Treatments of Missing Values in Large National Data Affect Conclusions: The Impact of Multiple Imputation on Arthroplasty Research

Anatomic Versus Reverse Total Shoulder Arthroplasty for Primary Osteoarthritis With an Intact Rotator Cuff: A Midterm Comparison of Early Top Performers

BACKGROUND

Several surgeons state that their best anatomic total shoulder arthroplasty (aTSA) outperforms their best reverse total shoulder arthroplasty (rTSA) when performed for rotator cuff-intact glenohumeral osteoarthritis. We identified the top-performing aTSAs and rTSAs at short-term follow-up and compared their clinical performance at midterm follow-up to validate this common claim.

METHODS

A retrospective review of a multicenter shoulder arthroplasty database was conducted. All shoulders undergoing primary aTSA or rTSA for rotator cuff-intact glenohumeral osteoarthritis between 2007 and 2020 were reviewed. Shoulders with a follow-up clinical visit between 2 and 3 years and a clinical follow-up of minimum 5 years were included. Two separate cohorts were identified: patients with a top 20% (1) American Shoulder and Elbow Surgeons (ASES) score and (2) Shoulder Arthroplasty Smart (SAS) score at 2 to 3 years of follow-up. Clinical outcomes including range of motion, outcome scores, and rates of complications and revision surgeries were compared at minimum 5-year follow-up.

RESULTS

The ASES score cohort comprised 185 aTSAs (mean age 67 years, 42% female) and 49 rTSAs (mean age 72 years, 45% female). The SAS score cohort comprised 145 aTSAs (mean age 67 years, 59% female) and 42 rTSAs (mean age 71 years, 57% female). Active external rotation (ER) was greater after aTSA at midterm follow-up in both ASES and SAS score cohorts; however, preoperative to postoperative improvement was equivalent. Postoperative ER and SAS scores were greater after aTSA in both cohorts (P < 0.05); however, no other significant differences in any preoperative or postoperative clinical outcomes were present (P > 0.05), and patients achieved the minimal clinically important difference and substantial clinical benefit at similar rates for all outcomes. No difference was found in the incidence of complications and revision surgeries between top-performing aTSAs and rTSAs.

CONCLUSION

Among top-performing shoulder arthroplasties at early follow-up, aTSA does not appear to outperform rTSA, except superior ER at midterm follow-up.

LEVEL OF EVIDENCE

Retrospective comparative cohort study, Level Ⅲ.

Early outcomes after first reverse total shoulder arthroplasty better prognosticate contralateral success compared with early outcomes after anatomic total shoulder arthroplasty

BACKGROUND

The ideal timing between bilateral total shoulder arthroplasty (TSA) is unclear. The purpose of this study is to determine whether early outcomes after first TSA can be used to predict clinical outcomes after TSA of the contralateral shoulder and to evaluate the ideal time after TSA to perform the contralateral shoulder.

METHODS

A single-institution prospectively collected shoulder arthroplasty database was reviewed. Patients who underwent bilateral primary anatomic or reverse TSA (aTSA + rTSA) without an indication of fracture, tumor, or infection were identified. Included patients had minimum 2-year follow-up on their second TSA and postoperative follow-up after their first TSA at 3 months, 6 months, 1 year, or 2 years. Our primary outcome was whether outcome scores and motion at 3-month, 6-month, 1-year, and 2-year follow-up after first TSA predicted clinical success after second TSA at final follow-up, defined as achieving the patient acceptable symptomatic state (PASS = the highest level of symptoms beyond which patients consider themselves well). Outcomes included the American Shoulder and Elbow Surgeons and Constant scores, abduction, forward elevation, and external/internal-rotation. Multivariable logistic regression determined whether postoperative outcomes after first TSA were predictive of achieving the PASS after second TSA independent of age, sex, and body mass index. Receiver operating characteristic analysis determined cutoffs of postoperative outcomes after first TSA at each time point that best predicted achieving the prosthesis-specific PASS after second TSA.

RESULTS

One hundred thirty-four patients were included in the final analysis (110 aTSA and 158 rTSA). Range of motion and outcome scores at late (1- or 2-year) follow-up after first aTSA were more predictive of achieving the second TSA PASS compared with early (3- or 6-month) outcomes. In contrast, outcomes after early and late follow-up after first rTSA were similarly predictive of achieving the second TSA PASS. Specifically, the Constant score threshold at 2 years after first aTSA (79.4; area under the curve [AUC] = 0.804) better differentiated achieving the second TSA PASS vs. the 6-month threshold (72.0; AUC = 0.600). In contrast, the Constant score threshold at 2 years after first rTSA (76.4; AUC = 0.703) was similarly discriminant of achieving the second TSA PASS compared with the 6-month threshold (65.8; AUC = 0.711).

CONCLUSIONS

Patients with good outcomes after first rTSA can be counseled on contralateral TSA as early as 3 months postoperatively with confidence of a similar result on the contralateral side. In contrast, success after first aTSA does not reliably predict contralateral success until ≥1 year.

Comparison of Pain Scores and Functional Outcomes of Patients Undergoing Arthroscopic Hip Labral Repair and Concomitant Capsular Repair or Plication Versus No Closure

Background

The need for capsular closure during arthroscopic hip labral repair is debated.

Purpose

To compare pain and functional outcomes in patients undergoing arthroscopic hip labral repair with concomitant repair or plication of the capsule versus no closure.

Study Design

Cohort study.

Methods

Outcomes were compared between patients undergoing arthroscopic hip labral repair with concomitant repair or plication of the capsule versus no closure at up to 2 years postoperatively and with stratification by age and sex. Patients with lateral center-edge angle <20°, a history of instability, a history of prior arthroscopic surgery in the ipsilateral hip, or a history of labral debridement only were excluded. Subanalysis was performed between patients undergoing no capsular closure who were propensity score matched 1:1 with patients undergoing repair or plication based on age, sex, and preoperative Modified Harris Hip Score (MHHS). We compared patients who underwent T-capsulotomy with concomitant capsular closure matched 1:5 with patients who underwent an interportal capsulotomy with concomitant capsular repair based on age, sex, and preoperative MHHS.

Results

Patients undergoing capsular closure (n = 1069), compared with the no-closure group (n = 230), were more often female (68.6% vs 53.0%, respectively; P < .001), were younger (36.4 ± 13.3 vs 47.9 ± 14.7 years; P < .001), and had superior MHHS scores at 2 years postoperatively (85.8 ± 14.5 vs 81.8 ± 18.4, respectively; P = .020). In the matched analysis, no difference was found in outcome measures between patients in the capsular closure group (n = 215) and the no-closure group (n = 215) at any follow-up timepoint. No significant difference was seen between the 2 closure techniques at any follow-up timepoint. Patients with closure of the capsule achieved the minimal clinically important difference (MCID) and the patient acceptable symptom state (PASS) for the 1-year MHHS at a similar rate as those without closure (MCID, 50.3% vs 44.9%, P = .288; PASS, 56.8% vs 51.1%, P = .287, respectively). Patients with T-capsulotomy achieved the MCID and the PASS for the 1-year MHHS at a similar rate compared with those with interportal capsulotomy (MCID, 50.1% vs 44.9%, P = .531; PASS, 65.7% vs 61.2%, P = .518, respectively).

Conclusion

When sex, age, and preoperative MHHS were controlled, capsular closure and no capsular closure after arthroscopic hip labral repair were associated with similar pain and functional outcomes for patients up to 2 years postoperatively.

Clinical outcomes of anatomic vs. reverse total shoulder arthroplasty in primary osteoarthritis with preoperative external rotation weakness and an intact rotator cuff: a case-control study

BACKGROUND

Anatomic (aTSA) and reverse total shoulder arthroplasty (rTSA) are well-established treatments for patients with primary osteoarthritis and an intact cuff. However, it is unclear whether aTSA or rTSA provides superior outcomes in patients with preoperative external rotation (ER) weakness.

METHODS

A retrospective review of a prospectively collected shoulder arthroplasty database was performed between 2007 and 2020. Patients were excluded for preoperative diagnoses of nerve injury, infection, tumor, or fracture. The analysis included 333 aTSAs and 155 rTSAs performed for primary cuff-intact osteoarthritis with 2-year minimum follow-up. Defining preoperative ER weakness as strength <3.3 kilograms (7.2 pounds), 3 cohorts were created and matched: (1) weak aTSAs (n = 74) vs. normal aTSAs (n = 74), (2) weak rTSAs (n = 38) vs. normal rTSAs (n = 38), and (3) weak rTSAs (n = 60) vs. weak aTSAs (n = 60). We compared range of motion, outcome scores, strength, complications, and revision rates at the latest follow-up.

RESULTS

Despite weak aTSAs having poorer preoperative strength in forward elevation and ER (P < .001), neither of these deficits persisted postoperatively compared with the normal cohort. Likewise, weak rTSAs had poorer preoperative strength in forward elevation and ER, overhead motion, and Constant, Shoulder Pain and Disability Index, and University of California, Los Angeles scores (P < .029). However, no statistically significant differences were found between preoperatively weak and normal rTSAs. When comparing weak aTSA vs. weak rTSA, no differences were found in preoperative and postoperative outcomes, proportion of patients achieving the minimal clinically important difference and substantial clinical benefit, and complication and rate of revision surgery.

CONCLUSIONS

In preoperatively weak patients with cuff-intact primary osteoarthritis, aTSA leads to similar postoperative strength, range of motion, and outcome scores compared with patients with normal preoperative strength, indicating that preoperative weakness does not preclude aTSA use. Furthermore, patients who were preoperatively weak in ER demonstrated improved postoperative rotational motion after undergoing aTSA and rTSA, with both groups achieving the minimal clinically important difference and substantial clinical benefit at similar rates.

Does achieving clinically important thresholds after first shoulder arthroplasty predict similar outcomes of the contralateral shoulder?

BACKGROUND

Patients are increasingly undergoing bilateral total shoulder arthroplasty (TSA). At present, it is unknown whether success after the first TSA is predictive of success after contralateral TSA. We aimed to determine whether exceeding clinically important thresholds of success after primary TSA predicts similar outcomes for subsequent contralateral TSA.

METHODS

We performed a retrospective review of a prospectively collected shoulder arthroplasty database for patients undergoing bilateral primary anatomic (aTSA) or reverse (rTSA) total shoulder arthroplasty since January 2000 with preoperative and 2- or 3-year clinical follow-up. Our primary outcome was whether exceeding clinically important thresholds in the American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form (ASES) score for the first TSA was predictive of similar success of the contralateral TSA; thresholds for the ASES score were adopted from prior literature and included the minimal clinically important difference (MCID), the substantial clinical benefit (SCB), 30% of maximal possible improvement (MPI), and the patient acceptable symptomatic state (PASS). The PASS is defined as the highest level of symptom beyond which patients consider themselves well, which may be a better indicator of a patient's quality of life. To determine whether exceeding clinically important thresholds was independently predictive of similar success after second contralateral TSA, we performed multivariable logistic regression adjusted for age at second surgery, sex, BMI, and type of first and second TSA.

RESULTS

Of the 134 patients identified that underwent bilateral shoulder arthroplasty, 65 (49%) had bilateral rTSAs, 45 (34%) had bilateral aTSAs, 21 (16%) underwent aTSA/rTSA, and 3 (2%) underwent rTSA/aTSA. On multivariable logistic regression, exceeding clinically important thresholds after first TSA was not associated with greater odds of achieving thresholds after second TSA when success was evaluated by the MCID, SCB, and 30% MPI. In contrast, exceeding the PASS after first TSA was associated with 5.9 times greater odds (95% confidence interval 2.5-14.4, P < .001) of exceeding the PASS after second TSA. Overall, patients who exceeded the PASS after first TSA exceeded the PASS after second TSA at a higher rate (71% vs. 29%, P < .001); this difference persisted when stratified by type of prosthesis for first and second TSA.

CONCLUSIONS

Patients who achieve the ASES score PASS after first TSA have greater odds of achieving the PASS for the contralateral shoulder regardless of prostheses type.

Pain scores and functional outcomes of patients with shoulder labral repair using all-suture anchors versus conventional anchors

HYPOTHESIS/PURPOSE

The purpose of this study was to compare PROMs in patients undergoing anterior glenoid labral repair using all-suture versus conventional anchors. We hypothesized PROMs would be similar between groups.

METHODS

We performed a retrospective review of the Arthrex Global Surgical Outcomes System (SOS) database, querying patients who underwent arthroscopic glenoid labral repair between 01/01/2015 and 12/31/2020. Patients aged 18-100, who had isolated glenoid labrum repair with at least 12-month follow-up were included. The visual analog pain scale (VAS), Western Ontario Shoulder Instability Index, Veteran's RAND 12-items health survey, single assessment numeric evaluation and the American Shoulder and Elbow Surgeons score (ASES) were compared preoperatively, 3 months, 6 months, 1 year and 2 years postoperatively in patients who received all-suture anchors versus conventional anchors in the setting of anterior glenoid labrum repair. Our primary aim was comparison of PROMs between patients receiving all-suture versus conventional suture anchors. Secondarily, a sub-analysis was performed comparing outcomes based on anchor utilization for patients with noted anterior instability.

RESULTS

We evaluated 566 patients, 54 patients receiving all-suture anchors and 512 patients receiving conventional anchors. At two-year follow-up there was no significant difference between the two groups in PROMs. In a sub-analysis of isolated anterior labrum repair, there was an improvement in ASES (P = 0.034) and VAS (P = 0.039) with the all-suture anchor at two-year follow-up.

CONCLUSIONS

All-suture anchors provide similar or superior pain and functional outcome scores up to 2 years postoperatively compared to conventional anchors.

CLINICAL RELEVANCE

As all-suture anchors gain popularity among surgeons, this is the largest scale study to date validating their use in the setting of glenoid labrum repair. Institutional Review Board (IRB): IRB202102550.

Quantifying success after first revision reverse total shoulder arthroplasty: the minimal and substantial clinically important percentage of maximal possible improvement

BACKGROUND

When patients require reoperation after primary shoulder arthroplasty, revision reverse total shoulder arthroplasty (rTSA) is most commonly performed. However, defining clinically important improvement in these patients is challenging because benchmarks have not been previously defined. Furthermore, although the minimal clinically important difference and substantial clinical benefit are commonly used to assess clinically relevant success, these metrics are limited by ceiling effects that may cause inaccurate estimates of patient success. Our purpose was to define the minimal and substantial clinically important percentage of maximal possible improvement (MCI-%MPI and SCI-%MPI) for commonly used pain and functional outcome scores after revision rTSA and to quantify the proportion of patients achieving clinically relevant success.

METHODS

This retrospective cohort study used a prospectively collected single-institution database of patients who underwent first revision rTSA between August 2015 and December 2019. Patients with a diagnosis of periprosthetic fracture or infection were excluded. Outcome scores included the American Shoulder and Elbow Surgeons (ASES), raw and normalized Constant, Shoulder Pain and Disability Index (SPADI), Simple Shoulder Test (SST), and University of California, Los Angeles (UCLA) scores. We used an anchor-based method to calculate the MCI-%MPI and SCI-%MPI. In addition, we calculated the MCI-%MPI using a distribution-based method for historical comparison. The proportions of patients achieving each threshold were assessed. The influence of sex, type of primary shoulder arthroplasty, and reason for revision rTSA were also assessed by calculating cohort-specific thresholds.

RESULTS

Ninety-three revision rTSAs with minimum 2-year follow-up were evaluated. The mean age of the patients was 67 years; 56% were female, and the average follow-up was 54 months. Revision rTSA was performed most commonly for failed anatomic TSA (n = 47), followed by hemiarthroplasty (n = 21), rTSA (n = 15), and humeral head resurfacing (n = 10). The indication for revision rTSA was most commonly glenoid loosening (n = 24), followed by rotator cuff failure (n = 23) and subluxation and unexplained pain (n = 11 for both). The anchor-based MCI-%MPI thresholds (% of patients achieving) were ASES = 33% (49%), raw Constant = 23% (64%), normalized Constant = 30% (61%), UCLA = 51% (53%), SST = 26% (68%), and SPADI = 29% (58%). The anchor-based SCI-%MPI thresholds (% of patients achieving) were ASES = 55% (31%), raw Constant = 41% (27%), normalized Constant = 52% (22%), UCLA = 66% (37%), SST = 74% (25%), and SPADI = 49% (34%).

CONCLUSIONS

This study is the first to establish thresholds for the MCI-%MPI and SCI-%MPI at minimum 2 years after revision rTSA, providing physicians an evidence-based method to assess patient outcomes postoperatively.

Clinical outcomes of anatomical versus reverse total shoulder arthroplasty in patients with primary osteoarthritis, an intact rotator cuff, and limited forward elevation

Aims

Both anatomical and reverse total shoulder arthroplasty (aTSA and rTSA) provide functional improvements. A reported benefit of aTSA is better range of motion (ROM). However, it is not clear which procedure provides better outcomes in patients with limited foward elevation (FE). The aim of this study was to compare the outcome of aTSA and rTSA in patients with glenohumeral osteoarthritis (OA), an intact rotator cuff, and limited FE.

Methods

This was a retrospective review of a single institution's prospectively collected shoulder arthroplasty database for TSAs undertaken between 2007 and 2020. A total of 344 aTSAs and 163 rTSAs, which were performed in patients with OA and an intact rotator cuff with a minimum follow-up of two years, were included. Using the definition of preoperative stiffness as passive FE ≤ 105°, three cohorts were matched 1:1 by age, sex, and follow-up: stiff aTSAs (85) to non-stiff aTSAs (85); stiff rTSAs (74) to non-stiff rTSAs (74); and stiff rTSAs (64) to stiff aTSAs (64). We the compared ROMs, outcome scores, and complication and revision rates.

Results

Compared with non-stiff aTSAs, stiff aTSAs had poorer passive FE and active external rotation (ER), whereas there were no significant postoperative differences between stiff rTSAs and non-stiff rTSAs. There were no significant differences in preoperative function when comparing stiff aTSAs with stiff rTSAs. However, stiff rTSAs had significantly greater postoperative active and passive FE (p = 0.001 and 0.004, respectively), and active abduction (p = 0.001) compared with stiff aTSAs. The outcome scores were significantly more favourable in stiff rTSAs for the Shoulder Pain and Disability Index, Simple Shoulder Test, American Shoulder and Elbow Surgeons score, University of California, Los Angeles score, and the Constant score, compared with stiff aTSAs. When comparing the proportion of stiff aTSAs versus stiff rTSAs that exceeded the minimal clinically important difference and substantial clinical benefit, stiff rTSAs achieved both at greater rates for all measurements except active ER. The complication rate did not significantly differ between stiff aTSAs and stiff rTSAs, but there was a significantly higher rate of revision surgery in stiff aTSAs (p = 0.007).

Conclusion

Postoperative overhead ROM, outcome scores, and rates of revision surgery favour the use of a rTSA rather than aTSA in patients with glenohumeral OA, an intact rotator cuff and limited FE, with similar rotational ROM in these two groups.

Does interaction occur between risk factors for revision total knee arthroplasty?

INTRODUCTION

Several risk factors for revision TKA have previously been identified, but interactions between risk factors may occur and affect risk of revision. To our knowledge, such interactions have not been previously studied. As patients often exhibit multiple risk factors for revision, knowledge of these interactions can help improve risk stratification and patient education prior to TKA.

MATERIALS AND METHODS

The State Inpatient Databases (SID), part of the Healthcare Cost and Utilization Project (HCUP), were queried to identify patients who underwent TKA between January 1, 2006 and December 31, 2015. Risk factors for revision TKA were identified, and interactions between indication for TKA and other risk factors were analyzed.

RESULTS

Of 958,944 patients who underwent TKA, 33,550 (3.5%) underwent revision. Age, sex, race, length of stay, Elixhauser readmission score, urban/rural designation, and indication for TKA were significantly associated with revision (p < 0.05). Age was the strongest predictor (p  < 0.0001), with younger patients exhibiting higher revision risk. Risks associated with age were modified by an interaction with indication for TKA (p < 0.0001). There was no significant interaction between sex and indication for TKA (p = 0.535) or race and indication for TKA (p = 0.187).

CONCLUSIONS

Age, sex, race, length of stay, Elixhauser readmission score, urban/rural designation, and indication for TKA are significantly associated with revision TKA. Interaction occurs between age and indication.

Quantifying success after first revision reverse total shoulder arthroplasty: the minimal clinically important difference, substantial clinical benefit, and patient acceptable symptomatic state

BACKGROUND

When patients require revision of primary shoulder arthroplasty, revision reverse total shoulder arthroplasty (rTSA) is most commonly performed. However, defining clinically important improvement in these patients is challenging because benchmarks have not been previously defined. Our purpose was to define the minimal clinically important difference (MCID), substantial clinical benefit (SCB), and patient acceptable symptomatic state (PASS) for outcome scores and range of motion (ROM) after revision rTSA and to quantify the proportion of patients achieving clinically relevant success.

METHODS

This retrospective cohort study used a prospectively collected single-institution database of patients undergoing first revision rTSA between August 2015 and December 2019. Patients with a diagnosis of periprosthetic fracture or infection were excluded. Outcomes scores included the ASES, raw and normalized Constant, SPADI, SST, and University of California, Los Angeles (UCLA) scores. ROM measures included abduction, forward elevation (FE), external rotation (ER), and internal rotation (IR) score. Anchor-based and distribution-based methods were used to calculate the MCID, SCB, and PASS. The proportions of patients achieving each threshold were assessed.

RESULTS

Ninety-three revision rTSAs with minimum 2-year follow-up were evaluated. Mean age was 67 years, 56% were female, and average follow-up was 54 months. Revision rTSA was performed most commonly for failed anatomic TSA (n = 47), followed by hemiarthroplasty (n = 21), rTSA (n = 15), and resurfacing (n = 10). The indication for revision rTSA was most commonly glenoid loosening (n = 24), followed by rotator cuff failure (n = 23), subluxation and unexplained pain (n = 11 for both). The anchor-based MCID thresholds (% of patients achieving) were as follows: ASES, 20.1 (42%); normalized Constant, 12.6 (80%); UCLA, 10.2 (54%); SST, 0.9 (78%); SPADI, -18.4 (58%); abduction, 13° (83%); FE, 18° (82%); ER, 4° (49%); and IR, 0.8 (34%). The SCB thresholds (% of patients achieving) were as follows: ASES, 34.1 (25%); normalized Constant, 26.6 (43%); UCLA, 14.1 (28%); SST, 3.9 (48%); SPADI, -36.4 (33%); abduction, 20° (77%); FE, 28° (71%); ER, 15° (15%); and IR, 1.0 (29%). The PASS thresholds (% of patients achieving) were as follows: ASES, 63.5 (53%); normalized Constant, 59.1 (61%); UCLA, 25.4 (48%); SST, 7.0 (55%); SPADI, 42.4 (59%); abduction, 98° (61%); FE, 110° (56%); ER, 19° (73%); and IR, 3.3 (59%).

CONCLUSIONS

This study establishes thresholds for the MCID, SCB, and PASS at minimum 2-years after revision rTSA, providing physicians an evidence-based method to counsel patients and assess patient outcomes postoperatively.

[Evidence-based versus expertise-based medicine in orthopedic and trauma surgery : There is nothing more practical than a good theory]

About a quarter of a century after the introduction of the concept and principles of evidence-based medicine (EbM), some healthcare providers are still adamant that these are incompatible with knowledge gained through experience. Across the surgical disciplines, it is often argued EbM underestimates or neglects the importance of intuition and surgical skills. To put it bluntly, these assumptions are wrong and often characterized by a misunderstanding of the methodology of EbM. Even the best controlled trial cannot be properly interpreted or implemented without clinical reasoning; furthermore, clinicians of all disciplines are obligated to provide care according to the current state of scientific knowledge. In an era of revolutionary biomedical developments, exponential increase of research but incremental innovations, they must become familiar with pragmatic tools to appraise the validity and relevance of clinical study results, and to decide whether there is a need to adapt current beliefs and practices based on the new information. We herein use the recent example of a new medical device for the surgical treatment of rotator cuff tears and subacromial impingement syndrome to illustrate how important it is to interpret data in the context of a precise, answerable question and to combine clinical expertise with methodological principles offered by EbM.

Incidence, Risk Factors, and Subsequent Complications of Postoperative Hematomas Requiring Reoperation After Primary Total Hip Arthroplasty

Background

Studies analyzing the incidence and clinical implications of postoperative hematomas after total hip arthroplasty (THA) remain limited. The purpose of the present study was to use the National Surgical Quality Improvement Program (NSQIP) dataset to determine rates, risk factors, and subsequent complications of postoperative hematomas requiring reoperation after primary THA.

Methods

Study population included patients who underwent primary THA (CPT code: 27130) from 2012-2016 recorded in NSQIP. Patients who developed a hematoma requiring reoperation in the 30-day postoperative period were identified. Multivariate regressions were created to identify patient characteristics, operative variables, and subsequent complications that were associated with a postoperative hematoma requiring reoperation.

Results

Among the 149,026 patients who underwent primary THA, 180 (0.12%) developed a postoperative hematoma requiring reoperation. Risk factors included body mass index (BMI) ≥ 35 (relative risk [RR]: 1.83, P = .011), American Society of Anesthesiologists (ASA) class ≥3 (RR: 2.11, P < .001), and history of bleeding disorder (RR: 2.71, P < .001). Associated intraoperative characteristics were an operative time ≥100 minutes (RR: 2.03, P < .001) and use of general anesthesia (RR: 1.41, P = .028). Patients developing a hematoma requiring reoperation were at higher risk of subsequent deep wound infection (RR: 21.57, P < .001), sepsis (RR: 4.3, P = .012), and pneumonia (RR: 3.69, P = .023).

Conclusions

Surgical evacuation for a postoperative hematoma was performed in about 1 in 833 cases of primary THA. Several nonmodifiable and modifiable risk factors were identified. Given the 21.6 times increased risk of subsequent deep wound infection, select, at-risk patients may benefit from closer monitoring for signs of infection.

Impact of Missing Data on Identifying Risk Factors for Postoperative Complications in Hand Surgery

BACKGROUND

The mismanagement of missing data in large clinical databases may lead to inaccurate findings. The purpose of this study was to demonstrate the effects of missing data on hand surgery research findings using an analysis of postoperative morbidity in patients undergoing hospital-based hand surgery.

METHODS

The National Surgical Quality Improvement Program database was queried for patients undergoing common hand and upper extremity surgery between 2011 and 2016. Major and minor postoperative complications were identified. Demographics, comorbidity, and preoperative laboratory values were identified, and the percentage missing of each was tabulated. To demonstrate how missing data can alter analysis results, these variables were evaluated for an association with major complications using multivariable regression on 3 separate cohorts: (1) all patients; (2) all patients after exclusion of any patient entry with >10% of missing data; and (3) after removal of any patient entry with any missing data.

RESULTS

Groups 1, 2, and 3 had 48 370, 23 118, and 6280 patients, respectively. There were 14 variables associated with increased odds of major complications in group 1, yet only 10 and 9 variables for groups 2 and 3, respectively. Six variables were associated with increased major complications across all 3 groups, whereas only 1 was associated with decreased odds of major complications across all groups.

CONCLUSIONS

Filtering patient cohorts according to the amount of missing patient information affected analyses of predictors for major complications associated with hospital-based hand surgery. These findings highlight the importance of considering and addressing missing data in large database studies.

Hip Resurfacing vs Total Hip Arthroplasty in Patients Younger than 35 Years: A Comparison of Revision Rates and Patient-Reported Outcomes

Background

Hip resurfacing arthroplasty (HRA) and total hip arthroplasty (THA) are two treatment options for end-stage degenerative hip conditions. The objective of this single-center retrospective cohort study was to compare implant survival and patient-reported outcomes (PROs) in young patients (≤35 years) who underwent HRA or THA.

Methods

All patients aged 35 years or younger who underwent HRA or THA with a single high-volume arthroplasty surgeon between 2004 and 2015 were reviewed. The sample included 33 THAs (26 patients) and 76 HRAs (65 patients). Five-year implant survival and minimum 2-year PROs were compared between patient cohorts.

Results

Three patients in the THA group (9%) were revised within 5 years for instability (n = 1), squeaking (n = 1), or squeaking with a ceramic liner fracture (n = 1). No patients who underwent HRA were revised. The University of California, Los Angeles, activity score, modified Harris Hip score, and Hip Dysfunction and Osteoarthritis Outcome Scores for Joint Replacement increased by 74%, 64%, and 49%, respectively, among all patients. Compared to the HRA cohort, patients who underwent THA had lower preoperative and postoperative University of California, Los Angeles, activity, modified Harris Hip score, and Hip Dysfunction and Osteoarthritis Outcome Scores for Joint Replacement scores, yet there were no differences in the absolute improvements in any of the three measures between the two groups.

Conclusions

Excellent functional outcomes were seen in young patients undergoing either HRA or THA. Although young patients undergoing THA started at lower preoperative baseline and postoperative PROs than patients undergoing HRA, both groups improved by an equal amount after surgery, suggesting that both HRA and THA afford a similar degree of potential improvement in a young population.

Preoperative laboratory testing for total hip arthroplasty: Unnecessary tests or a helpful prognosticator

BACKGROUND

The last decade has seen increasing initiatives to improve health care delivery while decreasing financial expenditures, as particularly exemplified by the implementation of bundled payments for lower extremity arthroplasty, which hold the providers responsible for the both the quality and cost of these procedures. In this context, the utility of routine preoperative laboratory testing is unknown. The present study characterizes the associations, if any, between preoperative sodium, blood urea nitrogen (BUN), and creatinine values and the occurrence of general health adverse outcomes following total hip arthroplasty (THA).

METHODS

Patients undergoing primary THA were identified in the 2011-2015 National Surgical Quality Improvement Program. Cases with traumatic, oncologic, or infectious indications were excluded. Preoperative levels of sodium, BUN, and creatinine were tested for associations with perioperative adverse events and adverse hospital metrics using multivariate regressions that adjusted for patient baseline characteristics.

RESULTS

A total of 92,093 patients were included, of which 5.25% had an abnormal preoperative sodium level, 24.20% had an abnormal preoperative BUN level, and 11.95% had an abnormal preoperative creatinine level. Abnormal preoperative sodium levels (odds ratios: 1.23-1.50, p < 0.007) and creatinine levels (odds ratios: 1.27-1.55, p < 0.007) were associated with the occurrence of all studied adverse outcomes and abnormal preoperative BUN levels (odds ratios: 1.15-1.52, p < 0.007) were associated with the occurrence of all adverse outcomes except for hospital readmission.

CONCLUSIONS

Abnormal preoperative laboratory testing is significantly associated with adverse outcomes following THA, supporting the added value of laboratory evaluation of patients before elective arthroplasty procedures.

STUDY DESIGN

Clinical, Level III.

A novel weighted distance threshold method for handling medical missing values

Data in the medical field often contain missing values and may result in biased research results. Therefore, the objective of this work is to propose a new imputation method, a novel weighted distance threshold method, to impute missing values. After several experiments, we find that the proposed imputation method has the following benefits. (1) The proposed method with purity can reassign instances into the nearest class of the dataset, and the purity computation can filter outliers; (2) The proposed method redefines the degree of missing values and can determine attributes and instances relative to the missing values in different datasets; and (3) The proposed method need not set the k value of the nearest neighborhood because this study identifies the k value based on the best threshold to calculate purity to enhance the results of imputation. In addition, the distance threshold can adjust the optimal nearest neighborhood to estimate missing values. This study implements several experiments to compare the proposed method with other imputation methods using different missing types, missing degrees, and types of datasets. The results indicate that the proposed imputation method is better than the listed methods. Moreover, this study uses the stroke dataset from the International Stroke Trial (IST) to verify whether the proposed method can be effectively applied in practice, and the results show that the proposed method achieves 90% accuracy in the Stroke dataset.

What Associations Exist Between Comorbidity Indices and Postoperative Adverse Events After Total Shoulder Arthroplasty?

BACKGROUND

Comorbidity indices like the modified Charlson Comorbidity Index (mCCI) and the modified Frailty Index (mFI) are commonly reported in large database outcomes research. It is unclear if they provide greater association and discriminative ability for postoperative adverse events after total shoulder arthroplasty (TSA) than simple variables.

QUESTIONS/PURPOSES

Using a large research database to examine postoperative adverse events after anatomic and reverse TSA, we asked: (1) Which demographic/anthropometric variable among age, sex, and body mass index (BMI) has the best discriminative ability as measured by receiver operating characteristics (ROC)? (2) Which comorbidity index, among the American Society of Anesthesiologists (ASA) classification, the mCCI, or the mFI, has the best ROC? (3) Does a combination of a demographic/anthropometric variable and a comorbidity index provide better ROC than either variable alone?

METHODS

Patients who underwent TSA from 2005 to 2015 were identified from the National Surgical Quality Improvement Program (NSQIP). This multicenter database with representative samples from more than 600 hospitals in the United States was chosen for its prospectively collected data and documented superiority over administrative databases. Of an initial 10,597 cases identified, 70 were excluded due to missing age, sex, height, weight, or being younger than 18 years of age, leaving a total of 10,527 patients in the study. Demographics, medical comorbidities, and ASA scores were collected, while BMI, mCCI and mFI were calculated for each patient. Though all required data variables were found in the NSQIP, the completeness of data elements was not determined in this study, and missing data were treated as being the null condition. Thirty-day outcomes included postoperative severe adverse events, any adverse events, extended length of stay (LOS, defined as > 3 days), and discharge to a higher level of care. ROC analysis was performed for each variable and outcome, by plotting its sensitivity against one minus the specificity. The area under the curve (AUC) was used as a measure of model discriminative ability, ranging from 0 to 1, where 1 represents a perfectly accurate test, and 0.5 indicates a test that is no better than chance.

RESULTS

Among demographic/anthropometric variables, age had a higher AUC (0.587-0.727) than sex (0.520-0.628) and BMI (0.492-0.546) for all study outcomes (all p < 0.050), while ASA (0.580-0.630) and mFI (0.568-0.622) had higher AUCs than mCCI (0.532-0.570) among comorbidity indices (all p < 0.050). A combination of age and ASA had higher AUCs (0.608-0.752) than age or ASA alone for any adverse event, extended LOS, and discharge to higher level of care (all p < 0.05). Notably, for nearly all variables and outcomes, the AUCs showed fair or moderate discriminative ability at best.

CONCLUSION

Despite the use of existing comorbidity indices adapted to large databases such as the NSQIP, they provide no greater association with adverse events after TSA than simple variables such as age and ASA status, which have only fair associations themselves. Based on database-specific coding patterns, the development of database- or NSQIP-specific indices may improve their ability to provide preoperative risk stratification.

LEVEL OF EVIDENCE

Level III, diagnostic study.

Unlike Native Hip Fractures, Delay to Periprosthetic Hip Fracture Stabilization Does Not Significantly Affect Most Short-Term Perioperative Outcomes

BACKGROUND

The incidence of periprosthetic hip fractures is increasing due to higher numbers of total hip arthroplasties being performed. Unlike native hip fractures, the effect of time to surgery of periprosthetic hip fractures is not well established. This study evaluates the effect of time to surgery on perioperative complications for patients with periprosthetic hip fractures.

METHODS

Patients who underwent surgery for periprosthetic hip fracture were identified in the 2005-2016 National Surgical Quality Improvement Program database and stratified into 2 groups: <2 and ≥2 days from hospital admission to surgery. Multivariate regressions were used to compare risk for perioperative complications between the 2 groups. Independent risk factors for postoperative serious adverse events were characterized.

RESULTS

In total, 409 (<2 days from admission to surgery) and 272 (≥2 days from admission to surgery) patients were identified. Multivariate analysis revealed only higher risk of extended postoperative stay for patients who had delays of ≥2 days to surgery compared to those who had <2 days from admission to surgery. Independent risk factors for serious adverse events included increasing age, dependent preoperative functional status, and preoperative congestive heart failure, but not time to surgery.

CONCLUSION

Unlike for native hip fractures, time to surgery for periprosthetic hip fractures does not appear to affect most 30-day perioperative complications. However, it is worth noting that this study was unable to control for all potential confounders and therefore the results may not be generalizable to all types of periprosthetic hip fractures.

Can a power law improve prediction of pain recovery trajectory?

Introduction:

Chronic pain results from complex interactions of different body systems. Time-dependent power laws have been used in physics, biology, and social sciences to identify when predictable output arises from complex systems. Power laws have been used successfully to study nervous system processing for memory, but there has been limited application of a power law describing pain recovery.

Objective:

We investigated whether power laws can be used to characterize pain recovery trajectories.

Methods:

This review consists of empirical examples for an individual with complex regional pain syndrome and prediction of 12-month pain recovery outcomes in a cohort of patients seeking physical therapy for musculoskeletal pain. For each example, mathematical power-law models were fitted to the data.

Results:

This review demonstrated how a time-dependent power law could be used to refine outcome prediction, offer alternate ways to define chronicity, and improve methods for imputing missing data.

Conclusion:

The overall goal of this review was to introduce new conceptual direction to improve understanding of chronic pain development using mathematical approaches successful for other complex systems. Therefore, the primary conclusions are meant to be hypothesis generating only. Future research will determine whether time-dependent power laws have a meaningful role in improving strategies for predicting pain outcomes.