Understanding the mechanism of ice binding by type III antifreeze proteins.

Type III antifreeze proteins (AFPs) are present in the body fluids of some polar fishes where they inhibit ice growth at subzero temperatures. Previous studies of the structure of type III AFP by NMR and X-ray identified a remarkably flat surface on the protein containing amino acids that were demonstrated to be important for interaction with ice by mutational studies. It was proposed that this protein surface binds onto the (1 0 [\bar 1] 0) plane of ice with the key amino acids interacting directly with the water molecules in the ice crystal. Here, we show that the mechanism of type III AFP interaction with ice crystals is more complex than that proposed previously. We report a high-resolution X-ray structure of type III AFP refined at 1.15 A resolution with individual anisotropic temperature factors. We report the results of ice-etching experiments that show a broad surface coverage, suggesting that type III AFP binds to a set of planes that are parallel with or inclined at a small angle to the crystallographic c-axis of the ice crystal. Our modelling studies, performed with the refined structure, confirm that type III AFP can make energetically favourable interactions with several ice surfaces.

Open fractures of the tibia in children.

Forty-one children who had forty-two open fractures of the tibial metaphysis or diaphysis were studied retrospectively. Twelve fractures were Type I; eighteen, Type II; six, Type IIIA; four, Type IIIB; and two, Type IIIC, according to the classification of Gustilo et al. All fractures were irrigated and debrided, and antibiotics were given for a minimum of forty-eight hours after the injury. Twenty fractures were initially treated with external fixation and twenty-two, with immobilization in a plaster cast. Three patients had an early infection of the wound, one of which was associated with osteomyelitis; all were successfully treated. The average time to healing of the fracture was five months (range, two to twenty-one months). The time to union was related to the severity of the soft-tissue injury, the pattern of the fracture, the amount of segmental bone loss, the occurrence of infection, and the use of external fixation. There were six delayed unions. Four patients had an angular malunion of more than 10 degrees, which spontaneously corrected in three. One patient who had a proximal metaphyseal-diaphyseal segmental fracture had a progressive valgus deformity. Four patients who had a severe fracture that was treated with external fixation had more than one centimeter of tibial over-growth. There were no amputations. The incidences of compartment syndrome, vascular injury, infection, and delayed union were similar to those reported for open tibial fractures in adults.

The natural history of conservatively treated partial anterior cruciate ligament tears.

Twenty-five patients with arthroscopically proven partial ACL tears were reviewed. All patients underwent examination under anesthesia and arthroscopy following an acute injury to a previously normal knee. The percentage of tear was estimated during arthroscopy. Postoperatively, patients were treated with early motion and hamstring strengthening. Weightbearing and quadriceps rehabilitation were delayed. A detailed rating of symptoms and function was performed at a minimum of 18 months after injury, using a modification of the AOSSM ACL follow-up form. Neither the estimated percentage of ligament tear, length of followup, nor age at time of injury significantly correlated with clinical score at followup. Thirteen patients underwent partial meniscectomy at the time of original arthroscopy. Their clinical outcome was not different from those without meniscectomy. Two patients (8%) underwent ACL reconstruction 8 and 64 months after injury, respectively. Overall results were judged as excellent (28%), good (32%), fair (24%), and poor (16%). Only 44% were able to resume sports at their preinjury level, and 72% had activity-related symptoms.

Proprioception in the anterior cruciate deficient knee.

Proprioception was quantified in a group of patients who had documented complete ACL tears. Threshold to detection of passive change in position of the knee was measured using a well-described test. Eleven patients with arthroscopically proven complete ACL tears and findings consistent with moderate to severe anterolateral rotatory instability were tested. Testing was done within the 30 degrees to 40 degrees range of knee flexion. Patients were blindfolded and the injured and uninjured knees were tested in random sequence so that the normal knee could serve as an internal control. Testing was also done in a blind manner, i.e., the examiner did not know which knee had been injured. An age-matched control group underwent identical testing. Potentially significant variables such as age, time from injury, and degree of rehabilitation as measured by thigh circumference and isokinetic testing of the knee were included in a multivariate analysis. Control subjects demonstrated virtually identical threshold values between their two knees, the mean variation being less than 2%. The test group, however, showed a significantly higher mean threshold value for the injured versus the noninjured knee (P less than 0.01), the mean variation being over 25%. Multivariate analysis demonstrated that changes recorded in the proprioception of the injured knee were attributable to the loss of the ACL rather than to other variables. Patients who have complete ACL tears and moderate to severe rotatory instability may also experience a decline in proprioceptive function of their knee.

Partial versus complete acute anterior cruciate ligament tears. The results of nonoperative treatment.

A study was undertaken to determine whether a significantly different clinical outcome could be expected following nonoperative treatment of acute partial anterior cruciate ligament (ACL) tears from that of complete tears. A detailed follow-up of 107 patients with arthroscopically confirmed tears was obtained; 72 were complete tears and 35 partial. The overall results in those with partial tears were 23% excellent, 29% good, 17% fair, and 31% poor; with complete tears the results were 11% excellent, 20% good, 15% fair, and 54% poor. The patients with partial tears had a lower incidence of associated meniscal tears, needed fewer reconstructions and more of them returned to sport than those with complete tears.

Arthroscopic surgery of the knee on the U.S. Naval Hospital Ships during Operation Desert Shield.

Between September 1990 and January 1991, while deployed to the Persian Gulf for Operation Desert Shield, 118 patients underwent arthroscopic surgery of the knee on the U.S. Naval Hospital Ships USNS Mercy and USNS Comfort. There were 113 men and 5 women, with an average age of 28 years (range, 19-59 years). The most common findings at the time of arthroscopy were meniscus tears (53%), anterior cruciate ligament tears (29%), and normal arthroscopic examinations (9%). There were three complications, two hemarthroses and one superficial portal site infection. Seventy patients (59%) were able to be returned to duty at an average of 6 days post-operatively, obviating the need to evacuate these patients out of the Middle East theater to Europe or the United States, thus avoiding additional delay, expense, and loss of the service member to his military unit.

Current trends in the treatment of femoral shaft fractures in children and adolescents.

Healthcare cost containment and a desire for early discharge of the pediatric patient to the home environment have become important factors in the treatment of femoral shaft fractures in children. As a result, newer techniques of treatment have become popular. The immediate hip spica cast remains the primary method of treatment for most children 6 years of age and younger. The treatment for children between the ages of 6 and 10 years is the most controversial. Many such patients may be treated successfully with immediate hip spica casts. However, external fixation and flexible intramedullary rod fixation are being used more frequently, particularly in patients with multiple trauma. The initial enthusiasm for rigid intramedullary rod fixation of adolescent femoral fractures has been tempered by recent reports of femoral head avascular necrosis. Avoiding the piriformis fossa during rod insertion may prevent this complication. Most children and adolescents with femoral fractures can be treated successfully with a brief hospital course without compromising care or outcome.

Sports injuries in children.

More children are participating in organized sports than ever before. Although improved coaching, equipment, officiating, and rules have been implemented to reduce injuries, a significant number of young athletes continue to be injured. Fortunately, most injuries sustained by young athletes are minor requiring only symptomatic treatment. However, because of the unique features of the immature skeleton, particularly the presence of open physes, these injuries can nonetheless result in permanent alteration of bone growth with long-term morbidity and disability. Furthermore, the prognosis and natural history of sports injuries in children may be different than that for similar injuries in adults. It is important that the practitioner dealing with young athletes be aware of the unique features of children's sports injuries so that proper treatment may be initiated and prognosis and expected outcome may be intelligently discussed with the patient and parents. This review provides current information regarding sports injuries in children by summarizing the most recent pertinent articles.

Computerized axial tomography of pelvic ring fractures.

The radiographs of all patients admitted to the Naval Hospital, Oakland with the diagnosis of pelvic trauma from 1981 through 1985 were reviewed. Thirty-one patients sustained single or double vertical ring fractures. Fifteen of these patients underwent both plain radiography and Computerized Axial Tomographic (CAT) scans in the evaluation of their pelvic injuries. The CAT scans of these pelvic injuries aided in detecting occult sacroiliac disruptions, determining the extent of posterior ring comminution, evaluating possible extension of the pelvic fractures into the acetabulum, assessing pelvic ring stability, and demonstrating soft-tissue injuries within the pelvis. Six pelvic injuries were diagnosed as single vertical breaks in the pelvic ring and nine were diagnosed as double vertical breaks in the pelvic ring by plain radiographs. CAT scanning demonstrated occult posterior ring disruptions in four patients which led to the reclassification of their injuries to double vertical fractures. CAT scanning also demonstrated significant degrees of sacral comminution in five patients which altered surgical treatment plans in all five patients. Two fractures were classified as unstable based on marked sacral comminution demonstrated on CAT scan. Extension of the pelvic ring fractures into the acetabulum was suggested on plain radiographs in three patients and was excluded by review of the CAT scans in these patients. Significant intrapelvic hematomas were demonstrated in three patients and urine extravasation into the hip joint from a bladder laceration was seen in one patient with the CAT scan.(ABSTRACT TRUNCATED AT 250 WORDS)

Intraosseous lipoma of the ilium. A case report.

Intraosseous lipoma is the rarest of the benign primary tumors of bone. It occurs most often in the metaphysis of long bones and is usually identified as an incidental roentgenographic finding. A 53-year-old man demonstrated a mass in his buttock and a lytic lesion of his ilium. Preoperative computed axial tomography (CAT) scanning was helpful in establishing its anatomic boundaries and the cellular composition of the mass. The CAT scan demonstrated the tumor extending anteriorly and posteriorly through the ilium and having a uniform soft tissue density with the same attenuation as adipose tissue. The patient was successfully treated with a marginal excision of the tumor. An intraosseous lipoma seems not to have been previously reported to involve the ilium or be associated with significant extension into soft tissue.

Coccidioidomycosis of the first cuneiform: successful treatment utilizing local debridement and long-term ketoconazole therapy.

Although intravenous amphotericin B is generally considered to be the standard treatment for coccidioidomycosis, the treatment of monostotic coccidioidomycosis is controversial. Long-term intravenous and oral antifungal chemotherapy has been utilized alone and in conjunction with local surgical debridement. We present a case of coccidioidal osteomyelitis of a tarsal bone successfully treated with local surgical debridement and oral ketoconazole and propose clinical guidelines for selecting the proper chemotherapeutic agent and for following the efficacy of the treatment regimen.

Surgical failures in the management of pelvic floor relaxation.

There are a vast number of operations for the correction of symptomatic pelvic floor relaxation, and the pelvic surgeon is faced with a difficult task in selecting the most appropriate procedure(s) for an individual patient. A successful outcome not only depends on the surgeon's skill and operative technique, but also relies heavily on the preoperative recognition and evaluation of factors related to surgical failure. Most importantly, careful attention to all components of the pelvic floor will allow the surgeon to tailor an operation to the individual's particular needs. Awareness of the many pitfalls of pelvic reconstructive surgery should lead to the appropriate preoperative evaluation and patient counseling, thus ensuring the best opportunity for a favorable outcome.

The acetabulum in congenital and neuromuscular hip instability.

Acetabular morphology in congenital and neuromuscular hip instability was evaluated with computed tomography (CT) and plain radiography. Thirty-three unstable hips in 27 children with congenital hip dysplasia, cerebral palsy, or spina bifida were studied. Fourteen normal hips in 14 children served as controls. Unstable hips in the children with congenital hip dysplasia demonstrated anterior and superior acetabular deficiency with increased acetabular anteversion. Global deficiency was present in acetabuli of cerebral palsy and spina bifida patients with anterior, posterior, and superior deficiencies. The acetabuli in cerebral palsy patients had significant posterior deficiency and were the shallowest of the groups evaluated.

Osteotomy of the proximal tibia in the treatment of adolescent tibia vara.

Between 1983 and 1990, 9 patients with 13 involved lower extremities had proximal tibial osteotomies for the treatment of adolescent tibia vara. Average age at the time of onset was 11 years, 8 months. All patients were black and obese. The interval between awareness of the bowleg deformity and presentation averaged 1.7 years. The mean preoperative tibiofemoral angle was 13 degrees varus. Stabilization was achieved by external fixation (6 extremities), crossed pins (4 extremities), or staples (3 extremities). One patient with bilateral deformity experienced multiple postoperative complications including osteomyelitis and recurrent varus deformity at the osteotomy sites, both successfully treated. Another patient had recurrence of the varus deformity and a leg-length discrepancy secondary to early closure of the medial proximal tibial physis. At an average follow-up of 4 years, two patients complained of occasional pain; none complained of pain that restricted normal activities. The mean improvement in the tibiofemoral angle at follow-up was 20 degrees, with a mean tibiofemoral angle of 6 degrees valgus. Overall, there were 10 good, no fair, and 3 poor results.

Stress fractures of the femoral diaphysis in young children. A report of 2 cases.

Stress fractures of the femoral diaphysis in young children are rare. Pain and an antalgic gait are the most common features. There is usually no history of either trauma or a recent increase in physical activities. Initial radiographs may be normal. Technetium bone scanning is the most sensitive method of early diagnosis, but may not be diagnostic. Computed tomography and magnetic resonance imaging are useful in early confirmation of the diagnosis. Serial radiographs will show maturation of the periosteal new bone with evidence of repair. Biopsy should be avoided, except in cases of obvious neoplasm shown by computed tomography or magnetic resonance imaging, or in cases with progressive cortical destruction shown on serial radiographs, because fracture callus may be difficult to distinguish from osteosarcoma. Treatment consists of protected weight bearing and activity restriction until resolution of symptoms and radiographic evidence of healing.

Malignant neuroepithelioma (peripheral neuroblastoma). A case report.

Malignant neuroepithelioma is a rare neoplasm arising within the peripheral nervous system. It usually occurs in the lower extremities and may involve patients in any age group. In children younger than the age of five years, the tumor must be differentiated from a metastatic neuroblastoma; in adolescents and adults the tumor must be distinguished from other malignant round-cell tumors. The poor prognosis and the need for aggressive, combined surgical and chemotherapeutic modalities in treating this tumor necessitate a prompt and accurate diagnosis.

Scapular osteomyelitis. An unusual complication following subacromial corticosteroid injection.

Impingement syndrome is a common disorder of the shoulder. Most patients respond to conservative treatment consisting of rest, ice/heat, anti-inflammatory agents, and physical therapy. Subacromial corticosteroid injection may be used when other forms of conservative treatment fail. A case is reported involving a 29-year-old man who developed scapular osteomyelitis following subacromial corticosteroid injection. Successful treatment consisted of surgical debridement followed by a combination of intravenous and oral antibiotic therapy. Strict adherence to aseptic technique is emphasized for performing subacromial corticosteroid injection.

Analgesia for the reduction of fractures in children: a comparison of nitrous oxide with intramuscular sedation.

A prospective, randomized study was undertaken to compare the effectiveness of nitrous oxide with intramuscular sedation (meperidine and promethazine) in providing analgesia and amnesia during the reduction and treatment of children's fractures in an outpatient clinic setting. Fifteen patients received a 50:50 mixture of nitrous oxide and oxygen, and 15 received intramuscular injection. The two groups were similar in regard to gender distribution, age, and fracture types. Pain response was recorded using the Children's Hospital of Eastern Ontario (Canada) Pain Scale (CHEOPS) at the time of fracture reduction and 30 min postreduction. At the first follow-up visit a questionnaire regarding the patient's memory and subjective experience of the fracture reduction was answered. Data between the two groups were compared using the Mann-Whitney test. The CHEOPS scores, and the memory and subjective experience of the fracture reduction were similar between the two groups. Time in the outpatient department averaged 83 min for the intramuscular group and 30 min for the nitrous oxide group (p < 0.01). All of the nitrous oxide patients stated they would use nitrous oxide again, whereas only eight of 15 intramuscular patients stated they would try intramuscular sedation again. Nitrous oxide is as effective as intramuscular sedation in providing analgesia and amnesia in the treatment of children's fractures while having a more rapid onset and a shorter recovery period with greater patient acceptance.

Arthroscopic treatment of acute patellar dislocations.

Twenty-nine patients treated with arthroscopy alone for acute patellar dislocation were reviewed. All had a significant traumatic episode with hemarthrosis in a previously asymptomatic knee. Clinical follow-up averaged 25 months (range 5-64 months). Fifteen patients had concomitant percutaneous lateral release (LR). Significant-sized osteochondral defects not radiographically visible preoperatively were discovered in 40%. Fragments were excised and corresponding craters debrided or abraded. Additional intraarticular pathology discovered included two meniscal tears and one anterior cruciate tear. Overall excellent (E) and good (G) results were 83%. The recurrence rate was 14%, all of which occurred in the LR group. All recurrent dislocations occurred within 1-year post injury. The LR group had 73% G and E results compared with 93% in those without LR. Arthroscopy followed by immobilization was an efficacious approach to acute traumatic patellar dislocations in this specific group of patients. The addition of LR with early motion, however, detracted from the results.

Advanced ovarian carcinoma diagnosed during pregnancy in a patient with human immunodeficiency virus infection.

Many malignancies appear to occur with increased frequency and aggressive patterns of spread in patients seropositive for human immunodeficiency virus (HIV). The relationship between HIV infection and cervical neoplasia suggests that these patients present with more advanced disease and demonstrate poor response to therapy. To date, there have been no reported cases of ovarian cancer with concomitant HIV infection. We describe a young, gravid woman with an advanced ovarian carcinoma diagnosed at the time of delivery. Following poor response to cytoreductive surgery and initial chemotherapy, she was found to be HIV-seropositive. She received multiple chemotherapeutic regimens and experienced significant complications associated with her treatment and HIV infection. She progressively deteriorated and died within 13 months of diagnosis. Based on these findings and experience with other HIV-associated malignancies, it is apparent that the conventional approach to therapy is inadequate to treat the advanced and more aggressive form of disease seen in women infected with HIV.