Short vs Standard-Length Femoral Stems Cemented According to the "French Paradox": A Matched Paired Prospective Study Using Ein Bild Roentgen Analyze Femoral Component at Two-Year Follow-Up.

BACKGROUND: The purpose of this prospective matched paired study is to compare the in vivo migration patterns using Ein Bild Roentgen Analyze femoral component of shortened vs standard-length stems cemented line-to-line in primary total hip arthroplasty (THA) at 2-year follow-up. METHODS: We prospectively included the first 50 consecutive primary cemented THAs in 50 patients using a 12% shortened stem (AmisK group) of which design was derived from the original Charnley-Kerboull (CK) femoral components. These 50 patients were matched paired to 50 patients from a historical series of patients who underwent primary THAs using standard-length CK stems (CK group) with available long-term results, including Ein Bild Roentgen Analyze femoral component data at 2-year follow-up. RESULTS: Body mass index was significantly higher (P = .007) in the AmisK vs the CK group. At the 2-year follow-up, the mean subsidence was 0.65 mm (0-1.40) in the AmisK group vs 0.68 mm (0.07-1.43) in the CK group (P = .73). When using a 1.5-mm threshold, none of the stems in either group was considered to have subsided. Femoral cortical thickening in zones 3 and 5 occurred in 6 of the 50 hips (12%) in the AmisK group vs 20 (40%) of the 50 hips in the CK group (P = .003). CONCLUSION: Our study showed that a shortened highly polished double-tapered stem cemented line-to-line provided similar results including minimal subsidence as its standard-length counterpart, with significantly less distal femoral cortical thickening. However, longer term survival analysis still needs to be determined.

Dual mobility constructs in revision total hip arthroplasty: survivorship analysis in recurrent dislocation versus other indications at three to twelve-year follow-up.

BACKGROUND: The aim of this retrospective study was to evaluate the clinical, radiologic, and survival results of dual mobility (DM) sockets in revision total hip arthroplasty (THA) performed for instability versus revision THAs performed for other reasons. METHODS: From a computerized database, we identified 84 revision THAs using a modern DM socket performed in 81 patients with a mean age of 71 years. Indication for revision was recurrent dislocation in 47 hips, and other reasons in the remaining 37 hips. A survivorship analysis according to the actuarial method was carried out on the entire series using revision for any cause, revision for dislocation, and radiological cup loosening revised or not, as the end points. RESULTS: Of the 81 patients, twelve died, six were lost to follow-up, eight had been revised, and 55 patients (58 hips) were unrevised and alive at a mean follow-up of 6.4 years. Dislocation occurred in four of the 47 (8.5%) hips for which indication for revision was dislocation versus one of the remaining 37 (2.7%) hips [odds ratio = 3.4 (0.4-31.3), p = 0.07]. According to our criteria, three acetabular components of which one was revised were considered as loosened. When using revision for dislocation as the end-point, the survival rate at seven years was 90.4 ± 5.3% (IC95%, 79.9-100) in the 47 hips for which the indication for revision was dislocation versus 100% in the remaining 37 hips (log-rank, p = 0.5). CONCLUSIONS: The current study indicated that DM sockets represent an interesting solution to prevent dislocation in revision THAs at mid-term follow-up.

Were protective procedures against SARS-CoV-2 effective in an orthopaedic and trauma centre during the lockdown period? A retrospective study.

PURPOSE: The SARS-CoV-2 epidemic started in December 2019 in Wuhan. The lockdown was declared on March 16, 2020 in France. Our centre had to adapt daily practices to continue to take care of bone and soft tissue tumours and emergencies. Through this study, we wanted to assess the various procedures implemented during the lockdown period between March 17 and May 10. METHODS: A monocentric retrospective cohort study was conducted in Cochin Hospital (Paris, France). Patients included were those who had surgery during the lockdown period. To take care of COVID-19 positive and negative patients, various procedures have been set up: reverse transcriptase polymerase chain reaction (RT-PCR) tests for all hospitalized patients, a specific unit for COVID-positive patients, a specific surgical room, and use of protective personal equipment. To allow the effectiveness of the procedures implemented, we evaluated the number of complications attributed to SARS-CoV-2 and the number of patients who became COVID positive during hospitalization. RESULTS: During the lockdown period, there were 199 procedures of three types of procedures in our centre: 79 traumatology procedures (39.7%), 76 of bone and soft tissues tumours (38.2%), and 44 procedures related to infection (22.1%). We observed 13 complications (6.5%) during hospitalization, and only one patient became COVID-19 positive during the hospitalization. CONCLUSION: The COVID-19 epidemic has been a challenge for organization and adaptation to manage all COVID-19 positive and COVID negative. Through this study, we wanted to assess our procedures taken. They had been effective due to the low number of contamination and complications.

Acetabular reinforcement rings associated with allograft for severe acetabular defects.

Acetabular revisions with severe bone defects can be challenging procedures. Several grading systems have been set into place to help the surgeon adequately gauge the degree of bone loss within the acetabulum. Internationally innovative research in orthopedics and bio-engineering has helped with progression of successful techniques and rings to re-establish the normal anatomy of the hip. The purpose of this review is to evaluate the outcomes of the different acetabular reinforcement rings in the setting of severe acetabular defects. A successive report of relevant data from the literature of multiple techniques will be provided. The procedures include the cup-cage, the Müller ring, the Ganz Ring, the Kerboull acetabular reinforcement device (KARD), the graft augmentation prosthesis (GAP) ring, and the Burch-Schneider ring. The main focus of this overview is rings only; other devices such as trabecular augments, custom-made cages, or oblong cups are not discussed. Furthermore, a special emphasis on the surgical technique of the KARD is also given. Procedures using these rings are usually associated with bone grafts either bulk or morselized. When considering the available data on these various rings used for reconstruction of the severely damaged acetabulum, the cup-cage, the KARD, and the Burch-Schneider ring appear to be reliable options for more successful long-term outcomes.

Can a Single-Use and Patient-Specific Instrumentation Be Reliably Used in Primary Total Knee Arthroplasty? A Multicenter Controlled Study.

BACKGROUND: The aim of this controlled multicenter study is to evaluate the clinical and radiologic outcomes of primary total knee arthroplasty (TKA) using single-use fully disposable and patient-specific cutting guides (SU) and compare the results to those obtained with traditional patient-specific cutting guides (PSI) vs conventional instrumentation (CI). METHODS: Seventy consecutive patients had their TKA performed using SU. They were compared to 140 historical patients requiring TKA that were randomized to have the procedure performed using PSI vs CI. The primary measure outcome was mechanical axis as measured on a standing long-leg radiograph using the hip-knee-ankle angle. Secondary outcome measures were Knee Society and Oxford knee scores, operative time, need for postoperative transfusion, and length of hospital stay. RESULTS: The mean hip-knee-ankle value was 179.8° (standard deviation [SD] 3.1°), 179.2° (SD 2.9°), and 178.3° (SD 2.5°) in the CI, PSI and SU groups, respectively (P = .0082). Outliers were identified in 16 of 65 (24.6%), 15 of 67 (22.4%), and 14 of 70 (20.0%) knees in the CI, PSI, and SU group, respectively (P = .81). There was no significant difference in the clinical results (P = .29 and .19, respectively). Operative time, number of unit transfusion, and length of hospital stay were not significantly different between the 3 groups (P = .45, .31, and 0.98, respectively). CONCLUSION: The use of an SU in TKA provided similar clinical and radiologic results to those obtained with traditional PSI and CI. The potential economic advantages of single-use instrumentation in primary TKA require further investigation.

Using Bayesian statistics to estimate the likelihood a new trial will demonstrate the efficacy of a new treatment.

BACKGROUND: The common frequentist approach is limited in providing investigators with appropriate measures for conducting a new trial. To answer such important questions and one has to look at Bayesian statistics. METHODS: As a worked example, we conducted a Bayesian cumulative meta-analysis to summarize the benefit of patient-specific instrumentation on the alignment of total knee replacement from previously published evidence. Data were sourced from Medline, Embase, and Cochrane databases. All randomised controlled comparisons of the effect of patient-specific instrumentation on the coronal alignment of total knee replacement were included. The main outcome was the risk difference measured by the proportion of failures in the control group minus the proportion of failures in the experimental group. Through Bayesian statistics, we estimated cumulatively over publication time of the trial results: the posterior probabilities that the risk difference was more than 5 and 10%; the posterior probabilities that given the results of all previous published trials an additional fictive trial would achieve a risk difference of at least 5%; and the predictive probabilities that observed failure rate differ from 5% across arms. RESULTS: Thirteen trials were identified including 1092 patients, 554 in the experimental group and 538 in the control group. The cumulative mean risk difference was 0.5% (95% CrI: -5.7%; +4.5%). The posterior probabilities that the risk difference be superior to 5 and 10% was less than 5% after trial #4 and trial #2 respectively. The predictive probability that the difference in failure rates was at least 5% dropped from 45% after the first trial down to 11% after the 13th. Last, only unrealistic trial design parameters could change the overall evidence accumulated to date. CONCLUSIONS: Bayesian probabilities are readily understandable when discussing the relevance of performing a new trial. It provides investigators the current probability that an experimental treatment be superior to a reference treatment. In case a trial is designed, it also provides the predictive probability that this new trial will reach the targeted risk difference in failure rates. TRIAL REGISTRATION: CRD42015024176 .

Differences in limb alignment and femoral mechanical-anatomical angles using two dimension versus three dimension radiographic imaging.

PURPOSE: The purpose of this study was to compare the femoral mechanical-anatomical (FMA) and mechanical femoro-tibial (MFT) angles in an osteoarthritic population using the 2D (two dimension) and the 3D (three dimension) EOS low-dose biplanar radiographic system (EOS). METHODS: FMA and MFT angles were calculated in 127 adults with osteoarthritis. In 2D, FMA angle was measured between the femoral mechanical axis and the femoral anatomical axis, and MFT angle between the femoral mechanical axis and the tibial mechanical axis. In 3D, the measurement of FMA angle consisted of identifying specific anatomical landmarks on X-rays. MFT angle was then measured between the femoral mechanical axis and the tibial mechanical axis. The distribution of 2D and 3D values was assessed in terms of means and variances. RESULTS: Mean age was 69 ± 12 years. A total of 10% of the patients having a 3D FMA angle between 4° and 7° have a 2D-measured FMA over or underestimated. Particularly, FMA values tend to be underestimated in women in 2D. Finally, we found that men showed a tendency to a more varus morphology, with MFT values being significantly underestimated in 2D. CONCLUSIONS: The EOS 3D reconstruction system is a reliable method to measure FMA and MFT angles in an osteoarthritic population.

Causes for revision of dual-mobility and standard primary total hip arthroplasty : Matched case-control study based on a prospective multicenter study of two thousand and forty four implants.

INTRODUCTION: The causes for revision of primary total hip arthroplasty (THA) are various and quite well known. The developing use of dual-mobility THA (DM-THA) seems a relevant option to decrease the risk of instability. Due to lack of long-term follow-up, this innovative retentive concept is suspected to increase the risk of polyethylene (PE) wear. the aim of the study was to analyse the causes for DM-THA revision and assess whether or not its occurrence is different from that of fixed-standard (FS) THA , particularly for aseptic loosening or wear and/or osteolysis. MATERIALS AND METHODS: The SoFCOT group conducted an observational prospective multicentre study from 1 January 2010 to 31 December 2011. Inclusion criteria comprised an exhaustive collection of 2044 first-revision THAs with 251 DM-THAs and 1793 FS-THAs. After excluding complications linked to patient factors (infection and periprosthetic fractures), we performed a matched case-control study (matching ratio 1:1) comparing two groups of 133 THAs. RESULTS: Revisions for aseptic loosening or osteolysis/wear were as frequent in DM-THA (58.7 %) as in FS-THA (57.1 %) (p 0.32); 7.5 % of DM-THA were revised for dislocation versus 19.5 % of FS-THA (p 0.007). DISCUSSION: Revision for osteolysis/wear and aseptic loosening were as frequent in DM-THA as in FS-THA; revision for dislocation was less frequent in DM-THA. This confirms the efficiency of the DM concept regarding the risk of dislocation. Causes for revision were different between groups, and revisions for dislocation were less frequent in DM-THA. Only prospective comparative studies could provide reliable information that may support broader use of the DM concept.

Does vitamin E-blended polyethylene reduce wear in primary total hip arthroplasty: a blinded randomised clinical trial.

PURPOSE: Some data indicate that first-generation highly cross-linked polyethylene (HXLPE) can oxidise in vivo and is associated with reduced mechanical properties. To overcome these limitations, a natural anti-oxidant vitamin E has been added to HXLPE to preserve the mechanical properties and decrease oxidative degradation whilst conserving high wear resistance. We hypothesised that after a minimal three years of follow-up the use of vitamin E-blended HXLPE would result in lower radiographic wear when compared with ultra-high molecular weight polyethylene (UHMWPE). METHODS: One hundred patients were randomised to receive hybrid total hip arthroplasty (THA) using a monoblock cementless acetabular component made either of UHMWPE or vitamin E-blended HXLPE. All other parameters were identical in both groups. Complete follow-up was available for 74 of these patients. Femoral head penetration was measured using a validated computer-assisted method. RESULTS: The median creep measured 0.111 mm (range, -0.576 - +0.444 mm) in the vitamin E-blended group versus 0.170 mm (range, -0.861 - +0.884 mm) in the UHMWPE group (difference of medians, 0.059; p = 0.046). The median steady state penetration rate was -0.008 mm/year (range, -0.88 - +0.64 mm/year) in the vitamin E-blended group versus 0.133 mm/year (range, -0.84 - +0.85 mm/year) in the UHMWPE group (difference of medians 0.141, p = 0.043). CONCLUSIONS: This study demonstrated that femoral head penetration was lower when using vitamin E-blended HXLPE when compared with UHMWPE, with a steady-state penetration rate far below the osteolysis threshold. Longer-term follow-up is needed to warrant whether wear reduction will generate less occurrence of osteolysis and aseptic loosening.

Five to thirteen year results of a cemented dual mobility socket to treat recurrent dislocation.

PURPOSE: Dual mobility (DM) socket has been associated with a low rate of dislocation following both primary and revision total hip arthroplasty (THA). However, little is known about the long-term efficiency of DM in the treatment of THA instability. The purpose of this retrospective study was to evaluate the outcome of a cemented DM socket to treat recurrent dislocation after a minimum of five year follow-up. METHODS: The series included 51 patients with a mean age of 71.3 ± 11.5 (range, 41-98) years presenting with recurrent dislocation (mean 3.3). A single DM socket design was used consisting of a stainless steel outer shell with grooves with a highly polished inner surface articulating with a mobile polyethylene component. The femoral head was captured in the polyethylene component using a snap-fit type mechanism, the latter acting as a large unconstrained head inside the metal cup. RESULTS: At the minimum five year follow-up evaluation, 18 of the 51 patients deceased at a mean of 4.8 ± 2.3 years, three were lost to follow-up at a mean of 1.4 years, seven had been revised at a mean of 4.7 ± 3.1 years (range, 1.5-9.1), and the remaining 23 were still alive and did not have revision at a mean of 8.2 ± 2.4 years (range, 5-13 years). Of the seven revision, three were performed for further episodes of dislocation (at the large bearing for one patient and intra-prosthetic for two patients) after a mean 5.9 ± 2.9 years (range, 2.7-9.1), whereas two were performed for late sepsis and two for aseptic loosening of the acetabular component. Radiographic analysis did not reveal any further loosening on the acetabular side. The survival rate of the cup at ten years, using re-dislocation as the end-point, was 86.1 ± 8.4% (95% confidence interval, 69.7-100%). The survival rate of the cup at ten years, using revision for any reason as the end-point, was 75.2 ± 9.3% (95% confidence interval, 56.9-93.5%). CONCLUSION: A cemented dual mobility cup was able to restore hip stability in 94% of patients presenting with recurrent dislocating hips up to 13-year follow-up with none of the complications associated with constrained devices, as mechanical failure occurred in only 3.9% of the patients of this series. The overall reduced survival using revision for any reason as the end-point at ten years was related to this specific patients population that had various co-morbidities.

Do the Reasons for Ceramic-on-ceramic Revisions Differ From Other Bearings in Total Hip Arthroplasty?

BACKGROUND: Despite widespread use of ceramic-on-ceramic (CoC) in total hip arthroplasty (THA) during the past 10 years, little is known about why revisions are performed in hips with this bearing or the time elapsed before revision. QUESTIONS/PURPOSES: The purposes of this study were: (1) Do the reasons for first revision differ between CoC bearings and other bearing couples? (2) Does the time to revision differ between CoC and other bearing couples? (3) Are there unique reasons for revisions of CoC bearings? METHODS: All members of the Société Française de Chirurgie Orthopédique et Traumatologique (SoFCOT) who performed ≥ 30 revisions per year were invited to participate in this multicenter, prospective, observational study. Our data represent 12% of the revision procedures performed in France. A total of 2107 first revisions of THA (from January 2010 to December 2011) were done in 2107 patients (1201 females [57%] and 906 males [43%]; median age, 73 years; age range, 17-104 years) at the time of surgery after a median of 11 years (range, 0 day-42 years) after the primary THA. There were 238 of 2107 (11%) CoC, 148 of 2107 (7%) metal-on-metal (MoM), and 1721 of 2017 (82%) metal-on-polyethylene (MoP) bearings. RESULTS: The reasons for reoperation differed according to the bearing component: (1) for the MoP reference bearing (odds ratio [OR]; 95% confidence interval), cup loosening occurred in 698 of 1721 hips (41%), periprosthetic fracture in 220 of 1721 hips (13%), and osteolysis in 213 of 1721 hips (12%); (2) for CoC, cup loosening occurred in 41 of 238 hips (17%) (OR, 0.31 [0.22-0.43; p < 0.001), infection in 39 of 238 hips (16%) (OR, 1.63 [1.12-2.37]; p = 0.01), and dislocation in 23 of 238 hips (10%) (OR, 0.9 [0.57-1.42]; p = 0.9); (3) for MoM, cup loosening occurred in 28 of 148 hips (19%) (OR, 0.34 [0.22-0.52]; p < 0.001), adverse reaction to metallic debris in 26 of 148 hips (18%) (OR, 18.12 [9.84-33.4]; p < 0.001), and infection in 16 of 148 hips (11%) (OR, 1 [0.59-1.73]; p = 0.9). In comparison with MoP, osteolysis was rarely the reason for revision in CoC (four of 238 hips [2%]; OR, 0.12 [0.05-0.33]; p < 0.001), but this bearing was frequently revised because of iliopsoas irritation (18 of 238 hips [8%]; OR, 4.9 [2.7-9]; p < 0.001). The time elapsed before revision differed between bearings: median of 3 years (range, 3 days to 28 years) for CoC and 4 years (range, 14 days to 37 years) for MoM versus a median 13 years (range, 0 day to 42 years) for MoP (p < 0.001). Thirty-seven of the 238 revisions (16%) were directly related to ceramic use (ceramic breakage [n = 23], squeaking [n = 6], impingement [n = 7], incorrect ceramic insert insertion [n = 1]). No factors were identified that contributed to breakage of the 12 bulk ceramic components (eight heads, four inserts, four of 12 Delta ceramic). No factors were associated with squeaking, iliopsoas irritation, or impingement, but component orientation was not assessed. CONCLUSIONS: The reasons and time to first revision differed between CoC and other bearings. CoC THAs are revised earlier and are sensitive to mechanical problems such as impingement, squeaking, and ceramic rupture that did not disappear with introduction of Delta ceramics and large-diameter (≥ 36 mm) bearings. CoC was rarely revised for osteolysis, but a high rate of iliopsoas irritation requires further investigation. LEVEL OF EVIDENCE: Level III, therapeutic study.

Validity and Reliability of Intraoperative Radiographs to Assess Leg Length During Total Hip Arthroplasty: Correlation and Reproducibility of Anatomic Distances.

BACKGROUND: Leg length discrepancy after total hip arthroplasty is a frequent complication. The aim of this study was to assess the validity (correlation) and reproducibility (inter-rater agreement) of various intraoperative hip radiographs measures to estimate leg length. METHODS: Patients were included if they were aged 15 years or older; were eligible for a total hip arthroplasty, and were operated in lateral recumbent. An intraoperative hip radiograph was performed with the definitive implants in place. At 6 weeks postoperatively, anteroposterior pelvis radiograph was taken. We used 3 measures to assess leg length: the height from the ischial tuberosity to the lesser trochanter (LTI), the height from the center of femoral head to the greater trochanter (GTC), and to the inferior teardrop (TC). RESULTS: The study group consisted of 71 hips with an average age of 69 years (range, 24-92 years). The correlation was 0.545 (95% CI: 0.35-0.69) for GTC, 0.75 (95% CI: 0.61-0.84) for TC, and 0.70 (95% CI: 0.56-0.80) for LTI. Intraoperative and postoperative measures were statistically different for GTC (<0.0001) and TC (<0.0001), and not significant for LTI (P = .06). Reproducibility of these measures were excellent with intraclass correlation coefficients of 0.977, 0.814, and 0.983 for the GTC, TC, and LTI, respectively. CONCLUSION: None of the parameters used to assess leg-length based on an intraoperative radiograph showed good correlation with the postoperative radiograph.

Intra-prosthetic dislocation of dual-mobility cups after total hip arthroplasty: potential causes from a clinical and biomechanical perspective.

INTRODUCTION: Recurrent dislocation of total hip arthroplasty is a frequent indication for revision surgery. Hip joint stability depends on implant design, cup position and crucially on femoral head diameter. Due to an effective ultra-large diameter femoral head, dual-mobility cups are considered an attractive solution to prevent dislocation in unstable conditions. Although patients obviously benefit for many years in terms of mobility and pain, an increase of intra-prosthetic dislocation reports using dual-mobility cups has been recently observed. However, the failure mechanism of this implant-specific complication, which is characterized by the loss of the positive-locking between the femoral head and the mobile liner, is not yet completely understood. METHODS: A comprehensive search was performed with the PubMed database and a search engine to overview this topic and to identify potential causes for this implant-specific failure from a clinical and biomechanical perspective. RESULTS: Peri-operative findings indicate extensive fibrosis at the large articulation as well as cup loosening as potential causes. In addition, current research has shown that the failure mechanism is affected by the surface topography of the femoral neck and in particular by the design of the mobile liner. DISCUSSION: In clinical practice it is necessary to differentiate a classic dislocation between the mobile liner and the metallic shell from an intra-prosthetic dislocation between the femoral head and the liner. CONCLUSION: Due to the increasing popularity of dual-mobility cups in total hip arthroplasty, the understanding of which implant-specific features or tissue response may increase the risk of intra-prosthetic dislocation is of major importance for reduced revision rates by using optimized surgical techniques and implant designs.

Do oxidized zirconium femoral heads reduce polyethylene wear in cemented THAs? A blinded randomized clinical trial.

BACKGROUND: Charnley low-friction torque total hip arthroplasty (THA) remains the gold standard in THA. The main cause for failure is wear of the socket. Highly crosslinked polyethylene (HXLPE) has been associated with reduced wear rates. Also, oxidized zirconium has shown in vitro reduced wear rates. However, to our knowledge, there are no data comparing oxidized zirconium femoral heads with metal heads against HXLPE or ultrahigh-molecular-weight polyethylene (UHMWPE) when 22.25-mm bearings were used, which was the same size that performed so well in Charnley-type THAs. QUESTIONS/PURPOSES: We hypothesized that after a minimal 4-year followup (1) use of HXLPE would result in lower radiographic wear than UHMWPE when articulating with a stainless steel head or with an oxidized zirconium head; (2) use of oxidized zirconium would result in lower radiographic wear than stainless steel when articulating with UHMWPE and HXLPE; and (3) there would be no difference in terms of Merle d'Aubigné scores between the bearing couple combinations. METHODS: One hundred patients were randomized to receive cemented THA with either oxidized zirconium or a stainless steel femoral head. UHMWPE was used in the first 50 patients, whereas HXLPE was used in the next 50 patients. There were 25 patients in each of the four bearing couple combinations. All other parameters were identical in both groups. Complete followup was available in 86 of these patients. Femoral head penetration was measured using a validated computer-assisted method dedicated to all-polyethylene sockets. Clinical results were compared between the groups using the Merle d'Aubigné score. RESULTS: In the UHMWPE series, the median steady-state penetration rate from 1 year onward was 0.03 mm/year (range, 0.003-0.25 mm/year) in the oxidized zirconium group versus 0.11 mm/year (range, 0.03-0.29 mm/year) in the metal group (difference of medians 0.08, p < 0.001). In the HXLPE series, the median steady-state penetration rate from 1 year onward was 0.02 mm/year (range, -0.32 to 0.07 mm/year) in the oxidized zirconium group versus 0.05 mm/year (range, -0.39 to 0.11 mm/year) in the metal group (difference of medians 0.03, p < 0.001). The Merle d'Aubigné scores were no different between the groups with a median of 18 in each of the groups (range, 16-18). CONCLUSIONS: This study demonstrated femoral head penetration was reduced by oxidized zirconium when compared with metal on both UHMWPE and HXLPE. However, apart the metal-UHMWE group, all other groups had a steady-state penetration rate well below the osteolysis threshold with a low difference between groups that might not be clinically important at this point. Longer-term followup is needed to warrant whether wear reduction will generate less occurrence of osteolysis and aseptic loosening. LEVEL OF EVIDENCE: Level II, therapeutic study.

Minimum five-year wear rate of metal-on-highly cross-linked polyethylene in primary total hip arthroplasty.

PURPOSE: Highly cross-linked polyethylenes (PE) have been developed with encouraging results in terms of wear. Another body of the literature has indicated potential catastrophic failures related to reduced fatigue properties and oxidation. Each PE available on the market has its own processing characteristics. The aim of this retrospective study was to evaluate the minimum five-year wear properties of an original highly cross-linked PE in a consecutive series of primary THAs. METHODS: Between August 2005 and December 2007, 80 patients with a mean age of 62.7 years were included. All patients had a 28-mm CoCr femoral head articulating with a highly cross-linked insert (Highcross®, Medacta SA) that was 100 Mrads gamma radiated, remelted at 150 °C, and ethylene oxide sterilized. The primary criterion for evaluation was the femoral head penetration, as measured by Hip Analysis Suite software. The steady state wear was also calculated. Functional results were evaluated according to the WOMAC score. RESULTS: Complete data were available for analysis in 67 patients at a mean follow-up of 5.5 years. The mean femoral head penetration was 0.128 ± 0.62 mm and the steady state wear was-0.025 ± 0.22 mm/year. The WOMAC score significantly decreased from 16.5 ± 5.93 pre-operatively to 4.12 ± 5.5 at the latest follow-up (p <0.001). CONCLUSIONS: The minimal five-year results of this retrospective study indicate that this particular highly cross-linked and remelted polyethylene had a low wear rate. Longer-term results are needed to warrant that these mid-term data will generate less osteolysis and resultant aseptic loosening.

Randomized controlled trial of conventional versus modern surgical dressings following primary total hip and knee replacement.

PURPOSE: We prospectively compared two types of dressing (conventional gauze-based versus absorbing hydrofibre) after primary total hip (THA) or knee (TKA) arthroplasties. METHODS: Eighty candidates for THA (n = 40) or TKA (s = 40) were randomized: gauze-based versus hydrofibre absorbing (Aquacel®, ConvaTec). The two groups were comparable at baseline. RESULTS: There was a statistically significant decrease of dressing changes in the hydrofibre group (p = 0.0006). Two patients from the conventional group presented minor wound complications. Nurses' satisfaction was significantly higher in the hydrofibre group considering the adherence (p = 0.04) and flexibility (p = 0.03). Patients experienced a higher satisfaction with respect to ease of movement (p = 0.01) in the hydrofibre group. The cosmetic appearance of the scars six weeks after surgery was found to be similar between groups. CONCLUSIONS: Our findings support an overall improved comfort for the patients and the medical staff by using hydrofibre dressings after primary THA and TKA. The reduction of required dressing changes was observed also.

Length of clinically proven cemented hip stems: state of the art or subject to improvement?

PURPOSE: The purpose of this study was to identify the shortest possible length of an established cemented hip stem in order to reduce stress shielding and optimise its bending behaviour. METHODS: Twenty-five prototypes from the same batch (five for each stem length) were included. Lengths resulted from the original length (100 %) and four distal shortenings to 94, 88, 83 and 78 % of original length. For standardised implantations, synthetic femurs were prepared. Relative movements under axial torque and stem bending under varus-valgus torque applications were investigated consecutively. Analyses of variance (ANOVA) were applied to detect differences between lengths. RESULTS: The maximum torque transfer occurred at the level of the lesser trochanter (p < 0.01). In particular, for the 78 % version, relative motion of the stem tip increased significantly compared with all other lengths (p = 0.02-0.04). Comparable findings were made for mean overall movements. In regards to varus-valgus torque, both the distal tip and the proximal shoulder always bent in the same direction following the femoral deflection. For the 83 % version bending of stem's shoulder was increased compared with the other length (p = 0.01 - 0.02), whereas tip bending was always comparable (p = 0.45-0.91). CONCLUSIONS: Our data show that the intention to preclinically optimise the mechanical behaviour of cemented stems by modifying their length seems to be a reasonable option. Advantages are decreased inner bone stiffening to reduce stress shielding and a lower cement volume, which is involved in cellular interactions.

Determinants of satisfaction 1 year after total hip arthroplasty: the role of expectations fulfilment.

BACKGROUND: Between 7% and 15% of patients are dissatisfied after total hip arthroplasty (THA). To assess predictors and postoperative determinants of satisfaction and expectation fulfilment one year after (THA). METHODS: Before THA surgery, 132 patients from three tertiary care centres and their surgeons were interviewed to assess their expectations using the Hospital for Special Surgery Total Hip Replacement Expectations Survey (THR survey). One year after surgery, patients (n = 123) were contacted by phone to complete a questionnaire on expectation fulfilment (THR survey), satisfaction, functional outcome (Womac), and health-related quality of life (SF 12). Univariate and multivariate analyses were performed. RESULTS: Preoperative predictors of satisfaction were a good mental wellbeing (adjusted OR 1.09 [1.02; 1.16], p = 0.01) and optimistic surgeons expectations (1.07 [1.01; 1.14], p = 0.02). The main postoperative determinant of satisfaction was the fulfilment of patient's expectations (1.08 [1.04; 1.12], p < 0.001). Expectation fulfilment could be predicted before surgery by young age (regression coefficient -0.55 [-0.88; -0.21], p = 0.002), good physical function (-0.96 [-1.82; -0.10], p = 0.03) and good mental wellbeing (0.56 [0.14; 0.99], p = 0.01). Postoperative determinants of expectation fulfilment were functional outcome (-2.10 [-2.79; -1.42], p <0.001) and pain relief (-14.83 [-22.38; -7.29], p < 0.001). CONCLUSION: To improve patient satisfaction after THA, patients' expectations and their fulfilment need to be carefully addressed. Patients with low mental wellbeing or physical function should be identified and specifically informed on expected surgical outcome. Surgeons' expectations are predictive of satisfaction and information should aim to lower discrepancy between surgeons' and patients' expectations.

Intraprosthetic dislocation: a potentially serious complication of dual mobility acetabular cups.

Though dual mobility cups have gained growing popularity as a solution for instability in total hip replacements, these promising devices are subject to a specific implant failure mode, named intraprosthetic dislocation. We present the case of a patient sustaining such an adverse event. The planned revision surgery was postponed 12 months due to a severe heart condition, allowing a rare opportunity to document the natural history of this unusual complication. The small femoral head was found dislodged in the superior part of the metallic shell and had remarkably lost its sphericity. Severe metallic debris and granuloma were found in the proximal femoral region, associated with major periprosthetic bony and soft tissue damage. Surgeons, radiologists, and general practitioners should be aware of this specific complication, its incidence (almost 5%) and mechanisms (femoral neck to mobile polyethylene insert impingement, leading to rim fatigue and wear of the insert at the capturing area). Diagnosis is mainly based on anteroposterior and modified Lowenstein lateral radiographs of the hip, as an eccentric position of the small femoral head, lying against the concave inner surface of the shell. Prompt component revision should be planned, since delayed management could lead to severe irretrievable damages.

Evaluation of a method for the assessment of anterior acetabular coverage and hip joint space width.

OBJECTIVE: The false-profile view (FP) is an oblique view of the acetabulum and a true lateral view of femur and joint. It evaluates anterior and posterior hip joint space width (JSW) and anterior acetabular coverage using the vertical-center margin angle (VCA). The biplanar slot scanner (SS) allows simultaneous bilateral acquisitions of oblique views of hip joints. The aim of this work was to compare SS versus FP for the evaluation of VCA and JSW and to test its reproducibility and validity. MATERIALS AND METHODS: A prospective study of 28 patients (55 hips) with hip pain was performed from November 2011 until May 2012. Two readers measured VCA and JSW. JSW was normalized by the diameter of the femoral head for each technique. The radiation exposure was recorded and compared between the two modalities. Student's t test and the Pearson's correlation assessed the agreement between SS and FP. The intraclass correlation coefficient (ICC) was used to assess the interobserver agreement. RESULTS: The mean VCA angle was 32.1° (± 7.1°) and 30.3° (± 8.5°) with FP and SS, respectively. The coefficient of correlation was 0.90 (p < 0.01). The coefficient of correlation of normalized JSW was 0.83, 0.85, and 0.87 at anterior, vertical, and posterior points, respectively). The ICC was between 0.69 and 0.81 for each modality. The mean radiation exposure was 1.33 (± 0.02) mGy versus 8.69 (±0.04) mGy for FP and SS, respectively (p < 0.0001). CONCLUSIONS: SS has the potential advantages of simultaneous bilateral acquisition, higher standardization, and is less irradiating. SS is reliable for coxometry.