Objective Guidelines for Removing an External Fixator after Tibial Lengthening Using Pixel Value Ratio: A Pilot Study

During limb lengthening over an intramedullary nail, decisions regarding external fixator removal and weightbearing depend on the amount of callus seen at the lengthening area on radiographs. However, this method is subjective and objective evaluation of the amount of callus likely would minimize nail or interlocking screw breakage and refracture after fixator removal. We asked how many cortices with full corticalization of the newly formed bone at the lengthening area are needed to allow fixator removal and full weightbearing and how to radiographically determine the stage of corticalization. We retrospectively reviewed 17 patients (34 lengthenings) who underwent bilateral tibial lengthenings over an intramedullary nail. The average gain in length was 7.2 ± 3.4 cm. We determined the pixel value ratio (ratio of pixel value of regenerate versus the mean pixel value of adjacent bone) of the lengthened area on radiographs. There were no nail or screw breakage and refracture. Partial weightbearing with crutches was permitted when the pixel value ratio was 1 in two cortices and full weightbearing without crutches was permitted when the pixel value ratio was 1 in three cortices. The pixel value ratio on radiographs can be an objective parameter for callus measurement and may provide guidelines for the timing of external fixator removal. We cannot determine from our limited data the minimum pixel value in how many cortices would suggest safe removal, but we can say our criteria were not associated with subsequent refracture.     

Prediction of Callus Subsidence in Distraction Osteogenesis Using Callus Formation Scoring System: Preliminary Study

Objective

To develop the scoring system which describes both quality and quantity of callus formation to predict the callus subsidence.

Methods

Forty‐seven bony segments with an average lengthening of 5.17 ± 2.83 cm were included. The score was calculated based on the amount of callus classified in five patterns and the summation with the density of the callus classified in four patterns; the total score was 9. Bony subsidence >10% or >10° angulation were considered significant. We analyzed all of the data to find the most appropriate score that would prevent callus subsidence <10% and prevented angulation of the regeneration bone <10 degrees. Data was analyzed by using the receiver operating characteristic (ROC) curve. An area under the curve of 0.9–1 indicated an excellent test, 0.8–0.9 indicated a good test, 0.7–0.8 indicated a fair test, 0.6–0.7 indicated a poor test, and 0.5–0.6 indicated a fail test. The appropriate score for Ilizarov removal was selected from the highest sensitivity and specificity.

Results

Twenty‐two tibia segments and 25 femur segments were included. The mean of bone lengthening was 5.17 ± 2.83 cm (range, 1.6–13.5 cm) and the mean of percentage lengthening was 16.58% ± 10.03% (range, 4.63%–56.84%). The mean distraction period was 5 months. The average months of follow‐up for measurement of bony subsidence was 4.2 months. Mean subsidence was 21.06% (1.54%–57.44%). The mean of callus subsidence was 1.29 ± 1.17 cm (range, 0.03–4.72 cm). There were 32 segments (68%) with callus subsidence greater than 10% and 15 segments (32%) with subsidence less than 10%. The callus subsidence ranged from 0.3 mm to 4.72 cm, with 68% of bony fragments having significant subsidence. Type 5 callus diameter was statistically significant (P < 0.0001) in preventing callus subsidence compared to the other types. Type 4 callus density was statistically significant in preventing callus subsidence compared to the other types (P < 0.0001). The ROC curve with area under the curve 0.961 and sensitivity 0.933 showed that a callus scoring system score >7.5 was effective in preventing significant callus subsidence. When using score 8 as a result from the ROC curve, 73.3% of bony fragment subsidence was <10% with sensitivity 93.3 and specificity 83.2.

Conclusion

Callus diameter 81%–100% and callus density type 4 could prevent significant callus subsidence. Based on the results of the present study we suggest using callus score > 8 to determine the time of Ilizarov removal.

     

Tibial lengthening over an intramedullary nail

Background Long-term application of an external fixator to treat leg-length discrepancy and short stature often causes complications, such as pin-tract infection or loss of range of motion at the knee or ankle (or both). Prolonged fixator use also interferes with the activities of daily living. To minimize such problems, we have combined intramedullary nailing with external fixation. Using this technique, the external fixator can be removed more quickly after completing the lengthening. Methods We combined intramedullary nailing with lengthening in 13 tibias (8 patients) and then compared these cases with 17 standard tibial lengthenings (16 patients) using an external fixator alone. In both groups we excluded patients who had a history of previous bone infection, open fracture, immature bone, soft tissue compromise, antineoplastic chemotherapy, or bone deformity of a severity that required gradual deformity correction. We also excluded cases with lengthening of less than 3 cm. Results The mean external fixation index differed significantly between the two groups, but the consolidation index did not. Mean operating time for lengthening combined with intramedullary nail placement was approximately 60 min longer than for standard lengthening without nail placement; intraoperative blood loss was not greater in the nailing group. Complications related to the external fixator were far fewer in the combined intramedullary nailing and lengthening group compared with the control group, and callus formation was satisfactory for both groups. Conclusions A combination of intramedullary nailing and external fixation produces callus formation as good as that obtained by the standard Ilizarov method of lengthening. Furthermore, this combined procedure decreases the external fixation time and is associated with fewer complications.     

Role of early Ilizarov ring fixator in the definitive management of type II, IIIA and IIIB open tibial shaft fractures

We evaluated the results of patients with Gustilo types II, IIIA and IIIB open tibial fractures managed early with the Ilizarov external fixator (IEF). Sixty patients (51 males, nine females; age range 20–62 years; mean age 32.8 years) with type II (11 patients), type IIIA (13) and type IIIB (36) tibial diaphyseal fractures underwent emergency debridement and minimal bone fixation (with external fixator), followed by definite fixation with the IEF after three to five days. Average duration of the hospital stay was 8.6 days. All fractures united with an average union time of 21.1 weeks (standard deviation [SD] 3.18) in type II, 21.7 weeks (SD 3.57) in IIIA and 24. 9 weeks (SD 5.14) in IIIB fractures. The difference between union time in type II and IIIA was not significant (p > 0.05), but that between IIIA (and also type II) and IIIB was significant (p < 0.05). The healing index in patients who underwent lengthening was 1.5 months/cm. The wounds in 27 patients were managed by delayed primary closure, in 19 patients with second intent (all IIIB), in 11 patients with skin grafting (mostly type IIIB fractures) and in three patients with musculocutaneous flaps. The most common complications of the procedure were pin tract infection and pain at the fracture site. Most of the patients were able to achieve good knee and ankle range of motion. Early application of the Ilizarov fixator constitutes an excellent management of open tibial fractures, especially types II, IIIA and IIIB, due to good functional and radiological results. Despite the technical difficulties and some complications (which are mostly minor) IEF may be the preferred method in open tibial fractures, especially types II and III.     

Femoral lengthening over elastic stable intramedullary nailing in children using the monolateral external fixator

The authors report preliminary results of femoral lengthening performed with monolateral external fixation over elastic stable intramedullary nailing in children. Seven femoral lengthenings were performed in six patients, at a mean age at surgery of 6.6 years (range 1.5–12 years). All lengthenings were performed due to limb length discrepancy (congenital hypoplasia in four patients, growth arrest secondary to neonatal infective osteoarthritis in one, type II sacral agenesis in one). In six cases the elastic nails realised a bipolar ascending construct, in one case a descending construct. Cases were reviewed at a mean time from removal of external fixator of 34.2 months (range 15–75 months). The mean lengthening obtained was 4.8 cm (range 3.8–6.0 cm). Mean consolidation index was 42.9 days/cm. No case of axial deviation requiring surgery and no case of deep infection were recorded. No case of fracture of the regenerate occurred after removal of the external fixator. There were two premature consolidations requiring mobilisation under general anaesthesia, and a case of failure of consolidation requiring surgery. The technique reported provides indisputable biomechanical advantages, particularly increasing stability at the site of osteotomy. The characteristics of implants make this method ideal for lengthenings in children.     

Comparison of 39 post-traumatic tibia bone transports performed with and without the use of an intramedullary rod: the long-term outcomes

Bone transport can be performed with an external fixator alone or with the monorail technique which entails the combination of a fixator and an intramedullary nail. The purpose of this study was to compare the complication rates and long-term outcomes of these methods. Two groups of patients, the external fixator (n = 21) and the monorail group (n = 18), were compared. The average follow-up period was 7.9 ± 5.6 years and the mean defect length 8.3 ± 3.1 cm. Healing was achieved in 19 (90%) and 13 (72%) of the fixator and monorail patients, respectively. Six patients underwent amputations because of persistent infections (two in the fixator and four in the monorail group). The rate of deformities was significantly higher in the fixator group (p = 0.049). No statistically significant difference was found when comparing categories of the SF-36 test or the ability to work or do sports. The main advantages of the monorail method are reduction of the external fixation time and the lower rate of deformities. However, the authors recommend segmental transport with external fixator in patients with chronic infections.     

Postoperative Cox inhibitors and late prosthetic loosening—suspicion increases!

Background and purpose In clinical practice, achieved lengthening of a callotasis zone should be maintained after the external fixator has been removed. The common understanding has been that the regenerated bone may subside. To investigate this, we used high-resolution radiostereometric analysis (RSA) with accurate measurement of the lengthening zone.

Patients and methods We assessed the longitudinal subsidence of a callotasis zone after removal of the external fixator in distraction osteogenesis in 16 patients who underwent 17 segmental lengthening operations on the tibia (n = 9) or femur (n = 8). Median lengthening was 32 (6–80) mm. RSA was performed at the end of the consolidation period before the external fixation device was removed, and this was later repeated at a median time of 11 (4–32) weeks after frame removal.

Results A minimal median longitudinal change of 0.01 (–0.28 to 0.60) mm across the lengthening zone occurred in uncomplicated cases.

Interpretation Our results indicate that no subsidence of clinical interest occurs after external frame removal.     

Stimulation of Bone Formation by Recombinant Fibroblast Growth Factor-2 in Callotasis Bone Lengthening of Rabbits

Bone lengthening by callotasis is one of the most useful methods not only for the treatment of short extremities but also for extensive bone defects; however, the procedure takes a long time especially for the consolidation of the distracted callus. In this study, effects of a single local injection of recombinant human fibroblast growth factor-2 (FGF-2 or basic FGF) on callotasis bone lengthening were examined in rabbits. Ten days after the osteotomy at the middle of the tibia and the installment of an external fixator, the osteotomized site was distracted at a rate of 1.4 mm/day for 7 days, resulting in 9.8 mm lengthening. On the final day of distraction, 200 μg of FGF-2 in 150 μl of saline solution or vehicle alone was injected into the center of the distracted callus. Injection of FGF-2 increased bone formation at the distracted callus radiologically and histologically. A significant effect on bone mineral content (BMC) at the callus was observed as early as 2 weeks, and FGF-2 increased the BMC about twofold at 5 weeks after a normal remodeling process. We conclude that the callotasis method in combination with FGF-2 injection at the consolidation step could be clinically beneficial to shorten the bone lengthening period. Received: 6 May 1997 / Accepted: 1 November 1998     

Lower extremity lengthening by Wagner's method and by callus distraction

Fifty-three patients underwent 64 lengthenings of the femur or tibia by the Wagner technique or by the callus distraction method. Thirty-six femoral and 28 tibial segments were lengthened. Simultaneous lengthening of the femur and tibia was performed in seven limbs. Three segments underwent repeat lengthenings. The average length gained by the Wagner method was 5.1 cm in the femur and 5.4 cm in the tibia. Length gains by callus distraction were 4.9 cm in the femur and 4.5 cm in the tibia. Complication rates were fewer and less severe with callus distraction. The number of operations, days of hospitalization, and length of total treatment were less in patients operated on with the callus distraction method than in those who underwent the Wagner technique.     

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. Received: 2 June 1997     

Analysis of corticalization using the pixel value ratio for fixator removal in tibial lengthening

Background  

It is important to define callus maturation and corticalization during distraction osteogenesis. Quantitative methods such as ultrasound and Q-computed tomography are sensitive but expensive. The pixel value ratio (PVR) obtained using a PACS (picture archiving and communication system) is a simple and cost-effective investigation tool. Recently, the issue of whether the PVR is correlated with quantitative methods has been studied. We investigated whether serial PVR is a useful technique for predicting corticalization in each callus segment of the regenerate, and can act as a guide for fixator removal in tibial lengthening without intramedullary nailing.     

Monitoring of bone formation during distraction osteogenesis via osteocalcin: a time sequence study in dogs

 The aim of the current study was to analyze the osteocalcin level and radiographic density during distraction osteogenesis in order to investigate the role of osteocalcin in monitoring bone formation during callus distraction. Lengthening of the right tibia by 25% was performed in 12 beagle dogs by callus distraction after osteotomy and application of a ring fixator. Distraction was started on the 5th postoperative day, with a distraction rate of 0.5 mm twice a day, and was ended after 25 days. Blood samples and x-rays of the callus distraction segment were obtained preoperatively and once a week until day 55 after operation. A digital radiograph analysis system was used to determine the bone density of the callus distraction segments. The serum parameters of osteocalcin were evaluated by radioimmunoassay. The radiographic bone densities during the distraction phase increased during the distraction period and markedly increased during the consolidation period. A similar trend was observed for osteocalcin, whereby the coefficient of correlation between these two parameters was, on average, 0.68 ± 0.11. However, the radiographic bone density measurements, as well as the osteocalcin levels, showed large variation between different animals. Therefore, our results suggest that valuable information about bone formation during distraction osteogenesis can be obtained via serum osteocalcin levels, even though it seems that time sequence monitoring is more favorable than the determination of absolute values. Received: January 16, 2002 / Accepted: April 10, 2002     

A review of problems, obstacles and sequelae encountered during femoral lengthening : uniplanar versus circular external fixator

There is currently a consensus regarding the superiority of circular type external fixators over uniplanar fixators for lengthening of the tibia, but femoral lengthening is still subject to the surgeon's preference. This study compares the occurrence rates of significant problems, obstacles and sequelae between these two techniques. Fifty patients (29 male, 21 female), with a mean age of 20 years were assigned to a circular type fixator group (54 lengthening segments), whereas 60 patients (29 male, 31 female), with a mean age of 20 years were assigned to a uniplanar fixator group (67 lengthening segments). The incidence of knee stiffness was significantly higher in the circular external fixator group (031 per segment) compared to the uniplanar external fixator group (0.13 per segment) (p < 0.05). The incidence of pain during lengthening was higher in the circular external fixator group, and patient satisfaction was higher in the uniplanar external fixator group. We recommend the uniplanar external fixator as a preferable device for femoral lengthening.     

Deep intramedullary infection in tibial lengthening over an intramedullary nail

Tibial lengthening over an intramedullary (IM) device is associated with a risk of deep intramedullary infection; there is so far no guideline for decision making between early removal and delayed removal of the nail. Tibial lengthening over an intramedullary nail/Rush pin was performed in 118 limb segments (63 patients) from 2004 to 2008 in our institution. Fifty five patients had bilateral tibial lengthening. Ninety nine of the 118 segments went on to healing without infection, while 13 segments developed superficial infection and 6 segments developed deep infection. Among 6 patients with deep infection, 4 patients underwent early removal of the nail when deep infection signs and symptoms occurred and 2 patients underwent delayed removal of the nail at 11 months. The 6 segments with deep infection differed significantly with respect t to the callus pattern (p < 0.05) and density (p = 0.0001) from those without infection and with superficial infection. In this small sugroup, removal of the nail was delayed in two patients as there was visible callus bridging at more than one cortex, and deep infection subsided after local drainage.     

Inferior subluxation of the fibular head following tibial lengthening with a unilateral external fixator

BACKGROUND: Inferior subluxation of the proximal part of the fibula has been reported to occur with distraction osteogenesis of the tibia; however, the clinical sequelae of this subluxation are unknown. The purpose of this study was to evaluate inferior subluxation of the proximal part of the fibula and its possible clinical implications in patients who had undergone tibial lengthening by distraction osteogenesis with use of a unilateral external fixator. METHODS: Thirty tibiae in seventeen patients with a variety of conditions underwent tibial lengthening by distraction osteogenesis with use of a unilateral external fixator and were followed clinically and radiographically for a mean of two years and ten months (range, two to four years). Ten patients were female and seven were male. Their mean age at the time of the surgery was seventeen years (range, eight to twenty-five years). The mean tibial lengthening was 8.1 cm (range, 3.5 to 13 cm). RESULTS: An inferior shift of the fibular head in relation to the tibia was evident in all cases. The shift, which ranged from 0.4 to 3.3 cm, was proportionally related to the amount of tibial lengthening. This type of subluxation is probably attributable to the tension that is exerted by the intact interosseous membrane during the distraction as well as to the tension of the regenerated bone of the fibula and the fact that the fibula itself is not fixed or directly lengthened by the external fixator. CONCLUSIONS: It appears that inferior subluxation of the fibula is a common phenomenon in patients undergoing tibial lengthening by distraction osteogenesis with use of a unilateral external fixator. However, no clinical symptoms or findings related to the inferior subluxation of the fibula were found in our series.     

Bifocal tibial corrective osteotomy with lengthening in achondroplasia: an analysis of results and complications

The results and complications of bifocal tibial osteotomies with gradual correction and lengthening by Ilizarov ring fixator performed in 47 tibiae in 24 achondroplastic patients were analyzed. Comparison was made between the parameters of angular and torsional deformities of the tibia preoperatively, at fixator removal, and at last follow-up. Of these parameters, statistically significant change was seen postoperatively in the values of medial proximal tibial angle, lateral distal tibial angle, mechanical axis deviation, and tibial torsion, which changed from 78.8 +/- 7.05 degrees, 103.2 +/- 11.8 degrees, 25.1 +/- 14.6 mm (medial), and 22.7 +/- 10 degrees (internal) preoperatively to 87.3 +/- 6.3 degrees, 90.9 +/- 5.4 degrees, 5.3 +/- 10 cm (medial), and 15.8 +/- 4.2 degrees (external), respectively, at the time of fixator removal; and this correction was maintained during the follow-up period. Mean total tibial lengthening was 6.84 +/- 1.3 cm. Average healing index was 26.06 days/cm. Complications observed were 15 pin tract infections, 1 residual varus, 1 overcorrection into valgus, 2 recurrence of varus, 22 equinus contractures, 2 premature consolidations, and 3 fibula malalignments. Recurrence of varus was observed in limbs with a residual abnormal medial mechanical axis deviation due to femoral deformity. A hundred percent incidence of equinus was observed in limbs with tibial lengthening of more than 40%, with distal tibial lengthening of more than 15%. To minimize the risk for occurrence of equinus, we recommend restriction of distal tibial lengthening in achondroplasia to less than 15%, although total tibial lengthening may exceed 40%. Fibula malalignment was not observed after double fibula osteotomy. This procedure is safe and efficacious if performed with strict adherence to prescribed technique.     

Tibial lengthening over nails in children using modified Ender nails: preliminary results of a new treatment

Tibial lengthening over nails, using modified Ender nails, was performed in nine children whose mean age at surgery was 12.8 years. The prerequisite for using this technique was the absence of axial malalignment and an indication for tibial lengthening only. Lengthening was not performed in one case due to the development of a compartment syndrome after the tibial osteotomy. Breakage of one interlocking screw without loss of alignment or length was observed in one case. Superficial pin tract infections were observed in two cases. An average of 4.1 cm (range 3-4.5 cm) lengthening of the tibia was achieved in eight of the nine cases. The modified Ender nails used permitted locking at both ends after achieving the desired distraction and permitted early removal of the external fixator. The advantage of this technique is that it permits early removal of the fixator and thus decreases the incidence of fixator related problems and facilitates early rehabilitation.     

Association of Ilizarov’s technique and intramedullary rodding in the treatment of congenital pseudarthrosis of the tibia

Purpose  Many surgical techniques have been published on how to treat congenital pseudoarthrosis of the tibia (CPT). We combined Ilizarov’s fixator with intramedullary nailing of the tibia and developed a procedure which combines the advantages of both methods: Ilizarov’s high fusion rate with alignment control and the protection against refracture provided by the intramedullary nail. The results of this approach are presented and discussed. Material and methods  Seven boys and three girls aged 3–14 years (mean age 8 years 2 months) were treated using our combined technique. In six cases, the CPT was associated with neurofibromatosis. Two strategies were adopted: in six cases, a compression was applied on the bone defect, and in four cases, segmental bone transportation was performed before the compression procedure. The final follow-up (1.2–6.6 years) included a clinical and radiological examination. Results  Tibial union was achieved in nine cases without bone grafting. In one case, tibial union still remains uncertain, despite intertibiofibular bone grafting and additional compression procedures. Thirteen overall complications were noted, including three valgus deformity of the ankle. Bone transportation failed to achieve complete limb lengthening in three cases. One deep infection occurred 4 years after removal of the external fixator. The treatment for this included nail removal and antibiotic therapy for 3 months. Despite a permanent protection of orthosis, a refracture occurred 2 years after nail removal, reverting to the initial level of pseudarthrosis. Another surgical attempt using the same method was then performed with a satisfactory result. Conclusions  The association of Ilizarov’s technique and intramedullary nailing achieved and maintained tibial union in nine of ten patients at final follow-up. It also allowed correction of axial deformities and prevented refracture. Despite the short duration of the follow-up and a high rate of complications in our series, this method can be useful in many cases of CPT in which healing has failed to occur despite many previous surgeries.