Susumu Saito

Biomechanics of the Volar Plate of the Proximal Interphalangeal Joint: A Dynamic Ultrasonographic Study

PURPOSE To study the biomechanics of the volar plate of the proximal interphalangeal (PIP) joint using ultrasonography. METHODS The subjects were 20 normal and 5 pathological digits. We included as normal subjects 20 digits (10 index and 10 middle fingers) of 10 hands of 10 volunteers who had no history of trauma or any other hand-related pathological conditions. To clarify the biomechanical effect of the A3 pulley for the volar plate motion, we included a total of 5 digits (1 index, 2 middle, and 2 ring) of 4 hands of 4 consecutive patients who had flexor tendon repair surgeries in zone II with the A3 pulley left open as pathological subjects. Transducers were applied volarly to the PIP joint and the ultrasonographic plane was kept in the central axis of the digits to display the volar plate and the flexor tendons in the same image. We recorded cine videos during active joint motion. We also obtained sequential static images for morphological analysis. RESULTS The motion of the volar plate of the normal PIP joint was as follows: when joint flexion started, the volar plate slid proximally to lie parallel to the condylar slope of the proximal phalanx. In 30° of flexion, the flexor tendons tightened and the distal portion of the volar plate moved volarward. In 45° or more of flexion, the distal portion protruded over the lip of the middle phalanx. The lip rolled dorsalward in the recess in return. In the flexor tendon repair cases, the distal portion of the volar plate did not move volarward at all, even when the joint flexed 45° or more. The main body of the volar plate showed a marked wavelike or sigmoid deformity. CONCLUSIONS To characterize the biomechanics of the volar plate of the PIP joint, we propose the following 3 sequential phases: sliding, elevating, and rolling in the recess. The A3 pulley may serve as an elevator of the volar plate, triggering the next phase of rolling in the recess. The recess can provide some articulation which the lip of the middle phalanx can roll in.

Biomechanical Differences of the Proximal Interphalangeal Joint Volar Plate During Active and Passive Motion: A Dynamic Ultrasonographic Study

PURPOSE To define the biomechanical differences of the volar plate (VP) of the proximal interphalangeal joint during active and passive motion, which may provide clues to understanding the functional importance of the volar elevation of the VP. METHODS We imaged the volar aspect of the proximal interphalangeal joint in 10 healthy middle fingers using ultrasonography. Cine videos recorded the movements of the VP during joint motion from full extension to more than 60° of flexion both actively and passively. We plotted 5 points on the volar surface of the VP and traced them for motion analysis. We statistically analyzed the volar distances and volar angulation of the VP in full extension, 30°, 45°, and 60° of flexion to determine the differences between active and passive flexion. RESULTS In active flexion, the VP showed significantly higher volar distances in 45° and 60° and changed its configuration from the original flattened figure to an inverted U shape, with a significant higher angulation at 45° compared with passive flexion. Conversely, in passive flexion, we did not observe the volar elevation of the VP and the flattened configuration was maintained throughout the motion arc. CONCLUSIONS From an anatomical viewpoint, volar elevation of the VP seen in active flexion could provide dynamic stresses on the adjacent ligaments and contribute to the stability and smooth gliding of the joint.

Distraction arthrolysis using an external fixator and flexor tenolysis for proximal interphalangeal joint extension contracture after severe crush injury.

PURPOSE To introduce a technique for distraction arthrolysis with an external fixator followed by flexor tendon tenolysis for extension contracture of the proximal interphalangeal (PIP) joint after severe crush injury. We also assessed the results of this method in all patients treated. METHODS Five fingers of 4 men with extension contracture of the PIP joint after severe injury underwent distraction arthrolysis using an external fixator, followed by flexor tenolysis. On the day of attaching the external fixator, moderate distraction was applied to the joint and the gap was widened to approximately 2 mm. From the following day onward, the PIP joint was gradually widened for 10 days until a gap of about 5 mm was attained. After sustaining this amount of distraction for 3 or 4 days, the fixator was removed. Passive range of motion was performed for about one week until swelling of the affected digit subsided. Then, flexor tenolysis was performed. Patients were follow-up for an average of 31 months after surgery. RESULTS After tenolysis, the average improvement of active range of motion was 20 degrees, average gain of active flexion was 41 degrees, and average loss of active extension was 21 degrees. The average range of active motion was from 6 degrees to 38 degrees preoperatively, and from 27 degrees to 79 degrees postoperatively. The average median of active motion was 22 degrees preoperatively, and 52 degrees postoperatively. In all fingers, there was no significant difference in the total arc of active motion preoperatively and postoperatively, but there was a significant difference between preoperative and postoperative maximum active flexion. In all patients, painless motion was maintained and arthritic changes of the PIP joint did not worsen during the follow-up period. CONCLUSIONS Distraction arthrolysis with an external fixator followed by flexor tenolysis was a useful treatment for our patients with extension contracture of the PIP joint and tendon adhesions after severe crush injury. TYPE OF STUDY/LEVEL OF EVIDENCE Therapeutic IV.

A comparative study of the modified Sauvé–Kapandji procedure for rheumatoid wrist with and without stabilization of the proximal ulnar stump

We compared the clinical and radiological results of the modified Sauvé–Kapandji procedure for 41 of 86 operated rheumatoid wrists with (n = 22) and without (n = 19) stabilization of the proximal ulnar stump with a slip of half the extensor carpi ulnaris tendon. Gender, age, and follow-up period were similar in the two groups. We found no difference clinically or on radiographs between the two groups other than better early postoperative pain relief in those stabilized. Stabilization of the proximal ulnar stump may not be necessary in the modified Sauvé–Kapandji procedure for rheumatoid wrists.

Schwannomatosis affecting all three major nerves in the same upper extremity.

multiply injured patients (Manidakis et al., 2009). The role of the injectable bone substitute in initiating HO is uncertain. Contributory factors may have been the osteoblastic stimulation of the drilled bone fragments and any residual bone fragments at the tip of the prominent screw, combined with the unintentionally prolonged postoperative immobilization. A common argument for using locking fixation of distal radial fractures is that early mobilization may produce better wrist motion and function. However, immobilization for up to 6 weeks after palmar plate fixation of distal radial fractures has not been shown to reduce the range of flexion–extension in the wrist at 6 months follow-up (Lozano-Calderon et al., 2008). Options for treatment of HO include the use of indomethacin, radiotherapy and excision of mature heterotopic bone. We consider that good operative technique, including accurate screw placement without penetrating the dorsal cortex, removal of free bone fragments and prevention of postoperative haematoma, may be important in preventing this complication.

Thenar Dysplasia in Radial Polydactyly Depends on the Level of Bifurcation

Background: Little is known about thenar dysplasia in radial polydactyly, other than that thenar hypoplasia occasionally occurs in radial polydactyly with triphalangism. In particular, the phenotype and level of duplication associated with thenar dysplasia remain unclear. Methods: The abductor pollicis brevis and flexor pollicis brevis muscles were visualized using three-dimensional ultrasound, and their horizontal geometry was assessed using a biaxial level classification system. Subjects were categorized into three phenotypes according to the developmental condition of the radial thumb. The relationship between the level of distribution of the muscles and the level of the bifurcation of the radial thumb was investigated. Results: Nineteen patients with radial polydactyly without triphalangism were included. There were 10 patients with the nonfloating type, three with the floating type, and six with the rudimentary type. All patients with bifurcation at or more distal to the metacarpophalangeal joint had normal thenar muscle distribution, but the muscles in patients with bifurcation at or more proximal to the level of the metacarpals were confined, regardless of phenotype. The level of muscle distribution was strongly correlated with the level of the bifurcation of the radial thumb. Conclusions: These findings suggest that formation of the thenar muscles in the longitudinal direction in radial polydactyly might depend on the level of bifurcation of the radial thumb. The presence of thenar dysplasia even in floating-type or rudimentary-type duplications is of clinical and etiologic importance.

Digital artery deformation on movement of the proximal interphalangeal joint

This study aimed to characterize in vivo human digital arteries in three-dimensions using photoacoustic tomography in order to understand the specific mechanism underlying arterial deformation associated with movement of the proximal interphalangeal joint. Three-dimensional morphological data were obtained on the radialis indicis artery (radial artery of the index finger) at different angles of the joint. The association between increased curvature of the deformation and the anatomical region was assessed. Characteristic morphological deformations in areas of major deformation were determined. The deformation of the artery was characterized by three consecutive curves in juxta-articular regions, which were particularly noticeable when the joint was flexed at an angle of ≥ 60°. The change in the curvature of the deformation during 30°–90° of flexion was lower in middle-aged individuals than in young individuals. Better understanding of the mechanism underlying deformation of the digital arteries may contribute to advancements in flap procedures and rehabilitation strategies after digital artery repair.

Nontubulation Repair of Peripheral Nerve Gap Using Heparin/Alginate Gel Combined with b-FGF

Summary: All artificial nerve grafts have a tubular structure, and they guide axonal regrowth through the tube from the proximal side toward the peripheral side. Based on the results of our experimental study using animals, we used alginate gel without a tubular structure as an artificial nerve graft for digital nerve repair and evaluated peripheral nerve regeneration. In 2 patients, a gap due to digital nerve injury was bridged with controlled-release heparin/alginate gel combined with basic fibroblast growth factor, and restoration of the sensory function was serially evaluated. In both patients, Tinel’s sign appeared 3–4 weeks after the operation, and sensory recovery to the fingertip was achieved at 6 months postoperatively. Our results suggest that even gel without a tubular structure provides a site for peripheral nerve regeneration.

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

Abstract 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.

Non-operative Treatment for Extensive Skin Necrosis of a Neonatal Dorsal Foot caused by Extravasation

We herein describe two cases of non-surgical treatment for skin necrosis of the dorsum of the neonatal foot caused by extravasation. In both the cases, closure of the defects was achieved after 3 months of conservative treatment without any complications. Although the defects occupied almost all of the dorsal skin of the foot, no significant contracture disabling the toe or ankle occurred during the maximum follow-up period of 9 years. Non-surgical treatments could be an alternative treatment for neonatal skin necrosis caused by extravasation.