Elbow load with various forearm positions during one-handed pushup exercise

Elbow joint biomechanics during ADL focusing on total elbow arthroplasty - a scoping review

BACKGROUND

Overloading is hypothesized to be one of the failure mechanisms following total elbow arthroplasty (TEA). It is unclear whether the current post-operative loading instruction is compliant with reported failure mechanisms. Aim is therefore to evaluate the elbow joint load during activities of daily living (ADL) and compare these loads with reported failure limits from retrieval and finite element studies.

METHODS

A scoping review of studies until 23 November 2021 investigating elbow joint load during ADL were identified by searching PubMed/Medline and Web of Science. Studies were eligible when: (1) reporting on the elbow joint load in native elbows or elbows with an elbow arthroplasty in adults; (2) full-text article was available.

RESULTS

Twenty-eight studies with a total of 256 participants were included. Methodological quality was low in 3, moderate in 22 and high in 3 studies. Studies were categorized as 1) close to the body and 2) further away from the body. Tasks were then subdivided into: 1) cyclic flexion/extension, 2) push-up, 3) reaching, 4) self-care, 5) work. Mean flexion-extension joint load was 17 Nm, mean varus-valgus joint load 9 Nm, mean pronation-supination joint load 8 Nm and mean bone-on-bone contact force 337 N.

CONCLUSION

The results of our scoping review give a first overview of the current knowledge on elbow joint loads during ADL. Surprisingly, the current literature is not sufficient to formulate a postoperative instruction for elbow joint loading, which is compliant with failure limits of the prosthesis. In addition, our current instruction does not appear to be evidence-based. Our recommendations offer a starting point to assist clinicians in providing informed decisions about post-operative instructions for their patients.

A biomechanical study of headless compression screws versus a locking plate in radial head fracture fixation

HYPOTHESIS

Fixation of a 3-part radial head fracture with cannulated compression screws will show equivalent stiffness to a locking plate under axial load. Debate exists regarding the management of Mason type III fractures, with many believing that open reduction and internal fixation provides advantages over other options. By virtue of their subarticular placement, screw fixation is less likely to cause impingement compared with plate fixation, which can result in loss of rotation and requirement for hardware removal. Insufficient fixation stability can lead to nonunions, necrosis of the radial head, pain, and instability. We tested the mechanical stability of fixation of simulated radial head fractures using headless compression screws compared with standard plate construct.

METHODS

Standardized test constructs were created with repeatable osteotomy cuts and hardware placement on each Synbone model (Synbone AG, Malans, Switzerland). We presectioned 22 proximal radius Synbone models to simulate a 3-part radial head fracture. The models were fixed using a radial head locking plate or headless compression screws in a tripod construct. The constructs were potted into a compression test jig using 2-part epoxy resin. Compression testing was performed using a 30-kN Instron Universal machine (Instron, Norwood, MA, USA). The compression tool was spherical, representing the surface of the capitellum.

RESULTS

There was no significant difference between the stiffness of the Synbone constructs under axial load.

CONCLUSION

There was no significant difference between fixation stiffness of a 3-part radial head fracture with headless compression screws in a tripod structure vs. a locking plate in Synbone. Further study is required to allow clinical application.

Effect of various forearm axially rotated postures on elbow load and elbow flexion angle in one-armed arrest of a forward fall

BACKGROUND

Falling onto the outstretched hand is a major cause of upper extremity injury. The overall objectives of this study were to develop an experimental model for elbow load during a simulated fall onto one-armed arrest using three different forearm axially rotated postures as alternative fall arrest strategies. Additionally, the relationship between the elbow flexion angle and different axially rotated postures were also investigated.

METHODS

Fifteen healthy young male Taiwanese graduate students with an average age of 23 years were studied. Subjects performed a one-armed arrest of a 5 cm fall onto a force plate. Each subject fell onto the force plate with his forearm 45 degrees axial externally rotated (ER), non-rotated (NR), and 45 degrees axial internally rotated (IR) postures. Kinematics and kinetics of the upper extremity were calculated and analyzed by using laboratory-developed motion analysis procedures.

FINDINGS

The valgus-varus shear forces in the ER group were 1.4 times greater than the NR group, and 2.7 times greater than the IR group. The elbow joint remained at almost full extension in the ER (3.9 degrees) group, while elbow flexion angle was observed in the NR (24.6 degrees) and IR (40.3 degrees) groups.

INTERPRETATION

A fall onto the outstretched hand with an externally rotated forearm should be avoided in order to reduce excessive valgus-varus shear force on the elbow joint. Knowledge of elbow kinematics and kinetics during a forward fall with various forearm axially rotated posture may be helpful in preventing injuries.

Technique and safety aspects of resistance exercises: a systematic review of the literature

A systematic review of the scientific literature was conducted to identify the optimal ranges of motion for preventing injury in the main joints of the body during resistance exercise performance. These ranges of motion are independent of the type in which the resistance exercises could be applied (ie, adults, elderly, athletes, recreational exercisers), and the regions examined include the shoulder, spine, and knee, which are injured most often. It can be concluded that during the performance of any resistance exercise, it is possible to put anatomical structures at risk with certain body positions; therefore, it is necessary to understand these movements so injury can be avoided.

Direction of the load on the elbow of the ball blocking handball goalie

Elbow problems in goalkeepers in team handball "handball goalie's elbow" is common. The accepted mechanism in the common injuries is hyperextension of the elbow. The purpose of this study was to describe the elbow position at the time of impact of the ball on the hand. This study is based on video-analysis. Fifteen handball goalies (ten females and five males) who had been playing handball for a mean time of 6.5 years were used in the study. The participants were not aware of the details of the study. A national team member attacker performed repetitive shots toward the right side of each goalkeeper. The goalkeepers blocked the ball with their own usual style. Each block was videotaped with three digital cameras (one side view, one superior view, and one frontal view). The captured shots were later evaluated by three analysts as to the elbow position at the time of the impact. Seventy-eight out of 101 shots (77%) were valgus or mostly valgus load producing shots. The remaining 23 (23%) were hyperextension or mostly hyperextension load producing shots. This study shows that the elbows of the handball goalkeepers experience valgus loads at the time of ball blockade during the penalty shoot-out. A detailed understanding of the mechanism of the loads on the handball goalkeepers' elbow will help in defining ways to prevent and to treat handball goalie's elbow.