High failure rate of 2-stage revision for the infected total elbow arthroplasty: a single institution's experience

BACKGROUND

Despite 2-stage revision being a common treatment for elbow prosthetic joint infection (PJI), failure rates are high. The purpose of this study was to report on a single institution's experience with 2-stage revisions for elbow PJI and determine risk factors for failed eradication of infection. The secondary purpose was to determine risk factors for needing allograft bone at the second stage of revision in the setting of compromised bone stock.

METHODS

We retrospectively analyzed all 2-stage revision total elbow arthroplasties (TEAs) performed for infection at a single institution between 2006 and 2020. Data collected included demographics and treatment course prior to, during, and after 2-stage revision. Radiographs obtained after explantation and operative reports were reviewed to evaluate for partial component retention and incomplete cement removal. The primary outcome was failed eradication of infection, defined as the need for repeat surgery to treat infection after the second-stage revision. The secondary outcome was the use of allograft for compromised bone stock during the second-stage revision. Risk factors for both outcomes were determined.

RESULTS

Nineteen patients were included. Seven patients (37%) had either the humeral or ulnar component retained during the first stage, and 10 (53%) had incomplete removal of cement in either the humerus or ulna. Nine patients (47%) had allograft strut used during reimplantation and reconstruction. Nine patients (47%) failed to eradicate the infection after 2-stage revision. Demographic data were similar between the repeat-infection and nonrepeat-infection groups. Six patients (60%) with retained cement failed compared with 3 patients (33%) with full cement removal (P = .370). Two patients (29%) with a retained component failed compared to 7 patients (58%) with full component removal (P = .350). Allograft was used less frequently when a well-fixed component or cement was retained, with no patients with a retained component needing allograft compared to 9 with complete component removal (P = .003). Three patients (30%) with retained cement needed allograft, compared with 6 patients (67%) who had complete cement removal (P = .179).

CONCLUSION

Nearly half of the patients failed to eradicate infection after 2-stage revision. The data did not demonstrate a clear association between retained cement or implants and risk of recurrent infection. Allograft was used less frequently when a component and cement were retained, possibly serving as a proxy for decreased bone loss during the first stage of revision. Therefore, the unclear benefit of removing well-fixed components and cement need to be carefully considered as it likely leads to compromised bone stock that complicates the second stage of revision.

Reverse Shoulder Arthroplasty to Treat Proximal Humerus Fracture Sequelae: A Review

While several proximal humerus fractures treated nonsurgically reach satisfactory outcomes, some become symptomatic malunions or nonunions with pain and dysfunction. When joint-preserving options such as malunion or nonunion repair are not optimal because of poor remaining bone stock or glenohumeral arthritis, shoulder arthroplasty is a good option. Because of the semiconstrained design of reverse shoulder arthroplasty, it is effective at improving function when there is notable bony deformity or a torn rotator cuff. Clinical studies have demonstrated reliable outcomes, and a classification system exists that is helpful for predicting prognosis and complications. By understanding the associated pearls and pitfalls and with careful management of the tuberosities, reverse shoulder arthroplasty is a powerful tool for managing proximal humerus fracture sequelae.

Anatomic Total Shoulder: Predictors of Excellent Outcomes at Five Years after Arthroplasty

PURPOSE

The objectives of this study were to: report minimum 5-year outcomes in patients undergoing TSA and determine characteristics predictive of patients achieving an excellent functional outcome.

METHODS

Pre-operative demographic variables and Simple Shoulder Test (SST) scores were obtained pre-operatively and at a minimum of five years after surgery. A final SST ≥ 10 and percentage of maximal possible improvement (% MPI) of ≥ 66.7% were determined to be the thresholds for excellent outcomes. Univariate and multivariate analysis were performed to identify factors associated with excellent five year clinical outcomes.

RESULTS

Of 233 eligible patients, 188 (81%) had adequate follow-up for inclusion in this study. Mean SST scores improved from 3.4 ± 2.4 to 9.7 ± 2.2 (p < 0.001). Male sex was an independent predictor of both SST ≥ 10 (OR 3.46, 95% CI 1.70-7.31; p < 0.001) and %MPI ≥ 66.7 (OR 2.27, 95% CI 1.11-4.81, p = 0.027). Workers' Compensation insurance was predictive of not obtaining SST ≥ 10 (OR 0.12, 95% 0.02-0.60; p = 0.016) or %MPI ≥ 66.7 (OR 0.16, 95% CI 0.03-0.77, p = 0.025). MCID was passed by the vast majority (95%) of patients undergoing TSA and did not necessarily indicate an excellent, satisfactory outcome.

CONCLUSION

Male sex and commercial insurance coverage were significantly associated with these excellent outcomes, while Workers' Compensation insurance was associated with failure to achieve this result. Thresholds for excellent outcomes, such as final SST ≥ 10 and %MPI ≥ 66.7, may be useful in identifying the characteristics of patients who benefit most from TSA.

Does retained cement or hardware during 2-stage revision shoulder arthroplasty for infection increase the risk of recurrent infection?

INTRODUCTION

When treating chronic prosthetic joint infection (PJI) after shoulder arthroplasty, removal of the implants and cement is typically pursued because they represent a potential nidus for infection. However, complete removal can increase morbidity and compromise bone stock that is important for achieving stable revision implants. The purpose of this study is to compare the rates of repeat infection after 2-stage revision for PJI in patients who have retained cement or hardware compared to those who had complete removal.

MATERIAL AND METHODS

We retrospectively analyzed all two-stage revision total shoulder arthroplasties (TSAs) performed for infection at two institutions between 2011 and 2020 with minimum two-year follow-up from completion of the two-stage revision. Patients were included if they met the International Consensus Meeting (ICM) criteria for probable or definite infection2. Postoperative radiographs after the first-stage of the revision consisting of prosthesis and cement removal and placement of an antibiotic spacer were reviewed to evaluate for retained cement or hardware. Repeat infection was defined as either ≥2 positive cultures at the time of second-stage revision with the same organism cultured during the first-stage revision or repeat surgery for infection after the two-stage revision in patients that again met the ICM criteria for probable or definite infection. The rate of repeat infection among patients with retained cement or hardware was compared to the rate of infection among patients without retained cement or hardware.

RESULTS

Thirty-seven patients met inclusion criteria and were included in the analysis. Six (16%) patients had retained cement and one patient (3%) had two retained broken glenoid baseplate screws after first-stage revision. Of the ten cases of recurrent infection, one case (10%) involved retained cement/hardware. Age at revision (60.9±10.6 vs. 65.0±9.6, p=0.264), BMI (33.4±7.2 vs. 29.7±7.3, p=0.184), Charlson Comorbidity Index (2 (0-8) vs. 3 (0-6), p=0.289), male sex (7 vs. 16, p=0.420) and presence of diabetes (1 vs. 3, p=0.709) were not associated with repeat infection. Retained cement or hardware was also not associated with a repeat risk of infection (1 vs. 6, OR=0.389, p=0.374).

DISCUSSION

We did not find an increased risk of repeat infection in patients with retained cement or hardware compared to those without. Therefore, we believe that surgeons should consider leaving cement or hardware that is difficult to remove and may lead to increased morbidity and future complications.

Risk Factors for Stiffness Requiring Intervention After Ream-and-Run Arthroplasty

Ream-and-run arthroplasty can improve pain and function in patients with glenohumeral arthritis while avoiding the complications and activity restrictions associated with a prosthetic glenoid component. However, stiffness is a known complication after ream-and-run arthroplasty and can lead to repeat procedures such as a manipulation under anesthesia (MUA) or open surgical revision. The objective of this study was to determine risk factors associated with repeat procedures indicated for postoperative stiffness after ream-and-run arthroplasty.

Methods

We conducted a retrospective review of our shoulder arthroplasty database to identify patients who underwent ream-and-run arthroplasty and determined which patients underwent subsequent repeat procedures (MUA and/or open revision) indicated for postoperative stiffness. The minimum follow-up was 2 years. We collected baseline demographic information and preoperative and 2-year patient-reported outcome scores and analyzed preoperative radiographs. Univariate and multivariate analyses determined the factors significantly associated with repeat procedures to treat postoperative stiffness.

Results

There were 340 patients who underwent ream-and-run arthroplasty. The mean Simple Shoulder Test (SST) scores for all patients improved from 5.0 ± 2.4 preoperatively to 10.2 ± 2.6 postoperatively (p < 0.001). Twenty-six patients (7.6%) underwent open revision for stiffness. An additional 35 patients (10.3%) underwent MUA. Univariate analysis found younger age (p = 0.001), female sex (p = 0.034), lower American Society of Anesthesiologists (ASA) class (p = 0.045), posterior decentering on preoperative radiographs (p = 0.010), and less passive forward elevation at the time of discharge after ream-and-run arthroplasty (p < 0.001) to be significant risk factors for repeat procedures. Multivariate analysis found younger age (p = 0.040), ASA class 1 compared with class 3 (p = 0.020), and less passive forward elevation at discharge (p < 0.001) to be independent risk factors for repeat procedures. Of the patients who underwent open revision for stiffness, 69.2% had multiple positive cultures for Cutibacterium.

Conclusions

Younger age, ASA class 1 compared with class 3, and less passive forward elevation in the immediate postoperative period were independent risk factors for repeat procedures to treat postoperative stiffness after ream-and-run arthroplasty.

Level of Evidence

Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Drivers of inpatient hospitalization costs, joint-specific patient-reported outcomes, and health-related quality of life in shoulder arthroplasty for cuff tear arthropathy

BACKGROUND

Cuff tear arthropathy (CTA) can be successfully treated with various types of shoulder arthroplasty. While reverse total shoulder arthroplasty (RSA) is commonly used to treat CTA, CTA hemiarthroplasty (CTA-H, hemiarthroplasty with an extended humeral articular surface) can also be effective in patients with preserved glenohumeral elevation and an intact coracoacromial (CA) arch. As the value of arthroplasty is being increasingly scrutinized, cost containment has become a priority. The objective of this study was to assess hospitalization costs and improvements in joint-specific measures and health-related quality of life for these two types of shoulder arthroplasty in the management of CTA.

METHODS

Seventy-two patients (39 CTA-H and 33 RSA) were treated during the study time period using different selection criteria for each of the two procedures: CTA-H was selected in patients with retained active elevation, an intact CA arch, and an intact subscapularis, while RSA was selected in patients with pseudoparalysis or glenohumeral instability. The Simple Shoulder Test (SST) was used as a joint-specific patient-reported outcome measure. Improvement in quality-adjusted life years was measured using the Short Form 36. Costs associated with inpatient care were collected from hospital financial records. Univariate and multivariate analyses focused on determining predictors of hospitalization costs and improvements in patient-reported outcomes.

RESULTS

Significant improvements in SST and Short Form 36 physical component scores were seen in both groups. Inpatient hospitalization costs were significantly higher in the RSA group than that in the CTA-H group ($15,074 ± $1614 vs. $10,389 ± $1948, P < .001), driven primarily by supplies including the cost of the prosthesis ($9005 ± $2521 vs. $4715 ± $2091, P < .001). The diagnosis of diabetes was an independent predictor of higher inpatient hospitalization costs for both groups. There were no independent predictors for quality-adjusted life year improvements. SST improvement in the CTA-H group was significantly higher in patients with lower preoperative SST scores.

CONCLUSION

Using a standard algorithm of CTA-H for shoulders with retained active elevation and an intact CA arch and RSA for poor active elevation or glenohumeral instability, both procedures led to significant improvements in health-related quality of life and joint-specific measures. Costs were significantly lower for patients meeting the selection criteria for CTA-H. Further value analytics are needed to compare the relative cost effectiveness of RSA and CTA-H for patients with CTA having retained active elevation, intact CA arch, and intact subscapularis.

What happens at the L5/S1 facet joint when implants are placed across the sacroiliac joint?

BACKGROUND

Injuries to the posterior pelvic ring are often stabilized with fixation across the sacroiliac joint (SIJ). However, the compensatory changes at the neighboring L5/S1 facet joint are unknown. The objective of this study was to determine the compensatory change in pelvic kinematics and contact forces at the L5/S1 facet joint after fixation across the sacroiliac joint (SIJ) using a cadaveric model.

METHODS

Five fresh-frozen cadaveric pelvis specimens were dissected to remove non-structural soft tissue. Retroreflective markers were fixed to the L5 body, S1 body and bilateral anterior superior iliac spines to represent the motion of L5, S1 and the ileum, respectively. Pressure sensors were inserted in both L5/S1 facet joints. Testing was performed using a robotic system that applied load to mimic ambulation. Testing was performed prior to SIJ fixation, after unilateral SIJ fixation and bilateral fixation.

RESULTS

Contact force at the L5/S1 facet joint significantly increased by 55% from 48.4 N to 75.2 N following unilateral fixation (p = 0.0161) and increased by 100% to 96.9 N after bilateral fixation (p = 0.0038). Unilateral SIJ fixation increased flexion of the ilium relative to L5 from 1.2° to 2.0° (p = 0.01) and increased axial rotation of L5 relative to S1 from 0.7° to 1.6° (p = 0.001). Bilateral fixation increased flexion of the ilium relative to L5 to 2.0° from 1.2° prior to fixation (p = 0.001), increased axial rotation of L5 relative to S1 to 1.2° from 0.7° prior to fixation (p = 0.002) and increased flexion of L5 relative to S1 to 2.4° from 1.5° prior to fixation (p = 0.04).

CONCLUSION

The L5/S1 facet joint experiences compensatory increased motion under increased contact force after unilateral and bilateral SIJ fixation, possibly predisposing it to adjacent segment arthritis.

LEVEL OF EVIDENCE

V, cadaveric study.

New Approaches to the Diagnosis and Management of Periprosthetic Joint Infection of the Shoulder

Periprosthetic joint infection (PJI) of the shoulder is a potentially devastating complication following shoulder arthroplasty. It is important to review the workup of PJI in the shoulder, including recently developed diagnostic criteria for shoulder PJI, along with detailed examination of the most common causative organism, Cutibacterium acnes. Treatment strategies for PJI of the shoulder include antibiotic therapy, surgical options, and what to do with unexpected positive cultures in revision arthroplasty. Surgeons should be familiar with bony and soft-tissue reconstructive options following explantation of an infected shoulder prosthesis.

Association Between Serum Testosterone Levels and Cutibacterium Skin Load in Patients Undergoing Elective Shoulder Arthroplasty: A Cohort Study

Cutibacterium periprosthetic joint infections are important complications of shoulder arthroplasty. Although it is known that these infections are more common among men and that they are more common in patients with high levels of Cutibacterium on the skin, the possible relationship between serum testosterone levels and skin Cutibacterium levels has not been investigated.

Diagnostic Criteria for the Painful Swollen Pediatric Knee: Distinguishing Septic Arthritis From Aseptic Effusion in a Non-Lyme Endemic Area

Purpose: The child with a painful swollen knee must be worked-up for possible septic arthritis; the classic clinical prediction algorithms for septic arthritis of the hip may not be the best models to apply to the knee. Materials and methods: This was a retrospective case-control study of 17 years of children presenting to one hospital with a chief complaint of a painful swollen knee, to evaluate the appropriateness of applying a previously described clinical practice algorithm for the hip in differentiating between the septic and aseptic causes of the painful knee effusions. The diagnoses of true septic arthritis, presumed septic arthritis, and aseptic effusion were established, based upon the cultures of synovial fluid, blood cultures, synovial cell counts, and clinical course. Using a logistic regression model, the disease status was regressed on both the demographic and clinical variables. Results: In the study, 122 patients were included: 51 with true septic arthritis, 37 with presumed septic arthritis, and 34 with aseptic knee effusion. After applying a backward elimination, age <5 years and C-reactive protein (CRP) >2.0 mg/dl remained in the model, and predicted probabilities of having septic knee arthritis ranged from 15% for the lowest risk to 95% for the highest risk. Adding a knee aspiration including percent polymorphonucleocytes (%PMN) substantially improved the overall model performance, lowering the lowest risk to 11% while raising the highest risk to 96%. Conclusions: This predictive model suggests that the likelihood of pediatric septic arthritis of the knee is >90% when both "age <5 years" and "CRP > 2.0 mg/dl" are present in a child with a painful swollen knee, though, in the absence of these factors, the risk of septic arthritis remains over 15%. Aspiration of the knee for those patients would be the best next step.

Drivers of lower inpatient hospital costs and greater improvements in health-related quality of life for patients undergoing total shoulder and ream-and-run arthroplasty

BACKGROUND

With increasing emphasis on value-based care and the heavy demands on the US health care budget, surgeons must be cognizant of factors that drive cost and quality of patient care. Our objective was to determine patient-level drivers of lower costs and improved health-related quality of life (HRQoL) in 2 anatomic shoulder arthroplasty procedures: total shoulder arthroplasty (TSA) and ream-and-run arthroplasty.

METHODS

This study included 222 TSAs and 211 ream-and-run arthroplasties. Simple Shoulder Test, Single Assessment Numeric Evaluation, and Short Form 36 scores were collected preoperatively and 2 years postoperatively. Quality-adjusted life-years (QALYs) were calculated as a measure of HRQoL. Univariate and multivariate analyses determined factors significantly associated with decreased hospitalization costs and improved HRQoL.

RESULTS

In the TSA group, female sex, lower American Society of Anesthesiologists class, diagnosis other than capsulorrhaphy arthropathy, lower pain score, and higher Single Assessment Numeric Evaluation score were associated with decreased total hospitalization costs; in addition, female sex was an independent predictor of lower total costs. Insurance other than workers' compensation, a diagnosis of chondrolysis, and higher optimism led to greater QALY gains, but a diagnosis of capsulorrhaphy arthropathy was the only independent predictor of greater QALY gains. In the ream-and-run arthroplasty group, older age, lower body mass index (BMI), lower American Society of Anesthesiologists class, insurance other than Medicaid, diagnosis other than capsulorrhaphy arthropathy, no history of surgery, higher preoperative Simple Shoulder Test score, and higher preoperative Short Form 36 Physical Component Summary score were associated with lower total costs; moreover, lower BMI was an independent predictor of lower costs. Higher preoperative optimism was an independent predictor of greater QALY gains.

CONCLUSIONS

Identifying factors associated with decreased costs and increased quality is becoming increasingly important in value-based care. This study identified fixed (sex and diagnosis) and modifiable (BMI) factors that drive decreased hospitalization costs and increased HRQoL improvements in shoulder arthroplasty patients. Higher preoperative patient optimism is a consistent predictor of improved HRQoL for both TSA patients and ream-and-run arthroplasty patients, and further study on optimizing the influence of patient expectations and optimism may be warranted.

Assessing the Value to the Patient of New Technologies in Anatomic Total Shoulder Arthroplasty

BACKGROUND

Publications regarding anatomic total shoulder arthroplasty (TSA) have consistently reported that they provide significant improvement for patients with glenohumeral arthritis. New TSA technologies that have been introduced with the goal of further improving these outcomes include preoperative computed tomography (CT) scans, 3-dimensional preoperative planning, patient-specific instrumentation, stemless and short-stemmed humeral components, as well as metal-backed, hybrid, and augmented glenoid components. The benefit of these new technologies in terms of patient-reported outcomes is unknown.

METHODS

We reviewed 114 articles presenting preoperative and postoperative values for commonly used patient-reported metrics. The results were analyzed to determine whether patient outcomes have improved over the 20 years during which new technologies became available.

RESULTS

The analysis did not identify evidence that the results of TSA were statistically or clinically improved over the 2 decades of study or that any of the individual technologies were associated with significant improvement in patient outcomes.

CONCLUSIONS

Additional research is required to document the clinical value of these new technologies to patients with glenohumeral arthritis.

LEVEL OF EVIDENCE

Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Demographic data is more predictive of component size than digital radiographic templating in total knee arthroplasty

Background

Preoperative radiographic templating for total knee arthroplasty (TKA) has been shown to be inaccurate. Patient demographic data, such as gender, height, weight, age, and race, may be more predictive of implanted component size in TKA.

Materials and methods

A multivariate linear regression model was designed to predict implanted femoral and tibial component size using demographic data along a consecutive series of 201 patients undergoing index TKA. Traditional, two-dimensional, radiographic templating was compared to demographic-based regression predictions on a prospective 181 consecutive patients undergoing index TKA in their ability to accurately predict intraoperative implanted sizes. Surgeons were blinded of any predictions.

Results

Patient gender, height, weight, age, and ethnicity/race were predictive of implanted TKA component size. The regression model more accurately predicted implanted component size compared to radiographically templated sizes for both the femoral (P = 0.04) and tibial (P < 0.01) components. The regression model exactly predicted femoral and tibial component sizes in 43.7 and 43.7% of cases, was within one size 90.1 and 95.6% of the time, and was within two sizes in every case. Radiographic templating exactly predicted 35.4 and 36.5% of cases, was within one size 86.2 and 85.1% of the time, and varied up to four sizes for both the femoral and tibial components. The regression model averaged within 0.66 and 0.61 sizes, versus 0.81 and 0.81 sizes for radiographic templating for femoral and tibial components.

Conclusions

A demographic-based regression model was created based on patient-specific demographic data to predict femoral and tibial TKA component sizes. In a prospective patient series, the regression model more accurately and precisely predicted implanted component sizes compared to radiographic templating.

Level of evidence

Prospective cohort, level II.

Impact of previous non-arthroplasty surgery on clinical outcomes after primary anatomic shoulder arthroplasty

BACKGROUND

The objectives of this study were to address the following questions regarding previous non-arthroplasty surgery prior to primary anatomic shoulder arthroplasty (either total shoulder arthroplasty [TSA] or ream-and-run arthroplasty): (1) To what degree is primary anatomic shoulder arthroplasty after prior non-arthroplasty surgery associated with inferior clinical outcomes and higher revision rates compared with arthroplasty without previous surgery? (2) Does type, approach, or timing of previous surgery affect outcomes after anatomic arthroplasty?

METHODS

A retrospective review of a primary shoulder arthroplasty database was performed and identified 640 patients undergoing anatomic shoulder arthroplasty (345 TSAs and 295 ream-and-run arthroplasties). Of these patients, 183 (29%) underwent previous non-arthroplasty surgery. Baseline and demographic information, 2-year postoperative outcome scores, and revision surgical procedures with associated culture results were collected.

RESULTS

In patients undergoing TSA, previous non-arthroplasty surgery was associated with a significantly lower 2-year Simple Shoulder Test (SST) score (P = .010), percentage maximum possible improvement (MPI) (P = .024), and Single Assessment Numeric Evaluation (SANE) score (P < .001) and a higher rate of reoperation (P < .001). In patients undergoing ream-and-run arthroplasty, previous non-arthroplasty surgery was associated with a nonsignificantly lower 2-year SST score, percentage MPI, and SANE score and higher reoperation rate. Prior fracture surgery carried a higher risk of reoperation than other types of surgery including rotator cuff repair and instability surgery. Among TSA and ream-and-run arthroplasty cases with prior non-arthroplasty surgery, prior open surgery and the time interval from most recent surgery were associated with nonsignificant differences in the 2-year SST score, percentage MPI, SANE score, and revision risk.

CONCLUSION

Previous surgery is associated with inferior clinical outcomes and higher revision rates in patients undergoing index TSA but not in those undergoing the ream-and-run procedure. Patients with previous fracture surgery carry the highest risk of reoperation.

Extra-Articular Hip Resection and Reconstruction with Custom Acetabular Resection Guide and Implants in a Case of High-Grade Spindle Cell Sarcoma of the Proximal Femur: A Case Report

CASE

A 29-year-old man was admitted with acute atraumatic left hip pain and inability to bear weight. Subsequent workup revealed an intracapsular pathologic fracture of the femoral neck secondary to a high-grade spindle cell sarcoma. A unique method of extra-articular resection and reconstruction using a 3-dimensional (3D)-printed custom cutting jig and a custom acetabular component was pursued. Wide margins were achieved without violating the joint capsule but preserving pelvic integrity, allowing a return to an active lifestyle.

CONCLUSION

Three-dimensional-printed custom resection guides and implants can help achieve adequate resection margins while preserving pelvic integrity and function.

Biomechanics of an Articulated Screw in Acute Scapholunate Ligament Disruption

Background  An injury to the scapholunate interosseous ligament (SLIL) leads to instability in the scapholunate joint. Temporary fixation is used to protect the ligament during reconstruction or healing of the repair. Rigid screw fixation-by blocking relative physiological motion between the scaphoid and lunate-can lead to screw loosening, pullout, and fracture. Purpose  This study aims to evaluate changes in scaphoid and lunate kinematics following SLIL injury and the effectiveness of an articulating screw at restoring preinjury motion. Materials and Methods  The kinematics of the scaphoid and lunate were measured in 10 cadaver wrists through three motions driven by a motion simulator. The specimens were tested intact, immediately following SLIL injury, after subsequent cycling, and after fixation with a screw. Results  Significant changes in scaphoid and lunate motion occurred following SLIL injury. Postinjury cycling increased motion changes in flexion-extension and radial-ulnar deviation. The motion was not significantly different from the intact scapholunate joint after placement of the articulating screw. Conclusion  In agreement with other studies, sectioning of the SLIL led to significant kinematic changes of the scaphoid and lunate in all motions tested. Compared with intact scapholunate joint, no significant difference in kinematics was found after placement of the screw indicating a correction of some of the changes produced by SLIL transection. These findings suggest that the articulating screw may be effective for protecting a SLIL repair while allowing the physiological rotation to occur between the scaphoid and lunate. Clinical Relevance  A less rigid construct, such as the articulating screw, may allow earlier wrist rehabilitation with less screw pullout or failure.

Rotator cuff tear reduces muscle fiber specific force production and induces macrophage accumulation and autophagy

Full-thickness tears to the rotator cuff can cause severe pain and disability. Untreated tears progress in size and are associated with muscle atrophy and an infiltration of fat to the area, a condition known as "fatty degeneration." To improve the treatment of rotator cuff tears, a greater understanding of the changes in the contractile properties of muscle fibers and the molecular regulation of fatty degeneration is essential. Using a rat model of rotator cuff injury, we measured the force generating capacity of individual muscle fibers and determined changes in muscle fiber type distribution that develop after a full thickness rotator cuff tear. We also measured the expression of mRNA and miRNA transcripts involved in muscle atrophy, lipid accumulation, and matrix synthesis. We hypothesized that a decrease in specific force of rotator cuff muscle fibers, an accumulation of type IIb fibers, and an upregulation in fibrogenic, adipogenic, and inflammatory gene expression occur in torn rotator cuff muscles. Thirty days following rotator cuff tear, we observed a reduction in muscle fiber force production, an induction of fibrogenic, adipogenic, and autophagocytic mRNA and miRNA molecules, and a dramatic accumulation of macrophages in areas of fat accumulation.