PubMed Health⌕ Search

Biomedical subjects

R L Barrack

Publications and source records attributed to R L Barrack.

126 records · Page 7Linked to original sources
PubMed1984

Proprioception of the knee joint. Paradoxical effect of training.

Two tests frequently used to measure joint proprioception were performed on the knees of twelve members of a professional ballet company to determine the effect of extensive athletic training on this sensation. These tests measured the threshold of perception of joint motion and the ability of a subject to reproduce a joint position. A healthy, active age-matched control group was also tested. Results show that dancers performed significantly better on the threshold test (p less than 0.05) and significantly worse when reproducing a joint position (p less than 0.05) than the control group. The strong implication is that athletic training can affect joint proprioception and that these two tests are in fact, dependent on different neural mechanisms.

Adult↗
PubMed1984

Retrieval and analysis of intramedullary rods. A follow-up study.

From 1980 to 1983, 16 AO intramedullary femoral rods were retrieved and analyzed clinically, radiographically, and metallurgically. Cracking and/or fracture was observed in four of the 16 specimens. All cracks occurred at the point of maximum stress at the end of the slot. In two cases a structurally weaker weld zone coincided with this location. The weld zone and slot were also found to coincide in five of the uncracked rods. Two of the four cracked rods were removed because of pain, while only three of the 12 uncracked rods caused pain. Structural and material characteristics (i.e., the location of the weld at a point of maximum stress and significant variability in microstructure), rather than surgical technique or time in situ, were found to be responsible for the implant mechanical failures. Improvements should be made in fabrication techniques and material properties. For the present, careful assessment of a painful intramedullary rod and routine removal after healing are advisable.

Femoral Fractures↗
PubMed1984

Age-related decline in proprioception.

Joint-position sense of the knee was measured in 29 subjects with normal knee joints ranging in age from 20 to 82 years. Joint-position sense was determined by two common techniques that measure the threshold to detection of motion and the ability to reproduce passive knee positioning. Joint-position sense was found to deteriorate with increasing age as measured by both tests, with a correlation coefficient that was significant at the p less than 0.001 level for each test. The two tests were found to correlate at the p less than 0.025 level, indicating that the same biologic parameter was being measured by both tests. Deterioration of proprioception, or joint-position sense, as measured may be a sensitive indicator of subclinical degenerative joint disease of the knee, as well as a means of quantitating proprioception in suspected neuropathic joints.

Adult↗
PubMed1983

Ambulatory function in total knee arthroplasty.

Through the use of gait analysis, this study attempts to characterize gait after total knee arthroplasty as a function of postoperative time to quantify the effectiveness of the surgery and to evaluate prostheses of several different designs. Gait analysis on 32 preoperative and 50 postoperative patients included measurement of velocity, cadence, stride length, and gait cycle. Postoperative data were collected at various intervals from 0.7 to 111 months after knee surgery (average postoperative time, 45.3 months). Linear regression analysis of velocity, cadence, stride length, gait cycle, and the ratio of contralateral to pathologic single limb support time as a function of postoperative time are reported with statistical error limits. Extrapolation of these results to zero postoperative time indicates that the patients who had had total knee arthroplasty had a slight improvement in all gait parameters compared to the preoperative control group. This was not statistically significant, however, except for cadence (P less than .05). Although velocity and stride length increased slightly toward more normal values with increased postoperative time, gait parameters at no time approached normal values.

Adult↗
PubMed1983

Effect of articular disease and total knee arthroplasty on knee joint-position sense.

Joint proprioception in the human knee has been studied using two previously described tests. Threshold of detection of slow, constant, passive motion and ability to reproduce angles to which the knee was passively placed were accurately measured. A group of postoperative total knee arthroplasty (TKA) patients were examined. All patients also had documented articular disease in the unoperated knee. Results were compared to age-matched controls. In addition, a young control group was studied for comparison to both groups. A significant difference was seen between the young control group and the older control group in both tests performed. Age-matched controls and the postoperative patients demonstrated an even greater difference. There was, however, no difference between the operated and unoperated knee among the TKA patients. It is concluded that joint proprioception declines to some degree with normal aging. A more marked decline is associated with degenerative joint disease. Total joint replacement, however, did not lead to a further decrease in sensation.

Age Factors↗
PubMedDate not supplied

Vibratory hypersensitivity in idiopathic scoliosis.

This study determined whether a significant difference in response to vibratory stimuli was consistently present in a large group of children with idiopathic scoliosis as compared with age-matched controls. Fifty-eight unselected adolescent females with documented progressive idiopathic scoliosis were studied along with age-matched controls. Threshold to detection of a vibratory stimulus was measured in both the right and left upper and lower extremities. Results indicated that highly significant differences existed between scoliotic children and controls at all sites tested (p less than 0.01), with scoliotic children being more sensitive than controls. The results support the presence of a central aberration in posterior column function that may be a primary etiology of idiopathic scoliosis.

Adolescent↗
PubMedDate not supplied

Functional performance of the knee after intraarticular anesthesia.

Ten healthy young volunteers underwent gait analysis and tests of knee joint position sense. Gait analysis included determination of stride characteristics (velocity, cadence, gait cycle, stride length, and single limb support time), force plate analysis, and motion analysis of the knee. The tests of joint position sense examined the ability of the subject to reproduce passive positioning of the knee and the ability to detect change in angle at the knee joint. In a double-blind manner, 10 cc of sterile fluid were injected into the left knee of each volunteer. Five received 2% lidocaine, the other five received sterile saline. All tests were then repeated. No statistically significant difference was observed in any measurement before and after injection in either test group. It is concluded that intraarticular anesthesia has no effect on gait pattern or joint proprioception as measured. Intraarticular local anesthesia is used in sports medicine to alleviate pain during arthroscopy of the knee under local anesthetic. The possibility of permitting damage in the early postoperative period due to loss of joint position sense is addressed in this paper. The results of this study suggest that injection of local anesthetic into a joint with an intact joint capsule does not compromise joint position sense as measured in this study. Furthermore, no change in gait parameters was observed in the functional task of ambulation. It must be noted that no conclusions regarding the loss of pain sensation can be made from the results of this study. Also, no conclusions regarding competitive activity can be drawn from this study.

Arthroscopy↗
PubMedDate not supplied

Exercise-related knee joint laxity.

Knee injuries are the topic of increasingly sophisticated research because of the importance in professional athletics as well as increasing participation in recreational sports. The role of conditioning and fatigue in these injuries remains controversial. Ligaments have high collagen content, and a viscoelastic response to stress would be expected. Because of the postulated relationship between laxity and knee ligament injuries, an experiment was designed using highly motivated athletes to test the hypothesis that exercise to the point of muscular fatigue may cause laxity of the knee and thereby place athletes at risk for ligamentous injury to the knee when fatigued. An exercise protocol was designed to produce muscle fatigue in the hamstring and quadriceps muscle groups. Knee ligament laxity was tested prior to and subsequent to the exercise protocol. To document muscle fatigue, isokinetic testing of right knee flexion and extension power was used several times during the exercise protocol. A knee arthrometer (KT-1000) was used to quantitatively document ligamentous laxity before and after exercise. The results indicated a significant lengthening in knee joint laxity between preexercise and postexercise in the left knee as measured at 15 and 20 pounds of passive displacement force (P less than 0.05). Maximum manual displacement also demonstrated a significant increase in joint laxity (P = 0.02). The right knee, which had undergone isokinetic testing, demonstrated a similar tendency but without a statistically significant difference before and after exercise. There was no significant preexercise side to side difference, but postexercise measurements demonstrated a left-right difference at 15 pounds, 20 pounds, and maximum manual displacement of statistical significance (P less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMedDate not supplied

Proprioception in the anterior cruciate deficient knee.

Proprioception was quantified in a group of patients who had documented complete ACL tears. Threshold to detection of passive change in position of the knee was measured using a well-described test. Eleven patients with arthroscopically proven complete ACL tears and findings consistent with moderate to severe anterolateral rotatory instability were tested. Testing was done within the 30 degrees to 40 degrees range of knee flexion. Patients were blindfolded and the injured and uninjured knees were tested in random sequence so that the normal knee could serve as an internal control. Testing was also done in a blind manner, i.e., the examiner did not know which knee had been injured. An age-matched control group underwent identical testing. Potentially significant variables such as age, time from injury, and degree of rehabilitation as measured by thigh circumference and isokinetic testing of the knee were included in a multivariate analysis. Control subjects demonstrated virtually identical threshold values between their two knees, the mean variation being less than 2%. The test group, however, showed a significantly higher mean threshold value for the injured versus the noninjured knee (P less than 0.01), the mean variation being over 25%. Multivariate analysis demonstrated that changes recorded in the proprioception of the injured knee were attributable to the loss of the ACL rather than to other variables. Patients who have complete ACL tears and moderate to severe rotatory instability may also experience a decline in proprioceptive function of their knee.

Adult↗
PubMedDate not supplied

The natural history of conservatively treated partial anterior cruciate ligament tears.

Twenty-five patients with arthroscopically proven partial ACL tears were reviewed. All patients underwent examination under anesthesia and arthroscopy following an acute injury to a previously normal knee. The percentage of tear was estimated during arthroscopy. Postoperatively, patients were treated with early motion and hamstring strengthening. Weightbearing and quadriceps rehabilitation were delayed. A detailed rating of symptoms and function was performed at a minimum of 18 months after injury, using a modification of the AOSSM ACL follow-up form. Neither the estimated percentage of ligament tear, length of followup, nor age at time of injury significantly correlated with clinical score at followup. Thirteen patients underwent partial meniscectomy at the time of original arthroscopy. Their clinical outcome was not different from those without meniscectomy. Two patients (8%) underwent ACL reconstruction 8 and 64 months after injury, respectively. Overall results were judged as excellent (28%), good (32%), fair (24%), and poor (16%). Only 44% were able to resume sports at their preinjury level, and 72% had activity-related symptoms.

Adolescent↗
PubMedDate not supplied

Arthroscopic treatment of transchondral talar dome fractures.

Fifteen cases of transchondral talar dome fractures treated arthroscopically at the Naval Hospital in Oakland, California, were reviewed. Roentgenograms and results from clinical examination were assessed preoperatively and at regular intervals postoperatively. Clinical followup of 18 months was obtained in all cases (range, 18 to 36 months; mean, 26 months). All lesions were treated with arthroscopic excision of fragments with abrasion and/or drilling of the remaining crater. There were nine excellent results, four good, one fair, and one poor. There were no complications. Results of arthroscopic treatment compare favorably to those of open arthrotomy.

Adolescent↗
PubMedDate not supplied

Arthroscopic treatment of symptomatic synovial plica of the knee. Long-term followup.

We studied all patients undergoing arthroscopic resection of symptomatic plica without other intraarticular abnormality at our institution from October 1981 to March 1987. To be considered abnormal, plicae had to be thickened and/or fibrotic when viewed arthroscopically. Seventy-six of nearly 2000 patients (4%) who underwent diagnostic arthroscopies met our inclusion criteria. Clinical response after arthroscopic resection was evaluated in 51 patients at an average of 47 months (range, 15 to 77). Excellent or good results were obtained in 57 (75%) of the patients. Eleven patients (14%) had an impingement lesion defined as a localized femoral condylar ridge or groove of the articular surface that impinged upon the plica with increasing flexion. All of these patients had an excellent or good result. Other factors associated with a favorable outcome included a specific preoperative diagnosis localizing symptoms to the medial compartment, onset of pain after a period of increased athletic activity or after a twisting injury, and younger age. Poor prognostic factors included associated chondromalacia and an unclear preoperative diagnosis.

Adult↗
PubMedDate not supplied

Return of normal gait patterns after anterior cruciate ligament reconstruction.

Individuals with anterior cruciate ligament deficiency typically do not have quadriceps activity during stance. This aberrant pattern has been termed "quadriceps avoidance" gait. We performed gait analysis during walking on 10 normal controls and 10 subjects 8 to 12 months after they had anterior cruciate ligament reconstruction using autogenous middle third of the patellar tendon. All patients had good subjective and objective results at the time of analysis. Differences in gait between subjects and controls persisted up to 12 months after surgery. Specifically, subjects with anterior cruciate ligament reconstructions demonstrated significant reductions in midstance knee flexion moments (P < 0.01) and tibially directed loading rates (P < 0.05) when compared with controls. However, the subjects had a net external flexion moment throughout most of the stance phase of gait, implying that quadriceps activity was present. After anterior cruciate ligament reconstruction, there is a tendency toward gait normalization, and a quadriceps avoidance mechanism is no longer present.

Anterior Cruciate Ligament↗
PubMedDate not supplied

Open versus closed chain kinetic exercises after anterior cruciate ligament reconstruction. A prospective randomized study.

We conducted a prospective, randomized study of open and closed kinetic chain exercises during accelerated rehabilitation after anterior cruciate ligament reconstruction to determine if closed kinetic chain exercises are safe and if they offer any advantages over conventional rehabilitation. The closed kinetic chain group used a length of elastic tubing, the Sport Cord, to perform weightbearing exercises and the open kinetic chain group used conventional physical therapy equipment. Results are reported with a minimum 1-year followup (mean, 19 months). Pre- and postoperative evaluation included the Lysholm knee function scoring scale, Tegner activity rating scale and KT-1000 arthrometer measurements. Overall, stability was restored in over 90% of the knees. Preoperative patellofemoral pain was reduced significantly; 95% of the patients had a full range of motion. The closed kinetic chain group had lower mean KT-1000 arthrometer side-to-side differences, less patellofemoral pain, was generally more satisfied with the end result, and more often thought they returned to normal daily activities and sports sooner than expected. We concluded that closed kinetic chain exercises are safe and effective and offer some important advantages over open kinetic chain exercises. As a result of this study, we now use the closed kinetic chain protocol exclusively after anterior cruciate ligament reconstruction.

Adolescent↗
PubMedDate not supplied

Evidence of reinnervation of free patellar tendon autograft used for anterior cruciate ligament reconstruction.

We studied six adult male dogs to determine whether free patellar tendon grafts show evidence of reinnervation when used for anterior cruciate ligament reconstruction. Histologic return of neural elements and return of a somatosensory-evoked potential defined evidence of reinnervation. Before removal, the native anterior cruciate ligament was electrically stimulated with a bipolar electrode and a somatosensory-evoked potential was recorded from a scalp electrode. The ligament was excised and reconstructed using an autogenous patellar tendon graft. Somatosensory-evoked potential was attempted immediately after reconstruction. Histology for nerve endings was performed on the native ligaments. Each animal underwent repeat arthrotomy 6 months later. The grafts were isolated and somatosensory-evoked potentials were attempted. An evoked potential was seen in all six dogs before reconstruction. No graft demonstrated a somatosensory-evoked potential acutely; however, 6 months postoperatively, the somatosensory-evoked potential returned in two cases. Histology of native ligaments showed that 25% of the 100 sections evaluated contained neural elements. Of the receptors present, 89% were mechanoreceptors and 11% were free nerve endings. Histologic examination of the graft tissue 6 months postoperatively revealed that all six grafts also contained neural elements. Mechanoreceptors and free nerve endings were present in approximately equal numbers in the grafts. The results of histology and somatosensory-evoked potential demonstrate that in at least some cases, free patellar tendon grafts show evidence of reinnervation when used for anterior cruciate ligament reconstruction.

Animals↗
PubMedDate not supplied

Patellar resurfacing in total knee arthroplasty.

Whether or not to resurface the patella when performing a primary total knee arthroplasty remains an open question. A number of recent studies have added new information relevant to this controversy. Anatomic studies show that there is normally substantial variability in the anatomy of the trochlear groove. Implanting a femoral component therefore results in a change in the surface topography of the knee in a high percentage of cases. Even though a number of intraoperative techniques have been described in an attempt to accurately reproduce femoral and tibial component rotation, studies of the application of these techniques reveal that component malpositioning or malrotation of a measurable degree occurs in 10% to 30% of cases, depending on the surgical technique and landmarks used. There has been substantial change in the design of both femoral and patellar components in recent years. Even with current designs, biomechanical studies indicate that some degree of change in kinematics and contact stresses occurs following total knee arthroplasty. However, the results of clinical studies have been extremely variable, with most showing either no difference or very little difference between resurfaced and nonresurfaced patellae in osteoarthritic knees. The decision to resurface the patella or not must be individualized on the basis of the surgeon's training and experience and an intraoperative assessment of the patellofemoral articulation.

Arthroplasty, Replacement, Knee↗
PubMedDate not supplied

Vibratory response in congenital scoliosis.

Vibratory studies were performed on 10 adolescent subjects being followed for congenital scoliosis. The average age was 12 years 4 months and the average curve was 32 degrees. Twenty-one age-matched controls underwent identical studies. Threshold to detection of vibratory stimuli in the upper and lower extremities was quantified. Results showed that the scoliotic subjects were consistently less sensitive than the controls in the lower but not the upper extremity. The occurrence of hyposensitivity in only the lower extremity of persons with congenital scoliosis implies that the sensory deficit is secondary to the spinal deformity itself rather than a primary etiologic factor.

Adolescent↗