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Biomedical subjects

R F Warren

Publications and source records attributed to R F Warren.

At least 217 records · Page 12Linked to original sources

Patterns of meniscal injury associated with acute anterior cruciate ligament injury in skiers.

To determine if the incidence and patterns of meniscal injury associated with acute anterior cruciate ligament injury in skiers are different from those seen in individuals injured in nonskiing athletic activities, we reviewed the records of 150 patients with acute anterior cruciate ligament injuries. All patients had undergone arthroscopic evaluation within 21 days from the time of injury. There were 75 individuals who were injured while skiing and 75 individuals who sustained an injury in some other high-load athletic activity. Associated meniscal injury was documented at the time of arthroscopy and characterized by location, region, zone, depth, shape, size, and stability. Thirty-one of 75 skiers had an associated meniscal injury as compared to 47 of 75 of the nonskiers. This suggested a strong trend of decreased incidence of meniscal injury in the skier group, but the nonskiers had a higher incidence of major meniscal tears that required repair or partial meniscectomy. The location of the meniscal tear was also significantly different. The incidence of isolated lateral meniscal injury in skiers was higher than in nonskiers. There was a strong trend of increased incidence of medial meniscal involvement in the nonskiers than in the skiers. While there was no difference in the zone or region of tear between the two groups, the skier group was more likely to have a longitudinal tear of the posterior horn of the lateral meniscus. In both groups, lateral meniscal tears were more likely to require conservative treatment or partial meniscectomy while medial meniscal tears were more likely to be repaired than excised.

Adolescent↗

Static capsuloligamentous restraints to superior-inferior translation of the glenohumeral joint.

The purpose of this study was to determine the contributions of specific capsuloligamentous structures to restraining superior-inferior translation of the glenohumeral joint. Eleven cadaveric shoulders were tested using a four degrees-of-freedom test apparatus. The humerus was free to translate in three planes and free to flex and extend when a superior and inferior force of 50 N was applied. Testing was performed in three positions of abduction (0 degree, 45 degrees, and 90 degrees) and three positions of rotation (neutral, maximum internal, and external). Shoulders were tested intact, vented, and after division of specific capsuloligamentous structures. The primary restraint to inferior translation of the adducted shoulder was the superior glenohumeral ligament. The coracohumeral ligament appeared to have no significant suspensory role. With progressive abduction, the anterior and posterior portions of the glenohumeral ligament become the main static stabilizers resisting inferior translation: the anterior portion was the primary capsular restraint at 45 degrees of abduction, while the posterior portion was the primary restraint at 90 degrees of abduction, neutral rotation. Our results indicate that clinical assessment of glenohumeral translation in the superior-inferior plane should be performed in multiple positions of abduction and rotation.

Biomechanical Phenomena↗

Arthroscopic labral debridement. A three-year follow-up study.

UNLABELLED: This is a retrospective review of 40 patients who underwent arthroscopic labral debridement of the shoulder. All patients were active participants in sports involving use of the shoulder. All patients presented with shoulder pain. Only 40% were found to have distinct glenohumeral instability on examination. At surgery, all patients had labral injury. Ten patients had anterosuperior labral tears, 20 had anteroinferior labral tears or detachments, and 10 had posteroinferior labral tears or detachments. Outcome was assessed at a minimum of 2 years (average, 43 months) postoperatively. Overall, only 7% of the patients had significant symptomatic relief at followup. However, 72% noted relief of symptoms during the 1st year after surgery, but there was deterioration over time. CONCLUSION: Arthroscopic labral debridement is not an effective long-term solution for symptomatic relief in the overhead athlete.

Adolescent↗

The repair of osteochondral defects using an exogenous fibrin clot. An experimental study in dogs.

To evaluate the ability of an exogenous fibrin clot to hasten or optimize the repair of full-thickness articular cartilage defects, 4-mm diameter, full-thickness articular cartilage defects in 20 adult mongrel dogs were packed with an exogenous fibrin clot that had been prepared from each animal. The defects were created in a loaded and unloaded portion of the femoral trochlea. The healing response was then examined using routine histology at various intervals from 2 weeks to 6 months. Both the experimental (clot-filled) and control (empty) defects healed through a proliferation of fibrous connective tissue that eventually modulated into fibrocartilage. However, in the 2-, 4-, and 8-week animals, the experimental defects (both loaded and unloaded) demonstrated a more organized and advanced healing response than did the control defects. This difference was less pronounced in the 12- and 24-week animals. In all specimens, the clot-filled defects healed more uniformly than controls with less surface depression. In general, the unloaded sites were more uniform in healing than the corresponding loaded sites.

Animals↗

Anatomic considerations in harvesting the semitendinosus and gracilis tendons and a technique of harvest.

Although the semitendinosus and gracilis tendons have long been used in ligamentous reconstruction procedures of the knee, their anatomic relationships have not been explicitly detailed. Therefore, cadaveric dissections were performed on fresh-frozen adult knees to examine these relationships. Several key anatomic points are useful in the harvest of these tendons. Their conjoined insertion site is medial and distal to the tibial tubercle. They become distinct structures at a point that is farther medial and slightly proximal. Tendon harvest is facilitated by identifying the tendons proximal to this point. The superficial medial collateral ligament lies deep to the tendons in this area and should not be disturbed. The tendons are ensheathed in a dense fascial layer that may impede tendon stripping. The accessory insertion of the semitendinosus tendon (which was present in 77% of the knees dissected) should be identified and transected to avoid tendon damage at harvest. Knee flexion may reduce the risk of injury to the saphenous nerve as it crosses the gracilis tendon. Variation in tendon diameter affects graft strength.

Adult↗

The strength of the central third patellar tendon graft. A biomechanical study.

Thirty-seven bone-patellar tendon-bone composite grafts from the knees of 21 human cadavers were tested to failure. Average donor age was 28 years. The composites were divided into 4 groups: 3 groups with 10 grafts (5 pairs) and 1 group with 7 grafts from 6 donors. In Group 1 we tested 10- versus 15-mm wide grafts that were used without twisting; Group II, 10-mm wide grafts without twisting versus 10-mm wide grafts that were twisted 90 degrees; Group III, 10-mm wide grafts twisted 90 degrees versus 10-mm wide grafts twisted 180 degrees; and Group IV, 10- versus 7-mm wide grafts that were not twisted. The tests were performed using a newly described potting technique and clamp system and a servohydraulic testing machine with an elongation rate of 5 cm/sec. The results of this study suggest that the central third of the patellar tendon is stronger than previously reported. The mean ultimate load of a 15-mm bone-patellar tendon-bone composite was 4389 N (+/- 708); of the 10-mm wide composites, 2977 N (+/- 516); and of the 7-mm composites, 2238 N (+/- 316). Twisting the graft 90 degrees increased the strength (P < 0.05). Further twisting to 180 degrees had no significant effect compared with twisting 90 degrees. This study supports the practice of using smaller (10 mm) bone-patellar tendon-bone grafts to avoid the potential complications of patellar fracture and graft impingement in the notch.

Adult↗

The effect of joint-compressive load and quadriceps muscle force on knee motion in the intact and anterior cruciate ligament-sectioned knee.

To determine the effect of an externally applied joint-compressive load and a quadriceps muscle force on knee motion, we tested nine intact cadaveric knees and four knees after sectioning of the anterior cruciate ligament. Anteroposterior translation was measured at 0 degrees, 15 degrees, 30 degrees, 45 degrees, and 90 degrees of knee flexion after the application of an anteroposterior force of 100 N, a joint-compressive load of 0, 111, 222, 333, or 444 N, and a quadriceps force of 0 or 133 N. Both a joint-compressive load and a quadriceps force significantly decreased total anteroposterior translation by as much as 50% to 66% in intact knees and 42% to 71% in anterior cruciate ligament-sectioned knees. A substantial anterior translation was also found with the application of a joint-compressive load or a quadriceps force and no anterior force. We termed this translation an anterior neutral-position shift. The anterior neutral-position shift was significantly greater in the ligament-sectioned knees compared with the intact knees, so much so that at flexion angles greater than 15 degrees, the application of a 100-N posterior force could not translate the tibia to the most anterior position achieved in the intact knee with a 100-N anterior force.

Aged↗

An evaluation of the shoulder relocation test.

The purpose of this study was to evaluate the sensitivity, specificity, negative and positive predictive values, and accuracy of the shoulder relocation test in 100 patients who underwent shoulder surgery. Based on operative data and examination under anesthesia, the diagnoses were grouped into six categories: anterior instability (without cuff disease), posterior instability, rotator cuff disease (without associated anterior instability), acromioclavicular disorder, osteoarthrosis, and instability of the biceps tendon. The test was performed on the day of surgery by placing the arm in a position of 90 degrees of humerothoracic abduction and 90 degrees of external rotation (90 degrees/90 degrees). Patient responses of pain and apprehension (considered separately) were assessed in this position both with and without application of an anterior force to the proximal humerus. The relocation test assessed diminution of pain and apprehension after application of a posteriorly directed force to the proximal humerus relative to the position of 90 degrees/90 degrees alone and to the position of an anterior force being applied to the proximal humerus. Overall, 63 patients reported pain with 90 degrees/90 degrees; 74 reported pain when an anterior force to the proximal humerus was applied: the anterior instability group alone had 46 and 63 reports of pain, respectively; the rotator cuff group alone had 82 and 88 reports of pain, respectively. The only positive responses for apprehension were in the anterior instability group, of which 63% had apprehension with 90 degrees/90 degrees alone and 74 had apprehension when an anterior humeral force was applied.(ABSTRACT TRUNCATED AT 250 WORDS)

Evaluation Studies as Topic↗

Observations on the injury mechanism of anterior cruciate ligament tears in skiers.

The purpose of this study was to demonstrate the uniqueness of the injury mechanism for acute complete tears of the anterior cruciate ligament in recreational alpine skiers by using patterns of osseous injury as detected by magnetic resonance imaging. We treated 42 patients (average age, 32 years) who met the following criteria: 1) acute complete anterior cruciate ligament tear incurred during skiing, 2) no history of knee injury, 3) magnetic resonance imaging within 30 days of injury, and 4) arthroscopy and anterior cruciate ligament reconstruction or both for documentation of all intraarticular injury. An osseous injury detected by magnetic resonance imaging was seen in the lateral femoral condyle in 17 (40%) of the patients and was located over the terminal sulcus in 15 of these patients; only 1 had arthroscopic evidence of chondral injury. Four (10%) of the 42 patients had a bone bruise on the medial femoral condyle; all were located at the extreme posterior margin. Thirty-four patients (81%) had a bone bruise on the lateral tibial plateau; 33 were located at the extreme posterior margin and 27 of these were at the posterolateral tibial rim. Twelve patients (29%) had a bone bruise on the medial tibial plateau; all were located on the posterior margin.

Adolescent↗

Nonoperative treatment of acute anterior cruciate ligament injuries in a selected group of patients.

Conservative treatment of acute anterior cruciate ligament injuries was recommended to selected patients, including those with sedentary occupations, low athletic demands, or ages greater than 30 years. Patients with generalized hyperligamentous laxity were excluded. Fifty-five of 61 patients were available at an average followup of 46 months from the time of initial injury. At followup, giving-way symptoms had not occurred in 23 patients (42%); in 22 (40%) giving way occurred occasionally. Of the 44 patients involved in high- or moderate-demand athletics, 33 (70%) were able to continue with moderate-demand sports. Presence of a medial collateral ligament sprain did not affect the longterm function. Forty-eight percent of the patients scored excellent or good (9 and 18 patients, respectively) on the Hospital for Special Surgery ligament scoring system; 8 (15%) later chose surgical reconstruction. The remaining 47 patients did not believe that their symptoms were severe enough to warrant any further intervention. In a group of individuals who are older and relatively inactive, nonoperative management of anterior cruciate ligament injuries can yield satisfactory results, provided the patients are willing to accept a modest amount of instability and a slight risk of meniscal injury.

Acute Disease↗

Strategies for an anterior capsular shift of the shoulder. A biomechanical comparison.

We evaluated the effect of two different anterior capsular shift strategies on load-induced multidirectional glenohumeral motion. Nine cadaveric shoulders were tested on a special test apparatus in which three motions were constrained but which allowed simultaneous measurement of three translations: anteroposterior, mediolateral, and superoinferior. A simulated Bankart lesion was created by detaching the inferior glenohumeral ligament and labrum from the anterior glenoid from 5 mm superior to the anterior band of the inferior glenohumeral ligament to a point just posterior to the infraglenoid tubercle. The two types of medial-based anterior capsular shifts were performed sequentially using fixation via a transglenoid drill hole and No. 2 suture. One shift medialized the anterior capsule on the glenoid by 5 mm; the other one shifted the anterior capsule 5 mm superior on the anterior glenoid. Biomechanical testing was done in two positions of humeral elevation in the scapular plane, three positions of humeral rotation, and with an externally applied joint compression load of 22 N. Glenohumeral motion was measured in the intact state, after creation of the simulated Bankart lesion, and after each of the two anterior capsular shifts. Both the superior and medial shifts of the capsule decreased anterior glenohumeral translation to equivalent extents. For posterior and inferior translation at 45 degrees elevation, the superior shift significantly decreased translation to a greater extent than did the medial shift.

Aged↗

The role of the cruciate and posterolateral ligaments in stability of the knee. A biomechanical study.

The role of the posterolateral and cruciate ligaments in restraining knee motion was studied in 11 human cadaveric knees. The posterolateral ligaments sectioned included the lateral collateral and arcuate ligaments, the popliteofibular ligament, and the popliteal tendon attachment to the tibia. Combined sectioning of the anterior cruciate and posterolateral ligaments resulted in maximal increases in primary anterior and posterior translations at 30 degrees of knee flexion. Primary varus, primary internal, and coupled external rotation also increased and were maximal at 30 degrees of knee flexion. Combined sectioning of the posterior cruciate and posterolateral ligaments resulted in increased primary posterior translation, primary varus and external rotation, and coupled external rotation at all angles of knee flexion. Examination of the knee at 30 degrees and 90 degrees of knee flexion can discriminate between combined posterior cruciate ligament and posterolateral injury and isolated posterolateral injury. The standard external rotation test performed at 30 degrees of knee flexion may not be routinely reliable for detecting combined anterior cruciate and posterolateral ligament injury. However, measurements of primary anterior-posterior translation, primary varus rotation, and coupled external rotation may be used to detect combined anterior cruciate and posterolateral ligament injury.

Aged↗

Isolated closure of rotator interval defects for shoulder instability.

Fifteen patients noted at surgery to have an isolated defect in the rotator interval and no other pathologic abnormality underwent closure of the defect as an isolated procedure for recurrent instability symptoms. Intraoperative assessment of each of these shoulders after the closure demonstrated adequate stability, and no other stabilization procedures were performed. The average age of the patients was 24 years, and 10 of the 15 patients were women. Examination under anesthesia revealed increased inferior translation in all patients, as illustrated by at least a 1+ sulcus sign. The rotator interval defect averaged 2.75 cm in width and 2.3 cm in height. The rotator interval defect edges were freshened and approximated (nine patients) or imbricated (six patients), depending on the anterior capsular laxity and the degree of glenohumeral joint translation possible. Followup averaged 3.3 years (range, 2.2 to 5.3), and all patients achieved either a good or excellent result using the American Shoulder and Elbow Surgeons evaluation scale and the Rowe rating scale. Although most patients with a defect in the rotator interval require a standard stabilization procedure as a supplement to closure of the defect, approximation or imbrication of the defect as an initial step at surgery may confer adequate stability in selected patients and obviate the need for formal capsular advancement.

Adolescent↗

Reflex sympathetic dystrophy of the knee. Causes, diagnosis, and treatment.

Sixty patients with the diagnosis of reflex sympathetic dystrophy of the knee were evaluated retrospectively at our institution. The average followup was 2 years. Fifty-five (92%) patients treated with outpatient sympathetic blockade had resolution of the symptoms attributed to reflex sympathetic dystrophy. The time from onset of symptoms to initiation of treatment did not affect the ultimate outcome. The prognosis was most closely related to the presence or absence of an anatomic lesion that would continue to act as a painful stimulus. Eighty-one percent (29 of 36) of patients who had a significant anatomic lesion or surgical correction of a lesion had a complete resolution of their knee symptoms. However, only 21% (5 of 24) of patients with a persistent anatomic lesion in the knee had complete resolution. Fourteen patients required preliminary sympathetic blockade therapy before the underlying cause could be identified. This study emphasizes the need for establishing a precise diagnosis before contemplating any surgery of the knee, including arthroscopy. Arthroscopic procedures were the most common event precipitating reflex sympathetic dystrophy in this study.

Adolescent↗

The role of the popliteofibular ligament in stability of the human knee. A biomechanical study.

The popliteal tendon has a significant attachment to the fibula, the popliteofibular ligament. The role of this ligament in knee stability has not been determined. In this study we used selective cutting techniques to measure the static contribution of the popliteal tendon attachments to the tibia and the popliteofibular ligament for stability of the knee. Sectioning of all the posterolateral structures except the popliteal tendon attachments to the tibia or the popliteofibular ligament resulted in increased primary posterior translation, varus rotation, external rotation, and coupled external rotation. Although statistically significant, these increases were small. Sectioning of all the posterolateral structures resulted in larger increases in primary posterior translation, varus rotation, external rotation, and coupled external rotation. Our data indicate that the popliteal tendon attachments to the tibia and the popliteofibular ligament are important in resisting posterior translation and varus and external rotation. If an isolated injury to the posterolateral structures occurs, anatomic reconstruction of the major ligaments that restrain posterior translation and varus and external rotation may provide the best functional result. Reconstruction for isolated posterolateral instability should include anatomic attachment of the popliteal tendon to the tibia and the popliteofibular ligament.

Aged↗