Transfixation cast technique for arthrodesis of the distal interphalangeal joint of horses.

Surgical arthrodesis of the distal interphalangeal (DIP) joint by transfixation casting was used to salvage a three-year-old filly and a yearling filly that were chronically lame because of infection of the DIP joint for breeding. Unlike previously described techniques for arthrodesis of the DIP joint, the technique used did not require insertion of implants across the joint, which may have contributed to the successful outcome.

Double plate fixation for the management of proximal interphalangeal joint instability in 30 horses (1987-2015).

REASONS FOR PERFORMING STUDY: Double plate fixation has been reported in a small number of horses with comminuted fractures of the middle phalanx. There are no published reports using this technique in the management of other injuries that destabilise the proximal interphalangeal joint (PIJ), including biaxial palmar/plantar eminence fractures and disruption of the palmar/plantar soft tissue support structures of the PIJ. Furthermore, there is a paucity of information on the long-term prognosis for horses undergoing double plate fixation to manage destabilising injuries of the PIJ. OBJECTIVES: To document further the clinical use of double plate fixation for management of injuries to the PIJ resulting in palmar/plantar instability and compare these results with other methods of management. STUDY DESIGN: Retrospective case series. METHODS: The case records and radiographs of 30 horses with destabilising injuries to the PIJ treated by double plate fixation at Texas A&M University between 1987 and 2013 were analysed. Long-term follow-up information was obtained by telephone interview with the client or referring veterinarian. RESULTS: Thirty-one disruptive PIJ injuries were double plated in 30 cases. Twenty-nine of 30 horses were discharged from the hospital. The medial time for post operative external coaptation was 41 days. Long-term follow-up (>2 years) was available for 25 horses, of which 15 (60%) returned to useful function. Radiographic evidence of fracture healing and arthrodesis of the PIJ was evident in 28 (90%) repairs at 6 months following repair. CONCLUSIONS: The use of 2 abaxially placed dorsal plates for management of destabilising injuries to the PIJ results in a very good prognosis for survival and a reasonable prognosis for return to functional use.

Proximal interphalangeal joint arthrodesis using a combination plate-screw technique in 53 horses (1994-2003).

REASONS FOR PERFORMING STUDY: A method for proximal interphalangeal joint (PIP joint) arthrodesis that provides a stable fixation and minimal duration of cast support is evaluated retrospectively. OBJECTIVES: Evaluate the clinical use of a combined plate-screw method for PIP joint arthrodesis in a large number of horses. METHODS: The records of 53 horses undergoing PIP joint arthrodesis were reviewed. Arthrodesis was performed with a dorsally placed 3-, 4- or 5-hole narrow dynamic compression plate (DCP) with 2 transarticular cortex screws placed in lag fashion either side of the plate. Subject details, clinical presentation, radiographic findings, surgical technique, post operative treatment and complications were recorded. Long-term follow up (mean 3 years) was obtained for 46 horses. RESULTS: Arthrodesis procedures (n = 58) were performed on 53 horses with a DCP in combination with transarticular cortex screws placed in lag fashion. Conditions treated were osteoarthritis (OA) of the PIP joint, fracture of middle phalanx, PIP joint subluxation, subchondral cystic lesions and degenerative joint disease secondary to sepsis. Time of post operative cast application was 14 days. Overall 40/46 (87%) horses could be used as intended including 20/25 (81%) forelimb and 20/21 (95%) hindlimb arthrodeses. Twenty-three of 27 (85%) horses used for performance had successful outcomes. Complications included implant infection, cast sores and partial implant failure. CONCLUSIONS: PIP joint arthrodesis using a DCP and transarticular cortex screws placed in lag fashion provides a stable construct and short casting period with minimal complications. The prognosis for return to performance was excellent for horses treated with hindlimb PIP joint arthrodesis and good for forelimb arthrodesis. POTENTIAL RELEVANCE: Use of a combination technique for PIP joint arthrodesis allows a high proportion of horses with pastern joint disease to be returned to their athletic potential.

Oncogenic base substitution mutations in circulating leukocytes of normal individuals.

The background frequency of mutations in human tissues is an important issue in cancer susceptibility and genotoxic exposure determinations. Here we report the detection of rare mutant leukocytes containing oncogenic base substitutions of the Harvey-ras, N-ras, and p53 genes by the Needle-in-a-Haystack mutation assay with a sensitivity of one cell in a million. Altogether, we detected and identified 17 independent mutations of 66 separate base site analyses of peripheral blood specimens obtained from 19 apparently normal individuals. Two individuals harbored a substantially increased frequency of mutant cells, representing 9 of the 17 independent mutations found. These results suggest that up to 1 in 10 normal individuals may harbor a significant frequency of oncogenic mutations in circulating leukocytes.

A mortality study of employees of the nuclear industry in Oak Ridge, Tennessee.

An analysis was conducted of 27,982 deaths among 106,020 persons employed at four Federal nuclear plants in Oak Ridge, Tennessee, between 1943 and 1985. The main objectives were to extend the evaluation of the health effects of employment in the nuclear industry in Oak Ridge to include most workers who were omitted from earlier studies, to compare the mortality experience of workers among the facilities, to address methodological problems that occur when individuals employed at more than one facility are included in the analysis, and to conduct dose-response analyses for those individuals with potential exposure to external radiation. All-cause mortality and all-cancer mortality were in close agreement with national rates. The only notable excesses occurred for white males for lung cancer [standardized mortality ratio (SMR) = 1.18, 1,849 deaths] and non-malignant respiratory disease (SMR = 1.12, 1,568 deaths). A more detailed analysis revealed substantial differences in death rates among workers at the Oak Ridge plants. Evaluation of internally adjusted log SMRs using Poisson regression showed that workers employed only at Tennessee Eastman Corporation or K-25 and at multiple facilities had higher death rates than similar workers employed only at X-10 or Y-12, and that the differences were primarily due to non-cancer causes. Analysis of selected cancer causes for white males indicated large differences among the workers at the different facilities for lung cancer, leukemia and other lymphatic cancer. Dose-response analyses for external penetrating radiation were limited to a subcohort of 28,347 white males employed at X-10 or Y-12. Their collective recorded dose equivalent was 376 Sv. There was a strong "healthy worker effect" in this subcohort-all-cause SMR = 0.80 (4,786 deaths) and all-cancer SMR = 0.87 (1,134 deaths). Variables included in the analyses were age, birth cohort, a measure of socioeconomic status, length of employment, internal radiation exposure potential and facility. For external radiation dose with a 10-year lag, the excess relative risk was 0.31 per Sv (95% CI = -0.16, 1.01) for all causes and 1.45 per Sv (95% CI = 0.15, 3.48) for all cancer. The estimated excess relative risk for leukemia was negative but imprecisely determined. A preliminary dose adjustment procedure was developed to compensate for missing dose but not other dosimetry errors. Results of the analyses using the adjusted doses suggest that the effect of missing dose is an upward bias in dose-response coefficients and test statistics.

Occupational medical program alcohol screening. Utility of the CAGE and BMAST.

Alcohol consumption is a primary or secondary factor in many work-related accidents, suicides, homicides, violent crimes, and motor vehicle accidents. The absentee rate in alcoholics is 3.8 to 8. 3 times greater than that for nonalcoholic workers. The purpose of this research was to evaluate the effectiveness of two interview questionnaires-the Brief Michigan Alcoholism Screening Test (BMAST) and the CAGE (cut down, annoyed by criticism, guilty about drinking, and eye-opener drinks). The validity of the BMAST and the CAGE as screening tools for alcohol problems has been verified in a number of nonworkplace settings. If they prove to be as effective for screening workers in an occupational medical setting, follow-up definitive diagnoses could result in earlier detection of alcohol problems and allow prompt intervention. Positive outcomes could include a safer workplace, less absenteeism, improved worker productivity, and a reduction in personal and family problems caused by drinking.

Treatment of radial fractures in adult horses: an analysis of 15 clinical cases.

Fifteen cases of radial fractures in adult horses weighing more than 300 kg are discussed. Four of the horses were destroyed on humane grounds immediately because of a poor prognosis and expense of internal fixation; and two horses at five days and five weeks, respectively after treatment by cast application was initiated. Internal fixation was used in nine horses but of these only two horses recovered completely and resumed their former activities. In eight cases, two plates were applied, one lateral or medial and the other cranial. The internal fixation techniques of all nine horses were scrutinised and suggestions made for the future treatment of radial fractures. These suggestions are (1) the use of ASIF 5.5 mm cortical bone screws using the total width or thickness of the bone in each case. (2) Application of the dynamic condylar screw with its plate in distal or proximal fractures to allow more support. (3) Incorporation of a cancellous bone graft to the fracture. (4) Possible table recovery to prevent breakdown of the fixation during recovery. It is important that bone plates are applied over the total length of the bone. The fact that only two out of 15 horses survived and recovered completely underlines the problems associated with treatment of radial fractures in the adult horse.

Results of plate fixation of type 1b olecranon fractures in 24 horses.

REASONS FOR PERFORMING STUDY: Previous olecranon fracture reports contain a small proportion of type 1b fractures, with only a few repaired by tension band plate fixation. OBJECTIVES: To evaluate subject details, history, clinical findings and outcome of type 1b olecranon fractures in a large group of horses treated by tension band plate fixation. METHODS: Medical records of 77 horses diagnosed with an olecranon fracture were reviewed. Twenty-four horses (31%) were classified as having type 1b olecranon fractures. Clinical details and follow-up results (4-128 months post operatively) were recorded. RESULTS: Treatment included open reduction and internal fixation using a narrow dynamic compression plate (n = 20), conservative therapy (n = 2) and euthanasia (n = 2). Long-term follow-up was available for 16 plated horses. Four were sound and in training and 9 were sound and performing athletically. Articular surface involvement, comminution, open status or removal of anconeal process fragments did not appear to affect prognosis or soundness. CONCLUSIONS: Internal plate fixation provides an excellent prognosis for an animal capable of athletic performance. POTENTIAL RELEVANCE: Describing tension band plate fixation and results offers a method of fracture repair that will improve the treatment and prognosis for type 1b olecranon fractures.

Rectal tears in the horse: an analysis of 35 cases.

The records of 35 horses with Grade 3 or 4 rectal tears, presented to the Veterinary Medical Center at Texas A & M University over a five year period, were reviewed. Grade 3 tears were sub-classified according to whether the remaining tissue was serosa (Grade 3a) or mesorectum (Grade 3b). Five horses were destroyed on presentation and 30 were treated by primary suture closure (8 horses), faecal diversion alone (9 horses) or in combination with suture closure (11 horses) and packing of the tear with medicated gauze sponges (two horses). Faecal diversion was achieved with a temporary indwelling rectal liner (TIRL) in 19 horses and colostomy in one. Survival was related to classification of the tear, efficacy of first aid measures administered at time of injury and method of treatment. Seventy-four per cent of horses with Grade 3a tears and 44 per cent of those with Grade 3b tears survived. Grade 4 tears had a grave prognosis. Horses given adequate first aid before admission had a better survival rate. With proper patient selection, primary closure of the tear with sutures yielded excellent results. In horses which were not candidates for suture closure alone, a combination of faecal diversion and suturing gave better results than faecal diversion only. In addition, selected horses were treated successfully by packing the rectal tear with gauze sponges. The results demonstrate the value of a TIRL to divert faeces and appropriate first aid measures in treating rectal tears.

Surgical treatment of subchondral cystic lesions of the third metacarpal bone: results in 15 horses (1986-1994).

Subchondral cystic lesions (SCLs) in the condyle of the third metacarpal bone (MCIII) were surgically treated in 15 horses. The median age at presentation was 18 months (range 10 months-12 years) with 10 of 15 horses less than age 2 years. The SCLs were confined to the front limbs in all cases with 2 horses having bilateral lesions. Lesions were isolated to the medial condyle(s) of MCIII in 13 of 15 horses; a cystic lesion occurred in the lateral condyle in one horse and in the sagittal ridge in one horse. One horse with bilateral lesions had an additional cystic lesion located in the right medial femoral condyle. Fourteen of 15 horses had a history of moderate lameness attributable to the metacarpophalangeal joint; the lesion was an incidental finding in one horse. Duration of lameness ranged from 4 weeks to 8 months and was either acute in onset, or occurred intermittently and was associated with exercise. Fetlock flexion significantly exacerbated the lameness in all cases. Synovial effusion was absent in 8 (53%) cases. Cystic lesions were curetted arthroscopically in 12 horses, and through a dorsal pouch arthrotomy in 3 horses. Concurrent osteostixis of the cystic cavity was performed in 7 horses. Two horses were treated arthroscopically for osteochondral fragmentation of the proximodorsal aspect of the proximal phalanx one year following surgical curettage of the SCL. Twelve of 15 horses (80%) were sound for intended use following surgical treatment. Two horses did not regain soundness and follow-up information was unavailable for one horse. Total period of follow-up was 1-6 years. Follow-up radiographic examinations were available for 9 horses. Mild periarticular osteophyte formation and enthesiophyte formation at the dorsal joint capsular attachments was present in 5 of the 9 horses. Bony ingrowth of the cystic lesion was detectable in 8 horses and enlargement of the cystic cavity was observed in one horse. Based on the information gained from this study, it would appear that surgical treatment of SCLs in the distal metacarpus can result in a favourable outcome for athletic use.

Disseminated intravascular coagulation associated with colic in 23 horses (1984-1989).

Disseminated intravascular coagulation (DIC) secondary to colic was diagnosed in 23 horses. Each horse was categorized retrospectively as to the cause of the colic based on surgical and/or necropsy findings: group 1 consisted of 14 horses with compromised intestine that required resection and anastomosis; group 2 consisted of 3 horses with nonstrangulating intestinal displacement and/or impactions; and group 3 consisted of 6 horses with colic associated with enteritis and/or colitis. Horses were considered to be affected with DIC if at least three of five hemostatic parameters were significantly abnormal: decreased antithrombin III (AT III) values, increased level of fibrin degradation products (FDP), thrombocytopenia, prolonged activated partial thromboplastin time, and prolonged prothrombin time. The most consistent hemostatic abnormalities were decreased AT III activity, increased FDP titers, and thrombocytopenia. Clotting times were more variable and did not always correlate with the presence of excessive hemorrhage. Excessive hemorrhage was present during surgery in seven horses and occurred within 1 to 12 hours after surgery in nine other horses. In addition to treatment of the primary disease, 19 horses received treatment for DIC consisting of heparin and/or plasma or fresh whole blood transfusions. Heparin alone was used in 12 horses. Heparin, in addition to fresh whole blood transfusions or fresh plasma, was administered to four horses. Three horses were treated with plasma alone. Four other horses were not treated specifically for the DIC. Eight horses (34%) survived the acute coagulopathy. Although a greater proportion of the surviving horses received heparin therapy (87.5%; 7/8) than did those that died (60%; 9/15), the difference was not statistically significant (P = 0.345).(ABSTRACT TRUNCATED AT 250 WORDS)

In vitro comparison of the effect of parallel and divergent transfixation pins on breaking strength of equine third metacarpal bones.

Breaking strength (torque at failure) of equine third metacarpal bones, with transfixation pins placed parallel in the frontal plane and 30 degrees divergent from the frontal plane, was determined in vitro. Two transfixation pins were placed through the distal metaphysis, using a jig designed to drill the holes in the assigned configuration. Paired metacarpal bones II through IV from 12 horses were tested in torsion. The torsional moment of the force applied through the transfixation pins at failure was compared for each limb. Metacarpal bones with divergent pins were significantly (P = 0.030) stronger, compared with those with parallel pins. Metacarpal bones with parallel pins failed with longitudinal oblique fractures through a proximal bone-pin interface, whereas those with divergent pins failed with more comminuted fractures through multiple bone-pin interfaces.

In vitro evaluation of four methods of attaching transfixation pins into a fiberglass cast for use in horses.

OBJECTIVE: To compare the axial stability provided by 4 methods of attaching transfixation pins into a fiberglass cast. DESIGN: Axial stability of 4 methods of transfixation pin attachment to a fiberglass cast cylinder was determined in vitro. Methods of attachment included simple incorporation of the pins into the cast, placement of a washer and nut on the pin and incorporation into the cast, extension of pins beyond the cast and attachment to a steel halo, and washers within the cast and attachment to a steel halo. POPULATION: A model was designed to simulate a transfixation cast applied to the equine metacarpus. 8 identical constructs were present in each of the 4 groups. 6 fiberglass cylinders were also tested to identify the contribution of the cast cylinder to the overall stability of the transfixation cast. PROCEDURE: Load-sufficient curves were recorded, and a stiffness modulus was calculated for each treatment group and for a simple fiberglass cylinder without transfixation pins. RESULT AND CONCLUSION: There was no significant difference among the 4 methods of attachment. The fiberglass cast material appears to be the major determinant of axial stability.

Healing of surgically created defects in the equine superficial digital flexor tendon: collagen-type transformation and tissue morphologic reorganization.

Full-thickness defects were surgically created in the superficial digital flexor tendons of the front limbs of 20 horses. Tissues formed within the defect were evaluated histologically, and the collagen composition of the tissue was determined by immunofluorescence. Transformation occurred from loose fibrillar areas of types I and III collagen and pericellular types IV and V collagen to dense bundles of type I collagen fibers. Loose fibrillar areas of types I and III collagen were present after 24 weeks. Histologically, in horses killed after 2 weeks, the tissue within the defect was a randomly oriented mass of fibrovascular tissue. In horses killed after 24 weeks the tissue within the defect resembled normal tendon tissue.

Healing of surgically created defects in the equine superficial digital flexor tendon: effects of pulsing electromagnetic field therapy on collagen-type transformation and tissue morphologic reorganization.

The effect of pulsing electromagnetic field (PEMF) therapy on the healing of surgically created defects in equine superficial digital flexor tendons was evaluated. Defects were created in both front superficial digital flexor tendons of 20 horses. The defect in 1 limb was exposed to a PEMF for 2 hours daily. The other limb served as a control. Histologic and immunofluorescent evaluations were done in horse killed at postsurgical weeks 2, 4, 8, 12, and 24. Therapy with the PEMF significantly (P less than 0.05) delayed the maturation of the tissue formed within the defect at postsurgical weeks 8 and 12, as determined by histologic examination. The collagen-type transformation was also delayed by the PEMF therapy, but to a degree that was not significant.

In vitro comparison of the standard short limb cast and three configurations of short limb transfixation casts in equine forelimbs.

Axial stability of equine oblique proximal phalangeal osteotomies with application of the standard short limb cast or 1 of 3 configurations of transfixation casts was determined in vitro. Transfixation cast methods included use of parallel pins, divergent pins, or parallel pins incorporating a metal walking bar. Displacement at the osteotomy was recorded for each limb at 4,448 N. Standard short limb casts provided significantly (P = 0.0002) less axial stability than did any form of transfixation cast. Significant differences were not found between the 3 transfixation casts.

Effects of intra-articular administration of dimethylsulfoxide on chemically induced synovitis in immature horses.

The effects of intra-articular administration of dimethylsulfoxide (DMSO) on chemically induced synovitis in the middle carpal joint of 6 weanling horses were evaluated. Following aseptic collection of synovial fluid, the middle carpal joint of each forelimb was injected with 50 mg of Na-monoiodoacetate to induce synovitis. Eight days after injection, synovial fluid was obtained and the right middle carpal joints were injected with 2 ml of 40% DMSO in lactated Ringer solution. The corresponding joints of the left limb (control) were injected with 2 ml of lactated Ringer solution. Sampling and treatments were repeated on post-injection days 11 and 14, for a total of 3 treatments. Horses were visually evaluated daily for lameness and joint effusion. Synovial fluid was evaluated for color and clarity, differential and total WBC count, total protein content, and hyaluronic acid concentration. The Kaegi gait analysis system provided an objective assessment of lameness prior to inducing synovitis, again on day 7, and on day 17. At necropsy (day 17), synovial fluid, synovial membrane, and articular cartilage specimens were collected. Joint effusion was evident 12 hours after injection of Na-monoiodoacetate in all joints. Mild lameness was evident at 24 hours; however, the lameness resolved by 72 hours. Objective assessment of lameness did not reveal significant differences between treatment or control limbs. Hyaluronic acid concentrations increased significantly (P = 0.023) above baseline values in most joints over the study period. Synovial fluid WBC counts increased significantly (P = 0.002) following Na-monoiodoacetate injection and remained significantly (P = 0.002) above baseline values throughout the study.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of antimicrobial solution lavage on the palmar digital tendon sheath in horses.

Sixteen horses were allotted to 4 groups of 4 horses each to evaluate the effect of tendon sheath lavage with 4 solutions (balanced electrolyte solution, 0.1% povidone-iodine, 0.5% povidone-iodine, and 0.5% chlorhexidine). The synovitis caused by 0.1% povidone-iodine lavage was not appreciably worse than that caused by balanced electrolyte solution lavage, but the 0.5% povidone-iodine and chlorhexidine lavages caused severe synovitis, and, therefore, should not be used for tendon sheath lavage.

Temporary indwelling rectal liner for use in horses with rectal tears.

A temporary indwelling liner was surgically installed in 17 horses with grade III or grade IV rectal tears. The rectal tears of 9 of the horses healed. The remaining 8 horses developed peritonitis as a result of peritoneal contamination before surgery, a change in grade of the tear, or material failure.

Intermittent antimicrobial infusion for management of a septic distal interphalangeal joint in a horse.

A 13-month-old Quarter Horse colt sustained a puncture wound to the frog region of the foot, which penetrated the navicular bursa and distal interphalangeal joint, 7 days prior to examination. A street-nail procedure was performed to debride the tract and provide drainage of the navicular bursa and distal interphalangeal joint. An indwelling lavage system was placed through the dorsal aspect of the joint and antimicrobials were infused intermittently to supply a high local concentration of drug and to frequently lavage the distal interphalangeal joint and navicular bursa.