Unplanned Reoperation and Implant Revision After Total Wrist Arthroplasty

Background: Total wrist arthroplasty (TWA) is a treatment option for many debilitating wrist conditions. With recent improvements in implant design, indications for TWA have broadened. However, despite these improvements, there are still complications associated with TWA, such as unplanned reoperation and eventual implant removal. The goal of this study was to identify risk factors for an unplanned reoperation or implant revision after a TWA at 2 academic medical centers between 2002 and 2015. Methods: In this retrospective study, 24 consecutive TWAs were identified using CPT codes. Medical records were manually reviewed to identify demographic, patient- or disease-related, and surgery-related risk factors for reoperation and implant removal after a primary TWA. Results: Forty-six percent of wrists (11 of 24 TWAs performed) had a reoperation after a median of 3.4 years, while 29% (7 of 24) underwent implant revision after a median of 5 years. Two patients had wrist surgery prior to their TWA, both eventually had their implant removed (P = .08). There were no risk factors associated with reoperation or implant removal. Conclusion: Unplanned reoperation and implant removal after a primary TWA are common. Approximately 1 in 3 wrists are likely to undergo revision surgery. We found no factors associated with reoperation or implant removal; however, prior wrist surgery showed a trend toward risk of implant removal after TWA.

Radial Shortening Osteotomy for Symptomatic Kienböck's Disease: Complications and Long-Term Patient-Reported Outcome

Objective  To determine the rate of salvage procedures and any other unplanned reoperations in patients with symptomatic Kienböck's disease who were treated with radial shortening osteotomy. In addition, we studied patient-reported outcome in the long term using Patient-Reported Outcome Measure Information System (PROMIS) instruments. Patients and Methods  We performed a retrospective review of all patients who underwent radial shortening osteotomy for stage 2 and 3A Kienböck's disease. Patients who had concomitant revascularization were grouped separately. We collected demographic data, data regarding type of surgery and reoperations, and radiographic data. Patient-reported outcome measures were the PROMIS Upper Extremity Computer Adaptive Testing (CAT) and Pain Interference instruments, the abbreviated Disabilities of Arm, Shoulder, and Hand (QuickDASH), and the 0 to 10 numeric rating scale for pain and satisfaction. Results  We included 48 patients who had radial shortening osteotomy alone, and 17 patients who had a combined procedure of radial shortening and direct revascularization. The rate of unplanned reoperations was 33% (16 of 48) in those who had radial shortening osteotomy and 24% (4 of 17) in those who had a combined procedure. Six (13%) of 48 patients underwent proximal row carpectomy due to failed radial shortening osteotomy. No salvage procedures were performed after combined radial shortening/revascularization. Median PROMIS Physical Function CAT scores were 56 (interquartile range [IQR]: 44-56) and 56 (IQR: 41-56), respectively. Median PROMIS Pain Interference scores were 39 (IQR: 39-52) and 39 (IQR: 39-49), respectively. Median QuickDASH scores were 2.3 (IQR: 0-23) and 4.5 (IQR: 2.3-14), respectively. Conclusion  Radial shortening osteotomy for symptomatic Kienböck's disease yields reasonable long-term function. We observed that approximately one in eight patients underwent salvage surgery after radial shortening, and this should be taken into account when making the initial decision to treat Kienböck's disease surgically. There appeared to be no benefit of direct revascularization in addition to radial shortening in terms of patient-reported outcome in the long term. Level of Evidence  This is a Level IV, therapeutic study.

Scaphoid Fracture Patterns-Part Two: Reproducibility and Demographics of a Simplified Scaphoid Fracture Classification

Objective  To analyze the reproducibility, reliability, and demographics of a simplified anatomical scaphoid fracture classification based on posteroanterior radiographs using a large database of scaphoid fractures. Methods  The study consisted of a retrospective review of electronic medical records of 871 consecutive patients. All patients presented between 2003 and 2014 at two centers. Patient- and surgeon-related factors were analyzed. Additionally, interobserver reliability of the Herbert and simplified scaphoid fracture classifications were tested. Results  Proximal pole fractures were defined as fractures in which the center of the fracture line was proximal to the distal scapholunate interval (n = 30), waist fractures (n = 802) were defined as fractures involving the scaphocapitate interval, and distal tubercle fractures (n = 39) were defined as fractures involving the scaphotrapeziotrapezoid (STT) interval. The interobserver reliability of the simplified classification was fair (κ = 0.37) as for the Herbert classification (κ = 0.31). The average doubt of the answers of the observers was 2.1 on a scale from 0 to 10 for the simplified classification and 3.6 for the Herbert classification ( P  < 0.05). Conclusions  All complete fractures across the entire scaphoid distal to the scapholunate articulation and proximal to the STT joint can be classified as waist fractures; nonwaist scaphoid fractures are uncommon (6%) and have somewhat different presentations compared to waist fractures. Simplifying the fracture classification slightly improves interobserver reliability, although remaining fair, and significantly reduces doubt. Level of Evidence  This is a Level III, prognostic study.

An Anatomical Study to the Branching Pattern of the Posterior Interosseous Nerve on the Dorsal Side of the Hand

Partial denervation of the wrist can benefit patients with chronic wrist pain. A complication of partial denervation is loss of proprioception and hypesthesia on the dorsal side of the hand. Our aim is to evaluate whether the sensory branches of the posterior interosseous nerve could contribute to the loss of proprioception and sensation. The branching pattern of the posterior interosseous nerve was studied in 20 cadaveric hands. The terminal branches of the posterior interosseous nerve reached the metacarpophalangeal joints in three specimens (15%), the midshaft of the metacarpals in three specimens (15%), carpometacarpal joints in 11 specimens (55%), and the scapholunate joint in three specimens (15%). The finding that terminal branches of the posterior interosseous nerve can reach the metacarpals and the metacarpophalangeal joints indicates that the posterior nerve may contribute to the proprioception and sensation of the dorsal side of the hand. Clin. Anat., 33:678-682, 2020. © 2019 Wiley Periodicals, Inc.

Unplanned Reoperation After Surgery for Scapholunate Interosseous Ligament Insufficiency: A Retrospective Review of 316 Patients

Background: The purpose of this study was to identify factors associated with unplanned reoperation after surgery for scapholunate interosseous ligament (SLIL) insufficiency. Methods: Using Current Procedural Terminology (CPT) codes from 3 hand surgery centers across 2 metropolitan areas, we identified 316 patients undergoing surgery for SLIL insufficiency from 2000 to 2014. Medical records were manually reviewed to collect data on factors that might be associated with unplanned reoperation, including age, sex, tobacco use, occupation, acuity of treatment, and reconstruction method. Results: Thirty-eight patients (12%) had an unplanned reoperation; most of them (65%) were a secondary reconstruction or salvage procedure (eg, 6 proximal row carpectomies, 9 revision reconstruction, and 10 partial carpal arthrodeses), while 5 (13%) were for unplanned screw removal. The median time between the index and second surgery was 16 months (range, 2-97 months). The type of index procedure was not associated with reoperation. The only factor associated with reoperation was cigarette smoking, and this association persisted when looking specifically at reoperations for revision or salvage. Conclusions: Patients should be counseled that smoking is associated with reoperation after SLIL surgery. Smoking cessation or decreasing nicotine usage may be beneficial prior to surgery. With the numbers available, there was no association between surgical technique and reoperation.

The Prevalence of Triangular Fibrocartilage Complex Signal Abnormalities on Magnetic Resonance Imaging Relative to Clinical Suspicion of Pathology

PURPOSE

To determine the prevalence of triangular fibrocartilage complex (TFCC) signal changes in patients undergoing magnetic resonance imaging (MRI) of the wrist and its relationship to a clinical suspicion of TFCC pathology. The secondary purpose was to study factors that are associated with TFCC signal changes.

METHODS

In this retrospective study, we looked for any TFCC signal changes in the reports of MRI findings performed during a 3-year period in 1,134 patients. Demographic characteristics, the categorized indications for MRI, and symptoms at the time of the MRI were also retrieved from the medical records. Patients were divided into 6 groups, based on age, to calculate the proportions of TFCC signal changes in the entire cohort and as an incidental finding among patients without a clinical suspicion of TFCC pathology within each age group.

RESULTS

A total of 321 patients (28%) had incidental TFCC signal changes. The prevalence among 18- to 30 year-olds was 19%, and increased to 64% in patients older than 70 years. Multivariable logistic regression analysis demonstrated that an increase in age is significantly associated with having TFCC signal changes on MRI in patients who have a low clinical suspicion of TFCC pathology. The rate of incidental TFCC signal changes steadily increases with age.

CONCLUSIONS

The TFCC signal abnormalities on MRI are more common with increasing age in patients with low clinical suspicion of TFCC pathology. At age 70, more than half of all patients will have TFCC signal changes, and more than 90% are present in patients with a low clinical suspicion of TFCC pathology.

TYPE OF STUDY/LEVEL OF EVIDENCE

Diagnostic IV.

Variation in Repair of the Triangular Fibrocartilage Complex

Background  There is controversy regarding the value of repair of the triangular fibrocartilage complex (TFCC). Given that an acute tear of the TFCC associated with a displaced distal radius fracture uncommonly benefits from repair, the role of repair in other settings is uncertain. Our impression is that TFCC repair is highly variable from surgeon-to-surgeon. Purpose  The purpose of this study is to determine the rate of TFCC repair in patients who had a magnetic resonance imaging (MRI) scan of the wrist obtained for ulnar-sided wrist pain, and that showed signal changes in the TFCC. We tested the primary null hypothesis that there are no demographic or surgeon factors associated with repair of the TFCC. Patients and Methods  Three hundred and ninety-four patients with ulnar-sided wrist pain and an MRI scan showing changes in the TFCC were included in this retrospective study. No patients had instability of the distal radioulnar joint (DRUJ) recorded in the medical record. Surgical repair of TFCC tears was used as the primary outcome during statistical analysis to identify factors associated with repair. Results  Out of 394 (6%), 25 patients underwent TFCC repair. We found that 10% of the treating surgeons (4 out of 41) performed 80% of the procedures (20 out of 25). Patients who discerned a trauma prior to their symptoms and patients whose MRI showed signal changes primarily in the ulnar portion of the TFCC were more likely to have surgical repair. Conclusion We found that the rate of TFCC repair varies substantially from surgeon-to-surgeon. The observation that repair is more likely to happen when patients perceive themselves as injured suggests that perception of injury affects how patients and surgeons consider treatment options. To help avoid surgeries based on surgeon bias or patient misperception, we suggest studying the effect of tools that provide simple, balanced, dispassionate, and empowering information (e.g., decision aids) that can limit surgeon-to-surgeon variation. Level of Evidence  Level IV.

Risk Factors of Lunate Collapse in Kienböck Disease

PURPOSE

Not all patients with Kienböck disease progress to collapse of the lunate and carpal malalignment, but it is difficult to determine which patients are at risk. We aimed to identify demographic or anatomical factors associated with more advanced stages of Kienböck disease.

METHODS

We included all 195 eligible patients with Kienböck disease and available preoperative posteroanterior and lateral radiographs. We compared the mean age, sex distribution, mean ulnar variance, radial height, radial (ulnarward) inclination, palmar tilt, anteroposterior distance, and lunate type among the different Lichtman stages of Kienböck disease and performed ordinal logistic regression analysis.

RESULTS

We found that patients with more negative ulnar variance had more advanced stages of Kienböck disease (adjusted odds ratio, 1.4). An increase in age was also independently associated with a higher Lichtman stage of Kienböck disease (adjusted odds ratio, 1.02).

CONCLUSIONS

Our findings suggest that more negative ulnar variance may be related to a greater magnitude of lunate collapse in Kienböck disease. Additional long-term study is needed to confirm the longitudinal relationship of negative ulnar variance with progressive Kienböck disease.

TYPE OF STUDY/LEVEL OF EVIDENCE

Prognostic II.

Interobserver Agreement in Diagnosing Early-Stage Kienböck Disease on Radiographs and Magnetic Resonance Imaging

BACKGROUND

The appearance of early Kienböck disease on radiographs and magnetic resonance imaging (MRI) may be difficult to distinguish from other conditions that affect the lunate. We aimed to assess the interobserver agreement in the diagnosis of early Kienböck disease when evaluated on different imaging modalities.

METHODS

Forty-three hand surgeon members of the Science of Variation Group were randomized to evaluate radiographs and 35 hand surgeons to evaluate radiographs and MRI scans of 26 patients for the presence of Kienböck disease, the lunate type, and the ulnar variance. We used Fleiss' kappa analysis to assess the interobserver agreement for categorical variables and compared the κ values between the 2 groups.

RESULTS

We found that agreement on the diagnosis of early Kienböck disease was fair (κ, 0.36) among observers who evaluated radiographs alone and moderate (κ, 0.58) among observers who evaluated MRI scans in addition to radiographs, and that the difference in κ values was not statistically significant ( P = .057). Agreement did not differ between observers based on imaging modality with regard to the assessment of the lunate type ( P = .75) and ulnar variance ( P = .15).

CONCLUSIONS

We found, with the numbers evaluated, a notable but nonsignificant difference in agreement in favor of observers who evaluated MRI scans in addition to radiographs compared with radiographs alone. Surgeons should be aware that the diagnosis of Kienböck disease in the precollapse stages is not well defined, as evidenced by the substantial interobserver variability.

Risk factors for reoperation after total elbow arthroplasty

BACKGROUND

Total elbow arthroplasty (TEA) is a treatment option for arthritic conditions of the elbow and for complex distal humerus fractures in the elderly. Complications are common, however, and rates of survivorship vary. The goal of this study was to describe the factors associated with reoperation and revision after TEA.

METHODS

We retrospectively reviewed primary TEAs performed at 2 tertiary academic medical centers. We identified 102 primary TEAs in 82 patients by 9 surgeons. The average age of the patients was 61 years. Female patients represented 81% of TEAs performed. The mean follow-up was 6.1 years. The principal diagnosis was inflammatory arthritis in 63 patients (62%), acute trauma or post-trauma in 28 (27%), and primary osteoarthritis in 9 (8.8%).

RESULTS

The rate of reoperation was 41% (42 of 102). The median time to the first reoperation was 1.8 years. The percentage of elbows that had 1 or both components revised was 30% (31 of 102). The most common indication for reoperation was component loosening (17). Six elbows were treated definitively with resection arthroplasty, and 1 was revised to an elbow fusion. The rate of implant revision was 27% for inflammatory arthritis, 11% for osteoarthritis, and 57% after trauma. Trauma-related TEA was more likely to undergo additional reoperation (odds ratio, 4.3; P = .008) and implant revision (odds ratio, 3.4; P = .031).

CONCLUSION

Revision surgery with implant revision after primary TEA is common. Trauma-related TEA often leads to additional procedures.

Carpal Coalitions on Radiographs: Prevalence and Association With Ordering Indication

PURPOSE

Carpal coalitions are common and usually incidental to the indication for wrist radiographs. It is not clear if, or when, carpal coalitions cause pain. The aim of this study was to assess the prevalence of incidental carpal coalitions by evaluating radiographs taken for various indications and to test the association of demographic variables and ordering indications with the finding of a carpal coalition.

METHODS

We reviewed 1,119 posteroanterior wrist radiographs for the presence of carpal coalition. We used bivariate and multivariate analyses to assess demographic factors for their independent associations with the presence of carpal coalitions and to compare the difference in the prevalence of carpal coalitions between radiographs obtained to evaluate traumatic wrist pain (623 wrists), nontraumatic wrist pain (175 wrists), and other reasons (321 wrists).

RESULTS

Radiographs of 98 out of 1,119 patients (8.8%) showed a carpal coalition. Carpal coalitions were equally likely on radiographs obtained for traumatic wrist pain and nontraumatic wrist pain. Patients with no wrist trauma or wrist pain were less likely to have a carpal coalition on their radiograph.

CONCLUSIONS

We consider carpal coalitions an unlikely cause of wrist pain. The lower prevalence in radiographs obtained for causes other than wrist trauma or wrist pain remains unexplained, although it may be spurious. In the evaluation of a patient with nonspecific wrist pain, clinicians should be careful ascribing symptoms to anatomical variations on radiographs. These incidental findings should not usually affect management.

TYPE OF STUDY/LEVEL OF EVIDENCE

Diagnostic III.

The J-Shaped Bone Graft for Anatomic Glenoid Reconstruction: A 10-Year Clinical Follow-up and Computed Tomography-Osteoabsorptiometry Study

BACKGROUND

The J-shaped bone graft procedure is one of the recommended methods to reconstruct significant glenoid rim defects.

PURPOSE

To evaluate long-term (minimum 10-year) clinical outcomes and show further details of the remodeling effects on the articular cavity of the glenoid after J-shaped bone grafting.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

A total of 14 patients treated with a J-shaped bone graft procedure were observed clinically. Additionally, bilateral preoperative and postoperative follow-up computed tomography (CT) scans were used for CT-osteoabsorptiometry (OAM) to evaluate the bony remodeling processes.

RESULTS

The follow-up rate was 93% at a mean follow-up time of 10.7 years (range, 10.08-11.75 years). Patients exhibited a mean Constant score of 92.5 (range, 80-100) on the clinical evaluation. All patients had free range of motion and were pain free without any recurrence of instability. Based on CT-OAM, comparable and almost anatomically reconstructed, bilaterally equal glenoid cavities were found postoperatively. The distribution patterns of glenoid subchondral mineralization were bilaterally equal in 85.7% of the patients.

CONCLUSION

The surgical treatment of recurrent shoulder instability with a significant bony Bankart lesion using the J-shaped bone graft procedure provided excellent long-term results. This study lends evidence to support the capability of the J-shaped bone graft procedure to restore the normal glenoid shape due to physiological remodeling processes.

Incidental magnetic resonance imaging signal changes in the extensor carpi radialis brevis origin are more common with age

BACKGROUND

Patients with enthesopathy of the extensor carpi radialis brevis (ECRB) demonstrate signal changes on magnetic resonance imaging (MRI). It is likely that these MRI changes persist for many years or may be permanent, regardless of symptoms, and represent an estimation of disease prevalence. We tested the hypothesis that the prevalence of incidental signal changes in the ECRB origin increases with age.

METHODS

We searched MRI reports of 3374 patients who underwent an MRI scan, including the elbow, for signal changes in the ECRB origin. Medical records were reviewed for symptoms consistent with ECRB enthesopathy. Prevalences of incidental and symptomatic signal changes were calculated and stratified by age. We used multivariate logistic regression analysis to test whether age, sex, and race were independently associated with ECRB enthesopathy and calculated odds ratios.

RESULTS

Signal changes in ECRB origin were identified on MRI scans of 369 of 3374 patients (11%) without a clinical suspicion of tennis elbow. The prevalence increased from 5.7% in patients aged between 18 and 30 years up to 16% in patients aged 71 years and older. Older age (odds ratio, 1.04; P <.001) was independently associated with the incidental finding of ECRB enthesopathy on elbow MRI scans.

CONCLUSIONS

Increased MRI signal in the ECRB origin is common in symptomatic and in asymptomatic elbows. Our findings support the concept that ECRB enthesopathy is a highly prevalent, self-limited process that seems to affect a minimum of 1 in approximately every 7 people.

Does perceived injustice correlate with pain intensity and disability in orthopaedic trauma patients?

INTRODUCTION

Individuals who experience musculoskeletal trauma may construe the experience as unjust and themselves as victims. Perceived injustice is a cognitive construct comprised by negative appraisals of the severity of loss as a consequence of injury, blame, injury-related loss, and unfairness. It has been associated with worse physical and psychological outcomes in the context of chronic health conditions. The purpose of this study is to explore the association of perceived injustice to pain intensity and physical function in patients with orthopaedic trauma.

METHODS

A total of 124 orthopaedic trauma patients completed the Injustice Experience Questionnaire (IEQ), the PROMIS Physical Function Computer Adaptive Testing (CAT), the PROMIS Pain Intensity instruments, the short form Patient Health Questionnaire for depression (PHQ-2), the short form Pain Self-Efficacy Questionnaire (PSEQ-2), and the short form Pain Catastrophizing Scale (PCS-4) on a tablet computer. A stepwise linear regression model was used to identify the best combination of predictors explaining variance in PROMIS Physical Function and PROMIS Pain Intensity.

RESULTS

The IEQ was associated with PROMIS Physical Function (r=-0.36; P<0.001) and PROMIS Pain Intensity (r=0.43; P<0.001). In multivariable analysis, however, Caucasian race (β=5.1, SE: 2.0, P=0.013, 95% CI: 1.1-9.2), employed work status (β=5.1, SE: 1.5, P=0.001, 95% CI: 2.1-8.2), any cause of injury other than sports, mvc, or fall (β=7.7, SE: 2.1, P<0.001, 95% CI: 3.5-12), and higher self-efficacy (PSEQ-2; β=0.93, SE: 0.23, P<0.001, 95% CI: 0.48-1.4) were selected as part of the best model predicting variance in PROMIS Physical Function. Only a higher degree of catastrophic thinking (PCS-4; β=1.2, SE: 0.12, P<0.001, 95% CI: 0.99 to 1.5) was selected as important in predicting higher PROMIS Pain Intensity.

CONCLUSION

Perceived injustice was associated with both physical function and pain intensity in bivariate correlations, but was not deemed as an important predictor when assessed along with other demographic and psychosocial variables in multivariable analysis. This study confirms prior research on the pivotal role of catastrophic thinking and self-efficacy in reports of pain intensity and physical function in patients with acute traumatic musculoskeletal pain.

Radiographic Progression of Kienböck Disease: Radial Shortening Versus No Surgery

PURPOSE

The natural course of the pathophysiology of Kienböck disease is uncertain. Shortening of the radius is believed to modify the pathophysiology by addressing mechanical influences on the lunate. The aim of this study was to compare the radiographic progression of Kienböck disease among patients who had radial shortening osteotomy and patients who had no surgical treatment, with a minimum 1-year interval between radiographs.

METHODS

Among 207 patients with Kienböck disease, we included all 48 eligible patients who had either radial shortening osteotomy or nonsurgical treatment and 2 sets of wrist radiographs available a minimum of 1 year apart. We compared changes in carpal height ratio, Stahl index, and carpal angles between the 2 sets of radiographs and between radial shortening osteotomy and nonsurgical treatment.

RESULTS

We found, on average, a small decrease in the carpal height ratio and the Stahl index in patients who did and did not have surgery, with no differences between the 2 groups. Nearly half of the patients had no decrease in the carpal height ratio and/or the Stahl index.

CONCLUSIONS

Radiographic progression of Kienböck over 1 year or more seems slight on average regardless of treatment. Future research might address the probability of and factors associated with radiographic progression of Kienböck disease.

TYPE OF STUDY/LEVEL OF EVIDENCE

Prognostic IV.

What Is the Radiographic Prevalence of Incidental Kienböck Disease?

BACKGROUND

Kienböck disease is characterized by osteonecrosis of the lunate. Not all patients with radiographic evidence of the disease experience symptoms bothersome enough to consult a doctor. Little research has been performed on the prevalence of Kienböck disease, and the prevalence in the asymptomatic population is unclear. Knowledge of the natural course of the disease and how often patients are not bothered by the symptoms is important, because it might influence the decision as to whether disease-modifying treatment would be beneficial.

QUESTIONS/PURPOSES

(1) What is the prevalence of incidental and symptomatic Kienböck disease? (2) What are the factors associated with incidental and symptomatic Kienböck disease? (3) Are there differences in Lichtman stage distribution between incidentally discovered and symptomatic Kienböck disease?

METHODS

We retrospectively searched radiology reports of all MRI scans, CT scans, and radiographs that included the wrists of 51,071 patients obtained over an 11-year period at one institution to screen for Kienböck disease and avascular necrosis of the lunate. Corresponding MR images, CT scans, or radiographs were reviewed by an orthopaedic hand surgeon to confirm the presence of Kienböck disease when the report was inconclusive. The medical record was reviewed to determine whether the radiographic Kienböck disease was incidental. Prevalences were calculated for both symptomatic and incidental Kienböck disease. Additionally, we assessed the association of age, sex, and race with incidental and symptomatic Kienböck disease as well as the radiographic severity according to the Lichtman classification and calculated odds ratios.

RESULTS

We identified 51 cases (0.10%) of incidental Kienböck disease and 87 cases (0.17%) of symptomatic Kienböck disease out of 51,071 patients. Patients with incidental Kienböck were older (mean, 54 years; SD, 17; mean difference, -6.1; 95% confidence interval [CI], -11 to -0.96; p = 0.020) and patients with symptomatic Kienböck disease were younger (mean, 43 years; SD, 14; mean difference, 5.1; 95% CI, 1.2-9.0; p = 0.010) compared with the group of patients without Kienböck disease (mean, 48 years; SD, 19). Lunate collapse (Lichtman Stages III and IV) was seen in nine of 51 patients (18%) with incidental Kienböck disease and in 44 of 87 patients (51%) with symptomatic Kienböck disease (odds ratio, 0.21; 95% CI, 0.086-0.51; p < 0.001). Our study did not identify any other factors associated with Kienböck disease.

CONCLUSIONS

We found that Kienböck disease is diagnosed on radiographs in a notable number of asymptomatic patients and that asymptomatic patients are more likely to have precollapse stages of the disease. This suggests that symptoms and disability do not correlate with pathophysiology, progression, or activity. Patients and surgeons benefit from awareness that symptoms are not a good indicator of the severity or prognosis of pathophysiology and that lunate osteonecrosis can exist with no or insufficient symptoms. This is important when considering treatment, because we cannot distinguish active disease at risk of collapse that could merit disease-modifying treatment from disease that will not progress.

LEVEL OF EVIDENCE

Level III, prognostic study.

Negative Ulnar Variance and Kienböck Disease

PURPOSE

To test the primary null hypothesis that there is no difference in mean ulnar variance (UV) scaled to the length of the capitates between 166 wrists with Kienböck disease and an equal number of matched controls and to test the secondary null hypothesis that mean scaled UV does not vary based on age, sex, or race in both Kienböck and control wrists.

METHODS

Ulnar variance was measured on posteroanterior radiographs of the wrist as the distance between a line through the midpoint between the volar and the dorsal edges of the ulnar margin of the radius and a line tangential to the most distal aspect of the carpal surface of the head of the ulna, both perpendicular to the longitudinal axis of the radius. Measurement of UV was scaled to the length of the capitate, resulting in a UV to capitate height (UV:CH) ratio.

RESULTS

We found a significant difference in mean UV:CH ratio between patients with Kienböck disease and a control group matched by age, sex, race, and limb. The prevalence of negative UV was high in both patients with Kienböck disease and matched controls. There were no differences in mean UV:CH ratio with respect to age, sex, or race among patients with Kienböck disease or matched controls.

CONCLUSIONS

The precise role of ulna minus in the development of Kienböck disease remains uncertain and unanswered, given that many patients with Kienböck disease have neutral or positive UV. In addition, a large proportion of the normal population has negative UV, whereas Kienböck disease is rare.

What Factors are Associated With a Surgical Site Infection After Operative Treatment of an Elbow Fracture?

BACKGROUND

Surgical site infections are one of the more common major complications of elbow fracture surgery and can contribute to other adverse outcomes, prolonged hospital stays, and increased healthcare costs.

QUESTIONS/PURPOSES

We asked: (1) What are the factors associated with a surgical site infection after elbow fracture surgery? (2) When taking the subset of closed elbow fractures only, what are the factors associated with a surgical site infection? (3) What are the common organisms isolated from an elbow infection after open treatment?

METHODS

One thousand three hundred twenty adult patients underwent surgery for an elbow fracture between January 2002 and July 2014 and were included in our study. Forty-eight of 1320 patients (4%) had a surgical site infection develop. Thirty-four of 1113 patients with a closed fracture (3%) had a surgical site infection develop.

RESULTS

For all elbow fractures, use of plate and screw fixation (adjusted odds ratio [OR]= 2.2; 95% CI, 1.0-4.5; p = 0.041) and use of external fixation before surgery (adjusted OR = 4.7; 95% CI, 1.1-21; p = 0.035) were associated with higher infection rates. When subset analysis was performed for closed fractures, only smoking (adjusted OR = 2.2; 95% CI, 1.1-4.5; p = 0.023) was associated with higher infection rates. Staphylococcus aureus was the most common bacteria cultured (59%).

CONCLUSIONS

The only modifiable risk factor for a surgical site infection after open reduction and internal fixation was cigarette smoking. Plate fixation and temporary external fixation are likely surrogates for more complex injuries, therefore no recommendations should be inferred from this association. Surgeons should counsel patients who smoke.

LEVEL OF EVIDENCE

Level IV, prognostic study.

Proteasomal Degradation of Proinsulin Requires Derlin-2, HRD1 and p97

Patients with type 1 diabetes (T1D) suffer from beta-cell destruction by CD8⁺ T-cells that have preproinsulin as an important target autoantigen. It is of great importance to understand the molecular mechanism underlying the processing of preproinsulin into these CD8⁺ T-cell epitopes. We therefore studied a pathway that may contribute to the production of these antigenic peptides: degradation of proinsulin via ER associated protein degradation (ERAD). Analysis of the MHC class I peptide ligandome confirmed the presentation of the most relevant MHC class I-restricted diabetogenic epitopes in our cells: the signal peptide-derived sequence A15-A25 and the insulin B-chain epitopes H29-A38 and H34-V42. We demonstrate that specific silencing of Derlin-2, p97 and HRD1 by shRNAs increases steady state levels of proinsulin. This indicates that these ERAD constituents are critically involved in proinsulin degradation and may therefore also play a role in subsequent antigen generation. These ERAD proteins therefore represent interesting targets for novel therapies aiming at the reduction and possibly also prevention of beta-cell directed auto-immune reactions in T1D.

Cowpox virus protein CPXV012 eludes CTLs by blocking ATP binding to TAP

CD8(+) CTLs detect virus-infected cells through recognition of virus-derived peptides presented at the cell surface by MHC class I molecules. The cowpox virus protein CPXV012 deprives the endoplasmic reticulum (ER) lumen of peptides for loading onto newly synthesized MHC class I molecules by inhibiting the transporter associated with Ag processing (TAP). This evasion strategy allows the virus to avoid detection by the immune system. In this article, we show that CPXV012, a 9-kDa type II transmembrane protein, prevents peptide transport by inhibiting ATP binding to TAP. We identified a segment within the ER-luminal domain of CPXV012 that imposes the block in peptide transport by TAP. Biophysical studies show that this domain has a strong affinity for phospholipids that are also abundant in the ER membrane. We discuss these findings in an evolutionary context and show that a frameshift deletion in the CPXV012 gene in an ancestral cowpox virus created the current form of CPXV012 that is capable of inhibiting TAP. In conclusion, our findings indicate that the ER-luminal domain of CPXV012 inserts into the ER membrane, where it interacts with TAP. CPXV012 presumably induces a conformational arrest that precludes ATP binding to TAP and, thus, activity of TAP, thereby preventing the presentation of viral peptides to CTLs.