Biomedical subjects
Publications and source records attributed to A H Schmidt.
A case of antegrade nailing of the humeral shaft in a polytrauma patient was complicated by heterotopic ossification of the lateral deltoid muscle and severe loss of shoulder motion. The patient did not respond to physiotherapy alone and was successfully managed by excision of the heterotopic bone and adjunctive radiation therapy.
Visualisation of periacetabular osteolysis by standard anteroposterior (AP) radiographs underestimates the extent of bone loss around a metal-backed acetabular component. We have assessed the effectiveness of standard radiological views in depicting periacetabular osteolysis, and recommend additional projections which make these lesions more visible. This was accomplished using a computerised simulation of radiological views and a radiological analysis of simulated defects placed at regular intervals around the perimeter of a cadaver acetabulum. The AP view alone showed only 38% of the defects over all of the surface of the cup and failed to depict a 3 mm lesion over 83% of the cup. When combined with the AP view, additional 45 degree obturator-oblique and iliac-oblique projections increased the depiction, showing 81% of the defects. The addition of the 60 degree obturator-oblique view further improved the visualisation of posterior defects, increasing the rate of detection to 94%. Based on this analysis, we recommend using at least three radiographic views when assessing the presence and extent of acetabular osteolysis.
Patients with hip or pelvic fractures experience significant blood loss as a result of the fracture and from the surgery that subsequently is performed. The emergent and unplanned nature of fracture surgery precludes the use of preoperative blood donation and the optimization of chronic medical problems. Blood transfusion frequently is required to maintain adequate tissue O2 delivery in these injured patients. However, the administration of allogeneic blood causes other problems, including a well documented increase in the risk of infectious complications. Perioperative measures to minimize blood loss such as hypotensive anesthesia and red blood cell salvage are important, but often are inadequate to prevent the need for blood transfusion. Recently, erythropoietin therapy has been shown to stimulate hematopoiesis in patients with hip fractures. The authors discuss their experience with blood loss management in these patients with hip injuries, including aggressive Fe replacement therapy and the use of recombinant human erythropoietin.
Periprosthetic osteolysis is a well-described phenomenon associated with total hip arthroplasty. Two cases are presented in which apparently healthy patients developed lytic lesions adjacent to cementless hip implants. Despite atypical features, the lesions were initially attributed to wear debris-induced osteolysis, and it was discovered during revision surgery that metastatic tumor was present. For one patient, if the initial diagnosis had been correct, subsequent surgery and related complications may have been avoided. It is important to consider the entire differential of radiolucent bone lesions whenever a patient presents with periprosthetic osteolysis. If revision surgery is not warranted on the basis of loosening, then a thorough medical examination, close follow-up evaluation, and/or biopsy should be performed to rule out metastatic disease.
Forty-nine acute displaced tibial fractures (31 closed, 18 open: 5 Grade I, 7 Grade II, 4 Grade IIIA, and 2 Grade IIIB) were treated in 1 community with a standard operative protocol using a distractor without a fracture table, and an unreamed interlocked tibial nail. Forty-six fractures healed (94%). Complications included 3 nonunions (6%), 2 deep infections (4%), 9 delayed unions (18%), 4 angular malunions (8%), 2 rotatory malunions (4%), and 12 interlocking screws bent or broke (24%). Twenty-eight patients (57%) required at least 1 additional operation to obtain union, most commonly dynamization of a statically locked nail. The authors conclude that unreamed tibial nails provide adequate stabilization of displaced tibial fractures and can be used in the management of most open or closed tibial fractures. However, static locking is required in axially unstable fractures. Early dynamization or exchange nailing and bone grafting should be considered to hasten union and avoid screw failure. The distractor is an excellent adjunctive technique for reduction and alignment of tibial shaft fractures during intramedullary nailing.
The orthopaedic surgeon has a multitude of internal fixation devices and techniques available for use in the treatment of subtrochanteric fractures of the proximal femur. The successful use of second-generation locking nails is technically demanding. Close attention to positioning of the patient, reduction of the fracture, placement of the guide-wire, and insertion of the nail and of the proximal and distal locking screws is mandatory. The newer, high-strength hip-screws allow good fixation of a fracture that extends into the piriformis fossa. If medial comminution is present, this technique is best performed in conjunction with indirect reduction and bone-grafting. With proper technique, these devices allow the surgeon to manage predictably a complex subtrochanteric fracture that previously had to be treated with traction or extensive dissection and with (frequently inadequate) internal fixation.
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The intraoperative determination of bone viability is of fundamental importance in the surgical management of osteomyelitis. Recurrent infection will result from inadequate debridement, whereas reconstructive problems will be magnified by overzealous resections. The purpose of this article is to report the use of laser Doppler flowmetry (LDF) as a surgical adjunct allowing quantitative determination of bone viability in patients with osteomyelitis. Twenty-five patients with osteomyelitis underwent surgical debridement using LDF to assist with the intraoperative identification of necrotic bone and have been observed for at least 6 months. The LDF probe is placed directly on the bone and the output signal is channeled into an oscilloscope that calculates and displays the mean value of the signal in millivolts (mV). All patients underwent radical surgical debridement, including hardware removal if present and resection of nonviable bone. Bone debridement was continued when possible until LDF measurements in excess of 100 mV were obtained. Information regarding bone vascularity obtained with the LDF had a direct influence on the extent of bone debridement in all cases. The patients have been observed for an average of 16 months. No complications were associated with the use of LDF. All readings were pulsatile. Five patients had recurrence of infection. The average LDF reading following debridement for patients with recurrent infection was 72 mV, compared to 107 mV for patients without recurrence (p less than or equal to 0.025). All fractures were healed, although some required supplemental surgical management, including bone grafting or external fixation.(ABSTRACT TRUNCATED AT 250 WORDS)
Previous recommendations regarding the "safe" period of tourniquet hemostasis were based largely on studies of ischemia distal to the tourniquet. This study quantitatively analyzed skeletal muscle injury induced beneath and distal to a pneumatic tourniquet applied to the hindlimbs of rabbits for 1, 2, or 4 hours with a cuff inflation pressure of 125, 200, or 350 mm Hg. Technetium Tc 99m pyrophosphate incorporation after systemic injection (Tc 99 uptake) and correlative histology were used to evaluate tissue damage 2 days after tourniquet application. Compared with the contralateral control limbs, compression and ischemia induced statistically significant increases in Tc 99 uptake in the thigh and leg regions of all groups. Pyrophosphate incorporation was significantly greater in the thigh region than in the leg region after 2 hours of compression in the 200 and 350 mm Hg pressure groups and following 4 hours of compression in all pressure groups. Focal and regional fiber necrosis and degeneration were observed in thigh muscles after 2 hours of tourniquet compression. Two hours of continuous tourniquet application at clinically relevant cuff inflation pressures induced significant skeletal muscle necrosis beneath the tourniquet. Use of the lowest possible inflation pressure for a limited duration should minimize the degree of tissue injury caused by tourniquet application.
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OBJECTIVES: To determine if there are differences in healing, complications, or number of procedures required to obtain union among open and closed tibia fractures treated with intramedullary (IM) nails inserted with and without reaming. DESIGN: Prospective, surgeon-randomized comparative study. SETTING: Level One trauma center. PATIENTS: Ninety-four consecutive patients with unstable closed and open (excluding Gustilo Grade IIIB and IIIC) fractures of the tibial shaft treated with IM nail insertion between November 1, 1994, and June 30, 1997. INTERVENTION: Interlocked IM nail insertion with and without medullary canal reaming. MAIN OUTCOME MEASURES: Time to union, type and incidence of complications, and number of secondary procedures performed to obtain union. RESULTS: For open fractures, there were no significant differences in the time to union or number of additional procedures performed to obtain union in patients with reamed nail insertion compared with those without reamed insertion. A higher percentage of closed fractures were healed at four months after reamed nail insertion compared with unreamed insertion (p = 0.040), but there was not a difference at six and twelve months. More secondary procedures were needed to obtain union after unreamed nail insertion for the treatment of closed tibia fractures, but the difference was not statistically significant given the limited power of our study (p = 0.155). Broken screws were seen only in patients treated with smaller-diameter nails inserted without reaming, and the majority occurred in patients who were noncompliant with weight-bearing restrictions. There were no differences in rates of infection or compartment syndrome. CONCLUSION: Our findings support the use of reamed insertion of IM nails for the treatment of closed tibia fractures, which led to earlier time to union without increased complications. In addition, canal reaming did not increase the risk of complications in open tibia fractures.
Infection complicating internal fixation of fractures is a serious complication that is difficult to treat. Whenever metallic devices are implanted in vivo, successful biointegration requires that host cells colonize the highly reactive implant surface. Bacteria such as staphylococci can also become adherent to metallic or polymeric implants and will compete with host cells for colonization of the implant surface. Once adherent, these bacteria form a biofilm and undergo phenotypic changes that make them resistant to the normal host immune response as well as to antibiotics. Furthermore, metallic implants themselves cause specific deficits in the function of the local immune system that may render the host response to infection inadequate. Any associated soft-tissue injury causes even greater impairment of local immune function. Despite the potentially detrimental impact of internal fixation, fracture stability is of paramount importance in achieving fracture union and in preventing infection. It has been demonstrated in animal models that contaminated fractures without internal fixation develop clinical infection more commonly than similar fractures treated with internal fixation at the time of colonization. Because of the potential for infection whenever internal fixation is utilized, appropriate prophylactic antibiotic coverage for staphylococci and Gram-negative organisms should be provided. Open wounds and severely damaged soft tissues require aggressive management so that a viable soft-tissue envelope is maintained around the implant. Host factors such as smoking and malnourishment should be corrected. Early diagnosis and aggressive treatment of implant-related infection with antibiotics, debridement, and maintenance of stable internal fixation are essential to successful treatment.
Twenty-five patients with bladder exstrophy underwent pelvic osteotomy at or before initial bladder closure and anterior abdominal repair. Ten patients underwent bilateral iliac osteotomies before 1977. An alternative procedure consisting of bilateral superior pubic ramotomies has been used in 15 patients since 1977. In all patients, successful tension-free closure of the abdomen was achieved. Long-term follow-up of these two groups of patients shows no difference in the degree of pubic diastasis, which was asymptomatic. Posterior iliac osteotomy requires two additional incisions, longer operative time, and postoperative immobilization. We therefore recommend bilateral superior pubic ramotomy as an alternative procedure in initial reconstruction of the anterior abdomen in patients with bladder exstrophy.