Time Of Fixator Removal Research Articles

A Pelvic Support Osteotomy and Femoral Lengthening with Monolateral Fixator

Pelvic support osteotomies for chronically dislocated hips improve stability but result in limb-length discrepancy and valgus deformity of the knee. We prospectively evaluated and followed up 16 patients (14 females, two males) to ascertain whether a monolateral external fixator could achieve a pelvic support osteotomy and eliminate the limb-length discrepancy without disturbing knee motion. The patients had a mean age of 25.3 years at the time of surgery. The Harris hip score, knee range of motion, and Trendelenburg sign were evaluated preoperatively and at followup. The average time from fixator application until removal was 7 months (range, 5.2-9.5 months). The followup averaged 52.5 months (range, 26-84 months). The mean Harris hip score increased from 50 points (range, 32-73 points) preoperatively to 87.6 points (range, 67-98 points) at last followup. Four patients retained a positive Trendelenburg sign. At the time of fixator removal, 88% of preoperative knee range of motion was retained, and preoperative knee motion was achieved at last followup in all patients. The monolateral external fixator was suitable for a pelvic support osteotomy, equalizing limb-length discrepancy, and obtaining lower extremity alignment. This method achieved a pain-free, functional hip and good knee motion. Therapeutic study, Level IV (case series). See the Guidelines for Authors for a complete description of levels of evidence.

Mandibular fracture repair in dogs and cats using epoxy resin and acrylic external skeletal fixation

SummaryMandibular fractures in 17 dogs and in eight cats were managed using external skeletal fixation (ESF) with acrylic or epoxy resin connecting bars. In order to maintain dental occlusion during fracture repair pha- ryngostomy or tracheostomy was performed in 12 dogs and in six cats to permit inhalational anaesthesia during surgery. All of the fractures healed with the exception of fractures in two dogs. Mandibular external skeletal fixation was well tolerated and there was not any evidence of iatrogenic damage to teeth nor to neurovascular structures within the mandible. Implant loosening was commonly observed at the time of fixator removal, but it did not affect the outcome.

Evaluation of the fracture site mechanical properties in vivo by monitoring the motion of a dynamic pin clamp during simulated walking

Objective. To monitor pin clamp motion using a displacement sensor over time during weight bearing and to investigate whether this method could contribute to quantitative assessment of the mechanical properties of fracture healing. Methods. Patients with a shaft fracture of the tibia were monitored, all of whom were in the stage of dynamization. The hifixator equipped with a ball bearing mechanism was used as a dynamic external fixator. The displacement was recorded versus time during stamping with weight bearing of the patients. The displacement curve had an oscillatory component synchronized with touch down and lift up of the foot, a time-dependent component expressed by shifting of the baseline, and an irreversible component during a non-weight bearing period after stamping. The three components were analyzed with a simple Voigt model. Results. In all patients, both the amplitude of the oscillatory component and the time-dependent component expressed as retardation time decreased as fracture healing proceeded, and by the time of fixator removal the irreversible component had disappeared. Conclusions. The monitoring method could quantitatively evaluate viscoelastoplasticity of the healing fracture site. Relevance. Until now, there has been few method for assessing the viscoelastic property of the healing fracture site in vivo. Although the method described here involves some assumptions and approximations, it was able to quantitatively assess the viscoelasticity of the healing fracture site.

Distraction Osteogenesis for Nonunion After High Tibial Osteotomy

The purpose of this study was to determine whether distraction osteogenesis can be used to treat hypertrophic nonunion associated with angular deformity and shortening after Coventry style high tibial osteotomy. Five consecutive patients were retrospectively reviewed. In all patients the alignment had collapsed into excessive varus or valgus and leg length discrepancy was present. The leg length discrepancy, malalignment, and nonunion were treated simultaneously with distraction. Union was achieved by the time of fixator removal, which averaged 4.4 months. The Hospital for Special Surgery knee score significantly improved from 42 to 89. The mechanical axis deviation significantly improved by 5 cm. The coronal plane deformity significantly improved by 13 degrees, and leg length discrepancy improved significantly from 2.3 to 0.5 cm. Metaphyseal bone stock increased by 43%, and the Insall-Salvati ratio increased from 1.1 to 1.2 and remained within normal limits. All patients were satisfied with the procedure, and none have had or need a total knee replacement at an average followup of 4 years. Distraction osteogenesis of nonunion after high tibial osteotomy is a minimally invasive and successful procedure. It leads to bony union with correction of deformity and leg length discrepancy and prevents the need for total knee replacement at intermediate-term followup. The increase in metaphyseal bone stock may make total knee replacement technically easier.

Correction of complex foot deformities using the Ilizarov external fixator

There are many drawbacks to using conventional approaches to the treatment of complex foot deformities, like the increased risk of neurovascular injury, soft-tissue injury, and the shortening of the foot. An alternative approach that can eliminate these problems is the Ilizarov method. In the current study, a total of 23 deformed feet in 22 patients were treated using the Ilizarov method. The etiologic factors were burn contracture, poliomyelitis, neglected and relapsed clubfoot, trauma, gun shot injury, meningitis, and leg-length discrepancy (LLD). The average age of the patients was 18.2 (5-50) years. The mean duration of fixator application was 5.1 (2-14) months. We performed corrections without an osteotomy in nine feet and with an osteotomy in 14 feet. Additional bony corrective procedures included three tibial and one femoral osteotomies for lengthening and deformity correction, and one tibiotalar arthrodesis in five separate extremities. At the time of fixator removal, a plantigrade foot was achieved in 21 of the 23 feet by pressure mat analysis. Compared to preoperative status, gait was subjectively improved in all patients. Follow-up time from surgery averaged 25 months (13-38). Pin-tract problems were observed in all cases. Other complications were toe contractures in two feet, metatarsophalangeal subluxation from flexor tendon contractures in one foot, incomplete osteotomy in one foot, residual deformity in two feet, and recurrence of deformity in one foot. Our results indicate that the Ilizarov method is an effective alternative means of correcting complex foot deformities, especially in feet that previously have undergone surgery.

The Ilizarov method in the treatment of complex foot deformities

Objectives: There are many drawbacks in the use of conventional approaches in the treatment of complex foot deformities. These include increased risk of neurovascular injury, soft tissue injury, and shortening of the foot. The Ilizarov method seems to be an alternative approach that can eliminate these problems. Methods: Twenty-two patients (mean age 18.2 years; range 5 to 50 years) with deformed feet (n=23) were treated using the Ilizarov method. The deformities included burn contracture, poliomyelitis sequela, neglected and relapsed club foot, trauma, gun shot injury, meningitis sequela, and leg length discrepancy. Six feet had a history of several previous operations. The mean fixator duration was 5.1 months (range 2 to 14 months). Corrections were performed with (14 feet) or without (9 feet) osteotomy. The osteotomy types used were supramalleolar, U- and V-shaped, and midfoot osteotomies. Additional procedures included three tibial and one femoral osteotomies for lengthening and deformity correction, and one tibiotalar arthrodesis. The mean postoperative follow-up was 25 months (range 13 to 38 months). Results: At the time of fixator removal, a plantigrade foot was achieved in 21 feet. Improved gait was obtained in all cases. Pin-tract problems were observed in all cases. Other complications were toe contractures in two feet, metatarsophalangeal subluxation from flexor tendon contractures in one foot, incomplete osteotomy in one foot, residual deformity in two feet, and recurrence of deformity in one foot. Conclusion: Our results indicate that the Ilizarov method, albeit technically difficult, is an effective alternative treatment for correcting complex foot deformities, especially those in which previous surgical attempts were made.

Surgical treatment of lumbosacral instability caused by discospondylitis in four dogs.

To describe a surgical technique involving distraction and stabilization of the lumbo-sacral vertebral segment using an external skeletal fixator in dogs with lumbosacral instability caused by discospondylitis. Retrospective clinical study. Four client-owned dogs. Medical records of all dogs diagnosed with discospondylitis from 1994 to 1997 were identified and reviewed. Four dogs with lumbosacral discospondylitis requiring surgical treatment were then specifically studied. Surgical technique, clinical signs, preoperative diagnostic investigation, radiographic findings, and the results of short-term and long-term reevaluations were recorded. Twelve dogs with discospondylitis were identified, 4 of which had lumbosacral discospondylitis. These 4 dogs underwent surgical distraction and stabilization because they failed to respond to medical treatment. Three dogs received a cancellous bone graft between L7 and S1 and had rapid interbody fusion of this vertebral segment. The dog that did not receive a graft did not have interbody fusion at the time of fixator removal. This did not affect the final clinical outcome. Lumbosacral pain and neurological deficits present before surgery rapidly subsided after the procedure. All dogs received concurrent antibiotic treatment for a minimum of 4 weeks. All dogs were clinically normal at the time of fixator removal and all continued to do well during the follow-up period (8-48 months; mean, 27.5 months). Lumbosacral discospondylitis may not respond well to conservative treatment because of the mobility of the affected space. Surgical treatment involving distraction and stabilization to obtain intervertebral fusion is very effective in treating lumbosacral instability caused by discospondylitis.

Secondary Fractures Associated with External Fixation in Pediatric Femur Fractures

Sixty-six femur fractures sustained by children ages 4-14 years and treated with external fixation were reviewed retrospectively to assess factors influencing the incidence of refracture. The total rate of secondary fracture was 12% (eight patients) including five recurrent fractures at the original fracture site and three fractures through the pin sites. After removal of the external fixator, five patients refractured at the original fracture site and one patient fractured through a pin tract. Two patients fractured at pin sites while the fixator was still in place. Multivariate linear-regression analysis showed no correlation between the incidence of refracture and fracture pattern, percentage of bone fragment contact after fixator application, type of external fixator, or dynamization. A statistically significant association (p < 0.05) was found between the number of cortices demonstrating bridging callus [on both anteroposterior (AP) and lateral views] at the time of fixator removal and the rate of refracture. Fractures showing fewer than three cortices of bridging callus had a three (33%) in nine rate of refracture, whereas fractures with three or four cortices of bridging callus had a two (4%) of 57 rate of refracture.

Changes of callus diameter during axial loading and after fixator removal in leg lengthening.

We retrospectively reviewed nine tibial lengthenings in seven achondroplastic patients. The callotasis method was used, and a unilateral type lengthener, either the Dynamic Axial Fixator (Orthofix, Italy; eight legs) or the High Functional Fixator (Matsumoto Co., Japan; one leg), was applied. The distracted length averaged 14.6 (range 10-18) cm. The minimum diameter of the callus was measured using a ruler on anteroposterior and lateral radiographs. The callus diameter ratio (%) was calculated as the callus diameter divided by the original diaphysis diameter. For periods during axial loading and after removal of the fixator in each patient, a single regression line was drawn on the callus diameter ratio data using the least squares method, and the diameter change rate (%/day) was evaluated by inclination of this line. The diameter change rates during axial loading were negative in six legs, but those after fixator removal were positive in all legs, and the latter were significantly greater than the former. The diameter change rates after fixator removal on the anteroposterior radiographs were negatively correlated with the callus diameter ratio at the time of fixator removal (r = 0.84, P = 0.0008). Simple axial loading may not be a sufficient mechanial environment for restoration of the physiological shape, and it is important to be aware that we cannot expect the callus diameter to increase by this means alone.

External fixation of pediatric femur fractures.

One-hundred and thirty-two children with 139 femur fractures were treated with external fixation from 1984 to 1993. Average age at presentation was 8.97 years. All fractures were followed until union, with an average time of external fixation of 11.4 weeks. There were no nonunions. Of 18 patients with definitive radiographic measurements at 2-year follow-up, 15 patients developed overgrowth (average, 8.7 mm) and three demonstrated shortening (average, 7.7 mm). No patient required treatment for residual leg-length discrepancy. Although pin-tract inflammation was common, pin-tract infection requiring intravenous antibiotics occurred in only six patients (4.5%). No patient developed osteomyelitis. Two fractures (1.4%) were not healed at the time of elective fixator removal, necessitating additional time in the fixator. There were two refractures (1.4%) and one fracture through a healing pin tract after fixator removal (0.7%).

External Fixation of Pediatric Femur Fractures

Summary: One-hundred and thirty-two children with 139 femur fractures were treated with external fixation from 1984 to 1993. Average age at presentation was 8.97 years. All fractures were followed until union, with an average time of external fixation of 11.4 weeks. There were no nonunions. Of 18 patients with definitive radiographic measurements at 2-year follow-up, 15 patients developed overgrowth (average, 8.7 mm) and three demonstrated shortening (average, 7.7 mm). No patient required treatment for residual leg-length discrepancy. Although pin-tract inflammation was common, pin-tract infection requiring intravenous antibiotics occurred in only six patients (4.5%). No patient developed osteomyelitis. Two fractures (1.4%) were not healed at the time of elective fixator removal, necessitating additional time in the fixator. There were two refractures (1.4%) and one fracture through a healing pin tract after fixator removal (0.7%).

Tibial Shaft Fractures

To assess the capability of CT in assessing stability of tibial shaft fractures with planimetry. Eighteen patients with fracture of the tibial shaft were treated by external fixator. All patients underwent CT 1, 6, 12, and 18 weeks postoperatively to assess the fracture healing. The callus formation and compacta were determined with planimetry. Fractometry, a noninvasive method to measure stability, was used as the gold standard to determine the stability of the fracture. The patients were divided into three groups according to different periods of time for removal of external fixation. Twelve patients with stable fractures showed a steady increase of callus, which was 50% higher after 12 weeks. Three patients with delayed fracture healing demonstrated an increase of callus of > 50% after 18 weeks. Three patients with unstable fractures obtained only callus formation of < 20% after 15-18 weeks. The external fixator was removed and endomedullary nails were used for stabilization. The CT data allow quantification of callus and compacta formation and are able to determine the stability of tibial shaft fractures.

New bone formation during leg lengthening. Evaluated by dual energy X-ray absorptiometry.

We measured the extent and rate of new bone formation over an 18-month period before, during and after the lengthening of ten leg segments in six patients aged between 8 and 18 years, using dual-energy X-ray absorptiometry (DEXA). New bone formation could be identified within one week of the start of distraction. As lengthening proceeded, the bone density of the gap fell, reaching minimum values at the time of maximal distraction. Consolidation of the regenerating bone was started 1 to 2 weeks later in the tibia, and 2.5 to 3.0 weeks later in the femur. The rate of mineral accretion in new bone was significantly greater in the tibia than in the femur (16 +/- 1.86%/month, and 11 +/- 1.1%/month respectively; mean +/- SEM). There was significant osteoporosis distal to the osteotomy, more in the tibia than in the femur, particularly on the side of the fixator. The bone mineral density of the distal segment remained low at the time of fixator removal (44.2 +/- 5.58% and 61.0 +/- 4.2% of the control values at the tibia and femur respectively) and was only partially reversed by subsequent weight-bearing. We conclude that dual-energy X-ray absorptiometry provides an objective and quantitative assessment of new bone formation during leg lengthening. The technique also allows the measurement of the distraction gap and the assessment of leg alignment from the high-resolution images. Its use may decrease the requirements for conventional radiography.

Healing of rabbit tibial fractures using external fixation. Effects of removal of the fixation device.

Bone healing after external fixation of rabbit tibial osteotomies was studied in order to throw light on the problem of the optimal time for removal of external fixation. The animals were divided into various groups according to different periods of time for removal of external fixation and sacrifice. The strength and stiffness of the healing bones at 12 weeks were greater in tibiae where the external fixator was removed at 4, 6 or 9 weeks than in those with the continuous presence of the fixator for 12 weeks. Although fixation is essential in the early healing period, it seems that bone healing is stimulated by the removal of the fixation after a certain period of time. The optimum time for removal of external fixation in the rabbit tibia was at 6 weeks of healing, when the bone had regained normal stiffness and about 50 per cent of normal strength. The clinical relevance of this investigation is that it might be rational to remove the external fixator before bone healing has been completed. If it is felt that healing is not secure when the fixator is removed, a tibial brace might subsequently be used for a short period.

Trauma to the Carpus, Tarsus, and Phalanges of Dogs and Cats

The methods described are those currently employed by the authors for the injuries described. As surgical results accumulate, we hope to modify and improve our methods. Many injuries to the carpus and tarsus have been omitted. Many questions remain unanswered. How long must external coaptation be applied? When is the optimum time for removal of internal fixation devices? Are sclerosing agents more successful for the management of interphalangeal luxations than primary suturing? Should autogenous cancellous bone be used in all arthrodeses? What is the best method of handling sesamoid fractures, and what is the best postoperative care for these fractures? When should passive joint movement be initiated? What is the owner's optimum role in providing rehabilitative physical therapy? Only be evaluating large numbers of clinical cases or controlling experimental cases can these questions be answered.