Cementless Total Knee Arthroplasty: Is it Safe in Demineralized Bone?

There is concern for cementless total knee arthroplasty (TKA) in patients with decreased bone mineral density (BMD) due to the potential increase in complications, namely failed in-growth or future aseptic loosening. Some data suggest that advances in cementless prostheses mitigate these risks; however this is not yet born out in long-term registry data. It is crucial to expand our understanding of the prevalence and etiology of osteoporosis in TKA patients, survivorship of cementless implants in decreased BMD, role of bone-modifying agents, indications and technical considerations for cementless TKA in patients with decreased BMD. The purpose of this study is to review current literature and expert opinion on such topics.

Novel Technique for the Identification of Hip Implants Using Artificial Intelligence

BACKGROUND

The anticipated growth of total hip arthroplasty will result in an increased need for revision total hip arthroplasty. Preoperative planning, including identifying current implants, is critical for successful revision surgery. Artificial intelligence (AI) is promising for aiding clinical decision-making, including hip implant identification. However, previous studies have limitations such as small datasets, dissimilar stem designs, limited scalability, and the need for AI expertise. To address these limitations, we developed a novel technique to generate large datasets, tested radiographically similar stems, and demonstrated scalability utilizing a no-code machine learning solution.

METHODS

We trained, validated, and tested an automated machine learning-implemented convolutional neural network to classify 9 radiographically similar femoral implants with a metaphyseal-fitting wedge taper design. Our novel technique uses computed tomography-derived projections of a 3-dimensional scanned implant model superimposed within a computed tomography pelvis volume. We employed computer-aided design modeling and MATLAB to process and manipulate the images. This generated 27,020 images for training (22,957) and validation (4,063) sets. We obtained 786 test images from various sources. The performance of the model was evaluated by calculating sensitivity, specificity, and accuracy.

RESULTS

Our machine learning model discriminated the 9 implant models with a mean accuracy of 97.4%, sensitivity of 88.4%, and specificity of 98.5%.

CONCLUSIONS

Our novel hip implant detection technique accurately identified 9 radiographically similar implants. The method generates large datasets, is scalable, and can include historic or obscure implants. The no-code machine learning model demonstrates the feasibility of obtaining meaningful results without AI expertise, encouraging further research in this area.

Recurrent Periprosthetic Joint Infections: Diagnosis, Management, and Outcomes

Periprosthetic joint infection (PJI) remains one of the most common complications after total joint arthroplasty. It is challenging to manage, associated with significant morbidity and mortality, and is a financial burden on the health care system. Failure of 2-stage management for chronic PJI is not uncommon. Repeat infections are oftentimes polymicrobial, multiple drug-resistant microorganisms, or new organisms. Optimizing the success of index 2-stage revision is the greatest prevention against failure of any subsequent management options and requires a robust team-based approach.

Assessing the Diagnostic Accuracy of Next-Generation Sequencing in Patients With Antibiotic Spacers Before Reimplantation

Use of molecular sequencing modalities in periprosthetic joint infection diagnosis and organism identification has gained popularity recently. To date, there is no diagnostic test that reliably predicts infection eradication in patients with antibiotic spacers. The purpose of this study was to compare the diagnostic accuracy of next-generation sequencing (NGS), culture, the Musculoskeletal Infection Society (MSIS) criteria, and the criteria by Parvizi et al in patients with antibiotic spacers. In this retrospective study, aspirate or tissue samples were collected from 38 knee and 19 hip antibiotic spacers for routine diagnostic workup for the presence of persistent infection and sent to the laboratory for NGS. The kappa statistic along with statistical differences between diagnostic studies were calculated using the chi-square test for categorical data. The kappa coefficient for agreement between NGS and culture was 0.27 (fair agreement). The percentages of positive and negative agreement were 22.8% and 42.1%, respectively, with a total concordance of 64.9%. There were 12 samples that were culture positive and NGS negative. Eight samples were NGS positive but culture negative. The kappa coefficient was 0.42 (moderate agreement) when comparing NGS with MSIS criteria. In our series, NGS did not provide sufficient agreement compared with culture or MSIS criteria in the setting of an antibiotic spacer. A reliable diagnostic indicator for reimplantation has yet to be identified. [Orthopedics. 2024;47(1);46-51.].

The Challenge of Emerging Resistant Gram-Positive Pathogens in Hip and Knee Periprosthetic Joint Infections

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An increase in resistant bacterial pathogens has occurred over the last 4 decades.

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Careful patient selection and improving or correcting risk factors for periprosthetic joint infection (PJI) before elective surgical treatment are strongly recommended.

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Appropriate microbiological methods, including those used to detect and grow Cutibacterium acnes, are recommended.

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Antimicrobial agents used in the prevention or management of infection should be selected appropriately and the duration of therapy should be carefully considered in order to mitigate the risk of developing bacterial resistance.

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Molecular methods including rapid polymerase chain reaction (PCR) diagnostics, 16S sequencing, and/or shotgun and/or targeted whole-genome sequencing are recommended in culture-negative cases of PJI.

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Expert consultation with an infectious diseases specialist (if available) is recommended to assist with the appropriate antimicrobial management and monitoring of patients with PJI.

Obturator Anterior Dislocation After Direct Anterior Total Hip Arthroplasty in a Patient with Ehlers-Danlos Syndrome: A Case Report

CASE

A 71-year-old woman with Ehlers-Danlos syndrome suffered an atraumatic obturator dislocation status post direct anterior total hip arthroplasty. A closed reduction under conscious sedation was attempted, but was unsuccessful. Repeat closed reduction under full general anesthesia with paralysis and fluoroscopic guidance was successful at reducing the femoral prosthesis out of the pelvis and back into an appropriate position.

CONCLUSION

Atraumatic obturator dislocations after total hip arthroplasty are exceedingly rare. General anesthesia with full paralysis is helpful for a successful closed reduction, and open reduction may be necessary to remove the femoral prosthesis from the pelvis.

Increased Incidence of Methicillin-Resistant Staphylococcus aureus in Knee and Hip Prosthetic Joint Infection

BACKGROUND

Periprosthetic joint infection (PJI) is a devastating complication of knee and hip arthroplasty. Past literature has shown that gram-positive bacteria are commonly responsible for these infections, although limited research exists studying the changes in the microbial profile of PJIs over time. This study sought to analyze the incidence and trends of pathogens responsible for PJI over three decades.

METHODS

This is a multi-institutional retrospective review of patients who had a knee or hip PJI from 1990 to 2020. Patients with a known causative organism were included and those with insufficient culture sensitivity data were excluded. There were 731 eligible joint infections from 715 patients identified. Organisms were divided into multiple categories based on genus/species and 5-year increments were used to analyze the study period. The Cochran-Armitage trend tests were used to evaluate linear trends in microbial profile over time and a P-value <.05 was considered statistically significant.

RESULTS

There was a statistically significant positive linear trend in the incidence of methicillin-resistant Staphylococcus aureus over time (P = .0088) as well as a statistically significant negative linear trend in the incidence of coagulase-negative staphylococci over time (P = .0018). There was no statistical significance between organism and affected joint (knee/hip).

CONCLUSION

The incidence of methicillin-resistant Staphylococcus aureus PJI is increasing over time, whereas, coagulase-negative staphylococci PJI is decreasing, paralleling the global trend of antibiotic resistance. Identifying these trends may help with the prevention and treatment of PJI through methods such as remodeling perioperative protocols, modifying prophylactic/empiric antimicrobial approaches, or transitioning to alternative therapeutic strategies.

Predictors of Reinfection in Prosthetic Joint Infections Following Two-Stage Reimplantation

BACKGROUND

Two-stage reimplantation is an effective treatment for periprosthetic joint infection (PJI). Many factors are involved in the variable success of this procedure. The purpose of this study is to examine the relationship between patient risk factors, comorbidities, and the pathogen on reinfection rates following two-stage reimplantation.

METHODS

We evaluated 158 patients treated for PJI from 2008-2019. Only patients who had completed a two-stage exchange were included. Patient demographics, comorbidities, laboratory values, time-to-reimplantation, pathogen, antibiotic sensitivities, host status, and reinfection rates were assessed. Multivariate analysis was performed to identify correlation between risk factors and reinfection. A P-value < .05 was considered statistically significant.

RESULTS

31 patients experienced a reinfection (19.6%). There was a statistically significant association between infection with Methicillin Sensitive Staphylococcus Aureus (MSSA) and reinfection (P = .046). Patients with a reinfection also had a significantly greater median serum C-reactive protein (CRP) level (12.65 g/dL) at the time of diagnosis compared to patients without a reinfection (5.0 g/dL) (P = .010). Median Erythrocyte Sedimentation Rate (ESR) (56 in no re-infection and 69 in re-infection) and time-to-reimplantation (101 days in no reinfection and 141 days in reinfection) demonstrated a trend toward an association with re-infection but were not statistically significant (P = .055 and P = .054 respectively).

CONCLUSION

As the number of arthroplasties continue to rise, PJIs are increasing proportionately and represent a significant revision burden. Elevated C-reactive protein (CRP) levels and Methicillin Sensitive Staphylococcus aureus (MSSA) infection were strongly associated with failure of a two-stage reimplantation. While not statistically significant with our numbers, there were strong trends toward an association between elevated Erythrocyte Sedimentation Rate (ESR), longer time-to-reimplantation, and reinfection.

Long Term Results of Two-Stage Revision for Chronic Periprosthetic Knee Infection: A Multicenter Study

BACKGROUND

Long-term reinfection and mortality rates and clinical outcomes with sufficient subject numbers remain limited for patients undergoing two-stage exchange arthroplasty for chronic periprosthetic knee infections. The purpose of this study was to determine the long-term reinfection, complication, and mortality following reimplantation for two-stage exchange following knee arthroplasty.

METHODS

Retrospective review of 178 patients who underwent two-stage exchange knee arthroplasty for chronic PJI at three large tertiary referral institutions with an average of 6.63-year follow-up from reimplantation from 1990 to 2015. Rates of reinfection, mortality, and all-cause revision were calculated along with the cumulative incidence of reinfection with death as a competing factor. Risk factors for reinfection were determined using Cox multivariate regression analysis.

RESULTS

Overall rate of infection eradication was 85.41%, with a mortality rate of 30.33%. Patients with minimum 5-year follow-up (n = 118, average 8.32 years) had an infection eradication rate of 88.98%, with a mortality rate of 33.05%.

CONCLUSION

This is a large series with long-term follow-up evaluating outcomes of two-stage exchange knee arthroplasty resulting in adequate infection eradication and high mortality. Results were maintained at longer follow-up. This technique should be considered in patients with chronic PJI; however, realistic expectations regarding long-term outcomes must be discussed with patients.

Long Term Results of Two-Stage Revision for Chronic Periprosthetic Hip Infection: A Multicenter Study

BACKGROUND

Two-stage exchange arthroplasty remains the gold standard in the United States for treatment of chronic periprosthetic joint infection (PJI). Long-term reinfection rates and clinical outcomes with sufficient subject numbers remain limited. The purpose was to evaluate the long-term outcomes following two-stage exchange following hip arthroplasty.

METHODS

Retrospective review of 221 patients who underwent two-stage exchange hip arthroplasty for chronic PJI at three large tertiary referral institutions from 1990-2015. Outcomes including reinfection, mortality, and all-cause revision were calculated. Cumulative incidence of reinfection with death as competing factor was also calculated. Risk factors for reinfection were determined using Cox multivariate regression analysis.

RESULTS

Rate of infection eradication and all-cause revision was 88.24% and 22.6%, respectively. Overall mortality rate was 40.72%. Patients with minimum five-year follow-up (n = 129) had a success rate of 91.47% with mortality rate of 41.1%. Major risk factors for reinfection included polymicrobial infection (HR = 2.36, 95% CI: 1.08-5.14) and antibiotic resistant organism (HR = 2.36, 95% CI: 1.10-5.04).

CONCLUSION

This is the largest series with greater than 5-year follow-up evaluating outcomes of two-stage exchange hip arthroplasty. This technique resulted in a relatively high infection eradication, however, the mortality rate is alarmingly high. Antibiotic resistant organisms appear to be highest risk factor for failure.

Total hip arthroplasty using highly cross-linked polyethylene in patients aged 50 years and younger : minimum 15-year follow-up

AIMS

Highly cross-linked polyethylene (HXLPE) has greatly improved the durability of total hip arthroplasty (THA) in young patients because of its improved wear characteristics. Few studies have followed this population into the second decade, and therefore the purpose of this investigation was to evaluate the clinical outcome for THA patients 50 years of age and younger at a minimum of 15 years postoperatively. The second purpose was to evaluate the radiological findings secondary to wear or mechanical failure of the implant.

METHODS

Between October 1999 and December 2005, 105 THAs were performed in 95 patients (53 female, 42 male) aged 50 years and younger (mean 42 years (20 to 50)). There were 87 patients (96 hips) that were followed for a minimum of 15 years (mean 17.3 years (15 to 21)) for analysis. Posterior approach was used with cementless fixation with a median head size of 28 mm. HXLPE was the acetabular bearing for all hips. Radiographs were evaluated for polyethylene wear, radiolucent lines, and osteolysis.

RESULTS

Clinical outcomes showed significant improvement of mean Harris Hip Scores from 52.8 (SD 13.5) preoperatively to 94.8 (SD 7.6) postoperatively. One hip was revised for recurrent instability, and there were no infections. No hips were revised for mechanical loosening or osteolysis. Mean polyethylene linear wear was 0.04 mm/year and volumetric wear was 6.22 mm³/year, with no significant differences between head size or material. Osteolysis was not present in any of the hips.

CONCLUSION

The use of HXLPE in THA for patients aged 50 years and younger has performed exceptionally well without evidence of significant wear causing mechanical loosening or necessitating revision. The radiolucent lines of the acetabular component must be followed to determine the prognostic significance. This investigation represents the longest clinical follow-up of a large, consecutive cohort of patients aged 50 years or younger with THA using HXLPE. This long-term analysis found negligible polyethylene wear, no incidence of aseptic loosening, and excellent clinical outcomes at and beyond 15 years of follow-up. Cite this article: Bone Joint J 2021;103-B(7 Supple B):78-83.

Comparison of 3D Printed Spherical Implants versus Femoral Head Allografts for Tibiotalocalcaneal Arthrodesis

Successful tibiotalocalcaneal (TTC) arthrodesis can be difficult to achieve in patients with bulk bone defects even with the use of femoral head allograft. Retrograde intramedullary nail placement through custom 3-dimensional (3D) spherical implants is an innovative option for these patients. The purpose of this study was to compare fusion rates, graft resorption, and complication rates between patients undergoing TTC fusion with 3D sphere implants versus femoral head allografts. Patients who underwent TTC arthrodesis with an intramedullary nail along with a 3D spherical implant (n = 8) or femoral head allograft (n = 7) were included in this study. The rate of successful fusion of the tibia, calcaneus, and talar neck to the 3D sphere or femoral head allograft was compared between the groups. The rate of total fused articulations was significantly higher in the 3D sphere group (92%) than the femoral head allograft group (62%; p = .018). The number of patients achieving successful fusion of all 3 articulations was higher in the 3D sphere group (75%) than the femoral head allograft group (42.9%, p = .22). The rate of graft resorption was significantly higher in the femoral head allograft group (57.1%) than the 3D sphere group (0%, p = .016). There were no significant differences between the groups in terms of complications. These data demonstrate that the use of a custom 3D printed sphere implant is safe in patients with severe bone loss undergoing TTC arthrodesis with a retrograde intramedullary nail and may result in improved rates of successful arthrodesis.

Results of debridement, antibiotics, and implant retention for periprosthetic knee joint infection supplemented with the use of intraosseous antibiotics

AIMS

Debridement, antibiotics, and implant retention (DAIR) remains one option for the treatment of acute periprosthetic joint infection (PJI) despite imperfect success rates. Intraosseous (IO) administration of vancomycin results in significantly increased local bone and tissue concentrations compared to systemic antibiotics alone. The purpose of this study was to evaluate if the addition of a single dose of IO regional antibiotics to our protocol at the time of DAIR would improve outcomes.

METHODS

A retrospective case series of 35 PJI TKA patients, with a median age of 67 years (interquartile range (IQR) 61 to 75), who underwent DAIR combined with IO vancomycin (500 mg), was performed with minimum 12 months' follow-up. A total of 26 patients with primary implants were treated for acute perioperative or acute haematogenous infections. Additionally, nine patients were treated for chronic infections with components that were considered unresectable. Primary outcome was defined by no reoperations for infection, nor clinical signs or symptoms of PJI.

RESULTS

Mean follow-up for acute infection was 16.5 months (12.1 to 24.2) and 15.8 months (12 to 24.8) for chronic infections with unresectable components. Overall non-recurrence rates for acute infection was 92.3% (24/26) but only 44.4% (4/9) for chronic infections with unresectable components. The majority of patients remained on suppressive oral antibiotics. Musculoskeletal Infection Society (MSIS) host grade was a significant indicator of failure (p < 0.001).

CONCLUSION

The addition of IO vancomycin at the time of DAIR was shown to be safe with improved results compared to current literature using standard DAIR without IO antibiotic administration. Use of this technique in chronic infections should be applied with caution. While these results are encouraging, this technique requires longer follow-up before widespread adoption. Cite this article: Bone Joint J 2021;103-B(6 Supple A):185-190.

Next-generation sequencing not superior to culture in periprosthetic joint infection diagnosis

AIMS

Use of molecular sequencing methods in periprosthetic joint infection (PJI) diagnosis and organism identification have gained popularity. Next-generation sequencing (NGS) is a potentially powerful tool that is now commercially available. The purpose of this study was to compare the diagnostic accuracy of NGS, polymerase chain reaction (PCR), conventional culture, the Musculoskeletal Infection Society (MSIS) criteria, and the recently proposed criteria by Parvizi et al in the diagnosis of PJI.

METHODS

In this retrospective study, aspirates or tissue samples were collected in 30 revision and 86 primary arthroplasties for routine diagnostic investigation for PJI and sent to the laboratory for NGS and PCR. Concordance along with statistical differences between diagnostic studies were calculated.

RESULTS

Using the MSIS criteria to diagnose PJI as the reference standard, the sensitivity and specificity of NGS were 60.9% and 89.9%, respectively, while culture resulted in sensitivity of 76.9% and specificity of 95.3%. PCR had a low sensitivity of 18.4%. There was no significant difference based on sample collection method (tissue swab or synovial fluid) (p = 0.760). There were 11 samples that were culture-positive and NGS-negative, of which eight met MSIS criteria for diagnosing infection.

CONCLUSION

In our series, NGS did not provide superior sensitivity or specificity results compared to culture. PCR has little utility as a standalone test for PJI diagnosis with a sensitivity of only 18.4%. Currently, several laboratory tests for PJI diagnosis should be obtained along with the overall clinical picture to help guide decision-making for PJI treatment. Cite this article: Bone Joint J 2021;103-B(1):26-31.

Commercially Available Polymerase Chain Reaction Has Minimal Utility in the Diagnosis of Periprosthetic Joint Infection

The use of genetic sequencing modalities in the diagnosis of periprosthetic joint infection (PJI) and the identification of organisms has gained popularity recently. Polymerase chain reaction (PCR) offers timely results for common organisms. The purpose of this study was to compare the accuracy of broad-range PCR, conventional culture, the Musculoskeletal Infection Society (MSIS) criteria, and the recently proposed criteria by Parvizi et al in the diagnosis of PJI. In this retrospective study, aspirate or tissue samples were collected in 104 revision and 86 primary arthroplasties for routine diagnostic workup for PJI and sent to the laboratory for PCR. Concordance along with statistical differences between diagnostic studies were calculated using chi-square test for categorical data. On comparison with the MSIS criteria, concordance was significantly lower for PCR at 64.7% compared with 86.3% for culture (P<.001). There was no significant difference based on diagnosis of prior infection (P=.706) or sample collection method (tissue swab or synovial fluid) (P=.316). Of the 87 patients who met MSIS criteria, only 20 (23.0%) PCR samples had an organism identified. In this series, PCR had little utility as a stand-alone test for the diagnosis of PJI, with a sensitivity of only 23.0% when using MSIS criteria as the gold standard. Polymerase chain reaction also appears to be significantly less accurate than culture in the diagnosis of PJI. Currently, several laboratory tests used for either criteria for PJI diagnosis should be obtained along with the overall clinical picture to help guide decision-making for PJI treatment. [Orthopedics. 2020;43(6):333-338.].

Comparison of Tibiotalocalcaneal Arthrodeses Using a Sustained Dynamic Compression Nail Versus Nondynamized Nails

Background. Tibiotalocalcaneal (TTC) arthrodesis is a common treatment option for hindfoot arthritis and deformity. Loss of compression over time with statically locked nails may contribute to nonunion. A novel retrograde intramedullary nail with an internal pseudoelastic component has recently been used to provide sustained dynamic compression (SDC). The purpose of this study was to compare fusion rates and time to union between the SDC and nondynamized (ND) nails. Methods. All patients who underwent TTC arthrodesis with an intramedullary nail at a single institution from 2013 to 2017 and who had at least 1 year of follow-up were included in this study. Baseline patient and operative characteristics were collected and compared between the sustained SDC and ND nail groups. The rate of successful fusion, time to union, and complications were compared between the groups. Results. The SDC cohort had a significantly faster time to union by 3.9 months (P = .049). The SDC cohort had a higher fusion rate (78.0%) compared with the ND nail cohort (75.0%), although this was not statistically significant (P = .75). The SDC nail was used significantly (P < .05) more often in patients with known risk factors for nonunion, including female sex, smoking, revision surgery, prior trauma, and patients requiring 3D cage implants for significant bone loss. There were no differences between the groups in terms of complications. Conclusion. The SDC nail has been shown to achieve successful arthrodesis in a population at high risk for nonunion, using less hardware, and at a faster rate than ND nails. Level of Evidence: Level III: Retrospective, comparative study.

Single vs 2-Stage Revision for the Treatment of Periprosthetic Joint Infection

Periprosthetic joint infection (PJI) is one of the most devastating complications following total joint arthroplasty, accounting for a projected 10,000 revision surgeries per year by 2030. Chronic PJI is complicated by the presence of bacterial biofilm, requiring removal of components, thorough debridement, and administration of antibiotics for effective eradication. Chronic PJI is currently managed with single-stage or 2-stage revision surgery. To date, there are no randomized, prospective studies available evaluating eradication rates and functional outcomes between the 2 techniques. In this review, both treatment options are described with the most current literature to guide effective surgical decision-making that is cost-effective while decreasing patient morbidity.

Prior Hip Arthroscopy Increases Risk for Perioperative Total Hip Arthroplasty Complications: A Matched-Controlled Study

BACKGROUND

Arthroscopic hip surgery is becoming increasingly popular for the treatment of femoroacetabular impingement and labral tears. Reports of outcomes of hip arthroscopy converted to total hip arthroplasty (THA) have been limited by small sample sizes. The purpose of this study was to investigate the impact of prior hip arthroscopy on THA complications.

METHODS

We queried our institutional database from January 2005 and December 2017 and identified 95 hip arthroscopy conversion THAs. A control cohort of 95 primary THA patients was matched by age, gender, and American Society of Anesthesiologists score. Patients were excluded if they had undergone open surgery on the ipsilateral hip. Intraoperative complications, estimated blood loss, operative time, postoperative complications, and need for revision were analyzed. Two separate analyses were performed. The first being intraoperative and immediate postoperative complications through 90-day follow-up and a second separate subanalysis of long-term outcomes on patients with minimum 2-year follow-up.

RESULTS

Average time from hip arthroscopy to THA was 29 months (range 2-153). Compared with primary THA controls, conversion patients had longer OR times (122 vs 103 minutes, P = .003). Conversion patients had a higher risk of any intraoperative complication (P = .043) and any postoperative complication (P = .007), with a higher rate of wound complications seen in conversion patients. There was not an increased risk of transfusion (P = .360), infection (P = 1.000), or periprosthetic fracture between groups (P = .150). When comparing THA approaches independent of primary or conversion surgery, there was no difference in intraoperative or postoperative complications (P = .500 and P = .790, respectively).

CONCLUSION

Conversion of prior hip arthroscopy to THA, compared with primary THA, resulted in increased surgical times and increased intraoperative and postoperative complications. Patients should be counseled about the potential increased risks associated with conversion THA after prior hip arthroscopy.

Anatomic Magnetic Resonance Imaging Measurements in First-Time Patellar Dislocators by Sex and Age

CONTEXT

Anatomic differences of the knee in first-time patellar dislocators have not been clearly elucidated.

OBJECTIVE

To compare structural differences of the knee in those who have sustained an acute first-time patellar dislocation resulting in a medial patellofemoral ligament (MPFL) tear by sex and age (≤17 years old, ≥18 years old).

DESIGN

Case series.

SETTING

Retrospective magnetic resonance imaging analysis.

PATIENTS OR OTHER PARTICIPANTS

Thirty-five acute first-time patellar dislocators with an associated MPFL tear.

MAIN OUTCOME MEASURE(S)

Patellar height using 3 methods, patellar alignment using congruency angles, and trochlear morphology using the sulcus angle. We compared the means of these variables by sex and age. The intraclass correlation coefficient was then calculated to assess the agreement of the independent reviewers.

RESULTS

A total of 21 left and 14 right knees were analyzed. The MPFL tear location did not differ by sex (P = .34) or age (P = .43). Patellar height did not differ as measured by the Caton-Deschamps ratio (P = .29 for sex, P = .49 for age), Insall-Salvati index (P = .15 for sex, P = .33 for age), or patellotrochlear index (P = .67 for sex, P = .49 for age). The congruence angle (P = .81 for sex, P = .06 for age) and trochlear morphology as measured by the sulcus angle (P = .64 for sex, P = .45 for age) were similar between groups.

CONCLUSIONS

Patellar height and trochlear morphology did not differ by sex or age among patients whose first-time patellar dislocations resulted in an MPFL tear. In addition, the location of the tear did not appear to vary by sex or age.

Traditional Laboratory Markers Hold Low Diagnostic Utility for Immunosuppressed Patients With Periprosthetic Joint Infections

BACKGROUND

Although predictive laboratory markers and cutoffs for immunocompetent patients are well-studied, similar reference ranges and decision thresholds for immunosuppressed patients are less understood. We investigated the utility of typical laboratory markers in immunosuppressed patients undergoing aspiration of a prosthetic hip or knee joint.

METHODS

A retrospective review of adult patients with an immunosuppressed state that underwent primary and revision total joint arthroplasty with a subsequent infection at our tertiary, academic institution was conducted. Infection was defined by Musculoskeletal Infection Society criteria. A multivariable analysis was used to identify independent factors associated with acute (<90 days) and chronic (>90 days) infection. Area under the receiver-operator curve (AUC) was used to determine the best supported laboratory cut points for identifying infection.

RESULTS

We identified 90 patients with immunosuppression states totaling 172 aspirations. Mean follow-up from aspiration was 33 months. In a multivariate analysis, only synovial fluid cell count and synovial percent neutrophils were found to be independently correlated with both acute and chronic infection. A synovial fluid cell count cutoff value of 5679 nucleated cells/mm³ maximized the AUC (0.839) for predicting acute infection, while a synovial fluid cell count cutoff value of 1293 nucleated cells/mm³ maximized the AUC (0.931) for predicting chronic infection.

CONCLUSION

Physicians should be aware of lower levels of synovial nucleated cell count and percentage of neutrophils in prosthetic joint infections of the hip or knee in patients with immunosuppression. Further investigation is necessary to identify the best means of diagnosing periprosthetic joint infection in this patient population.

Is There a Difference in Infection Risk Between Single and Multiple Doses of Prophylactic Antibiotics? A Meta-analysis

BACKGROUND

The prevention of surgical site infection guidelines issued by the Centers for Disease Control and Prevention (CDC) recently recommended that only a single dose of preoperative antibiotics be administered to patients undergoing clean-contaminated procedures based on data from a variety of surgical disciplines. For orthopaedic procedures, where postoperative infections can have significant consequences, the existing evidence for this recommendation is widely debated.

QUESTIONS/PURPOSES

Is there a difference in postoperative infection risk when utilizing a single dose of preoperative antibiotics compared with multiple doses of perioperative antibiotics for orthopaedic procedures where implants are placed?

METHODS

MEDLINE, EMBASE, Google Scholar, and Cochrane were systematically reviewed for randomized controlled trials (RCTs) of a single dose of preoperative antibiotics compared with pre- and postoperative prophylaxis from 1980 to 2017 for all orthopaedic procedures where implants were being placed. Infection (both superficial and deep) as a primary outcome through all available followup was required for inclusion. Fourteen RCTs detailing 9691 orthopaedic procedures were included for analysis, including seven arthroplasty, one spine, and six general orthopaedic trials (two specific to hip fracture fixation). Pooled infection outcomes were analyzed with random-effects modeling in light of study heterogeneity. Bias was evaluated using the Cochrane risk of bias tool as well as a funnel plot for publication bias, and quality of evidence was evaluated using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach. Bias was largely uncertain; however, a high risk of bias was noted in four studies. No significant overall publication bias was noted. The quality of evidence was determined to be very low based on the GRADE tool, downgraded based on risk of bias, inconsistency, and imprecision. Despite the quality of evidence, the data were pooled in light of the current recommendations from the CDC to critically evaluate the recommendation that a single dose of antibiotics be utilized.

RESULTS

There were no differences in infection risk between single- versus multiple-dose groups (single: 83 of 4263 [2%], multiple: 101 of 5428 [2%]; odds ratio, 0.92 [95% confidence interval, 0.56-1.51]; p = 0.740, I = 36% for statistical heterogeneity).

CONCLUSIONS

There is no difference in infection risk between a single dose and multiple doses of perioperative antibiotics for orthopaedic procedures where implants are utilized, consistent with recent recommendations. However, the quality of evidence for orthopaedic procedures is low, and a randomized study with a sufficient sample size is needed to examine the issue before universal adoption of a single antibiotic dose.

LEVEL OF EVIDENCE

Level I, therapeutic study.

Clinical Impact of Routine Complete Blood Counts Following Total Knee Arthroplasty

BACKGROUND

Routine laboratory studies are generally obtained following total knee arthroplasty (TKA), and often continued daily until discharge. This study aims to investigate the utility and cost-effectiveness of complete blood count (CBC) tests following TKA.

METHODS

Retrospective review identified 484 patients who underwent primary TKA under a tourniquet at a single institution. Preoperative and postoperative CBC values were collected along with demographic data, use of tranexamic acid (TXA), and transfusion rates. Logistic regression models were calculated for all variables.

RESULTS

Twenty-five patients required transfusion following TKA (5.2%). Patients requiring transfusion had significantly lower preoperative hemoglobin compared to patients who did not require transfusion (11.47 vs 13.58 g/dL, P = .005). Risk of transfusion was 5.2 times higher in patients with preoperative anemia (95% confidence interval 2.90-9.35, P < .001). Without TXA, patients were 2.75 times more likely to receive transfusion (95% confidence interval 1.43-5.30, P < .001). An average of 2.9 CBC tests were collected per patient who did not receive medical intervention, costing a total of $144,773.80 in associated hospital charges ($316.10 per patient).

CONCLUSION

Ensuring quality, cost-effective patient care following total joint arthroplasty is essential in the era of bundled payments. Routine postoperative CBCs do not add value for patients with normal preoperative hemoglobin who receive TXA during TKA performed under tourniquet. Patients who are anemic preoperatively or do not receive TXA should obtain a postoperative CBC test. Daily CBCs are unnecessary if the first postoperative CBC does not prompt intervention.

When Should Complete Blood Count Tests Be Performed in Primary Total Hip Arthroplasty Patients?

BACKGROUND

Routine laboratory studies are often obtained following total hip arthroplasty (THA). Moreover, laboratory studies are often continued daily until the patient is discharged regardless of medical management. The purpose of this study was to investigate the use of routine complete blood count (CBC) tests following THA. Secondarily, the purpose was to identify patient factors associated with abnormal postoperative lab values.

METHODS

This retrospective review identified 352 patients who underwent primary THA at a single institution from 2012 to 2014. Preoperative and postoperative CBC values were collected along with demographic data, use of tranexamic acid (TXA), and transfusion rates. Logistic regression models were used to identify factors associated with an abnormal postoperative lab and risk of transfusion.

RESULTS

Of the 352 patients, 54 patients were transfused (15.3%). Patients who underwent transfusion had a significantly lower preoperative hemoglobin (Hb; 12.0 g/dL) compared to patients who did not undergo transfusion (13.5 g/dL; P < .001). Patients who did not receive TXA were 3.7 times more likely to receive a transfusion. No patients received medical intervention based on the outcome of postoperative platelet or white blood counts. A Hb value below 11.94 g/dL for patients who are anemic preoperative or did not receive TXA predicted transfusion after postoperative day 1.

CONCLUSION

Under value-based care models, cost containment while maintaining high-quality patient care is critical. Routine postoperative CBC tests in patients with a normal preoperative Hb who receive TXA do not contribute to actionable information. Patients who are anemic before THA or do not receive TXA should at minimum obtain a CBC on postoperative day 1.

The Utility of Basic Metabolic Panel Tests After Total Joint Arthroplasty

INTRODUCTION

Routine laboratory studies are often obtained daily after total joint arthroplasty (TJA) regardless of medical management. The purpose of this study was to investigate the utility of routine basic metabolic panel (BMP) tests after TJA. Furthermore, the goal was to identify factors that may predispose patients to abnormal laboratory values that require medical intervention.

METHODS

A retrospective review was performed on 767 patients who underwent primary TJA at a single institution. Preoperative and postoperative potassium, sodium, creatinine, and glucose values were collected along with demographic data, comorbidities, and procedural characteristics. Multivariable logistic regression models were used to determine independent risk factors for abnormal postoperative laboratory values.

RESULTS

Diabetes was associated with abnormal glucose (odds ratio [OR] 23.4, 95% confidence interval [CI] 10.7-51.0, P < .001), while chronic kidney disease was associated with abnormal creatinine (OR 3.1, 95% CI 1.7-5.8, P < .001) and potassium (OR 1.8, 95% CI 1.1-2.8, P = .014) requiring medical intervention. An abnormal preoperative laboratory value was also associated with medical treatment for each of sodium, potassium, and creatinine (all P < .001). Average number of BMP tests collected for patients who did not receive medical intervention was 2.8. This equated to $472,372.56 in total hospital charges.

CONCLUSION

Cost containment while maintaining high-quality patient care is critical. Routine postoperative BMP tests in patients with normal preoperative values without major medical comorbidities do not contribute to actionable information. Patients with diabetes, chronic kidney disease, or with abnormal preoperative values should obtain a BMP after TJA.

Trends in Opioid Utilization Before and After Total Knee Arthroplasty

BACKGROUND

Opioids are a mainstay in perioperative pain management among patients undergoing total knee arthroplasty (TKA). However, patterns in opioid use before and after TKA have not been well-studied. The objectives of this study are to characterize prescribing trends preoperatively and postoperatively and identify risk factors for chronic postoperative opioid use.

METHODS

A review of the prescription-tracking database of a large private payer from 2007 to 2013 was performed using International Classification of Diseases, Ninth Revision and Current Procedural Terminology codes. Chronic opioid use was defined as opioid prescriptions over 6 contiguous months postoperatively.

RESULTS

We identified 66,950 patients who underwent TKA with minimum 2-year follow-up and medication codes. Of those taking opioids preoperatively (n = 36,668), 34.8% became chronic users postoperatively compared to only 5.0% of the opioid-naïve cohort (n = 30,282). Major risk factors for chronic postoperative opioid use included preoperative opioid use (relative risk [RR] 3.75, 95% confidence interval [CI] 3.59-3.93), female gender (RR 1.23, 95% CI 1.20-1.25), and younger age (≤44 vs ≥60: RR 1.41, 95% CI 1.32-1.49; 45-59 vs ≥60: RR 1.42, 95% CI 1.40-1.46). From 2007 to 2013, there was a significant linear increase in opioid use preoperatively (odds ratio [OR] 1.04, 95% CI 1.03-1.05, P < .001) and postoperatively (OR 1.20, 95% CI 1.18-1.21, P < .001), but chronic postoperative opioid use increased only marginally (OR 1.01, 95% CI 1.00-1.02, P = .021).

CONCLUSION

The greatest risk factors for chronic postoperative opioid use were preoperative use, younger age, female gender, greater length of stay, and worse health status. Although the use of opioids continues to grow significantly preoperatively and postoperatively, chronic opioid use post-TKA has remained clinically unchanged.

Short and Long-Term Postoperative Complications Following Total Joint Arthroplasty in Patients With Human Immunodeficiency Virus, Hepatitis B, or Hepatitis C

INTRODUCTION

Due to advancement in treatment against human immunodeficiency virus (HIV), hepatitis B virus (HBV), and hepatitis C virus (HCV), the prevalence of this patient population electing to undergo total joint arthroplasty (TJA) is increasing. Current literature is scarce and conflicting especially when evaluating long-term surgical complications. The purpose of this study is to assess the postoperative medical and surgical complications following TJA in these patient populations.

METHODS

Using a nationwide database between 2005 and 2012, 4 cohorts were created: patients with HIV, HCV, HBV, and HIV and HBV or HCV who underwent TJA. Cohorts were matched to a control group by age, gender, and Charlson Comorbidity Index. Thirty-day and 90-day medical complications and 90-day and 2-year surgical complications were evaluated using odds ratios with 95% confidence intervals.

RESULTS

Following TJA, patients with HCV or HBV had increased risk of pneumonia, sepsis, joint infection, and revision surgery at 90 days and 2 years. Patients with HIV did not have increased risk of infection at 90 days and 2 years but did have increased risk of revision at 90 days (odds ratio 3.21, 95% confidence interval 1.31-7.84) following total hip arthroplasty.

CONCLUSIONS

Patients with HIV, HBV, or HCV have an overall increased risk of postoperative medical and surgical complications following TJA. Patients with HBV or HCV are at risk of more complications than patients with HIV especially for infection within 90 days after TJA. Patients with HIV are at risk of mechanical complications but do not appear to be at significant risk for infection following total hip arthroplasty.

Inpatient Consults and Complications During Primary Total Joint Arthroplasty in a Bundled Care Model

BACKGROUND

The Centers for Medicare and Medicaid Services (CMS) are implementing changes in hospital reimbursement models for total joint arthroplasty (TJA), moving to value-based bundled payments from the fee-for-service model. The purpose of this study is to identify consults and complications during the perioperative period that increase financial burden.

METHODS

We combined CMS payment data for inpatient, professional, and postoperative with retrospective review of patients undergoing primary TJA and developed profiles of patients included in the Comprehensive Care for Joint Replacement bundle undergoing TJA. Statistical comparison of episode inpatient events and payments was conducted. Multiple regression analysis was adjusted for length of stay, disposition, and Charlson-Deyo comorbidity profile.

RESULTS

Median total payment was $21,577.36, which exceeded the median bundle target payment of $20,625.00. Adjusted analyses showed that psychiatry consults (increase of $73,123.32; P < .001), internal medicine consults ($5789.38; P ≤ .001), pulmonary embolism ($35,273.68; P < .001), intensive care unit admission ($14,078.37; P < .001), and deep vein thrombosis ($9471.26; P = .019) resulted in increased payments using multivariate analysis adjusted for length of stay, Charlson-Deyo comorbidities, and discharge disposition.

CONCLUSION

Patients with inpatient complications such as pulmonary embolism and/or deep vein thrombosis, intensive care unit admission, and medical/psychiatric consultation exceeded the CMS target. Although study results showed typical complication rates, acute inpatient consultation significantly increased utilization beyond the CMS target even when adjusted for length of stay, patient comorbidities, and discharge. Needed medical care should continue to be a priority for inpatients, and allowance for individual outliers should be considered in policy discussions.

Postoperative Impact of Diabetes, Chronic Kidney Disease, Hemodialysis, and Renal Transplant After Total Hip Arthroplasty

BACKGROUND

The prevalence of diabetes mellitus (DM), chronic kidney disease (CKD), hemodialysis (HD), and renal transplantation (RT) is increasing. This study assessed postoperative complications among diabetic patients with CKD, HD, or post-RT after total hip arthroplasty (THA).

METHODS

Four cohorts were created using a nationwide database: DM&THA, DM&CKD&THA, DM&HD&THA, and DM&RT&THA. Cohorts were matched to a control group by age and gender. Thirty-day medical complications and 90-day and 2-year surgical complications were evaluated.

RESULTS

All 30-day complications were higher in each cohort. Ninety-day and 2-year surgical complications in the DM&HD&THA cohort were increased compared to the DM&RT&THA cohort. Remarkably, no increased risk of periprosthetic joint infection, periprosthetic fracture, or revision was noted post-THA in the DM&RT&THA cohort.

CONCLUSION

Diabetic patients with worsening kidney function are associated with increased post-THA complications. Postsurgical risks decline following RT. Diabetic patients with kidney failure may want to undergo RT prior to THA to optimize surgical outcomes.

Comparison of postoperative complications after total hip arthroplasty among patients receiving aspirin, enoxaparin, warfarin, and factor Xa inhibitors

Optimal prophylaxis for prevention of venous thromboembolism (VTE) after total joint arthroplasty (TJA) remains debated. The purpose of this study was to compare postoperative complications in patients receiving different VTE chemoprophylactic regimens. Using a nationwide healthcare database, 72,670 THA patients without a history of VTE were identified. Study cohorts received VTE prophylaxis within 30 days postoperatively. Odds ratios and 95% confidence intervals were used to assess 30-day and 90-day postoperative complications (hematoma, hemorrhage, transfusion, pulmonary embolism (PE), VTE, prosthetic joint infection (PJI), and incision/drainage (I&D)). Of the 72,670 THA patients, 25,966 received single medication VTE prophylaxis; 551 (2.12%) aspirin, 6791 (26.15%) enoxaparin, 12,008 (46.25%) warfarin, 5403 (20.81%) rivaroxaban, 876 (3.37%) fondaparinux and 337 (1.30%) apixaban. 30-day complications included; aspirin: I&D; warfarin: I&D, hematoma, hemorrhage, transfusion, PJI, PE and DVT; apixaban: hematoma and hemorrhage. 90-day complications included; aspirin: I&D; warfarin: I&D, hematoma, hemorrhage, transfusion, PJI, PE and DVT. Warfarin was the only anticoagulant associated with a higher risk for DVT, and the highest risk for 30-day and 90-day complications. Aspirin had the highest risk for I&D. Despite three times increased 30-day risk for bleeding, apixaban was effective in preventing VTE during the high-risk 3-month-period. Enoxaparin had the lowest risk for PE and DVT while rivaroxaban had the lowest risk for PJI, hematoma, I&D, hemorrhage and transfusion.

Measurement of Nitinol Recovery Distance Using Pseudoelastic Intramedullary Nails for Tibiotalocalcaneal Arthrodesis

BACKGROUND

Tibiotalocalcaneal arthrodesis is a salvage procedure for patients with complex disease of the ankle and subtalar joints. Despite the clinical efficacy and mechanical advantage of intramedullary nails, complications, such as nonunion, are common. It may be possible to sustain compression in the face of bone resorption and implant loosening over the course of healing using a novel pseudoelastic intramedullary nail with an internal nitinol element.

METHODS

We identified 15 patients with average age of 54.7 years (range, 28-75 years) who had undergone a tibiotalocalcaneal arthrodesis using a pseudoelastic intramedullary nail. Serial radiographs were used to determine the amount and rate of nitinol element migration over the first 3 postoperative months.

RESULTS

Postoperatively, there was at least 2.38 mm of nitinol element migration proximally with mean of 5.58 mm (± 1.38), (range, 2.38-8.11 mm). Average follow-up time was 195 days (± 106.3), (range, 89-490 days). On average, 86% of the total recovered distance took place within the first 39.7 days (±10.03).

CONCLUSIONS

The nitinol element recovers distance when stretched intraoperatively and maintains moderate compression in response to bone resorption. Further studies are needed to assess if this increased compression lends itself to higher fusion rates than traditional intramedullary nails.

LEVELS OF EVIDENCE

Therapeutic, Level IV: Case series.

Measurement of Nitinol Recovery Distance Using Pseudoelastic Intramedullary Nail in Tibiotalocalcaneal Arthrodesis

Category:

Ankle

Introduction/Purpose:

Tibiotalocalcaneal(TTC) arthrodesis is a salvage procedure for patients with complex disease of the ankle and subtalar joints. Despite the clinical efficacy and mechanical advantage of intramedullary nails, complications, such as nonunion, are not uncommon. It may be possible to sustain compression in the face of bone resorption and implant loosening over the course of healing using a novel pseudoelastic intramedullary nail.

Methods:

We identified 15 patients (age+54.7+/-20.0 years) who had undergone a tibiotalocalcaneal arthrodesis using a pseudoelastic intramedullary nai. Serial radiographs were used to determine the amount and rate of Nitinol element migration over time.

Results:

Three months after surgery, there was at least 2.38mm of Nitinol element migration proximally with mean of 5.58mm(range: 2.38 to 8.11mm). Average follow up time was 195 days (range: 89 to 490 days).

Conclusion:

The Nitinol element recovers distance when stretched intra-operatively and maintains moderate compression in response to bone resorption. Further studies are needed to assess if this increased compression lends itself to higher fusion rates than traditional IMN’s.