Das Parallels?geblatt

Problem

For shortening osteotomy, two exactly parallel osteotomies are needed to assure a congruent adaption of the shortened bone after segment resection. This is required for regular bone healing. In addition, it is difficult to shorten a bone to a precise distance using an oblique segment resection.

Solution

A mobile spacer between two saw blades keeps the distance of the blades exactly parallel during an osteotomy cut. The parallel saw blades from Synthes? are designed for 2, 2.5, 3, 4, and 5?mm shortening distances. Two types of blades are available (e.g., for transverse or oblique osteotomies) to assure precise shortening.

Surgical technique

Preoperatively, the desired type of osteotomy (transverse or oblique) and the shortening distance has to be determined. Then, the appropriate parallel saw blade is chosen, which is compatible to Synthes? Colibri with an oscillating saw attachment. During the osteotomy cut, the spacer should be kept as close to the bone as possible. Excessive force that may deform the blades should be avoided. Before manipulating the bone ends, it is important to determine that the bone is completely dissected by both saw blades to prevent fracturing of the corticalis with bony spurs. The shortening osteotomy is mainly fixated by plate osteosynthesis. For compression of the bone ends, the screws should be placed eccentrically in the plate holes. For an oblique osteotomy, an additional lag screw should be used.     

The anti-diabetic drug metformin does not affect bone mass in vivo or fracture healing

Summary

The present study shows no adverse effects of the anti-diabetic drug metformin on bone mass and fracture healing in rodents but demonstrates that metformin is not osteogenic in vivo, as previously proposed.

Introduction

In view of the increased incidence of fractures in patients with type 2 diabetes mellitus (T2DM), we investigated the effects of metformin, a widely used T2DM therapy, on bone mass and fracture healing in vivo using two different rodent models and modes of metformin administration.

Methods

We first subjected 12-week-old female C57BL/6 mice to ovariectomy (OVX). Four weeks after OVX, mice received either saline or metformin administered by gavage (100 mg/kg/daily). After 4 weeks of treatment, bone micro-architecture and cellular activity were determined in tibia by micro-CT and bone histomorphometry. In another experiment, female Wistar rats aged 3 months were given only water or metformin for 8 weeks via the drinking water (2 mg/ml). After 4 weeks of treatment, a mid-diaphyseal osteotomy was performed in the left femur. Rats were sacrificed 4 weeks after osteotomy and bone architecture analysed by micro-CT in the right tibia while fracture healing and callus volume were determined in the left femur by X-ray analysis and micro-CT, respectively.

Results

In both models, our results show no significant differences in cortical and trabecular bone architecture in metformin-treated rodents compared to saline. Metformin had no effect on bone resorption but reduced bone formation rate in trabecular bone. Mean X-ray scores assessed on control and metformin fractures showed no significant differences of healing between the groups. Fracture callus volume and mineral content after 4 weeks were similar in both groups.

Conclusions

Our results indicate that metformin has no effect on bone mass in vivo or fracture healing in rodents.     

Kniegelenknahe Osteotomietechniken

Background

Bone geometry following osteotomy around the knee suggests that biplanar rather than uniplanar open wedge techniques simultaneously create smaller wedge volumes and larger bone surface areas. However, precise data on the bone surface area and wedge volume resulting from both open and closed wedge high tibial osteotomy (HTO) and distal femoral osteotomy (DFO) techniques remain unknown.

Objectives

It was hypothesized that biplanar rather than uniplanar osteotomy techniques better reflect the ideal geometrical requirements for bone healing, representing a large cancellous bone surface combined with a small wedge volume.

Methods

Tibial and femoral artificial bones were assigned to four different groups of valgisation and varisation osteotomy consisting of open wedge and closed wedge techniques in a uniplanar and biplanar fashion. Bone surface areas of all osteotomy planes were quantified. Wedge volumes were determined using a prism-based algorithm and applying standardized wedge heights of 5 mm, 10 mm and 15 mm.

Results

Both femoral and tibial biplanar osteotomy techniques created larger contact areas and smaller wedge volumes compared to the uniplanar open wedge techniques.

Conclusion

Although this idealized geometrical view of bony geometry excludes all biological factors that might influence bone healing, the current data suggest a general rule for the standard osteotomy techniques applied and all surgical modifications: reducing the amount of slow gap healing and simultaneously increasing the area of faster contact healing may be beneficial for osteotomy healing. Thus, biplanar rather than uniplanar osteotomy should be performed for osteotomy around the knee.     

Zuklappende supratuberositäre Tibiakopfvalgisationsosteotomie

Objective

Well-balanced charge of femoral and tibial cartilage by lateral transfer of the mechanical leg axis in osteoarthritis of the medial compartment and of genu varum.

Indications

Symptomatic medial compartment osteoarthritis (MCOA). Posttraumatic varus deformity. Varus malalignment and planned reconstructive procedures of the cartilage in the medial knee compartment.

Contraindications

Cartilage lesion grade ≥III° (according to Outerbridge, 1961) in the lateral compartment. State after lateral meniscectomy. Patellofemoral osteoarthritis with extension lag >?10°. Femoral varus deformity. Knee instabilities. Advanced osteoporosis. Neurological disorders. General risks of adequate bone healing. Obesity (BMI >?30 kg/m²).

Surgical technique

Preoperative planning according to true-nominal analysis (according to Strecker, 2002) including a maximum and minimum extent of mechanical axis correction (according to Müller and Strecker, 2008). Arthroscopy of the knee to determine the cartilage status. In high tibial closed wedge valgus osteotomies >?10° an oblique osteotomy of the distal diaphyseal fibula is mandatory. Lateral approach and preparation of the tibial head. Partial osteotomy of the proximal tibial tuberosity. Defined angle of valgisation fixed by two laterally introduced K-wires. Bending of a 5-hole DC-plate (DCP). Transversal osteotomy with oscillating saw, medial cortex of tibial head remaining intact. Fixation of pre-bent DCP in the proximal hole. Gentle closing of osteotomy gap with distal cortical “play screw” in plate hole 5. Compression of the osteotomy gap with two interfragmentary screws in holes 2 and 3. Completion of internal fixation and change of “play screw”. In case of fibula osteotomy, further resection and internal fixation.

Postoperative management

First day after surgery: removal of drainage, x-ray control, mobilization. Partial weight bearing of 20 kg during 4 weeks postoperatively followed by 20 kg additional load per week according to clinical and radiological findings. Physical training with active and passive motion exercises. Low-molecular-weight heparin for at least 4 weeks.

Results

Between January 2006 and December 2008, procedure performed in 50 patients (27 men, 23 women, mean age 44 years); arthroscopic treatment in 43 patients, and osteotomy of the fibula in 10 patients. The valgus correction was 8.4° (6–13°). No complication during surgery. One non-union was treated by cancellous bone grafting.     

Poor histological healing of a femoral fracture following 12 months of oestrogen deficiency in rats

Summary

Fractures in post-menopausal osteoporosis cause significant morbidity; however, animal models for post-menopausal fracture healing lack the effect of ageing. Therefore, we developed a model using aged animals with chronic oestrogen deficiency, which demonstrates inferior fracture repair (decreased healing histologically, bone mineral density and content and strength). This novel model may help develop molecular strategies for osteoporotic fracture repair.

Introduction

The femur is susceptible to damage by both systemic conditions such as osteoporosis and locally by traumatic injury. The capacity for fracture repair decreases with age, while the risk of fracture increases. As studies of osteoporotic fracture healing in rats traditionally use a period of 3 months or less of oestrogen deficiency prior to fracturing, we aimed to establish a osteoporosis model in rats with chronic oestrogen deficiency by 12 months to better mimic human female osteoporosis.

Methods

Seventy female Sprague–Dawley rats (10 weeks old) were ovariectomised or sham operated and housed for 12 months. The right femur was fractured by way of an open osteotomy and fixed with an intramedullary Kirschner wire. Animals were sacrificed at 1, 3 and 6 weeks for radiography, dual-energy X-ray absorptiometry, tensile testing and histology.

Results

Bone mineral density and bone mineral content were lower by 60 and 63 %, respectively, (p?<?0.05) in the bilaterally ovariectomized (OVX) groups than those in the sham groups at 6 weeks in the right fractured femurs. Maximum breaking force of the OVX group was lower than that of the sham group, with the greatest difference seen at 6 weeks following osteotomy. Histologically, the OVX groups demonstrated a delay in cellular differentiation within the fracture callus and the presence of bone resorption. The sham animals had a superior histological healing pattern with an Allen score of 4 at 6 weeks compared to a score of 1 for the OVX groups (p?<?0.01).

Conclusions

Long-term ovariectomy has a deleterious effect on fracture healing in a rodent model.     

Serum albumin enhances bone healing in a nonunion femoral defect model in rats: a computer tomography micromorphometry study

Purpose

Blood-derived proliferative factors such as platelet rich plasma or activated plasma are promising adjuvants for bone grafts. Our earlier studies showed that serum albumin itself can markedly enhance the proliferation of stem cells on bone allograft and postulated that albumin coating alone may improve bone graft integration in vivo.

Methods

Two femoral defect models were performed in adult male Wistar rats. In the critical size model a six millimetre gap was created in the midshaft of the femur and fixed with plate and screws, while a nonunion model was established by the interposition of a spacer in the osteotomy for four weeks which resulted in compromised healing and nonunion. Albumin coated and uncoated grafts were placed into the defects. Bone healing and morphometry were evaluated by μCT and histology four weeks after implantation of the grafts.

Results

In the critical size model none of the bone grafts were able to bridge the defect, and graft resorption was the typical outcome. In the nonunion model regular uncoated grafts had a low union rate (two out of six), which increased markedly when albumin coating was applied (six out of eight). Trabecular thickness and pattern factor improved significantly in the albumin coated group versus uncoated or empty controls.

Conclusions

Our results showed that serum albumin coating of bone grafts can enhance the remodelling and efficacy of treatment in a nonunion model.     

Promotion of peri-implant bone healing by systemically administered parathyroid hormone (1-34) and zoledronic acid adsorbed onto the implant surface

Summary

The effect of human parathyroid hormone 1-34 (PTH) and zoledronic acid (ZA) alone or in combination on bone healing in osteoporotic settings was tested using implants inserted in tibiae of ovariectomized (OVX) rats. Combination therapy promoted bone healing more than each treatment alone 12 weeks after implant insertion.

Introduction

PTH and ZA have been demonstrated to be effective on implant fixation. However, reports about the combined use of PTH and ZA for promotion of bone healing around implant in osteoporotic settings are still limited. This study aims to investigate effects of PTH+ZA on implant stabilization in OVX rats.

Methods

Twelve weeks after bilateral ovariectomy, OVX rats randomly received implants without or with ZA (by immersion in 1 mg/ml ZA solution for 24 h). Subsequently, half of the animals from each group also received subcutaneous injections of PTH (60 μg/kg, three times a week) for 12 weeks. Thus, there were four groups: control, PTH, ZA, and PTH+ZA.

Results

All treatments promoted bone healing around implant compared to control, but PTH+ZA treatment showed significantly stronger effects than PTH or ZA alone in histological, micro-CT, and biomechanical tests.

Conclusion

The results indicated the additive effects of PTH and ZA on implant fixation in OVX rats; it was suggested that the anabolic effect of PTH was potent and not blunted by ZA during bone healing around implant when used concurrently.     

Kombinierte Salter-Pemberton-Beckenosteotomie

Objective

In simple pelvic osteotomy in childhood the aim is for better lateral roofing, a safe centering of the femoral head and tuning between the volumes of the acetabulum and the femoral head. By the combination of anterior modified Pemberton osteotomy with dorsal osteotomy according to Salter these objectives can be achieved.

Indications

Dysplasia of the acetabulum in patients between 2 years old and adolescence, subluxation and dislocation of the femoral head, also in neurological diseases as cerebral palsy and hypercontainment in Legg-Calvé-Perthes disease.

Contraindications

Critically small pelvic bones in toddlers younger than 18 months, children with a delay in skeletal formation. In patients aged more than 15 years if the symphysis is too taut for an effectual pivoting of the acetabulum and the acetabulum has no potential for future maturing.

Surgical technique

Surgery is carried out by making a skin incision by the iliac crest ending in the middle of the groin, the cartilaginous iliac apophysis is split and the periosteum is elevated from the medial and lateral wall of the ilium to the inner pelvic ring. A K-wire is used to mark the level and the center of the osteotomy and dorsal to the K-wire a straight osteotomy is performed with a Gigli saw and anteriorly an arc-shaped and tilted cut is made with a chisel. The distal iliac fragment is rotated widely outwards and forwards and a triangular bone graft is removed from the anterior part of the iliac crest. The graft is inserted into the opened up osteotomy, three K-wires are used to fix the desired position of the iliac fragments and the two halves of the iliac apophysis are sutured together.

Postoperative management

After the operation uncooperative children receive a scotch cast for 4 weeks. Cooperative children are mobilized after 3 weeks of bed rest. Partial weight-bearing is allowed after 6 weeks and full weight-bearing after 8–10 weeks.

Results

A total of 56 combined Salter-Pemberton pelvic osteotomies were performed in 49 patients from 1999 to 2008. The results of these studies demonstrate that this osteotomy is a safe and effective procedure which enables not only sufficient correction in classical dysplasia of the hip joint but also in high grade dislocation of the hip joint caused by cerebral palsy.     

Novel Microhydroxyapatite Particles in a Collagen Scaffold: A Bioactive Bone Void Filler?

Background

Treatment of segmental bone loss remains a major challenge in orthopaedic surgery. Traditional techniques (eg, autograft) and newer techniques (eg, recombinant human bone morphogenetic protein-2 [rhBMP-2]) have well-established performance limitations and safety concerns respectively. Consequently there is an unmet need for osteoinductive bone graft substitutes that may eliminate or reduce the use of rhBMP-2.

Questions/purposes

Using an established rabbit radius osteotomy defect model with positive (autogenous bone graft) and negative (empty sham) control groups, we asked: (1) whether a collagen-glycosaminoglycan scaffold alone can heal the defect, (2) whether the addition of hydroxyapatite particles to the collagen scaffold promote faster healing, and (3) whether the collagen-glycosaminoglycan and collagen-hydroxyapatite scaffolds are able to promote faster healing (by carrying a low dose rhBMP-2).

Methods

A 15-mm transosseous radius defect in 4-month-old skeletally mature New Zealand White rabbits were treated with either collagen-hydroxyapatite or collagen-glycosaminoglycan scaffolds with and without rhBMP-2. Autogenous bone graft served as a positive control. Time-series radiographs at four intervals and postmortem micro-CT and histological analysis at 16 weeks were performed. Qualitative histological analysis of postmortem explants, and qualitative and volumetric 3-D analysis of standard radiographs and micro-CT scans enabled direct comparison of healing between test groups.

Results

Six weeks after implantation the collagen-glycosaminoglycan group had callus occupying greater than ½ the defect, whereas the sham (empty) control defect was still empty and the autogenous bone graft defect was completely filled with unremodeled bone. At 6 weeks, the collagen-hydroxyapatite scaffold groups showed greater defect filling with dense callus compared with the collagen-glycosaminoglycan controls. At 16 weeks, the autogenous bone graft groups showed evidence of early-stage medullary canal formation beginning at the proximal and distal defect borders. The collagen-glycosaminoglycan and collagen-glycosaminoglycan-rhBMP-2 groups had nearly complete medullary canal formation and anatomic healing at 16 weeks. However, collagen-hydroxyapatite-rhBMP-2 scaffolds showed the best levels of healing, exhibiting a dense callus which completely filled the defect.

Conclusions

The collagen-hydroxyapatite scaffold showed comparable healing to the current gold standard of autogenous bone graft. It also performed comparably to collagen-glycosaminoglycan-rhBMP-2, a representative commercial device in current clinical use, but without the cost and safety concerns.

Clinical Relevance

The collagen-glycosaminoglycan scaffold may be suitable for a low load-bearing defect. The collagen-hydroxyapatite scaffold may be suitable for a load-bearing defect. The rhBMP-2 containing collagen-glycosaminoglycan and collagen-hydroxyapatite scaffolds may be suitable for established nonunion defects.     

Osteotomie am distalen Femur zur Korrektur von Genu valgum und Torsionsfehlern

Objective

Femoral medial closing wedge osteotomy for the correction of valgus malalignment to unload the cartilage in the lateral compartment and/or correction of symptomatic torsional malalignment.

Indications

Lateral unicompartmental osteoarthritis of the knee with genu valgum in young patients. Symptomatic torsional malalignement of >?30° and <?0°.

Contraindications

Grade 3 and 4 cartilage damage in the medial compartment. Heavy smoking. Medial meniscectomy. Extreme obesity. Inadequate soft tissue conditions.

Surgical technique

The operation begins with arthroscopy of the knee joint. In case of grade 4 lateral cartilage damage, a microfracture is performed. The distal femur is exposed via an anteromedial longitudinal incision starting 10 cm above the patella and ending in the upper third of the patella. The medial femoral cortex is exposed using Hohmann retractors and an oblique closing wedge osteotomy is performed with an oscillating saw. In case of valgus correction, the lateral cortex is left intact. In case of correction of torsional malalignment, the osteotomy plane is horizontal and the lateral cortex is cut. The wedge height is determined preoperatively based on full leg x-rays. The leg axis is controlled intraoperatively with a long metal rod and the use of an image intensifier. The osteotomy is manually closed and stabilized with a locking plate.

Postoperative management

The patient is mobilized under load with 20 kg body weight for the first 6 postoperative weeks. Full range of motion is permitted.

Results

We treated 23 patients with lateral cartilage damage (grades 3 and 4) and genu valgum with medial closing osteotomy of the distal femur (6 men and 17 women). After 3.5-years follow-up, the KOOS increased from 48.4 points to 84.9 points. In one case, there was an early loss of correction, with subsequent revision with bone grafting and lateral osteosynthesis. No peri-or postoperative complications such as infection, thrombosis, and embolism occurred [24]. In 5 cases a torsional osteotomy was performed. The torsional osteotomy was performed 4 times due to chronic patellofemoral instability, and once due to a medial tibiofemoral instability. Healing complications were not observed in this population. Recurrent instability was not observed.     

Ulnar shortening with the ulna osteotomy locking plate

Objective

Ulnar shortening for ulnocarpal unloading using a new device enabling parallel osteotomy, rotation-secured compressive shortening, lag screw placement and hybrid stabilization combined in a solely locking plate construct.

Indications

Idiopathic ulnar impaction syndrome. Posttraumatic radial shortening without major tilting of the radius in the sagittal or frontal plane, rotation deformity and/or translation of the distal fragment.

Contraindications

Advanced arthritis of the distal radioulnar joint (DRUJ), DRUJ type?III according to Tolat, malunion of the distal radius with major tilting of the radius in the sagittal or frontal plane, rotation deformity and/or translation of the distal fragment.

Surgical technique

Mounting of the UOL plate system on the palmar surface of the ulna using standard ulnopalmar exposure. Two parallel 45° osteotomies are performed using an osteotomy guide followed by rotation secured shortening and compression. Stabilization is gained by inserting an interfragmentary lag screw perpendicular to the osteotomy site and applying locking and compression screws.

Postoperative management

Lower arm cast for 4?weeks until radiological signs of bone healing become apparent. To limit negative influence of rotational forces during bone healing, patients were instructed to limit forearm rotation up to 30° in pro-/supination.

Results

Sixteen ulnar shortening osteotomies were performed in 15?patients (6?men, 9?women, average age 49?years) and evaluated retrospectively. In 10?cases a trauma-related pathology was the indication for the procedure. The average follow-up time was 53?weeks (range 12?C93?weeks). Bone union was observed at a median of 10?weeks (range 6?C33?weeks). Overall good clinical results could be achieved with an average shortening of 3.7?mm (range 2.1?C16?mm). In this series, there was one nonunion.     

Restdysplasie im Kleinkindesalter

Objective

Restoration of a congruent, stable, mobile hip joint with normal function.

Indications

Persistent acetabular dysplasia of congenital or neuromuscular origin in children with still open triradiate cartillage.

Contraindications

Age under 18 months, closed triradiate cartilage, femoral head deformity.

Surgical technique

Incomplete supraacetabular transiliac osteotomy, the correction is performed by reshaping the acetabulum taking advantage of the inherent flexibility of the triradiate cartilage and the periacetabular bone. A triangular bioresorbable xenograft is used to maintain the correction until bony healing.

Postoperative management

Cast immobilization is not necessary, non-weight bearing for 4 weeks after surgery, then full weight bearing.

Results

In all, 31 hips in 20 patients were surgically treated for persistent acetabular dysplasia with the Dega acetabuloplasty. The results were retrospectively studied. The mean age at surgery was 42 months (range 31–67 months). The mean follow-up was 31 months (range 12–60 months). The acetabular angle before surgery measured 31.5° (range 27–44°) and was corrected to 14° (range 8–20°) at last follow-up. All patients showed at last presentation normal hip range of motion and had no complaints. None of the patients had functional restrictions. Severe complications were not observed. Transitory inguinal swelling was observed in only 3 cases in the immediate postoperative period and resolved completely without sequelae.     

Compromised osseous healing of dental extraction sites in zoledronic acid-treated dogs

Summary

The goal of this study was to document how treatment with high doses of zoledronic acid affects dental extraction healing. Our results, showing significantly compromised osseous healing within the socket as well as presence of exposed bone and development of a sequestrum in one animal, provide a building block toward understanding osteonecrosis of the jaw.

Purpose

The goal of this study was to document how treatment with a bisphosphonate affects the bone tissue following dental extraction.

Methods

Skeletally mature female beagle dogs were either untreated controls (CON) or treated with intravenous zoledronic acid (ZOL). Following the extraction of the fourth premolars, healing was allowed for 4 or 8 weeks. Properties of the extraction site were assessed using microcomputed tomography (micro-CT) and dynamic histomorphometry.

Results

The initial infilling of the extraction socket with bone was not affected by ZOL, but subsequent removal of this bone was significantly suppressed compared to CON. After 8 weeks of healing, the alveolar cortical bone adjacent to the extraction socket had a remodeling rate of ～50% per year in CON animals while ZOL-treated animals had a rate of <1% per year. One ZOL-treated animal developed exposed bone post-extraction which eventually led to the formation of a sequestrum. Assessment of the sequestrum with micro-CT and histology showed that it had features consistent with those reported in humans with osteonecrosis of the jaw.

Conclusions

These results, showing significantly compromised post-extraction osseous healing as well as presence of exposed bone and development of a sequestrum in one ZOL animal, provide a building block toward understanding the pathophysiology of osteonecrosis of the jaw.     

Weak link of tendon–bone healing and a control experiment to promote healing

Objective

This study aims to observe the mechanical weak point and histological features of tendon–bone interface after anterior cruciate ligament reconstructive surgery and to explore the tendon–bone healing effects of the platelet-rich gel (PRG) + deproteinized bone (DPB) compound.

Methods

A total of 48 New Zealand white rabbits were randomly divided into normal group, model (without embedding), experimental (embedded with the PRG + DPB compound), and control (embedded with DPB) groups. The rabbits were executed at 2, 4, 8, and 12 weeks after the operation. Then, micro-computed tomography scan and uniaxial tensile test were conducted. The fractured specimens were subjected to histological observation.

Results

At 4, 8, and 12 weeks after the operation, the bone density of the tendon–bone bound section of the experimental group was higher than that of the other groups (P < 0.05). At 4 and 8 weeks, the maximum tensile load of the experimental group was obviously higher than that of the control and model groups (P < 0.05). Histological observation indicated that the tendon–bone interface in the experimental group had more cartilage and bone tissue growing toward the internal tendon, but the fracture layer mainly occurred in the non-ankylosed part.

Conclusion

The mechanical weak point of the early tendon–bone interface was in the immature fibrous tissue. The PRG + DPB compound can effectively trigger tendon–bone healing by promoting the maturation and ossification of the tendon–bone tissue. This compound improved the tensile strength of the healing interface and reduced bone tunnel enlargement.     

Efficacy of two different demineralised bone matrix grafts to promote bone healing in a critical-size-defect: a radiological,histological and histomorphometric study in rat femurs

Purpose

The aim of the study was to compare two different demineralised bone matrices used clinically regarding their ability to induce bone healing in a critical-size-defect rat model.

Methods

We stabilised 4 mm femur defects with a custom-made plate and filled them either with demineralised bone matrix (DBM) or DBX (DBX Putty®). Bone morphogenetic protein 2 (BMP-2)-loaded collagen and an empty defect served as controls. The outcome was followed after 21 and 42 days by radiology (Faxitron; microCT) and histology.

Results

Defect healing did not occur in any animal from the empty control, DBM or DBX group. Residuals of the implanted material were still found after six weeks, but only limited callus formation was visible. In contrast, the BMP-2 control demonstrated enhanced formation of callus tissue and undisturbed healing. After 21 days, 11 out of 16 and after 42 days, 7 out of 8 BMP-2-treated animals showed complete defect bridging by cancellous bone tissue.

Conclusions

Demineralised bone grafts were not capable of defect reconstruction; only BMP-2 was able to provide sufficient stimulus to induce uneventful bridging under the specific experimental conditions.     

The clinical outcomes of extracorporeal irradiated and re-implanted cemented autologous bone graft of femoral diaphysis after tumour resection

Purpose

We report the outcome of intercalary resection of the femoral diaphysis and extracorporeal irradiated autologous bone graft reconstruction, without the use of vascularized fibular graft.

Methods

Six patients with Ewing sarcoma of the mid-shaft femur who were treated by limb sparing tumour resection and reconstruction with extracorporeal irradiated autologous bone graft with intramedullary cement between 2002 and 2010 were studied.

Results

Mean age at the time of surgery was ten years (range, four–23). The length of resected femoral bone averaged 23 cm (15–32 cm). The ratio of bone resection length to total femoral length averaged 60 % (56–66 %). The patients had been followed up for between 16 and 79 months (mean, 41 months) at the time of the study. There was no infection nor fracture in this series. Primary union of the distal and proximal osteotomy sites was achieved in three patients. Delayed union of the proximal osteotomy site occurred in one patient that was successfully treated with iliac crest bone grafting. One patient developed non-union at the distal osteotomy site which failed to heal with bone grafting and was therefore converted to endoprosthetic replacement, and another patient was converted to rotationplasty at five months post-surgery because of contaminated margins. Function was excellent in all patients with surviving re-implanted bone. Local recurrence arose in one patient.

Conclusion

Our experience suggests that cement augmentation of extracorporeal irradiated and re-implanted bone autografts offer a useful method of reconstructing large femoral diaphyseal bone defects after excision of primary malignant bone tumours.     

Suprakondyläre Femurosteotomien in Kniegelenknähe

Background

Similar to the reappreciation of high tibial osteotomy (HTO), supracondylar distal femur varus osteotomy (SCO) for lateral compartment osteoarthritis (OA) of the knee has gained renewed interest as new knowledge has become available on the influence of malalignment on the development, progression and symptoms of OA. Furthermore, the less than optimal results of total knee replacement (TKR) in younger patients have also led to renewed interest in joint-preserving treatment options.

Purpose

Varus SCO has not had the same success or widespread use as valgus HTO. The goal in SCO is similar to HTO, to shift the load from the diseased to the healthy ompartment, in order to reduce pain, improve function and delay placement of a TKR. Valgus OA however occurs much less frequently than varus OA and varus SCO is considered a technically more demanding procedure. In the past the surgical techniques for SCO were mainly dependent on difficult-to-use implants making the procedure more complex. Complication rates related to the failure of fixation up to 16 % have been reported.

Disussion

The new biplane osteotomy technique fixated with a locking compression plate is very stable; bone healing potential is optimal using this technique and takes 6–8 weeks. Full weight bearing before full bone healing is possible without loss of correction.

Conclusion

In this article patient selection, planning, surgical techniques, stability of fixation and bone healing for SCO are discussed. In the past the surgical techniques for SCO were mainly dependent on difficult to use implants making the procedure more complex. Complication rates related to the failure of fixation of up to 16 % have been reported.     

Calcium Phosphate Cement with BMP-2-loaded Gelatin Microspheres Enhances Bone Healing in Osteoporosis: A Pilot Study

Background

The capacity for bone healing reportedly is limited in osteoporosis with a less than ideal environment for healing of bone grafts. We therefore developed a composite bone substitute with rhBMP-2 loaded gelatin microsphere (GM) and calcium phosphate cement (CPC) to use in osteoporosis.

Questions/purposes

We asked whether (1) controlled release of rhBMP-2 could be improved in this composite bone substitute and (2) increasing factors released from the bone substitute could accelerate osteoporotic bone healing.

Methods

We soaked rhBMP-2/GM/CPC and rhBMP-2/CPC composites in simulated body fluid for 28 days and then determined the amount of rhBMP-2 released. Both composites were implanted in bone defects of osteoporotic goats and left in place for 45 and 140 days; the specimens then were evaluated mechanically (pushout test) and morphologically (CT scanning, histology).

Results

The in vitro study showed the new composite released more rhBMP-2 compared with rhBMP-2/CPC. CT showed the defects healed more quickly with new grafts. The bone mineralization rate was greater in rhBMP-2/GM/CPC than in rhBMP-2/CPC after 45 days of implantation and the pushout test was stronger after 45 and 140 days of implantation.

Conclusions

The new graft composite released more loaded factors and appeared to repair osteoporotic bone defects.

Clinical Relevance

These preliminary data suggest the new composite can be used as a bone substitute to accelerate healing of fractures and bone defects in osteoporosis.     

Intelligente Implantate für das Monitoring der Knochenheilung

Background

Monitoring of fracture healing is a complex problem. Radiographs solely enable the estimation of calcification.

Telemetric determination of bone healing

A telemetric system to mechanically assess bone healing was developed. The system consists of an electronic unit applied to a locked plate, an external reader and a ground sensor to measure externally applied loads. By correlating the externally applied load and deformation in the implant, the elasticity of the osteosynthesis is calculated. Elasticity decreases with ongoing consolidation of a fracture or nonunion and is appropriate to monitor the course of bone healing.

Clinical application

Clinical application was performed in 56 patients suffering nonunions or a fracture of the femur; in 47 cases treatment was completed. In 46 of 47 patients, consolidation was achieved. Different types of healing curves could be differentiated (fast healing, slow healing, plateau with following fast healing, nonhealing).

Conclusion

The system proved to be valuable for the judgement of bone healing in difficult healing situations. Routine cost-effective manufacturing is possible, because the used electronic components are derived from mass products.