In vivo flexor tendon forces increase with finger and wrist flexion during active finger flexion and extension.

The effects of different hand motions and positions used during early protected motion rehabilitation on tendon forces are not well understood. The goal of this study was to determine in vivo forces in human flexor digitorum profundus (FDP) and flexor digitorum superficialis (FDS) tendons of the index finger during active unresisted finger flexion and extension. During open carpal tunnel surgery (n = 12), flexor tendon forces were acquired with buckle force transducers, and finger positions were recorded on video while subjects actively flexed and extended the fingers at two different wrist angles. Mean in vivo FDP tendon forces varied between 1.3N +/- 0.9 N and 4.0 N +/- 2.9 N while mean FDS tendon forces ranged from 1.3N +/- 0.5 N to 8.5 N +/- 10.7 N. FDP force increased with active finger flexion at both wrist angles of 0 degrees or 30 degrees flexion. FDS force increased with finger flexion when the wrist was in 30 degrees flexion, but was unchanged when the wrist was in 0 degrees of flexion. Tendon forces were similar regardless of whether the fingers were moving in the flexion or extension direction. Active finger flexion and extension with the wrist at 0 degrees and 30 degrees flexion may be used during early rehabilitation protocols with limited risk of repair rupture. This risk can be further decreased for a FDS tendon repair by reducing wrist flexion angle.     

Zone I flexor tendon rehabilitation with limited extension and active flexion.

This article describes an immediate active motion protocol for primary repair of zone I flexor tendons treated with tendon to tendon, or tendon to bone repair, and reviews clinical results. A rehabilitation protocol is proposed that will limit excursion of the zone I repair by blocking full distal interphalangeal (DIP) extension and by applying controlled active tension to both the unrepaired flexor digitorum superficialis (FDS) and the repaired flexor digitorum profundus (FDP). The rehabilitation technique utilized a dorsal protective splint with a relaxed position of immobilization with 30 degrees of wrist flexion, 40 degrees of metacarpophalangeal (MP) joint flexion, and a neutral position for the proximal interphalangeal (PIP) joints without dynamic traction. In addition, within the confines of the dorsal splint, the involved DIP joint was splinted at 40-45 degrees to prevent DIP joint extension during the early wound healing phases. Relaxed composite flexion was used to apply active tension to both the uninjured FDS, and the repaired FDP. This technique applies excursion of approximately 3 mm to the zone I tendon in a limited arc (45-75 degrees). The modified position of active flexion applies low loads of force (< 500 g), even with drag considered. This technique is supported by previous mathematical studies of excursion and internal tendon force, and clinical experience. Forty nine cases treated over a 10-year period were reviewed, and eight were excluded for incomplete follow-up. The use of this protocol for 41 zone I flexor digitorum profundus repairs by 12 different surgeons using varied surgical techniques was evaluated. None of the tendon to tendon repairs used more than two suture strands for the core repairs. Mean total active range of motion was 142 degrees (PIP 95 degrees plus DIP 47 degrees), or 81% of normal. Three tendons ruptured in non-protocol-related incidents and were excluded from the study. Results from this clinical study support the use of limited DIP extension combined with active tension with conventional repair in zone I.     

Use of a relative motion flexion orthosis after epitendinous zone II flexor tendon repair: A case report

Study designCase reportIntroductionRelative motion flexion (RMF) orthoses are emerging as an option for early active motion (EAM) postoperatively.Purpose of the studyTo describe the rationale and implementation of an RMF orthosis to manage a patient after partial zone II epitendinous flexor tendon repairs.MethodsThis case involves a female who sustained partial flexor tendon lacerations to her middle finger in zone II, 60% flexor digitorum superficialis (FDS) and 90% flexor digitorum profundus (FDP). After epitendinous repair she was referred to therapy for EAM with a no orthosis request. The unusual circumstances prompted the therapist, concerned about the risk of tendon rupture to engage in discussion with the surgeon. Following discussion, a decision was made to use an RMF orthosis for controlled EAM to protect the epitendinous zone II FDS and FDP repairs. Outcomes of range of motion (ROM), total active motion (TAM), %TAM, grip, and quickDASH are reported.ResultsNeither the FDP or FDS tendons ruptured, nor were there any joint contractures. “Good” %TAM outcomes were achieved at 12-week postoperatively. Quick DASH scores improved 61 points indicating a clinically meaningful difference of improved function.DiscussionThe lack of a multi-strand core suture repair is unusual in combination with EAM. The positive outcomes reported in this single patient have raised questions about the protective benefit of the RMF orthosis when used with a zone II epitendinous repair of a 90% FDP laceration. Epitendinous repair of a partial (60%) FDS injury, however, is not uncommon and often not repaired at all.ConclusionsIn this single case report the epitendinous repairs of zone II 90% FDP and 60% FDS with digital nerve involvement were successfully managed with an RMF only orthosis. The use of EAM with an epitendinous repair is in conflict to the current surgical and therapy literature.     

Effects of superficialis tendon repairs on lacerated profundus tendons within or proximal to the A2 pulley: an in vivo study in chickens

PURPOSE: In a flexor tendon injury model in chickens we undertook a study to evaluate effects of the flexor digitorum superficialis (FDS) tendon repairs on excursions, work of flexion, and adhesions of the repaired flexor digitorum profundus (FDP) tendon after their injuries within or proximal to the equivalent of the A2 pulley and early tendon motion. METHODS: Thirty-five leghorn chickens were divided into 3 groups. In group 1 the FDS and FDP tendons of the long toes on both sides were transected in the area covered by the pulley. In group 2 the tendons were transected proximal to the pulley. In the first 2 groups, both tendons were repaired on the left feet, and only the profundus was repaired with superficialis excision on the right. The operated toes underwent simulated passive flexion for 3 weeks and results were evaluated 8 weeks after surgery. Chickens in group 3 were unoperated and served as the controls. RESULTS: When the tendons were cut within the pulley the FDP excursions and work of flexion were significantly better in the toes in which the FDS was excised than in those with both tendon repairs. When they were cut proximal to the pulley the repairs of both tendons had outcomes similar to that with excision of the FDS. Adhesions were more severe when both tendons were repaired under the pulley as compared with those after repair of a single tendon. CONCLUSIONS: This study showed different effects of the surgical repair or excision of the FDS on the FDP tendon within or proximal to a major pulley. Repair of both tendons worsens the gliding of the FDP tendon and increases adhesions within the major pulley; however, repair of both tendons yields outcomes equivalent to that after repair of only the FDP tendon proximal to the pulley.     

Impact of flexor digitorum superficialis on gliding function of the flexor digitorum profundus according to regions in zone II

PURPOSE: Structures and gliding characteristics of the flexor tendons vary remarkably according to regions of zone II in the hand. We studied the impact of the flexor digitorum superficialis (FDS) on the work of flexion and excursion efficiency of the flexor digitorum profundus (FDP) tendon in different regions of zone II. METHODS: Twenty-one fresh-frozen human fingers were used as an experimental model. The FDP was pulled to flex the finger with a tensile machine. The work of flexion of the finger and gliding excursion of the tendon were recorded in the fingers with the FDS intact, after excision of the FDS proximal to, under, or distal to the A2 pulley. RESULTS: The FDS tendon exerts notably different effects on the work of flexion and excursion efficiency of the FDP in subregions of zone II. Removal of the FDS under the A2 pulley affected the FDP most manifestly, causing a 12% decrease in the work of flexion and a loss of the excursion efficiency at the metacarpophalangeal joint. Removal of the FDS proximal to the A2 pulley had a less notable effect on the work of flexion. Removal of the FDS distal to the pulley did not markedly alter the biomechanics of the FDP. CONCLUSIONS: Removal of the FDS tendon in the area of the A2 pulley reduces the work of flexion most notably and causes a loss of excursion efficiency. Removal of the FDS tendon distal to the A2 pulley does not change the work of flexion, and removal of the FDS tendon proximal to the A2 pulley has a notable but less pronounced effect on the FDP tendon.     

Long-term results after primary repairs of zone 2 flexor tendon lacerations in children younger than age 6 years

In young children, methods of primary flexor tendon repair in the digital canal are controversial. The authors reviewed 12 children younger than age 6 years with zone 2 flexor tendon repairs. The mean follow-up period was 8 years. In all cases, the flexor digitorum profundus tendons were repaired according to the Kessler modified technique and the hands were immobilized by an above-elbow cast. As for postoperative complications, there were no fingers with tendon rupture and two fingers with tendon adhesion. One finger needed tenolysis. The total active motion (TAM) in the interphalangeal joints evaluated with the Strickland formula averaged 155 degrees, and the TAM percentage averaged 89% (range 74%-100%). Eleven patients had an excellent result and one had a good result. The percentage phalangeal length averaged 99% (range 96%-100%). Functional motion and nearly normal growth of the finger can be expected after primary zone 2 flexor tendon repairs in children younger than age 6 years.     

Relative motion flexion following zone I-III flexor tendon repair: Concepts,evidence and practice.

Study DesignNarrative review and case series.IntroductionThe relative motion approach has been applied to rehabilitation following flexor tendon repair. Positioning the affected finger(s) in relatively more metacarpophalangeal joint flexion is hypothesized to reduce the tension through the repaired flexor digitorum profundus by the quadriga effect. It is also hypothesized that altered patterns of co-contraction and co-inhibition may further reduce flexor digitorum profundus tension, and confer protection to flexor digitorum superficialis.MethodsWe reviewed the existing literature to explore the rationale for using relative motion flexion orthoses as an early active mobilization strategy for patients after zone I-III flexor tendon repairs. We used this approach within our own clinic for the rehabilitation of a series of patients presenting with zone I-II flexor tendon repair. We collected routine clinical and patient reported outcome data.ResultsWe report published outcomes of the clinical use of relative motion flexion orthoses with early active motion, implemented as the primary rehabilitation approach after zone I-III flexor digitorum repairs. We also report novel outcome data from 18 patients.DiscussionWe discuss our own experience of using relative motion flexion as a rehabilitation strategy following flexor tendon repair. We explore orthosis fabrication, rehabilitation exercises and functional hand use.ConclusionsThere is currently limited evidence informing use of relative motion flexion orthoses following flexor tendon repair. We highlight key areas for future research and describe a current pragmatic randomized controlled trial.     

Resection of the flexor digitorum superficialis reduces gliding resistance after zone II flexor digitorum profundus repair in vitro

The effect of complete or partial resection of the flexor digitorum superficialis (FDS) tendon on the gliding resistance of the flexor digitorum profundus (FDP) tendon after FDP tendon repair was investigated. Twenty-four human FDP tendons were cut to 80% of their transverse section and repaired with a modified Kessler or a Massachusetts General Hospital augmented Becker suture technique. Gliding resistance was measured with the following constructs: intact state, sutured FDP tendon with FDS tendon intact, sutured tendon without FDS tendon, and sutured tendon with one slip of FDS tendon excised. After FDP repair the gliding resistance after modified Kessler repair increased 247% with FDS intact, 132% with one slip of FDS present, and 103% with FDS entirely removed. With a Becker repair, resistance increased 671% compared with normal with the FDS intact, 379% with one slip of the FDS, and 348% without the FDS tendon. Preserving the whole FDS resulted in a significantly larger increase in gliding resistance after FDP repair than did full or partial FDS removal, which were not significantly different from each other. These results suggest that the FDS tendon affects the gliding resistance under the pulley after FDP repair and that partial FDS excision may facilitate gliding of a bulky FDP repair.     

Neglected flexor tendon injury for 10 years,un-usual finding and one stage repair without free tendon graft: Case report

IntroductionIn delayed or neglected cases of flexor tendon injury, reconstruction of flexor digitorum profundus (FDP) is usually performed using free tendon graft due to the retraction of tendon ends and shortening of the tendon. Flexor digitorum superficialis (FDS), palmaris longus or plantaris tendons can be used as a free tendon graft [1–3].Presentation of caseThis is a case report of female patient 17 years old with neglected cut of her left Ring finger's FDP and FDS tendons zone II with suspected concomitant digital nerve injury, the injury was neglected for 10 years in the patient's non-dominant hand.DiscussionUpon exploration unusual finding of spontaneous healing of the proximal stumps of FDS and FDP tendons raised the idea of doing the repair one stage without free graft by using pedicled intra-synovial graft from the sublimis tendon to reconstruct the FDP tendon.The patient after 4 months follow-up and after completion of the physiotherapy program regained the ability to actively flex her finger to near full flexion with improved function and cosmesis.ConclusionDelayed flexor tendon reconstruction in neglected cases is still offering good results even after long periods of delay provided that the finger's joints are still supple and mobile.     

Wide-Awake Approach for Flexor Digitorum Superficialis Tendon Transfer Followed by Early Active Mobilization

Background The standard clinical practice to treat closed ruptures of the flexor digitorum profundus (FDP) tendons includes free tendon grafting; however, it is not suitable when the muscle amplitude of the ruptured FDP is not sufficient. We report outcomes of six patients who underwent flexor digitorum superficialis (FDS) tendon transfer of the ring finger using the wide-awake approach to repair the closed rupture of the FDP tendon of the little finger in zone 3 or 4. Methods The patients were identified by reviewing our institutional billing records from January 2012 to October 2019 for the International Classification of Disease 10 code M66.3 that describes the diagnosis as “spontaneous rupture of flexor tendons.” Results The patients comprised two men and four women with an average age of 72.2 years (standard deviation [SD], 8.4 years). All patients were hospitalized after surgery to undergo early active mobilization. The average total active motion at the final evaluation was 201.8° (range: 85–248°). According to Strickland’s criteria, outcomes were excellent for two, good for three, and poor for one patient. No patients complained about the ring finger. Conclusion These results suggest that FDS tendon transfer is recommended when the muscle amplitude of the ruptured FDP is insufficient. We believe that the wide-awake approach and early active mobilization may contribute to satisfactory outcomes.     

Gliding resistance after FDP and FDS tendon repair in zone II

Many suture techniques have been described for flexor tendon repair. While many of these sutures have been tested and used clinically, the interaction between repairs of the flexor digitorum profundus (FDP) and flexor digitorum superficialis (FDS) in the same digit has not been rigorously examined. Moreover, while much data are available on the mechanical properties of various suture techniques for FDP repair, much less is known about the mechanical performance of FDS repairs during motion of tendons.

To make up for this lack of information, we measured the gliding resistance of the repaired FDP tendon, as compared to different FDS tendon repairs in a human cadaver model. The FDP tendon was repaired with a modified Kessler technique, while the FDS was repaired with a modified Kessler (n = 10), Becker (n = 10), or a new double running zig-zag suture (n = 10). The modified Kessler repair had a threefold increase from normal gliding resistance, the Becker repair increased twofold, and the zig-zag repair increased twofold. The peak gliding resistance increased twofold with a modified Kessler repair, 2.5-fold with a Becker repair, and 2.5-fold with a zig-zag repair.     

Gliding resistance after FDP and FDS tendon repair in zone II: an in vitro study

Many suture techniques have been described for flexor tendon repair. While many of these sutures have been tested and used clinically, the interaction between repairs of the flexor digitorum profundus (FDP) and flexor digitorum superficialis (FDS) in the same digit has not been rigorously examined. Moreover, while much data are available on the mechanical properties of various suture techniques for FDP repair, much less is known about the mechanical performance of FDS repairs during motion of tendons. To make up for this lack of information, we measured the gliding resistance of the repaired FDP tendon, as compared to different FDS tendon repairs in a human cadaver model. The FDP tendon was repaired with a modified Kessler technique, while the FDS was repaired with a modified Kessler (n = 10), Becker (n = 10), or a new double running zig-zag suture (n = 10). The modified Kessler repair had a threefold increase from normal gliding resistance, the Becker repair increased twofold, and the zig-zag repair increased twofold. The peak gliding resistance increased twofold with a modified Kessler repair, 2.5-fold with a Becker repair, and 2.5-fold with a zig-zag repair.     

Traumatic simultaneous rupture of both flexor tendons in a finger of an athlete

We report a case of traumatic simultaneous disruption of both finger flexor tendons in a professional athlete. The novelties in this report are (1) the location of the rupture (FDS at midsubstance and FDP at insertion) and (2) the proposition that a normal but diminutive FDS tendon is a contributing factor in the rupture. We recommend that simultaneous rupture of the normal flexor tendons be treated in a similar manner as tendon lacerations. Primary repair, if possible, is the treatment of choice in these acute injuries. Tendon grafting should be reserved for subacute or chronic cases in which restoration of active finger flexion is needed.     

The Effect of Pulley Reconstruction on Maximum Flexion,Bowstringing, and Gliding Coefficient in the Setting of Zone II Repair of FDS and FDP: a Cadaveric Investigation

Purpose

The purpose of this experiment was to determine the effect of A2 pulley reconstruction on gliding coefficient (GC), bowstringing, and proximal interphalangeal (PIP) joint maximum flexion angle after zone II repair of flexor digitorum superficialis (FDS) and flexor digitorum profundus (FDP) lacerations.

Methods

Fresh frozen cadaver forearms were mounted, and the wrist and MCP joints fixed. FDS and FDP tendons were dissected free, and sequential loads were applied while digital images were captured. The dissected digit with intact native A2 pulley, FDS, and FDP tendons was used as the control (group 1). Zone II lacerations followed by four-stranded repair of FDP plus epitendinous suture and repair of FDS were then performed, and the data recorded (group 2). A2 pulley excision and reconstruction with a loop of palmaris longus autograft was then completed and the specimens sequentially loaded and photographed (group 3). Using the digital images, GC, bowstringing, and maximum flexion angle were calculated.

Results

No difference in maximum flexion angle was observed across the three testing conditions. Zone II laceration and subsequent FDS and FDP tendon repair significantly increased the GC for group 2 specimens; however, pulley reconstruction alleviated some of this increase for group 3. Bowstringing was significantly greater after pulley reconstruction, with a mean increase of 1.9 mm at maximum flexion for group 3 specimens relative to group 1 controls.

Discussion

Strong flexor tendon repairs are needed to prevent gap formation and subsequent triggering; however, the increased bulk from these large repairs can itself produce deleterious triggering, as well as tendon abrasion. Pulley reconstruction, in the setting FDP and FDS repair (group 3), significantly reduced the GC relative to tendon repair alone (group 2). While bowstringing was significantly greater after pulley reconstruction (group 3), it averaged only 1.9 mm over group 1 specimens and did not compromise maximum flexion angle compared to the uninjured controls (group 1) or the isolated tendon repair digits (group 2).     

Ultrasound assessment of the motion patterns of human flexor digitorum superficialis and profundus tendons with speckle tracking

The purposes of our study were to correlate ultrasonographically measured and joint angle estimated excursions of the flexor digitorum superficialis (FDS) and flexor digitorum profundus (FDP) tendons of the hand and to estimate the relative motion of FDS and FDP while gripping cylinders of standard diameter in normal human subjects. Thirty wrists from 15 human subjects were imaged with an ultrasound scanner. Speckle tracking was used to measure the excursion of the FDS and FDP tendons. The tendon excursions necessary to grip three differently sized acrylic tubes were measured and correlated with the corresponding finger joint angles. The FDP/FDS excursion ratio was calculated. The Pearson's correlation coefficient between the FDS excursion and MP + PIP joint angle was 0.61. The Pearson's correlation coefficient between the FDP + FDS excursion and the DIP + PIP + MP joint angle was 0.67. The FDP/FDS excursion ratio was smaller for larger excursions (gripping a smaller diameter tube) and larger for small excursions (gripping a larger diameter tube, P < 0.01). These data suggest that speckle tracking may be a useful method to discriminate the relative motion of flexor tendons, which in turn may be relevant in evaluating tendon function, for example after tendon injury. © 2011 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 29: 1465–1469, 2011     

Remodeling of the gliding surface after flexor tendon repair in a canine model in vivo.

Maintaining a smooth lubricated surface between the flexor tendon and sheath after tendon repair is very important for restoration of digit function. We studied the tendon surface after tendon repair mechanically in a canine model in vivo by measuring frictional force. One hundred and twenty flexor digitorum profundus (FDP) tendons were lacerated to 80% of their cross-section and repaired with either a modified Kessler (MK) or Becker (MGH) repair. The postoperative therapeutic regimen was either synergistic wrist and digit motion (SWM) or passive digit flexion and extension with the wrist fixed in 45 degrees of flexion (FIX). The dogs were sacrificed at one, three, or six weeks postoperatively. Thirty six FDP tendons from normal paws served as the control group, with each control tendon tested in two different conditions: intact and immediately after partial laceration and repair (0 time), making a total of five different timing points (intact, 0 time, one week, three weeks, and six weeks) for each repair type and each postoperative therapy. Frictional force between tendon and proximal pulley was evaluated after breaking any adhesions. Compared to intact tendons, friction was significantly increased immediately after tendon repair. The friction of the MK repair was significantly less than that of the MGH repair at all time and therapy groups, except at six weeks in the SWM group. For the MGH repair, at six weeks friction in the SWM group was significantly less than friction in the FIX group. This study showed that postoperative tendon gliding depends on the method of tendon repair and the postoperative therapy regimen. Furthermore, we have demonstrated that the gliding surface after tendon repair remodels with time.     

Partially retained small finger flexor digitorum profundus function despite complete tendon loss in the forearm

A case of traumatic laceration of the small finger flexor digitorum profundus (FDP) tendon in the distal forearm with retained partial active flexion at the small finger distal interphalangeal joint (DIP) joint is described. Tendinous interconnections between the ring and small FDP tendons and lumbrical muscles may permit partial FDP function at the DIP joint despite a complete deficit of the proximal tendon.     

Flexor tendon injuries in children

Flexor tendon injuries in adults differ from those in children. 38 children (22 male and 16 female) with a mean age of 6.7 years were treated for flexor tendon injuries by primary suture and controlled mobilization between 1985 and 1992. 53 flexor tendons were injured (average 1.5 digits per patient) and the injury most commonly affected the little finger (23 patients). 60% of injuries occurred in zone 2. Using Lister's criteria, 82% achieved excellent or good results. Repair of both FDS and FDP was better than repair of FDP alone, even in zone 2. There were three tendon ruptures(all classified as poor results) and one other poor result occurredin a zone injury with an associated ulnar nerve palsy. The outcome after flexor tendon repair in children is better than in adults in our hands because rapid healing of tendons occurs in children. No child has yet required tenolysis because in children adhesions are more pliable. Both flexor tendons should be repaired irrespective of the zone of injury. A functional hand can be expected after flexor tendon repair in children.     

Ⅱc区早期修复深浅指屈肌腱后A2滑车的处理

目的 探讨指屈肌腱Ⅱc区单纯切割伤双腱修复后A2滑车不同处理对肌腱功能的影响。方法 将21只来亨鸡随机分为二组,以鸡双足中趾为手术趾,在每趾肌腱均造成屈趾浅肌腱(FDS)、屈趾深肌腱(FDP)单纯切割伤,并行双腱修复。A组:A2滑车完整;B组:A2滑车切开;C组:A2滑车扩大。术后10周末处死动物,对鸡趾分别进行生物力学和形态学评定。结果 Ⅱc亚区屈肌腱单纯切割伤早期双腱修复后,A2滑车切开组与A2滑车扩大组的肌腱滑动距离明显大于A2滑车完整组,屈曲功则明显小于A2滑车完整组,而A2滑车切开组与A2滑车扩大组之间无论是肌腱滑动距离还是屈曲功在统计学上则无明显差异(P>0.05)。结论 临床上Ⅱc亚区FDS、FDP腱损伤早期双腱修复后作A2滑车切开或扩大成形术,有利于肌腱滑动和功能恢复。     

Closed rupture of both flexor digitorum profundus and superficialis tendons of the small finger in zone II: case report

We report a rare case of closed rupture of both flexor digitorum profundus (FDP) and flexor digitorum superficialis tendons in zone II in the small finger. We performed delayed, primary end-to-end suture of the FDP and excision of the flexor digitorum superficialis, because myostatic contracture of the FDP tendon was not severe and the FDP tendon remnants were not frayed.