Mechanical failure of articulating polymethylmethacrylate (PMMA) spacers in two-stage revision hip arthroplasty: the risk factors and the impact on interim function.

BACKGROUND: This study aimed to investigate the risk factors for mechanical failure of cement spacers and the impact on hip function after two-stage exchange arthroplasty for periprosthetic joint infection (PJI). METHODS: Thirty-one patients (19 males and 12 females) with hip PJIs underwent resection arthroplasty and implantation of cement spacers from January 2014 to December 2015. Patients who encountered spacer-associated mechanical complications in the interim period (14 of 31) were compared with those without complications (17 of 31). Complications were defined as spacer dislocation, spacer fracture, spacer fracture with dislocation, and femoral fracture during or following spacer implantation. Hip functional outcome was assessed using the Harris hip score (HHS). Treatment success was defined according to the following criteria: (1) no symptoms or signs indicative of infection; (2) no PJI-related mortality; and (3) no subsequent surgical intervention for infection after reimplantation surgery. Multivariate logistic regression and Kaplan-Meier survival curves were used for analysis. RESULTS: Fourteen patients (14/31 = 45%) suffered at least one spacer-related complication within the interim period. The development of spacer complications was associated with a younger age (odds ratio [OR] 0.91, 95% confidence interval [CI] 0.83-1.00, p = 0.045) and chronic PJI (OR 14.7, 95% CI 1.19-182, p = 0.036). Patients with spacer complications also had a lower median HHS (37 vs. 60, p < 0.001) before reimplantation in comparison to those without spacer complications. After reimplantation, the two groups had a similar median HHS (90 vs. 89, p = 0.945). Two patients did not undergo reimplantation due to extensive comorbidities, and subsequently retained the antibiotic spacer for definitive treatment. The 2-year treatment success rate was 84.6% in the spacer-complication group and 87.5% in the non-spacer-complication group (p = 0.81). CONCLUSION: There was a high complication rate for articulating PMMA spacers during the interim period of two-stage revision total hip arthroplasty. A young age and chronic infection were the primary risk factors associated with mechanical complications. Patients at high risk of spacer-related mechanical complications should be advised accordingly by surgeons. Knowing the possible risk factors, surgeons should educate patients thoroughly to avoid spacer complications, thereby increasing patient satisfaction in the interim stage. LEVEL OF EVIDENCE: Prognostic Level III.

Perioperative Complications of Total Knee Arthroplasty in Dialysis Patients.

BACKGROUND: Total hip arthroplasty in patients with end-stage renal disease (ESRD) may be associated with a high complication rate. However, the perioperative complication and mortality rates in these patients after total knee arthroplasty (TKA) have rarely been investigated. The purposes of this study were to measure the mortality and complication rates and to evaluate the 2- to 10-year clinical outcome of TKA in dialysis patients at our hospital during the past decade. METHODS: We retrospectively assessed 21 patients (26 knees) with ESRD who underwent primary TKA between 2007 and 2015. A preoperative medical evaluation was performed in all patients to assess the risk of surgery. All patients had complete clinical and radiographic evaluations, and the outcome was scored using American Knee Society Scores and the Western Ontario and McMaster Universities Arthritis Index. Perioperative complications and mortality were recorded. RESULTS: One patient died of stroke 1 year after surgery (4.8% mortality). The mean follow-up period of other 20 patients was 5.8 years (69.7 months, 24 to 119 months). Six patients (28.5%) had medical complications, including pneumonia (n = 3), stroke (n = 2), and cardiovascular events (n = 3), after discharge from hospital. At the latest follow-up, 19 patients (90.5%) had improved clinical outcomes of the knee after TKA according to the American Knee Society Scores (P < .01) and Western Ontario and McMaster Universities Arthritis Index scores (P < .01). CONCLUSION: Our study showed that TKA was a valid option for dialysis patients after careful preoperative evaluation. Most patients had an improved clinical outcome. There were no instances of prosthetic loosening or deep infection. However, dialysis patients under consideration for TKA need to be informed of the risk of possible medical complications due to the nature of ESRD.

Predictors of Treatment Failure After 2-Stage Reimplantation for Infected Total Knee Arthroplasty: A 2- to 10-Year Follow-Up.

BACKGROUND: The aim of this study is to identify risk factors which may lead to treatment failure following 2-stage reimplantation for chronic infected total knee arthroplasty (TKA). METHODS: We retrospectively reviewed 106 patients (108 knees) who underwent consecutive 2-stage revision for chronic PJI of the knee at our institution between January 2005 and December 2015. A total of 31 risk factors, including patient characteristics, comorbidities, surgical variables, and microbiology data, were collected. Kaplan-Meier survival and Cox regression analyses were used to calculate survival rates and adjusted hazard ratios (HRs) of treatment failure. RESULTS: Within the cohort, 16 of the 108 2-stage reimplantations (14.8%) had treatment failure. The treatment success for 2-stage reimplantation was 91% (95% confidence interval [CI] 0.8-1.0) at 2 years and 84% (95% CI 0.8-0.9) at 5 and 10 years. Multivariate analysis provided the strongest predictors of treatment failure, including body mass index ≥30 kg/m2 (adjusted HR 9.3, 95% CI 2.7-31.8, P < .001), operative time >4 hours (adjusted HR 11.3, 95% CI 3.9-33.1, P < .001), gout (adjusted HR 13.8, 95% CI 2.9-66.1, P = .001), and the presence of Enterococcus species during resection arthroplasty (adjusted HR 14.1, 95% CI 2.6-76.3, P = .002). CONCLUSION: Our study identified 4 potential risk factors that may predict treatment failure following 2-stage revision for chronic knee PJI. This finding may be useful when counseling patients regarding the treatment success and prognosis of 2-stage reimplantation for infected TKA.

MicroRNA-mediated interacting circuits predict hypoxia and inhibited osteogenesis of stem cells, and dysregulated angiogenesis are involved in osteonecrosis of the femoral head.

PURPOSE: MicroRNAs (miRNAs) are associated with various pathologic conditions and can serve as diagnostic or therapeutic biomarkers. This study tried to identify the differentially expressed miRNAs to predict the possible pathomechanisms involved in osteonecrosis of the femoral head (ONFH). METHODS: We compared the peripheral blood miRNAs in 46 patients with ONFH and 85 healthy controls by microarray and droplet digital polymerase chain reaction (ddPCR). Putative interacted networks between the differentially responded miRNAs were analyzed by web-based bioinformatics prediction tools. RESULTS: Microarray identified 51 differentially expressed miRNAs with at least twofold change (upregulation in 34 and downregulation in 17), and the results were validated by ddPCR using six selected miRNAs. Bioinformatics genetic network analysis focusing on the six miRNAs found the upregulated miR-18a and miR-19a are associated with angiogenesis after induction of ischemia; the upregulated miR-138-1 can inhibit osteogenic differentiation of mesenchymal stem cells; the most targeted genes, p53 and SERBP1, are associated with hypoxia and hypofibrinolysis. CONCLUSIONS: This study combined the miRNA analysis with the bioinformatics and predicts that hypoxia, inhibited osteogenesis of stem cells, and dysregulated angiogenesis might be orchestrated through the miRNA interacting circuits in the pathogenesis of ONFH.

The risk factors of failed reimplantation arthroplasty for periprosthetic hip infection.

BACKGROUND: Two-stage reimplantation arthroplasty is one of the standard treatments for chronic periprosthetic joint infection (PJI). Scanty data exist regarding the risk factors for failure after two-stage reimplantation for periprosthetic hip infection. The purpose of this study was to investigate and identify the risk factors associated with failure after two-stage reimplantation hip arthroplasty. METHODS: Sixty-two patients with hip PJI treated with a two-stage reimplantation protocol at our institution from 2005 to 2012 were reviewed. Patients requiring medical treatment or reoperation for recurrent infection were defined as treatment failure. A multivariate Cox proportional hazards model was used to analyze the risk factors associated with treatment failure. RESULTS: Of the 62 patients, 11 (17.7%) patients had developed reinfection after the two-stage reimplantation with a mean follow-up of 5.7 years. The implant survival was 82.2% (95% confidence interval [CI] 75.19-92.55) at 10 years. Multivariate analysis revealed BMI ≥30 kg/m2 (hazard ratio [HR] 9.16; 95% CI 1.51-55.3; p = 0.0158), liver cirrhosis (HR 6.39; 95% CI 1.09-37.4; p = 0.0398), gram-negative organism (HR 5.68; 95% CI 1.18-27.4; p = 0.0303), and presence of sinus tract (HR 18.2; 95% CI 2.15-153; p = 0.0077) as the independent risk factors for treatment failure. CONCLUSIONS: We found obesity, liver cirrhosis, gram-negative organism, and the presence of sinus tract were significantly related to the risks of failure after reimplantation arthroplasties.

Chronic Kidney Disease Is an Independent Risk Factor for Transfusion, Cardiovascular Complication, and Thirty-Day Readmission in Minimally Invasive Total Knee Arthroplasty.

BACKGROUND: Little is known about the relationship between chronic kidney disease (CKD) and minimally invasive total knee arthroplasty (MIS-TKA). We hypothesized that CKD was an independent risk factor for postoperative complications and increased blood transfusion in patients following MIS-TKA. METHODS: A retrospective review of a prospective database was conducted on patients who underwent MIS-TKAs at an academic medical center between 2009 and 2012. Glomerular filtration rates (GFRs) were calculated for each patient at the time of surgery and a CKD group of 205 patients (GFR < 60 mL/min) were matched at a ratio of 1:2 with 410 patients showing a GFR ≥ 60 mL/min (control group). There were no differences between the 2 groups regarding age, gender, body mass index, and American Society of Anesthesiologists grade. Patient characteristics, comorbidities, preoperative hemoglobin, calculated total blood loss, transfusion rate, length of stay, and postoperative complications were compared between the 2 groups. RESULTS: The CKD group had lower preoperative hemoglobin levels; higher preoperative comorbidities with cardiovascular disease, diabetes mellitus, and gout; longer length of stay; and higher total blood loss than the control group. Multivariate logistic regression showed that CKD was an independent risk factor for transfusions (odds ratio [OR] 7.6, 95% confidence interval [CI] 4.79-12.21, P < .001), cardiovascular complication (OR 5.5, 95% CI 1.68-9.39, P = .002), and 30-day readmission (OR 6.2, 95% CI 1.98-12.18, P = .005). CONCLUSION: Based on our data, CKD is an independent risk factor for blood transfusion, cardiovascular complication, and 30-day readmission in patients undergoing MIS-TKA.

Pipkin Type I and II femoral head fractures: internal fixation or excision?-from the hip arthroscopy perspective.

The treatment of patients with femoral head fractures with regard to fixation versus excision is controversial. This study aimed to compare the results of fixation and excision in hip arthroscopy-assisted surgery. This retrospective study included adult patients with femoral head fractures who were treated with hip arthroscopy surgery from March 2016 to April 2020, with a minimum follow-up of 24 months. The patients were divided into two groups: Group 1 (fixation group) and Group 2 (excision group). To compare the therapeutic effects between the two groups, clinical and radiographic outcomes, operative time, pain score, length of hospital stay after surgery and related complications were investigated. There were 13 (mean duration, 47.5 months; range, 24-72 months) and 8 (mean duration, 48.6 months; range, 26-74 months) patients in the fixation and excision groups, respectively. The excision group had better functional results than the fixation group in terms of the median modified Harris hip score (P = 0.009). No significant differences were observed in operative time, pain score or hospital stay after surgery between the two groups. Further, no osteonecrosis of the femoral head or traumatic arthritis occurred in either group. A piece of fracture fragment >2 cm can be considered for hip arthroscopy-assisted internal fixation, whereas the others can be removed. The excision group had better outcomes than the fixation group. Hence, hip arthroscopy-assisted internal fixation or excision of bony fragments led to satisfactory short-term clinical and radiological results for the treatment of Pipkin Type I and II femoral head fractures.

Decreased Ankyrin Expression Is Associated with Repressed eNOS Signaling, Cell Proliferation, and Osteogenic Differentiation in Osteonecrosis of the Femoral Head.

BACKGROUND: Reduced nitric oxide synthase (NOS) activity and decreased reparative potentials in stem cells may be involved in the pathogenesis of osteonecrosis of the femoral head (ONFH), but the underlying mechanism is not clear. Ankyrin, a cytoskeletal protein, can promote NOS expression and many cellular functions when it interacts with the CD44 receptors on the stem cells. This study investigated whether ankyrin is involved in the pathogenesis of ONFH. MATERIALS AND METHODS: Bone marrow stem cells (BMSCs) from ONFH patients were compared with cells from patients with proximal femoral fracture and BMSC cell lines (PT-2501, Lonza, NC, USA). Differences in the expression levels and downstream signal pathway of ankyrin-Akt-eNOS in BMSCs were studied between ONFH and control. The involvement of ankyrin in the signal cascade, cell proliferation, and differentiation were further investigated by silencing ankyrin using small interfering (si)RNA. RESULTS: We found the basal mRNA levels of ankyrin and CD44 in BMSCs from the ONFH group were significantly lower as compared with those from the control group. The signal transduction of CD44-ankyrin-Akt-eNOS was significantly repressed in the ONFH group as compared with the control group after hyaluronic acid treatment. Knockdown of ankyrin by siRNA could attenuate the eNOS signaling as well as the BMSCs proliferation and osteogenic differentiation. The proliferation ability and osteogenic differentiation potential of the BMSCs from the ONFH group were significantly reduced as compared with the control group, but they can be enhanced to the baseline levels of the control group by hyaluronic acid treatment. CONCLUSION: The aberrant eNOS signaling, reduced cell proliferation, and osteogenic differentiation potential in BMSCs from ONFH patients are associated with the decreased ankyrin expression. CLINICAL RELEVANCE: Altered signal transduction, proliferation, and osteogenic differentiation ability in BMSCs may be involved in the pathogenesis of ONFH. These need further studies especially in BMSC-based cell therapy.

Does preoperative dipyridamole-thallium scanning reduce 90-day cardiac complications and 1-year mortality in patients with femoral neck fractures undergoing hemiarthroplasty?

BACKGROUND: This study aimed to evaluate the effect of dipyridamole-thallium scanning (DTS) on the rates of 90-day cardiac complications and 1-year mortality in patients with a femoral neck fracture treated with hemiarthroplasty. METHODS: Between 2008 and 2015, 844 consecutive patients who underwent cemented or cementless hemiarthroplasty were identified from the database of a single level-one medical center. One-hundred and thirteen patients (13%) underwent DTS prior to surgery, and 731 patients (87%) did not. Patient characteristics, comorbidities, surgical variables, and length of the delay until surgery were recorded. A propensity score-matched cohort was utilized to reduce recruitment bias in a 1:3 ratio of DTS group to control group, and multivariate logistic regression was performed to control confounding variables. RESULTS: The incidence of 90-day cardiac complications was 19.5% in the DTS group and 15.6% in the control group (p = 0.343) among 452 patients after propensity score-matching. The 1-year mortality rate (10.6% vs 13.3%, p = 0.462) was similar in the two groups. In the propensity score-matched patients, utilization of DTS was not associated with a reduction in the rate of 90-day cardiac complications (matched cohort, adjusted odds ratio [aOR] = 1.32; 95% confidence interval [CI] 0.75-2.33, p = 0.332) or the 1-year mortality rate (aOR = 0.62; 95% CI 0.27-1.42, p = 0.259). Risk factors for cardiac complications included an American Society of Anesthesiologists grade ≥ 3 (OR 3.19, 95% CI 1.44-7.08, p = 0.004) and pre-existing cardiac comorbidities (OR 5.56, 95% CI 3.35-9.25, p < 0.001). Risk factors for 1-year mortality were a long time to surgery (aOR 1.15, 95% CI 1.06-1.25, p = 0.001), a greater age (aOR 1.05, 95% CI 1.00 to 1.10, p = 0.040), a low body mass index (BMI; aOR 0.89, 95% CI 0.81-0.98, p = 0.015), and the presence of renal disease (aOR 4.43, 95% CI 1.71-11.46, p = 0.002). DISCUSSION: Preoperative DTS was not associated with reductions in the rates of 90-day cardiac complications or 1-year mortality in patients with a femoral neck fracture undergoing hemiarthroplasty. The necessity for DTS should be re-evaluated in elderly patients with femoral neck fractures, given that this increases the length of the delay until surgery. LEVEL OF EVIDENCE: Prognostic level III.

Hip arthroscopy-assisted reduction and fixation for femoral head fracture dislocations: Clinical and radiographic short-term results of seven cases.

PURPOSE: Femoral head fracture dislocations are serious articular fractures that are associated with soft tissue injuries and are challenging to treat. Arthroscopic surgery may be a way to treat fracture reduction and fixation, thereby avoiding the need for extensive arthrotomy. METHODS: We followed up a consecutive series of seven patients with femoral head fracture dislocation via a scope-assisted percutaneous headless screw fixation between 2016 and 2017. The clinical and radiological results were assessed. RESULTS: The locations of the fracture were all involving infra-foveal area. The mean follow-up duration was 18 (range 12-24) months. The mean Harris hip score was 90.8 (range 88-93) at the latest follow-up. None of the patients showed early osteoarthritis, heterotopic ossification, or avascular necrosis. The average maximal displacement of the fracture site was improved from preoperative 6.79 mm (range 4.21-12.32) to postoperative 2.76 mm (range 0.97-3.97). Concomitant intra-articular hip lesions secondary to traumatic hip dislocation can also be treated. CONCLUSION: Managing the infra-foveal fracture of the femoral head using arthroscopic reduction and fixation with headless screws can be a safe and minimally invasive option. More patients and longer follow-up are needed for a definite conclusion.

Treatment of cam-type femoroacetabular impingement using anterolateral mini-open and arthroscopic osteochondroplasty.

BACKGROUND: Femoroacetabular impingement (FAI) is associated with decreased hip function and early hip osteoarthritis. Surgical treatment is often required to halt the process of mechanical degeneration. The study investigated the short-to-midterm results of using a modified anterolateral mini-open and arthroscopic osteochondroplasty in the treatment of cam-type FAI. METHODS: Thirty-six patients (39 hips), with the mean age of 43.6 years, who had cam-type FAI, were operated by a mini-open and arthroscopy-assisted osteochondroplasty via the Watson-Jones interval between 2002 and 2016. Radiographic parameters and Harris hip scores were retrospectively analyzed after a mean follow-up of 44 months. RESULTS: Of the 39 hips, the mean Harris hip score significantly improved from 61.1 preoperatively to 84.2 postoperatively (P < 0.01). There were nine hips (23%) undergoing total hip arthroplasty (THA) at a mean of 22 months (range, 3~64 months) due to progression of hip osteoarthritis. The 5-year survival for hip preserving was 74.9%. Cox proportional-hazards model showed that age ≥ 55 years (P = 0.03) and preoperative Tönnis stage II (P = 0.02) were independent risk factors for conversion to THA. CONCLUSIONS: The mini-open and arthroscopic approach allowed direct visualization and improved quality of the osteochondroplasty of FAI hip while avoiding the need for surgical dislocation. This technique could be a safe and viable option for symptomatic cam-type FAI patients to relieve symptoms and improve hip function.

Correction to: Treatment of cam-type femoroacetabular impingement using anterolateral mini-open and arthroscopic osteochondroplasty.

In the original publication of this article [1], the first name of the 5th author is wrong.

Isolated revision of the acetabular component using alumina-on-alumina bearings without a metal sleeve: A preliminary study.

INTRODUCTION: There has been a debate on the use of ceramic-on-ceramic coupling with the retained femoral stem in isolated acetabular revision. The purpose of this study was to retrospectively review the results and complications of isolated revision of the acetabular component using alumina-on-alumina bearings. METHODS: Between August 2010 and December 2013, 22 patients (23 hips) with a mean age of 60.74 years (40-73) underwent isolated revision of the acetabular component from metal-on-polyethylene to alumina-on-alumina bearings without using a metal sleeve on the undamaged trunnion. All patients completed clinical and radiographic evaluation. RESULTS: At a mean follow-up of 3 years (2-5.5), all patients had a significant improvement in the clinical outcome, including Harris Hip Score (84.9 vs. 43, p < 0.001), West Ontario McMaster University Osteoarthritis Index Score (14.4 vs. 49.2, p < 0.001), and visual analogue pain score (1.42 vs. 6.63, p < 0.001). Complications included one aseptic loosening of the acetabular component and three noisy hips (click only). No fracture of the ceramic bearings, dislocation, infection, or squeaking noise were observed in any of the patients. CONCLUSION: Isolated revision of the acetabular component to alumina-on-alumina bearings on the undamaged trunnion may be considered if there is no available titanium sleeves. Our study showed a satisfactory early outcome with minimal complications. However, a longer term follow-up study is necessary.

No benefit on functional outcomes and dislocation rates by increasing head size to 36 mm in ceramic-on-ceramic total hip arthroplasty.

BACKGROUND: Ceramic-on-ceramic (COC) total hip arthroplasty (THA) has gained popularity since improvements in wear characteristics and longevity. Whether large ceramic femoral heads (≥36 mm) have increased postoperative range of motion (ROM) and a lower dislocation rate is not clear. This study aimed to compare functional outcomes and early complications between large-head (≥36 mm) and smaller-head (≤32 mm) COC prostheses with a minimum follow-up of 12 months. METHODS: A total of 95 consecutive uncemented COC THAs were performed in 90 patients between January 2012 and July 2013. Of these, 49 patients (smaller-head group) received third generation and 41 patients (large-head group) received fourth generation COC prostheses. Harris hip score (HHS), Western Ontario and McMaster Universities Arthritis index (WOMAC), and ROM of the hip pre- and post-operatively were compared, as well as the presence of early complications. RESULTS: Postoperative HHSs (88.4 vs. 89.3, p = 0.34) and WOMAC scores (12.0 vs. 11.0, p = 0.111) were not different between the groups. Postoperative flexion ROM was lower in the smaller-head group (98.8° vs. 106.1°, p < 0.001), but there were no differences in extension, abduction, adduction, internal rotation, and external rotation. One patient in each group reported a grinding noise. There was one dislocation (1.9%) in the smaller-head group, and none in the large-head group (p = 0.371). No infections or loosening of the components occurred. CONCLUSIONS: Large-head COC articulation provided better flexion, but functional outcomes and early complications are similar to the smaller-head COC.