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Biomedical subjects

Robert L Barrack

Publications and source records attributed to Robert L Barrack.

43 records · Page 3Linked to original sources
PubMed2002

Analysis of retrieved uncemented porous-coated acetabular components in patients with and without pelvic osteolysis.

Retrieved polyethylene liners and femoral heads from a consecutive series of revision components of one design were examined. All patients had Long-Term Stable Fixation (OsteoTechnology International, Timonium, Md) total hip arthroplasties (THAs) implanted between 1987 and 1992. The retrieved femoral heads and liners from patients with osteolysis were compared to those without osteolysis. Patients with osteolysis had significantly thinner polyethylene (5.1 mm versus 7.4 mm, P<.01 ) and a higher linear wear rate (0.5 mm/y versus 0.3 mm/y, P=.05). The average femoral head surface roughness also was significantly greater in patients with osteolysis (67 nm versus 35 nm, P<.05). Patients with osteolysis had more total volumetric wear, total linear wear, and volumetric wear rate compared to patients without osteolysis. Age, obesity index, time in situ, and cup inclination were not different between the two groups. Excessive polyethylene wear, probably accelerated by surface roughness of the femoral heads, was associated with pelvic osteolysis in these patients.

Arthroplasty, Replacement, Hip↗
PubMed2002

Revision total knee arthroplasty: fixation with modular stems.

The number of revision total knee replacements continues to increase annually. To date, much of the literature has focused on the performance of titanium revision systems. The primary aim of the current study was to review the mid term results of a contemporary revision knee system, with alternative design features. Ninety-one consecutive patients having aseptic revision total knee arthroplasty with one, modular all-cobalt chrome stemmed revision knee system using hybrid stem fixation were studied prospectively. Eighty-nine revisions in 84 patients were reviewed at a mean of 5.9 years (range, 4.1-8.6 years). Significant improvements in pain scores (15 +/- 14 to 38 +/- 14), function (40 +/- 24 to 53 +/- 29), range of motion (88 degrees +/- 23 degrees to 98 degrees +/- 18 degrees ), and total Knee Society score (85 +/- 40 to 132 +/- 40) were seen at followup. Five patients had revision surgery, with a Kaplan-Meier survivorship of 93.5% at 8.6 years. Intermediate results support the use of cobalt chrome components and hybrid cement fixation; however, this fixation in combination with high articular constraint requires continued monitoring.

Adult↗
PubMedDate not supplied

An examination of bias in shoulder scoring instruments among healthy collegiate and recreational athletes.

This investigation examined whether gender, activity level, hand dominance, or age displayed bias for 5 common shoulder scores among 120 healthy collegiate or recreational athletes. Data were collected for 5 instruments: Constant-Murley, UCLA rating, pre-1994 American Shoulder and Elbow Surgeons, Shoulder Pain and Disability Index, and Oxford. Normalized total and subscale scores and effect sizes were analyzed to determine how each demographic variable affected the scores. The normalized scores for the 5 instruments were not equivalent. The normalized total scores were significantly lower for the Constant-Murley score (P <.0001) compared with those for the other instruments. Men had significantly higher Constant-Murley scores, primarily because of the strength subscale. The Constant-Murley score also displayed gender and age biases. The other instruments had mostly negligible variance attributable to gender, activity level, hand dominance, or age. In the absence of a universal validated method, shoulder scoring instruments should be carefully chosen to match the population and the purpose of the study.

Adolescent↗
PubMedDate not supplied

Dislocation after total hip arthroplasty: implant design and orientation.

Implant design and positioning are important factors in maintaining stability and minimizing dislocation after total hip arthroplasty. Although the advent of modular femoral stems and acetabular implants increased the number of head, neck, and liner designs, the features of recent designs can cause intra-articular prosthetic impingement within the arc of motion required for normal daily activities and thus lead to limited motion, increased wear, osteolysis, and subluxation or dislocation. Minimizing impingement involves avoiding skirted heads, matching a 22-mm head with an appropriate acetabular implant, maximizing the head-to-neck ratio, and, when possible, using a chamfered acetabular liner and a trapezoidal, rather than circular, neck cross-section. Computer modeling studies indicate the optimal cup position is 45 degrees to 55 degrees abduction. Angles <55 degrees require anteversion of 10 degrees to 20 degrees of both the stem and cup to minimize the risk of impingement and dislocation.

Arthroplasty, Replacement, Hip↗