Principles and results of corrective lower limb osteotomies for patients with vitamin D-resistant hypophosphatemic rickets

Forty-four lower limb osteotomies were performed in ten patients with vitamin D-resistant hypophosphatemic rickets. The average follow-up period was 51 months. Osteotomies were combined with shortening and compression plating. This allowed corrections of angular deformities in the sagittal plane as large as 70 degrees and in the coronal plane as large as 78 degrees. There was one complication, a compartment syndrome that resolved completely following prompt fasciotomy. Recurrence of deformity occurred in 27% of the cases. While osteotomies were safe and provided dramatic improvement to limb deformity, postoperative control of vitamin D metabolism was the one constant factor for maintenance of correction.     

Metabolic and orthopedic management of X-linked vitamin D-resistant hypophosphatemic rickets

Purpose  Therapy of vitamin D-resistant hypophosphatemic rickets (VDXLR) consists of oral phosphate and vitamin D supplements. Bone deformities, pain, and small stature can occur even in children with good compliance, requiring surgical correction and bone lengthening. However, only few surgical reports are available. Methods  Twelve patients (three males) with VDXLR were followed at our institution. Median age at diagnosis was 3 9/12 years (range, birth to 11 10/12) with a follow-up period of 7 8/12 years (1 9/12–30) and age at last follow-up of 13 6/12 years (2–30). Eight patients underwent surgical correction, three of them in combination with bone lengthening. The corrections were performed at the end of growth in three patients. Clinical endpoints were height, leg axis, and pain. Results  Single bilateral surgical correction was performed in six patients; one patient each had three and five corrections. Bone lengthening was performed in three patients. At last follow-up, the height of seven operated patients was within normal range. In addition, leg axis was normalized in six patients with mild genua vara in two. Only one patient complained of intermittent pain. Bone healing was excellent; surgical complications were rare. There was no radiological evidence of degenerative arthropathy. Conclusions  Medical treatment remains the main pillar of therapy in children with VDXLR. In case of bone deformity, surgery can safely be performed, independent of age or bone maturation. All patients were satisfied with the results of axial corrective surgery and bone lengthening, and in the majority only one corrective intervention was needed.     

Deformity correction by external fixation and/or intramedullary nailing in hypophosphatemic rickets

Background There are many modalities of treatment for complex lower extremity deformity in hypophosphatemic rickets. We evaluated the outcomes of deformity correction using an external fixation and/or intramedullary nailing in hypophosphatemic rickets

Patients and methods 55 segmental deformities (20 femora, 35 tibiae) from 20 patients were examined retrospectively. There were 9 children and 11 adults. Distraction osteogenesis was used in 28 segments and acute deformity correction in 27. External fixation was applied in 24 segments, intramedullary nailing in 6, and external fixation and intramedullary nailing in 25.

Results There were 18 major and 13 minor complications in 26 of 28 segments with distraction osteogenesis, and 13 major and 10 minor complications in 19 of 27 segments with acute correction. Recurrent deformity or refracture occurred in 10 of 21 segments with distraction osteogenesis by external fixation only, 4 of 6 with acute correction by intramedullary nailing, and 1 of 25 with distraction osteogenesis or acute correction by external fixation and intramedullary nailing. Nail-related complications occurred in 3 of 6 with intramedullary nailing and 2 of 25 with external fixation and intramedullary nailing.

Interpretation External fixation and intramedullary nailing can be recommended to prevent complications during or after deformity correction in hypophosphatemic rickets.     

Deformity correction by external fixation and/or intramedullary nailing in hypophosphatemic rickets

Background?There are many modalities of treatment for complex lower extremity deformity in hypophosphatemic rickets. We evaluated the outcomes of deformity correction using an external fixation and/or intramedullary nailing in hypophosphatemic rickets

Patients and methods?55 segmental deformities (20 femora, 35 tibiae) from 20 patients were examined retrospectively. There were 9 children and 11 adults. Distraction osteogenesis was used in 28 segments and acute deformity correction in 27. External fixation was applied in 24 segments, intramedullary nailing in 6, and external fixation and intramedullary nailing in 25.

Results?There were 18 major and 13 minor complications in 26 of 28 segments with distraction osteogenesis, and 13 major and 10 minor complications in 19 of 27 segments with acute correction. Recurrent deformity or refracture occurred in 10 of 21 segments with distraction osteogenesis by external fixation only, 4 of 6 with acute correction by intramedullary nailing, and 1 of 25 with distraction osteogenesis or acute correction by external fixation and intramedullary nailing. Nail-related complications occurred in 3 of 6 with intramedullary nailing and 2 of 25 with external fixation and intramedullary nailing.

Interpretation?External fixation and intramedullary nailing can be recommended to prevent complications during or after deformity correction in hypophosphatemic rickets.     

Adult-onset vitamin D-resistant hypophosphatemic osteomalacia. A possible variant of vitamin D-resistant rickets.

A family of 133 members showing unusual manifestations of vitamin D-resistant hypophosphatemic osteomalacia was studied. The hypophosphatemic children did not have rickets or clinical femoral bowing: the hypophosphatemic young adults had minimum clinically evident femoral bowing; and the older adults (age forty and older) were progressively disabled by severe bowing. The disorder appears to be an X-linked dominant, with almost complete penetrance of the hypophosphatemic trait. The etiology of this disorder could not be determined.     

Treatment of tibia vara by the Ilizarov method

Sixty-nine lower extremities of 45 patients (mean age, 10 years 8 months) with tibia vara were treated with the Ilizarov circular external fixator and distraction osteogenesis. Twenty-four of the patients had bilateral involvement, six of whom had simultaneous surgery and the remaining 18 had staged operations 8 to 12 months apart. In 11 limbs with femoral valgus deformity greater than 10 degrees simultaneous corrections were done. Active movements of the joints of the extremity were encouraged the day after surgery and partial weightbearing began 2 days later. All patients were followed up 27 to 178 months (mean, 80 months) after surgery. No neurovascular complications, delayed union, or nonunions were observed. The mean 28.6 degrees varus tibiofemoral angle preoperatively (range, 15 degrees -45 degrees ) improved to 7.5 degrees valgus (range, 0 degrees -18 degrees ) postoperatively. The preoperative internal torsion angle also improved from 20.7 degrees (range, 0 degrees -48 degrees ) to 3.5 degrees external torsion (range, 0 degrees -9 degrees ) postoperatively. Residual deformity was seen in six patients, and they had successful revision surgery using the same technique. The Ilizarov method allows early weightbearing and motion and allows all components of the deformity to be corrected.     

Genu Varum in Children: Diagnosis and Treatment

Genu varum is a relatively common finding in children. Physiologic bowing, which is seen most often, has a well-documented favorable natural history. Idiopathic tibia vara is the most common of the pathologic conditions that are associated with bowed legs; treatment strategies vary with the patient's age and the stage of disease and deformity. Genu varum may also accompany systemic conditions, such as achondroplasia, vitamin D-resistant rickets, renal osteodystrophy, and osteogenesis imperfecta-all of which can result in short stature. Indications for intervention are not always well defined. A rare disorder, focal fibrocartilaginous dysplasia, usually requires no treatment. Standing radiographs of the entire lower limbs are necessary for surgical planning, as the deformity can sometimes affect the distal femur rather than the proximal tibia. Restoration of the mechanical axis of the limb is the principal goal of treatment; the particular type of internal fixation is of secondary importance.     

X-linked rickets and tumor-acquired osteomalacia:PHEX and the missing link

Dietary rickets has been recognized as a major cause of skeletal abnormalities in the industrialized world for more than 350 years. In recent times, familial and tumor forms of rickets were found to be resistant to vitamin D₃ supplementation and light. The main nondietary types of rickets and osteomalacia include: a) X-linked vitamin D-resistant, hypophosphatemic rickets; b) hereditary hypercalciuria with hypophosphatemic rickets; c) Dent's disease including certain types of renal Fanconi syndrome; d) renal 1α-hydroxylase deficiency; e) defects in the 1,25-dihydroxy vitamin D₃ receptor (end-organ resistance); f) autosomal dominant forms of rickets; and g) oncogenic hypophosphatemic osteomalacia. This review will describe the recent advances in our knowledge of the molecular defects in hypophosphatemic rickets and tumor-acquired osteomalacia. This paper was presented at the 2nd International Forum “The Frontiers of Nephrology,” Tokyo, May 10, 1998.     

Correction of distal femoral deformity

This retrospective study reviews 12 distal femoral osteotomies in nine patients performed for angular and rotational deformities, using the Orthofix external fixator. All osteotomies progressed to solid union with reliable correction of the deformity. Few complications were encountered. Simultaneous lengthening was performed on one patient successfully. This method proved to be a safe and precise means of correcting distal femoral deformity with the option of simultaneous correction of length discrepancy.     

Humeral lengthening and deformity correction

Nine patients with achondroplasia and one patient with Apert syndrome underwent the surgical lengthening of both humerus and simultaneous correction of both associated bone deformity. An unilateral external fixator was applied to the lateral aspect of the humerus with four half-pins and percutaneous predrilling osteotomy was performed at the apex of flexion deformity of the bone. During the waiting period before distraction, the flexion deformity of the distal humerus was corrected using an additional external fixator. Slow gradual distraction was subsequently carried out at a rate of 0. 25 mm every 6 hours. The average lengthening was 8 cm (range 7.5 to 9 cm), the overall treatment time 312 days (range 192 to 406 days), and the average healing index 39.0 days/cm. The average correction of the elbow flexion deformity was 20 degrees. We believe this treatment is useful to improve the function of the arms and the activity of daily living for the patients with bilateral short humeri.     

Deformity correction of knee and leg lengthening by Ilizarov method in hypophosphatemic rickets: outcomes and significance of serum phosphate level

The authors evaluated 14 patients with hypophosphatemic rickets who underwent correction of a knee deformity along with a leg lengthening by the Ilizarov method. Deformity correction alone was performed in 8 femora and 4 tibiae-fibulae, and concomitant deformity correction and limb lengthening (>1.0 cm) in 9 femora and 19 tibiae-fibulae. The healing index correlated with the biochemical parameters. Knee deformities were satisfactorily corrected in all patients except one. There was a statistically significant negative correlation between the healing index and the serum phosphate level: those who had a serum phosphate level higher than 2.5 mg/dL showed a relatively rapid regenerate bone healing compared with those with less than 2.5 mg/dL. The authors conclude that a serum phosphate level of 2.5 mg/dL as a cut-off point should be considered in deciding whether deformity correction alone or with a concomitant leg lengthening should be undertaken.     

Treatment of rigid hypertrophic posttraumatic pseudarthrosis of the tibia in children using distraction osteogenesis

Posttraumatic tibial pseudarthrosis is a relatively uncommon complication of tibia fractures in children. Although reported as a successful method of treating tibial nonunions in adults, distraction osteogenesis through a nonunion site via ring external fixation has not been described in children. The authors report three consecutive cases of distraction through an angulated, shortened, hypertrophic, posttraumatic nonunion to achieve successful union and concurrent correction of deformity. Distraction was carried out using a ring fixator with computer-guided correction. Union was achieved in each of the three patients with complete correction of deformity and length. Lengthening of 8 to 31 mm was achieved. The length of time in the external fixator ranged from 7 to 27 weeks. Pin tract infections developed in all patients; they were treated successfully using oral antibiotics. No deep infections or other significant complications developed. Each patient was followed up for at least 1 year.     

Ossification of the posterior longitudinal ligament in vitamin D-resistant rickets: case report and review of the literature

STUDY DESIGN: A case report of cervical myelopathy caused by ossification of the posterior longitudinal ligament in a patient with vitamin D-resistant rickets is presented together with a review of literature. OBJECTIVE: To report the diagnosis of ossification of the posterior longitudinal ligament in a white woman with vitamin D-resistant rickets. SUMMARY OF BACKGROUND DATA: The association between ossification of the posterior longitudinal ligament and untreated vitamin D-resistant rickets has been reported in Japan, but infrequently in white populations. In whites, ossification of the posterior longitudinal ligament is closely associated with diffuse idiopathic skeletal hyperostosis. A clear association between ossification of the posterior longitudinal ligament and vitamin D-resistant rickets in white populations has not yet been established. METHODS: The medical record and imaging studies of a patient treated at the authors' institution for cervical myelopathy caused by ossification of the posterior longitudinal ligament in the setting of treated vitamin D-resistant rickets were reviewed. A Medline search of the medical literature between 1966-1999 was performed to identify pertinent studies and similar case reports. RESULTS: The occurrence of spinal stenosis in untreated adults with vitamin D-resistant rickets has been reported in all regions of the spine in Japanese patients. The association between ossification of the posterior longitudinal ligament and untreated vitamin D-resistant rickets was first reported in Japan, where ossification of the posterior longitudinal ligament is endemic. This association may be incidental, because reports on ossification of the posterior longitudinal ligament in whites are not as frequent as in Japanese, reflecting the higher prevalence of this condition in Japan. CONCLUSION: Ossification of the posterior longitudinal ligament and ossification of the posterior longitudinal ligament associated with deranged calcium or phosphate metabolism may be different pathologic entities sharing a common outcome. Adequate treatment of vitamin D-resistant rickets may not always prevent or reverse ossification of the posterior longitudinal ligament.     

Use of the Ilizarov method to correct lower limb deformities in children and adolescents

The introduction to the West in the early 1980s of the Ilizarov circular external fixator and method resulted in rapid advances in limb lengthening, deformity correction, and segmental long-bone defect reconstruction. The mechanical features of and biologic response to using distraction osteogenesis with the circular external fixator are the unique aspects of Ilizarov's contribution. The most common indications for children and adolescents are limb lengthening and angular deformity correction. Surgical application and postoperative management of the device require diligent attention to detail by both patient and surgeon. Also required of the surgeon is a thorough appreciation of the basic principles of the apparatus, mechanical axial realignment, potential complications, and biologic response to stretching.     

Combined technique for the correction of lower-limb deformities resulting from metabolic bone disease

We present the results of the surgical correction of lower-limb deformities caused by metabolic bone disease. Our series consisted of 17 patients with a diagnosis of hypophosphataemic rickets and two with renal osteodystrophy; their mean age was 25.6 years (14 to 57). In all, 43 lower-limb segments (27 femora and 16 tibiae) were osteotomised and the deformity corrected using a monolateral external fixator. The segment was then stabilised with locked intramedullary nailing. In addition, six femora in three patients were subsequently lengthened by distraction osteogenesis. The mean follow-up was 60 months (18 to 120). The frontal alignment parameters (the mechanical axis deviation, the lateral distal femoral angle and the medial proximal tibial angle) and the sagittal alignment parameters (the posterior distal femoral angle and the posterior proximal tibial angle) improved post-operatively. The external fixator was removed either at the end of surgery or at the end of the lengthening period, allowing for early mobilisation and weight-bearing. We encountered five problems and four obstacles in the programme of treatment. The use of intramedullary nails prevented recurrence of deformity and refracture.     

Taylor spatial frame-software-controlled fixator for deformity correction-the early Indian experience

Background:

Complex deformity correction and fracture treatment with the Ilizarov method needs extensive preoperative analysis and laborious postoperative fixator alterations, which are error-prone. We report our initial experience in treating the first 22 patients having fractures and complex deformities and shortening with software-controlled Taylor spatial frame (TSF) external fixator, for its ease of use and accuracy in achieving fracture reduction and complex deformity correction.

Settings and Design:

The struts of the TSF fixator have multiplane hinges at both ends and the six struts allow correction in all six axes. Hence the same struts act to correct either angulation or translation or rotation. With a single construct assembled during surgery all the desired axis corrections can be performed without a change of the montage as is needed with the Ilizarov fixator.

Materials and Methods:

Twenty-seven limb segments were operated with the TSF fixator. There were 23 tibiae, two femora, one knee joint and one ankle joint. Seven patients had comminuted fractures. Ten patients who had 13 deformed segments achieved full correction. Eight patients had lengthening in 10 tibiae. (Five of these also had simultaneous correction of deformities). One patient each had correction of knee and ankle deformities. Accurate reduction of fractures and correction of deformities and length could be achieved in all of our patients with minimum postoperative fixator alterations as compared to the Ilizarov system. The X-ray visualization of the osteotomy or lengthening site due to the six crossing struts and added bulk of the fixator rings which made positioning in bed and walking slightly more difficult as compared to the Ilizarov fixator.

Conclusions:

The TSF external fixator allows accurate fracture reduction and deformity correction without tedious analysis and postoperative frame alterations. The high cost of the fixator is a deterrent. The need for an internet connection and special X-rays to operate the fixator add to its complexity.     

Renal phosphate loss in hereditary and acquired disorders of bone mineralization

Three metabolic bone diseases display similar characteristics such as hypophosphatemia due to chronically elevated renal phosphate clearance, inappropriately low 1,25 (OH)₂ vitamin D serum levels, and variable bone disease (rickets and osteomalacia). X-linked dominant hypophosphatemic rickets (XLH), also called vitamin D-resistant rickets and autosomal dominant hypophosphatemic rickets (ADHR) represent two inherited diseases, whereas oncogenic hypophosphatemia (OHO), also known as tumor induced osteomalacia (TIO), is an acquired paraneoplastic syndrome that, in certain aspects, has much in common with XLH and ADHR. Although the primary causes for these disorders are distinct and well established, their similar features suggest a unifying pathophysiological basis.

This review summarizes what is known about the mechanisms that underlie these diseases and includes most up-to-date information about recently introduced factors that might be involved in the regulation of phosphate homeostasis and skeletal mineralization.     

Accuracy of complex lower-limb deformity correction with external fixation: a comparison of the Taylor Spatial Frame with the Ilizarov ring fixator

Purpose Circular external fixators have several advantages over other surgical options in the treatment of limb length discrepancy and axial deformity. The innovative Taylor Spatial Frame (TSF) combines a rigid hexapod fixation system with the support of a web-based software program, and thus offers the possibility of simultaneous corrections of multidirectional deformities. Whilst there is still some scepticism of many Ilizarov device users about the advantages of the TSF, the purpose of the study was to perform a comparison between the TSF and the Ilizarov ring fixator (IRF) with regard to the accuracy of deformity correction in the lower limb. Methods Two hundred and eight consecutive deformity corrections in 155 patients were retrospectively evaluated. There were 79 cases treated with the IRF and 129 cases treated with the TSF. The mean age of the patients at the time of surgery was 13.2 years (range; 2–49 years). Standing anteroposterior and lateral radiographs were evaluated preoperatively and immediately after removal of the frames. The final result was compared to the preoperatively defined aim of the deformity correction. According to the treated count of dimensions, we differentiated four types of deformity corrections. The results were graded into four groups based on the persisting axial deviation after removal of the frame. Results The aim of the deformity correction was achieved in a total of 90.7% in the TSF group, compared to 55.7% in the IRF group. On the basis of the count of dimensions, the TSF achieved obviously higher percentages of excellent results (one dimension: TSF 100%; IRF 79.3%; two dimensions: TSF 91.8%; IRF 48.6%; three dimensions: TSF 91.1%; IRF 28.6%; four dimensions: TSF 66.7%; IRF 0%). In addition, the degree of the persisting deformity increased with the number of planes of the deformity correction. Conclusions The TSF allowed for much higher precision in deformity correction compared to the IRF. In two-, three- and four-dimensional deformity corrections in particular, the TSF showed clear advantages. This may derive from the TSF-specific combination of a hexapod fixator with the support of an Internet-based software program, enabling precise simultaneous multiplanar deformity corrections.     

The effect of treatment on growth and deformity in hypophosphatemic vitamin D-resistant rickets

Vitamin D-resistant rickets is characterized by short stature, lower extremity deformities, and defective mineralization of bone. While basic biochemical defects vary among involved individuals, all patients show a failure of the proximal tubule of the kidney to resorb inorganic phosphate. Laboratory findings consist of low serum phosphorus, elevated alkaline phosphatase, and abnormal serum calcium. Previously recommended treatment programs of high doses of vitamin D have effected some roentgenographic improvement in the rachitic lesions, but no related increase in height or severity of deformities has been associated with significant complications resulting from vitamin D toxicity. Daily administration of low doses of vitamin D and oral phosphates has more recently been suggested to be beneficial in promoting growth and preventing deformities. Thirteen children with documented vitamin D-resistant rickets were treated with oral phosphate and low doses of vitamin D for a mean of five years, and followed for a mean of ten years. Partial roentgenographic resolution of rachitic lesions was similar to those who received vitamin D alone. While the majority had consistently lowered alkaline phosphatases, no patient had consistently normal phosphate levels. No patient exceeded the third percentile in height. One half required osteotomies of the lower extremities. All osteotomies (eight) performed before maturity required revision, whereas those done after maturity (12) did not. Since no apparent clinical roentgenographic benefit can be documented by the addition of oral phosphate to low doses of vitamin D, we would not recommend continually doing so at this time.     

Management of fibular hemimelia using the Ilizarov method

A comprehensive program for the correction of fibular hemimelia and associated deformities using the Ilizarov external fixator has been developed at the author's institution. This management involves classification of the deformity (type I, II, or III) and single or staged procedures with the goal to provide a stable plantigrade foot with correction of leg deformity and length discrepancy. The use of the Ilizarov external fixator allows correction of multiple deformities simultaneously. The initial experience with this correction with satisfactory functional and radiographic results in most patients. Final conclusions regarding treatment outcome will not be possible until a significant number of patients reach skeletal maturity.