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PubMed1999

Determining the angle of screw placement for internal fixation of calcaneal fractures.

OBJECTIVE: This study was designed to determine the angle off the perpendicular to the lateral calcaneal wall at which a screw would need to be angled to avoid entering the subtalar joint medially. It also determined the distance inferior to the articular surface at which a screw would need to be placed to avoid that penetration if the screw was placed perpendicular to the lateral calcaneal wall. METHODS: Eight specimens were dissected and the calcaneus was removed. The measurements were taken from portions of the subtalar joint. RESULTS: To avoid medial penetration, a screw at the anterior portion of the posterior facet would need to be angled 5 degrees plantar medially or placed 1.5 millimeters below the edge of the articular surface. In the midportion, placements are 20 degrees or 10 millimeters; posteriorly, placements are 32 degrees or 15 millimeters. CONCLUSION: This study shows that using a lateral approach, it is possible to position internal fixation screws without disrupting the articular surfaces of the medial subtalar joint.

Ankle Injuries↗

PubMed1999

A biomechanical analysis of internal fixation of complex tibial plateau fractures.

OBJECTIVE: To compare the mechanical stability of fixation of an unstable bicondylar tibial plateau fracture with several different fixation techniques in a cadaveric model. DESIGN: Randomized laboratory investigation using a simulated bicondylar tibial plateau fracture with metaphyseal-diaphyseal dissociation. SETTING: Complex tibial plateau fractures were instrumented and tested under ramp and cyclic loading conditions on a servohydraulic materials testing machine. INTERVENTION: Each tibia was instrumented sequentially with a lateral buttress plate, a lateral and a medial buttress plate, and a lateral buttress and an anteromedial antiglide plate for ramp load testing. For cyclic testing, one of the three constructs was used on each specimen. MAIN OUTCOME MEASUREMENTS: Vertical subsidence of the medial tibial plateau was measured in both ramp and cyclic loading in order to evaluate the three internal fixation techniques. RESULTS: No significant difference was measurable between the dual buttress construct and the lateral buttress/anteromedial antiglide construct. However, the lateral buttress plate alone provided significantly less stability. CONCLUSIONS: A lateral buttress plate with an anteromedial antiglide plate may provide equally effective fixation as compared with the dual buttress plating technique in complex tibial plateau fractures. This less invasive technique may also be associated with fewer complications due to the lack of soft tissue stripping that is required for its application.

Aged↗

PubMedDate not supplied

An experimental study of devices for internal fixation of distal femoral fractures.

Tibial traction for distal femoral fractures, followed after four to eight weeks by plaster, is the common treatment. Because of improved methodology, the proportion of surgically treated fractures had increased. Stable osteosynthesis with different plates is an established therapy for distal femoral fractures. In elderly or other patients with bone fragility, however, these operations often fail. The majority of the distal femoral fractures occur in such patients, and traction in bed is therefore often used. A less rigid device was constructed to meet the special circumstances with bone fragility. This device consists of two Ender's nails: one is inserted from each condyle, and each is connected to two cancellous screws traversing both condyles. The strength of this semielastic osteosynthesis was compared with four existing devices (AO, Rush, Zickel, Ender). Fixation was carried out in 17 pairs of osteotomized postmortem preparations from patients older than 60 years of age. The specimens were submitted to constant bending rate, and the load deformation was registered. The fixation with the condylar plate was strongest and showed the lowest flexibility. The Ender's nails and the Rush pins showed a tendency to lose their Condylar stabilization early. This was less pronounced with the Zickel nail, which, however, tended to displace at the osteotomy site during insertion and fracture the proximal fragment due to the limited bending ability of the blade construction. The new, semielastic device (ECS) was constructed to meet the special circumstances with bone fragility. It consists of two cancellous screws traversing both condyles. It combined easy insertion with moderate flexibility and high residual strength. In extension, it deflected 40 degrees without influencing residual stability. It is an interesting alternative to rigid internal fixation or traction in bed for osteoporotic patients with distal femoral fractures. In combines rigid screw fixation in the condylar part with an elastic adjustment in the femoral shaft above.

Aged↗

PubMed1992

Intense granulomatous inflammatory lesions associated with absorbable internal fixation devices made of polyglycolide in ankle fractures.

Since absorbable internal fracture fixation devices made of polyglycolide have been increasingly used clinically, a peculiar type of complication has emerged. After an initially uneventful course, a local nonbacterial inflammatory reaction appears two to four months after the operation, resulting in a copiously discharging sinus on the skin. A series of 286 patients with unimalleolar or bimalleolar fractures were treated by open reduction and internal fixation using cylindrical rods made of polyglycolide. Among these there occurred 18 nonbacterial inflammatory tissue responses (6.3% of the total) requiring surgical drainage. Six patients had an intense reaction necessitating repeated surgical measures and inpatient management. The hospital stay of these patients averaged 18 days. The mean duration of the discharge from the lesions was 10.8 weeks. Microscopic examination of biopsy specimens showed a nonspecific foreign-body reaction composed mainly of neutrophilic polymorphonuclear leukocytes and foreign-body giant cells phagocytizing the polymer debris left behind by the decomposing implants. On roentgenograms, osteolytic increase of the diameter of the implant channels was observed, but the bony union of the fracture seemed not to be disturbed. Thus the factors increasing the susceptibility of some individuals to this complication remain unknown.

Ankle Injuries↗

PubMed1981

The advantages of titanium alloy over stainless steel plates for the internal fixation of fractures. An experimental study in dogs.

An experimental study is reported of fracture healing in the femora of 36 Beagle dogs, comparing the results of using stainless steel plates with those of using less rigid titanium alloy plates. The alloy plates led to the appearance of a small amount of periosteal callus without any histological evidence of fracture instability, thus allowing the radiological assessment of fracture union. This also produced less bone loss during the remodelling phase. Radiological measurements 24 weeks after osteotomy showed cortical thickness to be reduced by six per cent under titanium alloy and by 19 per cent under stainless steel, while histological measurements showed a total bone loss of 3.7 per cent under titanium alloy and of 11 per cent under stainless steel plates. Removal of the titanium alloy plates after eight weeks followed by a recovery period of 16 weeks produced an increase of cortical thickness of 69 per cent and a gain in total bone mass of 30 per cent. Titanium alloy plates also produced less soft-tissue reaction than stainless steel plates. It is concluded that this alloy is a promising material for internal fixation devices.

Alloys↗

PubMedDate not supplied

Biomechanical comparison of conventional open reduction and internal fixation versus calcium phosphate cement fixation of a central depressed tibial plateau fracture.

OBJECTIVE: To evaluate the effect of calcium phosphate bone cement on stability and strength of the fracture repair in a central depressed tibial plateau fracture cadaveric model. DESIGN: Paired human cadaveric tibial specimens. SETTING: Biomechanics laboratory. PATIENTS: Uniform pure depression fractures of lateral tibial plateau were created in twenty human cadaveric tibial specimens. INTERVENTION: The first part of the study used thirteen pairs of tibiae in two groups: a control group receiving the conventional treatment of morselized bone graft and two cancellous screws and an experimental group receiving calcium phosphate bone cement only. The second part of the study used seven pairs of tibiae in two experimental groups: one receiving calcium phosphate bone cement with a more extensive void preparation and the other group receiving calcium phosphate bone cement with a more extensive void preparation and two screws. MAIN OUTCOME MEASUREMENTS: Each tibia was loaded on a Material Testing Systems machine from twenty newtons to 250 newtons for 10,000 cycles to simulate immediate postoperative load transmission to the tibial plateau. Specimens were then loaded to failure to determine the ultimate strength of the reconstruction. Displacement of the articular fragment and stiffness at each cycle were measured during dynamic loading. Peak load, deformation at peak load, and resistance to depression were measured during the load to failure. RESULTS: The treatment of depressed tibia plateau fractures with a calcium phosphate cement provides equivalent or better stability than conventional open reduction and internal fixation in pure depression tibial plateau fractures. If the fracture void is prepared by eliminating the cancellous bone under the subchondral plate, the results are further improved. CONCLUSIONS: This study suggests that the non-weight-bearing postoperative period may be significantly reduced without clinically significant articular collapse.

Absorptiometry, Photon↗

PubMed1988

Internal fixation for occipito-cervical fusion.

We describe a method of internal fixation for occipito-cervical fusion utilising a standard "small fragment" T-plate bent and fixed to the skull with three screws. The lower end of the plate is screwed and wired firmly to the spine of the axis. Of 14 patients so treated, 12 fused, one died and one failed to unite to the skull. Of eight with cord signs, seven remitted or improved and one died.

Arthritis, Rheumatoid↗

PubMed1993

Biomechanical analysis of the Cotrel-Dubousset spine internal fixator in different load conditions.

The aim of the present research is to analyse the mechanical behaviour of the Cotrel-Dubousset spine internal fixator using numerical and experimental techniques. Simple experimental and numerical models of a spine section (four vertebrae of the thoraco-lumbar region) were developed in order to evaluate the response of the system, particularly the stress-strain state in the rods, by means of strain-gauge measurements. The system was subjected to combined compressive and bending static loading and the deformations of the system were measured on models simulating physiological and pathological conditions, with and without the fixator.

Biomechanical Phenomena↗

PubMed1993

Intra-articular fractures of the distal tibia: surgical management by limited internal fixation and articulated distraction.

A series of 12 patients with severe intra-articular (pilon) fractures of the distal tibia were treated by open reduction and internal fixation of the principal articular fragments. Tibial length was restored and maintained by an articulated external fixator which allowed early mobilization of the joint, and associated fibular fractures were fixed internally. Of the patients, nine have been followed up for an average of 33 months (range 18-60 months); three are still undergoing active treatment. Results have been assessed using the scoring system devised by Karlsson and Peterson. Four patients had scores > 80, four had scores between 50 and 79, and one had a score < 50. This technique is less invasive than conventional open procedures that require the use of a tibial plate and may be of particular value in the management of open fractures.

Adult↗

PubMed2006

Muscle strength recovery and its effects on outcome after open reduction and internal fixation of acetabular fractures.

OBJECTIVE: To determine the relationship between muscle strength recovery and functional outcome in patients who were treated for an acetabular fracture via an anterior approach. DESIGN: Case series. SETTING: University Medical Center. PATIENTS: Fifteen patients with a displaced acetabular fracture treated via an anterior, ilioinguinal approach were studied. Hip muscle strength of these patients was then compared with the muscle strength of a similar group of patients treated via a Kocher-Langenbeck approach (posterior approach). These patient groups were then combined and muscle strength recovery was compared with the functional outcome. MAIN OUTCOME MEASURE: Primary outcome measures included hip muscle strength, including work (J/min) and maximum torque (Nm/kg) for abductors/adductors and flexors/extensors. Clinical outcome was assessed with the Musculoskeletal Function Assessment (MFA) questionnaire and the results correlated with muscle strength. Secondary outcome measures included adequacy of fracture reduction, radiographic grade, severity of heterotopic ossification, and range of motion of the affected and unaffected hips. RESULTS: At an average follow-up of 44 months, patients treated via an anterior approach had an overall muscle strength deficit of 9%. Hip extension strength was affected to the least extent (6% deficit when compared with the unaffected hip) whereas abduction, adduction, and flexion strength was affected to a greater degree. For each measure the affected side was typically weaker than the unaffected side. The average MFA score for the anterior approach group was 17 (range, 0 to 47) with most patients reporting poorest results in those domains assessing activities of the arms and legs, and those involving life changes and feelings. When MFA scores were compared with the muscle strength, a relationship was found between hip extension/flexion work and maximum torque and hip adduction work and maximum torque and MFA score. For each of these muscle groups, patients reported worsening function with decreased muscle strength. Assessment of the most recent radiographs revealed 9 patients with an excellent radiographic grade, 3 patients with a good grade, 1 patient with a fair grade, and 2 patients with a poor grade. Hip range of motion was not statistically different when the affected hip was compared with the unaffected hip, and none of these variables correlated with outcome. Heterotopic ossification was found in 8 patients; 4 with grade 1, and 4 with grade 2. CONCLUSIONS: Standardized muscle strength determination and completion of an MFA questionnaire provided a thorough evaluation of patients who had undergone open reduction and internal fixation of a displaced acetabular fracture. In these patients, hip muscle strength after operative treatment of a displaced acetabular fracture directly influences patient outcome. Therefore, in order to maximize the outcome of these patients, particular attention must be paid to postoperative muscle strengthening protocols and accurate and validated methods to assess strength and outcomes.

Acetabulum↗

PubMed2004

Preparation and characterization of biodegradable chitosan/hydroxyapatite nanocomposite rods via in situ hybridization: a potential material as internal fixation of bone fracture.

A transparent and slight yellow chitosan (CS)/hydroxyapatite (HA) nanocomposite with high performed, potential application as internal fixation of bone fracture was prepared by a novel and simple in situ hybridization. The method solves the problem of the nano-sized particle aggregation in polymer matrix. XRD, TEM and SEM were used to determine component and morphology of the composite. Results indicated that nano-HA particles were dispersed well in CS matrix, which can also be proved by the transparent appearance of composite rod, and that the structure of composite is assembled by CS molecule in the order of layer-by-layer. The mechanical properties of the composite were evaluated by using bending strength and modulus, and compared with some other bone replacement materials such as PMMA and bone cement. The initial mechanical properties of bending strength and modulus of composite are 86 MPa and 3.4 GPa, respectively, which is double or triple times stronger than that of PMMA and bone cement. It was found that the bending strength and modulus of CS/HA with ratio of 100/5 (wt/wt) is slightly higher than that of pure CS rod. The addition of HA can also reduce the ratio of water absorption of composite, which postponed the retention of mechanical properties of CS/HA composite under moisture condition. The phenomenon can be predicted with the fit exponential function according the data measured.

Absorbable Implants↗

PubMed1994

Stability and effect on the soft tissue profile of mandibular advancement with sagittal split osteotomy and rigid internal fixation.

The stability and the effect on the soft tissue profile of mandibular advancement with sagittal split osteotomy and rigid internal fixation was studied prospectively in 30 consecutive patients, 17 to 32 years old, who had a distal occlusion. Profile roentgen cephalometric recordings were made immediately before and shortly after surgery as well as 13 months postsurgically. The mean advancement of the mandible 3 to 8 days after surgery was 5 mm. On average, there was only a small increase in the anterior facial height. At the follow-up after 13 months, the advancement of the mandible had, in most cases, partially relapsed so that the median net effect was 70%. In six subjects, however, the mandible had advanced slightly further. The skeletal relapse was partially masked by compensatory movements of the maxillary incisors so that the mean net effect on the overjet was 83%. The amount of relapse was positively correlated to the magnitude of advancement during surgery. Likewise, a postsurgical relapse of the anterior facial height was positively correlated to the magnitude of advancement during surgery. Likewise, a postsurgical relapse of the anterior facial height was positively correlated to the magnitude of the vertical surgical displacement anteriorly and posteriorly. The soft tissue chin closely followed the underlying hard tissue. The mean net effect on the labial fold, however, was smaller, 88% of the mandibular advancement. The net effect on the lower lip was 66% of the advancement of the mandibular incisor.

Adolescent↗

PubMed1997

[Monosegmental internal fixator instrumentation and fusion in treatment of fractures of the thoracolumbar spine. Indications, technique and results].

Dorsal fusion with the internal fixator has become the standard treatment of instabilities and deformities of the thoracolumbar spine. With our new device, the modular spine fixator (MSF), which has been specially designed for short-distance instrumentations, we have increasingly been treating unstable injuries of the thoracolumbar spine by one-level stabilization. Prerequisite is an accurate evaluation of the indication, including CT and MRI to assess the involvement of the intervertebral disc and the ligamental structures. The operative technique differs in some details from the procedure in more-multi-level instrumentations, especially concerning the application of the pedicle screws. The instrumentation is always combined with posterior allogenic bone grafting. Since the beginning of 1993 we also perform anterior autogenic transpedicular bone grafting. Between January 1991 and July 1995, 57 one-level stabilizations with the MSF were performed. Of the 57 patients operated on 39, 27 men and 12 women, with an average age of 41 years, have had a clinical and radiographic follow-up examination so far, on average, 27 months after the accident. Seventeen patients were completely free of pain and 17 patients (were only) sensitive to weather changes or had minor pain during great physical stress. Five patients had pain even during slight physical stress or at rest. The preoperatively measured Cobb angle was 15.1 degrees on average, after the operation 5.2 degrees, and at the time of the follow-up examination amounted to 8.1 degrees. The patients' range of motion was normal. Only five minor complications have been seen. No implant fatigue failure has been noted in this series. We derive from these results that, for correct indications, one-level stabilization can be performed successfully and should be firmly established in the operative treatment of unstable fractures of the thoracolumbar spine.

Adolescent↗

PubMed2001

Internal fixation on the lower cervical spine--biomechanics and clinical practice of procedures and implants.

The decision to opt for a particular internal fixation procedure of a traumatized unstable lower cervical spine should be based on analysis and implementation of scientific and clinical data on the biomechanics of the intact, the unstable and the implant-fixed spine. The following recommendations for surgical stabilization of the lower cervical spine seem, therefore, to be justified. Firstly, the surgical procedure should be to bring about decompression, realignment, and stability. Secondly, the anterior approach should be the primary and preferred one. With regard to surgical and positioning technique, this access clearly involves fewer problems than the posterior approach; if required, unrestricted additional cord decompression can take place; implant fixation is technically simple, and the fusion is under direct compression, thus allowing optimal fusion healing. The awareness of instability and type of implant permits functional therapy, above all for the paraplegic patient. Thirdly, for traumatic conditions, posterior methods should be reserved for exceptional indications. The restriction to this approach is that the anterior column must be intact and a multi-segmental fixation must be used. Posterior fixation seems, therefore, to be more appropriate for degenerative, rheumatoid or tumorous instabilities than for traumatic instabilities. The cerclage wire technique depends on intact osseous posterior elements, while after laminectomy only implants fixed with screws can create safe stability. The disadvantages of the posterior access for the proprioception of the cervical muscles and the subjective symptoms of the patient are known and must be taken into account. Fourthly, combined techniques are indicated for highly unstable or particularly complex injuries. On the cervicothoracic junction, or in cases of Bechterew's disease, the decision is justifiably made in favor of this technique, which can be performed as a one-stage or two-stage operation. Finally, whenever possible, selection of the implant should take into account the foreseeable developments in diagnostic procedures, and therefore, in view of the modern imaging techniques likely to be used in any follow-up examinations required later, the implant chosen should be made of titanium.

Biomechanical Phenomena↗

PubMed1987

Open reduction and internal fixation of radial head fractures associated with olecranon fracture or dislocation.

Six fracture dislocations or dislocations of the olecranon associated with radial head fractures were treated with open reduction and internal fixation of the radial head. The olecranon was reduced and if fractured (three cases) was internally fixed. Postoperatively, early active range of motion was achieved in all cases. Twelve to 48 months after surgery, there was an average loss of 18 degrees of elbow extension and 56 degrees of forearm rotation. An average of 132 degrees of flexion was maintained. There was no elbow instability or wrist pain.

Adolescent↗

PubMed1986

Internal fixation with Knodt's rods.

Knodt's rods are an effective distraction internal fixator for promoting fusion for lumbar spine surgery. The chief disadvantage in 92 cases was a removal rate of about one third. The 93% fusion rate, and instant mobilization of the patient are reasonable trade-offs for the disadvantages of a second operation for removal of the rods.

Humans↗

PubMed1997

Open reduction and internal fixation of the distal humerus: functional outcome in the elderly.

OBJECTIVE: To examine the functional outcome of a cohort of elderly patients after open reduction and internal plate and screw fixation of distal humerus fractures. DESIGN: Retrospective review of a consecutive series of patients older than 60 years of age who underwent plate and screw fixation of a distal humerus fracture. MATERIALS AND METHODS: Eighteen patients, aged 63 to 85 years (average, 71 years), underwent open reduction and internal fixation of a displaced distal humerus fracture using plates and screws. Three were Arbeitsgemeinschaft für Osteosynthesefragen/Association for the Study of Internal Fixation (AO/ASIF) type A, 2 were type B, and 13 were type C fractures. The patients were reviewed at a minimum follow-up of 1 year after surgery. MEASUREMENTS AND MAIN RESULTS: All patients had a good or excellent clinical result using a standardized method of evaluation. General health status, as measured by the SF-36 Health Survey, was comparable to the published norms for U.S. male and female populations of similar age. CONCLUSION: Open reduction and internal fixation of the distal humerus in the elderly can provide good clinical results. Good clinical results, however, do not imply good general health status.

Aged↗

PubMed1992

[Use of internal fixator in injuries of the thoracic and lumbar spine].

Between 1984 and 1989 51 patients with spinal traumata received surgical treatment by means of Fixateur interne. The results of patients' postsurgical check-up were as follows: Cases with incomplete neurological dysfunctions (levels Frankel B-D)-especially lumbar-showed improvements of neurological deficiencies up to three levels Frankel after emergency decompression and stabilization. The majority of cases with complete paraplegia-especially thoracic-did not subside. This holds true even for the results of a second check-up after about three years. A correlation between the degree of stenosis of the spinal canal and the neurological dysfunctions could not be established. The results of segmental stabilization by means of internal fixator and of definitive spondylodesis by means of autogenous spongiosa were positive, as was the spine proof and the patients' postsurgical function.

Adolescent↗