Objectives. Long bone defects often require surgical intervention for functional restoration. The ‘gold standard’ treatment is autologous bone graft (ABG), usually from the patient’s iliac crest. However, autograft is plagued by complications including limited supply, donor site morbidity, and the need for an additional surgery. Thus, alternative therapies are being actively investigated. Autologous bone marrow (BM) is considered as a candidate due to the presence of both endogenous reparative cells and growth factors. We aimed to compare the therapeutic potentials of autologous bone marrow aspirate (BMA) and ABG, which has not previously been done. Methods. We compared the efficacy of coagulated autologous BMA and ABG for the repair of ulnar defects in New Zealand White rabbits. Segmental defects (14 mm) were filled with autologous clotted BM or morcellized autograft, and healing was assessed four and 12 weeks postoperatively. Harvested ulnas were subjected to radiological, micro-CT, histological, and mechanical analyses. Results. Comparable results were obtained with autologous BMA clot and ABG, except for the quantification of new bone by micro-CT. Significantly more bone was found in the ABG-treated ulnar defects than in those treated with autologous BMA clot. This is possibly due to the remnants of necrotic autograft fragments that persisted within the healing defects at week 12 post-surgery. Conclusion. As similar treatment outcomes were achieved by the two strategies, the preferred treatment would be one that is associated with a lower risk of complications. Hence, these results demonstrate that coagulated BMA can be considered as an alternative autogenous therapy for long bone healing. Cite this article: Z. X. H. Lim, B. Rai, T. C. Tan, A. K. Ramruttun, J. H. Hui, V. Nurcombe, S. H. Teoh, S. M. Cool. Autologous bone marrow clot as an alternative to autograft for bone defect healing. Bone Joint Res 2019;8:107–117. DOI: 10.1302/2046-3758.83.BJR-2018-0096.R1

This study was done to determine the effectiveness of percutaneous autologous bone marrow injection in fracture healing and to determine if centrifuged bone marrow is more effective in bone healing as compared to uncentrifuged marrow. This is a randomized interventional trial of 106 patients who had bone marrow injection. The study was done in 2 parts. In the first part, 51 patients were divided into three groups – a) Fresh fractures,(within 6 weeks of injury) b) Delayed union – (8 to 12 weeks after injury) c) Non union – more than 16 weeks after injury. All patients in the first part of the study underwent percutaneous autologous bone marrow injection and were followed up at 6,8,10 and 12 weeks and every 4th week thereafter. Forty seven out of 51 patients united. The second part of the study was done to compare centrifuged and uncentrifuged bone marrow injections. Fifty five patients having either tibial or femoral fractures were divided into two groups, centrifuged and uncentri-fuged and appropriate marrow injection was done. All patients were followed up every 6 weeks till 36 weeks. 48 patients out of 55 united. Equal number of patients united in the centrifuged and uncentrifuged group. We conclude that percutaneous autologous bone marrow injection is a simple and effective tool which can be used for fracture healing and centrifugation of bone marrow yields no added advantage in bone healing

Purpose of the study: Nonunion, which is a biological failure, requires revision, usually an aggressive operation. Haematopoietic bone marrow contains colony forming unit fibroblasts (CFU-F) which could favour bone healing. The purpose of this work was to determine whether a minimally invasive procedure, injection of CFU-F into the nonunion space, could favour bone healing without further procedure. Material and methods: Our series included 43 patients: 36 male and 7 female, mean age 39.9 years. Forty-seven atrophic and aseptic nonunions of long bones were treated with percutaneous injection of concentrated autologous bone marrow: 27 tibias, 17 femurs, 3 humeri. Bone marrow was harvested from the posterior iliac crests (346 ml) then centrifuged to keep the leuko-platelet fraction (78 ml). This concentrate was injection into the nonunion space under radioscopic guidance. Efficacy was assessed on the basis of clinical criteria (complete pain-free weight-bearing, absence of contention, absence of mobility) and on radiographic criteria (healing of 3/4 corticals). Results: Thirty nonunions healed: 19 tibias (70%, 11 femurs (65%) and 0 humerus. Mean time to healing was 5.9 months (2.4–15.6). Factors of poor prognosis were: smoking, alcohol, diabetes, corticosteroids, radiotherapy, history of sepsis (p=0.01). Early grafting increased the chances of success (p=0.04). Age, initial skin opening, type of fixation did not have a significant impact on healing. The number of CFU-F had an effect on the rate of healing. Discussion: This technique is effective for the treatment of nonunion of the lower limb, allowing bone healing in two thirds of the cases with a minimally aggressive procedure. The method is easy to perform but requires a rigorous technique for the different phases of puncture, concentration and reinjection. Nonunions unresponsive to conventional methods, and thus corresponding to multifactorial problems, probably constitute the limitation of this method. Cell expansion or differentiation techniques could be helpful in improving the success rate but at the present time the osteogenic potential of these cells remains to be elucidated as a function of their stage of maturation. Conclusion: Percutaneous grafts of concentrated autologous bone marrow can be a useful contribution to the therapeutic armamentarium for nonunion. Morbidity is low and the method does not compromise future options. It can be proposed as a first-intention solution for the treatment of long bone nonunion

INTRODUCTION. There is no effective therapy available today that alters the pathobiologic course of osteoarthritis. Recent advances have shown Mesenchymal stem cells to be a potential disease modifying treatment. Considering the tissue differentiation property and vast paracrine effects of MSCs we proposed the present study to find out the safety and efficacy of Mesenchymal stem cells in osteoarthritis of knee joint. METHODS. 12 patients with grade 1and2 bilateral osteoarthritis knee (Ahlbacks radiological grading) were selected. 8–10 ml of bone marrow was aspirated under strict aseptic precautions from the iliac spine. After the stem cell culture and expansion for 4–6 weeks the MSC suspension in 10xPBS was injected directly into the 24 knees by lateral approach. The outcome was evaluated by modified VAS score, WOMAC score, KOOS and MRI measurement of knee articular cartilage integrity by the modified WORMS score. RESULTS. Statistically significant improvement in VAS score, total WOMAC score and total KOOS score was observed from pre injection to 1st follow up at 6 weeks, 2nd follow up at 6 months and final follow up of mean 26.7 months. There was also a significant improvement from 1st follow up to 2nd and final follow up. The modified WORMS score showed a statistically significant decrease of 1.49 %. CONCLUSION. Intra-articular injection of autologous bone marrow derived culture-expanded MSCs can be considered a potential treatment of early osteoarthritis knee which relieves pain, stiffness, improves physical functions, and improves the articular cartilage integrity

Aim: To assess the efþcacy of percutaneous reaming of simple bone cysts followed by administration of a mixture of autologous bone marrow combined with demineralized bone matrix. Material-methods: 10 patients (7 boys aged 10 years on average and 3 girls aged 12 years on average) with a bone cyst (3 patients at the femur, and 7 at the humerus), were treated with the same surgical technique. The diagnosis was based exclusively on imaging methods (X-ray, CT, MRI) and no biopsy was performed. Under general analgesia and image intensi-þer control the cystic cavity was aspirated. Should ßuid was encountered then a mixture of bone marrow and demineralized bone matrix (DBM) was injected after thorough reaming of the canal proximally and distally. None of the patients required overnight hospital stay. The limb was protected till the patient became asymptomatic. Results: The average follow-up time was 24 months (9–29 months). No perioperative complications were noted. All patients were asymptomatic at the last examination, with normal limb movement. All bone cysts were classiþed from an independent observer, according to the Neer classiþcation, as type I and II. Conclusion: Percutaneous administration of DBM combined with autologous bone marrow after restoring the continuity of the medullary canal with reaming is a simple surgical technique requiring no hospitalization and a short period of immobilization while the clinical and radiological outcome is excellent

Purpose: The gravity of osteonecrosis in patients with sickle cell anaemia is well known, but the spontaneous course of grade I and II necrosis is not. The first MRI studies performed in these patients were made in 1985. This study compared the spontaneous course in 45 cases of grade I and II necrosis diagnosed between 1985 and 1990 with that in 43 cases of hip necrosis with the same grades I and II diagnosed between 1990 and 1995 in adult patients with sickle cell anaemia treated by medullary drilling with autologous bone marrow grafts. Material and methods: The 45 cases of necrosis followed were diagnosed between 1985 and 1990. These patients did not undergo conservative treatment until the sphericity of the femoral head was lost. They were followed clinically and radiographically up through 2000. The second group of 43 cases of hip necrosis were diagnosed between 1990 and 1995. These patients were treated by meduallary drilling with an autologous bone marrow graft. The bone marrow as harvested from the iliac crests, concentrated and reinjected in the osteonecrotic area. The patients were followed clinically and radiographically until 2000. All patients had an x-ray of the hip (AP and lateral views) at last follow-up. As the follow-up was different for the two groups, comparisons were made using the survival curves; all patients were followed for at least five years. Results: In group I where the clinical course was spontaneous, the spherical shape of the head was lost in 100% of the patients at five years (30% at one year, 60% at two years and 100% at five years), leading to surgery for 80%, usually with prosthesis implantation. In group II where the patients were treated by drilling and autologous bone marrow transplantation, two patients (5%) lost femoral head sphericity at five years. Ten percent of the patients (4 patients) had lost the femoral head sphericity at the current mean follow-up of eight years (minimum five, maximum ten) and required reoperation for prosthesis implantation. MRI and CT imaging in the non-reoperated patients demonstrated a spherical head and remodelling or disappearance of the osteonecrosis at five years. Discussion and conclusion: The spontaneous course of necrosis in adults with sickle cell anaemia is unfavourable after five years. This spontaneous course can be modified (at least the rate of progression) by drilling associated with autologous bone marrow transplantation, if it is performed early enough

Background: Traumatic brachial plexus (BP) injuries may cause loss of elbow flexion. After nerve surgery active elbow flexion often remains insufficient. Muscle strength improvement via cell therapy would be a potential option and could avoid muscle transfer surgery. The primary objective of this pilot study was to assess the safety and feasibility of autologous bone marrow (BM)-derived mononuclear cell (MNC) injection in partly denervated m. biceps brachii of BP patients. Secondary, this study has focused on the myogenic potential of BM-derived MNC by assessing the morphological and functional improvement of the biceps. Methods: Nine adult BP patients with insufficient force recovery of elbow flexion were included. Three escalating doses (0.9, 4 and 8 * 108) of MNCs were injected in the m. biceps brachii (group A, B and C). In group A, BM was aspirated under local anesthesia (60 ml). In group B and C, BM was aspirated in combination with a muscle tendon transfer (Steindler flexorplasty) under general anesthesia (350 and 650 ml respectively). A muscle biopsy was performed before and 3 months after transplantation. Furthermore, quantitative needle EMG, CT-scan and clinical function was obtained at pre-transplantation and at 3 and 6 months follow-up. The EMG and CT-scan data were blinded during analysis. Results: No negative side effects were observed. Biopsies showed an increase of 80% in myofiber diameter (P = 0.007), 51% in satellite cells (P = 0.045), 83% in capillary to myofiber ratio (P < 0.001) and a decrease of 51% in fibrosis (P = 0.012). Histological changes were most apparent in group B with an increase of 126% in myofiber diameter (P = 0.019), 100% in capillary to myofiber ratio (P = 0.027), and a decrease of 70% in fibrosis (P = 0.023). EMG demonstrated an increase of 36% in amplitude (P = 0.045), 29% in duration (P = 0.005) and 29% in number of phases of the motor unit potentials (P = 0.002). CT-scan analysis showed a decrease of 48% in mean muscle density (P = 0.009). Discussion: This study shows that BM-derived MNC transplantation in a partly denervated muscle of traumatic PB patients is safe and feasible. Muscle improvement was observed in muscle biopsies. Furthermore, changes in EMGs and CT-scans were also suggestive for muscle regeneration. The BM dose applied in group B could represent the optimal dose to enhance partly denervated muscles. The results of the present study require confirmation in a placebo-controlled study

Articular cartilage repair remains a challenge in orthopedic surgery, as none of the current clinical therapies can regenerate the functional hyaline cartilage tissue. In this study, we proposed a one-step surgery strategy that uses autologous bone marrow mesenchymal stem cells (MSCs) embedded in type II collagen (Col-II) gels to repair the full thickness chondral defects in minipig models. Briefly, 8 mm full thickness chondral defects were created in both knees separately, one knee received Col-II + MSCs transplantation, while the untreated knee served as control. At 1, 3 and 6 months postoperatively, the animals were sacrificed, regenerated tissue was evaluated by magnetic resonance imaging, macro- and microscopic observation, and histological analysis. Results showed that regenerated tissue in Col-II + MSCs transplantation group exhibited significantly better structure compared with that in control group, in terms of cell distribution, smoothness of surface, adjacent tissue integration, Col-II content, structure of calcified layer and subchondral bone. With the regeneration of hyaline-like cartilage tissue, this one step strategy has the potential to be translated into clinical application

Purpose of the study: Drilling along yields disappointing results for osteonecrosis of the femoral head due to the high failure rate despite prolonged rest and also because of the risk of fracture. To prevent these problems, we have developed a new drilling technique which was evaluated prospectively. Material and methods: The procedure performed percutaneously uses a lateral cortical orifice measuring 5mm, non-concentrated autologous bone marrow was injected after drilling. Osteoinductive protein (BMP7) was associated in random fashion (groups BMP+ and BMP−). Ficat stage 1 and 2 necrosis was included. Outcome was the rate or revision for prosthesis. Results: Forty hips (36 patients) were included and assessed at mean four years (range 2–6). The necrosis was related to: alcoholism (n=5), cortisone (n=25), barotraumas (n=2), metabolic disease (n=4), idiopathic condition (n=4). Group BMP- (drilling+bone marrow) included 24 hips and group BMP+ (drilling+bone marrow+BMP7) 16 hips. The groups were comparable regarding necrosis stage (15% stage 3, 65% stage 2, 20% stage 1) and mean Koo index (27 BMP+ vs 34 BMP-; NS). There were no infections and no fractures despite immediate and complete weight-bearing. The revision rate for prosthesis was higher in the BMP- group (67%) than in the BMP+ group (43%) but the difference did not reach significance (p=0.10). The failure rate was not affected by the severity of the necrosis in the BMP+ group: all stage 3 hips were revised in the BMP- group versus none in the BMP+ group. The only variable predictive of revision for prosthesis was the Koo index (p=0.02). Discussion: Adjunction of BMP did not improve significantly the success rate of drilling with bone marrow adjunction but adding BMP appeared to limit the unfavourable impact of server necrosis observed in the BMP- group. To reach a statistical power of 80%, 40 cases would be needed in each arm. This threshold has not yet been reached. It can be noted however that the proposed method does ensures early weight bearing without the risk of complications. Similarly, since it is a percutaneous procedure, later arthroplasty is not compromised. The principle confounding factor, the richness of the bone marrow, was not assessed, motivating a new randomized trial with measurement of CFU-F

Tissue engineering can be deþned as any effort to create or induce the formation of a speciþc tissue in a speciþc location through the selection and manipulation of cells, matrices, and biologic stimuli. The biologic concepts and the biochemical and biophysical principles on which these efforts are based have become a rapidly evolving þeld of biomedical research. More importantly, tissue engineering is becoming a clinical reality in the practice of orthopaedic surgery, providing patients and physicians with an expanding set of practical tools for effective therapy. The efþcacy of all current clinical tools depends entirely on the cells in the grafted site, particularly the small subset of stem cells and progenitor cells that are capable of generating new tissue. The current author reviews a series of key biologic concepts related to the rational design and selection of cells in contemporary bone grafting and tissue engineering efforts. The functional paradigms of stem cell biology are reviewed and sources for autogenous stem cells for connective tissues are discussed. Finally a technique to obtain stem cells for the treatment of non unions is described.

We included 48 patients: 38 cases of post-traumatic non union (12 of them with infection); 4 non unions following arthrodesis (3 knees, 1 tibiotarsal); 4 cases with Illizarov technique; 2 patients with congenital abnormalities. The source of bone marrow was the iliac crest. The marrow was reduced in volume (50 ml) in order to increase the concentration in stem cells by elimination of erythrocytes and polynuclear cells. The number of nucleated cells was counted in the marrow transplanted and the þbroblast colony forming cells (CFU-F) and the osteoblast colony forming cells (CFU-Ost) were cloned to appreciate the number and the activity of progenitor in the marrow transplanted.

Tissue engineering can be defined as any effort to create or induce the formation of a specific tissue in a specific location through the selection and manipulation of cells, matrices, and biologic stimuli. The biologic concepts and the biochemical and biophysical principles on which these efforts are based have become a rapidly evolving field of biomedical research. More importantly, tissue engineering is becoming a clinical reality in the practice of orthopaedic surgery, providing patients and physicians with an expanding set of practical tools for effective therapy. The efficacy of all current clinical tools depends entirely on the cells in the grafted site, particularly the small subset of stem cells and progenitor cells that are capable of generating new tissue. The current author reviews a series of key biologic concepts related to the rational design and selection of cells in contemporary bone grafting and tissue engineering efforts. The functional paradigms of stem cell biology are reviewed and sources for autogenous stem cells for connective tissues are discussed. Finally a technique to obtain stem cells for the treatment of non unions is described.

We included 48 patients: 38 cases of posttraumatic non union (12 of them with infection); 4 non unions following arthrodesis (3 knees, 1 tibiotarsal); 4 cases with Illizarov technique; 2 patients with congenital abnormalities. The source of bone marrow was the iliac crest.

The marrow was reduced in volume (50 ml) in order to increase the concentration in stem cells by elimination of erythrocytes and polynuclear cells. The number of nucleated cells was counted in the marrow transplanted and the fibroblast colony forming cells (CFU-F) and the osteoblast colony forming cells (CFU-Ost) were cloned to appreciate the number and the activity of progenitor in the marrow transplanted.

We present our clinical experience in treating atrophic non-union of long bones by injecting, percutaneously, autologous bone marrow aspirate concentrated as a source of progenitors stem cells

Bone marrow aspirated from the iliac crest contains progenitor cells that can be used to obtain bone-healing of non-union. However, its efficacy appears to be related to the number and concentration of progenitors in the graft. The last three-year period, 11 patients (8 men-3 women) with established atrophic non-union were treated in our department. In all cases, the gap between the fragments was smaller than 5 mm. A constant volume of 60+60 ml of marrow were aspirated from both iliac crests and centrifuged for 15 minutes aiming at the increase of concentration of progenitor-mononucleotide cells. An average volume of 20 ml (+/− 2) concentrated bone marrow was injected percutaneously, under C-arm, at the site of non-union. The graft contained an average of 272.64 x 10(6)/ ml mononucleotide cells. The evaluation of treatment was based on the clinical and radiological findings after 3, 6, 9 and 12 months. However, prior to administration of bone marrow stem cells, there was no case with evidence of ongoing deep sepsis.

Bone union was obtained in 10 out of 11 patients (full weight bearing, callus formation in 3 out of 4 cortices). In one case a second operation was needed due to impaired indications of treatment. However, in all cases, there were no signs of local or systematic complications.

Percutaneous concentrated bone marrow grafting is an efficient and safe method, for treating atrophic non-unions, with a minimal invasion technique. Contraindications for the above technique are a gap larger than 5 mm and a preexisting angular and axial deformity.

Once damaged, articular cartilage has limited capacity for self-repair due to their avascular and acellular nature. Tissue engineering approaches using cultured chondrocytes and biomaterials as scaffoldings hold promises for repairing cartilage defects. However, the source of articular chondrocytes is limited and the chon-drocytes may de-differentiate when cultured for a prolonged period. Bone marrow derived mesenchymal stem cells (BMSCs) have multi-differentiation potentials and autologous BMSCs are easy to obtain and culture with no/little immunological reaction when re-implanted.

24 NZW rabbits were used. Rabbit autologous BMSCs were obtained through marrow aspirations and expanded in culture under the chondrogenic induction media (DMEM, 10% FCS, plus 10ng/ml TGF-β1) for 3 weeks. A full-thickness articular cartilage defect (3 mm in diameter and 3 mm in depth) was created on both medial condyles in the rabbit. For experimental group (16 joints), the defects were filled immediately with alginate capsules containing autologous chondrogenic cells (8.5 x 104); for the control groups, the defects were filled with either alginate capsules alone (16 joints) or left untreated (16 joints). All the animals were terminated at 6 and 12 weeks after surgery and the cartilage samples were harvested for histology, immunochemistry and in situ hybridization examinations.

For histology, in the experimental group the defects were filled with immature hyaline-like cartilaginous tissues at 6 weeks; by 12 weeks the newly formed cartilage showing signs of remodeling and integrating into the surrounding articular cartilage. The expression of type II collagen in the newly formed cartilaginous tissues was confirmed by immunohistochemistry and by in situ hybridization methods. In the control groups, the defects were mainly filled with fibrous tissues in all the animals at the two time points examined. We have used Wakitani cartilage grading system for semi-quantitative histological evaluation. Significant lower scores (with superior histology) were found in the experimental group comparing to the two control groups.

Our results confirmed that full-thickness articular cartilage defects can be repaired by chondrogenically differentiated autologous BMSCs seeded into alginate capsules. Further studies are ongoing to explore the long term outcome of this treatment approach as well as using new scaffolds for cartilage tissue engineering.

Objectives

Traumatic brachial plexus injury causes severe functional impairment of the arm. Elbow flexion is often affected. Nerve surgery or tendon transfers provide the only means to obtain improved elbow flexion. Unfortunately, the functionality of the arm often remains insufficient. Stem cell therapy could potentially improve muscle strength and avoid muscle-tendon transfer. This pilot study assesses the safety and regenerative potential of autologous bone marrow-derived mononuclear cell injection in partially denervated biceps.

Aims: The aim of the study is to evaluate the clinical application in veterinary orthopedics of the bone stromal cells loaded on three-dimensional resorbable osteogenic scaffolds.

Methods: On the basis of the results obtained after an experimental study on 54 adult sheep (data in process), the Authors have carried out a clinical study on 9 dogs of different breed, age,sized with the different orthopaedic lesion associated to large bone defects (from 2 to 4,8 cm) (bone cyst of glenoid rime, non-union of the tibia and of the femur, osteosarcoma of the radio and the proximal humerus, lenghtening of the radius, bone large defect of the distal radius).With the local anesthesia performed with 2% lidocaine the marrow samples were collected from the iliac crest two hours before the surgery. The bone marrow nucleated cells were then isolated from the bone marrow by gradient centrifugation and loaded on the scaffold on biomaterial, which size and shape was defined before performing the surgery. The cells separated were added with some drops of thrombin. The material used for the study was Osteostim Skelite resorbable bone graft substitute (manufactured by Millenium Biologic Inc-.Canada) which chemical composition and size facilitates the ingrowth of bone.

X-ray exams were performed immediately after the surgery. Clinical, ultrasound and x-ray exams were performed after 20 days and then every month.

Results: 7 of 9 treated dogs have shown very good clinical and x-ray results.

Conclusions: One of the objective of the study was to use the fresh bone stromal cells (BMSCs) in clinical applications in large bone defects in the dog. The advantages of using the cells are: they don’t need to be expanded in vitro, they preserve their osteogenic potential to form bone and promote the proper integration of the implant with bone and lastly, the technique is easier and the costs are lower. We use a fully resorbable biomaterial with BMSCs to obtain a complete substitution of large bone defects since the final goal is the complete substitution of the biomaterial scaffold with new formed bone. Persistency of biomaterial, in fact, limits the complete integration of the two (old and new) interfaces and may represent a weak spot in functionality when tensions and loads are fully applied to the bone, in spite of a satisfactory surgical recovery.

The reconstruction of large bone segments is a major goal in orthopaedic surgery. Autologous cancellous bone is recognized as the most biologically active graft material, but autologous bone harvest is associated with significant morbidity and founds its limit in the available quantity. Biomaterials or allografts do not encounter these limitations, but have no osteogenic and limited osteinductive potential. In order to enhance tissue regeneration and healing we have tried to obtain a graft with osteconductive, inductive and osteogenic properties. The day before operation 350 cc of autologous blood is donated from the patient and centrifuged to obtain a platelet-rich plasma. Bone marrow is aspirated from the posterior iliac crests with the patient under spinal anaesthesia and is processed to increase its stem cell content. The structural scaffold used is morcellized cancellous bone provided from our Bone Bank. At operation bone is mixed with bone marrow buffy coat and Platelet Rich Plasma in a sterile glass becker with addition of CaCl2 till clot formation to produce a gel-like component that is handled easily. We have utilized this technique from November 2000 till January 2004 for 68 patients: 41 of these patients required healing of large bone defects: 22 males and 19 females. Fresh bone marrow alone was used for a percutaneous injection in 11 cases; open surgery with autologous growth factors, bone marrow buffy coat and allograft was used in 30 patients. The radiological and clinical results showed early healing of the defects treated with this technique and no complications related to the procedure at an average follow up of 23 months (3–40).

Aims

The aim of this study is to evaluate the surgical treatment with the best healing rate for patients with proximal femoral unicameral bone cysts (UBCs) after initial surgery, and to determine which procedure has the lowest adverse event burden during follow-up.

Large bone defect repair has always presented a difficult treatment problem. Marrow-derived osteogenic progenitor cells combined with hydroxyapatite (HA) were used for segmental bone reconstruction. The validity of this model has been shown for the repair of bone defects of critical size in large animal models. We used this cell-based therapeutic approach to treat three patients with large bone defects.

The patients were 41, 22 and 16 years old and had large tibial, ulnar and humeral diaphyseal gaps that ranged in size from 3.0 to 28.3 cm³. Marrow samples were harvested from the iliac crest and osteogenic progenitors isolated and expanded “ex vivo”. The expanded cells were then combined with a highly macroporous bioceramic scaffold whose size and shape reflected each individual bony defect. The cell/bioceramic composites were implanted at the lesion sites. External fixation was used to stabilise the grafts.

At present all patients have been followed up for 4–5 years. Already after the first month after surgery an initial integration at the bone/implant interface was evident. Bone formation in the implants, assessed by X-ray, progressed steadily in the follow-up period. Two patients achieved full functional recovery at 6 months after surgery, one patient at 12 months after surgery. The present report shows that large segmental bone reconstruction can be achieved in humans using osteoprogenitor cells. This technique can be improved by a more biodegradable and more biomechanically resistant scaffold use.