Machine Learning Did Not Outperform Conventional Competing Risk Modeling to Predict Revision Arthroplasty.

BACKGROUND: Estimating the risk of revision after arthroplasty could inform patient and surgeon decision-making. However, there is a lack of well-performing prediction models assisting in this task, which may be due to current conventional modeling approaches such as traditional survivorship estimators (such as Kaplan-Meier) or competing risk estimators. Recent advances in machine learning survival analysis might improve decision support tools in this setting. Therefore, this study aimed to assess the performance of machine learning compared with that of conventional modeling to predict revision after arthroplasty. QUESTION/PURPOSE: Does machine learning perform better than traditional regression models for estimating the risk of revision for patients undergoing hip or knee arthroplasty? METHODS: Eleven datasets from published studies from the Dutch Arthroplasty Register reporting on factors associated with revision or survival after partial or total knee and hip arthroplasty between 2018 and 2022 were included in our study. The 11 datasets were observational registry studies, with a sample size ranging from 3038 to 218,214 procedures. We developed a set of time-to-event models for each dataset, leading to 11 comparisons. A set of predictors (factors associated with revision surgery) was identified based on the variables that were selected in the included studies. We assessed the predictive performance of two state-of-the-art statistical time-to-event models for 1-, 2-, and 3-year follow-up: a Fine and Gray model (which models the cumulative incidence of revision) and a cause-specific Cox model (which models the hazard of revision). These were compared with a machine-learning approach (a random survival forest model, which is a decision tree-based machine-learning algorithm for time-to-event analysis). Performance was assessed according to discriminative ability (time-dependent area under the receiver operating curve), calibration (slope and intercept), and overall prediction error (scaled Brier score). Discrimination, known as the area under the receiver operating characteristic curve, measures the model's ability to distinguish patients who achieved the outcomes from those who did not and ranges from 0.5 to 1.0, with 1.0 indicating the highest discrimination score and 0.50 the lowest. Calibration plots the predicted versus the observed probabilities; a perfect plot has an intercept of 0 and a slope of 1. The Brier score calculates a composite of discrimination and calibration, with 0 indicating perfect prediction and 1 the poorest. A scaled version of the Brier score, 1 - (model Brier score/null model Brier score), can be interpreted as the amount of overall prediction error. RESULTS: Using machine learning survivorship analysis, we found no differences between the competing risks estimator and traditional regression models for patients undergoing arthroplasty in terms of discriminative ability (patients who received a revision compared with those who did not). We found no consistent differences between the validated performance (time-dependent area under the receiver operating characteristic curve) of different modeling approaches because these values ranged between -0.04 and 0.03 across the 11 datasets (the time-dependent area under the receiver operating characteristic curve of the models across 11 datasets ranged between 0.52 to 0.68). In addition, the calibration metrics and scaled Brier scores produced comparable estimates, showing no advantage of machine learning over traditional regression models. CONCLUSION: Machine learning did not outperform traditional regression models. CLINICAL RELEVANCE: Neither machine learning modeling nor traditional regression methods were sufficiently accurate in order to offer prognostic information when predicting revision arthroplasty. The benefit of these modeling approaches may be limited in this context.

Time trends in case-mix and risk of revision following hip and knee arthroplasty in public and private hospitals: a cross-sectional analysis based on 476,312 procedures from the Dutch Arthroplasty Register.

BACKGROUND AND PURPOSE: This study aims to assess time trends in case-mix and to evaluate the risk of revision and causes following primary THA, TKA, and UKA in private and public hospitals in the Netherlands. METHODS: We retrospectively analyzed 476,312 primary arthroplasties (public: n = 413,560 and private n = 62,752) implanted between 2014 and 2023 using Dutch Arthroplasty Register data. We explored patient demographics, procedure details, trends over time, and revisions per hospital type. Adjusted revision risk was calculated for comparable subgroups (ASA I/II, age ≤ 75, BMI ≤ 30, osteoarthritis diagnosis, and moderate-high socioeconomic status (SES). RESULTS: The volume of THAs and TKAs in private hospitals increased from 4% and 9% in 2014, to 18% and 21% in 2022. Patients in private hospitals were younger, had lower ASA classification, lower BMI, and higher SES compared with public hospital patients. In private hospitals, age and ASA II proportion increased over time. Multivariable Cox regression demonstrated a lower revision risk for primary THA (HR 0.7, CI 0.7-0.8), TKA (HR 0.8, CI 0.7-0.9), and UKA (HR 0.8, CI 0.7-0.9) in private hospitals. After initial arthroplasty in private hospitals, 49% of THA and 37% of TKA revisions were performed in public hospitals. CONCLUSION: Patients in private hospitals were younger, had lower ASA classification, lower BMI, and higher SES com-pared with public hospital patients. The number of arthroplasties increased in private hospitals, with a lower revision risk compared with public hospitals.

Similar revision rate after cemented and cementless femoral revisions for periprosthetic femoral fractures in total hip arthroplasty: analysis of 1,879 revision hip arthroplasties in the Dutch Arthroplasty Register.

BACKGROUND AND PURPOSE: Periprosthetic femoral fracture (PPF) after total hip arthroplasty (THA) is a serious complication, as it often is followed by functional deficits and morbidity. There is no consensus regarding the optimal stem fixation method and whether additional cup replacement is beneficial. The aim of our study was to perform a direct comparison of reasons and risk of re-revision between cemented and uncemented revision THAs following PPF using registry data. PATIENTS AND METHODS: 1,879 patients registered in the Dutch Arthroplasty Registry (LROI) who underwent a first-time revision for PPF between 2007 and 2021 (cemented stem: n = 555; uncemented stem: n = 1,324) were included. Competing risk survival analysis and multivariable Cox proportional hazard analyses were performed. RESULTS: 5- and 10-year crude cumulative incidence of re-revision following revision for PPF was similar between cemented (resp. 13%, 95% CI 10-16 and 18%, CI 13-24) and uncemented (resp. 11%, CI 10-13 and 13%, CI 11-16) revisions. Multivariable Cox regression analysis, adjusting for potential confounders, showed a similar risk of revision for uncemented and cemented revision stems. Finally, we found no difference in risk of re-revision between a total revision (HR 1.2, 0.6-2.1) compared with a stem revision. CONCLUSION: We found no difference in the risk of re-revision between cemented and uncemented revision stems after revision for PPF.

Revision risk by using the direct superior approach (DSA) for total hip arthroplasty compared with postero-lateral approach: early nationwide results from the Dutch Arthroplasty Register (LROI).

BACKGROUND AND PURPOSE: The direct superior approach (DSA) is a modification of the classic posterolateral approach (PLA) for total hip arthroplasty (THA), in which the iliotibial band and short external rotators are spared. The revision rate of the DSA has not been investigated previously using arthroplasty registry data. We examined the reasons and risk of revision of the DSA, compared with the direct anterior approach (DAA) and PLA. PATIENTS AND METHODS: In this population-based cohort study we included 175,543 primary THAs performed between 2014 and 2020 (PLA, n = 117,576; DAA, n = 56,626; DSA, n = 1,341). Competing risk survival analysis and multivariable Cox proportional hazard analyses, adjusted for potential confounders, were performed. RESULTS: After 3 years, crude revision rates due to any reason were 2.1% (95% confidence interval [CI] 1.3-3.3) for DSA, and 2.9% (CI 2.8-3.0) for PLA. Crude dislocation revision rates were 0.3% (CI 0.1-0.8) for DSA, versus 1.0% (CI 0.9-1.0) for PLA. Dislocation revision rate for DSA did not differ from DAA (0.3% [CI 0.2-0.3]). Multivariable Cox regression analysis demonstrated no overall difference in revision rates for the DSA (HR 0.6 [CI 0.4-1.09) compared with the PLA. Lower risk of revision due to dislocation was found in patients operated on through the DSA (HR 0.3 [0.1-0.9]) compared with the PLA. CONCLUSION: Early nationwide results suggest that the DSA for total hip arthroplasty seems to show a tendency towards a lower risk of revision for dislocation but no overall reduced revision risk compared with the PLA.

No clinically relevant difference in patient-reported outcomes between the direct superior approach and the posterolateral or anterior approach for primary total hip arthroplasty: analysis of 37,976 primary hip arthroplasties in the Dutch Arthroplasty Registry.

BACKGROUND AND PURPOSE: The direct superior approach (DSA) is a modification of the posterolateral approach (PLA) for total hip arthroplasty (THA). Patient-reported outcome measures (PROMs) of the DSA have not been investigated previously using nationwide data. Our aim was to assess PROMs after THA using the DSA compared with the PLA and, secondarily, with the anterior approach (DAA). PATIENTS AND METHODS: In this population-based cohort study we included 37,976 primary THAs performed between 2014 and 2020 (PLA: n = 22,616; DAA: n = 15,017; DSA: n = 343) using Dutch Arthroplasty Registry data. PROMs (NRS pain, EQ-5D, HOOS-PS, and OHS) were measured preoperatively, and at 3 and 12 months postoperatively. Repeated measurements were analyzed using mixed-effects models, adjusted for confounders, to investigate the association between surgical approach and PROMs over time. RESULTS: From baseline to 3 and 12 months, improvements for NRS pain scores, EQ-5D, and OHS were comparable for the DSA compared with the PLA or DAA. No difference was found in HOOS-PS improvement 3 months postoperatively between DSA and PLA (-0.2, 95% confidence interval [CI] -2.4 to 1.9) and between DSA and DAA (-1.7, CI -3.9 to 0.5). At 12 months postoperatively, patients in the DSA group had improved -2.8 points (CI -4.9 to -0.6) more in HOOS-PS compared with the DAA, but not with the PLA group (-1.0, CI -3.2 to 1.1). CONCLUSION: Our study showed no clinically meaningful differences between the DSA and either PLA or DAA.

The learning curve of the direct anterior approach is 100 cases: an analysis based on 15,875 total hip arthroplasties in the Dutch Arthroplasty Register.

BACKGROUND AND PURPOSE: In the last decade, the direct anterior approach (DAA) for total hip arthroplasty (THA) has become more popular in the Netherlands. Therefore, we investigated the learning curve and survival rate of the DAA in primary THA, using data from the Dutch Arthroplasty Register (LROI). PATIENTS AND METHODS: We identified all patients who received a primary THA using the DAA in several high-volume centers in the Netherlands between 2007 and 2019 (n = 15,903). Procedures were ordered per surgeon, using date of operation. Using the procedure number, operations were divided into 6 groups based on the number of previous procedures per surgeon (first 25, 26-50, 51-100, 101-150, 151-200, > 200). Data from different surgeons in different hospitals was pooled together. Revision rates were calculated using a multilevel time-to-event analysis. RESULTS: Patients operated on in group 1-25 (hazard ratio [HR] 1.6; 95% CI 1.1-2.4) and 26-50 (HR 1.6; CI 1.1-2.5) had a higher risk for revision compared with patients operated on in group > 200 THAs. Between 50 and 100 procedures the revision risk was increased (HR 1.3; CI 0.9-1.9), albeit not statistically significant. From 100 procedures onwards the HR for revision was respectively 1.0 (CI 0.6-1.6) and 0.8 (CI 0.5-1.4) for patients in operation groups 101-150 and 151-200. Main reasons for revision were loosening of the stem (29%), periprosthetic infection (19%), and dislocation (16%). INTERPRETATION: We found a 64% increased risk of revision for patients undergoing THA using the DAA for the first 50 cases per surgeon. Between 50 and 100 cases, this risk was 30% increased, but not statistically significant. From 100 cases onwards, a steady state had been reached in revision rate. The learning curve for DAA therefore is around 100 cases.

Patient Characteristics Influence Revision Rate of Total Hip Arthroplasty: American Society of Anesthesiologists Score and Body Mass Index Were the Strongest Predictors for Short-Term Revision After Primary Total Hip Arthroplasty.

BACKGROUND: Outcome and survival after primary total hip arthroplasty (THA) can be affected by patient characteristics. We examined the effect of case-mix on revision after primary THA using the Dutch Arthroplasty Register. METHODS: Our cohort included all primary THAs (n = 218,214) performed in patients with osteoarthritis in the Netherlands between 2007 and 2018. Multivariable logistic regression analysis was used to calculate the difference in survivorship in patients with different patient characteristics (age, gender, American Society of Anesthesiologists [ASA] score, body mass index [BMI], Charnley score, smoking, and previous operations to the hip). RESULTS: Case-mix factors associated with an increased risk for revision 1 year after THA were the following: a high ASA score (II and III-IV) (odds ratio [OR] 1.5, 95% confidence interval [CI] 1.1-2.0 and OR 3.0, 95% CI 1.7-5.3), a higher BMI (30-40 and >40) (OR 1.4, 95% CI 1.2-1.5 and OR 2.0, 95% CI 1.4-1.7), age ≥75 years (OR 1.5, 95% CI 1.1-2.0), and male gender (OR 1.3, 95% CI 1.2-1.4). A similar model for 3-year revision showed comparable results. High BMI (OR 1.9, 95% CI 1.3-2.9), a previous hip operation (OR 1.8, 95% CI 1.3-2.5), ASA III-IV (OR 1.2, 95% CI 1-1.6), and Charnley score C (OR 1.5, 95% CI 1.1-2.2) were associated with increased risk for revision. Main reasons for revision in obese and ASA II-IV patients were infection, dislocation, and periprosthetic fracture. Patients with femoral neck fracture and late post-traumatic pathology were more likely to be revised within 3 years, compared to osteoarthritis patients (OR 1.5, 95% CI 1.3-1.7 and OR 1.5, 95% CI 1.2-1.7). CONCLUSION: The short-term risk for revision after primary THA is influenced by case-mix factors. ASA score and BMI (especially >40) were the strongest predictors for 1-year revision after primary THA. After 3 years, BMI and previous hip surgery were independent risk factors for revision. This will help surgeons to identify and counsel high-risk patients and take appropriate preventive measures.

Predicting omasal flow of nonammonia N and milk protein yield from in vitro-determined utilizable crude protein at the duodenum.

This study evaluated the relationship between utilizable crude protein (uCP) at the duodenum estimated in vitro and omasal flow of crude protein (CP; omasal flow of nonammonia N × 6.25) measured in lactating dairy cows. In vivo data were obtained from previous studies estimating omasal digesta flow using a triple-marker method and 15N as microbial marker. A total of 34 different diets based on grass and red clover silages were incubated with buffered rumen fluid previously preincubated with carbohydrates for 3 h. The buffer solution was modified to contain 38 g of NaHCO3 and 1 g of (NH4)HCO3 in 1,000 mL of distilled water. Continuous sampling of the liquid phase for determination of ammonia-N was performed at 0.5, 4, 8, 12, 24, and 30 h after the start of incubation. The ammonia N concentrations after incubation were used to calculate uCP. The natural logarithm of uCP [g/kg of dry matter (DM)] at time points 0.5, 4, 8, 12, 24, and 30 h of incubation was plotted against time to estimate the concentration of uCP (g/kg of DM) at time points 16, 20, and 24 h using an exponential function. Fixed model regression analysis and mixed model regression analysis with random study effect were used to evaluate the relationships between predicted uCP (supply and concentration) and observed omasal CP flow and milk protein yield. Residual analysis was also conducted to evaluate whether any dietary factors influenced the relationships. The in vitro uCP method ranked the diets accurately in terms of total omasal CP flow (kg/d) or omasal CP flow per kilogram of DM intake. We also noted a close relationship between estimated uCP supply and adjusted omasal CP flow, as demonstrated by a coefficient of determination of 0.87, although the slope of 0.77 indicated that estimated uCP supply (kg/d) was greater than the value determined in vivo. The linear bias with mixed model analysis indicated that uCP supply overestimated the difference in omasal CP flow between the diets within a study, an error most likely related to study differences in feed intake, animals, and methodology. Predicting milk protein yield from uCP supply showed a positive relationship using a mixed model (coefficient of determination = 0.79), and we observed no difference in model fit between the time points of incubation (16, 20, or 24 h). The results of this study indicate that the in vitro method can be a useful tool in evaluating protein value of ruminant diets.

Similar Superior Patient-Reported Outcome Measures for Anterior and Posterolateral Approaches After Total Hip Arthroplasty: Postoperative Patient-Reported Outcome Measure Improvement After 3 months in 12,774 Primary Total Hip Arthroplasties Using the Anterior, Anterolateral, Straight Lateral, or Posterolateral Approach.

BACKGROUND: Patient-reported outcome measures (PROMs) are used to evaluate the outcome of total hip arthroplasty (THA). We determined the effect of surgical approach on PROMs after primary THA. METHODS: All primary THAs, with registered preoperative and 3 months postoperative PROMs were selected from the Dutch Arthroplasty Register. Based on surgical approach, 4 groups were discerned: (direct) anterior, anterolateral, direct lateral, and posterolateral approaches. The following PROMs were recorded: Hip disability and Osteoarthritis Outcome Score Physical function Short form (HOOS-PS); Oxford Hip Score; EQ-5D index score; EQ-5D thermometer; and Numeric Rating Scale measuring pain, both active and in rest. The difference between preoperative and postoperative scores was calculated (delta-PROM) and used as primary outcome measure. Multivariable linear regression analysis was performed for comparisons. Cohen's d was calculated as measure of effect size. RESULTS: All examined 4 approaches resulted in a significant increase of PROMs after primary THA in the Netherlands (n = 12,274). The anterior and posterolateral approaches were associated with significantly more improvement in HOOS-PS scores compared with the anterolateral and direct lateral approaches. Furthermore, the posterolateral and anterior approaches showed greater improvement on Numeric Rating Scale pain scores compared with the anterolateral approach. No relevant differences in delta-PROM were seen between the anterior and posterolateral surgical approaches. CONCLUSION: Anterior and posterolateral surgical approaches showed more improvement in self-reported physical functioning (HOOS-PS) compared with anterolateral and direct lateral approaches in patients receiving a primary THA. However, clinical differences were only small.

The effect of bearing type on the outcome of total hip arthroplasty.

Background and purpose - Alternative bearing surfaces such as ceramics and highly crosslinked polyethylene (HXLPE) were developed in order to further improve implant performance of total hip arthroplasties (THAs). Whether these alternative bearing surfaces result in increased longevity is subject to debate. Patients and methods - Using the Dutch Arthroplasty Register (LROI), we identified all patients with a primary, non-metal-on-metal THA implanted in the Netherlands in the period 2007-2016 (n = 209,912). Cumulative incidence of revision was calculated to determine differences in survivorship of THAs according to bearing type: metal-on-polyethylene (MoPE), metal-on-HXLPE (MoHXLPE), ceramic-on-polyethylene (CoPE), ceramic-on-HXLPE (CoHXLPE), ceramic-on-ceramic (CoC), and oxidized-zirconium-on-(HXL)polyethylene (Ox(HXL)PE). Multivariable Cox proportional hazard regression ratios (HRs) were used for comparisons. Results - After adjustment for confounders, CoHXLPE, CoC, and Ox(HXL)PE resulted in a statistically significantly lower risk of revision compared with MoPE after 9 years follow-up (HR =0.8-0.9 respectively, compared with HR =1.0). For small (22-28 mm) femoral head THAs, lower revision rates were found for CoPE and CoHXLPE (HR =0.9). In the 36 mm femoral head subgroup, CoC-bearing THAs had a lower HR compared with MoHXLPE (HR =0.7 versus 1.0). Crude revision rates in young patients (< 60 years) for CoHXLPE, CoC, and Ox(HXL)PE (HR =0.7) were lower than MoPE (HR =1.0). However, after adjustment for case mix and confounders these differences were not statistically significant. Interpretation - We found a mid-term lower risk of revision for CoHXLPE, CoC, and Ox(HXL)PE bearings compared with traditional MoPE-bearing surfaces.

The relationship between therapist-rated function and patient-reported outcome measures.

STUDY DESIGN: Prospective cohort study. INTRODUCTION: Some third-party payers require hand therapists to rate patient's functional disability based on patient self-rating using patient-reported outcome measures (PROMs), objective measurements of impairment, and observation of functional tasks-hand therapist-rated function (HTRF). PURPOSE OF THE STUDY: To test the correlation between HTRF and PROMs (upper limb functional index [ULFI] and Patient-Reported Outcomes Measurement Information System upper extremity [PROMIS UE]) and its association with psychological factors. METHODS: In 2014, 100 new patients with upper extremity illness presenting to hand therapists were asked to participate in an observational cross-sectional study. Demographic-, condition-related, and psychological factors were obtained in addition to PROMs and HTRF. RESULTS: HTRF correlated moderately with PROMIS UE (r = -0.49, P < .001) and ULFI (r = -0.56, P < .001). Correlation between PROMIS UE and ULFI was strong (r = 0.78, P < .001). Psychological factors explained most of the variations in both HTRF and PROMs. CONCLUSIONS: Hand therapists' ratings of patient function correlate less strongly with PROMs than PROMs correlate with one other. The discrepancy between HTRF and PROMs may offer an opportunity to address stress, distress, or ineffective coping strategies that can interfere with recovery-an opportunity for therapists and patients to collaborate and develop goals and for future research to develop effective and feasible strategies for hand therapists. LEVEL OF EVIDENCE: Level II, diagnostic study.

Factors Associated With Reoperation After Fixation of Displaced Olecranon Fractures.

BACKGROUND: Surgery for fixation of olecranon fractures is associated with reoperation, mostly for implant removal. A study of a large cohort of patients treated by many different surgeons allows us to determine if specific techniques or implants are associated with a higher rate of reoperation. QUESTIONS/PURPOSES: After open reduction and internal fixation of isolated olecranon fractures, what factors are associated with (1) reoperation and (2) implant removal? METHODS: Three hundred ninety-two adult patients who had operative treatment of a displaced olecranon fracture not associated with other fractures, dislocation, or subluxation at two area hospitals between January 2002 and May 2014 were analyzed to determine factors associated with reoperation. One hundred thirty-eight (35%) patients had plate and screw fixation and 254 (65%) tension band wiring. Nearly 100% of patients with displaced olecranon fractures are currently treated operatively at our hospitals. All patients were followed for at least four months. Two hundred three of the 392 (52%) patients were followed for one year or more. Ninety-nine patients (25%) had a second operation, 92 (93%) at least in part for implant removal (12 for wire migration [3% of all fractures, 12% of reoperations]). We considered patient-related, fracture-related, and implant-related endpoints as possible factors associated with reoperation. With a total sample size of 99 reoperations, an α of 0.05, and an effect size of 0.3, we had 87% power. RESULTS: Reoperation was less common in men (36 [36%], women: 63 [64%]; adjusted odds ratio, 0.32; 95% confidence interval, 0.18-0.56; p < 0.001) and older patients (adjusted odds ratio, 0.75; 95% confidence interval, 0.65-0.87; p < 0.001). Similarly, request for implant removal was less in men (33 [36%], women: 59 [64%], adjusted odds ratio, 0.31; 95% confidence interval, 0.18-0.56; p < 0.001) and older patients (adjusted odds ratio, 0.75; 95% confidence interval, 0.65-0.87; p < 0.001). CONCLUSIONS: Patients who have operative fixation of a fracture of the olecranon can be counseled that most patients keep their implants, that only 3% experience implant migration, and that technical factors such as the type or configuration of an implant seem less important than personal factors in determining who requests a second surgery for implant removal. LEVEL OF EVIDENCE: Level III, prognostic study.

Cow-specific diet digestibility predictions based on near-infrared reflectance spectroscopy scans of faecal samples.

This study was designed to obtain information on prediction of diet digestibility from near-infrared reflectance spectroscopy (NIRS) scans of faecal spot samples from dairy cows at different stages of lactation and to develop a faecal sampling protocol. NIRS was used to predict diet organic matter digestibility (OMD) and indigestible neutral detergent fibre content (iNDF) from faecal samples, and dry matter digestibility (DMD) using iNDF in feed and faecal samples as an internal marker. Acid-insoluble ash (AIA) as an internal digestibility marker was used as a reference method to evaluate the reliability of NIRS predictions. Feed and composite faecal samples were collected from 44 cows at approximately 50, 150 and 250 days in milk (DIM). The estimated standard deviation for cow-specific organic matter digestibility analysed by AIA was 12.3 g/kg, which is small considering that the average was 724 g/kg. The phenotypic correlation between direct faecal OMD prediction by NIRS and OMD by AIA over the lactation was 0.51. The low repeatability and small variability estimates for direct OMD predictions by NIRS were not accurate enough to quantify small differences in OMD between cows. In contrast to OMD, the repeatability estimates for DMD by iNDF and especially for direct faecal iNDF predictions were 0.32 and 0.46, respectively, indicating that developing of NIRS predictions for cow-specific digestibility is possible. A data subset of 20 cows with daily individual faecal samples was used to develop an on-farm sampling protocol. Based on the assessment of correlations between individual sample combinations and composite samples as well as repeatability estimates for individual sample combinations, we found that collecting up to three individual samples yields a representative composite sample. Collection of samples from all the cows of a herd every third month might be a good choice, because it would yield a better accuracy.

Nationwide review of mixed and non-mixed components from different manufacturers in total hip arthroplasty.

Background and purpose - Combining components from different manufacturers in total hip arthroplasty (THA) is common practice worldwide. We determined the proportion of THAs used in the Netherlands that consist of components from different manufacturers, and compared the revision rates of these mixed THAs with those of non-mixed THAs. Patients and methods - Data on primary and revision hip arthroplasty are recorded in the LROI, the nationwide population-based arthroplasty register in the Netherlands. We selected all 163,360 primary THAs that were performed in the period 2007-2014. Based on the manufacturers of the components, 4 groups were discerned: non-mixed THAs with components from the same manufacturer (n = 142,964); mixed stem-head THAs with different manufacturers for the femoral stem and head (n = 3,663); mixed head-cup THAs with different head and cup manufacturers (n = 12,960), and mixed stem-head-cup THAs with different femoral stem, head, and cup manufacturers (n = 1,773). Mixed prostheses were defined as THAs (stem, head, and cup) composed of components made by different manufacturers. Results - 11% of THAs had mixed components (n = 18,396). The 6-year revision rates were similar for mixed and non-mixed THAs: 3.4% (95% CI: 3.1w-3.7) for mixed THAs and 3.5% (95% CI: 3.4-3.7) for non-mixed THAs. Revision of primary THAs due to loosening of the acetabulum was more common in mixed THAs (16% vs. 12%). Interpretation - Over an 8-year period in the Netherlands, 11% of THAs had mixed components-with similar medium-term revision rates to those of non-mixed THAs.

Plate and Screw Fixation of Bicolumnar Distal Humerus Fractures: Factors Associated With Loosening or Breakage of Implants or Nonunion.

PURPOSE: To identify factors associated with reoperation for early loosening or breakage of implants or nonunion after operative treatment of AO type C distal humerus fractures. METHODS: We retrospectively analyzed 129 adult patients who had operative treatment of an isolated AO type C distal humerus fracture at 1 of 5 hospitals to determine factors associated with reoperation for early loosening or breakage of implants or nonunion. RESULTS: Within 6 months of original fixation, 16 of 129 fractures (12%) required reoperation for loosening or breakage of implants (n = 8) or nonunion (n = 8). In bivariate analyses, the Charlson comorbidity index, smoking, a coded diagnosis of obesity, diabetes mellitus, and radiographic osteoarthritis were significantly associated with reoperation for early loosening or breakage of implants or nonunion. CONCLUSIONS: With the numbers available, patient factors rather than technical factors were associated with reoperation for loosening or breakage of implants and nonunion. Because of the relative infrequency of fixation problems and nonunion, a much larger study is needed to address technical deficiencies.

Factors associated with radial nerve palsy after operative treatment of diaphyseal humeral shaft fractures.

BACKGROUND: The radial nerve is at risk after diaphyseal humeral fracture or surgery to repair the fracture. We hypothesized that there are no factors associated with iatrogenic radial nerve palsy and, secondarily, that there are no factors associated with traumatic radial nerve palsy or radial nerve palsy of any type. METHODS: We analyzed 325 adult patients who underwent operative treatment of a diaphyseal humerus fracture at 6 hospitals between January 2002 and November 2014 to determine factors associated with a radial nerve palsy. We excluded patients with pathologic fractures, fractures with massive bone loss, prior surgery in another hospital, periprosthetic fractures, and if no operative note was available. RESULTS: In patients without a traumatic radial nerve palsy, an iatrogenic radial nerve palsy occurred in 18 of 259 diaphyseal humeral fractures (7%). The surgical approach was associated with iatrogenic radial nerve palsy (P = .034). No factors were associated with traumatic radial nerve palsy (66 of 325 patients [20%]) of the humeral diaphysis. Open fractures, location of fracture, and high-energy trauma were significantly associated with radial nerve palsy of any type (84 of 325 patients [26%]). CONCLUSIONS: Patients and surgeons should keep in mind that iatrogenic transient dysfunction of the radial nerve will occur in approximately 1 in 5 patients treated with lateral exposure of the humerus, in 1 in 9 patients treated with posterior exposure, and in 1 in 25 patients with an anterolateral exposure.

Femoral Neck Design Does Not Impact Revision Risk After Primary Total Hip Arthroplasty Using a Dual Mobility Cup.

Background: The use of dual mobility (DM) cups has increased quickly. It is hypothesized that femoral neck taper geometry may be involved in the risk of prosthetic impingement and DM cup revision. We aim to (1) explore the reasons for revision of DM cups or head/liners and (2) explore whether certain femoral neck characteristics are associated with a higher risk of revision of DM cups. Methods: Primary total hip arthroplasties with a DM cup registered in the Dutch Arthroplasty Register between 2007 and 2021 were identified (n = 7603). Competing risk survival analyses were performed, with acetabular component and head/liner revision as the primary endpoint. Reasons for revision were categorized in cup-/liner-related revisions (dislocation, liner wear, acetabular loosening). Femoral neck characteristics were studied to assess whether there is an association between femoral neck design and the risk of DM cup/liner revision. Multivariable Cox proportional hazard analyses were performed. Results: The 5- and 10-year crude cumulative incidence of DM cup or head/liner revision for dislocation, wear, and acetabular loosening was 0.5% (CI 0.4-0.8) and 1.9% (CI 1.3-2.8), respectively. After adjusting for confounders, we found no association between the examined femoral neck characteristics (alloy used, neck geometry, CCD angle, and surface roughness) and the risk for revision for dislocation, wear, and acetabular loosening. Conclusions: The risk of DM cup or head/liner revision for dislocation, wear, and acetabular loosening was low. We found no evidence that there is an association between femoral neck design and the risk of cup or head/liner revision.

The Direct Superior Approach in Total Hip Arthroplasty: A Systematic Review.

BACKGROUND: Evolution of the surgical approach for total hip arthroplasty (THA) has led to the development of the minimally invasive direct superior approach (DSA). It is hypothesized that the DSA reduces postoperative pain and hospital length of stay (LOS). We aimed to provide an overview of current evidence on clinical, functional, and radiological outcomes with respect to risk of revision, complications, pain scores, physical function, operative time, LOS, blood loss, radiological outcomes, and learning curve. METHODS: A comprehensive search of Medline, Embase, Web of Science, Cochrane Central Register of Controlled Trials, and Google Scholar, reported according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses literature search extension guidelines, was conducted to identify studies evaluating clinical, functional, and radiological outcomes of the DSA. Quality assessment was performed using the Cochrane Risk of Bias tool and Newcastle-Ottawa Scale. The review protocol was prospectively registered in the International Prospective Registry of Systematic Reviews. RESULTS: Seventeen studies were included, generally of moderate quality. Qualitative synthesis evidenced accurate implant positioning, short LOS, and a short learning curve. Conflicting findings were reported for postoperative complications compared with conventional approaches. Better functional outcomes were seen in the early postoperative period than the posterolateral approach (PLA). Outcomes such as blood loss and operative time exhibited conflicting results and considerable heterogeneity. CONCLUSION: Based on moderate-certainty evidence, it is uncertain if the DSA provides short-term advantages over conventional approaches such as PLA. There is limited evidence on long-term outcomes post-THA using the DSA. Further studies and ongoing registry monitoring is crucial for continuous evaluation of its long-term outcomes. LEVEL OF EVIDENCE: Level III. See Instructions for Authors for a complete description of levels of evidence.