Biomedical subjects

P St Pierre

Publications and source records attributed to P St Pierre.

7 recordsLinked to original sources

PubMed2000

Effect of ankle position fixation on peak torque and electromyographic activity of the knee flexors and extensors.

The purpose of this study was to examine the effect of ankle position fixation on peak torque (PT) and electromyographic (EMG) activity of knee-joint muscles during isokinetic testing. Twelve female athletes performed isokinetic knee flexion and extension at 60 degrees and 180 degrees/s under two conditions: with the ankle fixed in a position of plantarflexion and with the ankle fixed in a position of dorsiflexion. Bipolar surface electrodes were placed on the vastus lateralis, vastus medialis, biceps femoris, medial hamstrings, and the lateral head of the gastrocnemius for determination of the root mean square of the EMG (rmsEMG) and the median frequency of the EMG (mfEMG). No significant differences in knee extensor PT were noted in either ankle position for each velocity tested. Significant differences were noted, however, in knee flexor PT (p < 0.05) at both 60 degrees and 180 degrees/s, with the greatest PT observed with the ankle fixed in dorsiflexion. Neither quadriceps, hamstrings, nor gastrocnemius rmsEMG activity was affected by ankle position; however, there was a significant difference in mfEMG for the gastrocnemius, with higher frequencies observed with the ankle fixed in plantarflexion (p < 0.01). These results suggest that ankle position effects knee flexor PT during open chain isokinetic movements. The reason for decreased knee flexor PT with the ankle fixed in plantarflexion is probably due to the gastrocnemius muscle being in a too shortened position, thereby preventing it from effectively producing force at the knee joint.

Adult↗

PubMed1999

Posterior cruciate ligament injuries.

Treatment of posterior cruciate ligament (PCL) injuries has received renewed attention over the past few years. This article reviews the anatomy, natural history, and pathophysiology of posterior cruciate ligament injuries. Also described are the physical examination and proper imaging modalities used to diagnose the injury. Appropriate operative and nonoperative management methods are discussed.

Arthroscopy↗

PubMed1995

Tendon-healing to cortical bone compared with healing to a cancellous trough. A biomechanical and histological evaluation in goats.

This study was performed to test the hypothesis that attaching a tendon to a trough in cancellous bone results in tendon-healing that is biomechanically superior to that after direct fixation of a tendon to cortical bone. Twenty adult female goats were treated with a bilateral tenotomy of the infraspinatus tendon with subsequent reattachment of the tendon. In shoulders randomized to the cancellous-fixation group, a cancellous bed was prepared with a motorized burr and a template measuring twenty by five by five millimeters. The repair in the shoulders randomized to the cortical-fixation group was performed in the same manner, except that the tendon was attached to cortical bone. Three outcome measures were assessed, six and twelve weeks after the repair, with the Student paired t test and analysis of variance: load to failure, energy to failure, and stiffness. The types of repair were not significantly different with regard to any of the three outcomes. When the six and twelve-week data were combined, an average difference in load to failure of 3.9 per cent in favor of cancellous repair was observed but it was not significant (p = 0.78). The associated 95 per cent confidence interval for the difference ranged from 10.5 per cent in favor of cortical repair to 18.3 per cent in favor of cancellous repair. Histological analysis at six and twelve weeks revealed progressive maturation and reorganization of the bone-tendon interface with re-establishment of collagen-fiber continuity between the tendon and bone. This process was indistinguishable between the cortical and cancellous specimens. This study demonstrated no significant benefit from the creation of a trough to expose the tendon to cancellous bone. In this model, at both six and twelve weeks, the tendon-to-bone healing process of the two groups appeared similar and the biomechanical properties were approximately equal.

Analysis of Variance↗

PubMed1995

A prospective, randomized comparison of open vs arthroscopically assisted ACL reconstruction.

A prospective, randomized study comparing arthroscopic and open anterior cruciate ligament (ACL) reconstructions was undertaken. Neither the patients nor the physical therapists were made aware of which technique was used. The central one third of the patellar tendon with proximal and distal bone plugs was utilized as the graft material to reconstruct the ACL in all cases. Rehabilitation was identical for each group. The following variables were compared: postoperative pain score, operating time, estimated blood loss (EBL), quantity of analgesics used, complications, range of motion at 1, 3, and 6 months, a 6-month evaluation consisting of Lachman's, anterior drawer, and pivot shift tests, amount of thigh atrophy, and Cybex II tests. Statistical significance was achieved (P < .05) in only three parameters. The 1-month postoperative range of motion, the 6-month postoperative thigh atrophy, and the Cybex II test (knee extension at 60 degrees/sec) were statistically different favoring the arthroscopic method.

Adolescent↗

PubMed1995

Acute shoulder dislocation. Indications and techniques for operative management.

The acute management of the initial, anterior shoulder dislocation is dependent on the age and activity demands of the patient. After a thorough examination and appropriate radiographs, a gentle closed reduction is the initial treatment. Previous authors have recommended a period of immobilization followed by a rehabilitation program emphasizing rotator cuff strengthening. Restricting return to athletic activities to allow adequate soft tissue healing is also recommended. This will effectively treat the vast majority of patients with this injury. In patients older than 25 years of age, one would expect a relatively low recurrence rate, especially in patients with low activity demands or in patients willing to modify activity. In active, young patients desiring a return to strenuous activity, however, most studies and our own experience demonstrate high recurrence rates. In the authors' experience, the examination under anesthesia and arthroscopic evaluation have confirmed an avulsion of the anterior-inferior capsulolabral complex as the primary injury component. The special circumstances of an initial dislocation with a hemarthrosis and excellent tissue quality make it ideal for arthroscopic stabilization. Our early results are encouraging and we believe this approach is a viable option in the management of this common injury in young athletes. As arthroscopic techniques for glenohumeral instability improve, we would expect an improvement on these initial results. Acute operative stabilization for the initial anterior dislocation is considered for: (1) initial dislocation that requires a reduction; (2) a young, athletic, high demand patient (<25 years of age) who is unwilling to modify his lifestyle; (3) subjects with no prior shoulder subluxation or impingement history; (4) subjects with no neurologic injury; and (5) subjects with no greater tuberosity fracture.

Acute Disease↗

PubMed1990

Syndesmosis sprains of the ankle.

A retrospective review of the clinical records and radiographs of 1344 ankle sprains occurring over a 41-month period at the United States Military Academy was performed. The incidence and severity of these sprains did not differ significantly from other studies with the exception of those injuries involving the tibiofibular ligaments. Those patients sustaining incomplete injuries to the ankle syndesmosis had a recovery time of almost twice that of those patients with severe (3rd degree) ankle sprains (55 vs. 28 days). Eight of 13 patients with 10 of 15 incomplete syndesmosis injuries were available for follow-up examination and radiographs at an average time of 20 months postinjury (range of 7-39 months). All patients with this injury had a positive "squeeze test" (compression of the fibula to the tibia at mid-calf) at the time of initial examination. Nine of 10 patients developed ossification of the syndesmosis in follow-up radiographs. None of these patients had developed chronic ankle instability, loss of motion, or arthritic changes of the joint at the time of final followup.

Adolescent↗

PubMedDate not supplied

Femoral neck stress fractures in children and adolescents.

Five new cases of femoral neck stress fracture in children and adolescents are added to seven cases in the literature. All patients were involved in increased repetitive activity without evidence of violent trauma. Most fractures healed uneventfully with appropriate treatment. However, increased morbidity from displacement of the fracture, delayed union, nonunion, or avascular necrosis does occur in this age group and needs to be avoided. A delayed union healed after treatment in a spica cast; a nonunion and a displaced fracture healed after internal fixation. All patients returned to their previous level of activity. Our treatment algorithm addresses the unique differences associated with this injury in immature patients and allows for early diagnosis and treatment to prevent complications.

Adolescent↗