Reduced growth of intra- and infra-pyramidal mossy fibers is produced by continuous exposure to polychlorinated biphenyl.

Exposure to polychlorinated biphenyl (PCB) has been shown to produce cognitive deficits in both humans and laboratory animals. However, no study to date has identified long-term brain changes which could account for these problems. This study employed Timm's silver sulfide staining to visualize the hippocampal mossy fibers in Sprague-Dawley rats continuously exposed to either 125 ppm Aroclor 1254 or untreated control food beginning in utero. Reduced growth of hippocampal intra-and infra-pyramidal (II-P) mossy fibers were found in PCB treated rats compared to controls. Other measured hippocampal subdivisions remained relatively unaffected by PCB treatment, as did cortical thickness. The changes observed in hippocampal morphology in response to PCB exposure are the first to provide a potential explanation for at least part of the long-term PCB-induced cognitive deficits.

Biomechanical and histologic characteristics of canine flexor tendon repair using early postoperative mobilization.

The purpose of this experimental study was to evaluate the mechanical and histologic healing of flexor tendon repairs using an early active motion protocol. Three different flexor tendon repair techniques in zone II were used. Forty-seven lacerated canine flexor profundus tendons from 25 dogs were repaired and evaluated at 5, 10, and 21 days after surgery. Eight of 9 Kessler repairs ruptured at days 5 and 10. None of the 19 Savage repairs or the 19 dorsal tendon splint repairs ruptured; 3 of 19 dorsal tendon splint repairs failed owing to adhesions. Smooth tendon gliding was obtained in all specimens in which repair was successful. The gap strength values for both the Savage and dorsal tendon splint repairs improved significantly for day-21 specimens compared to day-5 or day-10 specimens. The ultimate tensile strength showed no reduction during the 3-week period of tendon healing for both repairs. Histologically, there was evidence of progressive healing without surrounding adhesions. The improved suture techniques have the potential to withstand the stress produced by active digital motion protocols.

Effect of suture knot location on tensile strength after flexor tendon repair.

This study investigated the effect of increased suture material within the flexor tendon repair site on tensile strength in a canine model after in vivo healing. Four-strand modified Savage suture repairs with the knots located either inside or outside the repair site were performed in dogs. The tendons were placed on a passive-motion protocol after surgery and were biomechanically tested at 1, 3, and 6 weeks of in vivo healing. The knots-outside technique initially was 1.14 kg stronger on load-to-failure testing. After 6 weeks of healing, the knots-inside tendons had equal tensile strength (3.91 +/- 0.50 kg [inside] vs 4.16 +/- 0.66 kg [outside]). Relative tensile strength compared to initial strength showed an increase of 20% for the knots-outside technique and an increase of 67% for the knots-inside technique after 6 weeks. Suture material within the repair site did not have any deleterious effects on tensile strength and may stimulate tendon healing.

Cyclic stress testing after in vivo healing of canine flexor tendon lacerations.

This study evaluated the effects of cyclic tension applied to lacerated and repaired canine flexor tendons after various periods of in vivo healing for up to 30 days. Final gaps obtained after cyclic stress testing were found to increase from a baseline of 0.75 +/- 0.17 mm (zero time controls) to a maximum of 1.14 +/- 0.24 mm at 3 days after repair, before returning to baseline at 10 days (0.63 +/- 0.27 mm). Gap formation at 30 days after repair (0.65 +/- 0.27 mm) was similar to that of control tendons. This canine study suggests that continued protection of flexor tendons from strong repetitive tensile, stress should extend at least through 30 days after repair.

Mechanical properties of various circumferential tendon suture techniques.

We evaluated the mechanical properties of six different circumferential tendon sutures with a variable number of suture strands. Seventy-two human cadaver flexor profundus tendons were cut and repaired using only a 6/0 polypropylene circumferential suture. The six running suture techniques were: Simple; Simple-locking; Lembert; Halsted; Cross-stitch; Lin-locking; using 10, 14 and 18 suture passes. The increased suture passes increased both tensile and gap strengths. The tensile strength of the Lin-locking technique (29 to 63 N) was significantly stronger than the others, followed by Cross-stitch (27 to 38 N), Halsted (21 to 27N), Lembert (20 to 27N), Simple (11 to 22 N) and Simple-locking (10 to 17 N). The gap strength values were between 3 to 14N, with no significant differences between the techniques. The resistance to gliding, as measured by work of flexion, was not affected by the number of strands. However, the Lin-locking significantly increased the resistance to gliding (33-36%) compared to the other techniques (6-21%); there were no significant differences between these five techniques.

Effect of motion and tension on injured flexor tendons in chickens.

This study was undertaken to evaluate the individual effects of motion and tension on the healing response of injured flexor profundus tendons in chickens. Partial midsection transverse lacerations of the profundus tendons were produced in 53 chickens. Postoperatively, they were assigned randomly to four management groups: both motion and tension; only motion, no tension; no motion, only tension; no motion and no tension. Biomechanical results at 4 weeks showed that breaking strength significantly increased with both motion and tension, significantly decreased with neither, and was intermediate with only motion or only tension. Histologic evaluation generally showed the greatest cellular activity with both motion and tension, the least with neither, and an intermediate response with one or the other alone. Collagen fiber staining was increased primarily in the tension groups. The finding that both motion and tension enhance the tendon's response to injury encourages the development of active mobilization protocols following tendon repair.

Work of flexion after flexor tendon repair according to the placement of sutures.

Tendon repairs comparing dorsal or volar placement of sutures were done on 36 flexor profundus tendons from 9 canine cadaveric paws. Three suture techniques were used. Work of flexion as a measure of resistance to tendon gliding was measured in the following groups: Groups 1 and 2: 4-strand Savage technique with 5-0 core suture, dorsal or volar placement; Groups 3 and 4: 4-strand Savage technique with 4-0 core suture, dorsal or volar placement; and Groups 5 and 6: tendon splint technique, dorsal or volar placement. The increase in work of flexion values were 11.3%, 14.1%, 12.2%, 37%, 20.5%, and 92.7% for Groups 1 through 6, respectively. The increase in work of flexion value in Group 4 was significantly greater than that in Group 3, and the value in Group 6 was significantly greater than Group 5. These data suggest that the work of flexion after tendon repair was influenced by the location of the suture material; volar location of suture material significantly increased the work of flexion value.

Effects of dopamine D1 and D2 receptor antagonists on cocaine-induced place preference conditioning in preweanling rats.

The effects of dopamine D1 and D2 receptor antagonists on the reward processes of 10- and 17-day-old rats were assessed using the conditioned place preference paradigm. Conditioning and testing were conducted in a three-compartment chamber, with each end compartment having its own distinct tactile and odor cues (almond and lemon). During six experiments, 10- and 17-day-old rats (age at initial conditioning) were injected intraperitoneally with either saline, the dopamine D1 receptor antagonist R(+/-)-SCH 23390 hydrochloride (0.01-1.0 mg/kg), or the dopamine D2 receptor antagonists (+/-)-sulpiride (1-100 mg/kg) or S(-)-eticlopride hydrochloride (0.1-0.5 mg/kg) 30 min prior to being injected with cocaine hydrochloride (20 mg/kg) or saline. After the latter injections, rats were immediately confined in the lemon-scented (nonpreferred) compartment for 30 min. On the alternate conditioning day, rats were injected with saline and confined in the almond-scented compartment. On the third day (i.e., the test day), rats were given saline and allowed free access to the entire chamber for 15 min. The results showed that the dopamine D1 receptor antagonist SCH 23390 blocked the cocaine-induced place preference conditioning of both 10- and 17-day-old rats. Surprisingly, the dopamine D2 receptor antagonists sulpiride and eticlopride blocked the place preference conditioning of 10-day-old rats, while leaving the 17-day-old rats unaffected. These results indicate that dopamine D1 receptors are critically involved in the reward processes of preweanling rats, but that the importance of dopamine D2 receptors changes across ontogeny.

Work of flexion after tendon repair with various suture methods. A human cadaveric study.

After flexor tendon repair there is often increased resistance to tendon gliding at the repair site, which is greater for techniques using increased suture strands or suture material. This increased "friction" may be measured as the "work of flexion" in the laboratory setting. Tendon repairs performed in zone 2 in human cadaver hands using the two strand Kessler, the lateral Becker, the six strand Savage, internal and dorsal tendon splint, or the external mesh sleeve techniques, had "work of flexion" measurements made both before and after the laceration and repair. The average increase in work of flexion was 4.8% for Kessler; 6.5% for Becker; 10.9% for Savage; 19.3% for the internal tendon splint, 16.2% for the dorsal tendon splint and 44.3% for the external mesh sleeve. The work of flexion was found to increase in direct proportion to the amount of suture material at the repair site.

Effect of cyclic tension on lacerated flexor tendons in vitro.

The effect of tension on tendon healing was evaluated in vitro using cyclic tension and no tension groups of chicken flexor digitorum profundus tendons and histologic and immunohistologic techniques. A Vitrodyne force-loading machine was used for application of cyclic tension on partially lacerated chicken flexor tendons in culture media. Laceration sites under cyclic tension after 14 days were covered by newly proliferated fibroblasts, aligned in the direction of tension. This new growth was much thicker than that seen in the no tension group at the same time interval. Procollagen synthetic activity began at 3 days of culture in both groups. At 21 days, newly formed fibroblasts in the cyclic tension group were stained positive more strongly at the surface layer than in the deeper layers. In the no tension group, the staining was primarily in the surface layer. Cyclic tension stimulated the intrinsic response of lacerated flexor tendons significantly more than no tension did by enhancing proliferation and migration of fibroblasts, as well as stimulating collagen synthesis.

Canine cadaveric study of flexor tendon repair using tendon splint: tensile strength and the work of flexion.

A total of 128 flexor tendon repairs in zone II were performed with various suture techniques using a canine cadaver model to determine the tensile strength, gap strength, and resistance to tendon gliding as measured by the work of flexion. The ultimate tensile strength in kilogram force (kgf) following tendon laceration and repair was the greatest after repair by the Savage technique (4.84 kgf) and the dorsal tendon splint technique (4.89 kgf), while the standard Kessler technique showed a strength of only 1.48 kgf. The greatest gap strength values were also obtained for the Savage and dorsal tendon splint techniques. The work of flexion increase was the greatest at 85.5% after repair using a mesh sleeve technique. While, the Savage and dorsal tendon splint techniques showed an increase of 24.3% and 25.1% with no significant difference compared to the other technique studied. Considering the values of these biomechanical parameters, we believe that the best flexor tendon repair techniques in the canine model are the Savage and dorsal tendon splint.

Effect of suture knots on tensile strength of repaired canine flexor tendons.

59 dog cadaver flexor digitorum profundus tendons were repaired with one or two knots inside or outside the tendon, using two, four and six suture strands. The ultimate tensile strength and gap strengths were compared. Locating the knots outside rather than within the tendon repair site showed significantly higher ultimate tensile strength for two, four, and six strand sutures. The strength was greater in one knot than in two knot sutures; the value of the six-strand suture using the one knot outside technique was the greatest. Similarly, increased gap strength was also obtained from the one-knot-outside technique. We concluded that the knots should be located away from the tendon repair site and there should be as few as possible.

Tendon repair using flexor tendon splints: an experimental study.

Mechanical strength of tendon repair using Dacron tendon splints across the laceration site were evaluated in human cadaver profundus tendons; the splints were placed both on the dorsal surface and internally within the tendon substance. Comparison was made to modified Kessler, Becker, and Savage repair techniques. Ultimate tensile strength was 2.55 kgf for the Kessler, 3.00 kgf for the Becker, 8.29 kgf for the Savage, 8.46 kgf for the internal tendon splint, and 8.10 kgf for the dorsal tendon splint; the Savage and both Tendon Splints techniques had significant higher tensile strength than the Kessler and Becker. Gap strength was 1.44 kgf for the Kessler, 2.22 kgf for the Becker, 2.45 kgf for the Savage, 2.05 kgf for internal tendon splint, and 3.15 kgf for the dorsal tendon splint. The dorsal tendon splint technique showed significant greater gap strength than the other four techniques. There was no significant difference in the magnitude of the gap during cyclic testing of these techniques; however, three of seven Kessler repairs failed and one of six Becker repairs failed. The results of these cadaver studies suggest that both tendon splint repair techniques are comparable to the Savage and may have sufficient strength to allow postoperative active motion against minimal resistance. Further in vivo testing is in order.

Computed tomography scanning with image reconstruction in evaluation of distal radius fractures.

Seventeen patients with 18 intraarticular distal radius fractures underwent computed tomography (CT) scanning and image reconstruction to evaluate their distal radius fractures. All patients were selected prospectively because of intraarticular extension and/or displacement of their fractures on pre- or post reduction plain films. Patients who were not surgical candidates for open reduction and internal fixation of their fracture were not included in the study. X-ray films and CT scans were viewed separately and in random order by a senior radiologist not familiar with the cases. Both x-ray films and CT scans readily showed extension of fracture lines into the radiocarpal joint, radial shaft, and the ulnar styloid, but CT scans were better than x-ray films at demonstrating fracture involvement of the distal radioulnar joint, the extent of articular surface depression, and the amount of comminution. Due to the cost, it is recommended that the test only be used for patients who are surgical candidates for open reduction and internal fixation or when more information about the extent of comminution and joint depression is required.

Distal humeral osteotomy for correction of posttraumatic cubitus varus.

Twelve patients with posttraumatic cubitus varus were treated by a laterally based closing wedge osteotomy of the distal humerus. Smooth crossed K-wires held the osteotomy. After a minimum follow-up of 2 years, a good or excellent result was obtained in 83% of patients as assessed by clinical and radiographic examination. All patients and families were satisfied with their cosmetic outcome. Correction of even severe cubitus varus deformities is obtained with this straightforward surgical technique. The overall complication and morbidity rate is acceptably low, which is important in a procedure performed primarily for cosmetic indications.

Lunotriquetral arthrodesis.

Lunotriquetral arthrodesis has been recommended for the treatment of disabling pain at the lunotriquetral joint after more conservative measures have failed. We retrospectively analyzed a series of 22 patients treated with a lunotriquetral arthrodesis for presence of fusion, method of fixation, duration of immobilization, carpal alignment, pain relief, and ability to return to work. Fixation with a Herbert screw supplemented with a Kirschner wire (K-wire) was superior to fixation with K-wires alone. Immobilization longer than 6 weeks was superior to immobilization less than 6 weeks. Combined use of a Herbert screw supplemented with a K-wire and immobilization longer than 6 weeks resulted in union in all patients, even when performed for nonunion after a prior attempted arthrodesis. Pain was improved in all patients; all patients who previously were working returned to work. Routine posteroanterior and lateral x-ray films often failed to adequately profile the arthrodesis site. We recommend using a Herbert screw supplemented with a K-wire for lunotriquetral arthrodesis and keeping the patient in a cast until fusion is documented, usually at least 8 weeks. Fluoroscopic spot views or tomograms are recommended to demonstrate bone fusion.

Communicating intraosseous ganglion of the lunate.

The authors describe a symptomatic intraosseous ganglion of the lunate communicating directly with the scapholunate joint. The communication was demonstrated by arthrography and computed tomography. This case is believed to be the first reported in which the communication was shown by arthrography. Demonstration of such a communication can obviate the need for further imaging to diagnose the lesion. A review of intraosseous ganglia of the hand and their treatment is presented.

Scaphocapitolunate arthrodesis.

Since 1985 scaphocapitolunate arthrodesis has been performed on 21 patients with either chronic incompetence of the scapholunate ligament or a scaphoid nonunion. The average age was 31 years; follow-up averaged 28 months. Eighty-six percent of the injuries involved workers' compensation. The operative procedure was done through a dorsal approach, with the use of autogenous bone grafting and Kirschner wire fixation. Eight-one percent healed after the primary procedure; one patient had a major infection. Range of motion averaged 35 degrees of extension, 30 degrees of flexion, 10 degrees of radial deviation, and 20 degrees of ulnar deviation. Grip strength averaged 70% of the uninvolved side. Pain was significantly reduced in 80% of the patients. Sixteen of 20 patients were able to return to work. Radiographic examination at final follow-up showed mild degenerative changes at the radiocarpal joint in two patients.

Shoulder arthrodesis in pediatric patients.

Shoulder arthrodesis was performed in 17 pediatric patients. Diagnoses included birth-related brachial plexus palsy (six patients), posttraumatic palsy (three patients), and residual paralysis after poliomyelitis (eight patients). The position of fusion was not as important as the stability gained by the patient. Excessive abduction or forward flexion should be avoided, however, because this can be cosmetically displeasing to patients.