Deep Flexor Tendon Research Articles

Structural Failure Mechanisms of Common Flexor Tendon Repairs.

This study investigated the exact failure mechanisms of the most commonly used conventional tendon repair techniques. A new method, radiographing repair constructs in antero-posterior and lateral projections before and after tensioning was used. This allowed to precisely analyse failure mechanisms in regards to geometrical changes in all three dimensions. Additionally the biomechanical stability focusing on gapping was tested. Sheep fore limb deep flexor tendons were harvested and divided in eight groups of ten tendons. Three common variants of the Kessler repair method and four common 4-strand repair techniques were tested. Additionally a new modification of the Adelaide repair was tested. Biomechanical testing showed no significant differences in gapping for the three tested 2-strand Kessler repair groups. Once a double Kessler or 4-strand Kessler repair was performed the stability of the repair improved significantly. Further significant improvements in biomechanical stability could be achieved by using cross locks in the repair like in the Adelaide repair method. Qualitative analysis using radiographs showed that all Kessler repair variants unfolded via rotations around the transverse suturing component, no matter which variant was used. Additional to the commonly described constriction of the repair construct, the rotating deformation is the main reason for repair site gapping in Kessler tendon repair methods. The term "locking" in a Kessler repair is misleading. The cruciate repairs tended to loose grip and drag (cheese-wire) through the tendon and therefore lead to gapping. The most stable repair constructs in all three dimensions were the Adelaide repair and its interlocking modification. This is due to the superior anchoring qualities of its cross locks and three dimensional stability.

Biomechanical and Macroscopic Evaluations of the Effects of 5-Fluorouracil on Partially Divided Flexor Tendon Injuries in Rabbits.

Background:The main goals of flexor tendon surgery are to restore digital motion by providing tendon healing and to preserve tendon gliding. Our purpose was to investigate the effects of 5-fluorouracil (5-FU) on tendon adhesions in partially divided profundus flexor tendons (flexor digitorum profundus [FDPs]) following surgical repair and in partially divided FDPs without surgical repair, and to compare the results of the repair versus the nonrepair of zone two injuries via macroscopic and biomechanical evaluations of tendon adhesions.Methods:We used 32 adult male European rabbits (Oryctolagus cunniculus) weighing from 2.5 to 3.5 kg. The study was performed on the deep flexor tendons of the second and third digits of the right hind paws of the rabbits; thus, a total of 64 tendons were examined in this study.Results:Based on the results achieved in our experimental study, the load (N) significantly increased in subgroup 1a in which the tendons were surgically repaired and were not treated with 5-FU compared with subgroup 2a in which tendons were surgically repaired and treated with 5-FU.Conclusions:The load (N) significantly increased in subgroup 1a in which the tendons were surgically repaired and were not treated with 5-FU compared to subgroup 2a in which the tendons were surgically repaired and treated with 5-FU. Therefore, these results revealed a decrease in adhesion formation in the subgroup that was treated with 5-FU due to increased resistance to tendon adhesions during their excursion through the tendon sheath, which in this case required greater traction force.

Effectiveness of flexor tenolysis in zone II: A retrospective series of 40 patients at 3 months postoperatively

Flexor tendon tenolysis consists of the surgical release of adhesions formed around tendons that persist despite splinting and appropriate rehabilitation. The aim of this study was to evaluate the increase in active range of motion following flexor tenolysis in zone II and to document the ensuing complications. Sixty patients (75 fingers) underwent zone II flexor tenolysis following flexor tendon injury, with or without dorsal tenolysis or PIP arthrolysis. Tenolysis cases following tendon graft or replantation were excluded. Both passive and active ranges of motion were measured at metacarpophalangeal, proximal and distal interphalangeal joints preoperatively and postoperatively at 6 weeks (57 patients) and 3 months (40 patients). These measurements were completed by a functional evaluation using the Strickland classification. Any complications were noted. Mean preoperative total active motion (TAM) was 128°, increasing postoperatively to 188° at 6 weeks and 192° at 3 months. Mean increase in TAM for patients undergoing tenolysis only was 60°, compared to 90° in those undergoing tenolysis with arthrolysis. The functional outcome at 6 weeks was excellent in 23% of cases, good in 47%, average in 20% and poor in 10%. Deep flexor tendon rupture occurred in seven cases. Palmar flexor tenolysis can improve active range of motion of the fingers, and consequently, function.

Finger injuries in ball sports

Ball sports are the most frequent cause of sport injuries and 60% of all hand injuries involve the fingers. The most common injury is closed rupture of the extensor tendon of the distal interphalangeal joint (mallet finger). Rupture of the deep flexor tendon (jersey finger) occurs particularly in contact ball sports, such as rugby. Injuries of the proximal interphalangeal and metacarpophalangeal joints are of high functional relevance. These injuries frequently represent complex lesions which are demanding both in diagnostics and therapy. Errors in diagnosis or insufficient treatment can lead to misalignment and functional impairment of the hand. This article provides an overview of the current treatment strategies and includes recommendations for the treatment of professional athletes.

Laminitis: a perennially life-threatening disease

L aminitis is a disease associated with ischaemia (loss of blood suppy) to digital epidermal tissues. The bond between the dermal and epidermal laminae (the inter-laminar bond) is the only means of support of the coffin bone within the hoof. Horses are suspended within their hooves by this interlaminar bond; if the laminar bond is destroyed, the pedal bone moves distally within the hoof capsule. Laminitis can be acute (actively laminitic) or chronic (had laminitis in the past but not painful presently). Laminitis can be ‘rotational’ (the laminar bond has broken down at the dorsal region of the hoof and the coffin bone is pulled downwards by the deep flexor tendon) or ‘sinking’ (where a greater proportion of the laminar bed is deprived of blood, and consequently nutrients, resulting in the coffin bone sinking downwards within the hoof capsule).

Graft tendon slippage with metallic and bioabsorbable interference screws under cyclic load: a biomechanical study in a porcine model

Introduction The rupture of the anterior cruciate ligament (ACL) is the most common type of knee injury. Reconstructive surgery is the ‘gold standard’ treatment. During the immediate post-operative period, the fixation of the graft is entirely dependent on the ability of the grafted implant to be secured inside the bone tunnel under the cyclical loads associated with daily tasks. Poor fixation can lead to graft slippage, thus impairing the healing and integration of the graft. The aim of this study was to evaluate the biomechanical performance of tendon graft fixation devices with metallic and bioabsorbable interference screws. Methods Twenty ACL reconstructions were carried out in porcine tibias using deep flexor tendons to fix 9 × 20 mm metallic (n=10) and PLLA 70/30 bioabsorbable screws (n=10). To verify the ability of a construct to resist immediate postoperative (PO) rehabilitation protocols for immediate load bearing, a cyclic loading test was applied with 50-250 N of tensile force at 1 Hz for 1000 cycles, and the displacement was measured at 10, 50, 100, 500 and 1000 load cycles to quantify the slippage of the graft during the test. After the cyclic loading test, a single-cycle load-to-failure test was applied. Results The slippage of the graft using metallic screws did not differ (P = 0.616) from that observed when using bioabsorbable screws. Conclusion The results obtained in this experiment indicate that metallic screws may promote a similar amount of graft slippage during low cyclic loading as bioabsorbable screws. Additionally, there was no difference in the biomechanical performance of these two types of screws during high failure loads.

Transfer of the Fifth Finger to Replace an Amputated Thumb: A Preliminary Study.

Amputation of the thumb causes not only loss of significant functional use of the hand but also psychological and social problems. The procedures of toe-to-thumb transfer, pollicization, or metacarpal extension are recognized and well-documented options in thumb reconstruction. Although these techniques have been successfully applied, they have some disadvantages. This study aims to test the feasibility of the fifth finger for thumb reconstruction. The fifth finger was released following exploration of the digital artery, vein, nerve, and flexor and extensor tendons, including the flexor retinaculum. The digital vein and the extensor tendon of the fifth finger were separated at the level of the metacarpophalangeal joint. The proximal phalanx of the fifth finger was cut smoothly at the level of the metacarpophalangeal joint with a saw. The deep flexor tendons, digital arteries, and nerves were preserved. The proximal phalanx of the released fifth finger was fixed to the first metacarpal bone. The digital vein of the first finger was anastomosed to the digital vein of the fifth finger by microsurgery. Angiography was done after the transfer. Exploration till the flexor retinaculum enabled thumb transfer without any restriction of movement in all 10 cadaver fingers. The average total surgical time was 135 ± 12 minutes. Flow from both radial and ulnar arteries was demonstrated in the transferred fifth finger by angiography. The technique appears to be feasible for thumb reconstruction by preserving digital arteries and nerves in a relatively short time, but further important aspects have to be assessed in further clinical studies.

Tendon structural adaptations to load exercise are inhibited by anabolic androgenic steroids

The present study investigated the structural changes in the rat calcaneal tendon (CT), superficial flexor tendon (SFT), and deep flexor tendon (DFT) in response to jump exercises and anabolic androgenic steroids (AAS). Animals were divided into four groups: sedentary, trained, AAS-treated sedentary rats, and AAS-treated trained animals. Training increased the volume density (Vv%) of blood vessels in all regions of the CT and DFT, cell Vv% in the peritendinous sheath of the proximal and distal regions of the SFT and proximal region of DFT, and cell Vv% in the tendon proper of the proximal and distal regions of the SFT and DFT. The combination of AAS and load exercises showed little increased blood vessel Vv% at the proximal region of the CT, intermediate region of the SFT, and all regions of the DFT as opposed to an increase in adipose cell Vv% in the CT proximal region. The AAS reduced the levels of hydroxyproline in the proximal region of the DFT and in the distal region of the STF. In conclusion, exercise promoted benefits to the adaptation of the tendons to overload. These effects were absent when load exercise was combined with AAS. The abusive consumption of AAS contributes to tendon inertness and rigidity, and increases the potential risk of injury.

Wiederherstellung der Daumenendgelenkbeugung durch Transposition der oberflächlichen Beugesehne des Ringfingers

Restoration of active thumb flexion at the distal joint. Loss of active flexion of the interphalangeal (IP) joint of the thumb if there is a transection of the flexor pollicis longus (FPL) tendon at the tendon channel of the thumb or thenar and direct suture is not possible but the tendon channel is intact, as alternative procedure to a free tendon graft if the transection is proximal to the tendon channel and the muscle of the FPL is contracted/injured or the FPL tendon is unharmed but the FPL muscle is partially or complete paralyzed. Insufficiency of the FPL tendon channel, impairment of the superficial or deep flexor tendon of the ring finger, limited passive motion of the proximal and distal thumb joints, acute local general infection and non-compliance or incapacity of the patient. The surgical technique depends on the necessity of transosseous refixation of the FDS IV at the base of the distal phalanx of the thumb or the possibility of woven sutures through the FPL proximal to the tendon channel. If the tendon channel is intact the distal part of the FPL tendon is shortened to 1cm, the FDS IV tendon is cut distal to the chiasma of Camper, pulled through the carpal tunnel and moved into the channel of the FPL tendon and fixed transosseously through the base of the distal phalanx of the thumb. If the transection of the FPL tendon is located proximal to the tendon channel and muscle of the FPL is injured, FDS IV tendon will be woven using the Pulvertaft technique through the FPL tendon at the distal forearm. Postoperative 6weeks motion of thumb flexion without resistance in relieved position of the thumb through a thermoplast splint and 6weeks of functional use of the hand with increasing weight bearing. In this study 10patients with FDS IV transposition to reconstruct an isolated rupture of the FPL tendon could be followed for an average of 4.1years postoperatively. The active range of motion of the IP joint of the thumb averaged 65° (10-100°), 8/10patients achieved an equal active and passive range of motion of the IP joint of the thumb, in 2patients some flexion insufficiency remained, 9 patients could reach the fingertip of the small finger with the thumb and 1patient lacked 3mm. Contracture of the proximal thumb joint developed in two patients. After removal of the FDSIV tendon two patients developed contracture of the PIP joint of the ring finger. The grip force was reduced to 81 %, lateral grip to 83 % and pinch grip to 77 %. The DASH score averaged 18 (0-31) and 8/10patients would choose to undergo this surgery again.

Percutaneous flexor tenotomy for preventing and treating toe ulcers in people with diabetes mellitus

IntroductionThe purpose was to examine the effectiveness of flexor tenotomy in a modified technique to prevent and heal neuropathic and neuroischaemic pressure ulcers on the tip of the toe in claw- or hammer-toe deformities in people with diabetes. Patients and methodsA consequetive 4 years series of 38 patients was retrospectively studied. Percutaneous tenotomy on the superficial and deep flexor tendons was performed in 65 toes through a small transverse plantar stab incision just proximal to the web level. There were 16 (42%) patients with 27 ulcerated toes and 22 (58%) patients with 38 toes with impending ulceration. Ten patients had neuropathic ulcers and six patients had neuro-ischaemic ulcers. Sixteen patients (42%) had macrovascular disease. Ten (26%) had proliferative rethinopathy, 7 (18%) macroalbuminuria and 18 (47%) microalbuminuria. ResultsAll surgical incisions healed uneventfully. Twenty-five (93%) of the toe ulcers healed in median 21 days (range 7–224 days). Three patients had recurrence of the ulcer. There were no infections in the incisions or toe amputations. No patients treated with preventive tenotomy experienced toe ulceration. No complications were recorded in neuro-ischaemic ulcers. During the follow up period of median 31 months (range 2–48 months) 33 other ulcers were recorded in 18 patients (47%). One of these developed a transfer ulceration under the adjacent metatarso-phalangeal joint and another had a late pressure ulcer on a neighbouring toe. The other 31 ulcers were not related to ulcers treated with tenotomy. ConclusionTenotomy is a simple, safe and effective procedure for preventing and treating distal plantar neuropathic toe ulcers in claw toe or hammer toe deformities in people with diabetes with or without serious co-morbidity. The results suggest that tenotomy should be considered also in neuroischaemic ulcers.

Performance of a knotless four-strand flexor tendon repair with a unidirectional barbed suture device: a dynamic ex vivo comparison

With increased numbers of reports using barbed sutures for tendon repairs we felt the need to design a specific tendon repair method to draw the best utility from these materials. We split 30 sheep deep flexor tendons in two groups of 15 tendons. One group was repaired with a new four-strand barbed suture repair method without knot. The other group was repaired with a conventional four-strand cross-locked cruciate repair method (Adelaide repair) with knot. Dynamic testing (3-30 N for 250 cycles) and additional static pull to failure was performed to investigate gap formation and final failure forces. The barbed suture repair group showed higher resistance to gap formation throughout the test. Additionally final failure force was higher for the barbed suture group compared with the conventional repair group. When used appropriately, barbed suture materials could be beneficial to use in tendon surgery, especially with regard to early loading of the repair site and gap formation.

Emergent Tendon Transfer in Hand Trauma: A Case Report

In this report we describe our encounter of a case of hand trauma referred to our center presenting with incomplete left thumb amputation at metacarpal level with extensor pollicis longus (EPL) and flexor pollicis longus (FPL) tendon avulsion from the tenomuscular junction. After metacarpal bone fixation the ulnar digital artery was anastomosed and the digital nerves were coapted. Transfer of extensor indicis proprius (EIP) to EPL and side-to-side suturing of the FPL to the deep flexor tendon of the index finger were performed.

Effect of Lactoferrin Peptide (PXL01) on Rabbit Digit Mobility After Flexor Tendon Repair

Restoration of digital function after flexor tendon injuries remains a clinical challenge. Complications such as adhesion formation and tendon rupture can lead to limited hand function. The aim of this study was to compare the effects of the lactoferrin-derived peptide, PXL01, formulated in sodium hyaluronate (SH), with SH alone on joint mobility as an indirect measure of postsurgical adhesion prevention and healing strength of the tendon and to elucidate the most optimal concentration of PXL01. Using a rabbit flexor tendon repair model, in which the deep flexor tendon was fully transected and repaired, PXL01 in SH or SH alone was administered between the repaired tendon and the tendon sheath before closure of the surgical wound. Three concentrations of PXL01 in SH (5, 20, or 40 mg/mL) were compared to determine the lowest effective concentration. The repaired tendons were evaluated 7 weeks after surgery by measuring the proximal interphalangeal joint mobility by full range of flexion assessment and the tendon repair strength. Treatment with PXL01 formulated in SH resulted in improved mobility of the proximal interphalangeal joint with an average of 10°, corresponding to improvement of approximately 25% to 60% of the flexion of nonoperated toes at the different measuring points compared with SH alone. The difference was statistically significant in 5 out of 6 measuring points (0.5, 1, 2, 3, and 4 N; P < .05). The dose-response study indicated that the lowest effective concentration of PXL01 was 20 mg/mL. There was no difference in healing strength of the tendon between the groups as assessed by load-to-failure breaking strength. PXL01 in SH significantly improved the mobility compared with the carrier SH alone, without any negative effect on healing strength, and PXL01 at 20 mg/mL was the lowest effective concentration. The result provides a valuable basis for a clinical trial to assess efficacy and safety of PXL01 in clinical hand surgery.

Biomechanical assessment of a novel tendon junction

The Pulvertaft weave has been the standard tendon junction technique used both in tendon transfers and tendon grafts. A limitation of this repair is the sequential failure of stabilizing sutures, rather than the tendon. A novel loop weave is described and compared with the Pulvertaft weave in biomechanical performance. Ovine deep flexor and extensor tendons were used to simulate Pulvertaft or loop weaves (n = 11) for tensile testing. The Pulvertaft weaves failed at the stabilizing sutures, whereas the loop weaves repairs failed by longitudinal splitting of the motor tendon. The loop weave demonstrated significantly higher mean initial failure and ultimate strengths. Tensile loads required to elongate the loop weave by 4, 6, and 8 mm were significantly higher, while more displacement was associated with the Pulvertaft repair under the application of 50, 75, and 100 N tensile loads. This study demonstrates favourable biomechanical characteristics of the new loop weave technique.

Synovial hemangioma in an adult horse

A 15-year-old gelding presented with a progressive lameness of the left forelimb of 2.5 months duration. Clinically, a dilation of the deep flexor tendon sheath with a firm elastic consistency and a pronounced tenderness was noted. Ultrasonically, a marked swelling of the flexor tendon sheath with an irregular density of the mesotendineum was observed. The white, firm material forming a nodular distension of the flexor tendon sheath with a diameter of approximately 1 cm was excised and sent for histopathological examination. Biopsies of the deep flexor tendon and corresponding tendon sheath were sent for histopathological evaluation. Histologically, the mass consisted of clefts and numerous anastomosing vascular channels extending between the collagen fibers of the deep flexor tendon. These capillary-like spaces were lined by neoplastic cells that were flattened to polygonal and contained few erythrocytes. There was 0 to 1 mitotic figure per 10 high power fields (400×). Immunohistochemically, the neoplastic cells stained positive for vimentin and factor VIII-related antigen. Adjacent to the neoplastic endothelial cells located pericytes expressed α-smooth muscle actin antigen. Based on the histopathological and immunohistochemical features, synovial hemangioma was diagnosed. One year after surgery, the horse has shown no lameness.

Prospective Morphologic and Dynamic Assessment of Deep Flexor Tendon Healing in Zone II by High-Frequency Ultrasound: Preliminary Experience

The purpose of this article is to prospectively evaluate early postoperative morphologic and functional changes after deep flexor tendon repair in zone II using ultrasound and to correlate findings from ultrasound with the clinical outcome. Ten patients (mean age, 34 years; range, 19-55 years) with 11 injured deep flexor tendons of the hand underwent surgical tendon repair. Postoperative tendon morphology was assessed with gray-scale and power Doppler ultrasound over a period of 3 months. Tendon excursion over the proximal interphalangeal joint was assessed by sonographic scar tracking. Correlation of ultrasound findings with clinical outcome was performed. Almost all repaired tendons exhibited a spindlelike shape after 1 week, of which 50% developed a normal shape after 12 weeks. A persisting spindlelike shape over 3 months was associated with a significantly increased tendon excursion (p < 0.05) and a trend toward better active motion of the fingers (p = 0.056). Tendons with increased power Doppler signal showed a significantly better tendon excursion and active motion after 12 weeks (all p < 0.05). Tendon excursion measurements obtained by scar tracking showed excellent correlation (r = 0.84; p < 0.05) with total active finger motion. Preliminary data of this study indicate a better clinical outcome if a sutured tendon maintains a spindlelike shape and increased power Doppler signal. This might indicate a predominantly intrinsic healing pattern with reduced adhesion formation. Ultrasound morphology, power Doppler signal, and tendon excursion may be helpful tools to rate tendon healing and to establish individually modified rehabilitation protocols.

Biomechanical responses of different rat tendons to nandrolone decanoate and load exercise

Androgenic-anabolic steroids (AAS) have been associated with an increased incidence of tendon rupture. The aim of this study was to compare the biomechanical properties of the rat calcaneal tendon (CT), superficial flexor tendon (SFT), and deep flexor tendon (DFT), and to determine the effect of jump training in association with AAS. Animals were separated into four groups: sedentary, trained, AAS-treated sedentary rats (AAS), and AAS-treated and trained animals. Mechanical testing showed that the CT differed from the DFT and SFT, which showed similar mechanical properties. Jump caused the CT to exhibit an extended toe region, an increased resistance to tensional load, and a decreased elastic modulus, characteristics of an elastic tendon capable of storing energy. AAS caused the tendons to be less compliant, and the effects were reinforced by simultaneous training. The DFT was the most affected by training, AAS, and the interaction of both, likely because of its involvement in the toe-off step of jumping, which we suggest is related to the rapid transmission of force as opposed to energy storage. In conclusion, tendons are differently adapted to exercise, but responded equally to AAS, showing reduced flexibility, which is suggested to increase the risk of tendon rupture in AAS consumers.

Minimally Invasive Management of Dorsiflexion Contracture at the Metatarsophalangeal Joint and Plantarflexion Contracture at the Proximal Interphalangeal Joint of the Fifth Toe

Several surgical options have been described to manage persistent dorsiflexion contracture at the metatarsophalangeal joint and plantarflexion contracture at the proximal interphalangeal joint of the fifth toe. We describe a minimally invasive technique for the management of this deformity. We perform a plantar closing wedge osteotomy of the 5th toe at the base of its proximal phalanx associated with a lateral condylectomy of the head of the proximal phalanx and at the base of the middle phalanx. Lastly, a complete tenotomy of the deep and superficial flexor tendons and of the tendon of the extensor digitorum longus is undertaken. Correction of cock-up fifth toe deformity is achieved using a minimally invasive approach.

Gene expression in distinct regions of rat tendons in response to jump training combined with anabolic androgenic steroid administration

The aim of this study was to evaluate the expression of key genes responsible for tendon remodeling of the proximal and distal regions of calcaneal tendon (CT), intermediate and distal region of superficial flexor tendon (SFT) and proximal, intermediate and distal region of deep flexor tendon (DFT) submitted to 7weeks of jumping water load exercise in combination with AAS administration. Wistar male rats were grouped as follows: sedentary (S), trained (jumping water load exercise) (T), sedentary animals treated with AAS (5mg/kg, twice a week) and animals treated with AAS and trained (AAST). mRNA levels of COL1A1, COL3A1, TIMP-1, TIMP-2, MMP-2, IGF-IEa, GAPDH, CTGF and TGF-β-1 were evaluated by quantitative PCR. Our main results indicated that mRNA levels alter in different regions in each tendon of sedentary animals. The training did not alter the expression of COL1A1, COL3A, IGF-IEa and MMP-2 genes, while AAS administration or its combination with training reduced their expression. This study indicated that exercise did not alter the expression of collagen and related growth factors in different regions of rat tendon. Moreover, the pattern of gene expression was distinct in the different tendon regions of sedentary animals. Although, the RNA yield levels of CT, SFT and DFT were not distinct in each region, these regions possess not only the structural and biochemical difference, but also divergence in the expression of key genes involved in tendon adaptation.

Kinetics of Crimp and Slope Grip in Rock Climbing

The aim was to investigate differences of the kinetics of the crimp and the slope grip used in rock climbing. Nine cadaver fingers were prepared and fixated with the proximal phalanx in a frame. The superficial (FDS) and deep (FDP) flexor tendons were loaded selectively and together with 40 N in the crimp grip (PIP joint flexed 90°/DIP joint hyperextended) and the slope grip position (<25° flexed/50° flexed respectively). Five different grip sizes were tested and the flexion force which was generated to the grip was measured. In the crimp grip the FDP generated more flexion force in small sized holds whereas the FDS generated more force in the larger holds. During the slope grip the FDP was more effective than the FDS. While both tendons were loaded, the flexion force was always greater during crimp grip compared with the slope grip. The FDP seems to be most important for very small holds using the crimp grip but also during slope grip holds whereas the FDS is more important for larger flat holds.