Biomechanical differences of the proximal interphalangeal joint volar plate during active and passive motion: a dynamic ultrasonographic study

Dynamic study of the finger interphalangeal joint volar plate-motion analysis with magnetic resonance cinematography and histologic comparison

OBJECTIVE

We aimed to further improve knowledge about volar plate (VP) motion of the finger proximal interphalangeal joint (PIP), by analyzing the dynamic VP shape during a full range of finger flexion using magnetic resonance cinematography of the fingers (MRCF), and to compare the results with anatomical cross sections from cadaver specimens.

MATERIALS AND METHODS

The dynamic sagittal VP shape was visualized with MRCF in a total number of 23 healthy volunteers. The length, angle, and thickness as well as the contact length of the VP to the PIP joint base were measured. Statistical analysis included t-test or rank-sum testing. Anatomical cross sections with differing degrees of PIP joint flexion were obtained from 12 cadaver specimens (fingers) for comparison.

RESULTS

Significant positive correlations between PIP joint flexion angle and VP area, length, depth and the VP contact length were found. This matched histologically to fiber rearrangements especially within the loose third VP layer.

CONCLUSION

Our study analyzed the full range of motion dynamic VP shape of the PIP joint using MRCF. This contributes to a more precise understanding of the complex interaction of the VP with the PIP joint and may facilitate evaluation of clinical cases such as VP avulsion or pulley rupture.

The Role of Dynamic Ultrasound in the Immediate Conservative Treatment of Volar Plate Injuries of the PIP Joint: A Series of 78 Patients

INTRODUCTION

The management of volar plate avulsion fractures in the context of a stable joint and a bony fragment of less than 30% has traditionally been conservative. This study was performed to assess volar plate healing with high-resolution ultrasound in order to provide early full mobilization.

MATERIAL AND METHODS

Between January 2012 and December 2013, 78 patients with volar plate injuries of the proximal interphalangeal (PIP) joints (42 distortions and 36 dislocations) were treated conservatively in our department for volar plate avulsion fracture associated with stable joint and bony fragment inferior to 30% of the intra-articular surface assessed both by radiography and ultrasound. Conservative treatment included extension stop splinting for the first 2 weeks and Coban bandage until 6 weeks postinjury. However, it may be possible to modify the duration of extension stop splinting based on clinical and ultrasound findings (with no additional X-ray) performed every 2 weeks for the first 3 months and then at 4 months postinjury. Only patients with residual contracture at the 4-month assessment had prolonged follow-up in order to ensure adequate dynamic splint therapy.

RESULTS

The amount of soft tissue oedema and the mobility of the volar plate were factors used to determine return to full mobilization. Mean extension-stop-splint wear was 16 ± 2 days. During the first 2 follow-up assessments, 4 patients were excluded from the study because of the instability of the PIP joint. One patient required refixation of a large fragment of 30%, 2 patients required superficial flexor tendon (FDS) tenodesis of the unstable volar plate in hyperextension and 1 other patient required arthrodesis of the PIP joint. In 51 patients, the postoperative follow-up was free of complications at 4 months. In 18 patients, flexion contracture of 20° (range 11°-40°) and oedema during follow-up required dynamic extension splints for 3 to 5 months. After this time, 5 patients had a residual contracture of 10° to 15°.

CONCLUSION

Avulsion fractures of the volar plate at the PIP joint are common. In general, they have a good outcome using the conservative treatment with extension block splints. Flexion contracture is a common complication and may be reduced by immediate splints in full extension at night and Coban bandage during the day. High-resolution sonography is a convenient tool to evaluate palmar plate stability, to assess reduction of oedema, and thus to guide safe return to full range of movement.

Ultrasonographic characteristics of volar-lateral ligament constrains after proximal interphalangeal joint injuries

Objective To characterise posttraumatic constrains of the volar-lateral ligaments by analysing volar plate (VP) dynamics after proximal interphalangeal (PIP) joint injuries using ultrasonography. Materials and methods From the anatomical and biomechanical perspectives of the VP and its surrounding structures, posttraumatic constrains of the volar-lateral ligament were evaluated by analysing the changes of VP motion. Using ultrasound, VP motion during active flexion of 0-60° was recorded in the central sagittal plane at 12 weeks after injury. VP trajectories visualised by 5-point tracing on the VP were analysed qualitatively to detect differential patterns of the ligament constrains. Quantitatively, correlation between averaged constrain index determined by measuring volar locational values of the 5 points on the VP and limitation in extension at the final follow-up was assessed. Results Eleven patients with PIP joint injuries involving five VP avulsions, three volar intra-articular fractures, or three dorsal fracture-dislocations were included. All patients with VP avulsion revealed a totally-constrained pattern, whereas patients with intra-articular or fracture-dislocation injuries showed distally-constrained pattern or normal. Averaged constrain index was negatively correlated with limitation in extension, indicating positive contribution of volar-lateral ligament constrains to residual flexion contracture. Conclusion Ultrasonographic visualisation of VP motion characterised posttraumatic constrained conditions of the volar-lateral ligaments. Knowledge of the manner of ligament damages might be useful to set treatment strategies for PIP joint injuries.

In Vivo length changes of the proximal interphalangeal joint proper and accessory collateral ligaments during flexion

PURPOSE

To investigate the length changes in proper collateral ligament (PCL) and accessory collateral ligament (ACL) during flexion of the proximal interphalangeal (PIP) joint in vivo and how portions of the PCL and ACL stabilize the PIP joint.

METHODS

We obtained computed tomography scans of the index, middle, and ring fingers of one hand from 6 volunteers at 0°, 30°, 60°, 90°, and full flexion of the PIP joint. Radial and ulnar PCL and ACL were measured and analyzed with computer modeling.

RESULTS

The data showed that during flexion the average length of the dorsal portion of the radial and ulnar PCL increased significantly and reached a maximum at 90°. The volar portion of the radial and ulnar PCL and the distal portion of the radial and ulnar ACL shortened continuously from extension to full flexion.

CONCLUSIONS

The proximal and middle portions of each ACL are nearly isometric, the dorsal portion of each PCL becomes taut only in flexion, and the volar portion of PCL and the distal portion of ACL become taut only in extension. The current findings indicate that the dorsal portion of PCL is the most stabilizing structure during flexion of the PIP joint, and that the volar portion of PCL and the distal portion of ACL provide the crucial lateral stability to the joint at extension.

CLINICAL RELEVANCE

The results may provide information relevant to the ligaments of PIP joint reconstruction and rehabilitation.

Curvatures of the DIP joints of the hand

BACKGROUND

The distal interphalangeal (DIP) joints of the hand are highly susceptible to osteoarthritis and trauma. Surgical treatment options mandate accurate characterization of their osseous anatomy; however, there are few studies that describe this. We describe the curvatures of the DIP joints by measuring the bone morphology using advanced imaging and modeling methods.

METHODS

The fingers of 16 right hand fresh frozen human cadavers were analyzed. Fingers showing signs of DIP joint arthritis were excluded. The fingers were scanned using microtomography (microCT). Measurements of the bony morphology were made using models created from the scans.

RESULTS

In each finger, there is no statistically significant difference between the radii of curvature of the ulnar and radial condyles of the middle phalanx head. Conversely, the radius of curvature of the distal phalanx ulnar groove is significantly greater than that of the radial groove. The radii of curvature of the groove of the distal phalanx and the condyles of the middle phalanx displayed nonconformity with disparity increasing from the index to small fingers. Remarkably, the radius of curvature of the distal phalanx central ridge and the mean radius of the middle phalanx condyles are essentially the same.

CONCLUSION

The purpose of this study is to gain better insight into the DIP joints of the hand. The asymmetry between the distal phalanx grooves and the middle phalanx condyles suggests that there may be a translational component to DIP joint motion. Our understanding of morphology may lend insight into the biomechanics and disease progression within the DIP joints.