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Biomedical subjects

S J Snyder

Publications and source records attributed to S J Snyder.

At least 37 records · Page 2Linked to original sources
PubMed1991

Partial thickness rotator cuff tears: results of arthroscopic treatment.

Thirty-one patients with arthroscopically documented partial thickness rotator cuff tears treated by arthroscopic debridement of the lesion were retrospectively reviewed. The patients had had symptoms for an average of 20.5 months prior to surgery. Twenty-two of these 31 shoulders also had bursoscopy, with 18 having arthroscopic subacromial decompression. The results were graded by both the UCLA Shoulder Rating Scale and Neer's criteria. Twenty-six (84%) of the patients had satisfactory results with the remaining 5 (16%) patients having unsatisfactory results. A classification system for the size and location of partial thickness rotator cuff tears is presented. The lesion size did not affect the result. Repeat arthroscopy in three patients demonstrated no further deterioration of their rotator cuff. The results with and without subacromial decompression were similar. The need for subacromial decompression is best determined by the arthroscopic finding of a bursal side tear.

Adult↗
PubMed1991

Hemodynamic instability after the initiation of extracorporeal membrane oxygenation: role of ionized calcium.

OBJECTIVES: To prospectively document the occurrence of ionized hypocalcemia in infants and children treated with extracorporeal membrane oxygenation (ECMO), to determine if the type of calcium salt (calcium chloride or gluconate) used in priming the ECMO circuit affected ionized calcium, to determine if ionized calcium concentrations correlate with total calcium, protein, albumin, or total magnesium values, and to determine if the hypotension usually observed after ECMO initiation correlates with low circulating ionized calcium concentrations. DESIGN: Prospective study. SETTING: Pediatric ICU and neonatal ICU. PATIENTS: Sixteen neonatal and three pediatric patients who were started on ECMO for cardiopulmonary support. INTERVENTIONS: The ECMO circuit was primed in a standardized manner, 100 mg of calcium gluconate was added in group 1 patients and 100 mg of calcium chloride was added in group 2 patients. MEASUREMENTS: Ionized calcium was measured from the circuit before initiation of ECMO and from the patient before, and then 5, 10, 15, 30, 60, 120, and 240 mins after initiation of ECMO. Total calcium and ionized calcium concentrations were measured simultaneously every 6 hrs. Serum total protein, albumin, magnesium, and ionized calcium values were measured from blood samples collected simultaneously twice daily. RESULTS: A significant decrease in the mean serum ionized calcium value occurred 5 mins after the initiation of ECMO in both groups, p less than .001. The ionized calcium value remained significantly decreased until 30 mins after the initiation of ECMO. There were no differences between the ionized calcium concentrations obtained during priming with calcium gluconate vs. those concentrations obtained with calcium chloride priming (p = .79). Throughout the course of ECMO, the serum ionized calcium concentrations ranged from 0.60 to 1.86 mmol/L. Poor correlations existed between circulating ionized calcium values and total calcium (r2 = .30), total protein (r2 = .20), albumin (r2 = .20), and magnesium concentrations (r2 = .10). There was a good correlation between the patients' BP and ionized calcium concentrations after bypass was initiated (r2 = .87). CONCLUSION: Our data demonstrate that ionized hypocalcemia is a frequent occurrence after the initiation of ECMO. Since there is a poor correlation between ionized calcium and total calcium, ionized calcium concentrations should be measured directly in these patients.

Blood Pressure↗
PubMed1991

Rotator cuff lesions. Acute and chronic.

The complex anatomy of the shoulder often impedes the orthopedic surgeon's evaluation and understanding of injuries to the shoulder joint, particularly the rotator cuff muscle-tendon complex. Arthroscopy, MRI, and digital data analysis are several techniques now at the surgeon's disposal. This article reviews the application of these techniques in the evaluation of rotator cuff injuries.

Arthroscopy↗
PubMed1991

Accuracy of diagnoses from magnetic resonance imaging of the knee. A multi-center analysis of one thousand and fourteen patients.

Magnetic resonance images of the knee were made for 1014 patients, and the diagnosis was subsequently confirmed arthroscopically. The accuracy of the diagnoses from the imaging was 89 per cent for the medial meniscus, 88 per cent for the lateral meniscus, 93 per cent for the anterior cruciate ligament, and 99 per cent for the posterior cruciate ligament. The magnetic resonance examinations were done at several centers, and the results varied substantially among centers. The accuracy ranged from 64 to 95 per cent for the medial meniscus, from 83 to 94 per cent for the lateral meniscus, and from 78 to 97 per cent for the anterior cruciate ligament. The results from different magnetic-resonance units were also compared, and the findings suggested increased accuracy for the units that had a stronger magnetic field. Of the menisci for which the magnetic resonance signal was reported to be Grade II (a linear intrameniscal signal not extending to the superior or inferior meniscal surface), 17 per cent were found to be torn at arthroscopy.

Adolescent↗
PubMed1990

Transient postoperative blindness as a possible effect of glycine toxicity.

This case report of transient blindness after bilateral knee arthroscopy postulates glycine toxicity as a possible cause of postoperative blindness. The orthopaedic surgeon should be aware of this dose-related effect, and should use glycine irrigant selectively and sparingly for electrosurgical applications.

Arthroscopy↗
PubMed1990

SLAP lesions of the shoulder.

A specific pattern of injury to the superior labrum of the shoulder was identified arthroscopically in twenty-seven patients included in a retrospective review of more than 700 shoulder arthroscopies performed at our institution. The injury of the superior labrum begins posteriorly and extends anteriorly, stopping before or at the mid-glenoid notch and including the "anchor" of the biceps tendon to the labrum. We have labeled this injury a "SLAP lesion" (Superior Labrum Anterior and Posterior). There were 23 males and four females with an average age of 37.5 years. Time from injury to surgery averaged 29.3 months. The most common mechanism of injury was a compression force to the shoulder, usually as the result of a fall onto an outstretched arm, with the shoulder positioned in abduction and slight forward flexion at the time of the impact. The most common clinical complaints were pain, greater with overhead activity, and a painful "catching" or "popping" in the shoulder. No imaging test accurately defined the superior labral pathology preoperatively. We divided the superior labrum pathology into four distinct types. Treatment was performed arthroscopically based on the type of SLAP lesion noted at the time of surgery. The SLAP lesion, which has not been previously described, can be diagnosed only arthroscopically and may be treated successfully by arthroscopic techniques alone in many patients.

Accidental Falls↗
PubMed1990

Acute anterior cruciate ligament reconstruction. Analysis of complications.

One hundred fifty-six patients treated with intraarticular anterior cruciate ligament (ACL) reconstruction were analyzed to determine the incidence of complications. The study group of 31 patients (Group I) was treated with repair or reconstruction of an acute ACL injury. A comparison group of 125 patients had reconstruction for chronic ACL instability (Group II). The patients were evaluated clinically and by roentgenograms. The average follow-up time for the study group was 52.2 months. In Group I, 35% developed fibroarthrosis postoperatively that required arthroscopic lysis of adhesions and manipulation to restore motion. In Group II, only 12% developed this complication. However, developing this complication did not affect a patient's long-term clinical result when properly recognized and promptly treated.

Adolescent↗
PubMed1989

Glenohumeral instability.

Glenohumeral instability is an important cause of shoulder pain and disability in an active population. An awareness of the prevalence of recurrent instability, either in the form of dislocation or subluxation, is particularly useful in the assessment of the young athlete presenting with shoulder pain. Young adults presenting with rotator cuff tendinitis may have an underlying instability as the primary cause of their problem. A careful clinical examination should determine whether the instability is voluntary or involuntary, of traumatic or atraumatic onset, and the primary direction of the instability, as these factors have important implications with regard to treatment. Anterior glenohumeral instability is most common and the incidence of recurrent instability following on from an initial dislocation is high in the young active patient. An intensive rehabilitation programme is indicated for all initial dislocations or subluxations but surgery may become necessary after failure of conservative treatment. Care must be taken to determine accurately those patients with voluntary or multi-directional instability and a longer trial of conservative treatment is indicated here, as results of operative treatment in those cases are less favourable. Conservative treatment should be directed at strengthening the dynamic stabilizers of the shoulder joint, notably the rotator cuff muscles. Additional X-ray views are needed to demonstrate all the radiological changes associated with recurrent instability and further evaluation with examination under anaesthesia and arthroscopy is beneficial in the assessment of these patients. Arthroscopic surgery also has a role in the treatment of patients with symptomatic labral pathology and is now being used to perform stabilization procedures in selected cases. Many operative procedures have been described for stabilization of the shoulder and these should be directed at correcting the pathology present. Restoration of the patient's flexibility and strength postoperatively is essential, especially in the athlete in order to allow a full return to sporting activity.

Combined Modality Therapy↗
PubMed1989

Intraarticular versus intraarticular and extraarticular reconstruction for chronic anterior cruciate ligament instability.

One hundred twenty-seven patients were evaluated for the results of surgical stabilization in chronic anterior cruciate ligament instability. Eighty-four patients had been treated with intraarticular reconstruction alone, while 43 patients had been treated with a combination of intraarticular and extraarticular stabilization. Patients were evaluated by questionnaire to assess subjective and functional status by clinical examination of objective findings, and by roentgenograms and instrumented ligamentous stability testing. The follow-up interval averaged 45.2 months for the entire group (range, 24-90 months). Using a 200-point scale, the rating for the group treated with intraarticular reconstruction alone was 169.1, while the average rating for the group treated with combined intraarticular and extraarticular stabilization was 166.2. Overall, an excellent or good result was obtained in 67% of patients in the intraarticular only group and in 70% of the patients in the combined reconstruction group. There were no significant differences between the two groups in terms of changes seen on roentgenograms or in terms of residual laxity measured by instrumented testing. Thus, there is no demonstrable benefit derived from combined intraarticular and extraarticular stabilization procedures for chronic anterior cruciate ligament instability, provided that a well-placed intraarticular substitute of sufficient strength is functional.

Adolescent↗
PubMed1988

Sonographic evaluation of the rotator cuff: correlation with arthroscopy.

High-resolution real-time sonography has been reported as a non-invasive means of evaluating the integrity of the rotator cuff. Fifty-two patients underwent both sonographic and arthroscopic evaluation of the rotator cuff. There were 42 men and 10 women with an average age of 47 years (range 28-71 years). The duration of shoulder pain averaged 24 months (range 3 months to 9 years). Thirty-five rotator cuff tears were noted arthroscopically. Twenty-seven of the tears were diagnosed by sonography for a sensitivity rate of 77%. Eleven of the 17 intact rotator cuffs were normal by sonography for a specificity rate 65%. The overall accuracy of sonography was 73% and the predictive value of a positive sonogram was 82%. Sonography appears to be a good initial screening examination in evaluating the integrity of the rotator cuff. It is noninvasive and relatively inexpensive. Technical limitations of this technique as well as the experience of the radiologist in performing and interpreting the examination play a major role in the accuracy of this test. As instrumentation improves and as experience in using this technique increases, we expect the accuracy of sonography in detecting tears of the rotator cuff to continue to improve.

Adult↗
PubMed1988

Synovial chondromatosis of the acromioclavicular joint. A case report.

Synovial chondromatosis involving the acromioclavicular joint occurred in a 20-year-old woman. Synovectomy including removal of loose bodies and resection of the distal end of the clavicle relieved symptoms. Synovial chondromatosis is a relatively rare disorder and seems not to have been reported in the acromioclavicular joint.

Acromioclavicular Joint↗
PubMed1988

Reconstruction of the anterior cruciate ligament using a torn meniscus.

In eighty of 100 patients, reconstruction of the anterior cruciate ligament using a torn meniscus was successful in restoring stability. The length of follow-up ranged from two to six years and the mean interval from injury to operation was two years. Preoperatively, all but one patient had a positive (2+ or 3+) Lachman test and a positive pivot-shift test. Only ten patients had evidence of major instability, as seen on either test. The result was the same regardless of whether the patient had had a concomitant extra-articular (Ellison) procedure. The results of arthroscopic biopsy in eleven patients did not support the hypothesis that the meniscus underwent metaplasia to ligamentous tissue. Although this procedure yielded results similar to those of other procedures in which autogenous tissues are used to reconstruct the ligament, the meniscus should rarely, if ever, be used for reconstruction of the anterior cruciate ligament. The procedure is indicated only for patients who, in addition to needing reconstruction of the anterior cruciate ligament, also have a torn meniscus that would otherwise have to be totally excised.

Adolescent↗
PubMed1987

Failed arthroscopic meniscectomy: prognostic factors for repeat arthroscopic examination.

The authors have reviewed 44 patients retrospectively who failed arthroscopic partial meniscectomy. The study attempts to define the chances for success and to identify prognostic factors as these patients return for reoperation. Each patient had a repeat arthroscopic examination from 2 to 60 months after partial meniscectomy (average 19 months). They were reviewed an average of 31 months after reoperation (6 to 60 months), and each completed a subjective questionnaire evaluating the efficacy of their repeat arthroscopic surgery. Seventy-one percent of the patients had improvement with reoperation and were classified as good or excellent. Twelve patients (29%) did not improve and were rated poor. Ten parameters, as recorded before repeat arthroscopic examination, were investigated in an attempt to correlate each with success and to find those that are significant prognostic factors. Age of the patient, number of surgeries on the involved knee, time between arthroscopic examinations, nature of history (acute or chronic), workers' compensation or private insurance status, range of motion on physical examination prior to repeat arthroscopy, and degree of chondromalacia as seen at the first surgery were not found to correlate with the ultimate success of the patient. The presence of mechanical complaints before reoperation was a statistically significant parameter that led to a good or excellent result in 86% of the patients at follow-up. Lateral meniscal pathology seen at first partial meniscectomy gave more favorable results than medial meniscal pathology even if the patient had nonmechanical complaints. A history of reinjury between arthroscopic surgeries is helpful only if positive. In the absence of such a history, no conclusion can be drawn.

Adolescent↗
PubMed1987

Patellar instability: treatment by arthroscopic electrosurgical lateral release.

We reviewed the results of arthroscopic lateral release using electrosurgery in 39 patients (45 knees) with a history of recurrent patellar subluxation or dislocation. The average follow-up time was 28 months (range, 24-36). At follow-up, the patients had decreased swelling, instability, and pain. There was an improvement in flexion activities, sports participation, and overall functional ability. Only 20% of the knees had completely normal physical findings: 11.1% of the knees were rated as excellent; 64.4% were improved; and 24.5% were poor. Dislocators had more frequent poor results. The complication rate was 4.4%. There were no postoperative hemathroses. One patient was considered a surgical failure. The technique yields results comparable with those of open extensor realignment procedures and avoids the complications inherent to lateral release in general. The place for this procedure in patellar instability is well-documented.

Adult↗
PubMed1987

Conversion of xanthine dehydrogenase to oxidase in ischemic rat tissues.

In response to global ischemia, tissue xanthine dehydrogenase was converted to xanthine oxidase in all tissues with half-times of conversion at 37 degrees C of approximately 3.6, 6, 7, and 14 h for the liver, kidney, heart, and lung, respectively. The time course of enzyme conversion at 4 degrees C was greatly extended with half-conversion times of 6, 5, 5, and 6 d for the respective tissues. Increases in xanthine oxidase activity were accompanied by the appearance of a distinct new protein species with greater electrophoretic mobility. The oxidase from ischemic rat liver was purified 781-fold and found to migrate with a higher mobility on native gels than the purified native dehydrogenase. Sodium dodecyl sulfate profiles revealed the presence of a single major band of 137 kD for the native dehydrogenase, whereas the oxidase had been partially cleaved generating polypeptides of 127, 91, and 57 kD. Polypeptide patterns for the oxidase resemble those seen following limited in vitro proteolysis of the native dehydrogenase supporting a proteolytic mechanism for the conversion of xanthine dehydrogenase to oxidase in ischemic rat liver.

Animals↗
PubMed1987

Treatment of the anterior cruciate ligament-absent knee with associated meniscal tears. Instrumented testing and clinical evaluation of two patient groups.

The UCLA instrumented clinical testing apparatus was used to measure postoperative stiffness and laxity for two groups of patients with documented chronic absence of the anterior cruciate ligament (ACL) and associated meniscal tears. Group 1 consisted of 76 patients (average age, 25 years) who had undergone anterior cruciate substitution using the torn meniscus, and a second group of 34 patients (average age, 31 years) who had partial meniscectomy alone without ACL substitution. Subjective and objective evaluations were significantly higher and symptoms of pain and buckling significantly lower in the substitution group. In addition, 29% of Group 1 and only 7% of Group 2 patients were able to return to their preinjury sports without limitations, while 5% of the former and 12% of the latter could not return to any sport. At 90 degrees of flexion, there were no significant differences in stiffness or laxity between the patient groups. At 20 degrees of flexion and neutral foot rotation, the meniscal substitution group had an average of 1.4 mm less side-to-side laxity difference than the partial meniscectomy patients; 51% of the substituted patients still had an injured knee laxity that was at least 2 mm greater than the uninjured knee, as contrasted to 67% of the partial meniscectomy patients who exceeded this upper limit of the normal range. At 20 degrees, anterior stiffness of the injured knees of the substitution patients was 28% greater than the injured knees of the partial meniscectomy group; 42% of the substituted patients had an injured knee stiffness within the normal range, while only 18% of the partial meniscectomy patients fell within normal limits. There were no statistical correlations of stiffness or laxity values with clinical scores or patient symptomatology in either group.

Adult↗
PubMed1986

Nine-year functional nonunion of a femoral neck stress fracture: treatment with internal fixation and fibular graft. A case report.

Open reduction and internal fixation utilizing a full thickness fibular graft was performed on a patient who presented with a 9-year-old functional nonunion of a femoral neck stress fracture. During this period, the patient had remained fully ambulatory, with intermittent episodes of hip pain. Our experience indicates that the treatment of old, nonunited stress fractures of the femoral neck with a fibular bone graft and internal fixation contributes to a successful result, lending support while stimulating osteogenesis as the nonunion heals. Use of rigid internal fixation will eliminate motion at the site of the fracture, enhancing incorporation of the bone graft and, thereby, speeding the patient's recovery.

Adult↗