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Biomedical subjects

R T Burks

Publications and source records attributed to R T Burks.

At least 19 recordsLinked to original sources

Obtaining intra-articular bone grafts arthroscopically for intra-articular grafting.

Autogenous bone graft is frequently necessary for arthroscopic procedures and even small open procedures that involve cruciate revision, osteochondritis dissecans repair, and fracture reduction and internal fixation. Currently used sites to obtain bone graft are the iliac crest and Gerdy's tubercle. This article describes an arthroscopic technique for harvest of small amounts of bone graft from the distal femur. This avoids the morbidity of the extra-articular harvest. Tube harvesters frequently used for osteochondral autografts are the primary tool required for this technique. However, as described, the obtaining of bone graft is much less technically exacting than when procuring osteochondral bone plugs. This provides a safe, simple way to obtain extra autogenous bone at minimal additional operative morbidity.

Adult↗

Pitfalls associated with fixation of osteochondritis dissecans fragments using bioabsorbable screws.

The purpose of this study was to evaluate 2 cases in which bioabsorbable screw fixation for an osteochondritis dissecans lesion of the femoral condyle resulted in complications necessitating the need for secondary surgery. We reviewed the case history of these patients and described the circumstances under which the bioabsorbable screws were used, the events leading to the need for secondary surgery, and the ultimate outcome. In the 2 cases presented, these implants were found to retain their mechanical stiffness for many months. This resulted in articular damage in 1 case after the treated lesion failed to heal. In the second case, screw breakage 8 months after implantation resulted in it becoming a loose body, which required removal during a second arthroscopic procedure. We conclude that these implants retain their mechanical properties for many months and cannot be relied on to degrade quickly. If a treated lesion fails to heal, these implants can cause mechanical problems due to their retained structural properties.

Absorbable Implants↗

Axillary nerve temperatures during radiofrequency capsulorrhaphy of the shoulder.

PURPOSE: The purpose of this study was to determine the temperatures along the course of the axillary nerve during radiofrequency (RF) capsulorrhaphy of the shoulder in a cadaver model. The hypothesis of this project was that temperatures capable of damaging neural tissue would be recorded during simulated RF capsulorrhaphy. TYPE OF STUDY: Basic science evaluation. METHODS: This study used 9 fresh-frozen cadaver shoulder capsules removed en bloc along with the underlying axillary nerve and soft tissue. The axillary nerve was instrumented with 4 thermocouples placed along the course of the nerve (2 thermocouples anterior and 2 posterior to the 6 o'clock position, spaced 7 mm apart). Each of the specimens underwent RF thermal capsulorrhaphy during which the temperature at each of the thermocouple positions was continuously recorded. RESULTS: The average of the maximum temperature at each of the 4 positions measured along the course of the axillary nerve were 52.2 +/- 18.0 degrees C at the most anterior place probed, 45.8 +/- 5.44 degrees C (mid anterior), 44.5 +/- 8.7 degrees C (mid posterior), and 42.8 +/- 10.1 degrees C at the most posteriorly positioned probe. Two specimens had a maximum temperature greater than the 67 degrees C set point of the device, and 7 specimens had a maximum temperature greater than 45 degrees C in at least 1 thermocouple position. CONCLUSIONS: This study shows that heating of the axillary nerve can occur during RF capsular shrinkage of the shoulder and may potentially reach levels that can damage neural tissue.

Body Temperature↗

Expression of c-kit (CD117) in benign and malignant human endometrial epithelium.

BACKGROUND: The proto-oncogene c-kit encodes a tyrosine kinase receptor (CD117) with a molecular weight of 145 kd. Previous studies, predominantly utilizing immunohistochemistry, have led to contradictory findings regarding the expression of CD117 in the endometrium. To help resolve this issue, we analyzed a series of benign and malignant endometrial tissues using both immunohistochemistry and Western blot analysis. OBJECTIVE: To examine the expression of CD117 in benign and malignant human endometrial tissues. METHODS: The expression of CD117 in 35 benign endometrial tissues (7 hyperplastic, 14 proliferative, 14 secretory) and 10 endometrioid carcinomas was investigated by immunohistochemistry (clone K45 monoclonal antibody). Immunoprecipitation (clone K69 monoclonal antibody) followed by Western blotting (clone K45 monoclonal antibody and clone 1.D9.3D6 monoclonal antibody) was performed to confirm CD117 expression. RESULTS: Fifty-seven percent of the hyperplasias, 93% of proliferative endometria, and 79% of secretory endometria immunostained positively for CD117. In benign endometria, epithelial staining tended to be more intense in the hyperplastic and proliferative endometria as compared to the secretory endometria, whereas endometrial stromal cells were not immunoreactive. Of the 10 frozen endometrial tissues analyzed by immunohistochemistry, 4 of 9 endometrioid carcinomas and a single case of an endometrioid polyp developing in association with a carcinoma expressed CD117. Immunoprecipitation followed by Western blot analysis confirmed expression of full-length CD117 in an endometrial polyp and carcinoma, and revealed a correlation between levels of immunoprecipitated CD117 and immunohistochemical staining intensity. CONCLUSIONS: Benign and malignant endometrial tissues express CD117. Our data suggest (a) a possible relationship between estrogen and CD117 expression in benign endometrium and (b) potential involvement of this growth factor receptor in endometrial carcinogenesis.

Blotting, Western↗

Pathology residents' use of a Web-based tutorial to improve Gleason grading of prostate carcinoma on needle biopsies.

Little is known about pathology residents' ability to Gleason grade or their ability to learn surgical pathology using Internet-based technology. A free Web-based program (available at www.pathology. jhu.edu/prostate) was developed that consisted of 20 pretutorial images for grading, 24 tutorial images, and the same 20 posttutorial images for Gleason grading. The grading images were selected from cases that had a consensus Gleason grade from 10 uropathology experts. In 2.5 months, 255 residents visited the website, and 151 (59%) completed it. Of those who completed the website, their year in training was known in 85 (56%): 1st year, 25.8%; 2nd year, 20%; 3rd year, 22.3%; 4th year, 14.1%; 5th year, 15.3%; and 6th year, 2.4%. Eighty percent learned Gleason grading in residency versus being self-taught, and 66% were male. In a multivariate analysis, higher pretutorial scores were associated with both their year in training (P = .001) and their hospital size (P = .003). Improvements in grading posttutorial were not related to the residents' year in training. Overall, the website significantly improved grading in 11 of 20 images and had no effect in 9 of 20 images. Improvements were noted in 1 of 1 Gleason score 4; 2 of 7 Gleason score 5 to 6; 2 of 6 Gleason score 7; and 6 of 6 Gleason score above 7 tumors. In summary, a Web-based tutorial improved Gleason grading accuracy by pathology residents to an equal extent regardless of their year in training. It is more difficult to teach residents to grade Gleason scores 5 to 7 tumors, and additional training should be concentrated in this area.

Biopsy, Needle↗

Histopathologic features of ovaries at increased risk for carcinoma. A case-control analysis.

In this study, the pathogenesis of ovarian carcinoma was investigated by performing a masked histopathologic comparison of benign ovaries removed from 61 women predicted to be at increased risk for developing carcinoma (cases) with ovaries removed from 121 women without known predisposing conditions (controls). The cases included 26 women who had a unilateral invasive carcinoma and 35 women undergoing prophylactic oophorectomy for a family history of ovarian cancer. As predicted by previously developed models, epithelial inclusion cysts were identified more frequently with advancing age in both cases and controls. However, the mean and maximum number of cysts per slide in a woman were not increased among cases. Surface epithelial "atypia," a designation based on a composite impression of multiple features, was found in 13% of cases compared with 3% of controls (relative risk 7.1; 95% confidence interval, 1.9 to 26.1), but this result was based on small numbers. None of the other histologic features examined was found more often in cases following age-adjustment. Reexamination of sections with well-preserved surface epithelium or inclusion cysts under oil immersion demonstrated several differences in the detection of specific features between cases and controls and increased detection of "atypia" among cases, but none of these findings reached statistical significance. It is concluded that there may be subtle differences in the surface epithelium of ovaries predisposed to developing cancer as compared with controls, but these changes are difficult to identify reliably with light microscopy. Future etiologic studies should attempt to optimize specific handling and include molecular studies and epidemiologic analyses.

Adult↗

Biomechanical evaluation of lateral patellar dislocations.

This investigation was undertaken to identify the structures torn within the medial retinaculum and localize the injury site anatomically following acute lateral dislocation of the patella in a cadaver model. The patellae of 10 fresh-frozen cadavers were translated laterally 135% of the patella width on a universal testing instrument. Magnetic resonance imaging (MRI) was performed on all specimens prior to testing and immediately following testing. Anatomical dissection also was performed on the medial retinaculum following testing. Dissection revealed avulsion fractures from the inferomedial border of the patella in 8 of the 10 knees. The medial patellofemoral ligament was injured in 8 of the 10 knees; the location of the injury varied. Tears of the medial patellofemoral ligament from the femur in 6, a midsubstance tear in 1, and stretch in 1 knee were noted. In a knee with a femoral-sided tear, an avulsion fracture of the medial patellofemoral ligament was identified. None of the cadaver knees demonstrated tears of the lateral retinaculum or medial patellotibial ligaments on dissection. Review of the MRIs revealed a medial retinaculum tear in 6 of the 10 knees. Two tears from the femur, 3 from the patella, and 1 tear from both the patella and femur were noted. An avulsion fracture was noted from the inferomedial patellar border in 3 of the 10 knees. No pathology was noted on 4 of the MRIs. When anatomically correlated, the 3 patellar retinacular tears and 3 avulsion fractures noted on MRI represented a tear of the medial patellomeniscal ligament from the patella. The femoral-sided tear represented a tear of the medial patellofemoral ligament from the femur. An appreciation of the spectrum of injury to the medial retinaculum may aid in the diagnosis of an acute dislocation of the patella and help establish the anatomical structures damaged. The pathology demonstrated in this study may explain the diversity of injury seen clinically. Whereas an avulsion fracture from the patella may represent the medial patellomeniscal ligament, a femoral-sided retinacular tear may represent the medial patellofemoral ligament. This may lead to future refinements of surgical options and anatomic restoration of the damaged structure.

Biomechanical Phenomena↗

Fifteen-year follow-up of arthroscopic partial meniscectomy.

From an original pool of 283 patients, 146 patients who had undergone arthroscopic partial meniscectomy an average of 14.7 years before were followed-up. Lysholm score, Tegner activity level, satisfaction index on a scale of 1 to 10, and standing anteroposterior and flexion weight-bearing radiographs of both knees, were obtained. A physical examination was performed on each knee emphasizing motion, swelling, and ligament evaluation. Radiographs were graded for degenerative changes for each knee. Each knee joint space was also measured in millimeters and compared, operative knee with unoperated knee. The unoperated knee had no injuries or surgeries and was used as a control. Patients were 83% male and 17% female; 78% had undergone medial meniscectomies, 19% lateral, and 3% both. There were 88% good and excellent results in anterior cruciate ligament-stable knees. The radiographic grade side-to-side difference showed the operative knee to be only a 0.23 grade worse than the nonoperative knee. Age at the time of meniscectomy was not found to be a factor. Male patients had better radiographic results than female patients, but not better functional scores. Medial meniscus and lateral meniscus results were not significantly different. Knees with a femoral-tibial anatomic alignment of > 0 degree valgus compared with < or = 0 degree and that had undergone medial meniscectomy had significantly better radiographic results. Patients with anterior cruciate ligament tears and meniscectomy did significantly poorer than stable knees with meniscectomy in regards to radiographic grade change, Lysholm, satisfaction index, Tegner level, and medial joint space narrowing.

Adult↗

DCC genetic alterations and expression in endometrial carcinoma.

DCC (Deleted in Colorectal Carcinoma) is a candidate tumor suppressor gene located on the long arm of chromosome 18. DCC was initially identified and cloned during a search for the target gene located in a region of 18q that demonstrated loss of heterozygosity (LOH) in 70 to 80% of colorectal cancers. More recently, the region of 18q harboring the DCC gene has been shown to undergo LOH in approximately 14 to 30% of endometrial carcinomas. These findings suggest that DCC may be a target of LOH in at least some endometrial carcinomas and, therefore, may have a role in the pathogenesis of this common malignancy of the female genital tract. To address this possibility, we analyzed 26 cases of endometrioid endometrial carcinoma for DCC LOH and alterations in an AT microsatellite repeat located in an intron of the DCC gene. LOH was detected in one case (4%). Allelic shifts at the DCC AT repeat were detected in five (19%) additional cases. We also evaluated DCC protein expression by immunohistochemical analysis in normal, hyperplastic, and neoplastic endometrial tissues. Three proliferative and five secretory endometria and one simple endometrial hyperplasia demonstrated staining for DCC. Four of the 26 endometrioid endometrial carcinomas for which frozen tissue was available, including at least one from each histologic grade, and a case of endometrioid carcinoma confined to the endometrium completely lacked detectable staining for DCC. Although DCC LOH was infrequent in endometrial carcinomas, alterations of the gene (LOH or AT repeat alterations) were not uncommon (23% of our cases). In addition, DCC was expressed in normal endometrial tissue, whereas expression was lost in all of the five endometrial carcinomas. The combination of the genetic alterations and loss of DCC protein expression suggests that inactivation of the DCC gene may play a role in the pathogenesis of endometrial carcinoma.

Carcinoma↗

Comparison of anterior cruciate ligament reconstructions using patellar tendon autograft or allograft.

Seventy-eight of 113 consecutive patellar tendon anterior cruciate ligament reconstructions (autograft, 47 of 66; allograft, 31 of 47) were evaluated at an average of 34 months. Reconstructions were compared with Lysholm and Tegner knee-rating scales, physical examination findings, instrumented laxity values, single-leg hop distances, and isokinetic strength results. Lysholm scores > or = 90 were achieved by 69% of autograft patients versus 67% of allograft patients. Desired Tegner activity scores were achieved by 80% of autograft patients versus 74% of allograft patients. Patellofemoral signs and symptoms were absent in 40% of autograft patients versus 44% of allograft patients. Side-to-side laxity differences < or = 3 mm were achieved in 80% of autograft patients versus 70% of allograft patients. Single-leg hop scores > or = 90% of the nonoperated leg were obtained in 76% of autograft patients versus 81% of allograft patients. Isokinetic results between groups were also similar. Traumatic ruptures were sustained by four allograft patients at an average of 11 months postoperatively compared with no traumatic ruptures in the autograft group (P = .011). This was the only difference of statistical significance.

Adult↗

Micropapillary serous carcinoma of the ovary. A distinctive low-grade carcinoma related to serous borderline tumors.

According to the International Federation of Gynecology and Obstetrics (FIGO) and the World Health Organization (WHO), stromal invasion, defined as destructive infiltrative growth, is the sole criterion used to distinguish serous borderline tumors from invasive serous carcinomas of the ovary. Although this criterion effectively identifies most malignant tumors, it does not permit the identification of a small subset of well-differentiated ovarian carcinomas that do not display destructive infiltrative growth but that may be associated with malignant behavior. In this study, we describe a group of such serous neoplasms that have distinctive morphologic features and that are often associated with progressive, invasive disease. We have designated these tumors micropapillary serous carcinomas (MPSC). They are characterized by a filigree pattern of highly complex micropapillae arising directly from large, bulbous papillary structures. The micropapillae are covered by round to cuboidal cells with a high nuclear-to-cytoplasmic ratio. Typical serous borderline tumors tend to display a hierarchical pattern of branching terminating in small papillae or tufts, and the cells covering the papillae tend to be more columnar and often ciliated compared with cells of MPSC. We reviewed more than 400 cases of serous ovarian borderline tumors and well-differentiated serous carcinomas and identified 26 cases of MPSC. Seventeen tumors lacked destructive infiltrative growth (noninvasive), and nine contained areas of invasion ranging from minimal to extensive. Eight of the 26 tumors were stage I, and none of the patients developed recurrence whether or not their tumors had demonstrable invasion. In contrast, of the 16 women presenting with stage II disease or higher and who had more than 1 year of follow-up, eight (50%) have either died of intra-abdominal carcinomatosis or are alive with carcinoma. Twenty-four (92%) of MPSCs contained areas of serous borderline tumor. The frequent association of MPSCs with serous borderline tumors suggests that MPSCs arise from the latter and may account for the few cases of serous borderline tumors that have been associated with progression to invasive carcinoma.

Adult↗

Lisfranc injuries in the athlete.

Injuries to the Lisfranc joint in the athlete comprise a very small proportion of tarsometatarsal injuries and are unique in several different ways. The energy involved appears to be on a much smaller order of magnitude than more commonly encountered injuries leading to obvious fracture and dislocation. Second metatarsal subluxation with diastasis between the first and second metatarsal tends to be the most commonly encountered injury; however, the true extent of injury cannot be based solely on the amount of diastasis present. Lateral weight-bearing radiographs facilitate evaluation of the normal medial cuneiform-fifth metatarsal relationship, which when disrupted indicates an injury more significant than a simple sprain and the possible need for open reduction and internal fixation. Finally, the restoration of this normal radiographic relationship between the medial cuneiform and fifth metatarsal on lateral weight-bearing views correlates well with the prognosis for achieving an asymptomatic, well-functioning foot, allowing a return to a competitive level of athletic participation.

Adult↗

Microsatellite instability in endometrial carcinoma.

Microsatellite instability (MI), detected as electrophoretic shifts in allele sizes of microsatellite DNA sequences, has been identified in some colorectal carcinomas. Investigators have previously attributed such microsatellite instability to replication errors (RER). The colorectal carcinomas with RER have been found to arise either sporadically or in association with the hereditary non-polyposis colorectal cancer (HNPCC) syndrome. Because endometrial carcinoma is also commonly associated with HNPCC, we studied 30 cases of endometrial carcinoma to characterize the presence of MI in these neoplasms. Seven cases (23%) showed MI. Four cases showed both Type I (large shifts) and Type II (small shifts) mutation patterns and the remaining three cases showed Type I mutations only. We conclude that MI frequently occurs in endometrial cancers and that this type of genetic alteration may be an important pathogenetic feature of this tumor type.

Alleles↗

Principles and decision making in meniscal surgery.

This article provides a review of the basic science and clinical information available to the orthopedist on which a systematic approach to meniscal surgery can be based. Attitudes toward the meniscus have changed dramatically in the last 50 years. Laboratory investigations show that the menisci participate in many important functions, including tibiofemoral load transmission, shock absorption, lubrication, and passive stabilization of the knee joint. Histologic/structural analyses reveal the menisci to be annular structures, with the ability to transmit and properly distribute load over the tibial plateau, primarily facilitated by the circumferential collagen fibers in the peripheral third of the meniscus, in conjunction with their strong bony attachments at the anterior and posterior horns. Biologic studies demonstrate that meniscal healing can occur through two pathways: an intrinsic ability of the meniscal fibrochondrocyte to migrate, proliferate, and synthesize matrix (provided they are given the proper environment), and extrinsic stimulation through neovascularization (when the meniscal injury occurs in the vascular periphery). This review makes it clear that the menisci are essential components of the normal knee, and that techniques intended to preserve the menisci are both possible and mandatory. As evidence has accumulated from both animal and clinical studies of the frequent development of degenerative changes following meniscectomy, surgeons have become increasingly aggressive in their efforts to conserve as much meniscal tissue as possible. Current approaches to treatment of meniscal tears are based on a thorough understanding of meniscal structure, biology, and function, as well as familiarity with the basic principles of meniscal repair and resection. To synthesize these principles, the article concludes with an algorithm intended to guide surgeons in decision making when faced with a variety of meniscal lesions in different clinical situations.

Algorithms↗

Subtle injuries of the Lisfranc joint.

In fifteen patients, a subtle injury of the Lisfranc joint (tarsometatarsal articulation) was found. The lesion was defined as a diastasis of two to five millimeters between the bases of the first and second metatarsals, as seen on anteroposterior radiographs. There often was a long delay between injury and diagnosis. Eight patients were treated with a below-the-knee cast only, three had treatment with a cast and then tarsometatarsal arthrodesis, two had no initial treatment but later had arthrodesis, and two had open reduction and internal fixation. The duration of follow-up ranged from two to thirteen years after the diagnosis. There was no correlation between the severity of the diastasis and the patient's functional result. Marked disability and pain persisted in seven patients, and six of them had flattening of the longitudinal arch. Maintenance of the longitudinal arch usually was associated with a better functional outcome. When a patient has a subtle injury of the Lisfranc joint, weight-bearing lateral radiographs of both feet are needed to identify flattening of the longitudinal arch. Such radiographs should be made routinely in the evaluation of all injuries of the foot that may involve the Lisfranc joint.

Adult↗