First-time revision acetabular components have a 36% re-revision rate at 10 years in Australia, with subsequent revisions known to have even worse results. Acetabular component migration >1mm at two years following revision THA is a surrogate for long term loosening. This study aimed to measure the migration of porous tantalum components used at revision surgery and investigate the effect of achieving press-fit and/or three-point fixation within acetabular bone. Between May 2011 and March 2018, 55 patients (56 hips; 30 female, 25 male) underwent acetabular revision THR with a porous tantalum component, with a post-operative CT scan to assess implant to host bone contact achieved and Radiostereometric Analysis (RSA) examinations on day 2, 3 months, 1 and 2 years. A porous tantalum component was used because the defects treated (Paprosky IIa:IIb:IIc:IIIa:IIIb; 2:6:8:22:18; 13 with pelvic discontinuity) were either deemed too large or in a position preventing screw fixation of an implant with low coefficient of friction. Press-fit and three-point fixation of the implant was assessed intra-operatively and on postoperative imaging. Three-point acetabular fixation was achieved in 51 hips (92%), 34 (62%) of which were press-fit. The mean implant to host bone contact achieved was 36% (range 9-71%). The majority (52/56, 93%) of components demonstrated acceptable early stability. Four components migrated >1mm proximally at two years (1.1, 3.2, 3.6 and 16.4mm). Three of these were in hips with Paprosky IIIB defects, including 2 with pelvic discontinuity. Neither press-fit nor three-point fixation was achieved for these three components and the cup to host bone contact achieved was low (30, 32 and 59%). The majority of porous tantalum components had acceptable stability at two years following revision surgery despite treating large acetabular defects and poor bone quality. Components without press-fit or three-point fixation were associated with unacceptable amounts of early migration.
First-time revision acetabular components have a 36% re-revision rate at 10 years in Australia, with subsequent revisions known to have even worse results. Acetabular component migration >1mm at two years following revision THA is a surrogate for long term loosening. This study aimed to measure the migration of porous tantalum components used at revision surgery and investigate the effect of achieving press-fit and/or three-point fixation within acetabular bone. Between May 2011 and March 2018, 55 patients (56 hips; 30 female, 25 male) underwent acetabular revision THR with a porous tantalum component, with a post-operative CT scan to assess implant to host bone contact achieved and Radiostereometric Analysis (RSA) examinations on day 2, 3 months, 1 and 2 years. A porous tantalum component was used because the defects treated (Paprosky IIa:IIb:IIc:IIIa:IIIb; 2:6:8:22:18; 13 with pelvic discontinuity) were either deemed too large or in a position preventing screw fixation of an implant with low coefficient of friction. Press-fit and three-point fixation of the implant was assessed intra-operatively and on postoperative imaging. Three-point acetabular fixation was achieved in 51 hips (92%), 34 (62%) of which were press-fit. The mean implant to host bone contact achieved was 36% (range 9–71%). The majority (52/56, 93%) of components demonstrated acceptable early stability. Four components migrated >1mm proximally at two years (1.1, 3.2, 3.6 and 16.4mm). Three of these were in hips with Paprosky IIIB defects, including 2 with pelvic discontinuity. Neither press-fit nor three-point fixation was achieved for these three components and the cup to host bone contact achieved was low (30, 32 and 59%). The majority of porous tantalum components had acceptable stability at two years following revision surgery despite treating large acetabular defects and poor bone quality. Components without press-fit or three-point fixation were associated with unacceptable amounts of early migration.
Subjective outcomes used in THA show outstanding improvements in patient-reported outcomes. However, recent evidence suggests that there may be a disconnect between patient-reported and objectively measured function. The aim of this study was to investigate if physical activity and sleep patterns change from pre- to six months post primary THA. 54 patients scheduled for THA were recruited. Patients were given a wrist-worn accelerometer (GeneActiv, UK) to wear continuously for one week pre-operatively and six weeks, three months and six months post-operatively. The device was also fitted to the patient immediately following surgery to capture data for the first two post-operative weeks. The following parameters were calculated: (1) sleep efficiency; (2) the amount of time (and length of each bout and fragmentation of the activity) spent in sedentary activity; and (3) time spent in light, moderate and vigorous physical activity. Sedentary activities showed no change in the number, duration or fragmentation (p= 0.382, 0.288, 0.382, respectively). Patients were sedentary for 5–6 bouts/day with each bout lasting 50–76 minutes/day. A significant main effect was identified for time spent in light intensity activities (p=0.049). Prior to surgery, patients spent 201 minutes/day in light intensity activity. This decreased significantly to 133 minutes/day (p=0.025) in the first two postoperative weeks before returning close to pre-operative levels (192 minutes/day) at six weeks (p=0.025). No further changes were observed in light intensity activities. A significant main effect was identified for time spent in moderate intensity activities (p=0.003). Prior to surgery, patients spent 45 minutes/day in moderate intensity activities. This dropped to 18 minutes/day in the first two postoperative weeks (p=0.190). By three months this had increased to 66 minutes/day (p=0.049). No further changes were seen. There were no significant differences in time spent in vigorous intensity activities (p=0.244). Patients spent <1minute/day in vigorous intensity activities. Sleep efficiency did not change significantly from pre- (82%) to six months post-operative (75%) (p=0.067) − 85% is typically considered good sleep efficiency. Patients discharged to a regional hospital had significantly poorer sleep efficiency than those discharged home (mean difference=14%, p=<0.001) or to a rehabilitation centre (mean difference=15%, p=0.001). This patient cohort didn't demonstrate an overall improvement in objectively measured physical activity patterns from pre- to six months post-operative. Sleep efficiency, did not improve and remained sub-optimal.
Severely comminuted, displaced acetabular fractures with articular impaction in the elderly population present significant treatment challenges. To allow early post-operative rehabilitation and limit the sequelae of immobility, treatment with acute total hip replacement (THA) has been advocated in selected patients. Achieving primary stability of the acetabular cup without early migration is challenging and there is no current consensus on the optimum method of acetabular reconstruction. We present clinical results and radiostereometric analysis of trabecular metal (TM) cup cage construct reconstruction in immediate THA without acetabular fracture fixation. Between 2011 and 2016, twenty-one acetabular fractures underwent acute THA with a TM cup cage construct. Patient, fracture and surgical demographics were collected. They were followed up for a mean of 24months (range 12–42months). Clinical and patient reported outcome measures were collected at regular post-operative intervals. Radiosterometric analysis (RSA) was used to measure superior migration and sagittal rotation of the acetabular component.Introduction
Methods
Acetabular components used to treat large defects are at greater risk of loosening. Porous tantalum acetabular components have reported the most promising early to midterm revision rates. Early stability of acetabular components used at revision THR was shown to be a good predictor of later loosening. The primary aim was to assess the migration of porous acetabular component used to reconstruct severe acetabular defects. Secondarily, we investigated the effect of acetabular defect severity and type of component fixation on migration. Radiosterometric analysis was used to measure migration at a mean follow-up of four years, (range 2–10) in 59 reconstructions of severe acetabular defects with porous tantalum components. Acetabular component fixation was classified as superior if augmented with screws through cup, augments or cage in the ilium only. Fixation was classified as combined, superior and inferior, if flanges and/or screws were also placed in the ischium and or pubis. Acceptable limits of proximal migration were defined as ≤1mm within 2 years and ≤2.5mm at any time point. Eight hips had reconstruction of Paprosky II defects with superior fixation only. The mean proximal migration of the eight acetabular components was 0.25mm (0.08–0.40) at 2 years and 0.29mm (0.10–0.81) at last follow-up. Fifty-one hips had reconstruction of Paprosky III defects. Seven of these reconstructions exceeded the migration thresholds. Five reconstructions (four with superior fixation and one cup cage construct with no inferior screw fixation) of hips with pelvic discontinuity developed pain and were re-revised for loosening. Two reconstructions are asymptomatic and migrated 2.68mm (cup-cage construct with superior screws) and 2.86mm (no pelvic discontinuity, superior fixation) at final follow-up. The mean proximal migration of the 51 Paprosky III reconstructions was 0.99mm (0.03 to 16.4) at 2 years and 1.92mm (0.01 to 29.4) at last follow-up. The mean proximal translation at 2 years of the 11 reconstructions with inferior screw fixation was 0.2mm (−0.6 to 0.7mm), compared with 0.9mm (−0.6 to 16.4mm) for the reconstructions without inferior screw fixation. In conclusion, when used to reconstruct Paprosky II defects, porous tantalum acetabular components provide component stability similar to a good performing primary THR. These implants achieve adequate stability when used to treat Paprosky III defects, including those with pelvic discontinuity. For the most severe defects, combined fixation with inferior screws is recommended, particularly when reconstructing hips with pelvic discontinuity.
The primary aim of this study was to determine dislocation and revision total hip replacement (THR) up to ten years following primary THR, as well as rates of polyethylene wear, in patients previously enrolled in a randomised controlled trial (RCT) which compared 28 mm and 36 mm metal on highly cross-linked polyethylene (XLPE) articulations. 328 primary THR patients were enrolled in the RCT in Australia. Dislocation was identified from hip instability and hospital visit questionnaires completed by patients or, if they were unable to do so, by their next of kin or primary carer, or General Practitioner. All reported dislocations were confirmed radiographically. Patients' names were cross-matched with the Australian National Joint Replacement Registry to determine whether the index hip had undergone revision THR. Linear wear was measured on plain radiographs using PolyWare (Rev 5, Draftware Developers, Vevay IN, USA). A separate RCT examined the mean proximal wear rate of 28 and 36 mm articulations using radiostereometric analysis (RSA). At 10 years, 110 patients were deceased and 3 patients were lost to follow-up. Overall, dislocation was identified in 8 of 167 (5%) patients with a 28 mm articulation and 2 of 158 (1%) patients with a 36 mm articulation. Three patients experienced recurrent dislocation; all had a 28 mm articulation. 320 (163 28 mm; 157 36 mm) patients were successfully cross-matched with Registry data to identify revision THR. Three patients, all with a 28 mm articulation, underwent revision because of dislocation. Other reasons for revision were infection (1:2), periprosthetic fracture (0:3), loosening/lysis (1:2) and liner fracture (0:1). Adequate radiographs were available to measure wear in 122 hips (67:55) using PolyWare. Excluding bedding in, the mean annual linear wear rate from 1–10 years was 0.04 mm/yr for both 28 and 36 mm articulations (p=0.48). The more sensitive RSA data indicated that at 7 years following primary THR, the mean annual wear rate did not exceed 0.02 mm/yr with either articulation. Up to 10 years following primary THR, 36 mmm articulations were associated with fewer dislocations and revisions for dislocation and did not increase the mean annual linear wear rate.
There has not been any published work quantifying the volume cement used/needed for knee arthroplasty. The number of mixes of cement used is at the discretion of the surgeon, based on their own experience/training. The objective of this study was to quantify the volume of cement used for knee arthroplasty in our institution, and to observe variations between surgeons and implant size. The study then aimed to calculate the theoretical volumes required and observe the volume of cement actually implanted before commenting on cost implications of cement usage. Prospective data for 85 consecutive knee arthroplasties performed by 9 consultants was examined. A single mix in this institution refers to 40g of Palacos R+G. Significant variation between surgeons was seen, with a range of one to three mixes being used. Several surgeons used one mix exclusively, independent of implant size, whilst others exclusively used two mixes. The departmental average was 1.4 mixes per knee. The total surface area of our largest implants (Size 8 Triathlon Femoral and Tibial components) was measured-108cm2 and compared to the volume of a single mix of cement −49 cm3. Even using the largest component size, a single mix will provide 4.5mm of uniform cement coverage. The volume of cement actually implanted during 10 knee arthroplasties was examined by weighing the residual cement. The average volume of cement implanted was 18cm3 per knee. In 2009 1085 knee replacements were performed in this institution. If all surgeons in the department used a single mix of cement this could potentially save £16,357.46 per year. (Presuming average usage was 1.4 mixes per knee, 434 ‘extra’ mixes were used, costing £37.69 each) We conclude that a single mix of cement will cover the area required for all Triathlon implants and that less than half a mix (on average) is actually implanted.
To evaluate the clinical success and hip pain and function of patients with infected hip replacement treated by two-stage exchange using a temporary implant with high dose vancomycin added to the antibiotic cement at the first stage revision. Thirty-three hips in 32 patients (median 67 yrs) underwent first stage revision using the PROSTALAC™ system (n=27) or a self-made system using an Elite long stem (n=6). Infection was diagnosed after 19 primary, 11 revision and 3 hemiarthroplasty hip replacements. Patients were reviewed regularly clinically and by questionnaire. The median follow-up was 3 years.Introduction
Method
There has been almost universal adoption of highly cross-linked polyethylene as the polyethylene of choice in metal-on-polyethylene articulations in total hip replacement (THR). Although wear of conventional polyethylene has been shown to be related to periprosthetic osteolysis, the relationship between wear of highly cross-linked polyethylene and osteolysis remains uncertain. Our aim was to determine the incidence and volume of periacetabular osteolysis at a minimum of seven years following primary THR with metal on highly cross-linked polyethylene articulations. 644 patients were enrolled into a randomised controlled trial which examined the effect of articulation size (28 vs 36 mm) on the incidence of dislocation one year following THR. To date, 62 patients (34 patients – 28 mm articulation; 28 patients – 36 mm articulation) have undergone a quantitative computed tomography (CT) scan, with metal artefact reduction protocol, to detect and measure osteolysis at a minimum of seven years following THR. Osteolysis was defined as a localised area of bone loss of at least 1 cm3 that is expansile, with a well-defined sclerotic border, a clear communication between the defect and the joint space and the absence of acetabular cysts. Pre-operative and post-operative plain radiographs were examined to identify the existence of acetabular cysts. Polyethylene wear from one to seven years following THR was also measured, using a computerised edge detection technique (PolyWare Rev 5, Draftware) of analysing standard radiographs.Introduction
Methods
Component malalignment has long been implicated in poor implant survival in Total Knee Arthroplasty (TKA). Malalignment can occur in orientation of bony cuts, and in component cementation/implantation. Several systems exist to aid bony cut alignment (navigation, shape matching), but final implantation technique is common to all TKA. Correction of errors in bony cut alignment at cementation/implantation by surgeons has been described. Changes in alignment at this stage are likely to result in asymmetrical cement penetration, which is implicated in early failure. This study reviewed a consecutive series of 150 primary cemented TKAs using an imageless navigation system (aiming for neutral overall limb alignment). Deviation at implantation was calculated by comparing limb alignment recorded using the trial components with limb alignment recorded with the final implanted components, prior to closure. 136 patients (91%) had a final overall limb alignment within 2° of neutral. Three patients (2%) had a final overall limb alignment greater than 3° from neutral. Deviation occurring at implantation is shown in Figure 1 with deviations distributed around zero (mode 0, median 0.3, range −2 to +4,)
The aim of this study was to examine the progression of osteolytic lesions following liner exchange surgery and relate this to the size of the lesion prior to surgery, and whether the defect underwent curettage and bone grafting during surgery. Six patients with well-fixed Harris-Galante-1 acetabular components underwent liner exchange surgery for excessive polyethylene wear and osteolysis. The mean interval from primary arthroplasty to revision was 14 years (range 11–17 years). All patients underwent a CT scan pre-operatively to identify the location and size of the osteolytic lesions and during surgery, accessible lesions were curetted and bone grafted. One patient had recurrent dislocations and the acetabular component was revised one year following liner exchange surgery. The remaining five patients had CT scans taken at a mean of five months (range 3–5 months) and 5 years (range 3.4–8.2 years) following surgery. Osteolytic lesion volume with or without bone grafting was measured. Of the 19 osteolytic lesions detected pre-operatively, the first post-operative CT scan showed that four lesions were fully bone-grafted, ten lesions were partially bone-grafted and five lesions had no bone grafting during surgery. At a minimum of three years following surgery, all fully bone-grafted lesions remained full of bone- graft. Of the ten partially bone-grafted lesions, the osteolytic non-grafted zone decreased in volume in five lesions and five lesions remained unchanged. Of the five osteolytic lesions with no bone grafting, one lesion increased in volume, one lesion decreased in volume and three lesions remained unchanged. No new lesions were detected in any of the hips. These preliminary results suggest that liner exchange surgery is effective in treating periacetabular osteolysis. Although bone grafting appears to aid in restoring bone stock, it is not essential in halting the progression of osteolysis, which likely results from the ongoing production of polyethylene particles in the joint.
Sensitive and accurate measures of osteolysis around TKR are needed to enhance clinical management and assist in planning revision surgery. Therefore, our aim was to examine, in a cadaver model of osteolysis around TKR, the sensitivity of detection and the accuracy of measuring osteolysis using Xray, CT and MRI. Fifty-four simulated osteolytic lesions were created around six cadaver knees implanted with either a cemented or cementless TKR. Twenty-four lesions were created in the femur and thirty in the tibia ranging in size from 0.7 cm3 to 14 cm3. Standard anteroposterior and lateral fluoroscopically guided radiographs, CT and MRI scans with metal reduction protocols were taken of the knees prior to the creation of lesions and at every stage as the lesion sizes were enlarged. The location, number and size of the lesions from images obtained by each method were recorded. The sensitivity of osteolytic lesion detection was 44% for plain radiographs, 92% for CT and 94% for MRI. On plain radiographs, 54% of lesions in the femur and 37% of lesions in the tibia were detected. None of the six posterior lesions created in the tibia were detected on the AP radiographs; however, three of these six lesions were detected on the lateral radiographs. CT was able to detect lesions of all sizes, except for four lesions in the posterior tibia (mean volume of 1.2 cm3, range 1.06–1.47 cm3). Likewise, MRI was very sensitive in detecting lesions of all sizes, with the exception of three lesions, two of which were in the femur and one was in the medial condyle of the tibia (mean volume of 1.9 cm3, range 1.09–3.14 cm3). Notably, all six posterior tibial lesions, which could not be detected using AP radiographs, were detected by MRI. This study demonstrates the high sensitivity of both CT and MRI (which uses no ionising radiation) to detect simulated knee osteolysis and can therefore be used to detect and monitor progression of osteolysis around TKR. The study also shows the limitations of plain radiographs to assess osteolysis.
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, EBRA and RSA, were used to measure stem subsidence. Major stem re-revision was required in five hips in series one, one hip in series two and no hips in series three. Two periprosthetic fractures occurred in series one. There was a statistically significant reduction in stem subsidence at the cement-bone interface at 12 months between series one and series two and three (p<0.05). In series three there was negligible stem subsidence at the cement-bone interface. Technique developments in femoral impaction grafting, including the use of modular tamps designed to simply the procedure, yields excellent early clinical and radiographic results. Using RSA, we have shown that the fixation of the stems in bone is comparable to that achieved in primary hip replacement.
Large articulations are increasingly being used to reduce dislocation, the most common early complication following THR. However, potential benefits of large articulations in reducing dislocation have not been proven in a well-controlled clinical trial. The aim of our randomised controlled trial was to compare the one-year incidence of dislocation between 36 and 28 mm metal on highly cross-linked polyethylene articulations. Patients were excluded if they had a high risk of dislocation due to, for example, abnormal anatomy, neuromuscular disease, previous infection or dislocation. Eligible patients were stratified according to a number of other factors which may influence dislocation risk, including primary or revision THR and, if primary THR, by surgeon, age, diagnosis, sex and Charnley grade. Patients were randomised intra- operatively to either a 28 or 36 mm articulation. Dislocation incidence was determined using a hip instability questionnaire and a hospital visit questionnaire. A dislocation was diagnosed if there was radiological evidence and reduction by a doctor was required. Six-hundred-and-forty-four patients undergoing primary or revision THR were entered into the study. Overall, the incidence of dislocation at one year following THR was 5.4% with a 28 mm articulation and 1.3% with a 36 mm articulation (p=.004). Incidence in primary THR patients was 4.4% with a 28 mm articulation, compared to 0.8% with a 36 mm articulation (p=.007). Incidence in revision THR patients was 12.2% and 4.9% with 28 and 36 mm articulations, respectively. For both primary and revision THR patients, sex distribution, age and BMI of patients who dislocated were similar to those of the total samples of primary or revision patients. This large randomised study unequivocally shows for the first time that, compared to a 28 mm articulation, a 36 mm articulation in THR is efficacious in reducing the incidence of dislocation in the first year following THR.
The purpose of this paper is to review the early results of Prostalac system under licence from Therapeutic Goods Administration for Professor Howie in the management of two stage exchange hip arthroplasty for infection (restricted to Royal Adelaide Hospital) and the addition of vancomycin and teicoplanin powder to tobramycin cement without additional tobramycin. Thirteen patients were treated for an infected THR with the Prostalac system. Preoperative and intra-operative cultures were taken to identify the infective organisms. Vancomycin 3 gm was added to the Prostalac cement mantle per 40 gm packet of antibiotic bone cement containing tobramycin 1 gm. Teicoplanin 2.4 gm was used in one case where the patient had a known vancomycin allergy. Postoperatively patients underwent six weeks of IV antibiotics followed by four to six weeks of oral. A short term successful clinical outcome was determined by implantation of a total hip prosthesis at the time of second stage operation and no reoperations resulting from recurrent infection and off antibiotics for â□¥ 6 months with normal clinical and CRP lab values. Thirteen patients received the Prostalac system. No patient was lost to follow-up. Nine have progressed to second stage revision, eight of which had femoral impaction grafting. Two deaths occurred not attributed to the Prostalac system. Three superficial wound infections and two required washout and debridement. One Prostalac stem subsidence. There has been no recurrence of deep joint infection. Retention of the second stage prosthesis has been 100% at 17 months. The PROSTALAC system with the addition of vancomycin or teicoplanin to the tobramycin antibiotic cement has encouraging short-term results for treatment of deep joint infection. Complication rate has been well within the range reported in literature. Successful early outcomes are encouraging with all patients in the Prostalac study having retained their permanent hip prosthesis following second stage surgery.
This large randomized study unequivocally shows for the first time that, compared to a 28 mm articulation, a 36 mm articulation in THR is efficacious in reducing the incidence of dislocation in the first year following THR.
Early revision is an important risk factor for repeated revision and poor results after primary total hip replacement and instability is a major cause of early revision. Larger articulations with cross-linked polyethylene are proposed as a solution, but these are not without risk, including fracture of the thin polyethylene rim of the liner. The aim of our study was to examine implant-related revisions among primary total hip replacement patients with up to six year follow-up in a randomized controlled trial which compared 28 mm and 36 mm metal on highly cross-linked polyethylene articulations in total hip replacement. 557 patients undergoing primary total hip replacement were included in this study. Risk factors for dislocation and wear were controlled by stratification and patients were then randomized intra-operatively to either a 28 or 36 mm articulation. To date, 10 hips have been revised for implant-related problems following primary total hip replacement. Seven hips with a 28 mm articulation were revised to a larger articulation because of instability. Four of these were for recurrent dislocation, one for an irreduceable first dislocation and two for subluxation. In contrast, only one patient who had undergone total hip replacement with a 36 mm articulation was revised for recurrent dislocation. One hip with a 36 mm articulation in a well-positioned cup was revised to a 32 mm articulation because of elevated lip liner fracture. Another 36 mm articulation hip was revised for acetabular component loosening. This study shows that a 36 mm metal on highly cross-linked polyethylene articulation reduces the need for early revision for instability after primary total hip replacement. However, these benefits need to be weighed against the potential risks associated with these articulations, including rare fracture of the relatively thin poly-ethylene liner.
Large articulations using cross-linked polyethylene and other alternate bearings are increasingly being used to reduce the incidence of dislocation, the most common early complication following total hip replacement. While indirect evidence has suggested the potential benefits of a large articulation in reducing dislocation risk, this has not been proven in a well-controlled clinical trial. The primary objective of our multi-centre international randomized controlled trial was to compare the one-year incidence of dislocation between a 36 mm and 28 mm metal on highly cross-linked polyethylene articulation in primary and revision total hip replacement. 644 patients were entered into the study. Patients were stratified according to a number of factors which may influence dislocation risk, including primary or revision total hip replacement, age, sex, Charnley grade, diagnosis and stem type. Patients were randomized intra-operatively to either a 28 or 36 mm articulation. The 12-month incidence of dislocation was statistically significantly lower in patients undergoing total hip replacement with a 36 mm articulation than in those with a 28 mm articulation (1.3% vs 5.2%, p<
.05). A total of 6 dislocations occurred in the 4 patients who dislocated with a 36 mm articulation, compared to a total of 36 dislocations in the 17 patients who dislocated with a 28 mm articulation. When primary and revision THR were examined separately, the 12-month incidence of dislocation was statistically significantly lower in patients undergoing primary total hip replacement with a 36 mm articulation than in those with a 28 mm articulation (0.7% vs 4.2%, p<
.05). A total of 4 dislocations occurred in two patients with a 36 mm articulation, compared to a total of 19 dislocations in 12 patients with a 28 mm articulation. The incidence of dislocation after revision total hip replacement with a 36 mm articulation was 4.8%, compared to 11.1% with a 28 mm articulation. This large randomized study unequivocally shows for the first time that, compared to a 28 mm articulation, a 36 mm articulation in total hip replacement is efficacious in reducing the incidence of dislocation in the first year following hip replacement.
RSA: Longitudinal Results: In all patients, the osteo-chondral fragment continued to migrate up to six months, with one exception that stabilised at three months. At six months, the osteochondral fragment translated between 0.02 and 4.15 mm and rotated between 0.2 and 7.2° (>
0.5mm and/or >
1.5° in five cases). DLRSA: Flexion Results: During 60° of flexion, translations exceeding 0.5mm were recorded in only one patient (0.7 mm at 2 weeks). Rotations exceeding 1.5° were recorded in three patients (1.6°, 2° and 2.1° all at six months). DLRSA: Weightbearing Results: Translations exceeding 0.5mm were recorded in four patients whilst full weightbearing (0.7mm in two patients at three months, and 0.6mm and 0.8 mm at 18 weeks). Rotations exceeding 1.5° were recorded in two patients. One patient recorded 2.3° under full weightbearing at three months. Another recorded 2.3° under 20kg of weight at two weeks and 1.8° under full weightbearing at 18 weeks. Patient reported outcomes improved progressively. At six months, five patients reported excellent results, two good and two fair. The two patients reporting fair results recorded low interfragmentary displacements.
While computed tomography (CT) provides an accurate measure of osteolysis volume, it would be advantageous in general clinical practice if plain radiographs could be used to monitor osteolysis. This study determined the ability of plain radiographs to detect the presence of and determine the progression in size of osteolytic lesions around cementless acetabular components. Nineteen acetabular components were diagnosed with osteolysis using a high-resolution multi-slice CT scanner with metal artefact suppression. Mean duration since arthroplasty was 14 years (range 10–15 years) at initial CT. Repeat CT scans were undertaken over a five year period to determine osteolysis progression. On anteroposterior pelvis (AP) radiographs and oblique radiographs of the acetabulum seen on the rolled lateral hip view, which were taken at the same time as the CT scans, area of osteolysis was measured manually correcting for magnification. Osteolysis was detected on the AP radiographs in 8 of 19 hips (42%), on the oblique radiographs in 6 of 19 hips (32%) and on the combined AP and oblique radiographs in 8 of 19 hips (42%). Throughout the study period, osteolysis was detected on 31 of 76 AP radiographs (41%) and 22 of 75 oblique radiographs (29%). Osteolysis was more likely to be detected on plain radiographs if the lesion volume was greater than 10cm3 in size (p=0.005). On CT, osteolysis progressed by more than 1cm3/yr in 10 of 19 hips (55%). In these ten hips, osteolysis progression was detected on AP radiographs in six hips and on oblique radiographs in three hips. No correlation was found between osteolysis progression measured by CT and that measured on AP (r2=0.16, p=0.37) or oblique (r2=0.37, p=0.15) or AP and oblique radiographs (r2=0.34, p=0.17). Plain radiographs are poor in monitoring progression in size of periacetabular osteolytic lesions. Plain radiographs may detect lesions more than 10cm3 in size, but are unreliable.
Computed tomography (CT) provides a sensitive and accurate measure of periacetabular osteolytic lesion volume, however, there may remain a role for plain radiographs in monitoring osteolysis. This study aimed to compare CT and plain radiographs for determining the progression in size of osteolytic lesions around cementless acetabular components. A high-resolution multi-slice CT scanner with metal artefact suppression was used to determine the volume and progression of osteolysis around 19 cementless Harris Galante-1 and PCA acetabular components. The mean duration since arthroplasty was 14 years (range 10–15 years) at initial CT. Repeat scans of the hip were undertaken over a five year period to determine the progression in size of osteolytic lesions over time. A second blinded observer manually measured the area of osteolytic lesions off anteroposterior pelvis radiographs and oblique radiographs of the acetabulum that were taken at the same time as the CT scan. All 19 hips had CT detected osteolysis. Osteolysis was detected on one or both of the anteroposterior pelvis or oblique radiographs from at least one time point in eight of 19 hips (42%). Osteolysis was detected on 31 of 76 anteroposterior pelvis radiographs (41%) and on 22 of 75 oblique radiographs (29%) (p=0.140). Osteolysis was more likely to be detected on plain radiographs if the lesion volume was greater than 10cm3 in size compared to those 5–10cm3 and less than 5cm3 in size (p=0.009). In 10 of 19 hips (55%), CT determined that osteolytic lesions progressed in size by more than 1cm3/yr. The mean volume of osteolysis progression was 3.2cm3/yr (range 1.1–7.5cm3/yr). Progression in size of osteolytic lesions was significantly associated with hips with larger osteolytic lesions at the initial CT (p=0.0004). Radiographic measurements detected progression of osteolytic lesions in 5 of the 10 hips (50%) that progressed. No correlation was found between progression in size of osteolytic lesions as measured by CT and progression in size of osteolytic lesions as measured off the anteroposterior pelvis (r2 = 0.16, p=0.37), oblique (r2=0.37, p=0.15) and combined anteroposterior pelvis and oblique radiographs (r2=0.34, p=0.17). Periacetabular osteolytic lesions are more likely to be detected on plain radiographs if they are more than 10cm3 in size. Plain radiographs may therefore provide some monitoring value as lesions more than 10cm3 are more likely to be progressive. However, plain radiographs should not be relied upon to monitor the progression of these lesions.
Differentially loaded radiostereometric analysis (DLRSA) uses RSA whilst simultaneously applying load to the bones under investigation. This technique allows measurement of interfragmentary translations and rotations under measured weight bearing and joint movement. We have recently introduced this technique to monitor tibial plateau fracture healing. This paper presents our preliminary results. Twelve patients with a 41 B2, B3, C2, or C3 fracture were followed for a minimum of three months. RSA beads were inserted in the largest osteochondral fragment and the adjacent metaphysis. Knee flexion was restricted to 60° for 6 weeks. After partial weight bearing (20kg) between 2 and 6 weeks, patients progressed to full weight bearing. Follow up included clinical and radiological examinations and patient reported outcome scores (Lysholm, KOOS). DLRSA examinations included RSA radiographs in 60° flexion and under measured weight bearing. Significant interfragmentary displacement was defined as translations greater than 0.5mm and/or rotations greater than 1.5°. There was no loss to follow-up. Longitudinal RSA follow-up: Follow-up RSA radiographs were compared to postoperative examinations. Osteochondral fragment depression was less than 0.5mm in seven patients and between 2 and 4mm in the remaining five patients. Significant interfragmentary displacement after three months was recorded in three patients. DLRSA flexion results: Under 60° of flexion, translations over 0.5mm were recorded in five patients (one postoperatively; one at 2 weeks; two at 6 weeks; and one postoperatively, at 2 weeks and at 3 months). Rotations over 1.5° were recorded in six patients (one postoperatively; two at 2 weeks; one at 6 weeks; one at 2 weeks, 3 months and 4.5 months; and one postoperatively, at 2 weeks, 3 months and 6 months). DLRSA weight bearing results: Under partial weight bearing at two weeks, two patients recorded significant translations, one involving a significant rotation. Under weight bearing as tolerated, three patients recorded significant translations (one at 6 weeks; and two at 18 weeks) and four patients recorded significant rotations (one at 6 weeks; one at 18 weeks; and two at 12 and 18 weeks). Patient Reported Outcomes: Both the Lysholm and KOOS scores improved between 6 weeks and 3 months. DLRSA provides new insight and perspective in tibial plateau fractures. Some fractures take more than three months to heal. Our current rehabilitation protocol was safe in most patients, however significant interfragmentary displacement was encountered in 17% at the 2 week followup, raising questions about the quality of the initial stability.
Differentially loaded radiostereometric analysis (DLRSA) uses RSA whilst simultaneously applying load to the bones under investigation. This technique allows measurement of interfragmentary translations and rotations under measured amounts of weight bearing. The aim of this paper was to measure the mechanical stiffness of distal femoral fractures during healing. Six patients with a 33A2, 33A3, 33B2 and 33C2 fracture were treated with open reduction, internal fixation using a long bridging plate. All patients had a DLRSA examination at 6, 12, 18 and 26 weeks postoperatively. Each DLRSA examination consisted of RSA radiographs taken without load (pre-load), under different increments of load, and finally, without load (post-load). The direction and magnitude of the interfragmentary displacements in six degrees of freedom were recorded at each examination. DLRSA examinations were able to monitor the inter-fragmentary displacements of the distal femoral fragment relative to the femoral shaft. The interfragmentary displacement recorded, progressively increased as more load was applied in all patients, at all follow-up time points. The two dimensional (2D) translations under maximum tolerated load, progressively decreased over time in three patients. The 2D translations recorded under 60 kg of load at 26 weeks for these patients was 0.18, 0.21 and 0.27mm. The 2D translations of two patients did not decrease progressively between 6 and 18 weeks but did decrease at 26 weeks to 0.47 and 0.75mm. One patient recorded 2D translations of 4.11, 3.48 and 4.53mm under 30kg at 12, 18 and 26 weeks respectively. In the majority of examinations, post-load radiographs enabled the interfragmentary displacements under load to be identified as elastic in nature. The DLRSA stiffness data confirmed that at 26 weeks three patients had united; two were delayed but improving; and one was a clear non-union without progression. DLRSA examinations may be used as a clinical research tool. to monitor in vivo the stiffness of healing femoral fractures fixed with “relative stability”.
Irradiating allograft bone may compromise the mechanical stability of the prosthesis-bone construct, potentially having adverse effects on the outcome of femoral impaction grafting at revision hip replacement. This in vitro study aimed to determine the effect of irradiation of allograft bone used in femoral impaction grafting on initial prosthesis stability. Morsellised ovine femoral head bone was irradiated at 0 kGy (control), 15 kGy and 60 kGy. For each group, six ovine femurs were implanted with a cemented polished double taper stem following femoral impaction bone grafting. Dynamic hip joint loading was applied to the femoral head using a servo-hydraulic materials testing machine. The primary outcome was stem micromotion. Tri-axial micromotion of the stem relative to the bone at two sites was measured using linear variable differential transformers and non-contact laser motion transducers. Statistical analysis was performed using SPSS. Compared to the control and 15 kGy groups, specimens in the 60 kGy group demonstrated statistically significant greater micromotion in the axial, antero-posterior and medio-lateral axes. A multi-factorial post-hoc power analysis based on the overall effect of group size indicated a power of 0.7. There was no difference in micromotion between the control and 15 kGy groups. The average micromotion in the axial axes was 63μm in the control and 59μm in the 15 kGy group. The results of this study suggest that a maximum irradiation dose of 15 kGy may not affect initial prosthesis stability following femoral impaction grafting in this model and provide the basis for us to now proceed to in-vivo studies examining the effect of irradiated bone on implant stability over time.
Periprosthetic osteolysis is a serious medium to long-term complication of total hip arthroplasty. Interobserver reliability of detecting osteolysis around cementless ace-tabular components is reported to be poor using plain radiographs. Quantitative computed tomography (CT) provides sensitive and accurate measures of osteolytic lesion volume, however, there may remain a role for plain radiographs in monitoring progression of osteolysis. The aim of this study was to use quantitative CT to monitor the progression of osteolytic lesions around cementless acetabular components and to compare plain radiographs and CT in determining the progression of osteolysis. A high-resolution multi-slice quantitative CT scanner with metal artefact suppression was used to determine the volume of osteolysis around 18 cementless acetabular components. The mean time since arthroplasty was 14 years (range 10–15 years) at the initial CT. Repeat scans of the hip were undertaken over a five-year period to determine progression of osteolysis with time. A second blinded observer examined anteroposterior and lateral plain radiographs taken at the same time as the CT scans and measured the location and area of osteolytic lesions. CT measurements determined that in ten of 18 hips (56%), osteolytic lesions progressed by more than 1cm3/yr. Progression in size of osteolytic lesions was significantly associated with hips with larger osteolytic lesions at the initial CT (p=0.0005). The mean volume of osteolysis progression was 4.9cm3/year (range 2.8–7.5cm3/yr) for cases with osteolysis volumes greater than 10cm3 at the initial CT, and 0.7cm3/yr (range 0–2.3cm3/yr) for cases with osteolysis volumes smaller than or equal to 10cm3 at the initial CT (p=0.002). Importantly, the rate of osteolysis progression between CT scans varied greatly in some hips. In contrast, using plain radiograph assessment, progression in the area of osteolytic lesions was only detected in 10% of hips. In conclusion, quantitative CT provides new insights into the natural history of periacetabular osteolysis. Total osteolysis volume greater than 10cm3 is associated with a high risk of progression and progress, on average, at a greater rate than those less than 10cm3. Plain radiographs, including a lateral view, are an unreliable clinical diagnostic tool to predict substantial progression of periacetabular osteolytic lesions.
Relatively high rates of fracture of the femoral stem of total hip replacements were seen with early designs manufactured with stainless steel. Improvements in metallurgy, alloy chemistry, materials and stem design have led to a reduction in the incidence of this complication and the occurrence of fracture with modern femoral stems is a now a rare event. However, the implantation of modern stems into heavy patients and the use of higher offset stems leads to considerable testing of the mechanical capabilities of some stem designs. We present ten cases of fracture of modern stainless steel polished tapered stems. The fractures occur either in the neck, or in the distal half of the stem. Our clinical data suggests that heavy patients with small stems and high offsets are at risk of breaking their implants. Varus positioning of the stem in a number of cases further increases the bending moment of the stems, and the sacrifice of cement mantle thickness for implant size within narrow medullary canals may lead to the loss of proximal support. Failure analysis of the retrieved high nitrogen stainless stems also suggests there may be metallurgical factors that contribute to their failure. On the basis of our findings, careful consideration is required when using high offset stainless steel stems in large patients.
In relation to the conduct of this study, one or more of the authors is in receipt of a research grant from a non-commercial source.
In relation to the conduct of this study, one or more of the authors is in receipt of a research grant from a non-commercial source.
In relation to the conduct of this study, one or more of the authors is in receipt of a research grant from a non-commercial source.
The purpose of health outcomes monitoring is to assess the benefits and risks of health care processes, to enable benchmarking and to allow comparative studies of new technologies and variations in clinical practice. This paper critically reviews the discipline of health outcomes monitoring in joint replacement surgery. We reviewed over 250 papers published over the last 20 years in the major English speaking journals were reviewed. We conclude that there are considerable shortcomings of clinical studies which make it difficult to determine the results of different joint replacement designs. The shortcomings include inadequate study design and the lack of comparative data. Despite repeated calls for standardisation of outcome measures, this has yet to be achieved. Considerable resources are often invested in outcomes monitoring programs.It is therefore important that instruments are selected based on them meeting strict psychometric criteria, that adequate follow-up is achieved and that appropriate data analysis techniques are utilised, otherwise interpretation of results is difficult. We have found that patients’ reporting of symptoms and outcomes after hip arthroplasty were found to be consistent with those reported by their reviewing doctor. We therefore suggest that for uncomplicated joint arthroplasty cases, the marginal costs of their regular review in outpatients probably outweighs the marginal benefits and important resources and doctors time would be made available for other patient care activity if these patients were reviewed by patient self-administered questionnaires. Our studies have shown that SF-36 health survey and the WOMAC instruments are useful when administered by mailed survey, however, the cost-benefits of using these outcomes instruments is an important consideration. The lack of comparable outcomes data should encourage greater orthopaedic participation in multi-centre outcomes studies including randomised trials.
Reported rates of dislocation after primary and revision total hip replacement (THR) vary widely, whereas subluxation after THR is not commonly reported. Importantly, it is now recognised that reported dislocation rates are likely to be an underestimate of the true dislocation rate. The primary aim of this study was to develop and validate a Patient Hip Instability Questionnaire and subsequently to use this questionnaire to determine the incidence of dislocation, subluxation and symptoms due to hip instability following primary and revision THR. In addition the associated costs, morbidity, disability and effects on health-related quality of life were examined. A retrospective review of dislocation rates from 1996 to 1998 identified problems in determining the true dislocation rate from standard hospital and database records. Therefore, a patient-completed Hip Instability Questionnaire was developed and validated to monitor dislocation and subluxation rates. This was then mailed to patients three and 12 months following primary or revision THR. All dislocations were then confirmed by telephone interview and radiographs. Telephone interviews and patient completion of the SF-36 questionnaire were used to assess morbidity, disability and quality of life. Costs of treating patients with hip dislocation were also determined. The response rate to the mailed questionnaire was greater than 95%. The questionnaire was shown to be a valid measure of the true rate of dislocation following THR and confirmed the inaccuracies in previous methods of determining dislocation rate based on hospital and database records. Using this questionnaire, the rate of subluxation was higher than previously reported and the significant morbidity and health care costs associated with with this complication were identified. The use of this questionnaire will allow better assessment of morbidity and costs due to complications following THR.
Loosening was classified as possible if there was between 50 and 99 percent c-b radiolucency, probable when there was complete radiolucency, or definite when vertical subsidence was more than 5mm. The presence and type of radiological features analysed according to surgeon and whether a centraliser was utilised.
Wear particles are thought to be a major factor causing osteolysis that leads to aseptic loosening. The aim of this study was to investigate the role of primary regulators of osteoclast development, RANKL (also known as osteoclast differentiation factor), its receptor RANK and natural inhibitor osteoprotegerin (OPG) in aseptic loosening. Cells were isolated from periprosthetic tissues taken at revision from more than 30 patients and the expression of these mediators in vivo was assessed using semi-quantitative reverse transcription polymerase chain reaction (RT-PCR). These cells were also cultured on dentine to determine their ability to become mature osteoclasts. In situ hybridisation using DIG labelled riboprobes specific for RANK mRNA was used to identify cells likely to become osteoclasts. We were able to compare revison tissues containing several different types of prosthetic wear particles. RANKL, RANK and OPG mRNA were found in samples of periprosthetic revision tissues. Cells derived from this tissue developed into mature osteoclasts capable of resorbing dentine. Cells that rapidly formed osteoblasts expressed a fifteen fold higher ratio of RANKL:OPG mRNA. In situ hybridisation showed RANK expression by macrophages and giant cells, many of which contained wear particles. Significantly, cells from tissues containing silastic wear particles expressed higher levels of RANKL relative to OPG and more produced large numbers of osteoclasts in vitro. This study shows that different bio materials in a particulate form may differ in their ability to form osteoclasts and that the relative levels of RANKL and OPG are likely to be important in determining if osteolysis will occur. In the future molecules that inhibit RANKL binding, such as OPG, may be considered for therapy of periprosthetic osteolysis.
There is a lack of properly undertaken comparative studies of total hip replacement (THR). A randomised trial was established to examine the hypothesis that there are no important differences in clinical outcome at 2 years and at long-term follow-up between cemented and uncemented primary THR in middle aged patients.Eighty-three patients with 90 osteoarthritic hips were randomised to a cemented Exeter THR involving a matte or polished tapered stem (n=47, median age 68yrs) or an uncemented PCA proximally porous-coated cobalt-chrome stem and porous coated press fit cup (n=43, median age 66yrs). Patients underwent immediate full weight bearing post-operatively. The follow-up period is 8 to 16 years. The median Harris hip scores for the cemented and uncemented groups respectively were 92 and 95 at 2 years and 89 and 96 at long-term follow-up. Four cemented hips have been revised for aseptic loosening. There have been no failures of the polished stems. An analysis of a larger series of matt versus polished cemented stems also found that the results of the polished stems were superior. Four uncemented hips have been revised, two more recently for acetabular wear and osteolysis. There was a high rate of radiographic demarcation of the cemented cups. There were no important differences in the clinical scores between cemented and uncemented THR. Some matte surfaced femoral stems failed and this trend was confirmed by analysis of a larger series. Osteolysis around the uncemented acetabular components is a concern. Importantly immediate weight bearing was associated with good results of uncemented stems.