Early pin failure following external femoral fracture fixation in a head-injured child.
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A series of 42 patients operated on due to humeral shaft fracture and 67 patients with forearm bones shaft fracture were analyzed clinically and statistically. The type of fracture was related to the time span between injury and surgery and number of complications. Complications were divided into two groups--early ones (skin necrosis, infection) and late ones (fixation failure, delayed union, pseudoarthrosis). Injury to surgery time span was divided into for sections: less than 10 h, 10-24 h, 24 h-10 d and above 10 days. Early and late complications prevailed in patients operated within 24 hours from injury (87% of all complications). Eleven patients with humeral fracture had fair or poor result; 8 of them were operated within 24 hours from injury. Among 18 patients with fair and poor results after forearm fracture 13 were operated on within 24 hours from injury.
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OBJECTIVE: To compare the mechanical effectiveness of three different techniques for stabilization of transverse fractures of the patella. DESIGN: Cadaveric knees were used to model acute fractures of the patella. To test three treatment techniques in pairs of knees, specimen pairs were assigned randomly to a set of predetermined treatment pairs so as to provide equal numbers of paired and unpaired data sets. Results then were analyzed using a two-way analysis of variance. SETTING: The treatment techniques used are widely applicable in the clinical setting for the treatment of transverse fractures of the patella. No specialized equipment or training is required for the general or subspecialized orthopaedic surgeon. PATIENTS/PARTICIPANTS: None. INTERVENTIONS: Fractures were created in eighteen knees (nine pairs) and repaired by one of three techniques: (a) modified tension band (AO technique); (b) two parallel 4.5-millimeter interfragmentary lag screws; or (c) a new technique using four-millimeter cannulated lag screws with a tension band wired through the screws. MAIN OUTCOME MEASURES: In mechanical testing, the amount of interfragmentary separation in simulated knee extension and the maximum load to failure at 45 degrees of flexion were measured. RESULTS: Fractures stabilized with a modified tension band were found to displace significantly more than those fixed with screws alone or screws plus a tension band in simulated knee extensions (p < 0.05). The fractures fixed with the cannulated screws plus the tension band failed at higher loads (mean = 732 newtons) than those stabilized with screws alone (mean = 554 newtons, p = 0.06) or those with a modified tension band (mean = 395 newtons, p < 0.05). CONCLUSIONS: Combining interfragmentary screw fixation with the tension band principle appears to provide improved stability over the modified tension band or screws alone for transverse patella fractures. Cannulated screws allow for simple, reliable addition of a tension band to screw fixation.
The objective of this study was to investigate the effect of cerclage wire position and determine the number of wires necessary to prevent crack opening and stem subsidence following a proximal femoral fracture in cementless total hip arthroplasty. A cementless femoral stem one size larger than the templated size was inserted into each femur to initiate a proximal crack. A cerclage wire was wrapped around the fracture in one of two orientations: 1) parallel to the osteotomy (PO) and 2) normal to the fracture line (NF). The femur was compressed to a load of 890 N, 1780 N and 2670 N while crack opening and stem subsidence were measured. A second cerclage wire was placed parallel to NF wire and inferior to the lesser trochanter and a third wire was placed 1 cm distal and parallel to the second wire. The loading was repeated again. The mechanical evaluation of stem subsidence were verified by various computer simulations even using four wires. We have found that placement of the cerclage wires normal to the fracture line prevents stem subsidence and crack opening better than placement of the wires parallel to the osteotomy. Three cerclage wires, placed normal to the fracture line at three locations: 1) adjacent to the superior of the lesser trochanter, 2) adjacent to the inferior of the lesser trochanter and 3) 10 mm distal to the bottom of the lesser trochanter were necessary to achieve stability under higher loads.
BACKGROUND: Fifth metatarsal Jones fractures are common in the athletic population. Optimal screw selection for operative treatment has not been determined. HYPOTHESIS: A 4.5-mm cannulated screw used for fixation of the fifth metatarsal Jones fractures in athletes is an effective treatment approach. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: The authors studied 23 consecutive athletes (24 feet) who were treated surgically with a 4.5-mm cannulated screw for fifth metatarsal fractures (Jones fracture) with clinical and radiographic assessments. RESULTS: There have been no refractures to date. Clinical healing was 100%. The mean percentage healing as shown on radiographs was 98.9%, with a range of 90% to 100%. All athletes returned to sport at a mean time of 7.5 weeks (range, 10 days to 12 weeks). Two athletes experienced a "reinjury" without need for operative treatment. All athletes were recommended to wear orthoses until their competitive careers were completed. CONCLUSION: Fixation with a stainless steel 4.5-mm cannulated screw gives 100% clinical healing and near-100% healing as shown on radiographs. CLINICAL RELEVANCE: The 4.5-mm cannulated screws can yield reliable and effective healing as evidenced by clinical assessment and radiographs of fifth metatarsal Jones fractures in athletes.
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Subtrochanteric osteotomies were created in 18 matched pairs of embalmed cadaveric femora. The femora were stabilized with a Synthes, Zimmer, or Richards second generation femoral reconstruction nail with retrograde blade or screws. The femoral pairs were randomly assigned to groups based on nails used: Synthes versus Zimmer, Synthes versus Richards, and Zimmer versus Richards. The reconstructions were cyclically loaded in bending for 2000 cycles and then loaded to failure. The mean stiffness of the Synthes, Zimmer, and Richards reconstructions was 17%, 40%, and 40% of the intact femora, respectively. The Richards construct was the strongest, and predominately failed by fracture at the distal interlocking screw hole. The Zimmer construct failed by bending of the nail at the osteotomy site and fracture of the proximal femoral shaft. The Synthes construct was the most flexible and least strong and failed by bending of the spiral, retrograde blade with concomitant fracture of the femoral neck. This study indicates that fixation of subtrochanteric femur fractures with a Synthes spiral blade or Richards or Zimmer reconstruction nails provides stable fixation for postoperative loading conditions. However, the Richards and Zimmer nails were able to withstand higher loads than was the Synthes nail before failure.
To find out whether adhesive techniques could have a role in bone fixation in selected cases an in vitro comparison between the current 'Champy' miniplate system and bonded stainless steel was undertaken using cyanoacrylate or dental composite cement. 33 bovine ribs were sectioned to simulate fracture separation, divided randomly into three groups, and immobilised by one of the three treatments. Distraction across the 'fracture' was produced using a universal testing apparatus, and forces at failure were recorded in Newtons (N). Image analysis enabled the contact area of the adhesive to be determined in mm2, so the bond strength in N/mm2 was derived. The Champy system failed at a significantly greater force (N) than the adhesives (p = 0.000). There was no significant difference in bond strength between either of the adhesive systems tested.
An 18-month-old female crossbred dog was presented with a unilateral sacroiliac luxation and separation of the pelvic symphysis. Surgical correction of the luxation with screw fixation led to entrapment of the urethra between the symphyseal parts of the two hemipelves.
Five configurations of pins or screws interconnected with polymethylmethacrylate (PMMA) were applied to isolated canine lumbar spines (L2 to L5) in which a complete fracture-luxation had been produced at L3 to L4. Twenty-five repaired spines and five intact control spines were subjected to four-point bending and tested once to failure in ventral flexion. The purpose of this study was to determine the effects of pin number, pin angle, and use of 3.5-mm cortical bone screws instead of smooth 3.2-mm diameter pins on rigidity and ultimate strength of spinal fractures repaired by the implant-PMMA fixation technique. Bending moment versus the angular deformation curves were recorded. Rigidity, bending moment at 10 degrees angular deformation, moment at failure, and deformation at failure of each type of fixation were compared using analysis of variance. Spinal segments stabilized with eight pin-PMMA fixation had significantly greater rigidity and strength at failure than four pin-PMMA fixations (P < .05). Furthermore, spinal segments stabilized with eight pins angled away from the fracture failed at significantly greater bending moment than those with eight pins angled toward the fracture (P < .05). However, for four-pin fixation, greater strength was achieved by angling pins in the bone toward the fracture site (P < .05). Screw-PMMA fixations failed by screw bending and were less rigid and weaker at failure than the corresponding configuration of pin-PMMA fixation (P < .05).
Measurement of the velocity of propagation and attenuation of ultrasound (200 kHz) is believed to be a useful non-invasive technique for assessing the mechanical properties of bone. A new method for the determination of ultrasound velocity and attenuation of longitudinal waves in cortical bone was used in vivo and in situ on intact and fractured human tibiae. The measured ultrasound attenuation and velocity were found to be unaffected by the soft tissue between transducers and bone. The ultrasound velocity in vivo on control tibiae was 3614 +/- 32 m s-1 and the attenuation was 5.52 +/- 0.43 dB MHz-1 cm-1. The ultrasound velocity in fractured tibiae was considerably lower 1 week after fracture (2375 +/- 82 m s-1), but had significantly increased after 3 weeks (to 2882 +/- 90 m s-1). A higher attenuation was measured 1 week after fracture (17.81 +/- 3.91 dB MHz-1 cm-1), but it had decreased again 3 weeks after fracture (10.42 +/- 3.56 dB MHz-1 cm-1). In situ studies under well-defined conditions confirmed the in vivo results. The effects of internal plate fixation and gradually cutting through the cortex on the ultrasound velocity and attenuation were studied in situ. These results demonstrate the clinical potential of this technique for the non-invasive assessment of bone fracture healing.
56 distal radius fractures were followed for a median period of 54 months (31-88 months) following the accident. Conservative treatment (immobilisation in a plaster alone) was compared to percutaneous K-wire fixation. The two groups of patients were matched in regard to type of fracture, age (+/- 5 years) and sex. The functional end result was assessed according to the scoring system of Gartland/Werley, which was modified by Solgaard. The operative treatment modality showed better functional end results, especially for intraarticular fractures, when compared to the conservatively treated fractures.
Plate fixation is considered by many clinicians to be the treatment of choice for displaced diaphyseal fractures of the forearm. One possible complication associated with plate fixation is refracture with the plate in situ or after plate removal. With the plate in situ, refracture typically occurs through the last screw hole near the end of the plate. Some clinicians have advocated the use of unicortical end screws to minimize the risk of such refractures. In this study, we performed a series of in vitro tests to compare the breaking strength of plated bone analogues that used either unicortical or bicortical end screws. The plated constructs that used unicortical end screws were significantly weaker in the two most important physiologic loading modes. Based on these results, we conclude that the use of unicortical end screws may result in a greater risk of refracture with the plate in situ.
The best way to stabilize supracondylar femur fractures remains debatable. Previous studies have compared internal fixation to intramedullary fixation, but none have compared the stiffness characteristics and strength of the 95 degrees angled blade plate (ABP) with the 95 degrees condylar side plate and screw (DCS). 14 synthetic femora were cut in half and the proximal pole of the distal fragment was made secure. A 1 cm gap was made parallel to the femoral condylar weight-bearing surface to create an extraarticular supracondylar femur fracture (OTA 33-A3). 7 femora were stabilized with an ABP and 7 with a DCS. Using an MTS compression/torsion servohydraulic testing machine, each femur was tested in 7 modes of loading: (1) axial compression; (2) anterior compression; (3) posterior compression; (4) medial compression; (5) lateral compression; (6) torsion in external rotation; and (7) torsion in internal rotation. The stiffness of the construct in each mode, the "maximum load in axial compression", and the fatigue characteristics in axial compression were measured. The DCS showed a statistically significant greater stiffness in axial compression and average maximal load than the ABP. The fatigue tests revealed no evidence of permanent deformation or loosening of either construct.