The Effect of Forearm Shortening on Finger Flexion: A Biomechanical Study.

PURPOSE: Surgeons may shorten the forearm for many indications. We quantified the impact of shortening on finger flexion with a cadaver model. METHODS: Ten fresh cadaver proximal forearms were pinned to a static block. We pinned each distal forearm/hand to a block that could unlock, slide, and relock on a mounting track. This block allowed wrist-neutral or 30-degree extension. With the sliding block locked, we removed the central 10 cm of the radius/ulna. We placed sutures in the proximal end of each flexor digitorum profundus (FDP). After pretensioning, we simulated near-maximum baseline FDP muscle-generating force by applying 100 N via a load cell at the proximal sutures. We then anchored the load cell system proximally to set the initial length-tension relationship for simulating near-maximum baseline muscle-generating force. We called subsequent load cell readings the simulated muscle force (SMF) and pressure sensor readings between fingertips and the palm the tip-to-palm force (TPF). We shortened the forearm in 1 cm increments with the distal sliding-locking block. At each increment, we recorded SMF and TPF in the wrist-neutral position. Once a specimen lost measurable TPF, we applied 30 degrees wrist extension until again losing TPF. RESULTS: Incremental forearm shortening was associated with exponential decreases in each FDP's SMF and TPF. In wrist-neutral, 3 cm mean shortening had a loss of 99% and 98% SMF and TPF, respectively. Wrist extension marginally improved SMF and TPF up to 4 cm mean shortening, where both lost 99%. Loss of any fingertip touchdown occurred after a mean shortening of 4.9 cm in wrist-neutral and 5.3 cm in 30 degrees wrist extension. CONCLUSIONS: Mean forearm shortening of 3 or 4 cm had a near-complete loss of FDP SMF and TPF in wrist-neutral/wrist extension, respectively. With ∼5 cm shortening, there was a complete loss of fingertip touchdown. CLINICAL RELEVANCE: Surgeons should consider the influence of forearm shortening on the FDPs and contemplate flexor tendon shortening or alternative reconstructions as indicated.

Feasibility of a Multi-Center Respiratory Therapist Endotracheal Intubation Study.

BACKGROUND: Respiratory therapists (RTs) have historically performed safe and effective intubations, yet there are limited multi-center data assessing their intubation performance. Multi-center data can be used to compare RT intubation performance to that of other professions and identify quality improvement opportunities at hospitals where RTs perform intubation. We aimed to explore the feasibility of a multi-center collaborative to evaluate RT intubation outcomes. METHODS: A data collection tool was developed by the authors and implemented at two institutions. Following institutional review board approval at each center and completion of data-use sharing agreements, data were collected between May 25, 2020-April 30, 2022, and combined for analysis. Descriptive statistics were used to compare overall success rate, first-attempt success rate, adverse events (AEs), and type of laryngoscopy. RESULTS: There were a total of 689 intubation courses where RTs made an attempt, 363 from center A and 326 from center B. Center A captured 85% of all RT intubation courses, and center B captured 63%. Overall, RTs were successful in 98% of attempts. RTs made 86% of initial attempts. The most common indications for intubation were cardiac arrest (42%) and respiratory failure (31%). Videolaryngoscopy was used during 65% of initial attempts and was associated with higher first-attempt success rate, higher overall success rate, and fewer AEs. Airway-related adverse event rate was 8.7%; physiologic AE rate was 16%, and desaturation rate was 11%. CONCLUSIONS: A collaborative examining RTs intubation performance was successfully initiated at 2 separate facilities. Intubations performed by RTs had a high success rate, with AE rates comparable to published results from other types of providers.

Effect of reverse shoulder arthroplasty humeral component retroversion on acromial strain.

INTRODUCTION: Acromion and scapular spine stress fractures can be catastrophic complications following reverse shoulder arthroplasty (RSA). A variety of host, implant, and technical factors have been identified that increase the risk of this complication. The glenoid component in particular has been closely evaluated for its impact on rates of stress fractures following RSA. The goal of this biomechanical study is to evaluate if humeral stem version has an impact on acromion and scapular spine strain after RSA. METHODS: Eight cadaveric specimens were tested on a custom dynamic shoulder frame. Commercially available RSA components were implanted with the humeral component inserted in 0° of retroversion. Acromion and scapular spine strain were measured at 0°, 30°, and 60° of abduction using strain rosettes secured to the acromion and scapular spine in the typical locations for Levy type II and type III stress fractures, respectively. The humeral stem was then removed and reimplanted in 30° of retroversion and the measurements were repeated. Student t test was performed to analyze the relationship between humeral stem version and acromion and scapular spine strain at various abduction angles. RESULTS: Strain at the both the acromion and scapular spine were found to have no significant difference at any abduction angle when comparing 0° and 30° version of the humeral stem. With 0° and 30° versions pooled together, there is significantly lower acromion and scapular spine strain at 60° of abduction when compared to 0° of abduction (strain at 0° abduction - strain at 60° abduction: acromion 313.1 µêœª; P = .0409, Scapular spine 304.9 µêœª; P = .0407). There was no significant difference in strain at either location when comparing 0° of abduction to 30° of abduction and when comparing 30° of abduction to 60° of abduction. CONCLUSIONS: This biomechanical study found no significant difference in scapular spine and acromion strain after RSA when comparing variations in humeral stem version. There does appear to be lower strain at both the acromion and scapular spine at 60° of abduction when compared to 0° of abduction regardless of stem version.

Impact of radiocapitellar interposition arthroplasty on ulnohumeral joint biomechanics.

BACKGROUND: Radial head excision (RHE) has been shown to increase contact pressures within the ulnohumeral joint. Radiocapitellar interposition arthroplasty (RCIA) with the use of a soft tissue graft is an alternative for the treatment of isolated radiocapitellar arthritis or with failure of radial head replacement. We investigated contact pressures and contact area within the ulnohumeral joint after RHE compared to RCIA with dermal autograft. METHODS: Six fresh-frozen cadaver elbows were tested on a custom dynamic elbow frame. A pressure sensor was inserted into the intact elbow joint, and mean contact pressure, peak contact pressure, contact area, and force within the ulnohumeral joint were recorded at 0°, 30°, 60°, 90°, and 120° of flexion as a valgus load was applied to the elbow. The radial head was then excised and specimens were retested. Finally, a dermal graft matched to the size of the resected radial head was inserted in the radiocapitellar space and the specimens were tested a third time. RESULTS: At 90° of flexion, contact pressure within the ulnohumeral joint was significantly lower with RCIA compared with RHE (110.8 kPa vs 216.8 kPa; P = .013). The mean peak contact pressure was also significantly lower with RCIA compared with RHE at 90° (279.4 vs 626.7 kPa; P = .025). No statistically significant differences were seen in mean contact area or force between the 3 testing conditions at any flexion position. CONCLUSION: RCIA with a dermal graft reduced contact pressures within the ulnohumeral joint compared to RHE at 90° of flexion without a significant change in contact area or contact force.

Improving Tracheostomy Decannulation Rate In Trauma Patients.

OBJECTIVE: Identify the effect of a multidisciplinary tracheostomy decannulation protocol (TDP) in the trauma population. DESIGN: Single center retrospective review. SETTING: American College of Surgeons Level 1 Trauma Center; large academic associated community hospital. PATIENTS: Adult trauma patients who required a tracheostomy. INTERVENTIONS: A TDP empowering respiratory therapists to move patients towards tracheostomy decannulation (TD). MEASUREMENTS: TD rate, time to TD, length of stay, reintubation and recannulation rates. MAIN RESULTS: A total of 252 patients met inclusion criteria during the study period with 134 presenting after the TDP was available. Since the TDP was implemented, patients managed by the TDP had a 50% higher chance of TD during the hospital stay (p<0.001). The time to TD was 1 day shorter with the TDP (p=0.54). There was no difference in time to discharge after ventilator liberation (p=0.91) or in discharge disposition (p=0.66). When comparing all patients, the development of a TDP, regardless if a patient was managed by the TDP, resulted in an 18% higher chance of TD (p=0.003). Time to TD was 5 days shorter in the post intervention period (p=0.07). There was no difference in discharge disposition (p=0.88) but the time to discharge after ventilator liberation was shorter post protocol initiation (p=0.04). CONCLUSIONS: In a trauma population, implementation of a TDP significantly improves TD rates during the same hospital stay. A larger population will be required to identify patient predictive factors for earlier successful TD.