Project description:Intraprosthetic fracture of a femoral component is a rare but devastating complication after total hip arthroplasty (THA). We present the case of a 68-year-old man who presented with acute hip pain approximately 8 years after a left THA with a modern cementless, titanium femoral component. Radiographs revealed a fracture of the midportion of the neck of the stem, below the level of the trunnion. The patient underwent an isolated 1-component revision THA with a modular exchange. To our knowledge, this is the only reported case of a catastrophic failure fracture of this particular prosthesis.
Project description:Consensus regarding femoral stem fixation options in revision total knee arthroplasty remains controversial. Tapered, modular, fluted titanium (TMFT) stems have an excellent track record in total hip arthroplasty for their ability to provide axial and rotational stability in situations of compromised host bone. We present 3 successfully treated cases in which the Food & Drug Administration granted permission to use custom TMFT stems in situations of failed femoral fixation in multiple revised knees. These stems hold promise to achieve stable fixation in revision total knee arthroplasty where host metadiaphyseal bone is deficient. Implant manufactures should consider dedicating future resources to create adapters that can link existing successful TMFT stems currently used in hip arthroplasty to revision total knee components when host bone is severely compromised.
Project description:Fractures of well-ingrown femoral components are a rare and often challenging complication after revision total hip arthroplasty. Prior series have documented catastrophic failure at the modular junction of revision femoral components. However, to the authors' knowledge, there has been only 1 report of a mid-stem fracture of a modular tapered revision stem. The present article reports 2 cases of fatigue fractures (14 months and 10 years after implantation) of a tapered modular revision stem. It presents the results of the fracture surface analysis, discusses the etiology of failure, and presents the authors' recommendations on how to best avoid this complication.
Project description:The diagnosis of and decision-making for early revision surgery to treat failure of biological fixation with a proximally coated cementless stem are challenging. A 73-year-old woman was referred to our hospital with thigh pain 2 years after the initial total hip arthroplasty. Although a plain radiograph showed no signs indicating biological fixation failure, digital tomosynthesis showed a highly radiodense line along the proximal part, and bone scintigraphy showed uptake at the distal part. With the diagnosis of biological fixation failure due to the proximal-distal mismatch, the cementless stem was revised to a cemented stem, and the thigh pain was improved after the revision surgery. Digital tomosynthesis and bone scintigraphy can be helpful for the diagnosis of biological fixation failure due to proximal-distal mismatch.
Project description:Background/objectiveA stem sitting proud (SP) or that above the final rasp position remains in some patients who undergo hip replacement using proximally coated tapered wedge stems. Surgeons may face challenges providing the best fit because of unpredictable SP of proximally coated tapered wedge stems. Zimmer Inc. introduced a new rasp to solve this issue but the clinical results of this rasp have not yet been published. Therefore, our aim was to address the following: (1) What is the stem SP incidence using a proximally coated cementless tapered wedge stem? (2) Does the new rasp system (0-mm rasp) improve seating height? and (3) What are the risk factors of stem SP?MethodsWe performed a retrospective study with 338 hips, in which Tri-Lock Bone Preservation Stem (BPS) was used in 181 hips and M/L Taper stem was used in 157 hips (82 hips before and 75 hips after 0-mm rasp use). A positive stem SP was defined as a stem proud height of >2 mm. We analysed and compared SP incidence in two stems and M/L Taper stems before and after the 0-mm rasp use.ResultsAn incidence of stem SP was 13% in the Tri-Lock BPS and 15% in the M/L Taper stem before the 0-mm rasp use. Stem SP incidence in the M/L Taper stem substantially decreased after the 0-mm rasp use (4%). The significant risk factor for stem SP was use of the high offset option in Tri-Lock BPS.ConclusionThe proximally coated tapered wedge stems present potential problems related to stem SP. The new rasp of the M/L Taper stem showed significant improvement in initial seating height.The translational potential of this articleThis study was conducted to understand "stem sitting proud" in proximally coated tapered wedge stem as one of the most popular designs nowadays in adult hip joint arthroplasty field. In this study, we aimed to address the incidence of stem proud, investigated the risk factor and introduced the effect of new rasp system which improve stem seating height.
Project description:PurposePeriprosthetic bone loss around the femoral stem is frequently found after total hip arthroplasty. We have shown that periprosthetic bone mineral density (BMD) loss using the triple tapered stem is consistently much less in comparison with the straight type component. In this study, we compared periprosthetic BMD change with clinical factors.MethodsPostoperative dual-energy X-ray absorptiometry was evaluated at follow-up. BMD was determined based on seven Gruen zones. We further compared BMD with clinical examination: body mass index (BMI), age, Harris hip score (HHS) or University of California at Los Angeles (UCLA) activity rating score.ResultsPeriprosthetic BMD loss of the triple tapered stem was maintained. Especially, BMD in Gruen zone 1 which was maintained at 96% in comparison with the straight tapered stem. We compared the BMD change with clinical factors. There is no correlation between BMD and BMI, age or HHS. However, we found significant correlation between BMD and UCLA activity rating score in Gruen zones 1 and 2 of the triple tapered stem. Further, the correlation coefficient was increased at 48 months in comparison with 24 months.ConclusionThe cementless triple tapered stem maintains periprosthetic bone mineral density. Activity may reflect improving periprosthetic bone quality after THA using a triple tapered stem.
Project description:BackgroundIn clinical trials of THA, model-based radiostereometric analysis (RSA) techniques may be less precise than conventional marker-based RSA for measurement of femoral stem rotation. We verified the accuracy and clinical precision of RSA based on computer-aided design models of a cementless tapered wedge femoral stem.QuestionsWe asked: (1) Is the accuracy of model-based RSA comparable to that of marker-based RSA? (2) What is the clinical precision of model-based RSA?MethodsModel-based RSA was performed using combined three-dimensional computer-aided design models of the stem and head provided by the implant manufacturer. The accuracy of model-based RSA was compared with that of marker-based RSA in a phantom model using micromanipulators for controlled translation in three axes (x, y, z) and rotation around the y axis. The clinical precision of model-based RSA was evaluated by double examinations of patients who had arthroplasties (n = 24) in an ongoing trial. The clinical precision was defined as being at an acceptable level if the number of patients needed for a randomized trial would not differ from a trial done with conventional marker-based RSA (15-25 patients per group).ResultsThe accuracy of model-based RSA was 0.03 mm for subsidence (translation along the y axis) (95% CI for the difference between RSA measurements and actual displacement measured with micrometers, -0.03-0.00) and 0.39° for rotation around the y axis (95% CI, -0.41 to -0.06). The accuracy of marker-based RSA was 0.06 mm for subsidence (95% CI, -0.04-0.01; p = 0.728 compared with model-based RSA) and 0.18° for the y axis rotation (95% CI, -0.23 to -0.07; p = 0.358). The clinical precision of model-based RSA was 0.14 mm for subsidence (95% CI for the difference between double examinations, -0.02-0.04) and 0.79° for the y axis rotation (95% CI, -0.16-0.18).ConclusionsThe accuracy of model-based RSA for measurement of the y axis rotation was not quite as high as that of marker-based RSA, but its clinical precision is at an acceptable level.Clinical relevanceModel-based RSA may be suitable for clinical trials of cementless tapered wedge femoral stem designs.
Project description:BackgroundFemoral stem fracture following total hip arthroplasty is an uncommon event that requires immediate revision surgery.Questions/purposesWe report on four patients who experienced stem fractures of one design and a review of the US Food and Drug Administration adverse event reports on this design.MethodsFracture surfaces of four EMPERION™ (Smith & Nephew, Memphis, TN) femoral stems were analyzed under optical and scanning electron microscopy. A search of the FDA's Manufacturer and User Facility Device Experience (MAUDE) that reports on all EMPERION™ adverse events was completed.ResultsFracture surfaces exhibited characteristics consistent with a fatigue fracture mechanism. Sixteen MAUDE reports claimed stem fracture or breakage of EMPERION™ stems.ConclusionThe four cases of EMPERION™ stem fractures were likely driven by small stem diameter, high offset, and high patient weight. Modular stem-sleeve femoral systems are susceptible to fatigue failure under high stress and should only be used in appropriate patients, whom are not considered obese.
Project description:The present study aimed to investigate the prevalence and clinical consequences of occult intra-operative periprosthetic femoral fractures in total hip arthroplasty (THA). Between 2012 and 2017, a total of 113 primary THAs were enrolled. The mean age of the patients was 66.4 ± 7.6 years. We assessed occult intra-operative periprosthetic femoral fractures with the use of computed tomography (CT) and risk factors, including age, sex, body mass index, diagnosis, stem size, and radiographic parameters of proximal femoral geometry were analyzed. We also assessed the differences in thigh pain and stem subsidence and alignment between the patients with and without occult periprosthetic femoral fracture. Occult intra-operative periprosthetic femoral fractures were found in 13 of 113 hips (11.5%). In 9/13 (69.2%) of occult fractures, fracture lines were started from the region below the tip of the lesser trochanter. Six periprosthetic femoral fractures (5.3%) were found during the operation. Out of the five hips that had detected femoral fractures around the lesser trochanter intra-operatively, four hips (80%) showed concurrent occult fractures on different levels. The female sex (P = .01) and canal filling ratio at 7 cm below the tip of the lesser trochanter (P = .01) were significantly different between the patients with and without occult periprosthetic femoral fracture. The sex was significantly associated with an increased risk in predicting an occult intra-operative periprosthetic femoral fracture (odds ratio of male, 0.25 compared with the female; 95% CI, 0.08-0.85; p = .02). There was a significant difference in the incidence of thigh pain between occult fracture group and non-occult fracture group (P < .05). There were no significant differences in stem subsidence and alignment between the patients with and without occult periprosthetic femoral fracture. All 13 cases of occult intra-operative periprosthetic femoral fractures were healed at the final follow-up. Occult periprosthetic femoral fractures are common during a long, trapezoidal, double-tapered cementless femoral stem fixation in primary THA, that CT scans are helpful to identify them, and that these fractures do not adversely affect the implant's survival if a rigid fixation of the implants has been achieved.
Project description:This study examined early perioperative complications and subsidence following total hip arthroplasty (THA) with a short femoral stem. A retrospective review of 207 consecutive patients (247 hips) having undergone THA via the direct anterior approach produced only six perioperative complications: two intraoperative fractures, three perioperative femur fractures and one dislocation. Subsidence greater than 5 mm was observed in four hips but subsidence did not progress greater than 3 mm at the latest follow-up. Based on these results, cementless THA though the direct anterior approach with a short femoral stem provides a clinical and radiographic advantage while maintaining low complication rates.