Further experience in rehabilitation of zone II flexor tendon repair with dynamic traction splinting

A review of all flexor tendon repairs in the "no man's land" performed from January of 1985 to June of 1987 was done to evaluate the efficacy of our method of rehabilitation. There were 60 fingers (57 patients) with complete laceration of the flexor digitorum profundus and flexor digitorum superficialis tendons in zone II. Fingers with phalangeal fractures, joint injuries, or significant skin loss were excluded. Follow-up ranged from 12 to 48 months. Rehabilitation consisted of a 12-week protocol using the U.S. military combined regimen of controlled motion. Features from the technique of controlled active extension against rubber band passive flexion as well as those of controlled passive extension and passive flexion were incorporated. The palmar pulley modification of Kleinert's dynamic traction splint was utilized. Strickland's total active motion formula was employed to determine results. The results were classified into the four categories of excellent, good, fair, and poor. Fifty-two fingers (86 percent) were rated excellent, 4 fingers (7 percent) were rated good, 1 finger (2 percent) was rated fair, and 3 fingers (5 percent) were rated poor.     

Anatomical variations of the extensor tendons to the fingers over the dorsum of the hand: a study of 50 hands and a review of the literature

The extensor tendons to the fingers were studied in dissections of 50 fresh cadaveric hands, and the divisions of the tendons, as well as the communications (juncturae), were analyzed. The pattern of distribution most frequently observed was as follows. The extensor digitorum communis provided one tendon to the index finger, one to the middle finger, two to the ring finger, and none to the little finger. The extensor indicis exhibited one tendon, whereas the extensor digiti minimi exhibited two tendons. The extensor indicis tendon was always observed to lack a junctura tendinum. The extensor indicis was absent in both hands of one cadaver. A tendon slip from the extensor digiti minimi to the ring finger was observed in one hand. All surgeons must bear in mind the existence of these variations when performing common tendon transfers.     

Wrist and digital joint motion produce unique flexor tendon force and excursion in the canine forelimb

The force and excursion within the canine digital flexor tendons were measured during passive joint manipulations that simulate those used during rehabilitation after flexor tendon repair and during active muscle contraction, simulating the active rehabilitation protocol. Tendon force was measured using a small buckle placed upon the tendon while excursion was measured using a suture marker and video analysis method. Passive finger motion imposed with the wrist flexed resulted in dramatically lower tendon force (approximately 5 N) compared to passive motion imposed with the wrist extended (approximately 17 N). Lower excursions were seen at the level of the proximal interphalangeal joint with the wrist flexed (approximately 1.5 mm) while high excursion was observed when the wrist was extended or when synergistic finger and wrist motion were imposed (approximately 3.5 mm). Bivariate discriminant analysis of both force and excursion data revealed a natural clustering of the data into three general mechanical paradigms. With the wrist extended and with either one finger or four fingers manipulated, tendons experienced high loads of approximately 1500 g and high excursions of approximately 3.5 mm. In contrast, the same manipulations performed with the wrist flexed resulted in low tendon forces (4-8 N) and low tendon excursions of approximately 1.5 mm. Synergistic wrist and finger manipulation provided the third paradigm where tendon force was relatively low (approximately 4 N) but excursion was as high as those seen in the groups which were manipulated with the wrist extended. Active muscle contraction produced a modest tendon excursion (approximately 1 mm) and high or low tendon force with the wrist extended or flexed, respectively. These data provide the basis for experimentally testable hypotheses with regard to the factors that most significantly affect functional recovery after digital flexor tendon injury and define the normal mechanical operating characteristics of these tendons.     

Motor control theories improve biomechanical model of the hand for finger pressing tasks

BackgroundBiomechanical models are a useful tool to estimate tendon tensions. Unfortunately, in previous fingers' models, each finger acts independently from the others. This is contradictory with hand motor control theories which show that fingers are functionally linked in order to balance the wrist/forearm joint with minimal tendon tensions. (i.e. principle of minimization of the secondary moments). We propose to adapt a hand biomechanical model according to this principle by including the wrist joint. We will determine whether the finger tendon tensions changed with the wrist joint added to the model.MethodsTwo models have been tested: one considering fingers independently (model A) and one with the fingers mechanically linked by the inclusion of the wrist balance (model B). A single set of data, additional results from the literature and in-vivo values have been used to compare the results.ResultsModel A corroborates previous results in the literature. Contrast results were obtained with model B, especially for the Ring and Little fingers. Different tendon tensions were obtained, particularly, in finger extensor muscles critical to balance the wrist.DiscussionWe discuss the biomechanical results in accordance with the hand/finger motor control theories. It appears that the wrist joint balance is critical for finger tendon tension estimation. When including the wrist joint into finger models, the tendon tension estimations agree well with the minimization of secondary moments and the force deficit.     

Tendon disorders of the hand

LEARNING OBJECTIVES: After reading this article, the participant should be able to: 1. Make decisions on flexor tendon repair based on current evidence. 2. Perform some important tendon transfers after viewing Dr. Kozin's videos. 3. Inject local anesthesia for wide-awake flexor tendon repair after viewing the appropriate videos in the article. 4. Use relative motion extension splints for the postoperative management of extensor tendon injuries. SUMMARY: This article provides a practical, clinically useful overview of some of the current best techniques and evidence available to the plastic surgeon in the treatment of flexor and extensor tendon injuries, tendon transfers, trigger fingers, mallet fingers, boutonniere deformities, and De Quervain tenosynovitis. Twelve short movies and drawings emphasize important points of diagnosis and treatment of tendon disorders.     

Tendon displacements during voluntary and involuntary finger movements

In the human hand, independent movement control of individual fingers is limited. One potential cause for this is mechanical connections between the tendons and muscle bellies corresponding to the different fingers. The aim of this study was to determine the tendon displacement of the flexor digitorum superficialis (FDS) of both the instructed and the neighboring, non-instructed fingers during single finger flexion movements. In nine healthy subjects (age 22–29 years), instructed and non-instructed FDS finger tendon displacement of the index, middle and ring finger was measured using 2D ultrasound analyzed with speckle tracking software in two conditions: active flexion of all finger joints with all fingers free to move and active flexion while the non-instructed fingers were restricted. Our results of the free movement protocol showed an average tendon displacement of 27 mm for index finger flexion, 21 mm for middle finger flexion and 17 mm for ring finger flexion. Displacements of the non-instructed finger tendons (≈12 mm) were higher than expected based of the amount of non-instructed finger movement. In the restricted protocol, we found that, despite minimal joint movements, substantial non-instructed finger tendon displacement (≈9 mm) was still observed, which was interpreted as a result of tendon strain. When this strain component was subtracted from the tendon displacement of the non-instructed fingers during the free movement condition, the relationship between finger movement and tendon displacement of the instructed and non-instructed finger became comparable. Thus, when studying non-instructed finger tendon displacement it is important to take tendon strain into consideration.     

The extensor assembly in two species of opossum,Philander opossum and Didelphis marsupialis

In considering primate and hominoid phylogeny, the fundamental position assigned to opossums is explained partially by the characteristic morphology of their hands and feet. One of the main functional features of the human hand is the ability to make a stabilized arch of the finger. Because the extensor assembly plays a key role in establishing an arched finger, the extensor systems of the digits of both the hands and feet were studied in two species of opossum, Philander opossum and Didelphis marsupialis. In the foot, two extensor tendons join in each toe to form one tendinous plate, which inserts onto the base of the second phalanx. Lumbricals join this plate along the tibial side, and interosseus insertions are found, although a true interosseus wing is lacking. At the proximal interphalangeal level, a terminal tendon takes its origin from this tendinous plate. This terminal tendon is oval in cross-section and contains elastic structures. Oblique bands arise from this terminal tendon and run proximally along the proximal interphalangeal joint inserting onto the base of the first phalanx. There are elastic structures in the flexor tendon on the dorsal side near its site of insertion. In the hand, the main extensor tendons are arranged differently and the interossei contribute substantially to the extensor assembly. Otherwise, the extensor assembly of the hands and feet are quite similar. The function of the so-called paratendinous intravaginal flexors is discussed as are evolutionary aspects of the extensor assembly.     

A combined regimen of controlled motion following flexor tendon repair in "no man's land"

A program of controlled motion following repair of flexor tendons in the hand is presented. This regimen incorporates the features of active extension against rubber band passive flexion, as well as those of controlled passive extension and passive flexion. In this prospective study, 44 digits with complete lacerations of the flexor digitorum profundus and flexor digitorum superficialis in zone 2 were treated. Using the Strickland formula of total active motion of the interphalangeal joints, 36 fingers (82 percent) were rated "excellent"; 7 fingers (16 percent) were rated "good"; 1 finger (2 percent) was rated "fair"; none was rated "poor". There was no statistical difference between the results of delayed primary repair and immediate primary repair.     

A light weight compliant hand mechanism with high degrees of freedom

This paper presents the design and prototyping of an inherently compliant lightweight hand mechanism. The hand mechanism itself has 15 degrees of freedom and five fingers. Although the degrees of freedom in each finger are coupled, reducing the number of independent degrees of freedom to 5, the 15 degrees of freedom of the hand could potentially be individually actuated. Each joint consists of a novel flexing mechanism that is based on the loading of a compression spring in the axial and transverse direction via a cable and conduit system. Currently, a bench top version of the prototype is being developed; the three joints of each finger are coupled together to simplify the control system. The current control scheme under investigation simulates a control scheme where myoelectric signals in the wrist flexor and extensor muscles are converted in to x and y coordinates on a control scheme chart. Static load-deformation analysis of finger segments is studied based on a 3-dimensional model without taking the stiffener into account, and the experiment validates the simulation.     

A Comparative Study of Four Types of Free Flaps from the Ipsilateral Extremity for Finger Reconstruction

Aim

To compare the outcomes of finger reconstruction using arterialized venous flap (AVF), superficial palmar branch of the radial artery (SPBRA) flap, posterior interosseous perforator flap (PIPF), and ulnar artery perforator free (UAPF) flap harvested from the ipsilateral extremity.

Methods

We retrospectively reviewed the outcomes for 41 free flaps from the ipsilateral extremity in the reconstruction of finger defects in 41 patients with small/moderate skin defects, including 11 AVFs, 10 SPBRA flaps, 10 PIPFs, and 10 UAPF flaps. Standardized assessment of outcomes was performed, including duration of operation, objective sensory recovery, cold intolerance, time of returning to work, active total range of motion (ROM) of the injured fingers, and the cosmetic appearance of the donor/recipient sites.

Results

All flaps survived completely, and the follow-up duration was 13.5 months. The mean duration of the complete surgical procedure for AVFs was distinctly shorter than that of the other flaps (p<0.05). AVFs were employed to reconstruct skin defects and extensor tendon defects using a vascularized palmaris longus graft in 4 fingers. Digital blood supply was reestablished in 4 fingers by flow-through technique when using AVFs. Optimal sensory recovery was better with AVFs and SPBRA flaps as compared with UAPF flaps and PIPFs (p<0.05). No significant differences were noted in ROM or cold intolerance between the 4 groups. Optimal cosmetic satisfaction was noted for the recipient sites of AVFs and the donor sites of SPBRA flaps. The number of second-stage defatting operations required for AVFs was considerably lesser than that for the other flaps.

Conclusion

All 4 types of free flaps from the ipsilateral extremity are a practical choice in finger reconstruction for small/moderate-sized skin defects. AVFs play an important role in such operations due to the wider indications, and better sensory recovery and cosmetic appearance associated with this method.     

A kinematic model of the flexor tendons of the hand

The multi-joint model is a kinematic simulation of the long flexor tendons of the fingers. The tendons modeled are the flexor pollicis longus, the flexor digitorum profundus, and the flexor digitorum superficialis. The simulated tendons are displayed on an Evans and Sutherland PS330 color graphics terminal attached to a display of articulated bones of the hand. As a user changes the position of the joints of the simulated hand, the simulation displays the new tendon path and the excursion of the tendon for the new position of the hand. The multi-joint model is one component of a comprehensive model for use in a hand biomechanics computer workstation.     

In vivo forces generated by finger flexor muscles do not depend on the rate of fingertip loading during an isometric task

Risk factors for activity-related tendon disorders of the hand include applied force, duration, and rate of loading. Understanding the relationship between external loading conditions and internal tendon forces can elucidate their role in injury and rehabilitation. The goal of this investigation is to determine whether the rate of force applied at the fingertip affects in vivo forces in the flexor digitorum profundus (FDP) tendon and the flexor digitorum superficialis (FDS) tendon during an isometric task. Tendon forces, recorded with buckle force transducers, and fingertip forces were simultaneously measured during open carpal tunnel surgery as subjects (N=15) increased their fingertip force from 0 to 15N in 1, 3, and 10s. The rates of 1.5, 5, and 15N/s did not significantly affect FDP or FDS tendon to fingertip force ratios. For the same applied fingertip force, the FDP tendon generated more force than the FDS. The mean FDP to fingertip ratio was 2.4+/-0.7 while the FDS to tip ratio averaged 1.5+/-1.0 (p<0.01). The fine motor control needed to generate isometric force ramps at these specific loading rates probably required similar high activation levels of multiple finger muscles in order to stabilize the finger and control joint torques at the force rates studied. Therefore, for this task, no additional increase in muscle force was observed at higher rates. These findings suggest that for high precision, isometric pinch maneuvers under static finger conditions, tendon forces are independent of loading rate.     

The effect of finger extensor mechanism on the flexor force during isometric tasks.

The role of the intrinsic finger flexor muscles was investigated during finger flexion tasks. A suspension system was used to measure isometric finger forces when the point of force application varied along fingers in a distal-proximal direction. Two biomechanical models, with consideration of extensor mechanism Extensor Mechanism Model (EMM) and without consideration of extensor mechanism Flexor Model (FM), were used to calculate forces of extrinsic and intrinsic finger flexors. When the point of force application was at the distal phalanx, the extrinsic flexor muscles flexor digitorum profundus, FDP, and flexor digitorum superficialis, FDS, accounted for over 80% of the summed force of all flexors, and therefore were the major contributors to the joint flexion at the distal interphalangeal (DIP), proximal interphalangeal (PIP), and metacarpophalangeal (MCP) joints. When the point of force application was at the DIP joint, the FDS accounted for more than 70% of the total force of all flexors, and was the major contributor to the PIP and MCP joint flexion. When the force of application was at the PIP joint, the intrinsic muscle group was the major contributor for MCP flexion, accounting for more than 70% of the combined force of all flexors. The results suggest that the effects of the extensor mechanism on the flexors are relatively small when the location of force application is distal to the PIP joint. When the external force is applied proximally to the PIP joint, the extensor mechanism has large influence on force production of all flexors. The current study provides an experimental protocol and biomechanical models that allow estimation of the effects of extensor mechanism on both the extrinsic and intrinsic flexors in various loading conditions, as well as differentiating the contribution of the intrinsic and extrinsic finger flexors during isometric flexion.     

Studies on the tendinous compartments of the extensor muscles on the back of the human hand and their tendon sheaths. I

In 47 dissected right and left hands of adults of both sexes, kept in a moist condition, significant practical-clinical investigations of the transitional zone between forearm and hand were undertaken. In particular it was sought to determine the characteristic sizes of the extensor retinaculum, the osteofibrous tunnels, the insertion tendons of the hand and finger extensor muscles, and their tendon sheaths. Together with the palmar carpal ligament, the 2 to 3 cm wide extensor retinaculum annularly surrounds the whole circumference of the carpus. It extends obliquely from radial-proximal to ulnar-distal and conducts the extensor tendons over the carpal articulations. According to recent studies, it is divided into a superficial and a deep fibrous layer. From the undermost surface, vertical and oblique septa run to the plane of the forearm and carpal bones. They separate the fibrous portion of the 6 tendinous compartments of the dorsum manus. In 8.5% of cases, an accessory and completely independent tunnel of the extensor pollicis brevis muscle exists in the material investigated, and in 2.2% of cases, there is an additional tunnel for the extensor carpi radialis muscle. Hence, one occasionally finds 8 separate osteofibrous gliding compartments for the extensor muscles in the dorsal hand region. The longest tunnel belongs, as a rule, to the extensor digiti minimi muscle, whilst the widest pertains to the extensor digitorum muscle. Within the tunnel and also proximal and distal to it, the extensor tendons are surrounded by synovial sheaths. Because of its wide encroachment on the dorsum of the hand, the insertion tendon of the extensor digiti minimi muscle possesses the longest tendon sheath, measuring 68.8 mm. The next longest sheath, that of the extensor pollicis longus muscle, which measures 56.2 mm, begins further proximal to the gap of the radiocarpal articulation. In 12.8% of cases, there are divided sheaths of the abductor pollicis longus and of the extensor pollicis brevis muscle. The tendon sheath of both extensor carpi radiales muscles is frequently divided into 2 compartments which, in 2/3 of cases, communicate. The compartment of the extensor carpi radialis brevis muscle, in 91.5% of cases, shares a window-like opening with the roof of the synovial vagina of the extensor pollicis longus muscle. The tendon sheath of the long extensor muscles of the fingers originates 5 mm proximal to the forearm border of the extensor retinaculum and has a communal recess. The IVth tendon sheath opens distally and splays out in a glove-like manner to some distal recesses.(ABSTRACT TRUNCATED AT 400 WORDS)     

低强度脉冲超声波对肌腱愈合的促进作用

目的:分析低强度脉冲超声波(low intensity pulsed ultrasound,LIPU)对Ⅱ区屈指肌腱愈合的促进作用,并探讨其减少肌腱粘连的临床效果。方法:选取2010年8月至2013年4月在我院接受II区屈指肌腱损伤修复术治疗的患者80例并随机分为两组。LIPU组(33例,共39指),该组患者均接受系统的低强度脉冲超声波进行治疗;对照组(34例,共41指),所有患者在治疗时放置超声探头,但不接通电源。在术后12周,采用视觉模拟评分法(visual analogue scale,VAS)评估患手疼痛程度;采用肌腱总主动活动度(total active motion,TAM)评定标准评价肌腱的功能状况;采用Lovett分级法评价患指屈指肌力。结果:两组术后无肌腱再断裂病例出现。术后12周时,LIPU组与对照组的VAS疼痛评分分别为(1.9±1.8)和(2.3±1.9)(t=0.996,P=0.337)。根据TAM系统评定标准,LIPU组与对照组的优良率分别为94.9%和70.7%,组间差异有统计学意义(X2=12.798,P=0.000),LIPU组显著高于对照组,两组患指屈指肌力恢复正常的发生率分别为100%和95.1%,组间差异无统计学意义(X2=1.951,P=0.162)。结论:LIPU具有促进II区屈指肌腱愈合,改善患指主动活动功能的效果,且不增加肌腱断裂的风险,但其促进肌腱愈合的机制尚需进一步实验研究证实。     

Estimation of the effective static moment arms of the tendons in the index finger extensor mechanism

A novel technique to estimate the contribution of finger extensor tendons to joint moment generation was proposed. Effective static moment arms (ESMAs), which represent the net effects of the tendon force on joint moments in static finger postures, were estimated for the 4 degrees of freedom (DOFs) in the index finger. Specifically, the ESMAs for the five tendons contributing to the finger extensor apparatus were estimated by directly correlating the applied tendon force to the measured resultant joint moments in cadaveric hand specimens. Repeated measures analysis of variance revealed that the finger posture, specifically interphalangeal joint angles, had significant effects on the measured ESMA values in 7 out of 20 conditions (four DOFs for each of the five muscles). Extensor digitorum communis and extensor indicis proprius tendons were found to have greater MCP ESMA values when IP joints are flexed, whereas abduction ESMAs of all muscles except extensor digitorum profundus were mainly affected by MCP flexion. The ESMAs were generally smaller than the moment arms estimated in previous studies that employed kinematic measurement techniques. Tendon force distribution within the extensor hood and dissipation into adjacent structures are believed to contribute to the joint moment reductions, which result in smaller ESMA values.     

Radial half of extensor carpi radialis longus tendon as graft to elongate muscle tendon unit for correction of finger clawing

In 12 patients, the extensor carpi radialis longus muscle tendon unit was elongated using the radial half of the parent tendon so that it could reach the site of new insertion, the A1-A2 pulley of flexor sheath or lateral bands, after routing the transfer through the carpal tunnel. The tendon was of appropriate thickness and could be split into two halves to be used as a graft. Further splitting of the tendon into four tails was possible. The transferred slips retained adequate strength to activate the fingers after the operation. It is suggested that splitting of the extensor carpi radialis longus tendon to use one half as a tendon graft be considered in patients in whom extensor carpi radialis longus transfer is planned to correct finger clawing. This technique is simple, needs minor modification in the sequence of operative steps, reduces operating time, and saves the patient from postoperative discomfort, muscle herniation, and scarring at the donor site (usually the thigh).     

Variation of finger forces in maximal isometric grasp tests on a range of cylinder diameters

An investigation of maximal isometric cylindrical grasping actions of the hand is reported. A dynamometer is described which allows simultaneous measurement of both the normal forces and the tangential shear forces imposed by each of the three phalangeal segments of a finger during a test. Seventeen subjects were tested, grasping cylinders 31–116 mm in diameter. Normal grasp forces decreased significantly as cylinder size increased, while with large diameters, shear forces moved the skin towards the finger tip. In all cases the distal segments of the fingers imposed forces significantly larger than those of the middle and proximal segments. The mean contributions of fingers from index to little were: 30, 30, 22 and 18%, proportions that did not vary significantly for the range of grasp diameters. Forces acting during grasping activities are reported in greater detail, for a wider range of hand gripping postures, than previously available. These data are useful in the design of hand operated controls or in the prediction of tendon and joint forces in vivo for the design of implants.     

The influence of concentric and eccentric loading on the finger pulley system

In this study we investigated the influence of the loading condition (concentric vs. eccentric loading) on the pulley system of the finger. For this purpose 39 cadaver finger (14 hands, 10 donors) were fixed into an isokinetic loading device. The forces in the flexor tendons and at the fingertip were recorded. In the concentric loading condition A2 and A4 ruptures as well as alternative events such as fracture of a phalanx or avulsion of the flexor tendons were almost equally distributed, whereas the A2 pulley rupture was the most common event (59%) in the eccentric loading condition and alternative events were rare (23.5%). The forces in the deep flexor tendon, the fingertip and in the pulleys were significantly lower in the eccentric loading condition. As the ruptures occurred at lower loads in the eccentric than in the concentric loading condition it can be concluded that friction may be an advantage for climbers, supporting the holding force of their flexor muscles but may also increase the susceptibility to injury.     

Kinematic evaluation of the finger’s interphalangeal joints coupling mechanism—variability,flexion–extension differences,triggers, locking swanneck deformities,anthropometric correlations

The human finger contains tendon/ligament mechanisms essential for proper control. One mechanism couples the movements of the interphalangeal joints when the (unloaded) finger is flexed with active deep flexor. This study’s aim was to accurately determine in a large finger sample the kinematics and variability of the coupled interphalangeal joint motions, for potential clinical and finger model validation applications. The data could also be applied to humanoid robotic hands. Sixty-eight fingers were measured in seventeen hands in nine subjects. Fingers exhibited great joint mobility variability, with passive proximal interphalangeal hyperextension ranging from zero to almost fifty degrees. Increased measurement accuracy was obtained by using marker frames to amplify finger segment motions. Gravitational forces on the marker frames were not found to invalidate measurements. The recorded interphalangeal joint trajectories were highly consistent, demonstrating the underlying coupling mechanism. The increased accuracy and large sample size allowed for evaluation of detailed trajectory variability, systematic differences between flexion and extension trajectories, and three trigger types, distinct from flexor tendon triggers, involving initial flexion deficits in either proximal or distal interphalangeal joint. The experimental methods, data and analysis should advance insight into normal and pathological finger biomechanics (e.g., swanneck deformities), and could help improve clinical differential diagnostics of trigger finger causes. The marker frame measuring method may be useful to quantify interphalangeal joints trajectories in surgical/rehabilitative outcome studies. The data as a whole provide the most comprehensive collection of interphalangeal joint trajectories for clinical reference and model validation known to us to date.