A comparison of University of Wisconsin and albumin solutions for donor liver preservation.
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Adenosine↗
Biomedical subjects
D C Mears
Publications and source records attributed to D C Mears.
Intraoperative somatosensory evoked potential monitoring of pelvic and acetabular fractures.
The efficacy of intraoperative somatosensory evoked potential (SSEP) monitoring was evaluated in the surgical management of 82 patients with pelvic and acetabular fractures. The injuries consisted of 45 acetabular fractures, 30 pelvic ring disruptions, and seven combined injuries. Preoperative neurological deficits were recorded in 34% of the study group (29% of those with an acetabular fracture and 47% of those with a pelvic ring injury). Three patients sustained an iatrogenic sciatic nerve injury during the study period (all of which were documented in the first 40 cases). Two patients sustained an exacerbation of an existing sciatic nerve injury. In the group of pelvic fractures, hazardous parts of the exposure, reduction, and fixation were identified by the SSEP monitoring. Removal of the provocative stimulus by the surgeon led to reversal of the SSEP abnormalities, and none of this group of patients sustained an iatrogenic injury. When the intraoperative SSEP changes were noted during an acetabular fracture fixation, immediate attempts were made to relieve the excessive tension on the sciatic nerve by replacing or removing a retractor, flexing the knee, extending the hip, or dividing the femoral insertion of the gluteus maximus. None of the SSEP changes were associated with the lacerative injury to the sciatic nerve. For the method to be clinically effective in reducing the incidence of neurological deficit, even subtle changes in the SSEP tracing must be recognized immediately by the neurophysiologist so that a corresponding corrective measure can be rapidly undertaken by the surgeon to remove the offending stimulus.
Acetabulum↗
Treatment of chronic infected hip arthroplasty wounds by radical debridement and obliteration with pedicled and free muscle flaps.
Nine patients with extensive wounds of the hip joint due to chronic infection following total hip arthroplasty or internal fixation of fractures of the femoral head and neck have been treated by serial radical debridements to remove infected bone, contaminated remnants of bone cement, and the surrounding fibrotic soft tissues. The resultant deep cavity extending down to the acetabulum has then been obliterated with either pedicled muscle flaps or free muscle flaps. Subcutaneous or transpelvic transposition of rectus abdominis muscle flaps is preferred for smaller defects, but only the free latissimus dorsi muscle flap provides sufficient volume of tissue to obliterate the more extensive hip defects. Systemic antibiotics have been continued only for a short-term course of 14 days postoperatively. There has been no recurrence of infection, with follow-up ranging between 6 months and 3 1/4 years. One patient has undergone reimplantation of a second custom hip prosthesis into the vascularized bed of a free latissimus dorsi muscle flap.
Adult↗
Three dimensional analysis of calcaneal fractures.
Thirty calcaneal fractures in 22 patients were evaluated by conventional radiographs, two dimensional computed tomography scans (2D CT) and three dimensional computed tomography reformations (3D CT). A special protocol for the reproducible procurement of high quality 3D CT scans was developed and is presented for the first time. Computer-generated three dimensional plastic models of fractured calcanei and videotaped presentations of fractured calcanei were made in selected cases. This study is the first to reproducibly demonstrate the usefulness of 3D CT scans in visualizing a calcaneal fracture. This information highlights the rotational displacement of major fracture fragments (multiplanar malrotation) and can facilitate the preparation of an appropriate surgical approach and reconstruction.
Adolescent↗
Lateral compression injury of the pelvis. A case report.
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Adult↗
Arthrodesis of the ankle and subtalar joints.
The late reconstruction of a complex nonunion of the distal tibial metaphysis, the ankle, or the subtalar joint was undertaken in five patients through a posterior surgical approach and the application of a blade plate into the os calcis. This technique was preferred as a salvage operation when the surrounding soft tissue envelope was compromised by the initial injury, previous surgical procedures, or infection. Each of the cases was notable for a segmental bone loss, an infected nonunion, or a collapse of the talar body. In the presence of a major soft tissue defect, the internal fixation was accompanied by the application of a microvascular free flap. The postoperative assessment of the posterior arthrodesis with the blade plate fixation was at an average of 33 months. Using a modification of the Boston Children's Hospital ankle scoring system, a preoperative and postoperative assessment was made. The criteria included an objective rating system based on the intensity of pain, the cessation of drainage, the degree of independent ambulation, and the roentgenographic documentation of union. The average preoperative score was 13 (range, 8-16). After arthrodesis, the average score was 44 (range, 40-48), with three patients rated excellent and two rated good.
Adult↗
Ankle arthrodesis with an anterior tension plate.
The incidence of complications associated with arthrodesis of the ankle has remained high, especially in wound complications and infections. A new method to achieve arthrodesis of the ankle that utilizes an anterior surgical approach and an anterior tension plate was assessed in 17 patients. This method transforms the potentially deforming force of the tendoachilles into a compressive and corrective force and facilitates realignment of the ankle in all planes. Also, dissection and subperiosteal elevation is minimized while soft tissue coverage of the hardware is maximized. Whereas the predominant preoperative diagnosis was posttraumatic degenerative joint disease, others included failed ankle arthroplasty, failed arthrodesis, and a fixed equinus deformity. A solid arthrodesis was achieved in 82% of the patients. Although complications occurred and two patients required reoperations, there were no problems with respect to wound healing or infection, which is a marked contrast to other series. This technique is recommended as a simple, safe, and effective method to achieve an arthrodesis of the ankle joint.
Adult↗
Canine pancreas and kidney transplantation following total-lymphoid irradiation.
The effect of total-lymphoid irradiation on survival of canine pancreas and kidney allografts was studied. TLI had a marked immunosuppressive effect as measured by in vitro immune responses and reduced circulating leukocytes. Despite the changes, median graft survival times for animals treated with 800 cGy (9 days) or 1800 cGy (9.5 days) were not significantly different from untreated control animals (7 days). The addition of low-dose antithymocyte globulin (10 mg/kg/day) on post-transplant days 0, 2, 4, 6, 8, and 10 had no measurable synergistic effect. Similarly, median segmental pancreas allograft survival times after 1700-2200 cGy of TLI treatment (16.5 days) were only marginally longer than those of untreated controls (9 days). The only animal to maintain a graft for greater than 200 days was matched to the donor in mixed lymphocyte culture (MLC). This animal was able to reject a third-party skin graft after 8 days while a graft from the original donor was still surviving after 21 days when the pancreas graft failed from a chronic-type rejection. These results indicate that TLI alone or in combination with ATG will not be predictably effective as a method of prolonging allograft survival. The role of matching major histocompatibility complex antigens in TLI treatment requires clarification.
Animals↗
Three-dimensional angio-computed tomography. New technique for imaging the acetabulum and adjacent vessels in a patient with acetabular protrusio.
An arterial injury is an infrequent but potentially lethel occurrence after primary or revision total hip arthroplasty complicated by an acetabular protrusio. Frequently, a plain radiograph and an arteriogram are used to assess the major arteries around the hip. The limitations of these techniques are well documented. A novel technique for documenting the spatial relationships of the external iliac and common femoral arteries to the acetabulum employs an arterial study combined with a three-dimensional computed scan. An angiocatheter is inserted by conventional radiographic technique and a standard computed scan with 3-mm sections is obtained and reconstructed to a three-dimensional image. The scan provides an accurate three-dimensional image of the osseous architecture and arterial images around the acetabulum. Even in the presence of a metallic arthroplastic component, the resolution of the three-dimensional angio-computed scan is sufficient to identify the external iliac artery adjacent to the pelvis.
Acetabulum↗
Distinguishing avascular necrosis from segmental impaction of the femoral head following an acetabular fracture: preliminary report.
To distinguish segmental impaction from avascular necrosis of the femoral head, 26 consecutive patients who sustained an acute displaced acetabular fracture were assessed preoperatively with routine radiographs, computed tomography, and radionuclide imaging using pinhole collimation and single photon emission computed tomography (SPECT). The diagnostic criterion for avascular necrosis was a photopenic defect of the femoral head, whereas, the criterion for segmental impaction was an area of impaction of at least 1 cm2 noted at the time of surgery. Of this series, 3 incurred a segmental impaction while 1 showed evidence consistent with avascular necrosis on SPECT imaging. None of the patients possessed diagnostic features of both complications. The distinction between these two complications of an acetabular fracture should contribute to the application of appropriate surgical techniques to correct segmental impaction and avascular necrosis.
Acetabulum↗
The "double barrel" free vascularized fibular bone graft.
A further modification of the free vascularized fibular bone graft is described in which a transverse osteotomy is made from the anterolateral aspect of the fibular shaft just distal to the entry of the nutrient artery. This produces two vascularized bone struts that may be folded parallel to each other but that remain connected by the periosteum and muscle cuff surrounding the peroneal artery and vein. The proximal strut is vascularized by both a periosteal and an endosteal blood supply, whereas the distal strut is vascularized by a periosteal blood supply alone. This so-called "double barrel" free vascularized fibular graft has been employed in three patients with segmental bone defects of the distal femur and in one patient with adjacent bony defects of the radius and ulna.
Adult↗
Posterior pelvic disruptions managed by the use of the Double Cobra Plate.
From five years of experience with 30 patients on whom the Double Cobra plate technique was employed for reconstruction of a variety of acute and late posterior pelvic injuries, this method appears to be highly suitable for effective stabilization of both sacral fractures and bilateral sacroiliac dislocations. With late presentations and larger individuals, associated anterior reconstruction of the pelvic ring is strongly recommended. The surgical complications have been sufficiently uncommon to recommend more widespread application of the protocol. Nevertheless, the potential for major complications, including life-threatening problems associated with pelvic reconstruction, should not be underestimated. These surgical techniques of internal fixation are potentially formidable undertakings that should be limited to those surgeons who possess appropriate training, instrumentation, and experience.
Adolescent↗
Acetabular fractures: three-dimensional computer tomographic imaging and interactive surgical planning.
Three-dimensional imaging can provide a valuable perceptual link between conventional radiographs and axial computed tomographic scans in the evaluation of complex acetabular fractures. With the 3D83 computer program, three-dimensional images can be generated to correlate with standard radiographic views. Unique images can also be created that offer perspectives unobtainable by conventional radiography. More sophisticated interactive techniques allow computer simulation of surgical approaches.
Acetabulum↗
Management of difficult lower extremity fractures and nonunions.
Difficult fractures and nonunions of the lower extremities are defined as compound fractures with soft-tissue loss, segmental bone fractures, and infected nonunions. A variety of methods for managing these defects are presented, including the use of modern fixation techniques and the application of highly vascularized bone and soft tissues. Vascularized bone grafts play a significant role in the treatment of difficult fractures that previously would have required amputation.
Adult↗
The role of free-tissue transfers in lower-extremity reconstruction.
Eighty-five free flaps were performed in 76 patients for defects in the lower extremity. A new classification of lower-extremity defects was devised to help define the role of free-tissue transfers: group 1, soft-tissue defects; group 2, soft-tissue and bone loss less than 8 cm; group 3, massive soft-tissue and bone loss greater than 8 cm; and group 4, bone defect only. Each group was further divided into clean (A) and infected (B) wounds. Our overall results include resolution of the presenting problem in 82 percent; there were 17 flap losses (20 percent), persistent osteomyelitis in 8, and 10 amputations. This review has prompted us to limit our indications for limb salvage, particularly in group 3B, in patients with compound injuries that include loss of plantar sensation, and in patients with large segments of infected bone.
Adolescent↗
Three-dimensional computed tomography of acetabular fractures.
Computer programs that produce 3D surface reformations from sets of contiguous axial CT scans were used in evaluating a variety of acetabular fractures in 20 patients. The 3D images were easily correlated with plain radiographs, and new views were produced that provided a unique perspective not obtainable by conventional radiography. The 3D images were useful in complex displaced fractures in cases in which the interpretation of plain radiographs was difficult. Plain radiographs and conventional CT scans were more sensitive than the 3D images in detecting undisplaced fractures.
Acetabulum↗
Fractures of the acetabulum.
A critical analysis of the results reveals the following major factors in determining the outcome of an individual acetabular disruption: The damage to the acetabular articular surface, which is reflected by the pattern of fracture and its degree of comminution, impaction, and osteoporosis, and associated damage of the femoral head The adequacy of the reduction, which is reflected by intraoperative inspection and postoperative radiographs The associated complications of the fracture and treatment (e.g., avascular necrosis, sciatic palsy, and heterotopic ossification) We recommend principles of treatment of acetabular fractures comparable to those employed for most other displaced intraarticular fractures, namely an anatomic reduction, stable internal fixation, and early motion, to realize reproducibly optimal results. The principal contraindications to open reduction are osteoporosis and generalized comminution to a degree that precludes a reasonable likelihood for the surgical team to achieve a stable anatomic reduction. We have provided guidelines for the surgical approach, techniques of reduction, and methods of fixation, and an analysis of results, which provide the basis for the successful treatment of these difficult intraarticular injuries.
Acetabulum↗
The results of 39 fractures complicated by major segmental bone loss and/or leg length discrepancy.
Thirty-nine fractures with segmental bone loss and/or limb length discrepancy with defects of 1.8 to 12.0 cm were reviewed retrospectively. Most patients presented with an acute open fracture with segmental bone loss or a late reconstructive problem with a nonunion, frequently complicated by infection, segmental bone loss, and adjacent soft-tissue disruption. One hundred forty-two weeks was the average length of time of treatment before referral of a patient to us. Eighty-eight per cent of the patients received a bone graft that included either autologous cancellous bone, bank bone, a vascularized free iliac crest or fibular transplant, or some combination of these materials. Forty per cent of the patients required some type of soft-tissue coverage such as a split-thickness skin graft, myoplasty, or a free vascularized flap. Seventy-nine per cent of the cases achieved complete osseous and soft-tissue healing within an average of 49 weeks. One patient underwent an above-knee amputation. Almost 80% of all of the patients healed to within 85% or better of anatomic length. Based upon these results a protocol for the management of osseous and soft-tissue defects is outlined which includes debridement, rigid stabilization, and various types of soft-tissue and osseous reconstruction.
Adolescent↗