In vivo non-contact regions of proximal scaphoid in six extreme wrist positions.

INTRODUCTION: Fractures of the scaphoid are the most common carpal injuries, account for 80-90% of all carpal fractures. 5-15% nonunion of scaphoid fractures were reported even with adequate primary treatment, which probably progresses to osteoarthritic changes several decades later. Researches regarding to scaphoid physiological characteristic in vitro and in vivo and kinds of trials in clinical practice are being kept on going, which contribute much to our clinical practice. With the advancing wrist arthroscopy, 3D-print patient-specific drill guide, and intraoperative fluoroscopic guidance, dorsal approach (mini-invasive and percutaneous technique) is being popular, through which we can implant the screw in good coincidence with biomechanics and with less disturbing tenuous blood supply of the scaphoid. Investigating the noncontact area of the dorsal proximal scaphoid in different wrist positions can facilitate preoperatively estimating insert point of the screw. MATERIALS AND METHODS: Eight volunteers were recruited to accept CT scans in six extreme wrist positions. The images of DICOM mode were imput into the Mimics analytical system, the segmented scaphoid, lunate and radius were exported in mode of ASCII STL and were opened in the software of Geomagic studio. We created four planes based on anatomic markers on the surface of the radius and scaphoid to confine the proximal scaphoid to form the so-called non-contact regions. We measured and compared the areas in six targeted positions. RESULTS: Amidst six extreme wrist positions, area of the non-contact region in extreme dorsal extension (59.81 ± 26.46 mm2) was significantly the smallest, and it in extreme palmar flexion significantly was largest (170.51 ± 30.44 mm2). The non-contact regions increased in order of dorsal extension, supination, ulnar deviation, radial deviation, pronation and palmar flexion. As for two-group comparison, the non-contact region showed significantly larger (p < 0.05) in palmar flexion than the others except for in pronation individually, and in radial deviation (p < 0.05) than in dorsal extension. CONCLUSIONS: Sufficient space was available for the screw started from the dorsal approach despite the wrist positions.

Functional reconstruction of severe hand injuries using allogeneic tendons: a retrospective study.

OBJECTIVE: To evaluate the effectiveness and safety of allogeneic tendons for functional reconstruction of severe hand injuries. METHODS: From August 2007 to July 2014, we performed functional reconstruction with tendon allografts for severe hand injuries affecting two or more tendons. At the final follow-up, we assessed total active motion (TAM); pincer pinch strength; grip strength; Disabilities of the Arm, Shoulder, and Hand (DASH) score; degree of satisfaction; and adhesion. We measured the white blood cell count, C-reactive protein concentration, erythrocyte sedimentation rate, total T-cell count, and CD4+T/CD8+T ratio to evaluate the immune response and check for infection. RESULTS: Ten patients received 26 allogeneic tendons to reconstruct hand function. The average follow-up period was 50.0 months (range, 24-82 months). The TAM was 126.4° (12°-253°), pincer pinch strength was 0.83 kg (0-4.5 kg), and grip strength was 13.69 kg (4-41.5 kg). The DASH score was 14.25 (3.3-30.8), and seven and three patients were satisfied and partially satisfied, respectively. One patient developed tendon adhesion. All immune and infectious parameters were within the reference range. CONCLUSION: Functional reconstruction using allogeneic tendons for severe hand injuries with multiple tendon defects was effective and safe; however, more research is needed.

Medial versus lateral approach to harvesting of anterolateral thigh flap.

OBJECTIVE: This study was performed to evaluate two classic procedures guided by anatomic markers for harvesting the anterolateral thigh (ALT) flap: one began with an incision on the lateral side to identify perforators emerging from the muscle to the superficial tissue and to track the perforators upward to the upper stem vessel, and the other began with an incision on the medial side to identify the vessel branch from the stem artery and to track it downward to the flap perforators. METHODS: Twenty-eight consecutive patients with tissue defects repaired with ALT flaps were investigated; 13 and 15 patients underwent the lateral and medial incision technique, respectively. The surgeon's subjective view regarding procedural difficulty and the operative times were statistically analyzed. RESULTS: All flaps were harvested successfully. A two-paddle flap from one thigh in the medial group failed due to necrosis; all others survived completely. Subjectively, harvesting of flaps starting with a lateral incision was somewhat difficult, and the operative time was significantly longer using the lateral technique. CONCLUSIONS: Classic procedures to harvest the anterolateral thigh flap are still practicable, and starting with a medial incision is more efficient than starting with a lateral incision. Type of study/level of evidence: Therapeutic IV.

In Vivo Contact Characteristics of Distal Radioulnar Joint With Malunited Distal Radius During Wrist Motion.

PURPOSE: To determine whether distal radioulnar joint (DRUJ) contact characteristics were altered in patients with malunited distal radius fractures. METHODS: We obtained computed tomography scans at 5 positions of both wrists of 6 patients who had unilateral malunited distal radius fractures with dorsal angulation from 10° to 20° and ulnar variance less than 3 mm. We reconstructed 3-dimensional images and mapped contact regions of DRUJ by calculating the shortest distance between the 2 opposing bones. The contact areas of the DRUJ were measured and the contact region centers were calculated and analyzed. The values of the malunited side were compared with those of the contralateral uninjured side. RESULTS: In the uninjured wrist, the contact areas of the DRUJ increased slightly from wrist flexion to extension and ulnar deviation. In the malunited wrist, we found the contact areas of DRUJ to be progressively reduced from 20° flexion to neutral, 40° extension, and 20° extension, to ulnar deviation. The centroid of this area on the sigmoid notch moved to distal from flexion to extension. Compared with the contralateral uninjured wrist, the contact area significantly decreased during wrist extension and ulnar deviation, and significantly increased during wrist flexion. The centroids of this area on sigmoid notch all moved volarly in all selected wrist positions. CONCLUSIONS: The contact areas of the DRUJ and the centroid of contact area on sigmoid notch are altered in patients with malunited distal radius fractures. The contact area of the DRUJ increases during wrist flexion and decreases during wrist extension and ulnar deviation. The centroids of the contact area on sigmoid notch move volarly during wrist flexion-extension and ulnar deviation. CLINICAL RELEVANCE: The in vivo findings suggest that alterations in joint mechanics may have an important role in the dysfunction associated with these injuries.

Allograft tendon for second-stage tendon reconstruction.

Tendons are made of compact dense collagen fibers with only sparse cellularity and naturally low immunogenicity. Allogenic tendons may be preserved through deep freezing methods and retain excellent mechanical properties after revitalization. Allogenic tendons were used in 22 patients (30 tendons) for second-stage tendon reconstruction in the hand. Preliminary results indicate no observable adverse tissue reactions, and functional recovery after tendon grafting does not seem different from reconstruction using tendon autografts. This type of allogenic graft does not seem to produce serious concern as a foreign tissue in the body, at least in the short term.

In vivo length and changes of ligaments stabilizing the thumb carpometacarpal joint.

PURPOSE: To investigate the lengths and changes of selected ligaments stabilizing the thumb carpometacarpal (CMC) joint during thumb motion in vivo. METHODS: We obtained serial computed tomography scans of the thumb CMC joints of 6 healthy volunteers during thumb flexion, abduction, and opposition. We reconstructed the 3-dimensional structures of the bones of the thumb CMC joint using customized software and modeled the paths of fibers of 5 principal ligaments--deep anterior oblique (beak), dorsoradial, posterior oblique, intermetacarpal, and dorsal intermetacarpal--at each of the CMC joint positions studied. We estimated the virtual lengths of these ligaments in neutral position, flexion, abduction, and opposition of the CMC joint by measuring the distances between the origin and the insertion of individual ligaments, and statistically analyzed the length changes. RESULTS: The estimated length of the CMC joint ligaments underwent significant changes during thumb motion in vivo. Thumb flexion led to the greatest changes in ligament lengths. During flexion, all the ligaments lengthened significantly (p < .05 or p < .01), except for the beak ligament, which shortened significantly (p < .001). The lengths of the ligaments changed similarly during thumb abduction and opposition, except for the dorsoradial ligament. In both motions, the posterior oblique and dorsal intermetacarpal ligaments lengthened and the beak ligament shortened significantly (p < .05 or p < .01). During the 3 thumb motions, the beak ligament underwent marked shortening, while the other measured ligaments lengthened to varied extent. CONCLUSIONS: The estimated lengths of principal ligaments stabilizing the CMC joint change substantially during thumb motions in vivo. Thumb flexion causes the greatest changes of the ligament lengths; abduction and opposition result in similar changes in the ligament lengths. The beak ligaments shorten while the other ligaments lengthen. This in vivo study suggests that thumb motions expose the CMC joint ligaments to different tensions at these thumb positions, and that the ligaments are under lower tension during thumb opposition and abduction than during flexion.

Scaphoid and lunate movement in different ranges of carpal radioulnar deviation.

PURPOSE: We aimed to investigate scaphoid and lunate movement in radial deviation and in slight and moderate ulnar deviation ranges in vivo. METHODS: We obtained computed tomography scans of the right wrists from 20° radial deviation to 40° ulnar deviation in 20° increments in 6 volunteers. The 3-dimensional bony structures of the wrist, including the distal radius and ulna, were reconstructed with customized software. The changes in position of the scaphoid and lunate along flexion-extension motion (FEM), radioulnar deviation (RUD), and supination-pronation axes in 3 parts--radial deviation and slight and moderate ulnar deviation--of the carpal RUD were calculated and analyzed. RESULTS: During carpal RUD, scaphoid and lunate motion along 3 axes--FEM, RUD, and supination-pronation--were the greatest in the middle third of the measured RUD (from neutral position to 20° ulnar deviation) and the smallest in radial deviation. Scaphoid motion along the FEM, RUD, and supination-pronation axes in the middle third was about half that in the entire motion range. In the middle motion range, lunate movement along the FEM and RUD axes was also the greatest. CONCLUSIONS: During carpal RUD, the greatest scaphoid and lunate movement occurs in the middle of the arc--slight ulnar deviation--which the wrist frequently adopts to accomplish major hand actions. At radial deviation, scaphoid and lunate motion is the smallest.

[Kinematics of the triangular fibrocartilage complex during forearm rotation in vivo].

OBJECTIVE: To investigate three-dimensional kinematics of the superficial and deep portion of triangular fibrocartilage complex (TFCC) in different parts of the forearm rotation. METHODS: Six wrists of 6 volunteers were used to obtain CT scans at different positions of the wrist. The wrists were scanned from 90 degrees of pronation to 90 degrees of supination at an interval of 30 degrees. The 3-dimensional radius and ulna were reconstructed with customized software and changes in length of the superficial and deep portion of TFCC during forearm rotation. RESULTS: In forearm pronation, the superficial dorsal portion and the deep palmar portion of the TFCC were tight. While the superficial palmar portion and the deep dorsal potion of the TFCC were lax. In supination, the changes in length of all these fibers were reverse. CONCLUSIONS: In forearm rotation one portion fibers of dorsal TFCC and one portion fibers of palmar TFCC are tight, and this mechanism controls stability during DRUJ rotation.

[Measurements of parameters of posteroanterior X-ray films of distal radial fracture and their significance].

OBJECTIVE: To provide the basic knowledge of wrist joint for diagnosing of these morphological change in pathological condition by measuring the posteroanterior X-ray films of different types of distal radius fracture by AO classification. METHODS: Eleven radiographic indexes were measured including following 7 new parameters of 83 cases of distal radius fracture: ulnar styloid length (USL), ulnar head length (UHL), ulnar head diameter (UHD), maximal distal radius width (MDRW), proximal distal radius width (PDRW), sigmoid notch length (SNL) and sigmoid notch width (SNW) by Pacs system in standard X-ray films. The indexes were defined by the ratio of these parameters to the length of the third metacarpal. Statistical significance of indexes and correlations of parameters were analyzed by SPSS 16.0. RESULTS: It was found that indexes of 11 parameters and 27 pairs of indexes had significantly different. Compared the indexes of 14 groups with normal group existed statistical significance, 62 pairs value of 11 parameters had correlations. CONCLUSION: The study provides additional radiographic index that will be helpful to more careful diagnosis and treatment of the distal radius fractures and their associated injuries such as ulnar wrist injuries or carpal instability.

A2 pulley incision or one slip of the superficialis improves flexor tendon repairs.

Outcomes of flexor tendon repairs in the area covered by major pulleys are often unpredictable. We performed an in vivo study to investigate biomechanical effects of pulley incision, Kapandji pulley plasty, excision of one slip of the flexor digitorum superficialis, or closure of the incised pulley on function of the profundus tendons. Both long toes (104 total) of 52 leghorn chickens were divided into four experimental groups and one control group. The pulley and flexor digitorum superficialis tendon were subjected to the above-mentioned treatments in four groups, with 22 toes per group, after tendon transection in the A2 pulley area. Eight weeks after surgery, incision of the pulley improved excursion of the flexor digitorum profundus tendon and decreased the work of digital flexion over pulley closure. Resection of the one slip of the flexor digitorum superficialis tendon had results similar to pulley incision. Kapandji pulley plasty did not increase tendon excursion and decrease the work compared with a simpler pulley incision. Adhesions were more severe with pulley plasty or closure than with pulley incision. In this avian model, incision of the pulley or partial flexor digitorum superficialis resection improved outcomes of tendon repairs compared with pulley closure. Kapandji pulley plasty did not improve the outcomes over a simple pulley incision.

Influence of core suture purchase length on strength of four-strand tendon repairs.

PURPOSE: Recently the length of core suture purchase has been identified as a variable affecting the strength of tendon repairs. The influence of the length of the core suture purchase on the strength of multistrand locking and grasping suture repairs, however, has not been studied extensively in transversely lacerated tendons. We assessed the effects of the length of the core suture purchase on the strength of three 4-strand grasping or locking repair techniques. METHODS: Seventy-four fresh adult pig flexor tendons were cut transversely and repaired with 1 of 3 methods: double-modified Kessler, locking cruciate, and modified Savage. Each method was assessed using 2 different lengths of core suture purchase (1.0 and 0.4 cm). The tendons were subjected to a linear noncyclic load-to-failure test in a tensile testing machine. We recorded the forces required for gap formation, ultimate strength, stiffness of the tendon, and the mode of repair failure. RESULTS: The resistance to gap formation, the ultimate strength of all 3 repairs, and the stiffness of the tendons with the double-modified Kessler and modified Savage repairs decreased significantly as the length of core sutures decreased from 1.0 to 0.4 cm. Locking and grasping repairs had a similar decrease in strength when the purchase was decreased from 1.0 to 0.4 cm. All tendons with modified Savage repairs with 1.0-cm purchase failed by suture breakage and tendons with 0.4-cm purchase failed predominantly by pullout. CONCLUSIONS: The length of core suture purchase significantly affects the strength of these 4-strand tendon repairs. The forces required for gap formation and the ultimate failure of repairs with 0.4-cm purchase were 20% to 45% lower than those of the repairs with 1.0-cm purchase. Locking repairs did not show a greater capacity to offset the decrease in strength than grasping repairs when the length of core suture purchase was decreased from 1.0 to 0.4 cm. Our study indicates that the length of suture purchase directly influences the strength of both locking and grasping core tendon repair methods.

Core suture purchase affects strength of tendon repairs.

PURPOSE: It generally is considered that a certain distance should be maintained between the site of the tendon-suture junction and the laceration level of the tendon. In this study we assessed how the length of core suture purchase may affect the repair strength of transversely cut tendons using a 2-strand modified Kessler method and a 4-strand circle-locking method. METHODS: Seventy-four fresh pig flexor tendons were transected. Fifty-eight tendons were divided into 4 groups and repaired with a 2-strand grasping repair technique with the core suture purchase in the tendon stump ranging from 0.4 to 1.2 cm. Sixteen tendons were repaired with a 4-strand circle-locking tendon-suture repair technique. The core suture purchase of these tendons was 0.4 and 1.0 cm, respectively. The tendons were subjected to a linear, noncyclic, load-to-failure test in a tensile testing machine. The forces measured for initial gap formation, 2-mm gap formation, and ultimate strength were recorded for each repair. RESULTS: The resistance to gap formation and ultimate strength of 2-strand grasping technique repairs increased significantly as the suture purchase increased from 0.4 to 0.7, 1.0, and 1.2 cm although strength remained constant from 0.7 to 1.2 cm. The strength of 4-strand circle-locking repairs with a suture purchase of 1.0 cm was statistically greater than that of the repairs with a suture purchase of 0.4 cm. CONCLUSIONS: For both the 2-strand grasping and 4-strand circle-locking repair methods, the length of core suture purchase significantly influences the resistance to 2-mm gap formation and the ultimate strength of repairs in transversely lacerated flexor tendons. We determined that the optimal length of purchase is between 0.7 and 1.0 cm and that increased length of purchase from 0.7 to 1.2 cm does not increase the strength of the repair. Core suture purchase length of 0.4 cm or less results in significantly weaker repairs.

Effects of locking area on strength of 2- and 4-strand locking tendon repairs.

PURPOSE: The area of the tendon within the locking suture configuration of the modified Pennington repair is an important determinant of eventual tendon strength. This 2-strand repair's loop configurations encompass a large cross-sectional area of the tendon. Many recently proposed repairs, however, consist of locks in a number of narrow sites on the tendon surface and most are multistranded. It is not clear how the area within the locks affects tendon strength and whether the effects of locking areas change according to the number of repair strands. In this study we investigate the effects of locking area on repair strength of 2- and 4-strand tendon repairs. METHODS: Sixty-five fresh pig flexor tendons were divided equally into 6 groups and were transected completely. They were repaired with 2- or 4-strand techniques. The tendon-suture interface was a circle-locking junction and diameters of the locks were 1, 2, or 3 mm. The tendons were pulled in a tensile testing machine until failure of the repair and the mode of failure, 2-mm gap force, and ultimate strength were measured. RESULTS: In the tendons with either 2- or 4-strand repairs locks with a diameter of 2 or 3 mm had significantly greater gap formation force and ultimate strength than those of 1 mm. The gap formation and ultimate forces were not statistically different between tendons with locks of 2 or 3 mm in diameter. CONCLUSIONS: In both the 2- and 4-strand tendon repairs tested in this study repair strength increased as the diameter of locks of the repair increased from 1 mm to 2 or 3 mm. An increase in the diameter from 2 mm to 3 mm, however, did not increase the gap force and ultimate strength. These findings indicate that the cross-sectional area within the locks affects repair strength when the diameter of the locks is within a certain range (2 mm) and that further enlargement of the locking area does not increase strength.

Investigation of locking configurations for tendon repair.

PURPOSE: Locking sutures have proven beneficial to the strength of the repaired tendon. In this study we investigated the effects of 3 locks in the tendon-suture junction and their effect on repair strength. METHODS: Forty-seven fresh pig flexor tendons were transected and repaired using 4-strand repairs with 3 different configurations of locks in each tendon-suture junction: 1 exposed cross-lock, 1 embedded cross-lock, and 1 circle lock. The tendons were subjected to a linear noncyclic load-to-failure test using a tensile testing machine. The initial gap, the 2-mm gap force, and the ultimate strength were measured to compare the biomechanical performance for each repair. RESULTS: Despite noticeable differences in the configurations of locks the gap formation force and ultimate strength were not significantly different among the 3 tested locking configurations. CONCLUSIONS: An exposed cross-lock, an embedded cross-lock, and a circle lock at tendon-suture junctions had similar locking power. Circle-lock repairs without cross-locking components produce tensile strength similar to cross-locking repairs. The findings of this study suggest that the creation of cross-configurations in locking repairs used conventionally by many surgeons is not essential to repair strength and that circle locking is as efficient as cross-locking in the repair of lacerated flexor tendons.

[Management of sheath after repair of double tendons in zone II d].

OBJECTIVE: To evaluate the management of sheath after repair of double tendons in clean-cut injury or severe injury in zone II d. METHODS: Forty-eight white leghorn chickens were divided into 4 groups. Both FDS and FDP tendons in zone II d of long toes were repaired with modified Kessler suture after tendon transection in group A (clean-cut tendon injury, sheath closure), group B (clean-cut tendon injury, sheath excision), group C (severe tendon injury, sheath closure) and group D (severe tendon injury, sheath excision), respectively. Biomechanical studies of gliding excursion and work of flexion were carried out 6 weeks and 12 weeks after tendon repair. The extent of adhesion was examined. RESULTS: After 6 and 12 weeks of repair, there were no significant differences in tendon excursion and work of flexion of the toes between groups A and B. Excursions of FDP tendons in group D was significantly larger than that in group C (P < 0.05). Work of flexion and extent of adhesion in group D was significantly less than that in group C (P < 0.05). CONCLUSION: The above results indicate that sheath can be closed after repair of both FDS and FDP tendons in clean-cut injury and that sheath should be excised in severe injury in zone II d.

[Proliferative ability of the central area tenocytes of flexor tendons in vitro].

OBJECTIVE: To study the healing ability of the central area tissue of flexor tendons after injury. METHODS: Tendons of flexor digitorum profundus of the long toes from 8 white Leghorn hens were harvested in zone II. Tissues were cut in 4 mm segments and divided into the experimental group (the central area tissue of flexor tendons) and the control group (the tendon segments without epitenon). There were 12 tendon segments cultured in each group. Specimens were obtained and examined under light microscope on the 9th, 18th and 27th days after culture, respectively. Another 4 tendons were used as normal control, and they were directly examined under light microscope. RESULTS: The number of tenocytes was significantly less in the control group than in the experimental group and the uncultured state (P < 0.01); the number of tenocytes was significantly higher in the experimental group than in the uncultured state (P < 0.01). The number of tenocytes of the experimental group were higher on the 9th day than on the 18th and 27th days after culture(P < 0.01). CONCLUSION: The central area tissue of flexor tendons has favorable healing ability after injury.