study were to measure ion levels in unilateral MoMHRAs at different stages during the steady-state in order to study the evolution of wear and factors affecting it. Methods. 218 consecutive patients with minimum two serum ion measurements were included. The mean age at surgery was 52.3 years, the first assessment was made at a mean of 2.5 years (11 months–8 years) and the last assessment at a mean of 4.6 years post resurfacing (2– 12 years). Ion level change was defined as Ion level at last assessment minus Ion level at first assessment. Ten different resurfacing designs were implanted, the majority being BHR (n=104), Conserve plus(n=55) and ASR (n=25). The median femoral component size was 50 mm (38–59mm). Radiological assessment of acetabular component orientation was made with
INTRODUCTION. Metal-on-metal hip resurfacing arthroplasty (MoMHRA) is a surgical option in the treatment of end-stage hip disease. The measurement of systemic levels of metal ions gives an insight into the wear occurring and is advocated by regulatory bodies as routine practice in the assessment of resurfaced hips. However, the acceptable upper levels of Chromium (Cr) and Cobalt (Co) ions concentration with clinical significance still have to be established. The aim of this study is to address this issue in unilateral and bilateral resurfaced hips. METHODS. 453 patients with unilateral MoMHRA and 139 patients with bilateral MoMHRA at >12 months postoperative were retrospectively identified from an independent hip specialist's database. Routine metal ion levels were measured at last follow-up (ICPMS protocol). Radiological assessment included measurement of acetabular component orientation using