Callus formation in the humerus compared with the femur and tibia during limb lengthening

We investigated whether the callus formation in the humerus during the distraction period of limb lengthening proceeds at a higher rate than that in the femur and tibia. Ten achondroplastic patients underwent 3 bilateral humerus, 3 bilateral femur and 4 bilateral tibia lengthenings. To reduce the confounding effect of bone size, we used bone mineral apparent density (BMAD) to compare the three groups; this is a volumetric bone mineral density measurement. BMAD in the distracted callus space was evaluated at 8 weeks after the start of distraction using dual-energy X-ray absorptiometry (mean ± SD; g/cm³): in the humerus (0.24 ± 0.08) it was significantly higher than in the tibia (0.10 ± 0.02), while there was no difference between the humerus and femur (0.35 ± 0.11). We conclude that the callus formation in the humerus during the distraction period of limb lengthening proceeded at a significantly faster rate than in the tibia, but there was no significant difference between the humerus and femur. Received: 4 March 1997     

Lower limb lengthening by a modified Wagner technique

A series of 50 patients who underwent femoral and tibial lengthenings using the Wagner apparatus is reviewed. Satisfactory gains in leg length with an acceptably low complication rate were achieved. Both substitution of cortical osteotomy for complete osteotomy and delaying of distraction increased callus formation. The particular problems of lengthening the congenital short femur and tibia are discussed.     

Pulsed electromagnetic stimulation of regenerate bone in lengthening procedures

Distraction osteogenesis for limb lengthening represents the treatment of choice in patients with small stature or limb length discrepancies. Bone lengthening and callus formation requires a long therapy. Pulsed electromagnetic fields (PEMF) are normally used to enhance osteogenesis in patients with non-unions. In this study we investigated whether pulsed electromagnetic fields could be used effectively to encourage callus formation and maturation during limb lengthening procedures. Thirty patients underwent bilateral bone lengthening of the humerus, femur or tibia. At day 10 after surgery, PEMF stimulation was started on one side, for 8 hours/day. Stimulated distraction sites exhibited earlier callus formation and progression, and a higher callus density compared to non-stimulated sites. External fixation could be removed on average one month earlier in PEMF stimulated bones. Our results show that the use of pulsed electromagnetic fields stimulation during limb lengthening allows shortening the time of use of the external fixation.     

Operative Versorgung von pathologischen Humerus- und Femurfrakturen

The life expectancy of patients with malignant tumours and the incidence of osseous metastases have increased over the last decades. Operations for skeletal metastases of the extremities represent the most frequent surgery in orthopaedic oncology. The purpose of this study was to evaluate and compare the different operative treatment options for patients with pathologic fractures of the humerus and femur in terms of complications, postoperative recovery, and survival. From 2000 to 2005, 109 patients were surgically treated for pathologic fractures of the humerus (n=19) or femur (n=90). The study group consisted of 60 women and 43 men, with a mean age of 67 years (13–88). Breast carcinoma (36%) was the most common primary tumour, followed by kidney (17%) and bronchial (16%) carcinoma. Of all patients, 75 (73%) had numerous skeletal metastases, and 38 (37%) had visceral metastases. Wide or marginal resection was performed in seven fractures of the humerus and 14 fractures of the femur; intralesional resection was done in seven humeral and 73 femoral fractures; and stabilisation alone was done in five fractures of the humerus and three fractures of the femur. The median survival time for all patients was 6 months (0–102). The survival rate at 1 year was 25% (25% for both humeral and femoral fractures), 15% at 2 years (17% for humeral and 15% for femoral fractures), and 8% at 3 years (16% for humeral and 7% for femoral fractures). The overall complication rate was 11%, and revision surgeries were performed in seven patients (6.4%). The majority of patients (n=65; 60%), especially those with fractures close to the articular joint, were successfully treated with endoprosthetic replacement. Patients with fractures stabilised by intramedullary nails had shorter operating times, a shorter hospital stay, and fewer complications than patients treated with plating systems. Therefore, we recommend intralesional resection of the metastasis and stabilisation with intramedullary devices, supported by bone cement, as the treatment of choice for pathologic fractures of the diaphysis and metaphysis of the humerus and femur. Wide resection should be reserved for selected cases, such as solitary bone metastasis of kidney carcinoma.     

Callus formation in femur and tibia during leg lengthening:7 patients examined with DXA

We examined the callus formation during leg lengthening in 7 achondroplastic patients who underwent 3 bilateral femoral and 4 bilateral tibial lengthenings. Bone mineral content and bone mineral density (BMD) in the lengthened callus space were evaluated every 1 or 2 weeks for 10 weeks after the start of distraction using dual energy X-ray absorptiometry.

The mean rate of callus mineralization in femurs (0.64 g/wk) was higher than in tibias (0.22 g/wk). The mean BMD at 10 weeks after the start was 0.35 g/ cm² in the femur and 0.14 g/cm² in the tibia. Different rates of callus formation in different kinds of long tubular bones have not been reported previously.     

Limb lengthening with a fully implantable mechanical distraction intramedullary nail

AIM: The morbidity of fixator-assisted distraction osteogenesis should be reduced by intramedullary lengthening devices. The ISKD (intramedullary skeletal kinetic distractor) is a new, fully implantable mechanical lengthening nail. In a prospective cohort trial the possibilities and limitations of the device used on femur and tibia are examined. METHODS: 22 patients with a mean age of 25 (range: 16-46) years were treated with an ISKD for femoral (n = 16) and tibial (n = 6) lengthening. The average leg length discrepancy was 48 (range: 25-80) mm. The follow-up was 21 (range: 7-37) months. Clinical and radiological results and complications were evaluated. RESULTS: The results of femoral and tibial applications of the ISKD are different. At the tibia, in three patients a pseudarthrosis occurred and slow callus formation was observed twice. An equinus contracture became evident in 2 patients. At the femur, in one case the lengthening was not accomplished with the device. Five patients were manipulated under anaesthesia at least once to achieve the aim of distraction. Three of these patients received retrograde implantation of the ISKD. An infection or interlocking screw failure was not observed either at the femur or the tibia. CONCLUSION: The ISKD reduces fixator-associated problems but incorporates its own difficulties which are mainly based on the guidance of the device. Careful patient advice in monitoring the lengthening process is mandatory. At the femur 8 cm of lengthening can be achieved but the nail tends to "block". Proper reaming and osteotomy techniques are important. A lengthening of more than 1 mm/day is recommended to prevent early consolidation. At the tibia weak callus formation and soft tissue contractures occur, therefore not more than 4 cm lengthening should be planned, the distraction speed has to be reduced noticeable below 1 mm/day and the initial immobilisation should be for more than a week.     

Osteoporosis of the proximal humerus: Comparison of bone-mineral density and mechanical strength with the proximal femur

The hypothesis that the proximal humerus is more osteoporotic than the proximal femur has been examined by the indention test and bone-mineral density measurement on dissected proximal humeri and femora. The bone section at the base of the humeral head had about 65% of the bone-mineral density of the base of the femoral head. The energy required for 50% strain in the indention test on the humeral bone section was about 50% of that on the femoral head. The fact that the cancellous bone in the humeral head is more osteoporotic than in the femur may complicate surgical treatment of displaced humeral neck fractures.     

Treatment of complex limb deformities in children with the Ilizarov technique

Twenty-nine children underwent 36 Ilizarov procedures for a variety of limb deformities. We present the results in 11 patients, six with leg length discrepancies and five with achondroplasia, who underwent lengthening procedures using the Ilizarov method. Lengthening was accomplished in 15 of the 16 procedures (93%). Average increase in femur length was 10 cm (32%), in tibial length 7.5 cm (30%), in humerus length 11 cm (40%). Eleven complications occurred. The most common were pin tract infections (4), joint contractures (2), transient nerve injury (4), premature consolidation (5), and three fractures of the regenerated bone. The complication rate was as high as in other methods, but with the Ilizarov apparatus longer segments of bone were lengthened and more complex deformities were treated. The number of complications were lessened as experience was gained.     

Operative lengthening of the humerus: indications, benefits, and complications

The purpose of this study was to determine the benefits and risks of humeral lengthening procedures. Distraction osteogenesis was performed in 19 humeri on 16 patients (9 males, 7 females). The mean age at the time of lengthening was 11.5 years (range 3-24 years) and average follow-up was 8.7 years (range 2-21 years). Etiologies for short humeri included infection in six patients, congenital anomaly in six patients, unicameral bone cysts involving the physis in five patients, and posttraumatic growth disturbance in two patients. The average lengthening was 5 cm. The benefits from humeral lengthening include increased performance in daily activities, improved sports performance, and significantly better self-image. Complications included temporary radial nerve palsy in three cases, drainage from the pin tracts in two cases, elbow flexion contracture in three cases, and late humerus fracture in two cases. All the complications resolved over time and did not affect the outcome. Eleven lengthening procedures were not associated with any complications. Although the humerus is surrounded by complex neurovascular structures and muscles, humerus lengthening provided satisfactory results with temporary minor complications.     

Growth disturbance after lengthening of the lower limb and quantitative assessment of physeal closure in skeletally immature patients with achondroplasia

This study evaluated the effect of limb lengthening on longitudinal growth in patients with achondroplasia. Growth of the lower extremity was assessed retrospectively by serial radiographs in 35 skeletally immature patients with achondroplasia who underwent bilateral limb lengthening (Group 1), and in 12 skeletally immature patients with achondroplasia who did not (Group 2). In Group 1, 23 patients underwent only tibial lengthening (Group 1a) and 12 patients underwent tibial and femoral lengthening sequentially (Group 1b). The mean lengthening in the tibia was 9.2 cm (59.5%) in Group 1a, and 9.0 cm (58.2%) in the tibia and 10.2 cm (54.3%) in the femur in Group 1b. The mean follow-up was 9.3 years (8.6 to 10.3). The final mean total length of lower extremity in Group 1a was 526.6 mm (501.3?to 552.9) at the time of skeletal maturity and 610.1 mm (577.6 to 638.6) in Group 1b, compared with 457.0 mm (411.7 to 502.3) in Group 2. However, the mean actual length, representing the length solely grown from the physis without the length of distraction, showed that there was a significant disturbance of growth after limb lengthening. In Group 1a, a mean decrease of 22.4 mm (21.3 to 23.1) (4.9%) was observed in the actual limb length when compared with Group 2, and a greater mean decrease of 38.9 mm (37.2 to 40.8) (8.5%) was observed in Group 1b when compared with Group 2 at skeletal maturity. In Group 1, the mean actual limb length was 16.5 mm (15.8 to 17.2) (3.6%) shorter in Group 1b when compared with Group 1a at the time of skeletal maturity. Premature physeal closure was seen mostly in the proximal tibia and the distal femur with relative preservation of proximal femur and distal tibia. We suggest that significant disturbance of growth can occur after extensive limb lengthening in patients with achondroplasia, and therefore, this should be included in pre-operative counselling of these patients and their parents.     

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.     

Factors leading to hip subluxation and dislocation in femoral lengthening of unilateral congenital short femur

Congenital short femur is a rare and complex deformity. For it to be treated in the most accurate way, we must know of every possible complication. The purpose of this study was to determine the factors leading to hip subluxation or dislocation in patients with an unilateral congenital short femur who underwent a femoral lengthening procedure. Forty-four patients with congenital unilateral short femora types I, II, and IIIA were seen between 1981 and 1993 at Alfred I. duPont Hospital for Children. Seventeen patients had type I, 9 patients had type II, and 18 patients had type IIIA. Twenty patients underwent simultaneous lengthening of the femur and tibia, and 24 patients had primary lengthening of the femur. Eleven patients had an epiphysiodesis of the contralateral femur for residual leg length discrepancies of <6 cm. We observed that in patients with type IIIA, the acetabular dysplasia is severe, as well as the coxa vara deformity, and is associated with progressive subluxation and dislocation of the hip with lengthening. We believe that the combined abnormality of coxa vara and bow of the femoral shaft contributes to hip subluxation and dislocation in congenital short femur in association with an acetabular dysplasia prior to the lengthening. We recommend correction of the varus bow of the femur and the neck-shaft angle to 120 degrees and the acetabular index to <25 degrees prior to lengthening of type IIIA femora.     

Serial bone mineral density ratio measurement for fixator removal in tibia distraction osteogenesis and need of a supportive method using the pixel value ratio

Distraction osteogenesis is one of the common procedures for limb lengthening. However, attempts are being made constantly to establish objective guidelines for early and safe removal of a fixator using a sensitive and quantitative measurement technique. Dual-energy X-ray absorptiometry (DEXA) has been evaluated in the past for understanding callus stiffness, and the present study is a step further in this direction. The purpose of this study was to evaluate the correlation between bone mineral density ratio (BMDR) obtained by a DEXA scan and the pixel value ratio (PVR) on plain digital radiographs at each cortex and various callus pathways and callus shapes as described by Ru-Li's classification. A retrospective analysis of 40 tibial segments in 23 patients operated upon for various indications for limb lengthening was carried out. There were 11 male and 12 female patients with a mean age of 18 years. The Ilizarov method was applied after monofocal osteotomy, and distraction and consolidation were monitored using digital radiographs and DEXA scanning. BMDR was positively correlated with PVR, and the optimal BMDR for removal of the fixator was found to be 0.511. PVR of all cortices, except the anterior cortex, showed significant positive correlation with BMDR of the regenerate. There was good correlation between BMDR and PVR in the homogenous or heterogenous pathway according to callus shape and pathway. Thus, this study shows that BMD measurement can provide an objective and noninvasive method for assessing the rate of new bone formation during tibial distraction osteogenesis. It can thus function as an effective adjunct to measure callus stiffness, along with PVR, using digital radiographs, especially in cases in which callus maturation and stiffness is doubtful. Further studies especially dealing with callus progression through the lucent pathway as well as those dealing with regenerate fractures may be needed to conclusively prove the efficacy of this method for measurement of callus maturation.     

Callus patterns in femoral lengthening over an intramedullary nail

Our objectives were to evaluate callus patterns seen in femoral lengthening over an intramedullary nail by Li classification regarding shape and type and to predict the result while using the nail to reduce the external fixation period and its complications. Eight hundred digital radiographs of 15 patients with 15 segments of femur shortening who underwent femoral lengthening with a monolateral external fixator over an intramedullary nail were analyzed retrospectively by four observers. Each radiograph was studied for callus shape, feature type, and callus density using pixel values. The classification was tested for concurrence and reproducibility by interobserver studies and callus patterns were compared with treatment indices to evaluate how they correlated with the outcome. Mean length gained was 4.5 cm (range: 2–8 cm). External fixator index (EFI) was 21.68 days/cm. Average distraction consolidation index (DCI) was 48.49 days/cm. Fusiform callus was seen in three cases, cylindrical in seven, and lateral in five. The homogenous pathway had higher DCI (43.7) than the heterogeneous pathway (32.9), and mixed pathways making up the rest had a DCI of 50.1. Pixel value of callus showed gradual increase in density until 20–24 weeks, then density gradually fell for 8 weeks, again increased after 32 weeks, again gradually fell, and was comparable to adjacent normal bone by 44–48 weeks. Our results suggest that the Li classification can be satisfactorily applied to lengthening procedures over intramedullary nails. The radiologic pattern and pixel value of regenerate can be correlated with the clinical outcome and can be an aid of prognostic value for the surgeon. © 2011 Orthopaedic Research Society Published by Wiley Periodicals, Inc. J Orthop Res 29: 1106–1113, 2011     

微创PHILOS钢板内固定在儿童股骨粗隆下骨折中的应用

目的总结应用微创肱骨近端锁定钢板内固定与非手术治疗儿童股骨粗隆下骨折的结果和并发症。方法 2005年2月至2011年2月,我院采用肱骨近端锁定钢板和非手术治疗儿童股骨粗隆下骨折共24例患者,回顾性比较15例采用肱骨近端锁定钢板和9例采用非手术治疗的患者,从住院时间、完全负重时间和影像愈合时间以及结果评分和术后并发症等方面对两种治疗方法进行比较分析。结果 24例患者均获得随访,平均随访时间31.5个月,两组患者住院时间、完全负重时间和影像学愈合时间比较,差异有统计学意义(P0.05)。肱骨近端锁定钢板组结果评分更高(P0.05)。和非手术组相比,肱骨近端锁定钢板组总并发症发生率较低(P0.05)。结论对于儿童股骨粗隆下骨折,肱骨近端锁定钢板内固定系统与非手术组相比评分更高,总并发症率更低,是治疗儿童股骨粗隆下骨折的良好内固定之一。     

Comparative study of callus progression in limb lengthening with or without intramedullary nail with reference to the pixel value ratio and the Ru Li��s classification

Introduction

Callus progression is a great concern during limb lengthening. In this study, we investigated the difference in callus progression between tibial lengthenings with and without intramedullary nail.

Method

Seventy tibiae in 38 patients with an average age of 24?years were lengthened with Ilizarov external fixator and nail; 56 tibiae in 40 patients with an average age of 28.6?years were lengthened with the same Ilizarov external fixator but without nail. The callus progression was compared with reference to pixel value ratio (PVR) and Ru Li??s classification. Statistical analysis was performed to compare the variation trend of PVR and incidence of various callus pathways (particular patterns of callus progression as outlined in Ru Li??s classification) and shapes of each aspect of callus between the two groups.

Results

The trend of PVR was not statistically different in posterior, lateral and medial aspects of the callus between the two groups, but averagely lower in the anterior aspect in the group without nail than that with nail. The group without nail presented less incidence of homogeneous pathway, greater incidence of heterogeneous pathway; also greater incidence of fusiform callus, less incidence of cylindrical callus.

Conclusion

It was concluded that with nail, the callus underwent a more favorable progression and even longer lengthening could be allowed.     

Humeral lengthening in hypoplasia of the upper limb

Surgical treatment for the correction of upper limb discrepancies with primary involvement of the humerus is reported. The operative technique, the lengthening procedure with the G3-IOR distractor, and the successive external fixation are described. In the seven extremities treated, the mean lengthening was 5.0 cm, the mean percentage lengthening was 25.2%, and the mean residual discrepancy was 2.9 cm. The authors believe that humeral lengthening is advisable for 13- to 15-year-old patients with hypoplasia of the humerus when the discrepancy is greater than 3 cm.     

Comparison of the complication rates between first and second (repeated) lengthening in the same limb segment

The purpose of this study is to compare the incidence and types of complications in children who are undergoing first and second (repeated) lengthenings of the same bone. This is a retrospective review of 11 children (12 limbs) who underwent limb lengthenings of the same bone twice. There were 7 femoral and 5 tibial repeated lengthenings. Diagnoses included congenital femoral deficiency or proximal femoral focal deficiency in 6 patients, fibular hemimelia in 2, achondroplasia in 2, and tibial hypoplasia in 1. Mean age was 8.5 years for the first lengthening and 11.5 years for the second lengthening. There were 2.2 complications per lengthening for the first procedure and 1.5 for the second lengthening. There were 5 major and 22 minor complications for the first lengthening and 1 major and 17 minor complications for the second lengthening, none of these data were found to be statistically different. The healing index was 1.3 +/- 0.43 months per cm first lengthening and 2.2 +/- 1.7 cm for the second lengthening. This study did not demonstrate a significantly higher rate of complications with repeated lengthening of the same limb, although the time in the fixator for the second lengthening was longer and the degree of lengthening less.     

Histomorphometric, physical, and mechanical effects of spaceflight and insulin-like growth factor-I on rat long bones

Previous experiments have shown that skeletal unloading resulting from exposure to microgravity induces osteopenia in rats. In maturing rats, this is primarily a function of reduced formation, rather than increased resorption. Insulin-like growth factor-I (IGF-I) stimulates bone formation by increasing collagen synthesis by osteoblasts. The ability of IGF-I to prevent osteopenia otherwise caused by spaceflight was investigated in 12 rats flown for 10 days aboard the Space Shuttle, STS-77. The effect IGF-I had on cortical bone metabolism was generally anabolic. For example, humerus periosteal bone formation increased a significant 37.6% for the spaceflight animals treated with IGF-I, whereas the ground controls increased 24.7%. This increase in humeral bone formation at the periosteum is a result of an increased percent mineralizing perimeter (%Min.Pm), rather than mineral apposition rate (MAR), for both spaceflight and ground control rats. However, IGF-I did inhibit humerus endocortical bone formation in both the spaceflight and ground control rats (38.1% and 39.2%, respectively) by limiting MAR. This effect was verified in a separate ground-based study. Similar histomorphometric results for spaceflight and ground control rats suggest that IGF-I effects occur during normal weight bearing and during spaceflight. Microhardness measurements of the newly formed bone indicate that the quality of the bone formed during IGF-I treatment or spaceflight was not adversely altered. Spaceflight did not consistently change the structural (force-deflection) properties of the femur or humerus when tested in three-point bending. IGF-I significantly increased femoral maximum and fracture strength.     

骨痂延长术治疗肱骨大段骨缺损性骨不连

目的应用骨痂延长术治疗肱骨大段骨缺损性骨不连并对其临床疗效进行评价。方法20例肱骨大段骨缺损性骨不连均采用骨痂延长术进行治疗。结果术后随访1～2年,20例患者骨不连全部治愈,2例伴有桡神经损伤症状者术后恢复。结论骨痂延长术是治疗肱骨大段骨缺损性骨不连较好方法。