Biomedical subjects
C Krettek
Publications and source records attributed to C Krettek.
[A comparison of a fluoroscopy-free mechanical targeting system and a free-hand technic for the placement of distal interlocking screws of tibial nails].
Recently, radiation-independent aiming devices for the tibia which compensate for insertion-related implant deformation have been developed, but the benefits of such systems have not been determined. This study prospectively evaluated the duration of the nailing procedure, the length of radiation time, and the accuracy of interlocking screw placement with a radiation-independent distal aiming system and the free-hand technique. In an oblique cadaveric tibial fracture, a surgeon inexperienced with either technique performed a statically locked intramedullary nailing. For the aiming system and free-hand technique respectively, the total operation time was 25.4 +/- 11.3 vs 30.9 +/- 14.3 min (P = 0.029), the distal locking time was 16.7 +/- 8.6 vs 21.9 +/- 10.5 min (P = 0.004), the total fluoroscopy time was 9 +/- 5 vs 93 +/- 34 s (P < 0.0001), the distal locking fluoroscopy time was 0 versus 88 +/- 33 s (P < 0.0001), and the screw destruction was -0.7 +/- 5.2 vs 26.8 +/- 31.6 microns (P = 0.001). The failure rate was 1.6% (1 of 60 screws) in both groups. These results suggest that aiming devices can eliminate the need for radiation during distal interlocking screw placement.
[Advantages of the unreamed tibial nail in comparison with external fixator in treatment of grade 3 B open tibial shaft fractures].
Between 1987 and 1993, 41 grade 3B open tibial shaft fractures were treated with the unreamed tibial nail (URTN n = 22) or an external fixator (FIX n = 19). The method of treatment was left to the choice of the operating surgeon. Three below the knee amputations were performed, three patients died, and three were lost to follow-up. In all, 32 patients were followed up to union or at least for 1 year. There were no significant statistical differences between the two groups (P < 0.2, chi-squared, t-test) with respect to fracture type, fracture location, age, gender or accompanying injuries. The URTN group showed significantly better results regarding time to full weight-bearing (URTN 11 +/- 4 weeks; FIX 20 +/- 11 weeks, P < 0.01 M-W) Mann-Whitney Test, number of reoperations (URTN 1.04; FIX 2.89; P < 0.01 M-W), isolated bone grafting (URTN 3/22; FIX 8/19; P < 0.05 chi-squared), and average Karlström and Olerud score (URTN 30 +/- 4; FIX 26 +/- 5; P < 0.05 M-W). In all, 15/17 URTN patients and only 6/15 FIX patients achieved unlimited walking distance (P < 0.01 M-W). Time to bony union, infection, and nonunion were not significantly different between groups.
[Local foreign body reactions to biodegradable implants. A classification].
Biodegradable implants are increasingly used in orthopedic and trauma surgery. Many different implants consisting of different biodegradable polymers are currently available. Different factors contribute to the biocompatibility of these implants, and local foreign-body reactions remain a matter of concern. Therefore, it is mandatory to document and compare the tissue reactions caused by various biodegradable implants in experimental or clinical studies. We have developed a standardized system of classification based on our previous experimental and clinical observations. Foreign-body reactions are differentiated into osteolysis (0-0 to 0-4), extra-articular (EA-0 to EA-4) and intraarticular (IA-0 to A-4) soft-tissue reactions.
[New techniques in trauma surgery].
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[Complex knee joint trauma].
Juxta- and intraarticular fractures of the knee (floating knee), intraarticular fractures with severe soft tissue damage and knee dislocations with vascular or soft tissue lesions are defined as complex knee trauma. A specific management protocol is required for these cases. Fractures should be treated with soft-tissue sparing minimal invasive reduction and fixation techniques to reduce the significant complication rate which is presently encountered. Percutaneous plate fixation, percutaneous screw osteosynthesis and hybrid fixation should be widely used in these cases. In knee dislocation, the central pivot with the two cruciate ligaments should be reconstructed using augmented repair or primary tendon grafting in every case, whereas the treatment of collateral ligament lesions depends on the specific injury type.
[Pre-bending and and tension adjustment of narrow 4.5 mm AO titanium LC-DCP (limited contact dynamic compression plate)].
UNLABELLED: To assess the behavior of the LC-DCP with prebending and pretensioning we tested: gap angle vs. tensioning force without prebending; Bending moment for different prebending angles; In a model using a fiber tube to simulate the bone for different prebending angles and pretensioning forces of the LC-DCP the deformation in 4 point bending open was tested. Maximum prebending angle was 24 degrees, maximum pretensioning force was 2400 N; in human cadaver tibiae angles of 3 degrees, 9 degrees, 24 degrees and forces of 300 N, 1000 N and 1500 N, were tested to look for the difference in a less idealized model. RESULTS: 1. A near linear curve for gap angle vs. force with an angle of 0.45 degree/100 N was found between 100 N and 1500 N; 2. We did not find a near linear bending moment/bending angle curve up to 8 degrees like in the DCP but an exponential curve development as it had to be expected by the lower modulus of elasticity of titanium; 3. the maximum mechanical stability was found for a angle of 24 degrees and a force of 1500 N. The titanium LC-DCP shows a different mechanical reaction to prebending and pretensioning in the bone implant complex compared to stul DCP. Optimum prebending and pretensioning for axial compression and mechanical stability in the LC-DCP are by far greater than clinically possible. From our mechanical testing a prebending angle of 24 degrees and a pretensioning force of 1500 N would allow the largest axial compression and show the most resistance against deformation in bending open. In the clinical setting this would result in difficult reduction and therefore, we recommend a prebending angle of 9 degrees and a pretensioning force of 1000 N.
Foreword: concepts of minimally invasive plate osteosynthesis.
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Minimally invasive plate osteosynthesis and vascularity: preliminary results of a cadaver injection study.
A cadaver arterial injection study was performed to analyse the vascular supply to the femur and to study the effects of two surgical plating techniques on femoral vascularity. A 16-hole LC-DCP was applied on the intact femora of five fresh human cadavers. On one side, the plate was inserted using a conventional lateral plate osteosynthesis (CLPO) technique with elevation of the vastus lateralis muscle to expose the shaft. On the contralateral side, the plate was inserted percutaneously beneath the muscle using a minimally invasive plate osteosynthesis (MIPO) technique. After plating, blue silicone dye was injected through the common femoral artery. Cadaveric dissection was then performed to identify the femoral perforating arteries (PAs) and the nutrient artery (NA) of the femur. The pattern of periosteal filling and medullary perfusion of the injected dye was analysed and the topography of the PAs and NA was determined. CLPO placed the PAs and NA of the femur at risk. MIPO maintained the integrity of the PAs and NA and was associated with superior periosteal and medullary perfusion. The results of this study indicate that MIPO is superior to the CLPO in maintaining arterial femoral vascularity and perfusion.
Minimally invasive percutaneous plate osteosynthesis (MIPPO) using the DCS in proximal and distal femoral fractures.
In a prospective study, 14 cases of supracondylar or subtrochanteric fractures or osteotomies were stabilized with a dynamic condylar screw (DCS) inserted using a minimally invasive percutaneous plate osteosynthesis (MIPPO) technique. The technique consisted of 4 major steps: 1) placement of the guide wire under fluoroscopic control and condylar screw insertion through a stab incision; 2) plate insertion beneath the vastus lateral muscle; 3) engagement of the condylar screw to the plate using a modified T-handle and, 4) plate fixation to the shaft using percutaneously inserted self-cutting screws. Between October 1994 and December 1995, 14 cases in 12 patients met the inclusion criteria. There were 11 acute fractures (6 subtrochanteric, 5 supracondylar) and 3 corrective osteotomies. Nine fractures were closed, and 2 were open. One 97-year-old patient died 6 weeks after trauma. There were no infections and 12 of 13 cases healed without a second procedure. There was 1 implant failure (plate screw breakage), which required repeat fracture fixation. At follow-up, there were 2 varus deformities above 5 degrees, 2 shortenings over 20 mm, and 1 rotational deformity of 20 degrees. According to the Neer score, there were 6 excellent, 1 satisfactory, 3 unsatisfactory results and no failures. The results of this technique compare favourably with those of other series of osteosynthesis of subtrochanteric or supracondylar femoral fractures treated with internal fixation without the added morbidity associated with an extensive approach or autogenous bone grafting. However, the surgical technique is demanding, and care must be taken to restore the axial alignment.
Transarticular joint reconstruction and indirect plate osteosynthesis for complex distal supracondylar femoral fractures.
In a prospective study conducted between 1992 and 1995, displaced Müller type C2-C3 intraarticular fractures of the distal femur were treated using an indirect plate fixation technique and a lateral parapatellar arthrotomy for the direct reduction of the condylar block. There were 6 closed, and 2 open fractures (1 grade II and 1 grade IIIB). Following reconstruction of the articular block, the block was indirectly reduced and fixed to the shaft by a plate inserted by the retrograde method beneath the vastus lateralis. Transcutaneous/transmuscular screws were used to fix the plate to the shaft. Time to bone healing was 12 weeks (median range 8-17 weeks) after surgery without needing primary or secondary bone grafts. There were no infections or refractures. Except for one case which required a corrective osteotomy for 10 degrees of varus malalignment, there were no revisions. According to the Neer score, there were 6 excellent or satisfactory results, 2 unsatisfactory results, and no failures. At follow-up, there were 2 varus-valgus deformities greater than 5 degrees, 2 leg length discrepancies greater than 10 mm, and 2 rotational deformities of 15 degrees. The treatment results for complex supracondylar/intracondylar fractures of the distal femur obtained with this technique compare favourably with other reported series using different techniques without the added morbidity associated with autogenous bone grafting. However, the surgical technique is demanding and special care must be taken to ensure correct axial alignment.
The deformation of small diameter solid tibial nails with unreamed intramedullary insertion.
'Radiation-independent' aiming systems for the placement of interlocking screws in intramedullary tibial nails have failed because of insertional related nail deformation. Prior to the development of these distal aiming systems, the variable position of the nails' interlocking holes after insertion must be known. In this study, the amount and direction of implant deformation of solid stainless-steel tibial nails (diameters of 8 and 9 mm, n = 20) were analyzed. Measurement of implant deflection (three translations, three angles) in the center of distal transverse locking hole was performed with a three-dimensional-magnetic motion tracker system after nail insertion in paired human cadaver tibiae. The results showed combined mean lateral translation of the 8 and 9 mm nails (n = 20) of -4.5 +/- 3.5 mm (range: 14.3 mm) and dorsal translation -7.8 +/- 5.8 mm (range: 19.2 mm). The combined mean rotational deformation about the longitudinal axis of the nail was 0.3 +/- 0.7 degree (range: 2.4 degrees). The authors conclude that a simple aiming arm, mounted on the proximal nail end alone, is not sufficient to provide accurate distal aiming.
In vitro and in vivo radiomorphometric analyses of distal screw hole position of the solid tibial nail following insertion.
OBJECTIVE: The objective of this study was to analyse the position of the distal interlocking holes of an unreamed solid tibial nail relative to the adjacent cortices of the tibial bone. DESIGN. IN VITRO: and in vivo radiographic-morphometric analysis. BACKGROUND: To date, 'radiation-independent' intramedullary distal interlocking aiming systems have not been successful, primarily because proximally mounted aiming devices cannot account for the deformation of the nail during insertion; therefore the distal interlocking holes relative to the adjacent cortices must be understood. METHODS: A two-dimensional radiographic-morphometric analysis was performed in 40 tibiae after in vitro (n = 20) and in vivo (n = 20) implantation of unslotted stainless steel unreamed 8- and 9-mm diameter intramedullary nails. RESULTS: The combined in vitro and in vivo results showed average distances between the upper distal transverse hole and the anterior aspect of the tibia of 12.3 mm (SD 1.7 mm; variance 2.9 mm(2); range 7.6 mm). CONCLUSIONS: The distances between the upper distal transverse hole and the anterior aspect of the tibia are the most reliable parameters of distal nail hole position. RELEVANCE: For a 'radiation-independent' distal interlocking aiming system for unreamed intramedullary tibial nails to be successful, it could take advantage of the relatively constant distance between the anterior cortex and the most proximal distal screw hole.
Arthroscopic repair of the posterior cruciate ligament in a 3-year-old child.
We report a case of symptomatic acute posterior cruciate ligament (PCL) rupture in a 3-year-old boy. At arthroscopy, the PCL was avulsed from the femoral attachment with intact ligament substance. Arthroscopic repair of the PCL was performed by transosseous sutures, which were placed using a suture-punch and an anterior cruciate ligament drill guide. Two years later there was a perfect objective and functional result.
A new technique for the distal locking of solid AO unreamed tibial nails.
Proximally mounted distal aiming systems have failed primarily because of nail deformation during insertion. A mechanical aiming device for the insertion of distal locking screws for solid unreamed AO tibial nails was developed and was tested in twenty unreamed solid tibial nailing procedures in a video-documented prospective clinical study. The rate of accurate screw placement, time expended, complications, and outcome for each patient were recorded. Distal locking was performed successfully in all cases without image intensification. Although a high percentage (55%) of fractures were open, the total mean operative time was 108 minutes (range, 60 to 180 minutes) and the mean time for distal locking (three screws) was 15.5 minutes (range, 8.0 to 39.0 minutes). Notable drill-nail contact occurred in 15 percent of the distal screws placed, demonstrating accurate aiming and drilling. There were no major intra- or postoperative complications related to the distal aiming system.
Recurrent rotational deformity of the femur after static locking of intramedullary nails: case reports.
Rotational deformity following intramedullary nailing may cause symptoms and require surgical correction by osteotomy. Reamed, locked intramedullary nailing may be performed, but concern about cortical blood supply and potential pulmonary dysfunction from reaming have led many surgeons to limit this and use smaller diameter nails. Slotted nails are commonly used but are less stiff in torsion than the newer unslotted nails, particularly at the lower diameters. We report two cases of recurrent femoral rotational deformity after using statically interlocked slotted intramedullary nails to correct existing femoral rotational deformities. These patients show that small diameter statically interlocked femoral nails with diminished bone-nail contact must be stiff enough in rotation to avoid potential recurrence.
Rotationplasty for the treatment of severe bone loss and infection of the distal end of the femur. A case report.
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Non-union of the ulna in a ten-month-old child who had type-IV hereditary sensory neuropathy. A case report.
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