Loosening Of Acetabular Component Research Articles

Intra- and inter-observer agreement and reliability of bone mineral density measurements around acetabular cup: a porcine ex-vivo study using single- and dual-energy computed tomography.

BackgroundPeriprosthetic bone loss is considered to be a potentially contributing factor in aseptic loosening of acetabular hip components, but no studies have shown this association. The lack of association might be caused by insufficient image quality because of metal artifacts and challenges in measuring bone density (BMD) in complex anatomic structures which might be overcome using dual-energy computed tomography (DECT).PurposeTo test inter- and intra-observer agreement and reliability of in-house segmentation software measuring BMD adjacent to acetabular cup and to compare measurements performed with single-energy CT (SECT) and DECT in cemented and cementless cups.Material and MethodsTwenty-four acetabular cups inserted in porcine hip specimens were scanned with SECT and DECT. Bone density was measured in a three-dimensional volume adjacent to the cup. Double measurements were performed.ResultsBMD derived from SECT was approximately four times higher than that of DECT. In both scan modes, intraclass correlation coefficient (ICC) was >0.90 with no differences between repeated measurements, except for uncemented cups where a statistically significant difference of 11 mg/cm3 was found with DECT. DECT showed narrower limits of agreement than SECT. Inter-observer analysis showed small differences.ConclusionBMD can be estimated with high intra- and inter-observer reliability with SECT and DECT around acetabular cups using custom software. The intra- and inter-observer agreement of DECT is superior to that of SECT and better in the cementless concept. Good intra- and inter-observer reliability can be obtained in both cemented and cementless cups using the segmentation software. SECT and DECT cannot be used interchangeably.

Interventions for Improving Hip Resurfacing Outcomes in Women: A High-Volume, Retrospective Study

BackgroundWomen seeking surgical intervention for their hip disorders will often find total hip arthroplasty (THA) presented as their only option. THA, when compared with hip resurfacing arthroplasty, removes substantially more bone-stock, limits range-of-motion, exhibits increased dislocation risk, and presents greater overall 10-year mortality rate. Despite these risks, most surgeons continue to select against women for hip resurfacing because registries notoriously report inferior survivorship when compared with men and THA. MethodsWe investigated the reasons for why resurfacing arthroplasty devices survive poorly in women to develop interventions which might improve hip resurfacing outcomes in women. Using these findings, we developed a series of surgical interventions to treat the underlying issues. Herein, we compare 2 study groups: women who received hip resurfacings before (group 1) and after (group 2) these interventions. ResultsEight-year implant survivorship substantially improved from 89.6% for group 1 to 97.7% for group 2. Adverse wear-related failure, femoral component loosening, and acetabular component loosening were all significantly reduced in group 2, which we attribute to the implementation of our relative acetabular inclination limit guidelines, use of uncemented femoral fixation, and selection of the Tri-Spike acetabular component for supplemental fixation, respectively. Kaplan-Meier implant survivorship curves, grouped into 2-year time intervals, show that the disparity in failure rates between men and women is diminishing. ConclusionWhen experienced surgeons use refined and proper surgical technique, women show promise as excellent candidates for hip resurfacing as an alternative treatment for their debilitating hip conditions.

Survivorship of Total Hip Joint Replacements Following Isolated Liner Exchange for Wear

BackgroundLiner exchange for articular component wear in total hip joint replacements (THJRs) is a common procedure, often thought to be benign with reliable outcomes. Recent studies, however, suggest high failure rates of liner exchange revisions with significant complications. The primary aim of this study was, therefore, to analyze the survivorship of isolated liner exchange for articular component wear, and secondarily to assess the influence of patient demographics (gender, age, and American Society of Anaesthesiologists [ASA] ratings) on rerevisions following isolated liner exchange for wear. MethodsA retrospective review of the 15-year New Zealand Joint Registry (1999-2014) was performed, analyzing the outcomes of isolated liner exchange for articular component wear. The survivorship as defined as rerevision with component exchange was determined and 10-year Kaplan-Meier survivorship curves were constructed. These revision rates were compared to age, gender, and ASA rating groups using a log-rank test. ResultsThe 10-year survivorship of THJR following liner exchange revision for liner wear was 75.3%. If a rerevision was required, the median time to rerevision was 1.33 years with a rerevision rate of 3.33 per 100 component years (95% confidence interval 2.68-4.08/100 component years). The principle reasons for rerevision were dislocation (48.4%) and acetabular component loosening (20.9%). There was no statistically significant difference in rerevision rates based on gender, age categories, or ASA scores. ConclusionTHJR isolated liner exchange for liner wear is not a benign procedure with a survivorship of 75.3% at 10 years. Surgeons contemplating liner exchange revisions should be cognisant of this risk and should adequately assess component position and stability preoperatively.

Radiographic scoring system for the evaluation of stability of cementless acetabular components in the presence of osteolysis.

The stability of cementless acetabular components is an important factor for surgical planning in the treatment of patients with pelvic osteolysis after total hip arthroplasty (THA). However, the methods for determining the stability of the acetabular component from pre-operative radiographs remain controversial. Our aim was to develop a scoring system to help in the assessment of the stability of the acetabular component under these circumstances. The new scoring system is based on the mechanism of failure of these components and the location of the osteolytic lesion, according to the DeLee and Charnley classification. Each zone is evaluated and scored separately. The sum of the individual scores from the three zones is reported as a total score with a maximum of 10 points. The study involved 96 revision procedures which were undertaken for wear or osteolysis in 91 patients between July 2002 and December 2012. Pre-operative anteroposterior pelvic radiographs and Judet views were reviewed. The stability of the acetabular component was confirmed intra-operatively. Intra-operatively, it was found that 64 components were well-fixed and 32 were loose. Mean total scores in the well-fixed and loose components were 2.9 (0 to 7) and 7.2 (1 to 10), respectively (p < 0.001). In hips with a low score (0 to 2), the component was only loose in one of 33 hips (3%). The incidence of loosening increased with increasing scores: in those with scores of 3 and 4, two of 19 components (10.5%) were loose; in hips with scores of 5 and 6, eight of 19 components (44.5%) were loose; in hips with scores of 7 or 8, 13 of 17 components (70.6%) were loose; and for hips with scores of 9 and 10, nine of nine components (100%) were loose. Receiver-operating-characteristic curve analysis demonstrated very good accuracy (area under the curve = 0.90, p < 0.001). The optimal cutoff point was a score of ≥ 5 with a sensitivity of 0.79, and a specificity of 0.87. There was a strong correlation between the scoring system and the probability of loosening of a cementless acetabular component. This scoring system provides a clinically useful tool for pre-operative planning, and the evaluation of the outcome of revision surgery for patients with loosening of a cementless acetabular component in the presence of osteolysis. Cite this article: Bone Joint J 2017;99-B:601-6.

The diagnostic performance of radiographic criteria to detect aseptic acetabular component loosening after revision total hip arthroplasty.

This study aimed to determine the diagnostic performance of radiographic criteria to detect aseptic acetabular loosening after revision total hip arthroplasty (THA). Secondary aims were to determine the predictive values of different thresholds of migration and to determine the predictive values of radiolucency criteria. Acetabular component migration to re-revision was measured retrospectively using Ein-Bild-Rontgen-Analyse (EBRA-Cup) and manual measurements (Sutherland method) in two groups: Group A, 52 components (48 patients) found not loose at re-revision and Group B, 42 components (36 patients) found loose at re-revision between 1980 and 2015. The presence and extent of radiolucent lines was also assessed. Using EBRA, both proximal translation and sagittal rotation were excellent diagnostic tests for detecting aseptic loosening. The area under the receiver operating characteristic (ROC) curves was 0.94 and 0.93, respectively. The thresholds of 2.5 mm proximal translation or 2° sagittal rotation (EBRA) in combination with radiolucency criteria had a sensitivity of 93% and specificity of 88% to detect aseptic loosening. The sensitivity, specificity, positive predictive value and negative predictive value (NPV) of radiolucency criteria were 41%, 100%, 100% and 68% respectively. Manual measurements of both proximal translation and sagittal rotation were very good diagnostic tests. The area under the ROC curve was 0.86 and 0.92 respectively. However, manual measurements had a decreased specificity compared with EBRA. Radiolucency criteria had a poor sensitivity and NPV of 41% and 68% respectively. This study shows that EBRA and manual migration measurements can be used as accurate diagnostic tools to detect aseptic loosening of cementless acetabular components used at revision THA. Radiolucency criteria should not be used in isolation to exclude loosening of cementless acetabular components used at revision THA given their poor sensitivity and NPV. Cite this article: Bone Joint J 2017;99-B:458-64.

Local bisphosphonate reduces migration and formation of radiolucent lines adjacent to cemented acetabular components.

Post-operative migration of cemented acetabular components as measured by radiostereometric analysis (RSA) has a strong predictive power for late, aseptic loosening. Also, radiolucent lines predict late loosening. Migration has been reduced by systemic bisphosphonate treatment in randomised trials of hip and knee arthroplasty. Used as a local treatment, a higher local dose of bisphosphonate can be achieved without systemic exposure. We wished to see if this principle could be applied usefully in total hip arthroplasty (THA). In this randomised placebo-controlled, double-blinded trial with 60 participants, we compressed gauze soaked in bisphosphonate solution (ibandronate) or saline against the acetabular bone bed immediately before cementing the acetabular component. RSA, classification of radiolucent lines, the Harris Hip Score (HHS) and the Western Ontario McMasters Universities Osteoarthritis Index (WOMAC) were carried out at three-, six-, 12-, and 24-month follow-up. Migration of the cemented acetabular component relative to the pelvis was reduced by movement almost half in the ibandronate group, when measured as maximum total point or as movement of the femoral head (p = 0.001 and 0.004, respectively). Radiolucent lines after one year were classified as absent, partial or complete, and correlated with treatment (rho 0.37; p = 0.004). Only three of 30 patients in the ibandronate group had complete lines, compared with 13 of 28 in the placebo group (p = 0.002). There were no significant effects on HHS or WOMAC score. Considering the power of RSA to predict loosening of cemented acetabular components, and the likelihood that radiolucent lines indicate risk of loosening, these data suggest that local treatment with a bisphosphonate can reduce the risk of late aseptic loosening. Cite this article: Bone Joint J 2017;99-B:317-24.

Acetabulum-Only Revision Total Hip Arthroplasty Is Associated With Good Functional Outcomes and Survivorship

BackgroundThe coexistence of a stable femoral and a loose acetabular component may pose a clinical dilemma for the surgeon. Our study aims at comparing the intermediate functional outcomes and survivorship of acetabulum-only revision total hip arthroplasty (ArTHA) with an age-matched and gender-matched total revision THA (TrTHA) group. MethodsWe retrospectively reviewed prospectively collected data on the pain, function, and total Harris Hip Scores (HHS) and complication profile for ArTHA and TrTHA cohorts from our regional arthroplasty database. Kaplan-Meier survivorship, with the need for repeat revision surgery as the end point, was used for survival analysis. ResultsAmong 538 cases, there were fewer acute medical complications in ArTHA and a similar dislocation rate for both cohorts. Preoperative HHS for pain, function, and total were better in the ArTHA cohort, but only the function score reached statistical significance. No significant differences in subsequent years for all aspects of HHS, except the function score was significantly better in the ArTHA cohort at year 1. And 10.0% of ArTHAs and 7.8% of TrTHAs had required rerevision. The 5-year survivorship was 90.3% (95% confidence interval ± 2.1%) for the ArTHA cohort and 92.7% (95% confidence interval ± 1.8%) for the TrTHA cohort (P = .394). The ArTHA with posterior approach (n = 118) group had the lowest dislocation rate and the best trend of functional outcomes. ConclusionArTHA can provide similar functional outcomes and dislocation rate to TrTHA, with an acceptable rerevision rate. The posterior approach in this study was not associated with a significant dislocation rate.

Application of jumbo cup in acetabular revisions for patients with massive acetabular bone deficiency

Objective To investigate the effects of the jumbo cup in acetabular revision for patients with massive acetabular bone deficiency. Methods We retrospectively studies 48 patients (49 hips) who underwent jumbo cup revisions between 2006 and 2015 (19 men and 29 women; average age: 62±12 years). The acetabular bone defects were classified according to Paprosky classification (Paprosky II 27 hips, Paprosky IIIA 18 hips, Paprosky IIIB 4 hips). Radiological assessments were conduced to evaluate the acetabular prosthesis loosening, dislocation and infection. The reasons for revisions were mechanical loosening in 41 cases, and infections in another 8 cases with cement spacer putted by last surgery. Results The operation duration and blood loss was 110 min (85-160 min) and 315 ml (270-455 ml) respectively. After an average follow-up of 6.8 years (1-11 years), Harris hip score was increased from 47.6 ± 7.1 preoperatively to 82.4 ± 6.2 postoperatively. Osseointegration occurred in the acetabular components at 6 months postoperatively. Radiograph analysis showed satisfied position of acetabular cup without complications such as damages of vessels or nerves. The successful rate of jumbo cup revisions was 89.8%±4.4%. However, two in Paprosky IIIA failures for periprosthetic infection occurred and two in Paprosky IIIA, one in Paprosky IIIA and the other in Paprosky IIIB for acetabular component loosening. One patient in Paprosky IIIB had weight-bearing pain and relieve slightly after conservative treatment. The radiologic study showed that there was no relationship between failure rate and acetabular abduction angle (r=0.06, P= 0.53), rotation center migration in vertical direction (r=0.11, P=0.14) and horizontal direction (r=0.04, P=0.89). Conclusion The mid-term results show that using jumbo cup in revising acetabular failure with massive bone deficiency are optimal, which can be achieved by simplified operation procedures, reduction in the need of bone graft and promotion in acetabulum osseointegration. However, higher failure rate may occur in Paprosky IIIB patients. Key words: Arthroplasty, replacement, hip; Reoperation; Acetabulum; Osteolysis; Prosthesis failure

Long-Term Results of Cementless Total Hip Arthroplasty With Subtrochanteric Shortening Osteotomy in Crowe Type IV Developmental Dysplasia

BackgroundWhen surgeons reconstruct hips with a high dislocation related to severe developmental dysplasia of the hip (DDH) in total hip arthroplasty (THA), archiving long-term stable implant fixation and improving patient function and satisfaction remain challenging. The purpose of this study was to evaluate the 10-year outcomes of transverse subtrochanteric shortening osteotomy in cementless, modular THA in Crowe type IV-Hartofilakidis type III DDH. MethodsWe reviewed 62 patients (76 hips) who underwent cementless THA with transverse subtrochanteric shortening osteotomy from 2002-2010. There were 49 women and 13 men with a mean age of 38.8 years, all of whom had Crowe type IV DDH. Mean follow-up period was 10 years. The acetabular cup was implanted in placement of the anatomical hip center in all hips. ResultsThe mean Harris Hip Score significantly improved from 38.8 points to 86.1 points. Similarly, modified Merle d'Aubigne and Postel Hip Score, Hip dysfunction and Osteoarthritis Outcome Score, and SF-12 also significantly improved. The mean limb length discrepancy was reduced from 4.3 cm to 1.0 cm. At mean follow-up of 10 years, there were 3 cases of postoperative dislocation, 2 cases of transient nerve palsy, 1 case of nonunion, and 4 cases of intraoperative fracture. Revision surgery was performed in 2 patients due to isolated loosening of acetabular component and femoral stem, respectively. ConclusionOur data demonstrated that the cementless, modular THA combined with transverse subtrochanteric shortening osteotomy was an effective and reliable technique with high rates of successful fixation of the implants and satisfactory clinical outcomes.

Early aseptic loosening of cementless monoblock acetabular components.

Early aseptic loosening of cementless monoblock acetabular components is a rare complication of total hip arthroplasty (THA) and hip resurfacing arthroplasty (HRA). The purpose of this study was to evaluate the incidence and risk factors for early aseptic loosening of the cementless monoblock acetabular components. This retrospective analysis consisted of 4,043 cementless hip devices (3,209 THAs and 834 HRAs). We identified 41 patients with early aseptic loosening of the acetabular component. A control group of 123 patients without acetabular component loosening was randomly selected. The demographic data and risk factors for loosening of the acetabular component were evaluated. The mean follow-up time was 4.6 years (range, 1.7-7.8). The end-point was acetabular revision. The incidence of early acetabular component loosening was 1.0%. Mean time to revision was 1.2 years (SD 1.6, range 0.0-5.4). There was significantly more Dorr type A and C acetabular morphology in patients with early loosening (P = 0.014). The loosened components were implanted to more vertical (P < 0.001) and less anteverted (P = 0.001) position than those of the control group. Presence of acetabular dysplasia or acetabular component type did not associate to early loosening. Acetabular morphology (Dorr type A and C) and component positioning vertically and less anteverted were more common in patients with early aseptic loosening of cementless acetabular components. Suboptimal cup position most likely reflects challenges to obtain sufficient stability during surgery. We hypothesize that errors in surgical technique are the main reason for early loosening of monoblock acetabular components.

Total hip arthroplasty in patients with ankylosing spondylitis: Midterm radiologic and functional results

IntroductionThe aim of this study was to evaluate the clinical and radiological outcomes of total hip arthroplasty (THA) in patients with Ankylosing Spondylitis (AS). Patients and methodsOne hundred five hips of 61 AS patients (mean age: 41.3 ± 10.2 years) who underwent THA between 1997 and 2012 were included into the study. Dorr's classification of proximal femoral geometry, acetabular protrusio, bone ankylosis, acetabular protrusion, Brooker classification of heterotopic ossification (HO), Gruen and Charnley classifications of implant loosening were used in radiographic assessments. Patients were called back to return for an additional long-term follow-up for functional assessment. ResultsCementless total hip arthroplasty was used in 83 hips (79%) and cemented TKA was used in 22 hips (21%). The overall rate of aseptic loosening was 7.6% at a mean follow-up of 5.4 years. Femoral loosening was statistically similar in cemented and cementless femoral components (14% vs. 8%, p = 0.089). Acetabular component loosening was statistically higher in patients with any degree of HO (p = 0.04). Regardless of the type of femoral implant (cemented or cementless), femoral component loosening was higher in Dorr's type C patients (p = 0.005). The average pre-operative HSS was 46.6 ± 16.3, and it improved to 80.7 ± 18.7 at last follow-up (p < 0.01). ConclusionRevision incidence was similar in between ankylosed and non-ankylosed hips. While complication rates are high, significant functional improvement can be achieved after THA in patients with AS.

Outcome of Revision Total Hip Arthroplasty in Management of Failed Metal-on-Metal Hip Arthroplasty

BackgroundThis is a retrospective review of the functional outcomes and complications of revision total hip arthroplasty (THA) of failed metal-on-metal (MoM) hip arthroplasty. MethodsA total of 20 revision THAs were performed in 19 patients. Of them, 2 cases were failed hip resurfacing, and 18 cases were failed (MoM) THA. The mean age at revision (THA) was 59.35 years (standard deviation [SD] 9.83). ResultsThe mean follow-up was 45 months (SD 13.98). The indications of revision were aseptic loosening of acetabular component without adverse local tissue reaction (ALTR; 10 hips), aseptic loosening of the acetabular and femoral components without ALTR (1 hip), painful hip associated with ALTR (6 hips), iliopsoas impingement associated with a large-diameter femoral head or malpositioned acetabular component (3 hips). The acetabular components were revised in 18 hips using Trabecular Metal Modular cups. The femoral components were revised in 3 hips. A constrained acetabular liner was used in 5 hips. The Harris hip score significantly improved from 48.4 (SD 12.98) to 83.25 (SD 10.08). There were 2 complications (1 foot drop and 1 superficial infection) and 1 failure (recurrent dislocation) that required revision to a constrained liner. ConclusionEarly results of revision THA of failed MoM hip arthroplasty showed improvement in pain and functional outcome. No case of failed bone ingrowth was noted with the use of Trabecular Metal Modular cups. Extensive soft tissue and abductor muscles dysfunctions were common. A constrained acetabular component with repair of the hip abductors might be beneficial.

ANATOMICAL LARGE FEMORAL HEADS: EARLY COMPLICATIONS AND MID TERM RESULTS

Purpose: mechanical complications such as malrestoration of hip anatomy still impede surgical results and patient satisfaction after THA. Anatomical femoral «mega-heads» are a novel approach which enables a surgeon to use a large diameter metal on metal implant to restore hip anatomy. Ability to place femoral head eccentrically on the femoral taper results in possible anteversion, retroversion, offset and lengthening. Our hypothesis is that use of this device will result in more accurate anatomical restoration and clinical results. Methods: 64 anatomical mega-head arthroplasties were evaluated. Preoperative planning was done in order to determine the desired position of the head, restore the anatomy and avoid leg lengthening. Patients were observed at an average of 50-months for both subjective and objective outcomes. Radiograph analysis assessed anatomical restoration. Results: 51 of the 64 hips were available for follow up. In 35 the head was placed eccentrically. In 20 the positioning was inferior, 6 — posterior, 3 — anterior, 1 — superior, and 4 inferior and posterior. Harris Hip and SF-36 scores improved significantly (P < 0.001). Mean radiographic limb and offset discrepancy were 0.1 and 0.01mm respectively. Six patients (11.7 %) underwent revision surgery; elevated metal ion levels and pseudotumor (3), acetabular component loosening (2), and unexplained hip pain (1). Conclusions: The novel anatomical femoral mega-head allows versatility in restoration of normal hip anatomy. Mid-term follow-up showed a higher than anticipated rate of complications for this cup design and reduced longevity of the implant. Novel ways need to be explored to allow such versatility in restoring hip anatomy.

Mid-Term Clinical Results of VerSys Hip System (Zimmer) Uncemented Total Hip Replacement Arthroplasty.

We studied patients who received THR using VerSys Hip System and who could be followed-up more than 3 years. Clinical records were used to retrospectively identify patient characteristics, which included age, gender, disease requiring THR, preoperative and postoperative pain score of the Japan Orthopaedic Association scoring system, range of motion in flexion and abduction, operating time, intraoperative complication, and additional operation or revision surgery. Additionally, we investigated the loosening and alignment of implants from X-ray films. Ninety-one patients and 108 hip joints were investigated. Subjects were 11 males and 97 females (mean age, 64.6 years). Mean follow-up period was 6.9 years. Reasons for requiring THR were as follows: secondary osteoarthritis, 87 joints; idiopathic osteonecrosis of the femoral head, 16 joints; rapidly destructive coxarthrosis, 4 joints; and idiopathic ossification of the labrum, 1 joint. Mean operating time was 166 minutes. A total of 11 intraoperative fractures occurred, and wiring was performed in 3 of those cases. Adverse events pertaining to the surgery were limited; however, another adverse event was that 1 case resulted in intraoperative perforation of femoral cortex, for which a revision surgery was performed. There was no dislocation. Pain score using the Japan Orthopaedic Association scoring system and range of motion tests showed statistically significant improvement following THR. At the final follow-up, although no loosening of femoral implants was observed, the loosening of acetabular component was seen in 1 case. Varus insertion of femoral implant was recognized in 40 joints. Moreover, the average inclination angle of acetabular implants was 52.2 degrees. These data suggest that patients receiving VerSys Hip System uncemented THR demonstrate favorable results pertaining pain score and range of motion. However, high rate of intraoperative fracture and malalignment of implants, which may be at a risk of dislocation and/or polyethylene wear in future, suggests that this implant technique requires improvement.

Complications following conversion of a hip hemiarthroplasty to a total hip arthroplasty.

Conversion of hip hemiarthroplasty to total hip arthroplasty (CTHA) is a complication-prone procedure with high dislocation rates and early component loosening. The purpose of this study was to evaluate the complications of CTHA performed using contemporary implants. Forty-six patients who had CTHA were retrospectively matched to a control group of 46 patients who had a first-time THA revision. The mean follow-up was 47 (range 6-149) and 23 (range 6-139) months for CTHA and control groups, respectively. Radiographs taken at the last follow-up visit were evaluated for signs of loosening or other modes of failure. Clinical outcome was evaluated with the Harris Hip Score (HHS). Complications occurred in five patients (10.9 %) in the CTHA group, and all required repeat revision. Two patients (4.3 %) were revised due to recurrent dislocation. The other re-revisions were done for acetabular or femoral component loosening and deep infection. In the control group, complications occurred in six patients (13.0 %), and three (6.5 %) were revised with a constrained liner due to recurrent dislocations. Dislocation rates and re-revision for CTHA were not significantly different than those of first-time THA revision when using contemporary revision implants.

Development of a non-invasive diagnostic technique for acetabular component loosening in total hip replacements

Current techniques for diagnosing early loosening of a total hip replacement (THR) are ineffective, especially for the acetabular component. Accordingly, new, accurate, and quantifiable methods are required. The aim of this study was to investigate the viability of vibrational analysis for accurately detecting acetabular component loosening.A simplified acetabular model was constructed using a Sawbones® foam block. By placing a thin silicone layer between the acetabular component and the Sawbones block, 2- and 4-mm soft tissue membranes were simulated representing different loosening scenarios. A constant amplitude sinusoidal excitation with a sweep range of 100–1500 Hz was used. Output vibration from the model was measured using an accelerometer and an ultrasound probe. Loosening was determined from output signal features such as the number and relative strength of observed harmonic frequencies.Both measurement methods were sufficient to measure the output vibration. Vibrational analysis reliably detected loosening corresponding to both 2 and 4 mm tissue membranes at driving frequencies between 100 and 1000 Hz (p < 0.01) using the accelerometer. In contrast, ultrasound detected 2-mm loosening at a frequency range of 850–1050 Hz (p < 0.01) and 4-mm loosening at 500–950 Hz (p < 0.01).

Aseptic loosening of cobalt chromium monoblock sockets after hip resurfacing.

Acetabular component loosening is a leading cause for revision after metal-on-metal hip resurfacing arthroplasty (MMHRA). We aimed to identify potential risk factors and determine radiographic signs associated with this mode of failure. From a series of 1375 hips treated with MMHRA, 21 (20 patients) underwent revision surgery secondary to aseptic loosening of the acetabular component and 6 patients had a radiographically loose acetabular component. A control group of 27 hips (26 patients) was selected among the patients that did not have a revision, and was matched for age, gender, component size and diagnosis. Mean time to revision in the loosening group was 103.0 months and the mean time of follow-up in the control group was 161.4 months. We found greater activity levels, range of motion scores, and cup abduction angles in the loosening group. The centre-edge (CE) angle of Wiberg was 10° lower in the loosening group compared with the control group. In addition, 11 of the hips from the study group presented a sclerotic halo superior to the cup on the last radiograph vs. none in the control group. There was no difference in the prevalence of postoperative reaming gaps or radiographic signs of neck-cup impingement between the 2 groups. Risk factors for acetabular loosening included hip dysplasia with low CE angle, and a large cup abduction angle. The patient's level of activity influences the appearance of symptoms and the time to revision. We recommend selecting patients with a sufficient CE angle and properly orienting the cup.

The midterm and long-term effects of acetabular roof ring and Burch-Schneider anti-protusio cages in acetabular revisions for patients with acetabular bone deficiency.

The purpose of this study was to investigate the mid-term and long-term effects of the acetabular roof ring (ARR) and Burch-Schneider anti-protrusio cage (BSAPC) in acetabular revision for patients with acetabular bone deficiency and acetabular component loosening. Between 1988 and 2007, ARR revisions were performed in 51 patients (25 women; average age: 46.9 years) and BSAPC in 18 patients (16 women; average age: 62.1 years). Grafts were used in all revisions. The patients were evaluated retrospectively. The bone defects were classified according to the classification of the American Academy of Orthopaedic Surgeons (AAOS). Harris Hip Score (HHS) was used for clinical evaluation. Radiolucent lines, implant sizes, osseointegration, and heterotopic ossification in the 3 regions defined by DeLee and Charnley were evaluated radiologically. The success rate of ARR revisions after an average follow-up of 8.93±4.10 years (range: 4-23 years) was 87.9%, and the cumulative survival rate at year 10 postoperatively was 91%. Average HHS score increased to 83.70±8.98 postoperatively, from 40.10±2.49 preoperatively (p<0.01). The success rate of BSAPC revisions after an average follow-up of 7.06±2.39 years (range: 4-12 years) was 83.3%, and the cumulative survival rate was 78%. Average HHS score increased from 42.55 preoperatively to 73.86 postoperatively (p<0.01). All failures of ARR revisions occurred in type 3 defects (p<0.05). In 40 of the 47 patients in which an allograft was used, osseointegration occurred. No statistically significant difference was found between the increase in HHS scores of patients who underwent femoral component revision with acetabular revision and those who did not (p=0.06). Patients who underwent more than 1 revision had statistically significantly higher failure rates in comparison to patients undergoing revision for the first time (p=0.008). The mid-term and long-term results of the use of ARR and BSAPC with allografts in bone deficient acetabular revisions are satisfactory. The implants facilitate graft osseointegration, increase the bone stock, and make future revisions easier. ARR should be preferred in type 1 and type 2 acetabular bone defects, while BSAPC should be preferred in type 3 and 4 defects.

Ceramic-on-ceramic total hip arthroplasty in patients younger than 55 years.

To review the outcomes of 65 patients younger than 55 years who underwent uncemented total hip arthroplasty (THA) using third-generation ceramic-on-ceramic prostheses. Medical records of 30 men and 35 women (80 hips) aged 18 to 55 (mean, 39) years who underwent uncemented THA using third-generation ceramic-onceramic prostheses by a single surgeon were reviewed. 61 THAs used the Reflection cup with the Synergy stem (n=49), Spectron stem (n=7), or Anthology stem (n=5), and 19 THAs used the Trident cup with the Secur-Fit stem. Outcomes were assessed based on the UCLA Activity Score and Harris Hip Score, as well as radiolucency around the implants, malposition, and subsidence on radiographs. Patients were asked about their satisfaction with current activity level (yes/no), activity limitation (no limitation, musculoskeletal limitation, psychological impediments and lack of motivation, and pain or disability of the operative hip), and change in occupational activity level (same or similar, more active, and less active or disability). The mean follow-up period was 54 (range, 24-110) months. Six patients were excluded from the analysis owing to prosthetic failure secondary to ceramic liner fracture after falling (n=2), acetabular component loosening (n=1), intolerable squeak (n=1), periprosthetic fracture (n=1), and instability (n=1). The mean UCLA Activity Score improved from 4.0 (range, 1-10) to 7.7 (range, 2-10) [p<0.001], and the mean Harris Hip Score improved from 52.8 (range, 25-69) to 91.0 (range, 38-100) [p<0.001]. No hip had evidence of subsidence, loosening, or osteolysis. 52 (80%) patients were satisfied with their activity level; 28 (43%) patients reported no activity limitation; and 57 (88%) patients kept the same or similar occupation. Ceramic-on-ceramic THA achieved acceptable clinical and radiographic outcomes.

Outcomes of polyethylene liner cementation into a fixed metal acetabular shell with minimum follow-up of 7 years.

Cementation of a polyethylene liner into the well-fixed shell is a convenient option for revision total hip arthroplasty. We retrospectively reviewed 45 patients who had liner cementation to investigate the risk factors which gave rise to major complications and reoperation. Patients were observed for a minimum of 7 years (range 7.8-14 years). Relevant risk factors (age, BMI, surgical approach, previous cup size and position, types of coated surface) were assessed with Cox regression analysis. The mean Harris Hip Score was improved from 62.5 (range 57-68) preoperatively to 87.1 (range 70-97). A total of 7 hips (15.5%) had acetabular component loosening that was treated with reoperation. Prevalence of acetabular component loosening was statistically significantly higher in hydroxyapatite-coated group (5 of 13) than in the Ti-coated group (2 of 32, p = 0.015). All recurrent dislocations occurred in patients treated with a posterior approach. Diameter of the previous metal shell of below 54 mm showed a lower 10-year survival rate than those greater than 54 mm in diameter. PE liner cementation in stable metal cup is a useful alternative option for carefully selected patients. Pre-existing HA-coated cups as well as small sized cups were indicative of poor outcomes.