The Declining Number of Finger Replantations in Germany.

INTRODUCTION: Data from the United States have shown that finger replantation numbers have declined significantly in recent years. It is unclear whether this is due to a decrease in amputation injuries or other reasons. MATERIALS METHODS: Since 2005, all German hospitals have been required to produce structured quality reports. Based on these reports, we analyzed finger and hand replantation development and the incidence of amputation injuries between 2006 and 2018. RESULTS: Replantations decreased by 30%, whereas amputation injuries increased slightly. In 2018, only 17 centers carried out more than 10 replantations. Most hospitals had replanted less than 4 times a year. The majority of residents participated in fewer than 1 replantation per year. Most specialists performed fewer than 1 replantation per year. The reasons for the decline in replantation remain speculative. CONCLUSIONS: However, a reduction in amputation injuries was not observed. A change in medical indications, technical skills, and economic motivations needs to be considered. A further loss of specialized technical skills and experience with replantations might be a future consequence of this trend.

Donor Defect Morbidity of Intrinsic Flaps in the Posttraumatized Hand.

INTRODUCTION: There are many types of intrinsic flaps to cover wound defects on the hand, which have been well described in scientific literature. However, the donor sites are often neglected in such studies. Therefore, we aimed to evaluate donor site morbidity for homodigital island flaps, cross-finger flaps, Foucher's pedicle flaps, and flaps of the dorsal metacarpal artery system (DMCA). MATERIALS AND METHODS: A total of 106 intrinsic flap procedures were performed on 106 patients (16 women, 90 men). The donor sites were retrospectively followed up after an average of 3.4 years by a questionnaire, a Disability of the Arm, Shoulder and Hand score, and clinical examination. Donor sites of different flap types were compared for aesthetic outcome, trophic level, and sensation, including 2-point discrimination, temperature, sharp/dull discrimination, the Semmes-Weinstein monofilament test, pain (visual analog scale), and functionality. RESULTS: In general, primarily closed donor sites showed more favorable results than did grafted donor sites. Satisfaction among patients regarding aesthetics of the donor site was highest in patients who had received homodigital island flaps. Grip strength and pain at the operated hand were very heterogeneous and rather influenced by the primary trauma than the type of flap. Homodigital island flap donor sites demonstrated the best results for 2-point discrimination and sharp/dull discrimination, and those for DMCA flaps in the Semes-Weinstein test. CONCLUSIONS: Overall, intrinsic flaps demonstrated low donor site morbidity with reliable coverage of the defects. Of these, the DMCA (especially after primary closure) and homodigital island flaps seemed to produce the best donor site results.

Bacterial bioburden of wounds: influence of debridement and negative-pressure wound therapy (NPWT).

OBJECTIVE: To clarify the role of microbiological swabs in surgical decision-making, we investigated the effect of negative-pressure wound therapy (NPWT) and serial surgical debridement on bacterial bioburden in hard-to-heal wounds and ultimately correlated them with the success of surgical closure. METHOD: All patients were treated with surgical debridement, jet lavage and NPWT before their wounds were finally closed. The treatment effect was assessed by correlating microbiological swabs obtained immediately after intervention with those obtained after removal of the dressings during the following surgical procedures. The result of the last microbiological swab taken before definitive surgical closure was correlated with the requirement for revision surgery. RESULTS: We included the results of 704 microbiological swabs from 97 patients in 110 wound localisations in this monocentric, retrospective study. NPWT did not improve bacterial bioburden in 77% of cases and the duration of NPWT did not affect the result. Furthermore, no significant effect of NPWT could be found for either anaerobic (p=0.96) or aerobic bacteria (p=0.43). In contrast, surgical debridement decreased bacterial load in approximately 60% of cases. If sterile wound swabs could be obtained at all, it was during the first four surgical debridements in 60% of patients; after that only 10% became sterile. CONCLUSIONS: Sterile microbiological wound swabs before surgical closure were associated with lower rates of revision surgery, while low or medium bacterial loads did not increase revision rates.

The Usage of Pedicled or Free Muscle Flaps Represents a Beneficial Approach for Periprosthetic Infection After Knee Arthroplasty.

INTRODUCTION: Periprosthetic joint infection (PJI) is a severe complication after a total knee replacement that is primarily associated with soft tissue defects. Finding an appropriate therapy for PJI is a major challenge because of the lack of guidelines and research comparing treatment options. METHODS: In this study, we retrospectively compared 78 patients who had a knee prosthetic infection within a mean follow-up period of 24 months. Group A received a soft tissue coverage in addition to orthopedic surgical therapy with or without a component replacement (CR) of the prosthesis. Group B received the same orthopedic treatment without plastic surgery for soft tissue coverage. RESULTS: Only 21% of the patients in group A received a CR compared with 70% in group B (P = 0.0001). In group A, 83% did not have a recurrent infection, and in group B, 57% of the patients had no further infection and regained joint function (P = 0.0376). In group A, only 15% of the patients who received a CR had a significant complication within the follow-up period of 2 years, whereas in group B, 75% of patients exhibiting a major complication (P = 0.0048*). CONCLUSIONS: Soft tissue coverage improves the outcome after PJI of the knee with soft tissue defects. Patients who simultaneously needed plastic surgery for defect coverage and orthopedic surgery for CR had the lowest number of complications overall. Based on the results of this study, a therapy algorithm could be identified considering the soft tissue defect grade leading to the lowest major complication rates and maximizing the outcome of knee prosthesis infection therapies.

Microsurgeons do better--tactile training might prevent the age-dependent decline of the sensibility of the hand.

Recent data demonstrate that the normal sensibility of the hand seems to be age-dependent with the best values in the third decade and a consecutive deterioration afterwards. However, it is not clear if long-term tactile training might prevent this age-dependent decline. We evaluated sensibility of the hand in 125 surgeons aged between 26 and 75 years who perform microsurgical operations, thereby undergoing regular tactile training. We examined sensibility of the radial digital nerve of the index finger (N3) and the ulnar digital nerve of the small finger (N10) using static and moving two-point discrimination (2PD) tests and compared the results to 154 age-matched individuals without specific long-term tactile training. We found significantly lower static and moving 2PD values for the sixth, seventh, and eighth decade of life in the microsurgery group compared to the control group (p < 0.05). This study demonstrates that long-term tactile training might prevent the known age-dependent decline of the sensibility of the hand.

Impact of Timing of Admission and Microvascular Reconstruction on Free Flap Success Rates in Traumatic Upper Extremity Defects.

BACKGROUND: Despite a growing body of knowledge, the timing of microsurgical reconstruction for the upper extremity remains a controversial topic. Most of the available literature deals with lower extremity reconstruction and the few reports on microsurgical reconstruction of the upper extremity are mostly concerned with infection rates and rarely consider thrombosis and changes in coagulation parameters. METHODS: We performed a retrospective review of all free flaps performed for upper extremity reconstruction at our institution from 2000 to 2010. Only acute, isolated traumatic defects of the upper extremity requiring a free flap for reconstruction were included in this study. A review of medical records was performed to assess, among others, comorbidities, timing of reconstruction, and platelet levels. RESULTS: A total of 41 patients were included in this study, 70% of whom were male. Mean age at the time of surgery was 40.8 ± 15.4 years. Patients who were directly referred to our hospital underwent reconstruction significantly faster than those who were transferred secondarily (p = 0.0001). The number of surgical revisions as well as the flap loss rate was higher in patients undergoing reconstruction more than 1 week after trauma (p = 0.09 and 0.033, respectively). A significantly higher platelet count was seen in the patients undergoing delayed reconstruction (p = 0.002). CONCLUSION: In our study, early microsurgical reconstruction of the upper extremity yielded better results in terms of lower rates of surgical revisions and flap loss. This might be partly because of a trauma-induced thrombocythemia, with a maximum level of platelets in the 2nd week post trauma. We, therefore, advocate a timely coverage of these defects along with an anticoagulatory regimen including some form of platelet inhibition.

The normal sensibility of the hand declines with age--a proclamation for the use of delta two-point discrimination values for sensibility assessment after nerve reconstruction.

The scores used to evaluate sensibility after digital nerve reconstruction do not take the patient's age into consideration, although there is evidence that the outcome after digital nerve reconstruction is age-dependent. However, it is not clear if the normal sensibility of the hand is also age-dependent, as the existing studies have major limitations. We evaluated the normal sensibility of the hand in 232 patients using static and moving two-point discrimination (2PD) tests and the Semmes-Weinstein-monofilament test. We found the climax of sensibility in the third decade with age-dependent deterioration afterwards in all three tests. Mean 2PD values of the radial digital nerve of the index finger (N3) showed to be significantly lower than values of the ulnar digital nerve of the small finger (N10). To overcome shortcomings of classification systems that do not consider the patient's age and inter-individual differences, we suggest using the difference of the static 2PD values of the injured to the uninjured contralateral nerve (delta 2PD) for assessment of sensibility after digital nerve reconstruction.

Is nerve regeneration after reconstruction with collagen nerve conduits terminated after 12 months? the long-term follow-up of two prospective clinical studies.

BACKGROUND: Long-term follow-up data of digital nerve reconstructions with nerve conduits are limited. Furthermore, it is not known whether nerve regeneration after tubulization is terminated after 12 months, or whether improvement can be expected after this period of time. Therefore, we present the long-term follow-up of two prospective clinical trials. PATIENTS AND METHODS: We invited 45 patients who were enrolled in two prospective clinical trials for long-term follow-up. All patients underwent digital nerve reconstruction with conduits made from bovine collagen I due to a gap length of < 26 mm. Sensibility was assessed using static and moving two-point discrimination and monofilament testing. Follow-up data of 1 week, 3, 6, and 12 months, and the current examination were available. Improvement of sensibility was investigated by comparison of the American Society for Surgery of the Hand classification score at 12-month follow-up with the score raised at current examination. RESULTS: We examined 20 reconstructed nerves in 16 patients with a mean follow-up of 58.1 months (range, 29.3-93.3 months). We found an improved sensibility at current follow-up compared with the 12-month follow-up in 13 cases. Three cases had the same values whereas four cases had worsened sensibility. Improvement of sensibility was associated with a significantly shorter nerve gap length with significantly better results if the gap length was < 10 mm. CONCLUSION: Our results provide evidence that the long-term recovery of sensibility after digital nerve tubulization depends on the nerve gap length with better results in those < 10 mm. Nerve regeneration after tubulization seems not to be terminated after 12 months.

[Selective Neurectomy in Spastic Paralysis of the Upper Extremity]. / Die hyperselektive Neurektomie bei spastischen Lähmungen der oberen Extremität.

Selective neurectomy refers to the targeted transection of motor nerve fibres at their entry into the muscle in order to reduce the increased muscle tone in cases of spastic paralysis. This procedure has regained popularity in recent years, especially in the upper extremity. First and foremost, it requires an exact knowledge of the topographical anatomy of muscle innervation. To be able to control the extent and localisation of the denervation, the terminal nerve branches must be visualized precisely during the procedure. For a meaningful reduction of muscle tone, 2/3 to 4/5 of nerve fibres must be resected. This article presents the historical development, principles and operative details of this technique as well as clinical results.

[Concomitant injuries of the wrist, distal ulna and distal radioulnar joint in distal radius fractures : Primary operative cotreatment vs. healing with no additional treatment]. / Begleitende Verletzungen von Karpus, distaler Elle und distalem Radioulnargelenk bei distaler Radiusfraktur : Primäre operative Mitversorgung vs. Heilung ohne zusätzliche Therapie.

Distal radius fractures are the most common fractures in adults and account for one quarter of all fractures, with increasing incidence. The number of patients and the requirement of an exact treatment are high. Continuous developments in diagnostic and operative possibilities enable in many cases a high-quality treatment with good clinical outcome; however, radius fractures rarely occur alone but in combination with additional fractures or ligamentous injuries. The frequency and extent of these injuries are not linked to the complexity of the primary injury. The aim is to recognize and correctly diagnose potential concomitant injuries. Many injuries do not need immediate treatment but heal without additional treatment after the radius has been treated. It is important to recognize those injuries which can cause severe complications if untreated; however, exactly this is often difficult. In many cases there is still no consensus if and how concomitant injuries should be treated. This article highlights the most frequent concomitant injuries in distal radius fractures with the possible advantages and disadvantages of cotreatment in order to facilitate decision making.

Median neuropathy in malunited fractures of the distal radius.

PURPOSE: Irritation of the median nerve is a well-characterized complication after acute fractures of the distal radius, but there is limited literature on median neuropathy in malunited fractures. The aims of our prospective study were to estimate the prevalence of the median neuropathy, explore the relationship between radiographic findings and the condition, and investigate whether corrective osteotomy without carpal tunnel release was a sufficient treatment. METHODS: Thirty consecutive patients, who were referred to us for treatment of symptomatic distal radial malunion, underwent nerve conduction studies of both wrists by one board-certified neurologist under standardized conditions. Test results were correlated with conventional radiographic parameters (radial tilt, radial inclination, palmar shift, ulnar variance, radiolunate and capitolunate angle) and computer tomography (CT) based measurements of the cross-sectional area of the carpal tunnel. After corrective osteotomy without carpal tunnel release, 10 of 13 patients with unilateral preoperative median neuropathy agreed to an electrodiagnostic re-examination by the same neurologist. RESULTS: Nineteen patients demonstrated abnormal test results, but only seven patients complained about paresthesias of median-innervated fingers. There was no correlation between median neuropathy and conventional radiographic parameters. Surprisingly, the cross-sectional area of the carpal canal was significantly greater for patients with median neuropathy. Symptoms resolved in all patients after corrective osteotomy. Postoperatively, six of ten patients demonstrated improved nerve conduction studies, although only four patients demonstrated normal test results. DISCUSSION: There is a high rate of subclinical median neuropathy in malunited distal radial fractures that cannot be predicted by conventional radiographic parameters. Corrective osteotomy without carpal tunnel release is a sufficient treatment for neuropathy in malunited distal radius fractures.

Free tissue transfer in patients with severe peripheral arterial disease: functional outcome in reconstruction of chronic lower extremity defects.

Chronic wounds of the lower extremity are difficult to treat, especially in patients with peripheral arterial disease (PAD). This patient population frequently suffers from multiple comorbidities, which further impairs wound healing. Local flaps are often not available, or are insufficient to cover these defects, and limbs are frequently amputated, although they could possibly be salvaged by free tissue transplantation. Although there is a growing evidence that free tissue transfer may be feasible in these patients with otherwise doomed extremities, previous studies have mostly focused on short-term flap survival, but not long-term ambulatory status and independence. Therefore, we investigated the long-term results of limb salvage, ambulatory status, and social independence in patients with PAD who underwent free tissue transfer for chronic wounds of the lower extremities.In this study we retrospectively reviewed 38 patients who underwent free tissue transfer because of nontraumatic, chronic wounds of the lower extremities at our institution. All patients suffered from a nontraumatic occlusion of at least one major lower leg artery verified by angiography. After a mean time period of 34 months we assessed flap survival and limb preservation as well as pre- and postoperative ambulatory status and social independence. A subgroup of 14 patients with a "single-vessel-leg" was evaluated separately.It was observed that anterolateral thigh and latissimus dorsi musculocutaneous flaps were most often used to cover the defects. Overall 29 out of the 38 flaps healed completely (9 flap failures) and 34 extremities were salvaged, including 12 out of 14 single-vessel-legs. One patient had to be amputated despite a vital free flap because of persistent calcaneal osteomyelitis. After failure of free tissue transfer, six extremities could still be salvaged by secondary procedures (two secondary free flaps, two local flaps, and two skin grafts). Total 22 out of 34 patients with salvaged limbs maintained or improved their ambulatory status. In the amputee group, two patients remained on their preoperative level of mobility, while two declined. All patients with amputated limbs required assistance in activities of daily living while this was only true for 4 out of the 34 remaining patients.It was concluded that free tissue transfer is a valid option for salvaging lower extremities in patients with PAD. Long-term limb salvage can be achieved in a high percentage of cases, which allows the patients to ambulate freely and remain socially independent.

Cone-beam computed tomography in the treatment of distal radius fractures / Digitale Volumentomografie bei der Behandlung von Radiusfrakturen.

Cone-beam computed tomography (CBCT) is a relatively new imaging technique in hand surgery. Being the most common fractures in adults, distal radius fractures are of special importance not only to hand surgeons. The quantity alone calls for fast, efficient and reliable diagnostic procedures. Surgical techniques and possibilities are progressing, especially regarding intra-articular fracture patterns. The demand for exact anatomic reduction is high. There is an overall consensus regarding the indication for preoperative three-dimensional imaging and it is frequently used. Typically, it is obtained by multi-detector computed tomography (MDCT). Postoperative diagnostic procedures are usually limited to plain x-rays. Commonly accepted recommendations regarding postoperative 3D imaging are not yet established. There is a lack of relevant literature. In case of an indication for a postoperative CT scan, it is generally also obtained by MDCT. CBCT for the wrist is not widely used as yet. This review focuses on the potential role of CBCT in the perioperative management of distal radius fractures. CBCT allows for high-resolution imaging with a potentially lower radiation dose compared with MDCT, both with and without implants. It is easily available and can be operated independently, thus being time-efficient and making daily practice easier. Due to its many advantages, CBCT is a recommendable alternative to MDCT in the perioperative management of distal radius fractures.

State of the art review: The management of chronic vascular disorders in the hand and upper limb.

This review article summarizes the basic principles of vascular anatomy, physiology, diagnostic work-up and treatment for patients with nontraumatic upper extremity vascular disorders. Vascular disorders can be considered vasospastic or occlusive. The most commonly encountered vasospastic condition is Raynaud's Phenomenon secondary to scleroderma. While historically this has been managed medically with vasodilators, more advanced cases can benefit from surgical treatment to improve blood flow and minimize tissue loss, with compelling evidence that earlier surgical intervention can modify disease process and should be considered. Occlusive disease can present as aneurysm or thrombosis and often requires surgical treatment with resection of the occluded segment with or without vascular reconstruction. In advanced atherosclerotic disease or end stage ischemia, arterialization of the venous system can be considered to avoid more proximal amputations.

[WALANT - Wide Awake Local Anaesthesia No Tourniquet: Complications in elective and acute traumatological Hand Surgery Procedures]. / WALANT ­ Wide Awake Local Anaesthesia No Tourniquet: Komplikationen bei elektiven und akut-traumatologischen handchirurgischen Eingriffen.

INTRODUCTION: The WALANT (Wide Awake Local Anaesthesia No Tourniquet) technique has rapidly gained popularity. The advantages are often described, whereas information about complications is rare. Therefore, we followed up on our own patients regarding complications.Patients and Method Between January 2013 und June 2017, the complications experienced by one single surgeon were evaluated. The study included all elective (n = 195) and acute (n = 90) surgical procedures performed in WALANT. Minimum age of the patients was 18 years. All patients received Articaine 1 % and Suprarenine (1:200.000). Different volumes were injected with a minimum delay to surgery of 30 minutes. Complications were identified retrospectively by evaluation of patient files and a survey via telephone using a standardised questionnaire. Mean follow-up was 73 weeks. RESULTS: In 285 patients, there were 13 (4.6 %) complications. After injection of 16 ml of Articaine/Suprarenine, one patient had coronary symptoms, which ceased when two puffs of nitroglycerin spray were given. In one patient with a neurovascular injury in the palm, a bloodless field could not be obtained. A short tourniquet time was necessary for exploration. In one patient undergoing flexor tendon tenolysis, there was a need to convert to general anaesthesia with tourniquet because there was insufficient vasoconstriction due to marked scar tissue. One patient had an erythema around the injection site for a prolonged time, two had extensive erythema on the dorsum of the hand and seven patients reported swelling of the hand that lasted more than one week. SUMMARY: The WALANT method is safe. Perioperative complications are rare. Nevertheless, there are some disadvantages that should be considered.Vascular injuries, especially in fingers, are to be monitored closely regarding perfusion, and the off-label use should be remembered. Also, caution should be exercised in patients with cardiac disease. Larger injuries may need a short tourniquet time. Tissue that was operated on before does not always seem to be suitable for the technique as diffusion may be compromised. In rare cases, patients may suffer from prolonged erythema or swelling. Generally, patients should be evaluated for suitability to an operation in local anaesthesia.

Major traumatic amputations and replantations of the upper extremity in Germany - National quality reports 2014-2018.

The treatment of traumatic major upper limb amputation is complex and of great urgency. Loss of time often represents a majorrestriction for replantation. Thus, logistical and infrastructural developments, such as the expansion of specialised hand trauma centres, are crucial for optimizing delivery of care. Surveillance represents the fundament for a proper, demand-adapted implementation of such therapeutical improvements. However, a comprehensive database for surveillance of these injuries does currently not exist in Germany or Europe. In this study quality reports of German hospitals from 2014 to 2018 were screened retrospectively for traumatic major upper extremity amputations and replantations. A total of 329 amputations and 87 replantations were recorded, accounting for an overall replantation rate (RR) of 26%. Most of the injuries affected the level of the wrist and forearm. Treatment of these injuries experienced an increasing centralisation to medical teaching facilities, which accounted for higher RRs compared with non-teaching facilities. The cumulatively most populous federal states handled most of the amputation injures in this five-year study period. Ratio calculations on the basis of population counts, however, revealed great discrepancies to these results, with Hamburg, Rhineland-Palatinate and Saarland accounting for the highest per capita incidences. In 2018 Germany was provided with 46 specialised hand trauma and replantation centres, which performed 45% of the replantations in that year, revealing a RR of 17%, compared to an overall RR of 14% in that year. Nevertheless, there might be potential for improvement in the geographical distribution of these specialised centres. The provision of highly specialised therapy in highly specialised centres for highly complex injuries is a future challenge in replantation surgery. This data is contributing to logistical improvements for a need-adapted expansion of these specialised hand trauma centres. The study demonstrates an approach of a standardised and comprehensive injury surveillance program based on national quality reports, while underlining the importance of such a national or rather European database for optimisations in medical care. Level of evidence IV.

Relevance of the Scaphoid Shift Test for the Investigation of Scapholunate Ligament Injuries.

Background: Although it is part of the common clinical examination of scapholunate ligament pathologies, there are only little data on the diagnostic value of the scaphoid shift test. The aim of this study was to evaluate the scaphoid shift test in a large cohort of patients. Materials and Methods: We retrospectively analysed 447 patients who underwent the scaphoid shift test and wrist arthroscopy because of various suspected injuries of the wrist, correlating the results of clinical examination with data obtained during the wrist arthroscopy. Sensitivity, specificity, and positive and negative predictive values were calculated and evaluated. Results: The sensitivity of the scaphoid shift test was low (0.50) when examining the whole cohort. In a subgroup of patients specifically referred for suspected scapholunate ligament injury, the sensitivity was higher (0.61), but the specificity was low (0.62). In detecting more serious lesions (Geissler 3 + 4), the scaphoid shift test demonstrated higher sensitivity (0.66). Conclusions: An isolated scaphoid shift test may only be of limited value in the diagnosis of scapholunate ligament lesions and should, therefore, be viewed as a useful tool for a preliminary assessment, but a negative test should not prevent the surgeon from indicating a more extensive diagnostic workup.

The significance of conventional radiographic parameters in the diagnosis of scapholunate ligament lesions.

OBJECTIVE: Although in widespread clinical use, evidence of the diagnostic accuracy of radiographic parameters for the diagnosis of scapholunate ligament injuries is scarce. The objective of this study was to evaluate the scapholunate (SL) angle, radiolunate (RL) angle and SL gap as diagnostic parameters for these lesions. METHODS: Eight hundred forty nine patients, who underwent wrist arthroscopy at our institution because of wrist pain were included in a retrospective analysis. In all patients the SL angle, RL angle and SL gap were measured on preoperative radiographs. These parameters were correlated with the actual finding of the SL ligament during arthroscopy. Optimal test thresholds were calculated as well as sensitivity, specificity and the likelihood ratios of each parameter. RESULTS: All three parameters proved useful in statistical analysis. The optimal cut-off points for diagnosing lesions of the SL ligament were calculated as 62.5° for the SL angle, 12.5° for the RL angle and 2.5 mm for the SL gap. SL angles had the greatest specificity (0.93). CONCLUSIONS: We were able to validate plain radiographs as a reliable tool in the work-up of patients with suspected SL ligament injuries. However, wrist arthroscopy remains the gold standard in diagnosing and treating these lesions.

Reconstructive treatment of soft tissue sarcoma of the upper extremity.

Limb-sparing surgery is currently the cornerstone of treatment for most patients with soft-tissue sarcoma of the upper extremity. To achieve the best outcome, the reconstructive surgeon must be part of a multidisciplinary team and is required to have a thorough understanding of the whole treatment concept. This article provides an update for the current surgical management of patients with soft tissue sarcoma of the upper extremity. Relevant nonsurgical aspects are also highlighted.

Revitalization of cortical bone allograft by application of vascularized scaffolds seeded with osteogenic induced adipose tissue derived stem cells in a rabbit model.

BACKGROUND: Adipogenous tissue derived stem cells (ASC) are available in abundance in the human body and can differentiate in the presence of lineage-specific induction factors, for example, in myogenic, adipogenic, chondrogenic and osteogenic cells. The aim of this study was to evaluate the impact of osteogenic induced ASC's (O-ASC) on revascularization and cellular repopulation of avital cortical bone employing a vascularized bovine scaffold. METHODS: An inguinal arterio-venous bundle was dissected in the groin of female white New Zealand rabbits (n = 6) and placed centrally inside an O-ASC seeded scaffold via a central drill hole. In the same surgical session this construct was placed into a segment of avital cortical bone allograft from a donor rabbit. Unseeded scaffolds that were implanted and treated in the same fashion served as controls (n = 6). In order to prevent external revascularization, all constructs were wrapped in silicon foil and finally implanted in the rabbits' groin. Three months later, the constructs were explanted and investigated for vascularization of (a) the scaffold (b) the surrounding bone allograft. Histological stainings to determine cell growth, cellular repopulation of the scaffold and the cortical bone matrix, as well as inflammatory parameters were carried out. RESULTS: O-ASC seeded scaffolds showed a significant increase in new vessel formation in the scaffold as well as in the bone allograft compared to unseeded scaffolds. Furthermore, new vital osteocytes as a sign of cellular repopulation inside the bone allograft were found only in the treatment group. Vital chondrocytes were only found in the O-ASC seeded scaffolds as well. CONCLUSION: The presence of O-ASC significantly induce neo-vascularization and osteocytic repopulation of previously avital bone allograft as opposed to unseeded scaffolds in a rabbit model. Hence, this model might be of relevant value for future bone tissue engineering research and for re-vitalizing marginally nourished bone such as in avascular bone necrosis.