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Biomedical subjects

P C Peters

Publications and source records attributed to P C Peters.

At least 19 recordsLinked to original sources
PubMed1992

Disease and specific considerations in total hip replacements.

Total hip replacement arthroplasty has evolved where multiple options may be provided to the patient depending on disease, age, activity level, bone quality, and bone geometry. For elderly patients, the hybrid hip (uncemented acetabular and cemented femoral components) is widely used. In the young active population, uncemented porous bone ingrowth designs predominate. Special considerations involving the total hip patient include management of blood loss anemia, prevention of infection, and prevention of heterotopic ossification. Autologous blood donation as well as collection and infusion of shed blood in the postoperative patient greatly minimize the need for homologous transfusions. Optimizing the surgical environment, meticulous and efficient surgical technique, and antibiotic prophylaxis continue to be the cornerstones of infection prevention. Nonsteroidal anti-inflammatory medication and radiation are effective means of preventing heterotopic ossification.

Adolescent↗
PubMed1992

Soft-tissue balance and alignment in medial unicompartmental knee arthroplasty.

We reviewed two similar groups of patients with medial osteoarthritis of the knee treated by unicompartmental arthroplasty. The group receiving an Oxford meniscal-bearing implant, with no medial release, showed significantly better mechanical alignment than that receiving a fixed-bearing implant. Under-correction, with its ominous mechanical implications, was much more common with the fixed-bearing design. Over-correction was rare and was seen in both designs about equally. Degenerative stenosis of the intercondylar notch was common and appeared to put the anterior cruciate ligament at risk of rupture, especially after correction of the varus deformity. We consider that postoperative leg alignment and soft-tissue balance after unicompartmental knee replacement are determined more by the implant design and the surgical technique than by any variation in soft-tissue contracture. Release of the medial collateral ligament is not necessary for realignment, but a generous notchplasty is often needed to allow normal anterior cruciate ligament function.

Follow-Up Studies↗
PubMed1992

Cortical strut allografts in the reconstruction of the femur in revision total hip arthroplasty. A basic science and clinical study.

Repeated total hip arthroplasties cause a loss of bone stock that will produce diminished component support, and can compromise implant function. There is, therefore, a compelling argument to return bone stock to the femur at the time of revision arthroplasty. Cortical strut allografts serve this purpose. They unite consistently and reliably, by 8.4 months on average. The overall rate of strut union is 96.6%. The sequence of healing events starts with round-off, followed by partial bridging and complete bridging. The repair process includes remodeling of the host femur, as well as the graft. Although there is variable resorption of some grafts, usually where not opposed to the host bone, there is also extension of others from host callus build-up such that, on average, there is no significant measurable loss of graft length or width. Most of the allograft struts, 78%, maintained a radiodense appearance. Clinical results of femoral revision with strut allografting have shown satisfactory end results compared with historic controls, with an average Harris score of 79.6 and a 2.7% subsidence rate. Of particular note is that the subsidence rate and clinical scores did not vary with the state of the preoperative femur, as has been shown repeatedly in the past. The canine model shows that the strut allografts are biologically active. Through mobilization of mesenchymal tissue, they are transformed into vascularized calluslike structures while maintaining good strength, and then further remodel to lamellar bone.

Animals↗
PubMed1992

Osteolysis after total knee arthroplasty without cement.

The prevalence and characteristics of osteolysis were studied after 174 consecutive total knee arthroplasties, performed without cement; 16 per cent (twenty-seven) of the implants (in twenty-six patients) were identified as being associated with osteolysis. The diagnosis was made an average of thirty-five months after the operation. Fifteen (56 per cent) of the twenty-seven prostheses were revised after an average of forty-five months in situ. The remaining twelve implants were still in situ five years or more postoperatively. In the patients who were managed with revision, six implants were judged to be stable radiographically and intraoperatively. The remaining nine implants were loose. The average age of the patients who had osteolysis was sixty-three years, and the average weight was seventy-six kilograms (168 pounds). Eighteen of the twenty-six patients who had osteolysis were women. The medial aspect of the tibial metaphysis was the most common site for resorption of bone (twenty-four knees). Sequential radiographs demonstrated progressive extension of the osteolytic process around the tibial base-plate of the prosthesis and distally into the tibial metaphysis along the screw-bone interface in all patients. Histological evaluation of tissue obtained at the revision procedures revealed sheets of histiocytes and occasional giant cells. Intracellular particulate polyethylene and metal were found; most particles were less than one micrometer in size, although particles as large as three micrometers were identified. Mechanical failure of the thin, modular, polyethylene tibial insert; excessive abrasion of the prominent polyethylene tibial eminence, with secondary wear and impingement of the pin on the femoral component; and failure of the metal-backed patellar component all contributed to the extensive amount of polyethylene and the variable amount of metal debris that were generated. Corrosion between the angulated titanium screws and the cobalt-chromium base-plate also contributed particulate metal to the osteolytic process locally. This study demonstrated that osteolysis occurs in association with cementless total knee replacement.

Adult↗
PubMed1991

Long-term patient survival after cystectomy for regional metastatic transitional cell carcinoma of the bladder.

The records of 280 patients who underwent pelvic lymphadenectomy and radical cystectomy for transitional cell carcinoma of the bladder between 1971 and 1986 were reviewed. A total of 42 patients had either 1 (stage pN1) or more than 1 (stage pN2) positive lymph nodes (20 and 22 patients, respectively). The over-all 3-year survival rate for patients with positive lymph nodes was 27%, and it was 30 and 18.5% for stages pN1 and pN2 disease, respectively. Kaplan-Meier survival curves revealed a sustained survival advantage for stage pN1 over pN2 disease for the first 3 years (p less than 0.05) but the difference was not significant at 5 years of followup. Eleven patients with negative lymph nodes but local extension of tumor into the prostatic stroma and/or ducts had a 5-year survival rate of 36%, which equaled the survival of 49 stage pT3b,pN0 cancer patients in the same series. Surgical mortality for the entire population of 280 patients was 2.1% and there was no increase in mortality or morbidity among the node positive patients. Based on the findings of improved survival of stages pN1 and pT3b,N0 cancer patients compared to stage pN2 cancer patients, the tumor, nodes and metastasis classification offers more specific prognostic information than does a single designation of Jewett stage D disease.

Adult↗
PubMed1990

Predictors of residual mass histology after chemotherapy for advanced testis cancer.

The records of 15 patients with Stage B3 or B2/C germ cell testis tumors who underwent full surgical debulking of a residual mass after completion of chemotherapy were reviewed retrospectively to look for predictors of residual mass histology. The density, character, and change in volume of the retroperitoneal mass on computerized tomography before and after chemotherapy were compared with the histology in the primary tumor and in the residual mass. One of 6 patients without teratoma in the primary tumor had a 97 percent reduction in the mass which contained residual teratoma. Two patients with residual seminoma had a 50 percent decrease in tumor volume, and both patients died of tumor progression despite salvage chemotherapy. Two patients with pure seminomas had only residual fibrosis in masses that decreased in volume by 77 and 75 percent, respectively. One of these masses was discrete and the other was diffuse. Seven of 9 patients (78%) with teratoma in the primary tumor had either teratoma (4 of 9, 44%) or carcinoma (3 of 9, 33%) in the residual mass, and the change in mass volume ranged from a 93 percent decrease to a 540 percent increase in size. All 7 patients with residual teratoma and/or carcinoma remain free of disease after observation or further chemotherapy. For the entire series, the mass density and character did not correlate consistently with the primary tumor or residual mass histology. Residual fibrosis alone or teratoma and/or carcinoma were seen with least (0 to 50%) and greatest (more than 90%) decreases in mass volume.

Adolescent↗
PubMed1989

Transurethral prostatectomy: immediate and postoperative complications. A cooperative study of 13 participating institutions evaluating 3,885 patients.

The mortality rate for transurethral prostatectomy was 0.2 per cent in 3,885 patients reviewed retrospectively. The immediate postoperative morbidity rate was 18 per cent. Increased morbidity was found in patients with a resection time of more than 90 minutes, gland size of more than 45 gm., acute urinary retention and patient age greater than 80 years, and in the black population. Of the patients 77 per cent had significant pre-existing medical problems. Operative mortality, significant morbidity and hospital stay were reduced in comparison to studies done 15 and 30 years ago.

Age Factors↗
PubMed1989

Transurethral prostatectomy: practice aspects of the dominant operation in American urology.

In a national survey of all American urologists transurethral prostatectomy accounted for 38 per cent of the major surgical procedures performed by the respondents. They regarded the operation as complex and they believe achievement of proficiency requires that more be performed during residency training than any other urological operation. Furthermore, they assigned transurethral prostatectomy a significantly higher relative value than have medical economists doing research in the field of physician reimbursement. The effect of recent legislated congressional reductions in the allowable Medicare fees for transurethral prostatectomy is discussed along with the impact of these reductions on urological patient care and the American urologist. Practice patterns and geographic variations in the costs of transurethral prostatectomy also are considered.

Adult↗
PubMed1989

Intraperitoneal rupture of the bladder.

Intraperitoneal bladder ruptures are usually injuries of violent deceleration, although spontaneous ruptures have occurred in near-term pregnancies. Once diagnosis is established by a static cystogram and withdrawal films, exploration of the abdomen and repair of the bladder rupture are indicated. Complications are usually from associated injuries and not from suprapubic drainage.

Drainage↗
PubMed1988

Can transabdominal ultrasound estimation of postvoiding residual (PVR) replace catheterization?

In 81 outpatients the postvoiding residual urine (PVR) using real-time B-mode ultrasonography (3.5 MHz transducer) was measured. For the calculation of the bladder volume the formula for an ellipsoid (V = 4/3 pi X r1 X r2 X r3) was found to be most accurate in predicting the actual volume measured by in-and-out catheterization (r = 0.982). Other volume formulas, using only one diameter of the bladder, were found to be much less accurate. For any arbitrary value of PVR, used in determining clinical management, the incidence of misjudgment by ultrasound was negligibly low. We conclude, that sonographic measurement of the PVR as a quick, noninvasive method, should replace catheterization, if the basic equipment is available. Additional information, e.g., prostate size, bladder configuration, diverticula, etc., can be obtained during the procedure without additional costs or loss of time.

Abdomen↗
PubMed1988

Financing residency training in urology.

Five educators concerned with changes occurring in the financing of medical education and care reviewed the present status of residency programs and their financing. Future support depends on political decisions as well as demonstrable needs. The effects of anticipated reductions in funding for residents and their programs may be countered by the development of alternative sources and the restructuring of present programs for more efficient operation. The need for leadership is clear.

Costs and Cost Analysis↗
PubMed1988

Complications of radical prostatectomy and lymphadenectomy.

The technique associated with nerve-sparing radical prostatectomy has improved the likelihood of continence, especially, and certainly potency over previous techniques. With a decline in these complications, patients and physicians in increasing numbers are choosing this surgical method of elimination of the disease. Hence this review of complications of radical prostatectomy using a modified lymphadenectomy and the nerve-sparing prostatectomy (or cytoprostatectomy).

Aged↗