[Quality of life after surgical treatment of osteitis]. / Lebensqualität nach operativer Osteitisbehandlung.

Although many studies have measured the functional outcome after surgical treatment of osteomyelitis, there have been few published attempts to evaluate the long-term quality of life. We therefore undertook this study to assess the quality of life in a large patient population after operative treatment for this condition. All patients who underwent operative treatment for osteomyelitis from 1993 until 1997 at our institution were included in the study. The patients were assessed with a questionnaire which contained the SF-36 (German version) and questions about the activity and history of the illness. The result was compared to the data set from a standard population. Of the 502 patients, 345 (69%) returned questionnaires for evaluation. The infection was inactive in 301 (88%). Compared to a standard population, the investigated patients showed a significant reduction in their overall psychological well being and physical functional capacities. Surgical treatment was able to inactivate the infection in 88% of the patients. Because of persistent deficits, the psychological well being and physical functional capacities are reduced compared to a standard population.

Relevance of primary reduction for the clinical outcome of femoral neck fractures treated with cancellous screws.

INTRODUCTION: Femoral head-preserving treatment for femoral neck fractures with cancellous screws is a method widely performed, but its success depends on the quality of primary reduction. The goal of our study was to evaluate the relevance of reduction quality on the clinical outcome. PATIENTS AND METHODS: We retrospectively analyzed the postoperative reduction result of 39 patients. The angular rotation and the inferior displacement of the proximal fracture fragment were digitally assessed from AP radiographs. The clinical outcome was recorded by a follow-up after a mean 5.5 years. RESULTS: Unsuccessful healing was observed in eight patients, femoral head necrosis in three patients, non-union in two patients, implant loosening in one patient, and posttraumatic arthritis in two patients, all resulting in the need for a total hip replacement. This clinical course was strongly associated with a primary reduction in varus position, whereas reduction in anatomic or valgus angulation had no negative effect on the clinical outcome. An inferior offset was no negative predictor for successful healing. CONCLUSION: We conclude that a non-anatomic reduction in varus angulation significantly increases the risk of healing failure and therefore should be avoided. Reduction in valgus position should be performed if secondary redislocation is imminent.

[Osteotomies in malalignments of the lower extremities]. / Korrekturen bei Asymmetrien der unteren Extremität.

The surgical correction of malalignments of the lower extremities is a very demanding procedure. It requires extensive knowledge of: (1) fundamental lower extremity biomechanics, (2) various diagnostic modalities, and (3) methodology for multidimensional preoperative planning. Despite advanced techniques in diagnostics and surgery, the history of the patient and a physical examination are still the first steps in the diagnostic chain. The knowledge of the method-dependent normal values, their physiological range and intra-individual differences are a prerequisite. In posttraumatic deformities, the healthy leg is a good reference for the patient's geometric orientation. As a rule, values differing by three times the standard deviation or more are good indications for an operation. These are 15 and 12 mm for the upper and lower leg, 18 and 15 mm for the whole leg and only 3 degrees mm for the mechanical leg axis measured using computer tomography and long standing x-rays, respectively. The indication for surgical correction is not only based on geometric data. The patient's functional needs, symptoms, complaints and compensation possibilities must also be taken into account. The lower extremities have to be assessed in a psychosocial context. Among the huge number of possible surgical techniques, the procedure best suited for the patient has to be selected. This requires extensive knowledge and advanced technical skills from the treating orthopaedic surgeon. In supracondylar or high tibial osteotomies for the treatment of medial arthritis of the knee joint, the patient should be informed of the long term prognosis and endoprosthetic alternatives. Today, percutaneous epiphysiodesis is a very reliable and minimally invasive surgical technique for correcting the length and axis of the lower extremity in children between 10 and 14 years. With well planned epiphysiodesis procedures, it is often possible to avoid complex osteotomies in younger patients.

Radiographic results of callus distraction aided by pulsed low-intensity ultrasound.

OBJECTIVES: To determine whether pulsed low-intensity ultrasound (frequency of 1.5 megahertz, pulsed by one kilohertz, signal burst width of 200 microseconds, intensity of thirty milliwatts per square centimeter, and daily treatment time of twenty minutes per day) stimulates regenerate maturation after callus distraction. DESIGN: Prospective, controlled animal trial. METHODS: Operatively, we created a fifteen-millimeter defect in the right metatarsus of eighteen female mature merino sheep. A segmental transport was begun on Day 5 using a high-stiffness experimental ring fixator. The distraction rate was one millimeter per day divided into two increments of 0.5 millimeters each. On Day 21 after the operation, distraction was finished and the maturation period started and lasted until Day 84 after operation. During this period, Group 1 was treated with a daily twenty-minute low-intensity ultrasound stimulation (frequency of 1.5 megahertz, pulsed by one kilohertz, signal burst width of 200 microseconds, intensity of thirty milliwatts per square centimeter). Group 2 had no stimulation. Animals bore full weight. Plain radiographs in the anteroposterior view were taken every two weeks during the maturation period. After the animals were killed on Day 84, anteroposterior and lateral high resolution radiographs and computed tomography (CT) scans of the regenerate were performed. For each plain and high resolution radiograph, two different relationships (callus relation, the ratio of the amount of periosteal callus to the size of the space between the proximal fragment and transported segment; and interzone relation, the ratio of the fibrous callus interzone to the size of the new formed callus) were calculated. Using CT scan, callus area, bone density, and bone mineral content were evaluated. RESULTS: The results of interzone relation (both views) and callus relation (lateral view) in high-resolution radiographs and bone mineral content in CT indicate a significantly accelerated maturation of the regenerate in the ultrasound stimulated group even when a Bonferroni-Holm adjustment was used for multiple testing. CONCLUSION: Pulsed low-intensity ultrasound appears to stimulate the healing processes in the regenerate in this animal model and may have applicability in clinical practice.

[Therapy of aneurysmal bone cyst]. / Die Therapie der aneurysmatischen Knochenzyste.

The aneurysmal bone cyst represents a tumor-like lesion, which does not occur frequently. Every site of the skeleton may be involved. Although it can be observed at any age, it distinctly predominates from 10 to 20 years of age. Distinction of aneurysmatic bone cysts from certain benign or malignant bone tumours requires subtle imaging techniques and an experienced bone tumour pathologist. Since the lesion shows a heterogeneous biological behaviour and typically occurs in the growing skeleton, a wide range of surgical procedures must be provided concerning tumour resection and defect reconstruction. In the current retrospective study results of 41 surgically treated aneurysmal bone cysts, thereof 5 latent, 31 active, and 5 aggressive lesions, were investigated. While morbidity due to the therapeutic measures was comparatively low even in extended lesions and demanding reconstructions, a recurrence rate of 19.5% had to be observed in our series. Taking into consideration the biological activity of the lesion, analysis of the recurrences revealed inappropriate surgical margins had been chosen at the primary operation in all of these patients. Since the risk of a local relapse is linked both to aggressiveness of the primary lesion and to surgical radicality, therapy of aneurysmal bone cyst requires preoperative staging and stage-dependent surgical procedures.

The influence of stiffness of the fixator on maturation of callus after segmental transport.

The treatment of large bony defects by callus distraction is well accepted, but the duration of treatment is long and the rate of complications increases accordingly. We have examined the effect of the stiffness of the axial fixator on reducing the time for maturation of callus. We created a mid-diaphyseal defect of 15 mm in the metatarsal bone in sheep and stabilised it with a ring fixator. After four days a bony segment was transported for 16 days at 1 mm per day. After 64 days the animals were divided into four groups, three with axial interfragmentary movement (IFM) of 0.5, 1.2 and 3.0 mm, respectively, and a control group. The 3.0 mm IFM group had the smallest bone density (p = 0.001) and area of callus and the largest IFM after 12 weeks; it also had typical clinical signs of hypertrophic nonunion. The most rapid stiffening of the callus was in the 0.5 mm group which had the smallest IFM (p = 0.04) after 12 weeks and radiological signs of bridging of the defect. These results indicate that suitable dynamic axial stimulation can enhance maturation of distraction callus when the initial amplitude is small, but that a large IFM can lead to delayed union.

[Correction of complex deformities in infectious conditions]. / Die Korrektur komplexer Fehlstellungen in Infektsituationen.

Skeletal deformities do occur after conservative or operative fracture treatment, as a consequence of congenital growth disturbance and as sequlae after posttraumatic and haematogenous osteomyelitis. In postinfectious deformities the course of the bone and soft tissue infection plays a decisive role when choosing the appropriate operative technique. Even in non active situations with a closed soft tissues envelope and no draining sinus persistence of germs within the bone has to be anticipated. The biological quality of the bone and the soft tissue envelope is often reduced because of local changes and as a result of multiple local revisions. Consequently wide areas of scar tissue and sclerotic bone are often encountered. The apex of the deformity is in most cases identical with the focus of the active or non active infection. The correction of the deformity at the apex can therefore only be accomplished if the infectious bone is also resected. If a correction is not possible at the apex of the deformity, translation at the osteotomy site is necessary to achieve a correct mechanical axis. The later rather complex operative procedure necessitates intensive preoperative planning and an extensive experience with deformity corrections by external fixators.

[Tibiocalcaneal fusion for the treatment of talar necrosis. An analysis of 21 cases]. / Die tibiokalkaneare Arthrodese. Eine Analyse von 21 Fällen.

Between 1986 and 1996, 21 patients had a tibiocalcanear arthrodesis. Indications for surgery were in all cases either osteomyelitis or avascular necrosis of the talus. External stabilisation was used in 17 patients due to severe soft tissue damage or extensive infection of the talus, internal screw fixation was used in four patients. There were eight complications in seven patients, one patient had a below the knee amputation. The leg length discrepancies after resection of the talus was equalized in four cases with callus distraction using an Ilisarov ring fixator. Follow up evaluation was available in 18 patients after an average of 38 months (12-86 mo.). There were no infectious recurrencies during the follow up period and a solid fusion was achieved in all patients that were followed. According to a modified Kitaoka score, results were excellent and good in 12 of the 18 patients. External stabilisation, especially the Ilisarov ring fixator is the primary method of treatment in cases with severe infection or soft tissue damage.

[Correction of post-traumatic diaphyseal malalignment of the lower extremity]. / Die Korrektur posttraumatischer diaphysärer Fehlstellungen an der unteren Extremität.

Post-traumatic deformities do occur as a result of disturbed fracture healing with loss of bone stock, necrosis of fragments or the development of pseudarthrosis resulting in malunion or progressive malalignment. In the majority of the cases these disturbances can be related to technical problems of primary fracture treatment like insufficient reduction or implant failure. On the other hand, complex deformities with involvement of the adjacent joints may also be a result of injuries of the growth plate in childhood. In some cases primary correction is impossible because of critical conditions of the bone and the soft tissue envelope in the center of deformation. If a secondary correction is indicated, knowledge of all reconstructive techniques is essential to choose the appropriate method and carry out successful and exact correction of malalignment of the affected limb after detailed planning.

Fluorine-18-FDG PET and technetium-99m antigranulocyte antibody scintigraphy in chronic osteomyelitis.

UNLABELLED: The aim of this study was to assess the usefulness of PET with 2-18F-fluoro-2-deoxy-D-glucose (FDG), as compared to immunoscintigraphy (IS) with 99mTc-labeled monoclonal antigranulocyte antibodies (AGAbs), in the detection of chronic osteomyelitis. METHODS: Fifty-one patients suspected of having chronic osteomyelitis in the peripheral (n = 36) or central (n = 15) skeleton were evaluated prospectively with static FDG PET imaging and combined 99mTc-AGAb/99mTc-methylene diphosphonate (MDP) bone scanning within 5 days. FDG PET and IS were evaluated in a blinded and independent manner by visual interpretation, which was graded on a five-point scale of two observers' confident diagnosis of osteomyelitis. Receiver operating characteristic (ROC) curve analysis was performed for both imaging modalities. The final diagnosis was established by means of bacteriologic culture of surgical specimens and histopathologic analysis (n = 31) or by biopsy and clinical follow-up over 2 yr (n = 20). RESULTS: Of 51 patients, 28 had osteomyelitis and 23 did not. According to the unanimous evaluation of both readers, FDG PET correctly identified 27 of the 28 positives and 22 of the 23 negatives (IS identified 15 of 28 positives and 17 of 23 negatives, respectively). The area under the ROC curve was 0.97/0.97 (reader 1/reader 2) for FDG PET and 0.87/0.90 for IS, with a high degree of interobserver concordance (K-values were 0.96 for FDG PET and 0.91 for IS). In the central skeleton, the ROC curve area was 0.98/1.00 for FDG PET and 0.71/0.77 for IS (p<0.05). On the basis of ROC analysis, the overall accuracies of FDG PET and IS in the detection of chronic osteomyelitis were 96%/96% and 82%/ 88%, respectively. With regard to the optimal threshold values, sensitivity and specificity were 100%/97% and 95%/95% with FDG PET, compared to 86%/92% and 77%/82% with IS, respectively. CONCLUSION: In the peripheral skeleton, both FDG PET and combined 99mTc-AGAb/99mTc-MDP scanning are appropriate imaging modalities to diagnose chronic osteomyelitis. FDG PET additionally allows reliable differentiation between osteomyelitis and infection of the surrounding soft tissue. In the central skeleton within active bone marrow, FDG PET is highly accurate and superior to AGAb imaging in the diagnosis of chronic osteomyelitis, which frequently presents as a nonspecific photopenic lesion at scintigraphy with labeled white blood cells.

Local tissue properties in bone healing: influence of size and stability of the osteotomy gap.

To characterize the site-specific mechanical and histological properties in fracture repair and to relate these properties to the initial mechanical situation, an experimental fracture model was used in the metatarsus of 42 sheep. The mechanical situation of a transverse osteotomy was described by three gap sizes (1, 2, or 6 mm) and two amounts of strain (7 or 31%). An external fixator that allowed a defined axial movement provided control of these settings. Nine weeks following surgery, the healing area was dissected and tensile and compressive properties were measured in subregions of the fracture gap and the periosteal callus. The central, sagittal section was used for quantitative histology. We found the quality of the tissue along the osteotomy line to be most important for regaining mechanical stability. Increasing the size of osteotomy gaps resulted in poorer mechanical and histological qualities, and the repair process was less complete. Interfragmentary strain did not significantly influence the repair process. The smaller strain levels had already stimulated the secondary repair process, and this stimulatory effect could not be further enhanced by increasing the amount of strain. Our finding that large gaps between bone segments were not as well healed as were smaller gaps suggests that it is advantageous to avoid large gaps in fracture treatment.

Chronic osteomyelitis: detection with FDG PET and correlation with histopathologic findings.

PURPOSE: To evaluate use of positron emission tomography (PET) with 2-(fluorine-18) fluoro-2-deoxy-D-glucose (FDG) in detection of chronic osteomyelitis. MATERIALS AND METHODS: Thirty-one patients suspected to have chronic osteomyelitis in the peripheral (n = 21) or central (n = 10) skeleton were evaluated prospectively with FDG PET. Analysis of the receiver operating characteristic curve was performed. The final diagnosis was made by means of bacteriologic culture of surgical specimens and histopathologic analysis. RESULTS: FDG PET allowed identification of 17 of 18 patients with osteomyelitis and 12 of 13 without osteomyelitis. There was one false-positive and one equivocal result. The area under the ROC curve was 0.96 for all patients, 1.00 for patients suspected to have osteomyelitis in the peripheral skeleton, and 0.88 for patients suspected to have osteomyelitis in the central skeleton. The overall accuracy of FDG PET was 97% with a high degree of interobserver concordance (kappa = 0.93). The overall sensitivity and specificity were 100% and 92%, respectively. CONCLUSION: FDG PET enables noninvasive detection and demonstration of the extent of chronic osteomyelitis with a high degree of accuracy. Especially in the central skeleton within active bone marrow, FDG PET is highly accurate and shows great promise in diagnosis of chronic osteomyelitis.

Influence of size and stability of the osteotomy gap on the success of fracture healing.

Flexible fixation of fractures with minimally invasive surgical techniques has become increasingly popular. Such techniques can lead to relatively large fracture gaps (larger than 5 mm) and considerable interfragmentary movements (0.2-5 mm). We investigated the influence of the size of the fracture gap, interfragmentary movement, and interfragmentary strain on the quality of fracture healing. A simple diaphyseal long-bone fracture was modeled by means of a transverse osteotomy of the right metatarsus in sheep. In 42 sheep, the metatarsus was stabilized with a custom-made external ring fixator that was adjustable for gap size and axial interfragmentary movement. The sheep were randomly divided into six groups with three different gap sizes (1, 2, or 6 mm) and small or large interfragmentary strain (approximately 7 or 31%). The movement of the fracture gap was monitored telemetrically by a displacement transducer attached to the fixator. After 9 weeks of healing, the explanted metatarsus was evaluated mechanically in a three-point bending test to determine bending stiffness and was radiographed to measure the amount of periosteal callus formation. Increased size of the gap (from 1 to 6 mm) resulted in a significant reduction in the bending stiffness of the healed bones. Larger interfragmentary movements and strains (31 compared with 7%) stimulated larger callus formation for small gaps (1-2 mm) but not for larger gaps (approximately 6 mm). The treatment of simple diaphyseal fractures with flexible fixation can be improved by careful reduction of the fracture; this prevents large interfragmentary gaps. The experimental fracture model for the metatarsus showed that the healing process was inferior when the gap was larger than 2 mm.

[Correcting torsion after intramedullary nailing osteosynthesis of the lower extremity]. / Torsionskorrekturen nach Marknagelosteosynthesen der unteren Extremität.

Intraoperative control of torsion is delicate in intramedullary nailing of femur and tibia fractures. Post-traumatic torsional deformities cause clinical problems if the rotational 0-position, according to the neutral-0-method, cannot be attained or exceeded. The necessary precondition for every indication and planning of corrective osteotomies is conscientious analysis of the geometry of the lower extremities by clinical means, radiography and computed tomography. Operative procedures and techniques of corrective osteotomies in case of torsional deformities after intramedullary nailing are presented. Preoperatively, the intraindividual torsional differences in 15 patients with maltorsions of the femur were 33 degrees (-37/+50) and in 7 patients with maltorsions of the tibia 23 degrees (-21/+29). Positive signs indicate external and negative signs of internal maltorsions. Postoperatively, the intraindividual torsional differences were 6 degrees (-3/+14) in the femora and 7 degrees (+3/+12) in the tibiae. Therefore, the physiological torsional tolerance of 15 degrees was respected in all 22 patients. Additionally, limb lengthening was realized in 4 patients with shortening after intramedullary nailing of the femur. In 3 patients a one-step procedures with interposition of allogeneic cancellous bone in the osteotomy gap was performed and in one patient continuous callus distraction by external fixation.

[Covering soft tissue defects]. / Weichteildeckung.

In the past, the main emphasis in the treatment of complex limb injuries was placed upon the reconstruction of bony defects. Recently, however, reconstructive soft-tissue procedures have gained the attention they deserve. The salvage of a severely injured extremity depends rather on the feasibility of reconstructive surgical tissue procedures than on restoration of the bony defect. Sufficient vascularity is an essential condition for fracture healing and the prevention of post-traumatic complications like osteomyelitis and pseudarthrosis. If primary closure of a soft-tissue defect is not possible, preliminary covering has to be obtained with artificial skin replacement (vacuum sealing) until definitive covering with muscle or musculocutaneous flaps can be achieved. With the microvascular restorative techniques available today even complex soft-tissue problems can be solved. Nevertheless, an appropriate infrastructure and a trained and skilled surgeon are essential.

[Infected pseudarthrosis]. / Infizierte Pseudarthrose.

In open fractures the rate of infected non-union defects has in recent years decreased due to the increased primary application of external fixation. In spite of this positive state of affairs the condition is still encountered often enough to warrant specific treatment strategies and techniques. In the treatment of infected pseudarthroses the general principles of osteitis treatment are applied. This includes radical excision of infected pseudarthrotic bone and of the diseased surrounding soft tissue, provides mechanical stability in the non-union area and requires effective local treatment of the infection in combination with systemic, target-specific and temporary well-defined antibiotic therapy as well as procedures to improve local circulation. The incorporation of autogenous bone transplants in defects appears to depend on close contact between the transplant and the vascularized receiving site and on the quantity of the transplanted osseous material. A promising alternative method of dealing with extensive bone defects is osteogenesis produced by callus distraction; therefore special attention is given to Ilizarov's ring fixation system. Unstable scar formation demands local muscular flaps or microvascularized free flap transfer, which seems to be superior to other methods.

[Local complications of intramedullary nailing]. / Lokale Komplikationen der Marknagelung.

In the period from January 1990 to the end of December 1995 intramedullary nailing was performed in 294 patients with 156 fractures of the femur and 162 fractures of the tibia. Early nailing within the first 24 h after trauma was realized in 70% of the femur and in 64% of the tibia fractures. A synopsis focusing on local complications after intramedullary nailing is given on the basis of our results and a thorough analysis of the literature. Iatrogenic fractures of the femoral neck (0-5%), of the proximal femur (0.8-11.2%) and of the tibial head (0-8.3%) represent important intraoperative complications. Less frequent, but even more serious, are intraoperative lesions of nerves and arteries, as well as the development of compartmental syndromes of the lower leg (0-8.6%). Lengthy procedures and the use of traction tables seem to foster those complications. After primary intramedullary nailing, non-unions of the femur can be expected in 1-2% and of the tibia in 2-4%. The corresponding rates of osteomyelitis are 1-1.5% and 2-3%, respectively. After secondary nailing, particularly when changing from external fixation, and in cases of open fractures, the risk of deep infection is essentially elevated. Intramedullary nailing of the femur presents an important tendency to external torsional malalignment. In our investigation the torsional tolerance of 15 degrees was exceeded in 26%. A corresponding postoperative shortening of more than 2 cm length difference can be expected in 1.7-9.8%. Spiral fractures of the distal tibia offer a critical tendency to secondary varus and torsional malalignment, particularly after unreamed nailing and consecutive shortening due to breakage of locking bolts. The therapeutic indications of fracture stabilization in cases of unstable metaphyseal fractures should be reviewed.

In vivo effect of shock-waves on the healing of fractured bone.

In a controlled animal experiment we attempted to clarify the question of whether there is a stimulating effect of extracorporeal shock-waves on the repair process of fractured long bones. As a fracture model we used an osteotomy in the diaphysis of the ovine tibia and an external fixation device. Shock-wave treatment at two levels of intensity and with four different numbers of applied shocks was performed with an electromagnetic acoustic source. Healing of the osteotomized bone was evaluated by biomechanical and radiological investigations on the whole bone as well as on bone sections from areas of the fracture gap and the periosteal fracture callus. We found a non-significant tendency to deterioration of the fracture healing with increasing shock-wave intensities. The study of treatment parameters led neither to significantly different biomechanical outcomes nor to altered radiological results in comparison to the untreated control group. RELEVANCE:--While we cannot comment upon the effectiveness of extracorporeal shock-waves in the delayed treatment of fractures or pseudarthrosis, our results suggest that shock-waves have no beneficial effect in acute fracture repair.

[Open segmental bone transport. A therapeutic alternative in post-traumatic and osteitis soft tissue and bone defects]. / Der offene Segmenttransport. Eine therapeutische Alternative bei posttraumatischen und osteitischen Weichteil- und Knochendefekten.

Between 1990 und 1992, 22 patients with bone and soft tissue defects were treated by open segmental bone transport according to Ilizarov, and 20 of these were followed up over a period of 18 months after removal of the external fixator. In 19 cases the bone defect could be filled by callus distraction only, while 1 patient needed additional spongeous bone transplantation because of delayed ossification. In 1 case amputation was necessary because of extensive fistula carcinoma of the resected bone and soft tissue. Closure of soft tissue defect was achieved in 14 patients simultaneously with docking of the bone segments. In 5 patients additional skin transplantation was needed, and in 1 case a latissimus dorsi flap had to be transferred because of unstable scar formation. Transporting vital bone simultaneously with the overlying tissue into a defect allows for limb salvage even in poor biological conditions and in patients with vascular problems. Open bone transfer has extended the range of methods available for the treatment of bone and soft tissue defects.

Ilizarov callus distraction produces systemic bone cell mitogens.

We tested the hypothesis that the application of strain during callus distraction induces systemic osteoblast stimulating factors that enhance osteoblast activity both locally and systemically. To study the systemic occurence of strain-induced osteoblast stimulating factor during callus distraction, we investigated the mitogenic capacity of sera from 12 patients who had undergone callus distraction on the osteoblastic cell line SaOS-2 (part I). Serum samples from six patients who had undergone rigidly fixed high tibial osteotomy (i.e., without distraction) served as controls. The sera were assayed for platelet-derived growth factor and transforming growth factor-beta. In part II of the study, the in vitro effects of mechanical strain were investigated in a simplified model by cyclic stimulation of osteoblast cultures isolated from cortical bone explants from the same patients; a specially developed apparatus was used for cell-stretching. Sera taken during the third to fourth week of callus distraction demonstrated a significant increase in proliferation of SaOS-2 cells (p < 0.005). In contrast, sera from patients who had had an osteotomy failed to induce or decreased the mitogenic capacity of SaOS-2 cells. The concentration of platelet-derived growth factor increased significantly (p < 0.01) in sera from both the patients who had undergone callus distraction and the controls who had had osteotomy. However, the level of transforming growth factor-beta was increased (p < 0.05) in the sera from the patients who had distraction (sera that stimulated proliferation of SaOS-2 cells), but the level was not increased in the sera from patients who had osteotomy.(ABSTRACT TRUNCATED AT 250 WORDS)