Feasibility of partial A2 and A4 pulley excision: residual pulley strength

We investigated residual digital flexor pulley strengths after 75% excision of the A2 and A4 pulleys. For direct pull-off tests, A2 and A4 pulleys from cadaveric fingers were tested by pulling on a loop of flexor digitorum profundus tendon through the pulley. For functional loading tests, fingers were positioned with the metacarpophalangeal joint flexed to 90 degrees for A2 testing, and with the proximal interphalangeal joint in 90 degrees flexion for A4 testing (with all other joints in full extension). Excision of 75% of A2 and A4 pulleys reduced pulley strengths determined by both testing methods. For the functional loading tests, which are more clinically relevant, mean tendon forces at failure after partial excision of A2 and A4 pulleys were 224 and 131 N respectively, which is sufficient to withstand flexor tendon forces expected during activities of daily living.     

Development of a synthetic replacement for flexor tendon pulleys using expanded polytetrafluoroethylene membrane.

Reconstruction or replacement of the damaged pulley is a difficult surgical problem because of the need to find suitable biological material, the bulkiness of the repair, and adhesion formation between the pulley and flexor tendons. Therefore, a method was developed to reconstruct the fibro-osseous pulleys with polytetrafluoroethylene (PTFE) membrane. Twenty White Leghorn chickens had the A3 pulley of the long digit excised; this was followed by a standard injury to the flexor profundus tendon. The A3 pulley was then reconstructed with PTFE membrane. In the opposite foot, the A3 pulley was transected laterally, the tendon injured in the same manner, and the native pulley sutured. Seven control chickens had a PTFE pulley reconstruction without tendon injury in one foot and the opposite foot did not undergo surgery. At postoperative days 0, 21, and 35, the animals were killed to evaluate the effectiveness of the PTFE pulleys. Flexor tendon function was assessed by determining the active range of motion of the digit. There was no significant difference between the PTFE pulleys and suture repair of the native pulleys at postoperative days 21 and 35. This indicates that the PTFE pulleys were capable of preventing tendon bow-stringing and did not significantly impair tendon gliding. The breaking strength of the PTFE pulley was less than that of the normal A3 pulleys, but it was sufficient to allow immediate mobilization of the digits postoperatively without fear of pulley rupture. The synthetic PTFE pulley appears to have the potential to function as an effective immediate replacement for the fibro-osseous pulleys.     

Isolated flexor digitorum profundus tendon injuries in zones IIA and IIB repaired with figure of eight sutures

The 'figure of eight' suture technique for flexor tendon repair is known to be simple and strong but it has the major disadvantage of being bulky, with the knots outside the repair site. When the superficialis tendon is intact it may cause impingement and/or increase the work of flexion with postoperative mobilization and it is not known whether this bulky repair is suitable for isolated profundus injuries in zone II. A series of 36 patients (36 fingers) with clean-cut isolated flexor digitorum profundus tendon injuries in zones IIA/IIB were reviewed retrospectively. Repairs were done with three 'figure of eight' sutures and the pulleys proximal to the tendon laceration level were vented. Postoperatively, early active exercises were carried out. There were no ruptures. At a mean final follow-up of 6 months, the outcome (in range of motion) was excellent in 27 fingers and good in the remaining nine fingers by the Strickland criteria. It was concluded that the bulky 'figure of eight' technique can be used in isolated profundus tendon injuries in zones IIA/IIB.     

Mapping of vascular endothelium in the human flexor digitorum profundus tendon

PURPOSE: Previous techniques to delineate the human flexor digitorum profundus (FDP) vasculature have been innovative but potentially imprecise, resulting in uncertainty as to the existence of avascular zones in the flexor tendon. We aimed to use a novel immunohistochemical technique to determine more accurately the vasculature of the human flexor tendon. METHODS: Thirty fresh cadaveric human FDP tendons were harvested, fixed, wax embedded, sectioned, and stained using the anti-CD31 monoclonal antibody to allow vessel visualization. Vessel numbers and vascularity density ratios were determined by computed image analysis. RESULTS: Vessel density ratios varied with anatomic location, with a decrease between the A2 and A4 pulleys. There also was variation in vascularity ratios in the anteroposterior plane, with the palmar surface of the tendons having a lower vessel density. CONCLUSIONS: We have shown that although areas of low vascularity exist on the palmar aspect of the tendon, there are no truly avascular zones.     

Flexor Tendon Injuries: II. Operative Technique

The repair of flexor tendons (zones I and II) is a technique-intensive surgical undertaking. It requires a strong understanding of the anatomy of the tendon sheath and the normal relationship between the pulleys and the flexor digitorum superficialis and flexor digitorum profundus tendons in the digit. Meticulous exposure, careful tendon retrieval, and atraumatic repair are extremely important, and the repair should be of sufficient strength to resist gapping and permit the early postrepair application of motion forces. Whenever possible, the tendon sheath should be preserved or repaired, and a smooth gliding surface should be reestablished. The author describes an effective method of tendon retrieval and a simplified technique for a four-strand tendon repair with a supplementary peripheral running-lock suture. The repair is considered to maintain sufficient strength throughout healing to allow a postrepair rehabilitation protocol that will impart passive and modest active stress forces to the repaired tendons. Complications include tendon rupture, digital joint flexion contractures, and adhesions that restrict tendon gliding and ultimately necessitate tenolysis.     

Comparison of modified Kessler tendon suture at different levels in the human flexor digitorum profundus tendon and porcine flexors and porcine extensors: an experimental biomechanical study

This study compared the biomechanical behaviour of repairs in the human flexor digitorum profundus tendon in zones I, II and III with repairs of different segments of the porcine flexor tendon of the second digit and the extensor digiti quarti proprius tendon, in order to assess the validity of porcine tendons as models for human flexor tendon repairs. These porcine tendons were selected after comparing their size with the human flexor digitorum profundus tendon. The tendon repairs were done in three segments of each porcine tendon and repairs in the human tendons were done in zones I,II and III. Ten tendons in each group yielded a total of 90 specimens. A modified Kessler repair was done with 3-0 coated braided polyester suture and subjected to uniaxial tensile testing. In human flexor tendons, the ultimate force was higher in zones I and II than in zone III. The porcine flexor digitorum profundus tendon from the second digit and the proximal segment of the extensor digiti quarti proprius tendon behaved similarly to the human flexor tendon in zone III and can be considered as surrogates for the human flexor tendon.     

Importance of proximal A2 and A4 pulleys to maintaining kinematics in the hand: a biomechanical study

Purpose

The A2 and A4 pulleys have been shown to be important in finger flexor tendon function. Other authors have suggested either reconstruction or venting of portions of these pulleys in an attempt to preserve finger function in certain clinical situations. This study examines the effects of partial incision of these pulleys on finger flexion kinematics and biomechanics.

Methods

The index and ring fingers of 16 cadaveric hands were studied. The flexor digitorum profundus tendon was isolated and attached to a computer driven servo-motor. Micro-potentiometers measured flexion angles of the metacarpophalangeal, proximal inter-phalangeal and distal inter-phalangeal joints. Joint inertial torques were calculated making use of this experimental kinematic data.

Results

Proximal 50 % incisions of either the A2 or the A4 pulleys resulted in a statistically significant decrease in overall finger motion. This effect was greatest in the proximal inter-phalangeal joint, with a decrease in joint motion, as well as an earlier time to initiation of motion. These changes in finger motion were more pronounced with A2 pulley incision than they were with A4 pulley incision, but the changes were statistically significant in either case. No significant changes in joint inertial torques were shown.

Conclusions

Our data provides evidence to the importance of the proximal portions of the A2 and A4 pulleys, and may support partial distal incision of these pulleys in certain clinical situations.     

The Omega "Omega" pulley plasty. A new technique to increase the diameter of the annular flexor digital pulleys

The authors report a new technique of pulley plasty of the flexor digital system. It is not an operative procedure to reconstruct a damaged pulley but an original way to expand the volume of an intact pulley in order to adapt its volume to the diameter of the repaired flexor tendon. The flexor tendons ruptures in Verdan zone II and particularly in Tang zones IIA and IIB are often accompanied by an osteofibrous tunnel injury. Initially, the tendon sheath closure was advised after tendons repair. This sheath recovery had to have an effect on tendons nutrition by establishing the synovial cavity continuity and particularly to protect the tendons from adhesions formation. The closure of the digital tube was rapidly shown to be unnecessary creating an obstacle to the tendons movements without any effect on tendons healing. In primary tendon management, the tendon repair is associated with an increase of the tendon diameter. An incongruence appears with the surrounding digital tube with gliding resistance complicating the tendon injury recovery. In secondary tendon injury management, the flexor digital tube is subject to healing and inflammatory process. This situation with the absence of the flexor tendon generates a retraction with a collapse of the digital tunnel over the injured area. This incongruence between the repaired flexor tendons and the narrowed digital tube required a release of the retracted zone to restore an adequate volume. The only way reported is the "Venting" of a part or the total length of the pulley. This procedure even if it resolves the tendon gliding resistance, is still unacceptable. Indeed it destroys an important anatomical structure of the flexor tendon dynamic system. The flexor pulley Omega plasty "Omega" consists in releasing the lateral palmar attachment of the pulley enhancing its internal volume and increasing the flexor tendon gliding area. The digital tube is composed by the succession of five annular and three cruciform pulleys. The cruciform pulleys are thin and flexible. They retract during the digital flexion assuring the continuity of the digital tube, while the annular pulleys are thicker and fill a biomechanical function. There are two types of annular pulleys: the joint pulleys as A1, A3 and A5; they are attached to the palmar plates of the MP, PIP and DIP joints respectively. During the digital movement, they retract approximately 50% of their length. The osseous pulleys as A2 and A4 are fixed over the lateral and palmar borders of the first and the second phalanx respectively. It is on these pulleys that the Omega plasty is practised. The operative procedure is simple. It consists on a periosteal dissection over the one lateral border of the phalanx. The liberation is undergone palmarly releasing the lateral attachment of the pulley. It respects the anatomical continuity of the pulley and its mechanical properties. Indeed, the continuity of the pulley is fully respected with the periosteal flap of the digital tube floor maintaining sufficient attachment to the pulley to resist to the flexor tendon forces. The level of the flexor tendon injury and the digit position during the initial trauma will determine the level of tendon resistance and where the pulley plasty must be made. If the flexor zone II injury occurred with the digit in an extension position, the tendon conflict appears with the A2 pulley, while it arises with the A4 pulley if the digit was in flexed position. The Omega plasty creates the ideal conditions for an optimal flexor tendon movement recovery. It is a simple and a reproducible procedure. It doesn't distort the mechanical properties of the pulley and the digital tube. We used this pulley Omega plasty fifteen times in twelve patients. In 60% of the cases, the injury concerned the dominant hand, and in 67% of the cases, it was a work accident. In eight of our cases, the omega plasty was done in emergency at the same time of flexor tendon repair, while in the other seven cases, the pulley Omega plasty accompanied the late flexor tendon repair forgotten during the initial trauma management. In ten cases, the plasty concerned the A4 annular pulleys, while in the other five cases, it concerns the A2 annular pulleys. Four cases necessitate a secondary tenolysis three months after the tendon repair. Two patients moved out and cannot be included in our results. On the thirteen-remainder cases, nine retrieved a full digital flexion particularly those who underwent digital tenolysis, while the other four cases retrieved a satisfying digital function in spite of the partial DIP flexion. In our hand, the pulley Omega plasty "Omega" becomes almost a systematic procedure in conjunction with the flexor tendon repair. It offers the ideal conditions for a tendon healing and a physiological flexor tendons motion recovery.     

Vascular anatomy of flexor tendons. I. Vincular system and blood supply of the profundus tendon in the digital sheath.

The detailed blood supply of the flexor tendons in the digital canal was studied in 35 fresh human hands by means of an India ink-latex vascular injection technique. The specimens were examined by first exposing the pulley system, followed by examination of the intact tendon which had been rendered transparent by immersion in a solution of tributyl and tricresyl phosphate. Five annular and three cruciform pulleys were shown. There were five types of long vincula to the profundus (VLP) and three types of long vincula to the superficialis (VLS). The vincular systems of index and little fingers were symmetrical. Occasionally, neither the VLP nor the VLS was found in either the long or the ring fingers. The vincula received blood supply from four transverse branches of the digital arteries. A volar avascular area of the profundus tendon was seen in the cleared cross-sections, and the cross-over zone of its intrinsic vessels was found to be at the midproximal phalanx.     

Hunter手术治疗Ⅱ区屈肌腱陈旧性损伤

目的：探讨治疗Ⅱ区屈肌腱损伤的较佳方法。方法：采用一期手术切除指深、浅屈肌腱,保留或重建滑车,植入Hunter硅胶棒,2－6月后行二期手术,游离移植肌腱方法治疗Ⅱ区陈旧性屈肌腱损伤69例106指。结果：术后平均随访19例,TAM标准评价取得了84％的优良率。结论：硅胶棒植入手术治疗Ⅱ区屈肌腱陈旧性损伤,可有效避免肌腱移植术后经常发生的肌腱粘连,是一种较好手术方法。     

近节指间关节处屈肌腱腱鞘的功能研究

目的探索Ａ３、Ｃ１和Ｃ２滑车对指深屈肌腱及近节指间关节活动的影响。方法采用１０只尸体手示、中、环指，将掌指关节及远节指间关节固定后，进行以下４个阶段的实验：（１）腱鞘完整；（２）Ａ３滑车切除；（３）Ａ３及其近端切开；（４）Ａ４与Ａ２滑车间的腱鞘切开。牵拉指深屈肌腱至近节指间关节屈曲到１１０度时，测量指深屈肌腱的滑动距离。用方差分析法比较各实验阶段结果的差异。结果Ａ３及其周围腱鞘切除后，指深屈肌腱的滑动距离显著增加（Ｐ＜０．０５或＜０．０１），并出现明显的“弓弦＂状畸形。结论研究结果提示临床上行肌腱修复时应注意保留近节指间关节附近滑车的功能。     

Restoration of function of the thumb flexor apparatus requires repair of the oblique and one adjacent flexor tendon pulley

Damage to the pulleys of the thumb flexor apparatus may cause bow-stringing of the tendon and affect muscle function. An experiment using the hands and distal forearms of cadavers was designed to determine which damaged pulleys increase excursion length of the flexor tendon with constant tendon and resisting loads. Each specimen was mounted to a loading frame with a dead weight pinned to the tip of the thumb. The thumb flexor tendon was clamped to an actuator that applied a fixed load and measured excursion of the tendon. Ranges of motion of the thumb joint were also measured. The thumb flexor apparatus of each specimen was tested intact first, with the hand in flexed, neutral, and extended positions; then it was tested with progressive sectioning of pulleys from proximal to distal in one group and from distal to proximal in a second group. The length of excursion increased significantly with all pulleys cut but there was no effect on on overall range of motion of the thumb. With proximal to distal sectioning, no change in tendon excursion occurred when the flexor retinaculum and the first annular pulleys were cut, until the oblique pulley was sectioned, leadving only the second annular pulley intact (range, 1.17–1.31 times that of intact excursion, dependent on position of the hand). With distal to proximal sectioning, tendon excursion was not affected when the second annular and oblique pulleys were cut but did increase when the first annular pulley was sectioned, leaving only the flexor retinaculum intact (range, 1.28–1.36 times that of intact excursion). Dependent on the location of damage, therefore, an intact oblique or first annular pulley can maintain normal excursion of the tendon.     

An experimental study on the application of a hydroxyapatite artificial tendon sheath to prevent adhesions after tendon repair (Part 1)

The formation of adhesions around the lacerated flexor tendons in zone II was studied in chickens after using an artificial tendon sheath made of hydroxyapatite (HAp). The flexor sheath was excised between the proximal and distal pulleys in zone II to create a window in the fibro-osseous tunnel. After suturing the severed profundus tendon, an HAp sheath was placed around the suture site followed by 3 weeks of immobilization. The results were compared with controls in which no HAp sheaths were used after the operation. Adhesion formation was assessed both biomechanically and histologically. The mobility of the tendons was better in the HAp group at all the periods studied. HAp sheath was not firmly adherent to either the granulation tissue or the surface of the tendon. Histology at 3 as well as 6 weeks in HAp groups revealed epitenon-like structure on the tendon surface including the tenorrhaphy site and a wide space around the tendon after the HAp sheath was removed. The outer margins of this space was lined by a layer of fibrocyte-like cells and collagen fibers thereby resembling new formed tendon sheath. In the cases of control, marked peritendinous adhesions were observed.     

Spontaneous flexor tendon ruptures of the hand: case series and review of the literature

Spontaneous flexor tendon ruptures within the hand are incompletely understood. We report 5 cases of spontaneous tendon rupture involving the flexor digitorum profundus tendon. One case involves an abnormal intertendinous connection between the ring and small finger profundus tendons and another involves a lumbrical muscle variant. To our knowledge, the latter has not been reported in association with spontaneous tendon rupture. In reviewing the literature for spontaneous flexor tendon ruptures, a total of 50 spontaneous ruptures in 43 cases was found. The majority involve the profundus tendon of the small finger in the palm. The ruptures most often occur during periods of peak strain but can also occur without identifiable trauma. The pathogenesis of spontaneous tendon ruptures is still unclear and is likely multifactorial. Spontaneous flexor tendon ruptures of the hand occur more often than one might recognize.     

The fate of tendon grafts used to reconstruct the digital annular pulleys

An experimental morphological study on the reconstruction of the digital annular pulleys has been carried out in dogs. The segment corresponding to zones 1 and 2 of the flexor apparatus of the 2nd and 5th digits of the left forepaw was chosen for the experiment. The whole flexor apparatus was resected and a single digital pulley (A 2) was reconstructed, using segments of the animals own deep flexor tendon. A length of silicone rubber tube was used as tendon spacer. The new pulleys showed marked degeneration of the collagen fibres and thinning which increased with time and may be the cause of decrease in strength. A layer of mesothelial cells with secretory properties developed at the interface between the tendon graft and the spacer.     

Traumatic intratendinous flexor digitorum profundus rupture: A case report

Intratendinous ruptures of a flexor digitorum profundus tendon are rare in patients who do not have rheumatoid arthritis. A case of a patient with no history of autoimmune disease who suffered a traumatic rupture of the flexor digitorum profundus tendon to the ring finger in the mid-palm is reported.     

Ruptures of flexor tendons at the wrist as a complication of fracture of the distal radius.

We report two cases of rupture of flexor tendons after fracture of the distal radius. The first case was a rupture of the flexor digitorum profundus and superficialis tendon to the index finger that happened 20 years after the fracture. The second was a rupture of the flexor pollicis longus tendon that occurred two years after, and the flexor profundus tendon to the index finger that occurred four years after the fracture. In the first case, the ruptures were caused by the bony protuberance of the radius after long interval without interference of the ulnar head.     

Reconstruction of flexor tendon pulley with expanded polytetrafluoroethylene (E-PTFE). An experimental study in rabbits

Gore-Tex (expanded Polytetrafluoroethylene, E-PTFE) was used to replace the distal pulleys on the proximal phalanges of 20 rabbits. Morphology and function of the reconstructed pulleys were evaluated at 12-20 weeks. The breaking strength of the E-PTFE pulley equalled that of a normal pulley. Range of motion, tendon excursion, and force of flexion were no different from those of normal pulleys. No adhesions between flexor tendons and synovial tendon sheaths or the E-PTFE pulleys could be detected. No adverse tissue reactions were seen. Fibroblast-like cells from the surrounding tissues had grown into the membrane. In other experiments, where the pulleys had been either removed or detached, local fibrosis and adhesions were seen, and the deep flexor tendons had ruptured. The results of the present study indicate that E-PTFE can be used as a biosynthetic replacement for damaged pulleys.     

Flexor tendon rupture caused by gout: a case report

We present a case of primary gouty infiltration of flexor tendons in the hand, causing rupture of both flexor digitorum superficialis and profundus tendons in a single digit. The patient was managed by a single-stage reconstruction of the less involved flexor digitorum superficialis tendon using a segment of the proximal stump of flexor digitorum profundus tendon as a bridge graft. This uncommon etiology of tendon rupture should be considered in all patients with a history of gout presenting with tendon insufficiency.