The subacromial bursa modulates tendon healing after rotator cuff injury in rats

Rotator cuff injuries result in more than 500,000 surgeries annually in the United States, many of which fail. These surgeries typically involve repair of the injured tendon and removal of the subacromial bursa, a synovial-like tissue that sits between the rotator cuff and the acromion. The subacromial bursa has been implicated in rotator cuff pathogenesis and healing. Using proteomic profiling of bursa samples from nine patients with rotator cuff injury, we show that the bursa responds to injury in the underlying tendon. In a rat model of supraspinatus tenotomy, we evaluated the bursa's effect on the injured supraspinatus tendon, the uninjured infraspinatus tendon, and the underlying humeral head. The bursa protected the intact infraspinatus tendon adjacent to the injured supraspinatus tendon by maintaining its mechanical properties and protected the underlying humeral head by maintaining bone morphometry. The bursa promoted an inflammatory response in injured rat tendon, initiating expression of genes associated with wound healing, including Cox2 and Il6. These results were confirmed in rat bursa organ cultures. To evaluate the potential of the bursa as a therapeutic target, polymer microspheres loaded with dexamethasone were delivered to the intact bursae of rats after tenotomy. Dexamethasone released from the bursa reduced Il1b expression in injured rat supraspinatus tendon, suggesting that the bursa could be used for drug delivery to reduce inflammation in the healing tendon. Our findings indicate that the subacromial bursa contributes to healing in underlying tissues of the shoulder joint, suggesting that its removal during rotator cuff surgery should be reconsidered.

Tourniquet-free minimally invasive total knee arthroplasty is associated with early aseptic loosening

BACKGROUND

While tourniquet-free (T-) total knee arthroplasty (TKA) has gained popularity, tourniquet-use during minimally-invasive (MIS)-TKA has not been adequately studied. Traditional techniques employ knee hyper-flexion, compressing vasculature and reducing impact of bleeding, while MIS-TKA embraces the semi-extended knee position, which does not restrict the effects of bleeding on cementation and visualization. We compared the risk of aseptic loosening between patients undergoing T- MIS-TKA compared to T + MIS-TKA.

METHODS

This single-surgeon cohort study included 329 consecutive MIS-TKA (226 T+,103 T-) patients with minimum 3-year follow-up. Aseptic loosening, radiolucent lines (RLL), health related quality of life scores, and complications were recorded. T-test and chi-square test were used to compare continuous and categorical variables, and logistic regression included BMI, age, ASA, patellar-resurfacing, and tourniquet-use.

RESULTS

There were no differences in baseline demographics. One (0.4 %) aseptic loosening occurred with T+, versus 7 (6.8 %) with T- (p = 0.002). No T + and 3 T- patients (2.9 %, p = 0.01) had revision for aseptic loosening. The incidence of RLLs was 16.8 % in T + and 30.1 % in T- (p = 0.008). Logistic regression revealed T + was significantly associated with decreased aseptic loosening and risk of RLL (odds ratio = 16.4, odds ratio = 2.8).

CONCLUSION

In this consecutive series, T- MIS-TKA was associated with increased rates of revision for aseptic loosening as compared to the T + MIS-TKA, even controlling for BMI, age, ASA level, and patellar resurfacing. Radiolucent lines were increased with T- MIS-TKA compared to T + MIS-TKA. Complications, all-cause revision, ROM, and HRQoL scores were similar between tourniquet-use and tourniquet-free cohorts.

Anatomic Risks with Overpenetration of the Volar Locking Plates' Proximal Holes

Background  Volar locking plate fixation (VLP) is commonly used to treat distal radius fractures (DRF). Risk of dorsal compartment injury with distal screw hole fixation has been studied; however, the risk with proximal screw hole fixation is not well studied. Purpose  The goal of this study was to investigate the risk of dorsal structure injury from the screw holes proximal to the two distal rows. Methods  Nine cadaveric forearms were used. After volar distal radius exposure, a long VLP was applied. Kirschner wires were placed through the most proximal holes into the dorsal compartments. The extensor structures penetrated were noted and tagged with hemoclips. The distance from the dorsal cortex to the structures was measured. Results  The abductor pollicis longus (APL) and extensor pollicis brevis (EPB) muscle bodies were only penetrated; no tendons were penetrated. Proportion of muscle penetration increased with the more proximal screw holes. EPB was more likely to be penetrated distally and APL proximally; both were injured at holes 2 and 3. The extensors were 2 mm from the dorsal cortex of the radius on average; this did not decrease with compression of the forearm. Conclusions  This is the first study to examine the anatomic risk of extensor structure injury with VLP proximal screw hole penetration. No extensor tendons were penetrated by these proximal screw holes; first dorsal compartment muscle bellies may be irritated with overpenetration. Our findings suggest that proximal VLP screws do not need to be downsized if they are not over 2 mm prominent.

The subacromial bursa is a key regulator of the rotator cuff and a new therapeutic target for improving repair

Rotator cuff injuries result in over 500,000 surgeries performed annually, an alarmingly high number of which fail. These procedures typically involve repair of the injured tendon and removal of the subacromial bursa. However, recent identification of a resident population of mesenchymal stem cells and inflammatory responsiveness of the bursa to tendinopathy indicate an unexplored biological role of the bursa in the context of rotator cuff disease. Therefore, we aimed to understand the clinical relevance of bursa-tendon crosstalk, characterize the biologic role of the bursa within the shoulder, and test the therapeutic potential for targeting the bursa. Proteomic profiling of patient bursa and tendon samples demonstrated that the bursa is activated by tendon injury. Using a rat to model rotator cuff injury and repair, tenotomy-activated bursa protected the intact tendon adjacent to the injured tendon and maintained the morphology of the underlying bone. The bursa also promoted an early inflammatory response in the injured tendon, initiating key players in wound healing. In vivo results were supported by targeted organ culture studies of the bursa. To examine the potential to therapeutically target the bursa, dexamethasone was delivered to the bursa, prompting a shift in cellular signaling towards resolution of inflammation in the healing tendon. In conclusion, contrary to current clinical practice, the bursa should be retained to the greatest extent possible and provides a new therapeutically target for improving tendon healing outcomes.

One Sentence Summary

The subacromial bursa is activated by rotator cuff injury and regulates the paracrine environment of the shoulder to maintain the properties of the underlying tendon and bone.

Intimate Partner Violence in the Orthopaedic Patient Population: What Surgeons Need to Know

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Intimate partner violence (IPV) is under-reported and pervasive in the orthopaedic surgical setting.

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Screening programs that could increase reporting and assist in treatment and prevention are commonly underutilized.

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There is little formalized education during orthopaedic surgery training for IPV.

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The incidence of IPV continues to increase in the setting of recent stressors, such as COVID-19, and the orthopaedic surgeon should play a role in the screening and identification of patients presenting with IPV injuries and provide resources and referral.

A comparison of pin site complications between large and small pin diameters in robotic-assisted total knee arthroplasty

PURPOSE

Robotic-assisted total knee arthroplasty typically necessitates use of tracking pins, which can vary in diameter. Complications such as infections and fractures at the pin-site have been observed, but clarification of the effect of pin diameter on complication is needed. The aim of this study is to compare the pin-related complication rates following robotic-assisted total knee arthroplasty between 4.5 mm and 3.2 mm diameter pins.

METHODS

In this retrospective cohort study, 90-day pin-site complication rates after robotic-assisted total knee arthroplasty were compared between 4.5 mm diameter and 3.2 mm diameter groups. In total, 367 patients were included: 177 with large pin diameter and 190 with small pin diameter. All four pin sites were evaluated using postoperative radiographs. Cases without orthogonal views or visualization of all four pin tracts were noted. Multivariate logistic regression was used to control for age, which differed between the two cohorts.

RESULTS

The rate of pin-site complications was 5.6% in the large pin diameter cohort and 2.6% in the small pin diameter cohort, with no statistically significant difference between the groups. The adjusted odds ratio for complications in small compared to large diameter group was 0.48, with a p-value of 0.18. The most common pin-site complication was infection/persistent drainage, found in 1.9% of patients, followed by intraoperative fracture of the second cortex in 1.4%. Intraoperative fracture could not be ruled out in 96 cases due to inadequate radiographic visualization of all pin sites. There was one postoperative pin-site fracture in the large diameter cohort, which required operative fixation.

CONCLUSION

This study demonstrates no statistically significant difference in pin-site complication rates after robotic-assisted total knee arthroplasty between 4.5 mm and 3.2 mm pin diameter cohorts, although there was a trend towards increased intraoperative and postoperative pin-site fractures in the 4.5 mm group.

Extensor Tendon Injury After Volar Locking Plating for Distal Radius Fractures: A Systematic Review

Distal radius fractures are common orthopedic injuries. Treatment has varied historically, but volar locking plating currently predominates. Although flexor tendon injury is a well-studied complication of this operation, extensor tendon injury is less well studied. The purpose of this review is to search the literature and present the epidemiology, presentation, and treatment of this complication. The Cochrane, EMBASE, PubMed, and SCOPUS databases were searched for the terms "volar" + "radius" + ("plate" OR "plating") + "extensor." Ninety final studies were included for analysis in this review. The incidence of extensor tendon rupture varies from 0% to 12.5%; the extensor pollicis longus is most commonly ruptured. The presentation and management of extensor tendon injury after injury, intraoperatively, and postoperatively are summarized. Radiographic views are described to detect screw prominence and minimize intraoperative risk. Extensor tendon injury after volar locking plate for distal radius fractures is an uncommon injury with several risk factors including dorsal screw prominence and fracture fragments. Removal of hardware and tendon transfers or reconstruction may be necessary to prevent loss of extensor mechanism.