[TECHNICAL PRINCIPLES OF SURGICAL FRACTURE FIXATION].
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PURPOSE: To compare the biomechanical properties of 6 dorsal and volar fracture fixation plate designs in a cadaver model. METHOD: Six different plating techniques were used on surgically simulated, unstable, extra-articular distal radius fractures in fresh-frozen cadavers. Specimens were tested to failure in axial compression with the Materials Testing System machine, and were analyzed with a motion analysis system. The 6 different fixation systems studied included an AO stainless steel Pi plate (group 1), an AO titanium Pi plate (group 2), a Forte plate (group 3), a dorsally placed Symmetry plate (group 4), a volarly placed Symmetry plate (group 5), and a volarly placed SCS/V plate (group 6). RESULTS: All dorsal plates (groups 1, 2, 3, 4) failed in apex dorsal angulation and all volar plates (groups 5, 6) failed in apex volar angulation. No group developed an average angular deformity greater than 5 degrees with a load of 100 N, which compares with the physiologic loads expected with active wrist motion. Only the volarly placed SCS/V plated specimens (group 6) resisted deformation of 5 degrees or more at loads up to 250 N, which compares with the physiologic loads expected with active finger motion, and was significantly stronger and more rigid than the other 5 plate groups. CONCLUSIONS: The SCS/V plate fixation system is the most rigid of the systems tested and may offer adequate stability for the treatment of the distal radius fracture in which the anterior and/or posterior metaphyseal cortex is comminuted severely.
Injectable osteoconductive calcium phosphate cements have been introduced as an adjunct to internal fixation for treating selected fractures. These cements harden without producing much heat, develop compressive strength, and are remodeled slowly in vivo. The main purpose of the cement is to fill voids in metaphyseal bone, thereby reducing the need for bone graft, but cements also may improve the holding strength around metal devices in osteoporotic bone. Several bioactive cements are being developed. One of these cements, Skeletal Repair System, is available in Europe and has been approved by the United States Food and Drug Administration for use in selected distal radius fractures. Cadaveric studies have shown that using Skeletal Repair System cement with conventional metal fixation in certain fractures of the distal radius, tibial plateau, proximal femur, and calcaneus can produce better stability, stiffness, and strength than metal fixation alone. Early clinical results have shown reduced time to full weightbearing when cement has been used for augmentation of tibial plateau and calcaneal fractures, more rapid gain of strength and range of motion when used in distal radius fractures, and improved stability in certain hip fractures. Bioactive cements in general also may prove useful in vertebroplasty.
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80 cases of intratrochaner fractures were treated by fixation of 4 Steinmann's pins which were 3.5 mm in diameter and inserted percutaneously through the calcar and compression trabeculae and distension trabeculae respectively. They were compared with the cases treated by skeletal traction or fixed by Nail-plate or angle plate. The rate of bony union in fixed position in the percalcar Steinmann's pins group was 83.7%. Normal neck-shaft angle accounted to 53.1% in the traction group. Varus deformity occurred in 16.3% cases of the Steinmann's pins group, and 35.9% cases of the traction group. The deformity was most frequently seen in cases of type IIIa and IV. No fixation failure occurred in the Steinmann's pins group. The Steinmann's pins passing through the outer cortex, calcar and compression trabeculae produced strong fixation and it's direction was in parallel to the weight-bearing line of the hip, with less shearing force and much compression force distributed on the fracture line. The operation was done under local anesthesia. No blood transfusion and early mobilization were the advantages of this method.
The effect of femoral neck-shaft angle and implant type on the accuracy of lag screw placement in extra-capsular proximal femoral fracture fixation was investigated. Radiographs of all extra-capsular proximal femoral fractures seen in one unit over 18 months were reviewed. Of 399 cases, 307 (237 female, 70 male) were included in the study as they had no contra-lateral proximal femoral metal work. Femoral neck-shaft angle (NSA) of the uninjured hip and magnification adjusted tip-apex distance (TAD) of femoral head lag screw were measured. Type of fixation implant was 135 degrees classic hip screw (CHS) (n=144) or 130 degrees intra-medullary hip screw (IMHS) (n=163). Mean contra-lateral NSA was 130.2 degrees (112.9--148 degrees ) and 64 patients (58 female, 6 male) had a NSA <125 degrees . Mean adjusted TAD was 18.7 mm (5.8--43.8mm) and 88.9% of cases had a TAD of less than 25 mm. TAD values were significantly greater using an IMHS if NSA was <125 degrees than if NSA was >125 degrees (p=0.028). This was not the case with the CHS. The use of the 130 degrees -IMHS in patients with a NSA <125 degrees leads to poorer lag screw placement than if NSA >125 degrees and caution is advocated when using this device in such cases.
The quantification of sister chromatid exchange (SCE) during mitosis is a useful index for evaluating genotoxic effects in subjects occupationally or incidentally exposed to potentially toxic substances. The authors investigated the hypothesis that ions released by corrosion from prosthetic components of fracture fixation devices are associated with change in SCE incidence. In the present study, ten patients with implants were examined, and fifteen subjects with no implants were used as controls. SCE and high frequency cell (HFC) numbers were evaluated in circulating lymphocytes. In addition, nickel (Ni) and chromium (Cr) ion values in the serum were measured because, after iron, these metals are major components of stainless steel. A significant increase in SCE numbers was observed in patients compared to the control population (4.9 +/- 1.3 vs. 3.5 +/- 1.4). Ni concentration was 1.71 +/- 1.49 ng/mL in patients and 0.72 +/- 0.52 ng/mL in control subjects; Cr concentration was, respectively, 1.01 +/- 0.77 ng/mL and 0.19 +/- 0. 27 ng/mL. The increase of serum Cr and Ni was statistically significant. No correlation was found between the increased Cr concentrations and SCE number while Cr ion levels were found to be significantly correlated to HFC. An inverse correlation between Ni level and SCE numbers was observed. Our findings suggest that Cr release by stainless steel implants could have a genotoxic effect; thus it would be useful to carefully monitor implanted subjects with regard to serum ion dosage, SCE analysis, and HFC evaluation. In any case, it would be appropriate to remove the implant when fracture fixation is reached.
This study focuses on determining the effects of clinically relevant procedures on the flexural and fracture toughness properties of three short-fibre thermoplastic composites for potential application as fracture fixation devices. The procedures included sterilization, heat contouring and saline soaking. The three materials tested were polysulphone, polybutylene terephthalate and polyetheretherketone, all reinforced with 30% short carbon fibres. The polysulphone composite showed significant degradation in mechanical properties due to saline soaking. The polybutylene terephthalate exhibited significant degradation of mechanical properties following both contouring and saline soaking. The polyetheretherketone composite, however, exhibited no degradation in mechanical properties. The results demonstrated that flexion and fracture toughness testing were effective for determining the response of the composites to different applied conditions and demonstrated the stability of polyetheretherketone subjected to these treatments. Scanning electron microscopy demonstrated the most effective fibre-matrix bonding to be in the polyetheretherketone.
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The purpose of this study was to define the proximal ulna anatomy with respect to olecranon osteotomy and fracture fixation. Thirty-nine cadaver elbows were dissected. The mean ulnar length (triceps insertion to ulnar styloid) was 26.0 cm (range, 27.1-29.0 cm). The mean distance from the triceps insertion to the ulna's varus angulation point was 7.6 cm (range, 6.5-9.0 cm). The distance ratio from the triceps insertion to the proximal ulnar angle to the overall ulna length was consistent, averaging 0.29 (range, 0.23-0.33). The mean diameter of the medullary canal at the ulnar angulation point could accommodate a 7.0- or 7.3-mm intramedullary screw. The mean width of the olecranon bare area (lacking articular cartilage) was 0.53 cm (range, 0.13-0.97 cm), and the mean distance from the triceps insertion to the corresponding area of the bare spot on the dorsal cortex was 2.1 cm (range, 1.4-2.5 cm).
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To determine whether dimensional scaling (relative to the human) is necessary for screwed pins used in externally applied fracture fixation studies on sheep, geometrical data were determined for six ovine tibiae. Each tibia was potted relative to a lengthwise reference axis and sectioned at 5 per cent length intervals over its central 80 per cent. Enlarged (280 per cent) images of each cross-section were digitized at 1 mm increments around the periphery of the periosteal and endosteal surfaces, the data were digitally filtered, and geometrical properties were computed to include cross-sectional area A, maximum and minimum second moments of area (Imax and Imin), polar second moment of area J, and effective polar second moment of area J(eff). Proportional scaling of geometrical properties with respect to bone length (L2 for A, and L4 for second moments of area) significantly (p < 0.000001) decreased the coefficient of variation in data by an average 36 per cent. From 30-90 per cent distal, J(eff) for the ovine tibia is smaller but within 7 per cent of J--in stark contrast with the human tibia, where J(eff) has been reported as 70-80 per cent of J over the same tibial length. While previous ovine studies involving external fixator pins have employed the same diameter of pin as has been used in humans (that is 5 or 6 mm), a 'first-order' approximation of the data for A, Imax, Imin and J(eff) suggests these pins should be scaled down to 4 mm and 4.75 mm respectively for use on the ovine tibia over the range 25-80 per cent distal along its length.
We describe a 62-year-old woman who developed two pseudocysts, 25 x 15 cm and 20 x 12 cm, in the left proximal thigh as a complication 19 years after internal fixation of an intertrochanteric fracture. She received a 135 degrees dynamic hip screw and side plate in May 1979. She continued to live at home without major discomfort until May 1997. Two huge pseudocysts were noted in the left proximal thigh without trauma history. Angiography was normal. Computerized tomography scan revealed two voluminous cystic lesions without septa in the left proximal thigh, with accumulated fluid. During surgery, two huge cysts were found in the left proximal thigh, and their orifices were found slightly proximal to the curvature of the side plate. The pathology showed that the cysts consisted of a nonepithelialized wall of granulation tissue compatible with a pseudocyst. The patient had no further problems 2 years after surgery. We found no reports in the literature of this rare complication. The development of the pseudocysts may have been the result of chronic low-grade trauma due to irritation between the soft tissue and the implant. Orthopedic surgeons should be aware of the possible development of this rare complication following internal fixation of an intertrochanteric fracture.
A biomechanical study was conducted to determine the best fixation technique for mallet finger fracture among four commonly used methods. Considerations were technical complications, biomechanical properties, and maintenance of reduction. Techniques tested included Kirshner wire, figure-of-eight wire, tension band wire, and tension band suture. Technical complications were frequent with both the Kirschner wire and tension band wire techniques. Biomechanical testing yielded significantly greater energy absorbed to failure and a trend toward greater peak loads to failure for both the figure-of-eight wire and tension band suture techniques. Irreversible loss of reduction during testing occurred in all of the Kirschner wire-fixed fractures, in 60% of the tension band wire-fixed fractures, and in 50% of the figure-of-eight wire-fixed fractures. No irreversible failure occurred in the tension band suture group.
We report two cases of severe aseptic synovitis of the knee 8 and 13 weeks after biodegradable internal fixation (Biofix rods) of a fracture of the intercondylar eminence. Both knees were treated by surgical revision and synovectomy. Histologic examination revealed a severe foreign-body type of reactive synovitis in the absence of infection. It is not advisable to use Biofix intraarticularly.
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The Dynamic Hip Screw (DHS) is currently the most frequently used implant for the treatment of pertrochanteric hip fractures. The Percutaneous Compression Plate (PCCP) is a recently developed, alternative device that involves minimal invasive surgery. The objective of the present study was to compare functional recovery following these two surgical procedures. A total of 76 consecutive elderly subjects (mean age and standard deviation, 80.6 +/- 5.5) following pertrochanteric hip fracture fixation were evaluated prospectively. Functional recovery was assessed 3 and 12 weeks and 2 years following surgery. Differences between groups 3 weeks postsurgery were found only in pain level during ambulation and in the weight-bearing capability of the operated extremity, which were both in favor of the PCCP. By 3 months, both groups had improved in all measures, but did not reach their preinjury level of independence. However, the PCCP group ambulated with fewer assistive devices and demonstrated better recovery of basic activities of daily living (BADL). While the majority of the subjects from both groups ambulated independently 2 years postsurgery, the PCCP group exhibited less pain during ambulation, was more independent in ADL, and required fewer assistive devices for ambulation. To summarize, the PCCP presents enhanced short- and long-term recovery of functional abilities in comparison to DHS. However, given the limited number of patients, further studies are necessary to substantiate these results.