Polymethyl Methacrylate for Elbow Arthroplasty: Is There Another Way?

Polymethyl methacrylate remains the only US Food and Drug Administration-approved method of total elbow arthroplasty fixation and exhibits high aseptic loosening rates that result in challenging revision surgeries and potential morbidity secondary to bone-cement implantation syndrome. In this policy paper, the authors aim to explore the historical background of polymethyl methacrylate and the complications that arise in association with its use. We will review arthroplasty trends in the elbow and lower extremities and the challenges with the US Food and Drug Administration-approval process.

Comparison of Fusion Rates/Complications Between Different Types of Thumb Metacarpophalangeal Fusion Techniques.

BACKGROUND: Thumb metacarpophalangeal (MP) fusion is generally successful; however, complications have been reported to occur in 0% to 30% of cases, whereas nonunion rates vary by method but, overall, are reported to occur in 0% to 15% of cases. Many fixation techniques have been described, but there is no consensus on the optimal fusion technique. Our goal was to compare complication and union rates of different thumb MP arthrodesis techniques. METHODS: We performed a retrospective review of patients who underwent primary thumb MP fusion between 2000 and 2022. Patients who underwent revision fusion, fusion for infection, or amputation were excluded. Fusions of MP joints of other fingers were also excluded. Data collection consisted of demographic data, complications, time to fusion, rate of delayed union and rate of nonunion. Five different fusion constructs were evaluated during our study period: staples, Kirschner wires (K-wires), cerclage, K-wires with cerclage, and intramedullary screw. RESULTS: Forty-seven patients underwent fusion with staples, 16 with K-wires, 14 with cerclage, 9 with K-wires and cerclage, and 6 with an intramedullary screw. The individual complication and nonunion rates differed significantly among the groups with the intramedullary screw group having a statistically higher rate of nonunion (P = .004). Furthermore, smoking, diabetes, and being overweight were associated with nonunions. CONCLUSION: Union rates were significantly lower in patients treated with an intramedullary screw and those who are smokers, diabetics, and/or overweight. Caution should be exercised when using intramedullary screw fixation for MP fusion, especially in patients with these comorbidities.

Active Motion Laboratory Test Apparatus for Evaluation of Total Elbow Prostheses.

Purpose: The goal of this study was to develop a dynamic elbow testing apparatus that reproduces active joint motion at different shoulder positions to quantify the capabilities of total elbow arthroplasty designs. Methods: We designed a testing apparatus to create active cyclic elbow joint motion in human cadaveric and sawbones composite upper extremities. Two pneumatic actuators recreated humerus-originating muscles while rubber bands simulated forearm muscle action. Arthroplasty durability was quantified through laxity assessment at predetermined cyclic loading intervals. Results: Humeral forces were recorded in three specimens to generate active elbow motion at different degrees of shoulder abduction. The laxity in varus and valgus was measured as deflection between two fixed markers. Conclusions: In vitro simulation of elbow biomechanics through active cyclic elbow motion at different degrees of shoulder abduction may characterize in vivo performance of total elbow arthroplasty. Clinical relevance: Quantifying total elbow arthroplasty stability after cyclic loading in different shoulder positions may assist preclinical evaluation of arthroplasty designs.

Elbow Uncemented Hemiarthroplasty: Surgical Technique.

Management of elbow arthritis in younger and higher demand patients is challenging and may benefit from a distal humerus hemiarthroplasty that employs a noncemented method of implant fixation and stabilizes the elbow through ligament reconstruction. By not replacing both articulating surfaces, hardware longevity may be improved. We describe a novel system that may be indicated for the treatment of posttraumatic or primary osteoarthritis of the distal humerus. The step-by-step technique for surgical implantation of this uncemented distal humerus hemiarthroplasty is described and illustrated.

Functionalization of a zirconia surface by covalently immobilized fibronectin and its effects on resistance to thermal, acid, and mechanical exposure.

Silane chemistry has emerged as a powerful tool for surface modification, offering a versatile means to enhance the properties of various substrates, such as dental implant abutment materials. In this study, we investigated the stability of the 3-aminopropyldiisopropylethoxysilane (APDS) layer on yttria-partially stabilized zirconia (Y-TZP) surfaces after mechanical, acid, and thermal treatment in order to simulate fluctuations within the oral cavity. To accomplish that, the viability of human gingival fibroblasts on APDS-modified surfaces after applied treatment strategies was assessed by live/dead staining. Moreover, the hydrolysis stability and enzymatic degradation resistance of crosslinked fibronectin to the APDS layer was examined by immunostaining and western blot. The results revealed that the applied modifications were not affected by the different treatment conditions and could withstand the fluctuations in the oral cavity. Furthermore, crosslinked fibronectin on silanized Y-TZP was stable against hydrolysis over 21 days and enzymatic degradation. We thus can conclude that the proposed functionalization method has high potential to tolerate harmful effects within the oral cavity and remains unchanged on the surface.

The Effect of Timing Between Traumatic Flexor Tendon Injury of the Hand and Surgical Intervention on Repair Failure Rates.

Flexor tendon injuries of the hand, especially in zone II, pose a challenge for hand surgeons because of the region's intricate pulley mechanism and local avascularity, and post-surgical complications such as repair failure are not uncommon. One proposed predictor of outcomes following flexor tendon repair has been timing of surgery from initial injury. However, the effect of the timing of flexor tendon repair on failure rates remains controversial and understudied. The purpose of this study was to compare the failure rates of zone II flexor tendon repairs in patients at various time intervals from onset of injury. A retrospective chart review was conducted using data from hand surgery specialists at our level 1 trauma center from January 1, 2010, through May 31, 2020. This retrospective review included 407 zone II flexor tendon repairs. The primary outcome was failure of repair. Among 407 flexor tendon repairs, there were 12 reported repair failures. The failure rate was 2.9%. In the non-failure group, the mean number of days between the date of injury and the date of surgery was 7±13 days. For the failure group, this value was 14±17 days. Repairs occurring within 14 days had a failure rate of 2.3%, while repairs occurring beyond 14 days had a failure rate of 7.7%. This study demonstrates that there is a benefit to repairing the tendon within a 14-day window, as evidenced by a lower failure rate. More research is required to determine if other complications and overall health of the hand are also improved when a repair is performed in a more expedient manner. [Orthopedics. 2024;47(2):113-117.].

A Logistic Regression Analysis of Factors Associated with Guarded Outcome after Carpal Tunnel Release in Symptomatic Carpal Tunnel Syndrome.

BACKGROUND: The Boston Carpal Tunnel Questionnaire (BCTQ) is a validated measurement tool to assess the severity of carpal tunnel syndrome, and improvements in the BCTQ after carpal tunnel release (CTR) have been demonstrated to influence patient satisfaction. The authors hypothesized that patient-related factors influence response in BCTQ subscales, including the Symptom Severity Scale and the Functional Status Scale, after CTR. METHODS: Patients who underwent surgery with follow-up BCTQ were identified from a prospectively maintained database. Paired t tests were used to compare BCTQ subscales at each follow-up time point. Minimal clinically important differences were set. Patients below these thresholds were deemed as having failure to improve after CTR. Univariate analysis was used to identify risk factors for failure to improve after CTR. Multivariate logistic regression was used to identify independent predictors for failure to improve after CTR. RESULTS: A total of 106 patients met inclusion criteria. Patients demonstrated significant improvements at all follow-up time points. The factor most associated with improvement beyond the minimal clinically important differences was a more severe score in the respective domain assessed. Other independent factors that influenced outcome after CTR included race, concomitant cubital tunnel release, sex, and age. CONCLUSIONS: CTR results in significant improvements in BCTQ and its subscales, with improvements stabilizing after 6 weeks. In a select cohort of patients, failure to improve after CTR occurs with factors independently associated with a lower degree of improvement. Identification of patients with these risk factors will provide a basis for counseling and increased monitoring of patients at risk for a guarded prognosis. CLINICAL QUESTION/LEVEL OF EVIDENCE: Risk, III.

Static stability of novel uncemented elbow hemiarthroplasty stabilized with ligament reconstruction.

BACKGROUND: The purpose of this study was to create a model to simulate treatment of unreconstructable distal humerus fractures with hemiarthroplasty. Stability was restored with a latest plate-system that simultaneously tensions medial and lateral collateral ligament grafts. MATERIALS AND METHODS: Static varus and valgus elbow stability was tested in 11 cadaver elbows with intact ligaments and capsule at 5 flexion angles (0°, 30°, 60°, 90°, 120°). The elbows were then destabilized via release of all ligaments and capsular attachments. The distal humerus articular cartilage was excised and replaced with an uncemented hemiarthroplasty. Ligament reconstruction was subsequently performed, and elbow stability was measured and compared to the native state. Dimensions of the hemiarthroplasty component were compared to native elbow dimensions to assess and quantify any existing relationship to elbow stability. RESULTS: A hemiarthroplasty was implanted in all specimens. A size mismatch occurred between the distal humerus trochlea and the olecranon fossa in all specimens and averaged 6.3 mm. Following ligament reconstruction, specimens reproduced the flexion angle-dependent stability of native elbows to both varus and valgus stress. On the medial side, elbow joint stability in mid-flexion was approximately 7% tighter after hemiarthroplasty. Laterally, the elbow was approximately 15% tighter after hemiarthroplasty and demonstrated peak stability in full flexion. The 3 assessed hemiarthroplasty components and bony dimensions did not exhibit any relationship between implant-bone mismatch and elbow stability after ligamentous reconstruction. CONCLUSION: Cadaveric elbow specimens underwent uncemented hemiarthroplasty with soft tissue stabilization with a novel technique for ligament reconstruction. Following hemiarthroplasty and ligament reconstruction, these specimens maintained secure fixation between ligament and bone. Static stability was maintained at varying degrees of elbow flexion regardless of variable mismatch between the hemiarthroplasty component and the native olecranon fossa.

Establishing regions of interest of the lower leg and ankle for perioperative volumetric assessment with a portable 3D scanner in orthopedic and trauma surgery - a pilot study.

BACKGROUND: Soft tissue swelling assessment benefits from a reproducible and easy to use measurement method. Monitoring of the injured lower extremity is of clinical import during staged soft tissue management. Portable 3D scanners offer a novel and precise option to quantify and contrast the shapes and volumes of the injured and contralateral uninjured limbs. This study determined three regions of interest (ROI) within the lower extremity (lower leg, ankle and foot), that can be used to evaluate 3D volumetric assessment for staged soft tissue management in orthopedic and trauma surgery. METHODS: Twelve healthy volunteers (24 legs) were included in this cohort study. Scans of all three ROI were recorded with a portable 3D scanner (Artec, 3D scanner EVA) and compared between the right and left leg using the software Artec Studio (Arctec Group, Luxemburg). RESULTS: Mean volume of the right leg was 1926.64 ± 308.84 ml (mean ± SD). ROI: lower leg: 931.86 ± 236.15 ml; ankle: 201.56 ± 27.88 ml; foot: 793.21 ± 112.28 ml. Mean volume of the left leg was 1937.73 ± 329.51 ml. ROI: lower leg: 933.59 ± 251.12 ml; ankle: 201.53 ± 25.54 ml; foot: 802.62 ± 124.83 ml. There was no significant difference of the overall volume between right and left leg (p > 0.05; overall volume: △ difference: 29.5 ± 7.29 ml, p = 0.8; lower leg: △ difference: 21.5 ± 6.39 ml, p = 0.8; ankle: △ difference: 5.3 ± 2.11 ml, p = 0.4; △ difference: 16.33 ± 4.45 ml, p = 0.8. CONCLUSION: This pilot study defines three regions of interest of the lower leg and demonstrates no difference between the right and left side. Based on these ROI, further studies are needed to evaluate the clinical applicability of the scanner.

A Dynamic Elbow Testing Apparatus for Simulating Elbow Joint Motion in Varying Shoulder Positions.

Purpose: To develop and evaluate the capabilities of a dynamic elbow testing apparatus that simulates unconstrained elbow motion throughout the range of humerothoracic (HTA) abduction. Methods: Elbow flexion was generated by six computer-controlled electromechanical actuators that simulated muscle action, while six degree-of-freedom joint motion was measured using an optical tracking device. Repeatability of joint kinematics was assessed at four HTA angles (0°, 45°, 90°, 135°) and with two muscle force combinations (A1-biceps brachialis, brachioradialis and A2-biceps, brachioradialis). Repeatability was determined by comparing kinematics at every 10° of flexion over five flexion-extension cycles (0° to 100°). Results: Multiple muscle force combinations can be used at each HTA angle to generate elbow flexion. Trials showed that the testing apparatus produced highly repeatable joint motion at each HTA angle and with varying muscle force combinations. The intraclass correlation coefficient was greater than 0.95 for all conditions. Conclusions: Repeatable smooth cadaveric elbow motion was created that mimicked the in vivo situation. Clinical relevance: These results suggest that the dynamic elbow testing apparatus can be used to characterize elbow biomechanics in cadaver upper extremities.

Computed Tomography-Based Humeral Templating for Uncemented Elbow Arthroplasty.

BACKGROUND: Intramedullary (IM) screw insertion into the distal humerus provides fixation for a novel, uncemented elbow arthroplasty. A multitude of screw sizes is required to accommodate variable humeral morphology. The goal of this study was to use computed tomography (CT) for IM screw sizing and to validate this templating by inserting screws into three-dimensionally (3D) printed models. METHODS: Computed tomography humerus scans for 30 patients were reformatted in the plane of the distal IM canal. Screw size was templated by measuring the canal diameter at 3 locations corresponding to the lengths of the screws being tested. Interrater and intrarater reliabilities of the measurements were assessed. Three-dimensional models of 5 humeri were printed, and IM screws were placed to achieve a secure endosteal fit. RESULTS: We identified combinations of body components and IM screw length and diameter for all patients to seat this uncemented elbow arthroplasty. The measurements and screw width determinations were reliable. Canal diameter correlated with age but was unrelated to sex. Screws were inserted into five 3D-printed models which matched the templates and demonstrated mechanical and radiographic evidence of secure fit. CONCLUSIONS: This study characterizes distal humerus anatomy in the context of IM screw fixation. Humerus CT scans of 30 patients were able to be templated, and validation via implantation of IM screws into 3D models was successful. Computed tomography templating will allow surgeons to predict the optimal screw size prior to implantation. A broad range of screw lengths and diameters is critical for implantation of this novel elbow arthroplasty.

Long-Term, Self-Dosing CBD Users: Indications, Dosage, and Self-Perceptions on General Health/Symptoms and Drug Use.

Introduction: Self-dosing of off-the-shelf cannabidiol (CBD) for a myriad of health conditions is common in the USA. These CBD products are often mislabeled, suggesting that much less or much more CBD is being consumed than indicated on the label. This study examined the relationship between long-term self-dosing of CBD and (a) indications and, when a verified concentration of CBD is being consumed, (b) the daily CBD dosage, (c) the impact on general health and symptoms, and (d) over-the-counter (OTC) and prescription (Rx) drug usage. Methods: US adults 18-75 years of age who had used unverified CBD products for >1 month were recruited to participate in this decentralized, observational, IRB-approved study and provided a concentration-verified CBD product of their choice from 15 different vendors for 4 weeks. Prior to receiving product, they were queried on their primary reason for use (PRfU), primary symptom for use (PSfU), general health score (GHS), symptom score (SS), OTC and Rx drug use, and daily CBD dose. Individuals were queried daily on OTC and Rx drug use and CBD dose and weekly on SS and GHS prior to (pre-CBD) and after (post-CBD) ingestion of CBD on that day. Results: The PRfU included chronic pain, mental health, general health and wellness, sleep disorders, the central nervous system, digestive health, and others, while the PSfU included anxiety, back and/or joint pain, sleep, inflammation, and others. The mean daily dose was normally distributed, with a mean, median, and range of 53.1, 40.8, 8-390 mg/day, respectively. For both GHS and SS, the post-CBD was significantly higher than the pre-CBD score for each category of PRfU. The GHS scores did not change over the study, but pre- and post-CBD SS improved over time, with pre-improving more than post-CBD SS. The percentage of individuals decreasing or completely stopping OTC drugs or Rx drugs over the 4 weeks was 31.2% and 19.2%, respectively, with those taking CBD for chronic pain, decreasing drug use the most. OTC and Rx drug usage decreased when the CBD dose was changed and when GHS and SS improved. Conclusion: Pain, mental health (primarily anxiety/stress), and sleep are the most common reasons for CBD use. Self-administration of CBD reduced OTC and Rx drug usage at daily doses less than those reported in controlled studies. CBD self-administration significantly improves self-perception of general health and decreases symptom severity, and as these improve, fewer OTC and Rx drugs are used.

The Effect of Elbow Flexion On Valgus Carrying Angle.

PURPOSE: This study aimed to examine the effect of flexion on valgus carrying angle in the human elbow using a dynamic elbow testing apparatus. METHODS: Active elbow motion was simulated in seven cadaveric upper extremities. Six electromechanical actuators simulated muscle action, while 6 degrees-of-freedom joint motion was measured with an optical tracking system to quantify the kinematics of the ulna with respect to the humerus as the elbow was flexed at the side position. Repeatability of the testing apparatus was assessed in a single elbow over five flexion-extension cycles. The varus angle change of each elbow was compared at different flexion angles with the arm at 0° of humerothoracic abduction or dependent arm position. RESULTS: The testing apparatus achieved excellent kinematic repeatability (intraclass correlation coefficient, >0.95) throughout flexion and extension. All elbows decreased their valgus carrying angle during flexion from 0° to 90° when the arm was maintained at 0° of humerothoracic abduction. Elbows underwent significant total varus angle change from full extension of 3.9° ± 3.4° (P = .007), 7.3° ± 5.2° (P = .01), and 8.9° ± 7.1° (P = .02) at 60°, 90°, and 120° of flexion, respectively. No significant varus angle change was observed between 0° and 30° of flexion (P = .66), 60° and 120° of flexion (P = .06), and 90° and 120° of flexion (P = .19). CONCLUSIONS: The dynamic elbow testing apparatus characterized a decrease of valgus carrying angle during elbow flexion and found that most varus angle changes occurred between 30° and 90° of flexion. All specimens underwent varus angle change until at least 90° of flexion. CLINICAL RELEVANCE: Our model establishes the anatomic decrease in valgus angle by flexion angle in vitro and can serve as a baseline for testing motion profiles of arthroplasty designs and ligamentous reconstruction in the dependent arm position. Future investigations should focus on characterizing motion profile change as the arm is abducted away from the body.

Do Intramedullary Screws Provide Adequate Fixation for Humeral and Ulnar Components in Total Elbow Arthroplasty? A Cadaveric Analysis.

PURPOSE: The objective of this study was to determine the structural properties of the cadaver bone-screw interface for cementless intramedullary screw fixation in the context of total elbow arthroplasty. METHODS: The intramedullary canals of seven humerus and seven ulna specimens from fresh-frozen cadavers were drilled using custom drill bits until the inner cortex was reached and then hand tapped for the corresponding thread size. Titanium screws were advanced into the tapped holes until securely seated. The bones were potted and then mounted on a uniaxial material testing machine. A tensile load was applied, and end-of-test elongation, failure load, energy absorbed, and stiffness were determined. End-of-test load and elongation were defined as the elongation and load experienced by the structure at 3,000 N or failure. Each specimen was inspected for evidence of pullout, loosening, or visible fractures. RESULTS: The end-of-test load and elongation for the humerus specimens were 2721 ± 738 N and 3.0 ± 0.9 mm, respectively. The ulna specimens reached 92% of the humerus specimens' end-of-test load at 2,514 ± 678 N and 120% of their end-of-test elongation (3.6 ± 0.6 mm). The stiffness of the humerus specimens was 1,077 ± 336 N/mm, which was 1.3 times greater than the stiffness of the ulna specimens (790 ± 211 N/mm). Lastly, the energy absorbed by the humerus samples was 3.6 ± 1.6 J, which was 92% of the energy absorbed by the ulna samples at 3.9 ± 1.1 J. One humerus and three ulnas failed before the end-of-test load of 3,000 N. Two failures were caused by screw pullout and two by bone fracture. CONCLUSIONS: Our findings demonstrate that intramedullary screw fixation is successful in withstanding forces that are greater than required for osseointegration. CLINICAL RELEVANCE: Uncemented fixation may be beneficial in elbow arthroplasty.

Effect of Capitolunate Positioning on Outcomes in Scaphoid Excision and 4-Bone Fusion Patients.

BACKGROUND: Scaphoid excision and 4-bone fusion (4BF) is a surgical procedure to treat scapholunate advanced collapse. Some surgeons align the lunate over the capitates, whereas others leave the capitate in its uncovered native position. The capitolunate angle may affect long-term outcomes. This study examined whether postsurgical outcomes differed based on these differences in positioning. METHODS: A retrospective analysis was performed for patients that underwent a 4BF between 2006 and 2020. Wrist range of motion; pain (0-10); and Disabilities of the Arm, Shoulder, and Hand (DASH) scores were recorded. The width of the capitate, the width of the lunate contacting the capitate, and the capitolunate angle were measured. Pearson correlations and t tests were performed. For t tests of capitolunate uncovering, patients were divided into 2 groups: patients with 0% capitate uncovering and patients with >0% uncovering. For capitolunate angle, the 2 groups were patients with a capitolunate angle of ≤10° and patients with a capitolunate angle of >10°. RESULTS: There was a significant correlation between capitate coverage and wrist extension, but no correlation for flexion, pain, or DASH scores. Group 1 (0% uncovering) had increased wrist extension and decreased pain compared with group 2 (>0% uncovering). There were no significant correlations or differences in the analyses of capitolunate angle's impact on outcomes. CONCLUSIONS: In patients undergoing 4BF, those who had the lunate aligned to completely cover the capitate head had improved wrist extension and pain compared with patients where the capitate head was left partially uncovered. Capitolunate angle was not predictive of postsurgical outcomes.

Computed Tomography-Based Templating of Proximal Ulna Intramedullary Screw Fixation.

BACKGROUND: Intramedullary screw fixation of the proximal ulna can be used for fixation of the ulnar component in total elbow arthroplasty. Our purpose was to use computed tomography (CT) to characterize proximal ulna anatomy with respect to intramedullary screw fixation, and then to validate this templating process by inserting intramedullary screws into 3-dimensional (3D)-printed models. METHODS: Thirty elbow CT scans were reformatted in the axis of the proximal ulna. Screw placement was templated by fixing a length at 78 mm distal to the centerline of ulnohumeral rotation and measuring diameter, and then fixing the screw pitch diameter to 5.5 mm and measuring length. Three-dimensional models were printed for 5 patients, and intramedullary screws were advanced as distal as possible until endosteal fit was achieved. RESULTS: All patients had an anatomic limit for intramedullary screw fixation, due to dorsal angulation, varus angulation, or both. At 78 mm distal to the centerline of rotation, mean screw diameter was 5.4 mm (range, 3.2-8.0). When fixing screw diameter to 5.5 mm, the mean screw length was 79.9 mm (range, 64.2-107.9). All intramedullary screws were placed in the 3D models within 3 mm of the templated length, with correlation coefficient 0.992. CONCLUSION: This study characterized proximal ulna anatomy in the context of intramedullary screw fixation. Templating allows surgeons to predict intramedullary screw sizing, and a broad range of screw lengths and diameters is required when attempting intramedullary screw fixation for placement of the ulnar component in uncemented total elbow arthroplasty.

Comparing Static Stability of Native Elbow With Static Stability of Novel Bidirectional Ligament Reconstruction at Different Degrees of Elbow Flexion.

Purpose: The treatment of bidirectional ligament instability is proposed using a method that simultaneously tensions medial and lateral ligaments. Graft tension is maintained via plates that apply compression between the graft and bone. Methods: We tested static varus and valgus elbow stability in six cadaver elbows with intact ligaments and capsules at five positions, and then created gross instability by dividing all soft tissue attachments. A ligament reconstruction was subsequently performed with and without nonabsorbable ligament augmentation. Elbow stability was measured and compared with the native state. Results: The augmented and the nonaugmented ligament reconstructions provided stability to the lateral side with only 1.0 mm of increased deflection recorded for the augmented ligaments and 0.6 mm for the nonaugmented when compared with the native state. On the medial side, the deflection was greater after reconstruction compared with the native state with the augmented ligaments ranging between 1.0 and 1.8 mm and the nonaugmented ligament reconstruction ranging between 2.4 and 3.3 mm. Conclusions: This novel ligament reconstruction maintained secure fixation between ligament and bone and allowed for maintenance of static stability at different degrees of elbow flexion. Clinical Relevance: Restoring elbow stability using a method that minimizes ligament graft and which may not need to be removed could benefit management of bidirectionally unstable elbows, such as following interposition arthroplasty or substantial trauma.

Posterior Flange Cyclic Loading in a Novel Total Elbow Arthroplasty.

Purpose: The goal of this study was to test the static and dynamic strength and loosening resistance of the posterior flange of a novel total elbow arthroplasty. We also examined the forces experienced by the ulnohumeral joint and the posterior olecranon during expected elbow use. Methods: Static stress analysis was performed for 3 flange sizes. Failure testing was conducted on 5 flanges (1 medium size and 4 small sizes). Loading occurred to reach 10,000 cycles. If this was accomplished, the cyclic load was increased until failure occurred. If failure occurred before 10,000 cycles, a lower force was employed. The safety factor for each implant size was calculated, and implant failure or loosening was observed. Results: Static testing revealed a safety factor of 6.6, 5.74, and 4.53 for the small, medium, and large flanges, respectively. The medium-sized flange completed 10,000 cycles with 1,000 N at 1 Hz, and then the force was increased until it failed at 23,000 cycles. Two small-sized flanges failed at 2,345 and 2,453 cycles, respectively, when loaded with 1,000 N. Two more small flanges were loaded with 729 N for 10,000 cycles, and then the cyclic load was continued until they failed at 17,000 and 17,340 cycles, respectively. No screw loosening was noted in any specimens. Conclusions: This study demonstrates that the posterior flange withstood static and dynamic forces greater than what is expected during in vivo use of a novel total elbow arthroplasty design. Static strength calculation and cyclic loading demonstrate that the medium-sized posterior flange is stronger than the small-sized posterior flange. Clinical Relevance: Ensuring that the ulnar body component and the posterior flange maintain secure connectivity with the polyethylene wear component may be beneficial to the proper function of a novel nonmechanically linked total elbow arthroplasty.

Comparison of Patient-Reported Outcomes With or Without Prophylactic Carpal Tunnel Release After Distal Radius Fracture Stabilization.

Distal radius fractures (DRFs) are frequently complicated by acute carpal tunnel syndrome (CTS), which, if unrecognized, can cause permanent median neuropathy. Some surgeons recommend "prophylactic" carpal tunnel release (CTR) during open reduction and internal fixation (ORIF) of DRF. Patient-reported outcomes (PROs) and safety data regarding prophylactic vs symptomatic CTR strategies during DRF fixation are lacking. We conducted a retrospective review of two management strategies for DRFs at our institution (2017 to 2019). Group 1 consisted of patients operated on by two surgeons performing ORIF and symptomatic CTR only for acute CTS. Group 2 consisted of patients operated on by a third surgeon performing ORIF and prophylactic CTR on all patients irrespective of median nerve symptoms. The PROs included QuickDASH Wrist and PROMIS physical/mental health preoperatively vs at final follow-up. Demographic information, complications, and return to the operating room were recorded. Group 1 (36 patients) and group 2 (76 patients) were demographically similar. The mechanism of injury was more severe in group 1 (P<.05), but preoperative PROs were similar between the two groups. Eight patients (22.2%) in group 1 had symptomatic CTR for acute CTS. Significant improvement occurred within both groups from preoperative to final follow-up for PROMIS physical function and QuickDASH Wrist scores (P<.05). Intergroup PROs were not significantly different at either time point. One patient in group 1 (2.8%) and 2 patients in group 2 (2.6%) returned to the operating room due to median nerve symptoms (P>.05). A prophylactic CTR strategy is not associated with improved PROs compared with a symptomatic strategy during ORIF of DRF. [Orthopedics. 2023;46(6):e362-e368.].

Sub-continental-scale carbon stocks of individual trees in African drylands.

The distribution of dryland trees and their density, cover, size, mass and carbon content are not well known at sub-continental to continental scales1-14. This information is important for ecological protection, carbon accounting, climate mitigation and restoration efforts of dryland ecosystems15-18. We assessed more than 9.9 billion trees derived from more than 300,000 satellite images, covering semi-arid sub-Saharan Africa north of the Equator. We attributed wood, foliage and root carbon to every tree in the 0-1,000 mm year-1 rainfall zone by coupling field data19, machine learning20-22, satellite data and high-performance computing. Average carbon stocks of individual trees ranged from 0.54 Mg C ha-1 and 63 kg C tree-1 in the arid zone to 3.7 Mg C ha-1 and 98 kg tree-1 in the sub-humid zone. Overall, we estimated the total carbon for our study area to be 0.84 (±19.8%) Pg C. Comparisons with 14 previous TRENDY numerical simulation studies23 for our area found that the density and carbon stocks of scattered trees have been underestimated by three models and overestimated by 11 models, respectively. This benchmarking can help understand the carbon cycle and address concerns about land degradation24-29. We make available a linked database of wood mass, foliage mass, root mass and carbon stock of each tree for scientists, policymakers, dryland-restoration practitioners and farmers, who can use it to estimate farmland tree carbon stocks from tablets or laptops.