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Biomedical subjects

P T Simonian

Publications and source records attributed to P T Simonian.

69 records · Page 4Linked to original sources
PubMed1993

Synthetic posterior cruciate ligament reconstruction and below-knee prosthesis use in Ehlers-Danlos syndrome.

Ehlers-Danlos syndrome (EDS) has been associated with irreparable arterial disruption, spontaneous and traumatic, necessitating amputation. Recurrent and chronic joint dislocation is a common component. Because of the very thin, hypermobile skin and "tissue paper scars," these patients would be expected to be poor candidates for the use of lower extremity prostheses. A review of the literature failed to show any reports of lower extremity prosthesis use in EDS patients or of recurrent and chronic joint dislocation treated by synthetic ligament reconstruction. The case of a 21-year-old woman is an example of both.

Adult↗
PubMed1991

Transient penetration of the hip joint during in situ cannulated-screw fixation of slipped capital femoral epiphysis.

Before the routine intraoperative use of fluoroscopy at our institution during procedures to stabilize a slipped capital femoral epiphysis, twenty-five patients (thirty hips) had in situ cannulated-screw stabilization of a slipped capital femoral epiphysis with use of biplane radiography. Thus, a permanent record of the procedure was available for review. Fourteen hips in fourteen patients had an intraoperative episode during which the joint was penetrated by the guide-pin assembly or cannulated screw, or both. This penetration was corrected at the time of the operation. Eleven patients were followed for a minimum of two years (mean, thirty-nine months; range, twenty-four to sixty-three months). All physes went on to closure. None of the patients had clinical or radiographic evidence of chondrolysis. Transient penetration of the hip joint did not lead to chondrolysis in this series. This suggests that a single episode of penetration by a pin or screw, with immediate removal from the joint, is not associated with the development of chondrolysis.

Adolescent↗
PubMedDate not supplied

Arthroscopic meniscal repair with fibrin clot of complete radial tears of the lateral meniscus in the avascular zone.

Peripheral lateral meniscal tears are amenable to arthroscopic meniscal repair. However, the posterolateral aspect of the lateral meniscus adjacent to the popliteus tendon is devoid of penetrating peripheral vessels and therefore difficult to heal. A complete radial split at this site is usually treated with total meniscectomy. We report five cases of a tear of the posterolateral aspect of the lateral meniscus anterior to the popliteus fossa. All patients had a radial split that extended to the popliteus tendon. In all cases, the repair was enhanced with a fibrin clot. Second-look arthroscopy showed that healing of the periphery occurred in all of the cases. All patients returned to their initial level of sports activity. Three of five patients were available for follow-up at an average of 71 months, and magnetic resonance imaging was performed at that time to assess the previously repaired meniscus. All menisci were fully healed and showed no further signs of degeneration. The ability of an exogenous fibrin clot to stimulate and support a reparative response in the avascular portion of the meniscus may represent a potential method of repair. Awareness of the relatively low healing potential of this zone and enhancement of healing opportunities should improve outcome.

Adolescent↗
PubMedDate not supplied

Interference screw position and hamstring graft location for anterior cruciate ligament reconstruction.

Anterior cruciate ligament reconstruction with hamstring tendon graft and interference screw fixation has recently been considered. Concerns for the use of interference screws with soft tissue grafts include damage to the graft during screw insertion, decreased fixation strength, and a decrease in the bone-tendon contact area for healing within the tunnel when the screw is placed in an eccentric position. This last concern could be addressed by placing the interference screw centrally between the four limbs of the hamstring graft. The purpose of this study was to determine the mode of failure, the pullout force, and graft slippage before graft fixation failure of hamstring tendons fixed with an interference screw positioned eccentrically in relation to the hamstring tendons verses an interference screw positioned centrally between the four graft limbs. The semitendinosus and gracilis tendons were harvested from six, fresh cadaveric specimens. Each tendon was divided into two segments of equal length. Both the semitendinosus and gracilis tendon segments were looped to form four strands. The specimens were then fixed with a bioabsorbable interference screw in the two different positions and pulled from a standardized polyurethane foam. All tendons in both groups failed by pulling out from between the interference screw and tunnel, regardless of the screw position. No tendon was cut by the screw in either group. There was no significant difference between the forces required to produce specific amounts of graft slippage between the two fixation techniques tested. There was no significant difference between the average total slippage at maximum pullout, 11.8 mm for the screw placed in the eccentric position and 13.7 mm for the screw placed in the central position. The maximum pullout force averaged 265.3 N for the screw placed in the eccentric position, and 244.7 N for the screw placed in the central position; these values were not significantly different. Placement of the interference screw in the central position did not compromise strength and it improves graft contact within the bone tunnel. Interference screw fixation, when applied against a bone plug, has been shown to consistently have a pullout force of more than 400 N.

Aged↗
PubMedDate not supplied

The use of noncontrast magnetic resonance imaging in evaluating meniscal repair: comparison with conventional arthrography.

The objective of this study was to investigate whether new and different specialized fast spin-echo techniques could be used to accentuate signal within the site of meniscal repair, obviating the need for intra-articular contrast. With the use of the frequency-selective fat suppression technique, we were able to accentuate fluid in the repair site because of the inherent extended dynamic contrast range of the technique. We performed a blinded study to correlate specialized magnetic resonance imaging (MRI) sequences with standard contrast arthrography, which was used as a standard of reference. Thirty-six patients (36 meniscal repairs) agreed to have MRI followed by contrast arthrography of the affected knee, irrespective of their clinical symptoms. We found that MRI had a very high correlation with arthrography in assessing meniscal repair, with statistical significance. In eight cases that had a second-look arthroscopy, we were able to see that MRI proved to be more accurate than arthrography in discriminating partial or complete healing. This is the first report to show that specialized noncontrast MRI sequences are more effective in evaluating the physiological state of the repaired meniscus, without artifactual distention of the joint recesses by contrast and air. Noncontrast MRI can obviate the need for arthrography in assessment of meniscal repair.

Adolescent↗
PubMedDate not supplied

Potential pitfall of the EndoButton.

A clinical and cadaveric example show the EndoButton (Acufex Microsurgical Inc, Mansfield, MA), used for anterior cruciate ligament endoscopic fixation, flipping outside the extensor mechanism or vastus lateralis rather than flipping directly outside the lateral femoral cortex. This pitfall was caused by overdrilling the femoral socket beyond the recommended 6 mm and overadvancing the EndoButton beyond the required depth to flip the EndoButton. Overdrilling the femoral socket to a depth of 10 mm still allows the EndoButton to rest properly on the cortex without soft tissue interposition. Increasing angles of knee flexion at the time of Endobutton placement decrease the safe distance beyond the lateral femoral cortex for flipping without soft tissue interposition. There is also potential to flip the EndoButton within the substance of the vastus lateralis, but the flipping action is blunted and not discrete.

Anterior Cruciate Ligament↗
PubMedDate not supplied

Anterior cruciate ligament injury and patella dislocation: a report of nine cases.

Nine patients had combined anterior cruciate ligament (ACL) disruption and patella dislocation and underwent surgical reconstruction of one or both of these injuries. Six patients had both the ACL reconstructed and the patella realigned, and three had only the ACL reconstructed. Associated injuries were present in eight cases; these included meniscal tears in eight patients and medial collateral ligament injuries in two of these same patients. At final follow-up, at an average 19.7 months, examination revealed an average grade 1A Lachman and no pivot on all patients who underwent ACL reconstruction. No patients had hypermobile patellae or apprehension. One patient had a 4 degrees loss of extension and none had a loss of flexion. Two patients had continued anterior knee pain at final follow-up; one of these patients was the same person who had a loss of extension. None had recurrent instability of the ACL and none had recurrent instability of the patella.

Adolescent↗
PubMedDate not supplied

Radiographic evaluation of glenohumeral kinematics: a muscle fatigue model.

The purpose of this study was to document the effect of muscle fatigue on glenohumeral kinematics. Twelve male volunteers without shoulder disease and with an average age of 27 years were studied. Glenohumeral anteroposterior radiographs were taken at 45 degrees intervals as the arm was abducted in the plane of the scapula from 0 degree to 135 degrees. This series of radiographs was performed both before and immediately after the subject performed a series of deltoid and rotator cuff fatiguing exercises. The average humeral head position or translation before and after muscle fatigue for each arm angle was compared. For all subjects, before fatigue, the position of the humeral head was below the center of the glenoid for all angles of abduction. There was essentially no change in position of the humeral head in the prefatigue state, as the arm was abducted from 0 degree to 135 degrees with no more than an average 0.3 mm of total humeral head excursion. After fatigue, excursion of the humeral head increased to an average of 2.5 mm between the tested positions. The position of the humeral head with the arm at 0 degree of abduction was lower or had migrated inferiorly compared with the rested state, with an average 1.2 mm significant increase in inferior translation. With the initiation of abduction, the humeral head demonstrated significant superior migration or translation in all positions tested. This result has important implications for conservative treatment of shoulder impingement and underscores the importance of rehabilitation to maximize the endurance and strength of the rotator cuff musculature.

Adult↗
PubMedDate not supplied

Periarticular fractures after manipulation for knee contractures in children.

We report two cases, each of which sustained two separate periarticular fractures from overzealous manipulation for knee contracture. The four fractures reported in this study involve one normal child sustaining asynchronous ipsilateral distal femoral and proximal tibial fractures and a child with the diagnosis of amyoplasia sustaining bilateral proximal tibial fractures. The child with knee contracture must be treated carefully and not exposed to overzealous physiotherapy or manipulation. The child who has developed a joint contracture secondary to lengthy immobilization may be at increased risk for periarticular fracture secondary to disuse osteopenia. The knee joint is at particular risk because of the long lever arm of the leg. These concerns should be conveyed to anyone involved in the patient's care, including the parents, therapists, nurses, and physicians. Passive range of motion in the child should never be painful. Normal children often can obtain maximal range of motion if left alone and not restricted.

Arthrogryposis↗
PubMedDate not supplied

Semitendinosus augmentation of acute patellar tendon repair with immediate mobilization.

We report four cases of acute midsubstance rupture of the patellar tendon that were treated with primary surgical repair along with semitendinosus autograft augmentation. The goal of this treatment was to allow immediate mobilization of the knee with a single operative procedure. We also demonstrate a technique for determining patellar position intraoperatively. Patients were tested for functional performance at an average final followup of 40 months (range, 20 to 66) including hamstring and quadriceps muscle strength evaluation, completion of a functional questionnaire, functional test performance, range of motion assessment, and patellar tendon length measurement. In evaluating the results, all cases were essentially identical to the nonoperated side, except one knee that had multiple associated ligament injuries. The multitude of injuries to this knee are likely the cause of the discrepancy. Immediate midsubstance patellar tendon repair with semitendinosus augmentation allowed immediate mobilization, which decreased the recovery period and improved the outcome of rehabilitation. Furthermore, a second surgery for hardware removal was not needed. These two factors--early and improved rehabilitation and the decreased chance of a second surgery--affect the cost of treatment of this injury. All isolated patellar tendon injuries in the study had excellent function at followup. For these reasons, we recommend this procedure for acute patellar tendon ruptures.

Adult↗
PubMedDate not supplied

Popliteomeniscal fasciculi and lateral meniscal stability.

In an attempt to understand better the contribution of the anteroinferior and posterosuperior popliteomeniscal fasciculi to lateral meniscus stability, we objectively evaluated the stability of the lateral meniscus before and after sequentially sectioning these fasciculi. In the biomechanical model, we attempted to account for the inherent limitations of arthroscopic evaluation of lateral meniscal stability. When the fasciculi were intact, the average lateral meniscal motion with a 10-N load was 3.6 mm. When the anteroinferior fascicle was disrupted, the average lateral meniscal motion with a 10-N load was 5.4 mm. The mean increase in motion from the intact state was 1.8 mm or 50%, which was significant. When both fasciculi were disrupted, the average lateral meniscal motion with 10-N load was 6.4 mm. The mean increase in motion from the intact state was 2.8 mm or 78% and from the single fascicle disruption state was 1.0 mm or 18%, both differences were significant. The meniscus did not become locked with any of these loading trials, and it spontaneously reduced to the original position when unloaded. Both fasciculi make significant contributions to meniscal stability. Even though the meniscus never became locked in the joint when loaded during this study, with the variable loads seen with normal activities mechanical symptoms might be expected when meniscal motion is almost double. An increase in lateral meniscal motion at the time of surgery may aid in the diagnosis of fasciculi disruption, despite normal meniscal structure on magnetic resonance images and at arthroscopic visualization.

Aged↗
PubMedDate not supplied

Different regional healing rates with the outside-in technique for meniscal repair.

Fifty-one patients with meniscal repair using the outside-in technique were reassessed with second-look arthroscopic procedures (N = 15), arthrographic examination (N = 41), magnetic resonance imaging (N = 36), or a combination of these techniques. Forty-one medial and 10 lateral menisci were repaired. The average clinical follow-up was 15 months (range, 3 to 80). Forty-five of 51 patients had tears that were located in or extended into the posterior horn of the medial or lateral meniscus. Complete healing occurred in 23 menisci (45%), partial healing was observed in 16 (15 medial, 1 lateral) (32%), and no healing occurred in 12 (24%). Remarkably, in all 15 patients who had tears extending from the posterior to the middle third of the medial meniscus that were partially healed, it was always the posterior third that had not fully healed. This finding is statistically significant. In addition, the middle third of these menisci had not fully healed in five patients. No healing occurred in the two patients with tears in the posterior third of the medial meniscus. Poor healing with the outside-in technique was observed in patients with tears into the posterior horn of the medial meniscus. For tears in the middle and anterior portion of the medial meniscus, as well as all lateral meniscus tears, the outside-in technique is our current method of choice.

Adolescent↗
PubMedDate not supplied

Contact pressures at osteochondral donor sites in the knee.

The purposes of this study were to determine whether any of the commonly recommended osteochondral donor sites are nonarticulating throughout a functional range of knee motion, and to determine the differential contact pressures for these sites. Ten commonly recommended sites for osteochondral harvest were evaluated with pressure-sensitive film through a functional range of motion with a model that simulated nonweightbearing resistive extension of the knee. All 10 donor sites demonstrated a significant contact pressure through 0 degree to 110 degrees of knee motion. The different color density measurements between donor sites were also significant. Although donor sites 1, 2, 9, and 10 demonstrated significantly less contact pressure than the sites with the greatest contact pressure, the difference in mean pressures was small. No osteochondral donor site tested was free from contact pressure. It is currently unknown whether articular contact at these osteochondral donor sites will lead to degenerative changes or any other problems.

Aged↗