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Biomedical subjects

B T Cohn

Publications and source records attributed to B T Cohn.

At least 19 recordsLinked to original sources
PubMed1997

Intraosseous gouty invasion of the talus.

A 34-year-old man presents with a cystic lesion of the talus that has developed over the last 3 years and a history of a single first metatarsophalangeal attack of gout. Radiodiagnostic studies confirmed the cyst and an associated osteochondritic lesion but showed no evidence of avascular necrosis. At arthroscopy, chalk-like material was removed from the cyst, which was histologically compatible with tophaceous gout. The lesion was debrided, and the patient was then treated with antihyperuricemic medication; radiographic evidence of cyst resorption was seen after 9 months of treatment.

Adult↗
PubMed1995

The effect of cold therapy on the postoperative course of total hip and knee arthroplasty patients.

Fifty total hip arthroplasty (THA) patients and 24 total knee arthroplasty (TKA) patients were randomized in a controlled study to examine the effects of cold therapy (via thermal blankets) in the postoperative period. The postoperative hospital stay was significantly shorter for the cold-therapy (50 degrees F) compared with control (70 degrees F) groups (by 1.4 days, P = 0.03) for THA patients. There was a similar but nonsignificant trend observed in the TKA groups (1.5 days shorter, P = 0.19). Total knee arthroplasty patients using cold therapy achieved independent ambulation an average of 1 day sooner than TKA control patients, but this difference did not reach statistical significance (P = 0.08). There were no statistically significant differences between the control groups or the test groups for both THA and TKA patients in narcotic usage, postoperative range-of-motion (ROM), or rate of progression of ROM.

Adult↗
PubMed1993

An effective technique for corticosteroid injection into the knee joint.

Local injection of a corticosteroid into the knee joint is a commonly used modality for the treatment of various inflammatory processes. Injection of these agents at the superomedial or superolateral poles of the patella have led to problems with pain and discomfort for the patients, as well as damage to the chondral surface of the patella. Injection through the patellar tendon can lead to side effects related to injection into the fat pad and into the anterior cruciate ligament. These problems can be avoided by using the inferomedial or inferolateral poles of the patella as a needle insertion site.

Adrenal Cortex Hormones↗
PubMed1992

The biomechanical effects of geometric configuration of bone-tendon-bone autografts in anterior cruciate ligament reconstruction.

This study provides biomechanical support for a new technique of autograft anterior cruciate ligament reconstruction featuring circular bone plugs and endosteal interference fit fixation. Six matched pairs of fresh frozen human knees were utilized. Femoral interference fit pull-out strength was determined from material-testing-machine-generated oscillograph recordings at a strain rate of 100%/s. Circular bone plugs, obtained with a circular oscillating saw, provided 19.9% greater interference fit pull-out strength compared with identically fixed trapezoidal bone plugs. Different geometric defects were compared in three- and four-point bending on an Instron machine with frozen patellae and an artificial bone composite. Circular defects have 107% greater strength than matched trapezoidal patellar defects in three-point bending. In a bone composite, circular defects are 53% stronger than triangular and 25% stronger in four-point bending than trapezoidal defects. A new technique of harvesting bone plugs with endosteal interference fit fixation is described and biomechanically supported. To date, this technique has been performed on over 500 cases clinically without evidence of patellar fracture or fixation failure. This study demonstrates the efficacy of this simple and reproducible technique compared with previously reported procedures.

Aged↗
PubMed1991

The effects of in situ freezing on the anterior cruciate ligament. An experimental study in goats.

We developed an in situ freeze-thaw model designed to simulate an ideally placed and oriented autogenous graft of the anterior cruciate ligament. In this model, the anterior cruciate ligament was exposed, and the femoral insertion, tibial insertion, and body of the anterior cruciate ligament were frozen in situ with specially designed freezing probes. Freeze-thaw cycles were repeated five times. We used the technique in thirty-three mature goats to study the biological and biomechanical outcomes of the devitalized and devascularized anterior cruciate ligament at zero, six, and twenty-six weeks after treatment. Thus, the collagen fibers of the simulated autogenous graft remain in normal anatomical position and the simulated graft is fixed under physiological tension. At twenty-six weeks, no statistically significant differences were noted between treated and contralateral control (untreated) ligaments relative to anterior-posterior translation, maximum force to rupture, stiffness in the linear region of the force-length curve, modulus of elasticity in the linear region, strain to maximum stress, or maximum stress. The only statistically significant difference was an increase in cross-sectional area of the ligament. This increase was 22 and 42 per cent greater than that in the control ligaments at six weeks and six months. At six months, the ligaments in the control group had an average mid-cross-sectional area of 17.7 +/- 1.2 square millimeters and the ligaments in the experimental group, 25.2 +/- 3.1 square millimeters. Changes in the size and density of the collagen fibrils also were demonstrated at six months. These observations are in sharp contrast to our previous studies of replacement of the anterior cruciate ligament, in which an allograft of the ligament or an allograft supplemented with a 3M ligament augmentation device (LAD; 3M, St. Paul, Minnesota) was used. In those studies, an average reduction in maximum strength of 75 per cent for the allografts and 50 per cent for the allografts that had a ligament-augmentation device was found at one year. We concluded that devitalized, devascularized anterior cruciate ligaments do not lose strength if the anatomical position and the orientation of the collagen fibers are not altered.

Animals↗
PubMed1990

A complication of interference screw fixation in anterior cruciate ligament reconstruction.

Bone-tendon autografts using patellar tendon are rapidly becoming the autogenous grafts of choice for anterior cruciate ligament reconstruction. Patellar tendon is the strongest type of available autogenous tissue, and it is easily adaptable to arthroscopically assisted techniques. Secure immediate fixation is critical for the success of this procedure. The Kurosaka screw has emerged as one of the most reliable graft fixation methods. Although we have enjoyed much success with the Kurosaka screw, the following case represents the first report of failure with this fixation technique.

Adult↗
PubMed1990

Approaches to senior care #9. Results of total knee arthroplasty in patients 80 years and older.

Experience with total knee arthroplasty in the extremely elderly population, which has not been previously reported, is reviewed. Sixty-two total knee prostheses were implanted in 43 patients aged 80 to 95 years (average, 82 years). Ninety percent of the patients had a preoperative diagnosis of osteoarthritis. The results were compared with those obtained in a younger reference group (average age, 62 years) receiving 60 total knee prostheses.

Aged↗
PubMed1988

Clinical experience with a triradiate exposure of the hip for difficult total hip arthroplasty.

A triradiate exposure of the hip was developed to facilitate the performance of certain difficult primary and revision total hip arthroplasties. Using this triradiate skin and fascial incision, complete anterior and posterior exposure of the hip capsule can be performed with relative ease. Between October 1980 and January 1985, this exposure was used 50 times in selected cases, including 9 of 320 (3%) primary total hip arthroplasties. All of these cases involved obesity, acetabular protrusion, and/or fragile femoral bone, conditions that would have made safe, adequate exposure without trochanteric osteotomy considerably more difficult through a routine anterolateral or posterior approach. Over this period, the majority of revision hip arthroplasties were performed using triradiate exposure; trochanteric osteotomy was routinely performed in these revision cases. Excellent wound healing was observed in every case, despite unfavorable factors such as advanced age, prednisone therapy, and the presence of prior incisional scars. The triradiate incision offers safe, controlled, and improved exposure in selected primary and revision total hip arthroplasties. It has become nearly the routine incision for the senior author for revision cases.

Aged↗
PubMed1988

Total articular replacement arthroplasty.

Surface replacement, popularized in the early 1970s has fallen into disfavor by much of the orthopedic community. To date, the authors' experience with 29 cemented total articular replacement arthroplasties (TARAs) in 25 patients has been quite favorable. Factors associated with these favorable results include: a physiologic age less than 60, good bone quality, viability of the remaining femoral head, and preservation of the acetabular subchondral plate. The mean age of cases in this study was 52 years, with patient follow up ranging between 3.5 and 7 years; there were two failures. Today, although conventional cementless total hip arthroplasty seems to be in vogue, real and potential problems exist. These concerns, in conjunction with the good results reported in this series, should encourage the orthopedic surgeon to take a second look at resurfacing arthroplasty, especially in the select group of patients defined in this article. Pending the long-term results of non-cemented prostheses the surgeon may even consider using cementless TARA components.

Adult↗