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Biomedical subjects

K J Koval

Publications and source records attributed to K J Koval.

At least 91 records · Page 5Linked to original sources
PubMed1995

Biomechanical comparison of the sliding hip screw and the dome plunger. Effects of material and fixation design.

We studied the biomechanical behaviour of three sliding fixation devices for trochanteric femoral fractures. These were a titanium alloy sideplate and lag screw, a titanium alloy sideplate and dome plunger with cement augmentation, and a stainless-steel sideplate and lag screw. We used 18 mildly osteoporotic cadaver femora, randomly assigned to one of the three fixation groups. Four displacement and two strain gauges were fixed to each specimen, and each femur was first tested intact (control), then as a two-part fracture and then as a four-part intertrochanteric fracture. A range of physiological loads was applied to determine load-bearing, load-sharing and head displacement. The four-part-fracture specimens were subsequently tested to failure to determine maximum fixation strengths and modes of failure. The dome-plunger group failed at a load 50% higher than that of the stainless-steel lag-screw group (p < 0.05) and at a load 20% higher than that of the titanium-alloy lag-screw group (NS). All 12 lag-screw specimens failed by cut-out through the femoral head or neck, but none of the dome-plunger group showed movement within the femoral head when tested to failure. Strain-gauge analysis showed that the dome plunger produced considerably less strain in the inferior neck and calcar region than either of the lag screws. Inferior displacement of the femoral head was greatest for the dome-plunger group, and was due to sliding of the plunger. The dome plunger with cement augmentation was able to support higher loads and did not fail by cut-out through the femoral head.(ABSTRACT TRUNCATED AT 250 WORDS)

Biomechanical Phenomena↗
PubMed1995

Fractures of the proximal part of the femur.

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.

Adult↗
PubMed1995

Fracture of the iliac crest following bone grafting: a case report and literature review.

Fracture of the anterior iliac crest following bone grafting is an extremely rare occurrence. Five cases have been reported in the literature, none of which were internally stabilized. We are reporting a sixth case. Of the six cases, our harvest site is the furthest posterior from the anterior superior iliac spine. The fracture resulted in a large displaced anterior fragment that required open reduction and internal fixation with plates and screws. Osteoporosis increases the risk of anterior iliac crest fractures following bone grafting, but preventive procedures can be performed.

Bone Transplantation↗
PubMed1994

Vertical shear fractures of the medial malleolus: a biomechanical study of five internal fixation techniques.

Fifty embalmed human tibias were osteotomized to create a simulated vertical shear (supination-adduction) fracture of the medial malleolus and were stabilized using one of five internal fixation techniques. In offset axial testing, which simulated supination-adduction loading, the fixation strength of tibias stabilized with either cortical or cancellous lag screws placed perpendicular to the osteotomy was over five times greater than the strength of those treated with an antiglide plate and nearly two and a half times greater than those treated with cancellous lag screws placed oblique to the osteotomy. The tibias stabilized with cancellous lag screws placed perpendicular to the osteotomy exhibited twice the fixation strength of the tibias stabilized with an antiglide plate and distal lag screw. The tibias stabilized with an antiglide plate and distal lag screw and perpendicularly placed cortical or cancellous lag screws demonstrated three times greater resistance to displacement to the applied supination-adduction load than those stabilized with an antiglide plate alone. In offset transverse testing, to simulate loading in external rotation, the mean failure load of the tibias stabilized with cancellous lag screws placed perpendicular to the osteotomy was over two and a half times greater than those stabilized with an antiglide plate and distal lag screw. No significant differences were observed in the resistance to displacement for these tests. These results support the use of lag screws placed perpendicular to the fracture surface for stabilization of vertical shear fractures of the medial malleolus and indicate that the use of an antiglide plate, with or without a distal lag screw, does not offer any advantage over lag screw fixation.

Biomechanical Phenomena↗
PubMed1994

Fracture blisters.

A clinical and histological study was performed on fracture blisters found in association with 13 surgically treated ankle fractures. The timing of surgery was dependent upon soft tissue swelling; the status of the blister did not affect this aspect of the decision making process. The average time from injury to surgery was 2.1 days (range, 1-3 days). At the time of surgery all blisters were intact. Skin biopsies were obtained from the edge of the incision in proximity to the blister, and from the bed of the blister when the incision was made through the blister. Clinically, 2 blister types were identified: (1) clear fluid filled, and (2) blood filled. Histologically, both blister types demonstrated a cleavage injury at the dermoepidermal junction. However, the dermis of the clear fluid filled blister retained occasional epithelial cells, while the dermis of blood filled blisters was completely devoid of epidermis. Minimal to no evidence of dermal injury was found in histologic sections from the blister beds or from the skin in close proximity to blisters. All incisions made through and around skin blisters went on to heal without evidence of infection or wound breakdown. Delayed wound healing occurred in 1 patient in whom an incision was placed through a blood filled blister. The blood filled blister appears to represent a slightly deeper injury than the clear fluid blister and had a higher risk of poor healing of surgical incisions.

Adult↗
PubMed1994

Basicervical fractures of the proximal femur. A biomechanical study of 3 internal fixation techniques.

A biomechanical cadaver study was performed to compare the stability and ultimate strength of 3 standard fixation techniques used for treatment of basicervical hip fractures. Twenty one pairs of mildly osteoporotic femurs were selected, based on a computed tomography bone density reading of 40-50 Hounsfeld units and a Singh index of III. After initial mechanical characterization of intact femurs, basicervical femoral neck fractures were created, reduced, and then instrumented with random assignment to 1 of 3 methods of fixation: (1) 3 parallel 6.5-mm cannulated cancellous screws; (2) a 135 degrees sliding hip screw with a 4 hole side plate; and (3) a 135 degrees sliding hip screw with a 4 hole side plate and a 6.5-mm cannulated cancellous screw placed proximal and parallel to the sliding screw. Nine pairs were tested to failure in axial loading, 6 pairs in lateral bending, and 6 pairs in torsion. The group instrumented with the multiple cancellous screws had a significantly (p < 0.01) lower ultimate axial load to failure than either sliding hip screw group. However, the multiple screws demonstrated significantly (p < 0.01) less fracture displacement. There were no statistically significant differences in lateral bending or torsional testing behavior between the 3 fixation methods. Use of the sliding hip screw is recommended rather than use of multiple cancellous screws for treatment of basicervical femoral neck fractures. Although a superiorly located cancellous screw may provide rotational control during sliding hip screw insertion, it provides no incremental fixation after the sliding hip screw is placed.

Biomechanical Phenomena↗
PubMed1993

Retrograde reamed femoral nailing.

Closed, reamed, antegrade nailing remains the standard of care for femoral shaft fractures. This technique however, may be less attractive in the management of femoral shaft fractures associated with (a) ipsilateral acetabular, pelvis, or femoral neck fractures; (b) polytrauma requiring multiple simultaneous surgical procedures; and (c) pregnancy. We now report on our experience with the retrograde femoral nailing as a treatment option in these situations. Between 4/88 and 10/90, 29 retrograde femoral nailing in 24 patients were attempted. Average age was 29.3 (16-74) years. Five fractures were open. Fracture location was isthmal in 14 and infraisthmal in 15. The comminution was classified according to Winquist and Hansen: I(10), II(7), III(7), and IV(5). Nailing was possible in 28/29 cases. Insertion was made through an extraarticular medial condylar portal. Nail diameter ranged from 10 to 13 mm. An AO Universal Femoral Nail was used in the first 11 cases; all subsequent fractures were stabilized using an AO Universal Tibial Nail because its design appeared better suited to this technique. Follow-up was possible for 25 fractures in 21 patients and averaged 16.0 (range, 11-27); months 23/25 (92%) fractures healed within 12 weeks. No case was associated with an infection, loss of reduction, or nail failure. Knee flexion averaged 122 degrees; only two knees had an extensor lag of > 5 degrees. Intraoperative complications included three cases of crack propagation at the insertion site, and four infraisthmal malreductions (two valgus, two flexion). Based on these results, we feel that retrograde reamed femoral nailing is a suitable alternative to antegrade nailing and should be considered in situations where proximal access is neither possible nor desirable.

Acetabulum↗
PubMed1993

Exposure of the orthopaedic surgeon to radiation.

A prospective study of sixty-five orthopaedic procedures performed with fluoroscopic assistance was undertaken to determine the risk to the primary orthopaedic surgeon with regard to radiation. Radiation was monitored with the use of a universal film badge placed outside the collar of a lead apron, and a gas-sterilized thermoluminescent dosimeter ring worn on each hand. The rings were changed with every operation, but the same film badge was transferred from surgeon to surgeon. The hand dominance of the surgeon, the duration of the operative procedure, the type of operation, and the total time that fluoroscopy had been used were noted. The study was conducted during twenty-one intramedullary nailing procedures (thirteen involving distal locking), forty open reductions with internal fixation (plates and screws), and four external-fixation procedures. All of the badges and rings were submitted for a report regarding radiation exposure. No relationship was found between a ring with a positive reading for exposure to radiation and the duration of the operation. Similarly, there was no correlation between a positive reading and the surgeon's hand dominance. The mean duration of the fluoroscopy was 2.3 minutes for the group for which the rings did not show a positive reading and 4.7 minutes for the group for which the rings did show a positive reading. This was a significant difference (p < 0.0001). There was no positive reading for exposure to radiation from any ring that had been worn during a procedure in which the fluoroscope had been used for less than 1.7 minutes.(ABSTRACT TRUNCATED AT 250 WORDS)

Bone Nails↗
PubMed1993

Technical pitfalls in the use of the sliding hip screw for fixation of intertrochanteric hip fractures.

Two hundred fifty consecutive intertrochanteric fractures treated with a sliding hip screw (SHS) over a three year period were reviewed and specific types of technical pitfalls identified. Most pitfalls were technique dependent and potentially preventable with proper attention to the principles of fracture reduction and insertion of the device. Pitfalls encountered with the use of the SHS occurred as a result of either poor fracture reduction or implant insertion. Problems related to fracture reduction included poor radiographic visualization, posterior sag, varus angulation, and internal rotation of the femoral shaft in relation to the femoral neck. Potential pitfalls encountered during SHS insertion included superior guide wire placement, guide wire breakage or penetration into the hip joint or pelvis, loss of reduction during lag screw insertion, improper screw-barrel relationship, and improper plate application. Finally, the SHS may not be the implant of choice for all extracapsular hip fractures (i.e., the reverse obliquity fracture). This paper identifies the various pitfalls that may occur with the use of the SHS for the fixation of intertrochanteric hip fractures. Illustrative cases are provided and guidelines for avoiding these surgical pitfalls suggested.

Bone Screws↗
PubMed1993

A comparison of modified Knowles pins and cannulated cancellous screws for the treatment of nondisplaced or impacted femoral neck fractures.

A prospective study was performed comparing modified Knowles pins to cannulated cancellous screws for the treatment of nondisplaced and impacted femoral neck fractures. Forty-five impacted or nondisplaced fractures were identified: twenty-five were stabilized with modified Knowles pins and twenty with cannulated cancellous screws. Patient follow-up averaged twenty-four months (range 12 to 46 months) or until reoperation. Six patients (13%) required reoperation; these failures were evenly divided between the two groups. The remainder of patients (twenty-two patients (88%) in the Knowles pin group and seventeen patients (85%) in the cannulated screw group) were comparable with regard to functional outcome.

Activities of Daily Living↗
PubMed1993

Pudendal nerve palsy induced by fracture table.

There are 23 cases in the literature of fracture table-induced pudendal nerve palsy. The majority of these patients had full sensory return; however, return of sexual function was unpredictable. The relevant anatomy, etiology, and incidence of this complication are discussed, and suggestions are made for its prevention.

Female↗
PubMed1993

Posttraumatic tibial osteomyelitis: diagnosis, classification, and treatment.

The problem of osteomyelitis has, to date, not been completely resolved. Recent research has provided additional insight into the pathogenesis of bone infection. Advances in pharmacology and in surgical techniques have enhanced our ability to treat such infections. Despite these advances, successful treatment of posttraumatic tibial osteomyelitis depends on adherence to several basic principles: complete debridement of necrotic and infected tissue, obtaining bony stability, the elimination of dead space, and the provision of durable soft tissue coverage. Armed with this new knowledge and surgical ability, treatment results have improved. We do not know, however, whether osteomyelitis can ever be "cured," since infections become manifest many years after injury or treatment.

Anti-Bacterial Agents↗
PubMed1993

Symptomatic displacement of the lesser trochanter following trochanteric fracture fixation.

Unstable intertrochanteric hip fractures are characterized by comminution of the posteromedial cortex, resulting in a fragment of variable size containing the lesser trochanter. Controversy exists as to whether it is necessary to perform reduction and fixation of this fragment. This case lends further support to the practice of fixating the lesser trochanteric fragment in unstable intertrochanteric fractures.

Aged↗
PubMed1993

The radiologic evaluation of calcaneal fractures.

Although computed tomography (CT) scanning has revolutionized the treatment of calcaneal fractures, simple studies such as Böhler's view still have a role in the diagnosis and management of these fractures. This article reviews the benefits and limitations of these imaging techniques for calcaneal fractures.

Calcaneus↗
PubMed1993

Enhancing independence in the older hip fracture patient.

No doubt all experienced clinicians have observed cases in which a hip fracture dramatically diminished the independence and quality of life of an elderly person. This difficult problem requires a concentrated, multidisciplinary effort. More than 800 patients have now been treated using our interdisciplinary approach. A recent review of the data shows that results in this larger group compare favorably with those in the followup group described in this article. We believe that our approach shows promise as a model for the future. Further, comparisons with current practices may lead in some situations to significant improvements in hip fracture rehabilitation. Primary care physicians play a key role in this process of review and modification and in contributing to the overall restorative effort.

Activities of Daily Living↗
PubMed1992

Indirect reduction and percutaneous screw fixation of displaced tibial plateau fractures.

Indirect reduction and percutaneous screw fixation were attempted in 20 displaced tibial plateau fractures in 20 patients. Closed, indirect reduction was successful in 18 fractures; two others, both Schatzker type II fractures, required open reduction. The 18 fractures were followed for an average of 16.2 months (range, 12-24 months). Of the fractures successfully reduced with indirect techniques, 13 were reduced anatomically (72.2%), and five were considered nonanatomic (27.8%). Four of the five fractures with a nonanatomic reduction were type II fractures. Clinically, there were six excellent (33%), 10 good (56%), and two fair (11%) results. No fracture lost reduction; no patient developed an infection. Indirect techniques could effectively reduce only split fragments. Depressed fragments could not be reduced reliably with either ligamentotaxis or percutaneous elevation with a tamp. There was no correlation between radiographic reduction and clinical outcome. It did not matter whether two, three, or four screws were used to stabilize the fracture.

Adolescent↗