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Background: Femoral stem fracture is a rare and morbid complication after total hip arthroplasty (THA). There currently exists a paucity of reports regarding cementless non-modular, titanium, femoral stem fractures., Methods: A case report and review of the literature for modular and non-modular stem fractures was conducted., Results: We report the first documented fatigue fracture in the Wagner Self-Locking (SL) Revision (Zimmer-Biomet, Warsaw, Indiana) System., Discussion: Proximal stress shielding can lead to poor bone support and contribute to excessive cantilever bending forces, even on non-modular, titanium, tapered stems. Body mass index, prosthetic diameter, and stem length are factors that need to be vetted in order to prevent this complication.

Background: The purpose of this study was to examine the outcomes of repeat revision after failure of a constrained liner., Methods: We reviewed 1212 consecutive revisions and identified 74 (6%) revisions of a failed constrained liner in 46 patients with a mean age of 65 years. The most common reasons for revision of a constrained liner were recurrent instability (64.9%) and infection (25.7%)., Results: At a mean of 35 months, 42 of the 74 hips (57%) required repeat revision. Kaplan-Meier revision-free survival was 24% at 10 years. Thirty-two of the 74 revisions (43%) had a dislocation event after the index revision. Kaplan-Meier dislocation-free survival was 43% at 10 years. There was a higher failure rate among the 34 patients with abductor deficiency (hazard ratio 1.90, 95% confidence interval, 1.06-3.43; P = .032)., Conclusion: Patients undergoing revision of a failed constrained liner have a high likelihood of recurrent dislocation and repeat revision surgery., Level of Evidence: Level IV., (Copyright © 2018. Published by Elsevier Inc.)

Trunnionosis of total hip arthroplasty (THA) components has been an increasingly reported complication. Consensus is lacking regarding preventive practices and the overall incidence of trunnionosis. In this study, fellowship-trained adult reconstruction orthopedic surgeons were surveyed to identify expert opinions. A 25-question, web-based survey regarding trunnionosis incidence, prevention, and biomaterials was sent to 345 fellowship-trained adult reconstruction orthopedic surgeons in North America. The survey yielded 151 (43.8%) responses from surgeons with a mean of 11.97±9.49 years of experience. These surgeons believe that the material composite of the head-neck junction is the most important contributor to trunnionosis. They often choose a ceramic head with a metal alloy stem to reduce trunnionosis. They more commonly impact the femoral head 3 times than once. Fifty-one percent believe that trunnionosis leads to THA failure for between 0% and 2% of all THA revisions, whereas 48.3% believe that the failure rate is greater than 2%. More than half (53.6%) of these surgeons recommend a revision THA if a patient's serum cobalt level is greater than 10 µg/L, regardless of symptom presence. The incidence of trunnionosis appears to be increasing due to changes in implants and/or an increased awareness of the problem, with 48.3% of these surgeons believing that trunnionosis is the primary cause of THA failure for more than 1 in 50 patients. Some suggested preventive measures include cleaning and drying the trunnion, using ceramic femoral heads, matching THA components, and adding titanium sleeves on well-fixed stems that are retained during revision surgery. [Orthopedics. 2018; 41(4):e557-e562.]., (Copyright 2018, SLACK Incorporated.)

Background: Lateral unicompartmental knee arthroplasty (UKA) has been shown to be an effective procedure to treat isolated lateral compartment osteoarthritis with excellent long-term survivorship. Whether a medial parapatellar approach or a lateral parapatellar approach is superior in lateral UKA is unknown. The purpose of this study was to determine if there is a difference in intermediate-term clinical outcomes in patients undergoing lateral UKA through a lateral vs medial parapatellar approach., Methods: We retrospectively reviewed a consecutive series of 65 patients who underwent lateral UKA with a minimum of 2-year follow-up. Fifty-two patients (80%) had a lateral approach and 13 (20%) a medial parapatellar approach. Patient demographics, preoperative and postoperative radiographic findings, need for revision surgery, Knee Society Score, and range of motion were assessed., Results: Overall survivorship was 94% at a mean of 82 months; with the sample size available for study, there was no difference in survivorship between the groups. There was no difference in Knee Society Score or revision to total knee arthroplasty (5% vs 7%, P = 1.000) between the medial and lateral approach groups. Comparatively, the lateral approach group did have significantly greater postoperative flexion (123.6° vs 116.5°, P = .006) and greater improvement in flexion from preoperative measurements (3.0 vs -8.0°, P = .010)., Conclusion: Although our sample size was small, we could not demonstrate a difference in revision rates or clinical outcome scores when comparing a lateral or a medial approach with lateral UKA at intermediate-term follow-up. A lateral approach did have greater postoperative flexion, but its clinical significance remains undetermined., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Background: The ideal fixation for modern tibial components in total knee arthroplasty (TKA) remains controversial with uncertainty on whether cementless implants can yield equivalent outcomes to cemented fixation in early follow-up., Methods: A series of 70 consecutive cases with reverse hybrid cementless fixation were matched to 70 cemented cases from 2008 to 2015 based on implant design and patient demographics., Results: Cementless TKA demonstrated greater aseptic loosening (7 vs 0, P = .013) and revision surgery (10 vs 0, P = .001) than cemented fixation within 5 years of follow-up, but with no clinically significant differences in outcome scores., Conclusion: It remains unclear whether early aseptic loosening in cementless TKA can be reduced with enhanced adjunct fixation and what proportion of early failure justifies the potential lifelong fixation through biologic ingrowth of cementless tibial components., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Background: There are increasing reports of total hip arthroplasty failure subsequent to modular taper junction corrosion. The surfaces of tapers are machined to have circumferential machining marks, resulting in a surface topography of alternating peaks and valleys on the scale of micrometers. It is unclear if the geometry of this machined surface topography influences the degree of fretting and corrosion damage present on modular taper junctions or if there are differences between modular taper junction material couples., Questions/purposes: (1) What are the differences in damage score and surface topography between CoCr/CoCr and CoCr/Ti modular junctions? (2) How are initial surface topography, flexural rigidity, taper angle mismatch, and time in situ related to visual taper damage scores for CoCr/CoCr couples? (3) How are initial surface topography, flexural rigidity, taper angle mismatch, and time in situ related to visual taper damage scores for CoCr/Ti couples?, Methods: Damage on stem and head tapers was evaluated with a modified Goldberg score. Differences in damage scores were determined between a group of 140 CoCr/CoCr couples and 129 CoCr/Ti couples using a chi-square test. For a subgroup of 70 retrievals, selected at random, we measured five variables, including initial stem taper machining mark height and spacing, initial head taper roughness, flexural rigidity, and taper angle mismatch. All retrievals were obtained at revision surgeries. None were retrieved as a result of metal-on-metal failures or were recalled implants. Components were chosen so there was a comparable number of each material couple and damage score. Machining marks around the circumference of the tapers were measured using white light interferometry to characterize the initial stem taper surface topography in terms of the height of and spacing between machining mark peaks as well as initial head taper roughness. The taper angle mismatch was assessed with a coordinate measuring machine. Flexural rigidity was determined based on measurements of gross taper dimensions and material properties. Differences of median or mean values of all variables between material couples were determined (Wilcoxon rank-sum tests and t-tests). The effect of all five variables along with time in situ on stem and head taper damage scores was tested with a multiple regression model. With 70 retrievals, a statistical power of 0.8 could be achieved for the model., Results: Damage scores were different between CoCr/CoCr and CoCr/Ti modular taper junction material couples. CoCr/CoCr stem tapers were less likely to be mildly damaged (11%, p = 0.006) but more likely to be severely damaged (4%, p = 0.02) than CoCr/Ti stem tapers (28% and 1%, respectively). CoCr/CoCr couples were less likely to have moderately worn head tapers (7% versus 17%, p = 0.003). Stem taper machining mark height and spacing and head taper roughness were 11 (SD 3), 185 (SD 46), and 0.57 (SD 0.5) for CoCr/CoCr couples and 10 (SD 3), 170 (SD 56), and 0.64 (SD 0.4) for CoCr/Ti couples, respectively. There was no difference (p = 0.09, p = 0.1, p = 0.16, respectively) for either factor between material couples. Larger stem taper machining mark heights (p = 0.001) were associated with lower stem taper damage scores, and time in situ (p = 0.006) was associated with higher stem taper damage scores for CoCr/CoCr material couples. Stem taper machining marks that had higher peaks resulted in slower damage progression over time. For CoCr/Ti material couples, head taper roughness was associated with higher stem (p = 0.001) and head taper (p = 0.003) damage scores, and stem taper machining mark height, but not time in situ, was associated with lower stem taper damage scores (p = 0.007)., Conclusions: Stem taper surface topography was related to damage scores on retrieved head-neck modular junctions; however, it affected CoCr/CoCr and CoCr/Ti couples differently., Clinical Relevance: A taper topography of circumferential machining marks with higher peaks appears to enable slower damage progression and, subsequently, a reduction of the reported release of corrosion products. This may be of interest to implant designers and manufacturers in an effort to reduce the effects of metal release from modular femoral components.

The use of metal-on-metal bearing surfaces for total hip arthroplasty increased dramatically in the past decade for a variety of reasons, including the advantage of using larger-diameter femoral heads to reduce instability. However, recent research suggesting negative outcomes and high failure rates associated with some of these implants has decreased their use. Further, the use of larger-diameter femoral heads on relatively small femoral neck tapers has caused concern about localized corrosion at this junction, particularly with varus femoral alignment and longer femoral neck and head lengths. Although the advent of modular components offers the surgeon greater intraoperative flexibility, this modularity may prove to be a weak link when coupled with large-diameter femoral heads. This report describes a patient with a history of bilateral metal-on-metal total hip arthroplasty complicated by failure of the right hip as a result of fretting and mechanically assisted crevice corrosion. Notching of the femoral neck and head dissociation occurred 10 years after the primary procedure. The authors describe the patient's presenting symptoms, the possible etiology of the catastrophic failure, and the method of treatment and provide a brief review of metal-on-metal implants that may shed some light on the complications in this case. [Orthopedics.2016; 39(5):e984-e987.]., (Copyright 2016, SLACK Incorporated.)

Background: Aseptic prosthetic loosening is known to be an inflammatory, cellular process. We hypothesized that the synovial cell count would significantly differ among normal controls, patients with aseptic loosening, and patients with other etiologies of aseptic failure after total knee arthroplasty and thus that the cell count would be useful in the diagnosis of aseptic loosening., Methods: Over a six-year time period, all patients undergoing revision total knee arthroplasties at our institution underwent prospective intraoperative aspiration by the two senior authors. Each patient was assigned to a failure category on the basis of a priori criteria: aseptic loosening, periprosthetic infection, component wear, periprosthetic fracture, component malposition, instability, stiffness, and extensor mechanism failure. Simultaneously, patients with well-functioning total knee replacements underwent aspiration as normal controls. Aspirate characteristics were then compared between groups. Receiver-operating characteristic curves were created to determine optimal white blood-cell cutoffs when periprosthetic infection was compared with each individual failure category., Results: Thirty normal control patients and 433 patients who underwent revision total knee arthroplasties were included in this study. The synovial white blood-cell count in the normal control group was 558 ± 522 cells/μL, which did not significantly differ (p = 0.091) from that taken from patients with aseptic loosening (947 ± 1027 cells/μL). However, normal controls had significantly higher white blood-cell counts than subjects with stiffness (367 ± 392 cells/μL; p = 0.002) and significantly lower white blood-cell counts than subjects with periprosthetic fractures (1687 ± 1613 cells/μL; p = 0.002). Subjects with aseptic loosening had significantly higher white blood-cell counts than subjects with component malpositioning (p = 0.002) or stiffness (p = 0.001). When individual aseptic failure categories were compared with periprosthetic infection, the optimal white blood-cell cutoff varied widely, including 2104 cells/μL for component malposition and 4697 cells/μL for periprosthetic fracture, and the optimal differential segmented cell count percentages varied from 47% to 83%., Conclusions: Although synovial fluid aspirates in patients with aseptic loosening and those with normal total knee arthroplasties did not differ, synovial fluid aspirate characteristics differed among categories of aseptic failure. As a result, the optimal diagnosis of periprosthetic infection on the basis of synovial aspiration results may need to utilize different cutoff values depending on the alternative mode of failure being considered. Large prospective studies will be necessary to validate these threshold values., (Copyright © 2015 by The Journal of Bone and Joint Surgery, Incorporated.)

Innovations in the design of dual-modular femoral components have afforded surgeons several intraoperative advantages during both primary and revision total hip arthroplasty (THA). Although use of these implants has become more popular, the long-term outcomes and potential complications of introducing a second modular junction are still to be determined. In addition, concerns about corrosion potentiation at modular junctions in metal-on-metal (MOM) THA have arisen in recent studies. In this article, we present a unique case of fracture at the modular junction of the stem and modular sleeve of a dual-modular femoral component implanted with a MOM articulation. The proposed mechanisms of failure, including crevice and fretting corrosion as well as the potential effect of metal debris generated by MOM articulations, are reviewed. This case report is the first to describe component fracture at the stem-sleeve junction of this modern-generation dual-modular femoral component. Surgeons who encounter a painful dual-modular femoral stem must entertain this mode of failure and consider junctional failure as a potential diagnosis for such a patient, particularly in the setting of a MOM articulation.

In the evaluation of patients with a persistently painful total hip arthroplasty establishing an accurate diagnosis is paramount in the selection of a successful treatment regimen. It is unknown whether synovial analysis might differentiate aseptic loosening from other causes of failure. A physiological basis exists to suggest that aseptic loosening might be a process of non-segmented leukocytes. The objective of this study was to determine if the synovial fluid differential cell count might aid in the diagnosis of aseptic loosening. A retrospective chart review of all patients who had undergone revision hip arthroplasty with pre-operative or intra-operative aspiration results was performed. Aseptic loosening was defined as gross intraoperative movement in the absence of infection. From these results Relative-Operating Characteristic (ROC) curves were created, and sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated. A diagnosis of aseptic loosening was established in 76 of the 253 hips. The ROC curves indicated that lymphocyte count does have utility in the diagnosis of aseptic loosening. If an aspirate has a combination of fewer than 2500 WBCs (sensitivity 93%, specificity 42%, NPV 94%, accuracy 57%) or more than 10% lymphocytes (sensitivity 86%, specificity 42%, NPV 87%, accuracy 55%) then the sensitivity for aseptic loosening is 96%, the specificity is 33%, the NPV is 95% and the accuracy is 52%. In patients with painful total hip arthroplasties in whom infection has been excluded, aspiration data can be a useful adjunct in the diagnosis of aseptic loosening. In aspirates with neither a WBC cell count of less than 2500 nor a lymphocyte cell count of greater than 10% aseptic loosening can be effectively "ruled out" as fewer than 5% of these patients will have aseptic loosening. While non-specific, aspirate differential can be useful to "rule-out" aseptic loosening with a sensitivity and negative predictive value well exceeding that of standard radiographs., (Copyright © 2013 Elsevier Inc. All rights reserved.)

The use of modularity, specifically dual modular femoral stems, in total hip arthroplasty has increased in popularity over the past 2 decades. While offering several distinct advantages intraoperatively, the long-term success of adding a second modular junction has yet to be established. One potential complication of increasing modularity is component fracture. We present a case of modular femoral neck prosthesis fracture necessitating revision surgery to treat this complication. Careful preoperative planning during revision of these failures is essential to avoid morbidity and unnecessary subsequent revision surgeries, as demonstrated in this case. The combined effects of crevice and fretting corrosion, large-diameter femoral head, long modular neck, metal-on-metal articulation, patient size, and activity level may have all played integral roles in creating an environment susceptible to this classic pattern of fatigue fracture., (Copyright © 2013 Elsevier Inc. All rights reserved.)

Pseudotumor formation after hip arthroplasty is a rare complication that can occur with various head-liner articulation couples. Adverse local tissue reactions and pseudotumors have been shown to present as prosthetic infections or implant failures with a broad array of laboratory and imaging findings. We report a case of pseudotumor formation resulting from modular neckstem corrosion in a well-fixed ceramic-on-polyethylene total hip arthroplasty. The patient underwent successful revision surgery using an extended trochanteric osteotomy, long-stem revision femoral component, and headliner exchange. It is critical that surgeons are aware of the potential complications with increased component modularity and the possibility of adverse local tissue reactions resulting from fretting and crevice corrosion at modular junctions.

Early failures of metal-on-metal total hip arthroplasty (THA) occur due to aseptic loosening, metal hypersensitivity reactions, pseudotumor formation, and component seizing. The purpose of this study was to investigate the timing, common modes of failure, clinical outcomes, and incidence of metal-on-metal THA revisions. A review was performed of 80 patients who underwent revision of a failed metal-on-metal THA for any reason. The most common reason for metal-on-metal failure was aseptic acetabular loosening, with a rate of 56.25% (45/80 patients). Early failure of metal-on-metal THAs was noted, with 78% of these revisions being performed within 2 years of the index operation and 92.5% within 3 years. Furthermore, 13% of patients experienced significant localized soft tissue reactions. Mean preoperative Harris Hip Score was 42.35 ± 14.24 and mean postoperative Harris Hip Score was 66.5 ± 23.2 (range, 9.55-95.4), with an average follow-up of 438 ± 492 days (range, 40-2141), or 1.2 years.It is imperative that clinicians be cognizant of the fact that the proposed advantages of metal-on-metal THA are not without potential detrimental sequelae. This article proposes an algorithm to aid in diagnosing the etiology of a painful metal-on-metal THA, as well as 2 classification schemes regarding metal-on-metal THA complications to help direct treatment., (Copyright 2012, SLACK Incorporated.)

Periprosthetic femur fractures after total hip arthroplasty are a growing concern as their prevalence is expected to rise. A retrospective review was performed of all patients undergoing revision total hip arthroplasty with an extended trochanteric osteotomy (ETO) for treatment of a Vancouver B2/B3 fracture at our institution. Fourteen patients were identified having a minimum of 2-year follow-up. Clinical and radiographic evaluation was performed for all patients. At a mean 44.5 months of follow-up, mean modified D'Aubigne and Postel scores were 8.6. In all cases the ETO and fracture healed with radiographic evidence of osseointegration of the femoral component. Use of an ETO for the treatment of periprosthetic femur fractures provides excellent exposure, facilitates component implantation, and is compatible with fracture healing and good short-term clinical results.