Failed Total Hip Arthroplasty Research Articles

Clinical study of occult fractures around the prosthesis in primary total hip arthroplasty

ABSTRACT Objective To determine the prevalence, prevention measures, and risk factors for occult periprosthetic fractures after primary total hip arthroplasty (THA), as well as to determine whether or not they are the root of early THA failure. Methods From January 2014 to December 2018, 755 patients (769 hips) underwent primary total hip arthroplasty were retrospectively analyzed, including 327 males (339 hips) and 428 females (430 hips). X-ray, CT and 3D reconstruction of hip were performed before and after operation. By using CT to diagnose the occult fractures, the patients were then monitored and evaluated. Age, sex, body mass index (BMI), preoperative diagnosis, osteoporosis, kind of prosthesis, and the surgeon’s experience should all be considered. Patients with occult fracture were followed up, the fracture healing and prosthesis stability were recorded and analyzed. Results There are 23 of 769 cases (23/769) had occult fracture around the prosthesis, with an incidence of 2.99% (23/769);. The total revision rate was 0.52% (4/769). The revision patients accounted for 17.39% (4/23) of the patients with occult femoral fractures. The remaining patients received conservative care and successfully joined without their prostheses slipping. Osteoporosis, body mass index, and the surgeon’s experience were identified as the risk variables for periprosthetic occult fractures by univariate analysis (P < 0.05). Conclusion Periprosthetic occult fracture was a complication that can not be ignored in primary total hip arthroplasty. It is the cause of early failure of prosthesis. Osteoporosis, BMI and the surgeon’s experience are all risk factors for periprosthetic occult fractures.

Ultra-High-Molecular-Weight Polyethylene in Hip and Knee Arthroplasties.

Ultra-high-molecular-weight polyethylene (UHMWPE) wear and particle-induced osteolysis contribute to the failure of total hip arthroplasty (THA) and total knee arthroplasty (TKA). Highly crosslinked polyethylene (HXLPE) was developed in the late 1990s to reduce wear and has shown lower wear rates and loosening than conventional UHMWPE in THA. The irradiation dose for crosslinking is up to 100 kGy. However, during crosslinking, free radical formation induces oxidation. Using HXLPE in THA, the cumulative revision rate was determined to be significantly lower (6.2%) than that with conventional UHMWPE (11.7%) at a mean follow-up of 16 years, according to the Australian Orthopaedic Association National Joint Replacement Registry. However, HXLPE does not confer to TKA the same advantages it confers to THA. Several alternatives have been developed to prevent the release of free radicals and improve polymer mechanical properties, such as thermal treatment, phospholipid polymer 2-methacryloyloxyethyl phosphorylcholine grafting, remelting, and vitamin E addition. Among these options, vitamin E addition has reported good clinical results and wear resistance similar to that of HXLPE without vitamin E, as shown by short-term clinical studies of THA and TKA. This review aims to provide a comprehensive overview of the development and performance of UHMWPE in THA and TKA.

Is Outcome of Total Hip Arthroplasty for Hip Fracture Inferior to That of Arthritis in a Contemporary Arthroplasty Practice?

BackgroundOutcome of total hip arthroplasty (THA) for femoral neck fractures (FNF) has been associated with higher complication rates. However, THA for FNF is not always performed by arthroplasty surgeons. This study aimed to compare THA outcomes for FNF to osteoarthritis (OA). In doing so, we described contemporary THA failure modes for FNF performed by arthroplasty surgeons. MethodsThis was a retrospective, multisurgeon study from an academic center. Of FNFs treated between 2010 and 2020, 177 received THA by an arthroplasty surgeon [mean age 67 years (range, 42 to 97), sex: 64.4% women]. These were matched (1:2) for age and sex with 354 THAs performed for hip OA, by the same surgeons. No dual-mobilities were used. Outcomes included radiologic measurements (inclination/anteversion and leg length), mortality, complications, reoperation rates and patient-reported outcomes including Oxford Hip Score. ResultsPostoperative mean leg-length difference was 0 mm (range, −10 to −10 mm), with a mean cup inclination and anteversion of 41 and 26°, respectively. There was no difference in radiological measurements between FNF and OA patients (P = .3). At a 5-year follow-up, mortality rate was significantly higher in the FNF-THA group compared to the OA-THA group (15.3 versus 1.1%; P < .001). There was no difference in complications (7.3 versus 4.2%; P = .098) or reoperation rates (5.1 versus 2.9%; P = .142) between the groups. Dislocation rate was 1.7%. Oxford Hip Score at the final follow-up was similar [43.7 points (range, 10 to 48) versus 43.6 points (range, 10 to 48); P = .030]. ConclusionTHA for the treatment of FNF is a reliable option and is associated with satisfactory outcomes. Instability was not a common reason of failure, despite not using dual-mobility articulations in this at-risk population. This is likely due to THAs being performed by the arthroplasty staff. When patients live beyond 2 years, similar clinical and radiographic outcomes with low rates of revision can be expected compared to elective THA for OA. Level of evidenceIII, case-control study.

MRI-based artificial intelligence to predict infection following total hip arthroplasty failure

PurposeTo investigate whether artificial intelligence (AI) can differentiate septic from non-septic total hip arthroplasty (THA) failure based on preoperative MRI features.Materials and methodsWe included 173 patients (98 females, age: 67 ± 12 years) subjected to first-time THA revision surgery after preoperative pelvis MRI. We divided the patients into a training/validation/internal testing cohort (n = 117) and a temporally independent external-testing cohort (n = 56). MRI features were used to train, validate and test a machine learning algorithm based on support vector machine (SVM) to predict THA infection on the training-internal validation cohort with a nested fivefold validation approach. Machine learning performance was evaluated on independent data from the external-testing cohort.ResultsMRI features were significantly more frequently observed in THA infection (P < 0.001), except bone destruction, periarticular soft-tissue mass, and fibrous membrane (P > 0.005). Considering all MRI features in the training/validation/internal-testing cohort, SVM classifier reached 92% sensitivity, 62% specificity, 79% PPV, 83% NPV, 82% accuracy, and 81% AUC in predicting THA infection, with bone edema, extracapsular edema, and synovitis having been the best predictors. After being tested on the external-testing cohort, the classifier showed 92% sensitivity, 79% specificity, 89% PPV, 83% NPV, 88% accuracy, and 89% AUC in predicting THA infection. SVM classifier showed 81% sensitivity, 76% specificity, 66% PPV, 88% NPV, 80% accuracy, and 74% AUC in predicting THA infection in the training/validation/internal-testing cohort based on the only presence of periprosthetic bone marrow edema on MRI, while it showed 68% sensitivity, 89% specificity, 93% PPV, 60% NPV, 75% accuracy, and 79% AUC in the external-testing cohort.ConclusionAI using SVM classifier showed promising results in predicting THA infection based on MRI features. This model might support radiologists in identifying THA infection.

Causes of revision after total hip arthroplasty in patients undergoing revision total hip arthroplasty younger than 50 years of age

Background and Aims: Young patients undergoing revision total hip arthroplasty (THA) have different indications and causes of failure of THA. This retrospective cohort study examines the causes of failure of THA in a patient younger than 50 years. Subjects and Methods: Clinical and demographic data of 146 revision THA (130 patients) were gathered from case records of patients who underwent revision THA at our institute between January 1, 2018, and December 31, 2021. Fifty-two hips (46 patients) were younger than 50 years at the time of revision. Baseline characteristics, cause for revision, implants revised, and duration of survival were noted. Statistical Analysis: Chi-squared test was implemented to find a correlation, and P < 0.05 was considered statistically significant. Results: We had 52 hips, 46 patients (28 females), and the mean age at primary THA was 33.9 years, the mean age at revision THA was 44.5 years, and the mean survival of implants was 10.6 years. The most common diagnosis for primary THA was avascular necrosis of the femoral head (21 hips, 40.38%), followed by inflammatory arthritis. The most common cause of failure was aseptic loosening (27 hips, 51.92%). As compared to the overall population undergoing revision THA (60/146 hips, 41.09%), patients younger than 50 years having more frequency of aseptic loosening as a cause of failure of THA and less frequency of periprosthetic joint infection, instability, and fracture; but statistically significant difference was not found (P = 0.38). No correlation was found between the type of implants used (P = 0.84) and diagnosis at index THA (P = 0.78), with the cause of failure of THA. Conclusions: Aseptic loosening of THA is the most common mode of failure in patients younger than 50 years.

Monobloc press-fit cups with large-diameter bearings are safe in revision total hip arthroplasty.

Instability is a major cause of failure of revision total hip arthroplasty (THA) which can be avoided with the use of monobloc press-fit cups with large diameter heads (LDH). This consecutive case series analyses whether LDH monobloc components are a safe and clinically beneficial option for revision THA. This consecutive case series includes 47 revision THA with LDH monobloc acetabular cup. Acetabular bone defects were Paprosky type I (42), type IIA (2) and type IIC (3). The Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), Forgotten Joint Score (FJS) and the Patient's Joint Perception (PJP) scores were analysed and a radiographic evaluation for signs of implant dysfunction was performed. After a mean follow-up of 4.5 years, there were 5 (10.6%) acetabular cup re-revisions: 2 loss of primary fixation and 3 instabilities. Implant survivorship at 4-years was 89.4% (95% CI: 89.3 to 89.5). Recurrent hip dislocation was reported in 1 patient (2.1%) and remains under conservative treatment. The mean WOMAC and FJS were 19.5 (16.8; 0.0 to 58.3) and 57.3 (28.9; 6.3 to 100.0), respectively. Regarding the PJP, 3 (8.8%) patients perceived their hip as natural, 8 (23.5%) as an artificial joint with no restriction, 14 (41.2%) with minor restriction and 9 (26.5%) with major restriction. In cases of revision THA with limited bone loss, press-fit primary fixation with LDH monobloc acetabular components are valuable options that offer excellent mid-term out-comes with low re-revision and joint instability rates.

Comparison of periprosthetic joint infection rates in the direct anterior approach and non-anterior approaches to primary total hip arthroplasty: a systematic review and meta-analysis.

Periprosthetic joint infection is a serious complication and devastating mode of failure of total hip arthroplasty. Various surgical approaches exist for total hip arthroplasty, including the increasingly popularised direct anterior approach. There is no clear consensus on which approach is least associated with periprosthetic joint infection. The objective of this meta-analysis was to compare the rate of periprosthetic joint infection between surgical approaches to primary total hip arthroplasty for osteoarthritis. A search of 3 electronic databases (PubMed/MEDLINE, Embase, and Cochrane Library) was conducted for relevant studies up to June 2020 with a defined list of inclusion and exclusion criteria. Randomised controlled trials and longitudinal studies reporting periprosthetic joint infection rates after primary total hip arthroplasty for osteoarthritis were included based on surgical approach. Data extraction was completed, and a meta-analysis was then performed using OpenMeta[Analyst] software. A total of 24,407 hips were included for meta-analysis with an overall PJI incidence of 0.57%. The incidence rate for periprosthetic joint infection was 0.77% in the direct anterior approach group and 0.44% in the non-anterior approach group. The use of an anterior approach for a total hip arthroplasty was associated with an increased risk for periprosthetic joint infection (odds ratio = 1.404; 95% confidence interval, 0.711-2.771; p = 0.03). The direct anterior approach to total hip arthroplasty may be associated with a significantly increased risk for periprosthetic joint infection compared to non-anterior approaches, even though the overall rate was still small. This should be considered by orthopedic surgeons when choosing the surgical approach.

Dissociation of liner from cup in THA: does liner damage affect the risk of dissociation?

IntroductionA rare catastrophic failure of modular component Total Hip Arthroplasty is dissociation between liner and cup, which has been associated with component malposition and/or impingement and seems to be more frequently associated with the Pinnacle system. The goal of this study was to evaluate the resistance of a polyethylene liner to lever-out-forces of the Pinnacle locking mechanism and the locking mechanisms of two other current cup/liner systems using a standardized testing method (ASTM).Materials and methodsFive of each of the following cups were evaluated with their corresponding polyethylene liners: Pinnacle Multihole cup with and without intact anti-rotation tabs (ART’s); Allofit-S-Alloclassic and Plasmafit Plus7 cups. The ASTM test set-up was used to evaluate the lever-out force resulting in liner dissociation for each construct.ResultsThe Pinnacle construct with intact ARTs required the greatest force (F) to achieve dissociation (263.2 ± 79.2 N) followed by the Plasmafit Plus7 (185.8 ± 36.9 N) and the Allofit-S (101.4 ± 35.3 N) constructs, respectively. However, after removal of the ARTs, the Pinnacle system required the least force to achieve dissociation (75.1 ± 22.2 N) (p < 0.001).ConclusionsThe intact Pinnacle system appeared the most stable in lever-out tests when compared to the other systems. However, after removal of the ARTs, the Pinnacle system required the least force for dissociation, consistent with locking mechanism failure, and suggesting that the ARTs are a critical component of the locking mechanism. Our findings are consistent with the clinical experience of dissociated Pinnacle constructs displaying damaged or missing ARTs, and that damage to these may increase risk of liner dissociation.

The incidence of adverse local tissue reaction due to head taper corrosion after total hip arthroplasty using V40 taper and 36 mm CoCr head

Aims Head-taper corrosion is a cause of failure in total hip arthroplasty (THA). Recent reports have described an increasing number of V40 taper failures with adverse local tissue reaction (ALTR). However, the real incidence of V40 taper damage and its cause remain unknown. The aim of this study was to evaluate the long-term incidence of ALTR in a consecutive series of THAs using a V40 taper and identify potentially related factors. Methods Between January 2006 and June 2007, a total of 121 patients underwent THA using either an uncemented (Accolade I, made of Ti12Mo6Zr2Fe; Stryker, USA) or a cemented (ABG II, made of cobalt-chrome-molybdenum (CoCrMo); Stryker) femoral component, both with a V40 taper (Stryker). Uncemented acetabular components (Trident; Stryker) with crosslinked polyethylene liners and CoCr femoral heads of 36 mm diameter were used in all patients. At a mean folllow-up of 10.8 years (SD 1.1), 94 patients (79%) were eligible for follow-up (six patients had already undergone a revision, 15 had died, and six were lost to follow-up). A total of 85 THAs in 80 patients (mean age 61 years (24 to 75); 47 (56%) were female) underwent clinical and radiological evaluation, including the measurement of whole blood levels of cobalt and chrome. Metal artifact reduction sequence MRI scans of the hip were performed in 71 patients. Results A total of 20 ALTRs were identified on MRI, with an incidence of 26%. Patients with ALTR had significantly higher median Co levels compared with those without ALTR (2.96 μg/l (interquartile range (IQR) 1.35 to 4.98) vs 1.44 μg/l (IQR 0.79 to 2.5); p = 0.019). Radiological evidence of osteolysis was also significantly associated with ALTR (p = 0.014). Median Cr levels were not significantly higher in those with ALTR compared with those without one (0.97 μg/l (IQR 0.72 to 1.9) v 0.67 μg/l (IQR 0.5 to 1.19; p = 0.080). BMI, sex, age, type of femoral component, head length, the inclination of the acetabular component, and heterotopic ossification formation showed no significant relationship with ALTR. Conclusion Due to the high incidence of local ALTR in our cohort after more than ten years postoperatively, we recommend regular follow-up investigation even in asymptomatic patients with V40 taper and metal heads. As cobalt levels correlate with ALTR occurrence, routine metal ion screening and consecutive MRI investigation upon elevation could be discussed. Cite this article: Bone Joint J 2022;104-B(7):852–858.

Cutibacterium Positive Cultures in Total Hip Arthroplasty: Contaminant or Pathogen?

Cutibacterium spp. is an emerging pathogen in total hip arthroplasty (THA) that is not well evaluated in the literature. This study reported on the presentation and management of THA complicated by positive intraoperative Cutibacterium cultures. This is a retrospective review of 27 revision THAs with positive monomicrobial intraoperative Cutibacterium cultures from 2014 to 2020 at one academic center. These patients were divided into two cohorts based on meeting Musculoskeletal Infection Society (MSIS) criteria for prosthetic joint infections (PJI). Patient demographics, preoperative labs, and hip aspirate results were collected. Procedure performed, postoperative antibiotic regimens, and repeat infections were recorded. Data were compared with univariate analysis. Nine of the 27 patients preoperatively met MSIS criteria for PJI. Patients with positive MSIS criteria had significantly higher median synovial cell count (P= .048) and neutrophil percentage in a preoperative aspirate (P= .050). Eight patients with positive MSIS criteria received six weeks of postoperative antibiotics compared to two patients with negative criteria. Two patients with positive MSIS criteria had a postoperative infection that required further surgical intervention. Four patients with negative criteria who required further surgical intervention did not receive postoperative antibiotics after initial revision. While often categorized as a contaminant, Cutibacterium is an increasingly recognized pathogen in THA. Cutibacterium can often present with normal serology, which may result in misdiagnosis as aseptic THA failure. Without the administration of postoperative antibiotics after positive cultures, there is a risk for persistent infection requiring further surgical intervention.

Model validation for estimating taper microgroove deformation during total hip arthroplasty head-neck assembly

Total hip arthroplasty (THA) failure and the need for revision surgery can result from fretting-corrosion damage of the head-neck modular taper junctions. Prior work has shown that implant geometry, such as microgrooves, influences damage on retrieved implants. Microgroove deformation within the modular taper junction occurs when the female head taper meets the male stem taper during THA surgical procedure. The objective of this work was to validate microgroove deformation after head-neck THA assembly as calculated by finite element analysis (FEA). Four 28 mm CoCrMo head tapers and four Ti6Al4V stem tapers were scanned via white light interferometry. Heads were assembled onto stem tapers until 6kN reaction force was achieved, followed by head removal using a cut-off machine. The stem tapers were then rescanned and analyzed. Simultaneously, a 2D axisymmetric FEA model was developed and assembled per implant geometries and experimental data. For experiments and FEA, the mean change in microgroove height was 1.23 µm and 1.40 µm, respectively. The largest microgroove height change occurred on the proximal stem taper due to the conical angles of the head and stem tapers. FEA showed that the head-stem assembly induced high stresses and microgroove peaks flattening. 76–89% and 91–100% of the microgrooves in the experiments and FEA, respectively, showed height changes along the contact length of the stem taper. A validated FEA model of THA head-neck modular junction contact mechanics is essential to identifying implant geometries and surface topographies that can potentially minimize the risk of fretting and fretting-corrosion at modular junctions.

Can machine learning models predict failure of revision total hip arthroplasty?

Revision total hip arthroplasty (THA) represents a technically demanding surgical procedure which is associated with significant morbidity and mortality. Understanding risk factors for failure of revision THA is of clinical importance to identify at-risk patients. This study aimed to develop and validate novel machine learning algorithms for the prediction of re-revision surgery for patients following revision total hip arthroplasty. A total of 2588 consecutive patients that underwent revision THA was evaluated, including 408 patients (15.7%) with confirmed re-revision THA. Electronic patient records were manually reviewed to identify patient demographics, implant characteristics and surgical variables that may be associated with re-revision THA. Machine learning algorithms were developed to predict re-revision THA and these models were assessed by discrimination, calibration and decision curve analysis. The strongest predictors for re-revision THA as predicted by the four validated machine learning models were the American Society of Anaesthesiology score, obesity (> 35kg/m2) and indication for revision THA. The four machine learning models all achieved excellent performance across discrimination (AUC > 0.80), calibration and decision curve analysis. Higher net benefits for all machine learning models were demonstrated, when compared to the default strategies of changing management for all patients or no patients. This study developed four machine learning models for the prediction of re-revision surgery for patients following revision total hip arthroplasty. The study findings show excellent model performance, highlighting the potential of these computational models to assist in preoperative patient optimization and counselling to improve revision THA patient outcomes. Level III, case-control retrospective analysis.

Indication for Proximal Femoral Replacement Is Associated With Risk of Failure.

Proximal femoral replacement (PFR) is reserved as a salvage procedure after failed total hip arthroplasty (THA) or after wide margin resection of tumors involving the proximal femur. Although failure of the PFR construct remains a significant problem, indication has not previously been investigated as a risk factor for failure. This study retrospectively evaluated patients who underwent PFR over a consecutive 15-year period for primary sarcoma or metastatic disease of the proximal femur, compared with conversion to PFR after failed THA. PFR failure was defined as recurrent prosthetic dislocations, periprosthetic fracture, aseptic loosening, or infection that ultimately resulted in revision surgery. Overall, 99 patients were evaluated, including 58 in the neoplasm and 41 in the failed THA cohorts. Failed THA patients were older (P < .001), with a greater proportion having comorbid hypertension (P= .008), cardiac disease (P= .014), and history of prior ipsilateral and intracapsular surgeries (P< .001). The failure rate was significantly higher in failed THA patients (39.0% vs 10.3%; P < .001) with significantly shorter implant survivorship on Kaplan-Meier analysis (P= .003). A multivariate Cox proportional hazards model showed that THA failure was the only independent predictor for PFR failure (hazard ratio: 4.26, 95% confidence interval: 1.66-10.94; P= .003). This study revealed significantly worse PFR implant survivorship in patients undergoing PFR for the indication of failed THA compared with neoplasm. Although the underlying etiology of this relationship remains to be explicitly outlined, poor bone quality and soft tissue integrity, multiple prior surgeries, and comorbid conditions are likely contributing factors.

Mechanical failure of total hip arthroplasties and associated risk factors

IntroductionMechanical failure of total hip arthroplasties is a rare but devastating complication. With increasing numbers in primary arthroplasty implantation, revision surgeries are indicated more often. Therefore, understanding the mechanism and the location of failure is essential in determining proper treatment. Aim of this study was to identify mechanical failures of all total hip arthroplasties performed in a major academic center as well as the associated risk factors such as BMI and sports.MethodsA retrospective trial was conducted using our prospective arthroplasty database. Database was searched for all patients presenting with mechanical failures of total hip arthroplasty (THA) to the emergency department between 2011 and 2019. All medical charts and radiographs as well as surgical reports were analyzed to identify demographics, implant choice in addition to location of failure and subsequent treatment.ResultsIn total, 13 patients suffering from mechanical total hip implant failure were found. The femoral neck (conus) was broken in four patients, the stem in five cases, one broken inlay, two cup failures and one conus dislocation. The mean BMI was 31.42 ± 5.29 kg/m2 including five patients who have obesity class II. In all cases, revision surgeries were indicated. No structural causes or underlying risk factors such as repeated physical load (i.e. in sports) were identified.ConclusionImplant failure does not seem to correlate with participation in sports or BMI. Catastrophic failure of implants is a technical challenge requiring special extraction instruments that can be difficult even for experienced surgeons. It should be noted that functional outcome is often worse for this group of patients after surgery than comparing against those revised for loosening.Level of evidence.III, Retrospective Trial.

Stem-bone contact patterns of a long straight tapered uncemented stem for primary THA.

Despite excellent long-term survival, total hip arthroplasty (THA) can fail due to aseptic loosening, dislocations, sepsis and periprosthetic fractures, all of which remain considerably burdensome. Aseptic loosening is one of the main causes of THA failure, often due to osteolysis, stress shielding and/or lack of primary stability. This study aimed to investigate stem-bone contact patterns of a long straight-tapered uncemented stem following primary THA, and to determine whether these contact patterns are related to preoperative femoral morphology and whether they influence postoperative outcomes. The authors reviewed a continuous series of 60 hips (55 patients) that underwent primary THA using the Corail® stem (DePuy, Leeds, UK). Patients were evaluated pre- and post-operatively using the Japanese Orthopaedic Association (JOA) score. Computed-tomography (CT) scans were performed preoperatively to assess femoral bone morphology, and immediate postoperatively to assess stem-bone contact patterns. Postoperative radiographs were performed to calculate the Engh score. Regression analyses were performed to determine associations of postoperative JOA and Engh score with 27 independent variables. Forty-nine patients (54 hips) were assessed at 31 ± 8months, with a JOA score of 92.9 ± 8.1 and an Engh score of 21.2 ± 1.9. Six patients (6 hips) were lost-to-follow-up. There were no revisions and only one complication (recurrent dislocation). Stem-bone contact patterns were associated with preoperative femoral morphology (sagittal CFI [p = 0.006], femoral offset [p = 0.028], and NSA [p = 0.022]), but were not associated with either postoperative JOA or postoperative Engh score. The stem-bone contact patterns of a long straight-tapered uncemented stem are related to preoperative femoral morphology, but do not influence short-term postoperative outcomes. Contact patterns were related to preoperative femoral offset, NSA, and sagittal CFI, but not coronal CFI. Surgeons should, therefore, consider sagittal morphology for surgical planning and templating, in addition to the conventional parameters of coronal morphology.

Gross Trunnion Failure in Total Hip Arthroplasty: A Case Study and Review Article

Gross Trunnion Failure in Total Hip Arthroplasty: A Case Study and Review Article

The impact of stem fixation method on Vancouver Type B1 periprosthetic femoral fracture management.

Introduction: Our understanding of the impact of the stem fixation method in total hip arthroplasty (THA) on the subsequent management of periprosthetic femoral fractures (PFF) is still limited. This study aimed to investigate and quantify the effect of the stem fixation method, i.e., cemented vs. uncemented THA, on the management of Vancouver Type B1 periprosthetic femoral fractures with the same plate. Methods: Eight laboratory models of synthetic femora were divided into two groups and implanted with either a cemented or uncemented hip prosthesis. The overall stiffness and strain distribution were measured under an anatomical one-legged stance. All eight specimens underwent an osteotomy to simulate Vancouver type B1 PFF’s. Fractures were then fixed using the same extramedullary plate and screws. The same measurements and fracture movement were taken under the same loading conditions. Results: Highlighted that the uncemented THA and PFF fixation constructs had a lower overall stiffness. Subsequently, the mechanical strain on the fracture plate for the uncemented construct was higher compared to the cemented constructs. Conclusion: PFF fixation of a Vancouver type B1 fracture using a plate may have a higher risk of failure in uncemented THAs.

The relation between body weight and wear in total hip prosthesis: A finite element study

As the current obesity epidemic grows, an increased number of obese patients undergoing Total Hip Arthroplasty (THA) can be expected in the coming years. The National Health Service of the UK (NHS) recommends that an obese patient should undergo weight loss before THA. It is understood that an increased body weight would increase the wear rates on the prostheses, however, the extent of increased wear and the impact on the longevity of the prosthesis is unclear. The NHS found that 45% of THA failures in 2019 were caused by wear which led to a multitude of failures such as infection, aseptic loosening and dislocation such that a revision surgery is then needed. In this study, a finite element model was created to model a walking cycle and a newly developed wear algorithm was used to perform a series of computational wear analyses to investigate the effect of different patient weights on the evolution of wear in THAs up to 5 million cycles. The wear rates shown in this study are closely comparable to previous literature. The XLPE volumetric wear rates were found to be between 15 and 35 mm3/yr (range: 1.5–57 .6mm3/yr) and femoral head taper surface volumetric wear rates were between 0.174 and 0.225 mm3/yr (range: 0.01–3.15 mm3/yr). The results also showed that an increased weight of 140 kg can increase the metallic wear by 26% and polyethylene wear by 30% when compared to 100 kg body weight. As increased wear can lead to a multitude of failure such as aseptic loosening, dislocation and metallosis, from this study, it is recommended that obese patients undergo recommended weight loss and maintain this lesser weight to reduce wear and prolong the life of the THA.

Cementation of a dual mobility cup in a well-fixed acetabular component- a reliable option in revision total hip arthroplasty?

BackgroundThe “cup-in-cup” technique allows for revision of failed total hip arthroplasty (THA) when the cementless cup is well fixed. Furthermore, it can be used for liner wear or mechanical failure where liner replacement may be impossible or impractical. Recently, the “cup-in-cup” technique in combination with dual mobility cups (DMC) has drawn increased attention. Our aim was to report on the clinical and radiographic outcomes following this surgery.MethodsFrom 2015 to 2020, 33 patients treated with the DMC- “cup in cup” technique were retrospectively reviewed. Fourteen patients had died while 19 were available for the final follow-up (FU), of which 15 underwent both a radiograph and a FU visit, 2 underwent a radiograph only and 2 underwent a telephone interview only. Patient-related outcome measures included the HHS and the WOMAC. Radiographs were assessed for implant loosening and positioning. Primary endpoint was revision of any cause and secondary endpoint was loosening of the DMC at the latest FU. The survival analysis was conducted using the Kaplan-Meier method.ResultsThe mean age at surgery was 78.6 ± 7.1 (63–93) years and the mean surgery duration was 124.4 ± 52.0 (60–245) minutes. Recurrent dislocation (42.4%), periprosthetic fracture (39.4%) and polyethylene wear (6.1%) were the most frequent reasons for surgery. The mean FU duration (n = 19) was 28.5 ± 17.3 (3–64) months. The mean HHS score at FU was 59.4 ± 22.2 (29–91) and the mean WOMAC score was 59.7 ± 25.6 (15.6–93.8).Two cups were revised due to instability and one revision was performed due to periprosthetic joint infection, accounting for an overall cup survival rate of 86.8% after a mean FU of 22.9 ± 18.0 (1.5–64.6) months. The survival rate free of loosening was 90.9% after a mean FU of 22.3 ± 18.5 (1.5–64.7) months.ConclusionsWe found that the cementation of a DMC in a well-fixed cup is a promising short- to mid-term treatment addressing THA instability especially in elderly and frail patients, who benefit from a reduced operation time. Proper cementation technique, adequate cup positioning as well as selection of a sufficiently large DMC are crucial for treatment success. Longer FUs will be needed in the future in order to further prove the benefit of this technique.

Intraprosthetic Dislocation of Dual-Mobility Total Hip Arthroplasty: The Unforeseen Complication.

Total hip arthroplasty (THA) is one of the most successful and widely accepted orthopedic procedures. Instability after THA is one of the most significant postoperative complications. Dual-mobility THA components were introduced in 1974 to overcome the risk of instability by increasing the jump distance. Dual-mobility bearings couple two articulations, namely, one between a 22-28 mm prosthetic head and polyethylene liner and another larger articulation between the polyethylene liner and the metal cup. Dislocation of the polyethylene liner and the consequent direct articulation between the prosthetic head and metal cup is recognized as intraprosthetic dislocation (IPD). This mode of THA failure is specific to dual-mobility implants. Despite the reduced incidence of IPD in modern dual-mobility implants compared to the early designs, iatrogenic IPD can occur during closed reduction of dislocated polyethylene liner-metal cup articulation. IPD requires timely diagnosis and early surgical intervention to minimize the necessity of major revision surgeries. This study presents a comprehensive review for dual-mobility-bearing THA, including the history and biomechanics, and focuses on the pathomechanics, diagnosis, and management of IPD.