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Biomedical subjects

W G Rodkey

Publications and source records attributed to W G Rodkey.

33 records · Page 2Linked to original sources
PubMed1980

Peripheral nerve injuries: studies in higher nonhuman primates.

Two skeletally mature baboons underwent comparative neurorrhapies following transsection of both ulnar nerves without loss of nerve tissue. In baboon 1 there was no difference in objective evaluations at 12 months when an epineurial neurorrhaphy was compared to a perineurial fascicular neurorrhaphy. In baboon 2, the one that had interfacicular grafts in one upper extremity and an epineurial neurorrhaphy on the other side, there was significantly better functional return on the epineurial side than one the graft side. Grass and histological evaluation showed that the grafts retained their integrity and regenerating axons transversed the grafts well.

Animals↗
PubMed1980

Neurorrhaphy after loss of a nerve segment: comparison of epineurial suture under tension versus multiple nerve grafts.

Epineural neurorrhaphy under tension and interfascicular grafting, two methods of bridging gaps associated with loss of a nerve segment, were compared. After resection of a 2 cm length of both ulnar nerves in cats, one nerve was sutured under tension using an epineurial technique, and the other was repaired using multiple interfascicular sural nerve grafts. Six months later return of nerve function was evaluated. Subjective evaluation included ambulation, sensation, and intrinsic function. Objective measurements included muscle efficiency, maximum strength, muscle weights, and total axon counts. No statistical difference was observed between these two techniques. Histochemically, there was marked fiber type grouping of the reinnervated muscles for both types of repairs. Histologically, perineurial fibrosis and axonal disorganization were equal for both techniques, but significantly greater suture granuloma formation occurred in the nerve repaired under tension. Individual grafts retained their identity and remained distinct grossly and microscopically.

Animals↗
PubMed1979

Experimental penetrating renal trauma: a comparison of bench and in situ repair.

Penetrating renal trauma often requires total nephrectomy. To minimize this high rate of renal loss, extracorporeal (bench) surgery, already an accepted method for treating renovascular and renal tumor, might be used in patients with parenchymal injuries to provide a more meticulous repair and improved renal function. To compare the effectiveness of this technique with that of in situ repair, 32 dogs were divided into two equal groups. They all received a standardized injury to the renal parenchyma. Contralateral nephrectomy was performed. Renal function was evaluated for 21 days. Serum creatinine values were comparable in the two groups. Bench repair offered excellent results but not better than in situ repair for parenchymal and collecting system injuries.

Animals↗
PubMed1978

Arterialized capillary blood used to determine the acid-base and blood gas status of dogs.

Blood samples were collected by microhematocrit tube from posterior medial margin of the shaved, but otherwise untreated, canine ear. Acid-base and blood gas values of these samples were compared with the values of samples obtained simultaneously from the carotid artery. The arterialized nature of capillary blood from the canine ear was demonstrated under various degrees of chemical restraint and during conditions of extreme hypoxic acidosis to hyperventilatory alkalosis. Once a week determinations of acid-base and blood gas status with such arterialized capillary blood from a group of awake dogs showed within-subject variance to be significantly less (P less than 0.05) than between-subject variance; thus, uniqueness of individual dogs was reliably revealed. This technique also was used to demonstrated breed differences for acid-base and blood gas characteristics.

Acid-Base Equilibrium↗
PubMed1977

Coronary flow distribution and dynamics during continuous and pulsatile extracorporeal circulation in the pig.

Four extracorporeal perfusion conditions (continuous beating, continuous fibrillating, pulsatile beating, and pulsatile fibrillating) were tested for 15 minutes each in pigs. Coronary flow, endocardial-epicardial flow ratio, phasic coronary flow, myocardial oxygen consumption, and myocardial lactate extraction were measured. No significant differences in any of these variables were found between pulsatile and continuous flow states in either fibrillating or beating hearts (p greater than 0.05). In both fibrillating conditions, significant elevations of myocardial oxygen consumption and decreases in endocardial-epicardial flow ratios were found (p less than 0.05). Lactate extraction occurred in all conditions, and phasic coronary flows were similar in both beating conditions. These data suggest caution in the expectation that pulsatile perfusion will reverse the coronary flow and myocardial oxygen consumption changes seen with fibrillation.

Animals↗
PubMed1976

Epineurial and perineurial fascicular nerve repairs: a critical comparison.

To compare the results of epineurial and intrafascicular perineurial nerve repair techniques, ulnar nerves of 20 domestic cats were severed proximal to the medical humeral epicondyle. One nerve was repaired with No.8-O nylon by standard epineurial technique with the aid of three to five magnifications; the other nerve was repaired with No. 10-O nylon by intrafascicular perineurial technique under higher magnification. Four to five months following neurorrhaphies, the ambulation pattern, fanning of claws, and sensation were evaluated subjectively. Objective measurements included efficiency, absolute strength, and exact weight of the flexor carpi ulnaris muscle. Proximally and distally to each neurorrhaphy, complete axon counts were taken. Histochemically and histologic analyses were made on reinnervated muscles and neuromas. No statistically significant differences were detected between the results of epineurial and intrafascicular perineurial neurorrhaphies. These findings indicate that, following acute nerve laceration in the cat, epineurial neurorrhaphy is as satisfactory as is intrafascicular perineurial neurorrhaphy.

Animals↗
PubMedDate not supplied

Arthroscopic subchondral bone plate microfracture technique augments healing of large chondral defects in the radial carpal bone and medial femoral condyle of horses.

OBJECTIVE: To evaluate the effect of arthroscopic subchondral bone microfracture on healing of large chondral defects in horses. STUDY DESIGN: Short- (4 months) and long-term (12 months) in vivo experimental chondral defect model. ANIMALS: 10 horses, aged 2 to 5 years. METHODS: Each horse had a 1 cm2 full-thickness chondral defect created in both radial carpal bones and both medial femoral condyles. One carpus and one femoral condyle of each horse had the subchondral bone plate under the defect perforated using an orthopedic awl. All horses were exercised, five horses were evaluated after 4 months and five horses after 12 months. Gross, histologic, and histomorphometric examination of defect sites and repair tissues was performed, as was collagen typing of the repair tissue. RESULTS: On gross observation a greater volume of repair tissue filled treated defects (74%) compared with control defects (45%). Histomorphometry confirmed more repair tissue filling treated defects, but no difference in the relative amounts of different tissue types was observed. There was an increased percentage of type II collagen in treated defects compared with control defects and evidence of earlier bone remodeling as documented by changes in porosity. CONCLUSIONS: In full-thickness chondral defects in exercised horses, treatment with subchondral bone microfracture increased the tissue volume in the defects and the percentage of type II collagen in the tissue filling the defects when compared to nontreated defects. CLINICAL RELEVANCE: No negative effects of the microfracture technique were observed and some of the beneficial effects are the basis for recommending its use in patients cases with exposed subchondral bone.

Animals↗
PubMedDate not supplied

Experimental studies of acute anterior cruciate ligament injury and repair.

Ten dogs and six rhesus monkeys underwent transection and repair of the anterior cruciate ligament. One-half of the procedures involved the femoral end, the other half involved the tibial end of the ligament. Seven of the 10 canine and all of the primate ligaments, that had been transected and repaired, did heal. Functional and clinical instability was demonstrable in all repaired knees. The monkeys developed fewer degenerative changes with more grossly normal appearing ligaments after the repairs than did the dogs. Failure testing on an Instron materials testing machine revealed maximum strength of the repaired ligaments to be 10.4% for the repairs at the femoral end and 2.0% for repairs at the tibial ends in dogs when compared with the contralateral control knees. In monkeys the femoral repairs were 46.8% and the tibial repairs were 62.6% of the control knees. Inadequate immobilization and early stress were believed to be principal causes of the poorer results in dogs. The observations in monkeys support the suggestion that injured anterior cruciate ligaments that can be repaired, should be repaired.

Animals↗
PubMedDate not supplied

Acute anterior cruciate ligament injury and augmented repair. Experimental studies.

Eleven dogs underwent transection of the anterior cruciate ligament at the femoral origin of the stifle (knee) joint. The anterior cruciate ligaments were repaired in a conventional manner and augmented by transferring the medial one-third of the patellar tendon and inserting it into the lateral femoral condyle. The repairs were evaluated either 4 or 8 months postoperatively. All repaired and augmented anterior cruciate legaments in this series healed satisfactorily to provide clinical and functional stability to the knee joints. Instron testing of the repaired and augmented anterior cruciate ligaments showed maximum strength at 4 months of 46.2 +/- 10.9 kgf and at 8 months of 64.3 +/- 14.3 kgf as compared to the control of 122.7 +/- 11.6 kgf. Histologic evaluation showed that by 8 months the repaired and augmented anterior cruciate ligaments had healed by bony ingrowth. Thus, interstitial failure occurred during Instron testing. The transferred patellar tendon provided additonal blood supply, splinted the anterior cruciate ligament to allow healing, and increased the strength of the repaired complex.

Animals↗
PubMedDate not supplied

Medical meniscus repairs. An experimental and morphologic study.

In an effort to determine the healing potential of medial meniscus tears, 20 canine and 12 rhesus knee joints were subjected to transverse medial meniscus laceration and repair with a single Dexon suture (Davis & Geck, Pearl River, NY). At four months, 12 out of 32 (38%) had healed completely with restoration of the inner meniscal rim and 18 (56%) showed partial healing sufficient to protect the underlying articular cartilage. Only 2 (6%) of the menisci failed to heal. Histologic evaluation showed that the scar tissue present in the menisci was composed of unorganized collagen without common ground substance components. As a result of these studies, we believe that certain meniscal tears, particularly those involving the vascular periphery, can heal and may be repaired rather than treated by meniscectomy.

Animals↗
PubMedDate not supplied

Acute anterior cruciate ligament injury and repair reinforced with a biodegradable intraarticular ligament. Experimental studies.

The anterior cruciate ligament was transected at the femoral origin in the knee joint of 12 dogs. The ligaments were repaired in a conventional manner and reinforced with a polyglycolic acid (PGA) ligament of braided Dexon (Davis & Geck, Pearl River, NJ) suture. At two weeks the PGA ligament was still providing excellent support for the healing anterior cruciate ligament, and there was no synovitis within the knee joint. After five weeks, initial healing had firmly attached the repaired anterior cruciate ligament to the femoral condyle, and the PGA ligament had resorbed without inflammatory or fibrotic response. All repaired and reinforced ligaments in this series healed and provided functional stability to the knee joints. Biomechanical testing of the repaired anterior cruciate ligaments at four months produced a maximum strength of 54.2 +/- 6.3 kgf. Sulfur-35 uptake showed viable active collagen-producing cells in the repaired ligaments four months postoperatively. Thus, the biodegradable PGA ligament reinforced and splinted successfully the repaired anterior cruciate ligament.

Animals↗
PubMedDate not supplied

A partially biodegradable material device for repair and reconstruction of injured tendons. Experimental studies.

We assessed the applicability of a partially biodegradable synthetic material composed of polyglycolic acid (PGA) and dacron to repair or replace severely injured tendons. Adult rabbits underwent complete laceration and repair of one Achilles tendon. Group 1 (N = 8) had end to end tenorrhaphy with size 0 braided polyester suture, and Group 2 (N = 16) tendons were similarly repaired with the bicomposite designed PGA-dacron device. Group 3 (N = 16) received laceration and removal of 1 cm of tissue, and the defect was bridged with the same PGA-dacron material. No postoperative immobilization was applied. Evaluation, consisting of biomechanical testing or histologic inspection, was done at 4 and 8 weeks after tenorrhaphy. All tendons healed, and at 8 weeks the mean maximum load at failure of the repaired tendons was 32.2 +/- 3.4 kgf, 40.3 +/- 2.4 kgf, and 31.8 +/- 3.2kgf for Groups 1, 2, and 3, respectively. Values between groups were not significantly different, but all were significantly less (P less than or equal to 0.05) than the strength of the unoperated control tendons (55.8 +/- 7.2 kgf). The most noteworthy finding was the lengthening of the repaired tendons, due to scar elongation at the tenorrhaphy site, that occurred during healing as determined by a landmark placed a fixed distance proximal to the repair site. Group 1 tendons lengthened 22 mm, while Group 2 and 3 tendons increased by 12.5 mm. Histologically, fibrous tissue ingrowth into the residual dacron scaffold occurred, but it was inconsistent and inadequate in quality and quantity to be satisfactory as neotendon. The fibrous tissue did not mature or align in response to load. We concluded that the PGA-dacron material had adequate strength and physical properties to use both for primary tenorrhaphy and to bridge the tendon defect. However, in our experience this material lacks any significant advantage over other materials available or known to be under evaluation to support neotendon formation when an actual soft tissue defect exists.

Achilles Tendon↗
PubMedDate not supplied

Meniscal regeneration with copolymeric collagen scaffolds. In vitro and in vivo studies evaluated clinically, histologically, and biochemically.

We sought to create a regeneration template for the meniscal cartilage of the knee to induce complete meniscal regeneration, and to develop the technique for implanting the prosthetic appliance in vivo. We designed a resorbable collagen-based scaffold and conducted in vitro and in vivo studies. In vivo, the scaffold was implanted in the knees of immature swine and mature canines and evaluated clinically, histologically, and biochemically. Because the canine stifle joint meniscus is more clinically relevant to the human meniscus, this paper emphasizes those results. We studied 24 mixed breed dogs (14 males and 10 females) with an average weight of 25.5 kg (range, 20 to 35) that were obtained from a USDA-licensed supplier. The dogs were deemed clinically and radiographically skeletally mature. None of the dogs had a preexisting knee joint abnormality. All dogs underwent an 80% subtotal resection of the medial meniscus bilaterally. A collagen template was implanted in one stifle (N = 24). The contralateral side served as a control: 12 dogs had a total resection alone and the other 12 dogs had an immediate replantation of the autologous meniscus. Results were tabulated at 3, 6, 9, and 12 months. At final evaluation, before the animals were euthanized, the results were submitted for statistical analysis as well as histologic and biochemical analyses. The results demonstrated that a copolymeric collagen-based scaffold can be constructed that is compatible with meniscal fibrochondrocyte growth in vitro and in vivo, that does not inhibit meniscal regeneration in an immature pig, and that may induce regeneration of the meniscus in the mature dog.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMedDate not supplied

Measurements of the intercondylar notch by plain film radiography and magnetic resonance imaging.

The purpose of this investigation was twofold. In Part I, we determined the accuracy of morphometric analysis of the knee using magnetic resonance imaging and plain film radiography. The results of Part I validated the accuracy of magnetic resonance measurements and its superiority over plain film measurements. In Part II, we evaluated knee morphometry in 20 asymptomatic athletes with chronic anterior cruciate ligament insufficiency to determine if any predisposing factors to anterior cruciate ligament disruption could be detected. With our analysis, we could detect no predisposing factors to explain the anterior cruciate ligament disruption in the cohort group.

Anterior Cruciate Ligament Injuries↗