Biomechanics and Pinch Force of the Index Finger Under Simulated Proximal Interphalangeal Arthrodesis

Arthrodesis of the Proximal Interphalangeal Joint of the Finger—A Biomechanical Study of Primary Stability

Background: Osteoarthritis of the proximal interphalangeal (PIP) joint of the finger often leads to global hand-function detriment. Different techniques for the arthrodesis of the proximal interphalangeal joint have been described that all lead to union in a reasonable percentage of patients and period of time. This biomechanical study aims to analyze and compare the primary stability of different techniques of arthrodesis to render postoperative immobilization unnecessary. Methods: Arthrodeses of 40° of composite cylinders were tested with different techniques in four-point bending for stability in extension as well as flexion. Results: In extension, the compression screw and the compression wires showed the highest stability—whereas in flexion, plate fusion was superior. Tension band, cerclage or compression screw fusion showed the best compromise in flexion/extension stability. Conclusions: Fusion techniques that apply compression to the fusion show superior stability. Cerclage, tension band and compression screws might be able to provide enough stability to withstand the forces exerted during unencumbered activities of daily living. Arthrodesis with plates should be limited to patients with special indications and require immobilization during consolidation.

Functional evaluation of optimal index finger proximal interphalangeal joint fusion angle using a simulated joint arthrodesis

This study aims at qualitatively and quantitatively evaluating the effects of simulated index finger proximal interphalangeal (PIP) joint fusion angles on hand kinematic function and performance. Although arthrodesis of the index finger PIP joint is an effective medical procedure that produces a durable, pain-free, and stable joint, it permanently immobilizes the joint. Twenty healthy subjects performed basic functional hand activities with the index finger PIP joint unconstrained (UC) and constrained to selected angles under surveillance of a motion capture system. Our results indicate differences in perceived difficulty, time performance, and the functional ROM of the hand joints when the index finger PIP joint is UC and constrained to 0, 20, and 40 degrees of flexion. The mean total perceived difficulty scores for all 6 tasks were higher for the PIP at 0 degrees than for the UC condition (p < 0.001) and for the PIP at 40 degrees (p = 0.048). The functional ROM presented a smaller total number of hand joints affected by the PIP at 20 degrees (25 in total) than the PIP at 0 (31 in total) and 40 (27 in total) degrees during execution of all 6 tasks tested. Therefore, the decision on the appropriate index finger PIP angle for arthrodesis may be between 20 and 40 degrees, as globally for all 6 tasks tested, 0 degrees exhibited the worst results regarding perceived difficulty, performance time, and number of joints with affected ROM. Selecting the appropriate angle for arthrodesis should consider a more complete set of functional activities.

[Effect of a single proximal interphalangeal Joint Fusion of the Index, Middle or Ring Finger on the Grip and Finger Force and Load Distribution in the Hand]

BACKGROUND

Due to the functional coupling of adjacent finger joints and the quadriga effect, arthrodesis of the proximal interphalangeal joint (PIPJ) can be assumed to lead to a different grip pattern resulting in altered force distribution of the hand.

PATIENTS AND METHOD

Ten patients with isolated arthrodesis of the PIPJ due to posttraumatic osteoarthritis (4×PIPJ II, 4×PIPJ III, 2×PIPJ IV) were assessed 59 (17-121) months postoperatively on average. The angle of arthrodesis was assessed by radiographs. Grip force and load distribution of both hands were measured by manugraphy using 3 differently sized cylinders. Grip force was separately assessed and compared for the whole hand as well as for each of the fingers and each phalanx.

RESULTS

Average total grip force of the affected hand compared to the uninjured opposite side was 74% (38-136%) for the small cylinder, 104% (68-180%) for the mid-sized cylinder and 110% (69%-240%) for the large cylinder. Arthrodesis of the PIPJ of the index finger led to a reduction of the grip force (91%) for the small cylinder, but increased grip force for the mid-sized (120%) and large cylinder (139%). Grip force was reduced for all cylinder sizes by arthrodesis of the PIPJ of the middle finger (56%, 88% and 91%). Arthrodesis of the PIPJ of the ring finger resulted in a grip force of 76%, 105% and 91%, respectively, for the different cylinder sizes.The finger force of the affected finger was reduced after arthrodesis of the PIPJ, with the exception of the index finger, which was stronger than the unaffected opposite finger when using the large cylinder. The force of the healthy fingers on the affected side was greater when compared with the same finger on the opposite side, which led to increased grip force for the mid-sized and the large cylinder of the affected hand. A reduction in load distribution was measured mostly for the middle phalanx but also for the distal phalanx of the operated-on finger.

CONCLUSION

Arthrodesis of the PIPJ almost always led to force reduction in the middle and distal phalanx of the affected finger. However, the total grip force of the hand was compensated by a higher force of the adjacent healthy fingers. In many cases, total grip force was even higher on the affected side. However, arthrodesis of the PIPJ resulted in a noticeable force reduction when smaller objects were gripped.

Tamai Zone 1 Fingertip Amputation: Reconstruction Using a Digital Artery Flap Compared With Microsurgical Replantation

PURPOSE

The surgical treatment of fingertip amputations is controversial. This study was designed to compare the clinical results of 2 surgical procedures for fingertip amputation: reconstruction with a digital artery flap and microsurgical replantation.

METHODS

Between 2003 and 2015, 37 patients with Tamai zone 1 fingertip amputation of the index or middle finger were treated by reconstruction with a digital artery flap (n = 23) or microsurgical replantation (n = 14). Data for these patients were evaluated retrospectively. Nerve suture was not conducted in microsurgical replantation because spontaneous sensory recovery is expected in zone 1 replantation. Primary outcomes included hand dexterity (Purdue Pegboard Test), and disability of the upper extremity (Disabilities of the Arm, Shoulder, and Hand score). Secondary outcomes included strength (key pinch), digital sensitivity (Semmes-Weinstein test), and finger mobility (% total active motion).

RESULTS

The average follow-up period was 34 months. There was no significant difference in the primary outcomes between the 2 groups. The reconstruction group showed significantly better results for the secondary outcomes.

CONCLUSIONS

This study suggests that the 2 procedures were comparable regarding postoperative activities of daily living and hand performance, but reconstruction using a digital artery flap gave better objective functional outcomes than microsurgical replantation.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic IV.