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Background and purpose — Cup wear in total hip arthroplasty (THA) can be affected by different manufacturing processes of the polyethylene (PE). We report the long-term wear pattern differences, as well as early creep behavior, between conventional PE and highly cross-linked PE (HXLPE) liners, as measured with radiostereometry (RSA) up to 10 years. We also compare migration and clinical outcome of 2 similar uncemented cups with different backside surface roughness. Patients and methods — We included 45 patients with primary osteoarthritis. 23 received a conventional liner and 22 an HXLPE liner in a similar uncemented cup, but with a slightly rougher surface. The patients were followed up with RSA and hip-specific outcome questionnaire (HOOS) at 3 months, 1, 2, 5, and 10 years. Results — During the first 3 months both liners showed expected deformation with mean proximal head penetration of 0.39 mm (conventional PE) and 0.21 mm (HXLPE). Between 3 months and 10 years there was a difference in annual wear with 0.12 mm/year for the conventional liner and 0.02 mm/year for the HXLPE liner. The cup with rougher surface had less initial migration but both types had stabilized after 3 months. The HOOS scores improved after surgery and remained high for both groups throughout the study period. Interpretation — Up to 10 years the HXLPE has consistent lower annual wear, possibly contributing to longer survival of the THA, compared with conventional PE. All patients reported good results regardless of liner type.

Background Regenerex® is a porous titanium construct with a 3D interconnecting pore structure and biomechanical characteristics close to that of normal trabecular bone. This study aimed to compare the Regenerex (VR) to the non-interconnecting pore structure Porous Plasma Spray (VP) on tibial implants for total knee arthroplasty (TKA) at 5 years. Methods We enrolled and randomized 61 patients (mean age = 63(49–71) years, Female/Male = 35/26) who were planned for an uncemented Vanguard TKA (Biomet, Warsaw, Indiana, USA) to receive either a VR or a VP coated tibial component (31/29). We performed radiostereometric analysis (RSA) and Dual Energy X-ray Absorptiometry (DEXA) postoperatively, and at three, six, 12, 24 and 60 months with measurements of migration. In total 55 patients attended the 5-year follow-up. Results One patient died and four were reoperated during the 60-months period; none due to aseptic loosening. All reoperations were in the VR-group. The mean (range) 60-months MTPM was 1.4 mm (0.5–3.7) for the VP-group and 1.8 mm (0.4–4.9) for the VR-group (p = 0.8). The 24 to 60-months mean (range) MTPM was −0.3 mm (−5 to 1.24) in the VP-group and 0.2 mm (−0.4 to 3.5) in the VR-group (p = 0.8). Conclusion We did not find any statistically significant differences between the VP- and VR-group and both groups show recognizable migration. We will continue to follow the groups for years to come.

Background Inferior placement of a femoral stem is predictive for early loosening and failure, but does restoration of the original hip anatomy benefit the function and survival of a total hip replacement? Methods Seventy-five patients with primary unilateral hip osteoarthritis operated with an uncemented anatomical stem were randomized for either standard or modular stems. We used 50 ABG II stems with modular necks and 25 standard stems (control group). We measured the symmetry in hip anatomy between healthy and operated side. The anatomical restoration variables were anteversion, global offset, and femoral offset/acetabular offset (FO/AO) quota. We performed measurements using a CT-based 3D templating and measuring software. Migratory behavior of the stems was then measured postoperatively with repeated radiostereometry (RSA) examinations over 5 years. Results Both stem types showed an early (within 3 months) good stabilization after an initial slight rotation into retroversion and subsidence. There were no significant differences in RSA migration between modular and standard stems. Postoperative anteversion and FO/AO quota had no impact on stem migration. The standard stem tended to result in insufficient global offset (GO), whereas the modular stem did not. Conclusions The modular stem gave good symmetrical anatomical restoration and, like the standard version, a benign migratory behavior. Anteversion, GO, and FO/AO quota had no significant impact on stem migration. It therefore seems to be of no importance whether we choose a modular or a standard stem with regard to postoperative stem migration for this stem type. We overestimated the effect anatomical parameters have on stem movement; hence, we believe the study to be underpowered. Trial registration ClinicalTrials.gov identifier: NCT01512550. Registered 19 January 2012—retrospectively registered

Background: There is an increasing interest in shorter, proximally loading, uncemented femoral stems. The aim of this study was to evaluate a new short stem type, its design based on a well-proven precursor, but with several new design features to facilitate easier insertion and possible preservation of proximal bone stock. It is available with or without a collar. Methods: The study includes 50 patients with primary osteoarthritis, mean age 59 (range 36–75) years, randomised to receive either the collar-fitted or the collarless stem. The patients underwent repeated radiostereometry (RSA) examinations (0, 0.5, 3, 12, 24 months), conventional radiography and filled out both hip-specific (HOOS) and general health (EQ-5D) questionnaires. Results: There was no statistically significant difference between the collared and collarless stems regarding migration and clinical outcome. Both stem types exhibit a similar pattern of initial subsidence (collared 0.63 mm vs. collarless 0.75 mm [ p = 0.50]) and retroversion (collared 0.71° vs. collarless 0.97° [ p = 0.36]) up to 3 months followed by stabilisation, in similarity with its precursors, suggesting good osseointegration. No stem has been revised or considered loose. Conclusions: The new design features, including shortening the stem, do not compromise migration pattern or osseointegration, regardless collar or not.

Radiological and pathological characteristics of hip osteoarthritis (OA) is joint-space loss due to degradation of articular cartilage. However, patients with early-stage OA do not yet show any rad...

Background Aseptic loosening is one of the major reasons for late revision in total knee arthroplasty (TKA). The risk of aseptic loosening can be detected using radiostereometric analysis (RSA), whereby micromovements (migration) can be measured, and thus RSA is recommended in the phased introduction of orthopedic implants. Decrease in bone mineral density (BMD), as measured by dual-energy x ray absorptiometry (DXA), is related to the breaking strength of the bone, which is measured concurrently by RSA. The aim of the study was to evaluate bone remodeling and implant migration with cemented asymmetrical tibial and uncemented femoral components after TKA with a follow up period of 2 years. Methods This was a prospective longitudinal cohort study of 29 patients (number of female/male patients 17/12, mean age 65.2 years), received a hybrid Persona® TKA (Zimmer Biomet, Warsaw, IN, USA) consisting of a cemented tibial, an all-polyethylene patella, and uncemented trabecular metal femoral components. Follow up: preoperative, 1 week, and 3, 6, 12 and 24 months after surgery, and double examinations for RSA and DXA were performed at 12 months. RSA results were presented as maximal total point of motion (MTPM) and segmental motion (translation and rotation), and DXA results were presented as changes in BMD in different regions of interest (ROI). Results MTPM at 3, 6, 12, and 24 months was 0.65 mm, 0.84 mm, 0.92 mm, and 0.96 mm for the femoral component and 0.54 mm, 0.60 mm, 0.64 mm, and 0.68 mm, respectively, for the tibial component. The highest MTPM occurred within the first 3 months. Afterwards most of the curves flattened and stabilized. Between 12 and 24 months after surgery, 16% of femoral components had migrated by more than 0.10 mm and 15% of tibial components had migrated by more than 0.2 mm. Percentage change in BMD in each ROI for distal femur was as follows: ROI I 26.7%, ROI II 9.2% and ROI III 3.3%. BMD and at the proximal tibia: ROI I 8.2%, ROI II 8.6% and ROI III 7.0% after 2 years compared with 1 week postoperative results. There was no significant correlation between maximal percentwise change in BMD and MTPM after 2 years. Conclusion Migration patterns and changes in BMD related to femoral components after TKA in our study correspond well with previous studies; we observed marginally greater migration with the tibial component.

Background and purpose — It is believed that in uncemented primary total hip arthroplasty (THA) the anchorage of the stem is dependent on the level of bone mineral density (BMD) of the femoral bone. This is one of the reasons for the widely accepted agreement that a cemented solution should be selected for people with osteoporosis or age > 75 years. We evaluated whether preoperative BMD of the femur bone is related to femoral stem migration in uncemented THA. Patients and methods — We enrolled 62 patients (mean age 64 years (range 49–74), 34 males) scheduled for an uncemented THA. Before surgery we undertook DEXA scans of the proximal femur including calculation of the T- and Z-scores for the femoral neck. Evaluation of stem migration by radiostereometric analysis (RSA) was performed with 24 months of follow-up. In 56 patients both preoperative DEXA data and RSA data were available with 24 months of follow-up. Results — None of the patients had a T-score below –2.5. We found no statistically significant relationship between preoperative BMD and femoral stem subsidence after 3 or 24 months. When comparing the average femoral stem subsidence between 2 groups with T-score > –1 and T-score ≤ –1, respectively, we found no statistically significant difference after either 3 or 24 months when measured with RSA. Interpretation — In a cohort of people ≤ 75 years of age and with local femur T-score > –2.5 we found no relationship between preoperative BMD and postoperative femoral stem subsidence of a cementless THA.

BackgroundGlenohumeral osteoarthritis can, in the most severe cases, require surgery with insertion of a shoulder arthroplasty. A design with a stem in the humeral bone canal is currently regarded as the standard treatment option in patients who have an intact rotator cuff function, but complications related to the stem including humeral fractures can have devastating consequences. By using a stemless humeral component, stem-related complications can be reduced. The aim of this study is to compare the Comprehensive Nano stemless total shoulder arthroplasty (intervention group) with the Comprehensive stemmed total shoulder arthroplasty (control group).Materials and methodsThis is a randomized controlled trial comparing the stemless and the stemmed total shoulder arthroplasty. All Danish citizens with glenohumeral osteoarthritis indicating a total shoulder arthroplasty referred to the orthopedic department at Copenhagen University Hospital in Herlev/Gentofte will be offered participation. The following exclude from participation: below 18 years of age, cognitive or linguistic impairment, insufficient function of the rotator cuff, poor bone quality, and ASA groups 4–5. A total of 122 patients will be included of which 56 will be part of a radiostereometric analysis (RSA) study of humeral component migration. The primary outcomes are magnitude of migration of the humeral component assessed by RSA and patient-reported outcome by Western Ontario Osteoarthritis of the Shoulder index (WOOS). The secondary outcomes are additional patient-reported outcomes, functional outcome, readmission, complications, revisions, and changes in bone mineral density (BMD) of the proximal humerus assessed by duel energy x-ray absorptiometry (DXA) and economy (cost-utility analysis). The patients are examined before the operation and 3, 6, 12, and 24 months postoperative.DiscussionTo our knowledge, RSA has never been used to access migration of a stemmed or a stemless humeral component nor has the stemmed and the stemless humeral component been compared with regard to pain relief and shoulder function in a randomized clinical trial. Today, the two designs are considered equal in the treatment of osteoarthritis. The study will provide surgeons and patients with information about shoulder arthroplasty for osteoarthritis and assist them in decision-making.Trial registrationClinicalTrials.govNCT04105478. Registered on 25 September 2019

Background Restoration of a correct biomechanical situation after total hip arthroplasty is important. Purpose To evaluate proximal femoral symmetry of acetabular and femoral offset and femoral neck anteversion pre- and postoperatively in hip arthroplasty by semi-automated 3D-CT and to validate the software measurements by inter- and intraobserver agreement calculations. Material and Methods In low-dose CT on 71 patients before and after unilateral total hip arthroplasty, two observers used a digital 3D templating software to measure acetabular offset, true and functional femoral offset, and femoral neck anteversion. Observer agreements were calculated using intraclass correlation. Hip measurements were compared in each patient and between pre- and postoperative measurements. Results Preoperatively, acetabular offset (2.4 mm), true (2.2 mm), and functional global offset (2.7 mm) were significantly larger on the osteoarthritic side without side-to-side differences for true and functional femoral offset or femoral neck anteversion. Postoperatively, acetabular offset was significantly smaller on the operated side (2.1 mm) with a concomitantly increased true (2.5 mm) and functional femoral offset (1.5 mm), resulting in symmetric true and functional global offsets. There were no differences in postoperative femoral neck anteversion. Inter- and intraobserver agreements were near-perfect, ranging between 0.92 and 0.98 with narrow confidence intervals (0.77–0.98 to 0.94–0.99). Conclusion Acetabular and concomitantly global offset are generally increased in hip osteoarthritis. Postoperative acetabular offset was reduced, and femoral offset increased to maintain global offset. 3D measurements were reproducible with near-perfect observer agreements. 3D data sets should be used for pre- and postoperative measurements in hip arthroplasty.

Background A common bearing combination in total hip arthroplasty today is a metal femoral head articulating with polyethylene in the cup. Ceramic heads are thought to be more resistant to third-body damage, and have better wettability and decreased surface roughness, which taken together have been suggested to result in less polyethylene wear. The purpose of this study is to compare the initial creep deformation and follow wear pattern, using radiostereometric analysis, of ceramic and metal femoral heads that articulate with a modern highly cross-linked polyethylene cup liner. Methods Fifty patients with primary osteoarthritis and scheduled for an uncemented total hip arthroplasty were randomized 1:1 to either a ceramic (BIOLOX delta) or a metal (CoCr) femoral head. The patients were followed up for 5 years with repeated radiostereometric analysis examinations (postoperatively, then at 14 days, 3, 12, 24, and 60 months), as well as a hip-specific outcome questionnaire. Results During the first 3 months both groups showed expected creep within the liner of 0.12 mm (standard deviation 0.03) for the ceramic and 0.08 mm (standard deviation 0.02) for the metal heads. Between 3 months and 5 years there was very little wear of the liner in either group, corresponding to 0.003 mm/y for ceramic and 0.007 mm/y for metal heads. There was no difference in cup migration or clinical outcome between the groups and no cups were revised. Conclusion With the introduction of modern highly cross-linked polyethylene, the ceramic head demonstrates no superiority when it comes to either early deformation or polyethylene wear compared with the metal head.

Background and purpose — Despite the good results after total hip arthroplasty (THA), new implants are continuously being developed to improve durability. The Echo Bi-Metric (EBM) THA stem is the successor to the Bi-Metric (BM) THA stem. The EBM stem includes many of the features of the BM stem, but minor changes in the design might improve the clinical performance. We compared the migration behavior with radiostereometric analysis (RSA) of the EBM stem and the BM stem at 24 months and evaluated the clinical outcome. Patients and methods — We randomized 62 patients with osteoarthritis (mean age 64 years, female/male 28/34) scheduled for an uncemented THA to receive either an EBM or a BM THA stem. We performed RSA within 1 week after surgery and at 3, 6, 12, and 24 months. The clinical outcome was evaluated using Harris Hip Score (HHS) and Oxford Hip Score (OHS). Results — At 24 months, we found no statistically significant differences in migration between the two implants. During the first 3 months both the EBM and the BM stems showed visible subsidence (2.5 mm and 2.2 mm respectively), and retroversion (2.5° and 2.2° respectively), but after 3 months this stabilized. The expected increase in HHS and OHS was similar between the groups. Interpretation — The EBM stem showed a migration at 24 months not different from the BM stem, and both stems display satisfying clinical results.

Background and purpose — Impaction bone grafting (IBG) in revision hip surgery is an established method in restoring bone stock deficiencies. We hypothesized that local treatment of the morsellized allograft with a bisphosphonate in cemented revision would, in addition to increased bone density, also reduce the early migration of the cup as measured by radiostereometry (RSA). Patients and methods — 20 patients with aseptic cup loosening underwent revision using the IBG technique. The patients were randomized to either clodronate (10 patients) or saline (10 patients, control group) as local adjunct to the morsellized bone. The outcome was evaluated by dual-energy X-ray absorptiometry (DXA) during the first year regarding periacetabular bone density and with radiostereometric analysis (RSA) for the first 2 years regarding cup migration. Results — 2 patients were lost to follow-up: 9 patients remained in the clodronate and 9 in the control group. Less proximal migration was found in the clodronate group compared with the controls, measured both over time (mixed-models analysis, p = 0.02) as well as at the specified time points up to 2 years (0.22 mm and 0.59 mm respectively, p = 0.02). Both groups seemed to have stabilized at 1 year. We found similar bone mineral density measured by DXA, and similar RSA migration in the other directions. No cups were re-revised. Interpretation — Local treatment of the allograft bone with clodronate reduced early proximal migration of the revised cup but without any measurable difference in periacetabular bone density.

Background Porous metal augments have been used successfully for management of large acetabular defects during revision hip arthroplasty. The purpose of this study was to retrospectively review and compare the clinical and radiographic outcomes of porous metal augments in cemented and uncemented acetabular revisions, all performed at the same institution. Methods Using our institutional clinical databases, the clinical and radiological outcomes of 104 cemented and 43 uncemented acetabular revisions with metal augments, performed between 2006 and 2015, were studied and compared. Acetabular augments were used when preoperative and intraoperative findings indicated the presence of large acetabular defects that can hinder the stability of the revision implants. Results At a mean follow-up of 60.1 months (range 12.7-112.1), a total of 5 cups (3.4%), being 3 cemented (2.8%) and 2 uncemented (4.6%), had shown signs of aseptic loosening with cup and augment migration and 4 of these have been re-revised (2.7%). At final follow-up, the European Quality of Life-5 Dimensions for generic health, and the Hip disability and Osteoarthritis Outcome Score (HOOS) parameters had improved substantially without any significant difference between fixation techniques. Conclusion Porous metal augments show comparable excellent radiographic and clinical mid-term outcomes when combined with cemented or uncemented cups in revision hip arthroplasty.

Background and purpose — A tapered, polished and collarless stem is normally equipped with a hollow centralizer to prevent the stem from becoming end-bearing in the cement as the stem subsides. In a randomized clinical trial, we evaluated such a stem (MS-30), which was initially introduced with a solid centralizer but was later recommended to be fitted with a hollow centralizer. We hypothesized that while the stem would sink more, it would become rotationally stable and have less retroversion with a hollow centralizer than with a solid centralizer. Patients and methods — We randomized 60 patients with primary hip arthritis to receive either a hollow centralizer or a solid centralizer with the stem. The effect was evaluated over a 10-year follow-up period with repeated RSA examinations, conventional radiographs, and clinical follow-ups using the WOMAC and SF-12 questionnaires. Results — At 10-year follow-up, the group with hollow centralizers had subsided more than the group with solid centralizers (1.99 mm (hollow) as opposed to 0.57 mm (solid); p < 0.001). However, rotation was similar at 10-year follow-up (mean retroversion 1.34° (hollow) and 1.30° (solid)). Both groups showed excellent 10-year results, with similar clinical outcome, and none of the stems were radiographically loose or had been revised. Interpretation — As expected, there was more subsidence in the group with hollow centralizers, and with similar magnitude to that reported in earlier RSA studies on conceptually similar prostheses. Interestingly, there was no difference in the rotational behavior of the prostheses. This stem type appears to have a design that, regardless of the type of centralizer and the possibility of subsidence, withstands the rotational forces it is subjected to very well. This study does not support the need for a hollow centralizer for these types of stems.

Background Recently, total hip arthroplasty (THA) has come to focus on restoration of individual anatomy including femoral neck anteversion and global offset (femoral and acetabular offset). Three-dimensional (3D) computed tomography (CT) data could provide a better basis for preoperative templating. The use of CT has been hampered by high radiation dose. Purpose To evaluate the effective dose used in pelvis and hip CT for THA templating. Material and Methods CT data from two clinical trials of THA were evaluated for CT scan length and volume CT dose index (CTDIvol). The effective doses from hip-knee-ankle CT and pelvis and hip radiography were compared. Conversion factors for effective dose for radiography were calculated using the PCXMC software. Results A reduced dose CT protocol for pelvis imaging gave a substantial dose reduction compared with standard CT, while maintaining sufficient image quality. Between the two clinical trials there was a significant reduction in effective CT dose corresponding to changes in the CT protocol ( P Conclusion Although the CT dose remained higher than for radiography, potential reductions in scan length could reduce the dose further so that CT would have a comparable level of risk to radiography with the added benefit of 3D templating.

Introduction: In contrast to cemented hip prostheses, the effect of washing the bone bed with jet-lavage prior to insertion of cementless stem components in primary hip arthroplasty (THA) is unclear. Jet-lavage potentially decreases the risk of fat embolisation during rasping and stem insertion and might help in avoiding bacterial contamination. An earlier animal study has shown less debris and better-organised trabecular structure of new bone when jet-lavage was used. We hypothesised that the primary stability of cementless femoral stems implanted after jet-lavage of the femoral canal prior to stem insertion would improve with earlier stabilisation, as measured with Radiostereometry (RSA), compared with insertion without prior jet-lavage. Methods: 40 patients with primary osteoarthritis operated on with a cementless titanium grit blasted stem are included in the study. The patients were randomised to either jet-lavage or control without any lavage of the femoral canal prior to insertion of the prosthesis. The stem migration pattern was measured with RSA at 0, 3, 12, 24 and 72 months. Results: At 6 years, 19 patients remained for analysis in the jet-lavage and 18 in the control group. We found no difference in extent or pattern of migration as measured with RSA. Both groups seemed to have stabilised within 3 months after a slight subsidence and retroversion. No stem was revised or considered loose as measured with RSA. Conclusions: Washing the bone bed with jet-lavage prior to insertion of cementless stems does not affect the stability of cementless femoral components. No adverse effects were observed.

Background and purpose — Backside wear of the polyethylene insert in total knee arthroplasty (TKA) can produce clinically significant levels of polyethylene debris, which can lead to loosening of the tibial component. Loosening due to polyethylene debris could theoretically be reduced in tibial components of monoblock polyethylene design, as there is no backside wear. We investigated the effect of 2 different tibial component designs, monoblock and modular polyethylene, on migration of the tibial component in uncemented TKA. Patients and methods — In this randomized study, 53 patients (mean age 61 years), 32 in the monoblock group and 33 in the modular group, were followed for 2 years. Radiostereometric analysis (RSA) was done postoperatively after weight bearing and after 3, 6, 12, and 24 months. The primary endpoint of the study was comparison of the tibial component migration (expressed as maximum total point motion (MTPM)) of the 2 different implant designs. Results — We did not find any statistically significant difference in MTPM between the groups at 3 months (p = 0.2) or at 6 months (p = 0.1), but at 12 and 24 months of follow-up there was a significant difference in MTPM of 0.36 mm (p = 0.02) and 0.42 mm (p = 0.02) between groups, with the highest amount of migration (1.0 mm) in the modular group. The difference in continuous migration (MTPM from 12 and 24 months) between the groups was 0.096 mm (p = 0.5), and when comparing MTPM from 3–24 months, the difference between the groups was 0.23 mm (p = 0.07). Interpretation — In both study groups, we found the early migration pattern expected, with a relatively high initial amount of migration from operation to 3 months of follow-up, followed by stabilization of the implant with little migration thereafter. However, the modular implants had a statistically significantly higher degree of migration compared to the monoblock. We believe that the greater stiffness of the modular implants was the main reason for the difference in migration, but an initial creep in the polyethylene metal-back locking mechanism of the modular group could also be a possible explanation for the observed difference in migration between the 2 study groups.

Background: Bisphosphonates have previously been shown to increase the density of impacted graft bone. In the present study we hypothesise that bisphosphonates also reduce early stem subsidence. We examined the effect of locally applied bisphosphonate to allografts on prosthetic micromotion and bone density in femoral stem revision with impaction grafting. Methods: 37 patients were randomised to either clodronate or saline as local adjunct to the morsellised allograft bone. 24 patients were finally analysed per protocol and evaluated by dual-energy x-ray absorptiometry (DXA) during the first year and with radiostereometric analysis (RSA) for 5 years. Results: There were no significant differences neither in bone density, nor in migratory behaviour between the groups. The femoral stems had subsided 3.6 mm in both groups (p = 0.99) at 5 years and there was no difference as measured over time with mixed models analysis. The clinical outcome was good in both groups. Conclusion: Clodronate as a local addendum to allograft bone in hip revision did not increase bone density or reduce micromotion of the implant.

Background and purpose - Impaction bone grafting (IBG) in revision hip surgery is an established method in restoring bone stock deficiencies. We hypothesized that local treatment of the morsellized allograft with a bisphosphonate in cemented revision would, in addition to increased bone density, also reduce the early migration of the cup as measured by radiostereometry (RSA). Patients and methods - 20 patients with aseptic cup loosening underwent revision using the IBG technique. The patients were randomized to either clodronate (10 patients) or saline (10 patients, control group) as local adjunct to the morsellized bone. The outcome was evaluated by dual-energy X-ray absorptiometry (DXA) during the first year regarding periacetabular bone density and with radiostereometric analysis (RSA) for the first 2 years regarding cup migration. Results - 2 patients were lost to follow-up: 9 patients remained in the clodronate and 9 in the control group. Less proximal migration was found in the clodronate group compared with the controls, measured both over time (mixed-models analysis, p = 0.02) as well as at the specified time points up to 2 years (0.22 mm and 0.59 mm respectively, p = 0.02). Both groups seemed to have stabilized at 1 year. We found similar bone mineral density measured by DXA, and similar RSA migration in the other directions. No cups were re-revised. Interpretation - Local treatment of the allograft bone with clodronate reduced early proximal migration of the revised cup but without any measurable difference in periacetabular bone density.

BACKGROUND: After more than 4 decades experience of total knee arthroplasty (TKA), there is still a group of patients who are not satisfied with the outcome. In spite of the improvement of many aspects around the procedure, for unexplainable reasons, patient dissatisfaction is still approximately the same. We conducted this study to analyze correlations between preoperative psychological aspects and dissatisfaction after TKA.METHODS: A total of 186 patients were operated with a primary TKA. Patients filled out the Hospital Anxiety and Depression Scale, Visual Analog Pain Scale (0-100), and Knee injury and Osteoarthritis Outcome Score preoperatively and 4 years postoperatively. Four years postoperatively, the patients also scored their satisfaction degree with the outcome of the surgery.RESULTS: Of 186 patients, 27 (15%) reported that they were dissatisfied or uncertain with the result of their TKA 4 years postoperatively. Sixteen of those 27 patients had reported anxiety/depression preoperatively compared with 11 of 159 (7%) in the satisfied or very satisfied groups. Patients with preoperative anxiety or depression had more than 6 times higher risk to be dissatisfied compared with patients with no anxiety or depression (P < .001). Patients with deep prosthetic infection had 3 times higher risk to be dissatisfied with the operation outcome (P = .03). Dissatisfied patients had 1-day longer hospital stay compared with the satisfied group (P < .001).CONCLUSION: Preoperative anxiety and/or depression is an import predictor for dissatisfaction after TKA. Psychological assessment and treatment preoperatively might improve degree of satisfaction.

Background and purpose Local infiltration analgesia (LIA) is well established for effective postoperative pain relief in total knee arthroplasty (TKA). To prolong the effect of LIA, infusion pumps with local intraarticular analgesia can be used. We evaluated the effect of such an infusion pump for the first 48 h postoperatively regarding pain, knee function, length of stay (LOS) in hospital, and complications. Patients and methods 200 patients received peroperative LIA and a continuous intraarticular elastomeric infusion pump set at 2 mL/h. The patients were randomized either to ropivacaine (7.5 mg/mL) or to NaCl (9 mg/mL) in the pump. Visual analog scale (VAS) pain (0–100 mm), analgesic consumption, side effects of medicine, range of motion (ROM), leg-raising ability, LOS, and complications during the first 3 months were recorded. Results On the first postoperative day, the ropivacaine group had lower VAS pain (33 vs. 40 at 12 noon and 36 vs. 43 at 8 p.m.; p = 0.02 and 0.03, respectively), but after that all recorded variables were similar between the groups. During the first 3 months, the ropivacaine group had a greater number of superficial and deep surgical wound infections (11 patients vs. 2 patients, p = 0.02). There were no other statistically significant differences between the groups. Interpretation Continuous intraarticular analgesia (CIAA) with ropivacaine after TKA has no relevant clinical effect on VAS pain and does not affect LOS, analgesic consumption, ROM, or leg-raising ability. There may, however, be a higher risk of wound-healing complications including deep infections.

Background and purpose — Even small design modifications of uncemented hip stems may alter the postoperative 3-D migration pattern. The Furlong Active is an uncemented femoral stem which, in terms of design, is based on its precursor—the well-proven Furlong HAC—but has undergone several design changes. The collar has been removed on the Active stem along with the lateral fin; it is shorter and has more rounded edges in the proximal part. We compared the migration patterns of the uncemented Furlong HAC stem and the modified Furlong Active stem in a randomized, controlled trial over 5 years using radiostereometry (RSA). Patients and methods — 50 patients with primary osteoarthritis were randomized to receive either the HAC stem or the Active stem. The patients underwent repeated RSA examinations (postoperatively, at 3 months, and after 1, 2, and 5 years) and conventional radiography, and they also filled out hip-specific questionnaires. Results — During the first 3 months, the collarless Active stem subsided to a greater extent than the collar-fitted HAC stem (0.99 mm vs. 0.31 mm, p = 0.05). There were, however, no other differences in movement measured by RSA or in clinical outcome between the 2 stems. After 3 months, both stem types had stabilized and almost no further migration was seen. Interpretation — The Active stem showed no signs of unfavorable migration. Our results suggest that the osseointegration is not compromised by the new design features.

We report on two patients with fracture of a modular, tapered and distally fixed, uncemented titanium revision hip stem, not previously described. A failure analysis revealed that the cause of the fractures was the development of fatigue cracks in the mid-stem cobalt-chromium modular junction ending in corrosion-fatigue failure. No material defects or stress risers were found in any of the implants. The diameter of the mid-stem modular junction might be undersized for use in heavy and active patients. We also report a new way of detecting an undisplaced fracture at the modular junction, using the scout image from a computed tomography (CT) scan; a technique that can be used when plain radiographs are inconclusive.

Patient-specific finite element models of the implanted proximal femur can be built from pre-operative computed tomography scans and post-operative X-rays. However, estimating three-dimensional positioning from two-dimensional radiographs introduces uncertainty in the implant position. Further, accurately measuring the thin cement mantle and the degree of cement-bone interdigitation from imaging data is challenging. To quantify the effect of these uncertainties in stem position and cement thickness, a sensitivity study was performed. A design-of-experiment study was implemented, simulating both gait and stair ascent. Cement mantle stresses and bone-implant interface strains were monitored. The results show that small variations in alignment affect the implant biomechanics, especially around the most proximal and most distal ends of the stem. The results suggest that implant position is more influential than cement thickness. Rotation around the medial-lateral axis is the dominant factor in the proximal zones and stem translations are the dominant factors around the distal tip.

Background The fixation of uncemented tibia components in total knee arthroplasty may rely on the bone quality of the tibia; however, no previous studies have shown convincing objective proof of this. Component migration is relevant as it has been shown to predict aseptic loosening. Methods We performed 2-year follow-up of 92 patients who underwent total knee arthroplasty surgery with an uncemented tibia component. Bone mineral density (BMD; g/cm 2 ) of the tibia host bone was measured preoperatively using dual energy X-ray absorptiometry. The proximal tibia was divided into 2 regions of interest (ROI) in the part of the tibia bone where the components were implanted. Radiostereometric analysis was performed postoperatively and after 3, 6, 12, and 24 months. The primary outcome was maximum total point motion (MTPM; mm). Regression analysis was performed to evaluate the relation between preoperative BMD and MTPM. Results We found low preoperative BMD in ROI1 to be significantly related to high MTPM at all follow-ups: after 3 months (R 2 = 20%, P BMD = 0.017), 6 months (R 2 = 29%, P BMD = 0.003), 12 months (R 2 = 33%, P BMD = 0.001), and 24 months (R 2 = 27%, P BMD = 0.001). We also found a significant relation for low BMD in ROI2 and high MTPM: 3 months (R 2 = 19%, P BMD = 0.042), 6 months (R 2 = 28%, P BMD = 0.04), 12 months (R 2 = 32%, P BMD = 0.004), and 24 months (R 2 = 24%, P BMD = 0.005). Conclusion Low preoperative BMD in the tibia is related to high MTPM. Thus, high migration of uncemented tibia components is to be expected in patients with poor bone quality.

Introduction Shorter, anatomically shaped and proximally loading stems have been developed to achieve better stress distribution and be more bone preserving. The purpose of this prospective study was to evaluate the migration pattern of the Proxima™ ultra-short uncemented stem using radiostereometric analysis (RSA), and to review the literature regarding the migration of short stemmed hip arthroplasty. Methods 25 patients (28 hips) with hip osteoarthritis received a Proxima stem during total hip arthroplasty (THA). To measure stem migration, repeated RSA examinations were done during a 2 year follow up period. The patients were evaluated with the hip specific (HOOS) and the generic health (EQ5D) scores up to 1 year, and clinically for 6 years postoperatively. Results Almost all migration occurred within the first 3 months, with mean subsidence of 0.22 mm and varus rotation of 1.04°, being the primary effect variables. After the third postoperative month and up to the 2 year RSA follow up no further significant migration occurred. The outcome scores showed substantial improvement after 1 year. No revisions were performed or indicated for any stem after a mean clinical follow up of 72.1 months. Conclusions Like many other uncemented stems, the Proxima showed early migration up to 3 months hereafter osseointegration seems to have occurred. The achieved stability and clinical outcomes indicate favorable early results for this stem in younger patients who have good bone quality and average BMI. We found, however, the surgical technique to be slightly more demanding compared to conventional stems owing to the unique implant design that necessitates specific adjusted femoral cutting and broaching procedures.

Background Regenerex is a novel porous titanium construct with a three-dimensional porous structure and biomechanical characteristics close to that of normal trabecular bone. The aim of this study was to compare this novel construct to a well-proven porous plasma sprayed tibial (PPS) implant after total knee arthroplasty. Methods Sixty-one patients scheduled for an uncemented TKA were randomized to receive either a novel highly porous titanium construct Regenerex or the PPS tibial component. Radiostereometric analysis of the tibial components was performed postoperatively and at three, six, 12, and 24months with measurements of migration (segment motion and maximum total point motion (MTPM)). Results Knee and function scores improved significantly from preoperatively to two-year follow-up. For both the Regenerex and the PPS the majority of migration appeared during the first three months and then stabilized. No statistically significant differences in MTPM were found in any follow-up between three and 24months. The Regenerex group had a lower migration rate between 12 and 24months compared with the PPS implants (p=0.03) but the PPS group had an initial significantly lower subsidence (p=0.04). Conclusion In conclusion the Regenerex implant could prove an effective scaffold material for coating of uncemented implants but did no better than the PPS component at 24months of follow-up. ClinicalTrials.gov identifier: NCT01936415.

Background and purpose The remodeling of morselized bone grafts in revision surgery can be enhanced by an anabolic substance such as a bone morphogenetic protein (BMP). On the other hand, BMPs boost catabolism and might cause a premature resorption, both of the graft and of the new-formed bone. Bisphosphonates inactivate osteoclasts and can be used to control the resorption. We studied a combination of both drugs as a local admix to a cancellous allograft. Methods Cancellous bone allografts were harvested and freeze-dried. Either saline, BMP-7, the bisphosphonate zoledronate, or a combination of BMP-7 and zoledronate were added in solution. The grafts were placed in bone conduction chambers and implanted in the proximal tibia of 34 rats. The grafts were harvested after 6 weeks and evaluated by histomorphometry. Results Bone volume/total volume (BV/TV) was 50% in the grafts treated with the combination of BMP-7 and zoledronate and 16% in the saline controls (p < 0.001). In the zoledronate group BV/TV was 56%, and in the BMP group it was 14%. The ingrowth distance of new bone into the graft was 3.5 mm for the combination of BMP-7 and zoledronate and 2.6 mm in the saline control (p = 0.002). The net amount of retained remodeled bone was more than 4 times higher when BMP-7 and zoledronate were combined than in the controls. Interpretation An anabolic drug like BMP-7 can be combined with an anti-catabolic bisphosphonate as local bone graft adjunct, and the combination increases the amount of remaining bone after remodeling is complete.

Patellofemoral problems are relatively common sequelae of total knee arthroplasty (TKA), and many factors contribute to these complications. Vascular compromise has been identified as a possible contributing factor, and was selected for further investigation in the present study. Laser Doppler Flowmetry was used to quantify patella intraosseous blood flow in vivo during TKA surgery without the use of a tourniquet. Flow was measured after medial parapatellar arthrotomy, and compared to flow during patella eversion and lateral retraction. Patella blood flow during eversion was reduced to 13% of baseline values (p

The importance of the subchondral bone plate of the acetabulum when preparing the pelvis for a cemented acetabular cup during total hip arthroplasty (THA) has been investigated using finite element analysis. The effect of retaining or removing the subchondral bone plate and the use of anchoring holes are compared. Loading was applied via both hip joint contact force and the activity of up to 22 muscles at five stages through the load bearing phase of the gait cycle. Removing the subchondral bone plate leads to decreased stresses in the cancellous bone and slightly increased stresses in the cortical shell superior to the acetabulum. The differences between the two cases are small, nevertheless there are indications that removal of the subchondral bone plate reduces the stresses. Increasing the cement penetration depth leads to a slightly more rigid structure, due to cement penetrating the cancellous bone. Adding anchoring holes moves the position of the highest cancellous bone strains from the bone-cement interface into the cancellous bone. Thus removal of the subchondral bone plate should lead to an increased potential for cement penetration into the cancellous bone which should be beneficial for cup fixation and thus improve long term implant survival.