Functional Dart-Throwing Motion: A Clinical Comparison of Four-Corner Fusion to Radioscapholunate Fusion Using Inertial Motion Capture.

Background Dart-throwing motion (DTM) is an important functional arc of the wrist from radial extension to ulna flexion. An aim of partial fusion surgery of the wrist is to maintain maximal functional motion while addressing the pathology. The radioscapholunate (RSL) fusion, accompanied with partial resection of the distal scaphoid, is thought to allow better DTM than other partial wrist fusions such as the four-corner fusion (4CF). Question Does an RSL fusion allow better functional DTM than 4CF, and how does this range compare with healthy wrists and the patient's contralateral wrist? Patients and Methods Patients who have undergone an RSL fusion or 4CF at our tertiary center were identified and invited to present to have their DTM arc measured. To accurately measure DTM, a previously validated inertial measurement device was used. Patient's functional DTM arc was measured in both unrestrained (elbow and shoulder free to move) and restrained (elbow and shoulder immobilized) fashions. This was compared with their contralateral wrist and a group of healthy control volunteers. Results Overall five RSL fusions, 10 4CF and 24 control patients were enrolled in the study. There was no significant difference between functional DTM when 4CF and RSL fusion were compared. Both had significantly reduced functional DTM arc than control patients. There was no significant difference between the operated wrist compared with the patient's contralateral unoperated wrist. Conclusion RSL fusion is not significantly better at maintaining functional DTM when compared with 4CF. Both surgeries result in decreased functional DTM arc when compared with control patients. This is a cohort study and reflects a level of evidence IV. Level of Evidence This is a Leve IV, cohort study.

Qualification of Wrist Functional Performance During Dart Thrower's Movement.

Recently, numerous comprehensive studies have been concentrating on the intricate kinematics of the wrist joint functionality captured with dart thrower's movement. It is envisaged that the wrist capability in performing daily activities can be more accurately characterized or encapsulated in the dart thrower's movement. This study examines the characteristic function of wrist movements during dart-throwing motion using only gyroscopic data measured from inertial sensors. A multi-dimensional form of dart throwing trajectory is described using quaternion representation associated with distance metric to quantitatively validate the functional wrist performance between two cohorts; healthy controls and patients. Eight normal subjects and eight patients engaged in a series of clinical trials conducted after undergoing post-surgical reconstructive procedures of the wrist joint. The discriminative results in terms of silhouette clustering evaluation show that the use of distance metric values based quaternion trajectory is well-matched consistently with subjective expert assessments. Our proposed approach captures the relative motions underpinning the wrist joint instead of relying on the traditional measure based on the range of motion measure. Therefore, this paper proposes a reliable approach to dynamically capture the wrist functionality during dart thrower's movement; a movement envisaged to describe the ability to engage in daily life activities. These quantitative outcomes in terms of measurement consistency will provide insightful information in understanding the significant changes in wrist joint signatures associated with various scenarios.

Quantifying the human finger reachable space.

Describing the flexibility of the hand using the reachable space concept has drawn the attention of many researchers in recent years. Existing approaches involving numerical techniques to obtain the reachable space are generally computationally expensive. In this study, we propose a resource-friendly approach to determine and quantify the bidimensional reachable space of the finger. The fundamental idea of the approach connects to a set of arc formulae for the boundary of the reachable space. These formulae of the boundary result a unique description to calculate the area of the reachable space using Green's theorem. Adopting this novel approach, reachable spaces can be visualised and quantified to effectively evaluate the functionality of different subjects and their therapeutic conditions. We evaluated the performance of the proposed approach against the popular kinematic feedforward approach and Monte Carlo simulation separately. The exclusive description of the reachable space boundary resulted in significant improvement to the execution time while delivering more accurate quantification values.