Revision Hip Arthroplasty Performed by Fellowship-Trained Versus Non-Fellowship-Trained Surgeons: A Comparison of Perioperative Management and Complications.

BACKGROUND: Successful revision hip arthroplasty (rTHA) requires major resource allocation and a surgical team adept at managing these complex cases. The purpose of this study was to compare the results of rTHA performed by fellowship-trained and non-fellowship-trained surgeons. METHODS: A national administrative database was utilized to identify 5,880 patients who underwent aseptic rTHA and 1,622 patients who underwent head-liner exchange for infection by fellowship-trained and non-fellowship-trained surgeons from 2010 to 2020 with a 5-year follow-up. Postoperative opioid and anticoagulant prescriptions were compared among surgeons. Patients treated by fellowship-trained and non-fellowship-trained surgeons had propensity scores matched based on age, sex, comorbidity index, and diagnosis. The 5-year surgical complications were compared using descriptive statistics. Multivariable analysis was performed to determine the odds of failure following head-liner exchange when performed by a fellowship-trained versus non-fellowship-trained surgeon. RESULTS: Aseptic rTHA patients treated by fellowship-trained surgeons received fewer opioids (132 versus 165 milligram morphine equivalents per patient) and nonaspirin anticoagulants (21.4 versus 32.0%, P < .001). Fellowship-training was associated with lower dislocation rates (9.9 versus 14.2%, P = .011), fewer postoperative infections, and fewer periprosthetic fractures and re-revisions (15.2 versus 21.3%, P < .001). Head-liner exchange for infection performed by fellowship-trained surgeons was associated with lower odds of failure (31.2 versus 45.7%, odds ratio 0.76, 95% confidence interval 0.62 to 0.91, P < .001). CONCLUSIONS: rTHA performed by adult reconstruction fellowship-trained surgeons results in fewer re-revisions in aseptic cases and head-liner exchanges. Variations in resources, volumes, and perioperative protocols may account for some of the differences.

Three Differing Methods of Treating Intraoperative Nondisplaced Calcar Fractures Demonstrate Similar Radiographic Stem Subsidence.

BACKGROUND: Several management strategies have been described to treat intraoperative calcar fractures during total hip arthroplasty (THA), including retaining the primary implant and utilizing cerclage cables (CCs) or switching the implant to one that bypasses the fracture and achieves diaphyseal fixation. However, the radiographic and clinical outcomes of these differing strategies have never been described and compared. METHODS: We retrospectively identified 50 patients who sustained an intraoperative calcar fracture out of 9,129 primary total hip arthroplasties (0.55%) performed by one of three surgeons between 2008 and 2022. Each of the three surgeons consistently employed a distinct strategy for the management of these fractures: retention of the primary metaphyseal-engaging implant and placement of CCs; exchange to a modular, tapered-fluted stem (MTF); or exchange to a fully-coated, diaphyseal-engaging stem (FC). Stem subsidence was then evaluated on standing anteroposterior pelvis radiographs at three months and one year postoperatively. Postoperative medical and surgical complication rates were evaluated. RESULTS: A total of fifteen patients were treated with CC, 15 with MTF, and 20 with FC. At three-month follow-up, mean stem subsidence was 0.43 ± 0.08 mm, 1.47 ± 0.36 mm, and 0.68 ± 0.39 mm for CC, MTF, and FC cohorts, respectively (P = .323). At one-year, mean stem subsidence was 0.70 ± 0.08 mm, 1.74 ± 0.69 mm, and 1.88 ± 0.90 mm for the CC, MTF, and FC cohorts, respectively (P = .485). Medical complications included 2 venous thromboembolic events (4%) within 90 days of surgery. There were 6 reoperations (12%); 3 (6%) for acute periprosthetic joint infection (all within the FC cohort); 2 (4%) for postoperative periprosthetic fractures (one fracture distal to the stem in the FC cohort and one fracture at the level of the stem in the MTF cohort), and 1 (2%) closed reduction for instability (within the CC cohort). CONCLUSIONS: The three described methods of managing intraoperative nondisplaced calcar fractures demonstrated little radiographic stem subsidence; however, the risk of reoperation was much higher than expected.

A Systematic Review of the Efficacy and Safety of Ketamine in Total Joint Arthroplasty.

BACKGROUND: Ketamine is administered intraoperatively to treat pain associated with primary total hip (THA) and knee arthroplasty (TKA). The purpose of this study was to evaluate the efficacy and safety of ketamine in primary THA and TKA to support the combined clinical practice guidelines of the American Association of Hip and Knee Surgeons (AAHKS), American Academy of Orthopaedic Surgeons (AAOS), Hip Society, Knee Society, and the American Society of Regional Anesthesia and Pain Management (ASRA). METHODS: The MEDLINE, Embase, and Cochrane Central Register of Controlled Trials databases were searched for studies published prior to 2020 on ketamine in THA and TKA. All included studies underwent qualitative assessment and quantitative homogeneity testing followed by a systematic review and direct comparison meta-analysis to assess the efficacy and safety of ketamine. After a critical appraisal of 136 publications, 7 high-quality studies were included for analyses. RESULTS: High-quality evidence demonstrates that intraoperative ketamine decreases postoperative opioid consumption. Four of 7 studies found that ketamine reduces postoperative pain. Intraoperative ketamine is not associated with an increase in adverse events and may reduce postoperative nausea and vomiting (relative risk [RR] 0.68; 95% CI 0.50-0.92). CONCLUSION: High-quality evidence supports the use of ketamine intraoperatively in THA and TKA to reduce postoperative opioid consumption. Most studies found ketamine reduces postoperative pain, nausea, and vomiting. Moderate quality evidence supports the safety of ketamine, but it should be used cautiously in patients at risk for postoperative delirium, such as the elderly.

Machine learning algorithms predict within one size of the final implant ultimately used in total knee arthroplasty with good-to-excellent accuracy.

PURPOSE: To develop a novel machine learning algorithm capable of predicting TKA implant sizes using a large, multicenter database. METHODS: A consecutive series of primary TKA patients from two independent large academic and three community medical centers between 2012 and 2020 was identified. The primary outcomes were final tibial and femoral implant sizes obtained from an automated inventory system. Five machine learning algorithms were trained using six routinely collected preoperative features (age, sex, height, weight, and body mass index). Algorithms were validated on an independent set of patients and evaluated through accuracy, mean absolute error (MAE), and root mean-squared error (RMSE). RESULTS: A total of 11,777 patients were included. The support vector machine (SVM) algorithm had the best performance for femoral component size(MAE = 0.73, RMSE = 1.06) with accuracies of 42.2%, 88.3%, and 97.6% for predicting exact size, ± one size, and ± two sizes, respectively. The elastic-net penalized linear regression (ENPLR) algorithm had the best performance for tibial component size (MAE 0.70, RMSE = 1.03) with accuracies of 43.8%, 90.0%, and 97.7% for predicting exact size, ± one size, and ± two sizes, respectively. CONCLUSION: Machine learning algorithms demonstrated good-to-excellent accuracy for predicting within one size of the final tibial and femoral components used for TKA. Patient height and sex were the most important factors for predicting femoral and tibial component size, respectively. External validation of these algorithms is imperative prior to use in clinical settings. LEVEL OF EVIDENCE: Case-control, III.

The Cost-Effectiveness of Tibial Metaphyseal Cones in Revision Total Knee Arthroplasty.

BACKGROUND: The purpose of this study is to evaluate the cost-effectiveness of tibial cones in revision total knee arthroplasty. METHODS: A Markov model was used for cost-effectiveness analysis. The average cone price was obtained from Orthopedic Network News. The average cone aseptic loosening rate was determined by literature review. Hospitalization costs and baseline re-revision rates were calculated using the PearlDiver Database. RESULTS: The maximum cost-effective cone price varied from $3514 at age 40 to $648 at age 90, compared to the current average selling price of $4201. Cones became cost-effective with baseline aseptic loosening rates of 0.89% annually at age 40 to 4.38% annually at age 90, compared to the current average baseline loosening rate of 0.76% annually. CONCLUSION: For the average patient, tibial cones are not cost-effective, but may become so at lower prices, in younger patients, or in patients at substantially increased risk of aseptic loosening.

The Impact of Race and Socioeconomic Status on Total Joint Arthroplasty Care.

BACKGROUND: Racial minorities and patients from lower socioeconomic backgrounds are less likely to undergo total joint arthroplasty (TJA) for degenerative joint disease (DJD). However, when these patients do present for care, little is known about the overall severity of DJD and surgical wait times. METHODS: A retrospective cohort of 407 patients (131 black and 276 white) who presented to an arthroplasty clinic and went on to receive TJA was established. Severity of osteoarthritis was assessed radiographically via Kellgren-Lawrence (KL) grade. Preoperative Knee Society Score (KSS) and Harris Hip Score (HHS) were used to measure joint pain and function. Multivariate regression modeling and analysis of covariance were used to examine racial and socioeconomic differences in KL grade, KSS, HHS, and time to surgery. RESULTS: Black patients presented with significantly greater KL scores than white patients (P = .046, odds ratio = 1.65, 95% confidence interval [1.01, 2.70]). In contrast, there were no statistically significant racial differences in the mean preoperative KSS (P = .61) or HHS (P = .69). Black patients were also found to wait, on average, 35% longer for TJA (P = .03, hazard ratio = 1.35, 95% confidence interval [1.04, 1.75]). Low income was associated with higher KL grade (P = .002), lower KSS (P = .07), and lower HHS (P = .001). CONCLUSION: Despite presenting with more advanced osteoarthritis, black patients reported similar levels of joint dysfunction and had longer surgical wait times when compared with white patients. Lower socioeconomic status was similarly associated with more severe DJD.

Clinical Outcomes in Isolated Tibial Revision With Cruciate Retaining Total Knee Arthroplasty.

BACKGROUND: Tibial component loosening is one of the most common modes of failure in contemporary total knee arthroplasty (TKA). Limited literature is available on the outcomes of isolated tibial revision with retention of the cruciate retaining (CR) femoral component. The purpose of this study was to determine the results of isolated tibial revisions in CR TKA. METHODS: We identified 135 patients who underwent an isolated tibial revision after a primary CR TKA from our institutional registry between January 2007 and January 2017. The mean time between the primary and revision was 2.9 years (range 0.1-15.4). Revision with a press-fit stem was performed in 79 patients and 56 patients were revised with a fully cemented stem. Patients were evaluated at a minimum of two years using Knee Society Score, Knee Injury and Osteoarthritis Score for Joint Replacement, and radiography. Implant survivorship was determined using Kaplan-Meier survival analysis. RESULTS: At a mean follow-up of 5.1 years, there were six (4.4%) repeat revisions: three for periprosthetic infection (2.2%), two for instability (1.5%), and one for a fractured tibial stem (0.7%). The mean Knee Society Score and Knee Injury and Osteoarthritis Score for Joint Replacement increased from 51.6 and 56.1 preoperatively to 90.1 and 89.7 after surgery (P < .001). Survivorship free of repeat revision for any cause was 93.3% at 5 years, and aseptic revision survivorship was 95.8% at 5 years. No implants were radiographically loose. CONCLUSION: In patients with isolated tibial loosening and a well-fixed and well-positioned CR femoral component, isolated tibial revision provides excellent early to midterm implant survivorship and clinical outcomes with a low risk of instability and recurrent tibial loosening.

Randomized Trial of Static and Articulating Spacers for Treatment of the Infected Total Hip Arthroplasty.

BACKGROUND: The purpose of this randomized clinical trial is to compare perioperative and postoperative variables between static and articulating spacers for the treatment of chronic periprosthetic joint infection (PJI) complicating total hip arthroplasty (THA). METHODS: Fifty-two patients undergoing resection arthroplasty as part of a 2-stage exchange for PJI at 3 centers were randomized to either a static (n = 23) or articulating spacer (n = 29). The primary endpoint was operative time of the second-stage reimplantation and power analysis determined that 22 patients per cohort were necessary to detect a 20-minute difference. Seven patients were lost to follow-up, 4 were never reimplanted, and one died before discharge after reimplantation. Forty patients were followed for a mean 3.2 years (range 2.0-7.1). RESULTS: There were no differences in operative time at second-stage reimplantation (143 minutes static vs 145 minutes articulating, P = .499). Length of hospital stay was longer in the static cohort after stage 1 (8.6 vs 5.4 days, P = .006) and stage 2 (6.3 vs 3.6 days, P < .001). Although it did not reach statistical significance with the numbers available for study, nearly twice as many patients in the static cohort were discharged to an extended care facility after stage 1 (65% vs 30%, P = .056). CONCLUSION: This randomized trial demonstrated that the outcomes of static and articulating spacers are similar in the treatment of THA PJI undergoing 2-stage exchange arthroplasty. The significantly longer length of hospital stay associated with the use of static spacers may have important economic implications for the health care system.

Spacer Design Options and Consideration for Periprosthetic Joint Infection.

An articulating or nonarticulating antibiotic hip spacer can be placed following the first stage implant removal of a periprosthetic hip joint infection. Antibiotic spacers help fill in the dead space created at the time of resection and provide a high local concentration of antibiotics. Theoretical advantages of a static spacer include a higher elution of antibiotics because of the increased surface area, the ability to protect deficient bone in the proximal femur/acetabulum, and the ability to immobilize the periarticular soft tissues. Advantages of an articulating spacer include improved ambulation and easier motion for the patient, maintenance of soft tissue tension, and an easier surgical reconstruction at the time of the second stage. Additionally, an articulating antibiotic spacer may minimize the risk of dislocation following the second stage reconstruction. The choice of articulating or nonarticulating is currently one of surgeon preference yet it is advised that surgeons consider an articulating spacer for all patients except those with severe femoral/acetabular bone loss or deficient abductors.

Dilute Betadine Lavage Reduces the Risk of Acute Postoperative Periprosthetic Joint Infection in Aseptic Revision Total Knee and Hip Arthroplasty: A Randomized Controlled Trial.

BACKGROUND: The purpose of this randomized, controlled trial is to determine whether dilute betadine lavage compared to normal saline lavage reduces the rate of acute postoperative periprosthetic joint infection (PJI) in aseptic revision total knee (TKA) and hip arthroplasty (THA). METHODS: A total of 478 patients undergoing aseptic revision TKA and THA were randomized to receive a 3-minute dilute betadine lavage (0.35%) or normal saline lavage before surgical wound closure. Fifteen patients were excluded following randomization (3.1%) and six were lost to follow-up (1.3%), leaving 457 patients available for study. Of them, 234 patients (153 knees, 81 hips) received normal saline lavage and 223 (144 knees, 79 hips) received dilute betadine lavage. The primary outcome was PJI within 90 days of surgery with a secondary assessment of 90-day wound complications. A priori power analysis determined that 285 patients per group were needed to detect a reduction in the rate of PJI from 5% to 1% with 80% power and alpha of 0.05. RESULTS: There were eight infections in the saline group and 1 in the betadine group (3.4% vs 0.4%, P = .038). There was no difference in wound complications between groups (1.3% vs 0%, P = .248). There were no differences in any baseline demographics or type of revision procedure between groups, suggesting appropriate randomization. CONCLUSION: Dilute betadine lavage before surgical wound closure in aseptic revision TKA and THA appears to be a simple, safe, and effective measure to reduce the risk of acute postoperative PJI. LEVEL OF EVIDENCE: Level I.

Periprosthetic Fractures of the Distal Femur: Is Open Reduction and Internal Fixation or Distal Femoral Replacement Superior?

BACKGROUND: The purpose of this study is to compare open reduction and internal fixation (ORIF) to distal femoral replacement (DFR) for treatment of displaced periprosthetic distal femur fractures. METHODS: We identified 72 patients with minimum 2-year follow-up following a displaced periprosthetic distal femur fracture: 50 were treated with ORIF and 22 with DFR. Outcomes were assessed with multivariate regression analysis and include Knee Society Scores (KSS), infection rates, revision incidence, and mortality. RESULTS: Patients treated with DFR had a higher Charlson comorbidity index (5.2 vs 3.8; P = .006). The mean postoperative KSS were similar between groups, but the Knee Society Functional Scores were higher in the ORIF group (P = .01). Six ORIF patients (12%) and 3 DFR patients (14%) underwent a revision surgery (P = .1). In the ORIF group, 3 revisions were associated with periprosthetic infection, and 3 revisions occurred for aseptic nonunion. In the DFR group, 1 infection was treated with irrigation and debridement, and 2 cases of patellar maltracking resulted in 1 liner exchange with soft tissue release and 1 femoral revision for malrotation. More patients in the ORIF group required repeat revisions, with twice as many total revisions (P < .001). Six ORIF patients and 7 DFR patients died within 2 years (P = .26). CONCLUSION: The Knee Society Functional Score favored ORIF, but the total incidence of revision was higher in the ORIF cohort. Given the high mortality and the substantial risk of reoperation in both groups, additional studies are needed regarding the prevention of and optimal treatment for patients with periprosthetic distal femur fractures.

High Failure at a Minimum 5-Year Follow-Up in Primary Total Hip Arthroplasty Using a Modular Femoral Trunnion.

BACKGROUND: Modular femoral trunnions enable the surgeon to independently adjust offset, leg length, and anteversion in total hip arthroplasty (THA). However, modularity may result in an increased risk of fretting and corrosion along with a higher risk of implant dissociation or fracture. The purpose of this study is to evaluate mid-term survivorship of THAs using a cementless modular system. METHODS: A consecutive series of 221 patients who underwent a primary THA using the ALFA II modular stem by a single surgeon between 2002 and 2004 were reviewed. Survivorship of the ALFA II modular hip system was evaluated at a minimum of 5 years postoperatively. RESULTS: Of the 221 patients, 28 (12.7%) died from causes unrelated to the surgery before adequate follow-up, and 64 (29.0%) patients were lost to follow-up. The remaining 129 patients had a mean 6.5-year (range: 5-8 years) follow-up. All-cause survivorship of the modular stem system was 81% (95% confidence interval = 69-90) at a mean 6.5-year follow-up. Of the 25 (19.4%) cases requiring revision surgery, 52.0% was for dissociation of the modular components, 32.0% was for fracture of the prosthesis, 12.0% was for instability/multiple dislocations, and 4.0% was for chronic septic THA. Body mass index (odds ratio = 1.080) and offset (odds ratio = 1.254) were independent risk factors for mechanical failures of the modular stem system. CONCLUSION: The modular stem hip system of interest in this study demonstrates a high failure rate at mid-term follow-up, and we caution against the use of similar designs in primary THAs.

Internal Validation of a Predictive Model for Satisfaction After Primary Total Knee Arthroplasty.

BACKGROUND: As the number of total knee arthroplasty (TKA) procedures continues to rise in the context of bundled payment models, patients dissatisfied postoperatively that require additional care will impose additional cost to the healthcare system. The purpose of this study is to internally validate a predictive model for postoperative patient satisfaction after TKA. METHODS: In total, 484 consecutive primary TKA patients between January 2014 and January 2016 were included. Patients were stratified into 4 risk tiers based on scores of a retrospectively applied, 11-component novel knee survey for postoperative satisfaction: low risk (>96.5), mild risk (75-96.4), moderate risk (60-74.9), and high risk (<60). Binary logistic and multivariate linear regression models were constructed to determine whether the survey was predictive of satisfaction. A receiver operator curve was constructed to determine a threshold score below which patients were likely to experience postoperative dissatisfaction. RESULTS: The mean (±standard deviation) age was 66.3 ± 9.2 years (range 31.7-100.1) and mean body mass index was 34.2 ± 8.2 kg/m2 (range 16.2-68.4). A knee survey score of 96.5 conferred a 97.5% sensitivity and 95.7% negative predictive value for satisfaction. Patients with higher knee survey scores had greater odds (odds ratio 1.03, 95% confidence interval 1.01-1.06, P = .003) of postoperative satisfaction. Increasing risk tier was significantly associated with decreased satisfaction (low risk 95.7%, mild risk 93.8%, moderate risk 86.4%, and high risk 80.4%; P = .007). The knee survey was not significantly correlated with complications (r = -0.43, P = .32). CONCLUSION: This novel knee survey conferred a 97.5% sensitivity and 95.7% negative predictive value in identifying at-risk patients for postoperative dissatisfaction after primary TKA.

Superior Survivorship for Posterior Stabilized Versus Constrained Condylar Articulations After Revision Total Knee Arthroplasty: A Retrospective, Comparative Analysis at Short-Term Follow-Up.

BACKGROUND: The decision to use a posterior stabilized (PS) or constrained condylar knee (CCK) articulation in revision total knee arthroplasty (RTKA) has traditionally been based on surgeon preference and knee stability. The purpose of this study is to compare various outcomes and survivorship in RTKA with PS or CCK articulations. METHODS: A retrospective comparative study of RTKA with CCK or PS articulations (PS = 106/CCK = 147) was performed with minimum 2-year follow-up. Exclusion criteria were patients with rotating hinged implants or non-CCK/PS constructs. Multivariate logistic regression models were constructed to determine whether implant articulation influenced (1) complications, (2) aseptic loosening, and (3) re-revision. Kaplan-Meier estimates of cumulative implant survival were constructed with revision as the failure variable. RESULTS: PS articulation was an independent predictor of increased postoperative knee flexion (6.4°, P = .010) and the knee society functional score (10.0, P = .002). Survivorship was significantly reduced for CCK revision articulations when all-cause re-revision was the primary endpoint (P = .0003, log-rank test of equality). The primary reason for re-revision in the CCK cohort was a recurrent/persistent infection of the operative knee (N = 16, 37.2%), followed by aseptic loosening (N = 13, 30.2%). PS articulations conferred a lower likelihood of re-revision (odds ratio [OR] 0.3, P = .001), but articulation design was not associated with complications (OR 0.5, P = .123) or aseptic loosening (OR 2.6, P = .143). CONCLUSION: The PS articulation when used for appropriate indication conferred superior survivorship for the primary endpoint of all-cause re-revision and overall knee function when compared to the CCK articulation after RTKA. Implant articulation was not a predictor of aseptic loosening or complications.

Prospective Validation of a Demographically Based Primary Total Knee Arthroplasty Size Calculator.

BACKGROUND: Preoperative planning for total knee arthroplasty (TKA) is essential for streamlining operating room efficiency and reducing costs. Digital templating and patient-specific instrumentation have shown some value in TKA but require additional costs and resources. The purpose of this study was to validate a previously published algorithm that uses only demographic variables to accurately predict TKA tibial and femoral component sizes. METHODS: Four hundred seventy-four consecutive patients undergoing elective primary TKA were prospectively enrolled. Four surgeons were included, three of which were unaffiliated with the retrospective cohort study. Patient sex, height, and weight were entered into our published Arthroplasty Size Prediction mobile application. Accuracy of the algorithm was compared with the actual sizes of the implanted femoral and tibial components from 5 different implant systems. Multivariate regression analysis was used to identify independent risk factors for inaccurate outliers for our model. RESULTS: When assessing accuracy to within ±1 size, the accuracies of tibial and femoral components were 87% (412/474) and 76% (360/474). When assessing accuracy to within ±2 sizes of predicted, the tibial accuracy was 97% (461/474), and the femoral accuracy was 95% (450/474). Risk factors for the actual components falling outside of 2 predicted sizes include weight less than 70 kg (odds ratio = 2.47, 95% confidence interval [1.21-5.06], P = .01) and use of an implant system with <2.5 mm incremental changes between femoral sizes (odds ratio = 5.50, 95% confidence interval [3.33-9.11], P < .001). CONCLUSIONS: This prospective series of patients validates a simple algorithm to predict component sizing for TKA with high accuracy based on demographic variables alone. Surgeons can use this algorithm to simplify the preoperative planning process by reducing unnecessary trays, trials, and implant storage, particularly in the community or outpatient setting where resources are limited. Further assessment of components with less than 2.5-mm differences between femoral sizes is required in the future to make this algorithm more applicable worldwide.

High Rate of Failure After Revision of a Constrained Liner.

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.

Rotating Hinge Implants for Complex Primary and Revision Total Knee Arthroplasty.

BACKGROUND: Contemporary rotating hinge knee (RHK) prosthesis has shown improved survival rates over earlier generations. However, reports of high complication and mechanical failure rates highlight the need for more clinical outcome data in the complex primary and revision setting. The purpose of this study is to report our results of using a contemporary rotating hinge for complex primary and revision total knee arthroplasty. METHODS: Using a prospectively maintained surgical database, 79 knees in 76 patients who underwent an RHK of a single design for either a complex primary (14 knees) or revision total knee arthroplasty (65 knees) were identified. This included 19% undergoing an RHK for periprosthetic joint infection and 32.9% who had concomitant extensor mechanism repair. The cohort consisted of 60 women and 16 men with a mean age of 66.7 years (range 39-89) at the time of surgery. Patient outcomes were assessed using Knee Society Scores and radiographs were reviewed for signs of wear and loosening. Failure rates were estimated using Kaplan-Meier survival curves. RESULTS: At a minimum of 2 years, 13 patients had died and 4 were lost to follow-up, leaving 62 knees in 59 patients who were followed for a mean of 55.2 months (range 24-146). The mean Knee Society Scores improved from 35.7 to 66.2 points (P < .01). The incidence of complications was 38.7%. The most common complications were periprosthetic fracture, extensor mechanism rupture, and periprosthetic infection. Estimated survival was 70.7% at 5 years. CONCLUSION: Despite improvements in design and biomaterials, there remains a relatively high complication rate associated with the use of a modern RHK implant. While aseptic loosening was rare, periprosthetic fracture, infection, and extensor mechanism failure were substantial emphasizing the complex nature of these cases.

Clinical Outcomes and Survivorship of Lateral Unicompartmental Knee Arthroplasty: Does Surgical Approach Matter?

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.

Systemic Absorption of Antibiotics From Antibiotic-Loaded Cement Spacers for the Treatment of Periprosthetic Joint Infection.

BACKGROUND: Two-stage treatment of periprosthetic joint infections involves placement of high-dose antibiotic-loaded cement spacers (ACSs). Reports of ACS-induced nephrotoxicity have raised concern regarding systemic absorption of antibiotics after ACS placement. We sought to characterize the serum concentrations of antibiotics that occur after ACS placement. METHODS: We performed a prospective study of patients with an infected primary total hip (THA) or knee arthroplasty (TKA) treated with standardized ACSs with vancomycin, gentamicin, and tobramycin. Serum antibiotic levels were collected weekly for 8 weeks. RESULTS: Twenty-one patients (10 THA, 11 TKA) were included. Mean serum gentamicin levels ranged between 0.275±0.046 and 0.364±0.163 mg/L; mean serum tobramycin levels ranged from 0.313±0.207 to 0.527±0.424 mg/L; and mean serum vancomycin levels ranged from 5.46±6.6 to 15.34±9.6 mg/L. Serum antibiotic levels were detectable throughout the 8-week duration of ACS treatment. Regression analysis found that diabetes (coefficient 6.73, 95% CI 0.92-12.54, P < .05), blood urea nitrogen (coefficient 0.83, 95% CI 0.45-1.22, P < .001), number of cement doses (coefficient 3.71, 95% CI 0.76-6.66, P < .05), and use of systemic vancomycin (coefficient 6.24, 95% CI 2.72-9.75, P < .001) correlated with serum vancomycin levels. Patient age (coefficient -0.01, 95% CI -0.02 to 0, P < .01) and male sex (coefficient 0.20, 95% CI 0-0.41, P < .05) correlated with serum aminoglycoside level. CONCLUSION: Systemic absorption of antibiotics from high-dose ACS persists for at least 8 weeks. Patients should be monitored closely for complications related to systemic absorption of antibiotics from ACS treatment.

Internal Validation of a Predictive Model for Complications After Total Hip Arthroplasty.

BACKGROUND: Total hip arthroplasty (THA) is projected to increase in prevalence and associated complications will impose significant cost on the US healthcare system. The purpose of this study is to validate a predictive model for postoperative complications utilizing a novel 11-component hip-specific questionnaire encompassing preoperatively available clinical and radiographic data. METHODS: Consecutive primary THA patients between January 2014 and January 2016 were included. Exclusion criteria included patients without questionnaire scoring variables and less than 1-year follow-up. Patients were stratified into 4 tiers based on their questionnaire score: low risk (>74), mild risk (57-73), moderate risk (41-56), and high risk (<40). A binary logistic regression was performed to determine if the questionnaire predicted complications. Receiver-operator curves were constructed to determine the threshold score below which there was a high likelihood of experiencing a complication. RESULTS: Four hundred fifty patients were included in the final analysis with a mean (range) follow-up of 2.1 years (1.0-5.9), age of 63.1 years (25.7-9.17), and body mass index of 31.7 kg/m2 (17.8-64.5). The complication rate was 13.6%. A hip questionnaire score of 73.8 conferred a 98.5% sensitivity and 98.5% negative predictive value for complications. The questionnaire score was the strongest predictor of a decreased complication likelihood (odds ratio 0.94, 95% confidence interval 0.90-0.97, P < .001). Risk tier was significantly associated with complications (low risk: 0; mild risk: 12; moderate risk: 25; and high risk: 24; P < .001). CONCLUSION: This novel hip questionnaire demonstrated a high sensitivity and negative predictive value to identify patients at risk for postoperative complications. Future studies should attempt to prospectively validate the use of this questionnaire.